Glass Fibers Coated With Compositions Containing Complex Organo Silicon Compounds

This invention relates to size compositions, and more particularly to size compositions for use in the treatment of glass fibers to improve the bonding relationship between glass fibers and resinous plastics in the manufacture of glass fiber reinforced plastics.

The term "glass fibers", are used herein, is intended to refer to and include (1) continuous fibers formed by rapid attenuation of hundreds of streams of molten glass and to strands formed when such continuous glass fiber filaments are gathered together as they are being formed; and to yarns and cords formed by plying and/or twisting a number of strands together, and to woven and non-woven fabrics which are formed of such glass fiber strands, yarns or cords, and (2) discontinuous fibers formed by high pressure stream, air or other suitable attenuating force directed onto multiple streams of molten glass issuing from a glass melting bushing or from an orifice containing spinner, and to yarns that are formed when such discontinuous fibers are gathered together to form a silver which is drafted into a yarn; and to woven and non-woven fabrics formed of such yarns of discontinuous fibers, and (3) combinations of such continuous and discontinuous fibers in strands, yarns, cords and fabrics formed thereof.

It is now standard practice in the manufacture of glass fiber-reinforced plastics to employ glass fibers which have been coated with an organo silicon compound in the form of an organo silane or its hydrolysis products (e.g., the corresponding silanols and/or polysiloxanes). The nature of the organo silicon compound employed depends somewhat on the particular plastic to be reinforced. For example, where the resin is a polyepoxide, the organo silicon compound is frequently an organo silane containing an epoxy group ##EQU1## where x is an integer from 2 to 5 and R is an alkyl group containing 1 to 5 carbon atoms, or the corresponding hydrolysis products thereof. Where the resin is a polyester, the organo silicon compound frequently contains ethylenic unsaturation; the silane can be

or more preferably ##EQU2## wherein R.sub.1 is hydrogen or methyl.

While such silanes as well as their hydrolysis products are quite effective in promoting a secure bond between glass fibers and thermosetting plastics, they are quite expensive and therefore provide a significant contribution to the overall cost of manufacture of glass fiber reinforced plastics. Numerous attempts have been made to reduce the cost of such silanes, usually by replacing a portion of the epoxy or acryloxyalkyl silanes with a less expensive silane. In U.S. Pat. No. 3,702,783 there is described a size composition which is formulated to contain a glycidoxyalkyl silane of the type described above and a methyltrialkoxy silane. However, the methyltrialkoxy silane is not significantly less expensive than the glycidoxyalkyl silane and, consequently, the organo silicon compounds proposed by the foregoing patent represent only marginal savings.

It is accordingly an object of the present invention to provide a size composition for use in the treatment of glass fibers to promote a secure bonding relationship between glass fibers and organic resins.

It is a more specific object of the invention to provide a size composition for use in the treatment of glass fibers for use as reinforcement for resinous plastics or as reinforcement for elastomeric materials.

It is another object of the invention to provide glass fibers treated with the composition of this invention for use as reinforcement for plastic or elastomeric materials.

The concepts of the present invention reside in a glass fiber size composition which is formulated to include as the essential components a blend of an acrylate silane having the formula ##EQU3## wherein R is hydrogen or methyl, x is an integer from 3 to 6 and R.sub.1 is lower alkyl (e.g., methyl, ethyl, propyl, isopropyl, etc.), or the hydrolysis products thereof such as the corresponding silanol or polysiloxane and a complex organo silane characterized by one or more beta-haloalkoxy groups of the formula ##EQU4## wherein X is halogen.

Representative acrylate silanes include gamma-acryloxypropyltrimethoxy silane, gamma-methacryloxypropyltriethoxy silane, .DELTA.-methacryloxybutyltrimethoxy silane, etc. Preferred is gamma-methacryloxypropyltrimethoxy silane since this material is commercially available from Union Carbide under the trademark A-174. Such silanes are prepared in a conventional manner by forming the corresponding chloroalkyl silane by the reaction

The complex silanes having the beta-haloalkoxy group employed in the practice of the invention are those described in copending applications Ser. No. 347,264 and Ser. No. 347,241, both of which are filed on Apr. 2, 1973, and the disclosures of which are incorporated herein by reference.

