US 5,710,215 A · Method and material mixture for manufacture of reactive hotmelts

Abstract

The invention proposes the following method of producing reactive melts which are especially useful as hotmelt adhesives: a) suitable meltable hydroxy functional or amino functional polymers or polymer mixes (A) which become liquid at temperatures above 40.degree. C. are inhomogenously mixed with b) powdered, solid, surface desactivated polyisocyanates (B) or a suspension of such polyisocyanates (B) in a low volatility carrier fluid, c) in approximately stoichiometric proportions at a temperature of at least 40.degree. C. in a static mixer so that the resultant mixture of substances exhibits partial areas in which the ratio (1) of polymer (A) to (2) solid isocyanate (B) and desactivating agent (C) is different from the average ratio of these substances or mixtures thereof within the entire mix, d) the inhomogenous mixture is extracted in a form suitable for the intended use and solidified by cooling to below the mixture's softening point. These preformed or possibly nonformed solid reactive melts are able to be stored at room temperature and retain their latent thermoreactivity.

Claims15

Dependent claims

A method of manufacturing a room-temperature shelf-stable mixture of reactive substances comprising

(A) at least one thermoplastic polymer having a melting point above 40.degree. C., so that it is solid at room temperature, and which carries functional groups reactive with isocyanate,
(B) at least one solid polyisocyanate in powder form, suspended in the solid thermoplastic polymer and having a melting point higher than that of the thermoplastic polymer,
(C) at least one deactivating agent for reacting with surface isocyanate groups in the solid polyisocyanate,
wherein the polyisocyanate is pre-mixed with said deactivating agent, and is thereby deactivated, the pre-mix of polyisocyanate and deactivating agent is then, at a temperature above the melting point of the polymer but below the melting point of the deactivated polyisocyanate, mixed with the polymer, which has been made liquid through warming, in layers, so that the resulting mixture includes first layers which predominantly comprise said polymer, and, between said first layers, second layers which predominantly comprise said deactivated polyisocyanate and also unbound deactivating agent, and the mixture is then cooled and solidified with the said layer structure.

1 more element

Dependencies are inferred from the claim text.

Method and material mixture for manufacture of reactive hotmelts

Life of this patent

Method and material mixture for manufacture of reactive hotmelts

Life of this patent

Abstract

Claims15