WO2013092817A1

WO2013092817A1 - Lignocellulose materials comprising expanded plastic particles non-homogeneously distributed in the core

Info

Publication number: WO2013092817A1
Application number: PCT/EP2012/076310
Authority: WO
Inventors: Stephan WEINKÖTZ; Michael Schmidt; Michael Finkenauer; Ralph Lunkwitz
Original assignee: Basf Se; Basf Schweiz Ag
Priority date: 2011-12-23
Filing date: 2012-12-20
Publication date: 2013-06-27
Also published as: ZA201405334B; AU2012357001B8; MY182505A; JP2015506856A; AU2012357001A1; KR102052223B1; CN103998194B; EP2794210A1; BR112014007761B1; PT2794210T; EP2794210B1; PL2794210T3; CA2854701A1; NZ622991A; EA027632B1; CA2854701C; ES2704884T3; CL2014001022A1; BR112014007761A2; CN103998194A

Abstract

Materials which contain lignocellulose, have a core and two covering layers, and contain, in the core, A) 30 to 98 wt. % lignocellulose particles, B) 1 to 25 wt. % expanded plastic particles having a bulk density in the range of 10 to 150 kg/m³, C) 1 to 50 wt. % of one or more binding agents selected from the group consisting of amino resin, phenolic resin and organic isocyanate comprising at least two isocyanate groups, and D) 0 to 10 wt. % additives, and, in the covering layers, E) 70 to 99 wt. % lignocellulose particles, F) 1 to 30 wt. % of one or more binding agents selected from the group consisting of amino resin, phenol formaldehyde resin and organic isocyanate comprising at least two isocyanate groups, and G) 0 to 10 wt. % additives. The lignocellulose particles of the covering layers E contain at least 25 wt. % lignocellulose-containing chips, and the expanded plastic particles B are non-homogeneously distributed in the core.

Description

Lignocellulose materials with inhomogenously distributed in the core present expanded plastic particles

description

The present invention relates to lignocellulose-containing materials having a core and two outer layers, wherein expanded plastic particles are contained in the core, which are distributed inhomogeneous. From CH-A-370 229 light and at the same time pressure-resistant molding materials are known which consist of wood chips or fibers, a binder and a porous foamable or partially foamable plastic serving as a filler.

A disadvantage of these molding materials is that they have no plastic-free cover layers and therefore conventional coating technologies (for example lamination with furniture film or short-cycle coating with melamine films) lead to poor results.

From DE-U-20 2007 017 713 weight-reduced chipboard by combination of wood chips and evenly distributed foamed polystyrene beads in the middle position of the chipboard are known.

A disadvantage of these materials is that the flexural strength, the screw pullout strength and the surface quality are not sufficient for all applications. WO-A-2008/046890 discloses lightweight, single-layer and multilayer wood-based materials which contain wood particles, a filler of polystyrene and / or styrene copolymer with a bulk density of 10 to 100 kg / m ³ and binder. The filler is advantageously present uniformly distributed in the wood material. A disadvantage of these materials is that an improvement in the properties at the same plate density can be achieved only with an increase in the amount of glue and / or the amount of polymer and thus with an increase in costs.

It is an object of the present invention to remedy the abovementioned disadvantages, in particular to provide lightweight lignocellulose-containing materials with improved transverse tensile strengths, improved flexural strengths, improved helical extraction values and / or good surface properties, which still have good processing properties, such as conventional high-quality wood-based materials Dense, own. Accordingly, new and improved lignocellulosic materials with one core and two topcoats were used in the core

A) 30 to 98% by weight of lignocellulose particles; B) 1 to 25% by weight of expanded plastic particles having a bulk density in the range from 10 to 150 kg / m ³ ,

C) 1 to 50 wt .-% of one or more binders selected from the group consisting of aminoplast resin, phenoplast resin, and organic isocyanate having at least two isocyanate groups and

D) 0 to 10 wt .-% additives

and in the top layers

E) 70 to 99% by weight of lignocellulose particles,

F) 1 to 30 wt .-% of one or more binders selected from the group consisting of aminoplast resin, phenoplast resin and organic isocyanate having at least two

Isocyanate groups and

G) 0 to 10 wt .-% additives contain, preferably consist of found, which are characterized in that the lignocellulose particles of the outer layers E contain at least 25 wt .-% lignocellulose chips and that the expanded plastic particles B are distributed inhomogeneous in the core and Process for their preparation and their use.

