Process for the preparation of reinforced plastics based on a resorcinol-modified phenolic resin

Abstract: A fire resistant resin for use as a binder in reinforced plastics and a resultant reinforced plastic includes the reaction product of (a) at least one resorcinol component selected from the group consisting of resorcinol and resorcinol formaldehyde novolak resin, and (b) a phenolic resole resin. The reaction may be achieved in the presence of an alkaline catalyst. A method of making a fire resistant resin binder for reinforced plastics and the method of making such reinforced plastics including, (a) at least one resorcinol component selected from the group consisting of resorcinol and resorcinol formaldehyde novolak resin, and (b) a phenolic resole resin. The reaction may be achieved in the presence of an alkaline catalyst.

Description: This invention relates to the manufacture of articles from reinforced plastics materials, and to the use of fire resistant resin binders therein. It is known to employ reinforced plastic materials such as fibreglass, for example, in a wide variety of environments including building products, means of transportation, such as automobiles, planes and boats, as well as many other uses such as air ducts, panels, doors and electrical conduits. The reinforcing material serves to enhance the strength of the plastic materials, and the binders secure the material in the desired positions. A wide variety of reinforcing materials have been employed, including for example materials such as carbon fibres, glass fibres and flakes, glass or ceramic microspheres and a wide variety of synthetic materials in various forms including continuous fibre and chopped fibre. Among the important considerations in choosing resin binders for such purposes are the desire to have effective resistance to both flame and smoke development, as well as maintaining the desired mechanical properties at elevated temperatures. It has been known to employ a condensation product of resorcinol and formaldehyde resins in combination with cement in such resins - see U.S. Patent No. 3,663,720 and also U.S. Patent No. 3,502,610. Building codes and regulatory agencies specify such low smoke density values for thermosetting and thermoplastic materials that, due to economic considerations, only a limited number of materials can be employed. Further, increasingly tight restrictions have been imposed on emissions of styrene, a chemical generally deemed necessary in the industry, because styrene is currently under investigation as being a possible carcinogen. While phenolic resins have been suggested as a safe alternative for fire retardant applications, one of the impediments to growth in the use of such composites is the reluctance of fabricators to have the required acid catalyst present in the workshop environment. A serious problem with most fire-retardant resins is smoke emission. It is currently believed that a high percentage of fatalities are caused by smoke inhalation. Most fire retardant, reinforced plastics materials tend to emit dense clouds of toxic and acutely irritating smoke and gases which can cause death or lung damage as a result of inhalation. They also can obstruct vision, thereby interfering with escape to safety and efforts of fire fighters. Further, damage to facilities including delicate electronic equipment can occur. Most phenolic laminating resins rely upon acid catalysts or high temperature post-curing or both. As formaldehyde has recently been classified as a carcinogen, one must carefully evaluate the level of paraformaldehyde disclosed in the prior art. It is important to reduce the exposure of the laminating worker to formaldehyde emissions. U.S. Patent No. 4,403,066 discloses the use of liquid phenol-formaldehyde resoles in reinforced composites such as those reinforced by glass fibre. One of the difficulties with the system taught in this patent is that it requires curing of the resin at an elevated temperature, such as at about 80° to 150°C, and it requires strongly acidic or strongly alkaline conditions - see also U.S. Patent No. 4,433,129 which discloses hemi-formals of methylolated phenols including those made by reaction of paraformaldehyde with liquid phenol to produce the hemi-formals of methylolated phenols. U.S. Patent No. 4,433,119 discloses liquid compositions of a hemi-formal phenol or methylolated phenols with polymers such as phenol-formaldehyde resoles, phenol-formaldehyde novolaks, as well as other materials - see also U.S. Patent No. 4,430,473. U.S. Patent No. 4,053,447 discloses a resorcinol-modified phenolic resin which is said to be curable without the addition of heat, but requires the addition of paraformaldehyde powder to cure the resin mix. It has been known to use resorcinol modified phenolic resins in the manufacture of glue laminated wooden structural members. Adaptation of this technology to the manufacture of reinforced plastics has had limited success due to the