DE102014111415A1 - COATED SUBSTRATE AND METHOD FOR THE PRODUCTION THEREOF - Google Patents

Abstract

The invention relates to a method for producing a coated substrate by applying at least one coating agent to the substrate, which comprises a plastic which is selected from a group consisting of polyethylene (PE), polypropylene (PP), thermoplastic polyolefins (TPO) or mixtures thereof , with the following steps:
a - wet cleaning the untreated substrate;
b - applying a first coating agent;
c - intermediate drying or wet / wet treatment of the substrate coated with the first coating agent;
d - applying a second coating agent which is curable thermally and by actinic radiation (dual-cure);
e - heating or drying the coated substrate, wherein a polyaddition occurs;
f - irradiation of the coated substrate with actinic radiation, whereby a polymerization is triggered.

Description

Technical area

The present invention relates to a process for producing a coated substrate by applying at least one coating agent to the substrate comprising a plastic selected from a group consisting of polyethylene (PE), polypropylene (PP), thermoplastic polyolefins (TPO) or mixtures from this, as well as a corresponding plastic component.

The invention further relates to an apparatus for producing the coated substrate by applying at least one coating agent to the substrate.

State of the art

In the meantime, plastics account for between 15 and 20 percent by weight and are increasing in automotive engineering. These are often exterior and interior parts, which receive their corresponding visual, haptic and functional properties through a paint job. The increasing demands on quality and efficiency as well as resource efficiency, but also the global competitive pressure, require ever more economical, more sustainable and more flexible painting processes.

For example, the trend towards fewer coating steps, for example with filler-less coating systems, is also very popular with plastic attachments. The elimination of intermediate drying reduces energy consumption and at the same time reduces material consumption and solvent emissions. In addition, less production space is needed for the paint shop.

Corresponding paint solutions are available, inter alia, for glossy, injection-molded interior parts, for example decorative strips, of an ABS-PC blend (ABS: acrylonitrile-butadiene-styrene, PC: polycarbonate). The varnish provides a noble, high-gloss surface with a single-layer varnish structure.

In the automotive industry, mainly solvent-based and water-based paints are used for the coating of plastics. Solvent-based UV dual-cure systems have also been used for several years. They allow good matting and metallic shades. However, not all metallic shades can be produced with UV varnishes. High-gloss surfaces are produced with solvent-based UV dual-cure clearcoats in the structure with basecoats. Increasingly used for the plastic coating are both 100% UV clearcoats with piano lacquer optics and 2K dual-cure systems, the former having significantly higher chemical resistance properties. On many common plastic substrates such as ABS, SAN (styrene-acrylonitrile), PS (polystyrene) and ABS / PC (polycarbonate) good adhesion values are achieved without pretreatment. Otherwise, the adhesion properties can usually be optimized by activating the surface by flaming, plasma treatment or gas phase fluorination.

Dual-cure is the combined cure by heat and actinic radiation. Dual-cure coating materials and methods and devices for their curing with actinic radiation, in particular UV radiation, are known from the German patent applications DE 198 18 735 A1 . DE 42 15 070 A1 . DE 199 30 665 A1 . DE 199 30 067 A1 . DE 199 30 664 A1 . DE 199 24 674 A1 or DE 199 20 799 A1 known. They are used to produce coatings, in particular clearcoats and multicoat color and / or effect paint systems. The curing with actinic radiation is carried out mainly with UV radiation.

Usually, the binder components contained thereby have different functional groups which under appropriate conditions i.d.R. independently network with each other. Conventional dual-cure systems belonging to the prior art have radiation-curable and thermally curable groups, with particularly advantageous properties being achieved when using isocyanate and hydroxyl groups as thermally crosslinking functions.

EP 1 419 015 discloses a process for preparing coatings of thermally and actinic radiation curable coating compositions comprising: A) applying the coating materials to primed or unprimed substrates or to uncured, partially cured and / or fully cured enamel layers thereon, and B) the resulting layers the coating materials alone or together with the uncured and / or partially cured paint layers thermally and with curing with actinic radiation under an oxygen-depleted atmosphere.

