METALLIZABLE, SCRATCH-RESISTANT AND SOLVENT-RESISTANT FILM

Abstract

The present invention relates to a coating composition comprising at least one thermoplastic acrylonitrile-butadiene-styrene copolymer in a content of at least 30% by weight of the solids content of the coating composition, at least one UV-curable reactive diluent in a content of at least 30% by weight of the solids content of the coating composition, at least one photoinitiator in a content of 0.1 to 10 parts by weight of the solids content of the coating composition and at least one organic solvent, where the proportion of ethylenically unsaturated groups is at least 3 mol per kg of the solids content of the coating composition. This is used to provide films and mouldings coated therewith, having a metallizable, scratch-resistant and solvent-resistant surface.

Claims

1.-15. (canceled)

16. A coating composition comprising (a) at least one thermoplastic acrylonitrile-butadiene-styrene copolymer in a content of at least 30% by weight of the solids content of the coating composition; (b) at least one UV-curable reactive diluent in a content of at least 30% by weight of the solids content of the coating composition; (c) at least one photoinitiator in a content of 0.1 to 10 parts by weight of the solids content of the coating composition; and (d) at least one organic solvent, where the proportion of ethylenically unsaturated groups is at least 3 mol per kg of the solids content of the coating composition, wherein the acrylonitrile-butadiene-styrene copolymer (a) has an acrylonitrile content in the range from 22% to 25%, and wherein the acrylonitrile-butadiene-styrene copolymer (a) has a polybutadiene content in the range from 10% to 16%.

17. The coating composition as claimed in claim 16, wherein the acrylonitrile-butadiene-styrene copolymer (a) has a Vicat softening temperature VET to ISO 306 of at least 95 C.

18. The coating composition as claimed in claim 16, wherein the at least one UV-curable reactive diluent (b) comprises bifunctional, trifunctional, tetrafunctional, pentafunctional and/or hexafunctional acrylic and/or methacrylic monomers.

19. The coating composition as claimed in claim 16, wherein the solvent (d) is selected from 1-methoxy-2-propanol, diacetone alcohol, 2,2,3,3-tetrafluoropropanol and mixtures thereof.

20. The coating composition as claimed in claim 16, wherein the solvent (d) comprises a mixture of 1-methoxy-2-propanol and at least 50% by weight of diacetone alcohol.

21. A coated film comprising a film of a thermoplastic polymer and a coating obtained by coating with a coating composition as claimed in claim 16.

22. The coated film as claimed in claim 21, comprising a polycarbonate film or a copolycarbonate film.

23. The coated film as claimed in claim 21, further comprising a partial metal coating or a metal layer on the coated surface.

24. The coated film as claimed in claim 23, wherein the metal layer comprises at least one metal selected from the group consisting of tin, lead, silver, gold, palladium, platinum, cobalt, manganese, bismuth, copper, nickel, iron, chromium and mixtures thereof.

25. A process for producing a coated film, comprising the steps of: (i) coating a film with a coating composition as claimed in claim 16; (ii) drying the coating; (iii) optionally cutting the film to size and/or delaminating, printing and/or thermally or mechanically forming the film; (iv) irradiating the coating with UV radiation to cure the coating.

26. A method comprising utilizing the coating composition as claimed in claim 16 for the production of 3D mouldings for the automotive, transport, electricals, electronics and construction industries in a film insert moulding process.

27. A moulded component comprising at least one coated film as claimed in claim 24.

Description

EXAMPLES

Assessment Methods

Layer Thickness

[0083] The layer thickness of the coatings was measured by observing the cutting edge in an Axioplan optical microscope manufactured by Zeiss. Methodreflected light, bright field, magnification 500.

Assessment of Blocking Resistance

[0084] Conventional test methods as described, for instance, in DIN 53150 are insufficient to simulate the blocking resistance of rolled-up, pre-dried, coated films, and therefore the following test was employed: The coating materials were applied to Makrofol DE 1-1 (375 m) with a conventional coating bar (target wet film thickness 100 m). After a flash-off phase at 20 C. to 25 C. for 10 min, the coated films were dried in an air circulation oven at 110 C. for 10 min. After a cooling phase for 1 min, a commercial GH-X173 natur pressure-sensitive lamination film (manufacturer: Bischof und Klein, Lengerich, Germany) was applied without creasing to the dried coated film with a plastic roller over an area of 100 mm100 mm. Subsequently, the laminated film piece was subjected to a weight of 10 kg over the full area for 1 hour. Thereafter, the lamination film was removed and the coated surface was assessed visually.

