Patent GB-341891-A (GB)
Title: Improvements in or relating to the manufacture of laminated glass
IPC: B32B17/10
Filed: 1929-10-21
Abstract: A glass sheet is united to a strengthening sheet having a basis of cellulose derivative and containing triacetin by means of an adhesive comprising a wholly or partly polymerized vinyl compound. For making laminated glass a strengthening sheet comprising triacetin with cellulose nitrate or organic derivatives of cellulose such as cellulose acetate, formate, propionate or butyrate, or ethyl, methyl or benzyl cellulose is interposed between glass sheets.  The strengthening sheets may contain plasticizers such as diethyl tartrate, dibutyl tartrate, diethyl phthalate, pigments or dyes and stabilizers such as urea.  In some cases instead of using strengthening material in sheet form, a glass sheet may be first coated with adhesive as described below, and the strengthening layer built up by applying coatings of cellulose derivative solutions.  The adhesive may be any compound having the CH2CH group therein such as vinyl acetate, vinyl alcohol, vinyl chloroacetate, styrene &c. and the polymerization may be effected either before or after the application of the adhesive layer.  Polymerization may be effected by sunlight ultra-violet light or by heating with catalysts such as hydrogen peroxide, borax or uranium salts.  When polymerization is only partially completed, complete polymerization may be effected at any desired stage in the manufacture of the laminated glass or the finished glass may be subjected to ultra-violet light to complete polymerization.  Either 40, 60, 80, 100 or 120 parts of triacetin may be mixed with 100 parts of cellulose derivative to form the strengthening layer.  The adhesive layer containing the vinyl compound may also contain natural or synthetic resins, plasticizers including triacetin or softening agents, dyes or stabilizers.  The cellulose derivative solution is preferably filtered or treated with oxidizing agents such as nitric acid or hydrogen peroxide as described in Specification 341,890, [Group iv].  Any suitable glass may be employed.  In one example the adhesive consists of polymerized vinyl acetate 5 parts (by weight), acetone or ethyl acohol 100 parts. Higher boiling solvents may be used as in the following example, polymerized vinyl acetate 5 parts, butyl alcohol 10-30 parts.  The butyl alcohol may be replaced by diacetone alcohol, ethyl lactate &c. A mixture of high and low boiling solvents may be used as in the following example-polymerized vinyl acetate 10 parts, ethyl acetate 20 parts, butyl acetate 10 parts.  The following is an example of a solution of an adhesive also containing a synthetic resin-polymerized vinyl acetate 10 parts, synthetic resin 5 parts, acetone 30 parts, ethyl alcohol 30 parts.  The synthetic resin may be soluble and fusible phenol-formaldehyde prepared in the presence of an acid catalyst or other resin.  The adhesive may be applied by flowing, spraying, dipping, or brushing and in some cases two adhesive coats of the same or different compositions may be employed.  The adhesive may be applied either to the glass alone or to both the glass and the strengthening layer, and is preferably dried at 50 DEG -100 DEG  C. for 15 to 60 minutes or for a longer period at ordinary temperatures. The strengthening sheet is then inserted or built up and the assembly subjected to heat and pressure.