CA1153491A - Abrasion-resistant coating composition - Google Patents
Abrasion-resistant coating compositionInfo
- Publication number
- CA1153491A CA1153491A CA000345431A CA345431A CA1153491A CA 1153491 A CA1153491 A CA 1153491A CA 000345431 A CA000345431 A CA 000345431A CA 345431 A CA345431 A CA 345431A CA 1153491 A CA1153491 A CA 1153491A
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- Canada
- Prior art keywords
- composition
- pentaerythritol
- substrate
- product
- polyacrylate
- Prior art date
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F251/00—Macromolecular compounds obtained by polymerising monomers on to polysaccharides or derivatives thereof
- C08F251/02—Macromolecular compounds obtained by polymerising monomers on to polysaccharides or derivatives thereof on to cellulose or derivatives thereof
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- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Health & Medical Sciences (AREA)
- Paints Or Removers (AREA)
- Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)
- Application Of Or Painting With Fluid Materials (AREA)
- Manufacture Of Macromolecular Shaped Articles (AREA)
- Lubricants (AREA)
- Polymerisation Methods In General (AREA)
- Sliding-Contact Bearings (AREA)
- Coating Of Shaped Articles Made Of Macromolecular Substances (AREA)
- Laminated Bodies (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
Actinic radiation curable coating compositions are pro-vided applicable to many substrates comprising a penta-erythritol-based polyacrylate or polymethacrylate such as pentaerythritol tetraacrylate, a cellulose ester such as cell-ulose acetate butyrate and a photoinitiator. The compounds are preferably applied to the substrate by spraying a solution of the composition in one or more solvents selected from the group consisting of lower alcohols and ester, ketones having from 3 to 7 carbon atoms and lower alkyl Cellosolves, and re-moving the solvents.
Upon curing in air the compositions form extremely abra-sion resistant coatings on the substrate and are also char-acterized by being scratch resistant and resistant to attack by chemical and organic solvents.
Actinic radiation curable coating compositions are pro-vided applicable to many substrates comprising a penta-erythritol-based polyacrylate or polymethacrylate such as pentaerythritol tetraacrylate, a cellulose ester such as cell-ulose acetate butyrate and a photoinitiator. The compounds are preferably applied to the substrate by spraying a solution of the composition in one or more solvents selected from the group consisting of lower alcohols and ester, ketones having from 3 to 7 carbon atoms and lower alkyl Cellosolves, and re-moving the solvents.
Upon curing in air the compositions form extremely abra-sion resistant coatings on the substrate and are also char-acterized by being scratch resistant and resistant to attack by chemical and organic solvents.
Description
3~
BAC~GROUND OF THE INVENTION
This invention relates to radiation curable coating compositions which when cured form highly abrasion resistant coatings for most any substrate.
In the past, many curable or crosslinkable compositions have been developed in the art for use as coatings for clear plastics and the like which when cured offer varying degrees of abrasion and solvent resistance. Among such compositions are fluorocarbon-vinyl ether copolymers crosslinked with polysilicic acid, melamine-formaldehyde coatings, polyurethanes, polysiloxanes, polyalkyls, polyallyldicarbonates, and polyfunctional acrylics.
Such coatings have been applied to a wide variety of polymeric substrates including acrylic sheeting, polycarbonates, polyesters and the like. These compositions are generally applied to the substrate by any known method such as dipping, brushing or spraying and are cured at either high temperature or at low temperature in the presence of a catalyst. Ultra-violet curable coatings based on unsaturated polyester resins, including polyacrylics, and containing a photoinitiator have also been described in the art.
The present invention deals with radiation curable coating compositions containing a specific class of polyacry-lates and cellulos esters which can be applied to a variety of substrates. The precured coatings are dust-free, level out extremely well on the substrates and are stable against air inhibition of cure such that they can be cured in air hours after application to the substrate. On curing, coatings are formed exhibiting extremely high abrasion resistance, flex-ibility, weatherability and resistance to thermal stress cracking. Such coatings are additionally scratch resistant and are not attacked by chemical or organic solvents.
*~
~, ~ 39~
SUMMARY OF ~E INVENTION
In one embodiment of the present invention a coating composition curable by actinic radiation is provided which can be applied to most any substrate and when cured forms an extremely abrasion-resistant coating on the s~bstrate.
The curable composition comprises a pentaerythritol-10 based polyacrylate or polymethacrylate, a cellulose ester and a photoinitiator which can be applied to the subs~rate by any means known in the art such as by brushing, dipping, spraying or by roller, gravure, spin or flow coating techniques.
Spraying is particularly preferred. Solvents such as lower 15 alcohols, lower acetates, ketones and ethylenegylcol alkyl ethers may also be added to the composition to facilitate mix-ing of the components and to allow efficient and uniform application of the composition to the substrateO
In another embodiment of this invention a method of 20 forming an abrasion resistant coating on a substrate is pro-vided comprising applying the above composition to the sub-strate to form a coating, removing any solvents rom the com-position by evaporation and exposing the coating to ultra-violet radiation to effect curing thereof. Post-curing of the 25 coating at elevated temperatures may be conducted to further enhance abrasion resistance.
In other embodiments of the invention a composition comprising the cured product of the above curable composition and a substrate having a coating o~ the curable composition 30 and ~he cured product of the curable composition are also pro-vided.
DETAILED DESCRIPTION OF THE PREFERRED EMBODI~ENTS
The pentaerythritol-based polyacrylates and poly-methacrylates of the curable compositions of this invention include polyacrylates and polymethacrylatesof pentaerythritol such as the tri- and tetra-acrylates and methacrylates of pentaerythritol, polyacrylates and methacrylates of di- and 40 tri-pentaerythritol~ such as dipentaerythritol penta- and . . .
.
;i3~
hexa~acrylate and dipentaerythritol penta- and hexa-metha-crylate and tripentaerythritol octa-acrylate and methacrylate as well as mixtures of the above polyacrylates and polymeth-acrylates. Pentaerythritol tetraacrylate is particularly preerred due to its high performance in imparting abrasion resistance to the final, cured composition.
The cellulose esters of this invention comprise the 10 reaction product of cellulose with at least one organic carbo-xylic acid having ~rom about 2 to 4 carbon atoms or nitric acid. The preferred cellulose esters are cellulose acetate butyrates containing on the average from about 15% to 50~
butyrl groups, from about 1% to 30% acetyl groups and from 15 about 1~ to 5% hydroxyl groups and preferably having a vis-cosity in Poises of from about 50 to 200 at 25C. in a solution comprising 20 wt. % cellulose ester, 72 wt. % acetone and 8 wt. % ethyl alcohol. Particularly preferred is a cellu-lose acetate butyrate containing on the avera~e 37% butyryl 20 groups, 13~ acetyl groups and 2% hydroxyl groups and having a viscosity in Poises of from about 64 to 124 at 25C. in the ; above described solution. Nitrocellulose may also be employed as the cellulose ester.
A photoinitiator is added to the composition to 25 initiate crosslinking or curing upon irradiation. Such photo-initiators are well known in the art and include such com-pounds as benzoin, benzoin methylether, diphenyl disulfide, dibenzyl disulfide, benzil, benzophenone, xanthane, acetophe-none, anthraquinone, Michler's ketone and the like. A prefer-30 red photoinitiator is alpha-chloroacetyldiphenyloxide. An accelerator such as a tertiary amine may also be added.
It has also been found ~hat small amounts of a per oxide such as benzoyl peroxide may act as a photoinitiator by initiating crosslinking or curing of the compositions. Such 35 peroxide has the added advantage that it can be used in smaller amounts than the photoinitiators described above and does not tend to discolor or yellow the cured coatings. A
combination of photoinitiators may be employed in some cases.
The compositions of the present invention may be 40 applied to the substrate in any conventional manner such as ~539.`~
spraying, dippi~g, brushing or by roller, gravure, spin orflow coating techniques. Spraying is preferred since it allows uniform application of thin cured coatings to the sub-strate, i.e. on the order of 0.1 to 1.5 mils.
In order to facilitate mixing of the elements of the composition and to allow for efficient spraying, one or more solvents may be employed in the composition, which include 10 lower alcohols having from 1 to 4 carbon atoms such as pro-panol and butanol; lower alkyl acetates having from 4 to 6 carbon atoms such as propyl and butyl acetate; alkyl ketones having from 3 to 7 carbon atoms such as methyl isoamyl ketone;
and ethylene glycol lower alkyl ethers ~Cellosolves) such as 15 methyl and ethyl Cellosolve. Organic solvents other than those named above may also be employed provided they are good solvents for the pentaerythritol-based polyacrylate or poly-methacrylate and cellulose ester and do not attack ~he sub-strate on which the composition is coated. For example, a 20 quantity of an aromatic solvent such as xylol may also be employed with the above-described solvents to dissolve certain pentaerythritol-based polymethacrylates such as penta-erythritol tetramethacrylate.
The composition may also contain small amounts of 25 flatting agents to lower the gloss of the coating and sili-cones to increase the ~lowability of ~he compositions.
The substrates which can be coated with the curable compositions of this invention are numerous and include any material to which the composition will adhere and coat such as 30 wood, ~lass, metal, rubber and plastics. The compositions are particularly useful for coating polymeric substrates such as polycarbonates, polyvinyls including rigid polyvinyl chloride sheet substrate and substrates comprised of copolymers of polyvinyl chloride and polyvinylacetate, polyacrylics and 35 polyesters. The compositions may be used for the coating of vinyl and polycarbonate substrates used to manufacture low reflection filters for cathode ray tubes (C.R.T~'s~ and for acrylic substrates used as front panels for electronic equip-ment.
Upon curing in air by actinic radiation, the p~esent Trademar]c ~s~
compositions form a highl~ abrasion resistant coating even on contoured surfaces which have a lower point of contact with abrasive objects moved along its surface. Tesks conducted on cured compositions o~ this invention coated on polymeric sub-strates have proved their extremely high resistance to steel wool abrasion and Taber Abrasion. The compositions are also resistant to scratching as shown by tests with a weighted 1~ stylus according to the BTL Balanced Beam Mar Test (ASTM
Method D 2197). The cured compositions o~ this invention are also characterized by their high resistance to organic sol-vents, acids and bases, to thermal stress cracking and are flexible and weatherable. Moreover, clear, cured coatings 15 containing flatting agents made according to the invention are also characterized by their low gloss and high resolution mak-ing them ideally suitable for low re~lection filters for C.R.T.'s. Clear coatings of this invention may also be ap-plied to clear plastic lenses, meter faces, formed plastic 20 windshields and flat plastic windows used for optical applica-tions to provide abrasion and scratch resistance.
