USE OF MELTABLE ACRYLATE POLYMERS FOR PRODUCING CONTACT ADHESIVE LAYERS

• US 20110014404A1
• Filed: 03/30/2009
• Published: 01/20/2011
• Est. Priority Date: 03/31/2008
• Status: Active Grant

• Current Assignee: BASF SE
• Original Assignee: BASF SE
• Inventors: Kirsch, Stefan, Licht, Ulrike, Beyers, Cornelis Petrus
• Granted Patent: US 9,212,291 B2
• Time in Patent Office: Days
• US Class Current: 428/35.7
• CPC Class Codes: B32B 2250/24 All layers being polymeric
• CPC Class Codes: B32B 2255/10 on synthetic resin layer or on natural or synthetic rubber layer
• CPC Class Codes: B32B 2255/26 Polymeric coating
• CPC Class Codes: B32B 2307/31 Heat sealable
• CPC Class Codes: B32B 2307/412 Transparent
• CPC Class Codes: B32B 2307/7242 Non-permeable
• CPC Class Codes: B32B 2307/7265 Non-permeable
• CPC Class Codes: B32B 2307/748 Releasability
• CPC Class Codes: B32B 2435/00 Closures, end caps, stoppers
• CPC Class Codes: B32B 2439/00 Containers; Receptacles closures therefor B32B2435/00
• CPC Class Codes: B32B 2439/70 Food packaging
• CPC Class Codes: B32B 27/08 of synthetic resin
• CPC Class Codes: B32B 27/18 characterised by the use of special additives
• CPC Class Codes: B32B 27/20 using fillers, pigments, thixotroping agents
• CPC Class Codes: B32B 27/302 comprising aromatic vinyl (co)polymers, e.g. styrenic (co)polymers
• CPC Class Codes: B32B 27/306 comprising vinyl acetate or vinyl alcohol (co)polymers
• CPC Class Codes: B32B 27/308 comprising acrylic (co)polymers
• CPC Class Codes: B32B 27/32 comprising polyolefins comprising vinyl (co)polymers or acrylic (co)polymers B32B27/30
• CPC Class Codes: B32B 27/36 comprising polyesters
• CPC Class Codes: B32B 7/06 permitting easy separation
• CPC Class Codes: B32B 7/12 : using interposed adhesives or interposed materials with bonding properties
• CPC Class Codes: B65D 77/2096 : Adhesive means
• CPC Class Codes: C09D 133/08 : Homopolymers or copolymers of acrylic acid esters
• CPC Class Codes: C09J 133/08 : Homopolymers or copolymers of acrylic acid esters
• CPC Class Codes: Y10T 428/1352 : Polymer or resin containing [i.e., natural or synthetic]
• CPC Class Codes: Y10T 428/273 : of coating
• CPC Class Codes: Y10T 428/31797 : Next to addition polymer from unsaturated monomers
• CPC Class Codes: Y10T 428/31924 : Including polyene monomers
• CPC Class Codes: Y10T 428/31928 : Ester, halide or nitrile of addition polymer
• CPC Class Codes: Y10T 428/31935 : Ester, halide or nitrile of addition polymer

Abstract

The present invention relates to the use of meltable acrylate polymers for producing contact adhesive layers in resealable packagings. Moreover, the invention relates to multiple-layer films which have a contact adhesive layer on the basis of meltable acrylate polymers, to a method for producing said multiple-layer films, and to the use of said multiple-layer films for producing resealable packagings.

Claims

1. A method of producing a layer of pressure-sensitive adhesive on a surface of a reclosable pack, the method comprising applying an acrylate polymer having a glass transition temperature<

−

20°

C., determined according to ASTM-D 3418/82, comprising 1 to 30 mmol of copolymerized photoinitiator per kg of acrylate polymer, the acrylate polymer comprising, in reacted form, monoethylenically unsaturated monomers M and the photoinitiator, the monomers M comprising;

a) at least 80% by weight, based on the total weight of the acrylate polymer, of at least one monomer A selected from the group consisting of C₃-C₂₀ alkyl acrylates;

b) 1 to 20% by weight of at least one monomer B selected from the group consisting of C₁-C₄ alkyl methacrylates, methyl acrylate, and ethyl acrylate;

c) up to 10% by weight of at least one nonaromatic, monoethylenically unsaturated monomer C, which are selected from the group consisting of monoethylenically unsaturated C₃-C₈ monocarboxylic acids, amides of monoethylenically unsaturated C₃-C₈ monocarboxylic acids, monoethylenically unsaturated C₄-C₈ dicarboxylic acids, mono-C₁-C₂₀ alkyl esters of monoethylenically unsaturated C₄-C₈ dicarboxylic acids, and hydroxyalkyl esters of monoethylenically unsaturated C₃-C₈ monocarboxylic acids,

wherein weight fractions of monomers A, B and C add up to 100% by weight,

as a reacted coating component to the surface of the reclosable pack.

2. The method according to claim 1, wherein the acrylate polymer has at 130°

C. a zero viscosity in the range from 10 to 200 Pa·

s.

3. The method according to claim 1, wherein the acrylate polymer has a Fikentscher K value in the range from 20 to 90, measured at 21°

C. as a 1% strength by weight solution in tetrahydrofuran.

4. The method according to claim 1, wherein the copolymerized photoinitiator comprises an acetophenone or benzophenone group.

