WO2001090017A1

WO2001090017A1 - Sizing composition for glass yarns, resulting yarns and use thereof in cement products

Info

Publication number: WO2001090017A1
Application number: PCT/FR2001/001589
Authority: WO
Inventors: Eric Dallies; Eric Augier
Original assignee: Saint-Gobain Vetrotex France S.A.
Priority date: 2000-05-24
Filing date: 2001-05-23
Publication date: 2001-11-29
Also published as: FR2809389B1; FR2809389A1; CN1444548A; JP2003534462A; EP1284940A1; AU2001264006A1; CN1298653C

Abstract

The invention concerns a sizing composition for glass yarns, containing at least a bonding agent in a water base liquid carrier, comprising at least a silane additive bearing at least a function capable of complexing calcium. Preferably, at least one additive is selected among the compounds of formula (1) wherein R1 is an alkyl, or a C¿1?-C6 acyl, or phenyl group; R?2¿ is a hydrogen atom or an alkyl or phenyl group of 1 to 6 carbon atoms; R3 is a hydrocarbon chain, linear or branched, saturated or unsaturated, optionally substituted, advantageously comprising 2 to 20 carbon atoms; R4 is a hydrogen atom or a linear or branched alkyl group of 1 to 4 carbon atoms, or a -CO-R5 group, wherein R5 is a hydrogen atom or an alkyl or alkoxy group, linear or branched, of 1 to 4 carbon atoms; R6 is a polar group in particular carbonyl or amino; n is an integer from 1 to 3; m is an integer from 1 to 3; p is a non-null integer; q is a null or non-null integer, with p + m + q ≤ 6. The invention is useful for producing glass yarns designed to reinforce cement products.

Description

SIZING COMPOSITION FOR GLASS WIRES, THESE WIRES AND THEIR USE IN CEMENTITIOUS PRODUCTS

The present invention relates to the field of filamentary reinforcing materials and relates more particularly to glass strands intended for the reinforcement of materials, in particular mineral, said strands and / or said materials being liable to be exposed to a corrosive medium. The invention also relates to the composition used to coat the strands (called sizing composition), as well as the use of the strands in cementitious products and the products thus obtained.

The use of glass strands (or by abuse of the term "glass fibers") as reinforcing material is well known. These threads consist of filaments gathered in a thread and coated with a sizing composition intended in particular to protect the threads from abrasion and possibly to compatibilize the thread with the material where it will be used as reinforcement.

In the case of wires intended to be used in corrosive media, such as the matrices of cementitious products or else in products themselves used under corrosive conditions (permanent contact with water, salts, acid), a glass composition adapted to have increased resistance under the conditions considered. Thus, for the production of threads having improved chemical resistance in the basic medium of a cement matrix, known compositions of so-called alkali-resistant glasses which generally contain a large proportion of zirconium oxide. For information, reference may be made to document & B-A-1 290 528. However, these glass strands remain subject to a certain degradation, although reduced, in the cement environment, and additional protection methods have been proposed, in particular by incorporating additives into the sizing composition. Thus, document FR-A-2 235 888 indicates as protective material to be incorporated into the composition of the coating, a mono- or polycyclic aromatic compound carrying at least three hydroxyl groups on the, or if necessary at least one, nucleus aromatic. As particular examples of such protective compounds, mention is made of pyrogallol, a hydroxy-hydroquinone, phloroglucinol, gallic acid, propyl gallate, or other trihydroxybenzoic acids or derivatives.

FR-A-2 318 833 describes a dihydroxybenzoic acid as a protective compound capable of preventing or reducing the formation in the vicinity of the wires of calcium hydroxide crystals from the saturated solution of calcium hydroxide present in the cement (so-called anti-cementation compound).

FR-A-2 370 705 teaches to include in the coating composition a water-soluble ester formed by the reaction of a trihydroxy- or dihydroxy- substituted aromatic carboxylic acid, in particular gallic or dihydroxybenzoic acid, with an alcohol of which the molecule contains at least two hydroxy radicals.