- The curable compositions o~ this invention are pre-pared by first forming a heavy solution of the cellulose ester in one or more solvents, i.e. about 10 to 15% of cellulose 25 ester by weight. A portion of this solution and the penta-erythritol-based polyacrylate or methacrylate is added to a further solvent system to provide a coating composition which, if applied separately to a substrate and dried, would form a slightly tacky but dust free coating on the substrate. For 30 example such a ¢oating composition can be formed using penta-erythritol tetraacrylate and cellulose acetate butyrate by adding a portion of a heavy solution of cellulose acetate butyra~te in propyl acetate and propar,ol and pentaerythritol tetraacrylate to a further solvent system ~omprising propyl 35 acetate, propyl alcohol and methyl Cellosolve to form a solu-tion containing tne ~ollowing weight percentages of each com~
ponent:
1~53~
~ .
.
pentaerythritol tetraacrylate 30 wt. %
cellulose acetate butyrate3 wt. %
S propyl acetate 34 wt. %
propyl alcohol 28 wt. %
me~hyl cellosolve 5 wt. %
100 wt. %
10 This composition provides a weight ratio of pentaerythritol tetraacrylate to cellulose acetate butyrate of about 10 to 1.
~n the case o pentaerythritol-based polymethacrylates such as pentaerythritol tetramethacrylate, an aroma~ic solvent such as xylol may also be employed in forming the coating composi-15 tion.
The weight ratio of pentaerythritol-based polyacry-late or methacrylate to cellulose ester is an important factor in determining the abrasion resistance o the finally cured coatings. Coatings containing too low a ratio of penta-~0 erythritol-based polyacrylate or me~hacrylate to cellulose ester i.e., excessive cellulose ester, tend to lose abrasion resistance in the cured state because of the lack of suf-ficient amounts of crosslinked polyacrylate or methacrylate.
Coatings containing too high a ratio, i.e. insuff icient cell-25 ulose ester, tend to lose abrasion resistance in the curedstate because of ~he non-uniform or irregular distribution of the polyacrylate or methacrylate and the inability of the cellulose ester to prevent air inhibition of the polyacrylate or methacrylate cure which will be discussed further below.
30 Coatings containing no cellulose ester for example, are not appreciably abrasion resistant, especially as thin films.
Therefore there exists a set of ratio ranges ~or each type of polyacrylate or polymethacrylate and cellulose ester above and below which abrasion resistance in the finally cured coat-35 ings may decrease significantly or completely.
In the case of composi~ions containing penta-erythritol-based polyacrylates or methacryla~es and the preferred cellulose acetate butyrates, this ratio should be between about 6 to 1 and about 100 to 1 to 40 achieve abrasion resistance in ~he cured coatings. High abra-~ ~ 3 sion resistance is achieved at ratios o~ from about 8 to 1 to about 20 to 1 and optimum abrasion resistance is achieved using a ratio of about 10 to 1. At ratios greater than about 20 to 1 thermal stress cracking begins to occur in the cured composition if the temperat~re is elevated during curing.
This also depends on the type of s~bstrate coated and the film thickness of the coating. Below ratios of about 5 to 1 and 10 above ratios of about 100 to 1, abrasion resistance decreases significantly. Although it is important that the ratio of pentaerythritol-based polyacrylate or methacrylate to cellu-lose ester be maintained in the above ranges, the solvent com-positions and amounts may be altered to provide pre-cured 15 coatings or varying consistency as required or desired by those skilled in the art.
Next, a clear sprayable solution is prepared by dis-solving a portion of the above coating composition in one or more solvents which are mutually compatible and which will not 20 attack the substrate onto which the composition is to be applied. It has been found that a sprayable solution compris-ing about 50~ by weigh~ of the above coating composition in equal parts by weight of butyl acetate, butanol, methyl iso-amyl ketone, and methyl Cellosolve is useful and has the 25 advantage that such a mixture will not attack most polymeric substrates including polycarbonate substrates. However, such solvents may be varied by those skilled in the art depending on the substrate or the method of application. To this solu-tion is added the photoinitiator in a ratio of about 1 p.b.w.
30 of photoinitiator to 150 p.b.w. of sprayable solution. The amount o~ photoinitiator based on the amount of pentae~ythri-tol tetraacrylate in the solution is from about 2 to 5 weigh~
per cent but may be varied by those skilled in the art. I a peroxide such as benzoyl peroxide is employed as a photo-35 initiator the amount used is generally about 1 weight percent.
The sprayable solution is then preferably sprayed onthe substrate using a conventional low pressure spray gun at a wet film thickness of from about 0.9 to 3.0 mils. Thereafter, the solvents are allowed to evaporate either at room temper-40 ature for about 10 minutes or at 100 F. to 120F. for about 2 S3~
minutes. Coatings so ~pplied level out well on the substrate,that is form a smooth contiguous film The dry coating is S essentially non-tacky and dust-free. Finally, the dry coating is exposed to actinic radiation to provide a cured coating of rom about 0.1 to about 1.5 mil. in dry ilm thickness.
Actinic radiation as used herein is electromagnetic radiation having a wavelength of 700 nanometers or less which 10 is capable of producing, either directly or indirectly, free radicals in the photoinitiator which in turn cause cross~link-ing addition polymerization of the compositions. The most commonly used form of actinic light and the preferred form herein is ultraviolet light, that is, electromagnetic radia-15 tion having a wavelength in the range of from about 180 nano~meters to about 460 nanometers, although actinic light of greater or shorter wavelengths may also be used. Generally, exposures of from about 1 to 5 sec. are sufficient to effect curing of pentaerythritol-based polyacrylate compositions 2Q while somewhat longer exposure times are required for the pentaerythritol-based polymethacrylate compositions.
Any suitable source which emits ultraviolet light may be used in curing the compositions of this invention.
Particularly preferred are ultraviolet emitting lamps of the 25 medium mercury vapor type having a power rating o 200 watts/inch.
It has been found that the use of cellulose acetate butyrate as the cellulose esterj particularly the preferred cellulose acetate butyrates described above, solve many prob-30 lems associated with coating substrates with thin films,`ie.on the order of 2 to 20 microns~ of compositions comprised of radiation curable pentaerythritol based polyacrylates or methacrylates. Pentaerythritol-based polyacrylates such as pentaerythritol tetraacryla~e are low viscosity liquids which 3~ when deposited on a substrate do not form uniform coatings, nor do they level out well on the substrate. Pentaerythritol-based polymethacrylates such as pentaerythritoi tetrameth-acrylate are soft, tacky solids and tend to crystallize when coated in solution on the substrate aEter solvent removal.
40 Moreover, coatings of pentaerythritol-based polyacrylates are _ .. . . .... .. . . . . . . . . .. ., .. _ _ .. _ _ , .. . ~ ..
~S3~9~
1 ~9_ wet, tacky and dust attractive. It is also necessary to cure pentaerythritol-based polyacrylate or methacrylate films in an inert atmosphere since the presence of air inhibits their cure. The exclusion of air to enable curing of the poly-acrylates or methacrylates is impractical for most commercial coating applications and costly as well. Cured coatings of such polyacrylates are characterized by being brittle, inflex-10 ible and subject to cracking in response to hea~ or stress.
The use of a cellulose ester such as the celluloseacetate butyrates described above increases the viscosity of the pentaerythritol-based polyacrylate thereby allowing the coating to be uniformly deposited and to level out well on the lS substrate. Cellulose acetate butyrate inhibits crystalliza-tion of the pentaerythritol-based polymethacrylates.
Secondly, thin films on the order of 2 to 20 microns contain-ing the ester can be deposited on the substrate and dry quickly to a substan~ially dust free coating. Thirdly, and 20 probably most importantly, is the ability of the cellulose ester to substa`ntially eliminate the air inhibition of the polyacrylate or methacrylate cure. Fourthly, cured films con-taining the cellulose ester are characterized by being thermal stress crack resistant, flexible, and resistant to weathering.
Thus, compositions according to the present inven-tion can be applied as thin films which readily flow and level out on the substrate, dry rapidly to a dust-free and stable condition such that the films can be cured either immediately or hours later in a few seconds without concern for the elimi-30 nation of air at any time and form 1exible, thermal stress crack-resistant, weatherable, and highly abrasion resistant coatings.
It has also been foundythat by post-curing the irra diated coating at temperatu~es of from about 100F. to 200F.
3S at from 2 to 5 hrs., abrasion resistance is even further enhanced.
In order to more completely describe the presen~
invention, the following Examples are given:
~53~
_ _ This example illustrates the preparation, applica tion to a substrate and curing of the preferred composition of this invention~ The cellulose acetate butyrate employed in this Example had on the average 37% butyryl groups, 13% acetyl groups and 2% hydroxyl groups and a viscosity in Poises of 10 between about 64 and 124 at 25C. in a solution comprising 20 wt. ~ cellulose acetate butyrate, 72 w~. % acetone and 8 wt. % ethyl alcohol.
A stock solution containing 14.3 wt. ~ of cellulose acetate butyrate in propyl acetate and propanol was first pre-15 pared by dissolving 50 parts by weight (p.b.w.) of the cellu-lose acetate butyrate in a solvent mixture of 200 p.b.w. of propyl acetate and 100 p.b.w. of propanol.
A coating formulation was prepared by dissolving a portion of the so-formed stock solution and pentaerythritol 20 tetraacrylate in a further solvent system as shown below.
Additive p.b.w.
Stock Solution 126 Pentaerythritol Tetraacrylate180 25 Solvents Propyl acetate 132 Propanol 132 Methyl Cellosolve 30 , 600 3a This coating formulation contained the ~ollowing total weight percentages of each component.
Total Component wt. %
Pentaerythritol Tetraacrylate30 35 Cellulose Acetate Butyrate 3 Propyl Acetate 34 Propyl Alcohol 28 Methyl Cellosolve 5 Total 100 ~i3~
Such a coating formulation, if separately applied to a substrate and dried to remove solven~s, leaves a slightly tacky and dust free film on the substrate.
Next, a sprayable, clear solution was formed by add-ing a portion of the above coating ~ormulation to a spray-able solvent system as set forth below.
