EP2464692A1

EP2464692A1 - Light lignocellulosic materials having good mechanical properties

Info

Publication number: EP2464692A1
Application number: EP10742800A
Authority: EP
Inventors: Maxim Peretolchin; Stephan WEINKÖTZ; Günter Scherr
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 2009-08-13
Filing date: 2010-08-02
Publication date: 2012-06-20
Also published as: US20120138224A1; CA2770059A1; WO2011018373A1

Abstract

The invention relates to a method for producing a light lignocellulosic material having an average density in the range of 200 to 600 kg/m³, where: A) 30 to 95% by weight of lignocellulose particles; B) 1 to 25% by weight of expanded plastic particles having a bulk density in the range of 10 to 100 kg/m³; C) 3 to 50% by weight of a binding agent, selected from the group of aminoplast resin, phenol formaldehyde resin, and organic isocyanate having at least two isocyanate groups and optionally D) additives are mixed and pressed under increased temperature and increased pressure, characterized in that the expanded plastic particles are obtained from expandable plastic particles by expanding, and the expanded plastic particles thus obtained are further used for producing the light lignocellulosic material without further intermediate steps.

Description

The present invention relates to a process for producing a light lignocellulose-containing substance having an average density in the range from 200 to 600 kg / m ³ , in which, in each case based on the lignocellulose-containing substance:

A) 30 to 95% by weight of lignocellulose particles;

B) I to 25% by weight of expanded plastic particles having a bulk density in the range from 10 to 100 kg / m ³ ,;

C) 3 to 50 wt .-% of a binder selected from the group consisting of aminoplast resin, phenol-formaldehyde resin, and organic isocyanate having at least two isocyanate groups and optionally

D) mixes additives and then pressed under elevated temperature and under elevated pressure, characterized in that the expanded plastic particles are obtained from expandable plastic particles by expanding and the resulting expanded plastic particles without further intermediate steps for

Production of the light lignocellulosic substance be reused.

The sum of components A), B), C) and optionally D) adds up to 100%. Furthermore, the present invention relates to a process for producing a multilayered lignocellulosic material as defined in the claims.

Lignocellulosic materials, for example wood-based materials, in particular multilayer wood-based materials, are a cost-effective and resource-saving alternative to solid wood and have great significance, in particular in furniture construction

Laminate flooring and obtained as building materials. Serve as starting materials

Wood particles of different thickness, z. B. wood chips or wood fibers

different woods. Such wood particles are usually pressed with natural and / or synthetic binders and optionally with the addition of further additives to plate or strand-shaped wood materials.

In order to achieve good mechanical properties of the wooden materials, these are produced with a density of about 650 kg / m ³ and more. Users, especially private consumers, are often too heavy with wood-based materials of this density or the corresponding parts, such as furniture. The industrial demand for lightweight wood-based materials has therefore risen steadily in recent years, especially since pick-up furniture has gained in popularity. Furthermore, the rising price of oil, which leads to a constant increase in, for example, transport costs, causes an increased interest in light goods

Wood materials.

In summary, lightweight wood-based materials are of great importance for the following reasons: Lightweight wood-based materials make the end-user easier to handle the products, for example when packing, transporting, unpacking or constructing the furniture.

Light wood-based materials lead to lower transport and packaging costs, and material costs can be saved in the production of lightweight wood-based materials.

Light wood-based panels can, for example, when used in means of transport lead to lower energy consumption of these means of transport. Furthermore, using light wood materials, for example, material-consuming

Decorative parts, such as currently come in vogue thicker worktops and cheeks in kitchens, are offered at a lower cost.

There are many proposals in the state of the art for reducing the density of wood-based materials.

As light wood materials, which are available by constructive measures, for example, tube chipboard and honeycomb panels are mentioned. Due to their special properties, tube chipboards are mainly used in the

Production of doors as inner layer for use.

A disadvantage of the honeycomb panel, for example, the too low screw extraction resistance, the difficulty attaching fittings and the difficulties in edging.

Furthermore, there are proposals in the prior art to reduce the density of the wood materials by adding glue or to the wood particles.

In CH 370229 lightweight and pressure-resistant molding materials are described, which consist of wood chips or fibers, a binder and serving as a filler porous plastic. For the preparation of the molding materials are

Wood chips or fibers with binder and foamable or partially mixed foamable plastics, and pressed the resulting mixture at elevated temperature. The blowing agent content of the filler polymers is expressed

CH 370229 not.

WO 02/38676 describes a process for the preparation of light products in which 5 to 40 wt .-% of foamable or already foamed polystyrene with a

Particle size of less than 1 mm, 60 to 95 wt .-% lignocellulosic material and binder mixed and pressed at elevated temperature and pressure to the finished product. The propellant content of the filler polymer WO 02/38676 does not express.

In WO 2008 / 046890A (BASF SE), WO 2008/046891 A (BASF SE) and

WO 2008/046892 A (BASF SE) describes, among other things, light wood-containing substances which contain, for example, wood chips or fibers, a binder and a porous plastic serving as filler. For the production of wood-containing substances are, for example, the wood chips or fibers with binder and

mixed foamable or partially foamable plastics, and pressed the resulting mixture at elevated temperature. WO 2008/046890 A, WO 2008/046891 A and WO 2008/046892 A are silent on the blowing agent content of the filler polymers or their precursors.

The disadvantage of the prior art is summarized in that for the production of foamed fillers (synonymous with expanded

Plastic particles) used precursor polymers (synonymous with expandable plastic particles) relatively large amounts (usually more than 5 wt .-% based on the expandable plastic particles) of propellant, for example

Pentane (mixtures), included. Most propellants, such as pentane, are highly flammable.

This has the disadvantage that complex technical measures must be taken to the formation of flammable or even explosive propellant / air mixtures in the production of light lignocellulosic, preferably light wood-containing substances or equivalent, usually multilayer,

Lignocellulose materials, preferably multilayer wood materials to prevent. Usually, the expanded plastic particles, for example polystyrene, with pentane (mixtures) as blowing agent, stored for several days in special silos with ventilation, so that the propellant, for example, pentane (mixture), can escape. This relatively long storage prevents continuous production of the light lignocellulosic, for example woody, substances or corresponding, usually multilayer, lignocellulosic materials, for example wood-based materials, and can lead to a reduction of the production capacity for the light ones

lignocellulose-containing substances, for example wood-containing substances or equivalent, usually multi-layered, lignocellulosic materials, such as wood materials lead.

