CA1100672A - Green strength of elastomers - Google Patents
Green strength of elastomersInfo
- Publication number
- CA1100672A CA1100672A CA277,097A CA277097A CA1100672A CA 1100672 A CA1100672 A CA 1100672A CA 277097 A CA277097 A CA 277097A CA 1100672 A CA1100672 A CA 1100672A
- Authority
- CA
- Canada
- Prior art keywords
- dimethylbutadiene
- carbon atoms
- monomers
- class consisting
- butadiene
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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Classifications
-
- 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
- C08F36/00—Homopolymers and copolymers of compounds having one or more unsaturated aliphatic radicals, at least one having two or more carbon-to-carbon double bonds
- C08F36/02—Homopolymers and copolymers of compounds having one or more unsaturated aliphatic radicals, at least one having two or more carbon-to-carbon double bonds the radical having only two carbon-to-carbon double bonds
- C08F36/04—Homopolymers and copolymers of compounds having one or more unsaturated aliphatic radicals, at least one having two or more carbon-to-carbon double bonds the radical having only two carbon-to-carbon double bonds conjugated
- C08F36/045—Homopolymers and copolymers of compounds having one or more unsaturated aliphatic radicals, at least one having two or more carbon-to-carbon double bonds the radical having only two carbon-to-carbon double bonds conjugated conjugated hydrocarbons other than butadiene or isoprene
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L21/00—Compositions of unspecified rubbers
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- Chemical & Material Sciences (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Compositions Of Macromolecular Compounds (AREA)
Abstract
IMPROVED GREEN STRENGTH OF ELASTOMERS
ABSTRACT OF THE DISCLOSURE
Improved green strength of elastomers made from mono-mers selected from the class consisting of at least one conju-gated diene having from 4 to 10 carbon atoms, olefins having from 2 to 14 carbon atoms along with a diene having from 4 to 6 carbon atoms, and combinations thereof, is achieved by add-ing an amount of a polydimethylbutadiene compound to form a blend having a glass transition temperature of from about 0°C
to about -100°C. The polydimethylbutadiene compound may be merely the homopolymer of dimethylbutadiene, the copolymer, the terpolymer or the tetrapolymer of dimethylbutadiene in various combinations with monomers such as butadiene, isoprene, piperylene, acrylonitrile, vinylidene chloride, vinyl pyri-dine, methacrylic acid and vinyl substituted aromatic com-pounds.
ABSTRACT OF THE DISCLOSURE
Improved green strength of elastomers made from mono-mers selected from the class consisting of at least one conju-gated diene having from 4 to 10 carbon atoms, olefins having from 2 to 14 carbon atoms along with a diene having from 4 to 6 carbon atoms, and combinations thereof, is achieved by add-ing an amount of a polydimethylbutadiene compound to form a blend having a glass transition temperature of from about 0°C
to about -100°C. The polydimethylbutadiene compound may be merely the homopolymer of dimethylbutadiene, the copolymer, the terpolymer or the tetrapolymer of dimethylbutadiene in various combinations with monomers such as butadiene, isoprene, piperylene, acrylonitrile, vinylidene chloride, vinyl pyri-dine, methacrylic acid and vinyl substituted aromatic com-pounds.
Description
IMPROVED GREEN STRENGTH OF ELASTOMERS
BACKGRO~ND OE THE INVENTION
The present invention rel~tes to improved greenstrength of various elastomers. More specifically, the present invention relates to obtaining improved green strength of various elas-tomers by adding polydimethylbutadiene, copoly-mers, terpolymers or tetrapolymers thereof to various elasto-mers to form various blends.
Science and technology in the elas-tomer field has improved -to such an extent that synthetic elastomers have supplemented or replaced natural rubber to a great ex-tent in the fabrication of tires and other rubber produc-ts. Stereo-specific polymers and particularly synthetic cis 1,4-polyiso-prene have demons-trated physical properties similar -to and thus are capable of becoming a complete replacement for natural rubber. However, a major deficiency of rubber elasto-mers including synthetic cis-154-polyisoprene is its lack of sufficient green strength required for satisfactory pro-cessing or building properties as in the building of tires.
- 20 The abatement of -this deficiency has long been sough-t by the art and would greatly facilitate in the replacement of natural rubber which is solely produced in tropical climates.
The term "green strength", while being commonly em-ployed and generally understood by persons skilled in -the .:
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rubber industry, is nevertheless a difficult proper-ty to pre-cisely define. Basically, it is -that property of a polymer common in natural rubber, which contributes the proper building conditions where mul-tiple components are employed and which result in little or no release of relative movement of the assembled components subsequent to assembly and prior to ini-tiation of the curing operation. Thus, the problem of low green strength, that is the lack of the requisi-te mechanical strength for processing and fabricating operations necessarily carried out prior to vulcanization wi-th synt'hetic poly~ers or copolymers, is lacking. That is, generally wi-th maximum or "peak" stress which the unvulcanized ma-terials will exhibit during deforma-tion is rather low. Hence, unvulcanized strips or o-t'her forms of the elastomer are often distorted during processing or building operations. ~lthough numerous addi-tives and compounds have been utilized in association with various elastomers and particularly synthetic cis~ polyisoprene, substantial improvement in green strength has generally no-t been accomplished.
Green strength has generally been measured by stress/
s-train curves of unvulcanized compounds. Usually the per-formance of a green compound is based upon three points of the stress/strain curve, namely the firs-t peak or inf'lection of the stress, -the ultimate or breaking tensile and -the percen-t of ultimate elongation. Improvements in any one or more of' these stress properties indicate improved green strength.
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Among the various additive compo~mds or agents which have been utilized to improve green strength or synthe-tic rubber elastomers are numerous nitroso compounds as set forth in United States Patent Mumbers 2,457,331; 2,~77,015; 2,518, 576; 2,526,504; 2,540,596; 2,690,780; and 3,093,614. Addi-tionally, various dioxime compounds have been utilized such as those set forth in U. S. Patent Numbers 2,969,3~1; 3 9 037, 95~; 3,160,595; and P,ritish Patent 896,309. Yet another class - of additives or compounds are the diesters of 5-norbornene as set forth in U. S. Patent Numbers 3,817,883 and 3,843,613.
Another prior art patent is U. S. Patent 3,562,303 to Smith and McFadden, which relates to increased green strength of polyisoprene rubbers or copolymers of isoprene rubbers through a partial cure. That is, the polymer or co-: 15 polymer actually cross-links and thus is cured by using from 10 percent to 30 percent of the total amount of sulfur re-quired to effect complete vulcanization and from 10 percent to 50 percent of the total amo~mt of accelerator required to effect such vulcanization. Thus, thls paten~ does not re-late to a blend of rubber polymers but solely to copolymers wherein any green strength improvement is solely through a partial sulfur cure.
SU~IMARY OF THE INVENTION
It is, therefore, an object of an aspect of the pre-sent invention to provide elastomer blends having improved green ~strength.
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It is an object of another aspect of the present in-vention to provide improved green strength elastomer blends, as above ? wherein the blend contains elastomers of natural and synthetic cis-1,4-polyisoprene, butadiene, and a copolymer of styrene and bu~adiene.
It is another object of a further aspect of the present invention to provide improved green strength elastomer blends, as above, wherein the blend contains an amount of a polydimethylbutadiene compound or copolymers, terpol~mers or tetrapolymers of dimethylbutadiene.
It is another object of a further aspect of the present inve~tion to provide improved green strength elastomer blends, as above, wherein the elastomer contains a high amoLmt of cis units.
It is another objec-t of a further aspect of the pre-sent invention to provide improved green strength elastomer blends, as above, which are made according to a process and can readily be compounded with conventional compounding agents.
It is another object of a further aspect of the present invention to provide improved green strength elastomer blends, as above, which blends are conveniently used in the production of carcasses for radial tires.
It is another object of a further aspect of the present invention to provide improved green strength elastomer blends, as above, which can be utilized for truck tires.
Generally~ a process and composition for improving the green strength of blends of elastomers are characterized by providing an amount of a dimethylbutadlene compo~md, pro-~,~
viding an a~.ount of an elastomer, producing a physical and an uncured blend by mixing said dimethylbutadiene compound and said elastomer, said elastomer selected from the class consisting of natural rubber, synthetic elastomers, and com binations thereof, said synthetic elastomers made from mono-mers selected fror.l the class consisting of at least one conjugated diene having from 4 to 10 carbon atoms, olefins having from 2 to 14 carbon atoms and a diene having from to 10 carbon atoms, and combinations thereof, said blend ].0 having a glass transition temperature of from about 0C to about -100C, the amount of said dimethylbutadiene compound ranging from about 5 parts to about 80 parts based upon 100 parts of said blend, said dimethylbutadiene compo~mds being an elastomer selected from the class consisting of polydi-methylbutadiene, copolymers of dimethylbutadiene, terpolymers of dimethylbutadiene, and tetrapolymers of dimethylbutadiene, said polydimethylbutadiene made from monomers of dimethyl-butadiene, said copolymers, said terpolymers, and said tetra-polymers of dimethylbutadiene made from monomers selected.
.. Z from the class consisting of dienes having from ~ to 12 carbon atoms, and vinyl substituted aromatic hydrocarbons having from 8 to 12 carbon atoms, and combinations thereof.
Generally, a composition of elastomer blends hav-ing improved green strength,is characterized by: a physical and uncured blend of a dimethylbutadiene compound and an elastomer, the amount of said dimethylbutadiene compound ranging from about 5 parts to about ~0 parts per 100 parts of said blend; said elastomer selected from the class con-., ~
67~2 :
sisting of natural rubber, synthetic e].astomers, and combina--tions thereof; said synthetic elastomers made from monomers selected from the class consisting of at least one diene having from ~ to 10 carbon atoms, a diene having from 4 to 10 carbon atoms and an olefin having :Erom 2 to 1~ carbon atoms, and combinations thereof to Eorm a blend having a glass transition temperature of from about ~C to about -100C;
said dimethylbutadiene compound being an elastomer selected from the class consisting oE polydimethylbutadiene, copoly-mers of dimethylbutadiene, terpolymers of dimethylbutadiene, and tetrapolymers of dimethylbutadiene; said copolymers of dimethylbutadiene, said tetrapolymers of dimethylbutadiene made from monomers of dimethylbutadiene and monomers selected from the class consisting of dienes having from ~ to 12 carbon atoms, vinyl substituted aromatic hydrocarbon monomers having from 8 to 12 carbon atoms, and combinations thereof.