As is described in the foregoing copending applications, the complex organo silanes are prepared by reaction of various combinations of epoxides with a halosilane, and preferably a silicon tetrahalide. Epoxides used in the preparation of such silanes include alkylene oxides and the following: 1. Epoxides of the formula ##EQU7## wherein R.sub.2 is an aryl group such as phenyl or phenyl substituted with an amino group, a halogen group, an alkyl group; alkyl containing 1 to 20 carbon atoms and substituted derivatives thereof; an alkenyl group containing 2 to 8 carbon atoms (e.g., vinyl, allyl, etc.); styrene oxide; a group having the formula ##EQU8## wherein R' is hydrogen or methyl. Illustrative of such epoxides are phenyl glycidyl ether, cresyl glycidyl ether, allyl glycidyl ether, glycidyl acrylate, glycidyl methacrylate, a mixture of n-octyl and n-decyl glycidyl ethers (Epoxide No. 7 from Proctor and Gamble) and a mixture of n-dodecyl and n-tetradecyl glycidyl ethers (Epoxide No. 8 from Procter and Gamble). 2. Epoxides of the formula ##EQU9## wherein R.sub.3 is a divalent organic radical such as alkylene containing 1 to 10 carbon atoms; alkylene-oxyalkylene containing 2 to 20 carbons; oxyalkyleneoxy containing 1 to 10 carbon atoms; oxyalkylene-oxyalkyleneoxy containing 2 to 20 carbon atoms; divalent aromatic groups such as a group of the formula ##SPC1##

A numbeer of such epoxides are commercially available from Dow and Ciba and include the following: ##EQU10## ##SPC2## 3. Cycloalkane epoxides, including the following: ##EQU11## ##SPC3## ##SPC4##

In accordance with one embodiment of copending application Ser. No. 347,264, the organo silicon compounds are prepared by reaction of from 1 to 3 epoxide equivalents of the alkylene oxide and at least 0.5 and up to 3 epoxide equivalents of the epoxide containing a functional group per mole of the silicon tetrahalide. As used herein, the term "epoxide equivalent" refers to the number of moles of the epoxide divided by the number of epoxide groups per molecule. Thus, this reaction may be illustrated by the following: ##EQU12## wherein X represents halogen, R.sub.4 is hydrogen or C.sub.1 to C.sub.4 alkyl (e.g., methyl, ethyl, propyl, etc.), and R.sub.5 is hydrogen or C.sub.1 to C.sub.4 alkyl, and preferably hydrogen, a represents the epoxide equivalent of the alkylene oxide and b represents the epoxide equivalent of the epoxide containing a functional group ##EQU13##

In actual practice, the reaction product produced is a mixture of compounds which can be utilized as such without the need to separate specific compounds contained in the reaction product.

However, compounds contained in the reaction mixture can be, if desired, separated from the mixture by known techniques, such as fractional distillation, liquid chromatography, etc., to yield the substantially pure compounds. Such compounds frequently depend upon the epoxide equivalents employed, that is, the values of a and b. For example, when the reaction mixture contains about 2 to 3 epoxide equivalents of the alkylene oxide and about 1 to 2 epoxide equivalents of the epoxide containing the functional group, the reaction product includes the following compounds: ##EQU14## wherein X is an integer from 2 to 3 and y is an integer from 1 to 2, and ##EQU15## wherein x is 3 and y is 1 and where X, R.sub.3 and R.sub.4 are as described above, as well as the corresponding derivatives where the epoxide is a cyclohexane epoxide.

Where the epoxide containing the functional group includes two or more epoxide groups, it is generally preferred that the equivalents of the alkylene oxide a be at least 2.2 and preferably at least 2.5 to avoid polymer formation which leads to gelling of the reaction product.

