WO2009112515A1

WO2009112515A1 - Fibre coated with a sizing composition

Info

Publication number: WO2009112515A1
Application number: PCT/EP2009/052847
Authority: WO
Inventors: Cristina Piccinelli; Johan Franz Gradus Antonius Jansen; Federica Galli; Martijn Marcus Gabriël ANTONISSE; Debora Genini; Ronald Leonardus Verleg
Original assignee: DSM IP Assets BV
Current assignee: DSM IP Assets BV
Priority date: 2008-03-11
Filing date: 2009-03-11
Publication date: 2009-09-17
Anticipated expiration: 2010-09-11

Abstract

The present invention relates to a glass fibre coated with a sizing composition, wherein the sizing composition comprises 5-70 wt.% of a curable vinyl ester resin being the reaction product of component (a) being at least one component containing at least one glycidyl ether and component (b) being methacrylic acid and/or acrylic acid, 10-97 wt.% water and an ethylene oxide-propylene oxide copolymer as non-ionic emulsifier; the wt.% is relative to the total sizing composition.

Description

FIBRE COATED WITH A SIZING COMPOSITION

The present invention relates to the field of glass fibres for reinforcing, in particular for the production of composites. The present invention relates to a glass fibre coated with a sizing composition comprising a resin, water and an emulsifier.

It is known to produce glass fibre packages by supplying molten glass to a bushing, drawing glass fibres from the bushing, and at least partially coating the fibres with a sizing composition, usually aqueous based, by passing the fibres through a sizer. The sized fibres are usually gathered into a strand and are wound on a collet to produce a glass fibre package. The package may then be distributed on moving conveyors, in order to form mats or veils, or else chopped. Where appropriate, the fibres may, before or after being collected, be subjected to a heat treatment in a heated enclosure, such as an oven, to evaporate water from the aqueous based sizing composition and/or to cure them. The deposition of sizing composition is very important as it makes it possible, on the one hand, to obtain the strands and, on the other hand, to use these strands effectively in making composites. The size has the following usual functions: it protects the strand from abrasion, thus preventing them from breaking during their manufacture and possibly during their use; additionally, it allows the strands thus formed to be combined with organic and/or inorganic materials to be reinforced, especially making it easier for the strands to be wetted by and impregnated with these materials. In general, the size thus favours adhesion between the glass and the material to be reinforced, thereby making it possible to obtain composites having improved mechanical properties. For favouring such adhesion, the sizing composition must provide the fibres with an outer film which is compatible with the resin they will reinforce. Commonly applied sizing compositions are low viscosity aqueous sizing compositions comprising as sizing agent at least a compound having one or more epoxy functional groups such as bisphenol A diglycidyl ether or a novolac epoxy. See for example US-B-5779758, WO-A-2004/009507, US-B-7276282, US-A-2005/0214524. A disadvantage of the use of such sizing compositions is that the adhesion between in particular an unsaturated polyester and/or vinyl ester resin matrix and glass fibres coated with such sizing compositions may be insufficient. In view of this, the industry continues to want improved fibre reinforcement for in particular an unsaturated polyester resin or vinyl ester resin matrix. The object of the present invention is to increase the adhesion between in particular an unsaturated polyester or vinyl ester resin matrix and sized glass fibres.

It has now surprisingly been found that this could be achieved in that the glass fibres are coated with a sizing composition comprising 5-70 wt.% of a curable vinyl ester resin being the reaction product of component (a) being at least one component containing at least one glycidyl ether and component (b) being methacrylic acid and/or acrylic acid, 10-97 wt.% water and an ethylene oxide-propylene oxide copolymer as non-ionic emulsifier, wherein the wt.% is relative to the total sizing composition.

