COATING AGENT AND FILMS HAVING INCREASED MECHANICAL AND CHEMICAL RESISTANCE AND SUFFICIENT DEFORMABILITY IN 2-D FILM INSERT MOLDING METHODS

Abstract

A coating agent and films coated with it are provided, of which the coating comprises an enhanced mechanical and chemical resistance and a formability adequate for 2-D-film-insert molding processes. The coating agent, comprising (a) at least one thermoplastic polymer with a proportion of at least 30% by weight of the solid content of the coating agent; (b) at least one UV hardenable reactive thinner with a proportion of at least 30% by weight of the solid content of the coating agent; (c) at least one photo-initiator; and (d) at least one organic solvent, wherein the proportion of ethylenically unsaturated groups amounts to at least 3 mol per kg of the solid content of the coating agent, wherein the at least one reactive thinner comprises at least three polymerisable (meth)acrylate functions in the molecule and wherein the ester-oxygen atoms of the (meth)acrylate functions in the molecule of the reactive thinner are separated from one another by a chain of at least six atoms.

Claims

1.-15. (canceled)

16. A coating agent comprising (a) at least one thermoplastic polymer with a proportion of at least 30% by weight of the solid content of the coating agent; (b) at least one UV hardenable reactive thinner with a proportion of at least 30% by weight of the solid content of the coating agent; (c) at least one photo-initiator; and (d) at least one organic solvent, wherein the proportion of ethylenically unsaturated groups amounts to at least 3 mol per kg of the solid content of the coating agent, wherein the at least one reactive thinner comprises at least three polymerisable (meth)acrylate functions in the molecule and wherein the ester-oxygen atoms of the (meth)acrylate functions in the molecule of the reactive thinner are separated from one another by a chain of at least six atoms.

17. The coating agent according to claim 16, wherein the proportion of ethylenically unsaturated groups amounts to at least 3.5 mol per kg of the solid content of the coating agent.

18. The coating agent according to claim 16, wherein the atoms of the chain separating the ester-oxygen atoms of the acrylate functions in the molecule of the reactive thinner are selected from C, N, O, S and P atoms and combinations thereof.

19. The coating agent according to claim 16, wherein the ester-oxygen atoms of the acrylate functions in the molecule of the reactive thinner are separated from one another by a chain of at least nine atoms.

20. The coating agent according to claim 16, wherein the at least one reactive thinner is selected from the group consisting of triacrylates of ethoxylated trimethylol propane, tetraacrylates of ethoxylated pentaerythrite.

21. The coating agent according to claim 20, wherein the reactive thinner is ethoxylated (4) pentaerythrite-tetraacrylate and/or ethoxylated (9) trimethylol propane-triacrylate, preferably ethoxylated (4) pentaerythrite-tetraacrylate.

22. The coating agent according to claim 16, wherein the thermoplastic polymer comprises PMMA homopolymers and/or copolymers made of 70% by weight to 99.5% by weight methylmethacrylate and 0.5% by weight to 30% by weight methylacrylate.

23. The coating agent according to claim 16, wherein the solvent is 1-methoxy-2-propanol.

24. A coated film comprising a synthetic-material film and a coating, obtained by coating at least one side of the synthetic-material film with a coating agent according to claim 16.

25. The coated film according to claim 24, wherein the coating is dried and hardened directly after the coating.

26. The coated film according to claim 24, wherein the synthetic material of the synthetic-material film is selected from polycarbonate, copolycarbonate, polyester, polyethylene terephthalate, polypropylene, polystyrene, polyvinylchloride, preferably polycarbonate and/or copolycarbonate.

27. The coated film according to claim 24, wherein the coating is present with a layer thickness in the range from 0.1 m to 50 m.

28. A method for manufacturing a molded part, comprising the steps (I) coating of a surface of a film with a coating agent according to claim 16; (II) drying of the coating; (III) hardening of the coating through actinic radiation, preferably UV radiation; (IV) thermally and/or mechanically deforming the film; (V) back coating of the uncoated surface of the film with at least one thermoplastic polymer, wherein the steps (IV) and (V) can be implemented successively or simultaneously.

29. The method according to claim 28, wherein the steps (IV) and (V) take place simultaneously.

30. A molded body comprising at least one coated film according to claim 24.

Description

EXAMPLES

Evaluation Methods

[0077] The layer thickness of the coatings was measured by observation of the cut edge in an optical microscope of the type Axioplan manufactured by Zeiss. Methodincident light, bright field, enlargement 500.

Evaluation of Pencil Hardness

[0078] The pencil hardness was measured by analogy with ASTM D 3363 using an Elcometer 3086 Scratch boy (Elcometer Instruments GmbH, Aalen, Germany) with a load of 500 g, unless otherwise indicated.

