Process for preparing flowable amorphous poly-alpha olefin adhesive pellets
View Patent ↗The present invention relates to a process for producing free-flowing, agglomeration resistant amorphous poly-alpha-olefin based adhesive pellets. The process includes (a) extruding the adhesive through an orifice of a die plate immersed in a cooling fluid; (b) cutting the adhesive into a plurality of pellets in the cooling fluid; (c) solidifying the pellets at a temperature range of about 25° C. to about 40° C. for at least 30 minutes; and (d) separating the pellets from the recrystallization fluid and drying the pellets. The pellets harden at least three folds faster than conventionally formed pellets.
1. A process for forming a plurality of hot melt adhesive pellets comprising the steps of:
a) extruding an adhesive through an orifice of a die plate immersed in a cooling fluid, which has a temperature T1;
b) cutting the adhesive into a plurality of pellets in the cooling fluid;
c) solidifying the pellets in a recrystallization fluid at temperature T2 for at least 30 minutes and up to 24 hours;
d) separating the pellets from the recrystallization fluid and drying the pellets;
wherein the T1 is less than about 45° F. and the T2 is higher than T1 by at least 30° F.
wherein the adhesive comprises an amorphous poly-alpha-olefin polymer having a cold crystallization temperature;
wherein the adhesive has a needle penetration number of (i) 8 to 50 dmm after 1 hour conditioning at 77° F., (ii) 10 to 45 dmm after 4 hour conditioning at 77° F., and (iii) 10 to 40 dmm after 24 hour conditioning at 77° F.; and
wherein the pellets have an average percent deformation, (d 0 -d 1 )/d 0 ×100%, less than 40%, where d 0 is an initial diameter and d 1 is a diameter measured after applying a weight of 70 g for one minute.
2. The process of claim 1 wherein the T2 has a temperature range of about 77° F. to about 104° F.
3. The process of claim 2 wherein the T2 has a temperature range of about 86° F. to about 95° F.
4. The process of claim 1 wherein the pellets are held in the recrystallization fluid for at least about 60 minutes up to about 180 minutes.
5. The process of claim 4 wherein the pellets are held in the recrystallization fluid for at least about 100 minutes up to about 150 minutes.
6. The process of claim 1 wherein the amorphous alpha-olefin polymer comprises a comonomer of ethylene, propylene, butene, pentene, hexane, heptene, octane, nonene, decene, undecene, dodecene, and mixtures thereof.
7. The process of claim 6 wherein the amorphous alpha-olefin polymer comprises a comonomer of propylene and butene.
8. The process of claim 1 wherein the adhesive has a needle penetration number of (i) 15 to 40 dmm after 1 hour conditioning at 77° F., (ii) 15 to 40 dmm after 4 hour conditioning at 77° F., and (iii) 10 to 30 dmm after 24 hour conditioning at 77° F.
9. The process of claim 8 wherein the adhesive has a cold crystallization temperature of about 77° F. to about 105° F.
10. The process of claim 9 wherein the adhesive has a cold crystallization temperature of about 82° F. to about 104° F.