KR102030206B1 - Lignocellulosic materials with lignocellulosic fibers in the outer layers and expanded plastics particles present in the core, and process and use thereof - Google Patents

Abstract

The present invention is in the center
A) 30 to 98% by weight lignocellulosic particles,
B) expanded plastic particles having a bulk density in the range from 10 to 150 kg / m ³ , from 1 to 25% by weight,
C) 1 to 50% by weight of at least one binder selected from the group consisting of phenoplast resins, aminoplast resins, and organic isocyanates having at least two isocyanate groups, and
D) 0 to 30% by weight of additives
On the outer floor
E) 70 to 99% by weight lignocellulosic fibers,
F) 1 to 30% by weight of at least one binder selected from the group consisting of phenoplast resins, aminoplast resins, and organic isocyanates having at least two isocyanate groups, and
G) 0 to 30 wt% additive
It relates to a lignocellulosic material having a central portion and two outer layers.

Description

LIGNOCELLULOSIC MATERIALS WITH LIGNOCELLULOSIC FIBERS IN THE OUTER LAYERS AND EXPANDED PLASTICS PARTICLES PRESENT IN THE CORE, AND PROCESS AND USE THEREOF}

The present invention relates to a lignocellulosic material having a central portion and two outer layers, the central portion comprising expanded plastic particles and the outer layer comprising lignocellulosic fibers.

CH-A-370 229 discloses compression molding, having both light weight and compressive strength and consisting of porous, foamable or partially foamed plastics provided with wood chips or wood fibers, binders, and fillers.

The disadvantage of these compression moldings is that they do not have an outer layer without plastic, which indicates that conventional coating techniques (e.g., linings using furniture foils or short cycle coatings using melamine films) lead to poor results. it means.

DE-U-20 2007 017 713 discloses a weight-reduced plywood panel through the combination of wood chips in the middle layer of the panel with uniformly dispersed foamed polystyrene beads.

The disadvantage of this material is that flexural strength, screw pullout resistance and surface quality are not sufficient for all applications.

WO-A-2008 / 046890 discloses lightweight single and multi-ply wood comprising wood particles, fillers of polystyrene and / or styrene copolymers having a bulk density of from 10 to 100 kg / m ³ , and binders -Disclose the base material. The fillers are advantageously evenly distributed in the wood-based material. Wood-based materials are made from wood veneers, from wood chips, or from wood fibers, more preferably from wood chips and wood fibers.

A disadvantage of these materials is that the cost increases as a given improvement in panel density properties is only achievable by increasing the amount of adhesive and / or the amount of polymer.

Thus, it solves the above-mentioned disadvantages and more particularly is superior, such as high density wood-based materials, which are customary as lightweight lignocellulosic materials with improved flexural strength, improved thread pull and / or good surface properties. It is an object of the present invention to provide such materials with continuous processing properties.

Thus, it has a center and two outer layers,

In the heart

A) 30 to 98% by weight lignocellulosic particles,

B) expanded plastic particles having a bulk density in the range of 10 to 150 kg / m ³ of 1 to 25% by weight,

C) 1 to 50% by weight of at least one binder selected from the group consisting of phenoplast resins, aminoplast resins, and organic isocyanates having at least two isocyanate groups, and

D) 0 to 30% by weight of additives

On the outer floor

E) 70 to 99% by weight lignocellulosic fibers,

F) 1 to 30% by weight of at least one binder selected from the group consisting of phenoplast resins, aminoplast resins, and organic isocyanates having at least two isocyanate groups, and

G) 0 to 30 wt% additive

New and improved lignocellulosic materials have been found, including, preferably consisting of, above.

The description of the weight percentages of components A, B, C, D, E, F and G relates to the dry weight of the component as a percentage of the total dry weight. The sum of the weight percentage values for components A, B, C and D is 100% by weight. Likewise, the sum of components E, F and G is also 100% by weight. In addition, the core as well as the outer layer also contains water, which is not reflected in the weight figures. The water is derived from residual water present in the lignocellulosic particles, from the binder, from water additionally added for dilution of the binder or wetting of the outer layer, for example from additives (such as aqueous curing agent solutions or aqueous paraffin emulsions). For example, when forming expanded plastic particles (eg, using steam), they may originate from the particles. The water content of the central and outer layers can be up to 20% by weight, ie 0 to 20% by weight, preferably 2 to 15% by weight, more preferably 4 to 10% by weight, based on 100% by weight of the total dry weight. have. The ratio of the total dry mass of the center part to the total dry mass of the outer layer is generally 100: 1 to 0.25: 1, preferably 10: 1 to 0.5: 1, more preferably 6: 1 to 0.75: 1 , More particularly 4: 1 to 1: 1.

The lignocellulosic material (lignocellulose material) of the present invention may be prepared as follows:

The components for the center and the components for the outer layer are generally mixed separately from the other components.

In the case of the central portion, lignocellulosic particles A may comprise components B, C and D and / or component components contained therein (i.e., from, for example, a group of such components, two or more components (e.g., materials or Compound)) and in any desired order. Components A, B, C and D may in each case be one, two (A1, A2 or B1, B2, or C1, C2 or D1, D2) or a plurality of component components (A1, A2, A3,... , Or B1, B2, B3, ..., C1, C2, C3, ..., or D1, D2, D3, ...).

If the components consist of a plurality of component components, these component components may be added as a mixture or separately from each other. In the case of separate additions, these component components may be added at different times, not immediately after the addition of other component components or immediately after the addition of other component components. For example, when component C consists of two components C1 and C2, this means that C2 is added immediately after C1 or C1 is added immediately after C2, or one or more other components or component components, Eg component B is added between the addition of C1 and C2. It is also possible for the components and / or component components to be premixed with other components or component components before they are added. For example, additive component D1 may be added to binder C or to binder component C1 before this mixture is added to the actual mixture.

Preferably, the expanded plastic particles B can be added to lignocellulosic particles A first, after which the mixture is mixed with binder C or two or more binder components C1, C2 and the like. If two or more binder components are used, they are preferably added separately from each other. Additive D is preferably added after being partially mixed with binder C or with a binder component (ie, a plurality of components (eg a substance or compound), eg from the group of components above).

For the outer layer, lignocellulosic fibers E may comprise components F and G and / or component components present therein (i.e., from a group of components, for example, multiple components (e.g., materials or compounds) )) And mixed in any desired order. In the case of two outer layers, it is possible to use the same mixture or two different mixtures, preferably the same mixture.