Evaluation of the Steel Wool Scratching

[0079] The steel wool scratching is determined by glueing a steel wool No. 00 (Oskar Well GmbH Rakso, Lahr, Germany) onto the flat end of a 500 g hammer, wherein the area of the hammer is 2.5 cm2.5 cm, that is, approximately 6.25 cm2. The hammer is placed without additional pressure onto the area to be tested, so that a defined load of approximately 560 g is reached. The hammer is then moved back and forth 10 times in double strokes. Following this, fabric residues and lacquer particles are cleaned from the loaded surface with a soft cloth. The scratching is characterised by haze and gloss values, measured transversely to the scratching direction with a Micro-HAZE plus (20-Gloss and Haze; Byk-Gardner GmbH, Geretsried, Germany). The measurement is implemented before and after scratching. The difference values for gloss and haze before and after loading are indicated as gloss and haze.

Evaluation of Solvent Resistance

[0080] The solvent resistance of the coatings was measured conventionally with isopropanol, xylene, 1-methoxy-2-propylacetate, ethylacetate, acetone of technical quality. The solvents were applied to the coating with an impregnated cotton wool swab and protected from evaporation by covering. Unless otherwise described, an acting time of 60 minutes at approximately 23 C. was observed. After the end of the acting time, the cotton wool swab is removed and the test area is wiped clean with a soft cloth. The examination is carried out visually immediately and after light scratching with a fingernail.

[0081] The following stages are distinguished: [0082] 0=unchanged; no change visible; not damaged by scratching. [0083] 1=slight swelling visible, but not damaged by scratching. [0084] 2=change clearly visible, hardly damaged by scratching. [0085] 3=noticeably changed; surface destroyed after firm fingernail pressure. [0086] 4=strongly changed after firm fingernail pressure scratched through to substrate. [0087] 5=destroyed; the lacquer is already destroyed when wiping away the chemicals; the test substance is not removable (pitted).

[0088] Within this evaluation, the test is conventionally passed with the values 0 and 1. Values >1 stand for not passed.

Example 1

[0089] 175 g Degacryl M547 (Evonik) were completely dissolved in 994 g 1-methoxy-2-propanol at 100 C. within approximately 3 h. The solution was cooled to approximately 30 C. Separately, the following components were dissolved in 581 g 1-methoxy-2-propanol at room temperature: 252 g ethoxylated (4) pentaerythrite-tetraacrylate (SR 494, Sartomer), 10.1 g Esacure One (Lamberti), 5.04 g Darocur 4265 (BASF), 0.9 g BYK 333 (BYK). The second solution was added to the polymer solution while stirring. The coating agent obtained in this manner was stirred for a further 3 h at room temperature and, with a screening of the influence of direct light, bottled and allowed to rest for 1 day. The yield was 2000 g, the viscosity (23 C.) 1380 mPas and the solid content 22% by weight. The calculated double bond density in the solid content of the coating agent was approximately 4.5 mol/kg.

Example 2

[0090] 200 g Degacryl M547 (Evonik) were completely dissolved in 1136 g 1-methoxy-2-propanol at 100 C. within approximately 3 h. The solution was cooled to approximately 30 C. Separately, the following components were dissolved in 664 g 1-methoxy-2-propanol at room temperature: 200 g ethoxylated (4) pentaerythrite-tetraacrylate (SR 494, Sartomer), 8 g Esacure One (Lamberti), 4 g Darocur 4265 (BASF), 1 g BYK 333 (BYK). The second solution was added to the polymer solution while stirring. The coating agent obtained in this manner was stirred for a further 3 h at room temperature and, with a screening of the influence of direct light, bottled and allowed to rest for 1 day. The yield was 2200 g, the viscosity (23 C.) 1800 mPas and the solid content 19% by weight. The calculated double bond density in the solid content of the coating agent was approximately 3.8 mol/kg.

Comparison Example 1

[0091] 275 g Degacryl M547 (Evonik) were completely dissolved in 1562 g 1-methoxy-2-propanol at 100 C. within approximately 3 h. The solution was cooled to approximately 30 C. Separately, the following components were dissolved in 913 g 1-methoxy-2-propanol at room temperature: 275 g dipentaerythrite-penta/hexaacrylate (DPHA, Cytec), 11 g Esacure One (Lamberti), 5.5 g Darocur 4265 (BASF), 1.4 g BYK 333 (BYK). The second solution was added to the polymer solution while stirring. The coating agent obtained in this manner was stirred for a further 3 h at room temperature and, with a screening of the influence of direct light, bottled and allowed to rest for 1 day. The yield was 3000 g, the viscosity (23 C.) 2453 mPas and the solid content 19% by weight. The calculated double bond density in the solid content of the coating agent was approximately 5.1 mol/kg.

Example 3

[0092] The coating agents corresponding to Examples 1 and 2 and Comparison Example 1 were applied by means of slot caster to a carrier film, for example Makrofol DE 1-1 (Bayer MaterialScience AG, Leverkusen, Germany).

[0093] Typical application conditions whereas follows: [0094] Track velocity 1.3 to 2.0 m/min. [0095] Wet lacquer application 20-150 m [0096] Ambient air dryer 90-110 C., preferably within the range of the T.sub.g of the polymer to be dried. [0097] Dwell time in the dryer 3.5-5 min.

