Fusible adhesives crosslinkable by radiation

• US 20050165164A1
• Filed: 01/24/2005
• Published: 07/28/2005
• Est. Priority Date: 07/27/2002
• Status: Active Grant

• Current Assignee: Henkel AG & Co KGaA
• Original Assignee: Henkel KGaA (Henkel AG & Co KGaA)
• Inventors: Moeller, Thomas, Ferencz, Andreas, Heemann, Marcus
• Granted Patent: US 7,156,944 B2
• Time in Patent Office: Days
• US Class Current: 525/66
• CPC Class Codes: C08F 279/02 on to polymers of conjugated dienes
• CPC Class Codes: C08F 291/02 on to elastomers
• CPC Class Codes: C09J 121/00 Adhesives based on unspecified rubbers
• CPC Class Codes: C09J 4/06 Organic non-macromolecular compounds having at least one polymerisable carbon-to-carbon unsaturated bond in combination with a macromolecular compound other than an unsaturated polymer of groups C09J159/00 - C09J187/00

Abstract

To obtain an adhesive having both a high initial adhesive capacity and high heat resistance, a fusible adhesive which can be cross-linked by radiation and a low tendency to creep is provided. The adhesive contains 0 to 40 weight percent of at least one elastomer which cannot be cross-linked by radiation, 15 to 40 weight percent of at least one compound containing at least two olefinic double bonds, and 20 to 85 weight percent of at least one tackifier. The adhesive is especially suitable for use on high speed labeling machines.

Claims

1. A low-creep radiation-crosslinkable hotmelt pressure-sensitive adhesive comprising:

(A) 0 to 40% by weight of at least one natural or synthetic, non-radiation-crosslinkable elastomer as component (A);

(B) 15 to 40% by weight of at least one radiation-crosslinkable compound containing at least two olefinic double bonds selected from the group consisting of component (B1), component (B2) and component (B3), wherein

(B1) component (B1) is at least one diolefin homopolymer or copolymer having olefinic double bonds along the main chain and having a percentage content of recurring diolefin units being 50 to 100% by weight selected from the group consisting of homo- and copolymers of 1,3-pentadiene, 2-ethyl-1,3-butadiene, 2-propyl-1,3-butadiene, 2-isopropyl-1,3-butadiene, 2-hexyl-1,3-butadiene, 2,3-dimethyl-1,3-butadiene, 2,3-diethyl-1,3-butadiene, 2-methyl-1,3-pentadiene, 2-methyl-1,3-hexadiene, 2-methyl-1,3-octadiene, 2-methyl-1,3-decadiene, 2,3-dimethyl-1,3-pentadiene, 2,3-dimethyl-1,3-hexadiene, 2,3-dimethyl-1,3-octadiene and 2,3-dimethyl-1,3-decadiene, 2-methyl-1,3-cyclopentadiene, 2-methyl-1,3-cyclohectadiene, 2,3-dimethyl-1,3-cyclopentadiene, 2,3-dimethyl-1,3-cyclohexadiene, 2-chloro-1,3-butadiene, 2,3-dichloro-1,3-butadiene, 1-fluoro-1,3-butadiene, 2-chloro-1,3-pentadiene, 2-chloro-1,3-cyclopentadiene and 2-chloro-1,3-cyclohexadiene;

(B2) component (B2) is at least one compound having olefinic double bonds in the side chains and having a percentage content of recurring diolefin units of 50 to 100% by weight and a percentage content of vinylic double bonds of from 5 to 100%, based on the total number of olefinic double bonds in component (B2), selected from the group consisting of

i) homopolymers and copolymers of 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 1,3-pentadiene and cyclopentadiene; and

ii) homo- and copolymers of monomers selected from the group consisting of 1,3-butadiene, 2-methyl-1,3-butadiene, 1,3-pentadiene and cyclopentadiene which contain at least one functional group;

(B3) component (B3) is at least one acrylate or methacrylate ester with a functionality of at least two; and

(C) 20 to 85% by weight of at least one tackifying resin as component (C).

2. A low-creep radiation-crosslinkable hotmelt pressure-sensitive adhesive as claimed in claim 1, wherein at least one of component (B1) or component (B2) is present in said adhesive and is modified by at least one radiation-crosslinkable functional group other than olefinic double bonds.

3. A low-creep radiation-crosslinkable hotmelt pressure-sensitive adhesive as claimed in claim 1, wherein component (B2) is present in said adhesive and is a copolymer obtainable i) by reaction of two or more monomers selected from the group consisting of 1,3-butadiene, 2-methyl-1,3-butadiene, 1,3-pentadiene and cyclopentadiene or ii) by reaction of one or more monomers selected from the group consisting of 1,3-butadiene, 2-methyl-1,3-butadiene, 1,3-pentadiene and cyclopentadiene with one or more monomers selected from the group consisting of 2,3-dimethyl-1,3-butadiene, 1,4-pentadiene, 2,3-pentadiene, ethylene, propylene, butylene, hexene, octene, acrylesters, acrylonitrile, vinyl esters, and vinyl nitrile.

4. A low-creep radiation-crosslinkable hotmelt pressure-sensitive adhesive as claimed in claim 1, wherein component (A) is present in said adhesive and is selected from the group consisting of acrylates, polyester urethanes, ethylene acrylates, butyl rubbers;

natural rubber;

ethylene/propylene copolymers;

ethylene/vinyl acetate copolymers, styrene copolymers and mixtures thereof.

5. A low-creep radiation-crosslinkable hotmelt pressure-sensitive adhesive as claimed in claim 1, wherein component (A) is present in said adhesive and is comprised of at least one styrene block polymer.

