EP1725506A2 - Sized glass fibres which are intended to reinforce polymer materials, such as by means of moulding - Google Patents

Sized glass fibres which are intended to reinforce polymer materials, such as by means of moulding

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Publication number
EP1725506A2
EP1725506A2 EP04805872A EP04805872A EP1725506A2 EP 1725506 A2 EP1725506 A2 EP 1725506A2 EP 04805872 A EP04805872 A EP 04805872A EP 04805872 A EP04805872 A EP 04805872A EP 1725506 A2 EP1725506 A2 EP 1725506A2
Authority
EP
European Patent Office
Prior art keywords
glass
epoxy
strands
glass strand
copolymer
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.)
Withdrawn
Application number
EP04805872A
Other languages
German (de)
French (fr)
Inventor
Dino Lombino
Claire Metra
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Saint Gobain Adfors SAS
Original Assignee
Saint Gobain Vetrotex France SA
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Saint Gobain Vetrotex France SA filed Critical Saint Gobain Vetrotex France SA
Publication of EP1725506A2 publication Critical patent/EP1725506A2/en
Withdrawn legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
    • C08J5/04—Reinforcing macromolecular compounds with loose or coherent fibrous material
    • C08J5/06—Reinforcing macromolecular compounds with loose or coherent fibrous material using pretreated fibrous materials
    • C08J5/08—Reinforcing macromolecular compounds with loose or coherent fibrous material using pretreated fibrous materials glass fibres
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C25/00—Surface treatment of fibres or filaments made from glass, minerals or slags
    • C03C25/10—Coating
    • C03C25/24—Coatings containing organic materials
    • C03C25/26—Macromolecular compounds or prepolymers
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C25/00—Surface treatment of fibres or filaments made from glass, minerals or slags
    • C03C25/10—Coating
    • C03C25/24—Coatings containing organic materials
    • C03C25/26—Macromolecular compounds or prepolymers
    • C03C25/28—Macromolecular compounds or prepolymers obtained by reactions involving only carbon-to-carbon unsaturated bonds

