US3814715A - Glass fiber size containing polyolefin emulsion - Google Patents

Abstract

AN AQUEOUS FORMING SIZE FOR TREATING A GLASS FIBER STRAND, SAID SIZE CONSISTING ESSENTIALLY OF A POLYPROPYLENE EMULSION, A TEXTILE LUBRICANT AND A COUPLING AGENT. THE POLYPROPYLENE EMULSION CAN CONTAIN SOME EMULSIFIED POLYETHYLENE. THE SIZED STRANDS CAN BE FURTHER COATED WITH AN AQUEOUS RUBBER ADHESIVE COMPOSITION IN PREPARATION FOR USE AS REIN FORCEMENT FOR RUBBER.

Description

Patented June 4, 1974 lClaim ABSTRACT OF THE-DISCLOSURE An aqueous" forming sizefor treating a glass fiber strand, said size consisting essentially of a polypropylene emulsion, a textile lubricant and a coupling agent. The polypropylene emulsioncan'contain' some emulsified polyethylene. The sized strands-can be further coated with an aqueous rubber adhesive composition in preparation for use as reinforcement'for"rubber.

This is a divisionor npeiieanenwser. No. 826,715 filed May 21, 1969, now U.S. Pat. 3,655,353.

FIELD- OF THEKINVENTION The present invention relates to'a glass fiber treatment. The invention particularly relates to a novel size for treating glass fibers which are to be used in various forms as a reinforcement for resinous and rubber products.

DESCRIPTION OF THEPRIOR ART A glass fiber strandj'is' compos'edjof'a multitude of fine glass fiIamentswhich are'"formje d by being drawn at a high rate of speed from molten cones of glass located at the tips of "small orificesjinfa "bushing such as shown in U.SfPat. o, 2 ,133,23s; Dn E r n rien, the filaments are coated whilemovingat peed'on the order of 5,000 re 205000 feet" per minnre tlr a; size which contains a binder to give thestrand integrity'forworkability for any standard textile 'orfreinforcenient use. If the strand does not havepropr, integrity, fuzzirig occurs during these operations and eventually'the strand breaks. The size also cont'ains 'a' lnb ricaritffor'the filaments to prevent destruction of the strarid by'abrasion of the individual filaments against each "oth'eror against fiber handling equipment 5 It is common practice 't'o'use glass fiber strands and glass fibercloth; as'a-reinforcement for resins. For such use, the-glass fibersare c o'ate'd with a coupling agent or finish material which makes the surface of the glass fibers substantive andcompatible-with the particular resins with which-they are to be employedbThese coupling agents .grea'tly'increase the dry and wet' hysical strengths of the glass fiber resin laminate. When the glass fibers are: usedin the form of strand, i.e., roving or chopped strand or twisted strand,for resin reinforcement, the coupling agent is usually combined with the size and applied with the size'to thefibers during their formation. The size employed isusually air-aqueous dispersion or emulsion of a-film forifiin'gfsyntheticresinous binder,- and a glass fibertextileli b1' ica1it Roving is formed by unwinding; pl'uralit of strands from forming package's mounted' dn a creel, combining thestrands in parallel formand winding the {strands a United States Patent ()fice from ringer formation upon removal from the forming package and resistance to fuzzing during the steps employed to make the twisted strand or roving and fabricate them into forms suitable for use as a resin reinforcement.

It is desired that a treatment be provided for glass fiber strand which will render the strand capable of 1) being economically processed into a form suitable for reinforcing resins and elastomers (rubber) and (2) providing improved physical properties such as increased strength to glass fiber reinforced resinous and elastomeric products. More specifically, it is desired that a strand be provided with a size which permits the strand to be processed without ringer formation and fuzzing and which is compatible with resins or elastomeric adhesives so as to provide improved physical properties to the reinforced products.