E2~I~ODIkIENTS OF T~E INVENTION
According to the concepts of the present invention, improved green strength is obtained by adding a polydimethyl-butadiene compound to various elastomers to form blends.
'rhese blends are particularly suitable for use as radial tire carcasses and may contain either natural or synthetic cis-l,~~polyisoprene.
The uncured blends of the present invention are made from monomers generally considered by those skilled in the art capable of form-lng rubbers in combination with one or more of the various polydime~hylbutadiene compounds which generally are a polymer o.E dimethylbutadiene, a copolymer, -5a-i7~
a terpolymer, or a -tetrapolymer of dimetbylbutadiene.
More specifically, the elastomers are natural cis-1,4-polyisoprene or synthetic e]as-tomers made from monomers selected from the group of compounds consisting of a-t least one conju-gated diene having from 1~ to about 10 carbon a-toms so t'hat diene copolymers, terpolymers, etc., may be utilized, monomers of dienes having from 4 to 10 carbon atoms with olefins having from 2 -to about 14 carbon atoms so that diene-olefin copolymers may be utilized, and combinations -thereof. A preferred group of olefin compounds are the vinyl substituted aromatic hydro-carbons containing from 8 to about 12 carbon atoms and include styrene, alpha-methylstyrene, ortho-, para-, and meta-methyl and ethylstyrene and t'he like. Of the non-aromatic olefin compounds, the compounas con-taining from 3 to 6 car'bon atoms are preferred. Specific examples of olefins include e-thane, pro-pene, butene, pentene, hexene, heptene, octene, nonene, decene, dodecene and the like. Concerning the diene compounds, the dienes having from 4 to 6 carbon atoms are preferred.
Specific rubber elastomers which may be utilized in the present invention include polybutadiene, both cis and trans, polyisoprene, both cis and trans, polypiperylene, co-polymers or interpolymers of the dienes, for example, isoprene and butadiene, bu-tadiene ànd piperylene, and the like and terpolymers of dienes such as butadiene, isoprene and piperylene.
Additionally, copolymers of a diene and an olefin may be uti-lized such as styrene and butadiene, alpha-methylstyrene and butadiene, butadiene and propene, butadiene and butene and the like. Of course, combinations of a diene-olefin with at least i;7~
another diene may also be used. Preferred elastomers of the present invention include natural or synthe-tic cis~
polyisoprene, polybutadiene, and the copolymer of styrene-butadiene.
When copolymers are prepared utilizing an olefin, the amount of the olefin range may vary from 0.1 to about 99 percent by weight. In other words, so long as a few diene monomers are contained in the monomeric mixture, copolymers can be formed. Generally, the weight percent of the olefin compound will usually range from 0.1 to about 55 percent wi-th a more desirable range being from about 10 percent to about 40 percent. A preferred range of the olefin compounds such as styrene or alpha-rnethylstyrene ranges from abou-t 15 percent to ` about 25 percent.
Considering the elastomers, they may ~lave any cis content. Thus, polybutadiene and SBR will generally have a cis-1,4 content of 30 or 40 percen-t or greater whereas natural or synthetic cis 1,4-polyisoprene will have a cis-1,4 content in excess of 80 percent and often 90 percent. High cis-1,4 content in elastomers is of-ten desirable since the compounded elastomer tends to be fairly elastic.
The elastomers of the present invention, which are utilized in the blends, may generally be prepared according to any conventional or common process or technique. For example, ; the elastomers may be prepared by anionic polymerization using organometallic compounds as cata]ysts such as butyllithium.
Additionally, the elastomers may be made according to a free radical emulsion process. In any of these processes as well 7%
as any others, the various parame-ters such as time, tempera--ture, pressure and -the like as well as the various catalysts and -techniques are well known to those skilled in -the art.
The dimethylbu-tadiene compound may be blended with the above-noted elastomers either alone, -that is as a polymer of dimethylbutadiene, or as a copolymer, terpolymer or tetrapolymer of dimethylbutadiene. These compounds, or any combination thereof, have been found to give vastly improved green strength to the above elas-tomers and thus the blends have much improved green strength.
The polymer of dimethylbutadiene may be prepared in any common or conventional manner and thus may be made according to a -free radical emulsiorl process or an anionic process and the like. In accordance wi-th any of these -techniques, a polymer is desired which has a number average molecular weight : range of from 1 x 105 to about 5 x 105 with a preferred range being from about 1.5 x 105 to about 2.5 x 10 .
The dimethylbu-tadiene homopolymer, copolymer, terpolymer or te-trapolymer of dimethylbutadiene may be made according to any common, conventional or normal manner or method well known to those skilled in the art. The monomers in addition to -the dimethylbutadiene monomers are selected from the group consisting of dienes having from 4 to 12 carbon atoms, vinyl substituted aromatic hydrocarbons having from 8 to 12 carbon atoms, vinylidene chloride, acrylonitrile, metha-crylic acid, vinyl pyridine, or the like and any combinations ; -thereof to form a copolymer~ terpolymer or tetrapolymer. In other words, if a terpolymer is to be made, any two 67~
monomers may be u-tilized from -the immedia-tely above se-t forth list in combination with a third monomer of dime-thylbutadiene.
Considering specifically copolymers of dimethyl-butadiene, the addi-tional monomer is preferably selected from the group consisting of dienes having from 4 to 12 carbon a-toms, acrylonitrile, vinylidene chloride, methacrylic acid, vinyl pyridine, or the like. Of -these, the dienes having from 4 -to 6 carbon atoms are preferred and the monomers of butadiene, isoprene, and piperylene are highly preferred.
The dimethylbutadiene compounds in the form of terpolymers are preferably made by polymerizing three different types of monomers. In addition to monomers of dimethylbu-tacliene, the other monomers preferably include butadiene and monomers selected from the class consisting of vinyl subs-ti-tuted aro-ma-tic compounds having from 8 to 12 carbon atoms, methacYylic acid and vinyl pyridine. The vinyl substituted aromatic com-pounds are desirably -those compounds which contain from 8 to 10 carbon atoms. Examples of such compo~mds include styrene, alpha-methylstyrene, ortho-, para- and meta-methyl and e-thylsty-rene. Preferred vinyl substituted aromatic compounds include styrene and alpha-methyls-tyrene. The ratio by weight of s-tyrene to -the butadiene may range from 0.1 to 55 percent of -the styrene-butadiene copolymer. ~ preferred range is from 5 to 35 percent with the preferred range being from 15 to 25 percent by weight. In the particular situation where the terpolymer contains a copolymer of styrene and butadiene, -the styrene and butadiene monomers may be polymerized in association with -the dimethylbutadiene monomers or the co-,~, I
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polymer of styrene and butadiene may be added to monomers of dimethylbutadiene and polymerized. In general, the conten-t of any one monomer of the three monomers utilized in making the terpolymer may generally range from about 1 percen-t to about 98 percent by weight.
An important aspect of the presen-t invention is tha-t an amount of the dimethylbutadiene compound, be it a dimethyl-butadiene polymer or a copolymer, a terpolymer or a tetra-polymer thereof, may be added to the above elastomers such as the preferred elastomers of na-tural and synthetic cis-1,4-polyisoprene, polybutadiene and a copolymer of styrene and a butadiene~ in such an amount so -that glass transition tempera-ture of the blend will range from about 0C to about -100C
with a preferred range being from about -20C to abou-t -80 C.
As known -to those skilled in the art, the amounts of dimethyl-butadiene polymer, copolymers, terpolymers or tetrapolymers thereof will vary depending upon exact makeup of the copolymer, the terpolymer or the tetrapolymer. Of course, an amount of a particular copolymer, terpolymer or tetrapol~ner when added to the elastomer to give a desired glass transition ternpera--ture can be readily calculated.
Generally, it has been found the copolymers, -ter-polymers or te-trapolymers of dimethylbutadiene have a glass transition -temperature usually within a range of from between -20 C to about -80 C. Thus, at least 5 parts to about 80 parts by weight of the copolymer, terpolymer or tetrapolymer are utilized with a preferred amount being about 30 par-ts by weigh-t based upon lO0 par-ts of the total weight of the rubber blend -- 10 ~
(Dimethylbutadiene compound plus elastomer). An intermediate range is from 20 parts to 60 parts by weight per 100 par-ts of the total rubber blend. If solely the polymer of dimethyl-butadiene is utilized, since -the glass transition temperature(Tg) is about -5 C -to -~5C, an amount of this compound added to -the blend i5 generally at least 5 -to about 80 parts wi-th a more pre-ferred range being from about 20 parts -to about 60 par-ts by weight based upon 100 parts of the total weight of the rubber blend. Generally, an optimum amount of the dimethylbu-tadiene polymer or copolymers or terpolymers or tetrapolymers -thereof is approximately 30 percent by weight per 100 parts of rubber blend. This amount is largely based upon the fact that it gives very desirable physical proper-ty results as well as ease in mixing and the like upon compo-unding or processing.
