Repulpable adhesives
The invention relates to a repulpable adhesive comprising orthophosphoric acid, to adhesive tapes comprising at least one layer of such an adhesive, and to the use of adhesive tapes of this kind.
1. Repulpable pressure-sensitive adhesive comprising:
(a) at least one copolymer of (meth)acrylic acid with an ester of (meth)acrylic acid, wherein the amount of (meth)acrylic acid in said copolymer amounts to more than 20% by weight, based on the weight of the pressure-sensitive adhesive; and
(b) 2-5% by weight, based on the pure phosphoric acid content of the pressure-sensitive adhesive, of orthophosphoric acid;
wherein said pressure-sensitive adhesive exhibits improved tack stability compared to a comparison pressure-sensitive adhesive having an adhesive composition identical to said pressure-sensitive adhesive except that said comparison pressure-sensitive adhesive has instead of said orthophosphoric acid an identical content of either (i) diammonium hydrogen phosphate or (ii) a mixture of sodium polyphosphate and alkylphosphonate, and wherein the tack stability of both said pressure-sensitive adhesive and said comparison pressure-sensitive adhesive are measured instantaneously and after four weeks in Rolling-Ball Tack Test C against a base pressure-sensitive adhesive having an adhesive composition identical to said pressure-sensitive adhesive except that said base pressure-sensitive adhesive lacks said orthophosphoric acid.
2. Adhesive tape with repulpability properties, comprising at least one layer of an adhesive according to claim 1 .
3. A method for adhesively bonding filler-containing materials, said method comprising bonding said materials with an adhesive tape according to claim 2 .
4. A method of splicing two materials, said method comprising splicing the materials with an adhesive tape according to claim 2 .
5. Adhesive according to claim 1 , wherein the amount of (meth) acrylic acid in the copolymer in (a) amounts to more than 70% by weight, relative to a total weight of the pressure-sensitive adhesive.
6. Adhesive according to claim 1 , which exhibits improved tack stability compared to a comparison pressure-sensitive adhesive having an adhesive composition identical to said pressure-sensitive adhesive except that said comparison pressure-sensitive adhesive has instead of said orthophosphoric acid an identical content of a mixture of sodium polyphosphate and alkylphosphonate exhibiting a calcium-binding capacity of 120 mg CaO/g of the mixture, and wherein the tack stability of both said pressure-sensitive adhesive and said comparison pressure-sensitive adhesive are measured instantaneously and after four weeks in Rolling-Ball Tack Test C against a base pressure-sensitive adhesive having an adhesive composition identical to said pressure-sensitive adhesive except that said base pressure-sensitive adhesive lacks said orthophosphoric acid.
7. Adhesive according to claim 1 , wherein the amount of (meth)acrylic acid in the copolymer in (a) amounts to more than 80% by weight, relative to a total weight of the pressure-sensitive adhesive.
8. Adhesive according to claim 7 , wherein (a) is a copolymer of acrylic acid and 2-ethylhexyl acrylate.
9. Adhesive according to claim 7 , wherein (a) is a copolymer of acrylic acid, butyl acrylate and vinylcaprolactam.
10. Adhesive according to claim 7 , wherein (a) is a copolymer of acrylic acid and at least one (meth)acrylate monomer selected from the group consisting of alkyl acrylate, alkyl methacrylate, 2-ethoxalyloxyethyl methacrylate and 2-ethoxyethyl acrylate.
11. Repulpable pressure-sensitive adhesive comprising:
(a) at least one copolymer of (meth)acrylic acid with an ester of (meth)acrylic acid, wherein the amount of (meth)acrylic acid in said copolymer amounts to more than 80% by weight, based on the weight of the pressure-sensitive adhesive, and wherein said copolymer is selected from the group consisting of:
(i)copolymers of acrylic acid and 2-ethylhexyl acrylate;
(ii) copolymers of acrylic acid, butyl acrylate and vinylcaprolactam; and
(iii) copolymers of acrylic acid and at least one (meth)acrylate monomer selected from the group consisting of alkyl acrylate, alkyl methacrylate, 2-ethoxalyloxyethyl methacrylate and 2-ethoxyethyl acrylate; and
(b) 2-5% by weight, based on the pure phosphoric acid content of the pressure-sensitive adhesive, of orthophosphoric acid;
wherein said pressure-sensitive adhesive exhibits improved tack stability compared to a comparison pressure-sensitive adhesive having an adhesive composition identical to said pressure-sensitive adhesive except that said comparison pressure-sensitive adhesive has instead of said orthophosphoric acid an identical content of either (i) diammonium hydrogen phosphate or (ii) a mixture of sodium polyphosphate and alkylphosphonate, and wherein the tack stability of both said pressure-sensitive adhesive and said comparison pressure-sensitive adhesive are measured instantaneously and after four weeks in Rolling-Ball Tack Test C against a base pressure-sensitive adhesive having an adhesive composition identical to said pressure-sensitive adhesive except that said base pressure-sensitive adhesive lacks said orthophosphoric acid.
12. Adhesive according to claim 11 , which exhibits improved tack stability compared to a comparison pressure-sensitive adhesive having an adhesive composition identical to said pressure-sensitive adhesive except that said comparison pressure-sensitive adhesive has instead of said orthophosphoric acid an identical content of a mixture of sodium polyphosphate and alkylphosphonate exhibiting a calcium-binding capacity of 120 mg CaO/g of the mixture, and wherein the tack stability of both said pressure-sensitive adhesive and said comparison pressure-sensitive adhesive are measured instantaneously and after four weeks in Rolling-Ball Tack Test C against a base pressure-sensitive adhesive having an adhesive composition identical to said pressure-sensitive adhesive except that said base pressure-sensitive adhesive lacks said orthophosphoric acid.