Definitions

  • the invention relates to glass strands coated with a sizing composition intended to reinforce organic materials of the polymer type, the sizing composition used for coating said strands and the composites thus obtained.
  • the glass strands used for reinforcement in general are produced industrially from molten glass streaks flowing from the multiple orifices of a die. These threads are drawn mechanically in the form of continuous filaments, then are gathered into basic threads which are then collected, for example by winding on a rotating support. Before their gathering, the filaments are coated with a sizing composition by passing over a suitable device such as coating rollers.
  • the sizing composition is essential for several reasons.
  • the sizing composition protects the glass filaments from abrasion which occurs when the latter rub at high speed on the various members serving to guide and collect them. It also establishes connections between the filaments which makes it possible to give cohesion to the thread. The yarn being made more intact, its handling, especially during weaving operations, is improved and untimely breaks are avoided.
  • the sizing composition promotes the wetting and impregnation of the glass strands by the matrix to be reinforced, which matrix is generally implemented in the form of a more or less fluid resin. The mechanical properties of the final composite are therefore significantly improved.
  • the materials to be reinforced can integrate glass strands in different forms: continuous or cut strands, continuous or cut strand mats, fabrics, etc.
  • the composites which incorporate cut glass strands can be obtained, inter alia, by the technique of "contact molding” which consists in coating the interior of an open mold, without counter mold, with resin to be reinforced and glass wires of variable length.
  • the resin and the cut wires are projected together onto the internal walls of the mold by means of a "gun” comprising an incorporated cutter capable of cutting the wires extracted from one or more windings, generally in the form of rovings, and from a device making it possible to spray the resin, supplied for example by a pneumatic pump.
  • This simple and modular process is particularly suitable for unit production or small series of parts based on thermosetting polymers belonging to the family of polyesters or epoxides.
  • Another composite manufacturing technique also by molding, is known under the name "LFI" or Long Fiber Injection. It consists in projecting into a mold, simultaneously, wires cut at a high speed (of the order of 300 to 1200 meters per minute) in cycles lasting a few tens of seconds and reactive monomers capable of giving a resin by polymerization, and then applying a counter mold.
  • This technique is particularly suitable for the production of polyurethane parts, in particular in the form of foam.
  • the quality of the composites obtained by these processes depends largely on the properties provided by the glass strands, and therefore on the size which covers them.
  • compositions giving a size which can be easily wetted or impregnated on the surface with the resin in order to ensure close contact between the wires and the resin and thus obtain the expected mechanical reinforcement properties. It is also desired that these compositions are compatible with rapid processing, in particular that the mixture of son / resin or son / monomers which is sprayed onto the mold in the form of overlapping strips can spread evenly. In particular, the subsequent rolling step already mentioned intended to eliminate air bubbles and to ensure a better distribution of the wires in the resin must also be of short duration.
  • the sizing composition it is also necessary for the sizing composition to have a certain “incompatibility” with the resin, that is to say that it is not too soluble in the resin so as to avoid the mixture of yarns / resin forms a compact mass which "collapses" by simple gravity.
  • This parameter is important when it comes to producing very thick parts requiring to spray a large quantity of mixture into the mold.
  • it is sought to reduce the speed of impregnation of the wire with the resin.
  • the impregnation speed should not be too low because then the son / resin mixture has poor "conformability", that is to say that it is not able to perfectly match the shape of the mold.
  • the criterion of conformability is very important when the mold has a large dimension, from a few meters to several tens of meters. It is just as necessary that the cut strands maintain their integrity and do not “filamentize”, that is to say do not burst by releasing the filaments which constitute them, during projection but also during other treatments than they are brought to undergo such as the rolling / boiling operation already mentioned. It is still essential that the wire can be extracted from the roving without forming loops, without generating tension and by giving as little stuffing as possible so as not to disturb the operation of the cutter. Sized glass strands adapted to these molding techniques are already known.
  • glass strands coated with a sizing composition comprising, as tackifying film-forming agents, the combination of at least one low molecular weight polyvinyl acetate A and at least one vinyl acetate copolymer B which is thermally cross-linkable in an A / B weight ratio greater than or equal to 1. These threads have a high rate of impregnation with the resin.
  • the glass strands are coated with an essentially aqueous sizing composition which comprises at least one bis-silane A and at least one unsaturated monosilane (B) chosen from vinylsilanes and methyl ( acrylosilanes).
  • the glass strands are coated with a sizing product comprising an aqueous mixture based on polyvinyl acetate, a lubricant based on fatty acid, chromic methacrylato chloride and gamma (ethylene diamine) propyltrimethoxysilane.
  • a sizing product comprising an aqueous mixture based on polyvinyl acetate, a lubricant based on fatty acid, chromic methacrylato chloride and gamma (ethylene diamine) propyltrimethoxysilane.
  • the strands belonging to the first type are coated with a size based on polyvinyl acetate and compounds comprising chromium.
  • the object of the present invention is to provide a sizing composition for reinforcing threads, in particular intended for open mold molding, in particular for simultaneous projection molding, or for closed mold, in particular for LFI molding, which does not contain no chromium and which makes it possible to obtain performances equivalent to those of glass strands known for these applications, in particular in terms of speed of impregnation of the strands by the resin, production of fiber and integrity.
  • the subject of the invention is glass strands coated with an aqueous sizing composition which comprises, as tackifying film-forming agents, at least one polyvinyl acetate, at least one copolymer of vinyl acetate and of another monomer. unsaturated and at least one epoxy.
  • glass strands coated with a sizing composition which comprises ...” is meant not only the glass strands coated with the composition in question as obtained on immediate exit from the organ or sizing organs, but also these same threads after they have undergone one or more other treatments.
  • son means the basic son from the gathering under the die of a multitude of filaments, and products derived from these son, including the assemblies of these basic son rovings.
  • aqueous sizing composition means a sizing composition in the form of a solution in which the liquid phase consists of 97% by weight of water, preferably 99% and better still 100%, the complement consisting, where appropriate, of one or more essentially organic solvents which can help to dissolve certain constituents of the sizing composition.
  • the sizing composition comprises, as tackifying film-forming agents, the mixture of at least one polyvinyl acetate, at least one copolymer of vinyl acetate and of another unsaturated monomer, and at least an epoxy.
  • Polyvinyl acetate is important for quickly reaching a high level of resin impregnation of the wires and obtaining good conformability of the wire / resin mixture in the mold.
  • the molecular weight of the polyvinyl acetate is generally less than 80,000 g / mol, preferably less than 70,000 g / mol and preferably is between 40,000 and 65,000 g / mol.
  • the amount of polyacetate used generally represents 20 to 50% by weight of the solids of the sizing composition, preferably 30 to 40%.
  • the copolymer is obtained by co-polymerization of vinyl acetate and another unsaturated monomer, for example a monomer of the olefinic type.
  • the monomer is ethylene.
  • the copolymer has a lower solubility in the resin than polyvinyl acetate; it therefore contributes to reducing the speed of impregnation of the wires by the resin. By modulating the content of copolymer relative to that of polyvinyl acetate, it is possible to adjust the properties of the final sizing as well as possible.
  • the amount of copolymer generally represents 20 to 45% by weight of the solids of the composition, preferably 30 to 40%. When the content is greater than 45%, the conformability is insufficient. When the content is less than 20%, the wire loses its stiffness.
  • the weight ratio of polyvinyl acetate to the copolymer varies from 30:70 to 70:30, and better still from 40:60 to 60:40. More preferably, the sum of the contents by weight of polyvinyl acetate and of copolymer represents 50 to 80% by weight of the solid matters of the sizing composition.
  • the epoxy promotes the bonding of the filaments, thereby improving the stiffness of the wire which contributes to having a more homogeneous distribution of the wires cut in the resin after spraying into the mold. It also helps limit the formation of fluff.
  • the epoxy is generally chosen from resins having a molecular weight greater than 5,000 g / mol, preferably less than 20,000 g / mol. They advantageously have an epoxide index greater than 800 g equivalent, preferably between 1,200 and 2,000, and better still of the order of 1,500 g equivalent.
  • epoxy resins resulting from the reaction of epichlorohydrin and an alcohol for example bisphenol A or F, polyethylene glycols, glycerol, pentaerythritol or novolak resins.
  • the epoxy results from the reaction of epichlorohydrin and bisphenol A.
  • the epoxy is used in combination with another epoxy carrying one or more amine functions which has the role of providing stiffness to the wire without significantly affecting conformability.
  • the amount of epoxy generally represents 10 to 20% of the weight of the solids of the sizing composition, preferably 12 to 16%.
  • the sizing composition may advantageously comprise one or more other components (hereinafter referred to as "additives").
  • the sizing composition can thus comprise one or more lubricating agents in an amount representing 1 to 20% by weight of the solids of the sizing composition.
  • the lubricant (s) contribute) to limit the formation of fluff, to increase the stiffness of the wire and to avoid the sticking of the turns on the windings of basic son .
  • these agents are chosen from cationic compounds of the polyalkylene irnide type, and ionic compounds of the ester type of fatty acids and of poly (al ylene glycols) poly (oxyalkylene) such as polyethylene glycol monolaurate, or of the amide type d. fatty acids and poly (o yalkylene) such as hydrogenated tallow amides and polyethylene.
  • the sizing composition can also comprise at least one coupling agent making it possible to hang the sizing on the surface of the glass filaments.
  • the coupling agent is generally chosen from silanes such as gamma-glycidoxypropyltrimethoxysilane, gamma-acryloxypropyltrimethoxysilane, gamma-methacryloxypropyltrimethoxysilane, poly (oxyethylene / oxypropylene) trimet thoxysilane, gamma-amimropyltrioxetane phenyl - aminopropyltrimethoxysilane or slyiylammoélhylarninopropyltriméthoxy-silane, siloxanes, titanates, zirconates and mixtures of these compounds.
  • the silanes are chosen.
  • the amount of coupling agent generally represents less than 5% by weight of the solids of the sizing composition, preferably is greater than 2% and most often is of the order of 3%. All these additives contribute to the production of reinforcement threads which can be easily manufactured, which maintain good integrity, which can be cut without problem and sprayed into a mold while being slowly impregnated with the resin or the resin precursor monomers. . It is also possible to introduce an anti-static agent such as ethyl chloride in the sizing composition. The amount of this agent generally represents less than 5% of the weight of the solid materials contained in the sizing composition.
  • the glass strands coated with the sizing composition in accordance with the invention have a loss on ignition of less than 2.2%, preferably greater than 1.1% and better still between 1.4 and 1.60%.
  • the glass strands according to the invention are in the form of windings of basic strands which are subjected to a heat treatment.
  • This treatment is essentially intended to remove the water provided by the sizing composition and, where appropriate, makes it possible to accelerate the crosslinking of the sticky fihnogenic agents.
  • Treatment conditions may vary depending on the mass of the treatment. In general, the drying is carried out at a temperature of the order of 110 to 140 ° C for several hours, preferably 12 to 18 hours.
  • the yarns coated with the sizing composition according to the invention can be made of glass of any kind as long as it is suitable for being fiber, for example glass E, C, AR (alkali-resistant), or low boron level (less than 5%).
  • These same threads consist of filaments whose diameter can vary to a large extent, for example 9 to 17 ⁇ m, preferably 11 to 13 ⁇ .
  • these threads have a count between 30 and 160 tex, preferably 40 and 60 tex.
  • Such cut glass strands are distributed regularly and homogeneously within the resin, even when the thickness projected onto the mold is large, which makes it possible to have excellent quality reinforcement.
  • Another subject of the invention relates to the sizing composition capable of coating said glass strands, which composition is characterized in that it comprises an aqueous mixture of at least one polyvinyl acetate, of at least one copolymer d vinyl acetate and at least one other unsaturated monomer and at least one epoxy as defined above
  • the sizing composition is an aqueous mixture comprising the constituents below, in the following weight contents expressed as percentages solid materials: - 20 to 50% of at least one polyvinyl acetate, preferably 30 to 40% - 20 to 45% of at least one copolymer of vinyl acetate and at least one other unsaturated monomer, advantageously an olefinic monomer such as ethylene, preferably 30 to 40% - 10 to 20% of at least one epoxy, preferably 12 to 16% - 1 to 20% of at least one lubricating agent, - 0 to 5% of at least one coupling agent, preferably greater than 2% - 0 at 5% of at least one anti-static agent
  • the sizing composition comprises between 5 and 15% by weight of solid matter, preferably between 7 and 12%.
  • the liquid phase consists of 100% water.
  • Another subject of the invention relates to composites comprising glass strands coated with the sizing composition.
  • Such composites comprise at least one thermosetting material, preferably a polyester, a vinylester, an acrylic, a polyurethane, a phenolic or epoxy resin, and glass strands made up, in whole or in part, of glass strands in accordance with invention.
  • the content of glass in the composite is generally between 20 and 45% by weight, and preferably between 25 and 35%.
  • the glass strands give the composites which contain them better resistance to aging, especially in a humid environment.
  • Another subject of the invention is the use of glass strands coated with the sizing composition for the production of parts by the open mold molding technique, in particular by simultaneous spraying of said strands and of resin.
  • the invention also relates to the use of said glass son for the manufacture of molded parts operating in a closed mold, in particular by the LFI technique.
  • the properties relating to glass strands coated with the sizing composition and to the composites incorporating said strands are measured as follows: - the loss on ignition, in percentage, of the sized glass strand is measured under the conditions of the ISO 1887 standard, - the flock is measured by simultaneously passing the strands unwound from 2 rovings on a tie, at a speed of 200 m / ma.
  • the flock is defined by the quantity of fibrils, in mg, obtained after passing through a mass of thread of 3 kg. It is expressed in mg / kg of yarn.
  • a sizing composition is prepared in the form of an aqueous solution comprising, as a percentage by weight of the solid materials: "sticky film-forming agents - polyvinyl acetate (1 ; molecular weight: 50,000 35.7 vinyl acetate copolymer- ethylene ⁇ 35.7 epoxy resin (3) 12.6 amino-epoxy resin (4) 3.7
  • anti-static agent LiCl 4.5
  • water sufficient quantity to give 100 ml of sizing composition
  • the preparation of the sizing composition is carried out as follows: The methoxy groups of the silane (5) are hydrolyzed by adding acid to an aqueous solution of this silane which is kept stirring. The other constituents are then introduced, still with stirring, and the pH is adjusted to a value of 4 ⁇ 0.2, if necessary. The weight content of solid matter in the sizing composition is equal to 10.9%.
  • the sizing composition is used to coat, in a known manner, glass filaments E of approximately 12 ⁇ m in diameter drawn from glass filaments flowing from the orifices of a die, the filaments then being collected in the form of base wire windings with a title equal to 57 tex.
  • the winding is then dried at 130 ° C for 12 hours.
  • the basic threads extracted from 6 windings are brought together to form a roving.
  • the wire thus obtained has a loss on ignition equal to 1.5%.
  • the quantity of fill is equal to 24 mg.
  • EXAMPLE 2 A sizing composition is prepared under the conditions of Example 1, consisting of an aqueous mixture comprising, as a percentage by weight of the solid materials: "sticky film-forming agents - polyvinyl acetate (1) ; molecular weight: 50,000 36, 1 - vinyl acetate-ethylene copolymer ⁇ 36.1 - epoxy resin ⁇ 12.8
  • lubricating agent - mineral oil (6) 5.0 - silicone (7) 2.0 - ethylene glycol monolaurate (9) 3.0 - polyethylene imide polyamide salt (10) 0.3
  • water sufficient quantity to give 100 ml of sizing composition.
  • the weight content of solid matter in the sizing composition is equal to 7.5%.
  • the yarn extracted from a roving obtained under the conditions of Example 1 has a loss on ignition equal to 1.55%.
  • the amount of fill is equal to 3.6 mg.
  • EXAMPLE 3 A sizing composition is prepared under the conditions of Example 1, consisting of an aqueous mixture comprising, as a percentage by weight of the solid materials: "sticky film-forming agents - polyvinyl acetate (1) ; molecular weight: 50,000 34, 8 - vinyl acetate-ethylene copolymer (2) 34.8 - epoxy resin (3) 12.3 - amino-epoxy resin (4) 3.6 "coupling agent - gamma-methacryloxypropyltriethoxysilane (5) 2.2
  • water an amount sufficient to give 100 ml of sizing composition.
  • the weight content of solid matter in the sizing composition is equal to 11.5%.
  • the yarn extracted from a roving obtained under the conditions of the example 1 has a loss on ignition equal to 1.70%.
  • the quantity of fill is equal to 1.5 mg.
  • EXAMPLE S (Comparative) A sizing composition is produced under the conditions of Example 4 modified in that it additionally contains 0.45% by weight of LiCl. The weight content of solid matter in the sizing composition is equal to 9.8%. The yarn extracted from a rovel has a loss on ignition equal to 1.52% The quantity of flock is equal to 7.6 mg. EXAMPLES 6 to 11 The wire obtained according to examples 1 to 5 is used to manufacture composite parts by the technique of molding by simultaneous projection under the following conditions:
  • the mold in which the cut wires and the resin are projected is a stair-shaped mold with a vertical wall 1 m high, then a step 0.20 m deep and 0.2 m high and finally a horizontal wall 1 m long.
  • horizontal wall has two grooves 2 cm deep to assess the conformability of the cut son / resin mixture.
  • the mixture projected onto the mold contains approximately 30% by weight of glass and has an average thickness of the order of 5 mm.
  • the performance of the cut son / resin mixture is evaluated for the following parameters: - boiling / working time respectively corresponding to the ability of the air bubbles to be expelled from the mixture projected onto the mold by passing a boiling roller, and the ability of the wires to be impregnated with the resin, - held in a vertical wall, - conformability, evaluated at the level of the grooves in the horizontal wall, - speed of impregnation of the wires cut by the resin.
  • Examples 6 to 8 according to the invention make it possible to achieve an excellent compromise in terms of application properties: a particularly high vertical wall resistance associated with an impregnation speed which can be modulated according to the size, from moderate (examples 6 and 7) to slow (example 8).
  • the glass strands of Example 3 make it possible in particular to achieve the same level of performance as the glass strands adapted to this technique (Reference 1).
  • the glass strands coated with a size not comprising the mixture of sticky film-forming agents (examples 9 and 10) have insufficient conformability.
  • the yarns according to the invention have a lower wadding production than the yarns provided for the intended application (Reference 1). In Example 8, the fluff production is considerably reduced.
  • EXAMPLES 12 AND 13 The performance of the wire according to Example 3 is evaluated for the LFI application compared to the OC 900 wire (Reference 2) suitable for this technique.
  • the parameters are: - the number of loops present on 500 meters of wire unwound from a winding, generally a roving, - the integrity of the wire subject to the following conditions: the wire unwound from a roving is introduced in a WOLFANGEL 500 cutter which cuts and projects it substantially horizontally on a vertical wall (cutting speed: 1200 mmin; length: 12 mm).
  • the integrity of the cut wire is visually measured on a scale of values ranging from 1 (poor, cottony appearance) to 5 (very good, no breakage of the wire) the impregnation speed of the wire cut by the resin, measured visually on a scale ranging from 1 (very slow speed) to 5 (very fast).
  • Example 12 Example 13 Thread Example 3 Reference 2 Number of loops 30 43 Integrity 3.5 3.5 Impregnation speed 1 1
  • the thread according to the invention has a reduced number of loops compared to the spooling for integrity and speed d 'identical impregnation.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Geochemistry & Mineralogy (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • General Chemical & Material Sciences (AREA)
  • Polymers & Plastics (AREA)
  • Medicinal Chemistry (AREA)
  • Health & Medical Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Treatments For Attaching Organic Compounds To Fibrous Goods (AREA)
  • Surface Treatment Of Glass Fibres Or Filaments (AREA)
  • Reinforced Plastic Materials (AREA)
  • Laminated Bodies (AREA)

Abstract

The invention relates to glass fibres which are covered with a sizing composition comprising, by way of adhesive film forming agents, at least one polyvinyl acetate, at least one copolymer of vinyl acetate and of one other unsaturated monomer and at least one epoxy. The glass fibres thus obtained are used as reinforcement in the production of thermosetting matrix moulded parts obtained by means of open-mould moulding, for example, with the simultaneous projection of said fibres and resin, or using a closed mould, for example, by means of LFI.

