Low Viscosity, Hot-Melt Stable Adhesive Compositions

1 . Low viscosity, hot-melt stable adhesive composition, comprising:

a) at least one block copolymer, comprising at least two terminal poly(vinyl aromatic) blocks and at least one central block of randomly copolymerised isoprene/butadiene mixtures in an isoprene/butadiene weight ratio of from 45/55 to 55/45, having a poly(vinyl aromatic) content in the range of from 17 to 20%, a total apparent molecular weight in the range of from 180,000 to 190,000, a content of 1,2-vinyl bonds and/or 3,4 vinyl bonds of at most 15 wt % in the conjugated diene blocks, and a coupling efficiency in the range of from 63-80%, and occurring in a weight proportion of from 40 to 45 wt %, relative to the weight of the complete composition,

b) an aliphatic/aromatic hydrocarbon tackifying resin, containing less than 16% by weight of aromatic structure as determined by H-NMR, a differential scanning calorimetry (DSC) glass transition temperature (Tg) between 30 and 55° C., and a Ring and Ball softening point between 85 and 95° C., in a weight proportion of from 45 to 55 wt %, relative to the weight of the complete composition,

c) a plasticizer, in a weight proportion of from 5 to 15 wt %, relative to the weight of the complete composition;

and having a stable hot-melt viscosity of plus or minus 5% of the starting value after 24 hours at 177° C. and having a hot-melt viscosity of ≦80 Pa·s at 177° C.

2 . Low viscosity, hot-melt stable adhesive composition according to claim 1 , wherein the block copolymer component (a) is a S—(I/B)—S block copolymer, wherein S represents a block of polymerised substantially pure styrene and (I/B) represents a randomly copolymerised isoprene/butadiene block, and wherein the Poly Styrene Content is in the range of from 17 to 20 wt %.

3 . Low viscosity, hot-melt stable adhesive composition according to claim 2 , wherein the component (a) block copolymer has an apparent total molecular weight of from 180,000 to 185,000, an isoprene/butadiene weight ratio in the range of from 45/55 to 55/45, and a content of 1,2-vinyl bonds and/or 3,4-vinyl bonds, each in a proportion of from 5 to 10 wt % in the conjugated diene blocks.

4 . Low viscosity, hot-melt stable adhesive composition according to claim 1 , wherein the component (b) has an H-NMR aromatic structure in the range of from 4 to 10 wt %.

5 . Low viscosity, hot-melt stable adhesive compositions according to claim 1 , wherein the component (c) is a mineral oil.

6 . Adhesive tapes and labels, comprising a composition according to claims 1 - 5 on a carrier.

7 . Packaging tapes, comprising a composition according to claims 1 - 5 on a carrier.

8 . Block copolymers to be used in the low viscosity, hot-melt stable adhesive composition according to claims 1 - 5 , characterized in that they comprise at least two terminal poly(vinyl aromatic) blocks and at least one central block of randomly copolymerised isoprene/butadiene mixtures in an isoprene/butadiene weight ratio of from 45/55 to 55/45, having a poly(vinyl aromatic) content in the range of from 17 to 20%, a total apparent molecular weight in the range of from 180,000 to 190,000, a content of 1,2-vinyl bonds and/or 3,4 vinyl bonds, each in a proportion of at most 15 wt % in the conjugated diene blocks, and a coupling efficiency in the range of from 63-87%.

9 . Block copolymers according to claim 8 , characterized in that they have the structure S—(I/B)—S, wherein S represents a block of polymerised substantially pure styrene and (I/B) represents a randomly copolymerised isoprene/butadiene block.

10 . Block copolymers according to claims 8 and 9 , characterized in that they have an apparent total molecular weight of from 180,000 to 185,000, an isoprene/butadiene weight ratio in the range of from 45/55 to 55/45 and a content of 1,2-vinyl bonds and/or 3,4-vinyl bonds, each in a proportion of from 5 to 10 wt % in the conjugated diene blocks.

