The present invention provides an optical composition from which an optical article having reduced poor appearance such as cloudiness and optical strain during lens base material production can be obtained, and when a photochromic compound is added, a photochromic cured body having excellent photochromism and mechanical strength can also be formed, and a polyrotaxane used therefor. The polyrotaxane has a composite molecular structure formed of an axle molecule and a plurality of cyclic molecules clathrating the axle molecule, satisfying at least one of (X) and (Y). (X): A side chain having a secondary or tertiary hydroxyl group is introduced into at least part of the cyclic molecule of the polyrotaxane. (Y): A side chain having a group represented by -A (A is an organic group, and contains at least one hydroxyl group) is introduced into at least part of the cyclic molecule of the polyrotaxane, and a pKa of the hydroxyl group of the compound represented by H-A is 6 or more and less than 14.

The present invention relates to compounds having one of the following formulae (I) and (II):

##STR(I)##

##STR(II)##

and also to the uses thereof.

A crosslinking agent composition for water-compatible resins which comprises a hydrophobic crosslinking agent, a water-soluble organic compound, one or more oily media selected from among hydrocarbon-based solvents and ketone-based solvents having a solubility parameter of 9.0 (cal/cm.sup.−3).sup.1/2 or less, and an aqueous medium. The crosslinking agent composition can improve the storage stability of a water-compatible resin composition. The water-compatible resin composition which contains this crosslinking agent composition can give cured objects satisfactory in terms of water resistance and solvent resistance and is suitable also for use in wet-on-wet coating.

In a structural polyurethane adhesive, a polyisocyanate component contains a first prepolymer component containing a first isocyanate group-terminated urethane prepolymer which is a reaction product of a first material polyisocyanate consisting of an aromatic polyisocyanate, and a first material polyol containing a macropolyol; and a second prepolymer component containing a second isocyanate group-terminated urethane prepolymer which is a reaction product of a second material polyisocyanate consisting of an araliphatic polyisocyanate and/or an aliphatic polyisocyanate, and a second material polyol containing a polyether polyol having a number average molecular weight of 160 or more and 4800 or less. A ratio of the second prepolymer component with respect to the total amount of the first prepolymer component and the second prepolymer component is 2% by mass or more and 35% by mass or less.

A resin composition useful for additive manufacturing is provided, which resin composition may exhibit improved shelf life through inhibition of crystallization. Such resin composition may include a crystallization inhibitor as taught herein, and/or a prepolymer produced by reaction of an isocyanate with multiple isomers and comprising a lower percentage of the structurally symmetric isomer. Methods of forming a three-dimensional object using such resin composition are also provided.

There are provided a carbodiimide compound excellent in storage stability, and performance as a crosslinking agent, and a method for producing the same, and a resin composition excellent in the film forming properties and solvent resistance of a coating made at low temperature. A polycarbodiimide compound derived from an aliphatic diisocyanate compound having at least one primary isocyanate group, the polycarbodiimide compound having a structure in which all ends are capped with an organic compound having a functional group that reacts with an isocyanate group, carbodiimide group concentration A (%) and weight average molecular weight Mw satisfying the following formula (1), and a resin composition comprising the carbodiimide compound and an aqueous resin having a predetermined acid value at a predetermined ratio.
(A/Mw)×1000≥0.55  (1).

An adhesive includes: a urethane prepolymer (A) obtained by reacting a polyol (a) with a polyisocyanate (b) under such conditions that the molar ratio of NCO/OH is 0.5-0.9 and having a molecular-weight dispersion degree [(weight-average molecular weight (Mw))/(number-average molecular weight (Mn)); hereinafter referred to also as Mw/Mn] of 4-12; a polyfunctional polyol (B), and an isocyanate curing agent (C).

A pressure sensitive adhesive composition includes a polyurethane polymer that includes the reaction product of a polyisocyanate component and a polyol component. The polyol component has a total solubility parameter ranging from 10 to 14 (cal/cm.sup.3).sup.1/2.

A multicomponent adhesive composition comprises a composition A and a composition B. Composition A comprises at least one silyl polymer comprising at least one hydrolyzable alkoxysilane group and at least one tackifying resin. Composition B comprises at least one catalyst and at least one compound C chosen from a compound C1 with a number-average molecular mass ranging from 300 g/mol to 500 000 g/mol; and a compound C2 with a vapor pressure at 20° C. of greater than or equal to 0.08 kPa; and mixtures thereof. The composition A:composition B mass ratio ranges from 99.98:0.02 to 60:40. The total content of catalyst ranges from 0.01% to 10% relative to the total weight of said adhesive composition.

A resin composition useful for additive manufacturing is provided, which resin composition may exhibit improved shelf life through inhibition of crystallization. Such resin composition may include a crystallization inhibitor as taught herein, and/or a prepolymer produced by reaction of an isocyanate with multiple isomers and comprising a lower percentage of the structurally symmetric isomer. Methods of forming a three-dimensional object using such resin composition are also provided.