1~ Additive Coating Formulation 356 Solvents Butyl Acetate 100 Butanol 100 Methyl Isoamyl Ketone 100 Methyl Cellosolve 100 This sprayable solution contained the following total weight percentages o~ each component.
Total Component wt. %
Pentaerythritol Tetraacrylate 14.2 Cellulose Acetate Butyrate1.4 Propyl Acetate 16.0 Propyl Alcohol 13.2 Methyl Cellosolve 15.6 Butanol 13.2 3~ Butyl Acetate 13.2 ~ethyl Isoamyl Ketone 13.2 100.0 To this solution was added 0.8 p.b.w~ of alpha 35 chloroacetyldiphenyloxide to form a UV curable coating compo-sition. This curable composition was then sprayed under low prassure on a polyvinyl chloride substrate (TENNECO CHEM. CO.) at a wet film thickness of about 0.9 mil using a DeVilbiss-TYPE EGA spray gun and allowed to dry in air at room tempera-40 ture. The composition leveled out well on the substrate.
~3~
Upon drying the film thickness was about 0.3 mil. and was dust-free. The polyvinylchloride substrate coated with the curable mixture was then irradiated with high intensity UV
light for about 3 sec. ~o e~fect curing. It was ~ound that the curable composition could be le~t on the substrate ~or hou~s before UV curing without air inhibition of cure.
This Example demonstrates the resistance to steel wool abrasion of a cured composition according to this inven-tion on a polymeric substrate and its comparison to other 15 coated substrates and an uncoated substrate.
In this Example, a sample of the cured composition of Example 1 on polyvinyl chloride (Ex. 1 CO~TING) was sub-jected to abrasion by rubbing with a ~ inch block of aluminum covered with 1/8 inch thick 0000 steel wool under a 1000 gm.
20 load. After each double rub ~1 back and ~orth stroke) the coating was observed for visible scratches. No more than 1000 double rubs were made. As comparison samples, the following were also tested:
A polyvinyl substrate coated with a vinyl urethane 25 cQmposition (VINYL URETHANE);
A vinyl substrate coated with a composition compris-ing a vinyl chloride - vinyl acetate - vinyl alcohol terpoly-mer and melamine (VI~YL MELAMINE);
An acrylic substrate coated with a nitrocellulose-30 aliphatic urethane coating (ALIPHATIC URETHAN~); and An uncoated polyvinyl chloride substrate ~UNCOATEDSUBSTRATE).
~ Table 1 below summarizes the resullts of all test.
~ ~ 3 Table 1 _ ____ _ _ .
Sample No. of Double Rubs Yisible Scratches ,_, .
Ex. 1 COATING 1000 None 10 VINYL URETHANE 2 Namerous VINYL MELAMINE 2 Numerous ALIP~A~IC URETHANE 3 Numerous 15 U~COATED SUBST~ATE 1 Nu~erous _ . . . _ As the table shows, the Example 1 COATI~G resisted scratching by the steel ~ool up to 1000 double rubs The re-maining samples did not endure more than`3 double rubs before 20 severe scratching doveloped. ~n addition, tl~e Example 1 COAT-ING was resistant to thermal stress cracking and flexible.
EX~M
In this Example, the samples of Example 2 were test-ed on a Taber Abrader described in ASTM D 1004-56. To sum-marize this procedure, each sample was mounted on a ~urntable and was abraded by a pair of abrasive wheels (CS 10) weighing 1000g each rotating in opposite direc~ions. The abrasive 30 wheels traveled on the sample about a horizontal axis displaced tangentially from the axis of rotation of the sample re~
sulting in a wearing action. The abrasion was de~ermined by the visual condition of each sample a~ter S0, 100 and 200 revolutions of the ~brader. The weight loss of each sample 35 was also determined after the test. Table 2 summarizes the results.
Table 2 . ___ __~ ~_ SAMPLE CONDIT~ON AFTER WEIGHq;
SAMPLE P~EVOLUT~ONS LOSS
Ex. 1 No No Slight None COATING Effect Effect Poli~h URETH~NE Abraded _ 2 mg.
VINYL
MEL~INE Abraded 2 mg.
ALIPHATIC J
URETRANE Abraded 3 mg.
UNCOATED
SUBSTRATE Abraded 3 mg.
20' As table 2 shows, hardly any abrasion of the EX.
COATING occurred even after 200 revolutions. The remaining samples, on the other hand, were all abraded after 50 revolu-tions as indicated by their visible condition and weight loss.
BAC~GROUND OF THE INVENTION
This invention relates to radiation curable coating compositions which when cured form highly abrasion resistant coatings for most any substrate.
In the past, many curable or crosslinkable compositions have been developed in the art for use as coatings for clear plastics and the like which when cured offer varying degrees of abrasion and solvent resistance. Among such compositions are fluorocarbon-vinyl ether copolymers crosslinked with polysilicic acid, melamine-formaldehyde coatings, polyurethanes, polysiloxanes, polyalkyls, polyallyldicarbonates, and polyfunctional acrylics.
Such coatings have been applied to a wide variety of polymeric substrates including acrylic sheeting, polycarbonates, polyesters and the like. These compositions are generally applied to the substrate by any known method such as dipping, brushing or spraying and are cured at either high temperature or at low temperature in the presence of a catalyst. Ultra-violet curable coatings based on unsaturated polyester resins, including polyacrylics, and containing a photoinitiator have also been described in the art.
The present invention deals with radiation curable coating compositions containing a specific class of polyacry-lates and cellulos esters which can be applied to a variety of substrates. The precured coatings are dust-free, level out extremely well on the substrates and are stable against air inhibition of cure such that they can be cured in air hours after application to the substrate. On curing, coatings are formed exhibiting extremely high abrasion resistance, flex-ibility, weatherability and resistance to thermal stress cracking. Such coatings are additionally scratch resistant and are not attacked by chemical or organic solvents.
*~
~, ~ 39~
SUMMARY OF ~E INVENTION
In one embodiment of the present invention a coating composition curable by actinic radiation is provided which can be applied to most any substrate and when cured forms an extremely abrasion-resistant coating on the s~bstrate.
The curable composition comprises a pentaerythritol-10 based polyacrylate or polymethacrylate, a cellulose ester and a photoinitiator which can be applied to the subs~rate by any means known in the art such as by brushing, dipping, spraying or by roller, gravure, spin or flow coating techniques.
Spraying is particularly preferred. Solvents such as lower 15 alcohols, lower acetates, ketones and ethylenegylcol alkyl ethers may also be added to the composition to facilitate mix-ing of the components and to allow efficient and uniform application of the composition to the substrateO
In another embodiment of this invention a method of 20 forming an abrasion resistant coating on a substrate is pro-vided comprising applying the above composition to the sub-strate to form a coating, removing any solvents rom the com-position by evaporation and exposing the coating to ultra-violet radiation to effect curing thereof. Post-curing of the 25 coating at elevated temperatures may be conducted to further enhance abrasion resistance.
In other embodiments of the invention a composition comprising the cured product of the above curable composition and a substrate having a coating o~ the curable composition 30 and ~he cured product of the curable composition are also pro-vided.
DETAILED DESCRIPTION OF THE PREFERRED EMBODI~ENTS
The pentaerythritol-based polyacrylates and poly-methacrylates of the curable compositions of this invention include polyacrylates and polymethacrylatesof pentaerythritol such as the tri- and tetra-acrylates and methacrylates of pentaerythritol, polyacrylates and methacrylates of di- and 40 tri-pentaerythritol~ such as dipentaerythritol penta- and . . .
.
;i3~
hexa~acrylate and dipentaerythritol penta- and hexa-metha-crylate and tripentaerythritol octa-acrylate and methacrylate as well as mixtures of the above polyacrylates and polymeth-acrylates. Pentaerythritol tetraacrylate is particularly preerred due to its high performance in imparting abrasion resistance to the final, cured composition.
The cellulose esters of this invention comprise the 10 reaction product of cellulose with at least one organic carbo-xylic acid having ~rom about 2 to 4 carbon atoms or nitric acid. The preferred cellulose esters are cellulose acetate butyrates containing on the average from about 15% to 50~
butyrl groups, from about 1% to 30% acetyl groups and from 15 about 1~ to 5% hydroxyl groups and preferably having a vis-cosity in Poises of from about 50 to 200 at 25C. in a solution comprising 20 wt. % cellulose ester, 72 wt. % acetone and 8 wt. % ethyl alcohol. Particularly preferred is a cellu-lose acetate butyrate containing on the avera~e 37% butyryl 20 groups, 13~ acetyl groups and 2% hydroxyl groups and having a viscosity in Poises of from about 64 to 124 at 25C. in the ; above described solution. Nitrocellulose may also be employed as the cellulose ester.
A photoinitiator is added to the composition to 25 initiate crosslinking or curing upon irradiation. Such photo-initiators are well known in the art and include such com-pounds as benzoin, benzoin methylether, diphenyl disulfide, dibenzyl disulfide, benzil, benzophenone, xanthane, acetophe-none, anthraquinone, Michler's ketone and the like. A prefer-30 red photoinitiator is alpha-chloroacetyldiphenyloxide. An accelerator such as a tertiary amine may also be added.
It has also been found ~hat small amounts of a per oxide such as benzoyl peroxide may act as a photoinitiator by initiating crosslinking or curing of the compositions. Such 35 peroxide has the added advantage that it can be used in smaller amounts than the photoinitiators described above and does not tend to discolor or yellow the cured coatings. A
combination of photoinitiators may be employed in some cases.
The compositions of the present invention may be 40 applied to the substrate in any conventional manner such as ~539.`~
spraying, dippi~g, brushing or by roller, gravure, spin orflow coating techniques. Spraying is preferred since it allows uniform application of thin cured coatings to the sub-strate, i.e. on the order of 0.1 to 1.5 mils.
In order to facilitate mixing of the elements of the composition and to allow for efficient spraying, one or more solvents may be employed in the composition, which include 10 lower alcohols having from 1 to 4 carbon atoms such as pro-panol and butanol; lower alkyl acetates having from 4 to 6 carbon atoms such as propyl and butyl acetate; alkyl ketones having from 3 to 7 carbon atoms such as methyl isoamyl ketone;
and ethylene glycol lower alkyl ethers ~Cellosolves) such as 15 methyl and ethyl Cellosolve. Organic solvents other than those named above may also be employed provided they are good solvents for the pentaerythritol-based polyacrylate or poly-methacrylate and cellulose ester and do not attack ~he sub-strate on which the composition is coated. For example, a 20 quantity of an aromatic solvent such as xylol may also be employed with the above-described solvents to dissolve certain pentaerythritol-based polymethacrylates such as penta-erythritol tetramethacrylate.