Concerning the -tetrapolymers of dimethylbu-tadiene, in addition to the monomers of dimethylbutadiene, of course, three other types of monomers are necessary. As before, either all four of the monomers may be polymerized simultaneously or in various combinations thereof. Besides the monomers of dime-thylbutadiene, a remaining preferred class of monomers are the vinyl subs-titu-ted aromatic hydrocarbons containing from o to 12 carbon atoms. The desired range, examples of such compounds and, examples of specific preferred compounds are the same as set forth above. Another group of preferred monomers is butadiene which, in association with the vinyl substituted aromatic compounds, will generally form copolymers such as butadiene-styrene. The range of the s-tyrene to the butadiene is the same as previously set forth above. The ,~y.' fourth remaining preferred monomer may be selec-ted frorn the group consisting of me-thacrylic acid and vinyl pyridine. The total amount of any one const;tuent of the four making up the tetrapolymer may range from l percent to 97 percen-t. As no-ted above, the important factor is that an amount of the tetrapolymer be utilized so that the glass transition tempera-ture range of the blend will be between 0C and -100C with an amount as noted above of at least 5 percent by weight of the tetrapolymer being required based upon the total weight of the rubber blend.
The particularly dime-thylbutadiene compouna or plur-ality of such compounds are mixed with the particular or plural-ity of the elastomers in any conventional or common manner, method or process such as on a mill a-t common or conventional temperatures well known to -those skilled in the art. It is -to be understood -that by such mixing, the elastomer and the dime-thylbutadiene compound are merely mixed and not poly-merized since the blend is ac-tually a physical blend of -two types of components. Typically, during the mixing process or step, -the blend is also compounded. That is, various compounds and additives are added to the blend to improve streng-th, modulus, ease of processing, reduction of oxidation and the like. Thus, typical amounts of various compounds such as carbon blacks, various clays, various silicas, various oils including aliphatic and aromatic oils, various antioxidan-ts and the like are added and mixed -together as on a mill. The various types of additives desired are well known -to those skilled in the art and will tend to vary as to the type and amount depending on the desired end use of the - 30 blend. Additionally, various accelerators such as zinc oxide and curing agents such as peroxides or sulfur curatives may ~LC~Q~2 be added. However, -they are not ini-tiated or vulcanized during the mixing process according to the present inventlon.
Typically, the compounded blends are then extruded, molded or shaped by any method into a desired form such as the carcass - of a tire.
For the purposes o~ the present invention, it is to be understood that by the term "natural rubber" it is meant the rubber compounds which occurs in and is produced by nature and chemically speaking is (natural) cis-1,4-polyisoprene.
This compound, as well known to those skilled in the ar-t, is chemically identical and has very similar physical properties ` -to manmade or synthetic cis-l,L~ polyisoprene except that for some reason natural rubber has much better green strength.
Hence, it is very desirable in the manu~acture of -tire car-casses and the like.
The improved green strength elastomers of the present inven-tion are generally further blended with either natural rubber (natural cis-l,L~-polyisoprene) or a synthe-tic elastomer.
For example, if a synthetic elastomer contains a dimethylbuta-diene compound in accordance with the present invention, it will have improved green s-trength. However, as known to those skilled in the art, it is generally desirable to add and blend an amount o~ natural rubber to the synthe-tic elastomer.
Such a blend is generally a common and conventional practice in the tire industry and generally produces good tire car-casses as well as treads. 0-~ course, since the synthetic elastomer contains a dimethylbutadiene compound, the resulting blend con-taining the natural rubber will also have improved green strength.
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- On the other hand, if natural rubber is utilized, it is desirable to generally blend it with a syn-thetic elas-tomer in order to lower -the hysteresis (heat generation) and to ob-tain other favorable attributes as known to -those skilled in the art. However, since synthetic elastomers general]y have poor low green strength in comparison to natural rubber, the synthetic elastomers will lower the overall green strength of the natural rubber synthetic elastomer blend. Thus, in accordance with the presen-t invention, the use of a dimethyl-butadiene compound with the natural rubber will restore the green strength reduction caused by the synthetic elas-tomer.
Since the dimethylbutadiene compound is a synthetic elastomer itself, i-t can therefore be used solely or exclusively to overcome the hysteresis problem and ye-t impart good green s-trength to the blend.
The blends of the present invention which have greatly improved green strength are particularly suitable for use in the carcasses of tires and especially for truck tires.
Other uses include conveyor belts, hoses, shoe soles and other typical industrial uses.
The invention will be better unders-tood by reference to the following examples and data.
- EX~lPLE I
A typical recipe for the e~ulsion polymerization of .. - 2,3-dlme-th.ylbutadiene and its copo~lymers, terpol~mers and : tetrapolymers is as follows based on a lOQ gram monomer charge of 2,3-dimeth.ylbutadiene:
. RECIPE A
- GRAMS
CHA~GF. A Water 192.
8Q percent of Rosin acid 2.5 Tamol N (:a trademark of Rohm & Haas) a sodium salt of a condensed naphthalene sulfonic acid 0.3 Sodium or potassium phosphate 0.25 - Fatty acld 2.1 Potassium hydroxide 0.40 CHARGE B 2,3-dimethylhutadiene 95.
t-nodecyl mercaptan 0.05 CHARGE C Water 8.
. . 15 Sulfuric acid 0.002 Ferrous sulfate 0.025 Ethylene-dlamine tetraacetic acid (.34 percent~ 0.2 Sodium ormaldehyde sulfoxylate 0.1 Sodium hydrosulfite 0.01 . _HARGE D 2,3-dimethylbutadiene 5.
50 percent para-menthane hydroperoxide 0.16 ML
CHARGE E Water 4.4 41 percent sodium dimethyl dithiocarbamate 0.44 85 percent diethanol hydroxyl-amine 0.044 Charge A is the first char~e to a vessel and desira-bly maintalned at a pH of about 10 to about 11 due to the par-~ 25 :.
. -15 .~3 i;72 ticular soap system utilized. Generally, any conventiona:L
sodium salt of an aromatic sulfonic acid may be used. After Charge A, Charge B is added, then Charge C and then Charge D.
Preferably, all the monomers being solely the 2,3-dimethylbuta-diene or the monomers for forming copolymers, terpolymers or tetrapolymers are first washed in a caus-tic solution and then in water. If a copolymer, terpolymer, etc. is made, the recipe is basically changed only by adding the comonomer charge, etc.
be-tween steps A and D. The temperature of -the polymeri~ation is usually be-tween 40F and 50F although higher temperatures as up to approximately 150F can be utilized due to the low cross-linking constant of dimethylbutadiene. A~ter approxi-mately 50-95 percent of monomer conversion occurs depending on end use of the desired blend and other ~ac-tors well known to those skilled in the ar-t, the polymerization is stopped by the addition of Charge E. The resu~Lting latex is steam stripped, salt-acid coagulated or alum coagulated and then dried to ob-tain the dimethylbutadiene compound. Of course, it is to be understood that the above recipe is only an illustration in that the amount as well as the type of various ingredients can vary a subs-tantial amount to achieve many items such as varying molecular weight, molecular weight distribution, rate of polymerization and -the like.
Another recipe which may be utilized to produce a dimethylbutadiene compound in accordance with -the present invention is set forth in Recipe B.
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RECIPE s GRAMS
CHARGE A Water 183.
- Sodium sulfate 0.15 Sodium hydroxide 0.22 Linear alkyl sulfona.te e.g. LAS 9~ (trademark~
made by Pilot Chemical Co. 0.5 to 5.0 : CHARGE B Water 5.
Sulfuric ~cid 0.002 Ferrous sulfate 0.025 : Ethylenediamine tetraacetic - acid (:34 percentl 0.2 Sodium formaldehyde sulfo.xylate 0.1 Sodium hydrosulfite 0.01 CHARGE C 2,3-dimethylbutadiene 95.
t-dodecyl mercaptan 0.05 CHARGE D 2,3--dimethylbutadiene 5.
50 percent para-menthane hydroperoxide 0.16 ML
CHAR~E E Water 4.4 41 percent sodium dimethyl dithiocarbamate 0.44 85 percent diethanol hydroxylamine 0.044 B.asically, the polymerization is conducted in a manner as set forth above with reference to Recipe A. O~
course, dimethylbutadiene copolymers, terpolvmers, etc., mav be made simply by adding the desired amount of various monomers such as hutadiene, vinyl pyridine, methacrylic acid, isoprene, and the like. Of course, as before, the ingredients, the temperatures, and the like can be varied considerably to ob-~- tain polymers containing various molecular weights and processa-bility.
: ~n advantage o~ Recipe B is that the soap system is more versatile in t~at the latex is stable ove:r a wide range of pH ~e.g. from 2 to 11) with the p~ being adjusted :
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7;2 by tbe use of any conventional linear alkyl sulfona-te addition.
The dimethylbutadiene compound be it a homopolymer, a copolymer, a -terpolymer, etc. is then blended with any elastomer, either natural or syn-thetic, as set forth in the specification. If na-tural rubber is used, it can be obtained from natural sources as well known to those skilled in the art.
If a synthetic elastomer is used, the method and preparation is well known to those skilled in -the art. For example, if the elastomer is synthetic cis~
polyisoprene, a preferred catalyst such as triisobutyl aluminum/diphenyl ether/TiC14 is u-tilized having a molar ratio of 1/1/1. The preform catalyst is added to a solution of isoprene in hexane solvent (20 percent by weight of solvent) and the polymeri~ation is allowed to proceed at approximately 25-30 C.
After about 70 to 80 percent conversion, the reaction may be s-topped with tetraethylene pen-tamine. For protection, a hindered phenol antioxidant is added. A dry elastomer is obtained by steam s-tripping followed by extrusion drive. As with -the preparation of the dimethylbutadiene compound, various parameters may be varied, all within the knowledge of those skilled in the art.
In accordance with the present invention, natural rubber (natural cis-1,4-polyisoprene) was blended with polydimethylbutadiene which was made in accordance with Recipe A. In this formulation, the polydimethylbutadiene also consti-tuted the synthetic elas-tomer. The blending was achieved by mixing the elastomer and the polydimethylbutadiene in a Brabender for approxima-tely six minutes along with typical compounding ingredients as set forth in Table I. The Tg of the blend ranged from -50C to -60C.