An object of this invention is to provide glass fiber strand which has been treated with a size with good Wetout properties. It is desirable in the formation of glass fiber-resin laminates that the resin completely impregnate the strand and wet the surfaces of the fibers as quickly as possible in order to reduce the time required to make the laminates as well as to provide a laminate with maximum possible strength. It is desirable in the formation of elastomer-reinforcing glass fiber cord that the rubber adhesive completely impregnate the cord and Wet the surfaces of the individual fibers in order to provide good adhesion between the cord and elastomer to be reinforced and to provide good flexural and compressive strength properties to the reinforced elastomer product. This is especially important in the manufacture of tire cord.

It is another object of this invention to provide a glass fiber strand which is treated with a size and which can be twisted, plied and woven into fabrics for use as a resin or elastomer reinforcement without requiring heat cleaning and finishing of the cloth prior to such use as required when the glass fibers have been formed with a starch containing size.

SUMMARY OF THE INVENTION These, and other objects are accomplished by the practice of this invention which, briefly, comprises treating glass fiber strands during their formation with an aqueous size consisting essentially of about 2 to 15 percent by weight of an aqueous polyolefin emulsion selected from the group consisting of polypropylene and polypropylenepolyethylene emulsions, 0.1 to 2.0 percent by weight of a coupling agent and 0.2 to 4 percent by weight of a textile lubricant. The aqueous size has a viscosity which has been conventionally found to be suitable for glass fiber strand forming sizes to permit adequate pick-up of size by the strand to obtain strand integrity and prevent destruction of the strand by abrasion of the individual fibers against eachother.

' The solids content of the polyolefin emulsion is composed of about 25 to 100 percent by weight of polypropylene and 0 to-75 percent by weight of polyethylene. The polyethylene is employed to help stabilize the emulsion of the polypropylene As greater percentages ofpolyethylene are employed in the emulsion, it is preferred that tubular support 'in-a'inanner such that- 'the c'dmb ned package and-winding it' oh a tWist-e'r-bobbirffil isthere fore necessary that the strand *havegood integrity; freedom the'softening-point of the polyethylene'be higher .inorder to obtain good adhesion in glass fiber reinforced elastomers; Y

The polypropylene-employed in the size :has an'average molecular weight inthe range ofabout '5,3-00'to-7,300',-a Ring andBall softening point of 1-50 to 175 C., a density of=0.85 to 1 gram per cubic'cent'imeter and a penetration hardness grams/5 seconds/72 'F.) in tenths of a millimeter of 0.01 maximum; The polyethylene employed in the size has an average molecular weight in the range of about 2,000 to 10,000, a Ring and Ball softening point of about 100 to 175 C., a density of 0.85 to 1 gram per cubic centimeter and a penetration hardness (100 grams/ 5 seconds/25 C.) in tenths of a millimeter of 0.2 to 2.5.

Some examples of polypropylene and polyethylene which are suitable for use in the invention are as follows.

(1 Polypropylene:

Molecular weight 6,300. Ring and Ball softening point 160 C. Density (grams per cubic centimeter) 0.9.

Penetration hardness (100 grams/5 seconds/72 F.), tenths of a milli- The emulsion is prepared by melting polypropylene (and polyethylene when used), adding suitable emulsifying agents with stirring and then adding water until the water in oil emulsion inverts to an oil in water emulsion. The emulsion contains about 20 to 40 percent by weight of solids (non-aqueous ingredients) based upon the weight of the emulsion. Suitable emulsifying agents include Triton X-100, Igepal C0630 and Tergitol. Polyolefin emulsions which are useful in the practice of the invention are commercially available and can be used merely by mixing the polypropylene emulsion, water, lubricant and coupling agent together in a mixing tank.

Coupling agents which may be used in the aqueous size compositions in the practice of this invention include silane and siloxane materials. For example, hydrolyzable vinyl, allyl, beta chloropropyl, phenyl, thioalkyl, thio-alkaryl, amino-alkyl, methacrylato, epoxy and mercapto silanes, their hydrolysis products and polymers of the hydrolysis products and mixtures of any of these are suitable for such use. Some of the silanes are disclosed in U.S. Pats. Nos. 2,563,288; 2,688,006; 2,688,007; 2,723,211; 2,742,378; 2,754,237; 2,776,910; 2,799,598; 2,832,754; 2,930,809; 2,946,701; 2,952,576; 2,974,062; 3,044,982; 3,045,036; 3,169,884; 3,207,623 and 3,211,684, the disclosures of which are incorporated herein by reference.

