Abstract: A finely foamed pressure-sensitive adhesive tape or sheet possessing a pressure-sensitive adhesive layer having a fine cell size and cell wall thickness is disclosed. The tape or sheet is obtained by impregnating the pressure-sensitive adhesive tape or sheet with carbon dioxide in a liquid state or a supercritical state, and reducing the pressure to foam the pressure-sensitive adhesive layer. The main component of the pressure-sensitive adhesive layer is, for example, an acrylic resin or a rubber-based resin. The method provides a finely foamed pressure-sensitive adhesive tape or resin possessing a pressure-sensitive adhesive layer having a fine cell structure such that an average cell size d is from 0.01 to 1000 &mgr;m, an average cell wall thickness t is from 0.01 to 2000 &mgr;m, and the ratio t/d is in the range of from 0.5 to 3.5.

Abstract: An acrylic pressure-sensitive adhesive composition which contains a high molecular weight polymer, is excellent in cohesive force and adhesive strength and can be prepared without using an organic solvent. The acrylic pressure-sensitive adhesive composition is produced by a process which comprises radical-polymerizing monomers containing an alkyl (meth)acrylate using carbon dioxide as a diluent to thereby prepare a pressure-sensitive adhesive composition containing an acrylic polymer having a weight average molecular weight of 400,000 or more. The polymerization pressure ranges from, for example, about 5.7 to 40 MPa, AND the polymerization temperature ranges from, for example, about 20 to 100° C.

Abstract: A method and apparatus for producing a foamed pressure-sensitive adhesive tape or sheet having a fine cell structure with a good production efficiency without through complicated steps are provided. The method comprises subjecting a mixture containing monomers of a polymer constituting a foamed pressure-sensitive adhesive layer to polymerization in an inert fluid in a supercritical state or a liquid state under pressure, and ejecting the polymerized composition obtained on a substrate under a pressure lower than the pressure in the polymerization to form a foamed pressure-sensitive adhesive layer applied on the substrate. The apparatus comprises a pressure vessel for polymerizing monomers of a polymer constituting a foamed pressure-sensitive adhesive layer under pressure, an inert fluid supplying means for supplying an inert fluid in a supercritical state or a liquid state to the pressure vessel, and an ejection means for ejecting the polymerized composition obtained by polymerizing the monomers.

Abstract: A sheet for protecting paint film comprising a support having formed thereon a rubber adhesive layer comprising an isobutylene polymer having a degree of dispersion of from 1 to 2.3 and a weight average molecular weight of 300,000 to 600,000 (the domain A in the FIGURE) as the base polymer.The paint film protecting sheet has the compatibility of the prevention of the occurrence of a microdeformation and a good peelability. That is, when an article such as automobiles having a paint film applied with the protecting sheet is placed outdoors for a long period of time at high temperature, the paint film is hard to deform and the sheet can be easily peeled even after adhering for a long period of time.