EP2254938A1

EP2254938A1 - Molded composite article especially for furniture making

Info

Publication number: EP2254938A1
Application number: EP09720138A
Authority: EP
Inventors: Ingo Bellin; Carsten Schips; Klaus Hahn; Stephan WEINKÖTZ; Jochen Gassan; Jens Assmann
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 2008-03-10
Filing date: 2009-03-02
Publication date: 2010-12-01
Also published as: CN102015854B; BRPI0909437A2; KR20100139007A; CN102015854A; WO2009112392A1; RU2010141359A; US20110008608A1

Abstract

The invention relates to a molded composite article, especially for furniture making, containing a core layer and one or more additional layers, the core layer being a molded particle foam article which is obtained by welding pre-foamed foam particles from expandable, thermoplastic polymer granules containing 5 to 100% by weight of a SAN component (A) containing a1) 5 to 100% by weight (based on A) of a styrene/acrylonitrile copolymer, a2) 0 to 95 % by weight (based on A) of an a-methylstyrene/acrylonitrile copolymer and/or a-methylstyrene/styrene/acrylonitrile terpolymer, and 0 to 95% by weight of polystyrene (B) and 0 to 95% by weight of a thermoplastic polymer (C) which is different from (A) and (B).

Description

Composite molding in particular for furniture construction

description

The invention relates to a composite molding, in particular for furniture construction, comprising a core layer of a welded particle foam and at least one further layer, a method for its production, and the use of the composite molding in furniture construction.

Composite moldings for use in the furniture industry have long been known. They have, in addition to a core layer, further layers, for example cover layers, films or veneers, and optionally a stabilizing frame construction. If such composite moldings are to be used as lightweight components, it is desirable to have a core layer with the lowest possible density, which may, however, affect the further performance characteristics as little as possible.

German Utility Model DE 296 09 442 U1 describes a molded part, in particular for furniture or furniture parts, which contains a core layer of a paper honeycomb material, cover layers of, for example, chipboard or MDF (middle density fiber) sheets as cover layers and a frame construction. The disadvantage here is that the frame construction is imperative for stability reasons and that fittings are difficult to install, since the core layer is not solid.

LU-A 80594 describes a sandwich element with a honeycomb panel made of aluminum. In addition to economic disadvantages due to the use of expensive aluminum fittings are difficult to install here.

In German utility model DE 202005012486 U1 door blanks are described from a lightweight board with polyurethane (PU) core. A disadvantage is besides the high price of polyurethane the difficult recyclability of this substance.

Lightweight panels with a core of expanded polystyrene (EPS) are marketed by SWL-Tischlerplatten-Betriebs-GmbH (Langenberg / Westfalen, Germany). These plates also require a frame construction.

Although good results have already been achieved with the known lightweight building panels for furniture construction, there is nevertheless a broad scope for improvement, in particular as regards a combination of low density with good processability and favorable application properties. The object was therefore to provide a composite molding for furniture construction, which manages with the lowest possible density without a frame construction and can be easily coated with conventional technologies.

It has been found that composite moldings with particularly favorable properties are obtained when the core layer is formed as a particle foam molding and the underlying expandable thermoplastic polymer granules contain a styrene / acrylonitrile copolymer (SAN).

The invention therefore relates to a composite molding, in particular for furniture construction, comprising a core layer and one or more further layers, wherein the core layer is formed as a particle foam molding obtainable by welding prefoamed foam particles of expandable, thermoplastic polymer granules containing

5 to 100 wt .-% of a SAN component (A) containing

a1) from 5 to 100% by weight (based on A) of a styrene / acrylonitrile copolymer and a2) from 0 to 95% by weight (based on A) of an α-methylstyrene / acrylonitrile copolymer

Copolymers and / or α-methylstyrene / styrene / acrylonitrile terpolymers

0 to 95 wt .-% polystyrene (B) and

0 to 95 wt .-% of a different of (A) and B) thermoplastic polymers (C).

The composite moldings according to the invention can be processed more easily due to their good heat resistance compared to materials such as EPS, have a high pressure stability and require at densities between 50 and 100 g / l no frame construction. The particle foam used according to the invention can be welded into any shape, so that plates of any density and more complex spatial forms are easy to produce. In particular composite moldings containing α-methylstyrene / acrylonitrile (AMSAN) copolymers or terpolymers show a high heat resistance.