These solutions provide improvements in the resistance of cementitious products reinforced with the wires thus prepared, but the effect is sometimes limited in duration, it seems, by a phenomenon of trapping of the protective compound within the coating deposited on the wire. , a phenomenon which would prevent the compound from reacting properly with the alkaline environment.

In addition, the presence of these additives in the sizing composition is not without effect on the quality of the yarn obtained, so that the other properties of the yarn may be adversely affected, and the yarn may prove to be unsuitable for some applications. Thus it can be observed that the presence of gallic ester or equivalent compound in certain sizes can disturb the integrity of the wire, which makes its implementation very difficult in techniques where the wire is worked dry or dry mixed with the components of the cement product. This is for example the case for the manufacture of cement-glass composite products by simultaneous projection of cut wire and cement in the direction of a mold. In this particular case, a lack of integrity of the thread leads to the formation of fluff or lint which fouls the organs of the projection device, or even fly into the environment of the operator with a notable discomfort for the latter.

This problem then requires an adaptation of the base of the sizing with materials which can influence the cost of the product. The object of the invention is to propose a sizing composition capable of effectively protecting a glass strand in a corrosive medium, such as a hydrated cement matrix without harming the workability of the product.

This object, as well as others which will appear subsequently, has been achieved by incorporating into the sizing composition an additive of silane type carrying at least one function capable of complexing the calcium CdX.

In this regard, the subject of the invention is a sizing composition containing at least one tackifying agent in a liquid vehicle with an aqueous base, characterized in that it comprises at least one additive of silane type carrying at least one function capable of complex calcium. It has been found that functional groups capable of reacting with the surrounding calcium hydroxide by complexing the calcium can play their role effectively Without harming the integrity of the wire, if they are carried by a silane. An attempt to explain may be that the silicon chain would allow the active groups to be kept close to the glass by polar interaction of the glass and the silane, while preventing irreversible incorporation of the active groups in the coating deposited on the glass, so that the reactive functions would be available without harmful interaction with the other components of the coating.

Preferably, the silane additive comprises at least one benzene nucleus carrying at least two substituents, identical or different, capable of complexing calcium, that is to say that the two substituents together form a calcium complexing function.

Advantageously, at least one group carrying a calcium complexing function is of the mono- or poly-hydroxyphenyl type, preferably of the ortho-diphenol or ortho-triphenol type, where the hydroxyl groups are optionally at least partly in etherified form or blocked by protective groups, in particular acyl or carbonate. At least one carbonγl group can optionally substitute phenyl for ortho of a hydroxyl.

The silane type additive can advantageously be chosen from the compounds of formula (1) below:

in which :

• R ¹ is an alkyl, phenyl or acyl group of 1 to 6 carbon atoms,

R ² is a hydrogen atom or an alkyl group of 1 to 6 carbon atoms or phenyl,

R ³ is a hydrocarbon chain, linear or branched, saturated or unsaturated, optionally substituted, advantageously comprising from 2 to 20 carbon atoms,

• R ⁴ is a hydrogen atom or a linear or branched alkyl group of 1 to 4 carbon atoms, or a group

- CR ⁵

where R ⁵ is a hydrogen atom or a linear or branched alkyl or alkoxy group of 1 to 4 carbon atoms,

• R ⁶ is a polar group, in particular carbonyl or amino • n is an integer from 1 to 3,

• m is an integer from 1 to 3,

• p is a non-zero integer

• q is an integer zero or not with p + m + q ≤ 6, and when n, m, p or q is greater than 1, the groups R ¹ , respectively R ² , R ³ , R ⁴ , R ⁵ or R ⁶ can be the same or different.

Compounds of the monohydroxyphenyl or derivative type (p = 1) are capable of complexing calcium as soon as two neighboring molecules can cause each contribute their hydroxy group.

However, taking into account the relative steric hindrance which the compounds of formula (1) can have, silanes are preferred:

- poly-hydroxyphenyl derivatives (p> 2), advantageously with at least two hydroxyl groups carried by two neighboring benzenic carbon atoms

(ortho relative position); or

- Carbonyl-hydroxyphenyl or amino-hydroxyphenyl derivatives (p> 1; q> 1), advantageously with a hydroxyl and a carbonyl or amino carried by two neighboring benzenic carbon atoms (relative position ortho). This ensures the presence of the two complexing groups at a respective distance to interact with the calcium.