Assessment of Pencil Hardness

[0085] The pencil hardness was measured analogously to ASTM D 3363 using an Elcometer 3086 Scratch boy (Elcometer Instruments GmbH, Aalen, Germany) under a load of 500 g, unless stated otherwise.

Assessment of Steel Wool Scratching

[0086] The steel wool scratching was determined by sticking a piece of No. 00 steel wool (Oskar Weil GmbH Rakso, Lahr, Germany) onto the flat end of a 500 g fitter's hammer, the area of the hammer being 2.5 cm2.5 cm, i.e. approximately 6.25 cm.sup.2. The hammer was placed onto the surface to be tested without applying additional pressure, such that a defined load of about 560 g was attained. The hammer was then moved back and forth 10 times in twin strokes. Subsequently, the stressed surface was cleaned with a soft cloth to remove fabric residues and coating particles. The scratching was characterized by haze and gloss values, measured transverse to the scratching direction, with a Micro HAZE plus (20 gloss and haze; Byk-Gardner GmbH, Geretsried, Germany). The measurement was effected before and after scratching. The differential values for gloss and haze before and after stress are reported as gloss and haze.

Assessment of Solvent Resistance

[0087] The solvent resistance of the coatings was typically tested with isopropanol, xylene, 1-methoxy-2-propyl acetate, ethyl acetate, acetone, in technical-grade quality. The solvents were applied to the coating with a cotton bud soaked therewith and protected from vaporization by covering. Unless stated otherwise, a contact time of 60 minutes at about 23 C. was observed. After the end of the contact time, the cotton bud was removed and the test surface was wiped clean with a soft cloth. The inspection was immediately effected visually and after gentle scratching with a fingernail.

[0088] A distinction is made between the following levels: [0089] 0=unchanged; no change visible; cannot be damaged by scratching. [0090] 1=slight swelling visible, but cannot be damaged by scratching. [0091] 2=change clearly visible, can barely be damaged by scratching. [0092] 3=noticeable change, surface destroyed after firm fingernail pressure. [0093] 4=significant change, scratched through to the substrate after firm fingernail pressure. [0094] 5=destroyed; the coating is already destroyed when the chemical is wiped away; the test substance cannot be removed (has eaten into the surface).

[0095] Within this assessment, the test is typically passed with the ratings of 0 and 1. Ratings of >1 represent a fail.

Example 1

Production of a Coating Composition

[0096] 117 g of NovodurN H604 (manufacturer: Styrolution) were distributed homogeneously in 284 g of a mixture (2:3) of 1-methoxy-2-propanol and diacetone alcohol at 100 C. within about 3 h. The stable colloidal solution obtained in this way was cooled down to about 30 C. Separately, the following components were dissolved in 166 g of the mixture (2:3) of 1-methoxy-2-propanol and diacetone alcohol at room temperature: 117 g of dipentaerythrityl penta-/hexaacrylate (DPHA, manufacturer: Cytec), 4.7 g of Esacure One (manufacturer: Lamberti), 2.35 g of Darocur 4265 (manufacturer: BASF) and 0.25 g of BYK 333 (manufacturer: BYK). The second solution was added to the polymer solution while stirring. The coating composition obtained was stirred at room temperature and with shielding from direct incidence of light for another 3 h, dispensed and left to stand for 1 day. The yield was 665 g, the viscosity (23 C., DIN EN ISO 3219) was 1050 mPas, the solids content was 35% by weight and the calculated double bond density in the solids content of the coating material was about 5.1 mol/kg.

Example 2

Testing of the Solubility of Various ABS Products

[0097] For the testing, various commercially available ABS products were used. The solubility was tested in a mixture (2:3) of 1-methoxy-2-propanol (MP-ol) and diacetone alcohol (DAA). For the testing, the aim was a use-relevant concentration of 20% by weight of the polymer in each solvent. The dissolution test was conducted at 120 C. while stirring for 4 h. Then an intermediate result was registered. The solution was then allowed to cool to room temperature and the final result was registered.

