SIZE COMPOSITION

Abstract: Size compositions based on bis silane are disclosed. The bis silane sizes are useful for glass fiber reinforcements useful in filament winding and pultrusion. The size is particularly useful for vinyl ester resins for filament wound pipe.

Description: ' DESCRIPTION SIZE COMPOSITION TECHNICAL FIELD The present invention relates to glass fibers and more particularly it relates to sizing compositions for glass fibers. Even more particularly, the invention relates to size compositions for continuous glass fibers useful for the reinforcement of plastics. BACKGROUND ART As is well known in the art, glass fibers which are intended for use as reinforcements usually require a size. This size is applied during the fiber forming process. That is, the glass fibers are sized with a protective material substantially immediately after they are formed. The sized glass fibers then are gathered into a bundle and the bundles are wound onto a forming package. The continuous glass fibers then are used in various processes such as pultrusion or filament winding. Sizing compositions need to provide a lubricating quality to the individual filaments to provide them with abrasion resistance. Additionally, the sizing composition must provide the fibers with an outer film which is compatible with the resin they will reinforce. In the manufacture of composite articles such as pipes, cases, reaction vessels, cones, tubes and bottles, conventional practice impregnates continuous filaments with a resin, forms the impregnated continuous filaments into a shaped article, and then cures the resin to form the composite. Common processes for making composites are filament winding and pultrusion. Filament winding is a process in which continuous filaments are impregnated with a resin, wound onto a mandrel to build the desired shape and thickness, and cured. By "mandrel" is meant a tool used in filament winding on which bands of fibers are deposited into filamentary patterns to form layers. Upon curing of the resin, the composite so shaped is removed from the mandrel and applied to its intended use. The pultrusion process generally consists of pulling continuous filaments through a resin bath or impregnator and then into preforming fixtures (dies) in which a section of continuous filament impregnated with resin is partially shaped and excess resin and/or air are removed. Then the section is pulled through in heated dies in which it is cured. The industry continues to want the composites to have a longer working life, i.e., improved fatigue life such as cyclic fatigue in which the composites are subjected to repetitive loading cycles. These composites also need to sustain high working pressures, i.e., increased pressures at which the composite fail. DISCLOSURE OF THE INVENTION We now have discovered an improved size composition for glass fiber reinforcements useful in filament winding and pultrusion. We have found the size particularly useful for vinyl ester resins for filament winding for making pipe. The key to our size is its bis silane ingredient. The size improves toughness and consequently the cyclic (bursting) performance of the pipe. DETAILED DESCRIPTION OF THE INVENTION The bis silanes we use are represented by the formula: (R) 3 Si - R 1 - Si(R) 3 wherein R is an alkyl or alkoxy radical having 1 to 10 carbon atoms and R 1 is an alkylene radical having 1 to 10 carbon atoms. Preferably R is an alkyl or alkoxy radical having 1 to 5 carbon atoms and R 1 is an alkylene radical having 1 to 5 carbon atoms. The preferred bis silane is 1 -(triethoxy silyl)-2-(methyldiethoxy silyDethane represented by the formula: (CH 3 CH 2 O) 3 SiCH 2 CH 2 Si(CH 3 )(OCH 2 CH 3 ) 2 Another bis silane we found useful is 1 ,2-bis(trimethoxy silyl) ethane represented by the formula: (CH 3 O) 3 SiCH 2 CH 2 Si(OCH 3 ) 3 As the preferred bis silane shows, each R radical may be different. The size composition also contains epoxy (film forming epoxies), other silanes, lubricants, wetting agents and the like. As used herein the term film forming epoxy, or epoxy is a diglycidyl ether of bisphenol A. The term also includes suitable surfactants or emulsifiers. It is best, to employ commercially available film forming epoxy materials, and to also first form these epoxy materials into an emulsion for subsequent combination with the other ingredients of the size composition. The epoxy materials used in the size composition