The invention further relates to the use of a composite molding according to the invention in furniture construction. The invention likewise provides a process for producing a composite molding according to the invention, comprising the steps

a) polymerization of styrene monomers, optionally α-methylstyrene and acrylonitrile or styrene, to give styrene copolymers (A) or polystyrene (B) ₁

b) degassing of the resulting polymer melt,

c) optionally mixing the remaining polymers of components (A), (B) and (C),

d) mixing the blowing agent and optionally additives into the polymer melt by means of static or dynamic mixer at a tem- perature of at least 150 ⁰ C, preferably 180-260 ⁰ C.

e) cooling of the propellant-containing polymer melt to a temperature at least 120 ⁰ C, preferably is 150 - 230 ° C,

f) discharge through a nozzle plate with holes whose diameter at

Nozzle outlet is not more than 1, 5 mm,

g) granulating the blowing agent-containing melt,

h) foaming and welding of the resulting granules into a molded part and

i) applying at least one further layer.

The particle foams used according to the invention for the core layer generally have a density of 5 to 500 g / l, preferably from 10 to 250 g / l, particularly preferably from 15 to 150 g / l.

The particle foam moldings obtained therefrom have a high degree of closed-cell content, with more than 60%, preferably more than 70%, particularly preferably more than 80%, of the cells of the individual foam particles being closed-celled as a rule.

Particularly preferably, the thermoplastic polymer granules used contain 50 to 100 wt .-% SAN component (A) and 0 to 50 wt .-% thermoplastic polymer C).

Preferred as SAN component (A) are mixtures containing

10 to 100 wt .-%, preferably 20 to 100 wt .-%, particularly preferably 40 to 100 wt .-%, in particular 50 to 100 wt .-% (each based on (A)) of the component (a1), and

0 to 90 wt .-%, preferably 0 to 80 wt .-%, particularly preferably 0 to 60 wt .-%, in particular 0 to 50 wt .-% (in each case based on (A)) of component (a2).

In a preferred embodiment, the SAN component contains 100% by weight of component (a1).

In a further preferred embodiment, the SAN component (A) contains 10 to 99, preferably 20 to 90, particularly preferably 40 to 80, in particular 50 to 80 wt .-% (each based on (A)) of component (a1) and 1 to 90, preferably 10 to 80, particularly preferably 20 to 60, in particular 20 to 50 wt .-% (in each case based on (A)) of the component (a2).

As styrene / acrylonitrile copolymer (SAN) (a1) SAN types are available from

(a 11) 7 to 45 wt .-%, preferably 17 to 35 wt .-%, based on (a1) acrylonitrile and

(a 12) 55 to 93 wt .-%, preferably 65 to 83 wt .-%, based on (a1) styrene

prefers.

Preferred as component (a2) are α-methylstyrene / acrylonitrile copolymers (AMSAN) (a21).

Preferred as AMSAN are copolymers (a21) obtainable from

(a211) 10 to 50 wt.%, preferably 17 to 43 wt.%, especially 27 to 33

Wt .-% (based on (a21)) acrylonitrile and

(a212) 50 to 90 wt .-%, preferably 57 to 83 wt .-%, particularly preferably 67 to 73 wt .-% (based on (a21)) α-methylstyrene. As α-methylstyrene / styrene / acrylonitrile terpolymers (a22) polymers are available from

(a221) 61 to 85% by weight (based on (a22) α-methylstyrene, (a222) 1 to 15% by weight (based on (a22) styrene and (a223) 14 to 34% by weight (relative to on (a22) acrylonitrile

prefers.

As polystyrene B), e.g. radically polymerized glassy polystyrene (GPPS), impact modified polystyrene (HIPS) or anionically polymerized polystyrene

(A-PS) or anionically polymerized impact-modified polystyrene (A-IPS).

In a preferred embodiment, the polymer granules according to the invention contain no polystyrene (B) (0 wt .-%). In a further preferred embodiment, the polymer granules according to the invention contain 1 to 95, preferably 10 to 80 wt .-% polystyrene (B), which reduce the maximum upper limits for the component (A) accordingly.

