Non-swelling hot melt adhesive
Provided herein is a hot melt pressure sensitive adhesive comprising one or more styrene block copolymers, a tackifier, and polyisobutylene plasticizer, wherein the adhesive contains less than 1 wt % of a plasticizer oil. The adhesive can be used in a label construction along with a facestock such as a polyethylene facestock, wherein the swelling factor of the facestock is reduced as compared to the swelling factor of the facestock in labels that include a plasticizer oil. Also provided are methods for producing and using the hot melt adhesive, and articles labeled with the hot melt adhesive.
1. A hot melt adhesive comprising:
one or more styrene block copolymers;
a tackifier;
a polyisobutylene; and
a plasticizer oil,
wherein the number average molecular weight of the polyisobutylene ranges from 700 g/mol to 2500 g/mol, and
wherein the adhesive is a pressure sensitive adhesive;
wherein the one or more styrene block copolymers is selected from the group consisting of a styrene isoprene block copolymer, styrene butadiene block copolymer, or combinations thereof; and
the melt index of each of the styrene block copolymers ranges from about 10 g/(10 minute) to about 35 g/(10 minute) measured at 200° C. under pressure of 5 kg weight; and
wherein at least one of the one or more styrene block copolymers is a styrene butadiene block copolymer.
2. The hotmelt adhesive of claim 1 , wherein the weight ratio of the polyisobutylene to the one or more styrene block copolymers ranges from 3:8 to 8:3.
3. The hotmelt adhesive of claim 1 , wherein the weight ratio of the polyisobutylene to the tackifier ranges from 1:3 to 3:1.
4. The hot melt adhesive of claim 1 , comprising from 20 wt % to 45 wt % of the one or more styrene block copolymers.
5. The hot melt adhesive of claim 1 , wherein at least one of the one or more styrene block copolymers is a styrene isoprene block copolymer.
6. The hot melt adhesive of claim 5 , wherein the diblock content of each of the at least one styrene isoprene block copolymer ranges from 5% to 90%.
7. The hot melt adhesive of claim 1 , wherein at least one of the one or more styrene block copolymers is a styrene butadiene block copolymer.
8. The hot melt adhesive of claim 1 , wherein the polystyrene content of each of the one or more styrene block copolymer ranges from 10% to 25%.
9. The hot melt adhesive of claim 1 , wherein the tackifier is an aromatic hydrocarbon resin.
10. The hot melt adhesive of claim 1 , wherein the tackifier is a terpene phenolic resin.
11. The hot melt adhesive of claim 1 , wherein the softening point of the tackifier ranges from 80° C. to 120° C.
12. The hot melt adhesive of claim 1 , wherein the glass transition temperature of the tackifier ranges from 30° C. to 70° C.
13. The hot melt adhesive of claim 1 , wherein the weight average molecular weight of the tackifier ranges from 250 g/mol to 2000 g/mol.
14. The hot melt adhesive of any of claim 1 , further comprising:
from 5 wt % to 15 wt % of a filler.
15. The hot melt adhesive of claim 1 , wherein the hot melt adhesive demonstrates a swelling factor of less than 1% as measured 1 week after applying to a polyethylene facestock and a release liner.
16. A method of preparing a hot melt adhesive, the method comprising:
providing one or more styrene block copolymers, a tackifier, a polyisobutylene and a plasticizer oil;
combining the one or more styrene block copolymers, the tackifier, the polyisobutylene and the plasticizer oil,
wherein the number average molecular weight of the polyisobutylene ranges from 700 g/mol to 2500 g/mol,
wherein the adhesive is a pressure sensitive adhesive,
wherein the one or more styrene block copolymers is selected from the group consisting of a styrene isoprene block copolymer, styrene butadiene block copolymer, or combinations thereof; and
the melt index of each of the styrene block copolymers ranges from about 10 g/(10 minute) to about 35 g/(10 minute) measured at 200° C. under pressure of 5 kg weight; and
wherein at least one of the one or more styrene block copolymers is a styrene butadiene block copolymer.
17. A label comprising:
a facestock layer capable of receiving printed indicia; and
an adhesive layer comprising the hot melt adhesive of claim 1 .
18. The label of claim 17 , wherein the thickness of the facestock layer ranges from 0.5 mil to 5 mil.
19. The label of any of claim 17 , further comprising: a release liner.
20. The label of claim 19 , wherein the facestock layer comprises polyethylene.
21. The label of claim 20 , wherein the label has a swelling factor of less than 1% as measured 1 week after applying to the polyethylene facestock and the release liner.
22. A method of applying a label to a surface, the method comprising:
providing a surface having an outer face;
providing a label of claim 17 ; and
adhering the label to the outer face of the surface, thereby applying the label to the surface.
23. A labeled surface comprising:
a surface having an outer face; and
a label of claim 17 adhered to the outer face of the surface.
24. The hot melt adhesive of claim 1 consisting of:
the one or more styrene block copolymers;
the tackifier;
the polyisobutylene; and
0 wt % to 5 wt % of the plasticizer oil,
one or more fillers,
and one or more antioxidants.
25. The hotmelt adhesive of claim 1 , comprising from 15 wt % to 35 wt % polyisobutylene.
26. The hot melt adhesive of claim 1 , comprising from 15 wt % to 55 wt % tackifier.
27. The hot melt adhesive of claim 14 , wherein the filler comprises calcium carbonate.
28. The hot melt adhesive of claim 1 , further comprising: from 0.5 wt % to 1.5 wt % of a phenolic antioxidant.