The indication of the wt .-% of the components A, B, C, D, E, F and G refers to the dry weight of the respective component in the total dry weight. The sum of the wt .-% information of components A, B, C and D is 100 wt .-%. The sum of components E, F and G also gives 100 wt .-%. In addition, both the outer layers and the core contain water, which is not taken into account in the weight specifications. The water can be obtained from the residual moisture contained in the lignocellulose particles, from the binder, from additionally added water, for example for diluting the binders or for wetting the outer layers, from the additives, for example aqueous hardener solutions or aqueous paraffin emulsions, or from the expanded plastic particles, if these For example, be foamed with steam, come. The water content of the core and of the cover layers can be up to 20% by weight, ie 0 to 20% by weight, preferably 2 to 15% by weight, particularly preferably 4 to 10% by weight, based on 100% by weight. Total dry weight amount. The ratio of the total dry mass of the core to the total dry mass of the outer layers is generally 100: 1 and 0.25: 1, preferably 10: 1 to 0.5: 1, particularly preferably 6: 1 to 0.75: 1, in particular 4: 1 to 1: 1. Inhomogeneously distributed in the core expandable plastic particles B means that the weight ratio X (based on dry matter) of expanded plastic particles B to lignocellulose particles A in the outer regions of the core ("outside") of the weight ratio Y of expanded plastic particles B to lignocellulose particles A in the inner region of the core ("inside"), that is larger or smaller in the outer areas of the core ("outside") than in the inner area of the core ("inside"). The inner region of the core is usually separated from the two outer regions of the core by surfaces running parallel to the plane of the plate. The inner region of the nucleus is the region of 20 to 80 Wt .-%, preferably 30 to 70 wt .-%, particularly preferably 40 to 60 wt .-%, in particular 45 to 55 wt .-%, most preferably 50 wt .-% of the total dry mass of the core and between the two outer areas lies. The two outer regions can be the same, ie 25% by weight or approximately the same, ie 25.01 to 24.99

25.99: 24.01% by weight, preferably 25.01: 24.99 to 25.8: 24.2, particularly preferably 25.01: 24.99 to 25.6: 24.4, in particular 25, 01: 24.99 to 25.4: 24.6 or different mass based on the total dry mass of the core, ie 26:24 to 40:10 wt .-%, preferably 26:24 to 30:20 wt .-%, especially preferably 26:24 to 27:23 wt .-%, in particular 26:24 bis

26.5: have 23.5 wt .-%. The sum of the inner region and the two outer regions of the core result in 100 wt .-%. For the determination of the weight ratio X of expanded plastic particles B to lignocellulose particles A in the outer regions of the core, all expanded plastic particles B and all lignocellulose particles A, which are contained in both outer regions, can be used. In this case, the ratio X ^' , which describes the ratio of plastic particles B to lignocellulose particles A in one of the two outer regions, can be the same or equal to the ratio X ^" , which describes the ratio in the other of the two outer regions.

The lignocellulose-containing materials (lignocellulose materials) according to the invention can be prepared as follows:

The components for the core and the components for the cover layers are usually mixed separately from each other.

For the core, the lignocellulose particles A may be mixed with the components B, C and D or the component components (= several constituents, for example substances or compounds, from the group of one component) contained therein in any order. The components A, B, C and D can each consist of one, two (A1, A2 or B1, B2, or C1, C2 or D1, D2) or several components components (A1, A2, A3, ..., or B1, B2, B3, ..., C1, C2, C3, ..., and D1, D2, D3, ...) exist.

If the components consist of several component components, these component components can be added either as a mixture or separately. In the separate addition of these components components can be added directly behind each other or at different, not directly successive time points. This means, for example, in the case where the component C consists of two components C1 and C2, that C2 is added immediately after C1 or C1 immediately after C2, or that between the addition of C1 and C2 one or more other components or component components, For example, component B will admit. It is also possible to premix components or component components with other components or component components before they are added. For example, an additive component D1 can be added to the binder C or the binder component C1 before this mixture is then added to the actual mixture. Preferably, the expanded plastic particles B are first added to the lignocellulose particles A and this mixture is then mixed with a binder C or two or more binder components C1, C2, etc. If two or more binder components are used, they are preferably added separately from one another. The additives D are preferably partially mixed with the binder C or a binder component (= several constituents, for example substances or compounds, from the group of the component) and then added.

For the cover layers, the lignocellulose particles E are mixed with the components F and G or the component components contained therein (= several constituents, for example substances or compounds, from the group of one component) in any order. Either the same mixture or two different mixtures can be used for the two outer layers, preferably the same mixture. If the components consist of several component components, these components can be added either as a mixture or separately. These components components can be added directly behind each other or at different, not directly successive time points.

The additives G are preferably partially mixed with the binder F or a binder component and then added.