It has surprisingly been found that the adhesive strength between in particular an unsaturated polyester resin or vinyl ester resin matrix and sized glass fibres according to the invention can be increased compared to glass fibres sized with an aqueous emulsion containing, as sizing agent, a compound having one or more epoxy functional groups such as bisphenol A diglycidyl ether or a novolac epoxy. This is the more surprising since no coherent film is formed on a glass plate when subjecting a glass plate containing a film of the aqueous emulsion according to the invention to a heat treatment at 130⁰C for 1 hr, whilst employing an aqueous emulsion containing, as sizing agent, a compound having one or more epoxy functional groups such as bisphenol A diglycidyl, coherent films on the glass plate were obtained after drying for 1 hr at 130⁰C.

Furthermore, the increase in adhesive strength between the resin matrix and sized glass fibres does not result in a decrease of the overall performance of the glass fibre reinforced resin matrix as for example expressed in flexural strength and/or inter laminar shear strength. Even more, as demonstrated in the experimental part, it has surprisingly been found that the overall performance of the glass fibre reinforced resin matrix is improved.

Furthermore, we have found that the level of adhesion when employed at a fixed temperature can be further tuned via the addition of a curing catalyst, which can be beneficial in many applications.

The vinyl ester resin present as sizing agent in the sizing composition is the reaction product obtained by the reaction of component (a) and component (b). Component (a) is a component containing at least one, preferably at least two, glycidyl ether or is a mixture of at least two components containing at least one, preferably at least two, glycidyl ethers. Component (b) is methacrylic acid, acrylic acid or a mixture thereof. These reactants are preferably mixed in such amount to provide essentially a stoichiometric equivalency of carboxyl function with the oxirane groups present. Preferably the amount of (meth)acrylic acid components is from 0.8 up to and including 1.15 equivalents of (meth)acrylic acid components for each equivalent of the glycidyl ether component and more preferably from 0.9 up to and including

1.1 equivalents of (meth)acrylic acid components. The epoxy equivalent weight of the so obtained vinyl ester resin is preferably higher than 2000, more preferably higher than 5000.

The vinyl ester resin in the sizing composition preferably has a molecular weight Mw of from 400 up to and including 10000.

Any of the known components containing at least one glycidyl ether can be used in the preparation of the vinyl ester resin. Components containing at least two glycidyl ethers are preferred. Preferred components containing at least two glycidyl ether are bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, novolac glycidyl ethers or a mixture of at least two of these components. More preferred components are bisphenol A diglycidyl ether, preferably having a molecular weight Mw of from 360 up to and including 3000; novolac glycidyl ethers, preferably having a molecular weight Mw of from 1000 up to and including 10000; or a mixture thereof. The acid epoxide reaction is preferably catalyzed with known catalysts for the reaction of carboxyl groups with glycidyl ether groups. Such catalysts include tertiary amines and chromium salts. The esterification reaction is preferably effected at a temperature of between 50 and 150 ⁰C.

The amount of vinyl ester resin in the sizing composition is at least 5 wt. % and at most 70 wt.%. Preferably, the amount of vinyl ester resin in the sizing composition is at least 6 wt.% and more preferably at least 7 wt.%. Preferably, the amount of vinyl ester resin in the sizing composition is at most 50 wt.%, more preferably at most 40 wt.%.

The sizing composition comprises water, preferably deionized water. The amount of water in the sizing composition is at least 10 and at most 97 wt.%. Preferably, the amount of water in the sizing composition is at least 20 wt.%, more preferably at least 30 wt.%. Preferably, the amount of water in the sizing composition is at most 65 wt.%, more preferably at most 96 wt.% and even more preferably at most 95 wt.%.

The sizing composition comprises an ethylene oxide-propylene oxide copolymer non-ionic emulsifier. The presence of an ethylene oxide-propylene oxide - A -

copolymer non-ionic emulsifier results in an increase of the stability of the sizing composition.

The sizing composition comprises ethylene oxide-propylene oxide copolymer as non-ionic emulsifier. The ethylene oxide-propylene oxide copolymer non- ionic emulsifier in the sizing composition preferably has a molecular weight Mw of from 5000 up to and including 50000.