If the components consist of a plurality of component components, these components may be added as a mixture or separately from each other. In this case, these component components may be added at different points in time, not immediately after the addition of other component components or immediately after the addition of other component components. Additive G is preferably added after being partially mixed with binder F or binder component.

The resulting mixtures A, B, C, D and E, F, G are layered on top of each other and compressed by conventional processes at high temperatures to give lignocellulosic moldings. For this purpose, mats are prepared on a support, which mats consist of these mixtures in the order of E, F, G / A, B, C, D / E, F, G ("sandwich structure"). The mat has a temperature of 80 to 300 ° C., preferably 120 to 280 ° C., more preferably 150 to 250 ° C., and a pressure of 1 to 50 bar, preferably 3 to 40 bar, more preferably 5 to 30 bar. Usually compressed in, to form a casting. In one preferred embodiment, the mat is cold pretensioned prior to hot pressurization. Compression can be performed by any method known to those skilled in the art ("Taschenbuch der Spanplatten Technik", H.-J. Deppe, K. Ernst, 4 ^th edn., 2000, DRW-Verlag Weinbrenner, Leinfelden Echterdingen , Pp. 232 to 254 and in the examples of "MDF-Mitteldichte Faserplatten", H.-J. Deppe, K. Ernst, 1996, DRW-Verlag Weinbrenner, Leinfelden-Echterdingen, pp. 93-104). These methods use, for example, a discontinuous pressurization technique, for example in one or multiple stage pressurization phases, or a continuous pressurization technique, for example in a double belt pressurization phase.

The lignocellulosic material of the invention is generally 300 to 600 kg / m ³ , preferably 350 to 590 kg / m ³ , more preferably 400 to 570 kg / m ³ , more particularly 450 to 550 kg / has an average density of m ³ .

The lignocellulosic particles of component A are present in the lignocellulosic material at the center in an amount of 30 to 98% by weight, preferably 50 to 95% by weight, more preferably 70 to 90% by weight, and their base materials are Can be any desired wood variety or mixtures thereof, examples of which are spruce, beech, pine, larch, lime, poplar, eucalyptus, ash, chestnut and fir or mixtures thereof, preferably spruce , Beech or mixtures thereof, more particularly spruce, for example wood parts such as wood stents, wood strips, wood chips, wood fibers, wood flour or mixtures thereof, preferably wood chips, wood fibers, Wood flour and mixtures thereof, more preferably wood chips, wood fibers or mixtures thereof-plywood, MDF (medium density fiberboard) and HDF (high density fiberboard) plaques The can include those of the type used in manufacturing. The lignocellulosic particles can also be made from woody plants, such as flax, hemp, grain or other perennial plants, preferably from flax or hemp. Particular preference is given to using wood chips of the kind used to make plywood. If a mixture of different lignocellulosic particles, such as a mixture of wood chips and wood fibers or a mixture of wood chips and wood flour, is used, the proportion of wood chips is preferably at least 75% by weight, ie 75-100% by weight, More preferably, it is 90 weight% or more, ie, 90-100 weight%. The average density of component A is generally 0.4 to 0.85 g / cm ³ , preferably 0.4 to 0.75 g / cm ³ , more particularly 0.4 to 0.6 g / cm ³ .

Starting materials for lignocellulosic particles are typically plants containing wood from deforestation, forest residues, residual industrial wood and used wood, and wood fibers. Processes to the desired lignocellulosic particles, wood particles, such as wood chips or wood fibers can take place according to known methods (see, for example, M. Dunky, P. Niemz, Holzwerkstoffe und Leime, 91-156). , Springer Verlag Heidelberg, 2002].

Inside the lignocellulosic material of the outer layer, at least 75% by weight, ie 75 to 100% by weight, preferably at least 85% by weight, ie 85 to 100% by weight, more preferably at least 95% by weight, ie 95 The lignocellulosic fibers of component E, consisting of from 100% by weight of lignocellulosic fibers, are present in an amount of 70-99% by weight, preferably 75-97% by weight, more preferably 80-95% by weight. . Most preferably exclusively, ie 100% by weight lignocellulosic fibers are used. The raw materials used may be wood from all tree varieties or woody plants listed under component A. After mechanical grinding, the fibers can be produced by a grinding operation, for example after hydrothermal pretreatment. Fibrillation processes are known, for example, from Dunky, Niemz, Holzwerkstoffe und Leime, Technologie und Einflussfaktoren, Springer, 2002, pp. 135-148. The average density of component E is generally 0.3 to 0.85 g / cm ³ , preferably 0.35 to 0.8 g / cm ³ , more particularly 0.4 to 0.75 g / cm ³ .

Component A is 0 to 10% by weight, preferably 0.5 to 8% by weight (within the usual low fluctuation range of 0 to 0.5% by weight, preferably 0 to 0.4% by weight, more preferably 0 to 0.3% by weight) %, More preferably 1 to 5% by weight of conventional minor amounts of water. This quantitative value is based on 100% by weight of absolute dry wood material and immediately prior to mixing with the first component or the first component component or the first mixture selected from B, C and D (known to those skilled in the art The water content of component A after drying (by conventional methods) is described.

In a preferred embodiment, component E is 0 to 10% by weight (within the usual low fluctuation range of 0 to 0.5% by weight, preferably 0 to 0.5% by weight, more preferably 0 to 0.3% by weight), preferably May comprise a small amount of water of 0.5 to 8% by weight, more preferably 1 to 5% by weight. This quantitative value is based on 100% by weight of absolute dry wood material and immediately before mixing with the first component or with the first component component or with the first mixture selected from F and G (conventionally known to those skilled in the art) The water content of component E after drying) by a method is described.

In another preferred embodiment, component E is in the range of 0 to 20% by weight, preferably 0 to 10% by weight, more preferably 0 to 5% by weight), 30 to 200% by weight, preferably 40 To 150% by weight, more preferably 50 to 120% by weight of water. This quantitative value is based on 100% by weight of absolute dry wood material and describes the water content of component E immediately before mixing with the first component or with the first component component or the first mixture selected from F and G. do. In this embodiment, after the addition of all components and / or some of the component components, drying occurs according to methods known to those skilled in the art, and preferably this drying occurs after addition of all components.

Suitable expanded plastic particles (component B) are 10 to 150 kg / m ³ (measured by metering a defined volume filled with bulk material), preferably 30 to 130 kg / m ³ , more preferably 35 to Expanded plastic particles, preferably expanded thermoplastic particles, having a bulk density of 110 kg / m ³ , more particularly 40 to 100 kg / m ³ .