OBJECTS OF THE INVENTION Another class of coupling agents which has been found to be useful are the basic (hydroxy containing) metal salts of a strong mineral acid, such as, for example, a basic chromium chloride, basic chromium sulfate, etc. These compounds are ones having a trivalent metal ion selected from the group consisting of chromium, cobalt, nickel, copper and lead, at least one hydroxyl group attached to the metal, and at least one anion of a strong mineral acid attached to the metal (as well as coordinate complexes of these compounds and mixtures thereof).

Another type of coupling agent which may be used in .the practice of this invention is a complex compound of the Werner type in which a trivalent nuclear atom, such as chromium, is coordinated with an organic acid such as methacrylic acid, i.e., a methacrylic acid complex of chromic chloride. Such agents are described in U.S. Pat. No. 2,611,718. Other Werner type coupling agents having vinyl alkyl amino, epoxy, mercapto, thio-alkyl, thioalkaryl, and phenyl groups are suitable for incorporation in the size of the invention.

Mixtures of two or more of any of these coupling agents may be used.

The size may contain a textile lubricant. The lubricant is preferably cationic or non-ionic. Various conventional glass fiber textile lubricants can be used. The lubricant can-be a commercially available acid solubilized, fatty acid amide. This includes both saturated and unsaturated fatty acid amides wherein the acid group contains 4 to 24 carbon atoms. Also included are anhydrous, acid,

solubilized polymers of the lower molecular weight, un-

saturated fatty acid amides. A suitable material is the pelargonic acid amide of tetraethylene pentamine.

Another glass fiber lubricant which can be used in the size is an alkyl imidazoline derivative which includes;

compounds of the class u-alkyl N-amidoalkyl imidazolines which may be formed by causing fatty acids to react with polyalkylene polyamines under conditions which producering closure. The reaction of tetraethylene pentamine with stearic acid is exemplary of such reaction. These imidazolines are described more fully in U.S. Pat. No. 2,200,815. Other suitable irnidazolines are. described in U.S. Pats Nos. 2,267,965, 2,268,273 and 2,355,837.

The above cationic lubricants may be used in combina; tion with or replaced by a quaternary pyridinium com pound which may be represented by the general formula;

R4 at wherein X is an anion; R is an organic group containing from 1 to 30 carbon atoms selected from the group consisting of alkyl, arylalkyl, aryl, alkenyl and acyl; and R R R R and R are each members selected from the group consisting of hydrogen, alkyl, aryl, arylalkyl, heterocyclic, halogen, alkenyl, carboxylic, alkoxy, ketonic, amido, and substituted amido. Thus, the anionic group X may be, for example, chloro, fluoro, iodo, bromo, hydroxyl, nitrate, sulfate, phosphate, etc. The group R may be, for example, methyl, ethyl, butyl, hexyl, lauryl, oleyl, benzyl, phenyl, acetyl, propionyl, benzoyl, etc. The groups R R R R and R may be, for example, methyl, ethyl, propyl, cyclohexyl, furyl, pyrryl, benzyl, phenyl, chloro, bromo, iodo, fluoro, oleyl, methoxy, acetoxy benzoxy acetonyl acetamido etc. These compounds are prepared in accordance with methods common in the art by the quaternization of the corresponding pyridine bases such as pyridine, niacin, nicotin-amide, nicotine, nicotyrine, nikethamide, Z-benzylpyridine, 3,5-dibromopyridine, 4-chloropyridine, 3-ethylpyridine, 4-methoxypyridine, 3- phenylpyridine, 2-picoline, 3-picoline, 4-picoline, 2-picoline-4,6,dicarboxylic acid, 2,4-lutidine, 2,6-lutidine, 3, lutidine, 2,4-pyridine dicarboxylic acid, 4-ethyl-3-methylpyridine, 3 ethyl-4-methylpyridine, 2,4,6-trimethylpyridine, etc.; with for example, an alkyl halide. In a preferred embodiment, the R group in the above formula is an aliphatic hydrocarbon radical containing from 4 to 18 carbon atoms.

