GB2030611A

GB2030611A - Storage Stable Polyolefin Compatible Size for Fibre Glass Strands

Info

Publication number: GB2030611A
Application number: GB7843705A
Authority: GB
Original assignee: PPG Industries Inc
Current assignee: PPG Industries Inc
Priority date: 1978-08-14
Filing date: 1978-11-08
Publication date: 1980-04-10
Also published as: NL178411B; DE2853755A1; IT1192742B; IT7923770A0; FR2433604A1; BE872343A; DE2853755C2; JPS5527889A; CA1115876A; NL178411C; JPS5738538B2; NL7810824A; GB2030611B; CH642034A5

Abstract

A strand of glass fibres is impregnated with a sizing comprising (1) a coupling agent, (2) a stabilizer, (3) a lubricant, (4) a non-crosslinkable film-forming polymer and (5) a cross- linkable film-forming polymer. The resulting sized glass fibre strands have been found, to be storage stable; to form a package of sized glass fibre which is readily available for subsequent use; and to show improved adhesion when used as filler for polymeric material. Many materials are listed but in the preferred embodiment (1) is gamma- amino propyl triethoxy silane, (2) is cis-butene-dioic acid, (3) is a maleonated amorphous polypropylene (4) is a vinylacetate homopolymer, and (5) is a vinylacetate- methylolacrylamide.

Description

SPECIFICATION Storage Stable Polyolefin Compatible Size For Fibre Glass Strands The present invention relates to glass fibre strand treatment and particularly relates to treating glass fibres during or after forming with an aqueous sizing which prepares the glass fibres for bonding to polymeric materials, for example polyolefins in the reinforcement of polyolefin materials, and further has long shelf life and can be used from forming packages.

It is known that glass fibres in the form of continuous strands, chopped strands or mats can be used successfully to reinforce polyolefins. And it is known that without effective coupling between the glass and the polyolefin, the adhesion between the two will be weak and separation will occur under shear or tensile stresses. It is further known that the affinity of glass for water aggravates bond weakness when glass is inadequately bonded to polyolefins.

A workable method has been disclosed which permits bonding glass to "lower" polyolefins which are essentially crystalline plastics formed from monomers having three or more carbon atoms. As disclosed in U.S. Patent No. 3,013,915 at column 2, lines 38-46, glass bonding to polyolefins may be improved by "cleaning the glass surface, applying a coupling agent to it, treating with a chemical agent which is a source of dehydrogenating or oxidizing radicals, contacting the polyolefin with the glass, and fusing it by heating the polyolefin above its melting point to complete the interbonding".At column 4, lines 1 6-1 9, the disclosure reveals a preference for radical sources having low decompositicn points below 1 800F and at column 4, lines 69-71, indicates that exposure to heat must be avoided.

U.S. Patent No. 3,849,148 proposes the method of sizing fibre glass strands with an aqueous sizing containing a coupling agent, a heat stable organic peroxide, a non-ionic surfactant and a lubricant. This process was successful in giving some storage capability to the sized strands but did not result in long storage life and further remains susceptible to degradation by high storage temperatures.

U.S. Patent No. 3,882,068 discloses the sizing compositions for glass fibres in several plastic resin systems wherein the size comprises a coupling agent and a polyolefin emulsion.

U.S. Patent No. 3,437,550 discloses a method of increasing the bonding of glass fibres to polyolefins by treating the fibre with a crystalline polypropylene matrix polymer. The preferred modifiers disclosed are maleic anhydride and acrylic acid.

U.S. Patent No. 3,883,333 discloses a method and apparatus for forming a continuous glass fibre mat of sized fibres that are suitable for bonding with polyolefins. The process and apparatus, although continuous, discloses lay down of the fibres immediately after formation of strands.

While the above processes and compositions were useful, there remains a need in the art for a sizing to promote the binding of polyolefins to continuous glass fibre strands with increased adhesion.

