US2792309A

US2792309A - Phonograph records containing silicone oils and resins

Info

Publication number: US2792309A
Application number: US388926A
Authority: US
Inventors: Charles F Teichmann
Original assignee: Texaco Development Corp
Current assignee: Texaco Development Corp
Priority date: 1953-10-28
Filing date: 1953-10-28
Publication date: 1957-05-14
Anticipated expiration: 1974-05-14

Description

PHONOGRAPH RECGRDS CONTAINING SILICGNE AND RESINS No Drawing. Application October 28 19 53, Serial No. 388,926

3 Claims. (Cl. 106-37) This invention relates to improvements in phonograph records.

Phonograph records of the types in commercial use today are formed of a moldable material upon which tone grooves from a matrix are impressed as by heat and pressure, the matrix usually being an electroplate formed on a master disc on which the sound is originally recorded. Such records are made of a variety of materials including vinyl resins such as are sold under the trademark Vinylite, and other mediums such as shellac, Celluloid, cellulose acetate, stearic acid and montan wax, ethyl cellulose, etc. The lower priced records are usually formed of a mixture of shellac, a filler such as clay, and coloring matter such as carbon black, the mixture being plasticized by a suitable plasticizer such as carnauba wax. The higher priced records are usually made of plastics such as vinyl resins, a -filler, and coloring matter. Some records are homogeneous whereas others are formed of a relatively cheap base having one or both faces coated with the material in which the tone grooves are impressed.

I All of the above types of records are characterized by a noticeable amount of so-called needle scratch or other noise. Scratch filters have been used in an effort to eliminate the scratch. They reduce the scratch to some degree but at the same time the desirable frequencies in the same band as the scratch are cut off so that the fidelity of the reproduction is impaired. Most, if not all of the needle scratch, appears to be due to imperfections in the surface of the record which are both macroscopic and microscopic. Such irregularities are apparently due to the inclusion of gas such as air during the manufacture of the initial composition and the subsequent evolvement of such included gas on the surface of the record when it is subjected to heat and pressure in the molding step. The gas bubbles apparently form on or close to the surface of the record in the tone grooves. Such bubbles, after molding, may continue to exist as interruptions of the record surface or they may be cut by the playing needle to form craters which gradually become enlarged and noisier. In any case, the small bubbles tend to expand on the surface when the pressure of the press is relieved thereby producing a very thin outer Wall which is easily cut by the playing needle.

It is an object of this invention to provide a recording surface wherein needle scratch insofar as imperfections in, the record surface is concerned. is substantially eliminated.

Another object of the invention is'to provide a phonograph record of novel composition.

Briefly stated, the present invention involves the incorporation in the record composition of a compound or mixture of compounds which have the ability to prevent the formation of gas bubbles on the recording surface of the record. Whether these results are accomplished by the prevention of foaming and frothing during the initial preparation of the composition or whether they are accomplished by preventing the formation of bubbles on the recording surface during the impressing step is not ates 2,792,309 7 Patented 'May '14, 1, 57

ice

s:1 They may be formed by polymerization or condensation of organo silicols, the latter including mono-, di and trisilicols as well as mixtures thereof.

Such compounds may be represented by the following I probable formula: I

in which n is l or more and .R represents similar or dissimilar organic radicals such as alkyl, aryl, and aralkyl,

- alkaryl or heterocyclic groups, or the terminal Rs may be substituted by hydroxyl groups or all but one of the Rs attached to each silicon atom may be substituted by hydroxyl groups or halides. Such condensation products may be ermed as straight chains, cyclic or cross polymerization products which maybe liquids or solids.

R is preferably a single organic radical of low molecular weight such as methyl, ethyl and short chain alkyl groups. However, compounds having organic radicals of higher molecular weight such as phenyls or compounds containing organic radicals of both high and low molecular weights can be used.

A preferred compound is a methyl silicone having the following formula:

r r CH3 Bi-O SlCHs Hi 1: H:

in which n is 1 or more. In most cases, it is believed that the product contains a number of such polymers of different chain lengths and perhaps different chain types.

The liquid compounds may be used in the record compositions. However, it is preferred to use the so-called methyl silicone resins which are characterized by excellent thermal stability and good resistance to oxidation. The ethyl resins are slightly softer, more soluble and slower to cure than the methyl resins. Hence for a good hardness and degree of infusibility and insolubility, compounds of fewer ethyl than methyl groups may be used. In the case of the methyl resins, the polymers having CH3 to Si ratios of 1.2 to 1.5 are preferred. In the ethyl compounds, a ratio of 0.5 to 1.5 ethyl groups per silicon atom is preferred.

Another class of organo siloxanes capable of use in practicing the invention is the organo silicate condensation products represented by the following probable formula: R. R

in which n is l or more and R likewise represents similar or dissimilar organic radicals such as alkyl, aryl, alkaryl, aralkyl or heterocyclic groups. Such compounds may be prepared by controlled or partial hydrolysis of the tetra or ortho silicate esters with water. Again organic radicals of the low molecular weight such as methyl and ethyl are preferred although it is to be understood that radicals of higher molecular weights can be used alone or in combination with radicals of low molecular weight. Such compounds exist in both liquid and solid form.

As the foregoing compositions and their methods of preparation are well known to the art and no claim thereto is made herein, further discussion is considered unnecessary.

