Multi-layer composite
A process for the production of a multi-layer composite comprising applying a coating layer from a pigmented coating composition A onto the back face of a transparent plastic film and then applying an NIR-opaque coating layer from a pigmented coating composition B, wherein the pigment content of coating composition A consists 50 to 100 wt. % of black pigment with low NIR absorption and 0 to 50 wt. % of further pigment, which is selected in such a way that coating layer A′ exhibits low NIR absorption and that the multi-layer composite exhibits a brightness L* of at most 10 units, wherein the pigment content of coating composition B is either a pigment content PC 1 consisting 90 to 100 wt. % of aluminum flake pigment and 0 to 10 wt. % of further pigment, which is selected in such a way that NIR-opaque coating layer B′ exhibits low NIR absorption, or a pigment content PC 2 comprising <90 wt. % of aluminum flake pigments and being composed in such a way that NIR-opaque coating layer B′ exhibits low NIR absorption, and wherein coating layers A′ and B′ are cured.
1. A process for the production of a multi-layer composite consisting of steps (1)-(3) as follows:
(1) applying a visually-opaque coating layer A′ from a solvent-or water-borne pigmented coating composition A directly onto the back face of a transparent plastic film such that the coating layer A′ is in direct physical contact with the transparent plastic film, wherein composition A comprises a pigment content and a resin solids content, wherein a ratio of pigment content to resin solids content is from 0.1:1 to 1:1, and wherein the overall solids content of composition A is from 10% to 40% by weight, and
(2) applying an NIR-opaque coating layer B′ from a solvent- or water-borne pigmented coating composition B directly onto the coating layer A′ such that coating layer B′ is in direct physical contact with the coating layer A′ but not the transparent plastic film, wherein composition B is different than composition A, wherein composition B comprises a pigment content and a resin solids content, wherein a ratio of pigment content to resin solids content is either from 0.1:1 to 2:1 or from 0.05:1 to 50:1, wherein the overall solids content of composition B is from 2% to 40% by weight,
wherein the pigment content of coating composition A consists of 50 to 100 wt. % of at least one black pigment with low NIR absorption and 0 to 50 wt. % of at least one further pigment, which is selected in such a way that coating layer A′, in and of itself, exhibits low NIR absorption, and wherein the at least one black pigment with low NIR absorption is chosen from one or more of iron oxide black pigments, mixed metal/iron oxide black pigments, and perylene black pigments,
wherein the pigment content of coating composition B is either a pigment content PC 1 consisting of 90 to 100 wt. % of at least one aluminum flake pigment and 0 to 10 wt. % of at least one further pigment, which is selected in such a way that NIR-opaque coating layer B′, in and of itself, exhibits low NIR absorption, or a pigment content PC 2 comprising <90 wt. % of aluminum flake pigments and being composed in such a way that NIR-opaque coating layer B′, in and of itself, exhibits low NIR absorption, and
(3) curing coating layers A′ and B′, wherein the multi-layer composite produced by the method consisting of steps (1)-(3) exhibits a brightness L* of at most 10 units.
2. The process of claim 1 , wherein coating composition A does not contain any carbon black.
3. The process of claim 1 , wherein coating composition B has the pigment content PC 1 and not the pigment content PC 2 .
4. The process of claim 1 , wherein coating composition B has the pigment content PC 2 and not the pigment content PC 1 .
5. The process of claim 4 , wherein coating composition B is either (i) a solid color, white, or black coating composition free of special effect pigments, (ii) a coating composition comprising from 80 to 100 wt. % titanium dioxide, or (iii) a coating composition comprising less than 25 wt. % of aluminum flake pigments.
6. The process of claim 1 , wherein coating composition B does not contain any carbon black.
7. The process of claim 1 , wherein coating composition A is applied by roller coating.
8. The process of claim 1 , wherein coating composition B is applied by roller coating.