Further, there remains a need for a sizing for glass fibre strands which will allow the formation of the sized fibre into forming packages that may be stored indefinitely prior to use. Effective sizings containing peroxides have limited shelf-life since they are very sensitive to elevated temperature variations during drying of the fibres and high temperatures during storage which can cause premature degradation of the peroxides thus reducing the effectiveness of the sizing in binding the glass fibre strands to the polypropylene matrix.

According to the present invention a sizing comprising a coupling agent, a stabilizer, a lubricant, a non-crosslinking film-former, a self-reactive cross-linking film former, and an aqueous carrier is applied to a glass fibre strand. The sized strand is then wound into a forming package and dried for later use as a reinforcement for polymeric material, for example polypropylene material.

In a preferred embodiment of the present invention, an aqueous sizing comprising a coupling agent of gamma-amino-propyltriethoxysilane, a stabilizer comprising cis-butenedioic acid, a lubricant of an emulsion of maleonated amorphous polypropylene, a non-crosslinking film former of vinyl acetate homopolymer, and a self-reactive copolymer of vinyl acetate and n-methylol-acrylamide are applied in an aqueous sizing to a glass fibre so as to impregnate the strand and improve its ability to reinforce polypropylene articles. The strand after being wound as a forming package and drying to remove the aqueous carrier may be withdrawn from the forming package and laid down on a mat which is contacted with polypropylene sheet and under heat and pressure formed into a fibre reinforced article.

The utilisation of the sizing system of the present invention results in numerous advantages over the prior processes. The utilization of a storage stable sizing with no shelf-life limitation improves production capability because it allows the storing and distribution of forming packages of sized glass fibre strand. Prior to the present invention, it was necessary that the sized fibre be used shortly after forming or be immediately formed into a mat for forming composite articles. Further, the drying of the sized fibre was difficult as the drying temperature conditions were limited by a necessity to not decompose the peroxide, an important ingredient of the sizing. With utilization of the present system, it is possible to form forming packages of sized glass fibre strands at a central location.These may be then shipped without limitations as to temperature or atmosphere during shipping to distant points for fabrication into composite polyolefin glass-fibre-reinforced articles. This offers considerable improvement since the forming of glass strands no longer must be carried out at the same location that the polyolefin glass fibre reinforced article is formed. Thus as can be seen that although the individual ingredients had been used in other sizings, the present combination of ingredients allows the achievement of numerous advantages not present in prior systems.

Any glass suitable for reinforcing and for drawing in fibre form may suitably be treated in accordance with the present invention. Soda-lime glasses and borosilicates ("E") glasses are particularly suited for this practice.

The glass fibre strands to be treated according to this invention may be typically produced according to the teachings of U.S. Patent No. 2,133,238. The glass fibre strands are composed of a multitude of fine glass filaments which are formed by being drawn at a high rate of speed from molten cones of glass located at the tips of small orifices in a bushing. During formation, the filaments are coated with the aqueous sizing prepared according to the description below. Coating of the filaments takes place while they are moving at a speed of the order of 1 ,000 to 20,000 feet per minute. The coating is accomplished in the immediate vicinity of the hot bushings and the glass furnace in which the glass is melted, and after coating, the glass fibre strands move a short distance onto collecting means.After the strands have been sized, they may be dried to drive off residual moisture from the sized glass.

The aqueous sizing to contact, impregnate and coat the glass fibre strand is composed of a coupling agent, a stabilizer, a lubricant, a non-crosslinking film former and a self-reactive crosslinking film former, The coupling agent may be any interfacial boundary area adhesive compound which acts to unite the surface of the glass fibre strand with the polyolefin polymer.Among typical coupling agents for uniting glass fibre strand and polymers are metal salts of the strong metal acids such as basic chromium chloride, basic chromium sulfide, having a trivalent metal ion selected from the group consisting of chromium, cobalt, nickel, copper, and lead having at least one hydroxyl group attached to the metal and at least one anion of a strong mineral acid attached to the metal; Werner type complexes in which a trivalent nuclear atom such as chromium is co-ordinated with an organic acid such as methacrylic acid, for instance, methacrylic acid complex of chromic chloride, and other Werner type coupling agents, having vinyl, alkyl, amino, epoxy, mercapto, thioalkyl, thioalkanyl and phenol groups.

