US2079642A - Cementing material - Google Patents

Description

I Patented May 11 1937 UNITED STATES CEMENTING MATERIAL James F. Walsh, South Orange, Harry E. Smith and Amerigo F. Caprio, Newark, N. 1., asslgnors to Celluloid Corporation, a corporation of New Jersey No Drawing. Application Ma 12, 1930, Serial No. 451,862

13 Claims.

This invention relates to the preparation of a cementing material for the compositing or lamination of sheets of cellulosic plastics.

An object of our invention is to prepare a sheet or film of plastic material adapted to be em ployed as an adhesive or cementing material for causing layers of plastic compositions containing derivatives of cellulose to adhere to each other or to the surfaces of other material. 'Further objects of our invention will appear from the following detailed description.

In cementing or compositing celluloid sheets. the practice has been to use volatile solvents such as acetone, alcohol, butyl acetate, etc. Said cements however are not always satisfactory, especially when colored cellulosic plastic sheets are cemented. In this case when the cement is brushed on the sheet, the colors have a tendency to run thus spoiling the configuration and color effects desired. This trouble is also experienced with celluloid sheets that have been printed and which are cemented in this manner, since the ink is dissolved by the active solvents and the letters become smeared and lose their sharp outline.

5 Spraying such sheets with liquid solvent is also objectionable, since the powerful action of the I solvents tends eventually to warp or distort the sheets. This isa rather serious defect, since the cellulosic plastic stock becomes green and 30 shrinkage and buckling difllculties develop upon use.

The need of a cementing medium to overcome all these difficulties has been great. We have found that thin flexible sheets of a plastic com- 35 position containing a derivative of cellulosev and a relatively large amount of a plasticizer comprising an alkyl ester of phthalic acid may be used as an intermediate layer between two sheets to be cemented. Upon the application of heat 40 and pressure, a fusion or-bond between the sheet is effected without the further application of a liquid cement. By the use of such sheets as the cementing material, all the objections arising, from the use of a volatile solvent are 45 avoided.

In accordance with our invention, we prepare sheets or films containing a derivative of cellulose and a relatively-large proportion of a plas-- ticizer comprising an allwl phthalate, which 50 sheets are adapted to be used as an, adhesive or cementing agent for causing films, sheets or'other articles made of cellulosic plastics to adhere to each other or to the surfaces of other materials. The cementing or adhesive sheet may contain 55 any suitable derivative of cellulose such as cellulose nitrate or pyroxylin .or organic derivatives of cellulose and cellulose ethers. Examples of such organic derivatives of cellulose are cellulose acetate, cellulose formats, cellulose propionate 60 and cellulose butyrate, while examples oi cellulose ethers are ethyl cellulose, methyl cellulose and benzyl cellulose.

As stated, we employ an alkyl ester of phthalic acid in the plasticizer. Examples of such alkyl phthalates are dimethyl phthalate, diethyl phthalate, methyl ethyl phthalate, dibutyl phthalate or diamyl phthalate. One or more of these alkyl phthalates may be used as the sole plasticizer.

In many cases, however, other plasticizers may also be added to the composition of the cementing sheet. Examples of these plasticizers are camphor, diethyl tartrate, dibutyl tartrate, triphenyl phosphate, para-ethyl-toluene-sulfonamid, etc. The choice of such plastioizer will depend upon the derivative of cellulose present. The total amount of plasticizer employed will generally vary from 50 to 150% or more of the weight of the derivative of cellulose present. The amount of plasticizer will be governed by the degree of heat and pressure to be employed in the cementing operation, generally the higher the temperature and pressure employed in such operation, the smaller will be the amount of plasticizer employed.

Often it is desirable to add higher boiling volatile solvents such as butyl acetate, diacetone alcohol, ethyl lactate, the ethyl ether of ethylene glycol, etc.,to the composition from which the adhesive sheets are made, since their presence tends to keep the sheets soft and easily cementable.

