Kuraray Europe Gmbh

Daniel Wenzlik

Uwe Keller

Martin Steuer

Takeshi Kusudo

Philipp Lellig

Michael Haerth

Michael HäRTH

Plasiticized polyvinylacetal films with greater film-to-film uniformity are produced by a process of extruding a melt stream containing a polyvinyl acetal and a plasticizer at 150-250&#xb0; C., the film having a predefined melt viscosity at 60-170&#xb0; C., by providing a first melt stream of at least a first plasticizer and a first polyvinyl acetal resin and measuring its melt viscosity at 60-170&#xb0; C. online; and adjusting the 60-170&#xb0; C. melt viscosity by adding a second plasticizer and/or a second polyvinyl acetal resin to the first melt stream in an amount to provide a second melt stream with a melt viscosity at 60-170&#xb0; C. having a difference of at most 20% to the predefined melt viscosity at 60-170&#xb0; C.

Method for producing films based on plasticized polyvinyl acetal having a predefined viscosity

Polyvinyl acetals with a degree of acetalization of 70-84 mol %, and characterized by a molar ratio of the amount of continuous syndiotactic sequences of vinyl alcohol groups with 3 members of at least 0.152, based on the total amount of vinyl alcohol groups in the polyvinyl acetal, have exceptionally low melt flow.

Polyvinyl acetal with reduced flowability

A multilayer laminating film contains at least one first and one second layer of plasticized polyvinyl acetal, wherein the first layer comprises a first plasticizer and a first polyvinyl acetal with a degree of acetalization of 75.1-84.0 mol % and a molar ratio of continuous sequences of vinyl alcohol groups with 5 members with a stereochemical sequence of rrrr of more than 0.23 based on the total amount of continuous syndiotactic sequences of vinyl alcohol groups with 3 members in the polyvinyl acetal, and the second layer comprises a second plasticizer and a second polyvinyl acetal with a degree of acetalization of 60-84 mol %.

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Wiesbaden, Germany

Daniel Wenzlik