In a preferred embodiment, the ethylene oxide-propylene oxide copolymer non-ionic emulsifier in the sizing composition has a molar ratio of ethylene oxide versus propylene oxide of from 1 :0.75 to 1 :5, preferably from 1 :1 to 1 :4 and more preferably 1 :1.1 to 1 :3. Such molar ratios results in even more stable emulsions.

Preferably, the amount of ethylene oxide-propylene oxide copolymer in the sizing composition, relative to the total amount of vinyl ester resin in the sizing composition, is at least 0.1 wt.%, more preferably at least 0.5 wt.%. Preferably, the amount of ethylene oxide-propylene oxide copolymer in the sizing composition is at most 2.5 wt.%.

The sizing composition may further comprise at least one cationic emulsifier and/or at least one anionic emulsifier. Non-limiting examples of cationic emulsifiers are alkoxylated fatty amines, fatty quaternary ammonium salts, fatty amines. Non-limiting examples of anionic emulsifiers are carboxylic acids, polyalkyl carboxy derivatives, alkylbenzene sulfonates, sulphate derivatives, sulphosuccinates, phosphate esters.

The particle size distribution of the particles in the sizing composition is advantageously from 100 up to and including 1000 nm. More preferably, the particle size distribution of the particles in the sizing composition is at least 200 nm. More preferably, the particle size of the particles in the sizing composition is at most 2000 nm, even more preferably at most 500 nm.

The sizing composition preferably further comprises a non-reactive organic solvent. Such non-reactive solvents include glycol ethers, alcohols such as for example methoxy propanol, and ketones. The amount of non-reactive solvent in the sizing composition (relative to the total sizing composition) is preferably lower than

7.5 wt.% and more preferably lower than 2.5. The amount of non-reactive solvent in the sizing composition (relative to the total sizing composition) is preferably higher than 0.01 wt.% and more preferably higher than 0.1.

The sizing composition may further comprise a reactive solvent. Examples of suitable reactive diluents are styrene, vinyl toluene, α-methyl styrene, tert butyl styrene, methyl methacrylate (MMA), hydroxyethyl methacrylate (HEMA), hydroxypropyl methacrylate (HPMA), vinyl ethers, vinyl esters, butanediol dimethacrylate (BDDMA), triethylene glycol dimethacrylate (TEGDMA), trimethylolpropane trimethacryate (TMPTMA), phenoxyethyl methacrylate (PEMA), N-vinylpyrrolidone and N-vinylcaprolactam, dibutylterephtalate. Preferably, the reactive diluent is a methacrylate and/or styrene. The amount of reactive solvent in the sizing composition (relative to the total sizing composition) is preferably lower than 20% by weight and more preferably lower than 5% by weight.

The sizing composition preferably further comprises a vinyl polymerisation inhibitor, preferably chosen from the group of phenolic compounds, catechols and/or phenothiazines.

The amount of inhibitor as used in the context of the present invention, may, however, vary within rather wide ranges. Preferably, the amount of phenolic inhibitor is from about 0,001 to 35 mmol per kg of solid vinyl ester resin, and more preferably it amounts to more than 0,01 , most preferably more than 0,1 mmol per kg of solid vinyl ester resin. The skilled man quite easily can assess, in dependence of the type of inhibitor selected, which amount thereof leads to good results according to the invention.

Suitable examples of inhibitors that can be used in the resin compositions according to the invention are, for instance, 2-methoxyphenol, 4-methoxyphenol, 2,6-di-t-butyl-4-methylphenol, 2,6-di-t-butylphenol, 2,4,6-trimethyl-phenol, 2,4,6-tris-dimethylaminomethyl phenol, 4,4'-thio-bis(3-methyl-6-t-butylphenol), 4,4'-isopropylidene diphenol, 2,4-di-t-butylphenol, 6,6'-di-t-butyl-2,2'-methylene di-p-cresol, hydroquinone, 2-methylhydroquinone, 2-t-butylhydroquinone, 2,5-di-t-butylhydroquinone,

