Compound safety glass and PVB foil for the production thereof

A sound-insulation film for producing laminated safety glass, comprising:

• from 50 to 80% by weight of partially acetalized polyvinyl alcohol, and
• from 20 to 50% by weight of a plasticizer mixture comprising a first plasticizer and one or more polyalkylene glycols, wherein from 30 to 70% by weight of said plasticizer mixture is said one or more polyalkylene glycols, and said one or more polyalkylene glycols are selected from:
• polyalkylene glycols of the general formula HO—(R—O)n—H, wherein R is alkylene and n>5;
• block copolymers of ethylene glycol and propylene glycol of the formula HO—(CH2—CH2—O)n—(CH2—CH(CH3)—O)m—H, wherein n>2, m>3, and (n+m)<25;
• derivatives of block copolymers of ethylene glycol and propylene glycol of the formula R1O—(CH2—CH2—O)n—(CH2—CH(CH3)—O)m—H or HO—(CH2—CH2—O)n—(CH2—CH(CH3)—O)m—R1, wherein n>2, m>3, and (n+m)<25 and R1 is an organic radical;
• derivatives of polyalkylene glycols of the formula R1—O—(R2—O)n—H, wherein R2 is alkylene and n≧2, and R1 is an organic radical;
• and
• derivatives of polyalkylene glycols of the formula R1—O—(R2—O)n—R3, where R2 is alkylene and n>5, ands R1 and R3 are each an organic radical.

A process for improving sound insulation in laminated safety glass containing a film of plasticized partially acetalized polyvinyl alcohol resin, said process comprising adding to said resin at least one polyalkylene glycol whereby sound insulation is increased by at least 2 dB, measured according to DIN EN ISO 717, in the coincidence frequency region from 1000 to 3500 Hz, wherein said at least one polyalkylene glycol is selected from:

• polyalkylene glycols of the formula HO—(R—O)n—H, wherein R is alkylene and n>5:
• block copolymers of ethylene glycol and propylene glycol of the formula HO—(CH2—CH2—O)n—(CH2—CH(CH3)—O)m—H, where n>2, m>3, and (n+m)<25;
• derivatives of block copolymers of ethylene glycol and propylene glycol of the formula R1O—(CH2—CH2—O)n—(CH2—CH(CH3)—O)m—H or HO—(CH2—CH2—O)n—(CH2—CH(CH3)—O)m—R1, wherein n>2, m>3, and (n+m)<25 and R1 is an organic radical;
• derivatives of polyalkylene glycols of the formula R1—O—(R2—O)n—H, wherein R2 is alkylene and n≧2, and R1 is an organic radical;
• and
• derivatives of polyalkyle glycols of the formula R1—O—(R2—O)n—R3, where R2 is alkylene and n>5, ands R1 and R3 are each an organic radical.