Hot melt pressure sensitive adhesives for paper labels
A HMPSA is provided that preferably includes at least a) from 30 to 50% of a mixture of triblock and diblock styrenic copolymers having an overall styrene content comprised between 14 and 40%, b) from 40 to 55% of a tackifying resin with a softening temperature comprised between 70 and 150° C. obtainable by hydrogenating, polymerizing or copolymerizing mixtures of aliphatic unsaturated hydrocarbons having about 5, 9 or 10 carbon atoms; c) from 4 to 20% of a hydrocarbon oil with an aromatic content less than 15%; d) from 1 to 6% of a filler selected among calcium carbonate or a low molecular weight homopolymer or copolymer of polyethylene. A laminated system is also provided that includes at least an adhesive layer utilizing the HMPSA and paper facestock. Also included are PSA labels obtainable from the laminated system with a reduced tendency to discolor after storage.
1. A hot melt pressure sensitive adhesive (HMPSA) composition comprising:
a) from 30 to 50% of a mixture of styrenic block copolymers comprising:
10 to 70% of at least one SX 1 S triblock copolymer, and
30 to 90% of at least one SX 2 diblock copolymer;
wherein:
S represents a polymerized segment of a styrene monomer,
X 1 and X 2 , are identical or different, and each represents an elastomeric polymerized segment of one or two monomers comprising isoprene, butadiene or their respective hydrogenated derivatives;
wherein the overall styrene monomer content in said mixture of styrenic block copolymers is between 14 and 40%;
b) from 40 to 55% of one or more tackifying resin(s), each of the one or more tackifying resin(s) having a softening temperature of between 70 and 150° C., wherein the one or more tackifying resin(s) comprises a tackifying resin (i) obtainable by hydrogenating, polymerizing or copolymerizing mixtures of aliphatic unsaturated hydrocarbons having from 5, 9 or 10 carbon atoms;
c) from 4 to 20% of a hydrocarbon oil with an aromatic content less than 15%; and
d) from 1 to 6% of a filler comprising a low number average molecular weight homopolymer or copolymer of polyethylene.
2. The HMPSA composition according to claim 1 , wherein the mixture of styrenic block copolymers includes 10 to 30% of SX 1 S triblocks and 70 to 90% of SX 2 diblocks.
3. The HMPSA composition according claim 1 , wherein the elastomeric polymerized segments X 1 and X 2 are the same monomer.
4. The HMPSA composition according to claim 1 , wherein the overall styrene monomer content in said mixture of styrenic block copolymers is from 15 to 30%.
5. The HMPSA composition according to claim 1 , wherein X 1 and X 2 represent a polymerized segment of isoprene or a polymerized segment of butadiene.
6. The HMPSA composition according to claim 1 , wherein the tackifying resin(s) (i) are in admixture with up to 50% of one or more tackifying resin(s) comprising:
a tackifying resin (ii) comprising a natural or chemically modified rosin;
a tackifying resin (iii) comprising a terpenic resin, optionally modified by action of phenols; or
a tackifying resin (iv) comprising a copolymer based on a natural terpene.
7. The HMPSA composition according to claim 6 , wherein the admixture comprises about 50% of resin (i) and about 50% of resin (ii), (iii) or (iv).
8. The HMPSA composition according to claim 1 , wherein the softening temperature of each of the one or more tackifying resin(s) is between 80 and 140° C.
9. The HMPSA composition according to claim 1 , wherein the hydrocarbon oil has an aromatic content which is less than 7%.
10. The HMPSA composition according to claim 1 , comprising:
from 32 to 40% of component a);
from 45 to 50% of component b);
from 10 to 20% of component c); and
from 3 to 5% of component d).
11. The HMPSA composition according to claim 1 , further comprising 0.5 to 2% of one or more stabilizer or antioxidant.
12. A laminated system comprising:
an adhesive layer comprising the HMPSA composition as defined in claim 1 ,
a paper facestock in contact with said adhesive layer, and
a release liner in contact with the adhesive layer.
13. The laminated system according to claim 12 , wherein the paper is a white paper comprising a grammage of between 60 and 100 g/m 2 .
14. A self-adhesive label comprising the laminated system of claim 12 .
15. The HMPSA composition according to claim 1 , wherein the softening temperature of each of the one or more tackifying resin is between 85 and 110° C.
16. A hot melt pressure sensitive adhesive (HMPSA) composition comprising:
a) from 30 to 50% of a mixture of styrenic block copolymers comprising:
10 to 70% of at least one SX 1 S triblock copolymer, and
30 to 90% of at least one SX 2 diblock copolymer;
wherein:
S represents a polymerized segment of a styrene monomer,
X 1 and X 2 , are identical or different, and each represents an elastomeric polymerized segment of one or two monomers comprising isoprene, butadiene or their respective hydrogenated derivatives;
b) from 40 to 55% of one or more tackifying resin(s), each of the one or more tackifying resin(s) having a softening temperature of between 70 and 150° C., wherein the one or more tackifying resin(s) comprises a tackifying resin (i) obtainable by hydrogenating, polymerizing or copolymerizing mixtures of aliphatic unsaturated hydrocarbons having from 5, 9 or 10 carbon atoms;
c) from 4 to 20% of a hydrocarbon oil with an aromatic content less than 15%; and
d) from 1 to 6% of a filler comprising a low molecular weight homopolymer or copolymer of polyethylene with an average number molecular weight between 1 and 5 kDa.