2,6-di-t-butylhydroquinone, 2,6-dimethylhydroquinone , 2,3,5-trimethylhydroquinone, catechol, 4-t-butylcatechol, 4,6-di-t-butylcatechol, benzoquinone, 2,3,5,6-tetrachloro-1 ,4-benzoquinone, methylbenzoquinone, 2,6-dimethylbenzoquinone, napthoquinone, 1-oxyl-2,2,6,6-tetramethylpiperidine, 1-oxyl-2,2,6,6-tetramethylpiperidine-4-ol (a compound also referred to as TEMPOL), 1-oxyl-2,2,6,6-tetramethylpiperidine-4-one (a compound also referred to as TEMPON), 1-oxyl-2,2,6,6-tetramethyl-4-carboxyl-piperidine (a compound also referred to as 4-carboxy-TEMPO), galvinoxyl, 1-oxyl-2,2,5,5-tetramethylpyrrolidine, 1-oxyl-2,2,5,5-tetramethyl-3-carboxylpyrrolidine (also called 3-carboxy-PROXYL), aluminium-N-nitrosophenyl hydroxylamine, diethylhydroxylamine, phenothiazine and/or derivatives or combinations of any of these compounds.

The vinyl ester resin contributes, after curing, appreciably to the structure of the cured size. The vinyl ester resin is curable by free radical reaction usually at elevated temperatures between 50 and 250 ⁰C

According to another embodiment of the invention, the sizing composition further comprises a catalyst which increases the rate of the curing reaction. Examples of suitable catalysts are tertiary amines; derivatives thereof; metal halides, such as for example AICI₃; organometallic complexes such as Cu-ethylenediamine; or peroxides. The catalyst content in the sizing composition may be up to 2% by weight. Preferred curing catalysts are redox initiators or thermal initiators. Peroxides are preferably used as redox initiator or thermal initiator.

Such peroxides include organic and inorganic peroxides, whether solid or liquid; also hydrogen peroxide may be applied. Examples of suitable peroxides are, for instance, peroxy carbonates (of the formula -OC(O)O-), peroxyesters (of the formula -C(O)OO-), diacylperoxides (of the formula -C(O)OOC(O)-), dialkylperoxides (of the formula -00-), et.Cτ The peroxides can also be oligomeric or polymeric in nature. An extensive series of examples of suitable peroxides can be found, for instance, in US 2002/0091214-A1 , paragraph [0018]. The skilled man can easily obtain information about the peroxides and the precautions to be taken in handling the peroxides in the instructions as given by the peroxide producers.

Preferably, the peroxide is chosen from the group of organic peroxides. Examples of suitable organic peroxides are: tertiary alkyl hydroperoxides (such as, for instance, t-butyl hydroperoxide), other hydroperoxides (such as, for instance, cumene hydroperoxide), the special class of hydroperoxides formed by the group of ketone peroxides (perketones, being an addition product of hydrogen peroxide and a ketone, such as, for instance, methyl ethyl ketone peroxide and acetylacetone peroxide), peroxyesters or peracids (such as, for instance, t-butyl peresters, benzoyl peroxide, peracetates and perbenzoates, lauryl peroxide, including (di)peroxyesters), perethers (such as, for instance, peroxy diethyl ether). Often the organic peroxides used as curing agent are tertiary peresters-or tertiary hydroperoxides, i.e. peroxy compounds having tertiary carbon atoms directly united to an -OO-acyl or -OOH group. Clearly also mixtures of these peroxides with other peroxides may be used in the context of the present invention. The peroxides may also be mixed peroxides, i.e. peroxides containing any two of different peroxygen-bearing moieties in one molecule). The sizing composition preferably further comprises a coupling agent that further improves the adhesion between the size and the fibre. Non-limiting examples of suitable coupling agents are silanes; siloxanes; titanates; zirconates and mixtures of these compounds. Examples of silane coupling agents which may be used in the present sizing compositions may be characterized by the functional groups amino, epoxy, vinyl, methacryloxy, azido, ureido, and isocyanato. Suitable silane coupling agents for use in the sizing composition include, but are not limited to, ϋaminopropyltriethoxysilane (A-1100), n-trimethoxy-silyl-propyl-ethylene-diamine (A-1120), Y-methacryloxypropyltrimethoxysilane (A-174), γ-glycidoxypropyltrimethoxysilane (A-187), methyl-trichlorosilane (A-154), methyl-trimethoxysilane (A-163), γ-mercaptopropyl-trimethoxy-silane (A-189), bis-(3-[triethoxysilyl]propyl)tetrasulfane (A-1289), γ-chloropropyl-trimethoxy-silane (A-143), vinyl-triethoxy-silane (A-151 ), vinyl-tris-(2-methoxyethoxy)silane (A-172), vinylmethyldimethoxysilane (A-2171 ), vinyl-triacetoxy silane (A-188), octyltriethoxysilane (A-137), methyltriethoxysilane (A-162), and methyltrimethoxysilane (A-1630).