The composition may also contain small amounts of 25 flatting agents to lower the gloss of the coating and sili-cones to increase the ~lowability of ~he compositions.
The substrates which can be coated with the curable compositions of this invention are numerous and include any material to which the composition will adhere and coat such as 30 wood, ~lass, metal, rubber and plastics. The compositions are particularly useful for coating polymeric substrates such as polycarbonates, polyvinyls including rigid polyvinyl chloride sheet substrate and substrates comprised of copolymers of polyvinyl chloride and polyvinylacetate, polyacrylics and 35 polyesters. The compositions may be used for the coating of vinyl and polycarbonate substrates used to manufacture low reflection filters for cathode ray tubes (C.R.T~'s~ and for acrylic substrates used as front panels for electronic equip-ment.
Upon curing in air by actinic radiation, the p~esent Trademar]c ~s~
compositions form a highl~ abrasion resistant coating even on contoured surfaces which have a lower point of contact with abrasive objects moved along its surface. Tesks conducted on cured compositions o~ this invention coated on polymeric sub-strates have proved their extremely high resistance to steel wool abrasion and Taber Abrasion. The compositions are also resistant to scratching as shown by tests with a weighted 1~ stylus according to the BTL Balanced Beam Mar Test (ASTM
Method D 2197). The cured compositions o~ this invention are also characterized by their high resistance to organic sol-vents, acids and bases, to thermal stress cracking and are flexible and weatherable. Moreover, clear, cured coatings 15 containing flatting agents made according to the invention are also characterized by their low gloss and high resolution mak-ing them ideally suitable for low re~lection filters for C.R.T.'s. Clear coatings of this invention may also be ap-plied to clear plastic lenses, meter faces, formed plastic 20 windshields and flat plastic windows used for optical applica-tions to provide abrasion and scratch resistance.
- The curable compositions o~ this invention are pre-pared by first forming a heavy solution of the cellulose ester in one or more solvents, i.e. about 10 to 15% of cellulose 25 ester by weight. A portion of this solution and the penta-erythritol-based polyacrylate or methacrylate is added to a further solvent system to provide a coating composition which, if applied separately to a substrate and dried, would form a slightly tacky but dust free coating on the substrate. For 30 example such a ¢oating composition can be formed using penta-erythritol tetraacrylate and cellulose acetate butyrate by adding a portion of a heavy solution of cellulose acetate butyra~te in propyl acetate and propar,ol and pentaerythritol tetraacrylate to a further solvent system ~omprising propyl 35 acetate, propyl alcohol and methyl Cellosolve to form a solu-tion containing tne ~ollowing weight percentages of each com~
ponent:
1~53~
~ .
.
pentaerythritol tetraacrylate 30 wt. %
cellulose acetate butyrate3 wt. %
S propyl acetate 34 wt. %
propyl alcohol 28 wt. %
me~hyl cellosolve 5 wt. %
100 wt. %
10 This composition provides a weight ratio of pentaerythritol tetraacrylate to cellulose acetate butyrate of about 10 to 1.
~n the case o pentaerythritol-based polymethacrylates such as pentaerythritol tetramethacrylate, an aroma~ic solvent such as xylol may also be employed in forming the coating composi-15 tion.
The weight ratio of pentaerythritol-based polyacry-late or methacrylate to cellulose ester is an important factor in determining the abrasion resistance o the finally cured coatings. Coatings containing too low a ratio of penta-~0 erythritol-based polyacrylate or me~hacrylate to cellulose ester i.e., excessive cellulose ester, tend to lose abrasion resistance in the cured state because of the lack of suf-ficient amounts of crosslinked polyacrylate or methacrylate.
Coatings containing too high a ratio, i.e. insuff icient cell-25 ulose ester, tend to lose abrasion resistance in the curedstate because of ~he non-uniform or irregular distribution of the polyacrylate or methacrylate and the inability of the cellulose ester to prevent air inhibition of the polyacrylate or methacrylate cure which will be discussed further below.
30 Coatings containing no cellulose ester for example, are not appreciably abrasion resistant, especially as thin films.
Therefore there exists a set of ratio ranges ~or each type of polyacrylate or polymethacrylate and cellulose ester above and below which abrasion resistance in the finally cured coat-35 ings may decrease significantly or completely.
In the case of composi~ions containing penta-erythritol-based polyacrylates or methacryla~es and the preferred cellulose acetate butyrates, this ratio should be between about 6 to 1 and about 100 to 1 to 40 achieve abrasion resistance in ~he cured coatings. High abra-~ ~ 3 sion resistance is achieved at ratios o~ from about 8 to 1 to about 20 to 1 and optimum abrasion resistance is achieved using a ratio of about 10 to 1. At ratios greater than about 20 to 1 thermal stress cracking begins to occur in the cured composition if the temperat~re is elevated during curing.
This also depends on the type of s~bstrate coated and the film thickness of the coating. Below ratios of about 5 to 1 and 10 above ratios of about 100 to 1, abrasion resistance decreases significantly. Although it is important that the ratio of pentaerythritol-based polyacrylate or methacrylate to cellu-lose ester be maintained in the above ranges, the solvent com-positions and amounts may be altered to provide pre-cured 15 coatings or varying consistency as required or desired by those skilled in the art.
Next, a clear sprayable solution is prepared by dis-solving a portion of the above coating composition in one or more solvents which are mutually compatible and which will not 20 attack the substrate onto which the composition is to be applied. It has been found that a sprayable solution compris-ing about 50~ by weigh~ of the above coating composition in equal parts by weight of butyl acetate, butanol, methyl iso-amyl ketone, and methyl Cellosolve is useful and has the 25 advantage that such a mixture will not attack most polymeric substrates including polycarbonate substrates. However, such solvents may be varied by those skilled in the art depending on the substrate or the method of application. To this solu-tion is added the photoinitiator in a ratio of about 1 p.b.w.
30 of photoinitiator to 150 p.b.w. of sprayable solution. The amount o~ photoinitiator based on the amount of pentae~ythri-tol tetraacrylate in the solution is from about 2 to 5 weigh~
per cent but may be varied by those skilled in the art. I a peroxide such as benzoyl peroxide is employed as a photo-35 initiator the amount used is generally about 1 weight percent.
The sprayable solution is then preferably sprayed onthe substrate using a conventional low pressure spray gun at a wet film thickness of from about 0.9 to 3.0 mils. Thereafter, the solvents are allowed to evaporate either at room temper-40 ature for about 10 minutes or at 100 F. to 120F. for about 2 S3~
minutes. Coatings so ~pplied level out well on the substrate,that is form a smooth contiguous film The dry coating is S essentially non-tacky and dust-free. Finally, the dry coating is exposed to actinic radiation to provide a cured coating of rom about 0.1 to about 1.5 mil. in dry ilm thickness.
Actinic radiation as used herein is electromagnetic radiation having a wavelength of 700 nanometers or less which 10 is capable of producing, either directly or indirectly, free radicals in the photoinitiator which in turn cause cross~link-ing addition polymerization of the compositions. The most commonly used form of actinic light and the preferred form herein is ultraviolet light, that is, electromagnetic radia-15 tion having a wavelength in the range of from about 180 nano~meters to about 460 nanometers, although actinic light of greater or shorter wavelengths may also be used. Generally, exposures of from about 1 to 5 sec. are sufficient to effect curing of pentaerythritol-based polyacrylate compositions 2Q while somewhat longer exposure times are required for the pentaerythritol-based polymethacrylate compositions.
Any suitable source which emits ultraviolet light may be used in curing the compositions of this invention.
Particularly preferred are ultraviolet emitting lamps of the 25 medium mercury vapor type having a power rating o 200 watts/inch.
It has been found that the use of cellulose acetate butyrate as the cellulose esterj particularly the preferred cellulose acetate butyrates described above, solve many prob-30 lems associated with coating substrates with thin films,`ie.on the order of 2 to 20 microns~ of compositions comprised of radiation curable pentaerythritol based polyacrylates or methacrylates. Pentaerythritol-based polyacrylates such as pentaerythritol tetraacryla~e are low viscosity liquids which 3~ when deposited on a substrate do not form uniform coatings, nor do they level out well on the substrate. Pentaerythritol-based polymethacrylates such as pentaerythritoi tetrameth-acrylate are soft, tacky solids and tend to crystallize when coated in solution on the substrate aEter solvent removal.
40 Moreover, coatings of pentaerythritol-based polyacrylates are _ .. . . .... .. . . . . . . . . .. ., .. _ _ .. _ _ , .. . ~ ..
~S3~9~
1 ~9_ wet, tacky and dust attractive. It is also necessary to cure pentaerythritol-based polyacrylate or methacrylate films in an inert atmosphere since the presence of air inhibits their cure. The exclusion of air to enable curing of the poly-acrylates or methacrylates is impractical for most commercial coating applications and costly as well. Cured coatings of such polyacrylates are characterized by being brittle, inflex-10 ible and subject to cracking in response to hea~ or stress.
The use of a cellulose ester such as the celluloseacetate butyrates described above increases the viscosity of the pentaerythritol-based polyacrylate thereby allowing the coating to be uniformly deposited and to level out well on the lS substrate. Cellulose acetate butyrate inhibits crystalliza-tion of the pentaerythritol-based polymethacrylates.
Secondly, thin films on the order of 2 to 20 microns contain-ing the ester can be deposited on the substrate and dry quickly to a substan~ially dust free coating. Thirdly, and 20 probably most importantly, is the ability of the cellulose ester to substa`ntially eliminate the air inhibition of the polyacrylate or methacrylate cure. Fourthly, cured films con-taining the cellulose ester are characterized by being thermal stress crack resistant, flexible, and resistant to weathering.
Thus, compositions according to the present inven-tion can be applied as thin films which readily flow and level out on the substrate, dry rapidly to a dust-free and stable condition such that the films can be cured either immediately or hours later in a few seconds without concern for the elimi-30 nation of air at any time and form 1exible, thermal stress crack-resistant, weatherable, and highly abrasion resistant coatings.
It has also been foundythat by post-curing the irra diated coating at temperatu~es of from about 100F. to 200F.
3S at from 2 to 5 hrs., abrasion resistance is even further enhanced.