Description of the invention

The object of the present invention is therefore to provide a simplified process for the preparation of a coated polyethylene (PE), polypropylene (PP), or thermoplastic polyolefin (TPO) containing plastic part, in which the number of painting steps and the cost of the painting reduced and at the same time the quality requirements for the paint are met.

Another object of the invention is to provide a corresponding coating apparatus and a coated plastic component obtained by the method.

• a – Nassreinigen des unbehandelten Substrats;
• b – Auftragen eines ersten Beschichtungsmittels;
• c – Zwischentrocknung oder Nass/Nass-Behandlung des mit dem ersten Beschichtungsmittel beschichteten Substrats;
• d – Auftragen eines zweiten Beschichtungsmittels, welches thermisch und durch aktinische Strahlung (Dual-Cure) härtbar ist;
• e – Erwärmen oder Trocknen des beschichteten Substrats, wobei eine Polyaddition erfolgt;
• f – Bestrahlen des beschichteten Substrats mit aktinischer Strahlung, wobei eine Polymerisation ausgelöst wird.

This object is achieved according to the method by the following steps:

• a - wet cleaning the untreated substrate;
• b - applying a first coating agent;
• c - intermediate drying or wet / wet treatment of the substrate coated with the first coating agent;
• d - applying a second coating agent which is curable thermally and by actinic radiation (dual-cure);
• e - heating or drying the coated substrate, wherein a polyaddition occurs;
• f - irradiation of the coated substrate with actinic radiation, whereby a polymerization is triggered.

With regard to the prior art, it was surprising and unforeseeable for the skilled worker that the object on which the present invention was based could be achieved with the aid of the method according to the invention. Namely, a particular advantage of the invention is that in the proposed method, the step of activating the substrate is entirely dispensed with.

This eliminates not only investment costs for the activation units when converting or upgrading existing paint shops, but also with the activation units (flame, plasma) associated fire protection measures and operating costs. The plastic substrate of polyethylene (PE), polypropylene (PP), or thermoplastic polyolefins (TPO) may be filled or unfilled.

On the plastic substrates of polyethylene (PE), polypropylene (PP), or thermoplastic polyolefins (TPO) can be provided without activation one-, two- and three-layer structures of dual-cure, 2K or 1K systems that meet the requirements of automotive manufacturers For example, for painted interior plastic components made of polypropylene, suffice.

In this case, the first coating agent in step b preferably contains at least one 1K or 2K hydroprimer or a solvent primer and / or UV-2K dual-cure primer.

Preferably, the second coating composition contains a hydrosol, preferably at least one UV-2K Dualcure hydro lacquer.

The combination of 1K or 2K solvent and / or hydroprimer and / or UV / 2K dualcure primer with UV / 2K Dualcure hydro lacquer systems on substrates of PP and TPO can be combined with ABS, ABS mod. PC, PC ABS, PC, PMMA for painted interior components. An activation unit, e.g. with flame or plasma is not required.

The process using UV / 2K Dualcure hydro lacquers makes it possible to produce matt and highly scratch-resistant lacquer systems with decorative, soft and comfort haptics for lacquered interior components.

Another advantage of such a coated plastic component u.a. in its perfume resistance, e.g. against essential oils and in its soft feel.

The combination of UV / 2K-Hydro-Dualcure clearcoats with 1K or 2K-solvent and hydroprimer and / or 2K-basecoats and / or UV / 2K-Dualcure hydrocoating systems also enables the generation of a wide product range with matt, semi-glossy or high-gloss surfaces.

The surface of the substrate or plastic is not activated according to the invention before the application of the first coating agent.

