Patent GB-348099-A (GB)
Title: Improvements in the manufacture of artificial and compound sheets and products produced therefrom
IPC: B32B17/08
Filed: 1929-11-02
Abstract: In the process described in the parent Specification for making cellulosic sheets having a thickness of above ,005 inch (and especially between ,005 inch and ,03 inch) by flowing a cellulose derivative solution over a surface and evaporating the solvent therefrom, the solution of cellulose derivative comprises a volatile solvent and also a medium boiling solvent and/or a high boiling solvent.  The volatile solvents include those having a boiling-point below 100 DEG  C. such as acetone, benzene, ethyl acetate, methylene chloride, ethylene dichloride, methyl alcohol, ethyl alcohol, chloroform, and mixtures of these solvents.  The medium boiling solvents (boiling-points between 100 DEG  and 125 DEG  C.) and high boiling solvents (boiling-points between 125 DEG  and 225 DEG  C. or over) include ethyl lactate, ethyl oxybutyrate, diacetone alcohol, benzyl alcohol, monomethyl ether of ethylene glycol, tetrachlorethane, butyl acetate, butyl alcohol, butyl propionate, amyl acetate, amyl alcohol or mixtures of such solvents.  From 1-2 per cent or more of medium and/or high boiling solvents may be added to the solutions, which may comprise any cellulose derivative such as the nitrate or preferably, organic esters of cellulose or cellulose ethers such as the acetate, formate, propionate or butyrate or ethyl, methyl or benzyl cellulose.  If more than 25-30 per cent of high boiling solvents are employed, drying of the films at a temperature of 30-35 DEG  C. may be necessary.  The solutions may contain plastifiers such as camphor, triacetin, diethyl tartrate, dibutyl tartrate, diethyl phthalate, diphenylol propane, &c.  Also resins particularly synthetic resins such as phenol aldehyde resin, diphenylol propane-formaldehyde resin, diphenylol propane-acetone resin, toluene sulphonamide-formaldehyde resin and lactic acid resin. Stabilizers such as urea and/or pigments may be added and for making laminated glass the combination should be light-fast.  The solutions may be applied to a polished surface of glass or nickel by brushing, spraying, flowing or dipping and the dried coating may be stripped from the surface.  For making splinterless glass the coatings may be built up on adhesive-coated glass to obtain the desired thickness. In some cases, the evaporation of the solvent may be retarded by placing the coated surface in a confined space.  The sheets may be mounted between glass plates coated with an adhesive such as gelatine, a vinyl acetate resin or the above-mentioned synthetic resins particularly as described in Specification 347,646.  If the films are built up on the glass, two such coated sheets may be pressed together with the film sides in contact or the cellulose film may be built up on one sheet and an adhesive-coated glass sheet placed and pressed thereon.  The cellulose solutions are preferably filtered as described in the parent Specification and may be treated with oxidizing agents such as nitric acid or hydrogen peroxide as described in Specification 341,890, [Group VIII].  The following example gives parts by weight of a suitable solution for forming the sheets:-Cellulose acetate 10 parts, acetone 35 parts, benzyl alcohol 5 parts, plastifier such as triacetin, diethyl phthalate, diphenylol propane, tricresyl phosphate or mixtures thereof, 1-10 parts.  In a second example the solution contains cellulose acetate 10 parts, acetone 20 parts, benzene 10 parts, diacetone alcohol 10 parts.  A third solution consists of cellulose acetate 10 parts, synthetic resin 25 parts, acetone 20 parts, ethyl lactate 5 parts.  An example containing cellulose nitrate consists of cellulose nitrate 10 parts, plastifier 4 parts, acetone 30 parts, butyl acetate 2 parts, butyl alcohol 2 parts.  The plastifier may be diethyl phthalate, camphor, butyl phthalate or mixtures of these substances.  In another example the solution comprises benzyl cellulose 30 parts, ester gum 5 parts, diethyl phthalate 5 parts, ethyl acetate 60 parts, benzene 20 parts, xylene 20 parts.