Suitable for the utilization in the present invention are coupling agents from the silane and siloxane groups. Typical of such coupling agents are hydrolyzable, vinyl, allyl, beta-chioropropyl, phenyl, thioalkyl, thio-alkaryl, amino-alkyl, methacrylate, epoxy, and mercapto silanes their hydrolysis products and polymers of hydrolysis products and mixtures of any of these. A preferred coupling agent is gammaaminopropyltriethoxysilane as this material has been found to provide very good coupling between the glass fibre strand and polyolefin polymers at low concentrations and with good stability.

Any stabilizer may be selected which acts as a secondary coupler to improve the stability of the sizing system, assists in crosslinking, improves the coupling agent fibre innerface and assists the action of the silane in coupling. Typical of stabilizers for sizes suitable for the invention are ethylenically unsaturated mono or di-carboxylic acids or an hydrides. Examples of such acids and anhydrides include maleic acid, fumaric acid, itaconic acid, citraconic acid, acrylic acid, methacrylic acid, crotonic acid, isocrotonic acid, mesaconic acid, himic anhydride, maleic anhydride, itaconic anhydride and citraconic an hydride, and mixtures thereof. A preferred stabilizer is maleic acid (cis-butenedioic acid) that gives a stable system and improves the coupling action of the silane coupling agent.

Any material that acts as a lubricant to aid film forming and assist the coupling may be used as the lubricant of the present invention. Suitable lubricants are chemically modified propylenes.

Maleonated or acrylic modified polypropylenes are preferred as they result in a sized fibre with good storage properties and ability to feed from the forming package.

The polymer which forms the non-crosslinked film former material of the sizing of the system of the present invention may be any material that provides strand integrity to aid in the processability of the glass fibre strand allowing strand removal from a forming package. The non-crosslinked polymer provides the desired level of plasticity to the size such that the sized fibre of the present system has an extended shelf-life and also the processability to allow successful needling of a mat formed of the sized fibres of the present invention. The non-crosslinking polymer generally is a homopolymer or mixtures of homopolymers that will not crosslink in the conditions of the sizing and molding operations to which the sized fibre is subjected in the drying of the aqueous sizing from the fibre and molding with an olefin homopolymer such as polypropylene.Typical of non-crosslinked film-forming polymers suitable for the present invention are epoxies, polyesters, polyurethanes and acrylics. A preferred non-crosslinked filmforming material is vinyl acetate homopolymer as vinyl acetate homopolymer is low in cost, does not degrade at the present forming temperatures and provide good strand integrity when used on a glass fibre strand.

The self-reactive crosslinked polymer of the present system may be any polymer or copolymer that contributes to the formability, strand integrity (hardness), strand lay, non-scroopy finish, and needleability and is capable of auto-co-reaction and cross-linking. These self-reactable crosslinking polymers may be defined as a polymer or copolymer capable of becoming crosslinked without addition of further materials in the conditions encountered during the drying of the sized strand forming package. Typical of seif-reactive crosslinking polymers are vinylacetates, epoxies, polyesters, polyurethanes and acrylic polymers. A preferred polymer is a self-reactive vinyl acetate-N methylolacryl-amide copolymer that has the advantages of compatability with the polyolefin polymers particularly polypropylene, low cost, and stability at the forming temperatures of polyolefins.