The conventional activation of plastic substrates by flame treatment, plasma processes, which are distinguished in low-pressure and atmospheric return plasmas, and gas phase fluorination can be used primarily for the cleaning of thin organic contaminants with simultaneous activation of the surface. This dual function is based on a physical and chemical reaction of the process. As a result, in addition to a clean surface, the increase of the surface tension or surface energy is achieved in order to create optimum conditions for the subsequent painting process.

In view of the method according to the invention, however, the simultaneous weakening of the plastic surface by the energy input during the activation seems to be just as crucial for the adhesion to the plastic substrates mentioned and is hardly considered so far. Analytical studies of the activation effects usually aim at the type and proportion of polar functional groups generated and the polarity achieved thereby, but disregard adverse degradation effects.

With PE, PP or TPO materials that are susceptible to polymer degradation, for example, it appears that activation can be dispensed with in order to ensure reliable adhesion of water-based coating systems, without the disadvantageous effect of a potential polymer degradation due to activation occurs.

Untreated PP shows pure C-C fractions of 91.25%, no -COOH content, in the XPS analysis (photoelectron spectroscopy). When flaming and ADP process (atmospheric pressure plasma method via nozzle), in particular the carboxyl groups (-COOH) increase very much. With 2K systems, known isocyanate side reactions take place in the direction of biurethane and urea groups via curing.

With ToF-SIMS (secondary ion mass spectrometry) such surface species are detectable, which then show differences to the untreated PP. The characterization and verification is carried out with coupled analyzes of XPS and ToF-SIMS.

Preferably, the first coating agent and / or the second coating agent contains at least one UV adsorbent, whereby the cured coating composition is effectively protected from UV radiation, in particular from sunlight. Sunlight-exposed varnish embrittles significantly slower and gives a longer shelf life.

The first coating agent and / or the second coating agent preferably contains at least one adhesion additive or a binder in order to improve the adhesion of the paint to the substrate. The adhesive additive or binder includes, for example, pigments and resins.

The plastic component with coated substrate obtained by a method described above, the first coating agent has a layer thickness of 10-30 .mu.m, preferably 15 .mu.m and / or the second coating agent has a layer thickness of 3-20 .mu.m, preferably 15-40 .mu.m, particularly preferably 25- 30 μm up. The second coating agent preferably has a layer thickness of from 3 to 20 μm for coating transparent substrates, in particular in conjunction with polycarbonate.

The device according to the invention for producing a coated substrate by applying at least one coating agent to the substrate which comprises a plastic which is selected from a group consisting of polyethylene (PE), polypropylene (PP), thermoplastic polyolefins (TPO) or mixtures thereof
a washing device for alkaline wet cleaning of the non-activated substrate;
a downstream adhesive water dryer with cooling zone;
a first painting device having an area for applying a first coating agent and a downstream second painting device having a region for applying a second coating agent, which comprises at least one heat-and-actinic radiation (dual-cure) hardening hydraulic paint, wherein
an intermediate drying and / or cooling zone is arranged between the first painting device and the second painting device; and
one of the first and second painting device downstream irradiation unit with actinic radiation.

The first coating device is preferably suitable for applying a first coating composition which contains at least one 1K or 2K hydroprimer or solvent primer and / or UV-2K dual-cure hydroprimer.

The second painting device is preferably suitable for applying a second coating composition which contains at least one UV-2K dual-cure hydro lacquer.

Preferably, the intermediate drying and / or cooling zone is designed for drying temperatures of 20-90 ° C.

Examples

Example paint structures:

The following examples show, in tabular form, various paint compositions consisting of hydro-primer as the first coating agent and basecoat or protective paint as the second coating agent on fluted and non-lubricated substrates. The coatings generally have a 1K Primer with UV Dualcure Topcoat or a 1K Primer with 2K Topcoat or UV-Hydro-Dualcure Topcoats.

This is followed by a paint inspection for scratch resistance and cream influences.