The sizing composition may also optionally include a pH adjusting agent, such as for example an organic acid, to adjust pH level of the composition. Preferably, the sizing composition has a pH of from 3.5 to about 6 with the addition of organic acid.

Preferably, the amount of coupling agent in the sizing composition, relative to the total amount of the sizing composition, is at least 0.1 wt.%, more preferably at least 0.5 wt.%. Preferably, the amount of coupling agent in the sizing composition, relative to the total amount of the sizing composition, is at most 15 wt.%. In addition to the aforementioned components, the sizing composition may include one or more additives. These additives give the size particular properties. Non-limiting examples of additives are lubricants, such as polyethyleneiminepolyamide, polyamides of fatty acid derivatives (Neoxil LC 88710, available at DSM), amine salts of fatty acid, alkylimidazoline derivatives, polyalkylenglycol ester, polyalkylene glycol and antistatic additives such as for example quaternary ammonium derivatives (Neoxil AO 5620, available at DSM) and inorganic salts, such as lithium chloride.

The solids content of the sizing composition is generally at least 1 % by weight of the total sizing composition, preferably at least 5%. The solids content of the sizing composition is generally at most 50%, preferably at most 15% by weight of the composition. The sizing composition of the present invention may be prepared by any suitable method well know to those of ordinary skill in the art. Preferably, each component is diluted in deionized water in a separate tank and well mixed before being combined with the other components in main mixing tank.

Non-limited examples of glass fibres include those prepared from fiberizable glass compositions such as E-glass, A-glass, C-glass, S-glass, ECR-glass (corrosion resistant glass), and fluorine and/or boron-free derivatives thereof. In particular, the glass fibres are based on E-glass.

The glass fibre according to the invention are produced using a process according to the state of the art such as for example described in K. Loewenstein, The Manufacturing Technology of Continuous Glass Fibres, third edition 1993, pages 30-44, 47-10, and 115-165, 219-222. In order to coat the aqueous emulsion of the surface of the fibre, various methods can be used such as spray coating or dip coating.

The sized glass fibres according to the invention may be used in a matrix or binder of a thermosetting synthetic resin, such as for example an epoxy resin, unsaturated polyester resin, a vinyl ester resin, phenolic resin, or a thermoplastic polymers, such as for example a polyamide, a polyolefin, a polycarbonate or a polyester. In a particular embodiment, the sized fibres are used in a matrix of a thermosetting synthetic resin, preferably in a matrix of an unsaturated polyester resin and/or a vinyl ester resin, more preferably in a matrix of vinyl ester resin. Vinyl ester resin matrix in which the sized glass fibres are preferably used are characterised in having unsaturated sites only in the terminal position, introduced by reaction of epoxy resins (e.g. diglycidyl ether of bisphenol-A, epoxies of the phenol-novolac type, or epoxies based on tetrabromobisphenol-A) with (meth)acrylic acid. Instead of (meth)acrylic acid also (meth)acrylamide may be used. As used herein, the vinyl ester resin of the matrix is a (meth)acrylate functional resin.

