Abstract: The present invention provides a sealing structure employing a piston ring structural body of a type wherein an outer ring continuously formed of a resinous material is pressed radially outwards by a metal coil expander via a metal inner ring provided with an abutment. The piston ring structural body has a construction wherein the outer ring continuously formed of polyimide is pressed radially outwards by the coil expander via the steel inner ring provided with the abutment. A sliding face of the outer ring, which slides on a cylinder wall, is divided by a groove into upper and lower sliding faces, whose respective upper edge portions are provided with chamfers.

Abstract: An absorbing agent has a diffusing absorbency under pressure of not less than 25 g/g when 60 minutes elapsed after absorption is started, and a water-soluble content is above 0 percent by weight and not more than 7 percent by weight. The absorbing agent is prepared by surface-crosslinking a precursor of the absorbing agent obtained by performing an aqueous solution polymerization of a hydrophilic unsaturated monomer having not less than 50 mole percent neutralized acrylic acid as a main component using a specific crosslinking agent having a main component composed of an ester compound of a specific polyhydroxy alcohol and an unsatuated carboxylic acid, and a high-boiling component having at least two alcohol structures in a molecule as a specific ratio.

Abstract: An absorbing agent has a diffusing absorbency under pressure of not less than 25 g/g when 60 minutes elapsed after absorption is started, and a water-soluble content is above 0 percent by weight and not more than 7 percent by weight. The absorbing agent is prepared by surface-crosslinking a precursor of the absorbing agent obtained by performing an aqueous solution polymerization of a hydrophilic unsaturated monomer having not less than 50 mole percent neutralized acrylic acid as a main component using a specific crosslinking agent having a main component composed of an ester compound of a specific polyhydroxy alcohol and an unsatuated carboxylic acid, and a high-boiling component having at least two alcohol structures in a molecule as a specific ratio.

Abstract: A method for the production of an absorbent resin having a very small residual monomer content either by adding to an absorbent resin powder a substance capable of reacting with the residual monomer in the absorbent resin powder thereby forming an absorbent resin composition having a water content in the range of 10 to 70% by weight and heat-treating the absorbent resin composition at a temperature in the range of 100.degree. to 200 .degree. C. while retaining the water content of the absorbent resin or by adding to an absorbent resin powder a substance capable of reacting with the residual monomer in the absorbent resin powder thereby forming an absorbent resin composition having a water content in the range of 25 to 55% by weight, heat-treating the absorbent resin composition at a temperature in the range of 120.degree. to 200 .degree. C.

Abstract: An absorbing agent has a diffusing absorbency under pressure of not less than 25 g/g when 60 minutes elapsed after absorption is started, and a water-soluble content is above 0 percent by weight and not more than 7 percent by weight. The absorbing agent is prepared by surface-crosslinking a precursor of the absorbing agent obtained by performing an aqueous solution polymerization of a hydrophilic unsaturated monomer having not less than 50 mole percent neutralized acrylic acid as a main component using a specific crosslinking agent having a main component composed of an ester compound of a specific polyhydroxy alcohol and an unsaturated carboxylic acid, and a high-boiling component having at least two alcohol structures in a molecule as a specific ratio.

Abstract: A piston, which reciprocates in a cylinder bore of an engine, is supplied with lubricating oil. The piston includes pin bosses provided under a piston head, a symmetrical pair of skirts, and side walls connecting the pin bosses and the skirts. The side walls have openings, which communicate the outer side of the walls with the inner side of the walls under the middle section of the head. A recess is defined in the lower surface of the head to receive a spray of lubricating oil. The width of the recess is wider than the width of each skirt at its basal portion. This causes the oil supplied to the lower surface of the head during movement of the piston to be injected against the recess and thus be diffused. As a result, oil passes by the basal section of the skirts and permeates into the space defined by the cylinder bore and the skirts.

Abstract: A method for the production of a water-absorbent agent comprises mixing an absorbent resin containing a carboxyl group with an additive soluble in the aqueous solution of at least one member selected from the group consisting of inorganic acids, organic acids, and polyamino acids and a cross-linking agent capable of reacting with the carboxyl group. A water-absorbent agent obtained by adding from 0.005 to 8 parts by weight of an epoxy compound to 100 parts by weight of a water-absorbent resin, exhibiting an absorption capacity without load of at least 45 (g/g), an absorption capacity under load of 20 g/cm.sup.2 of not less than 30 (ml/g) and having a residue amount of an epoxy compound of not more than 2 ppm. A water-absorbent composition comprises a polyamino acid (salt) and a water-absorbent resin containing a carboxyl group.

Abstract: A process for preparing an absorbent resin includes the steps of: preparing a first crosslinking agent (A) including at least two polymerizable unsaturated bonds; preparing a second crosslinking agent (B) including at least two polymerizable unsaturated bonds and hydroxyl groups; preparing a crosslinking agent including (A) and (B) with a ratio of (A) to (B) ranging from 95/5 to 50/50; and polymerizing a hydrophilic unsaturated monomer having at least one carboxyl group using the crosslinking agent. The crosslinking agent includes a crosslinking agent which includes a main component at least 90 percent by weight, the main component being an ester having at least two polymerizable unsaturated bonds, wherein the ester is composed of a polyhydroxy alcohol (C) having not more than six carbon atoms and at least three hydroxy groups, and an unsaturated carboxylic acid (D); and a molecular weight ratio of the main component to a standard compound (E) is in the range of from 0.7/1 to less than 1.