The sized glass fibres may be formed and the size applied by the known methods of fibre formation and sizing application. Representative of a method of fibre formation and sizing application is the process illustrated in Fig. 2 of U.S. Patent No. 3,849,148 which is hereby incorporated by reference. Glass fibre filaments emerge from orifices of an electrically heated bushing. These fibres are attenuated and by means of a strand pulling device these filaments are gathered to form a strand of glass fibre which may comprise numerous individual fibres. The sizing is applied to the fibres by a conventional size applicator such as a kiss applicator or a belt applicator device. Detail of a sizing applicator is shown in U.S. Patent No. 2,728,972. The filaments after exiting the bushing are cooled by air or preferably water.The filaments are gathered into bundles by a gathering shoe and are then led to a strand pulling device such as illustrated in U.S. Patent No. 3,292,013 as well as in the above referenced, U.S. Patent No. 3,849,148. The glass fibre strand or strands, if the filaments exiting from the bushing have been separated into several strands, are then wound onto a forming tube on a collet rotating at approximately 7,500 rpm to produce a strand travel of approximately 12,000 to 15,000 feet per minute. The glass fibre strand forming packages are then dried. This generally is accomplished by baking the packages of fibre at a temperature and for a length of time sufficient to remove substantially all of the water. Generally a curing time for the present size is about 11 hours at 2700F.

After drying the forming tube may be removed resulting in a forming package of sized glass fibre. These forming packages may be stored virtually indefinitely when sized with the present sizing. When the forming package is desired for use in forming a polyolefin composite article, a group of the forming packages are arranged so that the strands may be drawn from the packages and laid down to form a mat of fibres such as disclosed in U.S. Patent No. 3,883,333 or U.S. Patent No. 3,664,909. The mat is then needled and combined or impregnated with polyolefin resin or laminated with polyolefin sheets to form reinforced polyolefin articles which are heated at a temperature in the range of 4000F to about 4300F at a pressure of about 9250 pounds per square inch for about 5 to about 20 minutes to bind the sized glass fibres of the invention to the polyolefin.The laminated polyolefin glass fibre mat articles may then be stamped or moulded by a variety of means, including that of U.S. Patent No. 3,664,909 hereby incorporated by reference, to produce reinforced polyolefin laminates suitable for use as containers or for other low-cost, high strength and low temperature uses.

The coupling agent may be utilized in amounts which results in good interfacial boundary area adhesion between the glass fibre strand and the polyolefin. A silane coupling agent concentration of about .2 to about 1 8 percent by weight of the solids of the sizing concentration has been found to be suitable. A preferred percent of silane has been found to be about 6 percent by weight of the solids in the sizing of the silane to give maximum adhesion with minimum cost.

The lubricant may be utilized in any amount which results in good stability of the sizing system. A suitable amount has been found to be about 30 to about 80 percent by weight of solids in the sizing solution. A preferred amount of the maleonated amorphous polypropylene for good forming and fabrication processability has been found to be about 60 percent by weight of the solids in the sizing emulsion.

The stabilizer may be used in any amount which results in good interface bonding of the filmforming materials to the glass fibre strand. A suitable amount has been found to be about 1 to about 9 percent stabilizer to the solids of the sizing emulsion. A preferred amount of stabilizer has been found to be about one-half the amount of the silane coupling agent to give good adhesion of the film formers to the coupling agent.

The non-crosslinking-film forming material and the self-reactive crosslinking material are blended to give the desired handling properties to the sized strand. The non-crosslinkable polymer, preferably vinyl acetate homopolymer imparts plasticity to the fibre and its use is dependent on the hardness or brittleness of the self-reactive cross-linking film former. The self-reactive crosslinking film former acts to provide integrity to the glass fibre strand so that it does not come apart into filaments during processing or cutting operations. A normal range of the non-crosslinkable polymer would be between about 5 and 40 percent by weight of the solids in the sizing emulsion. A suitable amount of selfreactive crosslinking material would be between about 1 0 and about 50 percent by weight of the solids in the sizing emulsion.A preferred amount of the self-reactive crosslinking material would be about 22 percent of the solids in the sizing emulsion such that the fibre has good integrity. A preferred amount of the non-crosslinking vinyl acetate homopolymer is about 9 percent by weight of the solids in the sizing emulsion to give optimum handability.