The object of the present invention was to show plastic particles for light lignocellulosic materials and light lignocellulosic materials, which can be prepared and handled without risk of fire and which controlled with relatively simple process expand and quickly reuse but they lignocellulosic, preferably wood-containing, substances and Lignocellulosic materials, preferably wood materials, lower density lead, with at least equally good mechanical strength and good processing properties, such as Bekantbarkeit, such as those of the prior art.

The mechanical strength can be determined, for example, by measuring the

Transverse tensile strength according to EN 319 can be determined.

The TKH-Merkblatt (Technical Commission on Wood Adhesives in the Industrial Adhesives e.V.) of January 2006, Table 10 can be used to assess the edgebandability or sticking of edges on chipboard. Furthermore, the swelling value of the light lignocellulosic materials, preferably wood-based materials, should not be adversely affected by the reduced density.

The object was achieved by a process for producing a light lignocellulose-containing substance having an average density in the range from 200 to 600 kg / m ³ , in which, in each case based on the lignocellulosic substance:

A) 30 to 95% by weight of lignocellulose particles;

B) 1 to 25% by weight of expanded plastic particles having a bulk density in the range of 10 to 100 kg / m ³ ;

C) 3 to 50 wt .-% of a binder selected from the group consisting of aminoplast resin, phenol-formaldehyde resin and organic isocyanate having at least two isocyanate groups and optionally

Production of the light lignocellulosic substance be reused.

The terms lignocellulose, lignocellulose particles or lignocellulose-containing substance are known in the art. Lignocellulosic material, lignocellulosic particles or lignocellulosic particles are, for example, straw or wood parts, such as wood plies, wood strips, wood chips, wood fibers or wood dust, wood chips, wood fibers and wood dust being preferred. The lignocellulose-containing particles or lignocellulose particles may also be derived from wood fiber-containing plants, such as flax, hemp.

Starting materials for wood parts or wood particles are common

Thinning woods, industrial woods and used woods as well as wood fiber plants.

The preparation of the desired lignocellulose-containing particles, for example wood particles, by known methods, see for example M. Dunky, P.

Niemt, Holzwerkstoffe und Leime, pp. 91-156, Springer Verlag Heidelberg, 2002.

Preferred lignocellulose-containing particles are wood particles, particularly preferably wood fibers, such as those used for the production of MDF and HDF boards.

Highly suitable lignocellulose-containing particles are also flax or hemp particles, particularly preferably flax or hemp fibers, as can be used for the production of MDF and HDF boards.

The lignocellulosic, preferably wood-containing substance may contain the usual small amounts of water (in a usual small fluctuation range); This water is not included in the weight of the present application.

The weight specification of the lignocellulose particles, preferably wood particles, relates to dried in a conventional manner known to those skilled in the art

Lignocellulose particles, preferably wood particles.

The weight of the binder refers to the

Aminoplastkomponente in the binder on the solids content of the corresponding component (determined by evaporation of water at 120 ⁰ C, within 2 h after, for example, Günter Zeppenfeld, Dirk Grunwald, adhesives in the wood and furniture industry, 2nd edition, DRW-Verlag , Page 268) and with regard to the isocyanate, in particular the PMDI, to the isocyanate component per se, that is, for example, without a solvent or emulsifier.

The light lignocellulose-containing, preferably wood-containing substances according to the invention have an average density of 200 to 600 kg / m ³ , preferably 200 to 575 kg / m ³ , particularly preferably 250 to 550 kg / m ³ , in particular 300 to 500 kg / m ³ . The transverse tensile strength of the light lignocellulose-containing, preferably wood-containing materials according to the invention or preferably of the multilayer lignocellulose materials according to the invention, particularly preferably multilayer wood-based materials, is generally in the range from 0.1 N / mm ² to 1.0 N / mm ² , preferably 0.3 to 0 , 8 N / mm ² , more preferably 0.4 to 0.6 N / mm ² .

The determination of the transverse tensile strength is in accordance with EN 319.

Suitable multilayered lignocellulosic materials, preferably multilayer wooden materials, are all materials which are made of wood veneers, preferably with an average density of the wood veneers of 0.4 to 0.85 g / cm ³ , for example veneer boards or plywood boards or laminated veneer lumber (LVL ).

As multilayered lignocellulosic materials, preferably multilayered

Wood-based materials are particularly preferably all materials which are made of lignocellulosic chips, preferably wood chips, preferably with an average density of the wood chips of 0.4 to 0.85 g / cm ³ , for example chipboard or OSB boards, and wood fiber materials such as LDF , MDF and HDF boards.

Particleboard and fiberboard, in particular chipboard, are preferred.

The average density of the lignocellulose particles, preferably the wood particles of component A) is generally 0.4 to 0.85 g / cm ³ , preferably 0.4 to 0.75 g / cm ³ , in particular 0.4 to 0.6 g / cm ³ . For the production of wood particles any wood species comes into question; For example, spruce, beech, pine, larch, linden, poplar, ash, chestnut or fir wood are very suitable; spruce and / or beech wood, in particular spruce wood, are preferred. The dimensions of the lignocellulose particles, preferably wood particles, are not critical and, as usual, depend on the lignocellulose material to be produced, preferably wood-based material, for example the abovementioned wood-based materials, such as chipboard or OSB. Komponete B) are expanded plastic particles, preferably expanded thermoplastic particles.

Such expanded plastic particles are usually obtained as follows: Compact plastic particles containing an expansible medium (also called "propellant") are expanded by the action of heat energy or pressure change (often referred to as "foamed"). This stretches The propellant, the particles increase in size and cell structures arise.

This expansion is generally carried out in conventional frothing devices, often referred to as "prefoamers." Such prefouchers may be stationary or mobile.

The expansion can be carried out in one or more stages. As a rule, in the single-stage process, the expandable plastic particles are readily expanded to the desired final size.

In general, in the multi-stage process, the expandable plastic particles are first expanded to an intermediate size and then expanded in one or more further stages over a corresponding number of intermediate sizes to the desired final size.

The above-mentioned compact plastic particles, also referred to herein as "expandable plastic particles", contain, in contrast to the expanded ones

Plastic particles, usually no cell structures.

These expanded plastic particles have little, if any, propellant content.

The resulting expanded plastic particles are without further

Intermediate steps continue to be used to produce the lignocellulose-containing substance.

Usual measures to ensure production, such as feeding the expanded plastic particles in so-called buffer container, which compensate for example Dosierungsschwankungen the expanded plastic particles, or even temporary storage, for example for propellant reduction, the expanded plastic particles and the mixing of component B) with other additives, such as components A. ), C) or optionally D) are not intermediate steps in the sense of this invention. Typical measures for propellant reduction of expanded plastic particles are, for example, prolonged storage, generally 12 hours to several days, of the expanded plastic particles in open vessels or in vessels with, for the propellant, permeable walls. This storage generally takes place at ambient temperature, for example 20 to 30 ^° C.