In order to more completely describe the presen~
invention, the following Examples are given:
~53~
_ _ This example illustrates the preparation, applica tion to a substrate and curing of the preferred composition of this invention~ The cellulose acetate butyrate employed in this Example had on the average 37% butyryl groups, 13% acetyl groups and 2% hydroxyl groups and a viscosity in Poises of 10 between about 64 and 124 at 25C. in a solution comprising 20 wt. ~ cellulose acetate butyrate, 72 w~. % acetone and 8 wt. % ethyl alcohol.
A stock solution containing 14.3 wt. ~ of cellulose acetate butyrate in propyl acetate and propanol was first pre-15 pared by dissolving 50 parts by weight (p.b.w.) of the cellu-lose acetate butyrate in a solvent mixture of 200 p.b.w. of propyl acetate and 100 p.b.w. of propanol.
A coating formulation was prepared by dissolving a portion of the so-formed stock solution and pentaerythritol 20 tetraacrylate in a further solvent system as shown below.
Additive p.b.w.
Stock Solution 126 Pentaerythritol Tetraacrylate180 25 Solvents Propyl acetate 132 Propanol 132 Methyl Cellosolve 30 , 600 3a This coating formulation contained the ~ollowing total weight percentages of each component.
Total Component wt. %
Pentaerythritol Tetraacrylate30 35 Cellulose Acetate Butyrate 3 Propyl Acetate 34 Propyl Alcohol 28 Methyl Cellosolve 5 Total 100 ~i3~
Such a coating formulation, if separately applied to a substrate and dried to remove solven~s, leaves a slightly tacky and dust free film on the substrate.
Next, a sprayable, clear solution was formed by add-ing a portion of the above coating ~ormulation to a spray-able solvent system as set forth below.
1~ Additive Coating Formulation 356 Solvents Butyl Acetate 100 Butanol 100 Methyl Isoamyl Ketone 100 Methyl Cellosolve 100 This sprayable solution contained the following total weight percentages o~ each component.
Total Component wt. %
Pentaerythritol Tetraacrylate 14.2 Cellulose Acetate Butyrate1.4 Propyl Acetate 16.0 Propyl Alcohol 13.2 Methyl Cellosolve 15.6 Butanol 13.2 3~ Butyl Acetate 13.2 ~ethyl Isoamyl Ketone 13.2 100.0 To this solution was added 0.8 p.b.w~ of alpha 35 chloroacetyldiphenyloxide to form a UV curable coating compo-sition. This curable composition was then sprayed under low prassure on a polyvinyl chloride substrate (TENNECO CHEM. CO.) at a wet film thickness of about 0.9 mil using a DeVilbiss-TYPE EGA spray gun and allowed to dry in air at room tempera-40 ture. The composition leveled out well on the substrate.
~3~
Upon drying the film thickness was about 0.3 mil. and was dust-free. The polyvinylchloride substrate coated with the curable mixture was then irradiated with high intensity UV
light for about 3 sec. ~o e~fect curing. It was ~ound that the curable composition could be le~t on the substrate ~or hou~s before UV curing without air inhibition of cure.
This Example demonstrates the resistance to steel wool abrasion of a cured composition according to this inven-tion on a polymeric substrate and its comparison to other 15 coated substrates and an uncoated substrate.
In this Example, a sample of the cured composition of Example 1 on polyvinyl chloride (Ex. 1 CO~TING) was sub-jected to abrasion by rubbing with a ~ inch block of aluminum covered with 1/8 inch thick 0000 steel wool under a 1000 gm.
20 load. After each double rub ~1 back and ~orth stroke) the coating was observed for visible scratches. No more than 1000 double rubs were made. As comparison samples, the following were also tested:
A polyvinyl substrate coated with a vinyl urethane 25 cQmposition (VINYL URETHANE);
A vinyl substrate coated with a composition compris-ing a vinyl chloride - vinyl acetate - vinyl alcohol terpoly-mer and melamine (VI~YL MELAMINE);
An acrylic substrate coated with a nitrocellulose-30 aliphatic urethane coating (ALIPHATIC URETHAN~); and An uncoated polyvinyl chloride substrate ~UNCOATEDSUBSTRATE).
~ Table 1 below summarizes the resullts of all test.
~ ~ 3 Table 1 _ ____ _ _ .
Sample No. of Double Rubs Yisible Scratches ,_, .
Ex. 1 COATING 1000 None 10 VINYL URETHANE 2 Namerous VINYL MELAMINE 2 Numerous ALIP~A~IC URETHANE 3 Numerous 15 U~COATED SUBST~ATE 1 Nu~erous _ . . . _ As the table shows, the Example 1 COATI~G resisted scratching by the steel ~ool up to 1000 double rubs The re-maining samples did not endure more than`3 double rubs before 20 severe scratching doveloped. ~n addition, tl~e Example 1 COAT-ING was resistant to thermal stress cracking and flexible.
EX~M
In this Example, the samples of Example 2 were test-ed on a Taber Abrader described in ASTM D 1004-56. To sum-marize this procedure, each sample was mounted on a ~urntable and was abraded by a pair of abrasive wheels (CS 10) weighing 1000g each rotating in opposite direc~ions. The abrasive 30 wheels traveled on the sample about a horizontal axis displaced tangentially from the axis of rotation of the sample re~
sulting in a wearing action. The abrasion was de~ermined by the visual condition of each sample a~ter S0, 100 and 200 revolutions of the ~brader. The weight loss of each sample 35 was also determined after the test. Table 2 summarizes the results.
Table 2 . ___ __~ ~_ SAMPLE CONDIT~ON AFTER WEIGHq;
SAMPLE P~EVOLUT~ONS LOSS
Ex. 1 No No Slight None COATING Effect Effect Poli~h URETH~NE Abraded _ 2 mg.
VINYL
MEL~INE Abraded 2 mg.
ALIPHATIC J
URETRANE Abraded 3 mg.
UNCOATED
SUBSTRATE Abraded 3 mg.
20' As table 2 shows, hardly any abrasion of the EX.
COATING occurred even after 200 revolutions. The remaining samples, on the other hand, were all abraded after 50 revolu-tions as indicated by their visible condition and weight loss.
2~
This Example illustrates the high resistance to scratching of cured coatings according to the present inven~
~0 tion on various polymeric substrates.
A sample of the curable coating composition as set fo~th in ~xample 1 was sprayed on an acrylic sheet substrate, a vinyl sheet substrate and a polycarbonate sheet substrate at a wet film thickness of about 2 mil. and all,owed to dry to 35 remove solvents;. The dry film thickness was '~abou~ 0O4 mil.
and was dust-free. The dried coatings were then irradiated with high intensity UV light for 3 seconds in air to effect curing. Curing, could be conducted hours a~ter deposition of the composition without air inhibition of cure.
4~ Each coated sheet was then subjected to a surface .. ..
~5~
~15-endurance test (BT~ Balanced Beam Mar Test-ASTM Method D-2197). In this test each sample was placed on a movable hori~
zontal plastic plate beneath a stationary me~al s~ylus pivoted at an angle of 45 with respect ~o the plate. ~he stylus carried a horizontal platform on which were placed weights of different magni~udes. The weights used in this test were 50 gms., 100 gms., 150 gms. and 200 gms. After each weight was 10 placed on the platform, the plate and sample were moved hori-zontally under the stylus and the visual condition o~ tha sample observed thereafter.
Table 3 summarizes the results of the test.
Table 3 SAMPLE PLATFORM WEIG~T (GMS. ) 50 100 15~ 200 _ ~ ~ ~ ._ .
COATED ACRYLIC
20 SHEET` No effect No effect No efect No e~ect COATED VINYL
SHEETNo effect No effect No effect No e~ect COATED POLY-25 CARBONATE SHEET No effect No effect No e~fect No effect UNCOATED VI~YL Fineline Line Heavy Line Gouge _ ! _ _ ___ ___ As thè table shows all coated substrates were com-pletely resistant to scratching by the stylus, under all 30 loads. The uncoated vinyl sheet developed scr~atches under the lowest load and the intensity of scratching increased with increasing loads.
Example 5 In thi~s Example, the procedure o~ Example 1 was ~ol-lowed except that the stock solution of cellulose acetate butyrate was eliminated and the curable composition formed after removal of solvents essentially comprised pentaeryth~i 40 tol tetraac~ylate and the photoinitiator~ ~ter removal of ~i3~
solvents the coating was wet, tacky and easily picked ~p dust.After irradiating the composition with UV light about 5 sec.
in air the coating was hard and brittle and it was found that s~roking the coating with steel wool only a few times produced abrasion. This was attributed to air inhibition o~ the poly-acrylate cure which inhibition is substantially eliminated by the use o~ cellulose acetate butyra~e as demonstra~ed in the 1~ ~oreyoing Examples.
Example 6 In this Example, the procedure of Example 1 was fol-15 lowed except that nitrocellulose was substituted for celluloseacetate butyrate as the cellulose ester. The sprayable solu-tion formed using this procedure was applied to an acrylic substrate instead o~ the polyvinyl chloride substrate of Exam~
ple 1. The resul~ing cured coating was subjected to the steel 2~ wool abrasion test as set forth in Example 2. ~t was found that after 6 double rubs with the steel wool pad faint lines began to appear on the coating thus indicating that the nitro-cellulose-containing coating, although abrasion resistant, is less abrasion resistant than the other samples tested in Ex.
25 2.
~xample 7 This Example demonstrates the resistance of the 30 Example 1 coating to boiling water, organic solvents, acids and alkalis. For the boiling water and alcoholic potassium hydroxide tests, a sample of the Ex. 1 product was immersed in each reagent for ten minutes and the condition o~ the coating and substrate was observed for visual change. In the rem~in ing tests the reagents were maintained on the product in a wet condition or ten minutes and examined for visual change. The remaining reagents were T~F (tetrahydrofuran) which is a good solvent for PvC, M~C (methylene dichloride) a paint remover solvent, 50~ hydrofluoric acid known for its glass e~ahing properties, 10% sodium hydroxide, 40~ sulfuric acid, 70%
This Example illustrates the high resistance to scratching of cured coatings according to the present inven~
~0 tion on various polymeric substrates.
A sample of the curable coating composition as set fo~th in ~xample 1 was sprayed on an acrylic sheet substrate, a vinyl sheet substrate and a polycarbonate sheet substrate at a wet film thickness of about 2 mil. and all,owed to dry to 35 remove solvents;. The dry film thickness was '~abou~ 0O4 mil.
and was dust-free. The dried coatings were then irradiated with high intensity UV light for 3 seconds in air to effect curing. Curing, could be conducted hours a~ter deposition of the composition without air inhibition of cure.
