The present invention is in the field of polymers comprising XRF identifiable tracers allowing information to be encoded by the polymers, and in particular polymers for conservation, restoration and retouching in artworks, electronics, coatings, plastics etc.

Provided is an optical article having a substrate, a primer layer generated by curing a polymerizable composition for forming the primer layer, and a photochromic layer generated by curing a (meth)acrylate-based polymerizable composition containing a photochromic compound in this order, in which the polymerizable composition for forming the primer layer contains a component A: polyisocyanate and a component B: hydroxy group-containing (meth)acrylate.

Low-viscosity urethane methacrylate compounds can be used in a reactive resin component to improve the thixotropic properties of the reactive resin component and/or the afterflow behavior of a reactive resin system containing the reactive resin component.

Low-viscosity urethane methacrylate compounds can be used in a reactive resin component to improve the thixotropic properties of the reactive resin component and/or the afterflow behavior of a reactive resin system containing the reactive resin component.

Provided is a collection of polymer beads, wherein the volume distribution expressed as a function of bead diameter comprises (A1) a first peak having a maximum of PM1 at diameter PD1 and having full width at half maximum of 75 μm or less, (A2) a second peak having a maximum of PM2 at diameter PD2 and having full width at half maximum of 75 μm or less; and (B1) a valley having a minimum value of VM1 at a diameter between PD1 and PD2, wherein VM1 is less than 0.25*PM1 and VM1 is also less than 0.25*PM2.
wherein the polymer beads comprise polymerized units of one or more monofunctional vinyl monomer and one or more multifunctional vinyl monomer.

Provided is a collection of polymer beads, wherein the volume distribution expressed as a function of bead diameter comprises (A1) a first peak having a maximum of PM1 at diameter PD1 and having full width at half maximum of 75 μm or less, (A2) a second peak having a maximum of PM2 at diameter PD2 and having full width at half maximum of 75 μm or less; and (B1) a valley having a minimum value of VM1 at a diameter between PD1 and PD2, wherein VM1 is less than 0.25*PM1 and VM1 is also less than 0.25*PM2.
wherein the polymer beads comprise polymerized units of one or more monofunctional vinyl monomer and one or more multifunctional vinyl monomer.

A photosensitive resin composition contains a compound A which has a heterocyclic structure having at least one atom of an oxygen atom, a nitrogen atom, or a sulfur atom in a ring structure, and has at least one functional group selected from the group consisting of —SH, —OH, —COOH, —NH.sub.2, and —CONH.sub.2, an alkali-soluble binder polymer, an ethylenically unsaturated compound, and a photopolymerization initiator.

An active energy ray-curable inkjet ink containing polymerizable compounds and a polymerization initiator, wherein the polymerizable compounds include at least 5 types of polyfunctional polymerizable compounds having molecular weights within a range from 150 to 500, and include substantially no monofunctional polymerizable compounds.

It is an object of the present invention to provide an unsaturated group-containing ester compound which can be used as a raw material of a curable composition using transesterification reaction and which is inexpensive and has a good curability, and a polymer, a thermosetting resin composition, and a curable composition which containing the unsaturated group-containing ester compound, respectively. An unsaturated group-containing ester compound having a chemical structure represented by the following general formula (1): ##STR00001## n.sub.1: 1 to 10 (in the formula, R.sub.1, R.sub.2, and R.sub.3 are the same or different and each is a hydrogen, an alkyl group, a carboxyl group, an alkyl ester group or a structure represented by R.sub.4-[COOR.sub.5]n.sub.1; R.sub.4 is an aliphatic, an alicyclic or an aromatic alkylene group with a number of atoms of 50 or less in the main chain, which may have one or more functional groups selected from the group consisting of an ester group, an ether group, an amide group, and a urethane and may have a side chain; R.sub.5 is an alkyl group having 50 or less carbon atoms; and in the compound represented by the general formula (1), the R.sub.4-[COOR.sub.5] group may be a lactone structure represented by the following general formula (1-1). ##STR00002## (R.sub.x is a hydrocarbon group having 2 to 10 carbon atoms which may have a branched chain.

It is an object of the present invention to provide an unsaturated group-containing ester compound which can be used as a raw material of a curable composition using transesterification reaction and which is inexpensive and has a good curability, and a polymer, a thermosetting resin composition, and a curable composition which containing the unsaturated group-containing ester compound, respectively. An unsaturated group-containing ester compound having a chemical structure represented by the following general formula (1): ##STR00001## n.sub.1: 1 to 10 (in the formula, R.sub.1, R.sub.2, and R.sub.3 are the same or different and each is a hydrogen, an alkyl group, a carboxyl group, an alkyl ester group or a structure represented by R.sub.4-[COOR.sub.5]n.sub.1; R.sub.4 is an aliphatic, an alicyclic or an aromatic alkylene group with a number of atoms of 50 or less in the main chain, which may have one or more functional groups selected from the group consisting of an ester group, an ether group, an amide group, and a urethane and may have a side chain; R.sub.5 is an alkyl group having 50 or less carbon atoms; and in the compound represented by the general formula (1), the R.sub.4-[COOR.sub.5] group may be a lactone structure represented by the following general formula (1-1). ##STR00002## (R.sub.x is a hydrocarbon group having 2 to 10 carbon atoms which may have a branched chain.