Nisshin Spinning Co., Ltd.

Nisshinbo Industries, Inc.

Taisei Corporation

Japanese National Railways

Nisshin Boseki Kabushiki Kaisha

Kabushiki Kaisha Toshiba

Godo Kaisha IP Bridge 1

Yoshihiko Ogawa

Atsushi Matsumoto

Toshio Suzuki

Tatsuya Hongu

Takashi Iwai

Yoshihiko Sato

Takeshi Itoh

Fujio Ohishi

Takehiko Tokoro

Toshio Hiramatsu

Toshio Hatsuzaki

Hideo Senga

A mixture consisting essentially of (1) an organic polyisocyanate compound and/or a prepolymer having terminal isocyanate residues, which is derived from the reaction of an organic polyisocyanate with a polyhydroxyl compound, and (2) 2-pyrrolidone, is injected for grouting into water-leaking cracks or openings of concrete structures such as water tanks, subway constructions and tunnels. The injected mixture diffuses into the cracks or openings and is cured in short time by reacting with water at the leaking sites. The resultant polyurethane foam securely seals the water leaking sites.

Method of sealing water leakage in concrete structures

A vibration isolator composed of a low foam urethane elastomer having urethane bonds and a bulk density of 0.4-0.75 g/cm.sup.3 which is prepared from the starting foamable liquid of urethane elastomer composed substantially of

Vibration isolator

A resilient coat for a direct connection-type tie (Danchoku tie) which is composed of a concrete tie body and a microcellular polyurethane elastomer coating layer which adheres to and coats the lower portion of the tie body to form an integral body therewith, and said microcellular polyurethane elastomer having urethane bonds and a bulk density of 0.4-0.75 g/cm.sup.3 and being prepared from the starting foamable liquid of urethane elastomer composed substantially of (a) a polyether polyol having an average number of functional groups of 2.5-4.5 and a number average molecular weight of 2000-8500, (b) a vinyl monomer-grafted polyol having an average number of functional groups of 2.5-4.0, and the graft ratio of 4-20% by weight, (c) a liquid polybutadiene polyol having hydroxyl terminal group(s), an average number of functional groups of 2.0-3.0 and a number average molecular weight of 2000-7000, (d) an organic polyisocyanate, (e) a chain extender, (f) a blowing agent, and (g) a urethanation catalyst, at such ratios that the NCO index is within the range of 90-110, and the concentration of the chain extender, based on the total amount of the five components of (a), (b), (c), (d) and (e), being 0.3.times.10.sup.-3 to 1.5.times.10.sup.-3 mol/g.

Resilient coat for tie of direct-connection type track

A vibration isolator consisting essentially of a microcellular polyurethane elastomer having a bulk density of 0.3-0.9 g/cm.sup.3, said polyurethane elastomer obtained by reacting in the presence of water as the blowing agent (a) an organic polyisocyanate, (b) a polyether polyol having an average number of functional groups of 2.5-3.5 and a number average molecular weight of 4500-8500, and (c) a chain extender, in such a ratio that the NCO index is 90-110 and the concentration of the chain extender, based on the total weight of the three components (a), (b) and (c), is (0.4-2.0).times.10.sup.-3 equivalent/gram.

Microcellular polyurethane vibration isolator

Growing community of inventors

Tokyo, Japan

Yoshihiko Ogawa