A photochromic polyurethane laminate wherein the photochromic polyurethane layer of the laminate has been crosslinked with an isocyanate-active prepolymer using a crosslinking agent. The crosslinking agent is formulated to have at least three functional groups that are reactive with functional groups of the polyurethane or of the isocyanate-active prepolymer. A method of making the photochromic polyurethane laminate includes steps of causing the crosslinking.

A photochromic polyurethane laminate wherein the photochromic polyurethane layer of the laminate has been crosslinked with an isocyanate-active prepolymer using a crosslinking agent. The crosslinking agent is formulated to have at least three functional groups that are reactive with functional groups of the polyurethane or of the isocyanate-active prepolymer. A method of making the photochromic polyurethane laminate includes steps of causing the crosslinking.

A process for making an oxymethylene polymer comprising polymerizing at least one compound capable of forming —CH.sub.2O— repeat units (monomer) in the presence of at least one ester of the general formula I (ester): R.sup.1—CO—O—R.sup.2 (I) wherein R.sup.1 can be hydrogen, wherein R.sup.1 and R.sup.2 are independently of each other linear or branched C.sub.1 to C.sub.10 alkyl C.sub.5 to C.sub.7 cycloalkyl —[R.sup.3-0-].sub.nR.sup.4 wherein R.sup.3 is a linear or branched C.sub.2 to C.sub.5 alkylen and R.sup.4 is a linear of branched C.sub.1 to C.sub.5 alkyl and n is an integer of from 1 to 5. and in the presence of at least one Lewis acid.

A process for making an oxymethylene polymer comprising polymerizing at least one compound capable of forming —CH.sub.2O— repeat units (monomer) in the presence of at least one ester of the general formula I (ester): R.sup.1—CO—O—R.sup.2 (I) wherein R.sup.1 can be hydrogen, wherein R.sup.1 and R.sup.2 are independently of each other linear or branched C.sub.1 to C.sub.10 alkyl C.sub.5 to C.sub.7 cycloalkyl —[R.sup.3-0-].sub.nR.sup.4 wherein R.sup.3 is a linear or branched C.sub.2 to C.sub.5 alkylen and R.sup.4 is a linear of branched C.sub.1 to C.sub.5 alkyl and n is an integer of from 1 to 5. and in the presence of at least one Lewis acid.

A photochromic polyurethane laminate wherein the photochromic polyurethane layer of the laminate has been crosslinked with an isocyanate-active prepolymer using a crosslinking agent. The crosslinking agent is formulated to have at least three functional groups that are reactive with functional groups of the polyurethane or of the isocyanate-active prepolymer. A method of making the photochromic polyurethane laminate includes steps of causing the crosslinking.

A photochromic polyurethane laminate wherein the photochromic polyurethane layer of the laminate has been crosslinked with an isocyanate-active prepolymer using a crosslinking agent. The crosslinking agent is formulated to have at least three functional groups that are reactive with functional groups of the polyurethane or of the isocyanate-active prepolymer. A method of making the photochromic polyurethane laminate includes steps of causing the crosslinking.

A photochromic polyurethane laminate wherein the photochromic polyurethane layer of the laminate has been crosslinked with an isocyanate-active prepolymer using a crosslinking agent. The crosslinking agent is formulated to have at least three functional groups that are reactive with functional groups of the polyurethane or of the isocyanate-active prepolymer. A method of making the photochromic polyurethane laminate includes steps of causing the crosslinking.

Provided is a method of manufacturing a polyacetal copolymer including: a step of copolymerizing 100 parts by mass of trioxane (A), 0.05 to 5 parts by mass of a cyclic acetal compound (B), and 0.001 to 1 parts by mass of an aliphatic glycidyl ether compound (C) having a chlorine content of 1 to 500 mass ppm, in the presence of a linear formal compound (D) as a molecular weight regulator, in which in the step, when a total mass (g) of the trioxane (A), the compound (B), and the compound (C) is “a”, a molar number of the linear formal compound (D) is “b”, and total molar numbers of water and methanol contained in the trioxane (A), the compound (B), and the compound (C) are respectively “c” and “d”, setting is performed to satisfy (b+c+d)/a=1.5 to 7 μmol/g.

A photochromic polyurethane laminate wherein the photochromic polyurethane layer of the laminate has been crosslinked with an isocyanate-active prepolymer using a crosslinking agent. The crosslinking agent is formulated to have at least three functional groups that are reactive with functional groups of the polyurethane or of the isocyanate-active prepolymer. A method of making the photochromic polyurethane laminate includes steps of causing the crosslinking.

A photochromic polyurethane laminate wherein the photochromic polyurethane layer of the laminate has been crosslinked with an isocyanate-active prepolymer using a crosslinking agent. The crosslinking agent is formulated to have at least three functional groups that are reactive with functional groups of the polyurethane or of the isocyanate-active prepolymer. A method of making the photochromic polyurethane laminate includes steps of causing the crosslinking.