If the sheets are to be employedfor causing the cellulose plastics to adhere to surfaces of metal or other smooth surfaces, it is advisable to incorporate a resin compatible with the derivativeof cellulose in the same. In. the case of cellulose nitrate or pyroxylin, ester gum may be employed, while in the case of cellulose acetate accaroid resin, the fusible and soluble phenolformaldehyde condensation resins or toluenesulfonamid-formaldehyde resins may be used. The amount of resin added may be from 30 to 100% of the weight of the derivative of cellulose present in the cement sheets.

Pigments, dyes, fillers or other effect materials may be added, as may be also stabilizers such-as urea, etc.

vIn making the adhesive or cementing sheets, the cellulose derivatives and plasticizers may be mixed together with other ingredients that are to be present with suitable volatile solvents or latent solvents such as acetone, ethyl alcohol, methyl alcohol, benzol or suitable mixtures of these. The choice of solvents or solvent mixtures depends upon the solubility characteristics of the particular cellulose derivative employed. The mass may be converted or gelatinized by kneading at elevated temperatures and then treated with heated malaxating rolls, and. then further worked up into sheet form by any known method. Solutions of the cellulose derivative and plasticizers may be cast on polished surfaces to form films upon evaporation of the volatile solvent. The sheets are formed to have thicknesses of from 0.003 to 0.020" or more. We have found thicknesses of 0.005 to 0.010 and 0.020" produce very satisfactory results. The sheets are preferably used unpolished.

In employing the adhesive or cementing sheets made in accordance with this invention, the same are inserted between the films, sheets or layers of cellulosic plastic that are to be united, and the assembly is then pressed at elevated temperatures. Likewise such adhesive sheets may be inserted between a layer of cellulosic plastic and the surface of metal or wood and lamination caused by the application of heat and pressure. The amount of heat and pressure employed will depend on the percentage of plasticizers present and also the presence of high boiling solvents, the greater percentage of these present, the less heat or pressure required.

Thus an adhesive sheet containing equal parts of pyroxylin and plasticizercan be readily cemented at a temperature corresponding to only 10lbs.per square inch steam pressure and under a hydraulic pressure 500 lbs. per square inch for 10 minutes. Where only slight pressure and heat are available, the adhesive sheets may be subjected to the vapors of solvents prior to lamination.

In order further to illustrate our invention but without being limited thereto, the following specific examples are given.

' Example I The following is a formula for making adhesive sheets containing pyroxylin.

Parts by weight If desired the carnphor may be omitted entirely, in which case 75 parts of diethyl phthalate is employed. Other desirable results are obtained when diethyl phthalate is replaced by dibutyl phthalate.

Example [I p The following are examples or formulae for making adhesive sheets containing cellulose acetate.

- Parts by weight (a) Cellulose acetate 100 Triphenyl phosphate 10 Para-ethyl-toluene sulfonamid 25 ,Dimethyl phthalate 25 Triacetin; 20 Volatile solvent q s Partsby weight (b) Cellulose acetate 100 Dimethyl phthalate 45 Para-ethyl-toluene sulfonamid 25 Triacetin l5 Volatile solvent (Ls.

The adhesive sheets made in accordance with this invention are flexible and are readily applied between the two sheets to be cemented. There is no running of color, no color absorption, and the cementation can be limited to any particular section desired. The il 9f cementable sheets made in accordance with this invention is quite advantageous for many purposes.

They are dry, non-sticky,'easily applied and the union or amalgamation is perfect.

The foregoing examples are given merely by way of illustration, and many variations may be made therein without departing from the spirit of our invention.

Having described our invention, what we de sire to secure by Letters Patent is:

1. Method of causing the surface of a layer of plastic composition containing a derivative of cellulose to adhere to another surface without the aid of low-boiling solvents comprising interposing between the surfaces a preformed sheet containing a derivative of cellulose, relatively high boiling solvents and a plasticizer comprising an alkyl phthalate present in proportion of from 50 to 100% on the weight of the derivative of cellulose and applying heat and pressure.