As thermoplastic polymer C) z. Acrylonitrile-butadiene-styrene (ABS), acrylonitrile-styrene-acrylic ester (ASA), polyamide (PA), polyolefins such as polypropylene (PP) or polyethylene (PE), polyacrylates such as polymethyl methacrylate (PMMA), polycarbonate ( PC), polyesters such as polyethylene terephthalate (PET) or polybutylene terephthalate (PBT), polyether sulfone (PES), polyether ketones (PEK), polyether sulfides (PES) or mixtures thereof. Preference is given to polyamide (PA).

In a preferred embodiment, the polymer granules according to the invention contain no (0 wt .-%) thermoplastic polymer (C).

In a further preferred embodiment, the poly mergin granules according to the invention contain 1 to 95, preferably 10 to 50 wt .-% of the thermoplastic polymer component (C), which reduce the maximum upper limits for the component (A) accordingly. Preferably, in this embodiment, the thermoplastic polymer component (C) is polyamide.

The composition of the polymer granules can be selected according to the desired properties of the particle foam molding. With the polymer mixtures used according to the invention, the heat resistance is improved, in particular when using AMSAN. In order to obtain the smallest possible granule particles in the preparation of the polymer granules used according to the invention, the strand expansion after the nozzle exit should be as low as possible. It has been shown that the strand expansion can be influenced inter alia by the molecular weight distribution of the SAN. The expandable SAN should therefore preferably have a molecular weight distribution with a polydispersity M _w / M _n of at most 3.5, particularly preferably in the range from 1.5 to 2.8 and very particularly preferably in the range from 1.8 to 2.6 exhibit.

Suitable compatibilizers are e.g. Maleic anhydride-modified styrene copolymers, epoxy group-containing polymers or organosilanes.

The particle foams used according to the invention can be prepared by customary methods known to the person skilled in the art, such as suspension polymerization.

For example, the polymer composition is melted in an extruder, optionally mixed with additives in the melt, then granulated and the granules are re-impregnated with blowing agent, preferably in aqueous suspension.

The impregnation with the blowing agent is preferably carried out in a pressure-resistant stirring vessel. It is preferably carried out in aqueous suspension or ethylene glycol, generally using from 90 to 350 parts, preferably 100 to 300 parts of water per 100 parts of polymer.

In order to prevent sticking of the polymer particles, it is expedient to work in the presence of known suspending aids, such as ultrafine alumina, basic magnesium carbonate, basic zinc carbonate, calcium carbonate, calcium phosphate, kieselguhr. Also suitable as dispersing agents are customary water-soluble polymers which greatly increase the viscosity of the aqueous phase, such as liquid phase (serum) of a styrene emulsion polymerization.

The dispersing aid is generally used in amounts of 0.1 to 10 parts, preferably 0.1 to 4.0 parts per 100 parts of water.

The dispersion is heated together with the propellant (for example pentane) to a temperature at which the polymer softens. This softening temperature is generally lower than the softening temperature of the pure polymer mixture in the presence of the blowing agent, which at least partially already diffuses into the polymer particles during the cold or during the heating process. The optimum temperature can be easily determined by a preliminary test. It is between 100 and 250 ⁰ C. The pressure during the impregnation is primarily determined by the vapor pressure of water and the blowing agent and is generally between 8 and 60 bar.

After reaching the softening temperature, the dispersion is preferably kept for some time, e.g. 1 to 100 minutes at this temperature. It is then cooled and the expandable polymer is separated from the suspension, optionally washed and dried.

Preferably, however, melt impregnation, i. the charging of the polymers with blowing agent in the melt stream, as described for example in WO 03/106544.

The polymer melt can also polymer recyclates of said thermoplastic see polymers, in particular styrene polymers and expandable styrene polymers (EPS) are admixed in amounts that do not significantly deteriorate their properties, usually in amounts of at most 50 wt .-%, in particular in amounts of 1 to 20% by weight.