Among the compounds of formula (1), therefore, particular preference is given to the compounds of formula (2) below:

in which :

• R ⁷ = OR ⁴ or R ⁶ , where R ⁴ and R ⁶ have the previous meanings,

• r = 0 or 1.

Among these compounds, the compounds of formula (3) and (4) below are considered to be advantageous:

For reasons of steric hindrance, it is generally preferable to choose m = 1 in the formulas (1), (2), (3) or (4).

On the other hand, a good affinity of the silane for the glass yarn is obtained with n = 2 or 3, preferably 3, in the formulas (1), (2), (3) or (4). Examples of the meaning of R groups are as follows:

• R ¹ can be a methyl, ethyl, propyl, butyl group, in particular n-butyl, acyl, formyl, phenyl. The methyl, formyl and acyl groups are preferred because of the rapid hydrolysis of the corresponding methoxysilyl, formylσxysilyl or acetoxysilyl groups into hydroxysilyls which interact with the surface hydroxyls of the glass;

• R ² may advantageously be an ethyl group of 1 to 4 carbon atoms, in particular a methyl or ethyl group;

• R ³ may advantageously contain from 2 to 6 carbon atoms, in particular from 2 to 4. It may especially be a C2-C ₄ alkylene radical, in particular ethylene -CH2-CH2-, propylene -CH ₂ - CH ₂ -CH ₂ -:

• R ⁴ may be a methyl, ethyl, propyl, butyl group, preferably methyl, or else a - (CO) -R ^{5 group} where R ⁵ is, for example, a hydrogen atom, a methyl, ethyl group or a methoxy, ethoxy, propoxy, butoxy, isopropoxy group.

A group - (CO) -R ⁵ has the effect of blocking or protecting the hydroxy radical to which it is attached, which improves the stability of the phenolic silane during storage. Indeed, the phenolic hydroxyl groups may tend to react with the alkoxysilyl or acyloxysilyl group (s) of the silane by transesterification with the risk of formation of oligomers, which would increase the viscosity of the liquid composition into which the silane. This protective effect is particularly advantageous in the case of polyhydroxyphenylsilanes (R ⁷ = OR ⁴ in formula 2).

Preferably, in a compound of formula (1) (2) or (3) at least one group R ⁴ is a group - (CO) -R ⁵ .

Depending on the kinetics of release of the protective group in the liquid medium of the sizing composition, the latter may contain at a given time Either essentially blocked silane, or essentially released silane, or a mixture of the two in variable proportions . The unblocking reaction generates R ⁵ COOH acid as by-products when

R ⁵ is H or alkyl, or CO _z and an alcohol R ⁵ H when R ⁵ is alkoxy.

It is advantageous to choose R ⁵ so that these by-products either do not interfere with the sizing composition, or are eliminated from the composition at any stage of its manufacture or of its use, for example by evaporation or volatilization.

Certain blocking groups may also be preferred because they promote the solubility of the silane in the medium of the composition.

As an indication, the H-CO- formyl protecting group (R ⁵ = H) is rapidly unblocked in water and its hydrophilic nature increases the solubility of silane in water.

Another preferred protective group is the acetyl group CH3-CO- (R ⁵ = CH3).

A class of interesting silanes is thus formed of those corresponding to the formula (3 ') below:

in which :

• R ¹ , R ² , R ³ , R ⁴ , R ⁵ have the meaning indicated above,

• R ⁸ is a hydrogen atom or a linear or branched alkyl group of 1 to 4 carbon atoms, in particular methyl or ethyl, r = 0 or 1, preferably 0.

Particularly preferred is a methyl group for R ⁸ , since the methoxy group substituting the aromatic ring increases the water solubility of the silane.

It is preferred that all the hydroxyl groups or derivatives substituting the benzenic ring are carried by neighboring carbon atoms, in particular according to the formula (3 ") below:

where R ⁴ is preferably a hydrogen atom or an alkyl group.