The expanded plastic particles B are generally in the form of spheres or beads, having an average diameter of 0.01 to 50 mm 3, preferably 0.25 to 10 mm 3, more preferably 0.4 to 8.5 mm and more particularly 0.4 to 7 mm 3. Used. In one preferred embodiment, the spheres have a small surface area per unit volume, for example in the form of spherical or ellipsoidal particles, preferably a closed-cell sphere. The loss ratio according to DIN ISO 4590 is generally 30% or less, ie 0-30%, preferably 1-25%, more preferably 5-15%.

Suitable polymers on which the expandable or expanded plastic particles are based are generally all known polymers or mixtures thereof, preferably thermoplastic polymers or mixtures thereof, which can be foamed. Very suitable examples for these polymers are polyketones, polysulfones, polyoxymethylene, PVC (rigid and ductile), polycarbonates, polyisocyanurates, polycarbodiimides, polyacrylimides and polymethacrylimides, polyamides , Polyurethane, aminoplast resins and phenolic resins, styrene homopolymers (also referred to as "polystyrenes" or "styrene polymers"), styrene copolymers, C ₂ -C ₁₀ olefin homopolymers, C ₂ -C ₁₀ olefins Copolymers, and polyesters. To prepare the olefin polymers mentioned, preference is given to using 1-alkenes, examples of which are ethylene, propylene, 1-butene, 1-hexene and 1-octene.

The polymer, preferably the thermoplastic resin, may additionally be mixed with conventional additives which form the basis of the expandable or expanded plastic particle B, examples of which include UV stabilizers, antioxidants, paints, hydrophobicizing agents, nucleating agents, plasticizers, Flame retardants, soluble and insoluble, organic and / or inorganic dyes, pigments, and auxiliaries, are opaque particles, such as carbon black, graphite or aluminum powder, present or spatially separated in the same space.

Component B can typically be obtained as follows:

Suitable polymers, which use an expandable medium (also called "foaming agent") or comprise an expandable medium, can be expanded by exposure to microwave energy, thermal energy, hot air, preferably steam and / or pressure changes. (This swelling is also sometimes referred to as “foaming”) (Kuntstoff Handbuch 1996, volume 4, “Polystyrol”, Hanser 1996, pp. 640-673) or [US-A-5,112,875]. In the course of this procedure, generally, the blowing agent expands, the particles increase in size, and cell structures are formed. This expansion is performed in conventional foaming apparatus, often referred to as "prefoamers". Such preformers may be permanently installed or may be removable. Expansion may be carried out in one or more stages. In general, in a one step process, the expandable plastic particles are directly expanded to the desired final size. In general, in a multistage process, the expandable plastic particles are first expanded to intermediate size and then to one or more additional steps through the corresponding number of intermediate sizes to the desired final size. The small plastic particles identified above (also referred to herein as "expandable plastic particles") generally do not have a cell structure, unlike expanded plastic particles. The expanded plastic particles generally have a low residual blowing agent content of from 0 to 5% by weight, preferably from 0.5 to 4% by weight and more preferably from 1 to 3% by weight, based on the total mass of the plastic and the blowing agent. The expanded plastic particles obtained in this way can be stored in a temporary reservoir or further used without other intermediate steps for preparing component B of the present invention.

Expandable plastic particles can be expanded using any blowing agent known to those skilled in the art, examples of which are aliphatic C ₃ to C ₁₀ hydrocarbons such as propane, n-butane, isobutane, n-pentane, isopentane, neopentane, cyclo Commercial pentane of pentane and / or hexanes and isomers thereof, alcohols, ketones, esters, ethers or halogenated hydrocarbons, preferably n-pentane, isopentane, neopentane and cyclopentane, more preferably n-pentane and isopentane Isomer mixture.

The amount of blowing agent in the expandable plastic particles generally ranges from 0.01 to 7% by weight, preferably from 0.01 to 4% by weight, more preferably from 0.1 to 4% by weight, based in each case on the expandable plastic particles containing the blowing agent. to be.

One preferred embodiment uses styrene homopolymers (also referred to herein simply as “polystyrenes”), styrene copolymers or mixtures thereof as the only plastic in component B.

Polystyrene and / or styrene copolymers of this kind may be employed in any polymerization technique known to those skilled in the art (e.g. Ullmann's Encyclopedia, Sixth Edition, 2000 Electronic Release or Kunststoff-Handbuch 1996, volume 4 "Polystyrol", 567-598 Page].

Expandable polystyrene and / or styrene copolymers are generally prepared by conventional methods, either by suspension polymerization or using extrusion processes.

In the case of suspension polymerization, styrene can be polymerized by radical forming catalysts in aqueous suspension in the presence of conventional suspension stabilizers, optionally with the addition of additional comonomers. Blowing agents and any other conventional auxiliaries may be included in the initial charge in the polymerization, or added to the batch during the polymerization or after the polymerization is finished. The obtained bead-like expandable styrene polymer, impregnated with a blowing agent, can be separated from the aqueous phase, washed, dried and screened after the polymerization has ended.

In the case of an extrusion process, the blowing agent is, for example, mixed into the polymer via an extruder, transported through a die plate, and pelletized under pressure to form particles or strands.

Preferred or particularly preferred expandable styrene polymers or expandable styrene copolymers described above have a relatively low blowing agent content. Such polymers are also referred to as "low foaming agents". Very suitable methods for preparing expandable polystyrene or expandable styrene copolymers with low blowing agents are described in US Pat. No. 5,112,875, incorporated herein by reference.

As described, it is also possible to use styrene copolymers. Preferably, these styrene copolymers are at least 50% by weight, ie 50-100% by weight, preferably at least 80% by weight, ie 80-100% by weight, based on the mass of the plastic (without foaming agent). Containing copolymerized styrene. Examples of comonomers contemplated are esters with alcohols having 1 to 8 C atoms of α-methylstyrene, ring-halogenated styrene, acrylonitrile, acrylic acid or methacrylic acid, N-vinylcarbazole, maleic acid, Maleic anhydride, (meth) acrylamide and / or vinyl acetate.

