EP2681044A1

EP2681044A1 - Composite elements

Info

Publication number: EP2681044A1
Application number: EP12706833.6A
Authority: EP
Inventors: Markus SCHÜTTE; Frank Fechner; Manfred Genz
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 2011-03-04
Filing date: 2012-02-29
Publication date: 2014-01-08
Also published as: RU2013144410A; JP2014508057A; BR112013019576A2; WO2012119892A1; ZA201307355B; CN103402754A; AU2012224772A1; IN2013CN06932A; AU2012224772B2; MX2013008937A; KR20140009451A

Abstract

The invention relates to a composite element containing a) a core made of a foam or a porous material, b) a top coat applied to the core a), and c) a film c) which differs from the top coat b) and is made of a thermoplastic material.

Description

composite elements

Description The invention relates to composite elements consisting of a core of foam or a porous material which is coated with plastic film.

Composite elements of a foam core surrounded by at least one cover layer are well known. They serve decorative purposes, but preferably the thermal insulation, for example on buildings or refrigerators.

Refrigerators are of great importance both in the commercial and private sectors. They are manufactured in most cases by a housing is made, in which a liquid mixture of a rigid polyurethane foam system is introduced, where it hardens to polyurethane.

In order to reduce the thermal conductivity so-called vacuum insulation panels, also referred to as VIP for short, have recently been used. These are usually introduced into the housing and foamed there with rigid polyurethane foam.

These procedures are cumbersome. In particular, when installing VIP a fixation is necessary. During transport and further handling as well as during the foaming of VIP, there is also the risk that they will be damaged, for example in the area of the welds.

A known method of wrapping substrates with a plastic film is the Permaskin process. This is described for example in WO 01/32400.

In this case, a molding in a chamber between two thermoplastic films at a distance from each other is arranged and fixed, then the air evacuated from the chamber and the film thereby pressed onto the surface of the molding while maintaining a vacuum between the films. In this case, the film is preferably heated, in particular to a temperature which is above the softening temperature of the film. Polyurethane rigid foams, as used in the field of heat / cold insulation, can in principle also be used as a substrate. This is described in the application WO 2008/135550. Double-coated rigid foam elements produced in this way exhibit increased load-bearing capacity, resistance to breakage, weather resistance and improved haptics and barrier action against the ingress of liquids. In the example cited, a rigid foam made of Neopolen is coated. It is also referred to that rigid polyurethane foams can be used. The rigid foams used have no further pre-applied functional layers. In the long term, however, moldings produced in this way have only insufficient insulating properties due to gas exchange processes. Furthermore, there is only a low resistance to mechanical stress as z. B. can occur when loaded with sharp or sharp objects.

It was the object of the present invention to provide composite elements that can be used for refrigerators and, where appropriate, allow the installation of VIP. They should be easy to manufacture, have a good mechanical strength and a low weight. It should also be possible to apply decorative layers.

The object could surprisingly be achieved by the subject matter of the invention, namely a composite element comprising a) a core of a foam or porous material, preferably a foam material, b) a cover layer applied to the core a), and c) one of the Cover layer b) different film made of a thermoplastic material.

An object of the invention are also the production of the composite elements and their use, in particular for the production of refrigerators.

The core a) is preferably selected from the group consisting of foams and porous materials.

The foams a) are preferably selected from the group comprising open-cell rigid polyurethane foams, closed-cell rigid polyurethane foams and melamine-formaldehyde foams.

The porous materials are preferably monolithic organic or inorganic polymers, also referred to below as monoliths. Among the monoliths, aerogels are particularly preferred. Aerogels are pore-containing gels that have been dried under supercritical conditions.

In a preferred embodiment of the invention, the core a) is a foam, in particular a rigid foam. Depending on the field of application of the composite elements, the foams are open-celled or closed-celled. The open-cell foams can be rigid polyurethane foams or melamine-formaldehyde foams, preferably rigid polyurethane foams and in particular open-cell rigid polyurethane foams. In the context of this invention, rigid foams are to be understood as meaning foams according to DIN 7726 (05/1982) which offer relatively high resistance to deformation under compressive stress (compressive stress at 10% compression or compressive strength according to DIN 53421, 06/1984,> 80 kPa). ,

The rigid polyurethane foams used as core a) are known. The open-cell foams which can be evacuated are also described in many cases, for example in EP 2072548. The foams can be used as core a) without further pretreatment. WO 2006/120183 describes that the foam can be compressed to improve the evacuability.

The melamine-formaldehyde foams are also known, for example from EP 74,593th Such products are marketed for example under the name of Basotect ^® from BASF SE.