The blowing agent-containing polymer melt generally contains one or more blowing agents in a homogeneous distribution in a proportion of 2 to 10 wt .-%, preferably 3 to 7 wt .-%, based on the propellant-containing polymer melt. Suitable blowing agents are the physical blowing agents commonly used in EPS, such as aliphatic hydrocarbons having 2 to 8 carbon atoms, alcohols, ketones, ethers, esters or halogenated hydrocarbons. Preference is given to using isobutane, n-butane, isopentane, n-pentane. As co-propellants, ethanol, acetone and methyl formate are preferred.

To improve the foamability, finely distributed inner water droplets can be introduced into the polymer matrix. This can be done for example by the addition of water in the molten polymer matrix. The addition of the water can be done locally before, with or after the propellant dosage. A homogeneous distribution of the water can be achieved by means of dynamic or static mixers.

As a rule, from 0 to 2, preferably from 0.05 to 1.5,% by weight of water, based on the total polymer component, is sufficient. Expandable polymer granules with at least 90% of the internal water in the form of inner water droplets with a diameter in the range of 0.5 to 15 microns form on foaming foams with sufficient cell count and homogeneous foam structure.

The added amount of blowing agent and water is chosen so that the expandable polymer granules have an expansion capacity α, defined as bulk density before foaming / bulk density, after foaming at most 125, preferably 25 to 100.

The expandable polymer granules used according to the invention generally have a bulk density of at most 700 g / l, preferably in the range from 590 to 660 g / l. When using fillers, depending on the type and amount of the filler, bulk densities in the range of 590 to 1200 g / l may occur.

The expandable polymer granules used in the invention optionally contain one or more additives such as nucleating agents, fillers (for example mineral fillers such as glass fibers), plasticizers, flame retardants, soluble and insoluble inorganic and / or organic dyes and pigments, e.g. IR absorbers, such as carbon black, graphite or aluminum powder. For example, the additives may be jointly or spatially separated from the polymer melt, e.g. be added via mixer or side extruder.

The total amount of additives is generally 0 to 30 wt .-%, preferably 0 to 20 wt .-%, based on the total weight of the polymer granules.

Particularly preferred for thermal insulation is the addition of graphite, carbon black, aluminum powder or an IR dye (e.g., indoaniline dyes, oxonol dyes or anthraquinone dyes).

In general, the dyes and pigments are added in amounts ranging from 0.01 to 30, preferably in the range of 1 to 5 wt .-%. For homogeneous and microdispersed distribution of the pigments in the styrene polymer, it may be expedient, in particular in the case of polar pigments, to use a dispersing assistant, for example organosilanes, polymers containing epoxy groups or maleic anhydride-grafted styrene polymers. Preferred plasticizers are low molecular weight styrene polymers or low molecular weight styrene copolymers, fatty acid esters, fatty acid amides and phthalates, which can be used in amounts of 0.05 to 10 wt .-%, based on the styrene polymer. To prepare the expandable polymer granules used according to the invention, the blowing agent is preferably mixed into the polymer melt. The process comprises the stages a) melt production, b) mixing c) cooling d) conveying and e) granulation. Each of these stages can be carried out by the apparatuses or apparatus combinations known in plastics processing. For mixing, static or dynamic mixers are suitable, for example extruders. The polymer melt can be taken directly from a polymerization reactor or can be produced directly in the mixing extruder or a separate melting extruder by melting polymer granules. The cooling of the melt can be done in the mixing units or in separate coolers. For example, pressurized underwater granulation, granulation with rotating knives and cooling by spray misting of tempering liquids or sputtering granulation may be considered for the granulation. Apparatus arrangements suitable for carrying out the method are, for example:

a) Polymerization Reactor - Static Mixer / Cooler Granulator b) Polymerization Reactor - Extruder - Granulator c) Extruder - Static Mixer - Granulator d) Extruder - Granulator

Furthermore, the arrangement may include side extruders for incorporation of additives, e.g. of solids or thermally sensitive additives.

The propellant-containing polymer melt is usually promoted with a temperature ranging from 140 to 300 ⁰ C, preferably in the range from 160 to 240 ⁰ C by the nozzle plate. Cooling down to the range of the glass transition temperature is not necessary.