Description

FILS DE VERRE ENSIMES DESTINES AU RENFORCEMENT DE MATIERES POLYMERES, NOTAMMENT PAR MOU AGE.SIZED GLASS WIRES FOR THE REINFORCEMENT OF POLYMERIC MATERIALS, PARTICULARLY BY FLYING.
L'invention concerne des fils de verre revêtus d'une composition d'ensimage destinés à renforcer des matières organiques du type polymère, la composition d'ensimage utilisée pour revêtir lesdits fils et les composites ainsi obtenus. Les fils de verre utilisés pour le renforcement en général sont produits industriellement à partir de filets de verre fondu s'écoulant des multiples orifices d'une filière. Ces filets sont étirés mécaniquement sous la forme de filaments continus, puis sont rassemblés en fils de base qui sont ensuite collectés, par exemple par bobinage sur un support en rotation. Avant leur rassemblement, les filaments sont revêtus d'une composition d'ensimage par passage sur un dispositif adapté tel que des rouleaux d'enduction. La composition d'ensimage s'avère essentielle à plusieurs titres. Lors de la fabrication des fils de renforcement, la composition d'ensimage protège les filaments de verre de l'abrasion qui se produit lorsque ces derniers frottent à grande vitesse sur les différents organes servant à les guider et à les collecter. Elle établit également des liaisons entre les filaments ce qui permet de donner de la cohésion au fil. Le fil étant rendu plus intègre, sa manipulation, notamment lors des opérations de tissage, s'en trouve améliorée et les ruptures intempestives sont évitées. Lors de la fabrication des matériaux composites, la composition d'ensimage favorise le mouillage et Pimprégnation des fils de verre par la matrice à renforcer, laquelle matrice est généralement mise en œuvre sous la forme d'une résine plus ou moins fluide. Les propriétés mécaniques du composite final sont de ce iàit nettement améliorées. Les matières à renforcer peuvent intégrer les fils de verre sous différentes formes : fils continus ou coupés, mats de fils continus ou coupés, tissus, ... Les composites qui incorporent des fils de verre coupés peuvent être obtenus, entre autres, par la technique de «moulage au contact» qui consiste à enduire l'intérieur d'un moule ouvert, sans contre-moule, avec de la résine à renforcer et des fils de verre de longueur variable. Dans le procédé particulier de « moulage par projection simultanée », la résine et les fils coupés sont projetés ensemble sur les parois internes du moule au moyen d'un «pistolet» comprenant un coupeur incorporé apte à sectionner les fils extraits d'un ou plusieurs enroulements, en général se présentant sous la forme de stratifils, et d'un dispositif permettant de pulvériser la résine, alimenté par exemple par une pompe pneumatique. Ce procédé, simple et modulable, est particulièrement adapté à la production à l'unité ou en petite série de pièces à base de polymères thermodurcissables appartenant à la famille des polyesters ou des époxydes. Une autre technique de fabrication de composites, également par moulage, est connue sous la dénomination « LFI » ou Long Fiber Injection. Elle consiste à projeter dans un moule, de manière simultanée, des fils coupés à une vitesse élevée (de l'ordre de 300 à 1200 mètres par minute) par cycles d'une durée de quelques dizaines de secondes et des monomères réactifs aptes à donner une résine par polymérisation, et à appliquer ensuite un contre-moule. Cette technique est particulièrement adaptée à la réalisation de pièces en polyuréthane, notamment sous la forme de mousse. La qualité des composites obtenus par ces procédés dépend largement des propriétés apportées par les fils de verre, et donc de l'ensimage qui les revêt. Notamment, on cherche à obtenir des compositions donnant un ensimage qui peut être facilement mouillé ou imprégné en surface par la résine afin d'assurer un contact étroit entre les fils et la résine et obtenir ainsi les propriétés mécaniques de renforcement attendues. Il est également souhaité que ces compositions soient compatibles avec une mise en œuvre rapide, en particulier que le mélange fils/résine ou fils/monomères qui est projeté sur le moule sous la forme de bandes chevauchantes puisse s'étaler uniformément. Notamment, l'étape subséquente de roulage déjà mentionnée destinée à éliminer les bulles d'air et à assurer une meilleure répartition des fils dans la résine doit aussi être de courte durée. Mais par ailleurs, il est nécessaire que la composition d'ensimage ait une certaine « incompatibilité » avec la résine, c'est-à-dire qu'elle ne soit pas trop soluble dans la résine de manière à éviter que le mélange fils/résine forme une masse compacte qui « s'effondre » par simple gravité. Ce paramètre est important lorsqu'il s'agit de produire des pièces de forte épaisseur nécessitant de projeter une quantité importante de mélange dans le moule. Dans ce cas, on cherche à diminuer la vitesse d'imprégnation du fil par la résine. Néanmoins, la vitesse d'imprégnation ne doit pas être trop faible car alors le mélange fils/résine a une mauvaise « conformabilité » c'est-à-dire qu'il n'est pas apte à épouser parfaitement la forme du moule. Le critère de conformabilité revêt toute son importance lorsque le moule a une grande dimension, de quelques mètres à plusieurs dizaines de mètres. Il est tout aussi nécessaire que les fils coupés conservent leur intégrité et ne se « filamentisent » pas c'est-à-dire n'éclatent pas en libérant les filaments qui les constituent, pendant la projection mais aussi au cours des autres traitements qu'ils sont amenés à subir tels que l'opération de roulage/ébullage déjà mentionnée. Il est encore indispensable que le fil puisse être extrait du stratifil sans former de boucles, sans générer de tension et en donnant le moins de bourre possible afin de ne pas perturber le fonctionnement du coupeur. On connaît déjà des fils de verre ensimés adaptés à ces techniques de moulage. Dans EP-A-0 869 927, il est décrit des fils de verre revêtus d'une composition d'ensimage comprenant, en tant qu'agents filmogènes collants, l'association d'au moins un acétate de polyvinyle A de bas poids moléculaire et d'au moins un copolymère d'acétate de vinyle B autoréticulable thermiquement dans un rapport pondéral A/B supérieur ou égal à 1. Ces fils présentent une vitesse élevée d'imprégnation par la résine. Dans WO-A-02/059055, les fils de verre sont revêtus d'une composition d'ensimage essentiellement aqueuse qui comprend au moins un bis-silane A et au moins un monosilane insaturé (B) choisi parmi les vinylsilanes et les méthyl(acrylosilanes). L'ensimage permet d'augmenter la durée de vie des lames du coupeur. La vitesse d'imprégnation des fils est importante. Dans FR-A-2 279 688, on revêt les fils de verre d'un produit d'ensimage comprenant un mélange aqueux à base d'acétate de polyvinyle, d'un lubrifiant à base d'acide gras, de chlorure méthacrylato chromique et de gamma(éthylène diamine) propyltriméthoxysilane. On connaît encore deux types de fils de verre adaptés au moulage commercialisés par la société Owens Corning. Les fils appartenant au premier type (référence OC 1662) sont revêtus d'un ensimage à base de polyacétate de vinyle et de composés comprenant du chrome. Si ces fils s'avèrent satisfaisants du point de vue de leurs propriétés et de leur aptitude au moulage par projection simultanée, ils présentent l'inconvénient de contenir du chrome qui sous certains aspects peut s'avérer toxique et/ou présenter des risques de pollution pour l'environnement. Les fils du deuxième type (référence OC 900) sont revêtus d'un ensimage comprenant un polymère d'acétate de vinyle et de méthylolacrylamide et ils sont adaptés plus particulièrement à la technique LFI. Néanmoins, le niveau de performances s'avère insuffisant au regard de certains paramètres : le nombre de boucles présentes par unité de longueur de fil reste élevé et l'intégrité du fil demeure faible. La présente invention a pour but de proposer une composition d'ensimage pour des fils de renforcement, notamment destinés au moulage à moule ouvert, en particulier au moulage par projection simultanée, ou à moule fermé, en particulier au moulage par LFI, qui ne contient pas de chrome et qui permette d'obtenir des performances équivalentes à celles de fils de verre connus pour ces applications, notamment en terme de vitesse d'imprégnation des fils par la résine, de production de bourre et d'intégrité. L'invention a pour objet des fils de verre revêtus d'une composition d'ensimage aqueuse qui comprend en tant qu'agents filmogènes collants au moins un polyacétate de vinyle, au moins un copolymère d'acétate de vinyle et d'un autre monomère insaturé et au moins un époxy . Dans la présente invention, par « fils de verre revêtus d'une composition d'ensimage qui comprend... », on entend non seulement les fils de verre revêtus de la composition en question tels qu'obtenus à la sortie immédiate de l'organe ou des organes d'ensimage, mais aussi ces mêmes fils après qu'ils ont subi un ou plusieurs autres traitements. A titre d'exemple, on peut citer les opérations de séchage visant à éliminer la phase liquide de la composition, et les traitements conduisant à la polymérisation/réticulation de certains constituants de la composition d'ensimage. Toujours dans le contexte de l'invention, par « fils » il faut entendre les fils de base issus du rassemblement sous la filière d'une multitude de filaments, et les produits dérivés de ces fils, notamment les assemblages de ces fils de base en stratifils. De tels assemblages peuvent être obtenus en dévidant simultanément plusieurs enroulements de fils de base, puis en les rassemblant en mèches qui sont bobinées sur un support en rotation. Ce peut être également des stratifils « directs » de titre (ou de masse linéique) équivalent à celui des stratifils assemblés, obtenus par le rassemblement de filaments directement sous la filière et l'enroulement sur un support en rotation. Encore selon l'invention, on entend par « composition d'ensimage aqueuse » une composition d'ensimage sous forme d'une solution dans laquelle la phase liquide est constituée à 97 % en poids d'eau, de préférence 99 % et mieux encore 100 %, le complément étant constitué le cas échéant d'un ou plusieurs solvants essentiellement organiques pouvant aider à solubiliser certains constituants de la composition d'ensimage. Conformément à l'invention, la composition d'ensimage comprend en tant qu'agents fihnogènes collants le mélange d'au moins un polyacétate de vinyle, au moins un copolymère d'acétate de vinyle et d'un autre monomère insaturé, et au moins un époxy. Le polyacétate de vinyle est important pour atteindre rapidement un niveau élevé d'imprégnation des fils par la résine et obtenir une bonne conformabilité du mélange fils/résine dans le moule. Le poids moléculaire du polyacétate de vinyle est généralement inférieur à 80 000 g/mol, de préférence inférieur à 70 000 g/mol et de préférence est compris entre 40 000 et 65 000 g/mol. La quantité de polyacétate utilisée représente généralement 20 à 50 % en poids des matières solides de la composition d'ensimage, de préférence 30 à 40 %. Le copolymère est obtenu par co-polymérisation d'acétate de vinyle et d'un autre monomère insaturé, par exemple un monomère du type oléfînique. De préférence, le monomère est l'éthylène. Le copolymère présente une solubilité dans la résine plus faible que le polyacétate de vinyle ; il contribue de ce fait à diminuer la vitesse d'imprégnation des fils par la résine. En modulant la teneur en copolymère par rapport à celle du polyacétate de vinyle, il est possible d'ajuster au mieux les propriétés de l'encollage final. La quantité de copolymère représente généralement 20 à 45 % au poids des matières solides de la composition, de préférence 30 à 40 %. Lorsque la teneur