4~ Each coated sheet was then subjected to a surface .. ..
~5~
~15-endurance test (BT~ Balanced Beam Mar Test-ASTM Method D-2197). In this test each sample was placed on a movable hori~
zontal plastic plate beneath a stationary me~al s~ylus pivoted at an angle of 45 with respect ~o the plate. ~he stylus carried a horizontal platform on which were placed weights of different magni~udes. The weights used in this test were 50 gms., 100 gms., 150 gms. and 200 gms. After each weight was 10 placed on the platform, the plate and sample were moved hori-zontally under the stylus and the visual condition o~ tha sample observed thereafter.
Table 3 summarizes the results of the test.
Table 3 SAMPLE PLATFORM WEIG~T (GMS. ) 50 100 15~ 200 _ ~ ~ ~ ._ .
COATED ACRYLIC
20 SHEET` No effect No effect No efect No e~ect COATED VINYL
SHEETNo effect No effect No effect No e~ect COATED POLY-25 CARBONATE SHEET No effect No effect No e~fect No effect UNCOATED VI~YL Fineline Line Heavy Line Gouge _ ! _ _ ___ ___ As thè table shows all coated substrates were com-pletely resistant to scratching by the stylus, under all 30 loads. The uncoated vinyl sheet developed scr~atches under the lowest load and the intensity of scratching increased with increasing loads.
Example 5 In thi~s Example, the procedure o~ Example 1 was ~ol-lowed except that the stock solution of cellulose acetate butyrate was eliminated and the curable composition formed after removal of solvents essentially comprised pentaeryth~i 40 tol tetraac~ylate and the photoinitiator~ ~ter removal of ~i3~
solvents the coating was wet, tacky and easily picked ~p dust.After irradiating the composition with UV light about 5 sec.
in air the coating was hard and brittle and it was found that s~roking the coating with steel wool only a few times produced abrasion. This was attributed to air inhibition o~ the poly-acrylate cure which inhibition is substantially eliminated by the use o~ cellulose acetate butyra~e as demonstra~ed in the 1~ ~oreyoing Examples.
Example 6 In this Example, the procedure of Example 1 was fol-15 lowed except that nitrocellulose was substituted for celluloseacetate butyrate as the cellulose ester. The sprayable solu-tion formed using this procedure was applied to an acrylic substrate instead o~ the polyvinyl chloride substrate of Exam~
ple 1. The resul~ing cured coating was subjected to the steel 2~ wool abrasion test as set forth in Example 2. ~t was found that after 6 double rubs with the steel wool pad faint lines began to appear on the coating thus indicating that the nitro-cellulose-containing coating, although abrasion resistant, is less abrasion resistant than the other samples tested in Ex.
25 2.
~xample 7 This Example demonstrates the resistance of the 30 Example 1 coating to boiling water, organic solvents, acids and alkalis. For the boiling water and alcoholic potassium hydroxide tests, a sample of the Ex. 1 product was immersed in each reagent for ten minutes and the condition o~ the coating and substrate was observed for visual change. In the rem~in ing tests the reagents were maintained on the product in a wet condition or ten minutes and examined for visual change. The remaining reagents were T~F (tetrahydrofuran) which is a good solvent for PvC, M~C (methylene dichloride) a paint remover solvent, 50~ hydrofluoric acid known for its glass e~ahing properties, 10% sodium hydroxide, 40~ sulfuric acid, 70%
3~
nitric acid, an aromatic solven~ mixture, ie. benzene, toluene and xylene, alcohol, esters and ketones, and gasoline and nitromechene. Table 4 summarizes the results.
Table 4 _.___ ~
REAGENT VISUAL CHANGE
IN PRODUCT
~ __ , ...
Boiling Water Coating una~fected;
Substrate crazed Boiling 10~ Alcoholic No change Potassium Hydroxide THF No change MDC No change 50% ~ydrofluoric ~cid No change . 10~ Sodium hydroxide No change . :.
.' 40% Sulfuric Acid ~o change 70~ Nitric Acid No change Aromatic Solvents No change Alcohol ~o chan~e . Esters and Ketones No change .' Gasoline and .
Nitromethane No change . _ . _ _ _ _ xample 8 In this Example, Taber Abrasion tests as described 40 in Example 3 were conducted to compare the substrates coated ~53~
in accordance with the procedure o~ Example 1 ie., an acrylic, polycarbonate, rigid PVC and polyester substrate, with several uncoated substrates and substrates coa~ed with other composi-tions. The u~coated substrates included a polycarbonate sub-strate sold under ~h~ ~radem~rk C~-39 (PPG-Industries, Inc.) having abrasion resistant properties. The abxasive wheels used (CS-lOF) were of a more abrasive type than those used in 10 Example 3 and weighed 500 gms. eac'n. The change in visual appearance in the example a~ter 100 cycles was measured as percent increase in haze, according to ASTM D-1003. "Measure-ment of Haze and Lumi~ance Transmittance o~ Transpaxent Plastics" using a Gardner ~aze meter. Table S summarizes the lS resul~s.
Table 5 . _ _ . . .
SAMPLE PERCENT INCREP.SE
IN HAZE
2~ ~ , Ex. 1 coating on acrylic, polycarbonate, rigid PVC
and polyester substrate1 .
Untreated Polycarbonate (CR-99, PPG Ind., Inc.) 2.0 Acrylic coated with aliphatic urethane 20. 4 ~ Rigid PVC coated wi~h melami~e composition 31.7 . / .
Untreated rigid PVC 32.7 Untreated polyester 37.3 3~
Untrea~ed polycarbonate39.1 Untreated acrylic 49. 2 ~
~39L~ I
1 ~19-As Table S shows, the substrates coated with the Example1 coatin~ were from about 2 to 67 times more ab~asion resistant than the comparison samples.
Example 9 In this 3xample, the sprayable composition of Example 1 10 was sp~ayed on an acrylic su~strate, dried ~o remove solvents and irradiated with UV light to effect crosslinking acaording to Example 1. The dry ~ilm thickness of the cured coating was about 0.4 mil. The cured, coated acrylic substrate was post-cured by heati~g it in an oven at 150F. for about 4 hours.
15 The post-cured coated substrate was then sub-jected to the steel wool abrasion test o Exampla 2 using a more abrasive steel wool grade, #1 steel wool. After approximately 1000 double rubs there were no visible scratches on the coating, thus demonstrating that post-curing at elevated temp-eratures 2~ increases the abrasion resistance o~ cured coatings according to this invention.
.
Example 10 and 11 In these Examples, the procedure of Example 1 was repeat-ed Pxcept that in the coating formulation the weight ratio o~
pentaerythritol tetraacrylate to cellulose acetake butyrate was changed from 10 to 1 to 100 to 1 (Ex. 10) and to 6 to 1 (Ex. 11).
On testing for ~esistance to steel wool abrasion accord-ing to the procedure of Example 2 it was found that both the Example 10 and 11 coatings on a polyvinyl chloride substrate endured about -20 double rubs without developing visible scratches which indicated ~hat significant abrasion resis~-35 ance of cured coatings according to the invention wa s~ill provided at the~above ratios.
In this Example, the procedure o Example 1 was followed ~ ~S39~
using di-pentaerythritol pentaacrylate instead of penta-erythritol tetraacrylate. The cured coating on a polyvinyl chloride substrate was tested for s~eel wool abrasion in accordance with the procedure of Example 2. The results were substantially the same in respect to abrasio~ resistance as the Ex. 1 coating.
~
In the Example, the procedure of Example 1 was followed using benzoyl peroxide as a photoinitiator instead of alpha-chloroacetyldiphenyloxide at a level of 1 wei~ht percent based 15 on the weight of pentaery~hritol tetraacrylate. The composi-tion was coated and cured on an acrylic substrate at a dry film thickness of about 0.3 mil. Steel wool abrasion resistance according to the procedure of Example 2 was as good as the Ex. 1 coating.
Example 14 In this Example, the procedure of Example 1 was followed except that pentaerythritol tetramethacrylate was substituted 25 for pentaerythritol tetraacrylate and about 150 p.b.w. of xylol was additionally used in preparing the coating formula-tion. About 1~ benzoyl peroxide based on the weight of penta-erythritol tetramethacrylate was added as a co-photoinitiator with the alpha-chloroacetyldiphenyloxide. The sprayable 30 solution was sprayed on a polyvinyl chloride substrate at a wet-film thickness of about 0.9 mil. After removal of sol-vents the dry film thickness was about 0.3 mil. The cure time was about 15 sec. using high intensity UV light.
It was found that rubbing the coated surface with a ~0000 35 steel wool pad according to the procedure of Example ~, pro-duced no scratches after 100 double rubs.
nitric acid, an aromatic solven~ mixture, ie. benzene, toluene and xylene, alcohol, esters and ketones, and gasoline and nitromechene. Table 4 summarizes the results.
Table 4 _.___ ~
REAGENT VISUAL CHANGE
IN PRODUCT
~ __ , ...
Boiling Water Coating una~fected;
Substrate crazed Boiling 10~ Alcoholic No change Potassium Hydroxide THF No change MDC No change 50% ~ydrofluoric ~cid No change . 10~ Sodium hydroxide No change . :.
.' 40% Sulfuric Acid ~o change 70~ Nitric Acid No change Aromatic Solvents No change Alcohol ~o chan~e . Esters and Ketones No change .' Gasoline and .
Nitromethane No change . _ . _ _ _ _ xample 8 In this Example, Taber Abrasion tests as described 40 in Example 3 were conducted to compare the substrates coated ~53~
in accordance with the procedure o~ Example 1 ie., an acrylic, polycarbonate, rigid PVC and polyester substrate, with several uncoated substrates and substrates coa~ed with other composi-tions. The u~coated substrates included a polycarbonate sub-strate sold under ~h~ ~radem~rk C~-39 (PPG-Industries, Inc.) having abrasion resistant properties. The abxasive wheels used (CS-lOF) were of a more abrasive type than those used in 10 Example 3 and weighed 500 gms. eac'n. The change in visual appearance in the example a~ter 100 cycles was measured as percent increase in haze, according to ASTM D-1003. "Measure-ment of Haze and Lumi~ance Transmittance o~ Transpaxent Plastics" using a Gardner ~aze meter. Table S summarizes the lS resul~s.