The resulting mixtures A, B, C, D and E, F, G are stacked and pressed by a conventional method to a lignocellulose-containing molded body at elevated temperature. For this purpose, a mat is produced on a support which consists of these mixtures in the sequence E, F, G / A, B, C, D / E, F, G ("sandwich construction") .This mat is usually heated at temperatures from 80 to 300 ° C, preferably, 120 to 280 ° C, more preferably, 150 to 250 ° C and at pressures of 1 to 50 bar, preferably 3 to 40 bar, particularly preferably 5 to 30 bar, pressed into shaped bodies In a preferred embodiment, the mat is precompressed cold prior to this hot pressing, and the pressing can be carried out by all methods known to those skilled in the art (see examples in "Taschenbuch der Spanplatten Technik", H.-J. Deppe, K. Ernst, 4th ed. 2000, DRW - Verlag Weinbrenner, Leinfelden Echterdingen, page 232 to 254, and "MDF medium-density fiberboard" H.-J. Deppe, K. Ernst, 1996, DRW- Verlag Weinbrenner, Leinfelden-Echterdingen, pages 93 to 104.) These are discontinuous pressing methods, for example on single or multi-day presses or continuous Pressing method, for example, on double belt presses used.

The inhomogeneous distribution of the plastic particles B in the core can be produced as follows:

It is possible to prepare several mixtures of components A, B, C and D which have different mass ratios of components A and B. These can be spread one after the other. As a rule, no or only slight mixing of the mixtures with different mass ratios of components A and B should take place. This makes it possible to achieve an inhomogeneous distribution of the expanded plastic particles in the core of the lignocellulose material. In this case, both the wood particles A and the plastic particles B can be previously separated into different fractions, for example by sieving. Each of the mixtures may contain different fractions of the wood particles A and / or the plastic particles B.

In a further embodiment, the inhomogeneous distribution of the plastic particles B in the core can be carried out by separating scattering. The scattering takes place with a device which ensures that the balls accumulate either in the outer or in the inner regions of the core, depending on the size and / or the weight. This can be done, for example, that the mixture A, B, C, D is scattered using a sieve system. In a preferred embodiment, this system is equipped with screens of different hole sizes, which are arranged mirror-symmetrically. Particularly preferably, a carrier, on which the material for the lower cover layer is located, passes under a spreading device, in which a screening system is arranged so that at the beginning of the scattering device (in

Production direction) sieves with small hole size, the hole size of the sieves increases inwards towards the middle of the scattering station and decreases towards the end of the station again. The arrangement of the screens results in small lignocellulose particles getting into the outer areas of the core close to the cover, and large particles of lignocellulose in the inner area of the core. At the same time, small plastic particles enter the outer regions of the core close to the cover layer and large plastic particles enter the inner region of the core. Depending on the lignocellulose particle and plastic particle size distribution, different mass ratios of lignocellulose particles A to plastic particles B are thereby realized. Such scattering stations are described in EP-B-1 140447 and DE-C-19716130.

For example, the lignocellulosic particle scattering station may contain two metering bins, in each of which several backscatter rakes are arranged. The ("core mixture") bulk material consisting of different large particles A and components B, C and D can be supplied to the dosing bunkers (eg from above) On the underside of the dosing bins, a bottom band running over two deflection rollers can be arranged in each case Underneath the discharge rollers, an endless scraper belt guided over two deflection rollers can be arranged, the sub-tower of which can each be guided via screen devices with different hole sizes, so that different sections of the screen devices are formed along with the scraper belts, fractionating devices by which the lignocellulose particles A and the plastic particles B of the core mixture can be fractionated according to their sizes, The sections of the screening devices can be arranged so that the fine lignoce in the transport direction of the nonwoven outer regions of the litter station are sprinkled onto the lower cover layer, while the coarse lignocellulose particles A or plastic particles B are scattered over the inner regions of the fractionating devices onto the cover layer (see in detail) : EP-B-1 140447). According to a further advantageous embodiment of the invention, at least a portion of the Portionierungsabschnitte each comprise a Schleifelernent which rests against the surface of the screening device and is guided while moving the Portionierungsabschnitte dragging over the surface of the screening device. By means of a grinding element for each or at least a part of the portioning sections which bears against the surface of the screening device under slight pressure, the cleaning effect which arises when the portioning sections are moved over the surface of the screening device is further intensified. At the same time, the force acting on the particles in a direction perpendicular to the screen surface strength component is amplified by the grinding elements, so that an increase in the throughput is achieved. Preferably, the transport device is designed as a particular endless scraper belt. In this way, a particularly simple and inexpensive design of the transport device is possible. In this case, the scraper belt is advantageously designed to be permeable to the particles at least over a partial area in a direction perpendicular to the surface of the screening device, so that the particles can be poured out of the dosing hopper via the feed unit through the scraper belt onto the screening device. An elaborate design of the feed unit is unnecessary in this way. According to a further advantageous embodiment of the invention, the scraper belt comprises in particular plate-shaped driver, which are preferably provided at regular intervals on an endless chain or band-shaped carrier element. The carrier element can be mounted in each case centrally on the drivers. However, it is also possible to provide a plurality of, in particular two chain or band-shaped carrier elements, which are fastened in each case in the region of the lateral outer edges of the drivers. In this way, the stability of an inventively designed scraper belt is increased. Preferably, the carriers are releasably secured to the carrier element or to the carrier elements and / or formed impermeable to air. In this way, it is ensured that, on the one hand, the carriers used can be optimally matched to the screening devices used and, on the other hand, worn-out carriers can be exchanged for new ones. According to a further advantageous embodiment of the invention, the grinding elements are each formed by a portion of the drivers. In this way, a particularly cost-effective design of the device according to the invention is possible since no separate components are required for the grinding elements. In particular, the drivers are flexible, for example made of hard rubber, at least in their sections forming the grinding elements. This makes it possible to adapt the sanding elements to the surface of the screening device, so that even with a certain irregularity in the sanding surface it is ensured that the sanding elements bear against the surface of the screening device over their entire width and over their entire range of movement at a specific pressure ,