In preparing the reaction mixtures of the present invention, the reactants are contacted in the liquid phase. An inert organic solvent can be employed, if desired, but is not essential to the practice of the invention. The reaction temperature is not critical as the reaction generally takes place spontaneously and evolves heat. Best results are usually achieved when the reaction temperature is maintained below 100.degree.C, such as within the range of 0.degree. to 100.degree.C.

Where the epoxide containing the functional group as described above contains two or more epoxide groups, it is frequently preferred that the alkylene oxide be added to the halosilane prior to the time that the diepoxide is added to the reaction mixture. This procedure has the advantage that the reaction of alkylene oxide with the silicon tetrahalide is quite exothermic and thus raises the temperature of the reaction medium to a level suitable for addition of the epoxide containing the functional grouping.

Where the epoxide containing the functional group is a monoepoxide, the alkylene oxide or the monoepoxide can be added to the reaction mixture before the other, or they may be added simultaneously.

Where the reaction mixture contains two or more equivalents of an epoxide containing two or more epoxide groups per molecule, the reaction product includes compounds in which one of the epoxide groups in the functional epoxide remains unreacted with the silicon tetrahalide. For example, when the functional epoxide is one of those defined by 2 above, the reaction product includes compounds ##EQU16## where R.sub.3, R.sub.4 and X are as described above.

In accordance with yet another embodiment of the invention, the halosilane employed in the reaction can contain one or more organo groups attached directly to the silicon atom through a carbon-to-silicon bond. In the preferred practice of this embodiment of the invention, the halosilane is of the formula

wherein R.sub.7 is an organic group containing 1 to 20 carbon atoms, n is an integer from 1 to 2 and X is halogen and preferably chlorine or bromine.

R.sub.7 is preferably alkyl containing 1 to 20, and preferably 1 to 6 carbon atoms (e.g., methyl, ethyl, propyl, isopropyl, lauryl, etc.); alkenyl containing 2 to 20 and preferably 2 to 6 carbon atoms (e.g., vinyl, allyl, 3-butenyl, 4-pentenyl, etc.), cycloalkyl, such as cyclopentyl, cyclohexyl, etc., phenyl, as well as substituted derivatives thereof.

Where the organo halosilanes described above are reacted with an alkylene oxide and an epoxide containing a functional group as described above, it is preferred to employ from 1 to 2.5 epoxide equivalents or moles of the alkylene oxide per mole of the halosilane and from 0.5 to 3 epoxide equivalents of the epoxide containing the functional group per mole of the halosilane. Where the latter epoxide contains two epoxide groups and n = 1, it is desirable to employ at least 1.2 and perferably at least 1.5 epoxide equivalents of the alkylene oxide to minimize gel formation.

As is the case in the embodiments described above, the reaction product is usually in the form of a mixture of compounds. However, compounds which can be separated from the reaction products include: ##EQU17## where R.sub.7, R.sub.4, R.sub.2 and X are as described above and e is an integer from 1 to 2, and f is an integer from 1 to 2, with the total of e and f being equal to 3 where n is 1, and to 2 where n is 2; ##EQU18## and/or ##EQU19##

If desired, in the practice of this embodiment of the invention, the reaction can be carried out using a monoepoxide containing a functional group alone. This reaction frequently produces specific compounds but can also result in mixtures. Compounds produced include the following types: ##EQU20##

Representative of specific compounds include the following: ##EQU21## (CH.sub.2 =CHSiCl.sub.3 1 mole; allyl glycidyl ether 3 epoxide equivalents) ##EQU22## (CH.sub.2 =CHSiCl.sub.3 1 mole; glycidyl acrylate 3 epoxide equivalents)

In accordance with one embodiment of copending application Ser. No. 347,241, the organo silicon compounds are prepared by reaction of from 1 to 3 epoxide equivalents of the monoepoxide and at least 0.5 and up to 3 epoxide equivalents of another epoxide containing a functional group per mole of the silicon tetrahalide. As used herein, the term "epoxide equivalent" refers to the number of moles of the epoxide times by the number of epoxide groups per molecule.

