EP2155484A1

EP2155484A1 - Method for coating a molded foam part

Info

Publication number: EP2155484A1
Application number: EP08750050A
Authority: EP
Inventors: Christof MÖCK; Bernhard Vath; Lars Koppelmann
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 2007-05-08
Filing date: 2008-05-05
Publication date: 2010-02-24
Also published as: JP5356370B2; CN104669693A; US20100310844A1; JP2010529911A; CN101674932A; WO2008135552A1

Abstract

The invention relates to a method for coating a molded foam part with a plastic film, characterized in that a) the molded foam part is arranged in a capsule and fastened, the plastic film being interposed between the capsule wall and the molded foam part, b) the air in the chamber between the plastic film and the molded foam part is evacuated, c) thereby pressing the plastic film onto the molded foam part, and a vacuum is maintained during the pressing step. The invention also relates molded foam parts that are accessible for the first time by using said method and to the use of said molded foam parts.

Description

Process for coating a foam molding

description

The invention relates to a method for coating a foam molding with a plastic film, characterized in that

a) the foam molding is placed in a capsule and fastened, wherein the

Plastic film is mounted between the capsule wall and foam molding, b) the air in the chamber between the plastic film and foam molding is evacuated, c) the plastic film is thereby pressed onto the foam molding and during this pressing operation a vacuum is maintained.

Furthermore, the invention relates to coated foam moldings, which are accessible for the first time with this method and the use of the foam moldings.

For subsequent surface treatment of foam moldings, only expensive impregnation or impregnation processes have hitherto been described in the prior art (see US Pat. No. 6,607,817 and DE 100 11 388). Here foam layers are soaked in a solution of a hydrophobing or Oleophobierungs means, expressed the excess liquid in a roll mill and the foam layer finally dried.

Form, color and surface can hardly be changed at all with foam moldings afterwards. Straight look and properties such as haptics and weather resistance of the foam moldings often leave something to be desired.

Object of the present invention was therefore to find a method that allows a subsequent surface design of the foam moldings.

Surprisingly, it has now been found that the method mentioned at the beginning is outstandingly suitable for carrying out a subsequent surface design in the case of foam molded parts.

A comparable method for coating doors is already known from WO 01/032400. However, WO 01/032400 does not disclose whether and how foamed molded articles can be coated with this method. The method described in WO 01/032400 is hereby incorporated by reference. In particular, reference is made explicitly to the following process and device features of WO 01/032400, which are used individually or preferably in combination:

• Infrared heating, whereby the plastic film is preferably heated to 120 to 180 ⁰ C prior to pressing - blistering, tearing of the film or whitening of the film at the edges can thus be avoided;

• Separate chambers between foam molding and foil (chamber A), as well as between the film and the capsule wall (chamber B) - advantageous are the chambers

A and B simultaneously or preferably successively subjected to a vacuum. As a rule, a vacuum of less than 50 or preferably less than 30 mbar is set. As a result, buckling of the film or premature contact of the film with the foam molding is prevented. By relaxing the vacuum in chamber B to atmospheric pressure, the film is placed on the

Foam molding pressed while the vacuum in chamber A is still maintained;

• Simultaneous coating of the foam molding with foil on opposite sides - the easiest way to do this is to anchor the foam molding in a frame of wood, metal or plastic and center it in the center of the coating chamber by holding it to the head of the frame. Below the foam molding a further film is introduced, whereby a third chamber C between this film and the lower capsule wall is formed. Then, as already described above, all three chambers are subjected to a vacuum and the foam molding is coated on both sides after heating the film by opening the chambers A and C.

Coating of the plastic film or preferably of the foam molding with an adhesive, which allows the permanent adhesion of the film on the foam molding.