The nozzle plate is heated at least to the temperature of the propellant-containing polymer melt. Preferably, the temperature of the nozzle plate is in the range of 20 to 100 ⁰ C above the temperature of the propellant-containing polymer melt. This prevents polymer deposits in the nozzles and ensures trouble-free granulation.

In order to obtain marketable granule sizes, the diameter (D) of the nozzle bores at the nozzle exit should be in the range from 0.2 to 1.5 mm, preferably in the range from 0.3 to 1.2 mm, particularly preferably in the range from 0.3 to 0 , 8 mm lie. To read Even after strand expansion, granule sizes of less than 2 mm, in particular in the range of 0.4 to 1.4 mm, can be set in a targeted manner.

The strand expansion can be influenced by the nozzle geometry in addition to the molecular weight distribution. The nozzle plate preferably has bores with a ratio LJD of at least 2, the length (L) designating the nozzle region whose diameter corresponds at most to the diameter (D) at the nozzle exit. Preferably, the ratio LJD is in the range of 3 to 20.

In general, the diameter (E) of the holes at the nozzle inlet of the nozzle plate should be at least twice as large as the diameter (D) at the nozzle outlet.

An embodiment of the nozzle plate has bores with conical inlet and an inlet angle α less than 180 °, preferably in the range of 30 to 120 °. In a further embodiment, the nozzle plate has bores with conical outlet and an outlet angle ß smaller than 90 °, preferably in the range of 15 to 45 °. In order to produce targeted granule size distributions of the styrene polymers, the nozzle plate can be equipped with bores of different exit diameter (D). The various embodiments of the nozzle geometry can also be combined.

A particularly preferred process for the preparation of the expandable polymer granules used according to the invention comprises the steps

a) polymerization of styrene, if appropriate α-methylstyrene monomers and acrylonitrile to give styrene copolymers A) or polystyrene B),

b) degassing of the resulting polymer melt,

c) optionally mixing with the remaining polymers of components (A), (B) and (C),

d) mixing the blowing agent and optionally additives into the polymer melt by means of static or dynamic mixers at a temperature of at least 150 ⁰ C, preferably 180-260 ⁰ C.

e) cooling of the propellant-containing polymer melt to a temperature at least 120 ⁰ C, preferably from 150 to 200 ⁰ C, f) discharge through a nozzle plate with holes whose diameter at the nozzle outlet is at most 1, 5 mm and

g) granulating the blowing agent-containing melt.

In step g), the granulation can be carried out directly behind the nozzle plate under water at a pressure in the range of 1 to 25 bar, preferably 5 to 15 bar.

Due to the polymerization in stage a) and degassing in stage b), a polymer melt is directly available for the blowing agent impregnation in stage c) and melting of polymers is not necessary. This is not only more economical, but also leads to expandable polymers with low monomer contents, since the mechanical shear in the melting of an extruder, which usually leads to a back-cleavage of monomers, is avoided. In order to keep the monomer content low, in particular below 500 ppm, it is furthermore expedient to keep the mechanical and thermal energy input as low as possible in all subsequent process stages. Shear rates below 50 / sec, preferably 5 to 30 / sec, and temperatures below 260 ^° C. and short residence times in the range from 1 to 20, preferably 2 to 10 minutes in stages c) to e), are therefore particularly preferred. Particular preference is given to using only static mixers and static coolers in the entire process. The polymer melt can by pressure pumps, z. As gear pumps, promoted and discharged.

A further possibility for reducing the monomer content and / or the residual solvents such as ethylbenzene is to provide in step b) a high degassing by means of entrainers, for example water, nitrogen or carbon dioxide, or to carry out the polymerization step a) anionically. The anionic polymerization not only leads to polymers with a low monomer content, but at the same time to low oligomer proportions.

To improve processability, the finished expandable polymer granules may be coated by glycerol esters, antistatic agents or anticaking agents.

The expandable, thermoplastic polymer granules used according to the invention are prefoamed in a first step preferably by means of hot air or steam to foam particles having a density in the range of 10 to 250 g / l and welded in a second step in a closed mold to the particle foam moldings used in the invention. In addition to the described core layer of a particle foam molding, the composite moldings according to the invention contain at least one further layer. The core layer is preferably connected to one or more further layers on at least two sides. Further preferably, the core layer is connected on all sides with one or more further layers.