est supérieure à 45 %, la conformabilité est insuffisante. Lorsque la teneur est inférieure à 20 %, le fil perd de sa raideur. De préférence, le rapport pondéral du polyacétate de vinyle au copolymère varie de 30:70 à 70:30, et mieux encore de 40:60 à 60:40. De préférence encore, la somme des teneurs pondérales en polyacétate de vinyle et en copolymère représente 50 à 80 % en poids des matières solides de la composition d'ensimage. L'époxy favorise la liaison des filaments, permettant ainsi d'améliorer la raideur du fil ce qui participe à avoir une répartition plus homogène des fils coupés dans la résine après projection dans le moule. Il contribue aussi à limiter la formation de bourre. L'époxy est généralement choisi parmi les résines présentant un poids moléculaire supérieur à 5 000 g/mol, de préférence inférieur à 20 000 g/mol. Elles possèdent avantageusement un indice d'époxyde supérieur à 800 g équivalent, de préférence compris entre 1 200 et 2 000, et mieux encore de l'ordre de 1 500 g équivalent. A titre d'exemples, on peut citer les résines époxy résultant de la réaction d'épichlorhydrine et d'un alcool, par exemple le bisphénol A ou F, les polyéthylèneglycols, le glycérol, le pentaérythritol ou les résines novolaques. De préférence, l'époxy résulte de la réaction d'épichlorhydrine et de bisphénol A. De manière avantageuse, l'époxy est utilisé en association avec un autre époxy portant une ou plusieurs fonctions aminé qui a pour rôle d'apporter de la raideur au fil sans affecter signifîcativement la conformabilité. La quantité d'époxy représente généralement 10 à 20 % du poids des matières solides de la composition d'ensimage, de préférence 12 à 16 %. En plus des composants précités qui participent essentiellement à la structure de l'ensimage, la composition d'ensimage peut comprendre avantageusement un ou plusieurs autres composants (ci-après désignés par « additifs »). La composition d'ensimage peut ainsi comprendre un ou des agents lubrifiants en une quantité représentant 1 à 20 % en poids des matières solides de la composition d'ensimage. Outre le rôle de protection des filaments contre l'abrasion mécanique, le(s) lubrifiant(s) contribuent) à limiter la formation de bourre, à augmenter la raideur du fil et à éviter le collage des spires sur les enroulements de fils de base. En général, ces agents sont choisis parmi les composés cationiques du type polyalkylène irnide, et les composés ioniques du type esters d'acides gras et de poly(al ylèneglycols) poly(oxyalkylène) tel que le monolaurate de polyéthylèneglycol, ou du type amides d'acides gras et de ρoly(o yalkylène) tels que les amides de suif hydrogénés et de polyéthylène. La composition d'ensimage peut encore comprendre au moins un agent de couplage permettant d'accrocher l'ensimage à la surface des filaments de verre. L'agent de couplage est généralement choisi parmi les silanes tels que le gamma- glycidoxypropyltriméthoxysilane, le gamma-acryloxypropyltriméthoxysilane, le gamma-méthacryloxypropyltriméthoxysilane, le poly(oxyéthylène/oxypropylène) trimé- thoxysilane, le gamma-am opropyltriéthoxysilane, le vinyltriméthoxysilane, le phényl- aminopropyltriméthoxysilane ou le slyiylammoélhylarninopropyltriméthoxy-silane, les siloxanes, le titanates, les zirconates et les mélanges de ces composés. De préférence, on choisit les silanes. La quantité d'agent de couplage représente généralement moins de 5 % en poids des matières solides de la composition d'ensimage, de préférence est supérieure à 2 % et le plus souvent est de l'ordre de 3 %. Tous ces additifs concourent à l'obtention de fils de renforcement que l'on peut fabriquer facilement, qui conservent une bonne intégrité, qui peuvent être coupés sans problème et projetés dans un moule en étant imprégnés lentement par la résine ou les monomères précurseurs de résine. Il est encore possible d'introduire un agent anti-statique tel que du chlorure de ïïthium dans la composition d'ensimage. La quantité de cet agent représente généralement moins de 5 % du poids des matières solides contenues dans la composition d'ensimage. Les fils de verre revêtus de la composition d'ensimage conforme à l'invention présentent une perte au feu inférieure à 2,2 %, de préférence supérieure à 1,1 % et mieux encore comprise entre 1,4 et 1,60 %. Le plus souvent, les fils de verre conformes à l'invention se présentent sous la forme d'enroulements de fils de base que l'on soumet à un traitement thermique. Ce traitement est destiné essentiellement à éliminer l'eau apportée par la composition d'ensimage et, le cas échéant permet d'accélérer la réticulation des agents fihnogènes collants. Les conditions du traitement peuvent varier selon la masse de l'emoulement. En général, le séchage est réalisé à une température de l'ordre de 110 à 140°C pendant plusieurs heures, de préférence 12 à 18 heures. Les fils revêtus de la composition d'ensimage selon l'invention peuvent être constitués de verre de toute nature pour autant qu'il soit apte à être fibre, par exemple du verre E, C, AR (alcali-résistant), ou à bas taux de bore (moins de 5 %). Ces mêmes fils sont constitués de filaments dont le diamètre peut varier dans une large mesure, par exemple 9 à 17 μm, de préférence 11 à 13 μ . De manière avantageuse, ces fils ont un titre compris entre 30 et 160 tex, de préférence 40 et 60 tex. De tels fils de verre coupés se répartissent de façon régulière et homogène au sein de la résine, même lorsque l'épaisseur projetée sur le moule est importante, ce qui permet d'avoir un renforcement d'excellente qualité. Un autre objet de l'invention concerne la composition d'ensimage apte à revêtir lesdits fils de verre, laquelle composition se caractérise en ce qu'elle comprend un mélange aqueux d'au moins un polyacétate de vinyle, d'au moins un copolymère d'acétate de vinyle et d'au moins un autre monomère insaturé et d'au moins un époxy tels que définis ci-avant La composition d'ensimage est un mélange aqueux comprenant les constituants ci-après, dans les teneurs pondérales suivantes exprimées en pourcentages des matières solides : - 20 à 50 % d'au moins un polyacétate de vinyle, de préférence 30 à 40 % - 20 à 45 % d'au moins un copolymère d'acétate de vinyle et d'au moins un autre monomère insaturé, avantageusement un monomère oléfinique tel que l'éthylène, de préférence 30 à 40 % - 10 à 20 % d'au moins un époxy, de préférence 12 à 16 % - 1 à 20 % d'au moins un agent lubrifiant, - 0 à 5 % d'au moins un agent de couplage, de préférence supérieur à 2 % - 0 à 5 % d'au moins un agent anti-statique. De préférence, la composition d'ensimage comprend entre 5 et 15 % en poids de matières solides, de préférence entre 7 et 12 %. De manière avantageuse, la phase liquide est constituée à 100 % d'eau. Un autre objet de l'invention concerne les composites comprenant les fils de verre revêtus de la composition d'ensimage. De tels composites comprennent au moins une matière thermodurcissable, de préférence un polyester, un vinylester, un acrylique, un polyuréthane, une résine phénolique ou époxy, et des fils de verre constitués, pour tout ou partie, de fils de verre conformes à l'invention. Le taux de verre au sein du composite est généralement compris entre 20 et 45 % en poids, et de préférence entre 25 et 35 %. En plus de leurs avantages liés à la mise en œuvre par moulage (vitesse d'imprégnation lente et bonne conformabilité), les fils de verre confèrent aux composites qui les renferment une meilleure résistance au vieillissement, notamment en milieu humide. L'invention a aussi pour objet l'utilisation des fils de verre revêtus de la composition d'ensimage pour la réalisation de pièces par la technique de moulage à moule ouvert, notamment par projection simultanée desdits fils et de résine. L'invention a encore pour objet l'utilisation desdits fils de verre pour la fabrication de pièces moulées opérant dans un moule fermé, notamment par la technique LFI. Les exemples qui suivent permettent d'illustrer l'invention sans toutefois la limiter. Dans ces exemples, les propriétés relatives aux fils de verre revêtus de la composition d'ensimage et aux composites incorporant lesdits fils sont mesurés comme suit : - la perte au feu, en pourcentage, du fil de verre ensimé est mesurée dans les conditions de la norme ISO 1887, - la bourre est mesurée en faisant passer simultanément les mèches dévidées à partir de 2 stratifils sur un embarrage, à la vitesse de 200 m/ma. La bourre est définie par la quantité de fibrilles, en mg, obtenue après défilement d'une masse de fil de 3 kg. Elle est exprimée en mg/kg de fil. EXEMPLE 1 On prépare une composition d'ensimage sous la forme d'une solution aqueuse comprenant, en pourcentage pondéral des matières solides : " agents fihnogènes collants - polyacétate de vinyle (1 ; poids moléculaire : 50 000 35,7 copolymère acétate de vinyle-éthylène ^ 35,7 résine époxy (3) 12,6 résine amino-époxy (4) 3,7The invention relates to glass strands coated with a sizing composition intended to reinforce organic materials of the polymer type, the sizing composition used for coating said strands and the composites thus obtained. The glass strands used for reinforcement in general are produced industrially from molten glass streaks flowing from the multiple orifices of a die. These threads are drawn mechanically in the form of continuous filaments, then are gathered into basic threads which are then collected, for example by winding on a rotating support. Before their gathering, the filaments are coated with a sizing composition by passing over a suitable device such as coating rollers. The sizing composition is essential for several reasons. During the manufacture of the reinforcing threads, the sizing composition protects the glass filaments from abrasion which occurs when the latter rub at high speed on the various members serving to guide and collect them. It also establishes connections between the filaments which makes it possible to give cohesion to the thread. The yarn being made more intact, its handling, especially during weaving operations, is improved and untimely breaks are avoided. During the manufacture of the composite materials, the sizing composition promotes the wetting and impregnation of the glass strands by the matrix to be reinforced, which matrix is generally implemented in the form of a more or less fluid resin. The mechanical properties of the final composite are therefore significantly improved. The materials to be reinforced can integrate glass strands in different forms: continuous or cut strands, continuous or cut strand mats, fabrics, etc. The composites which incorporate cut glass strands can be obtained, inter alia, by the technique of "contact molding" which consists in coating the interior of an open mold, without counter mold, with resin to be reinforced and glass wires of variable length. In the particular method of "simultaneous projection molding", the resin and the cut wires are projected together onto the internal walls of the mold by means of a "gun" comprising an incorporated cutter capable of cutting the wires extracted from one or more windings, generally in the form of rovings, and from a device making it possible to spray the resin, supplied for example by a pneumatic pump. This simple and modular process is particularly suitable for unit production or small series of parts based on thermosetting polymers belonging to the family of polyesters or epoxides. Another composite manufacturing technique, also by molding, is known under the name "LFI" or Long Fiber Injection. It consists in projecting into a mold, simultaneously, wires cut at a high speed (of the order of 300 to 1200 meters per minute) in cycles lasting a few tens of seconds and reactive monomers capable of giving a resin by