TABLE-US-00001 Composition, % by wt. Poly- Acrylo- buta- MP-ol/DAA = 2:3 nitrile Styrene diene 120 C. 20 C. Novodur N 40.sup.# 43.sup.# 17.sup.# two phases two phases H950 Novodur N 23.sup.# 61.sup.# 16.sup.# homogeneous homogeneous H604 cloudy blend cloudy blend Magnum 24.sup.# 66.sup.# 10.sup.# homogeneous homogeneous 3404 cloudy blend cloudy blend Magnum 23.sup.# 62.sup.# 15.sup.# homogeneous homogeneous 3904 cloudy blend cloudy blend Magnum 24.sup.# 62.sup.# 14.sup.# homogeneous homogeneous 3616 cloudy blend cloudy blend Magnum 24.sup.# 65.sup.# 11.sup.# homogeneous homogeneous 8391 cloudy blend cloudy blend Magnum 22.sup.# 67.sup.# 11.sup.# homogeneous homogeneous 8434 cloudy blend cloudy blend .sup.#determination by IR spectroscopy; Novodur is a brand name of the manufacturer Styrolution; Magnum is a brand name of the manufacturer Styron.

[0098] In this way, it was possible to show that styrene-based ABS copolymers having an acrylonitrile content of less than 30% by weight have particularly good solubility in solvent mixtures of 1-methoxy-2-propanol and diacetone alcohol preferred in accordance with the present invention. Thus, ABS copolymers having an acrylonitrile content in the range of 20% by weight to 30% by weight, especially in the range of 22% by weight to 25% by weight, and especially in combination with a proportion of the polybutadiene in the range of 10% by weight to 16% by weight, are particularly preferred in the context of the present invention, especially in combination with a solvent mixture of 1-methoxy-2-propanol and diacetone alcohol.

Example 3

Coating of Films

[0099] Coating compositions according to Example 1 were applied to a backing film, for example Makrofol DE 1-1 (Bayer MaterialScience AG, Leverkusen, Germany), by means of a slot coater from the manufacturer TSE Troller AG. The layer thickness of the backing film was 250 m.

[0100] Typical application conditions here were as follows: [0101] web speed 1.3 to 2.0 m/min [0102] wet coating material applied 20-150 m [0103] air circulation dryer 90-110 C., preferably in the region of the TG of the polymer to be dried. [0104] residence time in the dryer 3.5-5 min.

[0105] The coating was effected roll to roll, meaning that the polycarbonate film was unrolled in the coating system. The film was conducted through one of the abovementioned application units and contacted with the coating solution. Thereafter, the film with the wet coating was run through the dryer. After leaving the dryer, the now dry coating was typically provided with a lamination film, in order to protect it from soiling and scratching. Thereafter, the film was rolled up again.

[0106] For the testing of the final properties of the product, the coated film, after leaving the dryer, can first be cured with a UV lamp and then provided with a lamination film.

Example 4

Testing of Blocking Resistance

[0107] The coated sides of the non-UV-cured films produced in Example 3 were covered with a lamination film of the GH-X 173 A type (Bischof+Klein, Lengerich, Germany) and weighted down with an aluminium sheet of dimensions 4.54.5 cm.sup.2 and a weight of 2 kg at about 23 C. for 1 h. Thereafter, the weight and the lamination film were removed and the surface of the coating was checked visually for changes.

TABLE-US-00002 TABLE 1 Blocking resistance of the coatings Coating Layer thickness on Blocking composition 250 m PC film resistance Example 1 8 m OK Example 1 13 m OK Example 1 18 m OK Example 1 24 m OK

Example 5

Forming of the Coated Films and Curing of the Coatings

[0108] The HPF forming tests were performed on an SAMK 360 system. The mould was electrically heated to 100 C. The film heating was undertaken by means of IR emitters at 240, 260 and 280 C. The heating time was 16 seconds. A film temperature of about 170 C. was attained. The forming was effected at a forming pressure of 100 bar. The forming mould was a heating/ventilation panel (HV panel).

[0109] The appropriate film sheet was fixed at an exact position on a pallet. The pallet passed through the forming station into the heating zone and resided therein for the time set (16 s). In the course of this, the film was heated in such a way that the film briefly experienced a temperature above the softening point; the core of the film was about 10-20 C. colder. As a result, the film was relatively stable when it is run into the forming station.

