Paper substrate comprising modified low molecular weight PVA with functional vinyl groups

Patent metadata

Field	Value
Publication number	US-11932992-B2
Application number	US-201817280946-A
Country	US
Kind code	B2
Filing date	Oct 9, 2018
Priority date	Oct 9, 2018
Publication date	Mar 19, 2024
Grant date	Mar 19, 2024

Abstract

The invention relates to a method for manufacturing a paper substrate suitable for binding silicone in a catalytic hydrosilation reaction and products thereof, wherein the molecular weight of polyvinyl alcohol is used to control the viscosity of the water-based acetalization reaction, such that a paper substrate may be coated with acetalized polyvinyl alcohol that contains high amount of functional vinyl groups, wherein the functional vinyl groups are part of catenated carbon structures which contain at least 4 carbon atoms and which have an acetal connectivity with the backbone chain of the acetalized polyvinyl alcohol.

First claim

The invention claimed is:

1. A paper substrate which is suitable for binding silicone in a catalytic hydrosilation reaction, the paper substrate comprising
a cellulose fiber-based support layer and
a hydrophobic primer layer that contains acetalized polyvinyl alcohol, wherein the acetalized polyvinyl alcohol
has a weight average molecular weight of less than 50000 g/mol, and
contains a vinyl group molality which is equal to or higher than 0.2 millimoles per gram of the acetalized polyvinyl alcohol, and wherein
the functional vinyl groups are part of catenated carbon structures which contain at least 4 carbon atoms, and which have an acetal connectivity with the backbone chain of the acetalized polyvinyl alcohol.

2. The paper substrate according to claim 1 , wherein the catenated carbon structure is a linear hydrocarbon that terminates into a functional vinyl group at the other end of the chain.

3. The paper substrate according to claim 1 , wherein the catenated carbon structures contain at least 5 carbon atoms.

4. The paper substrate according to claim 1 , wherein the vinyl group molality of the acetalized polyvinyl alcohol is equal to or higher than 0.23 millimoles per gram of the acetalized polyvinyl alcohol.

5. The paper substrate according to claim 1 , wherein the vinyl group molality of the acetalized polyvinyl alcohol is in the range of 0.20 to 1.41 millimoles per gram of the acetalized polyvinyl alcohol.

6. The paper substrate according to claim 1 , wherein the cellulose fiber-based support layer is made of bleached chemical pulp.

7. A method for manufacturing a paper substrate which is suitable for binding silicone in a catalytic hydrosilation. reaction, the method comprising steps of
dissolving polyvinyl alcohol which has a weight average molecular weight of less than 50000 g/mol and degree of hydrolysis in the range of 70% to 99% into water, thereby obtaining a water-based solution containing dissolved polyvinyl alcohol,
adding reactant which is an organic molecule that contains a catenated carbon structure having at least 4 carbon atoms, an aldehyde group and a functional vinyl group into the water-based solution containing the dissolved polyvinyl alcohol, thereby obtaining a reaction mixture
reacting the reactant with the dissolved polyvinyl alcohol in a water-based acetalization reaction, thereby forming acetalized polyvinyl alcohol which contains functional vinyl groups, wherein the functional vinyl groups are part of catenated carbon structures which contain at least 4 carbon atoms, and which have an acetal connectivity with the backbone chain of the acetalized polyvinyl alcohol, and
coating a cellulose fiber-based support layer with the acetalized polyvinyl alcohol, thereby forming a hydrophobic primer layer and the paper substrate, wherein the vinyl group molality of the acetalized polyvinyl alcohol is equal to or higher than 0.2 millimoles per grain of the acetalized polyvinyl alcohol.

8. The method according to claim 7 , wherein the viscosity of the reaction mixture containing the acetalized polyvinyl alcohol is less than 8000 mPa s after the water-based acetalization reaction.

9. The method according to claim 7 , further comprising
removing unreacted reactant from the reaction mixture containing acetalized polyvinyl alcohol.

10. The method according to claim 7 , wherein the dry matter content of the polyvinyl alcohol in the water-based solution is equal to or higher than 25 wt.-% .

11. The method according to claim 7 , wherein the polyvinyl alcohol is partially hydrolyzed, such that the degree of hydrolysis of the polyvinyl alcohol is less than 97%.

12. The method according to claim 7 , wherein the polyvinyl alcohol is fully hydrolyzed, such that the degree of hydrolysis of the polyvinyl alcohol is equal to or more than 97%.

13. The method according to claim 7 , wherein the organic molecule is 10-undecenal or 2,2′-dimethyl-4-pentenal.

14. The method according to claim 7 , wherein the acetalized polyvinyl alcohol has a weight average molecular weight of less than 5000 g/mol.

15. The method for manufacturing a paper substrate according to claim 7 , wherein the catenated carbon structure is a linear hydrocarbon that terminates into a functional vinyl group at the other end of the chain.

16. The method for manufacturing a paper substrate according to claim 7 , wherein the catenated carbon structures contain at least 5 carbon atoms.

17. The method for manufacturing a paper substrate according to claim 7 , wherein the vinyl group molality of the acetal.ized polyvinyl alcohol is equal to or higher than 0.23 millimoles per gram of the acetalized polyvinyl alcohol.

18. The method for manufacturing a paper substrate according to claim 7 , wherein the vinyl group molality of the a.cetaliz,ed polyvinyl alcohol is in the range of 0.20 to 1.41 m millimoles per gram of the acetalized polyvinyl alcohol.

19. The method for manufacturing a paper substrate according to claim 7 , wherein the cellulose fiber-based support layer is made of bleached chemical pulp.

20. A release liner which comprises a paper substrate according to claim 1 and a release layer based on a silicone compound that has been applied on the paper substrate.

Assignees

• Upm Kymmene Corp

Inventors

• Kosonen Harri
• Rissanen Mikko
• Littunen Kuisma
• Rautalahti Jaakko
• Antila Janne

Classifications

• D21H19/72 Primary

  Coated paper characterised by the paper substrate · CPC title

• C09D129/14

  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

• C09D183/04

  Polysiloxanes · CPC title

• D21H19/20

  comprising macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds · CPC title

• D21H19/32

  obtained by reactions forming a linkage containing silicon in the main chain of the macromolecule · CPC title