"Propellant reduction" herein is the demonstrable reduction of propellant by conventional analytical methods (for example gas chromatography). Concentration in the collective of freshly expanded plastic particles with

progressing time.

The term "propellant reduction" is intended to include here also the other changes of the expanded plastic particles occurring during prolonged storage of the expanded plastic particles, for example shrinkage or aging.

Conventional measures for propellant reductions can by the

inventive method can be avoided.

In a well-suited process, the expanded plastic particles become continuous to produce the light lignocellulosic material

on. That means expanding the expandable

Plastic particles to expanded plastic particles and their further use, preferably conveyed into the plant for the production of the light lignocellulosic material, proceed in a temporally practically uninterrupted process chain.

In the promotion of the expanded plastic particles in the plant for the production of the light lignocellulose-containing material, the conveying path for the expanded plastic particles may have one or more buffer containers in the main or shunt.

The plant for the production of the light lignocellulose-containing substance usually also comprises a mixing device in which the component B) is mixed with the other components.

In a preferred embodiment, the above-described expanding ("foaming") of the expandable plastic particles at the site of production of the light lignocellulosic, preferably light wood-containing material is carried out and the resulting expanded plastic particles, for example without further

Measures for propellant reduction, directly reused, for example, directly into the apparatus for producing the light lignocellulosic material, preferably light wood-containing substance, fed. "Locally" means nearby, for example, within a radius of about 200

Meters or in the vicinity of the device in which the light wood-containing material is produced and optionally further processed.

In a further preferred embodiment, the above-described

Expanding ("foaming") of the expandable plastic particles carried out at the site of production of the light lignocellulosic, preferably light wood-containing material in a mobile Aufschäumvorichtung and the thus obtained expanded plastic particles, for example, without further measures to

Propellant reduction, directly reused, for example, directly into the apparatus for producing the light lignocellulosic material, preferably light wood-containing material, fed.

"Locally" herein means nearby, for example, within about 200 meters, or adjacent to the device in which the light wood-containing material is produced and optionally further processed.

"Mobile frothing device" herein means that the frothing device can be easily assembled and disassembled, or, preferably, is mobile, for example, mounted on a wheeled vehicle (eg truck) or rail vehicle Mobile frothing devices as a truck body are used, for example, by HIRSCH Servo AG, Glanegg 58, A-9555 Glanegg Suitable polymers which are based on the expandable or expanded plastic particles are all polymers, preferably thermoplastic polymers, which can be foamed, which are known to the person skilled in the art.

Well-suited such polymers are, for example, polyketones, polysulfones, polyoxymethylene, PVC (hard and soft), polycarbonates, polyisocyanurates,

Polycarbodiimides, polyacrylimides and polymethacrylimides, polyamides, polyurethanes, aminoplast resins and phenolic resins, styrene homopolymers (hereinafter also referred to as "polystyrene" or "styrene polymer"), styrene copolymers, C 2 -C 10 -olefin homopolymers, C 2 -C 10 -olefin copolymers and polyesters.

Preference is given to the preparation of said olefin polymers, the

1-alkenes, for example, ethylene, propylene, 1-butene, 1-hexene, 1-octene.

The expanded plastic particles of component B) have a bulk density of from 10 to 100 kg / m ³ , preferably from 15 to 90 kg / m ³ , particularly preferably from 20 to 80 kg / m ³ , in particular from 40 to 80 kg / m ³ . The bulk density is usually determined by weighing a volume filled with the bulk material.

Expanded plastic particles B) are generally used in the form of spheres or beads having an average diameter of advantageously 0.25 to 10 mm, preferably 0.4 to 8.5 mm, in particular 0.4 to 7 mm.

Expanded plastic particle beads or beads B) advantageously have a small surface area per volume, for example in the form of a spherical or elliptical particle.

The expanded plastic particle balls B) are advantageously closed-cell. The open cell density according to DIN-ISO 4590 is usually less than 30%. If component B) consists of different types of polymers, ie polymer types which are based on different monomers (for example polystyrene and polyethylene or polystyrene and homopolypropylene or polyethylene and homopolypropylene), these may be present in different weight ratios, which, however, according to the current state of the art Knowledge, not critical.

In addition, the polymers, preferably the thermoplastics which underlie the expandable or expanded plastic particles B), may contain additives, for example UV stabilizers, antioxidants, coating agents, water repellents, nucleating agents, plasticizers, flameproofing agents, soluble and insoluble inorganic and / or organic compounds Dyes, pigments, and athermane particles, such as carbon black, graphite or aluminum powder, together or spatially separated as

Add additives. For expanding the expandable plastic particles it is possible to use all blowing agents known to the person skilled in the art, for example aliphatic C 3 - to C 10 -hydrocarbons, such as propane, n-butane, isobutane, n-pentane, isopentane, neopentane-cyclo-pentane and / or hexane and its isomers, Alcohols, ketones, esters, ethers or halogenated hydrocarbons.

The content of blowing agent in the expandable plastic particles is in the range of 0.01 to 7 wt .-%, preferably 0.01 to 4 wt .-%, particularly preferably 0.1 to 4 wt .-%, most preferably 0, 5 to 3.5 wt .-%, each based on the propellant-containing expandable plastic particles.

Preferably, styrene homopolymer (also referred to simply as "polystyrene" herein) and / or styrene copolymer is used as the sole plastic component in component B. Such polystyrene and / or styrene copolymer can be prepared by any polymerization method known to those skilled in the art, see, for example, Ullmann's Encyclopedia, Sixth Edition, 2000 Electronic Release or Plastics Handbook 1996, Volume 4 "Polystyrene", pages 567 to 598. The production of the expandable polystyrene and / or styrene copolymer is generally carried out in a conventional manner by suspension or by extrusion.

In the suspension polymerization is styrene, optionally with the addition of further comonomers in aqueous suspension in the presence of a conventional

Suspension stabilizer polymerized by means of radical-forming catalysts. The propellant and optionally other additives can thereby in the Be submitted to polymerization or be added to the approach in the course of polymerization or after completion of the polymerization. The resulting peribular, impregnated with blowing agent, expandable styrene polymers are separated after the polymerization from the aqueous phase, washed, dried and sieved.

In the extrusion process, the blowing agent is mixed for example via an extruder in the polymer, conveyed through a nozzle plate and granulated under pressure to particles or strands.