relatively high level of non-reactive solvents formerly believed necessary to achieve low viscosity in conventional resin systems. The high solvent content of conventional "first generation resins" as well as the water formed in the phenolic condensation reaction contribute to crazing, porosity and poor corrosion resistance experienced in earlier resin systems. In the interrelated family of documents including DE OLS 2738267, US-A-4690692, US-A-4251408, DE ALS 2853761, US-A-4298356 and EP-A-0009519 there are disclosed resin binders (adhesives) for use in the preparation of abrasive materials, e.g. sand paper. The resin binders disclosed are aqueous mixtures of (a) a phenol resole resin and (b) a co-condensate of a monohydric phenol and a polyhydric phenol (e.g. resorcinol) with formaldehyde, in which the molar ratio of phenols (both monohydric and polyhydric) to formaldehyde is in the range 1:0.6 to 1:1.5. EP-A-0180257 discloses resin compositions for use as moulding compounds which comprise a resole resin, a thickener, glass fibre, fillers and if desired condensation catalysts and other additives, in which the thickener disclosed is a pre-condensate of resorcinol and formaldehyde. It is stated that the resorcinol-formaldehyde precondensate can have a resorcinol-formaldehyde ratio between 4:1 and 1.2:1, and that the amount used is from 2 to 20%, based on the weight of the resole. Such resin compositions acquire viscosity stability and therefore can be used as sheet moulding compounds, bulk moulding compounds or dough moulding compounds. A sheet moulding process employing a pressure of 100kg/cm 2 and a temperature of 160°C is outlined. In spite of the known prior art systems, there remains a real and substantial need for a laminating resin binder which will have the desired flame and smoke development resistant characteristics while being curable at room temperature and easy to manufacture and use. It is an object of the present invention to provide the use of a laminating resin binder in the manufacture of articles of reinforced plastics material, whereby there can be obtained a product which has excellent resistance to flame development and extremely low smoke development as well as excellent high temperature mechanical strength. It is a further object of the present invention to provide the use of a phenolic resin binder which is curable at room temperature within a reasonable time and at intermediate pH values, as well as with an acidic catalyst, if desired. It is a further object of the present invention to provide the use of a phenolic resin binder which eliminates the need to use paraformaldehyde as a curing agent, and thereby retains less water and other volatile solvents which can contribute to weakening of the composite plastic material, and reduces formaldehyde exposure. It is a further object of the present invention to provide the use of a resin binder which when exposed to flame not only facilitates lower level flame spread without requiring additives and lower levels of smoke emission, but provides less toxic smoke emissions. It is a further object of the present invention to provide the use of a resin binder which, when used in reinforced plastics, gives improved tensile and flexural properties. It is a further object of the present invention to provide the use of a resin binder which avoids the requirement that there be a strongly acidic or strongly alkaline condition for curing and thereby avoids this source of potential damage to the reinforcing material. These and other objects of the present invention will be more fully understood from the following description of the invention. According to one aspect of the present invention there is provided a process, not being a sheet moulding, bulk moulding or dough moulding process, for the manufacture of an article of fire resistant reinforced plastics material, which process comprises forming a resin binder by mixing (a) a resorcinol formaldehyde novolak resin produced by the reaction of from 58 to 71 parts by weight of resorcinol and from 4 to 7 parts by weight of formaldehyde and (b) a phenolic resole resin, intimately mixing the resin binder with a reinforcing material, and thereafter curing the intimate mixture of resin binder and reinforcing material to produce the desired fire resistant article. In a second aspect, the present invention provides, in a process according to the invention, the use of a two-part, liquid-liquid pre-catalysed resin binder system which system comprises (a) a resorcinol formaldehyde novolak resin produced by the reaction of from 58 to 71 parts by weight of resorcinol and from 4 to 7 parts by weight of formaldehyde and (b) a phenolic resole resin. The resin binder may include an inert filler as an extender, if desired, but a filler does not need to be employed in order to achieve the fire and smoke emission properties. The higher solids content, as compared with known systems, provide superior chemical resistance and lower