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FILE NAME: AZW/W DATE:EZ DOC#: A/W OCUMENT DESCRIPTIONh^WZ&,Z dZWZDZZZZ 'United States Patent [19] Barker et al. [11] 3,922,241 [45] Nov. 25, 1975 [54] ASBESTOS.FREE HEAT.RESISTANT THERMOSETTABLE PHENOLALDEHYDE MOLDING COMPOSITION [75] Inventors: Richard H. Barker, Dalton; Frank P. Florentine, Pittsfield, both of Mass. [73) Assignee: General Electric Company, Pittsfield, Mass. [22J Filed: June 12, 1974 [21] App\. No.: 478,785 [52] U.S. CI. .................................. 260/17.2; 260/38 [5 I ) Int. CJ.2 ............................................ COSL 1/02 [58] Field of Search .............................. 260/17.2, 38 [56] 3,567,667 References Cited UNITED STATES PATENTS 3/1971 Rumbold .......................... 260/17.2 3,658,750 3,813,356 4/1972 Tsukui et al. ......................... 260/38 5/1974 Lievremont et al. ................ 260/2.5 OTHER PUBLICATIONS Chem. Abst. 68:11540(, "Structural Material-Resins -Filler," Yatsenko et al. Primary Examiner-Donald E. Czaja Assistant Examiner-Edward Woodberry Attorney, Agent, or Firm-William F. Mufatti; Donald M. Papuga [57] ABSTRACT An asbestos free, heat resistant phenolic molding composition comprising in admixture, a phenolic resin and a filler combination of aluminum silicate, talc and cellulose fibers. 6 Claims, No Drawings 3,922,241 1 2 ASBESTOSFREE HEATRESISTANT THERMOSETTABLE PHENOL.ALDEHYDE MOLDING COMPOSITION The phenolic resin employed in the practice of this invention is preferably a phenol-aldehyde resin and can be any phenol'aldehyde resin which is prepared by reacting from less than one mole to more than one mole 5 of an aldehyde per mole of phenol under certain condiThis invention relates to an asbestos free, heat resis- tions to provide a resin. Ifless than one mole of an aldetant phenolic molding composition ,comprising in ad- hyde is used, the resin so produced is commonly called mixture a phenolic resin and a filler combination of aluminum silicate,talc and c~lIulose fibers. a novolac. The novolac resin is generally the type that can be finely ground and requires blending thereof with lOan external crosslinking agent such as hexamethylene- BACKGROUND OF THE INVENTION tetramine in order to provide a thermosettable resin which can be advanced to an infusible state upon expo- Phenolic molding compositio'ns hilVe been availabie sure to elevated temperatures. While any external for many years and are generally ,made with an asbestos crosslinking agent can be employed herein, the pre- filler. The asbestos is used as a reinforcing fiber or as a 15 ferred external crosslinking agent is hexamethylenetet- reinforcing filler. The asbestos provides the phenolic ramine. Generally, the preferred range of aldehyde em- molding composition with increased mechanical, ther- ployed herein to prepare the novolac is 0.5-0.9 moles mal and electrical properties. However, the use of as- thereof per mole of phenol and preferably 0.6 -0.8 bestos filled phenolics provides a hazard to those ex- moles thereof. While any aldehyde can be employed posed to this type of material. 20 herein such as folmaldehyde, paraformaldehyde, acet- The standard for direct exposure to asbestos fibers is aldehyde, butyraldehyde, furfuraldehyde, etc., the pre- clearly detailed by the Department of Labor's Occupa- ferred aldehyde to be employed herein is formalde- tional Safety and Health Administration (OSHA). Ef- hyde. fects of exposure to personnel involved in the manufac- When employing more than one mole of aldehyde ture of phenolic molding compound in which raw as- 25 per mole of phenol, a one-stage resin is produced which bestos is handled or processed is well delineated. What can be,advanced to an infusible state by the mere appli- is less obvious is the health hazard to personnel in shops cation of elevated temperatures.' The one-stage resin that mold asbestos material and finish or machine the which can be employed herein is one prepared by re- molded parts. acting more than one mole of an aldehyde per mole of In order to comply with OSHA standards dealing 30 phenol and preferably 1.I-3.0 moles thereof. Again, with asbestos, the development of asbestos-free pheno- the preferred aldehyde is formaldehyde. Iic molding compositions which comply with the OSHA In addition, it has also been observed that when using law is needed. However, there are properties problems a phenolformaldehyde novolac, favorable molding associated with eliminating asbestos from phenolic characteristics are obtained when