For example, use can be made of a monoepoxide containing another functional group and a diepoxide as described above. This reaction can be illustrated by way of the following equations: ##EQU23## wherein X represents halogen, a represents the epoxide equivalent of the monoepoxide and b represents the epoxide equivalent of the diepoxide. In actual practice, the reaction product produced is a mixture of compounds which can be utilized as such without the need to separate specific compounds contained in the reaction product.

However, compounds contained in the reaction mixture can be, if desired, separated from the mixture by known techniques such as fractional distillation, liquid chromatography, etc., to yeild substantially pure compounds.

It has been found that in the reaction mixture, a should be at least 2.2, and preferably at least 2.5, to avoid polymer formation which causes gelling of the product. Thus, a is within the range of 2.2 to 3.5 and b is within the range of 0.5 to 1.8. It has also been found that where the reaction mixture contains 2 or more epoxide equivalents of the diepoxide, the compounds which predominate in the reaction mixture have the general formula ##EQU24## wherein c is within the range of 2.0 to 3 and d is within the range of 1 to 2.0. Most frequently, c is 3 and d is 1.

Where, however, use is made of less than 2 epoxide equivalents of the diepoxide, and epoxide equivalents used total 4, the product of the reaction includes compounds containing no free epoxy groups; these compounds have the general formula ##EQU25## if a = 3 and b = 1/2 (e.g., 36).

It will be observed that in all of the compounds specifically described above, each bond to the silicon atom contains a beta-haloalkoxy group. As indicated above, it is believed that such groupings impart improved stability to the compounds.

In accordance with another concept of the present invention, the reaction is carried out with 0.5 to 2.5 moles of an alkylene oxide in addition to 0.5 to 2.5 epoxide equivalents of monoepoxide and the diepoxide. In this embodiment of the invention, the alkylene oxide reacts with the halosilane in a similar manner to form a beta-haloalkoxy group attached directly to the silicon atom. This reaction can proceed in two ways, depending upon the amount of diepoxide employed. Thus, where the amount of the diepoxide is less than two epoxide equivalents, the reaction proceeds as follows: ##EQU26## where e and g are each integers from 1 to 2 and f is 1, and R is hydrogen or C.sub.1 to C.sub.6 alkyl (e.g., methyl, ethyl, propyl, etc.).

As with the embodiment described above, the reaction product of the above is a mixture which can be used as such or, if desired, the predominant compounds having the formula stated above can be separated from the reaction mixture.

Another group of compounds which can be employed in the practice of the invention include compounds prepared by reaction of substantially stoichiometric amounts of a silicon tetrahalide and an epoxide (9) as described above, preferably an epoxide containing ethylenic unsaturation. Preferred epoxides are those of the formula ##EQU27## where R.sub.8 is C.sub.2 to C.sub.8 alkenyl (e.g. alkyl, vinyl, etc.) or a group ##EQU28## wherein R' is as described above.

These compounds have the formula ##EQU29## Representative compounds include the following ##EQU30##

The combination of the acrylate silane and the beta-haloalkoxy organo silicon compounds is formulated into a size composition for application to the glass fibers. The size composition is formulated with a solvent or diluent such as an inert organic solvent or with water. For reasons of economy, water is frequently preferred but volatile organic solvents may also be employed if desired; suitable solvents include aliphatic aldehydes, aliphatic ketones, alcohols, etc.

The relative proportions of the acrylate silane and the beta-haloalkoxy organo silicon compound can be varied within fairly wide ranges. Best results are usually obtained when the acrylate solvent constitutes from 0.05 to 2% by weight of the size composition and the beta-haloalkoxy constitutes 0.5 to 3% by weight of the size composition. It has been found that the weight ratio of the acrylate silane to the beta-haloalkoxy organo silicon compound is within the range of 0.05 to 1, and preferably 0.1 to 0.7. Since the acrylate silane is the more expensive component, the amount of the beta-haloalkoxy organo compound usually exceeds the amount of the acrylate silane on a weight basis.