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~ rl E~
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1~1 O~rl ~ r~rJ
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O ~OCJ O-1~ ~
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r1r~H+~ O ~l ~a~ Iu~
~rl O H ~ rl V ~V ~ Pi ~p~ V~ ~
After compounding, the samples were pressed at 200 psi at 200 F for 15 minutes, water cooled, then irnmedia-tely clicked for dumbbells. Dumbbells having a thickness of approximately 1/10 inch were tes-ted on an Instron using a cross-head speed of 20 inches per minute. The following resul-ts were ob-tained.
TABLE II
-GREEN STRENGTE, PSI CONTROL A. B.
. . .
Initial 128 228 252 1/l~ 125 312 362 Tensile @ Break 186 514 674 Elongation @ Break 480 979 690 As apparent from Table II, Compounds A and B gave vastly improved tensi:Le strength, total elongation as well as improved green streng-th at ini-; t:lal ]./4, 1/2 and 3/4 percent of total elonga-tion.
EXAMPLE II
In a manner similar -to Example I, natural rubber was blended with either synthetic cis-1,4-polyisoprene, or SBR (styrene butadiene rubber), or a copolymer of dimethylbutadiene and butadiene, or a copolymer of dimethyl-butadiene and methacrylic acid in amounts as set forth in Table III. The polydimethylbutadiene was made in accordance with Recipe A and -thus reacted in a conventional manner to form the copolymer with either butadiene or meth-acrylic acid. As apparent from Table III~ the dimethylbutadiene copolymer also consti-tu-ted the sole synthe-tic elastomer which was added to the natural rubber. The blending was achieved by mixing the various elastomers set forth in a Brabender along with the typical compounding ingredients set forth in Table III for approximately six minutes.
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~ ~f ~ ~rl ~rl F~l V ~r~ æ d rJ rd ~1 iV ~rl O r~ rd q-l q-l H 5-1 rd 1-1 ~rl rl ~1 P~ d 0~ 0 P I u~ Q ,J u~
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Ul H U~ ~; Pi h rd O (1) d 11 11 r~ pO c~ ~ d ,~
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The various blends se-t forth in Table III generally had a Tg o~
frorn -50 C -to about -60 C. Sarnples of each blend were pressed a-t 200 psi at 200 F for 15 minutes, water cooled, and -then immedia-tely clic~ed for dumb-bells. Dumbbells having a thickness of approxima-tely 1/10 inch were -tested on an Instron using a cross-head speed of 20 inches per minute. The follow-ing results were obtained.
TABLE IV
I II
(Control) (Control) III IV
Mooney 47 5 5 53 100% Elongation, psi 34 39 49 65 300~ Elongation, psi L~2 46 64 124 Tensile Strength, psi 227 227 280 538 Elongation at break, psi 930 1106 1169 807 As readily apparen-t from Table IV, compo~mds III and IV gave im-proved green strength characteris-tics such as improved tensile strength, im-proved elongation as well as improved elongation at break.
While in accordance with the patent statutes, only the preferred embodiments have been illustrated and described in detail, it is to be under-stood that the invention is not lirrlited thereto; the scope of -the inven-tion ; being measured by the scope of -the a-ttached claims.
BACKGRO~ND OE THE INVENTION
The present invention rel~tes to improved greenstrength of various elastomers. More specifically, the present invention relates to obtaining improved green strength of various elas-tomers by adding polydimethylbutadiene, copoly-mers, terpolymers or tetrapolymers thereof to various elasto-mers to form various blends.
Science and technology in the elas-tomer field has improved -to such an extent that synthetic elastomers have supplemented or replaced natural rubber to a great ex-tent in the fabrication of tires and other rubber produc-ts. Stereo-specific polymers and particularly synthetic cis 1,4-polyiso-prene have demons-trated physical properties similar -to and thus are capable of becoming a complete replacement for natural rubber. However, a major deficiency of rubber elasto-mers including synthetic cis-154-polyisoprene is its lack of sufficient green strength required for satisfactory pro-cessing or building properties as in the building of tires.
- 20 The abatement of -this deficiency has long been sough-t by the art and would greatly facilitate in the replacement of natural rubber which is solely produced in tropical climates.
The term "green strength", while being commonly em-ployed and generally understood by persons skilled in -the .:
- 1 - ~
~0~6'~
rubber industry, is nevertheless a difficult proper-ty to pre-cisely define. Basically, it is -that property of a polymer common in natural rubber, which contributes the proper building conditions where mul-tiple components are employed and which result in little or no release of relative movement of the assembled components subsequent to assembly and prior to ini-tiation of the curing operation. Thus, the problem of low green strength, that is the lack of the requisi-te mechanical strength for processing and fabricating operations necessarily carried out prior to vulcanization wi-th synt'hetic poly~ers or copolymers, is lacking. That is, generally wi-th maximum or "peak" stress which the unvulcanized ma-terials will exhibit during deforma-tion is rather low. Hence, unvulcanized strips or o-t'her forms of the elastomer are often distorted during processing or building operations. ~lthough numerous addi-tives and compounds have been utilized in association with various elastomers and particularly synthetic cis~ polyisoprene, substantial improvement in green strength has generally no-t been accomplished.
Green strength has generally been measured by stress/
s-train curves of unvulcanized compounds. Usually the per-formance of a green compound is based upon three points of the stress/strain curve, namely the firs-t peak or inf'lection of the stress, -the ultimate or breaking tensile and -the percen-t of ultimate elongation. Improvements in any one or more of' these stress properties indicate improved green strength.
' a~
al6~2 .
Among the various additive compo~mds or agents which have been utilized to improve green strength or synthe-tic rubber elastomers are numerous nitroso compounds as set forth in United States Patent Mumbers 2,457,331; 2,~77,015; 2,518, 576; 2,526,504; 2,540,596; 2,690,780; and 3,093,614. Addi-tionally, various dioxime compounds have been utilized such as those set forth in U. S. Patent Numbers 2,969,3~1; 3 9 037, 95~; 3,160,595; and P,ritish Patent 896,309. Yet another class - of additives or compounds are the diesters of 5-norbornene as set forth in U. S. Patent Numbers 3,817,883 and 3,843,613.
Another prior art patent is U. S. Patent 3,562,303 to Smith and McFadden, which relates to increased green strength of polyisoprene rubbers or copolymers of isoprene rubbers through a partial cure. That is, the polymer or co-: 15 polymer actually cross-links and thus is cured by using from 10 percent to 30 percent of the total amount of sulfur re-quired to effect complete vulcanization and from 10 percent to 50 percent of the total amo~mt of accelerator required to effect such vulcanization. Thus, thls paten~ does not re-late to a blend of rubber polymers but solely to copolymers wherein any green strength improvement is solely through a partial sulfur cure.
SU~IMARY OF THE INVENTION
It is, therefore, an object of an aspect of the pre-sent invention to provide elastomer blends having improved green ~strength.
:
,`,,j,l,~,....
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It is an object of another aspect of the present in-vention to provide improved green strength elastomer blends, as above ? wherein the blend contains elastomers of natural and synthetic cis-1,4-polyisoprene, butadiene, and a copolymer of styrene and bu~adiene.
It is another object of a further aspect of the present invention to provide improved green strength elastomer blends, as above, wherein the blend contains an amount of a polydimethylbutadiene compound or copolymers, terpol~mers or tetrapolymers of dimethylbutadiene.
It is another object of a further aspect of the present inve~tion to provide improved green strength elastomer blends, as above, wherein the elastomer contains a high amoLmt of cis units.
It is another objec-t of a further aspect of the pre-sent invention to provide improved green strength elastomer blends, as above, which are made according to a process and can readily be compounded with conventional compounding agents.
It is another object of a further aspect of the present invention to provide improved green strength elastomer blends, as above, which blends are conveniently used in the production of carcasses for radial tires.
It is another object of a further aspect of the present invention to provide improved green strength elastomer blends, as above, which can be utilized for truck tires.
Generally~ a process and composition for improving the green strength of blends of elastomers are characterized by providing an amount of a dimethylbutadlene compo~md, pro-~,~
viding an a~.ount of an elastomer, producing a physical and an uncured blend by mixing said dimethylbutadiene compound and said elastomer, said elastomer selected from the class consisting of natural rubber, synthetic elastomers, and com binations thereof, said synthetic elastomers made from mono-mers selected fror.l the class consisting of at least one conjugated diene having from 4 to 10 carbon atoms, olefins having from 2 to 14 carbon atoms and a diene having from to 10 carbon atoms, and combinations thereof, said blend ].0 having a glass transition temperature of from about 0C to about -100C, the amount of said dimethylbutadiene compound ranging from about 5 parts to about 80 parts based upon 100 parts of said blend, said dimethylbutadiene compo~mds being an elastomer selected from the class consisting of polydi-methylbutadiene, copolymers of dimethylbutadiene, terpolymers of dimethylbutadiene, and tetrapolymers of dimethylbutadiene, said polydimethylbutadiene made from monomers of dimethyl-butadiene, said copolymers, said terpolymers, and said tetra-polymers of dimethylbutadiene made from monomers selected.
.. Z from the class consisting of dienes having from ~ to 12 carbon atoms, and vinyl substituted aromatic hydrocarbons having from 8 to 12 carbon atoms, and combinations thereof.
Generally, a composition of elastomer blends hav-ing improved green strength,is characterized by: a physical and uncured blend of a dimethylbutadiene compound and an elastomer, the amount of said dimethylbutadiene compound ranging from about 5 parts to about ~0 parts per 100 parts of said blend; said elastomer selected from the class con-., ~
67~2 :
sisting of natural rubber, synthetic e].astomers, and combina--tions thereof; said synthetic elastomers made from monomers selected from the class consisting of at least one diene having from ~ to 10 carbon atoms, a diene having from 4 to 10 carbon atoms and an olefin having :Erom 2 to 1~ carbon atoms, and combinations thereof to Eorm a blend having a glass transition temperature of from about ~C to about -100C;
said dimethylbutadiene compound being an elastomer selected from the class consisting oE polydimethylbutadiene, copoly-mers of dimethylbutadiene, terpolymers of dimethylbutadiene, and tetrapolymers of dimethylbutadiene; said copolymers of dimethylbutadiene, said tetrapolymers of dimethylbutadiene made from monomers of dimethylbutadiene and monomers selected from the class consisting of dienes having from ~ to 12 carbon atoms, vinyl substituted aromatic hydrocarbon monomers having from 8 to 12 carbon atoms, and combinations thereof.
