Polyurethane adhesive with semi-crystalline and highly crystalline polyesters
The present invention refers to polyurethane adhesives with semi-crystalline and highly crystalline polyesters, a method for the production of the same as well as the use of the polyurethane adhesive in the production of electronic devices.
1. A polyurethane adhesive that is the reaction product of a mixture comprising:
at least one semi-crystalline polyester in an amount of from 15 to 25 wt %, based on the total weight of the mixture; and
at least one highly crystalline polyester in an amount of from 5 to 10 wt %, based on the total weight of the mixture, wherein:
the melting point of the at least one highly crystalline polyester is higher than the melting point of the at least one semi-crystalline polyester,
the at least one semi-crystalline polyester and the at least one highly crystalline polyester are present in the mixture in a weight ratio of from 7:1 to 3:1, and
the polyurethane adhesive further comprises:
an acrylate in an amount of from 10 to 30 wt %, based on the total weight of the mixture; and
an NCO-terminated compound in an amount of from 10 to 20 wt %, based on the total weight of the mixture.
2. The polyurethane adhesive of claim 1 , wherein the at least one semi-crystalline polyester has a hydroxyl value (OH value) of from 10 to 50 mg KOH/g, determined according to DIN ISO 4629-2.
3. The polyurethane adhesive of claim 2 , wherein the at least one highly crystalline polyester has a hydroxyl value (OH value) of from 20 to 100 mg KOH/g, determined according to DIN ISO 4629-2.
4. The polyurethane adhesive of claim 3 , wherein the at least one semi-crystalline polyester has a hydroxyl value (OH value) of from 25 to 40 mg KOH/g and the at least one highly crystalline polyester has a hydroxyl value (OH value) of 35 to 60 mg KOH/g, each hydroxyl value (OH value) determined according to DIN ISO 4629-2.
5. The polyurethane adhesive of claim 1 , wherein the average molecular weight M n of the at least one semi-crystalline polyester and/or the at least one highly crystalline polyester is from 1000 to 5000 g/mol, determined according to DIN 55672-1:2007-08.
6. The polyurethane adhesive of claim 5 , wherein the average molecular weight M n of the at least one semi-crystalline polyester and/or the at least one highly crystalline polyester is from 1500 to 4000 g/mol, determined according to DIN 55672-1:2007-08.
7. The polyurethane adhesive of claim 1 , wherein the at least one semi-crystalline polyester has a melting point of from 50 to 100° C. and/or the at least one highly crystalline polyester has a melting point of from 65 to 120° C., each melting point determined by differential scanning calorimetry.
8. The polyurethane adhesive of claim 1 , wherein the mixture further comprises at least one of a polyol or an amorphous polyester.
9. The polyurethane adhesive of claim 8 , wherein the polyol is in an amount of from 10 to 30 wt %, based on the total based on the total weight of the mixture, and/or the amorphous polyester is in an amount of from 10 to 30 wt %, based on the total based on the total weight of the mixture.
10. The polyurethane adhesive of claim 1 , wherein the polyurethane adhesive is a solid at room temperature.
11. A cured reaction product comprising the polyurethane adhesive of claim 1 .
12. A device comprising the cured reaction product of claim 11 .
13. The polyurethane adhesive of claim 1 , wherein the polyurethane adhesive is a hot-melt adhesive.
14. The polyurethane adhesive of claim 1 , wherein the polyurethane adhesive is free of water and a solvent.
15. The polyurethane adhesive of claim 1 , wherein the polyurethane adhesive has a minimum open time of two minutes.
16. A polyurethane adhesive that is the reaction product of a mixture comprising:
an acrylate in an amount of from 10 to 30 wt %, based on the total weight of the mixture;
at least one semi-crystalline polyester in an amount of 25 wt %, based on the total weight of the mixture; and
at least one highly crystalline polyester in an amount of 25 wt %, based on the total weight of the mixture, wherein:
the at least one semi-crystalline polyester has a melting point of 55° C., determined by differential scanning calorimetry, and/or
the at least one highly crystalline polyester has a melting point of from 70 to 115° C., determined by differential scanning calorimetry.
17. The polyurethane adhesive of claim 16 , further comprising an NCO-terminated compound in an amount of from 10 to 20 wt %, based on the total weight of the mixture.
18. The polyurethane adhesive of claim 16 , wherein the polyurethane adhesive has a minimum open time of two minutes.
19. The polyurethane adhesive of claim 1 , wherein the acrylate is in an amount of from 15 to 25 wt %, based on the total weight of the mixture.
20. The polyurethane adhesive of claim 1 , wherein the NCO-terminated compound is diisocyante.