Very advantageously, the chain R ³ is in the para position relative to the group -O-CO-R ⁵ .

According to a preferred embodiment of the invention, the composition comprises at least one silane of formula (3 ") in which R ³ is para -O (CO) R ⁵ and R ¹ = R ⁵ = R ⁸ = CH ₃ , n = 3, R ³ = - (CH ₂ ) ₃ -, q = 0, i.e. 3- (4-acetoxy-3-methoxyphenyl) propyl-trimethoxysilane

Another class of interesting Silanes is formed by those corresponding to formula (4) below:

in which R ¹ , R ² , R ³ , R ⁴ , R ⁸ have the above meanings.

In this class, the chain R ³ is very advantageously in para with respect to OR ⁸ , and r is preferably equal to zero.

The compounds of formula (4 ") below are preferred:

According to a preferred embodiment of the invention, the composition comprises at least one silane of formula (4 ") in which R ¹ = CH ₃ , n = 3, R ³ = - (CH ₂ ) 3-, R ⁸ = H, i.e. 3- (4-hydroxy-3-carbonylphenyl) propyl-trimethoxysilane

In general, a sizing composition comprises so-called active materials in a liquid vehicle, generally based on water.

The composition generally comprises around 70 to 98%, especially 80 to 95%, by weight of aqueous vehicle, and is in the form of a dispersion, suspension, emulsion, or mixture of emulsion (s) and / or suspension (s), or solution. Among the active materials, the predominant material is a tackifier or a system of tackifiers for a total of about 50 to 75% by weight of the dry extract of the composition.

A tackifier is intended to ensure the bonding of the filaments with one another within the threads: these are generally substances of the polymer or prepolymer type which are generally crosslinkable. As an example, we can mention tights:

- based on epoxy resin, in particular an epoxidized derivative of bisphenol, epoxyphenol novolak resin, phenylglycidylether, or

- having a polyester function, in particular based on polyvinyl acetate, for example a crosslinkable polyvinyl acetate containing N methylolacrylamide units, or based on a copolymer of vinyl acetate and an olefin such as ethylene, or else based on a mixture of polyvinyl acetate and another polyester derived from maleic anhydride and ethylene glycol.

The level of silane (s) meeting the definition of the invention in the sizing composition is generally of the order of 2 to 20% by weight of the dry extract, advantageously from 4 to 18%, preferably from 6 to 16%, the improvement in mechanical properties after aging of the composites generally increasing with these rates. In the vicinity of the limit rate of 20%>, the cost of the composition becomes very large without significant improvement in the properties. In addition to at least one silane as previously mentioned, the sizing composition according to the invention can comprise one or more other silanes generally playing the role of coupling agents, in particular one or more silanes commonly used in sizing such as gamma methacryloxypropyltrimethoxy silane, gamma glγcidoxypropyltrimethoxy silane, (N-benzyΙaminoethyl) aminopropyl-trimethoxysilane etc ...., this or these silanes being able to contribute to the coupling between the glass strands and the reinforced material. In this case, the level of the silane (s) other than the silane defined according to the invention may generally be of the order of 5 to 107% by weight and, preferably 1 to 5% by weight of the dry extract of the composition. according to the invention, the maximum level of silaneis), all silanes combined, not exceeding 25% by weight of the dry extract of the composition according to the invention. The sizing composition can also comprise other coupling agents such as titanates, zirconates, etc. or organic compounds facilitating the coupling of glass strands to certain organic materials.

In addition to the components mentioned above, the composition according to the invention may also comprise other components, in particular components commonly used in sizing compositions such as lubricating agents, or even one or more film-forming agents, textile agent, agent antistatic, emulsifying agent, surfactant, wetting agent, etc., the proportion of these agents preferably being less than 30% by weight of the dry extract of the composition. In most cases, the composition comprises at least one lubricating agent, for example a fatty acid ester or a fatty alcohol derivative, the proportion of lubricating agent preferably being at least 5% by weight of the dry extract of the composition. The composition can also comprise a hydrophobic agent intended to maintain the degree of humidity of a hydrated cementitious material around the glass strands for a good impregnation thereof. The sizing composition can be obtained by directly mixing all the components or by adding the components in several stages. Generally, the silane can be added to the composition in hydrolysis form, in an alcohol, for example methanol, optionally mixed with water. It can also be mixed with a tackifier in emulsion or in dispersion. After the components have been mixed, a generally aqueous liquid vehicle is added to the mixture in order to obtain the desired composition and properties.