Abstract: A method for the production of an absorbent resin, which method comprises mixing 100 parts by weight of (A) a hydrated gel of absorbent resin which is resulted from aqueous solution polymerization having a polymerization ratio in the range of from 60 to 99%, an average particle diameter in the range of from 0.1 to 200 mm, a water content in the range of from 30 to 90% by weight, and a temperature in the range of from 40.degree. to 110.degree. C., with from 1 to 50 parts by weight of (B) a substantially dry fine absorbent resin powder having an average particle diameter smaller than the average particle diameter assumed by said hydrated gel of absorbent resin (A) while in a dried state, then raising the polymerization ratio of said hydrated gel of absorbent resin (A) to a level higher than the polymerization ratio of said hydrated gel when being mixed.

Abstract: A method for the production of an absorbent resin retaining at a high level an absorption capacity without load, one of the basic physical properties of absorbent resin, and excelling in an absorption capacity under load is provided. The production is attained by mixing an absorbent resin as a base polymer possessing a carboxyl group with a first cross-linking agent possessing a solubility parameter (SP value) of not less than 12.5 (cal/cm.sup.3).sup.1/2 and exhibiting reactivity with the carboxyl group and a second cross-linking agent possessing a solubility parameter (SP value) of less than 12.5 (cal/cm.sup.3).sup.1/2 and exhibiting reactivity with the carboxyl group and then subjecting the resultant mixture to a heat treatment at a temperature not less than 160.degree. C.

Abstract: A method of adjusting the hardness of a metallic material includes the steps of induction-tempering both of tough and hard portions which have been given a hardness required for the hard portion to a hardness required for the tough portion, induction-hardening the hard portion alone to a hardness higher than that required for the hard portion, and induction-tempering the hard portion alone to a hardness required for the hard portion.

Abstract: The invention provides [I] a water-absorbing agent composed of a water-absorbing resin powder having the molecular chains near its surface being crosslinked, said powder being obtained by mixing 100 parts by weight of a powder of a carboxyl-containing water-absorbing resin selected from the group consisting of a hydrolyzate of a starch-acrylonitrile graft polymer, a partially neutralized product of a starch-acrylic acid graft polymer, a saponification product of a vinyl acetate-acrylic ester copolymer, a hydrolyzate of an acrylonitrile copolymer, a crosslinked product of a hydrolyzate of an acrylonitrile copolymer, a hydrolyzate of an acrylamide copolymer, a crosslinked product of a hydrolyzate of an acrylamide copolymer, a partially neutralized product of polyacrylic acid, and a crosslinked product of partially neutralized polyacrylic acid with 0.001 to 10 parts by weight of a polyhydric alcohol, 0.

Abstract: A control valve for an exhaust gas recirculation apparatus for leading part of the exhaust gas from an exhaust line to a suction line. This control valve comprises a throttling member provided in the passage for recirculating exhaust gas, and a valve body the opens and closes the passage of the throttling member. The hole provided in the base of the throttling member has an inside diameter smaller than the hole of the throttling portion. The end portion of the valve body has an outside diameter a little smaller than the inside diameter of the hole of the throttling member, and the length of this end portion in the axial direction is selected so as to allow at least its end to pass the base of the throttling member when the large diameter portion of the valve body is in contact with the base. The thickness of the base of the throttling member in the axial direction is sufficiently smaller than the inside diameter of the hole of the base.

Abstract: An exhaust gas recirculation control valve for preventing carbon and the like contained in the exhaust gas from attaching to the inner wall surface of exhaust gas paths, through which the exhaust gas from an engine of a motor car passes, thus decreasing the diameters of the paths with time. This exhaust gas recirculation control valve is provided in a passageway, through which the exhaust gas from the engine is recirculated into an intake air-fuel mixture, a path being of a frusto-conical shape in cross-section and having a progressively larger diameter toward an exhaust gas inlet is formed upstream of the minimum diameter portion, and the inner diameter of the smallest diameter end of said path being of the frusto-conical shape in cross-section in the vicinity of said minimum diameter portion is larger than the inner diameter of said minimum diameter portion. The path being of the frusto-conical shape in cross-section may be formed of a valve housing separately manufactured of a valve seat.

Abstract: An absorbent resin composition obtained by copolymerizing in an aqueous solution a mixture of 100 parts by weight of an acrylate salt monomer (B) composed of 0 to 50 mol % of acrylic acid and 50 to 100 mol % of an alkali metal acrylate and 0.001 to 5 part by weight of a crosslinkable monomer (C) having 2 to 4 groups selected from the group consisting of CH.sub.2 .dbd.CHCO--, CH.sub.2 .dbd.C(CH.sub.3)C0-- and CH.sub.2 .dbd.CH-CH.sub.