E2~I~ODIkIENTS OF T~E INVENTION
According to the concepts of the present invention, improved green strength is obtained by adding a polydimethyl-butadiene compound to various elastomers to form blends.
'rhese blends are particularly suitable for use as radial tire carcasses and may contain either natural or synthetic cis-l,~~polyisoprene.
The uncured blends of the present invention are made from monomers generally considered by those skilled in the art capable of form-lng rubbers in combination with one or more of the various polydime~hylbutadiene compounds which generally are a polymer o.E dimethylbutadiene, a copolymer, -5a-i7~
a terpolymer, or a -tetrapolymer of dimetbylbutadiene.
More specifically, the elastomers are natural cis-1,4-polyisoprene or synthetic e]as-tomers made from monomers selected from the group of compounds consisting of a-t least one conju-gated diene having from 1~ to about 10 carbon a-toms so t'hat diene copolymers, terpolymers, etc., may be utilized, monomers of dienes having from 4 to 10 carbon atoms with olefins having from 2 -to about 14 carbon atoms so that diene-olefin copolymers may be utilized, and combinations -thereof. A preferred group of olefin compounds are the vinyl substituted aromatic hydro-carbons containing from 8 to about 12 carbon atoms and include styrene, alpha-methylstyrene, ortho-, para-, and meta-methyl and ethylstyrene and t'he like. Of the non-aromatic olefin compounds, the compounas con-taining from 3 to 6 car'bon atoms are preferred. Specific examples of olefins include e-thane, pro-pene, butene, pentene, hexene, heptene, octene, nonene, decene, dodecene and the like. Concerning the diene compounds, the dienes having from 4 to 6 carbon atoms are preferred.
Specific rubber elastomers which may be utilized in the present invention include polybutadiene, both cis and trans, polyisoprene, both cis and trans, polypiperylene, co-polymers or interpolymers of the dienes, for example, isoprene and butadiene, bu-tadiene ànd piperylene, and the like and terpolymers of dienes such as butadiene, isoprene and piperylene.
Additionally, copolymers of a diene and an olefin may be uti-lized such as styrene and butadiene, alpha-methylstyrene and butadiene, butadiene and propene, butadiene and butene and the like. Of course, combinations of a diene-olefin with at least i;7~
another diene may also be used. Preferred elastomers of the present invention include natural or synthe-tic cis~
polyisoprene, polybutadiene, and the copolymer of styrene-butadiene.
When copolymers are prepared utilizing an olefin, the amount of the olefin range may vary from 0.1 to about 99 percent by weight. In other words, so long as a few diene monomers are contained in the monomeric mixture, copolymers can be formed. Generally, the weight percent of the olefin compound will usually range from 0.1 to about 55 percent wi-th a more desirable range being from about 10 percent to about 40 percent. A preferred range of the olefin compounds such as styrene or alpha-rnethylstyrene ranges from abou-t 15 percent to ` about 25 percent.
Considering the elastomers, they may ~lave any cis content. Thus, polybutadiene and SBR will generally have a cis-1,4 content of 30 or 40 percen-t or greater whereas natural or synthetic cis 1,4-polyisoprene will have a cis-1,4 content in excess of 80 percent and often 90 percent. High cis-1,4 content in elastomers is of-ten desirable since the compounded elastomer tends to be fairly elastic.
The elastomers of the present invention, which are utilized in the blends, may generally be prepared according to any conventional or common process or technique. For example, ; the elastomers may be prepared by anionic polymerization using organometallic compounds as cata]ysts such as butyllithium.
Additionally, the elastomers may be made according to a free radical emulsion process. In any of these processes as well 7%
as any others, the various parame-ters such as time, tempera--ture, pressure and -the like as well as the various catalysts and -techniques are well known to those skilled in -the art.
The dimethylbu-tadiene compound may be blended with the above-noted elastomers either alone, -that is as a polymer of dimethylbutadiene, or as a copolymer, terpolymer or tetrapolymer of dimethylbutadiene. These compounds, or any combination thereof, have been found to give vastly improved green strength to the above elas-tomers and thus the blends have much improved green strength.
The polymer of dimethylbutadiene may be prepared in any common or conventional manner and thus may be made according to a -free radical emulsiorl process or an anionic process and the like. In accordance wi-th any of these -techniques, a polymer is desired which has a number average molecular weight : range of from 1 x 105 to about 5 x 105 with a preferred range being from about 1.5 x 105 to about 2.5 x 10 .
The dimethylbu-tadiene homopolymer, copolymer, terpolymer or te-trapolymer of dimethylbutadiene may be made according to any common, conventional or normal manner or method well known to those skilled in the art. The monomers in addition to -the dimethylbutadiene monomers are selected from the group consisting of dienes having from 4 to 12 carbon atoms, vinyl substituted aromatic hydrocarbons having from 8 to 12 carbon atoms, vinylidene chloride, acrylonitrile, metha-crylic acid, vinyl pyridine, or the like and any combinations ; -thereof to form a copolymer~ terpolymer or tetrapolymer. In other words, if a terpolymer is to be made, any two 67~
monomers may be u-tilized from -the immedia-tely above se-t forth list in combination with a third monomer of dime-thylbutadiene.
Considering specifically copolymers of dimethyl-butadiene, the addi-tional monomer is preferably selected from the group consisting of dienes having from 4 to 12 carbon a-toms, acrylonitrile, vinylidene chloride, methacrylic acid, vinyl pyridine, or the like. Of -these, the dienes having from 4 -to 6 carbon atoms are preferred and the monomers of butadiene, isoprene, and piperylene are highly preferred.
The dimethylbutadiene compounds in the form of terpolymers are preferably made by polymerizing three different types of monomers. In addition to monomers of dimethylbu-tacliene, the other monomers preferably include butadiene and monomers selected from the class consisting of vinyl subs-ti-tuted aro-ma-tic compounds having from 8 to 12 carbon atoms, methacYylic acid and vinyl pyridine. The vinyl substituted aromatic com-pounds are desirably -those compounds which contain from 8 to 10 carbon atoms. Examples of such compo~mds include styrene, alpha-methylstyrene, ortho-, para- and meta-methyl and e-thylsty-rene. Preferred vinyl substituted aromatic compounds include styrene and alpha-methyls-tyrene. The ratio by weight of s-tyrene to -the butadiene may range from 0.1 to 55 percent of -the styrene-butadiene copolymer. ~ preferred range is from 5 to 35 percent with the preferred range being from 15 to 25 percent by weight. In the particular situation where the terpolymer contains a copolymer of styrene and butadiene, -the styrene and butadiene monomers may be polymerized in association with -the dimethylbutadiene monomers or the co-,~, I
'`
67~
polymer of styrene and butadiene may be added to monomers of dimethylbutadiene and polymerized. In general, the conten-t of any one monomer of the three monomers utilized in making the terpolymer may generally range from about 1 percen-t to about 98 percent by weight.
An important aspect of the presen-t invention is tha-t an amount of the dimethylbutadiene compound, be it a dimethyl-butadiene polymer or a copolymer, a terpolymer or a tetra-polymer thereof, may be added to the above elastomers such as the preferred elastomers of na-tural and synthetic cis-1,4-polyisoprene, polybutadiene and a copolymer of styrene and a butadiene~ in such an amount so -that glass transition tempera-ture of the blend will range from about 0C to about -100C
with a preferred range being from about -20C to abou-t -80 C.
As known -to those skilled in the art, the amounts of dimethyl-butadiene polymer, copolymers, terpolymers or tetrapolymers thereof will vary depending upon exact makeup of the copolymer, the terpolymer or the tetrapolymer. Of course, an amount of a particular copolymer, terpolymer or tetrapol~ner when added to the elastomer to give a desired glass transition ternpera--ture can be readily calculated.
Generally, it has been found the copolymers, -ter-polymers or te-trapolymers of dimethylbutadiene have a glass transition -temperature usually within a range of from between -20 C to about -80 C. Thus, at least 5 parts to about 80 parts by weight of the copolymer, terpolymer or tetrapolymer are utilized with a preferred amount being about 30 par-ts by weigh-t based upon lO0 par-ts of the total weight of the rubber blend -- 10 ~
(Dimethylbutadiene compound plus elastomer). An intermediate range is from 20 parts to 60 parts by weight per 100 par-ts of the total rubber blend. If solely the polymer of dimethyl-butadiene is utilized, since -the glass transition temperature(Tg) is about -5 C -to -~5C, an amount of this compound added to -the blend i5 generally at least 5 -to about 80 parts wi-th a more pre-ferred range being from about 20 parts -to about 60 par-ts by weight based upon 100 parts of the total weight of the rubber blend. Generally, an optimum amount of the dimethylbu-tadiene polymer or copolymers or terpolymers or tetrapolymers -thereof is approximately 30 percent by weight per 100 parts of rubber blend. This amount is largely based upon the fact that it gives very desirable physical proper-ty results as well as ease in mixing and the like upon compo-unding or processing.
