Polymer-coated cellulosic release liner base material

Patent metadata

Field	Value
Publication number	US-2024279513-A1
Application number	US-202018024533-A
Country	US
Kind code	A1
Filing date	Sep 17, 2020
Priority date	Sep 17, 2020
Publication date	Aug 22, 2024
Grant date	—

Abstract

The invention relates to a polymer-coated cellulosic substrate (S2) for a release liner (REL1), comprising a cellulosic support layer (PAP1), a first coating layer (PO1), comprising a first composition containing polyolefin, and an extruded primer layer (PRIM1) comprising a second composition containing a thermoplastic polymer covalently bonded to functional vinyl groups: wherein the first coating layer (POI) is situated between the cellulosic support layer (PAP1) and the extruded primer layer (PRIM1).

First claim

1 . A polymer-coated cellulosic substrate for a release liner, comprising
a cellulosic support layer, a first coating layer (PH comprising a first composition containing polyolefin, an extruded primer layer comprising a second composition containing a thermoplastic polymer covalently bonded to functional vinyl groups;
wherein the first coating layer is situated between the cellulosic support layer and the extruded primer layer.

2 . The polymer-coated cellulosic substrate according to claim 1 , further comprising
a tie layer between the first coating layer and the extruded primer layer.

3 . A method for manufacturing a polymer-coated cellulosic substrate for a release liner, said method comprising
providing a cellulosic support layer, extruding a molten first composition containing polyolefin, thereby obtaining an extruded first composition, extruding a molten second composition comprising a thermoplastic polymer covalently bonded to functional vinyl groups, thereby obtaining an extruded second composition, allowing the temperature of the extruded molten first composition to decrease below its melting point thereby forming a first coating layer, allowing the temperature of the extruded molten second composition to decrease below its melting point thereby forming an extruded primer layer, and forming the polymer-coated cellulosic substrate, comprising the cellulosic support layer, extruded primer layer, and the first coating layer situated between the cellulosic support layer and the extruded primer layer.

4 . The method according to claim 3 , further comprising
extruding a third composition comprising a compatibilizer, thereby obtaining an extruded third composition, and allowing the temperature of the extruded molten third composition to decrease below its melting point, thereby forming a tie layer, such that the tie layer is situated between the first coating layer and the extruded primer layer.

5 . The method according claim 3 , wherein
at least two of the molten compositions are co-extruded.

6 . The method according to claim 3 , wherein the thermoplastic polymer covalently bonded to functional vinyl groups is a reaction product, of a molten thermoplastic and a grafting agent containing functional vinyl groups.

7 . The method according claim 3 , wherein
the thermoplastic polymer covalently bounded to vinyl groups has been formed from a thermoplastic poly(vinyl alcohol) (PVA).

8 . The method according claim 3 , wherein
the thermoplastic polymer covalently bounded to vinyl groups comprises ester bonded pendant chains of which at least some end into vinyl groups, wherein the pendant chains which end into vinyl groups contain a catenated carbon structure of at least 4 carbon atoms, the extruded primer layer further comprises carboxylic acid residue, wherein the carboxylic acid residue is organic compound that contains the same kind of catenated carbon structures of at least 4 carbon atoms that end into vinyl group as the pendant chains of the thermoplastic polymer covalently bounded to vinyl groups.

9 . The method according to claim 3 , wherein
the second composition further comprises
one or more plasticizers, and/or
non-thermoplastics.

10 . The method according claim 3 , wherein
the tie layer comprises polyolefin grafted with maleic anhydride, acrylic acid, or glycidyl methacrylate.

11 . (canceled)

12 . The method according to claim 3 , wherein the extruded primer layer has at least one of the following properties:
the PPS roughness value is less than 2 μm, the extruded primer layer comprising thermoplastic polymer covalently bound to functional vinyl groups has a coat weight of at least 0.6 g/m 2 , the extruded primer layer (PRIM H) contains functional vinyl groups in an amount of at least 0.06 mmol/m 2 , the thermoplastic polymer contains a vinyl group molality b vin which is in the range of 0.05 mmol/g to 2.00 mmol/g determined as millimoles per gram of dry thermoplastic polymer, when determined by iodometric titration method following the standard ISO 3961:2009(E).

13 . The method according claim 3 , wherein
the first coating layer comprises polypropylene, or polyethylene.

14 . The method according to claim 3 , wherein
the first coating layer comprises a polypropylene, and the tie layer comprises polyethylene grafted with maleic anhydride.

15 . The method according to claim 3 , further comprising,
prior to extruding the molten second composition
reacting a molten thermoplastic and a grafting agent containing functional vinyl groups, preferably in a solvent-free reaction, thereby obtaining the second composition being a thermoplastic polymer covalently bonded to functional vinyl groups.

16 . The method according to claim 15 , wherein
the step of reacting a molten thermoplastic and a grafting agent containing functional vinyl groups comprising:
heating thermoplastic poly(vinyl alcohol) having hydroxyl groups, wherein the thermoplastic poly(vinyl alcohol) has been dried and has a degree of hydrolysis in the range of 65 to 95 mol-%, and
admixing grafting agent with the thermoplastic poly(vinyl alcohol), wherein said grafting agent is an organic acid anhydride having at least a chain which has a catenated carbon structure of at least 4 carbon atoms and which ends into a vinyl group,
such that a mixture is obtained which contains molten thermoplastic poly(vinyl alcohol) having hydroxyl groups and organic acid anhydride which contains chains which end into vinyl groups, and
mixing the mixture at a temperature which is above the melting point of the mixture, thereby causing a reaction in a melt state, wherein at least some of the organic acid anhydride reacts with the hydroxyl groups of the thermoplastic poly(vinyl alcohol) in an ester bond forming condensation reaction,
such that reaction product, being the second composition, is formed which contains
carboxylic acid residue of the ester bond forming condensation reaction, wherein at least some of said carboxylic acid residue contains chains which end into vinyl groups, and
thermoplastic poly(vinyl alcohol) derivative which contains ester bonded pendant chains of which at least some end into vinyl groups.

17 . A release liner comprising
the polymer-coated cellulosic substrate according to claim 1 and a silicone coating layer on top of the polymer-coated cellulosic substrate.

18 . The polymer-coated cellulosic substrate according to 1, wherein the thermoplastic polymer covalently bonded to functional vinyl groups is a reaction product of a molten thermoplastic and a grafting agent containing functional vinyl groups.

19 . The polymer-coated cellulosic substrate according claim 1 , wherein the thermoplastic polymer covalently bounded to vinyl groups has been formed from a thermoplastic poly(vinyl alcohol).

20 . The polymer-coated cellulosic substrate according to claim 1 , wherein the thermoplastic polymer covalently bounded to vinyl groups comprises ester bonded pendant chains of which at least some end into vinyl groups, wherein the pendant chains which end into vinyl groups contain a catenated carbon structure of at least 4 carbon atoms.

21 . The polymer-coated cellulosic substrate according to claim 1 , wherein the second composition further comprises
one or more plasticizers, and/or a non-thermoplastic.

22 . The polymer-coated cellulosic substrate according to claim 1 , wherein the tie layer comprises polyolefin graf

Assignees

• Upm Kymmene Corp

Inventors

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

Classifications

• C09J2423/105

  in the release coating · CPC title

• C09J2301/41

  additives as essential feature of the carrier layer · CPC title

• C09J2301/50

  characterized by process specific features · CPC title

• C09J2301/312

  parameters being the characterizing feature · CPC title

• C09J7/401

  characterised by the release coating composition · CPC title