Patent ID: 6391974
Filing Date: 2002-05-21
Classification: C08F,C09J

Abstract:
A pressure-sensitive adhesive comprising an olefin-based copolymer, which copolymer satisfies the following requirements (1) and (2):(1) the olefin-based copolymer has a tensile strength at break of 2.0 MPa or less measured according to JIS K 6251, and (2) an elongation at break EB(%) measured according to JIS K 6251 of a resin composition essentially consisting of (i) the olefin-based copolymer and (ii) either of below-mentioned polypropylene-based resins (a) and (b) satisfies the following formula (1), wherein: S[2/6]&gE;âˆ’800â€ƒâ€ƒ(1) (2-1) the polypropylene-based resin satisfies the following requirements (i) and (ii): (i) the propylene-based resin is (a) a propylene-ethylene random copolymer having a melt flow rate of 3.0Â±0.5 g/10 min. measured at 230Â° C. under a load of 2.16 kg, and having an ethylene unit content of 3.5Â±1% by weight, or (b) a propylene-ethylene random copolymer having a melt flow rate of 1.0Â±0.5 g/10 min. measured at 230Â° C. under a load of 2.16 kg, and having an ethylene unit content of 5.0Â±1% by weight, and (ii) the content of xylene-soluble component contained in the propylene-based resin is not more than 20% by weight at 20Â° C., and (2-2) S[2/6] is a slope of a primary straight line, which straight line is obtained by a process consisting of the steps of: (i) plotting the elongation at break EB(%) on the ordinate, and the content (Pa; part by weight) of the olefin-based copolymer contained in the resin composition on the abscissa, respectively, to obtain a curve, (ii) deriving a quintet multiple regression from the above-mentioned curve to obtaining a multiple regression formula, wherein (a) the multiple regression formula has at least seven data of Pa values (Pa=0.00, 0.20, 0.30, 0.40, 0.50, 0.60 and 0.70), provided that a total weight of the olefin-based copolymer and the polypropylene-based resin is 1 part by weight, and (b) when the multiple regression formula has more than eight data of Pa values, all Pa values are plotted at an interval of 0.10 or less, and (iii) approximating a multiple-regression curve of the above-mentioned multiple regression formula, according to a least square method, in a Pa region of 0.20 to 0.60 to obtain the primary straight line.