The size may contain a wetting agent. The wetting agent is preferably cationic or non-ionic and it may also serve as an additional lubricant. Any material which is conventionally known to be useful as such and will reduce the surface tension of the size so that it is about 25 to 35 dynes per square centimeter can be used. Such materials include cetyl or stearyl monoamine hydrochloride 'or acetate, dodecyl amine, hexadecyl amine and secondary and tertiary derivatives of the same, for example, dodecyl methyl amine and salts thereof. Other examples of suitable wetting agents are polyoxyethylene derivatives of a sorbitol fatty acid ester such as polyoxyethylene sorbitan monostearate or polyoxyethylene sorbitan trioleate. The amount of such wetting agent employed generally ranges from about 0.01 to 1 percent by weight of the aqueous size.

The total solids (non-aqueous) content of the size is about 2 to 20 percent by weight of the size, preferably about 3 to percent by weight of the size. In all events the amounts of the various ingredients should not exceed that amount which will cause the viscosity of the solution to be greater than about 100 centipoises at 20 C. Solutions having a viscosity of greater than 100 centipoises at 20 C. are very difiicult to apply to glass fiber strands during their formation without breaking the strand. It is preferred that the viscosity of the size be between 1 and 20 centipoises at 20 C. for best results. The pH of the solution may generally vary from about 3 to 8.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Typical examples of the best mode of carrying out the invention are shown in the following examples of sizes.

For resin reinforcement:

Example I Parts by weight Ingredients: (grams) 1) Polypropylene emulsion containing 25% by weight of polypropylene (molecular weight 6,300) and 6% by weight of emulsifying agents 5,000 (2) Polyvinyl alcohol (Elvanol 52-22 sold by Du Pont) 500 (3) Imidazolamine (Emery Industries 1200- 136) 200 (4) Methacryloxy propyl trimethoxy silane (A-174) 250 (5) Acetic acid 8 (6) Silicone defoamer (SAG-470) 3.8 (7) Water pH'=9.8.

Percent solids=6.3.

1 Suflicient to make 10 gallons of size.

For elastomer reinforcement:

Example 11 Parts by weight Ingredients: (grams) (1) Polypropylene polyethylene emulsion containing 12% by weight of polypropylene (molecular weight 6,300), 12% by weight of polyethylene (molecular weight 2,500) and 6% by weight of emulsifying agents (Abraze Ade sold by Proctor Chemical Percent= 6.65 by weight.

Example III A size as described in Example II utilizing 12% polyethylene having an average molecular weight of 6,500- 8,500 in place of the polyethylene listed in the example.

Example IV A size as described in Example II utilizing 18% polypropylene (molecular weight 6,300) and 7% polyethylene (molecular weight 2,500) in the emulsion instead of the amounts of the polypropylene and polyethylene listed in the example.

The procedure for preparing the size of this invention is exemplified by the following procedure for making the size set forth in Example H. The polyolefin emulsion is poured in a size mixing tank. The SCC-137 is dissolved in hot water (140-150 F.) and added to the mixing tank. The Alamine 7-D is dissolved in hot water with acetic acid and added to the mixing tank. The Versamid 140 is dissolved in hot water with acetic acid and added to the mixing tank. The A-l and SAG-470 and water are added consecutively with stirring to the mixing tank and the size is then ready for use.

The sizes are applied to the individual glass fibers during their formation in the conventional manner. The sizes are applied to the individual fibers just after their emergence from orifices in an electrically heated, platinum alloy bushing containing molten glass. The sizes are applied to the filaments prior to the time they are grouped together to form a strand by means of a roller applicator which is partially submerged in the size contained in a reservoir. Such an applicator is shown in more detail in US. Pat. No. 2,728,972. The fibers are grouped into a strand by a graphite guide and wound around a forming tube rotating at approximately7,500 r.p.m. to produce a strand travel of approximately 12,000 to 15,000 feet per minute. Other methods of applying the size to the strand of glass fibers, such as pad applicator, may be employed and the strand may be formed by means other than winding on the forming tube, such as by means of a pair of rotating wheel pullers which direct the strand into a suitable collecting device.