5. A multilayer film comprising:

a) a backing film,

b) a layer of pressure-sensitive adhesive formed from an acrylate polymer having a glass transition temperature<

−

20°

C., determined according to ASTM-D 3418/82, comprising 1 to 30 mmol of copolymerized photoinitiator per kg of acrylate polymer, the acrylate polymer comprising, in reacted form, monoethylenically unsaturated monomers M and the photoinitiator, the monomers M comprising;

b1) at least 80% by weight, based on the total weight of the acrylate polymer, of at least one monomer A selected from the group consisting of C₃-C₂₀ alkyl acrylates;

b2) 1 to 20% by weight of at least one monomer B selected from the group consisting of C₁-C₄ alkyl methacrylates, methyl acrylate, and ethyl acrylate;

b3) up to 10% by weight of at least one nonaromatic, monoethylenically unsaturated monomer C, which are selected from the group consisting of monoethylenically unsaturated C₃-C₈ monocarboxylic acids, amides of monoethylenically unsaturated C₃-C₈ monocarboxylic acids, monoethylenically unsaturated C₄-C₈ dicarboxylic acids, mono-C₁-C₂₀ alkyl esters of monoethylenically unsaturated C₄-C₈ dicarboxylic acids, and hydroxyalkyl esters of monoethylenically unsaturated C₃-C₈ monocarboxylic acids,

wherein weight fractions of monomers A, B and C add up to 100% by weight, the polymer being crosslinked by UV radiation, and

c) a sealable layer,

wherein the layer of pressure-sensitive adhesive is disposed between the backing film and the sealable layer.

6. The multilayer film according to claim 5, wherein the backing film is a transparent polymer film or metallized polymer film.

7. The multilayer film according to claim 5, wherein the backing film is a polyolefin film or polyester film.

8. The multilayer film according to claim 5, wherein the backing film is a polyethylene terephthalate film.

9. The multilayer film according to claim 5, wherein the sealable layer comprises polyethylene.

10. The multilayer film according to claim 5, wherein the layer of pressure-sensitive adhesive has an average coating thickness of 1 to 50 g/m².

11. A method of producing a multilayer film according to claim 5, comprising:

i. applying an acrylate polymer having a glass transition temperature<

−

20°

C., determined according to ASTM-D 3418/82, comprising 1 to 30 mmol of copolymerized photoinitiator per kg of acrylate polymer, the acrylate polymer comprising, in reacted form, monoethylenically unsaturated monomers M and the photoinitiator, the monomers M comprising;

a) at least 80% by weight, based on the total weight of the acrylate polymer, of at least one monomer A selected from the group consisting of C₃-C₂₀ alkyl acrylates;

b) 1 to 20% by weight of at least one monomer B selected from the group consisting of C₁-C₄ alkyl methacrylates, methyl acrylate, and ethyl acrylate;

c) up to 10% by weight of at least one nonaromatic, monoethylenically unsaturated monomer C, which are selected from the group consisting of monoethylenically unsaturated C₃-C₈ monocarboxylic acids, amides of monoethylenically unsaturated C₃-C₈ monocarboxylic acids, monoethylenically unsaturated C₄-C₈ dicarboxylic acids, mono-C₁-C₂₀ alkyl esters of monoethylenically unsaturated C₄-C₈ dicarboxylic acids, and hydroxyalkyl esters of monoethylenically unsaturated C₃-C₈ monocarboxylic acids,

wherein weight fractions of monomers A, B and C add up to 100% by weight, as a coating to the backing film,

ii. irradiating the coating with UV radiation, and

iii. applying the sealable layer to the coating obtained in i or ii.

12. The method according to claim 11, wherein the acrylate polymer is applied as a melt to the backing.

13. The method according to claim 11, the coating is irradiated with an energy of 0.5 to 20 mJ/cm².

14. A reclosable pack comprising at least one multilayer film according to claim 5.

15. The pack according to claim 14, comprising two packaging elements connected to one another via a seal layer, one of the packaging elements being a multilayer film comprising:

a) a backing film, which is a polyolefin film or polyester film,

b) a layer of pressure-sensitive adhesive formed from an acrylate polymer having a glass transition temperature<

−

20°

C., determined according to ASTM-D 3418/82₁ comprising 1 to 30 mmol of copolymerized photoinitiator per kg of acrylate polymer, the acrylate polymer comprising, in reacted form, monoethylenically unsaturated monomers M and the photoinitiator, the monomers M comprising;

b1) at least 80% by weight, based on the total weight of the acrylate polymer, of at least one monomer A selected from the group consisting of C₃-C₂₀ alkyl acrylates;

b2) 1 to 20% by weight of at least one monomer B selected from the group consisting of C₁-C₄ alkyl methacrylates, methyl acrylate, and ethyl acrylate;

b3) up to 10% by weight of at least one nonaromatic, monoethylenically unsaturated monomer C, which are selected from the group consisting of monoethylenically unsaturated C₃-C₈ monocarboxylic acids, amides of monoethylenically unsaturated C₃-C₈ monocarboxylic acids, monoethylenically unsaturated C₄-C₈ dicarboxylic acids, mono-C₁-C₂₀ alkyl esters of monoethylenically unsaturated C₄-C₈ dicarboxylic acids, and hydroxyalkyl esters of monoethylenically unsaturated C₃-C₈ monocarboxylic acids,

wherein weight fractions of monomers A, B and C add up to 100% by weight,

the polymer being crosslinked by UV radiation, and

c) a sealable layer,

wherein the layer of pressure-sensitive adhesive is disposed between the backing film and the sealable layer.

16. The pack according to claim 14, wherein the multilayer film is in the form of a closure film.

17. The pack according to claim 14, wherein the multilayer film is in the form of a container molding.

18. The multilayer film according to claim 5, wherein the sealable layer consists of polyethylene.

19. The pack according to claim 15, wherein the multilayer film is in the form of a closure film.

20. The pack according to claim 15, wherein the multilayer film is in the form of a container molding