Protective films made of polyolefin support material, primer and radiation-crosslinkable hot melt adhesive

Patent metadata

Field	Value
Publication number	US-12305090-B2
Application number	US-201816649886-A
Country	US
Kind code	B2
Filing date	Sep 28, 2018
Priority date	Oct 11, 2017
Publication date	May 20, 2025
Grant date	May 20, 2025

Abstract

Described herein is a protection film comprising a polyolefin carrier material, a precoating of the polyolefin carrier material with a primer selected from polyurethane dispersions and a pressure-sensitive adhesive layer of a radiation-crosslinked hotmelt adhesive. A process for producing such protection films is also described.

First claim

The invention claimed is:

1. A removable protection film comprising:
(a) a polyolefin carrier material whose surface to be coated has been pretreated, wherein the carrier material is selected from the group consisting of polyethylene and polypropylene,
(b) a precoating of the polyolefin carrier material with at least one primer selected from aqueous polyurethane dispersions, the aqueous polyurethane dispersions consisting of a polyurethane dispersed in an aqueous solvent; and
(c) a pressure-sensitive adhesive layer, wherein the pressure-sensitive adhesive layer is formed by radiation crosslinking of a radiation-crosslinkable hotmelt adhesive and wherein the radiation-crosslinkable hotmelt adhesive comprises at least one poly(meth)acrylate formed from
(i) at least 60% by weight of C4-to C10-alkyl (meth)acrylates and
(ii) at least one ethylenically unsaturated monomer which comprises at least one polar group, wherein the polar group is selected from the group consisting of carboxylic acid groups, carboxylic anhydride groups, hydroxyl groups, amide groups, urethane groups, urea groups, piperidinyl groups, piperazinyl groups, morpholinyl groups, imidazoyl groups, ureido groups, pyrrolidone groups and combinations of two or more of the recited groups;

wherein the at least one poly(meth)acrylate of the radiation-crosslinkable hotmelt adhesive has a K value of at least 30, and wherein before crosslinking the at least one poly(meth)acrylate has a glass transition temperature of not more than 10° C.,
and wherein the radiation-crosslinkable hotmelt adhesive includes at least one photoinitiator and the photoinitiator is in the form of an additive not bonded to the at least one poly(meth)acrylate and/or the photoinitiator is incorporated into the at least one poly(meth)acrylate by polymerization, wherein the removable protection film exhibits a force for removal of the removable protection film from brushed steel of not more than 5 N/25 mm at 23° C.

2. The protection film according to claim 1 , wherein the polyurethane of the polyurethane dispersion is constructed from
a) diisocyanates,
b) at least one diol, of which
b1) 10 to 100 mol % based on the total amount of the diols (b) have a molecular weight of 500 to 5000 g/mol and
b2) 0 to 90 mol % based on the total amount of diols (b) have a molecular weight of 60 to 500 g/mol,

c) at least one monomer distinct from the monomers (a) and (b) having at least one isocyanate group or at least one isocyanate-reactive group which further bears at least one hydrophilic group and
d) optionally at least one further compound distinct from the monomers (a) to (c) having at least two reactive groups selected from alcoholic hydroxyl groups, primary or secondary amino groups or isocyanate groups and
e) optionally at least one monofunctional compound distinct from monomers (a) to (d) having a reactive group which is an alcoholic hydroxyl group, a primary or secondary amino group or an isocyanate group.

3. The protection film according to claim 2 , wherein
the diisocyanates a) are selected from diisocyanates of the formula X(NCO) 2 , wherein X represents an acyclic aliphatic hydrocarbon radical having 4 to 15 carbon atoms, a cycloaliphatic hydrocarbon radical having 6 to 15 carbon atoms, an aromatic hydrocarbon radical having 6 to 15 carbon atoms or an araliphatic hydrocarbon radical having 7 to 15 carbon atoms;
the diols b1) are selected from polyester diols, polycarbonate diols and polyether diols; and the compound c) is selected from dihydroxycarboxylic acids, diaminocarboxylic acids and diaminosulfonic acids.

4. The protection film according to claim 1 , wherein the polyurethane comprises anionic groups, and wherein a content of anionic groups in the polyurethane is 30 to 1000 mmol/kg of polyurethane.

