US1727039A - Duplicate sound record and process of making the same - Google Patents

Description

Patented Sept. 3, 1929.

1,7z1,639. UNITED STATES PATENT OFFICE. V

LEO nursrnm,

No Drawing.

- This invention. relates to im roved, duplicating sound records, tablets, disks or other bodies to be usedin sound recording and sound reproducing machines, of tough, flexible, permanent material, capable of receiving and retaining an impression thereon and an accurate copy of the matrix, containing no ingredient which will'evaporate or distort or otherwise injuriously affect the permanency or value of the record surface, at the same time practically non-inflammable, and this invention relates to the production of a duplicate soundrecord of this improved, impressionable material.

Sound records made by my im rovedprocess are superior to those hereto ore made in the respects, firstly, that the obtained impression is provided with a true cast surface, the material having no tendency to alter in composition, condition or form, and therefore retaining the record impression unimpaired in accuracy and tonal qualities for an indefinite period; and secondly, that the record can be made of less thickness and lighter weight than has been customary heretofore, with perfectly solid and homogeneous walls, there bein no 1 tendency inthe finished record to crack, ake, peel or warp, or to soften at normal summer temperatures.

By my composition a record mass results which has the desirable properties of flexibility, toughness, elasticity, resiliency, water- 'insolubility and non-'inflammability, possessing also great tensile strength, and hence satisfactory wearing qualities combined'with den; sirable acoustics and sound reproductionproperties.

Sound records used for phonographs, gramophones and similar apparatus give blurred, indistinct and impure .tones after a 4 very short use. This is usually due to microscopically small injuries to the edges of the sound grooves, or to the sound reproducing stylus cutting into the grooves themselves from the brittleness or softness of the foundation material of shellac, rosin, pitch, asphalt I and the like, used for making such sound records. Many attempts have been made to overcome this drawback by incor orating in the foundation material such pro ucts as cel- 9 luloid, xylonite, pyroxylin, galalith, indurated gelatin, vulcanite and ebonite, which materials, however, have proven unsuitable in many respects. Celluloid'which has been particularly recommended, gradually changes 5 in shape due to volatilization of camphor and OF NEWARK, NEW JERSEY, ASSIGNOR TO 'CELANESE CORPORATION OF AMERICA, A CORPORATION OF DELAWARE.

DUPLICATE SOUND RECORD AND PROCESS OF MAKING THE SAME.

Application filed February 24, 1923. Serial No. 621,108.

camphor substitutes contained therein, resulting m'distortion of the record and impair= ment of its tonal qualities. Celluloid is also highly inflammable. When celluloid shrinks, its tension then becomes so altered as to warp the record. Furthermore, celluloid is too hard, and produces shrill, harsh tones.

quantities in this connection, but it has its limitations. Shellac has desirable properties of thermoplasticity, softening at a temperature slightly above the temperature of Shellac at the present time is used in large boiling water and being sufficiently rigid at z ordinary atmospheric temperatures to render sound waves made thereon, quite durable. But shellac is a natural product of varying composition and properties, and subject to extensive adulteration. It must be imported from long distances, and is subject to market manipulation. In recent years the eostof shellac has risen to a point where its use is almost prohibitive, and forms a menace to the continued expansion of this industry. While many. substitutes for shellac have been brought forward and patented, the majority of these are lacking in the desirable property of thermoplastioity, or are obtainable in insufficient commercial quantitiesandat a prohibitive price.

Synthetic resins such as the phenol-aldesuited for general molding purposes, when used as phonograph record masses, require too long a time in the impression molds to render their use in sound records useful on account of materially diminished speed of production. When it is remembered that a ,complete record should be molded within a it has been s5 'hyde condensation products, while admirably are used through the record mass, the specific cellulose ester which I prefer to employ being the cellulose acetates, although the use of other cellulose esters of a similar nature and de ree of inflammability, such as, forexample, the cellulose 'formates, butyrates, propionates, phthalates and benzoates, would ,fall within the scope of my invention when used for this purpose. By my invention, recrd bodies are produced wanting in the undesirable properties previously mentioned,

butof the requisite degree of toughness coupled with a sulficient degree of hardness, readily workable through the malaxating rolls and on the steam table, ahd resulting in the production of a record wherein the requisite degree of toughness and hardness is obtained, and a material improvement in the tone and in the details of the phonetic record. Furthermore, when operating according to my invention, the thermoplasticity is such that an unduly high pressure on the steam tables is avoided, and hence the nickeled matrix will produce a large number of impressions before being discarded due to wear.