As blowing agent for the preparation of the expandable polystyrene and / or

Styrene copolymer can be used all blowing agents known to those skilled in the art and already mentioned above, for example aliphatic C3 to C10 hydrocarbons, such as propane, n-butane, isobutane, n-pentane, isopentane, neopentane cyclo-pentane and / or hexane and its isomers, Alcohols, ketones, esters, ethers or halogenated hydrocarbons.

The propellant is preferably selected from the group consisting of n-pentane, isopentane, neopentane and cyclopentane. It is particularly preferred to use a commercial pentane isomer mixture of n-pentane and isopentane.

The content of blowing agent in the expandable polystyrene or styrene copolymer is in the range of 0.01 to 7 wt .-%, preferably 0.01 to 4 wt .-%, particularly preferably 0.1 to 4 wt .-%, most preferably 0 , 5 to 3.5 wt .-%, each based on the propellant-containing expandable polystyrene or styrene copolymer.

The content of C3 to Cio hydrocarbons as blowing agent in the expandable polystyrene or styrene copolymer is in the range of 0.01 to 7 wt .-%, preferably 0.01 to 4 wt .-%, particularly preferably 0.1 to 4 wt. -%, most preferably 0.5 to 3.5 wt .-%, each based on the propellant-containing expandable polystyrene or styrene copolymer.

The content of blowing agent selected from the group consisting of n-pentane, isopentane, neopentane and cyclopentane, in expandable polystyrene or

Styrene copolymer is in the range of 0.01 to 7 wt .-%, preferably 0.01 to 4 wt .-%, particularly preferably 0.1 to 4 wt .-%, most preferably 0.5 to 3.5 wt. -%, respectively, based on the propellant-containing expandable polystyrene or styrene copolymer. The content of propellant selected from the group consisting of n-pentane,

Isopentane, neopentane and cyclopentane, in the expandable polystyrene is in the range of 0.01 to 7 wt .-%, preferably 0.01 to 4 wt .-%, particularly preferably 0.1 to 4 wt .-%, most preferably 0.5 to 3.5 wt .-%, each, based on the blowing agent-containing expandable polystyrene.

The preferred or (most) particularly preferred ones described above

Expandable styrene polymers or expandable styrene copolymers have a relatively low content of blowing agent. Such polymers are also referred to as "low blowing agent." A well-suited process for producing low-blowing expandable polystyrene or expandable styrene copolymer is described in US 5,112,875, which is incorporated herein by reference.

Furthermore, the styrene polymers or styrene copolymers, additives, for example UV stabilizers, antioxidants, coating agents, water repellents, nucleating agents, plasticizers, flame retardants, soluble and insoluble inorganic and / or organic dyes, pigments, and athermane particles such as carbon black, graphite or aluminum powder , be added together or separately as additives.

As described, styrene copolymers can also be used. These styrene copolymers advantageously have at least 50% by weight, preferably at least 80% by weight, of copolymerized styrene. As comonomers come z. B. α-methyl styrene, nuclear halogenated styrenes, acrylonitrile, esters of acrylic or methacrylic acid of alcohols having 1 to 8 carbon atoms, N-vinylcarbazole, maleic acid (anhydride),

(Meth) acrylamides and / or vinyl acetate into consideration. Advantageously, the polystyrene and / or styrene copolymer in copolymerized form contain a small amount of a chain splitter, d. H. a compound having more than one, preferably two, double bonds, such as divinylbenzene, butadiene and / or butanediol diacrylate. The branching agent is generally used in amounts of from 0.0005 to 0.5 mol%, based on styrene.

Preference is given to styrene polymers or styrene copolymers having a

Molecular weight in the range of 70,000 to 400,000 g / mol, more preferably 190,000 to 400,000 g / mol, most preferably 210,000 to 400,000 g / mol used.

Mixtures of different styrene (co) polymers can also be used.

Highly suitable styrene homopolymers or styrene copolymers are glass clear polystyrene (GPPS), impact polystyrene (HIPS), anionically polymerized polystyrene or impact polystyrene (A-IPS), styrene-α-methylstyrene copolymers, acrylonitrile

Butadiene-styrene polymers (ABS), styrene-acrylonitrile (SAN), acrylonitrile-styrene-acrylic ester (ASA), methyl acrylate-butadiene-styrene (MBS), methyl methacrylate-acrylonitrile-butadiene- Styrene (MABS) polymers or mixtures thereof or with polyphenylene ether (PPE) used.

Particular preference is given to using a styrene homopolymer having a molecular weight in the range from 70,000 to 400,000 g / mol, particularly preferably 190,000 to 400,000 g / mol, very particularly preferably 210,000 to 400,000 g / mol.

For the production of expanded polystyrene as component B) and / or expanded styrene copolymer as component B), in general the expandable styrene homopolymers or expandable styrene copolymers are expanded by heating to temperatures above their softening point, for example with hot air or preferably with steam and / or pressure change (often referred to as "foamed"), as described for example in Kunststoff Handbuch 1996, Volume 4 "polystyrene", Hanser 1996, pages 640-673 or US 5,112,875.

The expandable polystyrene or expandable styrene copolymer is usually in a conventional manner by suspension or by means of polymerization

Extrusion process as described above available.

During expansion, the propellant expands, the polymer particles increase in size and cell structures are formed.

The expansion can be carried out in one or more stages. In general, in the one-step process, the expandable polystyrene particles or expandable styrene copolymer particles are readily expanded to the desired final size.

In general, in the multi-stage process, the expandable

Polystyrene particles or expandable Styrolcopolymerteilchen initially expanded to an intermediate size and then expanded in one or more further stages over a corresponding number of intermediate sizes to the desired final size.

Preferably, the expansion is carried out in one stage. The expandable polystyrene particles (styrene homopolymer particles) or expandable styrene copolymer particles contain, in contrast to the expanded ones Polystyrene particles or expanded Styrolcopolymerteilchen, usually no cell structures.

The content of blowing agent in the expanded styrene homopolymer (polystyrene) or expanded styrene copolymer, preferably expanded Styrolhomopolymerisat, is in the range of 0 to 5.5 wt .-%, preferably 0 to 3 wt .-%, particularly preferably 0 to 2.5 wt. -%, most preferably 0 to 2 wt .-%, each based on the expanded polystyrene or expanded styrene copolymer.

0 wt .-% means herein that no propellant can be detected by the usual detection methods.

The expanded polystyrene particles thus obtained or expanded

Styrene copolymer particles are used without further intermediate steps for the production of the light lignocellulose-containing substance.