polymerization, and then applying a counter mold. This technique is particularly suitable for the production of polyurethane parts, in particular in the form of foam. The quality of the composites obtained by these processes depends largely on the properties provided by the glass strands, and therefore on the size which covers them. In particular, it is sought to obtain compositions giving a size which can be easily wetted or impregnated on the surface with the resin in order to ensure close contact between the wires and the resin and thus obtain the expected mechanical reinforcement properties. It is also desired that these compositions are compatible with rapid processing, in particular that the mixture of son / resin or son / monomers which is sprayed onto the mold in the form of overlapping strips can spread evenly. In particular, the subsequent rolling step already mentioned intended to eliminate air bubbles and to ensure a better distribution of the wires in the resin must also be of short duration. However, it is also necessary for the sizing composition to have a certain “incompatibility” with the resin, that is to say that it is not too soluble in the resin so as to avoid the mixture of yarns / resin forms a compact mass which "collapses" by simple gravity. This parameter is important when it comes to producing very thick parts requiring to spray a large quantity of mixture into the mold. In this case, it is sought to reduce the speed of impregnation of the wire with the resin. However, the impregnation speed should not be too low because then the son / resin mixture has poor "conformability", that is to say that it is not able to perfectly match the shape of the mold. The criterion of conformability is very important when the mold has a large dimension, from a few meters to several tens of meters. It is just as necessary that the cut strands maintain their integrity and do not “filamentize”, that is to say do not burst by releasing the filaments which constitute them, during projection but also during other treatments than they are brought to undergo such as the rolling / boiling operation already mentioned. It is still essential that the wire can be extracted from the roving without forming loops, without generating tension and by giving as little stuffing as possible so as not to disturb the operation of the cutter. Sized glass strands adapted to these molding techniques are already known. In EP-A-0 869 927, there are described glass strands coated with a sizing composition comprising, as tackifying film-forming agents, the combination of at least one low molecular weight polyvinyl acetate A and at least one vinyl acetate copolymer B which is thermally cross-linkable in an A / B weight ratio greater than or equal to 1. These threads have a high rate of impregnation with the resin. In WO-A-02/059055, the glass strands are coated with an essentially aqueous sizing composition which comprises at least one bis-silane A and at least one unsaturated monosilane (B) chosen from vinylsilanes and methyl ( acrylosilanes). The sizing increases the lifespan of the cutter blades. The speed of impregnation of the wires is important. In FR-A-2 279 688, the glass strands are coated with a sizing product comprising an aqueous mixture based on polyvinyl acetate, a lubricant based on fatty acid, chromic methacrylato chloride and gamma (ethylene diamine) propyltrimethoxysilane. There are also two known types of glass strands suitable for molding sold by the company Owens Corning. The strands belonging to the first type (reference OC 1662) are coated with a size based on polyvinyl acetate and compounds comprising chromium. If these threads prove satisfactory from the point of view of their properties and their aptitude for molding by simultaneous projection, they have the drawback of containing chromium which in certain aspects can prove toxic and / or present pollution risks. for the environment. The son of the second type (reference OC 900) are coated with a sizing composition comprising a vinyl acetate and methylolacrylamide polymer and they are more particularly suited to the LFI technique. However, the performance level proves to be insufficient with regard to certain parameters: the number of loops present per unit of wire length remains high and the integrity of the wire remains low. The object of the present invention is to provide a sizing composition for reinforcing threads, in particular intended for open mold molding, in particular for simultaneous projection molding, or for closed mold, in particular for LFI molding, which does not contain no chromium and which makes it possible to obtain performances equivalent to those of glass strands known for these applications, in particular in terms of speed of impregnation of the strands by the resin, production of fiber and integrity. The subject of the invention is glass strands coated with an aqueous sizing composition which comprises, as tackifying film-forming agents, at least one polyvinyl acetate, at least one copolymer of vinyl acetate and of another monomer. unsaturated and at least one epoxy. In the present invention, by “glass strands coated with a sizing composition which comprises ...”, is meant not only the glass strands coated with the composition in question as obtained on immediate exit from the organ or sizing organs, but also these same threads after they have undergone one or more other treatments. By way of example, mention may be made of the drying operations aimed at eliminating the liquid phase from the composition, and the treatments leading to the polymerization / crosslinking of certain constituents of the sizing composition. Still in the context of the invention, by "son" means the basic son from the gathering under the die of a multitude of filaments, and products derived from these son, including the assemblies of these basic son rovings. Such assemblies can be obtained by simultaneously unwinding several windings of basic wires, then by assembling them into wicks which are wound on a rotating support. It can also be "direct" rovings with a title (or linear density) equivalent to that of the assembled rovings, obtained by gathering filaments directly under the die and winding on a rotating support. Still according to the invention, the term "aqueous sizing composition" means a sizing composition in the form of a solution in which the liquid phase consists of 97% by weight of water, preferably 99% and better still 100%, the complement consisting, where appropriate, of one or more essentially organic solvents which can help to dissolve certain constituents of the sizing composition. According to the invention, the sizing composition comprises, as tackifying film-forming agents, the mixture of at least one polyvinyl acetate, at least one copolymer of vinyl acetate and of another unsaturated monomer, and at least an epoxy. Polyvinyl acetate is important for quickly reaching a high level of resin impregnation of the wires and obtaining good conformability of the wire / resin mixture in the mold. The molecular weight of the polyvinyl acetate is generally less than 80,000 g / mol, preferably less than 70,000 g / mol and preferably is between 40,000 and 65,000 g / mol. The amount of polyacetate used generally represents 20 to 50% by weight of the solids of the sizing composition, preferably 30 to 40%. The copolymer is obtained by co-polymerization of vinyl acetate and another unsaturated monomer, for example a monomer of the olefinic type. Preferably, the monomer is ethylene. The copolymer has a lower solubility in the resin than polyvinyl acetate; it therefore contributes to reducing the speed of impregnation of the wires by the resin. By modulating the content of copolymer relative to that of polyvinyl acetate, it is possible to adjust the properties of the final sizing as well as possible. The amount of copolymer generally represents 20 to 45% by weight of the solids of the composition, preferably 30 to 40%. When the content is greater than 45%, the conformability is insufficient. When the content is less than 20%, the wire loses its stiffness. Preferably, the weight ratio of polyvinyl acetate to the copolymer varies from 30:70 to 70:30, and better still from 40:60 to 60:40. More preferably, the sum of the contents by weight of polyvinyl acetate and of copolymer represents 50 to 80% by weight of the solid matters of the sizing composition. The epoxy promotes the bonding of the filaments, thereby improving the stiffness of the wire which contributes to having a more homogeneous distribution of the wires cut in the resin after spraying into the mold. It also helps limit the formation of fluff. The epoxy is generally chosen from resins having a molecular weight greater than 5,000 g / mol, preferably less than 20,000 g / mol. They advantageously have an epoxide index greater than 800 g equivalent, preferably between 1,200 and 2,000, and better still of the order of 1,500 g equivalent. By way of examples, mention may be made of epoxy resins resulting from the reaction of epichlorohydrin and an alcohol, for example bisphenol A or F, polyethylene glycols, glycerol, pentaerythritol or novolak resins. Preferably, the epoxy results from the reaction of epichlorohydrin and bisphenol A. Advantageously, the epoxy is used in combination with another epoxy carrying one or more amine functions which has the role of providing stiffness to the wire without significantly affecting conformability. The amount of epoxy generally represents 10 to 20% of the weight of the solids of the sizing composition, preferably 12 to 16%. In addition to the aforementioned components which essentially participate in the structure of the sizing, the sizing composition may advantageously comprise one or more other components (hereinafter referred to as "additives"). The sizing composition can thus comprise one or more lubricating agents in an amount representing 1 to 20% by weight of the solids of the sizing composition. In addition to the protective role of the filaments against mechanical abrasion, the lubricant (s) contribute) to limit the formation of fluff, to increase the stiffness of the wire and to avoid the sticking of the turns on the windings of basic son . In general, these agents are chosen from cationic compounds of the polyalkylene irnide type, and ionic compounds of the ester type of fatty acids and of poly (al ylene glycols) poly (oxyalkylene) such as polyethylene glycol monolaurate, or of the amide type d. fatty acids and poly (o yalkylene) such as hydrogenated tallow amides and polyethylene. The sizing composition can also comprise at least one coupling agent making it possible to hang the sizing on the surface of the glass filaments. The coupling agent is generally chosen from silanes such as gamma-glycidoxypropyltrimethoxysilane, gamma-acryloxypropyltrimethoxysilane, gamma-methacryloxypropyltrimethoxysilane, poly (oxyethylene / oxypropylene) trimet thoxysilane, gamma-amimropyltrioxetane phenyl - aminopropyltrimethoxysilane or slyiylammoélhylarninopropyltriméthoxy-silane, siloxanes, titanates, zirconates and mixtures of these compounds. Preferably, the silanes are chosen. The amount of coupling agent generally represents less than 5% by weight of the solids of the sizing composition, preferably is greater than 2% and most often is of the order of 3%. All these additives contribute to the production of reinforcement threads which can be easily manufactured, which maintain good integrity, which can be cut without problem and sprayed into a mold while being slowly impregnated with the resin or the resin precursor monomers. . It is also possible to introduce an anti-static agent such as ethyl chloride in the sizing composition. The amount of this agent