In one embodiment of the invention, the structure of the composite molding consists of core layer, one or more cover layers and a surface layer.

In a further embodiment of the invention, the structure of the composite molding consists of a core layer and a surface layer.

Aminoplast resin films, in particular melamine films, PVC (polyvinyl chloride), glass fiber reinforced plastic (GRP), for example a composite of polyester resin, epoxy resin, or polyamide and glass fibers, prepregs, films, laminates, for example HPL (high pressure laminate ) and CPL (continuous pressure laminates), veneers, and metal, especially aluminum, coatings preferred.

Also preferred is a planking of the core layer according to the invention with chipboard or MDF (medium-density fiberboard), in particular thin chipboard and MDF with a thickness of <3mm

Particularly preferred are chipboard or MDF, which are surface-coated on one side, i. by painting, veneering, an applied film (melamine film) or laminate.

The surface layer is then pressed by methods known in the art with the core layer according to the invention.

For example, in the case of a veneer, the glue liquor can be applied to the core layer according to the invention, the veneer can be applied and pressed under temperature and pressure.

The preparation of the resin films or laminates used as a surface layer is generally carried out by the impregnation of papers, for example a) kraft papers with a basis weight between 50 to 150 g / m ² , b) printed decor papers with a basis weight between 50 to 150 g / m ² or c) overlay papers with a basis weight of 20 to 50 g / m ² , by means of aqueous resin solutions, whereby the papers are impregnated with the resin solution and / or the resin solution is spread or spread over the paper. Subsequently, the substrate is dried to a residual moisture / water content of 2 to 8%. It is usually a basis weight in the case of a) from 100 to 250 g / m ² and in the case of b) and c) of 50 to 150 g / m ² .

These dried substrates are then pressed onto the core layer according to the invention or optionally a layer applied between the core and surface layer, for example a functional layer. The pressing pressure is usually between 5 and 80 bar, the pressing time is generally less than one minute, typically 10 to 30 seconds, the pressing temperature is about 160 to 200 ⁰ C.

In the production of laminates, if necessary, several films are pressed together to form the laminate. A laminate usually consists of several layers of impregnated core paper, preferably 2 to 15 layers of core paper, one or more impregnated decorative and / or overlay papers as a surface layer and optionally one or more impregnated Gegenzugpapieren from, for example, Natronkraftpapieren.

The pressing pressure is typically below 100 bar, the pressing time is usually up to 90 minutes and the pressing temperature is usually at most 150 ⁰ C. The correspondingly produced laminates are then glued to the core layer according to the invention by methods known in the art.

For a paneling of the core layer according to the invention, for example, all materials are considered, which are made of wood strips, such as veneer or plywood, made of wood chips wood materials, such as chipboard or OSB boards (oriented beach boards, and coarse chipboard), and wood fiber materials such as LDF , MDF and HDF boards. These wood-based materials are produced from the corresponding wood particles with the addition of natural and / or synthetic binders by hot pressing. Preference is given to OSB, wood fiber and chipboard.

The planking takes place according to known, familiar to the expert methods.

As adhesives, for example, dispersion adhesives, such as white glue, epoxy resins, formaldehyde condensation resins, such as phenolic resins, urea-formaldehyde resins, melamine-formaldehyde resins, melamine-urea-formaldehyde resins, resorcinol and phenolic resorcinol resins, isocyanate adhesives, polyurethane adhesives and hot melt adhesives are used.

If one or more layers of the composite molding are made of materials capable of emitting formaldehyde, it is advantageous to subject the corresponding layer or composite molding to a polyamine treatment as described in WO 2007/082837.

The composite molding according to the invention can be surface-treated after application of the surface layer, for example by grinding and / or painting.

The composite molding according to the invention preferably has a density in the range from 50 to 300 g / l, particularly preferably 50 to 150 g / l, in particular 50 to 100 g / l.

The composite molding according to the invention preferably contains no frame construction.

The composite molding according to the invention is preferably used for the production of furniture, packaging materials, in building, drywall or interior work, for example as a laminate, insulation, wall or ceiling element.