Usual measures to ensure production, such as feeding the expanded polystyrene particles or expanded Styrolcopolymerteilchen in so-called buffer tank, which, for example, metering variations of the expanded polystyrene or expanded Styrolcopolymerteilchen

compensate, or even short caching for example to

Propellant reduction, the expanded polystyrene particles or expanded Styrolcopolymerteilchen and the mixing of the expanded polystyrene or expanded Styrolcopolymerteilchen with other additives, for example

Components A), C) or optionally D) are not intermediate steps in the sense of this invention.

Conventional measures for reducing the blowing agent of expanded polystyrene particles or expanded styrene copolymer particles are, for example, longer storage, in the

Generally 12 hours to several days, of the expanded polystyrene particles or expanded styrene copolymer particles in open vessels or vessels with permeable walls for the propellant. This storage generally takes place at ambient temperature, for example 20 to 30 ^° C.

"Propellant reduction" herein is the detectable reduction in propellant concentration in the collective of freshly expanded polystyrene particles or expanded styrenic copolymer particles with time as measured by conventional analytical techniques (for example, gas chromatography).

The term "propellant reduction" is intended here but also the other, with prolonged storage of the expanded polystyrene or expanded Styrolcopolymerteilchen, occurring changes in the expanded polystyrene or expanded styrene copolymer particles, for example, shrinkage or aging, include.

Conventional measures for reducing the blowing agent can be avoided by the method according to the invention.

In a well-suited process, the expanded polystyrene particles or expanded styrene copolymer particles are continuously used to make the light lignocellulosic material. That is, expanding the expandable polystyrene particles or expandable styrenic copolymer particles into expanded polystyrene particles or expanded styrenic copolymer particles and their further use, preferably delivery to the plant for producing the lignocellulosic material, in a virtually uninterrupted time

Expire process chain.

The plant for producing the lignocellulose-containing substance usually also comprises a mixing device in which the component B) with the other

Components is mixed. In the promotion of expanded polystyrene particles or expanded

Styrolcopolymerteilchen in the plant for the production of light

lignocellulosic material may be the route of the expanded

Polystyrene or expanded Styrolcopolymerteilchen contain one or more buffer containers in the main or shunt.

In a preferred embodiment, the above-described expanding ("foaming") of the expandable polystyrene particles or expandable

Styrolcopolymerteilchen carried out at the place of production of the light lignocellulosic, preferably light wood-containing material and the resulting expanded polystyrene or expanded Styrolcopolymerteilchen without further measures, for example, for propellant reduction, directly

further used, for example, directly into the apparatus for producing the light lignocellulosic material, preferably light wood-containing material, fed. "Locally" herein means nearby, for example, within about 200 meters, or adjacent to the device in which the light wood-containing material is produced and optionally further processed.

In a further preferred embodiment, the above-described

Expanding ("foaming") the expandable polystyrene particles or

expandable Styrolcopolymerteilchen carried out at the place of production of the light lignocellulosic, preferably light wood-containing material in a mobile foaming and the resulting expanded Polystyrene particles or expanded styrenic copolymer particles, for example, without further measures for propellant reduction, directly used further, for example fed directly into the apparatus for producing the light lignocellulosic material, preferably light wood-containing material. "Locally" herein means nearby, for example in the vicinity of about 200 meters, or in the vicinity of the device in which the light wood-containing material is produced and optionally further processed.

"Mobile frothing device" herein means that the frothing device can be easily assembled and disassembled, or, preferably, is mobile, for example, mounted on a wheeled vehicle (eg, truck) or railcar.

Mobile foaming devices as a truck body are described for example by the company HIRSCH Servo AG, Glanegg 58, A-9555 Glanegg.

The expanded polystyrene or expanded styrene copolymer advantageously has a bulk density of from 10 to 100 kg / m ³ , preferably from 15 to 90 kg / m ³ , particularly preferably from 20 to 80 kg / m ³ , in particular from 40 to 80 kg / m ³ .

The expanded polystyrene or expanded styrene copolymer is advantageously in the form of spheres or beads having an average diameter in the range of 0.25 to 10 mm, preferably in the range of 0.4 to 8.5 mm, in particular in the range of 0.4 to 7 mm inserted.

The expanded polystyrene or expanded styrene copolymer spheres advantageously have a small surface area per volume, for example in the form of a spherical or elliptical particle.

The expanded polystyrene or expanded styrene copolymer spheres are advantageously closed-cell. The open cell density according to DIN-ISO 4590 is usually less than 30%.

Usually, the expandable polystyrene or expandable styrene copolymer or the expanded polystyrene or expanded styrene copolymer has an antistatic coating. As antistatic agents, the usual and common in the art substances can be used. Examples are N, N-bis (2-hydroxyethyl) -Ci 2 -C 18 -alkylamines,

Fatty acid diethanolamides, choline ester chlorides of fatty acids, C 12 -C 20 -alkyl sulfonates, ammonium salts. Suitable ammonium salts contain on nitrogen in addition to alkyl groups 1 to 3 hydroxyl-containing organic radicals. Suitable quaternary ammonium salts are, for example, those having on the nitrogen cation 1 to 3, preferably 2, identical or different alkyl radicals having 1 to 12, preferably 1 to 10 carbon atoms, and 1 to 3, preferably 2, the same or

containing various hydroxyalkyl or hydroxyalkylpolyoxyalkylene radicals bonded, with any anion, such as chloride, bromide, acetate, methyl sulfate or p-toluenesulfonate.

The hydroxyalkyl and hydroxyalkyl-polyoxyalkylene radicals are those which are formed by oxyalkylation of a nitrogen-bonded hydrogen atom and are derived from 1 to 10 oxyalkylene radicals, in particular oxyethylene and oxypropylene radicals.

Particular preference is given to using as antistatic agent a quaternary ammonium salt or an alkali metal salt, in particular the sodium salt of a C 12 -C 20 alkanesulfonate or mixtures thereof. The antistatic agents can generally be added both as a pure substance and in the form of an aqueous solution.

The antistatic agent can be used in the process of producing polystyrene or

Styrene copolymer be added analogously to the usual additives or applied after the preparation of the polystyrene particles as a coating.

The antistatic agent is advantageously used in an amount of 0.05 to 6 wt .-%, preferably 0.1 to 4 wt .-%, based on the polystyrene or styrene copolymer. The expanded plastic particles B), preferably expanded polystyrene particles or expanded Styrolcopolymerteilchen, are advantageously also after the

Pressing the light lignocellulose material, preferably light wood material, preferably multilayer lignocellulosic material, more preferably multilayer wood material, in a state before, in which their original shape is still recognizable. Optionally, melting of the expanded plastic particles that are on the surface of the lightweight material may occur

lignocellulosic, preferably light wood-containing material or preferably of the multilayer lignocellulosic material, preferably wood-based material come.

