Ube Industries, Inc.

Komatsulite Mfg. Co., Ltd.

Allied Corporation

Masao Nishiyama

Hiroyuki Teraoka

Junji Kitamura

Masao Ogasa

Keiichiro Katada

Yoshiteru Akimoto

Kaoru Ohtsuki

Yasuo Hirano

An image taking lens LA comprises an aperture S, a first lens Land a second lens Lwhich are arranged in this order from an object side to an image side. The first lens Lhas a positive power and a meniscus shape with a convex surface facing an object; and the second lens Lhas a positive power with a convex surface facing an image. The first lens Land the second lens Lsatisfy the following formulae (1) and (2):0.30&#x3c;1/2&#x3c;0.65&#x2003;&#x2003;(1)0.30&#x3c;3/&#x3c;0.50&#x2003;&#x2003;(2)This image taking lens formed of the two lenses is small in size and has a high optical performance, in which the entire image taking lens has a short focal length.

Image taking lens

An image taking lenscomprises a stop, a first lenshaving a positive power and biconvex configuration, a second lenshaving a negative power and having a meniscus configuration in which a concave surface is disposed to face an object, a third lenshaving a positive power and a meniscus configuration in which a convex surface is disposed to face an image, and a fourth lenshaving a negative power and a meniscus configuration in which a convex surface is disposed to face the object, which are arranged in this order from the object. The lensestosatisfy the following formulae (1) to (4),3.00&#x3c;1/1&#x3c;10.00&#x2003;&#x2003;(1)&#x2212;20.0&#x3c;2/3&#x3c;&#x2212;10.0&#x2003;&#x2003;(2)50.0&#x3c;&#x3bd;1&#x3c;60.0&#x2003;&#x2003;(3)20.0&#x3c;&#x3bd;2&#x3c;30.0&#x2003;&#x2003;(4)hereupon,

A process for producing a lactam copolymer, which comprises copolymerizing an omega-lactam and a diene polymer having an amino or imino group at molecular ends by the action of an alkaline catalyst and a polyfunctional co-catalyst, the proportions of the components satisfying the following equations (I) and (II)

Copolymerization of lactam with diene polymer having amino or imino end

A molded article is formed by a reaction injection molding method wherein a starting material, e.g., an .omega.-lactam, is injected into a mold, the inner pressure of which is maintained at 0.5 to 20 kg/cm.sup.2 .multidot.G with an inert gas; and the inner pressure of the mold is maintained at a level higher than the pressure increased by injection of the starting material until the polymerization molding of the starting material is completed.

Reaction injection molding method

A process for preparing polyamides having improved impact strength and elongation comprising polymerizing an -lactam in the presence of (1) an alkali catalyst and (2) the reaction product of (a) a polyfunctional co-catalyst such as a polyisocyanate and (b) a polyoxyalkalene amine. The polyamides of the present invention are particularly useful for making strong tough molded or cast articles.

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Takatsuki, Japan

Masao Nishiyama