Table 5 . _ _ . . .
SAMPLE PERCENT INCREP.SE
IN HAZE
2~ ~ , Ex. 1 coating on acrylic, polycarbonate, rigid PVC
and polyester substrate1 .
Untreated Polycarbonate (CR-99, PPG Ind., Inc.) 2.0 Acrylic coated with aliphatic urethane 20. 4 ~ Rigid PVC coated wi~h melami~e composition 31.7 . / .
Untreated rigid PVC 32.7 Untreated polyester 37.3 3~
Untrea~ed polycarbonate39.1 Untreated acrylic 49. 2 ~
~39L~ I
1 ~19-As Table S shows, the substrates coated with the Example1 coatin~ were from about 2 to 67 times more ab~asion resistant than the comparison samples.
Example 9 In this 3xample, the sprayable composition of Example 1 10 was sp~ayed on an acrylic su~strate, dried ~o remove solvents and irradiated with UV light to effect crosslinking acaording to Example 1. The dry ~ilm thickness of the cured coating was about 0.4 mil. The cured, coated acrylic substrate was post-cured by heati~g it in an oven at 150F. for about 4 hours.
15 The post-cured coated substrate was then sub-jected to the steel wool abrasion test o Exampla 2 using a more abrasive steel wool grade, #1 steel wool. After approximately 1000 double rubs there were no visible scratches on the coating, thus demonstrating that post-curing at elevated temp-eratures 2~ increases the abrasion resistance o~ cured coatings according to this invention.
.
Example 10 and 11 In these Examples, the procedure of Example 1 was repeat-ed Pxcept that in the coating formulation the weight ratio o~
pentaerythritol tetraacrylate to cellulose acetake butyrate was changed from 10 to 1 to 100 to 1 (Ex. 10) and to 6 to 1 (Ex. 11).
On testing for ~esistance to steel wool abrasion accord-ing to the procedure of Example 2 it was found that both the Example 10 and 11 coatings on a polyvinyl chloride substrate endured about -20 double rubs without developing visible scratches which indicated ~hat significant abrasion resis~-35 ance of cured coatings according to the invention wa s~ill provided at the~above ratios.
In this Example, the procedure o Example 1 was followed ~ ~S39~
using di-pentaerythritol pentaacrylate instead of penta-erythritol tetraacrylate. The cured coating on a polyvinyl chloride substrate was tested for s~eel wool abrasion in accordance with the procedure of Example 2. The results were substantially the same in respect to abrasio~ resistance as the Ex. 1 coating.
~
In the Example, the procedure of Example 1 was followed using benzoyl peroxide as a photoinitiator instead of alpha-chloroacetyldiphenyloxide at a level of 1 wei~ht percent based 15 on the weight of pentaery~hritol tetraacrylate. The composi-tion was coated and cured on an acrylic substrate at a dry film thickness of about 0.3 mil. Steel wool abrasion resistance according to the procedure of Example 2 was as good as the Ex. 1 coating.
Example 14 In this Example, the procedure of Example 1 was followed except that pentaerythritol tetramethacrylate was substituted 25 for pentaerythritol tetraacrylate and about 150 p.b.w. of xylol was additionally used in preparing the coating formula-tion. About 1~ benzoyl peroxide based on the weight of penta-erythritol tetramethacrylate was added as a co-photoinitiator with the alpha-chloroacetyldiphenyloxide. The sprayable 30 solution was sprayed on a polyvinyl chloride substrate at a wet-film thickness of about 0.9 mil. After removal of sol-vents the dry film thickness was about 0.3 mil. The cure time was about 15 sec. using high intensity UV light.
It was found that rubbing the coated surface with a ~0000 35 steel wool pad according to the procedure of Example ~, pro-duced no scratches after 100 double rubs.
Claims (74)
1. A composition curable by actinic radiation to form an abrasion-resistant product consisting essentially of a pentaerythritol based polyacrylate selected from the group consisting of a pentaerythritol polyacrylate, a pentaerythritol polymethacrylate, a dipentaerythritol polyacrylate, a dipentaerythritol polymethacrylate, a tripentaerythritol polyacrylate and a tripentaerythritol polymethacrylate, a cellulose ester comprising the reaction product of cellulose with at least one organic carboxylic acid having from about 2 to 4 carbon atoms or nitric acid and a photoinitiator, wherein the weight ratio of said polyacrylate to said ester is from about 6 to 1 to about 100 to 1.
2. The composition of claim 1 wherein said pentaerythritol polyacrylate is selected from the group consisting of penta-erythritol triacrylate, pentaerythritol tetraacrylate, di-pentaerythritol hexaacrylate, dipentaerythritol pentaacrylate, tripentaerythritol octaacrylate and mixtures thereof.
3. The composition of claim 1 wherein said pentaerythritol polyacrylate is pentaerythritol tetraacrylate.
4. The composition of claim 1 wherein said dipentaerythritol polyacrylate is dipentaerythritol pentaacrylate.
5. The composition of claim 1 where n said pentaerythritol polymethacrylate is selected from the group consisting of pentaerythritol trimethacrylate, pentaerythritol tetramethacrylate, dipentaerythritol hexamethacrylate, dipentaerythritol penta-methacrylate, tripentaerythritol octamethacrylate and mixtures thereof.
6. The composition of claim 1 wherein said pentaerythritol polymethacrylate is pentaerythritol tetramethacrylate.
7. The composition of claim 1 wherein said cellulose ester is cellulose acetate butyrate.
8. The composition of claim 7 wherein said cellulose acetate butyrate contains on the average from about 15% to 50%
butyryl groups, from about 1% to about 30% acetyl groups and from about 1% to 5% hydroxyl groups.
butyryl groups, from about 1% to about 30% acetyl groups and from about 1% to 5% hydroxyl groups.
9. The composition of claim 8 wherein said cellulose acetate butyrate has a viscosity in Poises of from about 50 to 200 at 25°C. in a solution comprising 20 wt. % cellulose acetate butyrate, 72 wt. % acetone and 8 wt. % ethyl alcohol.
10. The composition of claim 1 wherein said photoinitiator is alphachloroacetyldiphenyloxide.
11. The composition of claim 1 wherein said photoinitiator is benzoyl peroxide.
12. The composition of claim 1 which further comprises at least one solvent selected from the group consisting of lower alcohols, lower alkyl acetates, alkyl ketones having from 3 to 7 carbon atoms and ethylene glycol lower alkyl ethers.
13. A composition curable by actinic radiation to form an abrasion resistant product comprising a pentaerythritol based polyacrylate selected from the group consisting of a penta-erythritol polyacrylate, a pentaerythritol polymethacrylate, a dipentaerythritol polyacrylate, a dipentaerythritol poly-methacrylate, a tripentaerythritol polyacrylate and a tri-pentaerythritol polymethacrylate, a cellulose acetate butyrate containing on the average from about 15% to 50% butyryl groups, from about 1% to 30% acetyl groups and from about 1% to 5%
hydroxyl groups and a photoinitiator, wherein the weight ratio of said polyacrylate to said butyrate is from about 6 to 1 to about 100 to l.
hydroxyl groups and a photoinitiator, wherein the weight ratio of said polyacrylate to said butyrate is from about 6 to 1 to about 100 to l.
14. The composition of claim 13 wherein said cellulose acetate butyrate has a viscosity in Poises of from about 50 to 200 at 25°C. in a solution comprising 20 wt. % cellulose acetate butyrate, 72 wt. % acetone and 8 wt. % ethyl alcohol.
15. The composition of claim 13 wherein said cellulose acetate butyrate contains on the average 37% butyryl groups, 13% acetyl groups and 2% hydroxyl groups and has a viscosity in Poises of from about 64 to 124 at 25° C. in a solution comprising 20 wt. % cellulose ester, 72 wt. % acetone and 8 wt. % ethyl alcohol.
16. The composition of claim 13 wherein said photoinitiator is alpha chloroacetyldiphenyloxide.
17. The composition of claim 13 wherein said photoinitiator is benzoyl peroxide.
18. The composition of claim 13 which further comprises at least one solvent selected from the group consisting of lower alcohols, lower alkyl acetates, alkyl ketones having from 3 to 7 carbon atoms and ethylene glycol lower alkyl ethers.
19. The composition of claim 13 wherein said weight ratio is from about 8 to 1 to about 20 to 1.
20. The composition of claim 13 wherein said weight ratio is about 10:1.
21. The composition of claim 13 wherein said pentaerythritol polyacrylate is pentaerythritol tetraacrylate.
22. The composition of claim 13 wherein said dipentaery-thritol polyacrylate is dipentaerythritol tetraacrylate.
23. The composition of claim 13 wherein said dipentaery-thritol polymethacrylate is dipentaerythritol tetramethacrylate.
24. A composition curable by actinic radiation to form an abrasion resistant product comprising pentaerythritol tetra-acrylate, a cellulose acetate butyrate containing on the average 37% butyryl groups, 13% acetyl groups and 2% hydroxyl groups and having a viscosity in Poises of from 64 to 124 at 25°C. in a solution comprising 20 wt.% cellulose ester, 72 wt. % acetone and 8 wt. % ethyl alcohol and a photoinitiator wherein the weight ratio of said tetraacrylate to said cellulose acetate butyrate is from about 6 to 1 to 100 to 1.
25. A product comprising the cured composition of claim 1.
26. A product comprising the cured composition of claim 3.
27. A product comprising the cured composition of claim 8.
28. A product comprising the cured composition of claim 13.
29. A product comprising the cured composition of claim 14.
30. A product comprising the cured composition of claim 15.
31. A product comprising the cured composition of claim 21.
32. A product comprising the cured composition of claim 24.
33. An abrasion-resistant product comprising a substrate having coated thereon the cured composition of claim l.
34. An abrasion-resistant product comprising a substrate having coated thereon the cured composition of claim 13.
35. An abrasion-resistant product comprising a substrate having coated thereon the cured composition of claim 24.
36. A product comprising a substrate having coated thereon the composition of claim 1.
37. A product comprising a substrate having coated thereon the composition of claim 3.
38. A product comprising a substrate having coated thereon the composition of claim 8.
39. A product comprising a substrate having coated thereon the composition of claim 13.
40. A product comprising a substrate having coated thereon the composition of claim 14.
41. A product comprising a substrate having coated thereon the composition of claim 15.
42. A product comprising a substrate having coated thereon the composition of claim 21.
43. A product comprising a substrate having coated thereon the composition of claim 24.
44. The product of claim 33 wherein said substrate is a polymeric material selected from the group consisting of poly-acrylics, polyvinyls, polycarbonates and polyesters.