Aerogels which can be used as core a) are described, for example, in WO 2007/065847.

The cover layer b) is preferably selected from the group containing barrier layers to gases, also referred to as diffusion barriers, where steam is also considered as gas, flame retardant layers and mechanically supporting layers.

The diffusion barriers are preferably films which are impermeable to water vapor and other gases.

The flame-retardant barriers are preferably thin-layered mats of mineral wool, alkali metal silicate layers, as described, for example, in WO 2006/040097, or layers of other known flame retardants, such as phosphorus, graphite, melamine or antimony trioxide.

The mechanically assisting coatings are preferably single-layer or multi-layer layers of cardboard, plastic or sheet metal which, if appropriate, may additionally be reinforced with an underlying honeycomb structure. The diffusion barriers used as cover layer b) are, as described, particularly preferably films.

In the simplest case, the cover layer b) may be a metal layer, aluminum foils being preferred. Preferably, cover layer b) is a composite film.

The cover layer b) is particularly preferably a multilayer composite film with a vapor-deposited or laminated metal layer. The metal layer of the film used as cover layer b) is particularly preferably made of aluminum. The cover layer b) is therefore in particular an aluminum or an aluminum composite foil.

The film used as cover layer b) itself consists in particular of polyester, polyvinyl chloride, polyolefins such as polyethylene or polypropylene, or polyvinyl alcohol.

In the field of vacuum insulation panels, aluminum composite foils b) are preferred for later sealing, consisting of an aluminum layer having a thickness of about 6 micrometers and a polyethylene layer or metallized high barrier laminates consisting of Al-vapor-deposited polyethylene or polyethylene terephthalate laminates Here, the thickness of the Al layer is only 30-100 nm. The metallized high barrier laminates consist of at least two Al layers for penetration of small molecules, e.g. Prevent water by extending the diffusion paths. However, the thickness of the metal layer should by no means exceed several micrometers in the case of thermal insulation applications of the composite elements, since otherwise the heat loss via thermal bridges, in particular through corner discharge, becomes too great.

In a preferred embodiment of the invention, the cover layer b) is a film which completely surrounds the core a). The cover layer b), as described, is particularly preferably a gas-impermeable film. In this embodiment of the invention, the core a) is preferably evacuated.

In this embodiment, the above-mentioned open-cell foams, such as open-cell rigid polyurethane foams and melamine-formaldehyde foams, are preferably used as core a). In this case, the core a) is completely enveloped by the cover layer b) and sealed gas-tight.

The film c) consists, as stated above, of a thermoplastic material. This is preferably selected from the group comprising polyvinyl chloride, styrene copolymers, polypropylene, polyvinylidene fluoride, thermoplastic polyurethane (TPU) and polymethyl methacrylate (PMMA) and mixtures of thermoplastic polyurethane and styrene copolymers.

Such films are known and described for example in WO2004 / 098878.

The films used c) preferably have a thickness between 50 and 750 μιη, preferably between 100 and 500 μιη and more preferably between 200 and 350 μιη. They can be prepared from the appropriate raw materials in granular form by the known methods for Foil production are produced. These may be blown films or cast films, with 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.

WO2008 / 135550 describes a specific embodiment of the film c). This consists of mixtures containing thermoplastic polyurethane (TPU) and an acrylonitrile-styrene-acrylic ester copolymer (ASA).

These mixtures (1) contain between 1% by weight and 40% by weight, preferably between 3% by weight and 30% by weight, particularly preferably between 5% by weight and 25% by weight (A) thermoplastic polyurethane, in particular based on aliphatic isocyanate and between 60% by weight and 99% by weight, preferably between 70% by weight and 97% by weight, particularly preferably between 75% by weight and 95% by weight (B) Acrylonitrile-styrene-acrylic ester copolymer (ASA) and / or acrylonitrile-ethylene homo or copolymer-styrene (AES) material, preferably acrylonitrile-styrene-acrylic ester copolymer (ASA), in each case based on the total weight of the mixture (1 ), preferably based on the sum of the weights of (A) and (B) in the mixture (1).