[0110] In the forming station, the film was fixed by closing the mould over the actual mould; at the same time, the film was formed over the mould by means of gas pressure. The pressure hold time of 7 s ensured that the film was accurately formed by the mould. After the hold time, the gas pressure was released again. The mould opened and the formed film was run out of the forming station.

[0111] The film was subsequently removed from the pallet and could then be cured with UV light.

[0112] With the mould used, radii down to 1 mm were formed.

[0113] The UV curing of the inventive coating was executed with an evo 7 dr high-pressure mercury vapour lamp (ssr engineering GmbH, Lippstadt, Germany). This system is equipped with dichroitic reflectors and quartz discs, and has a specific power of 160 W/cm. A UV dose of 2.0 J/cm.sup.2 and an intensity of 1.4 W/cm.sup.2 were applied. The surface temperature was to reach >60 C.

[0114] The UV dose figures were determined with a Lightbug ILT 490 (International Light Technologies Inc., Peabody Mass., USA). The surface temperature figures were determined with temperature test strips of the RS brand (catalogue number 285-936; RS Components GmbH, Bad Hersfeld, Germany).

[0115] Results for the durability of the coatings which have been crosslinked using the conditions specified can be found in Table 2.

TABLE-US-00003 TABLE 2 Chemical resistance and scratch resistance of the coatings Steel wool Coating compo- Pencil (manufacturer: sition/Layer Solvent hardness Rakso, No. 00) thickness on IP/MPA/X/EA/Ac 500 g 560 g/10 DH 250 m PC film 1 h/RT Mitsubishi G/H Haze Example 1/8 m 0/0/0/0/0 HB 6/0 1.36 Example 1/13 m 0/0/0/0/0 HB 7/18 2.82 Example 1/18 m 0/0/0/0/0 F-H 12/24 4.27 Example 1/24 m 0/0/0/0/0 F-H 10/5 7.66 Makrofol DE 1-1 0/5/5/5/5 3B 100/285 250 m

[0116] IP/MPA/X/EA/Ac stands for isopropanol, 1-methoxy-2-propyl acetate, xylene, ethyl acetate, acetone

[0117] RT stands for room temperature, about 23 C. here. Makrofol DE 1-1, 250 m is an uncoated polycarbonate film (manufacturer: Bayer MaterialScience).

[0118] As Table 2 shows, the inventive coating, even in a thin layer, distinctly improves the pencil hardness and scratch resistance of the film compared to the known properties of the polycarbonate. The coating also imparts a high solvent resistance. Compared to extruded ABS layers, the optical cloudiness (haze) of the ABS layer can be significantly reduced by appropriately thin coating, without losing the metallizability.

Example 6

Metallization (Galvanization)

[0119] The roughening of the surface of the ABS polymer was effected in a chromosulphuric acid etchant at a working temperature of 60 C. The dipping time was 10 minutes. It is assumed that, during this operation, a constituent of the ABS, the butadiene rubber, was leached out of the surface under oxidation, and that caverns in the microscopic range were formed in this way. Thereafter, the parts were rinsed vigourously with water and with sodium hydrogensulphite solution.

[0120] Palladium nuclei were inserted into the cavities formed by the processes described in DE 10 2004 026 489 B3 as an activator, which catalysed the subsequent chemical nickel-plating in the nickel bath (nickel sulphate; ammonia and sodium hypophosphite), as described in WO 2012/120007 A1, page 19 line 30 to page 20 line 4. Thus, a first thin, conductive nickel layer was obtained, which had very good mechanical interlocking with the plastic through the filling of the cavities, and had correspondingly good adhesion.

[0121] It was then possible to deposit further metal layers on this conductive layer by electrochemical means.

[0122] Formed films produced in the HPF process having the inventive coating, UV-cured and insert-moulded with thermoplastic, show a homogeneous, conductive nickel layer after the above treatment.

[0123] As the examples clearly showed, the coated films of the invention have scratch-resistant and solvent-resistant surfaces. In addition, these surfaces have good metallizability in the standard processes. Thus, the inventive coating composition and the inventive films are of excellent suitability for production of all kinds of mouldings with metallic surfaces, especially by film insert moulding processes.