45. The product of claim 35 wherein said substrate is a polymeric material selected from the group consisting of poly vinyls, polyacrylics, polycarbonates and polyesters.
46. The product of claim 37 wherein said substrate is a polymeric material selected from the group consisting of poly-vinyls, polyacrylics, polycarbonate and polyesters.
47. A method of providing an abrasion resistant coating on a substrate comprising:
(a) forming a composition curable by actinic radiation comprising a pentaerythritol-based polyacrylate or polymethacrylate, a cellulose ester comprising the reaction product of cellulose with at least one organic carboxylic acid having from about 2 to about 4 carbon atoms or nitric acid and a photoinitiator wherein the weight ratio of said polyacrylate or poly-methacrylate to said ester is from about 6 to 1 to 100 to 1;
(b) applying said composition to said substrate;
(c) irradiating said composition with actinic radiation to effect curing thereof.
(a) forming a composition curable by actinic radiation comprising a pentaerythritol-based polyacrylate or polymethacrylate, a cellulose ester comprising the reaction product of cellulose with at least one organic carboxylic acid having from about 2 to about 4 carbon atoms or nitric acid and a photoinitiator wherein the weight ratio of said polyacrylate or poly-methacrylate to said ester is from about 6 to 1 to 100 to 1;
(b) applying said composition to said substrate;
(c) irradiating said composition with actinic radiation to effect curing thereof.
48. The method of claim 47 wherein said pentaerythritol-based polyacrylate is selected from the group consisting of pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexa-acrylate tripentaerythritol octaacrylate and mixtures thereof.
49. The method of claim 47 wherein said pentaerythritol-based polyacrylate is pentaerythritol tetraacrylate.
50. The method of claim 47 wherein said cellulose acetate butyrate contains on the average from about 15% to 50% butyryl groups, from about 1% to 30% acetyl groups and from about 1%
to 5% hydroxyl groups.
to 5% hydroxyl groups.
51. The method of claim 50 wherein said cellulose acetate butyrate has a viscosity in Poises of from about 50 to 200 at 25°C. in a solution comprising 20 wt. % cellulose ester, 72 wt. %
acetone and 8 wt. % ethyl alcohol.
acetone and 8 wt. % ethyl alcohol.
52. The method of claim 50 wherein said cellulose acetate butyrate contains on the average 37% butyryl groups 13% acetyl groups and about 2% hydroxyl groups.
53. The method of claim 47 wherein said photoinitiator is alpha chloroacetyldiphenyloxide.
54. The method of claim 47 wherein said photoinitiator is benzoyl peroxide.
55. The method of claim 47 wherein said composition is applied by spraying.
56. The method of claim 47 wherein said substrate is a polymeric material selected from the group consisting of polyacrylics, polyvinyls, polycarbonates and polyesters.
57. A method of providing an abrasion resistant coating on a substrate comprising:
(a) forming a composition curable by actinic radiation comprising a pentaerythritol-based polyacrylate or methacrylate, a cellulose acetate butyrate containing on the average from about 15% to 50% butyryl groups, from about 1%
to 30% acetyl groups and from about 1% to 5% hydroxyl groups and a photoinitiator, wherein the weight ratio of said acrylate or methacrylate to said butyrate is from about 6 to 1 to about 100 to 1;
(b) applying said composition to said substrate;
and (c) irradiating said composition with actinic radiation to effect curing thereof.
(a) forming a composition curable by actinic radiation comprising a pentaerythritol-based polyacrylate or methacrylate, a cellulose acetate butyrate containing on the average from about 15% to 50% butyryl groups, from about 1%
to 30% acetyl groups and from about 1% to 5% hydroxyl groups and a photoinitiator, wherein the weight ratio of said acrylate or methacrylate to said butyrate is from about 6 to 1 to about 100 to 1;
(b) applying said composition to said substrate;
and (c) irradiating said composition with actinic radiation to effect curing thereof.
58. The method of claim 57 wherein said cellulose acetate butyrate has a viscosity in Poises of from about 50 to 200 at 25°C. in a solution comprising 20 wt. % cellulose ester, 72 wt. % acetone and 8 wt. % ethyl alcohol.
59. The method of claim 57 wherein said cellulose acetate butyrate contains on the average 37% butyryl groups, 13 acetyl groups, and 2% hydroxyl groups.
60. The method of claim 58 wherein said cellulose acetate butyrate has a viscosity in Poises of from 64 to 124 at 25°C.
61. The method of claim 57 wherein said photoinitiator is alpha chloroacetyldiphenyloxide.
62. The method of claim 57 wherein said photoinitiator is benzoyl peroxide.
63. The method of claim 57 wherein said composition is applied by spraying.
64. The method of claim 57 wherein said substrate is a poly-meric material selected from the group consisting of poly-acrylics, polyvinyls, polycarbonates and polyesters.
65. The method of claim 57 wherein the weight ratio of said pentaerythritol-based polyacrylate or methacrylate to said cellulose acetate butyrate is from about 8 to 1 to 20 to 1.
66. The method of claim 57 wherein the weight ratio of said pentaerythritol-based polyacrylate or methacrylate to said cellulose acetate butyrate is about 10 to 1.
67. The method of claim 57 which further comprises post-curing said cured coating at elevated temperatures.
68. A method of providing an abrasion resistant coating on a polymeric substrate comprising:
(a) forming a solution of pentaerythritol tetra-acrylate, a cellulose acetate butyrate containing on the average 37% butyryl groups, 13% acetyl groups and 2% hydroxyl groups and having a viscosity in Poises of from about 50 to 200 at 25°C. in a solution comprising 20 wt. % cellulose ester, 72 wt. % acetone and 8 wt. % ethyl alcohol and a photoinitiator in at least one solvent selected from the group consisting of lower alcohols, lower alkyl acetates, alkyl ketones having from 3 to 7 carbon atoms and ethylene glycol lower alkyl ethers wherein the weight ratio of said tetraacrylate to said butyrate is from about 6 to 1 to about 100 to 1;
(b) spraying said solution on said substrate;
(c) removing said at least one solvent; and (d) irradiating said coating with ultraviolet radiation to effect curing thereof.
(a) forming a solution of pentaerythritol tetra-acrylate, a cellulose acetate butyrate containing on the average 37% butyryl groups, 13% acetyl groups and 2% hydroxyl groups and having a viscosity in Poises of from about 50 to 200 at 25°C. in a solution comprising 20 wt. % cellulose ester, 72 wt. % acetone and 8 wt. % ethyl alcohol and a photoinitiator in at least one solvent selected from the group consisting of lower alcohols, lower alkyl acetates, alkyl ketones having from 3 to 7 carbon atoms and ethylene glycol lower alkyl ethers wherein the weight ratio of said tetraacrylate to said butyrate is from about 6 to 1 to about 100 to 1;
(b) spraying said solution on said substrate;
(c) removing said at least one solvent; and (d) irradiating said coating with ultraviolet radiation to effect curing thereof.
69. The method of claim 68 wherein said polymeric substrate is selected from the group consisting of polyvinyl, poly-acrylics, polycarbonates and polyesters.
70. The method of claim 68 wherein said weight ratio is from about 8 to 1 to about 20 to 1.
71. The method of claim 58 wherein said weight ratio is about 10 to 1.
72. The method of claim 68 which further comprises postcuring said coating at temperatures of from between 100°F
and 150°F for from 2 to 5 hours.
and 150°F for from 2 to 5 hours.
73. The method of claim 68 wherein said photoinitiator is alpha chloroacetyldiphenyloxide.
74. The method of claim 68 wherein said photoinitiator is benzoyl peroxide.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US1341879A | 1979-02-21 | 1979-02-21 | |
| US013,418 | 1979-02-21 | ||
| US06/104,351 US4308119A (en) | 1979-02-21 | 1980-01-07 | Abrasion-resistant optical coating composition containing pentaerythritol based polyacrylates and cellulose esters |
| US104,351 | 1980-01-07 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1153491A true CA1153491A (en) | 1983-09-06 |
Family
ID=26684814
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000345431A Expired CA1153491A (en) | 1979-02-21 | 1980-02-12 | Abrasion-resistant coating composition |
Country Status (6)
| Country | Link |
|---|---|
| US (1) | US4308119A (en) |
| JP (2) | JPH021162B2 (en) |
| CA (1) | CA1153491A (en) |
| FR (1) | FR2449715B1 (en) |
| GB (1) | GB2056886B (en) |
| WO (1) | WO1980001805A1 (en) |
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| US4134809A (en) * | 1977-08-22 | 1979-01-16 | Eastman Kodak Company | Radiation curable cellulose ester-acrylate compositions |
| US4194955A (en) * | 1978-11-13 | 1980-03-25 | Celanese Corporation | Ultraviolet curable self-pigmented coating composition |
| US4308119A (en) * | 1979-02-21 | 1981-12-29 | Panelgraphic Corporation | Abrasion-resistant optical coating composition containing pentaerythritol based polyacrylates and cellulose esters |
-
1980
- 1980-01-07 US US06/104,351 patent/US4308119A/en not_active Expired - Lifetime
- 1980-02-12 CA CA000345431A patent/CA1153491A/en not_active Expired
- 1980-02-20 GB GB8033385A patent/GB2056886B/en not_active Expired
- 1980-02-20 JP JP55500574A patent/JPH021162B2/ja not_active Expired
- 1980-02-20 FR FR8003720A patent/FR2449715B1/fr not_active Expired
- 1980-02-20 WO PCT/US1980/000162 patent/WO1980001805A1/en active Application Filing
-
1988
- 1988-04-13 JP JP63091208A patent/JPS6426647A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| US4308119A (en) | 1981-12-29 |
| JPS6426647A (en) | 1989-01-27 |
| WO1980001805A1 (en) | 1980-09-04 |
| JPH0341495B2 (en) | 1991-06-24 |
| JPH021162B2 (en) | 1990-01-10 |
| FR2449715B1 (en) | 1984-10-05 |
| FR2449715A1 (en) | 1980-09-19 |
| JPS56500258A (en) | 1981-03-05 |
| GB2056886A (en) | 1981-03-25 |
| GB2056886B (en) | 1983-08-24 |
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| Date | Code | Title | Description |
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