Concerning the -tetrapolymers of dimethylbu-tadiene, in addition to the monomers of dimethylbutadiene, of course, three other types of monomers are necessary. As before, either all four of the monomers may be polymerized simultaneously or in various combinations thereof. Besides the monomers of dime-thylbutadiene, a remaining preferred class of monomers are the vinyl subs-titu-ted aromatic hydrocarbons containing from o to 12 carbon atoms. The desired range, examples of such compounds and, examples of specific preferred compounds are the same as set forth above. Another group of preferred monomers is butadiene which, in association with the vinyl substituted aromatic compounds, will generally form copolymers such as butadiene-styrene. The range of the s-tyrene to the butadiene is the same as previously set forth above. The ,~y.' fourth remaining preferred monomer may be selec-ted frorn the group consisting of me-thacrylic acid and vinyl pyridine. The total amount of any one const;tuent of the four making up the tetrapolymer may range from l percent to 97 percen-t. As no-ted above, the important factor is that an amount of the tetrapolymer be utilized so that the glass transition tempera-ture range of the blend will be between 0C and -100C with an amount as noted above of at least 5 percent by weight of the tetrapolymer being required based upon the total weight of the rubber blend.
The particularly dime-thylbutadiene compouna or plur-ality of such compounds are mixed with the particular or plural-ity of the elastomers in any conventional or common manner, method or process such as on a mill a-t common or conventional temperatures well known to -those skilled in the art. It is -to be understood -that by such mixing, the elastomer and the dime-thylbutadiene compound are merely mixed and not poly-merized since the blend is ac-tually a physical blend of -two types of components. Typically, during the mixing process or step, -the blend is also compounded. That is, various compounds and additives are added to the blend to improve streng-th, modulus, ease of processing, reduction of oxidation and the like. Thus, typical amounts of various compounds such as carbon blacks, various clays, various silicas, various oils including aliphatic and aromatic oils, various antioxidan-ts and the like are added and mixed -together as on a mill. The various types of additives desired are well known -to those skilled in the art and will tend to vary as to the type and amount depending on the desired end use of the - 30 blend. Additionally, various accelerators such as zinc oxide and curing agents such as peroxides or sulfur curatives may ~LC~Q~2 be added. However, -they are not ini-tiated or vulcanized during the mixing process according to the present inventlon.
Typically, the compounded blends are then extruded, molded or shaped by any method into a desired form such as the carcass - of a tire.
For the purposes o~ the present invention, it is to be understood that by the term "natural rubber" it is meant the rubber compounds which occurs in and is produced by nature and chemically speaking is (natural) cis-1,4-polyisoprene.
This compound, as well known to those skilled in the ar-t, is chemically identical and has very similar physical properties ` -to manmade or synthetic cis-l,L~ polyisoprene except that for some reason natural rubber has much better green strength.
Hence, it is very desirable in the manu~acture of -tire car-casses and the like.
The improved green strength elastomers of the present inven-tion are generally further blended with either natural rubber (natural cis-l,L~-polyisoprene) or a synthe-tic elastomer.
For example, if a synthetic elastomer contains a dimethylbuta-diene compound in accordance with the present invention, it will have improved green s-trength. However, as known to those skilled in the art, it is generally desirable to add and blend an amount o~ natural rubber to the synthe-tic elastomer.
Such a blend is generally a common and conventional practice in the tire industry and generally produces good tire car-casses as well as treads. 0-~ course, since the synthetic elastomer contains a dimethylbutadiene compound, the resulting blend con-taining the natural rubber will also have improved green strength.
. .
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- On the other hand, if natural rubber is utilized, it is desirable to generally blend it with a syn-thetic elas-tomer in order to lower -the hysteresis (heat generation) and to ob-tain other favorable attributes as known to -those skilled in the art. However, since synthetic elastomers general]y have poor low green strength in comparison to natural rubber, the synthetic elastomers will lower the overall green strength of the natural rubber synthetic elastomer blend. Thus, in accordance with the presen-t invention, the use of a dimethyl-butadiene compound with the natural rubber will restore the green strength reduction caused by the synthetic elas-tomer.
Since the dimethylbutadiene compound is a synthetic elastomer itself, i-t can therefore be used solely or exclusively to overcome the hysteresis problem and ye-t impart good green s-trength to the blend.
The blends of the present invention which have greatly improved green strength are particularly suitable for use in the carcasses of tires and especially for truck tires.
Other uses include conveyor belts, hoses, shoe soles and other typical industrial uses.
The invention will be better unders-tood by reference to the following examples and data.
- EX~lPLE I
A typical recipe for the e~ulsion polymerization of .. - 2,3-dlme-th.ylbutadiene and its copo~lymers, terpol~mers and : tetrapolymers is as follows based on a lOQ gram monomer charge of 2,3-dimeth.ylbutadiene:
. RECIPE A
- GRAMS
CHA~GF. A Water 192.
8Q percent of Rosin acid 2.5 Tamol N (:a trademark of Rohm & Haas) a sodium salt of a condensed naphthalene sulfonic acid 0.3 Sodium or potassium phosphate 0.25 - Fatty acld 2.1 Potassium hydroxide 0.40 CHARGE B 2,3-dimethylhutadiene 95.
t-nodecyl mercaptan 0.05 CHARGE C Water 8.
. . 15 Sulfuric acid 0.002 Ferrous sulfate 0.025 Ethylene-dlamine tetraacetic acid (.34 percent~ 0.2 Sodium ormaldehyde sulfoxylate 0.1 Sodium hydrosulfite 0.01 . _HARGE D 2,3-dimethylbutadiene 5.
50 percent para-menthane hydroperoxide 0.16 ML
CHARGE E Water 4.4 41 percent sodium dimethyl dithiocarbamate 0.44 85 percent diethanol hydroxyl-amine 0.044 Charge A is the first char~e to a vessel and desira-bly maintalned at a pH of about 10 to about 11 due to the par-~ 25 :.
. -15 .~3 i;72 ticular soap system utilized. Generally, any conventiona:L
sodium salt of an aromatic sulfonic acid may be used. After Charge A, Charge B is added, then Charge C and then Charge D.
Preferably, all the monomers being solely the 2,3-dimethylbuta-diene or the monomers for forming copolymers, terpolymers or tetrapolymers are first washed in a caus-tic solution and then in water. If a copolymer, terpolymer, etc. is made, the recipe is basically changed only by adding the comonomer charge, etc.
be-tween steps A and D. The temperature of -the polymeri~ation is usually be-tween 40F and 50F although higher temperatures as up to approximately 150F can be utilized due to the low cross-linking constant of dimethylbutadiene. A~ter approxi-mately 50-95 percent of monomer conversion occurs depending on end use of the desired blend and other ~ac-tors well known to those skilled in the ar-t, the polymerization is stopped by the addition of Charge E. The resu~Lting latex is steam stripped, salt-acid coagulated or alum coagulated and then dried to ob-tain the dimethylbutadiene compound. Of course, it is to be understood that the above recipe is only an illustration in that the amount as well as the type of various ingredients can vary a subs-tantial amount to achieve many items such as varying molecular weight, molecular weight distribution, rate of polymerization and -the like.
Another recipe which may be utilized to produce a dimethylbutadiene compound in accordance with -the present invention is set forth in Recipe B.
';`
RECIPE s GRAMS
CHARGE A Water 183.
- Sodium sulfate 0.15 Sodium hydroxide 0.22 Linear alkyl sulfona.te e.g. LAS 9~ (trademark~
made by Pilot Chemical Co. 0.5 to 5.0 : CHARGE B Water 5.
Sulfuric ~cid 0.002 Ferrous sulfate 0.025 : Ethylenediamine tetraacetic - acid (:34 percentl 0.2 Sodium formaldehyde sulfo.xylate 0.1 Sodium hydrosulfite 0.01 CHARGE C 2,3-dimethylbutadiene 95.
t-dodecyl mercaptan 0.05 CHARGE D 2,3--dimethylbutadiene 5.
50 percent para-menthane hydroperoxide 0.16 ML
CHAR~E E Water 4.4 41 percent sodium dimethyl dithiocarbamate 0.44 85 percent diethanol hydroxylamine 0.044 B.asically, the polymerization is conducted in a manner as set forth above with reference to Recipe A. O~
course, dimethylbutadiene copolymers, terpolvmers, etc., mav be made simply by adding the desired amount of various monomers such as hutadiene, vinyl pyridine, methacrylic acid, isoprene, and the like. Of course, as before, the ingredients, the temperatures, and the like can be varied considerably to ob-~- tain polymers containing various molecular weights and processa-bility.
: ~n advantage o~ Recipe B is that the soap system is more versatile in t~at the latex is stable ove:r a wide range of pH ~e.g. from 2 to 11) with the p~ being adjusted :
. .
'~
7;2 by tbe use of any conventional linear alkyl sulfona-te addition.
The dimethylbutadiene compound be it a homopolymer, a copolymer, a -terpolymer, etc. is then blended with any elastomer, either natural or syn-thetic, as set forth in the specification. If na-tural rubber is used, it can be obtained from natural sources as well known to those skilled in the art.
If a synthetic elastomer is used, the method and preparation is well known to those skilled in -the art. For example, if the elastomer is synthetic cis~
polyisoprene, a preferred catalyst such as triisobutyl aluminum/diphenyl ether/TiC14 is u-tilized having a molar ratio of 1/1/1. The preform catalyst is added to a solution of isoprene in hexane solvent (20 percent by weight of solvent) and the polymeri~ation is allowed to proceed at approximately 25-30 C.
After about 70 to 80 percent conversion, the reaction may be s-topped with tetraethylene pen-tamine. For protection, a hindered phenol antioxidant is added. A dry elastomer is obtained by steam s-tripping followed by extrusion drive. As with -the preparation of the dimethylbutadiene compound, various parameters may be varied, all within the knowledge of those skilled in the art.
In accordance with the present invention, natural rubber (natural cis-1,4-polyisoprene) was blended with polydimethylbutadiene which was made in accordance with Recipe A. In this formulation, the polydimethylbutadiene also consti-tuted the synthetic elas-tomer. The blending was achieved by mixing the elastomer and the polydimethylbutadiene in a Brabender for approxima-tely six minutes along with typical compounding ingredients as set forth in Table I. The Tg of the blend ranged from -50C to -60C.