While it is not essential to the practice of the invention, it is frequently preferred to formulate the size composition to include a film-forming material. A variety of film-forming materials can be used for this purpose, including polyester resins, polyamide resins, polyolefin resins (e.g., polyethylene, polypropylene, etc.), polyepoxide resins, vinyl resins (e.g., polyvinyl chloride, polyvinyl acetate, polyvinyl alcohol, polyvinyl pyrrolidone, etc.), waxes, polybutadienes, partially dextrinized starches and others. Such film forming materials are themselves well known to those skilled in the art and are described in U.S. Pat. Nos. 2,931,739, 2,958,114, 3,040,413, 3,252,278, 3,424,608. Combinations of two or more of such film-forming materials can also be used.

The size composition employed in the practice of this invention can also be formulated to include any of a variety of wetting agents, glass fiber lubricants, etc., also well known to the art.

The resulting size composition can be used in the treatment of glass fibers for use as reinforcement of thermosetting resins as well as elastomeric materials in accordance with conventional techniques. It has been found that the combination of the acrylate silanes and the beta-haloalkoxy organo silicon compounds containing ethylenic unsaturation are particularly well suited for use as a size for glass fibers for reinforcement of polyester resins.

While not equivalent to the acrylate silanes described above, other conventional organo silanes can be used in combination with the beta-haloalkoxy organo silicon compounds in the preparation of size compositions. Such silanes include alkenyl silanes of the formula

wherein a is 0 or an integer from 1 to 3, and R.sub.1 is as described above.

Also suitable are glycidoxy alkyl silanes of the formula ##EQU31## wherein x and R.sub.1 are as described above, and amino silanes of the formula

wherein b is an integer from 3 to 6. Representative examples include vinyltriethoxy silane, glycidoxypropyltrimethoxy silane and aminopropyltrimethoxy silane.

Having described the basic concepts of the invention, reference is now made to the following examples which are provided by way of illustration and not by way of limitation of the practice of the invention in the formulation of size compositions and the use of such compositions in the treatment of glass fibers.

An organo silane is prepared by SiCl.sub. 127.4 g (0.75 mole) of CiCl.sub.4 in a reaction flask, and then adding 87.1 g (1.5 mole) of propylene oxide and 171.1 g (1.5 mole) of allyl glycidyl ether. The product of the reaction is found to be a mixture which includes the compound ##EQU32##

Using the procedure outlined in Example 1, one mole of SiCl.sub.4 is reacted with 3 moles of propylene oxide and 1 epoxide equivalent of DER 332. The product is a mixture which contains the compound ##SPC5##

One mole of SiCl.sub.4 is reacted sequentially with 2.5 moles of propylene oxide, 0.5 mole of allyl glycidyl ether and 1 epoxide equivalent of DER 332. The product is a mixture which includes the compound ##SPC6##

One mole of SiCl.sub.4 is reacted with 2 moles of propylene oxide and 2 moles of glycidyl acrylate. The reaction mixture produced is found to contain the compound ##EQU33##

One mole of SiCl.sub.4 is reacted with 2.5 moles of propylene oxide, and the product is reacted with 0.5 moles of Epoxide No. 7 and 1.0 epoxy equivalent of ERE 1359. The product is a mixture which contains the compound ##SPC7##

One mole of SiCl.sub.4 is reacted with 3 moles of propylene oxide and 1 mole of glycidyl acrylate. The product, a mixture, contains the compound ##EQU34##

Using the procedure of Example 1, 1 mole of SiCl.sub.4 is reacted with 2 moles of propylene oxide, 1 mole of glycidyl methacrylate and 1 epoxy equivalent of ERE 1359. The product includes ##SPC8##

One mole of SiCl.sub.4 is reacted with 2 moles of propylene oxide, 1 mole of glycidyl methacrylate and 1 epoxy equivalent of DER 332. The mixture forming the product includes the compound ##SPC9##