porosity. Under the influence of flame contact or radiant heat, it resists flame and smoke development. Preferred resin binders of the present invention will have a pH in the range of from 6 to 10, and curing of a reinforced plastics material including a fire resistant resin binder of the present invention is preferably but not necessarily achieved at a moderate pH of the order of 6 to 10, and can advantageously be carried out in the presence of an alkaline catalyst. Any suitable alkaline catalyst may be used and may, for example, be selected from the group consisting of metal hydroxides, metal oxides and amines, such as sodium hydroxide, ammonium hydroxide and potassium hydroxide. A further advantage of the resin binders of the present invention over acid-catalyzed phenolic resins is that they will not corrode tooling and yet are not so alkaline as to damage the glass mat. Another of the advantages of preferred embodiments of the resin binder of the present invention is that they are curable to release at room temperature within a reasonable time period. Thus, for example, curing can be effected at 12.5°C to 35°C (55°F to 95°F), with a room temperature cure for about 8 to 14 hours being most advantageous. Generally, a resin binder of the present invention will be cured at temperatures in the range of from 16°C to 160°C over a period of from 20 hours to 0.06 hours. The resorcinol formaldehyde novolak resin may also include from 0.025 to 0.25 weight percent, preferably from 0.025 to 0.075 weight percent, of an organic acid solution such as, for example, p-toluene sulphonic acid or oxalic acid, in order to adjust the pH, or as a catalyst. Advantageously, the phenolic resole has from 40 to 71, preferably from 55 to 67, parts by weight phenol, and from 20 to 52, preferably from 35 to 43, parts by weight paraformaldehyde. One of the difficulties arising from the use of paraformaldehyde in the prior art systems was the use of powder which caused increased exposure of plant personnel to this potentially dangerous material. Among the advantages of the present invention are the faster reacting time as the paraformaldehyde must dissolve and at least partially dissociate into formaldehyde molecules before reaction with the phenolic. Also, the present system is easier to use as the hardening agent is in liquid form and requires less mixing. Further, the present system produces a better product as no solvent is required to dissolve the paraformaldehyde in order that it can react. In a preferred practice of the invention a further methylene donor is added to the binder in order to reduce the mix viscosity and thereby improve processing and wet out of the reinforcing material. It also serves to increase the cross-link density thereby providing added strength to the reinforced plastic. From 0.01 to 40 weight percent (based upon weight of the resin mix) and preferably from 12 to 21 weight percent of the methylene donor may be added to reaction mix. Any suitable methylene donor may be used: among the preferred materials are furfural, furfuryl alcohol, oxazolidine and acrolein as well as combinations thereof. In making an article of reinforced plastics material, the resin binder can be mixed with the reinforcing material material, such as a glass fibre, in a conventional manner. The mixture can then be cured at room temperature within 12 to 24 hours in order to achieve the desired bond between fibres and the plastic. It will be appreciated that the method of making the fire resistant resin binder of the present invention involves reacting (a) at least one resorcinol component selected from the group consisting of resorcinol and resorcinol formaldehyde novolak resin, and (b) a phenolic resole resin. The reaction may advantageously be effected in the presence of an alkaline catalyst and at room temperature. In employing the method to reinforce a plastic, the plastic material is intimately admixed with the binder and then may be cured with the addition of heat if desired to accelerate the action but may advantageously be cured at room temperature. In order to verify the technical characteristics of the present invention, a series of tests were performed. These tests are reported in the following examples. Examples 1 to 5 describe the preparation of the resole component and Examples 6 to 11 describe the preparation of the resorcinolic component. Examples 12 to 19 describe the preparation of the resin binder, its use in the process of the present invention, and the properties of the resulting reinforced plastic materials. Example 1 In this Example, 418.3 grams of a 90 percent solution of USP phenol, 3.7 grams of zinc acetate dihydrate, and 485.6 grams of a 37 percent formaldehyde solution were added to a reaction flask equipped with a stirrer, a condenser and a heating mantle. The reaction mass was heated at 85°C and a Dean Starke separator was connected to the condenser. 