2. .Method of causing vthe surface of a layer of plastic composition containing a derivative of cellulose to adhere to another surface without the aid of low-boiling solventscomprising interposing between the surfaces a preformed sheet containing a derivative of cellulose, a resin and a plasticizer comprising an alkyl phthalate present in proportion of from 50 to 100% on the weight of the derivative of cellulose and applying heat and pressure.

3. Method of causing the surface of a layer of plastic composition containing a derivative of cellulose to adhere to another surface without the aid of low-boiling solvents, which comprises interposing between the surfaces a preformed sheet containing cellulose nitrate, relatively high boiling solvents and a plasticizer comprising an alkyl phthalate present in proportion of from 50 to 100% on the weight of the cellulose nitrate and applying heat and pressure.

4. Method of causing the surface of a layer of plastic composition containing a derivative of cellulose to adhere to another surface without the aid of low-boiling solvents, which comprises Anterposing between the surfaces a preformed sheet containing cellulose nitrate, a resin and a plasticizer comprising an alkyl phthalate present in proportion of from 50 to 100% on the weight of the cellulose nitrate and applying heat and pressure.

5. Method of causing the surface of a'layer of plastic composition containing a derivative of' cellulose to adhere to another surface without the aid oflow-boiling solvents, which comprises interposing. between the surfaces a preformed sheet containing cellulose acetate,. relatively high'bolling solvents and a plasticlzer comprising an alkyl i -hthalate present in proportion of from 50 to 100% on the weight of the cellulose acetate and applying heat and pressure.

6. Method of causing the surface of a layer of plastic composition containing a derivative of cellulose to adhere to another surface without the aid of low-boiling solvents, which comprises interposing between the surfaces a preformed sheet containing cellulose acetatefa resin and a plasticizer comprising an alkyl phthalate present in proportion of from 50 to 100% on the. weight of the cellulose acetate and applying heat and pressure.

'7. Method of causing the surface of a layer of plastic composition containing a derivative of cellulose to adhere to another surface without the aid of low-boiling solvents, which comprises interposing between the surfaces a preformed sheet containing a derivative of cellulose, relatively high boiling solvents and a plasticizer selected from the group consisting of dimethyl phthalate and diethyl phthalate, said plasticizer being present in a proportion of from 50 to 100% on the weight of the derivative of cellulose, and applying heat and pressure. H

8. A sheet adapted to be employed as a cementing agent for cellulosic plastics, which sheet contains aderivative of cellulose, relatively high boiling solvents and a plasticizer comprising an alkyl phthalate, the amount of plasticizer present being in a proportion of from 50 to 100% on the weight of the derivative of cellulose.

9. A sheet adapted to be employed as a cementingagentior cellulosic plastics, whichsheet contains a derivative of cellulose relatively high boiling solvents and a plasticizer comprising an' 2oalky1 phthalate, the amount of plasticizer present being in a proportion of from 50 to 100% on the weight of the derivative of cellulose.

10. .A sheet adapted to be employed as a cementing agent for cellulosic plastics, which sheet contains a derivative of cellulose, a resin and a plasticizer comprising an alkyl phthalate, the amount of plasticizer present being in a proportion of from to on the weight of the derivative of cellulose.

11; A sheet adapted to be employed as a. cementing agent for cellulosic plastics, which sheet contains cellulose nitrate, relatively high boiling solvents and a plasticizer comprising an alkyl phthalate; the amount of plasticizer present being in a proportionoi from 50 to 100% on the weight of the cellulose nitrate.

boiling solvents and a plasticizer selected from the group consisting of dimethyl phthalate and diethyl phthalate, the amount 01' plasticizer present being in a proportion of from 50 to 100% on the weight of the derivative of cellulose.

' JAMES F. .WALSH. HARRY E. SMITH. AMERIGO 1". CAPRIO.