17. A hot melt pressure sensitive adhesive (HMPSA) composition comprising:
a) from 30 to 50% of a mixture of styrenic block copolymers comprising:
10 to 70% of at least one SX 1 S triblock copolymer, and
30 to 90% of at least one SX 2 diblock copolymer;
wherein:
S represents a polymerized segment of a styrene monomer,
X 1 and X 2 , are identical or different, and each represents an elastomeric polymerized segment of one or two monomers comprising isoprene, butadiene or their respective hydrogenated derivatives;
b) from 40 to 55% of one or more tackifying resin(s), each of the one or more tackifying resin(s) having a softening temperature between 70 and 150° C., wherein the one or more tackifying resin(s) comprises a tackifying resin (i) obtainable by hydrogenating, polymerizing or copolymerizing mixtures of aliphatic unsaturated hydrocarbons having from 5, 9 or 10 carbon atoms;
c) from 4 to 20% of a hydrocarbon oil with an aromatic content less than 15%; and
d) from 3 to 5% of a filler comprising a low number average molecular weight homopolymer or copolymer of polyethylene.
18. A hot melt pressure sensitive adhesive (HMPSA) composition comprising:
a) from 30 to 50% of a mixture of styrenic block copolymers comprising:
10 to 70% of at least one SX 1 S triblock copolymer, and
30 to 90% of at least one SX 2 diblock copolymer;
wherein:
S represents a polymerized segment of a styrene monomer,
X 1 and X 2 , are identical or different, and each represents an elastomeric polymerized segment of one or two monomers comprising isoprene, butadiene or their respective hydrogenated derivatives;
b) from 40 to 55% of one or more tackifying resin(s), each of the one or more tackifying resin(s) having a softening temperature between 70 and 150° C., wherein the one or more tackifying resin(s) comprises a tackifying resin (i) obtainable by hydrogenating, polymerizing or copolymerizing mixtures of aliphatic unsaturated hydrocarbons having from 5, 9 or 10 carbon atoms;
c) from 4 to 20% of a hydrocarbon oil with an aromatic content less than 15%; and
d) from 3 to 5% of a filler comprising a low molecular weight homopolymer or copolymer of polyethylene with a number average molecular weight between 1 and 5 kDa.
19. A hot melt pressure sensitive adhesive (HMPSA) composition comprising:
a) from 25 to 35% of a mixture of styrenic block copolymers comprising:
a first mixture comprising about 25% of a styrene-butadiene-styrene copolymer having a weight average molecular weight of about 170 kDa and about 75% of a styrene-butadiene copolymer having a weight average molecular weight of about 70 kDa, wherein said first mixture comprises about 30% styrene, and
a second mixture comprising a styrene-butadiene copolymer having about 30% styrene and a weight average molecular weight of about 100 kDa;
b) about 47% of a tackifying resin comprising a hydrogenated dicyclopentadiene modified by an aromatic compound, having a softening temperature of about 100° C.; a hydrogenated dicyclopentadiene modified by an aromatic compound, having a softening temperature of about 90° C.; a terpene phenolic resin, having a softening temperature of about 95° C.; or mixtures thereof;
c) from 12 to 18% of a hydrocarbon oil comprising about 5% aromatic hydrocarbon, about 47% paraffinic carbon, and about 48% naphthenic carbon;
d) from 3 to 5% of a filler comprising a low molecular weight homopolymer or copolymer of polyethylene with an average number molecular weight between 1 and 5 kDa.
20. The HMPSA composition according to claim 1 , wherein the composition exhibits a ΔE of from about 1.4 to about 2.5.
21. A hot melt pressure sensitive adhesive (HMPSA) composition comprising:
a) from 30 to 50% of a mixture of styrenic block copolymers comprising:
10 to 70% of at least one SX 1 S triblock copolymer, and
30 to 90% of at least one SX 2 diblock copolymer;
wherein:
S represents a polymerized segment of a styrene monomer,
X 1 and X 2 , are identical or different, and each represents an elastomeric polymerized segment of one or two monomers comprising isoprene, butadiene or their respective hydrogenated derivatives;
wherein the overall styrene monomer content in said mixture of styrenic block copolymers is between 14 and 40%;
b) from 40 to 55% of one or more tackifying resin(s), each of the one or more tackifying resin(s) having a softening temperature of between 70 and 150° C., wherein the one or more tackifying resin(s) comprises a tackifying resin (i) comprising residues of aliphatic unsaturated hydrocarbons having from 5, 9 or 10 carbon atoms;
c) from 4 to 20% of a hydrocarbon oil with an aromatic content less than 15%; and
d) from 1 to 6% of a filler comprising a low number average molecular weight homopolymer or copolymer of polyethylene.
22. The HMPSA composition according to claim 16 , wherein the composition exhibits a ΔE of from about 1.4 to about 2.5.
23. The HMPSA composition according to claim 17 , wherein the composition exhibits a ΔE of from about 1.4 to about 2.5.
24. The HMPSA composition according to claim 18 , wherein the composition exhibits a ΔE of from about 1.4 to about 2.5.
25. The HMPSA composition according to claim 21 , wherein the composition exhibits a ΔE of from about 1.4 to about 2.5.