The subject of the invention is also glass strands coated with a sizing composition as described above.

The composition is generally deposited on the glass filaments before they are gathered into son at the stage of manufacture of the latter.

In general, the production of the glass strands according to the invention is carried out in the following manner: molten glass filaments are drawn mechanically in the form of one or more plies of continuous filaments from the orifices of one or more dies, then the filaments are coated with the sizing composition according to the invention before being gathered into one or more threads. These threads can then be wound on rotating supports before undergoing other operations (extraction for indirect cutting, weaving, etc.), be distributed on moving conveyors or even be cut after formation by the organ used to stretch them (direct cut under die). The presentation of the wires thus varies depending on the application envisaged. The glass strands according to the invention may in particular be in the form of windings of continuous strands (rovings, cakes, cans, etc.), in the form of cut strands, of mats (layers of intermingled continuous strands), of braids, ribbons, networks, etc. these different threads generally being composed of filaments with a diameter between 5 and 24 μm. The glass strands according to the invention are mainly intended to be exposed to corrosive media, such as hydrated cementitious materials. In this regard, the wires are advantageously obtained from a so-called alkali-resistant glass, which generally contains zirconium oxide Zr0 ₂ .

These strands can be chosen from all the existing alkali-resistant glass strands (such as those described in patents GB 1,290,528, US 4,345,037, US 4,036,654, US 4,014,705, US 3,859,106, etc. ) and preferably comprise at least 5 mol% of ZrO ₂ . According to one embodiment of the invention, the glass constituting the wires comprises Si0 ₂ , Zr0 ₂ and at least one alkaline oxide, preferably N zO, as main constituents.

An alkali-resistant glass composition particularly used to make glass strands according to the invention is the composition described in patent GB 1,290,528, composed mainly of the following components in the proportions expressed in molar percentages: 62-75% SiO ₂ ; 7-11% ZrO ₂ ; 13-21% R ₂ O; 1- 10% R'O; 0-4% Al ₂ 0 ₃ ; 0-6% B ₂ 0 ₃ ; 0-5% Fe ₂ 0 ₃ ; 0-2% CaF ₂ ; 0-4% Ti0 ₂ ; R ₂ 0 representing one or more alkali metal oxide (s), preferably Na ₂ 0 and, optionally (up to 2%) Li ₂ O, and R'O being one or more components chosen from alkali metal oxides earthy ZnO and MnO.

The quantity of size deposited on the glass strands, also called loss on ignition, is preferably between 0.2 and 4% by weight of the strands, in particular of the order of 0.5 to 3%, in particular of 1 to 2.5%. The wires according to the invention can be used to make composites based on cementitious materials (cement, concrete, mortar, gypsum, slag, compounds formed by the reaction of lime, silica and water, etc.). The strands confer improved mechanical properties after aging, in particular as regards the ductility of the composites. The wires are also suitable for making composites by spraying into an open mold.

These applications are also objects of the invention.

Other characteristic and advantageous aspects of the invention will appear from the description of the following illustrative examples.

The following examples use glass wire implementation tests and mechanical tests on a composite which are described below in common. 1) Suitability for projection:

The technique of projection uses an equipment in which a continuous glass wire wound on a reel (roving) is guided by means of fixings (rings) towards a cutter for a continuous cut; at the outlet of the cutter, the cut wire is sent to a projection nozzle where it is mixed with a flow of hydrated cement; the nozzle simultaneously projects the fibers and the cement onto the surface of an open mold. During these stages, it can appear from the flock and the formation of sticky deposits during the passage of the wire in the tie-downs, due to the friction of the wire on the latter which breaks small filaments of the wire or which deposits part of the sizing on the rings. On the other hand, at the outlet of the spray gun, the cut wire can lose its integrity by forming lint which is less effective than a wire incorporated as reinforcement in a composite.