are diglycidyl ethers of bisphenol A, and are commercially available under such trade designations as AD 502 and NEOXIL 962. Such diglycidyl ethers have terminal unreacted epoxy groups and are generally of the formula: Preferred ethers are low molecular weight materials in which n is value between about 0.2 to about 0.34. These epoxy materials typically have epoxide equivalent weights of less than about 600 and suitably about 540 to about 170. In the preferred embodiment of this invention, we employ two epoxy emulsions. While any methylacryloxysilane may be employed, the preferred material is gamma-methacryloxypropyltrimethoxysilane such as that commercially available under the trade designation A-174. We can employ a wide variety of lubricants, but prefer a silicone lubricant. The wetting agent, an acid and water make up the balance of the size composition. We apply the size compositions in an acidic aqueous emulsion form. The preferred acid for pH adjustment is acetic acid. The above ingredients will constitute about 5 to about 10 percent by weight of the final applied size emulsion, with the balance being the acid and water. In the present invention at least one continuous filament is coated with a resin. The resin is selected from the group consisting of an unsaturated polyester, a vinyl ester, and mixtures thereof with vinyl ester being preferred. Vinyl ester resins which we employ are well known and are disclosed in U.S. Patent Nos. 3,367,992; 3,066,1 12; 3,179,623; 4,673,706 and 5,015,701 . Typically, vinyl ester resins are thermosetting resins what consist of a polymer backbone (B) with an acrylate (R = H) or methacrylate (R = CH 3 ) termination, schematically represented by the following: H 2 C = C(R)-C(O)-O-B-O-C(O)-C(R) = CH 2 The backbone component of vinyl ester resin can be derived from a variety of well known resins such as, for example, an epoxide resin, polyester resin, or a urethane resin. Those based on epoxide resins are widely used commercially and, hence, are especially preferred in the process of the present invention. Vinyl ester resins employed in the process of the present invention are well known and are generally prepared by reacting at least equivalent proportions of a polyepoxide resin and an unsaturated monocarboxylic acid wherein -C(O)-O-CH 2 -CH(OH)-CH 2 -O- linkages are formed and the resulting resin has terminal, polymerizable unsaturated groups. Examples of suitable vinyl ester resins include, for example, 8303 from Interplastics Corporation (Vadnais Heights, Minnesota) and Hetron ® 925 from Ashland Chemical Co. (Ashland, OH). Unsaturated polyester resins which can be employed are well known in the art. In general, polyester resins are prepared by condensing an ethylenically unsaturated dicarboxylic acid or anhydride or mixtures thereof with a dihydric alcohol or mixtures of dihydric alcohols. Continuous filaments or fibers which are employed in the process of the present invention are well known in the art. Filament means a single filament or fiber, and a multiplicity of fibers is known as a strand. The preferred glass fiber composition is selected from the group consisting of E-type, S-type, A-type and C-type. Most preferably the glass fiber is E- or S-type. The glass fiber used in this invention preferably have tensile strengths of approximately 2.9 to 4.4 GPa and Young's modulus of approximately 70 to 87 GPa. Glass fiber for use in the present invention is available as roving in yields from 675 to 1 13 yards per pound with fiber diameters from 6 to 25 micrometers, and preferably with a fiber diameter of 12 to 20 micrometers, and most preferably with a fiber diameter of 14 to 18 micrometers. Glass fibers are conventionally manufactured by discharging a plurality of molten glass streams from a heated bushing, attenuating the plurality of glass streams into a plurality of fibers and passing the fibers through an applicator to apply the aqueous based size to the fibers. Afterwards the fibers are gathered into a strand at a gathering shoe and wound on a collet to produce a glass fiber package. The package is dried to evaporate the water from the aqueous-based size. The in-line drying process of U.S. Patent No. 5,055, 1 19 is an energy efficient process for forming glass fiber packages which are free of migration. In the in-line drying process air from around the fiber forming bushing passes beneath the bushing whereby it is heated by bushing heat