11 . A low viscosity, hot-melt stable adhesive composition, comprising:

a) at least one block copolymer, comprising at least two terminal poly(vinyl aromatic) blocks and at least one central block of randomly copolymerised isoprene/butadiene mixtures in an isoprene/butadiene weight ratio of from 45/55 to 55/45, having a poly(vinyl aromatic) content in the range of from 17% to 20%, a total apparent molecular weight in the range of from 180,000 to 190,000, a content of 1,2-vinyl bonds and/or 3,4 vinyl bonds of at most 15 wt % in the conjugated diene blocks, and a coupling efficiency in the range of from 63% to 80%, and occurring in a weight proportion of from 40 wt % to 45 wt %, relative to the weight of the complete composition,

b) an aliphatic/aromatic hydrocarbon tackifying resin, containing less than 16% by weight of aromatic structure as determined by H-NMR, a differential scanning calorimetry (DSC) glass transition temperature (Tg) between 30° C. and 55° C., and a Ring and Ball softening point between 85° C. and 95° C., in a weight proportion of from 45 to 55 wt %, relative to the weight of the complete composition,

c) a plasticizer, in a weight proportion of from 5 wt % to 15 wt %, relative to the weight of the complete composition; and having a stable hot-melt viscosity of plus or minus 5% of the starting value after 24 hours at 177° C. and having a hot-melt viscosity of ≦80 Pa·s at 177° C.

12 . The low viscosity, hot-melt stable adhesive composition of claim 11 , wherein the block copolymer component (a) is a S—(I/B)—S block copolymer, wherein S represents a block of polymerised substantially pure styrene and (I/B) represents a randomly copolymerised isoprene/butadiene block, and wherein the Poly Styrene Content is in the range of from 17 wt % to 20 wt %.

13 . The low viscosity, hot-melt stable adhesive composition of claim 12 , wherein the component (a) block copolymer has an apparent total molecular weight of from 180,000 to 185,000, an isoprene/butadiene weight ratio in the range of from 45/55 to 55/45, and a content of 1,2-vinyl bonds and/or 3,4-vinyl bonds, each in a proportion of from 5 to 10 wt % in the conjugated diene blocks.

14 . The low viscosity, hot-melt stable adhesive composition of claim 1 , wherein the component (b) has an H-NMR aromatic structure in the range of from 4 wt % to 10 wt %.

15 . The low viscosity, hot-melt stable adhesive composition of claim 1 , wherein the component (c) is a mineral oil.

16 . An adhesive tape and label, comprising a carrier having disposed thereon a low viscosity, hot-melt stable adhesive composition, comprising:

a) at least one block copolymer, comprising at least two terminal poly(vinyl aromatic) blocks and at least one central block of randomly copolymerised isoprene/butadiene mixtures in an isoprene/butadiene weight ratio of from 45/55 to 55/45, having a poly(vinyl aromatic) content in the range of from 17% to 20%, a total apparent molecular weight in the range of from 180,000 to 190,000, a content of 1,2-vinyl bonds and/or 3,4 vinyl bonds of at most 15 wt % in the conjugated diene blocks, and a coupling efficiency in the range of from 63% to 80%, and occurring in a weight proportion of from 40 wt % to 45 wt %, relative to the weight of the complete composition,

b) an aliphatic/aromatic hydrocarbon tackifying resin, containing less than 16% by weight of aromatic structure as determined by H-NMR, a differential scanning calorimetry (DSC) glass transition temperature (Tg) between 30° C. and 55° C., and a Ring and Ball softening point between 85° C. and 95° C., in a weight proportion of from 45 to 55 wt %, relative to the weight of the complete composition,

c) a plasticizer, in a weight proportion of from 5 wt % to 15 wt %, relative to the weight of the complete composition;

and having a stable hot-melt viscosity of plus or minus 5% of the starting value after 24 hours at 177° C. and having a hot-melt viscosity of ≦80 Pa·s at 177° C.

17 . The adhesive tape and label of claim 16 , wherein the block copolymer component (a) is a S—(I/B)—S block copolymer, wherein S represents a block of polymerised substantially pure styrene and (I/B) represents a randomly copolymerised isoprene/butadiene block, and wherein the Poly Styrene Content is in the range of from 17 wt % to 20 wt %.

18 . The adhesive tape and label of claim 17 , wherein the component (a) block copolymer has an apparent total molecular weight of from 180,000 to 185,000, an isoprene/butadiene weight ratio in the range of from 45/55 to 55/45, and a content of 1,2-vinyl bonds and/or 3,4-vinyl bonds, each in a proportion of from 5 to 10 wt % in the conjugated diene blocks.

19 . The adhesive tape and label of claim 16 , wherein the component (b) has an H-NMR aromatic structure in the range of from 4 wt % to 10 wt %.