In the projection aptitude test, dry wire without cement is passed through the device and a visual assessment is made of the three criteria of flock, sticky deposit, integrity. By giving a + to each satisfactory criterion and a - if not, the score can vary as follows:

- very bad ; - bad ; + good; +++ very good.

2) Tensile strength of a wire in cement:

This test consists in drowning a glass wire in a cube of cement composed of: 75 parts by weight of CPA 52.5: 25 parts by weight of sand; 32 parts by weight of water.

The cube is subjected to ripening and aging conditions for 4 days in hot water at 80 ° C.

The stress at break of the wire in tension is then measured. The measurement result is conventionally known as “Strand In Cernent” expressed in MPa.

This measurement is mainly sensitive to the alkaline attack of glass by the cement, and is much less sensitive to carburizing (precipitation of crystals of

Ca (OH) ₂ in the matrix). In the context of the examples according to the invention, this measurement makes it possible to verify whether or not the additive compromises the protective function of the sizing sheath surrounding the glass filaments. 3) Flexural strength of flat products:

These products are produced by simultaneous projection of cut glass wire and cement at a rate of 5% by weight of glass fibers, relative to the total weight of the composite. The sheets thus produced are stored for a ripening period of 28 days, then are cut into test pieces subjected to a 4-point bending test (standard EN 1170-5).

The breaking stress (MOR) and the elongation at break (S _M OR) are measured after different accelerated aging deadlines (14 and 28 days at 60 ° C or 28 and 56 days at 50 ° C).

The elongation at break is representative of the ductility of the composite, which is very sensitive to cementation and, consequently, of the effectiveness of the complexing additive. EXAMPLE 1

In this example, glass filaments of 14 μm in diameter are obtained by drawing filaments of molten glass, this glass being an alkali-resistant glass of the following composition expressed in percentages by weight:

SiO ₂ 61.6%

Al ₂ O ₃ 0.9%

ZrO ₂ 16.8% CaO 5.4%

Na ₂ O 14.7%

K ₂ O 0.3%

Fe ₂ O ₃ 0.05%

Fluor 0.26% TiO ₂ 0.1%

S0 ₃ 0.05%

These filaments are coated, during their journey before gathering into threads, with a sizing composition comprising (in percentages by weight of dry matter): • tackifier:

polyvinyl acetate crosslinkable by N methylolacrylamide units 66% sold under the reference Vinamul 8828 by the company TNAMUL

- polyester derived from maleic anhydride and ethylene glycol 7.3% sold under the reference Neoxil 966 D by the company DS ITALIA

• anti-carburizing additive

3- (4-acetoxy3-methoxy phenyl) prσpyltrimethoxysilane 15% sold by the company WITCO

• fluorinated hydrophobic additive 3.2% • lubricant: paraffin 6.4%

• coupling agent:

(N benzylaminoethyl) aminopropyltrimethoxysilane 2.67o sold in the form of a hydrochloride solution in methanol under the reference Silquest A 1128 by the company WITCO The sizing composition is deposited on the glass wire with a loss on ignition of the around 2%.

Subject to tests 1) to 3) explained above, the wire demonstrates the properties listed in table 1.

For test 3), the wire was used in a cement composed of: 100 parts by weight of CPA 52.5; 100 parts by weight of sand; 1.8 parts of plasticizer; 36 parts by weight of water (water / cement ratio = 0.36). EXAMPLE 2

This example illustrates the properties of a wire, the size of which contains another additive of the silane type complexing calcium. The sizing composition is the same as that of Example 1, except that the 3- (4-acetoxγ3-methoxy phenyl) propyltrimethoxysilane is replaced by 3- (4-hydroxy-3-carbonylphenyl) propyl-trimethoxysilane also marketed by WITCO.

The sizing composition is deposited on the glass wire with a loss on ignition of the order of 2% and the properties of the wire subjected to tests 1) to 3) are presented in Table 1. In order to determine the effectiveness of the silane additives used, two comparative examples are produced. COMPARATIVE EXAMPLE 1

This example illustrates the properties of a wire whose size does not contain any calcium complexing additive.