:' .
'i?,~,; ' 67~2 ~ ~ o O ~ O ~ rl H IS\
H
L~ O
E~ O o ~ o ~ r~ r~
~ ¢l ~ ~ I ,~
P~
1- l u~ Lr\ o 0~ O O C-- O ~ r~ ri L
~1 V
H
" C) :~
. q~
',~ ~ ~
^ ~rl r~
~ rl E~
~i, ~ ~ 11 ~
1~1 O~rl ~ r~rJ
H t~ ~ 'O
~!u~
H ~r~ ~ O a) ~ 1~
O ~OCJ O-1~ ~
~~rl ~ 1 r ~ rl O
r1r~H+~ O ~l ~a~ Iu~
~rl O H ~ rl V ~V ~ Pi ~p~ V~ ~
After compounding, the samples were pressed at 200 psi at 200 F for 15 minutes, water cooled, then irnmedia-tely clicked for dumbbells. Dumbbells having a thickness of approximately 1/10 inch were tes-ted on an Instron using a cross-head speed of 20 inches per minute. The following resul-ts were ob-tained.
TABLE II
-GREEN STRENGTE, PSI CONTROL A. B.
. . .
Initial 128 228 252 1/l~ 125 312 362 Tensile @ Break 186 514 674 Elongation @ Break 480 979 690 As apparent from Table II, Compounds A and B gave vastly improved tensi:Le strength, total elongation as well as improved green streng-th at ini-; t:lal ]./4, 1/2 and 3/4 percent of total elonga-tion.
EXAMPLE II
In a manner similar -to Example I, natural rubber was blended with either synthetic cis-1,4-polyisoprene, or SBR (styrene butadiene rubber), or a copolymer of dimethylbutadiene and butadiene, or a copolymer of dimethyl-butadiene and methacrylic acid in amounts as set forth in Table III. The polydimethylbutadiene was made in accordance with Recipe A and -thus reacted in a conventional manner to form the copolymer with either butadiene or meth-acrylic acid. As apparent from Table III~ the dimethylbutadiene copolymer also consti-tu-ted the sole synthe-tic elastomer which was added to the natural rubber. The blending was achieved by mixing the various elastomers set forth in a Brabender along with the typical compounding ingredients set forth in Table III for approximately six minutes.
%
o u~ o ~ ~ O ~ H r; Ll~
æ ~ ,~, , , r l -J
H
,_ ~ _~
F~ ~0 U~ ~ O
H ~ d . ., r l r~
O ~ I I rl ~_ C~
U~ ~_ ~_ E~ H ~
~i H rl ~ Lr~ O
i-- o ~ ri r; Lt~
æ ~ I I ~ r-l ~ C\l C~ ~O
H ;~ ~
~0 r-l O u~ O~ ~
E-l O O ~ o ~ r-lri U~ c~ r~
æ ~ ~ ~ I r~ rl H O CO d H _~ t~l H H ~~ C) ~ a) ~
~rl C) d ~
C) rJ r.i . ~rl r~ I
. ~ d d :, ~, ~ ~ a) : d ~_ d ~ ;~
P
~I
d ~ ,~ '~ ~ H
:: ~I co, I ~ ;~
~ ~f ~ ~rl ~rl F~l V ~r~ æ d rJ rd ~1 iV ~rl O r~ rd q-l q-l H 5-1 rd 1-1 ~rl rl ~1 P~ d 0~ 0 P I u~ Q ,J u~
C~ ~r~ r~ r~
æ ~r~ ~ O a) p~ r~
H rO ,~ rO ~ ~r~ ~LI rO l--P~ ~ P~ ~rl ,!4 ~ rd P~ P~
Ia) I .. ~ rl O O
r~
~ d " H ~ r-l ~rl O
Ul H U~ ~; Pi h rd O (1) d 11 11 r~ pO c~ ~ d ,~
~ 21 ~' ~Q~7~
The various blends se-t forth in Table III generally had a Tg o~
frorn -50 C -to about -60 C. Sarnples of each blend were pressed a-t 200 psi at 200 F for 15 minutes, water cooled, and -then immedia-tely clic~ed for dumb-bells. Dumbbells having a thickness of approxima-tely 1/10 inch were -tested on an Instron using a cross-head speed of 20 inches per minute. The follow-ing results were obtained.
TABLE IV
I II
(Control) (Control) III IV
Mooney 47 5 5 53 100% Elongation, psi 34 39 49 65 300~ Elongation, psi L~2 46 64 124 Tensile Strength, psi 227 227 280 538 Elongation at break, psi 930 1106 1169 807 As readily apparen-t from Table IV, compo~mds III and IV gave im-proved green strength characteris-tics such as improved tensile strength, im-proved elongation as well as improved elongation at break.
While in accordance with the patent statutes, only the preferred embodiments have been illustrated and described in detail, it is to be under-stood that the invention is not lirrlited thereto; the scope of -the inven-tion ; being measured by the scope of -the a-ttached claims.
Claims (36)
1. A process for improving the green strength of blends having good strength of elastomers which is characterized by providing an amount of a dimethylbutadiene compound, providing an amount of an elastomer, producing a physical and an uncured blend by mixing said dimethylbutadiene compound and said elastomer/
said elastomer selected from the class consisting of natural rubber, synthetic elastomers, and combinations thereof, said synthetic elastomers made from monomers selected from the class consisting of at least one conjugated diene having from 4 to 10 carbon atoms, olefins having from 2 to 14 carbon atoms and a diene having from 4 to 10 carbon atoms, and combinations thereof, said blend having a glass transition temperature of from about 0°C to about -100°C, the amount of said dimethylbutadiene compound ranging from about 5 parts to about 80 parts based upon 100 parts of said blend, said dimethylbutadiene compounds being an elastomer selected from the class consisting of polydimethylbutadiene, copolymers of dimethylbutadiene, terpolymers of dimethylbuta-diene, and tetrapolymers of dimethylbutadiene, said polydimethylbutadiene made from monomers of dimethylbutadiene, said copolymers, said terpolymers and said tetrapolymers of dimethylbutadiene made from monomers selected from the class consisting of dienes having from 4 to 12 carbon atoms, and vinyl substituted aromatic hydro-carbons having from 8 to 12 carbon atoms, and combinations thereof.
said elastomer selected from the class consisting of natural rubber, synthetic elastomers, and combinations thereof, said synthetic elastomers made from monomers selected from the class consisting of at least one conjugated diene having from 4 to 10 carbon atoms, olefins having from 2 to 14 carbon atoms and a diene having from 4 to 10 carbon atoms, and combinations thereof, said blend having a glass transition temperature of from about 0°C to about -100°C, the amount of said dimethylbutadiene compound ranging from about 5 parts to about 80 parts based upon 100 parts of said blend, said dimethylbutadiene compounds being an elastomer selected from the class consisting of polydimethylbutadiene, copolymers of dimethylbutadiene, terpolymers of dimethylbuta-diene, and tetrapolymers of dimethylbutadiene, said polydimethylbutadiene made from monomers of dimethylbutadiene, said copolymers, said terpolymers and said tetrapolymers of dimethylbutadiene made from monomers selected from the class consisting of dienes having from 4 to 12 carbon atoms, and vinyl substituted aromatic hydro-carbons having from 8 to 12 carbon atoms, and combinations thereof.
2. A process according -to claim 1 including adding compounding agents and mixing said compounding agents with said blend.
3. A process according to claim 1 wherein said copolymers of dimethylbutadiene are made from monomers of dimethylbutadiene and monomers selected from the class con-sisting of dienes having from 4 to 12 carbon atoms.
4. A process according to claim 3, wherein said terpolymers and tetrapolymers of dimethylbutadiene are made from monomers of dimethylbutadiene, diene monomers having from 4 to 12 carbon atoms, and monomers selected from the class consisting of vinyl substituted aromatic hydrocarbons having from 8 to 12 carbon atoms.
5. A process according to claim 4 including adding compounding agents and mixing said compounding agents with said blend.
6. A process according to claim 4 wherein said diene monomers utilized in making a copolymer, a terpolymer,or a tetrapolymer of polydimethylbutadiene are selected from the class consisting of butadiene, isoprene and piperylene, said monomers forming said elastomers are selected from the class consisting of conjugated dienes having from 4 to 6 carbon atoms, vinyl substituted aromatic compounds having from 8 to 12 carbon atoms and conjugated dienes having from 4 to 6 carbon atoms, and combinations thereof.
7. A process according to claim 6 wherein said vinyl substituted aromatic hydrocarbon monomers of said dimethyl-butadiene compound are selected from the class consisting of styrene and alpha-methylstyrene.
8. A process according to claim 7 including adding compounding agents and mixing said compounding agents with said blend.
9. A process according to claim 7 wherein said di-methylbutadiene compounds are selected from the class consisting of polydimethylbutadiene, a copolymer of dimethylbutadiene and butadiene, a copolymer of dimethylbutadiene and isoprene, a copolymer of dimethylbutadiene and piperylene, a terpolymer of dimethylbutadiene, butadiene and styrene, and wherein said elastomer is selected from the class consisting of natural rubber, synthetic cis-1,4-polyisoprene, polybutadiene and a copolymer of styrenebutadiene.
10. A process according to claim 1, wherein the glass transition temperature of said blend ranges from about -20°C to about -80°C.
11. A process according to claim 10, wherein said elastomer is made from monomers selected from the class consisting of conjugated dienes having from 4 to 6 carbon atoms, vinyl substituted aromatic compounds having from 8 to 12 carbon atoms and conjugated dienes having from 4 to 6 carbon atoms, and combinations thereof.
12. A process according to claim 10, wherein said copolymer of dimethylbutadiene is made from monomers of dimethylbutadiene and monomers selected from the class con-sisting of dienes having from 4 to 12 carbon atoms.