Untreated PP as a substrate shows the sole use of 1K-, 2K-, etc. Hydro lacquers insufficient underground adhesion, whereby the coatings can be completely removed from the substrate. Solvent-based paints also adhere less well without pretreatment. The cross-hatch tests yield characteristic values> GT 3 - GT 5 (very poor adhesion) for hydrocoats on PP without activation. On the other hand, the coating structures according to the invention show characteristic values ≦ GT 1-GT 0 (very good adhesion) in cross-hatch tests.

Further, paint adhesion characterization techniques such as DSC (differential scanning calorimetry) and scratch resistance tests (e.g., Vickers indentation hardness), use of general surface analysis such as IR spectroscopy, XPS and ToF-SIMS as described above are contemplated.

The effects achieved for UV / 2K-Dualcure topcoats are for decor, soft, comfort, any color scheme for interior, exterior, such as black, beige, red, silver, chrome, contrast anthracite, titanium, etc., matte, semi-gloss and piano black, Pianowhite and high gloss.

The optical effects for UV / 2K clearcoats are high gloss, semi-gloss and matt, common shades are possible.

Beispiel Hochglanzaufbauten:

The following tables show by way of example various combinations of first and second coating compositions on a substrate and their properties:

Example high gloss superstructures:

Short description of the figures

Below, individual embodiments of the painting of the invention will be described in more detail with reference to the drawings.

Show:

1a , b a schematic representation of two prior art painting devices for interior components in the wet / wet process ( 1a ) or with intermediate drying after priming ( 1b );

2 a schematic representation of a coating device according to the invention for plastic components in the wet / wet process;

3 a schematic representation of a painting device for plastic components with intermediate drying after priming;

4 a schematic representation of a painting device for plastic components in the wet / wet process for clearcoats;

5 a schematic representation of a painting device for plastic components with intermediate drying after priming for clearcoats.

1 shows two painting devices from the prior art for interior components of acrylonitrile-butadiene-styrene (ABS) copolymer, ABS-modified polycarbonate (PC), polycarbonate (PC), polymethyl methacrylate (PMMA) or mixtures thereof, in the wet / wet process, ie without Intermediate drying ( 1a ) in the dryer 8th , or with intermediate drying after priming in the first painting booth 6 (1b).

In this usual process sequence is according to 1a the Dekorsoftlack applied in two jobs wet in wet. There is no interim drying but only flash off for 7-10 min at 20 ° -26 ° C and 55 ± 5% relative humidity.

In the first paint booth 6 a primer with or without intermediate drying is applied to the primer. In the second paint booth 11 2K Hydro topcoat is used for interior paints, decor, soft and effect paints such as metallic, silver, chrome, etc.

In both cases, an alkaline wet cleaning takes place 1 as equivalent for two degreasing zones in two rinsing zones and subsequent rinsing with demineralised water. This is followed by a blow zone 2 with a stick water dryer 3 at. Conventionally, plastic components which are not made of acrylonitrile-butadiene-styrene (ABS) copolymer, ABS-modified polycarbonate (PC), polycarbonate (PC), polymethyl methacrylate (PMMA) or mixtures thereof are after the adhesive water dryer 3 an activation device (not shown) is provided. This is followed by a drive-through area 5 before the first 6 and second 11 Paint booth. Before the drive-through area 5 to the first paint booth 6 there is a first cooling zone 4 ,

In the usual process for two-layer construction, two Dekorsoftlacke wet in wet in the first 6 and second 11 Paint booth applied, with a control zone between the paint booths 10 is arranged, in which also the flash-off takes place. The second spray booth is an evaporation zone 12 with the final paint dryer 13 in which the fully coated substrate is dried at 80 ° C for 30 minutes. After passing through the final cooling zone 14 the now painted component enters the extension area 15 and continue to take part in the inspection 17 , as well as the parts task 18 and the assembly area 19 ,

In the process sequence according to 1b The Dekorsoftlack is in two jobs in the primer dryer 8th which has an evaporation zone 7 upstream, after priming in the first spray booth 6 (1b) between dried. Again, between the spray booths is a control zone 10 arranged, in which also the Flash-Off takes place. The second spray booth is an evaporation zone 12 with the final paint dryer 13 in which the fully coated substrate is dried at 80 ° C for 30 minutes.