20 . The adhesive tape and label of claim 16 , wherein the component (c) is a mineral oil.

21 . A packaging tape, comprising a carrier having disposed thereon a low viscosity, hot-melt stable adhesive composition, comprising:

a) at least one block copolymer, comprising at least two terminal poly(vinyl aromatic) blocks and at least one central block of randomly copolymerised isoprene/butadiene mixtures in an isoprene/butadiene weight ratio of from 45/55 to 55/45, having a poly(vinyl aromatic) content in the range of from 17% to 20%, a total apparent molecular weight in the range of from 180,000 to 190,000, a content of 1,2-vinyl bonds and/or 3,4 vinyl bonds of at most 15 wt % in the conjugated diene blocks, and a coupling efficiency in the range of from 63% to 80%, and occurring in a weight proportion of from 40 wt % to 45 wt %, relative to the weight of the complete composition,

b) an aliphatic/aromatic hydrocarbon tackifying resin, containing less than 16% by weight of aromatic structure as determined by H-NMR, a differential scanning calorimetry (DSC) glass transition temperature (Tg) between 30° C. and 55° C., and a Ring and Ball softening point between 85° C. and 95° C., in a weight proportion of from 45 to 55 wt %, relative to the weight of the complete composition,

c) a plasticizer, in a weight proportion of from 5 wt % to 15 wt %, relative to the weight of the complete composition;

and having a stable hot-melt viscosity of plus or minus 5% of the starting value after 24 hours at 177° C. and having a hot-melt viscosity of ≦80 Pa·s at 177° C.

22 . The packaging tape of claim 21 , wherein the block copolymer component (a) is a S—(I/B)—S block copolymer, wherein S represents a block of polymerised substantially pure styrene and (I/B) represents a randomly copolymerised isoprene/butadiene block, and wherein the Poly Styrene Content is in the range of from 17 wt % to 20 wt %.

23 . The packaging tape of claim 22 , wherein the component (a) block copolymer has an apparent total molecular weight of from 180,000 to 185,000, an isoprene/butadiene weight ratio in the range of from 45/55 to 55/45, and a content of 1,2-vinyl bonds and/or 3,4-vinyl bonds, each in a proportion of from 5 to 10 wt % in the conjugated diene blocks.

24 . The packaging tape of claim 21 , wherein the component (b) has an H-NMR aromatic structure in the range of from 4 wt % to 10 wt %.

25 . The packaging tape of claim 21 , wherein the component (c) is a mineral oil comprising a composition according to claims 1 - 5 on a carrier.

26 . Block copolymers to be used in the low viscosity, hot-melt stable adhesive composition comprising: at least one block copolymer, comprising at least two terminal poly(vinyl aromatic) blocks and at least one central block of randomly copolymerised isoprene/butadiene mixtures in an isoprene/butadiene weight ratio of from 45/55 to 55/45, having a poly(vinyl aromatic) content in the range of from 17% to 20%, a total apparent molecular weight in the range of from 180,000 to 190,000, a content of 1,2-vinyl bonds and/or 3,4 vinyl bonds of at most 15 wt % in the conjugated diene blocks, and a coupling efficiency in the range of from 63% to 87%, and occurring in a weight proportion of from 40 wt % to 45 wt %, relative to the weight of the complete composition.

27 . The block copolymers of claim 26 , characterized in that they have the structure S—(I/B)—S, wherein S represents a block of polymerised substantially pure styrene and (I/B) represents a randomly copolymerised isoprene/butadiene block.

28 . The block copolymers of claim 26 , characterized in that they have an apparent total molecular weight of from 180,000 to 185,000, an isoprene/butadiene weight ratio in the range of from 45/55 to 55/45 and a content of 1,2-vinyl bonds and/or 3,4-vinyl bonds, each in a proportion of from 5 to 10 wt % in the conjugated diene blocks.

29 . The block copolymers of claim 27 , characterized in that they have an apparent total molecular weight of from 180,000 to 185,000, an isoprene/butadiene weight ratio in the range of from 45/55 to 55/45 and a content of 1,2-vinyl bonds and/or 3,4-vinyl bonds, each in a proportion of from 5 to 10 wt % in the conjugated diene blocks.

30 . The block copolymer of claim 28 wherein the Poly Styrene Content is in the range of from 17 wt % to 20 wt %.

31 . The block copolymer of claim 29 wherein the Poly Styrene Content is in the range of from 17 wt % to 20 wt %.