generally represents less than 5% of the weight of the solid materials contained in the sizing composition. The glass strands coated with the sizing composition in accordance with the invention have a loss on ignition of less than 2.2%, preferably greater than 1.1% and better still between 1.4 and 1.60%. Most often, the glass strands according to the invention are in the form of windings of basic strands which are subjected to a heat treatment. This treatment is essentially intended to remove the water provided by the sizing composition and, where appropriate, makes it possible to accelerate the crosslinking of the sticky fihnogenic agents. Treatment conditions may vary depending on the mass of the treatment. In general, the drying is carried out at a temperature of the order of 110 to 140 ° C for several hours, preferably 12 to 18 hours. The yarns coated with the sizing composition according to the invention can be made of glass of any kind as long as it is suitable for being fiber, for example glass E, C, AR (alkali-resistant), or low boron level (less than 5%). These same threads consist of filaments whose diameter can vary to a large extent, for example 9 to 17 μm, preferably 11 to 13 μ. Advantageously, these threads have a count between 30 and 160 tex, preferably 40 and 60 tex. Such cut glass strands are distributed regularly and homogeneously within the resin, even when the thickness projected onto the mold is large, which makes it possible to have excellent quality reinforcement. Another subject of the invention relates to the sizing composition capable of coating said glass strands, which composition is characterized in that it comprises an aqueous mixture of at least one polyvinyl acetate, of at least one copolymer d vinyl acetate and at least one other unsaturated monomer and at least one epoxy as defined above The sizing composition is an aqueous mixture comprising the constituents below, in the following weight contents expressed as percentages solid materials: - 20 to 50% of at least one polyvinyl acetate, preferably 30 to 40% - 20 to 45% of at least one copolymer of vinyl acetate and at least one other unsaturated monomer, advantageously an olefinic monomer such as ethylene, preferably 30 to 40% - 10 to 20% of at least one epoxy, preferably 12 to 16% - 1 to 20% of at least one lubricating agent, - 0 to 5% of at least one coupling agent, preferably greater than 2% - 0 at 5% of at least one anti-static agent. Preferably, the sizing composition comprises between 5 and 15% by weight of solid matter, preferably between 7 and 12%. Advantageously, the liquid phase consists of 100% water. Another subject of the invention relates to composites comprising glass strands coated with the sizing composition. Such composites comprise at least one thermosetting material, preferably a polyester, a vinylester, an acrylic, a polyurethane, a phenolic or epoxy resin, and glass strands made up, in whole or in part, of glass strands in accordance with invention. The content of glass in the composite is generally between 20 and 45% by weight, and preferably between 25 and 35%. In addition to their advantages linked to processing by molding (slow impregnation speed and good conformability), the glass strands give the composites which contain them better resistance to aging, especially in a humid environment. Another subject of the invention is the use of glass strands coated with the sizing composition for the production of parts by the open mold molding technique, in particular by simultaneous spraying of said strands and of resin. The invention also relates to the use of said glass son for the manufacture of molded parts operating in a closed mold, in particular by the LFI technique. The following examples illustrate the invention without, however, limiting it. In these examples, the properties relating to glass strands coated with the sizing composition and to the composites incorporating said strands are measured as follows: - the loss on ignition, in percentage, of the sized glass strand is measured under the conditions of the ISO 1887 standard, - the flock is measured by simultaneously passing the strands unwound from 2 rovings on a tie, at a speed of 200 m / ma. The flock is defined by the quantity of fibrils, in mg, obtained after passing through a mass of thread of 3 kg. It is expressed in mg / kg of yarn. EXAMPLE 1 A sizing composition is prepared in the form of an aqueous solution comprising, as a percentage by weight of the solid materials: "sticky film-forming agents - polyvinyl acetate (1 ; molecular weight: 50,000 35.7 vinyl acetate copolymer- ethylene ^ 35.7 epoxy resin (3) 12.6 amino-epoxy resin (4) 3.7
" agents de couplage - gamma-méthacryloxypropyltriéthoxysilane (5) 2,3 " agents lubrifiants - huile minérale (6) 0,8 - silicone (7) 3,0 polyéthylène glycol (poids moléculaire : 1000) (8) 1,7"coupling agents - gamma-methacryloxypropyltriethoxysilane (5) 2.3" lubricating agents - mineral oil (6) 0.8 - silicone (7) 3.0 polyethylene glycol (molecular weight: 1000) (8) 1.7
" agent anti-statique : LiCl 4,5 " eau : quantité suffisante pour donner 100 ml de composition d'ensimage La préparation de la composition d'ensimage est réalisée de la manière suivante : On procède à l'hydrolyse des groupes méthoxy du silane (5) par ajout d'acide dans une solution aqueuse de ce silane maintenue sous agitation. On introduit ensuite les autres constituants, toujours sous agitation, et on ajuste le pH à une valeur de 4 ± 0,2, si nécessaire. La teneur pondérale en matières solides dans la composition d'ensimage est égale à 10,9 %. La composition d'ensimage est utilisée pour revêtir, de manière connue, des filaments de verre E d'environ 12 μm de diamètre étirés à partir de filets de verre s' écoulant des orifices d'une filière, les filaments étant ensuite rassemblés sous forme d'enroulements de fils de base de titre égal à 57 tex. L'enroulement est ensuite séché à 130°C pendant 12 heures. Les fils de base extraits de 6 enroulements sont rassemblés pour former un stratifil. Le fil ainsi obtenu présente une perte au feu égale à 1,5 %. La quantité de bourre est égale à 24 mg."anti-static agent: LiCl 4.5" water: sufficient quantity to give 100 ml of sizing composition The preparation of the sizing composition is carried out as follows: The methoxy groups of the silane (5) are hydrolyzed by adding acid to an aqueous solution of this silane which is kept stirring. The other constituents are then introduced, still with stirring, and the pH is adjusted to a value of 4 ± 0.2, if necessary. The weight content of solid matter in the sizing composition is equal to 10.9%. The sizing composition is used to coat, in a known manner, glass filaments E of approximately 12 μm in diameter drawn from glass filaments flowing from the orifices of a die, the filaments then being collected in the form of base wire windings with a title equal to 57 tex. The winding is then dried at 130 ° C for 12 hours. The basic threads extracted from 6 windings are brought together to form a roving. The wire thus obtained has a loss on ignition equal to 1.5%. The quantity of fill is equal to 24 mg.
EXEMPLE 2 On réalise dans les conditions de l'exemple 1 une composition d'ensimage constituée d'un mélange aqueux comprenant, en pourcentage pondéral des matières solides : " agents fihnogènes collants - polyacétate de vinyle (1) ; poids moléculaire : 50000 36,1 - copolymère acétate de vinyle-éthylène ^ 36,1 - résine époxy ^ 12,8EXAMPLE 2 A sizing composition is prepared under the conditions of Example 1, consisting of an aqueous mixture comprising, as a percentage by weight of the solid materials: "sticky film-forming agents - polyvinyl acetate (1) ; molecular weight: 50,000 36, 1 - vinyl acetate-ethylene copolymer ^ 36.1 - epoxy resin ^ 12.8
" agent de couplage - gamma-méthacryloxypropyltriéthoxysilane (5) 2,3"coupling agent - gamma-methacryloxypropyltriethoxysilane (5) 2,3
" agent lubrifiant - huile minérale) (6) 5,0 - silicone (7) 2,0 - monolaurate d'éthylène glycol (9) 3,0 - sel de polyéthylène imide polyamide (10) 0,3"lubricating agent - mineral oil) (6) 5.0 - silicone (7) 2.0 - ethylene glycol monolaurate (9) 3.0 - polyethylene imide polyamide salt (10) 0.3
" agent anti-statique : LiCl 2,4"anti-static agent: LiCl 2,4
" eau : quantité suffisante pour donner 100 ml de composition d'ensimage. La teneur pondérale en matières solides dans la composition d'ensimage est égale à 7,5 %. Le fil extrait d'un stratifil obtenu dans les conditions de l'exemple 1 présente une perte au feu égale à 1,55 %. La quantité de bourre est égale à 3 ,6 mg."water: sufficient quantity to give 100 ml of sizing composition. The weight content of solid matter in the sizing composition is equal to 7.5%. The yarn extracted from a roving obtained under the conditions of Example 1 has a loss on ignition equal to 1.55%. The amount of fill is equal to 3.6 mg.
EXEMPLE 3 On réalise dans les conditions de l'exemple 1 une composition d'ensimage constituée d'un mélange aqueux comprenant, en pourcentage pondéral des matières solides : " agents fihnogènes collants - polyacétate de vinyle (1) ; poids moléculaire : 50000 34,8 - copolymère acétate de vinyle-éthylène (2) 34,8 - résine époxy (3) 12,3 - résine amino-époxy (4) 3,6 " agent de couplage - gamma-méthacryloxypropyltriéthoxysilane (5) 2,2EXAMPLE 3 A sizing composition is prepared under the conditions of Example 1, consisting of an aqueous mixture comprising, as a percentage by weight of the solid materials: "sticky film-forming agents - polyvinyl acetate (1) ; molecular weight: 50,000 34, 8 - vinyl acetate-ethylene copolymer (2) 34.8 - epoxy resin (3) 12.3 - amino-epoxy resin (4) 3.6 "coupling agent - gamma-methacryloxypropyltriethoxysilane (5) 2.2
" agent lubrifiant - huile minérale (6) 4,7 - silicone (7) 1,9 - monolaurate d'éthylène glycol (9) 3,1 - sel de polyéthylène imide polyamide (10 0,3"lubricating agent - mineral oil (6) 4.7 - silicone (7) 1.9 - ethylene glycol monolaurate (9) 3.1 - polyethylene imide polyamide salt (10 0.3
" agent anti-statique : LiCl 2,3"anti-static agent: LiCl 2,3
" eau : quantité suffisante pour donner 100 ml de composition d'ensimage. La teneur pondérale en matières solides dans la composition d'ensimage est égale à 11,5 %. Le fil extrait d'un stratifil obtenu dans les conditions de l'exemple 1 présente une perte au feu égale à 1 ,70 %."water: an amount sufficient to give 100 ml of sizing composition. The weight content of solid matter in the sizing composition is equal to 11.5%. The yarn extracted from a roving obtained under the conditions of the example 1 has a loss on ignition equal to 1.70%.
La quantité de bourre est égale à 1,5 mg.The quantity of fill is equal to 1.5 mg.
EXEMPLE 4 (comparatif) On réalise dans les conditions de l'exemple 1 une composition d'ensimage constituée d'un mélange aqueux comprenant, en pourcentage pondéral des matières solides :EXAMPLE 4 (Comparative) Under the conditions of Example 1, a sizing composition consisting of an aqueous mixture comprising, in percentage by weight of the solid materials:
" agents fihnogènes collants - copolymère acétate de vinyle-N-méthylolacrylamide (11) 42,2 - copolymère acétate de vinyle-éthylène p) 45,5 - résine amino-époxy (4) 4,0"sticky fihnogenic agents - vinyl acetate-N-methylolacrylamide copolymer (11) 42.2 - vinyl acetate-ethylene copolymer p) 45.5 - amino-epoxy resin (4) 4.0
" agent de couplage - gamma-méthacryloxypropyltriéthoxysilane (5) 2,4"coupling agent - gamma-methacryloxypropyltriethoxysilane (5) 2,4