The ASA (B) is preferably based on:

(B1) 10 to 90 wt .-% of at least one graft rubber based on

(B1 1) 50 to 95 wt .-% of a graft base prepared with

(B1 1 1) 70 to 99.9 wt .-% of at least one alkyl acrylate

(B1 12) from 0.1 to 30% by weight of at least one at least bifunctional crosslinker,

(B1 13) 0 to 29.9% by weight of at least one further copolymerizable monomer,

(B12) 5 to 50% by weight of a graft shell based on

(B121) 65 to 90 wt .-%, preferably 70 to 80 wt .-% of at least one vinyl aromatic

monomers

(B122) from 10 to 35% by weight, preferably from 20 to 30% by weight, of at least one polar, copolymerisable unsaturated monomer, preferably acrylonitrile and / or methacrylonitrile,

(B123) from 0 to 25% by weight of at least one further copolymerizable comonomer, (B2) from 10 to 90% by weight of at least one copolymer prepared with the components (B21) from 60 to 85% by weight of at least one vinylaromatic monomer,

(B22) 15 to 40% by weight of at least one polar, copolymerisable unsaturated monomer,

(B23) 0 to 9 wt .-% of at least one comonomer, wherein the weights of (B1) and (B2) on the weight of (B), the weights of (B1 1 and B12) on the weight of (B1) , the weight data for (B1 1 1), (B1 12) and (B1 13) on the weight of the component (B1 1), (B121), (B122) and (B123) on the weight of (B12) and the weights of (B21), (B22) and (B23) are based on the weight of (B2).

AES materials consist of a matrix of polystyrene and acrylonitrile and optionally other monomers. With regard to the above information on preferred component B, AES materials differ from ASA materials in component B1 1, which in the case of AES materials can be based on ethylene homo- or copolymers. Suitable copolymers are, for example, C3- to C20-alpha-olefins, preferably C3- to C8-alpha-olefins. AES plastics are described in detail in a suitable composition as well as with regard to their preparation processes in the Handbook of Technical Polymer Chemistry, VCH Verlag, 1993, in particular page 490.

The TPU is preferably an aliphatic TPU, in particular hexamethylene diisocyanate-1, 6 (HDI) being used as the isocyanate.

In order to improve the adhesion between the films b) and c), an adhesive is preferably applied between the two films.

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

As one-component adhesives are usually polyurethane dispersions into consideration. These are known and commercially available, by way of example Jowapur® 150.50 of the company Jowat mentioned here. As two-component adhesives are usually combinations of polyurethane dispersions in question, for example Jowapur® 150.30 with isocyanates such as Jowat® 195.40 the company Jowat. However, adhesives based on acrylate or epoxy resin are also suitable for use.

The application of the adhesive can be carried out by the conventional methods such as painting, rolling or spraying, wherein the spraying is particularly preferred. A 20 minute

Drying time at room temperature following the adhesive application is sufficient for the systems described.

It is also possible that the adhesive is on one of the films b) and c), preferably on the film c). In particular, a two-layer film with an adhesion promoter based on elastomeric styrene-butadiene block polymers as described, for example, in WO-A 96/23823 and WO-A 97/46608 is suitable for coating rigid foams by the process according to the invention. When using the above-mentioned adhesive films can be dispensed with the use of an additional adhesive in the rule. Preferably, coextruded two-layer films consisting of a carrier layer such as polystyrene, Hl PS, ASA, polyamide, polypropylene, polyethylene or polyester and an adhesive layer of an elastomeric thermoplastic such as said styrene-butadiene block polymers used.

The composite elements usually have a dimension of DIN A4 format up to a few square meters. The layer thickness of the composite elements usually ranges from 50 to 2000 mm.

The production of composite elements is preferably carried out according to the method described in WO 01/32400.

Generally, this method includes the steps

Provision of a core, application of the layer b),

Arrangement of the coated core of foam or a porous material a) in a chamber with at least one film c) with a distance between the film c) and the coated core and its attachment,

- evacuation of air from the chamber,

Heating the plastic film c) and pressing the plastic film c) onto the surface of the coated core a),

- Removal of the composite element.

In many cases, the layer b) can be applied to the core a) in a separate process.

When using films as cover layer b), the application of the film used as cover layer b) can also be carried out immediately before introduction into the device for applying the film c).

It is also possible to apply the films b) and c) in the same device.

If the core a) is to be evacuated, the evacuation and the sealing with component b) can take place before the application of the film c).

Such a method would include the steps a1) providing a core of foam or a porous material a), b1) wrapping of the core with a film b), c1) evacuation of the core a) and airtight sealing of the film b), d1) arrangement of the coated core a) in one Chamber with at least one film c) with a distance between the film c) and the coated core and its attachment, e1) evacuation of the air from the chamber, f1) heating of the plastic film c) and gl) pressing the plastic film c) on the surface of the coated core a), h1) removal of the composite element.

In another embodiment of the method according to the invention, the evacuation of the core in the device for applying the film c) can take place.