13. A process according to claim 12, wherein said terpolymers and said tetrapolymers of dimethylbutadiene are made from monomers of dimethylbutadiene, diene monomers having from 4 to 12 carbon atoms, and monomers selected from the class consisting of vinyl substituted aromatic hydrocarbons having from 8 to 12 carbon atoms.
14. A process according to claim 13, including adding compounding agents and mixing said compounding agents with said blend.
15. A process according to claim 13, wherein said vinyl substituted aromatic hydrocarbon monomers have from 8 to 10 carbon atoms.
16. A process according to claim 13, wherein said diene monomers utilized in making said copolymer, said terpolymer and said tetrapolymers of polydimethyl-butadiene are selected from the class consisting of butadiene, isoprene, and piperylene, said monomers form-ing said elastomers are selected from the class consisting of conjugated dienes having from 4 to 6 carbon atoms, vinyl substituted aromatic compounds having from 8 to 12 carbon atoms and conjugated dienes having from 4 to 6 carbon atoms, and combinations thereof.
17. A process according to claim 16, wherein said vinyl substituted aromatic hydrocarbon monomers forming said elastomers as well as said copolymers, terpolymers, and tetrapolymers of polydimethylbutadiene are selected from the class consisting of styrene and alpha-methylstyrene.
18. A process according to claim 15, wherein said elastomer is selected from the class consisting of natural rubber or synthetic cis-1,4-polyisoprene, polybutadiene and a copolymer of stvrene-butadiene.
19. A process according to claim 16, wherein the amount of sald dimethylbutadiene homopolymer, said dimethyl-butadiene copolymers, said dimethylbutadiene terpolymers, and said dimethylbutadiene tetrapolymers is from about 20 to about 60 percent by weight based upon the total weight of said blend.
20. A process according to claim 19, wherein said dimethylbutadiene compound is selected from the class consisting of dimethylbutadiene, a copolymer of dimethyl butadiene and butadiene, a copolymer of dimethylbutadiene and isoprene, a copolymer of dimethylbutadiene and piperylene, a terpolymer of dimethylbutadiene, butadiene and styrene.
21. A process according to claim 20, including adding compounding agents and mixing said compounding agents with said blend.
22. A process according to claim 20, wherein said dimethylbutadiene compound is selected from the class consisting of polydimethylbutadiene, a copolymer of dimethylbutadiene and butadiene, a copolymer of dimethyl-butadiene and isoprene, and a terpolymer of dimethylbutadiene, butadiene and styrene.
23. A process according to claim 22, wherein said butadiene compound is selected from the class consisting of polydimethylbutadiene, and a copolymer of dimethylbutadiene and butadiene.
24. A process according to claim 23, wherein the amount of elastomer is approximately 70 percent by weight and the amount of said dimethylbutadiene compound is approxi-mately 30 percent by weight.
25. A composition of elastomer blends having im-proved green strength, which is characterized by:
a physical and uncured blend of a dimethylbutadiene compound and an elastomer, the amount of said dimethylbuta-diene compound ranging from about 5 parts to about 80 parts per 100 parts of said blend, said elastomer selected from the class consisting of natural rubber, synthetic elastomers, and combinations thereof, said synthetic elastomers made from monomers selected from the class consisting of at least one diene having from 4 to 10 carbon atoms, a diene having from 4 to 10 carbon atoms and an olefin having from 2 to 14 carbon atoms, and combina-tions thereof to form a blend having a glass transition temperature of from about 0°C to about -100°C, said dimethylbutadiene compound being an elastomer selected from the class consisting of polydimethylbutadiene, copolymers of dimethylbutadiene, terpolymers of dimethylbuta-diene, and tetrapolymers of dimethylbutadiene, said copolymers of dimethylbutadiene, said tetra-polymers of dimethylbutadiene made from monomers of dimethyl-butadiene and monomers selected from the class consisting of dienes having from 4 to 12 carbon atoms, vinyl substituted aromatic hydrocarbon monomers having from 8 to 12 carbon atoms, and combinations thereof.
a physical and uncured blend of a dimethylbutadiene compound and an elastomer, the amount of said dimethylbuta-diene compound ranging from about 5 parts to about 80 parts per 100 parts of said blend, said elastomer selected from the class consisting of natural rubber, synthetic elastomers, and combinations thereof, said synthetic elastomers made from monomers selected from the class consisting of at least one diene having from 4 to 10 carbon atoms, a diene having from 4 to 10 carbon atoms and an olefin having from 2 to 14 carbon atoms, and combina-tions thereof to form a blend having a glass transition temperature of from about 0°C to about -100°C, said dimethylbutadiene compound being an elastomer selected from the class consisting of polydimethylbutadiene, copolymers of dimethylbutadiene, terpolymers of dimethylbuta-diene, and tetrapolymers of dimethylbutadiene, said copolymers of dimethylbutadiene, said tetra-polymers of dimethylbutadiene made from monomers of dimethyl-butadiene and monomers selected from the class consisting of dienes having from 4 to 12 carbon atoms, vinyl substituted aromatic hydrocarbon monomers having from 8 to 12 carbon atoms, and combinations thereof.
26. A process according to Claim 24, including adding compounding agents and mixing said compounding agents with said blend.
27. A composition according to claim 25, wherein said monomers forming said elastomer is selected from the class consisting of conjugated dienes having from 4 to 6 carbon atoms, vinyl substituted aromatic compounds having from 8 to 12 carbon atoms and conjugated dienes having from 4 to 6 carbon atoms, and combinations thereof.
28. A composition according to claim 27, wherein said dimethylbutadiene compounds are selected from the class consisting of polydimethylbutadiene, a copolymer of dimethyl-butadiene and butadiene, a copolymer of dimethylbutadiene and isoprene, a copolymer of dimethylbutadiene and piperylene, and a terpolymer of dimethylbutadiene, butadiene and styrene.
29. A composition according to claim 28, including adding compounding agents and mixing said compounding agents with said blend.
30. A composition according to claim 28, wherein the amount of said elastomer is about 70 percent by weight and the amount of said dimethylbutadiene compound is about 30 percent by weight.
31. A composition according to claim 30, including adding compounding agents and mixing said compounding agents with said blend.
32. A composition according to claim 27, wherein said copolymer of dimethylbutadiene is made from monomers of dimethylbutadiene and monomers selected from the class consisting of dienes having from 4 to 12 carbon atoms.
33. A composition according to claim 27, wherein said terpolymers and said tetrapolymers of dimethylbutadiene are made from monomers of dimethylbutadiene, diene monomers having from 4 to 12 carbon atoms, and monomers selected from the class consisting of vinyl substituted aromatic hydro-carbons having from 8 to 12 carbon atoms.
34. A composition according to claim 27, wherein said vinyl substituted aromatic hydrocarbon monomers of said dimethylbutadiene compound are selected from the class consisting of styrene and alpha-methylstyrene.
35. A composition according to claim 34, wherein said diene monomers forming said dimethylbutadiene compound are selected from the class consisting of butadiene, isoprene, and piperylene.
36. A composition according to claim 35, wherein said elastomers are selected from the class consisting of natural rubber, synthetic cis-1,4-polyisoprene, polybutadiene, and a copolymer of styrene-butadiene.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US692,267 | 1976-06-03 | ||
| US05/692,267 US4124546A (en) | 1976-06-03 | 1976-06-03 | Green strength of elastomers |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1100672A true CA1100672A (en) | 1981-05-05 |
Family
ID=24779904
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA277,097A Expired CA1100672A (en) | 1976-06-03 | 1977-04-27 | Green strength of elastomers |
Country Status (2)
| Country | Link |
|---|---|
| US (1) | US4124546A (en) |
| CA (1) | CA1100672A (en) |
Families Citing this family (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1603847A (en) * | 1977-09-09 | 1981-12-02 | Dunlop Ltd | Tyres |
| JPS57108144A (en) * | 1980-12-25 | 1982-07-06 | Japan Synthetic Rubber Co Ltd | Stabilized polyisoprene composition |
| US4626568A (en) * | 1985-08-08 | 1986-12-02 | Polysar Limited | Vibration and noise insulating rubber compositions |
| US4869968A (en) * | 1988-06-13 | 1989-09-26 | Monsanto Company | Rubber article comprising contiguous portions of an isoprene rubber composition and a butadiene rubber composition containing a polymeric activator |
| US6335392B1 (en) * | 1998-10-21 | 2002-01-01 | Sumitomo Rubber Industries, Ltd. | Outsole of shoes |
| US7294376B2 (en) * | 2003-08-26 | 2007-11-13 | The Goodyear Tire & Rubber Company | Tire with indicia |
| US8563656B1 (en) | 2012-11-08 | 2013-10-22 | The Goodyear Tire & Rubber Company | Method to improve green strength in elastomers |
| US20150096654A1 (en) | 2013-10-08 | 2015-04-09 | The Goodyear Tire & Rubber Company | Rubbery blend containing trans isoprene-butadiene copolymer |
| US10308792B2 (en) | 2013-10-08 | 2019-06-04 | The Goodyear Tire & Rubber Company | Rubbery blend containing trans isoprene-butadiene copolymer |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3337520A (en) * | 1962-10-22 | 1967-08-22 | Phillips Petroleum Co | Isoprene polymerization |
| US3400086A (en) * | 1965-06-21 | 1968-09-03 | Polymer Corp | Rubber blend |
| GB1193723A (en) * | 1968-03-15 | 1970-06-03 | Shell Int Research | Process for the preparation of Modified Synthetic Conjugated Diene Solution Polymers |
| US3629373A (en) * | 1969-10-14 | 1971-12-21 | Polymer Corp | Mastication of 2-alkyl butadiene-1 3-acrylic nitrile copolymer |
-
1976
- 1976-06-03 US US05/692,267 patent/US4124546A/en not_active Expired - Lifetime
-
1977
- 1977-04-27 CA CA277,097A patent/CA1100672A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| US4124546A (en) | 1978-11-07 |
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