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

Abstract

An acrylic pressure sensitive adhesive composition comprising 5 to 75 parts by weight of an adherent polymer (a) comprising (meth)acrylic ester component units as principal structural units and having a weight average molecular weight of 50,000 or more; 5 to 40 parts by weight of a tackifier resin (b) comprising (meth)acrylic ester component units as principal structural units and having a weight average molecular weight of 20,000 or less; and 20 to 90 parts by weight of monomers (c) whose principal component is a (meth)acrylic ester, wherein substantially no solvent is contained is provided. Further, a pressure sensitive adhesive tape having a pressure sensitive adhesive layer superimposed on a support surface is provided by coating the support surface with the above acrylic pressure sensitive adhesive composition, which contain a partial polymerizate, and carrying out a polymerization reaction on the support surface.

Description

field of invention [0001] This application is a divisional application of the patent application with the international application number PCT / JP00 / 08932 and the national application number 00819089.5. [0002] The present invention relates to a substantially solvent-free acrylic polymer composition, an acrylic pressure-sensitive adhesive tape prepared from the composition, and a method for preparing the composition and the tape. Background of the invention [0003] Acrylic monomers have excellent polymerizability and can be polymerized using a variety of reaction systems, including solution polymerization, suspension polymerization, emulsion polymerization and bulk polymerization techniques. [0004] For example, the following methods have been proposed for the preparation of acrylic polymers. One method involves heating a mixture of acrylic monomer thiol in the presence of oxygen at 20 to 200°C, thereby performing bulk polymerization (see Japanese Patent Publication No. 5...

AI Technical Summary

Problems solved by technology

[0006] There is a disadvantage of using a barrel device for the reaction: the reaction needs to set the reaction temperature in a high temperature region, and the result is that the molecular weight distribution of the obtained polymer will become broad and the molecular weight will become polydisperse as the temperature control accuracy decreases.

Therefore, there arises the problem that it is necessary to provide a very high-performance cooling device for suppressing heat generation

[0025] However, the methods disclosed in these published specifications have a disadvantage that since the monomer used as a solvent is polymerized by thermal polymerization, there will always be a coating surface portion where there is a high possibility of contact with oxygen in the air. Risk of terminating the reaction on contact, in which case it is difficult for the polymerization to proceed uniformly along the thickness of the layer

[0029] However, the pressure-sensitive adhesive tapes produced from the pressure-sensitive adhesives obtained by the above-mentioned polymerization method have a disadvantage that not only high energy is required for drying, but also that the pressure-sensitive adhesive tapes have an odor due to residual solvents.

In the initial polymerization of the monomer, prepolymerization is usually carried out by photopolymerization, because as mentioned above, if thermal polymerization is used for the partial polymerization of the monomer, the control of the reaction will be very difficult