After passing through the final cooling zone 14 the now painted component enters the extension area 15 and continue to take part in the inspection 17 , as well as the parts task 18 and the assembly area 19 ,

For PP / TPO substrates, no direct coatings without activation are possible in the prior art. Activation is also currently required for the use of aqueous primers. The painting systems described below represent a device-side solution to this problem.

2 shows a schematic representation of a coating device according to the invention for plastic components, in particular interior components containing polyethylene (PE), polypropylene (PP), thermoplastic polyolefins (TPO) or mixtures thereof in the wet / wet process. There is no intermediate drying 8th but only flash-off for 7-10 min at 20 ° -26 ° C and 55 ± 5% relative humidity.

The substrates used are PP, TPO without activation, optionally in combination with ABS, ABS mod., PC ABS, PC or PMMA. The process combination of 1K or 2K solvent and / or hydroprimer and / or UV / 2K dualcure primer with UV / 2K Dualcure hydro lacquer systems on substrates of PP and TPO can, also in combination with ABS, ABS mod. PC, PC ABS, PC, PMMA for all painted interior components. A costly and expensive activation unit, e.g. with flame or plasma is not required. This eliminates not only investment costs for the activation units when converting or upgrading existing paint shops, but also with the activation units (flame, plasma) associated fire protection measures and operating costs.

Even with the UV-Hydro Dualcure coating compositions according to the invention, the painting process can basically be "wet on wet" ( 2 ) or with intermediate drying in the primer dryer 8th ( 3 ) of the adhesion-promoting layer. In addition, a flash-off is performed for 7-10 min at 24 ° -26 ° C and 55 ± 5% relative humidity.

Unlike the attachment according to 1a , b is now the adhesion promoting UV / 2K Dualcure Hydroprimer / primer or a 2K Hydroprimer in the first spray booth 6 plotted.

In the second paint booth 11 UV / 2K Dualcure - Hydro basecoats are used for interior paints, decor, soft and effect paints such as metallic, silver, chrome, etc.

On the device side, the devices according to the invention additionally have a UV emitter unit compared to the prior art 16 on, which preferably in the plant area between the final cooling zone 14 and the extension area 15 is arranged.

The coating device according to the invention for producing a coated substrate is thus characterized in particular by the combination of a washing device for alkaline wet cleaning 1 of the non-activated substrate, a downstream adhesive water dryer 3 with cooling zone 4 , a first painting device 6 for applying a first coating agent and a downstream second painting equipment 11 for applying a second coating composition which has at least one dual-cure hydro-lacquer. This is an intermediate drying and / or evaporation zone 7 . 8th arranged between the first painting device and the second painting device and one of the second painting device 11 downstream irradiation unit 16 with actinic radiation.

4 shows, analogous to 2 , A schematic representation of a coating device in the wet / wet process for clearcoats.

In the case of UV-Hydro-Dualcure clearcoat systems, the painting process can basically also be "wet on wet" ( 4 ) or as a two-layer structure with intermediate drying 8th ( 5 ) of the adhesion-promoting layer. For intermediate drying 8th flash off is also carried out for 7-10 min at 24 ° -26 ° C and 55 ± 5% relative humidity.

In the first paint booth 6 An adhesion-promoting UV-Hydrobasislack in black, metallic-aqueous, etc. (interior paints, decor, comfort, soft and effect paints such as metallic, silver, chrome) is applied. Subsequently, in the second paint booth 11 the application of the UV Hydro Clearcoat, eg matt, semi-gloss or high gloss.

As UV lamps for UV / 2K Dualcure Hydrobasislacke (Decor, Soft, Comfort matted with effect and interior colors) are preferably iron-doped emitters, for clearcoat systems mercury-doped UV emitters in question.