One mole of SiCl.sub.4 is reacted with 2 moles of propylene oxide, 1 mole of glycidyl acrylate and 1 epoxy equivalent of ERE 1359. The mixture resulting includes the compound ##SPC10##

One mole of SiCl.sub.4 is reacted with 2 moles of propylene oxide, 1 mole of allyl glycidyl ether and 1 epoxide equivalent of ERE 1359. The mixture produced includes the compound ##SPC11##

One mole of SiCl.sub.4 is reacted with 2 moles of propylene oxide, 1 mole of glycidyl acrylate and 1 epoxy equivalent of DER 332. The product includes the compound ##SPC12##

One mole of SiCl.sub.4 is reacted with 2 moles of propylene oxide, 1 mole of glycidyl acrylate and 1 epoxide equivalent of ERL 4206. The mixture forming the product includes the compound ##SPC13##

One mole of SiCl.sub.4 is reacted with 2 moles of propylene oxide, 1 mole of allyl glycidyl ether and 1 epoxy equivalent of ERL 4206. The product includes ##SPC14##

In the preparation of each of the foregoing beta-haloalkoxy compounds, the reactants are added sequentially to the SiCl.sub.4 in the order indicated in each of the examples.

Each of the foregoing reaction products of Examples 1-13 is then tested in a size composition in combination with gammamethacryloxypropyltrimethoxy silane (A-174 from Union Carbide). The size compositions were each formulated in accordance with the following

Each of the size compositions is applied to glass fibers as they are formed, and the coated glass fibers are dried at 265.degree.F for 16 hours. The glass fibers coated (in the form of slivers) are then employed as reinforcement in standard polyester test rods. The rods are then tested to determine their flex strength, in a dry state and after having been contacted with boiling water for 4 hours. A control size is also used in the same manner; the control size is formulated as follows:

The results of these tests are shown in the following table.

As shown by the above data, the use of .beta.-haloalkoxy compounds in combination with A-174 is at least equal to the use of A-174 alone and generally superior in bonding glass fibers to polyester resins.

A series of size compositions are formulated in accordance with the following two recipes:

The polyepoxide-amine resins are fiber-forming resins and are described in U.S. Pat. No. 3,169,884.

The size compositions are applied to glass fibers in the form of slivers which are then dried at 235.degree.F for 10 hours. The coated fibers are then tested as reinforcement for a polyester resin as described in Example 14.

The results of the flex tests are shwon in the following table.

Using the procedure described in Example 1, one mole of vinyl trichlorosilane is reacted with 2 moles of propylene oxide and 1 mole of glycidyl methacrylate. The product of the reaction is found to contain the compound ##EQU35##

The reaction product is formulated into the following size composition:

The above composition can be applied to glass fibers to form a coating thereon as described above; the fibers are well suited for use as reinforcement for thermosetting resins.

It has been found that .beta.-haloalkoxy organo silicon compounds described in the foregoing copending applications which contain free epoxy groups are preferably formulated with epoxy silanes. The concept is illustrated by the following example.

One mole of SiCl.sub.4 is reacted sequentially with 3 epoxide equivalents of propylene oxide and then 2 epoxide equivalents of ERE 1359. The product is a mixture which includes the compound ##SPC15##

The reaction product is formulated into the following size composition:

The above composition can be used to size glass fibers for use as reinforcement for epoxy resins.

In a similar manner, the .beta.-haloalkoxy compounds described in Examples 1 to 13, 15 and 16 can also be formulated with vinyl silanes and amino silanes for use as reinforcement for both resins and elastomeric materials.

In the final reinforcement resin, the thermosetting resin constitutes a continuous phase in which the coated glass fiber reinforcements are distributed. The glass fibers can be in the form of chopped fibers, woven or non-woven mats, slivers, strands, etc. The coating on the glass fiber surfaces operates to establish a secure bonding relationship between the glass fibers and the resin.

It will be understood that various changes and modifications can be made in the details of procedure, formulation and use without departing from the spirit of the invention, especially as defined in the following claims.