UNITED STATES PATENT OFFICE 2,487,746 PHONOGRAPH RECORD COMPOSITION CON TAINING AS a BINDER SHELLAC and COUMARONE-INDENE RE SIN Lawrence A
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Patented Nov. 8, 1949 2,487,746 UNITED STATES PATENT OFFICE 2,487,746 PHONOGRAPH RECORD COMPOSITION CON TAINING AS A BINDER SHELLAC AND COUMARONE-INDENE RE SIN Lawrence A. Wood, Jr., and William P. Miller, Indianapolis, Ind., assignors to Radio Corpora tion of America, a corporation of Delaware No Drawing. Application June 19, 1946, Serial No. 677,903 3 Claims. (Cl. 260-27) 1 2 This invention relates to the art of preparing of these resins may be used in the production resinous compositions suitable for molding and of satisfactory molding compositions. more particularly to improved compositions suit Typical compositions falling within the con able for making phonograph records. cept of the present invention can be made up Many resinous compositions which have proven by using the various ingredients within the highly successful in making phonograph records ranges set forth in the following example. contain shellac as their principal resinous 1n gredient. Shellac ordinarily contains a wax Example which tends to separate out when the shellac Per cent by weight is mixed with the other ingredients of the record 10 Shellac ___________________________ __ 5-45 compositions and subiected to heat and pressure Coumarone-indene resin ____________ __ 0.1-5 in the molding operation. For this reason, it Gasoline insoluble, aromatic hydrocar has long been considered necessary to add a nat- ' bon soluble resinous extract of pine ural gum such as Manila or Congo copal in order wood ____________________________ __ 0-12 to inhibit the tendency of the wax to separate 15 Carbon black _______________________ __ 1-3 from the shellac. The use of these gums is, Mineral ?llers _____________________ __ 50~80i however, undesirable from several viewpoints. Zinc stearate _______________________ _‘_~ 0.25-1.0 First, like most natural products gathered from As stated previously, the coumarone-indene many different sources, the quality varies from resins may be replaced by similar amounts of time to time and from one local source to an either coumarone or indene polymers. other. Second, the supply is always uncertain The preferred form of gasoline insoluble, and subject to being cut off completely when aromatic hydrocarbon soluble resinous extract of ransportation di?iculties arise. And third, their pinewood used in these compositions has a melt cost often becomes prohibitive when world trade ing point range of l15-120° C. although the melt conditions become unsettled. 25 ing point may vary over a much wider range. For the above reasons, it appears to be highly As seen from the above example, this resin may desirable to substitute a more reliable ingredient be omitted entirely from the composition and for the natural gums. One object of the present when present usually replaces part of the shellac invention is to substitute a synthetic resin for in the ratio of 1:1. the natural gum in molding compositions con 30 The mineral ?llers, which usually contribute taining shellac. Another object is to provide an the major portion of the weight of the composi improved molding composition containing a resin tions, may be any one of numerous clays or of the coumarone-indene family as a substitute slates, diatomaceous earth, other silicates, or for natural gums. Another object is to provide ?nely divided calcium carbonate. Almost any a molding composition from which improved proportion of ?ller may be used up to about 80 phonograph records can be made. percent of the total composition by weight. Pro The essence of the present invention resides portions smaller than 50 percent are impractical in the discovery that resins of the coumarone for record compositions, however, due to the low indene family can advantageously be used in strength of the product Which results and the shellac molding compositions in place of natural 40 relatively high cost when a large proportion of gums since they effectively dissolve and prevent shellac is used. the separation of the natural wax found in shel The small percentages of zinc stearate are lac. Not only can coumarone-indene resins be preferred although not ‘absolutely necessary. used but coumarone polymers and indene poly This substance acts as a mold lubricant to pre mers as Well. vent pressings from sticking to the mold sur By varying the percentage of the coumarone face. Any other metallic soaps may be used for indene resin used in the compositions as well the same purpose, as Well as organic soaps, stearic as the amount of ?llers incorporated, resins of acid, natural or synthetic waxes, etc. this family having almost any melting point may Various percentages of carbon black are con ventional in this type of molding composition, be used eifectively. However, it is preferred to ' the percentages given in the above example use those resins having a softening point of merely being illustrative. The purpose served 115-120° C. The preferred range of coumarone is mainly that of a pigment and this could be indene resin is from 2 to 10 percent of the amount omitted entirely if desired. of shellac present although larger percentages There have thus been disclosed improved mold 2,487,746 4 ing compositions in which shellac is the principal and indene polymers and up to 12 percent of the resinous ingredient. The natural gums usually gasoline insoluble, aromatic hydrocarbon soluble present in this type 'of composition for the pur resinous extract of pinewood, and the remainder pose of dissolving the natural wax which accom comprising 50-80 percent of a ?ller and 0.25-1.0 panies theishc‘llac haveEbeen replaced with resins percent of a mold lubricant. of the coumarone-indene family. This results LAWRENCE‘ A. WOOD, JR. in better molding properties and more uniformity ‘ WILLIAM P. MILLER. of product. We claim as our invention‘: I REFERENCES CITED 1. An article according tocla-im 3, incl-udingl-é3 The following references are of record in the percent of carbon black. ?le of this patent: 2. An article according to claim 3 in which said synthetic resin polymer has asQften-in'g point UNITED STATES PATENTS of 115-120° C. ‘Number Name Date 3. A phonograph record made up of a com 15' 1,953,951 Boughton ________ __ Apr. 10, 1934 position including a binder consisting of :5-45 1,997,572 Bren _____________ __ Apr. 16, 1935 percent shellac, 01-51) percent of a synthetic 2,114,393 Lane ____________ __ Apr. 19, 1938 resin polymer from the class consisting of cou 2,130,239 Hunter __________ __ Sept. 13, 1938 marone-indene copolymers, coumarone polymers .