The total amount of the expanded plastic particles B), based on the light lignocellulose-containing, preferably light wood-containing material, is in the range of 1 to 15 wt .-%, preferably 3 to 15 wt .-%, particularly preferably 3 to 12 wt .-%. The total amount of expanded plastic particles B) with polystyrene and / or styrene copolymer as the only plastic particle component, based on the light lignocellulose-containing, preferably light wood-containing material, is in Range of 1 to 15 wt .-%, preferably 3 to 15 wt .-%, particularly preferably 3 to 12 wt .-%.

It has proven advantageous to match the dimensions of the above-described expanded plastic particles B), preferably expanded polystyrene particles or expanded styrene copolymer particles, to the lignocellulose particles, preferably wood particles A) or vice versa.

This tuning is expressed below by the relationship of the respective d'values (from the Rosin-Rammler-Sperling-Bennet function) of the lignocellulose particles, preferably wood particles A) and the expanded plastic particles B).

The Rossin-Rammler-Sperling-Bennet function is described for example in DIN 66145.

To determine the d'values, sieve analyzes are first carried out to determine the particle size distribution of the expanded plastic particles B) and

Lignocellulose particles, preferably wood particles A) analogous to DIN 66165, part 1 and 2 by.

The values from the sieve analysis are then used in the Rosin-Rammler-Sperling-Bennet function and calculated d '.

The Rosin-Rammler-Sperling-Bennet function is:

R = 100 ^* exp (- (d / d ') ⁿ ))

With the following meanings of the parameters:

R remainder (wt.%) Remaining on the respective sieve bottom

d particle size

d 'particle size at 36.8 wt% balance

n width of particle size distribution

Highly suitable lignocellulose particles, preferably wood particles A) have an d 'value according to Rosin-Rammler-Sperling-Bennet (definition and determination of the d value as described above) in the range from 0.1 to 5.0, preferably in the range of 0.3 to 3.0, and more preferably in the range of 0.5 to 2.75.

Highly suitable light lignocellulosic, preferably wood-containing substances or multilayer lignocellulosic materials, preferably multilayer wood-based materials are obtained if, for the d'values according to Rosin-Rammler-Sperling-Bennet Lignocellulose particles, preferably wood particles A) and the particles of the expanded plastic particles B), the following relationship applies: d 'of the particles A) <2.5 xd' of the particles B), preferably d 'of the particles A) <2.0 * d' of the particles Particle B), particularly preferably d 'of the particles A) <1, 5 * d' of the particles B), very particularly preferably d 'of the particles A) <d' of the particles B).

The binder C) is selected from the group consisting of aminoplast resin, phenol-formaldehyde resin and organic isocyanate having at least two

Isocyanate groups. These components refer to the present

Registrations the absolute and percentage amounts with regard to component C).

As a rule, the binder C) contains the substances known to the person skilled in the art for aminoplasts or phenolformaldehyde resins and commonly referred to as hardeners, such as ammonium sulfate or ammonium nitrate or inorganic or organic acids, for example sulfuric acid, formic acid or acid regenerating substances, such as aluminum chloride, aluminum sulfate , in each case in the usual, small amounts, for example in the range of 0.1 wt .-% to 3 wt .-%, based on the total amount of aminoplast resin in the binder C).

Phenol formaldehyde resins (also called PF resins) are known to the person skilled in the art, see for example Kunststoff-Handbuch, 2nd edition, Hanser 1988, Volume 10

"Duroplasts", pages 12 to 40. As aminoplast resin are here polycondensation products of compounds with at least one, optionally partially substituted by organic radicals, carbamide group (the carbamide group is also called carboxamide) and an aldehyde, preferably formaldehyde, understood as well Aminoplastharz can all be used to those skilled in the art, preferably the aminoplast resins known for the production of wood-based materials Such resins and their preparation are described, for example, in Ullmanns Enzyklopadie der technischen Chemie, 4th, revised and expanded edition, Verlag Chemie, 1973, pages 403 to 424 A2, VCH Verlagsgesellschaft, 1985, pages 115 to 141 "Amino Resins" and in M. Dunky, P. Niemz, wood materials and glues, Springer 2002, pages 251 to 259 (UF resins) and pages 303 to 313 (MUF and UF with a small amount of melamine).

Preferred aminoplast resins are polycondensation products of compounds having at least one, also partially substituted by organic radicals,

Carbamide group and formaldehyde.

Particularly preferred aminoplast resins are urea-formaldehyde resins (UF resins), melamine-formaldehyde resins (MF resins) or melamine-containing urea-formaldehyde resins (MUF resins).

Especially preferred amino resins are urea-formaldehyde resins, for example Kaurit ^® glue types from BASF SE. Furthermore, very preferred amino resins are polycondensation products of compounds having at least one, and partly with organic radicals

substituted, amino group and aldehyde, wherein the molar ratio of aldehyde:

optionally partially substituted with organic radicals amino group in the range of 0.3 to 1, 0, preferably 0.3 to 0.60, more preferably 0.3 to 0.45, most preferably 0.30 to 0.40 ,

Furthermore, very preferred aminoplast resins are polycondensation products of compounds having at least one amino group -NH 2 and formaldehyde, wherein the molar ratio of formaldehyde: -NH 2 group in the range of 0.3 to 1, preferably 0.3 to 0.60, particularly preferably 0 , 3 to 0.45, most preferably 0.30 to 0.40.

Furthermore, very preferred aminoplast resins are urea-formaldehyde resins (UF resins), melamine-formaldehyde resins (MF resins) or melamine-containing urea-formaldehyde resins (MUF resins), in which the molar ratio of formaldehyde: -NH 2 -

Group in the range of 0.3 to 1, 0, preferably 0.3 to 0.60, particularly preferably 0.3 to 0.45, most preferably 0.30 to 0.40.

Furthermore, very preferred amino resins are urea-formaldehyde resins (UF resins), wherein the molar ratio of formaldehyde: -NH2 group in the range of 0.3 to 1, preferably 0.3 to 0.60, particularly preferably 0.3 to 0.45, most preferably 0.30 to 0.40.