The glass fiber strands wound on the forming tube are then dried. This may be done by heating them at a temperature and for a length of time sufiicient to reduce the moisture level to that appropriate for further processing, for example, at about room temperature for 48 hours for twisting or 8 to 12 hours at 270F. for producing roving. This drying causes the coupling agents to fix themselves to the glass surface and to produce the degree of strand integrity and moisture level required for processing the strand into roving, yarn, cord, woven cloth or woven roving. The solids content of size on the strands averages about 0.2 to 2.0 percent by weight, preferably about 0.50 percent by weight.

Glass strands sized with a size such as described in Example I are particularly useful for reinforcement of thermoplastic and thermosetting resinous products. Such reinforced products have good tensine and fiexural strength. Increased physical strength, although an important and significant factor, represents only one benefit to be derived through the use of the subject sizes. Other equally beneficial and desirable aspects are the versatility and economic advantages obtained through the use of these sizes. Prior to introducing cloth woven from fiber glass strands having starch based sizes thereon into resins for reinforcement purposes, it is necessary to remove the size by literally burning it off in a heat cleaning process and subsequently apply a coupling agent to the filaments to serve as a coupler between the reinforcing fibers and e resin. These additional treatments involve a substantial investment in equipment and additional expense in maintenance and operation of such equipment. One substantial benefit obtained through the use of the size formulations disclosed in Example I is that one need not subject fiber glass cloth woven from yarn treated withthis size to the costly heat cleaning and coupling agent treatments. One need only take the cloth woven from fiber glass yarns treated with this size, saturate it with the desired resin and shape or form said saturated cloth to whatever configuration is desired by conventional molding or laminating techniques. Thus, fabricators manufacturing resinous articles reinforced with fiberglass "cloth can, through'the use of cloth woven from fiber glass yarn treated with the subject sizes, produce such reinforced articles with either polyester or epoxy resins without suffering the expense of heat cleaning or couplingagent treatments.

' The sized strands herein exemplified by Example'II are particularly useful as a reinforcement for elastomers. In such use, a plurality of ends of strand or yarn are combined and coated with a rubber adhesive. The coated ends are twisted and then plied with other coated ends to form a coated cord. For example, five or seven ends of ECG-75S with a one-half turn twist may be combined and coated and impregnated with a rubber latex adhesive. The coated ends are heated to dry the adhesive and fix it on the combined ends of yarn. The coated ends are then twisted to impart a 2.5Z twist. The twisted ends are then plied with other twisted ends to give a balanced 2.5S plied cord. Typical cords are /4 for belt reinforcement and 5 3 for tire reinforcement. The cords are used as such or in a loosely woven fabric form. The fabric is used in the belt portion of bias-belt and radial ply tires.

It has been found that different adhesives must be used with different synthetic fibers to get maximum properties in different rubber stocks. A satisfactory adhesive for glass fibers and rubber is a mixture of resorcinol, formaldehyde and a terpolymer of butadiene, styrene and vinyl pyridine such as shown in U.S. Pat. No. 2,817,616. Other suitable formulations are described in US. Pats. Nos. 2,691,614 and 2,822,311. The formulation of a suitable rubber adhesive and the coating of glass fiber strand and yarn therewith are described in the following example.

Example V A rubber adhesive is prepared from the following ingredients.