In example 1, the size composition is therefore modified as follows:

• tackifier:

-polyvinyl acetate crosslinkable by N methylolacrylamide units 70.8% Vinamul 8828

- plasticizer mixture 50/50 diethylene glycol dibenzoate 14% dipropylene glycol dibenzoate

- polyester Neoxil 966 D 3.5%

• hydrophobic fluorinated additive 1.4% • lubricant: paraffin 7.6%

• coupling agent:

- (N benzylaminoethyl) aminopropyltrimethoxysilane 2.6% Silquest A 1128

COMPARATIVE EXAMPLE 2 This comparative example illustrates the properties of a yarn whose size contains a calcium complexing additive which is not a silane but a gallic ester.

In Example 1, the size composition is modified as follows:

• tackifier:

-polyvinyl acetate crosslinkable by N methylolacrylamide units 61.4% Vinamul 8828

- plasticizer: 50/50 mixture of diethylene glycol dibenzoate 11.1% dipropylene glycol dibenzoate

- polyester maleic anhydride-ethylene glycol Neoxil 966 D 2.7%

• gallic ester 14% • hydrophobic fluorinated additive 1.3%

• lubricant: paraffin 7.2% coupling agent: (N benzylam inoethy l) am inopropy Itr imethoxysi fane 2.3% Silquest A 1128

TABLE 1

These results show that the additives used in Example 1 and 2 according to the invention have a favorable impact on the maintenance of the mechanical properties of the cement-glass composite after aging. The mechanical resistance (MOR) is thus improved, but it is especially the ductility of the composites which is affected (improvement of 40 to 50% for a short aging time) compared to Comparative Example 1.

Compared to Comparative Example 2, which uses an anti-carburizing additive, there is a slight gain in mechanical strength, but above all the ability to project is clearly improved. This shows that the additives used according to the invention disturb the integrity and the workability of the wire less than the reference additive. EXAMPLE 3

Example 1 is reproduced by lowering the calcium complexing silane content to 6.5% by dry weight of the size.

The composition is used with a loss on ignition, also lower, of 1.7%. The results are recorded in Table 2 where the results of Example 1 are recalled. EXAMPLE 4

In this example, a sizing composition is used with a modified tackifier. The composition is therefore as follows:

• tackifier:

-polyvinyl acetate crosslinkable by N methylolacrylamide units 64.5%

Vinamul 8828

- 16.5% vinyl acetate-ethylene copolymer sold under the reference Mo ilith DM 105 by the company Clariant

• 3- (4-acetoxy3-methoxy phenyl) propyltrimethoxysilane 8% sold by the company WITCO

• hydrophobic fluorinated additive 1.3%

• lubricant: paraffin 7.2%

• coupling agent:

(N benzylaminoethyl) aminopropyltrimethoxysilane 2.3% Silquest A 1128

The results are also presented in Table 2.

TABLE 2

It appears from this comparison that the properties of the wire are always good with regard to the sprayability and that the mechanical properties remain good despite the reduction in the silane content.

The modification of the tackifier by substitution of the polyester with an ethylene vinyl acetate copolymer also leads to an increase. significant ductility, even after long aging times. It can be assumed that this is due to the fact that the polymer itself is more resistant to hydrolysis by the alkaline medium of the cement when it is partially substituted by ethylenic groups. EXAMPLE 5

The wire of example 1 is subjected to the mechanical resistance test 3) in a cement matrix modified by the addition of pozzolan, which is an additive of cement known to react with calcium in Solution and prevent the precipitation of hydroxide sodium. The composition of this cement is as follows: 100 parts by weight of cement

CPA 52.5; 100 parts by weight of sand; 25 parts by weight of metakaolin ECC 501; 2 parts by weight of plasticizer; 36.5 parts by weight of water. EXAMPLE 6

This time, the wire of Example 4 is tested in the cement matrix of Example 5.

COMPARATIVE EXAMPLE 3

The thread of Comparative Example 1 is tested in the cement matrix of Example 5.