The invention is explained in more detail by the examples without wishing to be limited thereby.

Examples:

Starting Materials:

Luran VLP: SAN with an acrylonitrile content of 35% and MW 145,800 (commercial product of BASF SE)

Luran VLS: AMSAN with an acrylonitrile content of 31% and MW 101 000 (commercial product of BASF SE)

Luwax AH3: Nucleating agent, polyethylene wax with melting point 110 - 1 18 ° C and MW 3500 (commercial product of BASF SE)

Examples 1 to 4 (polymer granules used according to the invention) In a twin-screw extruder from Leistritz ZSK 18 were 50 wt .-% Luran VLP with 50 wt .-% Luran VLS at 230 - 250 ⁰ C melted. Subsequently, the polymer melt was loaded with 4.5 or 5.0 wt .-% s-pentane, based on the polymer matrix. Thereafter, the polymer melt was homogenized in two static mixers and cooled to 190 ° C. 0.2 wt% Luwax AH3, based on the polymer matrix, was added via a side extruder to the blowing agent-laden main melt stream as nucleating agent. After homogenization via two further static mixers, the melt was cooled to 140 ⁰ C - 150 ⁰ C and extruded through a heated perforated plate (4 holes with 0.65 mm bore and 280 ⁰ C perforated plate temperature). The polymer strand was chopped off by means of underwater pelletization (underwater pressure = 12 bar, water temperature 60 ⁰ C), so that a blowing agent minipellets laden with narrow particle size distribution (d '= 1, 2 mm) was obtained.

Table 1 (Examples 1 to 4) Preparation of the granules used according to the invention

Example 5 Production of a Foam Sheet as Core Layer

In a twin-screw extruder from Leitritz ZSK 18 were 50 wt .-% Luran VLP with 50 wt .-% Luran VLS at 230 - 250 ⁰ C melted. Subsequently, the polymer melt was loaded with 5.0% by weight of s-pentane and additionally 1.0% by weight of ethanol, based on the polymer matrix. Thereafter, the polymer melt was homogenized in two static mixers and cooled to 190 ⁰ C. 0.2 wt% Luwax AH3, based on the polymer matrix, was added via a side extruder to the blowing agent-laden main melt stream as nucleating agent. After homogenization via two further static mixers, the melt was cooled to 140 ⁰ C - 150 ⁰ C and extruded through a heated perforated plate (4 holes with 0.65 mm bore and 280 ⁰ C perforated plate temperature). The polymer strand was knocked off by means of underwater granulation (12 bar underwater pressure, 60 ^° C. water temperature), so that a propellant loaded Minigranulat with narrow particle size distribution (d '= 1, 2 mm) was obtained.

The propellant-containing granules were prefoamed in an EPS prefoamer foam beads with different densities (20 - 120 g / l) and processed in an EPS molding machine at an overpressure of 0.5 bar to form parts.

Example 6 Production of a composite molding made of foam board, formica and

laminated veneer

A foam panel (blend of 50 wt .-% SAN (Luran ^® 3380) and 50 wt .-% AMSAN

(Luran KR2256 ^®)) was coated with a Formica and a wood veneer.

A Kauritleim was used as adhesive, the pressing conditions were 90 to 95 C and 100 atü.

In the obtained plate, conventional dowels (e.g., HUD-1 or HLD 2 of U.S. Pat

Hilti Deutschland GmbH or HM der Fischwerke GmbH & Co KG). In addition, the plates could be cut by means of a circular saw.

Example 7 Production of a composite molding made of foam board and beech veneer on both sides

A 20 x 20 cm ² large and 0.5 cm thick foam sheet according to Example 6 with a density of 70 g / l was on both sides with a 1, 5 mm thick beech veneer pasted (glue application 200 g / m ² Kauritleim (urea resin glue, BASF SE, Ludwigshafen, Germany), screw press, press time 120 min at room temperature).

The resulting composite moldings were tested for shear strength V20 and transverse tensile strength V20.

The achieved values of 0.33 N / mm or 0.29 N / mm correspond to the requirements of z. B. be placed on chipboard.