Surprisingly, the process according to the invention is suitable for coating semirigid and, in particular, flexible foams which hitherto were not accessible to a coating with plastic film. In the context of the invention, foams are understood as meaning foams according to DIN 7726. Under elastic

Foams are to be understood in the context of this invention foams according to DIN 7726, which after a short deformation by 50% of the thickness in accordance with DIN 53 577 after 10 minutes no permanent deformation over 2% of their initial thickness. This may be a soft-elastic, or a semi-hard elastic foam. A semi-hard elastic foam is understood to mean an elastic foam according to DIN 7726, which at 10% compression has a compressive stress of greater than 15 kPa and less than 80 kPa, measured in accordance with DIN 53421 / DIN EN ISO 604. A soft elastic foam is understood to mean an elastic foam according to DIN 7726 which has a compressive stress of 15 kPa measured at 10% compression, measured in accordance with DIN 53421 / DIN EN ISO 604.

In order to avoid deformations of the foam molding during the coating process, the molding is clamped in a makeshift frame throughout the process. If the frame is to remain in the finished coated foam molding, it is sprayed before coating with a corresponding adhesive, which is then activated in the coating process by the heat of the film. If the frame is to be removed after the coating, no adhesive is applied and the film is cut along the frame, preferably with a blade.

The adhesives used are preferably aqueous polyurethane-based systems. There are both one-component and two-component systems in question.

As one-component adhesives, PU dispersions come into consideration, for example Jowapur® 150.50 may be mentioned here. As two-component adhesives combinations of PU dispersions such as Jowapur® 150.30 with isocyanates such as Jowat® 195.40 come into question. As a rule, however, adhesives based on acrylate or epoxy resin are also suitable for use.

Likewise, a two-layer film with a primer based on styrene-butadiene-styrene copolymers on the bottom is suitable. When using the adhesive films, the use of an additional adhesive can generally be dispensed with.

Application of the adhesive may be by conventional methods such as brushing, rolling or spraying, with spraying being particularly preferred. A drying time of 20 minutes at room temperature following the adhesive application is sufficient in the systems described.

To produce the foam moldings of the invention are foams such as polyurethanes such as Elastopor ^® or Elastoflex® ^® from. Elastogran GmbH, polystyrene foams such as Styropor ^®, Neopor ^®, styrofoam Major ^® from. BASF SE, polypropylene foams such as Neopolen ^® from. BASF SE and melamine formaldehyde resin foams (short melamine resin foam Basotect ^® the brand.) made by BASF SE suitable. Melamine resin foams are particularly preferred. These flexible foams are generally open-cell foams. The foam moldings usually have sizes from DIN A4 to door size. The foam layers can be up to 6 m long and usually have a thickness of 50-2000 mm. Open-cell foams made of melamine-formaldehyde polycondensation plastics have excellent sound absorption capacity and excellent thermal insulation properties. In addition, such foamed plastics are characterized by fire safety and high heat resistance. The low volume weight complements this attractive property profile.

Therefore, such open-cell foams made of melamine-formaldehyde polycondensation, short melamine resin foam, used in construction and transportation with the aim of noise reduction and / or energy conservation.

In particular, the use in transportation, for example in the automotive industry, in rail vehicles and in shipbuilding entails that the melamine resin foam comes into contact with liquid media, for example in the form of lubricating oil, condensation or rainwater. Even in engine test benches and machine capsules, where the melamine resin foam is used for noise reduction, contamination with liquid media is possible.

Due to its open-cell character and the sorption behavior of the base product, the melamine resin, the foam can absorb large quantities of liquid. In direct contact with water sucks the melamine resin foam fully, such as a

Cleaning sponge. The water absorption is over 90 volume percent (vol .-%). The same applies to the contact with motor oil, although here, too, the intake due to the higher viscosity precipitates slightly lower. For example, an oil intake of about 80% by volume was found in direct contact with engine oil of the SAE viscosity class 10W.

By coating with a plastic film, the liquid absorption of the foam molding can be almost completely suppressed.

Furthermore, the weather resistance and the feel of foam moldings can be significantly improved by the coating with plastic films.

