METHOD FOR PRODUCING A POLYCARBONATE LAYERED COMPOSITE

Abstract

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.

Claims

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.

2. A method according to claim 1, wherein the intermediate layer (3) is a printing layer, in particular 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, preferably from 20,000 to 300,000.

4. The method according to claim 1, wherein the polycarbonate derivative comprises functional carbonate structure units of formula (I), ##STR00004## wherein R.sup.1 and R.sup.2 are independently from each other hydrogen, halogen, preferably chlorine or bromine, C.sub.1-C.sub.8 alkyl, C.sub.5-C.sub.6 cycloalkyl, C.sub.6-C.sub.10 aryl, preferably phenyl, and C.sub.7-C.sub.12 aralkyl, preferably phenyl-C.sub.1-C.sub.4 alkyl, in particular benzyl, m is an integer from 4 to 7, preferably 4 or 5, R.sup.3 and R.sup.4 can be individually selected for each X, and independently represent hydrogen or C.sub.1-C.sub.6 alkyl X is carbon and n is an integer greater than 20, with the proviso that at least one atom X, R.sup.3 and R.sup.4 are both alkyl.

5. The method according to claim 4, wherein at 1 to 2 atoms X, in particular at only one atom X, R.sup.3 and R.sup.4 are both alkyl.

6. The method according to claim 4, wherein R.sup.3 and R.sup.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-trimethylcyclopentane-1,1-diyl) diphenol.

11. The method according to claim 1, wherein the polycarbonate derivative comprises a copolymer in particular consisting of monomer units M1 based on formula (Ib) 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 preferably is greater than 0.3, in particular greater than 0.4, preferably greater than 0.5.

12. The method according to claim 1, wherein the temperature in step f) is in the range from 140° C. to 200° C., in particular in the range from 150° C. to 180° 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) is identically or different in the range from 10 to 1,000 in particular from 20 to 200 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, in particular from 1 to 50 μm.

16. A structure obtainable with a method according to claim 1.

17. A structure comprising at least one first polycarbonate layer (1), a second polycarbonate layer (2), an intermediate layer (3) arranged between the first polycarbonate layer (1) and the second polycarbonate layer (2) and a preparation layer (4) connecting the intermediate layer (3) with the second polycarbonate layer (2) and comprising a polycarbonate derivative based on a geminally disubstituted dihydroxydiphenyl cycloalkane.

18. The use of a method according to claim 1 for making a security and/or value document, wherein optionally simultaneously with, before or after the production of the structure, the first polycarbonate layer (1) and/or the second polycarbonate layer (2) are directly or indirectly connected with at least one additional layer, for instance a carrier layer.

19. The security and/or value document obtainable according to claim 18.

20. The security and/or value document comprising a structure according to claim 16.

Description

[0053] In the following, the invention is described in more detail with reference to non-limiting embodiments. There are:

[0054] FIG. 1: layer thickness measurements at a layer produced by printing techniques with a preparation used according to the invention, after one-time printing (FIG. 1a) and after two-times printing (FIG. 1b), and

[0055] FIG. 2: process flow of making a multi-layer structure with a printing layer.

EXAMPLE 1: MAKING POLYCARBONATE DERIVATIVES TO BE USED ACCORDING TO THE INVENTION

[0056] Preferred are the polycarbonate derivatives of the Examples 1.3 to 1.5.

Example 1.1: Making a First Polycarbonate Derivative

[0057] 205.7 g (0.90 mole) bisphenol A (2,2-bis-(4-hydroxyphenyl)-propane, 30.7 g (0.10 mole) 1,1-bis-(4-hydroxyphenyl)-3,3,5-trimethyl cyclohexane, 336.6 g (6 moles) KOH and 2,700 g water are dissolved in an inert gas atmosphere under stirring. Then a solution of 1.88 g phenol in 2,500 ml methylene chloride is added. Into the well stirred solution, 198 g (2 moles) phosgene are introduced at pH 13 to 14 and 21 to 25° C. Then 1 ml ethylpiperidine is added and stirred for another 45 min. The bisphenolate-free aqueous phase is separated, after acidification with phosphoric acid, the organic phase is washed neutrally with water and freed from solvent.

[0058] The polycarbonate derivative had a relative solution viscosity of 1.255. The glass temperature was determined to be 157° C. (DSC).

Example 1.2: Making a Second Polycarbonate Derivative

[0059] In an analogous manner to Example 1, a mixture of 181.4 g (0.79 mole) bisphenol A and 63.7 g (0.21 mole) 1,1-bis-(4-hydroxyphenyl)-3,3,5-trimethyl cyclohexane was reacted to the polycarbonate derivative.

[0060] The polycarbonate derivative had a relative solution viscosity of 1.263. The glass temperature was determined to be 167° C. (DSC).

Example 1.3: Making a Third Polycarbonate Derivative

[0061] In an analogous manner to Example 1, a mixture of 149.0 g (0.65 mole) bisphenol A (2,2-bis-(4-hydroxyphenyl)-propane and 107.9 g (0.35 mole) 1,1-bis-(4-hydroxyphenyl)-3,3,5-trimethyl cyclohexane was reacted to the polycarbonate derivative.

[0062] The polycarbonate derivative had a relative solution viscosity of 1.263. The glass temperature was determined to be 183° C. (DSC).

