Amorphous polyurethane polymer and its use in hotmelt adhesives

1. Amorphous polyurethane polymer which is solid at room temperature, of formula (I)

where

R 1 is a divalent aliphatic or cycloaliphatic or araliphatic hydrocarbon radical having 2 to 12 C atoms, which optionally contains at least one heteroatom;

R 2 and R 3 either

independently of one another, are each a monovalent hydrocarbon radical having 1 to 12 C atoms,

or

together form a divalent hydrocarbon radical having 4 to 20 C atoms which is part of an unsubstituted or substituted carbocyclic ring having 5 to 8 C atoms;

Y 1 is a monovalent hydrocarbon radical having 1 to 35 C atoms which optionally contains heteroatoms;

X is O or S or N—R 6 ,

where R 6 either

is a monovalent hydrocarbon radical having 1 to 20 C atoms which optionally contains at least one carboxylic ester, nitrile, nitro, phosphonic ester, sulphone or sulphonic ester group,

or

is a substituent of the formula (II)

m is 1 or 2 or 3, n is 0 or 1 or 2, wherein the sum of m and n is 2 or 3;

A is the radical of a polyurethane polymer D, solid at room temperature and containing isocyanate groups, following removal of (m+n) isocyanate groups and prepared from the reaction of a polyol mixture comprising

at least one polyester polyol PE1 which is liquid at a temperature range of −50° C. to 0° C.,

at least one polyester polyol PE2 which is amorphous and solid at room temperature, and

at least one polyisocyanate PI, wherein

in the polyol mixture the weight ratio of all polyester polyols PE1 liquid at room temperature to all amorphous polyester polyols PE2 amorphous and solid at room temperature is 0.1-0.5,

the at least one polyester polyol PE1 has a molecular weight ranging from 2,000 to 8,000 g/mol, and

the at least one polyester polyol PE2 has a molecular weight ranging from 1,000 to 8,000 g/mol, and has a melting point ranging from 60° C. to 130° C.

2. Amorphous polyurethane polymer solid at room temperature according to claim 1 , wherein m is 1 and n is 1.

3. Amorphous polyurethane polymer solid at room temperature according to claim 1 , wherein R 2 and R 3 are each a methyl group.

4. Amorphous polyurethane polymer solid at room temperature according to claim 1 , wherein Y 1 is a radical of the formula (III)

where Z is a hydrogen atom or is an alkyl or arylalkyl group having 1 to 8 C atoms,

R 4 either

is a monovalent hydrocarbon radical having 1 to 30 C atoms which optionally contains at least one heteroatom,

or

is a radical

where R 5 is a monovalent hydrocarbon radical having 1 to 30 C atoms which optionally contains at least one heteroatom.

5. Amorphous polyurethane polymer solid at room temperature according to claim 4 , wherein R 4 is the radical

where R 5 is a monovalent hydrocarbon radical having 1 to 30 C atoms.

6. Amorphous polyurethane polymer solid at room temperature according to claim 1 , wherein R 1 has a formula weight of 28 to 100 g/mol.

7. Amorphous polyurethane polymer solid at room temperature according to claim 1 , wherein the polyisocyanate PI is a diisocyanate.

8. Amorphous polyurethane polymer solid at room temperature according to claim 1 , wherein the polyester polyol PE1 which is liquid at room temperature has a molecular weight ranging from 4,000 to 7,000 g/mol and the polyester polyol PE2 which is amorphous and solid at room temperature has a molecular weight ranging from 2,000 and 5,000 g/mol.

9. Amorphous polyurethane polymer solid at room temperature according to claim 1 , wherein X is O or N—R 6 .

10. Process for preparing an amorphous polyurethane polymer solid which is at room temperature, of the formula (I), according to claim 1 , wherein this polyurethane polymer is prepared by reacting an aldimine of the formula (XI), with a polyurethane polymer D containing isocyanate groups, of the formula (XII)

11. Hotmelt adhesive composition comprising at least one amorphous polyurethane polymer which is solid at room temperature, of the formula (I), according to claim 1 .

12. Hotmelt adhesive composition according to claim 11 , wherein the amount of polyurethane polymer of the formula (I) is 40%-100% by weight, based on the total hotmelt adhesive composition.

13. Cured hotmelt adhesive composition obtained by reaction of moisture with a hotmelt adhesive composition according to claim 11 .

14. Method of adhesively bonding substrates S1 and S2, comprising:

i) heating a hotmelt adhesive composition according to claim 11 to a temperature between 85° C. and 200° C.,

ii) applying the heated composition to a substrate S1;

iii) contacting the applied composition with a second substrate S2 within an open time;

the second substrate S2 being composed of a same material as or a different material as the material of substrate S1.

15. Amorphous polyurethane polymer solid at room temperature according to claim 1 , wherein the at least one polyester polyol PE2 has a molecular weight ranging from 2,000 to 3,000 g/mol and has a melting point ranging from 80° C. to 110° C.