Suitable plastic films are, in particular, polyvinyl chloride, styrene copolymers, polypropylene, polyvinylidene fluoride, thermoplastic polyurethane (TPU) and polymethyl methacrylate (PMMA). Due to their weather resistance, styrene copolymers such as SAN, AMSAN and in particular ASA have proved suitable for outdoor applications in particular. For example, in the case of the ASA copolymer, the film may be modified by 0.5-30% by weight of a thermoplastic elastomer. Typical typical thermoplastic elastomer classes include: TPE-O (olefin-based thermoplastic elastomers, predominantly PP / EPDM), TPE-V (olefin-based cross-linked thermoplastic elastomers, predominantly PP / EPDM), TPE-U (urethane-based thermoplastic elastomers), TPE E (thermoplastic copolyester) TPE-S (styrene Block copolymers such as SBS, SEBS, SEPS, SEEPS, MBS) and TPE-A (thermoplastic copolyamides, eg PEBA). Such films can be used in various plain colors as well as printed surfaces. Furthermore, the surface can be structured by different embossing rollers during the extrusion of the film.

The films used have a thickness between 50 and 750 .mu.m, preferably between 100 and 500 .mu.m and particularly preferably between 200 and 350 .mu.m. They may be prepared from the corresponding granular precursors by the known film production processes, the extrusion process being preferred for cast film production.

To improve adhesive properties, the films may have been corona treated on one or both sides.

Due to the good heat and sound insulation as well as the soundproofing, the coated foam moldings can be advantageously used in the construction sector.

In particular, the moldings according to the invention come as ceiling and wall coverings in question.

Due to their low weight and simple surface design, the foam moldings are still very well suited for trade fair construction. Partitions, room dividers, stage designs can be created very easily in the lightweight construction.

Due to their thermal insulation behavior, the attractive surface and their high flexibility, the foam moldings according to the invention are outstandingly suitable for laminating, for example, cable ducts, roller shutter boxes and curtain suspensions. The moldings can be quickly adapted to the given requirements, for example, by cutting, Flexen, etc., and since they are flexible fit into the respective recess. This process is reversible and in many cases does not require additional support.

Open-celled foams are usually ideal for upholstering, for example, seating, mattresses, mats. As already described, a corresponding plastic film such as artificial leather can give an attractive appearance.

The padding can be used to increase safety in road traffic, for example in the field of pedestrian protection in vehicles. For example, front spoiler of vehicles can be equipped with the foam moldings. But also the lining of the walls of gymnasiums as well as garages, multi-storey car parks and crash barriers should be considered. At least at vehicle height, the wall can be reinforced accordingly to prevent damage to the vehicle when, for example, parking.

example

One-sided coating of a melamine resin foam layer with an ASA film

As one-sided substrate to be coated is a soft foam molding of Basotect ^®, a commercially available melamine-formaldehyde resin foam was BASF SE employed. The molding was 29 cm long, 21 cm wide and 5 cm high. In the first step, the adhesive was first applied. The adhesive used was an aqueous two-component system (consisting of binder and hardener) based on polyurethane, which was prepared immediately before application by mixing the two individual components. To obtain a homogeneous mixture, the mixture was stirred at room temperature for at least 3 minutes using a KPG stirrer. Subsequently, the adhesive was applied to one of the two surfaces of the molding with the aid of a Waisther-Pilot spray gun in an amount of about 80 g / m ² . Subsequently, the molding was allowed to dry for 20 minutes at room temperature. In the next step, the molded part was placed in a matching wooden frame (wall thickness 2 cm), which exactly enclosed the outer edges of the molded part. The molded part fixed in the frame was now fixed in the coating capsule, wherein the plastic film to be applied between capsule wall and molding was attached. The sprayed with adhesive surface of the molding showed it on the plastic film. The plastic film was a 250 micron thick, white pigmented film of Luran ^® S, the ASA commercially available from BASF SE - used copolymer. Subsequently, in the capsule, the two separate chambers between the foam molding and film (chamber A) and between the film and the capsule wall