The present invention therefore further relates to in particular a composition comprising an unsaturated polyester resin or a vinyl ester resin (a (meth)acrylate functional resin as defined above), sized glass fibres according to the invention and a curing initiator, such as a photoinitiator, a thermal initiator or a redox initiator. The present invention further relates to cured objects obtained from such a composition.

The present invention further relates to a sizing composition comprising 5-70 wt.% of a vinyl ester resin being a reaction product of (meth) acrylic acid and at least one glycidyl ethers, 10-97 wt.% water and an ethylene oxide- propylene oxide copolymer as non-ionic emulsifier, with the proviso that the sizing composition does not comprise a photo-initiator; the wt.% is relative to the total sizing composition.

Experimental part

The resins used for curing and the emulsions are commercially available products and in addition thereto also two emulsions -hereinafter referred to as Emulsion A and Emulsion B- was specifically prepared on behalf of the inventors for being used in the tests.

Emulsion A: Synthesis resin A and emulsification

To a mixture of 115g Epon 828 (bisphenol A diglycidyl ether; commercially available from Huntsman), 16Og Araldite EPN 1180 (novolac glycidyl ether; commercially available from Huntsman), 0.16g hydroquinone and 0.35g chromiun trichloride solution (10% in methyl alcohol) was slowly added at 70 ⁰C under air flow 43g methacrylic acid whilst maintaining the temperature around 70 ⁰C. Temperature drops for dilution effect but then the exothermic reaction starts. When exothermic reaction is finished, add a second portion of 43g methacrylic acid. Repeat this step for another portion (in total 129g of methacrylic acid are added). After the addition of the last acid portion, reaction mixture was stirred for 15 minutes. At this moment, reaction temperature was increased to 100⁰C and mixture stirred till acid number below 5mg KOH/g and epoxy-equivalent weight EEW 5000-7000 g/eq before cooling. The mixture was set under nitrogen flow in cooling condition. At 75°C, 71 g methoxypropanol and 95g Synperonic PE/F 108 (non-ionic emulsifier; commercially available from Croda were added. Temperature was decreased till 40⁰C whilst stirring. 429g water was added in order to make emulsion A according to state-of-the art emulsion making. After cooling to room temperature emulsion A was obtained. Particle size distribution of such emulsion is about 450nm, being stable to settlement for at least 6 months. Employing non ionic surfactants based on ethyleneoxide (EO) polymers like for instance ethoxylated fatty alcohols instead of ethylene oxide- propyleneoxide (EO-PO) copolymers stable emulsions could not be obtained.

Emulsion B: Synthesis resin B and emulsification To a mixture of 377g Epon 828, 0.08g hydroquinone and 0.89g chromiun trichloride solution (10% in methyl alcohol) was slowly added at 100 ⁰C under air flow 42g methacrylic acid whilst maintaining the temperature around 100 ⁰C. Temperature drops for dilution effect but then the exotermic reaction starts. When exothermic reaction is finished, add a second portion of 42g methacrylic acid. Repeat this step for other two portions (in total 168g of methacrylic acid are added). After the addition of the last acid portion, reaction mixture was stirred till Acid number was below 100mgKOH/g. At this moment, reaction temp was increased to 1 10⁰C and mixture stirred till Acid number below 5mg KOH/g before cooling. At 80⁰C the mixture was set under nitrogen flow and 0.14g of toluhydrodroquinone, 33g methoxypropanol and 55g Synperonic PE/F 87 were added. Temperature was decreased till 40°C whilst stirring. 367g water was added in order to make emulsion B according to state-of-the art emulsion making. After cooling to room temperature emulsion B was obtained.

Particle size distribution of such emulsion is about 550nm, being stable to settlement for at least 6 months.

Curing Atlac 580 .

To 100g Atlac 580 (from DSM Composite Resins, Schaffhausen, Switzerland) was added 2.5g Co Solution (1% Co in spirits) and 0.1 g dimethylaniline. After stirring for 1 hr 1% Butanox M50 (a MEK peroxide solution, commercially available from Akzo Nobel Chemicals Inc.) was added followed by mixing for 30 second. The so obtained unsaturated polyester (UP) resin was applied immediately on the dried sizing film (see further) and will harden at room temperature within an hour.

