Process for the Production of Hot Melt Adhesives Having a Low Emission of Monomeric Isocyanates
AssigneeHenkel AG & Co. KGaA
InventorsUwe FRANKEN, Hans-Georg KINZELMANN
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Abstract
The present invention refers to a process for the production of hot melt adhesives having a low emission of monomeric isocyanates upon heating wherein in a first step a polyurethane prepolymer is generated which is subsequently reacted with a chain extender. Further, the present invention refers to hot melt adhesives obtained by the inventive process.
Claims19
A process for the production of a hot melt adhesive including a polyurethane prepolymer, comprising:
- reacting the polyurethane prepolymer with a chain extender wherein the polyurethane prepolymer is obtained by;
- (i) reacting 2,4′-toluene diisocyanate (2,4′-TDI) with a polyol and in a subsequent step
- (ii) reacting methylene diphenyldiisocyanate (MDI) to the reaction mixture of step (i);
- wherein the hot melt adhesive has an application temperature of 80 to 160° C. and the chain extender is selected from the group consisting of 1,3-butane diol, 1,2-propane diol, 2-ethyl-1-hexanol, diethylene glycol, tripropylene glycol, isosorbide, resorcinol, 1,4-dimethylol cyclohexane, and mixtures thereof.
A hot melt adhesive comprising a chain extended polyurethane prepolymer, wherein the chain extended polyurethane prepolymer is the reaction product of a polyurethane prepolymer and a chain extender, wherein:
- the polyurethane prepolymer is the reaction product of 2,4′-toluene diisocyanate (2,4′-TDI), a polyol and methylene diphenyl diisocyanate (MDI);
- the chain extender is selected from the group consisting of 1,3-butane diol, 1,2-propane diol, 2-ethyl-1-hexanol, diethylene glycol, tripropylene glycol, isosorbide, resorcinol, 1,4-dimethylol cyclohexane, and mixture thereof;
- and
- the hot melt adhesive has an application temperature of 80 to 160° C., the content of monomeric toluene diisocyanate is less than 0.02 wt.-%, based on the total weight of the hot-melt adhesive and the content of monomeric methylene diphenyl diisocyanate in the hot melt adhesive is less than 0.1 wt.-%, based on the total weight of the hot-melt adhesive.
Dependencies are inferred from the claim text.