Acrylic polymer compositions, acrylic pressure-sensitive adhesion tapes and process for producing the same

A process for producing a pressure sensitive adhesive tape, comprising coating a support surface with a mixture of 100 parts by weight of an acrylic pressure sensitive adhesive composition and 0.01 to 3 parts by weight of a polymerization initiator at a thickness of 0.01 to 1.0 mm and polymerizing the mixture,

• said acrylic pressure sensitive adhesive composition comprising:
• (a) 5 to 75 parts by weight of an adherent polymer comprising (meth)acrylic ester component units as principal structural units and having a weight avenge molecular weight of 50,000 or more,
• (b) 5 to 40 parts by weight of a tackifier resin comprising (meth)acrylic ester component units as principal structural units and having a weight avenge molecular weight off 20,000 or less, and
• (c) 20 to 90 parts by weight of monomers whose principal component is a (meth)acrylic ester,
• provided that the sum of component (a), component (b) and component (c) is 100 parts by weight,
• substantially no solvent contained in the acrylic pressure sensitive adhesive composition.

A pressure sensitive adhesive tape obtained by coating a support surface with a mixture of 100 parts by weight of an acrylic pressure sensitive adhesive composition and 0.01 to 3 parts by weight of a polymerization initiator at a thickness of 0.01 to 1.0 mm and polymerizing the mixture,

• said acrylic pressure sensitive adhesive composition comprising:
• (a) 5 to 75 parts by weight of an adherent polymer comprising (meth)acrylic ester component units as principal structural units and having a weight average molecular weight of 50,000 or more,
• (b) 5 to 40 parts by weight of a tackifier resin comprising (meth)acrylic ester component units as principal structural units and having a weight average molecular weight of 20,000 or less, and
• (c) 20 to 90 parts by weight of monomers whose principal component is a (meth)acrylic ester,
• provided that the sum of component (a), component (b) and component (c) is 100 parts by weight,
• substantially no solvent contained in the acrylic pressure sensitive adhesive composition.

An acrylic pressure sensitive adhesive tape comprising a support and, superimposed on at least one surface thereof, a pressure sensitive adhesive layer,

• said pressure sensitive adhesive layer formed by coating the support surface with a pressure sensitive adhesive composition and photopolymerizing the pressure sensitive adhesive composition,
• said pressure sensitive adhesive composition comprising:
• a partial polymerizate of monomers each having a polymerizable unsaturated bond whose principal component is an acrylic acid alkyl ester, said partial polymerizate containing polymers of the monomers in an amount of 5% by weight or more, wherein the partial polymerizate is a partial polymerizate obtained through a process comprising mixing 0.0001 to 0.5 part by weight of a polymerization initiator having a 10-hr half-life temperature of 41.0° C. or below with 100 parts by weight of monomers each having a polymerizable unsaturated bond whose principal component is an acrylic acid alkyl ester, initiating a polymerization reaction of the monomers each having a polymerizable unsaturated bond and, after the initiation of the polymerization reaction, increasing a maximum temperature of reaction mixture to 100-140° C. with the use of self-exothermic property of reaction system exerted by consumption of the polymerization initiator so that 5 to 50% by weight of the employed monomers each having a polymerizable unsaturated bond are polyemized,
• a crosslinking agent, and
• a photopolymerization initiator.

A process for producing an acrylic pressure sensitive adhesive tape, comprising coating at least one surface of a support with a pressure sensitive adhesive composition so as to form a coating layer and irradiating the coating layer with light so that the pressure sensitive adhesive composition is photopolymerized to thereby obtain the pressure sensitive adhesive layer superimposed on the support surface,

• said pressure sensitive adhesive composition comprising:
• a partial polymerizate of monomers each having a polymerizable unsaturated bond whose principal component is an acrylic acid alkyl ester, said partial polymerizate containing polymers of the monomers in an amount of 5% by weight or mote, wherein the partial polymerizate is a partial polymerizate obtained through a process comprising mixing 0.0001 to 0.5 part by weight of a polymerization initiator having a 10-hr half-life temperature of 41.0° C. or below with 100 parts by weight of monomers each having a polymerizable unsaturated bond whose principal component is an acrylic acid alkyl ester, initiating a polymerization reaction of the monomers each having a polymerizable unsaturated bond and, after the initiation of the polymerization reaction, increasing a maximum temperature of reaction mixture to 100-140° C. with the use of self-exothermic property of reaction system exerted by consumption of the polymerization initiator so that 5 to 50% by weight of the employed monomers each having a polymerizable unsaturated bond are polyermized,
• a crosslinking agent, and
• a photopolymerization initiator.

An acrylic pressure sensitive adhesive, tape comprising a support and, superimposed on at least one surface thereof, a pressure sensitive adhesive layer,

• said pressure sensitive adhesive layer formed by coating the support surface with a pressure sensitive adhesive composition and photopolymerizing the pressure sensitive adhesive composition,
• said pressure sensitive adhesive composition comprising:
• a partial polymerizate of monomers each having a polymerizable unsaturated bond whose principal component is an acrylic acid alkyl ester, said partial polymerizate containing polymers of the monomers in an amount of 5% by weight or more, wherein the partial polymerizate is a partial polymerizate obtained through a process comprising mixing 0.0001 to 0.5 part by weight of a polymerization initiator having a 10-hr half-life temperature of 41.0° C. or below with 100 parts by weight of monomers each having a polymerizable unsaturated bond whose principal component is an acrylic acid alkyl ester, initiating a polymerization reaction of the monomers each having a polymerizable unsaturated bond, increasing a maximum temperature of reaction mixture to 100-140° C. with the use of self-exothermic property of reaction system exerted by consumption of the polymerization initiator after the initiation of the polymerization reaction, and additionally introducing the monomers each having a polymerizable unsaturated bond as a cooling operation to thereby rapidly lower the temperature of the reaction mixture to below 100° C. so that 5 to 50% by weight of the monomers each having a polymerizable unsaturated bond, employed in the polymerization, are polymerized,
• a crosslinking agent, and
• a photopolymerization initiator.

A process for producing an acrylic pressure sensitive adhesive tape, comprising coating at least one surface of a support with a pressure sensitive adhesive composition so as to form a coating layer and irradiating the coating layer with light so that the pressure sensitive adhesive composition is photopolymerized to thereby obtain the pressure sensitive adhesive layer superimposed on the support surface,

• said pressure sensitive adhesive composition comprising:
• a partial polymerizate of monomers each having a polymerizable unsaturated bond whose principal component is an acrylic acid alkyl ester, said partial polymerizate containing polymers of the monomers in an amount of 5% by weight or more, wherein the partial polymerizate is a partial polymerizate obtained through a process of comprising mixing 0.0001 to 0.5 part by weight of a polymerization initiator having a 10-hr half-life temperature of 41.0° C. or below with 100 parts by weight of monomers each having a polymerizable unsaturated bond whose principal component is an acrylic acid alkyl ester, initiating a polymerization reaction of the monomers each having a polymerizable unsaturated bond, increasing a maximum temperature of reaction mixture to 100-400° C. with the use of self-exothermic property of reaction system exerted by consumption of the polymerization initiator after the initiation of the polymerization reaction, and additionally introducing the monomers each having a polymerizable unsaturated bond as a cooling operation to thereby rapidly lower the temperature of the reaction mixture to below 100° C. so that 5 to 50% by weight of the monomers each having a polymerizable unsaturated bond, employed in the polymerization, are polymerized,
• a crosslinking agent, and
• a photopolymerization initiator.