As will readily be understood by those versed in the art, in order to have a faithful reproduction of music or of the voice, the impression upon the master record must reproduce in theminutest detail the microscopic sound undulations, otherwise the reproduction sounds mufiied and possesses other disagreeable properties.

In producing a sound record composition according to my invention, I first weigh out the desired amounts of each of the inorganic filling materials such as clay, barytes, gypsum, kieselguhr', mica or red iron oxide, to

which is usually added in a manufacturing way, a proportion of waste record material from previous manufacture and ground records, this mixture being then mechanically mixed to a homogeneous, finely divided powder. Coloring matter as lampblack, and binder as finely divided cotton flock may then be incorporated by mixing, after which an amount of powdered shellac, in quantity de-' pending upon'the amount of organic cellulose ester required is added, and mixing continued until a mass of uniformity in appearance to the eye results. Finally the uninflammable cellulose ester with plastifieris" added, there being no volatile solvent required in the entire mixture, and mixing continued until the powder is apparentlyhomogeneous. This powder is then placed on the malaxatin'g rolls of hot and cold hollow cylinders, and a steam pressure admitted to the hot cylinder in amount depending upon the nature and amount of plastifying portion present in the mixture. From the malaxating' rollers, the mass is then run onto an endless belt through a marker which cuts out rectangles approximating the weight of an indic vidual record. These rectangles are then softened on the steam table, rolled into a ball,

' inserted under the reproducing matrix, and

steam and pressure then form the finished record, which, after removal, trimmin oif the burr on the edge, becomes the fimshed record of commerce. It will be obvious to those skilled in the art, that the proportions of filling materials, coloring matter, binder,

memes of cellulose,and non volatile cellulose ester plasticizer employed, will .vary depending cellulose ester employed. I may employ any non-volatile product which works harmoniously with shellac or shellac substitutes, or I may omit theme of a cellulose ester plastifier entirely, and depend upon the shellac and cellulose ester for the plasticity of the sound record composition.

I employ an amount of cellulose acetate and plastifier for the same in amounts from 25 percent to 50 percent of the weight of the completed batch, and depending upon the amount of shellac also present, a specific example of a satisfactory mixture embodying my invention being as follows To 100 pounds of finely ground record stock from which the paper from the labels has been removed, and the iron taken therefrom electrically, is added 100 lbs. rotten stone, 75 lbs. china clay, 40 lbs. mica, 5.1bs. lampblack, and 10 lbs. cotton flock, and the mixture thoroughly intermingled. There is then added 70 lbs. finely ground orange shellac and 80 lbs. cellulose acetate or cellulose acetate and non-volatile plastifier, the mass ance y further mixing. This mixture is then transported to the mixing .rolls and manipulated until the mass has sheeted, when it is marked out into individual record masses, softened-on the steam table, placed under the reproducing matrices, heat and pressure applied to the record mass, when a commercial record results. The manipulation of this mixture on the malaxating rolls, naturally differs 'from that in which the plasticity is entirely due to shellac. In general, less time and a lower steam pressure is required, resulting ingreater production per unit working force, and notable coal saving.

Records produced as above have an unusually high tensile strength, give sound reproductionsv remarkable for their fidelity and sonority, are less liable to breakage, not so prone to soften at' elevated temperatures, and

are somewhat lighter in weight. Due to the.

In the illustrative formula above given, satisfactory results are obtained with 50 lbs. steam pressure on the malaxating rolls, and

from .50 to 60 lbs.steam on the steam table where-the record is formed from the plastic mass. The record may be colored black with 130 lam black, or if large amounts of red iron OXlf e be used, the finished record will be of the corresponding color.

It may he mentioned that while it is old to make sound records from celluloid or nitrocellulose, or to provide such records with a coating of celluloid or of nitrocellulose, or to coat phonographic records with an extremely thin film of cellulose ester preparatory to the impression of the phonetic writing by applying a cellulose ester in a volatile solvent as a chlorhydrin; and while it is old to use such materials as paraffin, chlorinated fatty acids,

adjuncts to the cellulose acetate, or of softening the record mass by the introduction of paraffin or other fatty or waxy materials acting similarly I disclaim all these, but what I do claim and desire to secure by Letters Patent is:-

A composition for phonograph records comprising 100 pounds rotton stone, 100 pounds finely ground record mass, 75 pounds china clay, 40 pounds mica, 5 pounds lamp black, 10 bounds cotton flock, 10 pounds orange shellac, and 80 poundsof plastifier composed of cellulose acetate to which a nonvolatile solvent of the same has been added in suitable proportions.

This specification signed this nineteenth day of February, 1923.

' LEO RUTSTEIN.