Photochromic molding compositions and articles produced therefrom

The polyamide molding composition as claimed in any of the preceding claims, wherein the further polymer is a polyamide based on cycloaliphatic diamines and aliphatic dicarboxylic acids having from 6 to 40 carbon atoms, the cycloaliphatic diamine preferably being MACM and/or PACM, and the entire polyamide particularly preferably being MACM36 and/or PACM36, and/or wherein the further polymer is a block copolymer having soft segments, where the glass transition temperature of the soft segments is preferably below 40° C., preferably below 25° C.

The polyamide molding composition as claimed in any of the preceding claims, wherein the proportion by weight present of the transparent homopolyamide and/or copolyamide is from 70 to 99% by weight, particularly preferably from 80 to 98% by weight.

The polyamide molding composition as claimed in any of the preceding claims, wherein the proportion by weight present of the further polymer is from 1 to 30% by weight, particularly preferably from 2 to 20% by weight.

The polyamide molding composition as claimed in any of the preceding claims, wherein the transparent homopolyamide and/or copolyamide is a polyamide based on cycloaliphatic diamines and on aliphatic dicarboxylic acids having from 6 to 36 carbon atoms or is a mixture of such homopolyamides and/or copolyamides.

The polyamide molding composition as claimed in any of the preceding claims, wherein the transparent homopolyamide and/or copolyamide is a polyamide based on aromatic dicarboxylic acids having from 8 to 18 carbon atoms, or is a mixture of such homopolyamides and/or copolyamides, preferably based on lactams and/or aminocarboxylic acids, the aromatic dicarboxylic acids preferably being TPA and/or IPA.

The polyamide molding composition as claimed in any of the preceding claims, wherein the transparent homopolyamide and/or copolyamide is a polyamide based on at least one dicarboxylic acid and on at least one diamine having an aromatic ring, preferably based on MXD, where the dicarboxylic acid can be aromatic and/or aliphatic, the material preferably being 6I/MXDI.

The polyamide molding composition as claimed in any of the preceding claims, wherein the solution viscosity (ηrel) of the transparent homopolyamide and/or copolyamide is from 1.3 to 2.0, particularly preferably from 1.40 to 1.85, and/or its glass transition temperature Tg is above 90° C., preferably above 110° C., particularly preferably above 130° C.

The polyamide molding composition as claimed in any of the preceding claims, wherein the photochromic dye is a dye which is reversibly excitable with UV or short-wave VIS, preferably being a dye based on spirooxazines.

The polyamide molding composition as claimed in any of the preceding claims, wherein the additives are stabilizers, such as UV stabilizers, heat stabilizers, or free-radical scavengers, and/or are processing aids, plasticizers, or further polymers, and/or are functional additives, preferably for influencing optical properties, e.g. particularly refractive index, or are a combination or mixture thereof.

The polyamide molding composition as claimed in any of the preceding claims, which comprises polyamide-12, preferably low-viscosity polyamide-12.

The polyamide molding composition as claimed in any of the preceding claims, which comprises a polyamide oligomer, particularly preferably a polyamide-12 oligomer.

The polyamide molding composition as claimed in any of the preceding claims, wherein the ratio of the solution viscosities (ηrel) of the transparent homopolyamide and/or copolyamide and of the further polymer whose glass transition temperature is below 80° C. is smaller than 1.2, particularly smaller than 1.1.

A transparent, preferably haze-free article having at least one region or one layer composed of a polyamide molding composition as claimed in any of the preceding claims.

An article as claimed in the preceding claim for high-specification optical applications, whose transmittance is more than 70%, preferably more than 80%, in the wavelength range from 500 to 700 nm, and/or whose haze is less than 5, preferably less than 3, for a thickness of the layer composed of the polyamide molding composition of 2 mm.