the novolac h,as or- molding compositions. Two of the key properties ef- 35 tho-ortho content of less than 70 weight percent of the fected are dimensional stability and heat resistance. total novolac composition. Optimum results are ob- The heat resistance, mechanical and electrical prop- tained when the ortho-ortho content is around 50 erties of the non-asbestos, phenolic molding composi- weight percent, by the balance of the novolac consists tions must be at least equivalent to the asbestos-con- of ortho-para and para-para linkages. taining compositions. Additionally, the moldability, of 40 By these various types of linkage, it is meant the the non-asbestos compositions must be equivalent to methylene bridging between the phenol nuclei and can the asbestos-filled compositions. Since the same mold be represented by the following formulas: is used for asbestos and non-asbestos compositions, the shrinkage of both types should be similar. In short, the non-asbestos compositions should not change normal 45 operation procedures, at least in a deleterious sense. The non-asbestos filler combination of the instant in- vention satisfies this criteria. A. DESCRIPTION OF THE INVENTION 50 The invention is directed to an asbestos-free heat re- sistant phenolic molding composition comprising in ad- mixture, a phenolic resin and a filler combination of aluminum silicate, talc and cellulose fibers. 55 The filler combination of the instant invention when used with the phenolic resin provides a molding composition having heat resistant properties better than an ortho-ortho linkage asbestos filled phenolic resin composition. Also, heat deflection temperature and dielectric strength are 60 B. OH greater using the filler combination of the instant invention in place of asbestos in phenolic resins. Additionally, water absorption, arc resistance, tensile strength, flexural strength, flexural modulus, compres- @ sive strength, Izod impact and drop ball impact proper- 65 ties of a phenolic resin with the filler combination of the instant invention are comparable to an asbestos filled phenolic resin composition. OH CH2_@~ 3 ortho-para linkage OH I @ I 3,922,241 4 cent of asbestos fibers and 15 weight percent of wood flour to form a 50/50 mixture. The blend is then compounded in a screw extruder at about 220F which is 5 sufficient to melt the resin. The molten mixture is advanced through the screw and extruded into granular or pellet form; EXAMPLE II CH 2 10 Example I.is repeated except that a filler combination '1 of 14 weight percent aluminum silicate, 15 weight per- cent of talc and 8 weight percent of cellulose fiber is used in place of the asbestos. Each of the materials so prepared in Examples I and @o 15 II are subjected to the following tests: Water Absorp- tion, Heat Deflection (ASTM 0-648), Dielectric L I Strength (ASTM 0-149), Arc Resistance (ASTM D- OH para-para Iinkage 495), Tensile Strength (ASTM 0-651), Flexural Strength (ASTM 0-790), Flexural Modulus (ASTM The indi~idual cc:>mpo~ents .of the co~bin~t.ion of fill- 20 0-790), Compressive Strength (ASTM 0-695), Izod Impact (ASTM 0-256A) and the Drop Ball Impact. All ers of the mstant mventlOn, I.e., .alumma. slhca~e, tal.c and cellulose fibers are commer~lal~y aV3llable m van- test specimens are molded from conventional molding methods. The results are tabulated as follow ous forms and grades. The combmatlon of fillers can be s: employed in an amount of from about 15 to about 50 weight percent. Preferably the filler combm.a.tlon con ~-5 TABLE I stailiincsatfer,omfroamboaubtou5tt5o taobaobuot u2t02w0 ewigehigthpteprecrecnetnatloumf tianlca Test Example Example 11 I laonsde ffriobmersa. bSoauitd5wtoeigahbtoupter1c0enwtesigbhetinpgerbcaesnetdofonceltlhue- 30 DWHieaeatlteercDlArelfblescolrlpolnio(nO(F'k. ,al2426h4r.p) si) 0.2 0.2 380 350 weight of the molding composition. c Strength(6() cp. 2soC.st. VPM) 360 350 The composition of this invention is prepared by Arc Reslstanl (sec) TensIle Strength (psi) 180 180 methods well known to those skilled in the art. For ex- Flexur..1Strength (psi) 7000 12000 8000 12000 ample, the individual ingredients are mixed together in Flexural Modulus (psi) Compre..i.e Strength (psi) IxIO' 23000 IxIO' 27000 a suitable vessel and then fed directly to the feed 35 Izod Impact(ftlb/in, notch) .30 .33 hopper of a screw extruder or roll mill. Drop Ball Impact (in. 14 lb. weight) 11 13 It should be noted that the phenolic resin composi- tions of this invention can, and generally do, have present additive compounds