These ingredients are mixed in the following manner. The Gen-Tac terpolymer latex is mixed with 1,940 parts by weight of water. Water (7,632 parts by weight) is added to a separate container. NaOH is then added and dissolved in the water in the separate container. Resorcinol is next added to the aqueous solution of NaOH and dissolved therein. Formaldehyde is added after the resorcinol and the mixture is stirred for 5 minutes and allowed to age at room temperature for two to six hours. The aging permits a small amount of condensation of resorcinol and formaldehyde and provides superior adhesion of the subsequently coated yarn to the rubber stock. After aging, this mixture is added to the Gen-Tac latex and the resultant mixture is stirred slowly for 15 minutes. Ammonium hydroxide is then added and the mixture is stirred slowly for minutes. The ammonium hydroxide inhibits further condensation of the resorcinol formaldehyde. I v 7 Glass fiber strands sized as described in EXainpleII are coated and impregnated with the adhesive pr'pduced' as above described. Seven strands (ECG-75S) with one-half turn per inch of twist are combined in parallel relation and passed under slight tension through groovesin rotating rollers which are partially suspended in the adhesive.

The pickup of adhesive is sufficient to provide a coating 7 on the-strands ofabout 17 to 19 percent by weight of adhesive based upon the weight of strands. Eighteen percent (18%) by-weight of"adhesive-has been found tobe suitable for most purposes.--' a ir-r Thereafter, the coated strands are passed vertically through a dielectric or microwave drying oven to remove the water and NH from theadhesive. During this removal the strands appear to vibrate vigorously and further impregnation of the adhesive into' the strands and onto and around the individual fibers is achieved. The coated strands next pass upwardly through a gas oven maintained at a temperatu're of about 350' to. 500v F; to effect curing of the resorcinol formaldehydeg Further flowing and impregnating'of the adhesive is; accomplished during this second heating step-The curing or condensing of the resorcinol formaldehyde vis free to' proceed with the removal of the NH The condensation is time-ternperature dependent. For example, heating the coated strands for 30 secondsat 370 F. or 20 seconds at 420 F. is satisfactory. Apparatus suitable for performing the two-step heat treatment is shown in US. Pat. No. 2,865,- 790' The two-step drying and curing process provides improved uniformity and impregnation of the coating on the strands. This is'evidenced by a uniformity of amount and coloring of the coating on'the'strands and the absence of flags or lumps of "adhesive along thelength of the coated strand as is the case with conventional coating techniques. This, in turn, provides markedly improved flex life of the rubber product which is reinforced with the coated strands. The two-step coating process also permits coating of the adhesive at a much faster rate than conventional coating processes whichdo'notutiliZe the dielectric or microwave drying step.

Experimentation is usually necessary to determine the optimum cord construction and adhesive for thefpar'ticular rubber product. In this experimentation, VariOusscreening tests are utilized to determine the properties-of the reinforced rubber. The H-Adhesioit-test' is'one bf the standard rubber industry tests m The following rubber compounds were reinforced with glass fiber cord of ECG- 7/0 2.58 construction and tested. The individual fibers were formed and sized as described in Example II and the strands were coated as described in Example V. The chemical identification of the ingredients in the rubber compoundcan be found in Materials and Compounding lngredients for Rubber and Plastics published by RubbenWorld...

nxamme' v "SBRFNatural Ingredients: "-Rubber blend SBR 1500 '.."v 75 No. 1 RSS (rubber smoked sheet)" 25 HAF Black L 50 ZnO v 5 Stearic acid r l Age-Rite Resin (antioxidant) 1 Sundex 790 (plasticizer,inanufactured by Spn Oil Company) ;L ;ZQ 10 Santocure manufactured by Monsanto (accelerative) 'L"; 'L i 1 DOTG 0.2

Sulfur .1---

H-Pull adhesion 15.5-16.5 pounds.

Strip adhesion;

7 At room temperature- 98,104-. pounds. At 230 F. for 30 minutes 45.50 pounds. Retention (percent). 43.47%.- a Flex fatigue About 610,000

cycles. Breaking strength -85 pounds 9 Example VII An adhesive dip composition especially useful for cords which are to reinforce natural rubber and SBR stocks is as follows.