and the heated air is then drawn into a chamber through which the glass fibers pass in heat transfer contact with the heated air. The heat transfer causes the water or solvent in the applied size to be evaporated and results in a migration free glass fiber package. BEST MODE OF CARRYING OUT INVENTION The amount of each ingredient in the size is not critical. Typically, the size contains standard amounts of each ingredient on a percent by weight basis. Usually, these amounts are: Ingredient Percent bv Weight as Received Epoxy Film Former 5.0 to 10.0 Methylacryloxysilane 1.0 to 3.0 Bis-Silane 0.2 to 1.0 Lubricant 0 to 1.0 Wetting Agent 0 to 0.5 Acid 0 to 0.5 Deionized Water balance Preferably, these amounts are: Ingredient Percent bv Weight as Received Epoxy 5.0 to 7.5 Silane 1.0 to 2.0 Bis-Silane 0.3 to 0.8 Lubricant 0 to 0.7 Wetting Agent 0 to 0.3 Acid 0 to 0.3 Deionized Water Balance This size is an aqueous based size containing up to 10% solids with the balance being water. Example I The following size formulation was prepared for vinyl ester filament winding. In line drying was used in sizing the glass fibers. Size Formulation % by wt as received AD-502 (epoxy emulsion) 4.26 NEOXIL 962 (epoxy emulsion) 2.00 A-174 silane 1 .68 Y-1 1620 (bis-silane) 0.55 SM-2154 (silicone lubricant) 0.50 SILWET L-77 (wetting agent) 0.10 Acetic acid 0.20 Deionized water balance The size was an aqueous based size containing about 95% water and about 5% solids. We applied the size to E glass fiber strands. The strands were prepared according to the method described in Example I of U.S. Patent No. 5,055,1 19. The results are set forth in Table 1. From Table 1 , it can be seen that the size of this invention significantly improves fatigue life and hoop stress of a composite article. The test samples were the same except for the size employed. The sample contained about 70% glass and about 30% vinyl ester resin. Table 1. FATIGUE LIFE OF A CONTINUOUS GLASS FIBER REINFORCED VINYL ESTER PIPE CONTAINING BIS SILANE SIZED GLASS FIBER STRANDS Cycles to Failure Pressure, MPa (psi) Control Size of Ex I 8.27 (1200) 875 1337 12.41 (1800) 79 164 mwt*, mm 1.20 1.16 *mwt = minimum wall thickness, mm Cycles to Failure at 131 MPa (19,000 psi) Hoop Stress Control Size of Ex 1 24,681 40,312 Burst Strength Control Size of Ex 1 Hoop Stress, psi 72,228 83,875 Industrial Applicability The filament wound pipes were fabricated by passing the glass fiber strand through a resin bath containing a thermosetting resin, styrene and a strain relieving polymer in amounts designated in the tables. Fibers so impregnated were wound onto a mandrel to form a tube or pipe and placed in an oven at room temperature. The oven was heated to 82.2°C (180°F) in 6 minutes. The temperature of the oven was then raised to 148.9°C (300°F) in about 15 minutes and the mandrels with pipe were heated at that temperature for 15 minutes. The oven was allowed to cool to room temperature before the pipes were removed from the oven and separated from the mandrel. After the pipe was dislodged from the mandrel, it was cut into 61 cm segments each having a diameter of 57 mm. The wall thickness was measured for each pipe, and it was approximately 1.27 mm thick. Fatigue life of the pipe or tube was tested according to ASTM D-2143. Each pipe section was fitted on the outside of the pipe with three electrical detectors to sense the presence of water. The pipes were filled with water and mounted on a cyclic fatigue tester. The number of cycles for water to penetrate to the outer wall of the pipe was measured by each detector. After all the detectors failed, an average number of cycles was taken for each pipe section. Pipe sections were tested at different pressures. The pipe section's minimum wall thickness was determined according to ASTM D-2992. The pressures, minimum pipe wall thicknesses and pipe diameters were used to calculate hoop stress according to the following equation: Hoop Stress = Pressure x Pipe Diameter 2 x Pipe Wall Thickness The hoop stress is defined as the tensile stress in the wall of the piping product in the circumferential direction due to internal pressure. The linear regression of the logarithm of the hoop stress versus the logarithm of number of cycles was used to calculate the number of cycles to weep at a hoop stress of 131 MPa (19,000 psi), a commonly accepted method for reporting fatigue life in the art of continuous fiber reinforced pipe.

