PVB Film for Composite Safety Glass and Composite Safety Glass
Composite glass with films based on partially acetalated polyvinyl alcohol containing a softening agent, especially PVB based, as an intermediate layer with magnesium salts or calcium salts of organic acids as an adhesion-reducing additive (anti-adhesive agent) exhibit large amounts of fluctions with regard to adhesion when the composite glass is subjected to thermal stress. According to the invention, phosphorous compounds are used, selected from the group consisting of organophosphites i.e. esters of phosphorinic acid with organic radicals, organophosphates, i.e. esters of orthonophosphoric acid, as an additive which during further processing compensates for fluctations in adhesion in films based on partially acetalated polyvinyl alcohol containing a softening agent. The invention is used in the production of films for the manufacture of safety glass, especially used in the building and automotive industry.
1 . A film based on plasticized partially acetalized polyvinyl alcohol for use as intermediate layer in laminated safety glass, comprising
from 0.001 to 0.25% by weight, based on the entire film mixture, of one or more additives which reduce adhesion of the film to a glass surface, these having been selected from the group consisting of
magnesium salts of organic acids,
potassium salts of organic acids,
and an additive compensating for adhesion variations and comprising one or more phosphorus compounds selected from the group consisting of
organophosphites, i.e. esters of phosphorous acid with organic residues,
organophosphates, i.e. esters of orthophosphoric acid with organic residues,
where the amount added of the phosphorus compounds is such that
the pummel value, as defined in the description, of a laminated glass produced using the film as intermediate layer, after
the 90 min standard autoclave process,
after the 330 min long autoclave process, and—after heat-aging for 72 hours at 125° C.
is > — 1.5 and < — 8 on each of the two glass sides, and
the maximum A-pummel value, as defined in the description, is < — 2.5.
2 . The film as claimed in claim 1 , characterized in that the additive used which reduces adhesion of the film to a glass surface comprises magnesium 2-ethylhexanoate at a concentration of from 0.001 to 0.2% by weight, based on the entire film mixture.
3 . The film as claimed in claim 2 , characterized in that the plasticizer used comprises 3G8, 3G7, and/or DHA, and in that the amount used of the magnesium 2-ethylhexanoate is
from 0.01 to 0.1% by weight, if 3G8 is used as plasticizer,
from 0.005 to 0.05% by weight, if 3G7 is used as plasticizer
from 0.005 to 0.05% by weight, if DHA is used as plasticizer
an appropriate intermediate amount of magnesium 2ethylhexanoate, if use is made of a plasticizer mixture,
based in each case on the entire film mixture.
4 . The film as claimed in claim 1 characterized in that the additive used compensating for adhesion variations comprises one or more phosphites from the group consisting of tris(nonylphenyl) phosphite, triphenyl phosphite and diphenyl octyl phosphite in a concentration of from 0.05 to 0.5% by weight.
5 . The film as claimed in claim 1 characterized in that the additive used compensating for adhesion variations comprises tris(nonylphenyl) phosphite, triphenyl phosphite and/or diphenyl octyl phosphite in a concentration of from 0.1 to 0.2% by weight.
6 . A laminate, encompassing at least one silicate glass layer, and also a film as claimed in claim 1 .
7 . The use of phosphorus compounds, selected from the group consisting of
organophosphites, i.e. esters of phosphorous acid with organic residues,
organophosphates, i.e. esters of orthophosphoric acid with organic residues, as additive compensating for the variations in adhesion during further processing, in films based on plasticized partially acetalated polyvinyl alcohol.