50.0 grams of cyclohexane were added to the flask. Temperature was adjusted to 72-72°C and the reation mass was refluxed, separating the water azeotropically. 347 grams of water were collected and cyclohexane was distilled off under vacuum. The resin was cooled to room temperature and decanted. Example 2 This test involved 1882.2 grams of a 90 percent solution of USP phenol, 1187.8 grams of 91 percent paraformaldehyde and 16.9 grams of zinc acetate dihydrate being added to a reaction flask equipped with a stirrer, a condenser and a heating mantle. The reaction mass was heated to 85°C and maintained until a Gardner-Holdt bubble viscosity of Q-R was obtained. The resin was dehydrated under vacuum to 90°C, cooled to room temperature and decanted. Example 3 In this test 658.8 grams of USP phenol were charged to a reaction flask equipped with a stirrer, a condenser and a heating mantle. 34.3 grams of 90 percent paraformaldehyde and 13.1 grams of a 45 percent solution of potassium hydroxide were added. The reaction mass was heated to 80°C and maintained at that temperature. 308.4 grams of 91 percent paraformaldehyde were added in 9 increments over a two-hour period. The resin was held at 80°C until a Gardner-Holdt bubble viscosity of 19.3 seconds at 23.0°C was reached, then neutralized with 22.3 grams of a 75 percent solution of toluene-xylene sulfonic acid. 2.0 grams of 45 percent potassium hydroxide were added to adjust pH. The resin was cooled to room temperature and decanted. Example 4 In this test 34.6 kg (76.2 pounds) of a 90 percent solution of USP phenol were added to a reactor equipped with a stirrer, heating/cooling coil and condenser. 0.31 kg (0.68 pounds) of zinc acetate dihydrate and 21.8 kg (48.1 pounds) of 91% paraformaldehyde were added with mixing. The reaction mass was heated to 85°C and temperature was maintained at that point until a Gardner-Holdt bubble viscosity of "P" was obtained. The resin was then dehydrated under vacuum, cooled to room temperature and 20.43 kg (45 pounds) were discharged. 8.7 kg (19.2 pounds) of furfural were mixed into the remainder and discharged. Example 5 This test involved 34.6 kg (76.2 pounds) of 90% solution of USP phenol were added to a reactor equipped with a stirrer, a heating/cooling coil and a condenser. 0.31 kg (0.68 pounds) of zinc acetate dihydrate and 21.8 kg (48.1 pounds) of 91 percent paraformaldehyde being added while stirring. The reaction mass was heated to 85°C and held at that temperature until a Gardner-Holdt bubble viscosity of 1-J was reached. The resin was dehydrated under vacuum to an endpoint viscosity of 30-50 seconds (Gardner-Holdt), cooled to room temperature and discharged. Example 6 In this test 1982.0 grams of Resorcinol, Technical Flake, were added to a reaction flask equipped with a stirrer, a condenser and a heating mantle. 550 g. of de-ionized water and 131.1 grams of 37 percent formaldehyde were added to the flask. Heat was applied to 65°C and an exotherm resulted. 305.9 grams of 37 percent formaldehyde were added streamwise after the exotherm had subsided. 5.4 grams of a 50 percent solution of oxalic acid were added and the reaction mass temperature was held above 100°C for one-half hour. The resin was dehydrated at atmospheric pressure and then under vacuum to a temperature of 165°C, then 427.1 grams of de-ionized water were added. The resin was cooled to room temperature and decanted. Example 7 In this test 38.9 kg (85.7 pounds) of Resorcinol, Technical Flake, were charged to a reaction vessel equipped with a stirrer, a heating/cooling coil, and a condenser. 9.7 kg (21.4 pounds) of de-ionized water were added. 2.59 kg (5.7 pounds) of 37 percent formaldehyde solution were added and heat was added until a temperature of 100°C was reached. The reaction mass was stirred after the resorcinol dissolved. 6 kg (13.2 pounds) of 37 percent formaldehyde were added over one-half hour period. 0.227 kg (0.5 pound) of 50 percent oxalic acid solution was added and the reation mass was held above 100°C for one-half hour. The resin was dehydrated at atmospheric pressure, then under vacuum to 150°C, then 8.2 kg (18.1 pounds) of water were added . The resin was cooled to room temperature and discharged. Example 8 This test involved 1982 grams of Resorcinol, Technical Flake being charged to a reaction vessel equipped with a stirrer, heating mantle and a condenser. 495.5 grams of distilled water and 218.5 grams of 37 percent formaldehyde solution were added and mixed. Heat was applied until a temperature of 75°C was reached, then the reaction exotherm caused the temperature to rise to 90°C. When peak temperature was reached, 509.9 grams of 37 percent formaldehyde solution was added slowly over a 1-1/2 hour period. Next, 18.4 grams of a 50 percent oxalic acid solution in water were added. Temperature was held above 100°C for one hour. The resin was heated and dehydrated at atmospheric pressure, then added vacuum to a temperature of 165°C. 852 grams of distilled water and 1321.3 grams of resorcinol were added to the reaction flask and mixed for one hour. The resin was cooled to room temperature and discharged. Example 9 In this test 1982 grams of Resorcinol, Technical Flake, was charged to a glass reaction vessel equipped with a stirrer, condenser and heating mantle. The resorcinol was melted and 13.6 grams of a 20 percent solution of p-toluene sulphonic acid was added while mixing. 