• agents lubrifiant - huile minérale (6) 0,9 - silisone ^ 3,2 - polyéthylèneglycol (8) ; poids moléculaire : 1000 1,8 " eau : quantité suffisante pour donner 100 ml de composition d'ensimage. La teneur pondérale en matières solides dans la composition d'ensimage est égale à 9,9 %. Le fil extrait d'un stratifil obtenu dans les conditions de l'exemple 1 présente une perte au feu égale à 1,89 %. La quantité de bourre est égale à 12,7 mg.• lubricating agents - mineral oil (6) 0.9 - silisone ^ 3.2 - polyethylene glycol (8) ; molecular weight: 1000 1.8 "water: sufficient quantity to give 100 ml of sizing composition. The weight content of solids in the sizing composition is equal to 9.9%. The yarn extracted from a rovet obtained under the conditions of Example 1 has a loss on ignition equal to 1.89% The quantity of flock is equal to 12.7 mg.
EXEMPLE S (comparatif) On réalise une composition d'ensimage dans les conditions de l'exemple 4 modifié en ce qu'elle contient en outre 0,45 % en poids de LiCl. La teneur pondérale en matières solides dans la composition d'ensimage est égale à 9,8 %. Le fil extrait d'un stratifil a une perte au feu égale à 1,52 % La quantité de bourre est égale à 7,6 mg. EXEMPLES 6 à 11 Le fil obtenu selon les exemples 1 à 5 est utilisé pour fabriquer des pièces composites par la technique de moulage par projection simultanée dans les conditions suivantes :EXAMPLE S (Comparative) A sizing composition is produced under the conditions of Example 4 modified in that it additionally contains 0.45% by weight of LiCl. The weight content of solid matter in the sizing composition is equal to 9.8%. The yarn extracted from a rovel has a loss on ignition equal to 1.52% The quantity of flock is equal to 7.6 mg. EXAMPLES 6 to 11 The wire obtained according to examples 1 to 5 is used to manufacture composite parts by the technique of molding by simultaneous projection under the following conditions:
" on introduit le fil de verre extrait du stratifil dans un pistolet (APPLICATOR) qui permet de le couper et de le projeter simultanément avec une résine polyester insaturée (Enydyne D05 4500 TY commercialisée par CRAY VALLEY) de réactivité moyenne et thixotropée."we introduce the glass wire extracted from the roving in a spray gun (APPLICATOR) which allows it to be cut and projected simultaneously with an unsaturated polyester resin (Enydyne D05 4500 TY marketed by CRAY VALLEY) of medium and thixotropic reactivity.
" Le moule dans lequel les fils coupés et la résine sont projetés est un moule en forme d'escalier comportant une paroi verticale de 1 m de haut, puis une marche de 0,20 m de profondeur et 0,2 m de hauteur et enfin une paroi horizontale de 1 m de long. La paroi horizontale comporte deux rainures de 2 cm de profondeur permettant d'évaluer la conformabilité du mélange fils coupés/résine. * Le mélange projeté sur le moule renferme environ 30% en poids de verre et a une épaisseur moyenne de l'ordre de 5 mm. On évalue les performances du mélange fils coupés/résine pour les paramètres suivants : - ébullage/temps du travail correspondant respectivement à l'aptitude des bulles d'air à être expulsées du mélange projeté sur le moule par passage d'un rouleau ébulleur, et l'aptitude des fils à être imprégnés par la résine, - tenue en paroi verticale, - conformabilité, évaluée au niveau des rainures de la paroi horizontale, - vitesse d'imprégnation des fils coupés par la résine. L'évaluation relative aux paramètres d' ébullage/temps du travail, de tenue en paroi verticale et de conformabilité est mesurée visuellement selon une échelle de valeurs suivantes : 1 = très mauvais ; 2 = mauvais ; 3 = assez bien ; 4 = bien ; 5 = très bien. L'évaluation de la vitesse d'imprégnation est définie visuellement selon l'échelle de valeurs suivantes : 1 = très lente, 2 = lente, 3 = moyenne, 4 = rapide et 5 = très rapide. Le tableau 1 ci-dessous rassemble l'évaluation des performances des fils selon l'invention (exemples 1 à 3) et comparatifs (5 à 7). Dans ce tableau, on indique également les performances pour un fil de verre commercialisé par la société Owens Corning sous la référence OC 1662 comme étant adapté au moulage par projection simultanée (Référence 1). Ce fil est pourvu d'un ensimage renfermant du chrome. TABLEAU 1"The mold in which the cut wires and the resin are projected is a stair-shaped mold with a vertical wall 1 m high, then a step 0.20 m deep and 0.2 m high and finally a horizontal wall 1 m long. horizontal wall has two grooves 2 cm deep to assess the conformability of the cut son / resin mixture. * The mixture projected onto the mold contains approximately 30% by weight of glass and has an average thickness of the order of 5 mm. The performance of the cut son / resin mixture is evaluated for the following parameters: - boiling / working time respectively corresponding to the ability of the air bubbles to be expelled from the mixture projected onto the mold by passing a boiling roller, and the ability of the wires to be impregnated with the resin, - held in a vertical wall, - conformability, evaluated at the level of the grooves in the horizontal wall, - speed of impregnation of the wires cut by the resin. The evaluation relating to the parameters of boiling / working time, resistance to vertical wall and conformability is measured visually according to a scale of following values: 1 = very bad; 2 = bad; 3 = good enough; 4 = good; 5 = very good. The evaluation of the impregnation speed is defined visually according to the following scale of values: 1 = very slow, 2 = slow, 3 = medium, 4 = fast and 5 = very fast. Table 1 below brings together the evaluation of the performance of the yarns according to the invention (examples 1 to 3) and comparative (5 to 7). In this table, the performance is also indicated for a glass yarn marketed by the company Owens Corning under the reference OC 1662 as being suitable for simultaneous projection molding (Reference 1). This wire is provided with a size containing chromium. TABLE 1
On observe à la lecture du tableau 1 que les exemples 6 à 8 selon l'invention permettent d'atteindre un excellent compromis au niveau des propriétés d'application : une tenue en paroi verticale particuUèrement élevée associée à une vitesse d'imprégnation qui peut être modulée en fonction de l'ensimage, de modérée (exemples 6 et 7) à lente (exemple 8). Les fils de verre de l'exemple 3 permettent notamment d'atteindre le même niveau de performances que les fils de verre adaptés à cette technique (Référence 1). Les fils de verre revêtus d'un ensimage ne comprenant pas le mélange des agents fihnogènes collants (exemples 9 et 10) ont une conformabilité insuffisante. A noter que les fils conformes à l'invention ont une production de bourre plus faible que les fils prévus pour l'application visée (Référence 1). Dans l'exemple 8, la production de bourre est considérablement réduite. EXEMPLES 12 ET 13 Les performances du fil selon l'exemple 3 sont évaluées pour l'application LFI comparativement au fil OC 900 (Référence 2) adapté à cette technique. Les paramètres sont : - le nombre de boucles présentes sur 500 mètres de fil dévidé à partir d'un enroulement, en général un stratifil, - l'intégrité du fil soumis aux conditions suivantes : le fil dévidé à partir d'un stratifil est introduit dans un coupeur WOLFANGEL 500 qui le coupe et le projette sensiblement à l'horizontale sur une paroi verticale (vitesse de coupe : 1200 mmin ; longueur : 12 mm). L'intégrité du fil coupé est mesurée visuellement sur une échelle de valeurs allant de 1 (mauvais, aspect cotonneux) à 5 (très bonne, pas d'éclatement du fil) la vitesse d'imprégnation du fil coupé par la résine, mesurée visuellement sur une échelle allant de 1 (vitesse très lente) à 5 (très rapide). Exemple 12 Exemple 13 Fil Exemple 3 Référence 2 Nombre de boucles 30 43 Intégrité 3,5 3,5 Vitesse d'imprégnation 1 1 Le fil selon l'invention présente un nombre de boucles réduit par rapport au filéférence pour une intégrité et une vitesse d'imprégnation identiques.On reading Table 1, it can be seen that Examples 6 to 8 according to the invention make it possible to achieve an excellent compromise in terms of application properties: a particularly high vertical wall resistance associated with an impregnation speed which can be modulated according to the size, from moderate (examples 6 and 7) to slow (example 8). The glass strands of Example 3 make it possible in particular to achieve the same level of performance as the glass strands adapted to this technique (Reference 1). The glass strands coated with a size not comprising the mixture of sticky film-forming agents (examples 9 and 10) have insufficient conformability. Note that the yarns according to the invention have a lower wadding production than the yarns provided for the intended application (Reference 1). In Example 8, the fluff production is considerably reduced. EXAMPLES 12 AND 13 The performance of the wire according to Example 3 is evaluated for the LFI application compared to the OC 900 wire (Reference 2) suitable for this technique. The parameters are: - the number of loops present on 500 meters of wire unwound from a winding, generally a roving, - the integrity of the wire subject to the following conditions: the wire unwound from a roving is introduced in a WOLFANGEL 500 cutter which cuts and projects it substantially horizontally on a vertical wall (cutting speed: 1200 mmin; length: 12 mm). The integrity of the cut wire is visually measured on a scale of values ranging from 1 (poor, cottony appearance) to 5 (very good, no breakage of the wire) the impregnation speed of the wire cut by the resin, measured visually on a scale ranging from 1 (very slow speed) to 5 (very fast). Example 12 Example 13 Thread Example 3 Reference 2 Number of loops 30 43 Integrity 3.5 3.5 Impregnation speed 1 1 The thread according to the invention has a reduced number of loops compared to the spooling for integrity and speed d 'identical impregnation.
(1) Commercialisé sous la référence « Vinamuf® 8852 » par VINAMUL ; teneur en matières solides : 55%(1) Marketed under the reference “Vinamuf ® 8852” by VINAMUL; solids content: 55%
(2) Commercialisé sous la référence « Air Flex® EP740 » par AIR PRODUCTS ; teneur en matières solides : 55% (3) Commercialisé sous la référence «Neoxil® 8294 » par DSM ; teneur en matières solides : 55%(2) Marketed under the reference "Air Flex ® EP740" by AIR PRODUCTS; solid content: 55% (3) Marketed under the reference "Neoxil ® 8294" by DSM; solids content: 55%
(4) Commercialisé sous la référence « Neoxil® PS5164 » par DSM ; teneur en matières solides : 35%(4) Marketed under the reference "Neoxil ® PS5164" by DSM; solids content: 35%
(5) Commercialisé sous la référence « Silquest® A- 174 » par GESM ; teneur en matières solides : 70%(5) Marketed under the reference "Silquest ® A-174" by GESM; solids content: 70%
(6) Commercialisé sous la référence « Lubronyl® GF » par RHONE POULENC ; teneur en matières solides : 100% (7) Commercialisé sous la référence « Silicone® 2418 » par DOW CORNING ; teneur en matières solides : 50%(6) Marketed under the reference "Lubronyl ® GF" by RHONE POULENC; solids content: 100% (7) Marketed under the reference “Silicone ® 2418” by DOW CORNING; solids content: 50%
(8) Commercialisé sous la référence « Prioowax® 1000 » par CESALPINA CHEM ; teneur en matières solides : 100 %(8) Marketed under the reference "Prioowax ® 1000" by CESALPINA CHEM; solids content: 100%
(9) Commercialisé sous la référence « Ensital® 4L » par COGNIS ; teneur en matières solides : 100% (10) Commercialisé sous la référence « Emer ® 6760 » par COGNIS ; teneur en matières solides : 17%(9) Marketed under the reference “Ensital ® 4L” by COGNIS; solid content: 100% (10) Marketed under the reference "Emer ® 6760" by COGNIS; solids content: 17%
(11) Commercialisé sous la référence « Vinamul® 8828 » par VINAMUL ; teneur en matières solides : 51% (11) Marketed under the reference “Vinamul ® 8828” by VINAMUL; solids content: 51%