The polystyrene and / or styrene copolymers are preferably small amounts of copolymerized chain-branching agents, in other words compounds having one or more double bonds, preferably two double bonds, such as divinylbenzene, butadiene and / or Or butanediol diacrylate. Branching agents are generally used in amounts of 0.0005 to 0.5 mol%, based on styrene. Mixtures of different styrene copolymers may also be used. Very suitable styrene homopolymers or styrene copolymers are crystal clear polystyrene (GPPS), high-impact polystyrene (HIPS), anionically polymerized polystyrene or high-impact polystyrene (A-IPS), styrene- α-methylstyrene copolymer, acrylonitrile-butadiene-styrene polymer (ABS), styrene-acrylonitrile (SAN), acrylonitrile-styrene-acrylic acid ester (ASA), methyl acrylate-butadiene- Styrene (MBS), methyl methacrylate-acrylonitrile-butadiene-styrene (MABS) polymer or mixtures thereof, or used with polyphenylene ether (PPE).

Plastic particles, more preferably styrene polymers or styrene copolymers, more particularly having a molecular weight ranging from 70,000 to 400,000 μg / mol, more preferably 190,000 to 400,000 μg / mol, very preferably 210,000 to 400,000 μg / mol Preferably, styrene homopolymers are used.

Such expanded polystyrene particles or expanded styrene copolymer particles can be used, with or without further measurement of blowing agent reduction to prepare lignocellulosic material.

Expandable polystyrene or expandable styrene copolymers or expanded polystyrene or expanded styrene copolymers typically have an antistatic coating.

The expanded plastic particle B is generally in an unmelted state even after compression to form the lignocellulosic material, which does not generally penetrate or impregnate the lignocellulosic particles, but instead lignocellulosic particles It means that it is distributed between. Plastic particles B may be separated from lignocellulosic by conventional physical methods, for example after grinding of the lignocellulosic material.

The total amount of expanded plastic particles B is generally in the range of 1 to 25% by weight, preferably 3 to 20% by weight, more preferably 5 to 15% by weight, based on the total dry mass of the central part.

It has been shown that matching the dimensions of the expanded plastic particles B described above to lignocellulosic particles, preferably wood particles A, or vice versa.

This agreement is based on the relationship between the d 'value of each lignocellulosic particle, preferably wood particle A (from the Rosin-Rammler-Sperling-Bennet function) and the expanded plastic particle B It is expressed below by the relationship between the d 'values.

Rosin-Lammler-Spurling-Bennett functions are described, for example, in DIN 66145.

The d 'value is measured by first performing a sieve analysis to determine the particle size distribution of the expanded plastic particles B, and lignocellulosic particles, preferably wood particles A, similarly to parts 1 and 2 of DIN 66165.

 Subsequently, the sieve analysis value is assigned to the Rosin-Lammler-Spurling-Bennett function and the d 'value is calculated.

The Rosin-Lammler-Spurling-Bennett function is:

R = 100 * exp (-(d / d ') ⁿ ))

The parameters are defined as follows:

R Residue (wt%) remaining in each sieve tray

d particle size

d '36.8 in particle size by weight of residue

n width of particle size distribution

Very suitable lignocellulosic particles A, preferably wood particles, have a d 'value according to rosin-lammler-spurling-bennet in the range from 0.1 to 5, preferably from 0.3 to 3, more preferably from 0.5 to 2.75 (d 'Define and measure values as described above).

Very suitable lignocellulosic materials are obtained when the d 'value according to the rosin-lammler-spurling-bennett of lignocellulosic particles, preferably wood particles A and expanded plastic particles B, applies the following relationship: :

D '<2.5 of particle A x d' of particle B;

Preferably, d '≦ 2.0 × d ′ of particle B;

More preferably, d '≦ 1.5 × d ′ of particle B;

Very preferably, d 'of particle A ≦ d' of particle B.

The total amount of binder C is in the range of 1 to 50% by weight, preferably 2 to 15% by weight, more preferably 3 to 10% by weight, based on the total mass of the central portion.

The total amount of binder F is in the range of 1 to 30% by weight, preferably 2 to 20% by weight, more preferably 3 to 15% by weight, based on the total dry mass of the outer layer.

The binder of component C and the binder of component F may be selected from the group consisting of phenoplast resins, aminoplast resins, and organic isocyanates having two or more isocyanate groups, and the same or different binders or binder mixtures of components C and F Preference is given to using different binders, in which both phenoplasm and aminoplast are particularly preferred. Phenothiazine plast or weight value when the aminoplast resin is a second object according to (lit. [Gunter Zeppenfeld, Dirk Grunwald, Klebstoffe und in der Holz- Mobelindustrie, 2 ^nd edition, DRW-Verlag, p 268] in 120 ℃ Relating to the solids content of the corresponding component (as measured by evaporation over time), with regard to isocyanates, more particularly PMDI (polymeric diphenylmethane diisocyanate), the isocyanate component itself, in other words, To the absence of solvents or emulsifying media.

The term "phenoplasm" refers to a synthetic resin or modified product obtained by condensation of phenol and aldehyde. In addition to unsubstituted phenols, derivatives of phenols are used for the preparation of phenoplast resins. These include cresols, xylenols and other alkylphenols (eg p-tert-butylphenol, p-tert-octylphenol and p-tert-nonylphenol), arylphenols (eg phenylphenol and naphthol) and Dihydric phenols (eg, resorcinol and bisphenol A). The most important aldehyde component is formaldehyde, which is used in various forms including aqueous solutions and solid paraformaldehyde, and is also used as a compound to generate formaldehyde. Other aldehydes (e.g. acetaldehyde, acrolein, benzaldehyde and furfural) are also used with more limited extensions, like ketones. Phenoplast resins can be modified by chemical reaction of methylol or phenolic hydroxyl groups and / or by physical diffusion in the modifier (EN ISO 10082).

Preferred phenoplast resins are phenol aldehyde resins, most preferably phenol-formaldehyde resins. Phenol (also known as PF resins) formaldehyde resins, for example, are known from the literature ^{[Kunststoff-Handbuch, 2 nd edition} , Hanser 1988, volume 10, "Duroplaste", 12 to 40 p.

As aminoplast resins, it is possible to use all aminoplast resins known to the person skilled in the art, preferably for the production of wood-based materials. Types of such resins and methods for their preparation are described, for example, in Ullmanns Enzyklopadie der technischen Chemie, 4 ^th , revised and expanded edition, Verlag Chemie, 1973, pp. 403 to 424, and Ullmann's Encyclopedia of Industrial Chemistry , vol. A2, VCH Verlagsgesellschaft, 1985, pp. 115-141 "Amino Resins" and [M. Dunky, P. Niemz, Holzwerkstoffe und Leime, Springer 2002, pages 251 to 259 (UF resin) and pages 303 to 313 (MUF and UF with small amounts of melamine). Generally speaking, they are amino groups or carbamide groups (carbamide groups are also referred to as carboxamide groups), preferably partially substituted with one or more-optionally organic radicals, preferably carbamide groups, preferably urea or melamine And polycondensation products of compounds with aldehydes, preferably formaldehyde. Preferred polycondensation products are urea-formaldehyde resins (UF resins), melamine-formaldehyde resins (MF resins) or melamine-containing urea-formaldehyde resins (MUF resins), more preferably urea-formaldehyde resins, An example is a Kaurit® adhesive product from BASF SE.