The sizing emulsion generally contains between about 95 percent and about 80 percent water. It is preferred in the use of a kiss roll applicator to have between 83 and 93 parts by weight water in the sizing solution. Thus, solids amount is greatly dependent on the applicator that is used to size the fibre strand.

The sized fibre forming packages of the present system may be utilized to reinforce any polymeric resin article. However, the present fibres find greater functionality in the reinforcement of polyolefinic resin polymers including polyethylene and 5-methyl pentene polymers. A preferred polyolefinic polymer for utilization with the present sized glass fibre strand is polypropylene since this polymer binds very well with the present sizing, is relatively low cost and gives good strength properties when glass reinforced. The ratio of polyolefinic polymer to glass may be selected in any ratio that gives the desired properties to the finished article. Generally a ratio of about 10 to about 60 percent glass by weight is suitable.A preferred amount is about 35 to about 45 percent by weight glass in a polypropylene moulded article to give a good balance of cost, properties and structural strength.

The amount of the sizings used on the glass may be any amount which results in good structural strength of the finished polyolefin fibre composite, good fibre integrity and handleability. A suitable amount of sizing is about .02 to about 1 percent by weight sizing solids to total weight of the sized strand of glass. A preferred range is about .6 percent to give good fibre integrity and handleability.

The present invention will now be further illustrated by way of the following Example. The parts and percentages are by weight unless otherwise indicated.

Example I Ingredient Functional Parts by Weight Percent of Identification Chemical Identification of Sizing Size Solids Coupling agent gamma-aminopropyltriethoxysilane .7 6 (Union Carbide A-l 100) Stabilizer cis-butenedioic acid .35 3 Lubricant emulsion of maleonated amorphous polypropylene 7.3 60 22% active 10% surfactant and KOH 68% water surfactant=alkoxylated phenol Non-crosslinking vinylacetate homopolymer emulsion 54% solids 1.1 9 film former (National Starch Resyn 25-1031) Self-reactive film emulsion of vinyl acetate-n-methylolacrylamide 2.6 22 52% solids (National Starch Resyn 25-2828) Water 87.95 The glass fibre strand sizing is prepared by adding most of the necessary deionized water to the mix tank and then slowly adding the lubricant to the mix tank as it is agitated.The coupling agent is then added to the mix tank followed by adding the maleic acid with continued agitation. After the addition of the maleic acid, stirring is carried out for about 20 minutes to dissolve the acid. Then the non-crosslinking film-forming material is added to the tank followed by the addition of the crosslinkable polymeric emulsion which is diluted with an equal quantity of cold deionized water prior to addition. Additional make-up water necessary is added and the batch is checked to determine that the specifications are within the range of about a pH of about 6 and a solids of about 5 percent solids.

In a preferred embodiment, the aqueous sizing mixture is applied to fibre filaments that are formed from a 400-hole bushing. The filaments are treated by a kiss -roll applicator to coat about .6 percent solids by weight of the glass onto the filaments. The filaments are gathered into four strands or more then wound onto the collets to form packages of about 20 pounds or more each. The formed packages are cured for about 11 hours at 2700 F. Following the curing the forming package can be stored indefinitely at ambient conditions. The forming packages are then utilized to form a mat of continuous fibres which is then needled and laminated with polypropylene polymer in the weight of about 60 parts by weight of polypropylene polymer to 40 parts by weight of the needled mat.The polyolefin resin and mat are combined via a temperature range of about 4000F at a pressure of about 90 pounds per square inch for about 5 minutes to bond the reinforcing glass fibres to the polyolefin.

The heating is carried out between stainless steel belts. The laminate of sized fibre matting and polypropylene is then stamped into test tubs such as described at column 6 through column 7 of U.S.