LIST OF REFERENCE NUMBERS

1

 wet cleaning

2

 blow zone

3

 Dry-off oven

4

cooling zone 1

5

 Passage area before painting

6

spray booth 1

7

evaporation zone 1

8th

 Dryer primer

9

cooling zone 2

10

 control zone

11

spray booth 2

12

evaporation zone 2

13

 Dryer paint

14

cooling zone 3

15

 exit area

16

 UV lamp unit

17

 Parts removal / control

18

 parts task

19

 Assembly of the carriage

20

 Start end

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 19818735 A1 [0007]
• DE 4215070 A1 [0007]
• DE 19930665 A1 [0007]
• DE 19930067 A1 [0007]
• DE 19930664 A1 [0007]
• DE 19924674 A1 [0007]
• DE 19920799 A1 [0007]
• EP 1419015 [0009]

Claims (14)

 A method for producing a coated substrate by applying to the substrate at least one coating agent comprising a plastic selected from a group consisting of polyethylene (PE), polypropylene (PP), thermoplastic polyolefins (TPO) or mixtures thereof, marked by a - wet cleaning the untreated substrate; b - applying a first coating agent; c - intermediate drying or wet / wet treatment of the substrate coated with the first coating agent; d - applying a second coating agent which is curable thermally and by actinic radiation (dual-cure); e - heating or drying the coated substrate, wherein a polyaddition occurs; f - irradiation of the coated substrate with actinic radiation, whereby a polymerization is triggered. A method according to claim 1, characterized in that the first coating agent contains at least one hydroprimer or a solvent primer. Method according to one of claims 1 or 2, characterized in that the second coating agent includes a hydro lacquer. A method according to claim 3, characterized in that the hydro lacquer contains at least one UV-2K Dualcure hydro lacquer. Method according to one of claims 1 to 4, characterized in that the surface of the substrate is not activated before the application of the first coating agent. Method according to one of claims 1 to 5, characterized in that the first coating agent and / or the second coating agent comprise at least one UV adsorbent. Method according to one of claims 1 to 6, characterized in that the first coating agent and / or the second coating agent comprise at least one adhesion additive or a binder. Plastic component with coated substrate, obtainable by a method according to one of claims 1 to 7, characterized in that the first coating agent has a layer thickness of 10-30 .mu.m, preferably 15 .mu.m and / or the second coating agent has a layer thickness of 3-20 .mu.m, 15 -40 μm, preferably 25-30 μm. Plastic component with a coated substrate, obtainable by a method according to one of claims 1 to 8, characterized in that the second coating agent has a layer thickness of 3 to 20 microns for the coating of transparent substrates, in particular polycarbonate. Apparatus for producing a coated substrate by applying to the substrate at least one coating agent comprising a plastic selected from a group consisting of polyethylene (PE), polypropylene (PP), thermoplastic polyolefins (TPO) or mixtures thereof, marked by A washing device for alkaline wet cleaning of the non-activated substrate; - a downstream adhesive water dryer with cooling zone; A first painting device for applying a first coating agent and a downstream second painting device for applying a second coating agent, which comprises at least one heat and actinic radiation (dual-cure) hardening hydraulic paint, wherein An intermediate drying and / or evaporation zone is arranged between the first painting device and the second painting device; and - One of the second painting device downstream irradiation unit with actinic radiation. Apparatus according to claim 10, characterized in that the first painting device for applying a first coating composition which contains at least one 1K or 2K hydroprimer or solvent primer and / or UV-2K dual-cure hydroprimer is suitable. Device according to one of claims 10 or 11, characterized in that the second painting device for applying a second coating agent which contains at least one UV-2K Dualcure hydro lacquer and / or a 2K hydro lacquer, is suitable. Device according to one of claims 10-12, characterized in that the intermediate drying and / or evaporation zone is designed for drying temperatures of 20-90 ° C. Device according to one of claims 10-12, characterized in that the top coat drying and / or evaporation zone is designed for drying temperatures of 20-90 ° C.

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