Particularly preferred polycondensation products have a molar ratio of aldehyde to amino groups and / or carbamide groups, optionally partially substituted with organic radicals, from 0.3: 1 to 1: 1, preferably from 0.3: 1 to 0.6: 1, more It is preferably in the range of 0.3: 1 to 0.55: 1, very preferably 0.3: 1 to 0.5: 1. When aminoplasts are used in combination with isocyanates, the molar ratio of aldehyde to amino groups and / or carbamide groups, optionally partially substituted with organic radicals, is from 0.3: 1 to 1: 1, preferably 0.3: 1. To 0.6: 1, more preferably 0.3: 1 to 0.45: 1, very preferably 0.3: 1 to 0.4: 1.

The aminoplast resins mentioned are usually used in liquid form, but usually also in solid form, as 25 to 90% by weight strength solutions, preferably 50 to 70% by weight strength solutions, preferably aqueous solutions. .

The solids content of the liquid water-based aminoplast resins may be measured according to the literature [Gunter Zeppenfeld, Dirk Grunwald, Klebstoffe und in der Holz- Mobelindustrie, 2 ^nd edition, DRW-Verlag, p. 268].

The components of binder C and components of binder F by themselves may be used alone—ie, aminoplast resins or organic isocyanates or PF resins, for example as the only component of binder C or as a component of binder F. Can be. In addition, however, the resin component of binder C and the resin component of binder F may also be used as a combination of two or more components of the component of binder C and / or the component of binder F, which combination is preferably Aminoplast resins and / or phenoplast resins.

In one preferred embodiment, the combination of aminoplast and isocyanate can be used as binder C. In this case, the total amount of aminoplast resin in binder C is in the range of 1 to 45% by weight, preferably 4 to 14% by weight, more preferably 6 to 9% by weight, based on the total dry mass of the central part. to be. The total amount of organic isocyanates in binder C, preferably 2 to 10, preferably 2 to 8 monomer units, the total amount of oligomeric isocyanates having an average of at least one isocyanate group per monomer unit, more preferably PMDI, It is in the range of 0.05 to 5% by weight, preferably 0.1 to 3.5% by weight, more preferably 0.5 to 1.5% by weight, based on the total dry mass of the core.

Components D and G may each independently comprise different or identical, preferably identical, curing agents known to those skilled in the art, or mixtures thereof. Such components are commonly used when the binders C and / or F comprise an aminoplast or phenoplast resin. Such curing agents are preferably 0.01 to 10% by weight, preferably 0.05 to 5% by weight, more preferably 0.1 to 3% by weight, for example based on the total amount of aminoplast resin or phenoplast resin To the binder C and / or F.

Curing Agents for Aminoplast Resin Components or Curing Agents for Phenoplast Resin Components are understood herein to encompass all chemical compounds of any molecular weight, which accelerate or cause polycondensation of aminoplast resins or phenoplast resins. do. Very suitable groups of curing agents for aminoplast resins or phenol-formaldehyde resins are organic acids, inorganic acids, acidic salts of organic acids, and acidic salts of inorganic acids, or acid-forming salts such as ammonium salts or acidic salts of organic amines. The components of this group can of course be used in mixtures. These examples are ammonium sulfate or ammonium nitrate or organic acids or inorganic acids such as sulfuric acid, formic acid or acid-reforming materials such as aluminum chloride, aluminum sulfate or mixtures thereof. Preferred groups of curing agents for aminoplast resins or phenoplast resins are homopolymers or copolymers of organic or inorganic acids such as nitric acid, sulfuric acid, formic acid, acetic acid, and polymers with acid groups such as acrylic acid or methacrylic acid or maleic acid. to be.

Phenoplast resins, preferably phenol-formaldehyde resins, may also be cured alkyleneically. Preference is given to using carbonates or hydroxides such as potassium carbonate and sodium hydroxide.

Further examples of curing agents for aminoplast resins are described in M. Dunky, P. Niemz, Holzwerkstoffe und Leime, Springer 2002, pp. 265 to 269, further examples of curing agents for phenoplast resins, preferably phenol-formaldehyde resins, are described in M. Dunky, P. Niemz, Holzwerkstoffe und Leime, Springer 2002, pp. 341-352.

The lignocellulosic material of the present invention, as component D and component G, comprises from 0 to 10% by weight of commercially available conventional additives and additives known to those skilled in the art, independently of one another, identical or different, preferably identical additives, Preferably in an amount of 0.5 to 5% by weight, more preferably 1 to 3% by weight, examples of which include hydrophobic agents such as paraffin emulsions, antifungal agents, formaldehyde scavengers, such as urea Or polyamines, and flame retardants.

The thickness of the lignocellulosic material of the present invention, having expanded plastic particles in the center and lignocellulosic fibers in the outer layer, depends on the application and is generally 0.5-100 mm 3, preferably 10-40 mm mm, more particular. Preferably in the range of 15-20 mm.

In a preferred embodiment of the invention, the expandable plastic particles B are in a nonuniform distribution in the center. This is because the weight ratio X of the expanded plastic particles B to the lignocellulosic particles A in the outer region (“outside”) of the center is expanded to the lignocellulose particles A in the inner region (“inside”) of the center. Different from the weight ratio Y of B, in other words, it is larger or smaller in the outer region (“outside”) of the center than in the inner region (“inside”) of the center. The inner region of the center is generally separated from the two outer regions of the center by a surface extending parallel to the panel surface. The inner region of the central part is 20 to 80% by weight, preferably 30 to 70% by weight, more preferably 40 to 60% by weight, more particularly 45 to 55% by weight, very preferably of the total dry mass of the central part. It is understood to be an area comprising 50% by weight and lies between two outer areas. The two outer regions are of the same mass, in other words 25% or in each case approximately equal mass, ie 25.01: 24.99 to 25.99: 24.01% by weight, preferably 25.01: 24.99 to 25.8: 24.2%, more preferably 25.01: 24.99 to 25.6: 24.4%, more particularly 25.01: 24.99 to 25.4: 24.6%, or a different mass based on the total dry mass of the core, i.e. 26:24 to 40:10 weight percent, preferably 26:24 to 30:20 wt%, more preferably 26:24 to 27:23 wt%, more particularly 26:24 to 26.5: 23.5 wt%. The sum of the inner regions of the central portion and the sum of the two outer regions constitutes 100% by weight. In order to measure the weight ratio X of the expanded plastic particles B to the lignocellulosic particles A in the outer region of the central portion, all expanded plastic particles B and all lignocellulosic particles A included in the two outer regions are used. In this case, the ratio X 'describing the ratio of plastic particles B to lignocellulosic particles A in one of the two outer regions is the same as or different from the ratio X "describing the ratio in the other regions of the two outer regions. can do.