Eample 1A,B and 2A,B and comparative experiments A and B

On a glass plate a 200 micron thick wet film was applied. The emulsion gave approximately a 100 micron film when dried in an oven with or without the addition of a BPO paste as cure additive to the emulsion, after which a 100 micron film of Atlac 580 was applied on top of the dried film.

After 2 hours at room temperature the Atlac 580 was cured and it was tested whether the films of the sizing and the cured unsaturated polyester could be removed manually from each other. The results are shown in table 1.

As control the commercially available (from DSM Composite Resins, Schaffhausen, Switzerland) epoxy emulsions Neoxil 965 and Neoxil 962D were used, which are known to be compatible with unsaturated polyesters and are employing in the glass fibre reinforcement of UP and epoxy resins.

Table 1

This result clearly indicate that employing as sizing a vinyl ester which is based on a glycidyl ether a superior adhesion towards the UP matrix could be obtained, which is surprisingly in view of the fact that the controls are sizings used for UP matrices. Furthermore this result indicate that adding cure additives to the sizing (example 2) further improves the adhesion to the UP matrix

This result is even more surprising considering the fact that when drying emulsion A or B for 1 hr at 130⁰C no coherent films on the glass plate could be obtained whilst employing both Neoxil 965 and 962D emulsions coherent films on the glass plate were obtained after drying for 1 hr at 130⁰C.

Examples 3A,B and 4A,B and comparative experiments C and D

In an aluminium cup (8cm diameter), 1 Og of emulsion A resp. of emulsion B was applied. The film was dried in an oven with or without the addition of a BPO paste as cure additive, after which a 2mm film of emulsion A and B was obtained. On top of the so obtained films a 2 mm layer of Altlac 580 was applied. After 2 hours at room temperature, the aluminium cup was removed and it was tested whether the films of the sizing and the cured unsaturated polyester could be separated manually from each other. The results are shown in table 2.

Table 2

These experiments clearly demonstrate that with the sizings employed according to the invention, a very good adhesion between the sizing and the UP matrix can be obtained even when they are used as 2 mm thick films.

Examples 5A-5B and Comparative Experiments E-F Preparation of sizing according to the invention (VE sizing)

20kg of the sizing has been prepared adding in a tank 10kg of demi water. Under gentle agitation, 7g of A1100 (aminopropyltrimethoxysilane) was added. Few minutes after, pH was reduced between 3.5 and 6 with acetic acid. 10Og of A 187 (glycidoxypropyltrimethoxysilane) and 16g of A 174 (Methacryloxytrimethoxysilane) were so added and the mixture stirred for about 15 minutes. 608g of vinyl ester resin emulsion B and 258g of Neoxil 965 (epoxy emulsion, EEW 250) were then added.

A premix was prepared diluting in 1 kg of demi water 7.2g of Emery 6760 and 6.2g of Emerstat 6660A. This blend is then added to the main mixture and the final solid content adjusted to 5%.

The sizing is used to produce vinyl ester resin sized glass fiber. Preparation of reference sizing (Neoxil 965 sizing)

The above preparation was repeated, except that 866g of Neoxil 965 was used instead of 608g of VE emulsion B and 258g of Neoxil 965. The sizing is used to produce Neoxil 965 sized glass fibre.

Preparation of sized fibres

Before the individual fibres being drawn from the bushing are gathered and consolidated into a strand, they are coated with the sizing. The fibers pass over a moving surface, called the roller applicator, covered with a film of sizing as described above (VE sizing and Neoxil 965 sizing)size. The applicator is a double-roller type. The gap between the rollers is set to meter the thickness of fibre sizing on the big roller. After application the fiber glass will have around 0.5% of LOI and a diameter adjusted at 15-17micron

In this way VE sized glass according to the invention and the Neoxil 965 sized glass reference were obtained