7. A low-creep radiation-crosslinkable hotmelt pressure-sensitive adhesive as claimed in claim 1, wherein at least one of component (B1) or component (B2) is present in saidadhesive and is modified by at least one radiation-crosslinkable functional group other than olefinic double bonds selected from the group consisting of acrylate groups, methacrylate groups and epoxide groups.

8. A low-creep radiation-crosslinkable hotmelt pressure-sensitive adhesive as claimed in claim 1, wherein component (A) is present in said adhesive and is selected from the group consisting of styrene/diene block copolymers, styrene/ethylene/butylene block copolymers and styrene/ethylene/propylene/styrene block copolymers.

9. A low-creep radiation-crosslinkable hotmelt pressure-sensitive adhesive as claimed in claim 1, wherein component (B2) is present in said adhesive and is selected from the group consisting of homo- and copolymers of monomers selected from the group consisting of 1,3-butadiene, 2-methyl-1,3-butadiene, 1,3-pentadiene and cyclopentadiene which contain two or three functional groups.

10. A low-creep radiation-crosslinkable hotmelt pressure-sensitive adhesive as claimed in claim 1, wherein component (B2) is present in said adhesive and is selected from the group consisting of homo- and copolymers of monomers selected from the group consisting of 1,3-butadiene, 2-methyl-1,3-butadiene, 1,3-pentadiene and cyclopentadiene which contain two or three functional groups selected from the group consisting of hydroxyl groups, amino groups, epoxide groups, isocyanate groups carboxyl groups, carboxylic anhydride groups, mercapto groups, silane groups and hydrosilyl groups.

11. A low-creep radiation-crosslinkable hotmelt pressure-sensitive adhesive as claimed in claim 1, wherein component (B3) is present in said adhesive and is selected from the group consisting of dipropylene glycol diacrylate, tripropylene glycol diacrylate, tetrapropylene glycol diacrylate, neopentyl glycol propoxylate di(meth)acrylates, trimethylolpropane tri(meth)acrylate, trimethylolpropane monoethoxytri(meth)acrylate and pentaerythritol triacrylate.

12. A low-creep radiation-crosslinkable hotmelt pressure-sensitive adhesive as claimed in claim 1, wherein component (C) comprises a terpene hydrocarbon resin.

13. A low-creep radiation-crosslinkable hotmelt pressure-sensitive adhesive as claimed in claim 1, additionally comprising at least one photoinitiator.

14. A low-creep radiation-crosslinkable hotmelt pressure-sensitive adhesive as claimed in claim 1, wherein component (A) is comprised of at least one styrene block polymer, component (B) is comprised of at least one of polybutadiene, polyisoprene or a (meth)acrylate ester of a polyol selected from the group consisting of aromatic polyols, aliphatic polyols, cycloaliphatic polyols, and polyether alcohols, and said adhesive additionally comprises at least one photoinitiator.

15. A low-creep radiation-crosslinkable hotmelt pressure-sensitive adhesive as claimed in claim 1 additionally comprising at least one compound selected from the group consisting of mercaptans and thio compounds.

16. A low-creep radiation-crosslinkable hotmelt pressure-sensitive adhesive as claimed in claim 1 additionally comprising at least one non-elastomeric polymer selected from the group consisting of ethylene/n-butyl acrylate copolymers, ethylene/(meth)acrylic acid copolymers, amorphous polyolefins, polyamides, and polyphenylene oxide.

17. A low-creep radiation-crosslinkable hotmelt pressure-sensitive adhesive as claimed in claim 1 additionally comprising at least one adhesion promoter.

20. A process for attaching a label to a substrate, said process comprising joining said label to said substrate using a radiation-crosslinkable hotmelt pressure-sensitive adhesive in accordance with claim 1 and exposing said adhesive to radiation selected from the group consisting of UV radiation and electron beam radiation.

21. A process as claimed in claim 20 wherein at least one of either said label or said substrate is comprised of plastic.

6. A low-creep radiation-crosslinkable hotmelt pressure-sensitive adhesive comprising:

5 to 20% by weight of at least one elastomer selected from the group consisting of styrene block copolymers, ethylene/vinyl acetate copolymers and mixtures thereof as component (A);

15 to 40% by weight of at least one radiation-crosslinkable compound selected from the group consisting of butadiene homopolymers and copolymers with a 1,2-vinyl content of 30 to 90% and (meth)acrylate esters of polyether alcohols as component (B);

20 to 85% by weight of at least one tackifying resin as component (C);

0.1 to 10% by weight of at least one photoinitiator as component (D);

0 to 30% by weight of at least one plasticizer as component (F); and

0.1 to 1% by weight of at least one antioxidant as component (H).

22. A process for attaching a label to a substrate, said process comprising joining said label to said substrate using a radiation-crosslinkable hotmelt pressure-sensitive adhesive in accordance with claim 6 and exposing said adhesive to radiation selected from the group consisting of UV radiation and electron beam radiation.

23. A process as claimed in claim 22 wherein both said label and said substrate are comprised of plastic.

18. A process for attaching a label to an article selected from the group consisting of hollow plastic containers, aerosol cans, and contour bottles, said process comprising joining said label to said article using a radiation-crosslinkable hotmelt pressure-sensitive adhesive comprising 0 to 40% by weight of at least one natural or synthetic, non-radiation-crosslinkable elastomer, 15 to 40% by weight of at least one radiation-crosslinkable compound containing at least two olefinic double bonds, and 20 to 85% by weight of at least one tackifying resin and exposing said adhesive to radiation selected from the group consisting of UV radiation and electron beam radiation.

19. A process as claimed in claim 18 wherein at least one of either said label or said article is comprised of plastic.