In the material of the invention, the weight ratio X of the expanded plastic particles to the lignocellulosic particles in the outer region (“outside”) of the center and the expanded lignocellulosic particles in the inner region (“inside”) of the center The ratio Z between the weight ratios Y of the plastic particles is 1.05: 1 to 1000: 1, preferably 1.1: 1 to 500: 1, more preferably 1.2: 1 to 200: 1. In a further preferred embodiment, this ratio Z is from 0.001: 1 to 0.95: 1, preferably from 0.002: 1 to 0.9: 1, more preferably from 0.005: 1 to 0.8: 1.

The heterogeneous distribution of plastic particle B at the center is produced as follows:

Multiple mixtures of components A, B, C and D can be prepared, containing components A and B in different mass ratios. These mixtures can be continuously scattered. In this case, in general, mixtures having components A and B of different mass ratios should be mixed only slightly or not at all. As a result, a nonuniform distribution of the expanded plastic particles in the center of the lignocellulosic material can be achieved. In this context, both the wood particles A and the plastic particles B can be separated in advance in different minutes, for example by screening. Each mixture may comprise different fractions of wood particles A and / or plastic particles B.

In another embodiment, the nonuniform distribution of plastic particles B in the center can be achieved by independent scattering. In this case, the scattering takes place using means to ensure that the spheres accumulate in the outer or inner regions of the central part, depending on the size and / or weight. This can be achieved by scattering the mixtures A, B, C and D, for example using a screening system. In one preferred embodiment, the system is equipped with screens of different hole sizes listed mirror-symmetrically. Particularly preferably, the support carrying the material for the lower outer layer has a small hole size (in the manufacturing direction) in which the screen system increases inward toward the middle of the scattering station at the start of the scattering station and decreases again at the end of the station. The screen with the conveyance is conveyed under the scattering means which are arranged in such a way. The arrangement of the screen means that the small lignocellulosic particles enter the outer region of the center in proximity to the outer layer and the large lignocellulosic particles enter the inner region of the center. At the same time, small plastic particles enter the outer region of the center close to the outer layer and large plastic particles enter the inner region of the center. Depending on the size distribution of the lignocellulosic particles and the size distribution of the plastic particles, this produces a different mass ratio of lignocellulosic particles A to plastic particles B. These types of scattering stations are described in EP-B-1140447 and DE-C-19716130.

For example, the lignocellulosic particle scattering station may include two metering silos equipped with multiple back-scraping rakes. Bulk material consisting of different large particles A and components B, C and D (“central mixture”) can be fed to the metering silo (eg from above). Placed at the bottom of each metering silo may be a bottom belt which implements two deflection rollers and in each case with the release rolls forms a discharge unit for the central mixture. Underneath each release roll there can be a continuous scraper belt, which can be guided through two deflection rollers and its lower tower in each case through a screen device having a different hole size, so that different parts of the screen device To form. Together with the scraper belt, the screen device forms a fractionating means by which lignocellulosic particles A and plastic particles B of the central mixture can be classified according to their size. The screen unit may be arranged in such a way as to scatter the fine lignocellulosic particles A and / or the plastic particles B, respectively, on the lower outer layer in the region of the scattering station externally placed in the transport direction of the network, while the granulated ligno Cellulose particles A and / or plastic particles B are scattered through the inner region of the fractionation means on the outer layer (see EP-B-1140447 for details).

According to another advantageous embodiment of the invention, at least some of the apportioning sections in each case comprise an abrasive element that bears against the surface of the screen means, and when the dispensing part is moved, wear on the surface of the screen means. Guided by the way. At each or at least some of the dispenses, the polishing element that bears under mild pressure against the surface of the screen means further enhances the cleaning effect that appears when the dispense is moved on the surface of the screen means. At the same time, the polishing element reinforces the force component acting on the particles in a direction perpendicular to the screen surface, thereby increasing the throughput. The vehicle is preferably designed as a scraper belt, more particularly as a continuous scraper belt. In this way, a particularly simple and inexpensive configuration of the vehicle is possible. Here, preferably, the scraper belt is previously formed with respect to the particles on at least a partial region in a direction perpendicular to the surface of the screen means, whereby the particles pass through the scraper belt from the metering silo, through their supply unit. Allow to bounce up. This eliminates the need for complex construction of the supply unit. According to a further advantageous embodiment of the invention, the scraper belt comprises a driver, more particularly a plate-shaped driver, which is preferably provided at regular intervals on the continuous support element in the form of a chain or belt. In this case, the support element can in each case be mounted centrally on the driver. However, it is also possible for a plurality of support elements, more particularly to be provided with two chain or belt support elements, each fixed to the lateral outer edge region of the driver. This increases the stability of the scraper belt designed according to the invention. Preferably, the driver is detachably on the support element or fixed to the support element and / or consists of an air impermeable design. On the one hand, this ensures that the driver used is optimally adapted to the screen means used, and on the other hand, worn drivers can be replaced with new ones. According to another advantageous embodiment of the invention, the polishing element is in each case formed by a driver part. In this way, the design of the means of the invention can be particularly cost effective since no separate component is needed for the polishing element. In particular, at least in the part forming the abrasive element, the driver is of a flexible design, for example made of hard rubber. This allows the polishing element to conform to the surface of the screen means, ensuring that even in the case of certain irregularities in the screen surface, the polishing element withstands a certain pressure over its width and over its entire range of motion on the surface of the screen means. . According to another preferred embodiment of the invention, the driver is subject to a wear resistant design, at least in the part forming the abrasive element, more particularly having a wear resistant coating, such as a Teflon coating. The driver portion forming the abrasive element can be designed in one part with the driver or as a separate component. If the abrasive elements are designed as separate components, they are preferably mounted on the driver so that they can be replaced when worn. According to another advantageous embodiment of the invention, the driver is formed from a waterproof, non-adhesive material, at least in the part forming the abrasive element. This prevents the particles from getting wet with the remaining adhesive attached to the driver, which may limit the pickup's pickup capacity. According to a further preferred embodiment of the invention, the screen means comprise a screen section with different screen openings, more particularly two screen sections. In this way, particles of different sizes are separated by screen regions having screen openings of different sizes. In this context, in particular, the screen zones are arranged side by side along the direction of movement of the distributable portion on the surface of the screen means, and preferably the screen openings of the screen zone located in the direction of movement of the dispensing portion are located opposite the direction of movement Is larger than the screen opening. This ensures that as they pass on the screen surface, particles with small diameters pass first through the screen means, while finally the next largest particles pass through the screen in the next screen area. Thus, depending on the number of screen zones and the size of the screen openings, the desired fractionation of the particles is achieved. These fractionated particles may fall into different collecting means for different particle diameters depending on the screen area, or may fall onto moving conveyor belts disposed below the screen means, for example, and in this way differ in particle diameters above their thickness. A network having a distribution can be prepared.

