Patent GB-1006401-A (GB)
Title: Polyvinyl butyral sheeting
IPC: B32B27/36
Filed: 1964-08-04
Abstract: 1,006,401. Polyvinyl butyral films; laminates. E.I. DU PONT DE NEMOURS & CO. Aug. 4, 1964 [July 22, 1963], No. 30651/64. Headings B5B and B5N Plasticized polyvinyl butyral sheeting, at least one surface of which has a normalized adhesion to glass of from 1 to 9 pounds of pull per 3 cms. at a moisture content of 0À3% water by weight of the plasticized sheeting, has a tensile strength of 2500 to 6000 p.s.i. and a blocking that varies with sheeting thickness in accordance with the equation: where B = blocking in pounds, e = base of natural logarithms, t = sheeting thickness in mils. Such sheeting may have a normalized adhesion to glass of 1 to 9 pounds per 3 cms. throughout the moisture content range of 0À2 to 1À4% water by weight of the plasticized sheeting. Such sheeting may be treated so that both surfaces have a normalized adhesion to glass of from 1 to 9 pounds pull per 3 cms. at a moisture content of 0À3% water by weight of plasticized sheeting and, when laminated to glass under the conditions specified by the headform impact test at a moisture content of 0À3% by weight moisture of plasticized sheeting, the sheeting has a 50% penetration height given by the formula: where pH = 50% penetration height in inches, e = base of natural logarithms, t = sheeting thickness in mils. Such sheeting may have a 50% penetration height throughout the moisture content range of 0À2 to 1À4% water by weight of the plasticized sheeting. Three processes for the treatment of plasticized polyvinyl butyral sheeting to improve its adhesion to glass, yielding a product having the above properties, are disclosed. Thus at least one surface of plasticized polyvinyl butyral sheeting having a tensile strength of 2500 to 6000 p.s.i. may be subjected to a flaming treatment, or to a high voltage electrical discharge, or to infrared radiation treatment. Specified plasticizers include triethylene glycol-di-2-ethyl butyrate; dibutyl sebacate; dibutyl " Cellosolve " (Trade Mark) adipate and triethylene glycol dihexoate. The plasticized sheeting to be treated may contain colouring matter, and its surface or surfaces prior to treatment may be coated with sodium bicarbonate powder, or diatomaceous earth, the weight of the powder being less than 15% by weight of the powdered sheeting. The flaming treatment may be effected with a flame produced by burning a mixture comprising a hydrocarbon fuel gas or natural gas and an oxygen-containing gas, the sheeting being passed over and supported by a rotatable roll as the sheeting is passed through the flame, the roll being cooled to below 80‹ C., and above the dewpoint of the surrounding atmosphere. Preferably, the distance between the surface of the sheeting and the face of the burner from which the flame is emerging is greater than onehalf the length of the undisturbed inner cone of the flame and less than the length of the outer luminous cone of the flame, the speed of the sheeting treated being 2 to 1,000 ft. per minute. Where the sheeting is subjected to high-voltage discharge, it may be subjected to from 0À1 to 8 watt hours of energy per square foot of surface, especially 0À2 to 2À6 watt hours per square foot and the sheeting moved at 2 to 500 ft. per minute during the treatment, and spaced at a distance of 10 to 100 mils. from at least one electrode. Where the sheeting is subjected to infra-red radiation, this may be provided by a 1500 watt heater spaced from the sheeting about 1¢ inches, treatment being carried out for from 0À5 to 10 minutes. Glass laminates may be made containing the plasticized polyvinyl butyral sheeting, such laminates being useful as windshields. A laminate used in testing the adherence of the treated polyvinyl butyral to glass is made by placing a strip of polyethylene terephthalate on a clear glass sheet and placing a polyvinyl butyral sheet on the glass so as to overlap the polyethylene terephthalate, covering this with a layer of polyethylene terephthalate film and then placing a sheet of glass over the latter film (Fig. IIE). Specifications 566,004, 842,438, and U.S.A. Specifications 2,442,754, 3,008,855 and 3,068,525 are referred to.