(Chamber B) evacuated simultaneously. After reaching a vacuum of 25 mbar, the plastic film with the aid of IR lamps, which are mounted on the capsule wall above the film (in chamber B), heated to a temperature of 150 ⁰ C. After the temperature was reached, heating was stopped and chamber B was depressurized with air to atmospheric pressure, while at the same time the vacuum in chamber A was maintained. Due to the flooding of chamber B, an overpressure occurred, whereby the heated plastic film was pressed onto the surface of the molded part sprayed with adhesive. This ended the coating process. By heating with the IR emitters during the process, the adhesive on the surface of the molded part was also activated, whereby a very good adhesion between the adhesive and the plastic film was achieved already after completion of the process. After completion of the coating process, the coated molding was removed from the capsule removed and removed the outer edges enclosing wooden frame. The film overhanging the edges of the coated surface was manually removed with a sharp blade.

Claims

claims

1. A method for coating a foam molding with a plastic film, characterized in that

a) the foam molding is arranged and secured in a capsule, wherein the plastic film is mounted between the capsule wall and foam molding, b) the air is evacuated in the chamber between plastic film and foam molding, c) the plastic film thereby on the foam molding is pressed and during this pressing a vacuum of less than 30 mbar is maintained.

2. The method according to claim 1, characterized in that between the plastic film and the capsule wall, a second chamber exists, which is first also evacuated to less than 30 mbar and during the steps b) and / or c) is expanded to atmospheric pressure to the film to press on the foam molding.

3. The method of claim 1 for coating both sides of a foam molding, characterized in that the foam molding is placed between two plastic films and in steps b) and c), a vacuum is applied and maintained in the bounded by the two films chamber.

4. The method according to claim 3, characterized in that between the two plastic films and the respective capsule wall two further chambers exist, which are relaxed during the steps b) and / or c) to atmospheric pressure to the films on the opposite sides of the Foam molding partly press.

5. The method according to any one of claims 1 to 4, characterized in that an adhesive is applied to the foam molding and / or the plastic films prior to step b).

6. The method according to any one of claims 1 to 5, characterized in that the foam molding consists of a polyurethane and / or melamine resin foam.

7. The method according to claim 6, characterized in that the foam molding is introduced in step a) in a frame to ensure a uniform mounting of the film on the foam molding in steps b) and c).

8. One-side coated foam molding obtainable according to one of the methods 1, 2, 5 to 7.

9. Two-sided coated foam molding obtainable according to any one of methods 3 to 7.

10. The method according to any one of claims 1 to 9, characterized in that the films represent primer films that can be easily treated.

1 1. A coated foam molding according to claim 8 to 10, wherein the film of one or more plastics selected from the group consisting of polyvinyl chloride, styrene copolymers, polypropylene, polyvinylidene fluoride, thermoplastic polyurethane and polymethyl methacrylate and has a layer thickness between 100-500 microns.

12. Coated foam moldings according to claim 1 1, wherein the film consists of a fiber-reinforced plastic.

13. Coated foam moldings according to claim 1 1, wherein the film consists of SAN, AMSAN or ASA.

14. Use of the foam moldings according to claims 8 to 13 for heat or sound insulation or soundproofing.

15. Use of the foam moldings according to claims 8 to 13 for ceiling and wall coverings.

16. Use of the foam moldings according to claims 8 to 13 for partition walls.

17. Use of the foam moldings according to claims 8 to 13 for laminating example cable ducts, roller shutter boxes, curtain rails.

18. Use of the foam moldings according to claims 8 to 13 for upholstering, for example, seats, mattresses, mats, walls of gymnasiums, garages, parking garages or crash barriers.

19. Use of the foam moldings according to claims 8 to 13 in the field of pedestrian protection in vehicles.