728.4 grams of a 37 percent formaldehyde solution were added streamwise. The reaction mass was held above 100°C for one hour after the formaldehyde addition was complete, then 321.3 grams of resorcinol were added. The reaction mix was heated to dissolve the resorcinol and held for 1 hour above 100°C. 161.8 grams of 50 percent sodium hydroxide were added. The resin was cooled to room temperature and discharged. Example 10 In this test 25.65 kg (56.5 pounds) of Resorcinol, Technical Flake, were charged to a steel reactor equipped with a heating/cooling coil, a stirrer and a condenser. The resorcinol was melted and 0.18 kg (0.4 pound) of a 20 weight percent water solution of p-toluene sulphonic acid was added to the reactor while stirring. 9.44 kg (20.8 pounds) of a 37 percent formaldehyde solution were added streamwise to the reactor over a 1-1/2 hour period. The reaction mass was held at 100-110°C for one hour with mixing, then 17.1 kg (37.7 pounds) of Resorcinol, Technical Flake, were added to the vessel. Temperature was maintained at 80-100°C for a 1/2 hour mixing period, then 2.63 kg (5.8 pounds) of a 50 percent solution of sodium hydroxide were added. The resin was cooled to room temperature and discharged. Example 11 This test involved 1101.1 grams of Resorcinol, Technical Flake being added to a reaction flask equipped with a stirrer, a condenser and a heating mantle. The resorcinol was heated to melting and 814 grams of a 20 percent p-toluene sulphonic acid solution were added. 404.6 grams of a 37 percent formaldehyde solution were added streamwise over a 45-minute period and the reaction mass was maintained above 100°C for an hour. 734.2 grams of Resorcinol, Technical Flake, were added and mixed at 80-100°C for one-half hour. 112.0 grams of 50% sodium hyroxide were added and mixed. The resin was cooled and decanted. To one increment, designated 11A, 5 parts per hundred resin (phr) of acetone were added. To a second increment, designated as 11B, 5 phr of methanol were added. A third increment was not modified. Example 12 Resins from Examples 2 and 6 were mixed with filler, solvents and bonding agents as per the table below and applied to chopped strand mat (which is marketed by PPG Industries of Pittsburgh, Pennsylvania under the trade designation PPG AKM) using hand layup techniques. Example 12A was heated in a press at 85°C for 10 minutes. Example 12B was maintained at room temperature. Mechanical properties were tested as per applicable ASTM procedures. Glass content was approximately 25 weight percent. Results are listed below. This Example shows a phenolic component at about 60 percent phenol and 42 percent formaldehyde along with a resorcinol novolak at 77 percent resorcinol and 17 percent formaldehyde used to make the reinforced plastic laminate. The results indicate good mechanical properties for the laminates. The results also show that the properties were generally the same whether the material was cured at room temperature or was heated to accelerate the cure. Example 13 Resins from Examples 4 and 7 were mixed with filler, solvents, catalysts and bonding promoters as per the previous example and applied to PPG AKM chopped strand mat using hand layup techniques. Glass content was approximately 25 weight percent. The amount of furfural and resin (7) was varied but the total ratio of methylene donor and acceptor was maintained. Mechanical properties were obtained with applicable ASTM test methods and are listed below. A B C D E Furfural Content, phr 20 30 35 40 50 Tensile Strength, psi x 10 3 10.7 11.7 9.4 12.2 10.7 Tensile Modulus, psi x 10 6 0.76 0.79 0.61 0.85 0.71 Flexural Strength, psi x 10 3 21.0 23.1 20.7 25.6 23.8 Flexural Modulus, psi x 10 6 0.75 0.85 0.79 0.89 0.86 This Example illustrates a phenolic component at about 61 percent phenol and 38.5 percent formaldehyde. Furfural ratios were varied from 25 to 50 parts per 100 parts of the phenolic component. The resorcinol novolak was 79 percent resorcinol and 17.5 percent formaldehyde. This test showed good results with varied amounts of furfural and resorcinol novolak component. Example 14 Resins from Examples 4 and 7 were mixed with various fillers, solvents, catalysts and bonding promoters in the ratio from Example 11 and applied to PPG AKM chopped strand mat using hand layup techniques (glass content is approximately 25 weight percent). Samples were cured at room temperatures and testing using applicable ASTM procedures. Mechanical properties are listed below. A B C D Filler ATH None Talc Kaolin Tensile Strength, psi x 10 3 13.1 11.0 10.9 9.6 Tensile Modulus, psi x 10 6 0.94 0.78 0.79 