TECHNOLOGY FOCUS - POLYMERS - Preferred Composition: The resin composition contains radical polymerizable resin and radical polymerizable diluent. The resin or the diluent has carboxyl group. The radical polymerizable resin contains polymerizable unsaturated carboxylic acid and is chosen from unsaturated polyester type resin and vinyl ester resin. The polymerizable resin is of formula (a).Ra,Rb = H or alkyl group;Rc = H or methyl group;Rd = 1-3C alkyl group;i = 0 or 1;j = 0-4; andk = 0, 1 or more.The weight ratio of the resin having k of 0 or 1 and the resin having k of 4 or more is 95/5-5/95. The composition contains 5-60 wt.% of aromatic vinyl compound as the diluent. The composition further contains low shrinkage component chosen from saturated polyester type resin, acrylic type resin and multi-layer resin particle. Alternately, the composition contains vinyl ester resin having multiple alpha and beta ethylenically unsaturated bonds or unsaturated polyester type resin, aromatic vinyl compound, methacrylic acid and carbon powder as electroconductive agent. The electroconductive agent and the resin are contained in the weight ratio of 55/45-95/5, preferably 65/35-95/5.Preferred Properties: The double bond equivalent of the radical polymerizable resin is 200-1000. The cured material of the resin composition has glass transition temperature of 120degreesC or more. The weight retention of the electroconductive plate after immersing in 90degreesC warm water for 2000 hours is 98% or more with respect to the value before immersion. The bending strength retention of the electroconductive plate after immersing in 90degreesC warm water for 2000 hours is 95% or more with respect to the value before immersion.Preferred Process: The electroconductive agent and the radical polymerizable heat curing type resin are mixed with a pressurization kneader and the obtained mixture is molded by resin molding method to obtain electroconductive plate.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Diluent: The aromatic vinyl compound is of formula (1).R1,R2 = H or 1-3C alkyl group;R3 = 2-4C alkylene group;R4 = Rc;R5 = 1-3C alkyl group;n = 0-5, preferably 1-5;m = 0 or 1, preferably 1; ands = 0-4. EXAMPLE - EPOTHOTO YD128 (bisphenol A epoxy resin with epoxy equivalent of 187 g/equivalent) (in g) (374), methacrylic acid (172), triphenyl phosphine (0.2) and hydroquinone (0.1) were reacted at 120degreesC for 8 hours to obtain vinyl ester resin with acid value of 1.8 mgKOH/g. The obtained resin was diluted with styrene (364) and vinyl ester resin composition was obtained. The obtained resin composition, polymer microparticle, low shrinkage providing agent and radical polymerizable diluent were mixed to obtain resin composition. The obtained composition, artificial graphite powder used as electroconductive agent and polymerization initiator were mixed and hardened to obtain a flat electroconductive plate. The flat plate had bending strength of 38.9 MPa measured according to JISK7203, flexibility of 0.4%, heat conductivity of 36 W/m.k, gas permeability of less than 10-10 cm2/second.atmosphere, favorable heat stability, bending strength retention of less than 99% and weight retention of less than 99%.