Dispersion adhesives
The invention relates to formulations of aqueous dispersion adhesives on the basis of aqueous polyurethane or polyurethane-urea dispersions and the use of the adhesive formulations for bonding foam substrates according to the spray coagulation method.
1. A process for adhesively bonding substrates by mixing a formulation with a coagulant in a two-component spray gun, wherein the coagulant is conveyed separately into the two-component spray gun and is mixed in a spray jet and the coagulation of the dispersion in the spray jet takes place on a path to a surface of a first substrate, on impact with said substrate forms a film which is immediately tacky in a still-wet state and in the wet state a second surface is immediately joined, optionally with pressure on the substrate towards an adhesive surface,
wherein the formulation comprises:
I. an aqueous polyurethane or polyurethane-urea dispersion, containing as disperse phase a polymer A) which after drying is semicrystalline or crystalline and has a melting temperature in a range from 30 to 80° C. and an enthalpy of fusion of ≥35 J/g,
II. at least one plasticizer resin B),
III. at least one tackifier resin C),
wherein the formulation, based on the total formulation solids, comprises
60%-90% by weight of polymer A),
5%-20% by weight of plasticizer resin B) and
5%-20% by weight of tackifier resin C), and
wherein the formulation comprises from 40% to 85% by weight of water.
2. The method as claimed in claim 1 , wherein the aqueous polyurethane or polyurethane-urea dispersion does not contain an external emulsifier.
3. The method as claimed in claim 1 , wherein the formulation, based on the total formulation solids, comprises
66%-85% by weight of polymer A),
8%-18% by weight of plasticizer resin B) and
7%-16% by weight of tackifier resin C).
4. The method as claimed in claim 1 , wherein the formulation, based on the total formulation solids, comprises
70%-81% by weight of polymer A),
10%-16% by weight of plasticizer resin B) and
9%-14% by weight of tackifier resin C).
5. The method as claimed in claim 1 , wherein the formulation, based on the total formulation solids, comprises
72%-80% by weight of polymer A),
10%-15.5% by weight of plasticizer resin B) and
10%-12.5% by weight of tackifier resin C).
6. The method as claimed in claim 1 , wherein the polymer A), after drying, is semicrystalline or crystalline and has a melting temperature in the range from 35° C. to 80° C.
7. The method as claimed in claim 1 , wherein the polymer A), after drying, is semicrystalline or crystalline and has an enthalpy of fusion of ≥35 J/g.
8. The method as claimed in claim 1 , wherein the plasticizer B) comprises non-volatile, low molecular weight compounds bearing polar groups.
9. The method as claimed in claim 1 , wherein the tackifier resin C) comprises a rosin, and/or a modified rosins.