Vinylcyclopropane of general formulae I

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in which X, Y in each case are O or NH, wherein X and Y cannot have the same meaning, R.sup.1 is a linear or branched C.sub.1-C.sub.8-alkyl radical, which can be interrupted by O, S, an ester group or a urethane group, R.sup.2 is a linear or branched C.sub.2-C.sub.10-alkylene radical, which can be interrupted by O, S, an ester group or a urethane group, R.sup.3 is a hydrocarbon radical with 1 to 20 carbon atoms, which additionally can contain one or more N, O or S atoms, and n is 1, 2, 3 or 4, preferably 1 or 2. The vinylcyclopropanes are characterized by a low shrinkage and a high reactivity on radical polymerization and are suitable in particular for the preparation of dental materials.

A polymerizable compound has a practical low melting point, excellent solubility in a general-purpose solvent, and can produce an optical film at low cost, exhibits low reflected luminance, and achieves uniform conversion of polarized light over a wide wavelength band, an optically anisotropic article.

The present teachings show that it is possible to polymerize 1,1-disubstituted alkene compounds in an emulsion (for example using a water based carrier liquid), despite the possible reactions between the monomer and water. Polymerization of 1,1-disubstituted alkene compounds in an emulsion provides opportunities to better control the polymerization compared with bulk polymerization. The emulsion polymerization techniques can be employed for preparing homopolymers, copolymers (e.g., random copolymers), and block copolymers.

A polymerizable compound has a practical low melting point, excellent solubility in a general-purpose solvent, and can produce an optical film at low cost, exhibits low reflected luminance, and achieves uniform conversion of polarized light over a wide wavelength band, an optically anisotropic article. A carbonyl compound is useful as a raw material for producing the polymerizable compound. (In the formula (I), Y.sup.1 to Y.sup.8 represent C(O)O, G.sup.1 and G.sup.2 represent a C.sub.1-20 divalent linear aliphatic group, Z.sup.1 and Z.sup.2 represent a C.sub.2-10 alkenyl group that is unsubstituted, or substituted with a halogen atom, A.sup.x represents a C.sub.2-30 organic group with at least one aromatic ring, A.sup.y represents a hydrogen atom or C.sub.1-20 alkyl group, A.sup.1 represents a trivalent aromatic group, A.sup.2 and A.sup.3 represent a C.sub.3-30 divalent alicyclic hydrocarbon group, A.sup.4 and A.sup.5 represent a C.sub.6-30 divalent aromatic group or the like, and Q.sup.1 represents a hydrogen atom.) ##STR00001##

This invention provides the following active energy ray-curable coating composition: an active energy ray-curable coating composition comprising (A) a polymerizable unsaturated group(s)-containing acrylic resin having a weight average molecular weight in the range of 5,000 to 30,000, (B) a urethane (meth)acrylate having a weight average molecular weight in the range of 1,000 or more but less than 5,000 and containing an average of two to four polymerizable unsaturated groups per molecule, (C) a polymerizable unsaturated compound having a weight average molecular weight in the range of 200 or more but less than 1,000 and containing an average of two to nine polymerizable unsaturated groups per molecule, and (D) a photopolymerization initiator, the molecular weight between crosslinks of a cured coating film obtained by applying the active energy ray-curable coating composition being in the range of 300 to 900 g/mol.

A polymerizable system includes a curable composition and one or more encapsulated initiator particles. The curable composition can include one or more 1,1-disubstituted alkene compounds and the encapsulated initiator particles can include one or more polymerization initiators encapsulated by a cured composition. The cured composition includes one or more 1,1-disubstituted alkene compounds.

An active energy ray curable composition is provided. The active energy ray curable composition includes a polymerizable monomer (A) and a polymerization initiator (B). The polymerization initiator (B) includes a skin-sensitizing polymerization initiator (B1) in an amount less than 1.0% by mass but not less than 0.1% by mass of the active energy ray curable composition, and 99.0% by mass or more of the active energy ray curable composition consists of non-skin-sensitizing constituents.

An active energy ray curable composition is provided. The active energy ray curable composition includes a polymerizable monomer (A) and a polymerization initiator (B). The polymerization initiator (B) includes a skin-sensitizing polymerization initiator (B1) in an amount less than 1.0% by mass but not less than 0.1% by mass of the active energy ray curable composition, and 99.0% by mass or more of the active energy ray curable composition consists of non-skin-sensitizing constituents.

A curing agent composition is capable of curing a base resin containing a 2-methylene-1,3-dicarbonyl compound. The curing agent composition contains a specific 2-methylene-1,3-dicarbonyl compound and an initiator. A two-part mixing adhesive contains the curing agent composition and a base resin containing another specific 2-methylene-1,3-dicarbonyl compound.

A curing agent composition is capable of curing a base resin containing a 2-methylene-1,3-dicarbonyl compound. The curing agent composition contains a specific 2-methylene-1,3-dicarbonyl compound and an initiator. A two-part mixing adhesive contains the curing agent composition and a base resin containing another specific 2-methylene-1,3-dicarbonyl compound.