According to a further advantageous embodiment of the invention, a continuous scraper belt is guided through two deflection rolls so that the lower belt portion runs directly on the surface of the screen means, the upper belt portion at a certain distance from the surface of the screen means, more In particular in each case it is carried out substantially parallel to the surface of the screen means. In this way, in particular a compact design is possible with the means of the invention. Preferably in this case there is pick-up means provided for picking up the removed particles, at least at one end of the scraper belt, more particularly in the region of the deflection roll. These particles can be, for example, extraterrestrial bodies, such as screws or nails, present in the bulk material, and can instead be aggregates or particles exceeding the maximum allowable size, which even the largest screen opening of the screen means. Emitted and removed to prevent clogging. According to another preferred embodiment of the present invention, at least in the region between the upper and lower belt portions, an intermediate base is provided, the driver bears with the end opposite the portion forming the abrasive element with respect to the intermediate base, When the dispensing part is moved it is meant that these ends are guided in abrasion manner on the intermediate base. For this embodiment, the bulk material applied from the metering silo via its initial feed unit to the intermediate base can be introduced in a defined manner between specific deflection rollers. In this case, according to the preferred embodiment, the intermediate base can extend from one deflection roller in the direction of movement of the upper belt portion facing away from the other deflection roller; Between this other deflection roller and the end of the intermediate base facing the other deflection roller, this region is formed which is particle permeable in a direction perpendicular to the surface of the screen means. In particular, where this area is formed from further screen means having relatively large screen openings, preliminary deposition of aliens or particles having a size exceeding the size of these screen openings is possible here. Only particles passing through additional screen means fall on the primary screen means while they travel through the vehicle. According to another preferred embodiment of the invention, there are two scraper belts located one after the other in the longitudinal direction, the scraper belts being in particular mirror-symmetrically arranged with one another. In this case, advantageously, the dispensing means, more particularly in the form of a shuttle dispenser, is located downstream of the supply unit of the metering silo, and the particles taken from the metering silo are fed into the two scraper belts via the supply unit. In particular, it can be used for feeding. Using this design, it is possible to disperse particles from two different scraper belts starting from one metering silo. In particular, when the two scraper belts can be driven in the opposite direction, the two upper belt parts can be moved in a way that diverges from each other, an intermediate base is provided between the upper and lower belt parts in the above-described manner, each intermediate base It is possible for the particles applied via the distribution means of the furnace to be transported to the ends of the scraper belt located in the opposite direction, in which case they are applied to the screen means arranged under the scraper belt. Given a suitable size of the screen opening of such screen means, in particular when the size of the screen opening increases in the direction of movement of the lower belt portion, the material about the center can be formed on a moving conveyor belt disposed below the screen means, The lower outer layer is already scattered and the formation of the central material is the accumulation of fine lignocellulosic particles A and / or plastic particles B in the outer layer of the central portion, and the crude lignocellulosic particles A and / or plastic particles B are the inner layer of the central portion. Accumulates in. Instead of dispensing means, it is also possible, for example, to fill two metering silos by filling two scraper belts with particles. In all embodiments, the screen means and / or additional screen means are preferably designed as oscillating screens or as vibrating shaker screens. In this case, the bulk material supplied to the screen means becomes looser, meaning that finer particles and medium sized particles away from subsequent screens pass more quickly towards and through the screen openings (details are described in DE-C). -197 16 130).

Another preferred embodiment is the use of a roller scattering system with a specially profiled roll (roll screen). Also in this case, preferably, a symmetrical structure is selected, which means that the small lignocellulosic particles A and / or the small plastic particles B enter the outer region of the center close to the outer layer and the large lignocellulosic particles A and / or This means that large plastic particles B enter the inner region of the center. A particularly preferred embodiment is the use of one or more ClassiFormer ™ devices. Suitability is, for example, carried by the Clashformer CC from Defenbacher, which has a symmetrical structure. Alternatively, it is possible to use two C-formers C arranged in reverse and in turn.

As a wood-based material, for example, lignocellulosic material is an inexpensive and resource protection alternative to solid wood and has become particularly important in furniture making, especially for reinforced flooring and as a building material. Commonly provided as starting materials are wood particles of different thickness, examples of which are wood chips or wood fibers from various woods. Such wood particles are typically compressed with the addition of natural and / or synthetic binders and optionally additional additives to form wood-based materials in the form of panels or strands.

Lightweight wood-based materials are very important for the following reasons:

Lightweight wood-based materials make it very easy to handle the product by the end customer, for example when packaging, transporting, unpacking or making furniture. Lightweight wood-based materials result in lower transportation and packaging costs, and may save material costs in the manufacture of lightweight wood-based materials. Lightweight wood-based materials result in a reduction in energy consumption by the vehicle, for example when used as a vehicle. It is also possible to produce more cost-effectively, for example, material-intensive decorations, relatively thick countertops and side panels in kitchens using lightweight wood-based materials.

For example, there are various applications in the bathroom or kitchen furniture sector or in interior equipment, where lightweight and economical lignocellulosic materials with improved mechanical properties (eg, improved flexural strength and thread removal values) are It is required. In addition, these materials have very good surface quality to allow the application of coatings with good properties, for example paint or varnish finishes.

