Hot-melt adhesive that has good open time at room temperature and can form creep-resistant bonds
AssigneeMinnesota Mining and Manufacturing Company
InventorDennis Hansen
Life of this patent
Estimating the term…
Abstract
A hot-melt adhesive of ethylene/vinyl acetate copolymer and tackifying resin can be spread into a thin layer that remains tacky for more than 5 seconds, after which a bond can be made without applying heat or more than hand pressure. Within a short period of time, the adhesive crystallizes so that the bond becomes creep-resistant. The temperature at which this hot-melt adhesive can be spread into thin layers is significantly lower than could be used with prior hot-melt adhesives that develop creep resistance.
Claims19
A method for adhesively bonding a first substrate to a second substrate, the method comprising the steps of:
- (a) providing a first substrate;
- (b) applying to the first substrate in a thin layer about 50 .mu.m thick and in molten form, a hot melt adhesive comprising by weight:
- (1) an ethylene/vinyl acetate copolymer having from 14 to 35 weight % vinyl acetate and a melt index of at least 500, and
- (2) from 50 to 200 parts of a tackifying resin per 100 parts of the copolymer, which resin has a ring and ball softening point within the range of from 70.degree. to 115.degree. C. and a combined aromatic and olefinic content within the range of from 0.5 to 50 mole %;
- (c) cooling the thin layer of the molten hot melt adhesive until it is no longer molten, wherein the non-molten thin layer of adhesive remains tacky for 5 seconds to about 330 seconds at room temperature;
- and
- (d) applying a second substrate to the tacky, non-molten thin layer of adhesive in step (c) to adhesively bond the first substrate to the second substrate.
Dependencies are inferred from the claim text.