Photochromic molding compositions and articles produced therefrom

Abstract

A polyamide molding composition is described, comprising a proportion by weight of from 50 to 99% by weight of at least one transparent homopolyamide and/or copolyamide, a proportion by weight of from 1 to 50% by weight of at least one further polymer whose glass transition temperature is below 80° C., and also a proportion by weight of from 0.001 to 2.0% by weight of at least one photochromic dye. Further dyes and/or additives can optionally be present. The invention moreover encompasses articles manufactured therefrom, a particular example being photochromic ophthalmic lenses.

Description

Claims

1. A polyamide molding composition comprising a proportion by weight of from 50 to 99% by weight of at least one transparent homopolyamide and/or copolyamide;a proportion by weight of from 1 to 50% by weight of at least one further polymer whose glass transition temperature is below 80° C.;a proportion by weight of from 0.001 to 2.0% by weight of at least one photochromic dye;and also, optionally,further dyes and/or additives.

2. The polyamide molding composition as claimed in claim 1, wherein the glass transition temperature of the further polymer is below 40° C., preferably below 25° C.

3. The polyamide molding composition as claimed in claim 1 or 2, wherein the glass transition temperature of the further polymer is below 0° C., preferably in the range from (−60)-(−20)° C.

4. 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.

5. The polyamide molding composition as claimed in claim 4, wherein the further polymer is a polyamide block copolymer having soft segments, preferably is a polyamide-12 block copolymer, the soft segments preferably being polyether soft segments and/or polyester soft segments and/or polysiloxane soft segments and/or polyolefin soft segments and/or polyacrylate soft segments, preferred polyether segments being those based on the monomers ethylene oxide and/or propylene oxide and/or tetrahydrofuran.

6. The polyamide molding composition as claimed in any of the preceding claims, wherein the further polymer is a polymer selected from the following group: polyester having soft segments; TPU elastomers having soft segments; acrylate polymer; methacrylate polymer, particularly preferably having long pendent groups; polycarbonate copolymer; styrene copolymer, preferably based on acrylonitrile, butadiene, acrylic esters, methacrylic esters; polyolefin, particularly grafted; ethylene copolymers, particularly based on propene, butene, pentene, hexene, octene, decene, undecene, butadiene, styrene, acrylonitrile, isoprene, isobutylene, derivatives of (meth)acrylic acid, vinyl acetate, tetrafluoroethylene, vinylidene fluoride, hexafluoropropene, and 2-chlorobutadiene; polyisobutylene; polybutyl acrylate, and also combinations and mixtures thereof.

7. 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.

8. 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.

9. 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.

10. The polyamide molding composition as claimed in claim 8, wherein the cycloaliphatic diamines are MACM and/or PACM.

11. The polyamide molding composition as claimed in claim 9 or 10, wherein the aliphatic dicarboxylic acid is an aliphatic dicarboxylic acid having 10, 12, 14 or 18 carbon atoms.

12. The polyamide molding composition as claimed in any of claims 9 to 11, wherein the transparent polyamide is a homopolyamide selected from the group of MACM12, MACM14, MACM18 and/or is a copolyamide selected from the group of MACM12/PACM12, MACM14/PACM14, MACM18/PACM18.

13. 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.

14. The polyamide molding composition as claimed in claim 13, wherein the transparent homopolyamide and/or copolyamide is a polyamide selected from the group of: 6I6T, TMDT, 6I/MACMI/MACMT, 6I/6T/MACMI, MACMI/MACM36, 6I, 12/PACMI, 12/MACMI, 12MACMT, 6/PACMT, 6/6I, 6/IPDT, or a mixture thereof.

15. 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.

16. 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.

17. 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.

18. 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.

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

20. The polyamide molding composition as claimed in claim 19, wherein the solution viscosity (ηrel) of the low-viscosity polyamide-12 is from 1.5 to 2, preferably from 1.6 to 1.9.

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

22. The polyamide molding composition as claimed in claim 21, wherein the polyamide oligomer is a polyamide-12 oligomer whose average molar mass is from 1500 to 2500 g/mol, preferably having mainly non-condensable alkyl end groups.

23. 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.

24. 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.

25. 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.

26. The article as claimed in claim 24 or 25, which is a foil, a profile, a tube, a hollow body, or an optically variable filter or an optical lens, preferably is an ophthalmic lens, particularly preferably is an element with spectral filter action, for example in the form of a spectacle lens, sun lens, corrective lens, or optical filter, or in the form of a switching assembly or optical signal processing, ski goggles, visor, safety spectacles, photorecording, display, optical data storage, or windows of buildings and of vehicles, or is a decorative element or a structural element, for example in the form of a spectacle frame, toy, or cover, particularly in the form of a mobile-telephone case, a part of electronic devices, a coating, particularly of packaging, of decorative items, of sports equipment, or of cladding, preferably in the automobile sector.

27. The article as claimed in any of claims 24 to 26, which has a color gradient and/or has a photochromic coating, an antireflective coating, a scratch-resistant coating, an optical filter coating, a polarizing coating, an oxygen-barrier coating, or a combination of such coatings.

28. The article as claimed in any of claims 24 to 27, wherein the glass transition temperature of the region or the layer composed of the polyamide molding composition is above 90° C., preferably above 100° C., particularly preferably above 130° C.

29. The process for production of an article as claimed in any of claims 24 to 28, which comprises molding a polyamide molding composition as claimed in any of claims 1 to 23 in an extrusion process, in an injection-molding process, or in an in-mold-coating process, to give the article, where the photochromic dye can, if appropriate, be introduced in a downstream immersion-bath process and/or thermal transfer process into the mixture composed of transparent polyamide and of further polymer, and where the photochromic article can also be a foil which can be applied to a substrate, preferably an optical lens, via lamination or adhesive bonding.

30. The process for production of a bulk-colored molding as claimed in claim 28, which comprises compounding the photochromic dye together with the transparent homopolyamide and/or copolyamide and with the further polymer, where the dye can be added in the form of a liquid concentrate to the polymer melt composed of transparent homopolyamide and/or copolyamide and further polymer with the aid of a metering pump, and/or the dye is applied in the form of solid to the other components in a drum mixer, and where use may also be made, if appropriate, of application aids.

31. The process for production of a bulk-colored molding, as claimed in claim 29, wherein the dye and the further polymer are processed to give a masterbatch with high color concentration which is preferably up to 30%, and the required amount of this masterbatch is processed with the transparent polyamide and/or copolyamide in an extruder to give pellets or is converted directly into the finished molding in the injection-molding machine.