Patent GB-347648-A (GB)
Title: Improvements in or relating to the manufacture of composite articles
IPC: B32B17/08
Filed: 1929-10-21
Abstract: In making laminated glass, a strengthening layer having a basis of cellulose or cellulose derivative is secured between glass sheets by means of adhesive layers of less than ,001\yF thickness.  The adhesive layer may be applied either to the glass or to the strengthening layer or to both and the assembly completed by heat and pressure.  The adhesive may be gelatine in aqueous or other solution or partly or completely polymerized vinyl compound or, preferably, a resin.  Either natural resin, semisynthetic resin such as an ester gum or a synthetic resin may be employed.  Suitable synthetic resins are fusible and soluble phenol formaldehyde resin prepared in the presence of an acid catalyst or a resin as described in Specification 296,675, [Class 2 (iii), Dyes &c.], prepared by condensing a phenol or cresol with formaldehyde, paraformaldehyde or acetaldehyde in the presence of p  phosphoric acid or an acid phosphate.  The resin may also be made by the condensation of diphenylol propane and an aldehyde (as described in Specification 299,065, [Class 2 (iii), Dyes &c.]) or a ketone (as described in Specification 299,066, [Class 2 (iii), Dyes &c.].  Other suitable resins are lactic acid resin obtained by heating lactic acid under reflux, toluene sulphonamide-aldehyde resins, benzene sulphonamide-aldehyde resins, xylene sulphonamide-aldehyde resins, ethyl toluene sulphonamide-aldehyde resins, &c.  The adhesive coatings should also preferably contain derivatives of cellulose and may contain other resins, plasticizers or softening agents, dyes and/or stabilizers. The adhesive layer is applied so as to form films of the order of ,00005\yF, ,0001\yF, ,0002\yF, or ,0005\yF thickness by using solutions of about 1-5 per cent concentration of film-forming material.  The thin adhesive films permit the use of resins which are too dark in colour to be used in a film of usual thickness.  The cellulosic material of the strengthening layer may be reconstituted cellulose made from viscose or a derivative such as cellulose nitrate or organic derivatives including such esters as cellulose acetate, formate, propionate, or butyrate or ethers such as ethyl, methyl or benzyl cellulose. The layers may contain plasticizers such as camphor, triacetin, diethyl tartrate, dibutyl tartrate, &c., and also pigments and/or dyes and stabilizers such as urea.  Instead of using a sheet of material for the strengthening layer this layer may be built up on the adhesive coated glass by applying coatings of a solution of cellulosic material with or without resin until a film of sufficient thickness is formed.  The cellulose derivatives employed are preferably purified by filtration or are treated either in solid form or in solution with oxidizing agents such as hydrogen peroxide or nitric acid.  The following is an example giving parts by weight of a solution of adhesive where the reinforcing layer is cellulose acetate.  Synthetic resin compatible with cellulose acetate such as phenol-formaldehyde toluene sulphonamide formaldehyde or lactic acid resins 5 parts, acetone 100 parts.  If the plastic layer is cellulose nitrate the adhesive solution may consist of ester gum 5 parts, acetone 100 parts, benzene 50 parts.  In the following example the adhesive solution contains cellulose derivative-cellulose acetate 2 parts synthetic resin 2 parts, acetone 100 parts.  Another adhesive solution containing a plasticizer may comprise cellulose acetate 2 parts, synthetic resin 3 parts, triacetin 2 parts, acetone 50 parts, alcohol 25 parts, benzene 25 parts, ethyl lactate 5 parts. Another adhesive solution containing cellulose nitrate consists of cellulose nitrate 1,1 parts camphor, ,4 parts, toluene sulphonamide formaldehyde resin 1,5 parts, benzene 40 parts ethylalcohol 30 parts, butyl alcohol 10 parts, butyl acetate 10 parts, ethylacetate 60 parts.  The adhesive solution may be applied by flowing, spraying, dipping or brushing.  In some cases two or more coats of the same or different compositions may be applied.  The first coat preferably contains a larger proportion of synthetic resin and succeeding coatings have less resin and more cellulose derivative and/or plasticizer.  The adhesive coating may be dried for 15-60 minutes at 50-100 DEG  C. or for a longer period at ordinary temperature.