Patent No. 3,849,148 and tested for structural strength and structural modulus. The flexural strength averages at least about 23,000 pounds per square inch and flexural modulus about 1 x 1 o6 pounds per square inch. This example shows that the polypropylene reinforcing sized glass fibre strands of the present invention provide satisfactory strong reinforced articles even after extended storage period of the forming packages.

By practice of the present invention there may be provided one or more of the following:- (i) a storage stable polyolefin bonding sizing for continuous glass fibres, (ii) polyolefin glass fibre composites using glass fibres from forming packages, (iii) storage stable forming packages of polyolefin compatible glass fibre strands, (iv) a polyolefin bonding sizing not susceptible to thermal degradation during the drying operation.

While the present invention has been described with reference to several embodiments, those skilled in the art will recognize that variations may be made to the described methods and devices without departing from the substance of this invention. For instance, a pigment or dye could be added to the sizing solution without interference with its effect.

As will be apparent to those skilled in the art, the present system may be modified and equivalent elements or processes may be employed in combination therewith without departing from the spirit of the invention. For instance, an application device for the sizing could be utilized which would not require as large an amount of water in the sizing emulsion. Further, the fibre forming packages of the present invention could be utilized in the reinforcing of polymeric materials other than polyolefins. Also, a combination of the sized fibre forming packages of this invention could be utilized with fibres sized with a different material, with unsized fibres or with chopped strand sized with the sizing of this invention.

Thus, the present disclosure of preferred embodiments is not intended to limit the scope of the present invention.

Claims

1. A glass fibre strand comprising a strand of glass impregnated with a sizing comprising a coupling agent, a stabilizer, a lubricant, a non-crosslinked film forming polymer and a crosslinked film forming polymer.

2. A glass fibre strand as claimed in claim 1 wherein said coupling agent is selected from silanes and siloxanes.

3. A glass fibre strand as claimed in claim 2 wherein said coupling agent is an aminosilane.

4. A glass fibre strand as claimed in any one of claims 1 to 3, wherein said stabilizer comprises a mono or difunctional acid selected from ethylenically unsaturated carboxylic acid and anhydrides.

5. An article as claimed in claim 4 wherein said stabilizer comprises a difunctional acid selected from ethylenically unsaturated carboxylic acids and anhydrides.

6. A glass fibre strand as claimed in claim 5 wherein said stabilizer comprises cis-butenedioic acid.

7. A glass fibre strand as claimed in claim 4 wherein said stabilizer comprises himic anhydride.

8. A glass fibre strand as claimed in any one of claims 1 to 7, wherein said lubricant comprises an emulsion cf chemically modified polypropylene.

9. A glass fibre strand as claimed in any one of claims 1 to 7, wherein said lubricant comprises maleonated amorphous polypropylene.

10. A glass fibre strand as claimed in any one of claims 1 to 9 wherein said coupling agent comprises from 2 to 1 8 weight percent of said sizing.

1 A glass fibre strand as claimed in any one of claims 1 to 10, wherein said stabilizer comprises -from 1 to 9 weight percent of said sizing.

12. A glass fibre strand as claimed in any one of claims 1 to 11 wherein said lubricant comprises from 30 to 80 weight percent of said sizing.

13. A glass fibre strand as claimed in any one of claims 1 to 1 2, wherein said non-crosslinkable film former comprises from 5 to 40 parts by weight of said sizing.

14. A glass fibre strand as claimed in any one of claims 1 to 1 3 wherein said self-reactive film former comprises from 1 0 to 50 parts by weight of said sizing.

1 5. A glass fibre strand as claimed in any one of claims 1 to 14, wherein said non-crosslinked filmforming polymer comprises a member selected from epoxy polymers, polyester polymers, polyurethanes, acrylic polymers and mixtures thereof.

1 6. A glass fibre strand as claimed in claim 1 5 wherein said non-crosslinking polymer is a vinyl acetate homopolymer.