The said aminoplast resins are usually used in liquid form, usually suspended in a liquid suspending agent, preferably in aqueous suspension, but may also be used as a solid. The solids content of the aminoplast resin suspensions, preferably aqueous suspension, is usually from 25 to 90% by weight, preferably from 50 to 70% by weight. The solids content of the aminoplast resin in aqueous suspension can be determined according to Günter Zeppenfeld, Dirk Grunwald, adhesives in the wood and furniture industry, 2nd edition, DRW-Verlag, page 268. To determine the solids content of aminoplast glues, 1 g of aminoplast glue is accurately weighed into a weighing dish, finely distributed on the bottom and dried for 2 hours at 120 ^° C. in a drying oven. After tempering to room temperature in a desiccator, the residue is weighed and calculated as a percentage of the initial weight.

The aminoplast resins are prepared by known processes (see above Ullmann-Literatur "Aminoplasts" and "Amino Resins", as well as literature Dunky et al.) By reacting the carbamido-containing compounds, preferably urea and / or melamine, with the aldehydes, preferably

Formaldehyde, in the desired molar ratios Carbamidgruppe: aldehyde, preferably in water as a solvent.

The setting of the desired molar ratio of aldehyde, preferably formaldehyde: optionally partially substituted with organic radicals amino group can also be done by addition of -NH2 group-carrying monomers to formaldehyde-rich finished, preferably commercial, Aminoplastharzen. NH 2 group-carrying monomers are preferably urea, melamine, more preferably urea.

The further component of the binder C) may be an organic isocyanate having at least two isocyanate groups.

As a suitable organic isocyanate, all those skilled in the art, preferably those known for the production of wood materials or polyurethanes,

organic isocyanates are used. Such organic isocyanates and their preparation and use are described, for example, in Becker / Braun, Kunststoff Handbuch, 3rd revised edition, Volume 7 "Polyurethane", Hanser 1993, pages 17 to 21, pages 76 to 88 and pages 665 to 671.

Preferred organic isocyanates are oligomeric isocyanates of 2 to 10,

preferably 2 to 8 monomer units and on average at least one

Isocyanate group per monomer unit. A particularly preferred organic isocyanate is the oligomeric organic

Isocyanate PMDI ("Polymeric methylenediphenylene diisocyanate") obtainable by condensation of formaldehyde with aniline and phosgenation of the Condensation arose isomers and oligomers (see, for example

Becker / Braun, plastic manual, 3rd revised edition, volume 7

"Polyurethane", Hanser 1993, pages 18 last paragraph to page 19, second paragraph and page 76, fifth paragraph).

For the purposes of the present invention very suitable PMDI products are the products of LUPRANAT ^® type series of BASF SE, in particular LUPRANAT ^® M 20 FB of BASF SE. It is also possible to use mixtures of the described organic isocyanates, the mixing ratio not being critical according to current knowledge.

The resin components of the binder C) can be used alone, for example, aminoplast resin as the sole resin component of the binder C) or organic isocyanate as the sole resin component of the binder C) or PF resin as the sole component of the binder C).

However, the resin components of the binder C) can also be used as a combination of two or more resin components of the binder C).

The total amount of the binder C), based on the light wood-containing material, is in the range from 3 to 50 wt .-%, preferably 5 to 15 wt .-%, particularly preferably 7 to 10 wt .-%.

This is generally the total amount of the aminoplast resin (always based on the solid), preferably the urea-formaldehyde resin and / or melamine urea-formaldehyde resin and / or melamine-formaldehyde resin, more preferably urea-formaldehyde resin, in the binder C), based on the light lignocellulose-containing, preferably light wood-containing substance in the range of 1 to 45 wt .-%, preferably 4 to 14 wt .-%, particularly preferably 6 to 9 wt .-%.

In this case, the total amount of the organic isocyanate, preferably of the oligomeric isocyanate, is generally from 2 to 10, preferably from 2 to 8

Monomer units and an average of at least one isocyanate group per

Monomer unit, particularly preferably PMDI, in the binder C), based on the light lignocellulose-containing, preferably light wood-containing substance in the range from 0 to 5 wt .-%, preferably 0.1 to 3.5 wt .-%, particularly preferably 0.5 to 1, 5 wt .-%.

The proportions of the amino resin to the organic isocyanate result from the above-described ratios of the binder aminoplast Resin to light lignocellulosic, preferably light wood-containing substance or the binder organic isocyanate to light

lignocellulosic, preferably light wood-containing substance. Preferred embodiments of the light wood-containing material contain 55 to 92.5 wt .-%, preferably 60 to 90 wt .-%, in particular 70 to 88 wt .-%, based on the light wood-containing material, wood particles, wherein the wood particles have an average density from 0.4 to 0.85 g / cm ³ , preferably 0.4 to 0.75 g / cm ³ , in particular 0.4 to 0.6 g / cm ³ , 3 to 25 wt .-%, preferably 3 to 15 wt .-%, in particular 3 to 10% by weight based on the light wood-containing material, polystyrene and / or styrene copolymer as component B) having a bulk density of 10 to 100 kg / m ³ , preferably 20 to 80 kg / m ³ , in particular 30 to 60 kg / m ³ and 3 to 40 wt .-%, preferably 5 to 25 wt .-%, in particular 5 to 15 wt .-%, based on the light wood-containing material,

Binder C), wherein the total amount of the aminoplast resin, preferably the urea-formaldehyde resin and / or melamine-urea-formaldehyde resin and / or melamine-formaldehyde resin, more preferably urea-formaldehyde resin, in the binder C), based on the light wood-containing material in the range of 1 to 45 wt .-%, preferably 4 to 14 wt .-%, particularly preferably 6 to 9 wt .-% and wherein the average density of the light wood-containing material in the range of 200 to 600 kg / m ³ , preferably in the range from 300 to 575 kg / m ³ .

Optionally, in the inventive light lignocellulosic, preferably light wood-containing substance or the inventive

multilayered lignocellulose material, preferably multilayer wood material, other commercial additives known to the person skilled in the art are present as component D), for example water repellents, such as paraffin emulsions,

Antifungal agents, formaldehyde scavengers, for example urea or polyamines, and flame retardants. The present invention further relates to a process for producing a multi-layered lignocellulosic material containing at least three layers, wherein only the middle layer or at least a part of the middle layers contains a light lignocellulose-containing substance as defined in claims 1 to 4, wherein the components for the layered individual layers and pressed under elevated temperature and elevated pressure and wherein the expanded plastic particles B) are obtained from expandable plastic particles by expanding and the resulting expanded plastic particles without further intermediate steps to produce the light lignocellulosic material

continue to be used.