Such a method would include the steps

A) providing a core of foam or a porous material a), B) wrapping the core with a film b),

C) Arrangement of the coated core a) in a chamber with at least one film c) with a distance between the film c) and the coated core and its attachment, D) evacuation of the air from the chamber,

E) airtight sealing of the film b),

F) heating of the plastic film c) and

G) pressing the plastic film c) onto the surface of the coated core a),

H) removal of the composite element. This embodiment of the method according to the invention is simpler and faster to carry out than the separate application of component b) to the core a). Between steps d) and e), an adhesive is preferably applied to the coated core and / or the film c).

Preferably, the film c) is heated above the softening point in step f).

Preferably, steps b) and c) are performed in the same device.

For the process according to the invention for two-sided coating of the core a) with a plastic film, it is essential that

the molded part is arranged and fastened in a capsule between films at a distance ratio,

- The air is evacuated from the capsule and

- The films are thereby pressed onto opposite surfaces of the molding, while maintaining a vacuum between the films. This prevents surface defects such as wrinkles or warping.

The film c) can be applied to one side of the composite element. Preferably, a film c) is applied to two opposite sides of the molded body. In this case, the film c) can be flush with the edge of the molding; In another embodiment of the invention, the film c) may be bent over the edge of the molding. In this case, the shaped body can also be completely surrounded by the film c).

The composite elements according to the invention can be used in many ways. So they can be used in construction, for example in the thermal insulation of buildings. The film c) serves both decorative purposes and the protection of the core a) from the weather.

Due to the different cover layers b) desired properties of the composite element, for example in relation to the flame retardant, can be adjusted specifically.

The moldings according to the invention can be used particularly advantageously in the production of refrigerators. The composite elements can be made in the form of the walls and doors of refrigerators. These components can then be assembled into the finished cooling unit. This considerably simplifies the manufacture of the refrigerators. Again, by the film c) the color and decor of the refrigerators can be varied. In addition, protection of the surface is achieved.

When using evacuated composite elements can continue to reduce the thermal conductivity of the refrigerators.

Claims

claims

1 . Composite element comprising a) a core made of a foam or a porous material, b) a cover layer applied to the core a), and c) a film c) made of a thermoplastic material other than the cover layer b).

2. Composite element according to claim 1, characterized in that the core a) a

Foam selected from the group comprising open-cell polyurethane rigid foams, closed-cell polyurethane rigid foams and melamine-formaldehyde foams.

3. Composite element according to claim 1, characterized in that the core a) is an airgel.

Composite element according to one of claims 1 to 3, characterized in that the cover layer b) is selected from the group containing barrier layers to gases, flame retardant layers and mechanically supporting layers.

Composite element according to one of claims 1 to 4, characterized in that the

Cover layer b) is a metal or a metal composite foil.

6. Composite element according to one of claims 1 to 5, characterized in that the cover layer b) is a multilayer composite film with a vapor-deposited or laminated metal layer.

7. Composite element according to one of claims 1 to 6, characterized in that the metal layer of the cover layer b) consists of aluminum.

8. Composite element according to one of claims 1 to 7, characterized in that the cover layer b) is a film which completely encloses the core a), and that the core a) is evacuated.

9. Composite element according to one of claims 1 to 8, characterized in that the film c) is mounted only on two opposite sides of the composite element.

10. Composite element according to one of claims 1 to 9, characterized in that between the cover layer b) and the film c) an adhesive is attached.

1 1. Composite element according to one of claims 1 to 10, characterized in that the material for the film c) is selected from the group consisting of polyvinyl chloride, styrene copolymers, polypropylene, polyvinylidene fluoride, thermoplastic polyurethane (TPU) and polymethyl methacrylate (PMMA) and mixtures of thermoplastic polyurethane and styrene copolymers.

12. A process for producing composite elements according to any one of claims 1 to 1 1, comprising the steps a1) providing a core of foam or porous material a), b1) wrapping the core with a film b), c1) Evacuation of the core a) and airtight sealing of the film b), d1) arrangement of the coated core a) in a chamber with at least one film c) with a distance between the film c) and the coated core and its attachment, e1) evacuation of the air from the chamber, f1) heating of the plastic film c) and gl) pressing of the plastic film c) on the surface of the coated core a), h1) removal of the composite element.

13. The method according to claim 12, characterized in that between the steps d1) and e1) an adhesive on the coated core and / or the film c) is applied.

14. The method according to claim 12 or 13, characterized in that the film c) is heated in step f1) to above the softening point. 15. The method according to any one of claims 12 to 14, characterized in that the steps b1) and c1) are made in the same device.

16. Use of the composite elements according to claim 1 to 1 1 for the production of refrigerators.