Cross-linkable hot-melt adhesive and method of producing same

• US 5,075,386 A
• Filed: 04/12/1990
• Issued: 12/24/1991
• Est. Priority Date: 04/12/1990
• Status: Expired due to Term

• Current Assignee: Eastman Chemical Company
• Original Assignee: Eastman Kodak Company
• Inventors: Vanderbilt, Jeffrey J.
• Primary Examiner(s): Kight, III, John
• Assistant Examiner(s): Mosley, T.
• Application Number:
  US07/508,374
• Time in Patent Office: 621 Days
• Field of Search: 525/65, 525/74, 525/327.3, 525/327.4, 528/95, 428/355
• US Class Current: 525/327.3
• CPC Class Codes: C08F 255/02 on to polymers of olefins having two or three carbon atoms
• CPC Class Codes: C08F 8/00 Chemical modification by after-treatment graft polymers, block polymers, crosslinking with unsaturated monomers or with polymers C08F251/00 - C08F299/00; of conjugated diene rubbers C08C
• CPC Class Codes: C08L 2666/02 Organic macromolecular compounds, natural resins, waxes or and bituminous materials
• CPC Class Codes: C08L 2666/28 Non-macromolecular organic substances
• CPC Class Codes: C09J 151/06 grafted on to homopolymers or copolymers of aliphatic hydrocarbons containing only one carbon-to-carbon double bond
• CPC Class Codes: Y10T 428/2891 including addition polymer from alpha-beta unsaturated carboxylic acid [e.g., acrylic acid, methacrylic acid, etc.] Or derivative thereof

Abstract

A cross-linkable hot-melt adhesive is prepared by mixing an acid graft modified propylene/olefin copolymer with an epoxy cross-linking agent and a tertiary amine catalyst. The adhesive is cross-linked at an elevated temperature such as when melt mixing the components.

Claims

1. A cross-linkable hot-melt adhesive comprising:

(a) about 50 to 99% by weight, based on the total composition of at least one acid graft modified propylene/higher olefin copolymer containing about 70 to 95 mole percent propylene;

(b) up to 50% by weight of at least one tackifying resin;

(c) about 1 to 20 parts by weight per 100 parts by weight of (a) an epoxy cross-linking agent of the formula;

##STR6## in which n is between 2 and 6 inclusive, A is a polyfunctional group of the valency n, and R is hydrogen or a hydrocarbon radical;

(d) about 0.05 to 10% by weight of at least one antioxidant; and

(e) about 0.1 to about 10% by weight based on (c) plus (e) of a tertiary amine catalyst.

2. The cross-linkable hot-melt adhesive according to claim 1 wherein the olefin in said copolymer is from an alpha olefin of 4 to 10 carbon atoms.

3. The cross-linkable hot-melt adhesive according to claim 2 wherein the copolymer is a maleated amorphous propylene/hexene copolymer.

4. The cross-linkable hot-melt adhesive according to claim 1 wherein said acid graft modified propylene/olefin copolymer has an acid number of about 5 to 20 and a melt viscosity of about 1,000 to 2,000 cP at 177°

C.

5. The cross-linkable hot-melt adhesive according to claim 1 wherein the acid graft modified propylene/olefin copolymer is selected from low molecular weight propylene/olefin copolymers and degraded propylene/olefin copolymers and is present in an amount between about 55 and 65%.

6. The cross-linkable hot-melt adhesive according to claim 1 wherein the tackifying resin is present in an amount between about 20 and 35% by weight of the total adhesive composition, is selected from the group consisting of hydrocarbon resins, terpene resins, and rosin esters, and has a ring and ball softening point of about 95°

C. to 135°

C.

7. The cross-linkable hot-melt adhesive according to claim 6 wherein said tackifying resin is a hydrocarbon resin having a ring and ball softening point of about 125°

to 130°

C., an acid number of about 0 to 2, an acid value of less than about 1, and an iodine value of about 75 to 100.

8. The cross-linkable hot-melt adhesive according to claim 6 wherein said tackifying resin is a terpene resin comprising a mixture of sulphate terpene, and at least 20% of at least one other terpene selected from the group consisting of pinene, limonene, and dipentene.

9. The cross-linkable hot-melt adhesive according to claim 1 wherein the amount of epoxy is such that the equivalent ratio, ##EQU2## is between about 0.1 and 1 and the epoxy is Bisphenol-A diglycidyl ether.

10. A cross-linkable hot-melt adhesive comprising:

(a) about 50 to 99% by weight, based on the total composition of at least one acid graft modified propylene/olefin copolymer containing about 70 to 95 mole percent propylene;

(b) up to 50% by weight of at least one tacktifying resin;

(c) about 1 to 20 parts by weight per 100 parts by weight of (a) of an epoxy cross-linking agent of the formula;

##STR7## in which n is between 2 and 6 inclusive, A is a polyfunctional group of the valency n, and R is hydrogen or a hydrocarbon radical;

(d) about 0.05 to 10% by weight of at least one antioxidant; and

(e) about 0.1 to about 10% by weight based on (c) plus (e) of a latent tertiary amine catalyst of the formula R'"'"'₃ NX wherein R'"'"' is a hydrocarbon radical having from 1 to 30 carbon atoms, and X is thermally labile in combination with R'"'"'₃ N.

15. The cross-linkable hot-melt adhesive according to claim 10 wherein said latent tertiary amine catalyst is n-methyl morpholine picrate.

11. A process for producing a hot-melt adhesive comprising:

(1) mixing a propylene/olefin copolymer with an unsaturated carboxylic acid, anhydride, or monoester thereof under conditions of temperature and pressure to graft the acid, anhydride, or monoester onto said propylene/olefin copolymer;

(2) mixing the resulting acid graft modified propylene/olefin copolymer with

(a) about 1 to 20 parts by weight per 100 parts by weight of said copolymer of an epoxy cross-linking agent of the formula ##STR8## in which n is between 2 and 6 inclusive, a is a polyfunctional group of the valency of n, and R is a hydrocarbon radical or hydrogen;

(b) up to 50% by weight of at least one tackifying resin,

(c) about .05 to 10% by weight of at least one antioxidant; and

(d) about 0.1 to about 10% by weight based on (a) plus (d) of a tertiary amine catalyst;

(3) heating this mixture to a sufficient temperature for a sufficient time to substantially cross-link the acid graft modified propylene/olefin copolymer with the epoxy.

12. The process according to claim 11 wherein Step 3 is carried out at a temperature of at least 150°

C. for at least 5 minutes.

13. The process according to claim 11 wherein Step 3 is at least partially carried out in a heated stirred pot of a hot-melt applicator followed by applying the hot-melt adhesive to a substrate.

14. An article of manufacture comprising the hot-melt adhesive and substrate of claim 13.