Preparation of pultrudates

The coated fiber glass are pulltruded using a vinylester resin and a unsaturated polyester resin using 0.5% Trigonox 21 and 1% Trigonox C as peroxides with a glass load of 80wt%. The pultrusion occurred at die temperatures of 150-175⁰C employing a 2 mm thick and 10 mm wide geometry. The pulltrudates were postcured for 4hrs @ 100C

The pultrudates are analyzed for flexural strength according to

ISO 178 using 60 mm long specimens and a support span of 50 mm and for Inter Laminar Shear Strenght according to ISO 14130 using 15 mm long specimens and a support span of 10 mm

Th e results are shown in the table below

These examples clearly demonstrate the advantages in using the sized fibers according to the invention

Claims

1. A glass fibre coated with a sizing composition, wherein the sizing composition comprises 5-70 wt.% of a curable vinyl ester resin being the reaction product of component (a) being at least one component containing at least one glycidyl ether and component (b) being methacrylic acid and/or acrylic acid, 10-97 wt.% water and an ethylene oxide-propylene oxide copolymer as non- ionic emulsifier; the wt.% is relative to the total sizing composition.

2. A fibre according to claim 1 , wherein component (a) being at least one component containing at least two glycidyl ethers.

3. A fibre according to anyone of the above claims, wherein component (a) being a bisphenol A diglycidyl ether, a bisphenol F diglycidyl ether, novolac glycidyl ether or a mixture of at least two of these components.

4. A fibre according to anyone of the above claims, wherein component (a) being a bisphenol A diglycidyl ether or novolac glycidyl ether or a mixture thereof.

5. A fibre according to anyone of the above claims, wherein the sizing composition further comprises a non-reactive organic solvent.

6. A fibre according to anyone of the above claims, wherein the amount of vinyl ester resin in the sizing composition is at least 6 wt.% and at most 50 wt.%.

7. A fibre according to anyone of the above claims, wherein the amount of water in the sizing composition is at least 20 wt.% and at most 96 wt.%.

8. A fibre according to anyone of the above claims, wherein the amount of ethylene oxide-propylene oxide copolymer in the sizing composition, relative to the total amount of vinyl ester resin in the sizing composition, is at least 0.1 wt.% and at most 2.5 wt.%.

9. A fibre according to anyone of the above claims, wherein the ethylene oxide- propylene oxide copolymer in the sizing composition has a molecular weight Mw of from 5000 up to and including 50000.

10. A fibre according to anyone of the above claims, wherein the ethylene oxide- propylene oxide copolymer non-ionic emulsifier in the sizing composition has a molar ratio of ethylene oxide versus propylene oxide of from 1 :0.75 to 1 :5.

11. A fibre according to anyone of the above claims, wherein the ethylene oxide- propylene oxide copolymer non-ionic emulsifier in the sizing composition has a molar ratio of ethylene oxide versus propylene oxide of from 1 :1 to 1 :4.

12. A fibre according to anyone of the above claims, wherein the sizing composition further comprises an inhibitor.

13. A fibre according to anyone of the above claims, wherein the sizing composition further comprises a curing catalyst.

14. A fibre according to claim 13, wherein the curing catalyst is a peroxide.

15. A fibre according to anyone of the above claims, wherein the sizing composition further comprises a coupling agent.

16. Sizing composition comprising 5-70 wt.% of a curable vinyl ester resin being the reaction product of component (a) being at least one component containing at least one glycidyl ether and component (b) being methacrylic acid and/or acrylic acid, 10-97 wt.% water and an ethylene oxide-propylene oxide copolymer as non-ionic emulsifier, with the proviso that the sizing composition does not comprise a photo-initiator; the wt.% is relative to the total sizing composition.

17. Use of sized glass fibres according to anyone of claims 1-15 in a matrix of a thermosetting synthetic resin or of a thermoplastic polymer.

18. Use according to claim 17, wherein the matrix is a thermosetting synthetic resin.

19. Use according to claim 18, wherein the thermoset composite comprises an unsaturated polyester resin and/or a vinyl ester resin.