Method for producing a polycarbonate layered composite
The invention relates to a method for making a structure with at least a first polymer layer and a second polymer layer, each made from a polycarbonate polymer based on bisphenol A, and in between the first polymer layer and the second polymer layer an intermediate layer being arranged, comprising the following steps: a) the intermediate layer is applied at least on a partial region of the first polymer layer, b) optionally the intermediate layer is dried, c) the first polymer layer is coated on the side, on which the intermediate layer is arranged, with a liquid preparation comprising a solvent or a mixture of solvents and a polycarbonate derivative based on a geminally disubstituted dihydroxydiphenyl cycloalkane, the preparation covering the intermediate layer, d) optionally a drying step is made after step c), e) after step c) or step d), the second polymer layer is placed on the first polymer layer, covering the intermediate layer, f) the first polymer layer and the second polymer layer are laminated with each other under pressure, at a temperature from 120° C. to 230° C. and for a defined time.
1. A method for making a structure with at least one first polymer layer ( 1 ) and a second polymer layer ( 2 ), each said layer is made from a polycarbonate polymer based on bisphenol A, and in between the first polymer layer ( 1 ) and the second polymer layer ( 2 ) is an intermediate layer ( 3 ) being arranged, comprising the following steps:
a) applying the intermediate layer ( 3 ) at least on a partial region of the first polymer layer ( 1 ),
b) optionally, drying the intermediate layer ( 3 ),
c) coating the first polymer layer ( 1 ) on the side, on which the intermediate layer ( 3 ) is arranged, with a liquid preparation comprising a solvent or a mixture of solvents and a polycarbonate derivative based on a geminally disubstituted dihydroxydiphenyl cycloalkane, the preparation covers the intermediate layer ( 3 ),
d) optionally, drying after step c),
e) after step c) or step d), placing the second polymer layer ( 2 ) on the first polymer layer ( 1 ) covering the intermediate layer ( 2 ), and
f) laminating the first polymer layer ( 1 ) and the second polymer layer ( 2 ) with each other under pressure, at a temperature from 120° C. to 230° C. and for a defined time, the intermediate layer being a layer that is configured to cause a reduced adherence of the first polymer layer to the second polymer layer relative to adherence of the first and second layer without use of the intermediate layer therebetween.
2. The method according to claim 1 , wherein the intermediate layer ( 3 ) is a printing layer comprising a security printing element and/or a printed photographic representation, a photographic emulsion, and/or a film, in particular a diffractive security film.
3. The method according to claim 1 , wherein the polycarbonate derivative has an average molecular weight (mean weight) of at least 10,000.
4. The method according to claim 1 , wherein the polycarbonate derivative comprises functional carbonate structure units of formula (I),
wherein
R 1 and R 2 are independently from each other hydrogen, halogen, C 1 -C 8 alkyl, C 5 -C 6 cycloalkyl, C 6 -C 10 aryl, and C 7 -C 12 aralkyl,
m is an integer from 4 to 7,
R 3 and R 4 can be individually selected for each X, and independently represent hydrogen or C 1 -C 6 alkyl
X is carbon and
n is an integer greater than 20,
with the proviso that at least one atom X, R 3 and R 4 are both alkyl.
5. The method according to claim 4 , wherein at 1 to 2 atoms X, R 3 and R 4 are both alkyl.
6. The method according to claim 4 , wherein R 3 and R 4 are methyl.
7. The method according to claim 4 , wherein the X atoms in the alpha position to the diphenyl-substituted C atom (C1) are not dialkyl-substituted.
8. The method according to claim 4 , wherein the X atoms in the beta position to C1 are disubstituted with alkyl.
9. The method according to claim 4 , wherein m is 4 or 5.
10. The method according to claim 4 , wherein the polycarbonate derivative is based on
4,4′-(3,3,5-trimethyl cyclohexane-1,1-diyl) diphenol,
4,4′-(3,3-dimethyl cyclohexane-1,1-diyl) diphenol, or
4,4′-(2,4,4-trimethyl cyclopentane-1,1-diyl) diphenol.
11. The method according to claim 1 , wherein the polycarbonate derivative comprises a copolymer consisting of monomer units M1 based on the formula HO—Z—OH, where Z is an aromatic radical with 6 to 30 atoms, and monomer units M2 based on the geminally disubstituted dihydroxydiphenyl cycloalkane, preferably of the 4,4′-(3,3,5-trimethyl cyclohexane-1,1-diyl) diphenol, wherein the molar ratio M2/M1 is greater than 0.3.
12. The method according to claim 1 , wherein the temperature in step f) is in the range from 140° C. to 200° C.
13. The method according to claim 1 , wherein the first polycarbonate layer ( 1 ) and the second polycarbonate layer ( 2 ) have a glass temperature Tg of more than 145° C.
14. The method according to claim 1 , wherein the thickness of the first polycarbonate layer ( 1 ) and of the second polycarbonate layer ( 2 ) differ by no more than 1,000 μm.
15. The method according to claim 1 , wherein the thickness, measured in directions orthogonal to a main face of a polycarbonate layer ( 1 , 2 ), of the intermediate layer ( 3 ) is in the range from 0.1 to 1,000 μm.
16. The method according to claim 1 wherein the structure is a security and/or value document, and further comprising directly or indirectly connecting at least one additional layer with the first polycarbonate layer ( 1 ) and/or the second polycarbonate layer ( 2 ).