Example

1. Preparation of expanded polymer particles

Expandable polystyrene Polystyrol Kaurit® Lite 200 (BASF S) was provided as starting material. Polystyrene particles were treated with steam in a batch prefoamer and foamed to a bulk density of 50 g / l. The expanded polymer particles (component B) obtained in this way were stored in an air permeable bag at room temperature for 7 days before further use.

2. Manufacture of wood

A mixture of three different starting materials for each wood plank was prepared.

Mixture 1: Components E, F, and G for the Coating Layer

Mixture 2: Components A, B, C and D for Outer Regions of the Core

Mixture 3: Components A, B, C and D for the Internal Region of the Core

Component B is omitted in Comparative Example 1. That is, mixtures 2 and 3 contain only components A, C and D. In Comparative Example 2 and Example 3 according to the invention, mixtures 2 and 3 are identical. Mixture 1 included wood shavings as component E in Comparative Examples 1 and 2 and all other examples included wood fibers.

The mixtures were each prepared with a laboratory mixer, with the solid components first introduced and mixed. The liquid components were premixed in a vessel and then sprayed.

For mixture 1, fine coating layer spruce chips with a water content of 5.9% or wood fibers with a water content of 2.8% were used (component E).

For mixtures 2 and 3, middle layer shavings consisting of shavings having a water content of 3.2% were used (component A).

Kaurit® Glue 347 (BASF S) having a solids content of 67% was used as binder (components C and F). For mixture 1, 40 parts by weight of water and 1 part by weight of 52% strength ammonium nitrate solution (in each case based on 100 parts by weight of Kaurit Glue 347) were added to the adhesive prior to application to the solid components of the mixture. . For mixtures 2 and 3, 4 parts by weight of 52% strength ammonium nitrate solution (based on 100 parts by weight of Kaurit Glue 347) was added to the adhesive before applying to the solid components of the mixture.

In the case of the coating layer (mixture 1), the amount of the adhesive mixture was set such that 10% by weight of the adhesive (solid basis) per 100 parts by weight of E (solid basis) was obtained so that an adhesive amount of 10% was obtained.

At the center (both in the outer zone-mixture 2 and inner zone-mixture 3 at the center), the amount of the adhesive mixture is such that 8.0% of the adhesive addition is obtained, ie 8.0 per 100 parts by weight of the mixture of A and B (based on solids) Weight parts of adhesive (solid basis) were set.

The mixture was subsequently placed over the others in a 30 × 30 cm mold to obtain a wood mat having a symmetrical structure consisting of five layers (Sequence: Mixture 1, Mixture 2, Mixture 3, Mixture 2, Mixture 1). The amount was chosen in each case such that the weight ratio of the layers (dry basis) was 15.5: 20.5: 28: 20.5: 15.5.

For all examples comprising component B, the mass ratio of the total amount of component B included in the inner three layers to the total amount of component A included in the inner three layers is the same (solid basis).

The total weight of the wood mat was chosen to obtain the desired density at a predetermined thickness of 18.5 mm at the end of the pressing process.

The wood mat was then pre-compressed cold and pressed in a hot press. A thickness of 16 mm was set here. In each case the press temperature was 210 ° C. and the press time was 210 seconds.

3. Survey of Wood

3.1 Density

24 hours after preparation, the measurement of density was carried out according to EN 1058.

3.2 transverse tensile strength

Measurement of transverse tensile strength was performed according to EN 319.

3.3 Flexural Strength and E Modulus in Bending

Measurements of flexural strength and E modulus in bending were performed according to EN 310.

3.4 thread pull-out resistance

The measurement of the thread pullout resistance was performed according to DIN EN 320. Only the screw pull resistance to the surface was measured.

3.5 Lift-off strength

Peel strength was measured as a measure of surface quality according to DIN EN 311.

Examples 1 and 2: Comparative example using debris in coating layer (with or without expanded polymer particles in center)

Examples 3 to 7: Examples according to the invention

In the table above, a) indicates that the comparative example does not include any expanded polymer particles.

Claims (9)

Central
A) 30 to 98% by weight lignocellulosic particles,
B) expanded plastic particles having a bulk density in the range from 10 to 150 kg / m ³ , from 1 to 25% by weight,
C) 1 to 50% by weight of at least one binder selected from the group consisting of phenoplast resins, aminoplast resins, and organic isocyanates having at least two isocyanate groups, and
D) from 0 to 10% by weight of an additive,
Outer layer
E) 70 to 99% by weight lignocellulosic fibers,
F) 1 to 30% by weight of at least one binder selected from the group consisting of phenoplast resins, aminoplast resins, and organic isocyanates having at least two isocyanate groups, and
G) 0-10% by weight of an additive,
The expanded plastic particles B are present in a nonuniform distribution in the center, such that the weight ratio X of the expanded plastic particles B to the lignocellulosic particles A in the outer region (“outside”) of the center is the inner region (“inside”) of the center. Different from the weight ratio Y of the expanded plastic particles B to the lignocellulosic particles A in
Lignocellulosic material having a central portion and two outer layers. The method of claim 1,
Central
A) 30 to 98% by weight lignocellulosic particles,
B) expanded plastic particles having a bulk density in the range from 10 to 150 kg / m ³ , from 1 to 25% by weight,
C) 1 to 50% by weight of at least one binder selected from the group consisting of phenoplast resins, aminoplast resins, and organic isocyanates having at least two isocyanate groups, and
D) from 0 to 10% by weight of additives,
Outer layer
E) 70 to 99% by weight lignocellulosic fibers,
F) 1 to 30% by weight of at least one binder selected from the group consisting of phenoplast resins, aminoplast resins, and organic isocyanates having at least two isocyanate groups, and
G) consisting of 0 to 10% by weight of additives,
The expanded plastic particles B are present in a nonuniform distribution in the center, such that the weight ratio X of the expanded plastic particles B to the lignocellulosic particles A in the outer region (“outside”) of the center is the inner region (“inside”) of the center. Different from the weight ratio Y of the expanded plastic particles B to the lignocellulosic particles A in
Lignocellulosic material having a central portion and two outer layers. The method of claim 1, wherein components E, F and G for the outer layer, and components A, B, C, and D for the center are mixed, but the material for the center is scattered to form a heterogeneous mixture of components A and B. Process for preparing lignocellulosic material according to claim 2. The method of claim 3, wherein
A non-uniform mixture of components A and B is obtained by successively scattering different mixtures having different mass ratios of A to B. The method of claim 3, wherein
A non-uniform mixture of components A and B is obtained by separately scattering a mixture comprising A, B, C and D. delete delete delete delete