The average density of the multilayer, preferably of the three-layer, lignocellulose material according to the invention, preferably Wood material is in the range of 300 kg / m ³ to 600 kg / m ³ , preferably in the range of 350 kg / m ³ to 600 kg / m ³ , particularly preferably in the range of 400 kg / m ³ to 500 kg / m ³ . Preferred parameter ranges and preferred embodiments with regard to the average density of the light lignocellulose-containing, preferably light wood-containing substance and with regard to the components and their

Production process A), B), C) and D) and the combination of the features correspond to those described above.

In a well-suited process, the expanded polystyrene particles or expanded styrene copolymer particles are continuously used to make the light lignocellulosic material and the multilayer lignocellulosic material. This means that the foaming of the expanded

Polystyrene particles or expanded Styrolcopolymerteilchen and their

Further use, preferably promotion in the plant for the production of the lignocellulosic material and / or multilayer lignocellulosic material, proceed in a temporally practically uninterrupted process chain. In a preferred embodiment for producing a multilayered

Lignocellulose material, the expandable plastic particles, as described in more detail above, foamed at the site of production of the light lignocellulosic material to expandable plastic particles. In a further preferred embodiment for producing a multilayered lignocellulose material, the expandable plastic particles, as described in more detail above, are foamed to form expanded plastic particles at the place of production of the light lignocellulose-containing substance in a mobile foaming device. Middle layers in the sense of the invention are all layers that are not the outer layers.

Preferably, the outer layers (usually called "cover layer (s)") have no expanded plastic particles B).

Preferably, the multilayer lignocellulose material according to the invention, preferably multilayer wood material, contains three lignocellulosic layers,

preferably wood pulp layers, wherein the outer cover layers in sum are generally thinner than the inner layer (s).

The binder used for the outer layers is usually an aminoplast resin, for example, urea-formaldehyde resin (UF), melamine-formaldehyde resin (MF), melamine-urea-formaldehyde resin (MUF) or the invention

Binder C). Preferably, the binder used for the outer layers is an aminoplast resin, more preferably a urea-formaldehyde resin, most preferably an aminoplast resin wherein the molar formaldehyde: -NH ₂ - group ratio is in the range of 0.3 to 1.0.

The thickness of the multilayered lignocellulosic material according to the invention, preferably multilayer wood material, varies with the field of application and is generally in the range of 0.5 to 100 mm; preferably in the range of 10 to 40 mm, in particular 15 to 20 mm.

The processes for producing multilayer wood-based materials are known in principle and described, for example, in M. Dunky, P. Niemz, Holzwerkstoffe und Glue, Springer 2002, pages 91 to 150.

An example of a method for producing a novel

multilayer wood material is described below.

After cutting the wood, the chips are dried. Thereafter, if necessary, coarse and fines are removed. The remaining chips are sorted by sieving or sifting in the air stream. The coarser material is used for the

Middle layer, the finer used for the cover layers. Middle class and

Overlay chips are glued separately from each other with components B) (only the middle layer (s)), C) (same or different for middle layer and outer layer) and optionally D) (middle layer and / or outer layers),

or mixed and then scattered. The component B) was obtained shortly before by expanding the expandable plastic particles and mixed directly and preferably continuously with the other components for the preparation of the middle layer. First, the cover layer material is scattered on the forming belt, then the middle layer material - containing the components B), C) and optionally D) - and finally again cover layer material. The three-layer chip cake thus produced is precompressed cold (usually at room temperature) and then pressed hot. The pressing can be carried out by all methods known to the person skilled in the art. Usually, the wood particle cake is pressed at a press temperature of 150 ⁰ C to 230 ⁰ C to the desired thickness. The pressing time is normally 3 to 15 seconds per mm plate thickness. This gives a three-layer chipboard.

The advantages of the present invention lie in the low density of

light lignocellulose-containing, preferably light wood-containing material according to the invention or multilayer lignocellulosic pulps according to the invention, preferably multilayer wood material, wherein a good mechanical stability is maintained.

Furthermore, the light lignocellulose-containing, preferably light wood-containing material according to the invention and multilayer lignucellulose material according to the invention, preferably multilayer wood-based material, can be produced easily and even continuously; There is no need to convert the existing plants for the production of the multilayer wood-based materials according to the invention or storage space for the expanded plastic particles, for example for

Propellant reduction, to install.

Claims

claims

1. A process for producing a light lignocellulosic material having a mean density in the range of 200 to 600 kg / m ³ , in which, in each case based on the lignocellulosic substance:

A) from 30 to 95% by weight of lignocellulosic particles;

C) 3 to 50 wt .-% of a binder selected from the group consisting of aminoplast resin, phenol formaldehyde resin and organic isocyanate anat with at least two isocyanate groups and optionally D) additives and then pressed under elevated temperature and under elevated pressure, characterized that the expanded plastic particles are obtained from expandable plastic particles by expanding and the resulting expanded plastic particles are used without further intermediate steps for the production of the light lignocellulosic material.

2. The method according to claim 1, characterized in that the expanded plastic particles are continuously used for the production of the light lignocellulosic material.

3. The method according to claims 1 to 2, characterized in that the expanded plastic particles are conveyed into the plant for producing the light lignocellulose-containing substance.

4. The method according to claims 1 to 3, characterized in that the conveying path for the expanded plastic particles has one or more buffer container in the main or shunt.

5. The method according to claims 1 to 4, wherein the expandable plastic particles are foamed at the site of production of the light lignocellulose-containing material to expand plastic particles.

6. The method according to Ansprüchel to 5, wherein the expandable plastic particles are foamed at the site of production of the light lignocellulosic material in a mobile foaming to expanded plastic particles.

7. The method according to claims 1 to 6 wherein the lignocellulose-containing particles are wood particles.

8. The method according to claims 1 to 7 wherein the component B) is selected from the group consisting of styrene homopolymer and Styrolcopolymeri- sat.

9. A process for producing a multi-layered lignocellulosic material containing at least three layers, wherein only the middle layer or at least a portion of the middle layers contains a light lignocellulosic material as defined in claims 1, 7 and 8, wherein the components for the individual layers stacked and pressed under elevated temperature and elevated pressure and wherein the expanded plastic particles

B) are obtained from expandable plastic particles by expanding and the resulting expanded plastic particles are used without further intermediate steps for the preparation of the light lignocellulosic material.

10. The method according to claim 9, wherein the expandable plastic particles are foamed at the site of production of the light lignocellulosic material to expandable plastic particles.

1 1. A method according to claims 9 to 10, wherein the expandable plastic particles are foamed at the site of production of the light lignocellulosic material in a mobile foaming to expanded plastic particles.

12. The method according to claims 9 to 1 1 wherein the outer cover layers contain no expanded plastic particles B).