Example 1.4: Making a Fourth Polycarbonate Derivative

[0063] In an analogous manner to Example 1, a mixture of 91.6 g (0.40 mole) bisphenol A and 185.9 g (0.60 mole) 1,1-bis-(4-hydroxyphenyl)-3,3,5-trimethyl cyclohexane was reacted to the polycarbonate derivative.

[0064] The polycarbonate derivative had a relative solution viscosity of 1.251. The glass temperature was determined to be 204° C. (DSC).

Example 1.5: Making a Fifth Polycarbonate Derivative

[0065] As in Example 1, a mixture of 44.2 g (0.19 mole) bisphenol A and 250.4 g (0.81 mole) 1,1-bis-(4-hydroxyphenyl)-3,3,5-trimethyl cyclohexane was reacted to the polycarbonate.

[0066] The polycarbonate derivative had a relative solution viscosity of 1.248. The glass temperature was determined to be 216° C. (DSC).

EXAMPLE 2: MAKING LIQUID PREPARATIONS USED ACCORDING TO THE INVENTION

[0067] The following different liquid preparations were made:

[0068] A first liquid preparation was made from 17.5 weight parts of the polycarbonate derivative from Example 1.3 and 82.5 weight parts of a solvent mixture according to Table I.

TABLE-US-00001 TABLE I Mesitylene 2.4 1-methoxy-2-propanolacetate 34.95 1,2,4-trimethylbenzene 10.75 Ethyl-3-ethoxypropionate 33.35 Cumol 0.105 Solvent naphtha 18.45

[0069] A colorless, highly viscous solution with a solution viscosity of 800 mPas at ambient temperature was obtained.

[0070] Further liquid preparations were made according to the following Table II.

TABLE-US-00002 TABLE II Used substance wt % wt % wt % wt % wt % wt % wt % Solv. mixture of 90 90 90 95 95 of Tab. I Acetone 95 Butanone 95 Example 1.3 10 5 5 Example 1.4 10 Example 1.5 10 Example 1.2 5 Example 1.1 5

[0071] The preparations of the Table II were applied on glass plates for the purpose of deter-mining the softening temperatures, so that dry-layer thicknesses of 5 μm resulted. The layers were dried for 1 hour at 100° C. in the vacuum dry box. Then, the dried films were separated from the glass plate and examined by means of Differential Scanning calorimetry (DSC).

[0072] The following thermal conversion temperatures were measured for the films:

TABLE-US-00003 1.sup.st 2.sup.nd Delta Polymer heating Cooling heating 1.sup.st heating/ from Solvent [° C.] [° C.] [° C.] 2.sup.nd heating Example Hydrocarbon 112.41 113.88 1.47 1.1 mixture Example Hydrocarbon 143.02 144.29 144.28 1.26 1.2 mixture Example Hydrocarbon 128.54 171.56 176.45 47.89 1.3 mixture Example Hydrocarbon 172.45 188.22 191.68 19.23 1.4 mixture Example Hydrocarbon 170.39 207.20 207.06 36.67 1.5 mixture Example Acetone 165.80 155.40 157.22 −8.58 1.3 Example Butanon 174.21 172.20 179.11 4.9 1.3

[0073] It is remarkable that for instance the film of Example 1.3 has after drying after the 1.sup.st heating-up step a softening temperature of 128.54° C. Only after the cooling-off and 2.sup.nd heating-up steps, the expected transitions at 171.56 or 176.45° C., respectively are observed.

[0074] Due to the fair solubility for instance of the polycarbonate derivate of Example 1.3 in halogen-free solvents and the detected softening behavior of dried films, this material is excellently suitable to serve as a bonding agent in polycarbonate-based structure materials, in particular so-called smart cards.

EXAMPLE 3: MAKING STRUCTURES ACCORDING TO THE INVENTION

[0075] A polycarbonate film 1 Makrofol® 6-2 (thickness approx. 100 μm) is covered with an intermediate layer 3, in the example a printing layer 3 (FIG. 2a), for instance by means of offset or silk-screen printing. On the left side, a printing layer with a screened print can be seen, whereas on the right side a printing layer 3 of a print over the full surface is shown. The printing layer 3 is first dried, if applicable. Then the side of the polycarbonate film 1 provided with the printing layer 3 is fitted for instance by silk-screen printing with a preparation layer 4 of a composition of Example 2, for instance based on the polycarbonate derivate according to Example 1.3 and the mixture of solvents according to Table I (FIG. 2b). This can take place either over the full surface, or, as shown, partially only, covering the regions of the printing layer 3. Silk-screen printing is made once or twice. Then drying is made under air atmosphere at 100° C. for 60 min. A layer thickness of approx. 2.2 μm or 3.3 μm of the dried polycarbonate derivate (FIG. 2b) results. Then the side of the polycarbonate film 1 with the printing layer 3 and the preparation layer 4 is covered with another polycarbonate film 2 Makrofol® 6-2 (thickness approx. 100 μm), and the thus resulting structure is laminated with, if applicable, further stacked polymer layers 5, 6, 7 in a conventional industrial laminating press under the action of usual pressures (approx. 5 bars) and at about 160° C. (FIGS. 2c and 2d).

[0076] An optical investigation of the structure did not show any recognizable phase limit. The structure is a monolithic block.

[0077] Comparative experiments were made in a corresponding manner, however without the preparation layer 4. Then it was found that a structure according to the invention is clearly more stable against delamination between the printing layer 3 and the second polymer layer 2 than in said comparative experiments representing prior art.