which are normally used in Dimensional stability refers to the ability of the molded part to maintain its dim such compOSitions in addition to the composition of 40 ensions within reasonable limits under a wide variety of ambient conditions; this invention. Included among these other additives are fillers such as wood flour, calcium carbonate, glass it is particularly important when the molded phenolic part is a component in a device or assembly tibers, etc. and any combination of these or other which must rely on close part tolerances for successful operation. known tillers employed position as well as such in the phenolic molding comadditives as coal, lime, stearic 45 This property was evaluated for the compositions of Examples I and 11. The test moldings, in acid, etc. In a preferred embodiment of the instant in- this case, were compression molded Ilh in. X 3 in. rectangular boxes, vention, the composition of the instant invention may contain lime in amounts offrom 4 to IO weight percent. % in. deep, with crosssections of 0.100 in. (walls) and lA! in. and If4 in. (bottom). In yet another preferred embodiment the composition of the instant invention may contain coal in amounts of 50 Dimensions in both the length and width were tracked over a period of 15 days at direction from 5 to 15 weight percent. ture, 150F, 200F and 250F. room tempera- PREFERRED EMBODIMENT OF THE INVENTION The results are tabulated as follows: The following examples are set forth to illustrate more clearly the principle and practice ofthis invention to those skilled in the art and unless otherwise specified, where parts or percentages are mentioned, they are parts or precentages by weight. EXAMPLE I A phenol-formaldehyde resin is prepared by reacting about 0.7 moles of formaldehyde per mole of phenol in the presence of an acid catalyst, which is subsequently neutralized, to form a novolac. The novolac is ground to a fine particle size with about 16 weight percent of hexamethylenetetramine based on the weight of novolac. The resin mixture is then blended with 38 weight per- 55 TABLE 11 Temperature Example W Example I" 60 R15o0omF Temperature(7S0F) 01..14 01..23 200F 2.3 2.6 250F 2.9 3.4 Thl.~e numbers indi~te dimensional chanse of length in mils per inch. 65 The results in Table I demonstrate that heat deflection and dielectric strength were significantly improved with the com'position of Example 11 whereas water absorption, arc resistance, tensile strength, flexural strength, flexural modulus, compressive strength, Izod * * * 3,922,241 5 6 impact and drop ball impact data of Example I were sentially of in admixture, a phenol-aldehyde resin and a comparable with Example 11. Table 1I demonstrates that at higher temperatures the composition of Exam- filler combination of aluminum silicate, taIc and cellulose fibers; said filler combinatio ple II exhibits less overall change in dimension than the 5 n present in an amount of from about 15 to about 50 weight percent based on composition of Example I. Therefore, the filler combi- the weight of the molding composition. nation of the instant invention provides a phenolic 2. The composition as defined in claim 2 wherein the molding composition of comparable and better properties than a composition containing asbestos. aluminum silicate is present in an amount of from about 5 to about 20 weight percent based on the Example 11 was repeated using varying amounts of IQ of the molding composition. weight the aluminum silicate, talc and cellulose fibers. The results obtained were similar to those set forth in Tables 3. The composition as defined in claim 1 wherein the talc is present in an amount of from about 5 to about 20 I and 11. weight percent based on the weight of the molding Obviously, other modifications and variations of the composition. present invention are possible in the light of the above 15 4. The composition as defined in claim 1 wherein the teachings. It is, therefore, to be understood that cellulose fibers are present in an amount of from about changes may be made in the particular embodiments 5 to about 10 weight percent based on the weight of the described which are within the full intended scope of molding composition. the invention as defined by the appended claims. S. The composition as defined in claim 1 which con- What is claimed is: "0 tains lime. 1. An asbestos-free, heat-resistant thermosettable - 6. The composition as defined in claim 1 which contains coal. phenol-aldehyde molding composition consisting es- * * 25 30 35 40 45 50 55 60 65