Example 8 Production of a composite molding of foam board and one-sided book veneer

A 20 x 20 cm ² large and 0.5 cm thick foam sheet according to Example 6 with a density of 70 g / l was stuck on one side with a 1, 5 mm thick beech veneer (Glue application 170 g / m ² Kauritleim, screw press, pressing time 120 min at room temperature).

Example 9 Production of a composite molding made of foam board and double-sided medium-density fiberboard (MDF)

A 20 x 20 cm ² large and 0.5 cm thick foam sheet according to Example 6 with a density of 70 g / l was on both sides with 3.5 mm thick MDF boards (Homanit GmbH & Co KG, Herzberg am Harz, Germany) pasted (Glue application 200 g / m ² Kauritleim, screw press, press time 120 min at room temperature).

Claims

claims

1. Composite molding, in particular for furniture, comprising a core layer and one or more further layers, wherein the core layer is formed as a particle foam molding obtainable by welding prefoamed foam particles of expandable, thermoplastic polymer granules containing

5 to 100 wt .-% of a SAN component (A) comprising a1) 5 to 100 wt .-% (based on A) of a styrene / acrylonitrile copolymer a2) 0 to 95 wt .-% (relative to A) of a α-methylstyrene / acrylonitrile copolymers and / or α-methylstyrene / styrene / acrylonitrile terpolymers;

0 to 95 wt .-% polystyrene (B) and

0 to 95 wt .-% of a of (A) and (B) different thermoplastic polymers (C).

2. A composite molding according to claim 1, wherein the core layer has a density in the range of 50 to 150 g / l.

3. Composite molding according to claim 1 or 2 having a density in the range of 50 to 300 g / l.

4. Composite molding according to one of claims 1 to 3, wherein the component (a2) of the particle foam consists of an α-methylstyrene / acrylonitrile copolymer (a 21).

5, composite molding according to one of claims 1 to 4, wherein the component (a2) of the particle foam comprises an α-methylstyrene / acrylonitrile copolymer (a 21), which consists of (a 211) 10 to 50 wt .-% of acrylonitrile and (a 212) 50 to 90 wt .-% α-methylstyrene is available.

6. Composite molding according to one of claims 1 to 5, wherein the component A of the particle foam

20 to 100 wt .-% (based on A) of a styrene / acrylonitrile copolymer (a1) and 0 to 80% by weight (based on A) of an α-methylstyrene / acrylonitrile copolymer (a2)

contains.

7. The composite molding according to any one of claims 1 to 6, wherein the component A of the particle foam 20 to 90 wt .-% (based on A) of a styrene / acrylonitrile copolymer (a1) and 10 to 80 wt .-% (based on A) ) of an α-methylstyrene / acrylonitrile copolymer (a2).

8. Composite molding according to one of claims 1 to 7, wherein the particle foam contains one or more additives from the group nucleating agents, fillers, plasticizers, flame retardants, inorganic and organic dyes and pigments.

9. Composite molding according to claim 8, wherein the particle foam contains graphite particles.

10. Composite molding according to one of claims 1 to 9, wherein at least one further layer of aluminum, high pressure laminates, Holzfumier, GRP, synthetic resin or PVC.

11. Use of a composite molding according to one of claims 1 to 10 in the Mo- bbe.

12. A method for producing a composite molding according to any one of claims 1 to 10, comprising the steps

a) polymerization of styrene monomers, optionally α-methylstyrene and

Acrylonitrile, to styrene copolymers (A) or polystyrene (B),

b) degassing of the resulting polymer melt,

c) optionally mixing the remaining polymers of components (A), (B) and (C), d) mixing the blowing agent and optionally additives into the polymer melt by means of static or dynamic mixers at a temperature of at least 150 ⁰ C, preferably 180-260 ⁰ C.

e) cooling of the propellant-containing polymer melt to a temperature at least 120 ⁰ C, preferably from 150 to 200 ⁰ C,

f) discharge through a nozzle plate with holes whose diameter at the nozzle outlet is at most 1.5 mm,

g) granulating the blowing agent-containing melt,

h) foaming and welding of the resulting granules into a molded part and

i) applying at least one further layer.