[0098] The coating was implemented roller-to-roller, that is, the polycarbonate film was unrolled in the coating plant. The film was guided through one of the above named application appliances and charged with the coating solution. After that, the film with the wet coating was passed through the dryer. After leaving the dryer, the now dried coating was transferred continuously into a UV hardening plant and then provided with a lamination film in order to protect the latter from contamination and scratching. Following this, the film was rolled up again.

Example 4

[0099] The chemical and scratch resistance of the coated sides of the coated films from Example 3 were tested as indicated above. The results are summarised in Table 1.

TABLE-US-00001 TABLE 1 Chemical and scratch resistance of the coatings Steel wool Solvent Pencil (Manufactured by Coating agent/ IP/MPA/X/ hardness Rakso, No. 00) Layer thickness on EA/Ac 500 g 560 g/10 DH 250 m PC-film 1 h/RT Mitsubishi G/H Example 1/6 m 0/0/0/0/1 B 2/3 Example 1/11 m 0/0/0/0/1 HB 1/2 Example 1/16 m 0/0/0/0/1 HB 3/3 Example 1/22 m 0/0/0/0/0 F 3/4 Example 1/25 m 0/0/0/0/1 H 2/3 Example 2/5 m 0/0/0/1/5 B 0/1 Example 2/8 m 0/0/0/0/5 HB 3/6 Example 2/13 m 0/0/0/0/0 HB 0/4 Example 2/17 m 0/0/0/0/0 F 2/1 Example 2/23 m 0/0/0/0/0 H 2/4 Comparison Example 0/0/0/0/1 B 3/4 1/6 m Comparison Example 0/0/0/0/0 B 1/4 1/9 m Comparison Example 0/0/0/0/0 HB 5/9 1/12 m Comparison Example 0/0/0/0/0 HB 9/16 1/16 m Comparison Example 0/0/0/0/0 F 3/8 1/23 m Makrofol DE 1-1 250 m, 0/5/5/5/5 3B 100/285 uncoated

[0100] IP/MPA/X/EA/Ac stands for isopropanol, 1-methoxy-2-propylacetate, xylene, ethylacetate, acetone

[0101] RT stands for room temperature, here approximately 23 C.

[0102] As shown in Table 1, even in a thin layer, the coating according to the invention improves the pencil hardness and scratch resistance of the film significantly by comparison with the known properties of the polycarbonate. The coating according to the invention also provides a high solvent resistance.

Example 5

[0103] The film coated according to the invention can be deformed with the process described above according to the current prior art.

[0104] In the film-insert molding process, the film according to the invention is optionally printed on the rear side, punched into the desired shape or cut to size and placed into the injection molding mold. The injection molding experiments were carried out with an injection molding machine of the type Arburg TYP: 570C 2000/-675(350). After closing of the mold, the film was back injected with Makrolon 2405 (Bayer) with a mass temperature of 280 C. The filling time for the filling of the tool was 2 seconds. The tool temperature was varied. Good results were achieved with a tool temperature in the range from 80 C. and 100 C. In this respect, no negative effect was observed visually. The holding-pressure time was 12 seconds and the cooling time was disposed around 20 seconds.

[0105] It was noted here, that the easy deformation of film and lacquer here took place rapidly and without special heating. Many commercially available hardcoats do not withstand this deformation without forming cracks.

[0106] With the method, the heating-ventilation screens (HV screens) were manufactured from the films of Example 3 (coating agent from Examples 1 and 2 and of the Experiment Example 1). The surfaces, especially the critical radii, were evaluated optically after manufacture of the HV screens, by means of a microscope from ZEISS, type: Axioplan (enlargement 6). The samples without visible cracks on the entire surface were evaluated positively.

[0107] The results are summarised in Table 2:

TABLE-US-00002 TABLE 2 Evaluation of the front surface of the synthetic-material parts manufactured in the film-insert molding process Coating agent/ Observation in optical Layer thickness on stereo-microscope 250 m PC-film (Enlargement 6x) Example 1 - 6 m Crack-free surface Example 1 - 11 m Crack-free surface Example 1 - 16 m Crack-free surface Example 2 - 5 m Crack-free surface Example 2 - 8 m Crack-free surface Example 2 - 13 m Crack-free surface Example 2 - 17 m Crack-free surface Comparison Example Crack-free surface 1 - 6 m Comparison Example Isolated cracks 1 - 9 m Comparison Example Isolated cracks 1 - 12 m Comparison Example Isolated cracks 1 - 16 m

[0108] The examples have shown that the films according to the invention with the coatings from the Examples 1 and 2 withstand the 2-D forming in the back-injection process without problems, without the hardcoat layer experiencing damage here. In this case, the coating agent according to the invention contains ethoxylated (4) pentaerythrite-tetraacrylate (SR 494, Sartomer) as reactive thinner. The shortest connecting chain between two acrylate groups in molecule of this reactive thinner contained, according to the invention, 9 atoms.

[0109] By contrast, films with the coatings from the Comparison Example 1 receive isolated cracks in the region of the strongest deformation after the 2-D forming in the back-injection process. In this case, the coating agent contains dipentaerythrite-penta/hexaacrylate (DPHA, Cytec) as reactive thinner. The shortest connecting chain between two acrylate groups in molecule of this reactive thinner contains only 3 atoms.