0.62 Flexural Strength, psi x 10 3 22.7 21.6 19.9 23.8 Flexural Modulus, psi x 10 6 0.73 0.67 0.67 0.92 These tests illustrate examples of several different fillers i.e., ATH (hydrated alumina), kaolin (China clay) and talc or no filler can be satisfactorily employed in making laminates of the present invention. Example 15 Resins from Examples 3 and 8 were mixed with solvents, fillers catalysts and bonding promoters as in earlier examples and applied to PPG AKM chopped strand mat at an approximate glass content of 25 weight percent. Hand layup techniques were used and the samples were allowed to cure at room temperature. Mechanical testing was performed following applicable ASTM procedures. Results are listed below. Weight Percent Resin 3 41.5 Furfural 16.6 Resin 8 20.5 Mg(OH) 2 3.3 ATH 15.7 Aminosilane 2.4 NaOH 1.0 Tensile Strength, psi x 10 3 8.6 Tensile Modulus, psi x 10 6 0.81 Flexural Strength, psi x 10 3 17.4 Flexural Modulus, psi x 10 6 0.70 This Example illustrates the activation and cure of a conventional phenolic resole (non-Bender catalyzed) containing about 63.5 percent phenol and 33 percent formaldehyde by addition of a resorcinol novolak containing about 74.3 percent resorcinol and 16.4 percent formaldehyde along with the addition of an aldehyde source, furfural, to make a laminate with reasonably satisfactory mechanical properties when cured at room temperature. These tests demonstrate that the use of resorcinol or a resorcinol novolak has broader applications than the specific type of resole resin employed in the other examples. Example 16 A resole resin commercially available from Koppers Company, Inc., a Pittsburgh, Pennsylvania, under the trade designation B-505-10, and a resin from Example 8 were mixed with solvents, fillers, catalysts and bonding promoters and applied using hand layup techniques to PPG AKM chopped strand mat at a qlass content of approximately 25 weight percent. Mechanical properties were evaluated using applicable ASTM test procedures and are listed below. Weight Percent A B Resole 34.6 33.9 Furfural 13.8 13.5 Resin 8 29.7 29.1 Mg(0H) 2 2.8 2.7 ATH 15.8 15.4 Aminosilane 2.1 2.1 NaOH 1.0 2.9 Tensile Strength, psi x 10 3 10.6 8.6 Tensile Modulus, psi x 10 6 0.84 0.87 Flexural Strength, psi x 10 3 18.0 16.3 Flexural Modulus, psi x 10 6 0.64 0.63 NBS Smoke Chamber D max. Flaming Mode 37 -- Smoldering Mode 15 -- The tests of Example 16 were very similar in objective to those of Example 15. A different resole, i.e., Koppers phenolic foam resole available under the trade designation B-505-10 was cured by the addition of a resorcinol novolak and a methylene donor, furfural under mildly alkaline conditions to produce a satisfactory laminate at room temperature. Example 17 Resins from Examples 5 and 11 were mixed with solvents, fillers, catalysts and bonding promoters and applied to PPG AKM chopped strand mat using hand layup technique. Glass content was approximately 25 weight percent. Mechanical results were obtained using applicable ASTM test methods and are listed below. Weight Percent A B C Resin 5 34.2 34.6 34.6 Resin (11) (11A) (11B) Level 30.6 29.9 29.9 Furfural 13.7 13.9 13.9 Mg(OH) 2 2.7 2.7 2.7 ATH 15.7 15.7 15.7 Aminosilane 2.4 2.4 2.4 NaOH 1.0 1.0 1.0 Tensile Strength, psi x 10 3 13.3 10.8 10.6 Tensile Modulus, psi x 10 6 0.99 0.73 0.78 Flexural Strength, psi x 10 3 20.0 16.7 19.1 Flexural Modulus, psi x 10 6 0.68 0.60 0.64 Limiting Oxygen Index 54 48 49 NBS Smoke Chamber D max. Flaming Mode 28 12 17 Smoldering Mode 9 5 8 This Example establishes that satisfactory laminates may be made with resorcinol novolaks diluted with solvents to improve processability without having a negative effect on smoke emissions. A resole with phenol, furfural and formaldehyde in the preferred range and a resorcinol novolak in the preferred ranges were employed. Example 18 Resins from Examples 5 and 10 were mixed with fillers, solvents, catalysts and bonding promoters and applied using hand layup techniques to a variety of chopped strand mats as listed below. Glass content was approximately 35 weight percent. Mechanical testing was done following applicable ASTM procedures. Results are listed below. Glass Manufacturer Owens Corning Owens Corning Certainteed Scandinavian Owens Corning Type M902x23A M-710 M-127 MK10B M-711 Tensile St., psi x 10 3 14.2 14.4 14.9 14.4 13.1 Tensile Mod., psi x 10 6 0.72 0.99 0.86 0.81 0.84 Flexural St., psi x 10 3 32.3 30.4 31.0 26.8 29.4 Flexural Mod., psi x 10 6 1.15 1.09 1.11 0.99 0.97 These tests show that the invention was effective in the preferred ranges with a variety of brands of fiberglass reinforcement. Example 19 Resins from Examples 5 and 10 were mixed with solvents, fillers, catalysts and bonding promoters and applied to Certainteed M-127 trademark chopped strand mat, faced with C-glass veil, using hand layup techniques. Glass content was approximately 35 weight percent. Mechanical properties were evaluated by applicable ASTM test procedures and are