17. A glass fibre strand as claimed in any one of claims 1 to 1 6, wherein said crosslinked filmforming polymer is selected from epoxy polymers, polyester polymers, polyurethanes, acrylic polymers, and copolymers and mixtures thereof.

1 8. A glass fibre strand as claimed in claim 1 7 wherein said crosslinked polymer is a vinyl acetate copolymer.

1 9. A forming package of glass fibre strand, said glass fibre strand being as claimed in any one of claims 1 to 18.

20. An article comprising a polymeric material reinforced with glass strands wherein said glass strands are as claimed in any one of claims 1 to 1 8.

21. An article as claimed in claim 20, wherein said polymeric material is a polyolefin polymer.

22. An article as claimed in claim 21, wherein said polyolefin is selected from polypropylene, polyethylene, 5-methyl pentene and mixtures thereof.

23. A method of forming a composite article comprising bringing together polymeric material and sized glass strands and applying pressure wherein said sized glass strands are impregnated with a sizing comprising coupling agent, stabilizer, lubricant, non-crosslinked polymer and crosslinked polymers

24. A method as claimed in claim 23, wherein said glass strands are in the form of a mat.

25. A method as claimed in claim 23 or claim 24, wherein said glass strands comprise about 10 to about 60 percent by weight of said article.

26. A method as claimed in any one of claims 23 to 25 wherein said coupling agent is selected from silanes and siloxanes.

27. A method as claimed in claim 26 wherein said coupling agent is an aminosilane.

28. A method as claimed in any one of claims 23 to 27, wherein said stabilizer comprises a mono or difunctional acid selected from ethylenically unsaturated carboxylic acid and anhydrides.

29. A method as claimed in claim 28 wherein said stabilizer comprises cis-butenedioic acid.

30. A method as claimed in any one of claims 23 to 29, wherein said lubricant comprises an emulsion of chemically modified polypropylene.

31. A method as claimed in any one of claims 23 to 29, wherein said lubricant comprises amorphous polypropylene.

32. A method as claimed in any one of claims 23 to 31, wherein said coupling agent comprises from 2 to 1 8 weight percent of said sizing.

33. A method as claimed in any one of claims 23 to 32 wherein said stabilizer comprises from 1 to 9 weight percent of said sizing.

34. A method as claimed in any one of claims 23 to 33 wherein said lubricant comprises from 30 to 80 weight percent of said sizing.

35. A method as claimed in any one of claims 23 to 34 wherein said non-crosslinkable film former comprises from 5 to 40 parts by weight of said sizing.

36. A method as claimed in any one of claims 23 to 35 wherein said self-reactive film former comprises from 10 to 50 parts by weight of said sizing.

37. A method as claimed in any one of claims 23 to 36, wherein said non-crosslinked film forming polymer comprises a member selected from epoxy polymers, polyester polymers, acrylic polymers and mixtures thereof.

38. A method as claimed in claim 37 wherein said non-crosslinking polymer is a vinyl acetate homopolymer.

39. A method as claimed in any one of claims 23 to 38, wherein said crosslinked film-forming polymer is selected from epoxy polymers, polyester polymers, acrylic polymers, and copolymers and mixtures thereof.

40. A method as claimed in claim 39, wherein said crosslinked polymer is a vinyl acetate copolymer.

41. A method as claimed in any one of claims 23 to 40 wherein said polymeric material is a polyolefin polymer.

42. A method as claimed in claim 41 wherein said polyolefin polymer is selected from polyethylene, polypropylene 5-methyl pentene and mixtures thereof.

43. A forming package of glass fibre strand comprising a strand of glass impregnated with a sizing comprising gamma-aminopropyl-triethyoxysilane, cis-butenedioic acid, maleonated amorphous polypropylene, vinylacetate homopolymer and vinyl acetate-metholacrylamide copolymer.

44. A forming package as claimed in claim 43, wherein said sizing comprises about .6 percent by weight of said sized fibre.