The results are shown in Table 3 below. TABLE 3

These results show that even in a matrix adapted to improve the mechanical properties of the composite (as demonstrated by the comparison of Comparative Examples 1 and 3), the complexing silane additive used according to the invention brings an additional improvement by guaranteeing a resistance excellent mechanical properties over time (in particular the ductility for long aging times).

Claims

1. Sizing composition for glass wire, in particular of alkali-resistant glass, containing at least one tackifier in an aqueous-based liquid vehicle, characterized in that it comprises at least one additive of silane type carrying at least one function capable of complexing calcium.

2. Composition according to Claim 1, characterized in that the silane additive comprises at least one benzenic nucleus carrying at least two substituents, identical or different, capable of complexing the calcium.

3. Composition according to claim 1 or 2, characterized in that the silane additive carries at least one function of the mono- or polyhydroxyphenyl type, where the hydroxy groups are optionally at least partly in etherified form or blocked by protective groups, especially acyl or carbonate.

4. Composition according to claim 3, characterized in that it comprises at least one additive chosen from the compounds of formula (1)

in which :

R ¹ is an alkyl or acyl group of 1 to 6 carbon atoms or phenyl,

• R ² is a hydrogen atom or an alkyl or phenyl group of 1 to 6 carbon atoms, • R ³ is a hydrocarbon chain, linear or branched, saturated or unsaturated, optionally substituted, advantageously comprising from 2 to 20 atoms carbon,

• R ⁴ is a hydrogen atom or a linear or branched alkyl group of 1 to 4 carbon atoms, or else a group -CO- R ⁵ where R ⁵ is a hydrogen atom or a linear alkyl or alkoxy group or branched from

1 to 4 carbon atoms,

• R ⁶ is a polar group, in particular carbonyl or amino

• n is an integer from 1 to 3, • m is an integer from 1 to 3,

• p is a non-zero integer,

5. Composition according to claim 4, characterized in that it comprises at least one additive of formula (2)

in which: • R ⁷ = OR ⁴ or R ⁶ , where R ⁴ and R ⁶ have the previous meanings, • r = O or 1.

5. Composition according to claim 3 or 4, characterized in that it comprises at least one additive of formula (3) or (4)

7. Composition according to any one of claims 4 to 6, characterized in that in the formula (1) (2) (3) or (4) m = 1 and n = 2 or 3.

8. Composition according to any one of claims 4 to 6, characterized in that it comprises at least one additive of formula (1) (2) or (3) in which at least an R ⁴ group is a -CO-R ^{5 group} .

9. Composition according to claim 8, characterized in that it comprises at least one additive of formula (3 ')

in which :

• R ¹ , R ² , R ³ , R ⁴ , R ⁵ have the meaning indicated above,

• R ⁸ is a hydrogen atom or a linear or branched alkyl group of 1 to 4 carbon atoms, in particular methyl or ethyl, r = O or 1, preferably 0. 10. Composition according to any one of claims 4 to 7, characterized in that it comprises at least one compound of formula (4)

in which R ¹ , R ² , R ³ , R ⁴ , R ⁸ have the above meanings.

11. Composition according to any one of claims 4 to 10, characterized in that in the formula (1), (2), (3), (4), (3 '), (4):

• R ¹ is a methyl, formyl or acyl group

• R ² is a methyl or ethyl group

• R ³ is an ethylene or propylene radical

• R ⁴ is a methyl, carboxy or acetyl group.

12. Composition according to claim 9, characterized in that it comprises at least one additive of the following formula:

13. Composition according to claim 10, characterized in that it comprises at least one additive of the following formula:

14. Composition according to any one of the preceding claims, characterized in that it comprises at least one tackifying agent based on a vinyl acetate polymer or copolymer.

15. Glass thread intended for the reinforcement of in particular mineral materials, characterized in that it is coated with a sizing composition according to any one of the preceding claims.

16. Glass strand according to claim 15, characterized in that it is obtained from an alkali-resistant glass.

17. Use of a glass wire according to claim 15 or 16 for the reinforcement of a cementitious product.

18. Cement product reinforced with glass threads, characterized in that the threads are as defined in claim 15 or 16.