listed below. Fillers were added at 12.5 and 20 weight percent levels. A B Filler, weight percent 12.5 20.0 Tensile Strength, psi x 10 3 16.5 17.6 Tensile Modulus, psi x 10 6 0.95 1.39 Flexural Strength, psi x 10 3 25.8 24.9 Flexural Modulus, psi x 10 6 1.18 1.13 D max. Flaming Mode 22 17 Example 19 shows laminates using the preferred ratio of components and two levels of a different filler, i.e., barium sulfate as well as a different type of veil. This illustrates as well the numerous areas of potential improvements over the prior art with minor modifications which one skilled in the art may employ. It will be appreciated that desired additional ingredients may be employed in the resin and resultant composite plastic of the present invention if desired. For example, fillers, if desired, such as wood flour, barium sulfate, hydrated alumina, silicates, kaolin, talc, walnut shell flower, glass beads, ceramic and, for example, carbon may be employed in a manner known to those skilled in the art. While such fillers may be employed in order to reduce costs and contribute to dimensional stability, they are not needed to provide flame and smoke retardation. In addition, should it be desired, pigments may be employed. Accelerators and other additives known to those skilled in the art may be employed. While for simplicity of disclosure herein, reference has been made to fiberglass as the reinforced plastic, it will be appreciated that other reinforced plastics whether or not reinforced by glass or synthetic fibers may be used beneficially with the resinous binder of the present invention. Included in such materials are polyvinyl chloride polyethylene, polypropylene, polyester urethane and epoxies. It will be appreciated, therefore, that the present invention provides an efficient resinous binder and method of using the same in creating reinforced plastics having improved properties. All of this is accomplished in a simple and economical manner which permits the use of room temperature curing and has the desired flame and smoke resisting characteristics. All of this is done in such a manner as to eliminate the disadvantageous characteristics of the use of paraformaldehyde as a curing agent. It will be appreciated that the resins and reinforced plastics of the present invention are usable in a wide range of environments where reinforced plastics are employed. While the invention facilitates the advantageous use of alkalne catalysts, the invention is not so limited. If desired, for example, acid catalysts may be used. Whereas particular embodiments of the invention had been described above for purposes of illustration, it will be appreciated by those skilled in the art that numerous variations of the details may be made without departing from the invention as described in the appended claims.

Claims: Claims for the following Contracting States : AT, BE, FR, DE, IT, NL, SE, CH, GB A process for the manufacture of an article of fire resistant reinforced plastics material, which process comprises forming a resin binder by mixing (a) a resorcinol formaldehyde novolak resin produced by the reaction of from 58 to 71 weight parts by weight of resorcinol and from 4 to 7 parts by weight of formaldehyde and (b) a phenolic resole resin, intimately mixing the resin binder with a reinforcing material, and thereafter curing the intimate mixture of resin binder and reinforcing material to produce the desired fire resistant article, provided the process is not a sheet moulding, bulk moulding or dough moulding process. A process according to claim 1, wherein the intimate mixture is cured at room temperature to release within 8 to 24 hours. A process according to claim 1 or 2, wherein the resorcinol formaldehyde novolak resin is produced in the presence of from 0.025 to 0.25 weight percent of an organic acid catalyst. A process according to claim 1, 2 or 3, wherein the phenolic resole resin is the reaction product of a phenol with paraformaldehyde which has first dissolved and at least partially disassociated into formaldehyde before reacting with the phenol. A process according to claim 4, wherein the phenolic resole resin is produced from a reaction mixture containing from 40 to 71 parts by weight of phenol and from 20 to 52 parts by weight paraformaldehyde. A process according to any one of claims 1 to 5, wherein the phenolic resole resin is produced in the presence of zinc acetate dihydrate. A process according to any one of claims 1 to 6, wherein the resin binder has a pH in the range 6 to 10. A process according to any one of claims 1 to 7, wherein the resin binder includes an alkaline catalyst. A process according to claim 8, wherein the alkaline catalyst is a metal hydroxide, a metal oxide or an amine. A process according to any one of claims 1 to 9, wherein a methylene donor is added to the resin binder, to reduce the viscosity of the resin binder, before it is mixed with the reinforcing material. A process according to claim 10, wherein