45. A forming package as claimed in claim 44, wherein said sizing comprises about 6 percent by weight of said silane, about 3 percent by weight of said cis-butenedioic acid, about 60 percent by weight of said maleonated amorphous polypropylene, about 9 percent by weight of said vinylacetate homopolymer and about 22 percent by weight of said vinylacetate-n-methyolacrylamide copolymer.

45. A forming package as claimed in claim 44, wherein said sizing comprises about 6 percent by weight of said silane, about 3 percent by weight of said cis-butenedioic acid, about 60 percent by weight of said maleonated amorphous polypropylene, about 9 percent by weight of said vinylacetate homopolymer and about 22 parts by weight of said vinylacetate-n-methyolacrylamide copolymer.

46. A glass fibre strand as claimed in claim 1 and substantially as hereinbefore described with reference to the Example.

47. A forming package as claimed in claim 1 9 and substantially as hereinbefore described with reference to the Example.

48. An article as claimed in claim 20 and substantially as hereinbefore described with reference to the Example.

49. A method as claimed in claim 23 and substantially as hereinbefore described with reference to the Example.

New claims or amendments to claims filed on 14th September 1979.

Superseded claims 1, 13-18, 22, 23, 35-40, 45.

New or amended claims

1. A glass fibre strand comprising a strand of glass impregnated with a sizing comprising a coupling agent, a stabilizer, a lubricant, a non-crosslinkable film forming polymer and a self-reactive crosslinking film forming polymer.

13. A glass fibre strand as claimed in any one of claims 1 to 12, wherein said non-crosslinkable film former comprises from 5 to 40 weight percent of said sizing.

1 4. A glass fibre strand as claimed in any one of claims 1 to 13 wherein said self-reactive film former comprises from 10 to 50 weight percent of said sizing.

1 5. A glass fibre strand as claimed in any one of claims 1 to 14, wherein said non-crosslinkable film-forming polymer comprises a member selected from epoxy polymers, polyester polymers, polyurethanes, acrylic polymers and mixtures thereof.

1 6. A glass fibre strand as claimed in claim 1 5 wherein said non-crosslinkable polymer is a vinyl acetate homopolymer.

17. A glass fibre strand as claimed in any one of claims 1 to 16, wherein said self-reactive crosslinking film-forming polymer is selected from epoxy polymers, polyester polymers, polyurethanes, acrylic polymers, and copolymers and mixtures thereof.

18. A glass fibre strand as claimed in claim 17 wherein said self-reactive crosslinking polymer is a vinyl acetate copolymer.

22. An article as claimed in claim 21, wherein said polyolefin is selected from polypropylene.

polyethylene, 5-methyl pentene polymer and mixtures thereof.

23. A method of forming a composite article comprising bringing together polymeric material and sized glass strands and applying pressure wherein said sized glass strands are impregnated with a sizing comprising coupling agent, stabilizer, lubricant, non-crosslinkable polymer and self-reactive crosslinking polymer.

35. A method as claimed in any one of claims 23 to 34 wherein said non-crosslinkable film former comprises from 5 to 40 weight percent of said sizing.

36. A method as claimed in any one of claims 23 to 35 wherein said self-reative film former comprises from 10 to 50 weight percent of said sizing.

37. A method as claimed in any one of claims 23 to 36, wherein said non-crosslinkable filmforming polymer comprises a member selected from epoxy polymers, polyester polymers, acrylic polymers and mixtures thereof.

38. A method as claimed in claim 37 wherein said non-crosslinkable polymer is a vinyl acetate homopolymer.

39. A method as claimed in any one of claims 23 to 38, wherein said self-reactive crosslinking film-forming polymer is selected from epoxy polymers, polyester polymers, acrylic polymers, and copolymers and mixtures thereof.

40. A method as claimed in claim 39, wherein said self-reative cross-linking polymer is a vinyl acetate copolymer.