Weather-resistant multilayer systems
The invention relates to a multilayer product comprising a first layer (A), a second layer (B), a third layer (C), and a fourth layer (D). The first layer (A) is a scratch-resistant protective layer having a minimum extinction of 0.3 at 340 nm, the second layer (B) is an alkyl acrylate layer having a minimum extinction of 2 at 340 nm, and the third layer (C) and the fourth layer (D) contain a UV-stabilized polycarbonate. The invention also relates to a method for manufacturing the multilayer product.
1. A multilayer product comprising a first layer (A), a second layer (B), a third layer (C), and a fourth layer (D), wherein
the first layer (A) comprises a scratch-resistant protective layer which has an extinction of at least 0.2 at 340 nm, and which comprises an UV absorber of Formula (I):
wherein R represents a substituted or unsubstituted monocyclic or polycyclic aromatic residue, R 1 represents a branched or unbranched C 1 -C 10 alkyl, and R 2 represents a branched or unbranched C 1 -C 6 alkyl, and
the second layer (B) comprises an alkyl acrylate layer having an extinction of at least 2 at 340 nm, and which comprises a UV absorber of Formula (II):
wherein
X represents OR 1 ; OCH 2 CH 2 OR 1 ; OCH 2 CH(OH)CH 2 OR 1 or OCH(R 2 )COOR 3 , and wherein
R 1 respectively represents C 1 -C 13 alkyl, C 2 -C 20 alkenyl, C 6 -C 12 aryl or —CO—C 1 -C 18 alkyl;
R 2 represents H or C 1 -C 8 alkyl; and R 3 represents C 1 -C 12 alkyl, C 2 -C 12 alkenyl or C 5 -C 6 cycloalkyl and
Z, independently of one another, represents an unsubstituted phenyl or diphenyl or a phenyl or diphenyl singly or multiply substituted with C 1 -C 6 alkyl, and
the third layer (C) comprises a UV-stablized polycarbonate and the fourth layer (D) comprises polycarbonate which may be UV-stabilized.
2. The multilayer product according to claim 1 , wherein layer (A) has an extinction of at least 0.3 at 340 nm.
3. The multilayer product according to claim 1 , wherein layer (A) is based on sol-gel coating compositions and has an extinction of between 0.2 and 4 at 340 nm.
4. The multilayer product according to claim 1 , wherein layer (B) has an extinction of from 1 to 10 at 340 nm.
5. The multilayer product according to claim 1 , wherein the UV absorber is at least one compound selected from the group consisting of 4,6-dibenzoyl-2-(3-trialkoxysilylalklyl)resorcinol and 4,6-dibenzoyl-2-(3-triethoxysilylpropyl)resorcinol.
6. The multilayer product according to claim 1 , wherein, in Formula (II):
X represents OR 1 ,
R 1 represents CH 2 CH(CH 2 CH 3 )C 4 H 9 and
Z represents diphenyl.
7. The multilayer product according to claim 1 , further comprising at least one additional layer selected from (E) and (F) or a layer (G), wherein (E) is a further UV protection layer based on alkyl acrylate and comprises a UV stabiliser, (F) is a scratch protection layer and (G) is a UV-stabilised scratch protection layer.
8. The multilayer product according to claim 7 , wherein layer (E) comprises a UV absorber of Formula (II):
wherein
X represents OCH(R 2 )COOR 3 ,
R 2 represents CH 3 ,
R 3 represents C 8 H 17 and
Z represents diphenyl.
9. A method for manufacturing the multilayer product according to claim 1 , comprising providing the second and third layers (B and C) in the form of a coextruded film, two laminated films or a polycarbonate film coated with the layer (B), and back injection moulding the second and third layers, and contacting the second and third layers with layer (A).