from 12 to 21 weight percent of the methylene donor, based on the weight of the resin binder, is added to the binder. A process according to claim 10 or 11, wherein the methylene donor is furfural, furfuryl alcohol, oxazolidine, acrolein or combinations thereof. A process according to claim 1, wherein the intimate mixture is cured to release at a temperature in the range of from 16°C to 160°C over a period of from 20 hours to 0.06 hours. A process according to claim 13, wherein the intimate mixture is cured to release at room temperature over a period of from 8 to 14 hours. A process according to any one of claims 1 to 14, wherein the reinforcing material comprises a fibrous material. A process according to claim 15, wherein the fibrous reinforcing material comprises glass fibres. The use of a two-part, liquid-liquid pre-catalysed system, as a resin binder in the process claimed in any one of the preceding claims, which system comprises: (a) a resorcinol formaldehyde novolak resin which has been produced by the reaction of from 58 to 71 parts by weight of resorcinol and from 4 to 7 parts by weight of formaldehyde, and (b) a phenolic resole resin. The use according to claim 17, wherein the phenolic resole resin is produced by the reaction of 40 to 71 parts by weight of phenol and from 20 to 52 parts by weight paraformaldehyde. The use according to claim 17 or 18, wherein the phenolic resole resin is produced in the presence of zinc acetate dihydrate. The use according to claim 17, 18 or 19, wherein the resin binder includes a methylene donor to reduce the viscosity thereof. The use according to claim 17, 18, 19 or 20, wherein the resin binder is curable, to release, at room temperature within 8 to 24 hours. The use according to claim 17, 18, 19, 20 or 21, wherein the resin binder has a pH in the range 6 to 10. Claims for the following Contracting State : ES A process for the manufacture of an article of fire resistant reinforced plastics material, which process comprises forming a resin binder by mixing (a) a resorcinol formaldehyde novolak resin produced by the reaction of from 58 to 71 weight parts by weight of resorcinol and from 4 to 7 parts by weight of formaldehyde and (b) a phenolic resole resin, intimately mixing the resin binder with a reinforcing material, and thereafter curing the intimate mixture of resin binder and reinforcing material to produce the desired fire resistant article provided that the process is not a sheet moulding, bulk moulding or dough moulding process. A process according to claim 1, wherein the intimate mixture is cured at room temperature to release within 8 to 24 hours. A process according to claim 1 or 2, wherein the resorcinol formaldehyde novolak resin is produced in the presence of from 0.025 to 0.25 weight percent of an organic acid catalyst. A process according to claim 1, 2 or 3, wherein the phenolic resole resin is the reaction product of a phenol with paraformaldehyde which has first dissolved and at least partially disassociated into formaldehyde before reacting with the phenol. A process according to claim 4, wherein the phenolic resole resin is produced from a reaction mixture containing from 40 to 71 parts by weight of phenol and from 20 to 52 parts by weight paraformaldehyde. A process according to any one of claims 1 to 5, wherein the phenolic resole resin is produced in the presence of zinc acetate dihydrate. A process according to any one of claims 1 to 6, wherein the resin binder has a pH in the range 6 to 10. A process according to any one of claims 1 to 7, wherein the resin binder includes an alkaline catalyst. A process according to claim 8, wherein the alkaline catalyst is a metal hydroxide, a metal oxide or an amine. A process according to any one of claims 1 to 9, wherein a methylene donor is added to the resin binder, to reduce the viscosity of the resin binder, before it is mixed with the reinforcing material. A process according to claim 10, wherein from 12 to 21 weight percent of the methylene donor, based on the weight of the resin binder, is added to the binder. A process according to claim 10 or 11, wherein the methylene donor is furfural, furfuryl alcohol, oxazolidine, acrolein or combinations thereof. A process according to claim 1, wherein the intimate mixture is cured to release at a temperature in the range of from 16°C to 160°C over a period of from 20 hours to 0.06 hours. A process according to claim 13, wherein the intimate mixture is cured to release at room temperature over a period of from 8 to 14 hours. A process according to any one of claims 1 to 14, wherein the reinforcing material comprises a fibrous material. A process according to claim 15, wherein the fibrous reinforcing material comprises glass fibres.

Inventors: DAILEY THEODORE HARVEY JR, DAILEY, THEODORE HARVEY, JR.
Applicants: INDSPEC CHEMICAL CORP, INDSPEC CHEMICAL CORPORATION
Application year: 1989
Main classification: C08G8
IPC codes: C08G16, C09J161, C08G8, C08L61, C08K7