Ingredients: Parts by weight Butadiene-styrene latex (70% butadiene, 30%

styrene by weight 7,800 Rescorcinol 350 Formaldehyde l 8 NaOH 9.6 Water 9,572

This adhesive dip is prepared in the same manner as the adhesive in Example V with the exception that NH OH is omitted. The latex appears to act as a sufficient inhibitor to condensation of the resorcinol and formaldehyde to permit absence of NH OH.

Example VIII An adhesive dip composition especially useful for cords which are to reinforce neoprene rubber stock is as follows.

Percent Parts by Antioxldant which prevents breakdown oi Neoprene at high temperature-B-phenylnaphthyl (amine).

This adhesive is prepared in the same manner as in Example V and is aged for 24 hours at room temperature before use.

Example IX An adhesive dip composition especially useful for neoprene rubber stock is as follows.

Percent Parts by Ingredient solids weight Neoprene latex (DuPont latex 460) 46 4, 176 Butadiene-stryene-vinyl pyridine latex 41 1, 171 MgO 33 315 NHrOH 28 271 Resorcinol 100 264 37 389 The adhesive dip composition is prepared in the same manner as described in Example V.

The term elastomer as used herein and in the claims is intended to include elastic substances such as natural latex from the Hevea tree and synthetic rubber and rubber-like' materials. It also includes natural and synthetic rubber and rubber-like materials which have been chemically modified such as by chlorination to improve their physical properties. Synthetic rubber includes rubber-like materials such as chloroprene, butadiene, isoprene and copolymers thereof with acrylonitrile, styrene and isobutylene. The term elastomer includes natural and synthetic rubber in the uncured or unvulcanized state as well as in the cured or vulcanized state.

Although the present invention has been described with respect to specific details of certain embodiments thereof, it is not intended that such details act as limitations upon the scope of the invention except insofar as set forth in the accompanying claim.

What is claimed is:

1. An aqueous glass fiber strand forming size consisting essentially of 2 to 15 percent by weight of a polyolefin emulsion selected from the group consisting essentially of polypropylene or polypropylene-polyethylene mixtures, wherein the polypropylene has an average molecular weight in the range of about 5,300 to about 7,300 and is present in amounts from about 25 to 100 percent by weight of the polyolefins present and the polyethylene present has an average molecular weight of about 2,000 to about 10,000 and is present in amounts from about 0 to percent by weight of the polyolefins, a glass fiber coupling agent in an amount of 0.1 to 2 percent by weight and a' glass fiber textile lubricant in an amount ranging between 0.2 and 4 percent by weight, the viscosity of the aqueous size being less than centipoises at 20 C.

References Cited UNITED STATES PATENTS 2,965,596 12/ 1960 Sharf 2-6029.6 XA 3,296,174 1/1967 Pickard 260-29.6 XA 3,357,853 12/1967 Pickard 26029.6 XA 3,350,337 10/1967 Campbell 26029.6 XA 3,644,141 2/1972 Preston 260-29'.6 XA

HAROLD D. ANDERSON, Primary Examiner US. Cl. X.R.

\ UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,814,715 Dated June 4, 1974 lnventofls) Charles E. Nalley and Joe B. Lovelace It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 2, line l7, "products" should read -product-. Column 4,

lines 48 and 49, "acetoxy benzoxy acetonyl acetamide etc." should read acetoxy benzoxy, acetonyl, acetamide, etc.-. Column 5, line 63, "Versmid should read -Versamid Column 5, line 69, after "Percent", insert -solids. Column 6, line 54, "tensine" should read -tensile--; Column 7, line 49, "(28%, NH in 1-1 0)" should read --(28% NH in H 0)--. Column 8, line 68, "25.50 pounds" should read -45-50 pounds--; Column 8, line 69, "43.47%" should read -43-47%--. Column 10, line 24, "or" should read and--; Column 10, line 34,

"and" should read -to-.

Signed and sealed this 8th day of October 1974.

' (SEAL) Attest:

MCCOY M. GIBSON JR. C. MARSHALL DANN Attesting Officer Commissioner of Patents USCOMM-DC 60376-P69 9 us, GOVERNMENT PRINTING OFFICE: I9! 0-."6-384,

YORM PO-1050 (10-69)