Claims

REVENDICATIONS
1. Fil de verre revêtu d'une composition d'ensimage aqueuse, caractérisé en ce que ladite composition comprend en tant qu'agents fihnogènes collants au moins un polyacétate de vinyle, au moins un copolymère d'acétate de vinyle et d'un autre monomère insaturé et au moins un époxy. 1. Glass wire coated with an aqueous sizing composition, characterized in that said composition comprises, as sticky film-forming agents, at least one polyvinyl acetate, at least one copolymer of vinyl acetate and another unsaturated monomer and at least one epoxy.
2. Fil de verre selon la revendication 1, caractérisé en ce que le polyacétate de vinyle a un poids moléculaire inférieur à 80000 g/mol, de préférence inférieur à 70 000 g/mol et mieux encore entre 40000 et 65 000 g/mol. 2. Glass strand according to claim 1, characterized in that the polyvinyl acetate has a molecular weight of less than 80,000 g / mol, preferably less than 70,000 g / mol and better still between 40,000 and 65,000 g / mol.
3. Fil de verre selon la revendication 1 ou 2, caractérisé en ce que le copolymère est un copolymère d'acétate de vinyle et d'un monomère oléfinique. 3. Glass strand according to claim 1 or 2, characterized in that the copolymer is a copolymer of vinyl acetate and of an olefinic monomer.
4. Fil de verre selon la revendication 3, caractérisé en ce que le monomère oléfinique est l'éthylène. 4. Glass strand according to claim 3, characterized in that the olefinic monomer is ethylene.
5. Fil de verre selon l'une des revendications 1 à 4, caractérisé en ce que le rapport pondéral du polyacétate de vinyle au copolymère varie de 30:70 à 70:30, et de préférence de 40:60 à 60:40. 5. Glass strand according to one of claims 1 to 4, characterized in that the weight ratio of polyvinyl acetate to the copolymer varies from 30:70 to 70:30, and preferably from 40:60 to 60:40.
6. Fil de verre selon l'une des revendications 1 à 5, caractérisé en ce que l'époxy est choisi parmi les résines présentant un poids moléculaire supérieur à 5 000 g/mol, de préférence 20000 g/mol. 6. Glass strand according to one of claims 1 to 5, characterized in that the epoxy is chosen from resins having a molecular weight greater than 5,000 g / mol, preferably 20,000 g / mol.
7. Fil de verre selon la revendication 6, caractérisé en ce que l'époxy présente un indice d'époxyde supérieur à 800 g équivalent, de préférence compris entre 1 200 et7. Glass strand according to claim 6, characterized in that the epoxy has an epoxy index greater than 800 g equivalent, preferably between 1,200 and
2 000 g/équivalent. 2,000 g / equivalent.
8. Fil de verre selon l'une des revendication 1 à 7, caractérisé en ce que la composition comprend en outre un agent lubrifiant. 8. Glass strand according to one of claims 1 to 7, characterized in that the composition also comprises a lubricating agent.
9. Fil de verre selon la revendication 8, caractérisé en ce que l'agent lubrifiant est choisi parmi les composés cationiques du type polyalkylène imide et les composés non ioniques du type esters d'acides gras et de poly(alkylèneglycol) poly(oxyalkylène) ou de type amides d'acide gras et de poly(oxyalkylène). 9. Glass strand according to claim 8, characterized in that the lubricating agent is chosen from cationic compounds of the polyalkylene imide type and non-ionic compounds of the ester type of fatty acids and of poly (alkylene glycol) poly (oxyalkylene) or of the fatty acid amide and poly (oxyalkylene) type.
10. Fil de verre selon l'une des revendications 1 à 9, caractérisé en ce que la composition comprend en outre un agent de couplage choisi parmi les silanes, le siloxanes, les titanates et les zirconates. 10. Glass strand according to one of claims 1 to 9, characterized in that the composition also comprises a coupling agent chosen from silanes, siloxanes, titanates and zirconates.
11. Fil de verre selon l'une des revendications 1 à 10, caractérisé en ce qu'il présente une perte au feu inférieure à 2,2 %, de préférence supérieure à 1,1 % et mieux encore comprise entre 1,4 et 1,6 %. 11. Glass strand according to one of claims 1 to 10, characterized in that it has a loss on ignition of less than 2.2%, preferably greater than 1.1% and better still between 1.4 and 1.6%.
12. Fil de verre selon l'une des revendications 1 à 11, caractérisé en ce qu'il est constitué de filaments ayant un diamètre variant de 9 à 17 μm. 12. Glass strand according to one of claims 1 to 11, characterized in that it consists of filaments having a diameter varying from 9 to 17 μm.
13. Fil de verre selon l'une des revendications 1 à 12, caractérisé en ce qu'il présente un titre compris entre 30 et 160 tex, de préférence 40 à 60 tex. 13. Glass strand according to one of claims 1 to 12, characterized in that it has a titer between 30 and 160 tex, preferably 40 to 60 tex.
14. Composition d'ensimage destinée à revêtir des fils de verre selon l'une des revendications 1 à 13, caractérisée en ce qu'elle comprend un mélange aqueux d'au moins un polyacétate de vinyle, d'au moins un copolymère d'acétate de vinyle et d'un autre monomère insaturé et d'au moins un époxy. 14. Sizing composition intended to coat glass strands according to one of claims 1 to 13, characterized in that it comprises an aqueous mixture of at least one polyvinyl acetate, of at least one copolymer of vinyl acetate and another unsaturated monomer and at least one epoxy.
15. Composition selon la revendication 14, caractérisée en ce qu'elle comprend les constituants ci-après, dans les teneurs pondérales suivantes exprimées en pourcentages de matières solides : - 20 à 50 % d'au moins un polyacétate de vinyle, de préférence 30 à 40 % - 20 à 45 % d'au moins un copolymère d'acétate de vinyle et d'au moins un autre monomère insaturé, avantageusement un monomère oléfinique tel que l'éthylène, de préférence 30 à 40 % - 10 à 20 % d'au moins un époxy, de préférence 12 à 16 % - 1 à 20 % d'au moins un agent lubrifiant, - 0 à 5 % d'au moins un agent de couplage, de préférence supérieur à 2 % - 0 à 5 % d'au moins un agent anti-statique. 15. Composition according to Claim 14, characterized in that it comprises the following constituents, in the following weight contents expressed as percentages of solid matter: - 20 to 50% of at least one polyvinyl acetate, preferably 30 at 40% - 20 to 45% of at least one copolymer of vinyl acetate and at least one other unsaturated monomer, advantageously an olefinic monomer such as ethylene, preferably 30 to 40% - 10 to 20% at least one epoxy, preferably 12 to 16% - 1 to 20% of at least one lubricating agent, - 0 to 5% of at least one coupling agent, preferably greater than 2% - 0 to 5 % of at least one anti-static agent.
16. Composition selon la revendication 14 ou 15, caractérisée en ce qu'elle comprend 5 à 15 % en poids de matières solides, de préférence 7 à 12 %. 16. Composition according to claim 14 or 15, characterized in that it comprises 5 to 15% by weight of solid matter, preferably 7 to 12%.
17. Composite comprenant au moins une matière polymère thermodurcissable et des fils de verre de renforcement, caractérisé en ce que tout ou partie des fils est constitué de fils selon l'une des revendications 1 à 13. 17. Composite comprising at least one thermosetting polymeric material and reinforcing glass strands, characterized in that all or part of the strands consists of strands according to one of claims 1 to 13.
18. Composite selon la revendication 17, caractérisé en ce que la matière thermodurcissable est un polyester, un vinylester, un acrylique, un polyuréthane, une résine phénolique ou une résine époxy. 18. Composite according to claim 17, characterized in that the thermosetting material is a polyester, a vinylester, an acrylic, a polyurethane, a phenolic resin or an epoxy resin.
19. Composite selon la revendication 17 ou 18, caractérisé en ce qu'il comprend 20 à 45 % en poids de verre. 19. Composite according to claim 17 or 18, characterized in that it comprises 20 to 45% by weight of glass.
20. Utilisation des fils de verre selon l'une des revendications 1 à 13 pour la réalisation de pièces par la technique de moulage à moule ouvert, notamment par projection simultanée desdits fils et de résine. 20. Use of the glass strands according to one of claims 1 to 13 for the production of parts by the open mold molding technique, in particular by simultaneous projection of said strands and of resin.
21. Utihsation des fils de verre selon l'une des revendications 1 à 13 pour la réalisation de pièces par la technique de moulage à moule fermé, notamment par LFI. 21. Use of the glass strands according to one of claims 1 to 13 for the production of parts by the closed mold molding technique, in particular by LFI.
EP04805872A 2003-12-17 2004-12-01 Sized glass fibres which are intended to reinforce polymer materials, such as by means of moulding Withdrawn EP1725506A2 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR0314800A FR2864072B1 (en) 2003-12-17 2003-12-17 ENSIMES GLASS YARNS FOR REINFORCING POLYMERIC MATERIALS, IN PARTICULAR BY MOLDING
PCT/FR2004/050634 WO2005058770A2 (en) 2003-12-17 2004-12-01 Sized glass fibres which are intended to reinforce polymer materials, such as by means of moulding

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EP1725506A2 true EP1725506A2 (en) 2006-11-29

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DE102006062733B4 (en) * 2006-07-27 2010-08-05 S.D.R. Biotec Verfahrenstechnik Gmbh R- E and ECR glass fibers with aqueous sizing and their use
DE102007036774B4 (en) * 2007-08-03 2012-08-16 S.D.R. Biotec Verwaltungs GmbH Thermally stable glass fibers, process for their trimming and use
CN104947410B (en) * 2015-06-03 2017-05-10 扬州市邗江扬子汽车内饰件有限公司 Glass fibre reinforcement and surface modification method

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CA937830A (en) * 1970-10-15 1973-12-04 Owens-Corning Fiberglas Corporation Moldable glass fiber-reinforced resin composite
US3933711A (en) 1972-10-31 1976-01-20 Ppg Industries, Inc. Forming size of aqueous polyvinylacetate
US3968068A (en) * 1974-06-07 1976-07-06 Owens-Corning Fiberglas Corporation Glass sizing
ZA766854B (en) * 1975-12-31 1977-10-26 Owens Corning Fiberglass Corp Sizing for glass fibers
FR2755127B1 (en) * 1996-10-29 1998-11-27 Vetrotex France Sa SIZED GLASS WIRES FOR THE REINFORCEMENT OF POLYMERIC MATERIALS
JPH111348A (en) * 1997-06-11 1999-01-06 Nippon Electric Glass Co Ltd Glass fiber bundling agent and glass fiber treated therewith
FR2819801B1 (en) 2001-01-24 2004-10-01 Saint Gobain Vetrotex SIZED GLASS WIRES, SIZING COMPOSITION AND COMPOSITES COMPRISING SAID WIRES

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FR2864072B1 (en) 2006-01-27
WO2005058770A3 (en) 2006-03-23
FR2864072A1 (en) 2005-06-24
WO2005058770A2 (en) 2005-06-30

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