5. The protection film according to claim 1 , wherein the polyurethane of the polyurethane dispersion is formed using at least one amorphous polymeric polyester polyol.

6. The protection film according to claim 5 , wherein the at least one amorphous polyester polyol is constructed from a mixture of at least one aliphatic dicarboxylic acid having 3 to 10 carbon atoms and at least one aromatic dicarboxylic acid in a ratio of 0.5:1 to 2:1 and at least one alkanediol having 2 to 10 carbon atoms.

7. The protection film according to claim 6 , wherein the amorphous polyester is constructed from a mixture of an at least one aliphatic dicarboxylic acid having 3 to 10 carbon atoms and at least one aromatic dicarboxylic acid in a ratio of 0.5:1 to 2:1 and at the least one alkanediol having 4 to 8 carbon atoms.

8. The protection film according to claim 1 , wherein the polyurethane of the polyurethane dispersion comprises 10% to 80% by weight of at least one amorphous polyester diol having a molecular weight of more than 500 and up to 4000 g/mol and the at least one amorphous polyester diol is composed of a mixture of at least one aliphatic dicarboxylic acid having 3 to 10 carbon atoms and at least one aromatic dicarboxylic acid in a ratio of 0.5:1 to 2:1 and at least one alkanediol having 2 to 10 carbon atoms.

9. The protection film according to claim 1 , wherein the polyurethane of the polyurethane dispersion is chain-extended with at least one polyamine.

10. The protection film according to claim 1 , wherein the radiation-crosslinkable poly(meth)acrylate is crosslinkable by irradiation with UV light and the photoinitiator is copolymerized into the radiation-crosslinkable poly(meth)acrylate in the form of an ethylenically unsaturated, copolymerizable photoinitiator in an amount of not less than 0.5% by weight.

11. The protection film according to claim 1 , wherein the radiation-crosslinkable poly(meth)acrylate comprises 0.1% to 30% by weight, from the at least one monomer which comprises at least one polar group.

12. The protection film according to claim 1 , wherein the at least one radiation-crosslinkable poly(meth)acrylate is formed from
(a1) at least 60% by weight of at least one acrylate selected from the group consisting of n-butyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, propylheptylacrylate and mixtures thereof,
(a2) 1% to 5% by weight of at least one monomer having polar groups, wherein the polar groups are selected from the group consisting of carboxylic acid groups, carboxamide groups, pyrrolidone groups, urethane groups and urea groups,
(a3) 0.5% to 4% by weight of at least one ethylenically unsaturated copolymerizeable photoinitiator, and
(a4) 0% to 25% by weight of at least one further monomer distinct from the monomers (a1) to (a3).

13. The protection film according to claim 1 , wherein an application rate of a pressure-sensitive adhesive in the pressure-sensitive adhesive layer (c) is at least 2 g/m 2 .

14. The protection film according to claim 1 , wherein detachment from a substrate takes place by adhesion failure of a radiation-crosslinked adhesive layer, wherein the pressure-sensitive adhesive layer (c) detaches from the substrate and remains entirely on the polyolefin carrier material.

15. The protection film according to claim 1 , wherein the force for removal of the protection film from brushed steel is from 0.5 to 5 N/25 mm at 23° C.

16. A process for producing protection films, comprising:
(1) precoating a polyolefin carrier material whose surface to be coated has been pretreated with at least one primer, wherein the at least one primer is selected from polyurethane dispersions, the aqueous polyurethane dispersions consisting of a polyurethane dispersed in an aqueous solvent, thereby forming a primer layer; and
(2) applying a pressure

Assignees

• Basf Se

Inventors

• Wulff Dirk
• Kern Holger
• Gerst Matthias
• Kiener Christoph

Classifications

• C09J133/08

  Homopolymers or copolymers of acrylic acid esters · CPC title

• C08L75/06

  from polyesters · CPC title

• C09J2301/416

  use of irradiation · CPC title

• C09J7/50

  characterised by a primer layer between the carrier and the adhesive · CPC title

• C09J2423/006

  in the substrate · CPC title