In incorporating organo siloxanes in compositions going to make up the record, surface of the record, such compounds are preferably charged to the initial mix. The amounts used vary in accordance with the type of composition from which the records are being made. In most cases the use of a liquid silicone such as dimethyl silicone may be limited to as little as 0.5 to 1% by weight or even less. In other cases where the organo siloxane is in the form of a resin, it may be used in amounts as high as 20%.

The following represent a few of many possible combinations.

Asbestos powder sufiicient to suit. Magnesium oxide sufficient to suit.

The dimethyl silicone above is preferably of a viscosity of about 1 000 centistokes at 25 C.

Example II Parts Vinyl resin 90.0 Chromium oxide 7.5 Carbon black 50.0 Calcium stearate 1.0 Carnauba wax 1.5 Chlorinated naphthalene 4.5 Methyl silicone resin (CHs/Si ratio 1.5) 1 to 5 Among the vinyl resins that can be used successfully, in compositions such as illustrated in Example II, are those selected from the group comprising polymerized vinyl esters of aliphatic acids such as vinyl acetate, vinyl halides such as vinyl chloride, vinyl benzene, or conjointly polymerized vinyl compounds of said group. Reference is made to British Patent 408,969 for further information.

It-is to be understood that the foregoing examples are only typical and that dependent upon the compositions employed, it will be found advantageous to vary the organo siloxane compound used both as to chemical composition and physical state.

The organo siloxane compounds apparently exert a surface tension effect in the original mixing or in the subsequent molding or both which prevents the formation of gas bubbles with consequent interruptions in the recording surface of the record.

It is to be understood that the organo siloxane compounds may be used in homogeneous records or may be used in the compositions applied to the recording surfaces of so-called laminated records which are formed by placing the recording composition proper on one or both faces of a core of relatively cheap base material.

It is also to be understood that the silicone polymers may be omitted from the original composition and applied to the surface of the record immediately before pressing or the compound may be used in both steps. In the former method, the polymers may be dusted on as a powder, or sprayed as a liquid on the matrix.

The value of the invention will be appreciated when it is considered that substantially all the so-called needle scratch may be eliminated, thus enabling a record even of the cheapest type to give true tone fidelity and to reproduce as well as it was originally pressed.

The use of the organo siloxanes has an added advantage in enabling the pressed record to be freely removed from the matrix without breakage, thus increasing the accuracy of reproduction and reducing the percentage of defective records. This is a considerable item when it is considered that the better records are subject to a very rigid inspection and rejections in some cases have run as high as 10%. This figure is significant when it is considered that hundreds of thousands of records are produced daily.

This application is a continuation-in-part of my application Serial No. 25,071, filed May 4, 1948.

Obviously, many modifications and variations of the invention as above set forth may be made without departing from the spirit and scope thereof, and therefore only such limitations should be imposed as are indicated in the appended claims.

I claim:

1. A phonograph record having impressed therein tone grooves and characterize-d by the absence of gas bubbles in the tone groove surface thereof and substantial elimination of needle scratch when played, said record comprising a moldable plastic material suitable for phonograph records selected from the group consisting of cellulose acetate, shellac, polyvinyl chloride, polyvinyl acetate, polyvinyl benzene, and copolymers of said polyvinyl compounds with one another, said record containing a material selected from the group consisting of polymethyl silox'ane oils and resins in an amount from about 0.5 to 1% by weight.

2. A phonograph record having impressed therein tone grooves and characterized by the absence of gas bubbles in the tone groove surface thereof and substantial elimination of needle scratch when played, said record comprising a moldable plastic material suitable for phonograph records selected from the group consisting of cellulose acetate, shellac, polyvinyl chloride, polyvinyl acetate, polyvinyl benzene, and copolymers of said polyvinyl compounds with one another, said record containing a polymethyl siloxane resin in an amount from about 0.5 to 20% by weight.

3. A phonograph record having impressed therein tone grooves and characterized by the absence of gas bubbles in the tone groove surface thereof and substantial elimination of needle scratch when played, said record comprising a moldable plastic material suitable for phonograph records selected from the group consisting of cellulose acetate, shellac, polyvinyl chloride, polyvinyl acetate, polyvinyl benzene, and copolymers of said polyvinyl compounds with one another, said record containing dimethyl silicone oil in an amount from about 0.5 to 1% by weight.

No references cited.

Claims

1. A PHONOGRAPH RECORD HAVING IMPRESSED THEREIN TONE GROOVES AND CHARACTERIZED BY THE ABSENCE OF GAS BUBBLES IN THE TONE GROOVE SURFACE THEREOF AND SUBSTANTIAL ELIMINATION OF NEEDLE SCRATCH WHEN PLAYED, SAID RECORD COMPRISING A MOLDABLE PLASTIC MATERIAL SUITABLE FOR PHONOGRAPH RECORDS SELECTED FROM THE GROP CONSISTING OF CELLULOSE ACETATE, SHELLAC, POLYVINYL CHLORIDE, POLYVINYL ACETATE, POLYVINYL BENZENE, AND COPOLYMERS OF SAID POLYVINYL COMPOUNDS WITH ON ANOTHER, SAID RECORD CONTAINING A MATERIAL SELECTED FROM THE GROUP CONSISTING OF POLYMETHYL SILOXANE OILS AND RESINS IN AN AMOUNT FROM ABOUT 0.5 TO 1% BY WEIGHT.