Polyvinyl acetal with reduced flowability

Patent metadata

Field	Value
Publication number	US-10875941-B2
Application number	US-201716092069-A
Country	US
Kind code	B2
Filing date	Apr 5, 2017
Priority date	Apr 8, 2016
Publication date	Dec 29, 2020
Grant date	Dec 29, 2020

Abstract

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.

First claim

The invention claimed is:

1. Polyvinyl acetal with a degree of acetalization of 70-84 mol %, having 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.

2. The polyvinyl acetal of claim 1 , wherein continuous syndiotactic sequences of vinyl alcohol groups with 3 members are present in an amount of at least 4.5 mol%, based on the sum of the amounts of vinyl alcohol groups, vinyl acetal groups and vinyl acetate groups in the polyvinyl acetal.

3. The polyvinyl acetal of claim 1 , having a molar ratio of the amount of continuous sequences of vinyl alcohol groups with 5 members with a stereochemical sequence of mrrm of less than 0.3 based on the total amount of continuous syndiotactic sequences of vinyl alcohol groups with 3 members in the polyvinyl acetal.

4. The polyvinyl acetal of claim 2 , having a molar ratio of the amount of continuous sequences of vinyl alcohol groups with 5 members with a stereochemical sequence of mrrm of less than 0.3 based on the total amount of continuous syndiotactic sequences of vinyl alcohol groups with 3 members in the polyvinyl acetal.

5. The polyvinyl acetal of claim 1 , having a molar ratio of the amount 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.

6. The polyvinyl acetal of claim 1 , having an OH blockiness of the polyvinyl acetal, defined as a quotient VV(VB+BB) of more than 0.35, wherein VV is the amount of methylene groups of two adjacent alcohol sequences, VB is the amount of methylene groups adjacent to an alcohol and an acetal sequence and BB is the amount of methylene groups of two adjacent acetal sequences.

7. The polyvinyl acetal of claim 1 , having a solution viscosity in a 5% by weight solution in ethanol of more than 90 mPas.

8. The polyvinyl acetal of claim 1 , wherein the process of producing the polyvinyl acetal is carried out in the absence of emulsifiers or surfactants.

9. The polyvinyl acetal of claim 1 , having a residual acetate content of 0.1 to 8 mol %.

10. The polyvinyl acetal of claim 1 , having a polymerisation degree of less than 2500.

11. A process for preparing a polyvinyl acetal of claim 1 , by acid-catalysed reaction of at least one polyvinyl alcohol with at least one aldehyde, comprising the following process steps:
a) acetalizing by reacting the polyvinyl alcohol with the aldehyde at a temperature of 0 to 30° C. by addition of an acid catalyst, whereas the ratio of acid catalyst to the polyvinyl alcohol to be acetalized is at least 7.5 mol H+ per kg of the polyvinyl alcohol,
b) completing the acetalizing by heating the reaction mixture of a) after complete dosage of the acid catalyst, to 69° C. to 80° C. and maintaining within this temperature range for at least 180 min,
c) cooling the reaction mixture of b) to 15 to 45° C. and separating the polyvinyl acetal, and
d) neutralising the polyvinyl acetal separated from the reaction mixture.

12. The process of claim 11 , wherein the polyvinyl acetal precipitates during step a) and at least 5% of the acid catalyst is added before the beginning of the precipitation of the polyvinyl acetal.

13. The process of claim 11 , wherein the temperature in process step a) is maintained over a period of at least 20 min.

14. The process of claim 11 , wherein the temperature in process step b) is maintained over a period of at least 210 min.

15. The process of claim 11 , which is conducted in the absence of emulsifiers or surfactants.

16. A Film comprising 0 -42 weight % plasticizer and 100-58 weight % of at least one polyvinyl acetal of claim 1 .

17. A Film comprising 0-42 weight % plasticizer and 100-58 weight % of at least one polyvinyl acetal produced by the process of claim 11 .

Assignees

• Kuraray Europe Gmbh

Inventors

• Steuer Martin
• Wenzlik Daniel
• Kusudo Takeshi
• Keller Uwe

Classifications

• B32B17/10761

  containing vinyl acetal · CPC title

• C08F216/34 Primary

  by an aldehydo radical · CPC title

• C08F8/28

  Condensation with aldehydes or ketones · CPC title

• C08F16/38 Primary

  by an acetal or ketal radical · CPC title

• C08J2329/14

  Homopolymers or copolymers of acetals or ketals obtained by polymerisation of unsaturated acetals or ketals or by after-treatment of polymers of unsaturated alcohols · CPC title