Claims: CLAIMS: 1. An aqueous size composition useful for coating glass fibers, wherein the coated glass fibers are useful in a filament winding process, the size composition comprising: at least one bis silane represented by the formula: (R) 3 SI - R 1 - SI(R) 3 wherein R is an alkyl or alkoxy radical having 1 to 10 carbon atoms and R 1 is an alkylene radical having 1 to 10 carbon atoms; at least one epoly film former; and at least one methylacryloxysilane. 2. A size composition according to claim 1 wherein , in the bis silane formula, R is an alkyl or alkoxy radical having 1 to 5 carbon atoms and R 1 is an alkylene radical having 1 to 5 carbon atoms. 3. A size composition according to claim 1 wherein the bis silane is 1-(triethoxy silyl)-2-(methyldiethoxy silyDethane represented by the formula: (CH 3 CH 2 O) 3 SiCH 2 CH 2 Si(CH 3 )(OCH 2 CH 3 ) 2 4. A size composition according to claim 1 wherein the bis silane is 1 ,2-bis(trimethoxy silyl) ethane represented by the formula: (CH 3 O) 3 SiCH 2 CH 2 Si(OCH 3 ) 3 5. A size composition according to claim 1 wherein the epoxy film former is an epoxy emulsion of diglycidyl ethers of bisphenol A. 6. A size composition according to claim 1 wherein the methylacryloxysilane is gamma methacryloxypropyltrimethoxysilane. 7. A size composition according to claim 1 wherein the composition has a solids content of 5 to 10 percent by weight. 8. A size composition according to claim 1 including a silicone lubricant, a wetting agent, an acid and water. 9. An aqueous size composition useful for coating glass fibers, wherein the coated glass fibers are useful in a filament winding process, the size composition comprising: 1 -(triethoxy silyl)-2- (methyldiethoxy silyDethane represented by the formula: (CH 3 CH 2 O) 3 SiCH 2 CH 2 Si(CH 3 )(OCH 2 CH 3 ) 2 ; two epoxy emulsions of diglycidyl ether of bisphenol A; and gamma methacryloxypropyltrimethoxysilane. 10. A size composition according to claim 1 including a silicone lubricant, a wetting agent, an acid and water. 1 1. Glass fibers coated with the dried residue of an aqueous size composition comprising at least one bis silane represented by the formula: (R) 3 Si - R 1 - Si(R) 3 wherein R is an alkyl or alkoxy radical having 1 to 10 carbon atoms and R 1 is an alkylene radical having 1 to 10 carbon atoms; at least one epoxy film former; and at least one methylacryloxysilane. 12. Coated glass fibers according to claim 1 1 wherein, in the bis silane formula, R is an alkyl or alkoxy radical having 1 to 5 carbon atoms and R 1 is an alkylene radical having 1 to 5 carbon atoms. 13. Coated glass fibers according to claim 1 1 wherein the bis silane is 1 -(triethoxy silyl)-2-(methyldiethoxy silyDethane represented by the formula: (CH 3 CH 2 O) 3 SiCH 2 Si(CH 3 )(OCH 2 CH 3 ) 2 14. Coated glass fibers according to claim 1 1 wherein the bis silane is 1 ,2-bis(trimethoxy silyl) ethane represented by the formula: (CH 3 O) 3 SiCH 2 CH 2 Si(OCH 3 ) 3 1 5. Glass fibers coated with the dried residue of an aqueous size composition comprising: 1 -(triethoxy silyl)-2-(methyldiethoxy silyDethane represented by the formula: (CH 3 CH 2 O) 3 SiCH 2 CH 2 Si(CH 3 )(OCH 2 CH 3 ) 2 ; two epoxy emulsions of diglycidyl ether of bisphenol A; and gamma methacryloxypropyltrimethoxysilane. 1 6. Glass fiber reinforced products wherein the glass fibers are glass fibers coated with the dried residue of an aqueous size composition comprising: at least one bis silane represented by the formula: (R) 3 Si - R 1 - Si(R) 3 wherein R is an alkyl or alkoxy radical having 1 to 10 carbon atoms and R 1 is an alkylene radical having 1 to 10 carbon atoms; at least one epoxy film former; and at least one methylacryloxysilane. 17. Reinforced products according to claim 1 6 wherein, in the bis silane formula, R is an alkyl or alkoxy radical having 1 to 5 carbon atoms and R 1 is an alkylene radical having 1 to 5 carbon atoms. 18. Reinforced products according to claim 16 wherein the bis silane is 1 -(triethoxy silyl)-2-(methyldiethoxy silyDethane represented by the formula: (CH 3 CH 2 O) 3 SiCH 2 CH 2 Si(CH 3 )(OCH 2 CH 3 ) 2 19. Glass fiber reinforced products wherein the glass fibers are glass fibers coated with the dried residue of an aqueous size composition comprising: 1 -(triethoxy silyl)-2-(methyldiethoxy silyDethane represented by the formula: (CH 3 CH 2 O) 3 SiCH 2 CH 2 Si(CH 3 )(OCH 2 CH 3 ) 2 ; two epoxy emulsions of diglycicyl ether of bisphenol A; and gamma methacryloxypropyltrimethoxysilane. 20. Reinforced products according to claim 16 wherein the products are filament wound or pultrusion products. 21. Reinforced products according to claim 16 wherein the products are filament wound vinyl ester resins. 22. Reinforced products according to claim 19 wherein the products are filament wound vinyl ester resin pipe products.

Inventors: ADZIMA LEONARD J, FLAUTT MARTIN C, ADZIMA, LEONARD, J., FLAUTT, MARTIN, C.
Applicants: OWENS CORNING FIBERGLASS CORP, OWENS-CORNING FIBERGLAS CORPORATION
Application year: 1993
Main classification: C03C25
IPC codes: C03C25, C07F7, C08J5, C08K7, C08K9