Double-sided adhesive tape and method for producing the same

A method of producing a double-sided adhesive tape, the double-sided adhesive tape including a polyethylene foam substrate and acrylic-based adhesive layers formed on respective sides thereof, the method comprising the following steps (a) to (e):

• Step (a)
• a step of irradiating a solvent-free photopolymerizable monomer composition containing an acrylic-based monomer and a photopolymerization initiator with ultraviolet rays to produce an acrylic-based polymer A having a weight average molecular weight of 700,000 to 3,000,000 by photopolymerization of the acrylic-based monomer in the absence of a cross-linking agent, whereby a polymer syrup containing the acrylic-based polymer A and an unreacted portion of the acrylic-based monomer is prepared;
• Step (b)
• a step of mixing an adhesion-imparting polymer having a weight average molecular weight of 2,000 to 10,000 with the polymer syrup to prepare an adhesive coating solution;
• Step (c)
• a step of coating release film substrates with the adhesive coating solution to form adhesive coating films;
• Step (d)
• a step of irradiating the adhesive coating films with ultraviolet rays to produce an acrylic-based polymer B having a weight average molecular weight of 350,000 to 650,000 by photopolymerization of the unreacted portion of the acrylic-based monomer in the adhesive coating films in the absence of a cross-linking agent, whereby the acrylic-based adhesive layers are formed from a cured resin composition containing the acrylic-based polymer A, the acrylic-based polymer B, and the adhesion-imparting polymer (wherein a molecular weight distribution of the cured resin composition measured by gel permeation chromatography using tetrahydrofuran is 2.4 to 4.4);
• and
• Step (e)
• a step of laminating the acrylic-based adhesive layers on the release film substrates to respective sides of an electron beam cross-linked polyethylene foam substrate.

A double-sided adhesive tape comprising a polyethylene foam substrate and acrylic-based adhesive layers formed on respective sides of the polyethylene foam substrate, wherein

• the polyethylene foam substrate has been subjected to electron beam cross-linking treatment,
• the acrylic-based adhesive layers are formed from a cured resin composition formed by irradiating a solvent-free photopolymerizable monomer composition containing an acrylic-based monomer and a photopolymerization initiator with ultraviolet rays to photo-polymerize the acrylic-based monomer,
• the cured resin composition contains an adhesion-imparting polymer having a weight average molecular weight of 2,000 to 10,000, an acrylic-based polymer A obtained by photopolymerization in the absence of a cross-linking agent and having a weight average molecular weight of 700,000 to 3,000,000, and an acrylic-based polymer B obtained by photopolymerization in the absence of a cross-linking agent and in the presence of the adhesion-imparting polymer and the acrylic-based polymer A and having a weight average molecular weight of 350,000 to 650,000, and
• a molecular weight distribution of the cured resin composition measured by gel permeation chromatography using tetrahydrofuran is 2.4 to 4.4.