According to a further preferred embodiment of the invention, the drivers are abrasion resistant at least in their grinding element forming portions and in particular have an abrasion-resistant coating, such as a Teflon coating. The sections of the drivers forming the grinding elements can be formed both as one piece with the drivers and as separate components. If the grinding elements are designed as separate components, they are preferably detachably attached to the drivers, so that they can be exchanged in the event of wear. According to another advantageous embodiment Guidance form of the invention, the drivers are formed at least in their grinding elements forming sections of water-repellent, non-adhesive material. This prevents the binder-crosslinked particles from adhering to the drivers, which could limit the capacity of the portioning sections. According to a further preferred embodiment of the invention, the sieve device comprises in particular two sieve zones with different sieve openings. In this way it is achieved that particles of different sizes are fractionated through the sieve zones with sieve openings of different sizes. In particular, the sieve zones are arranged one behind the other along the direction of movement of the portioning sections movable over the surface of the sieving apparatus, wherein the sieve openings of the sieve zone / sieve zones lying in the direction of movement of the portioning sections are preferably larger than the sieve openings of the sieve zone / sieve zones opposite to the direction of movement. As a result, when passing over the screen surface, first the particles of small diameter pass through the screening device, while in the next screen zone the next larger particles subsequently pass through the screen. Depending on the number of sieve zones and the size of the sieve openings, the desired fractionation of the particles is thus achieved. The fractionated particles can be poured either in accordance with the screening zones in different collecting devices for the different particle sizes or for example on a arranged under the sieve moving conveyor belt on which in this way a nonwoven can be produced with its thickness distributed differently particle sizes.

According to a further advantageous embodiment of the invention, the endless scraper belt is guided over two deflection rollers, so that a lower belt section directly

on the surface of the screening device and an upper band section extends at a certain distance to the surface of the screening device, in particular in each case substantially parallel to the surface of the screening device. In this way, a particularly compact embodiment of a device according to the invention is possible. Preferably, at least at one end of the scraper belt, in particular in the region of the deflection rollers, a receiving device for receiving excreted particles is provided. These particles may be foreign bodies present in the bulk material, such as screws or nails; However, it is also possible for lumps or particles which exceed a permissible maximum size, and thus also the largest screen openings of the screening device, to be rejected and removed. According to a further preferred embodiment of the invention, an intermediate bottom is at least partially provided between the upper and the lower band portion, wherein the driver abut with their the sanding elements forming portions opposite ends of the intermediate bottom, so that these ends when moving the Portionierungsabschnitte sliding over the Zwischenboden be led. With this embodiment, bulk material applied to the intermediate bottom from the dosing hopper can first be transferred to a specific position between the deflection rollers via its feed unit. In this case, according to a preferred embodiment of the intermediate bottom of the one guide roller in the direction of movement of the upper band portion to the opposite other guide roller out extend, wherein between said other guide roller and said other guide roller facing the end of the intermediate floor, a region is formed which is permeable in a direction perpendicular to the surface of the screening device for the particles. In particular, if this region is formed of further sieve devices which has relatively large sieve openings, pre-separation of foreign bodies or particles having a size which is greater than the size of these sieve openings can take place here. Only the particles passing through the further screening device fall onto the sieve device below, over which they are moved by means of the transport device. According to a further preferred embodiment of the invention, two longitudinally successive scraper bands are provided, wherein the scraper bands are arranged in particular mirror-symmetrical to one another. Advantageously, the supply unit of the dosing bunker is followed by a distribution device, in particular in the form of a pendulum distributor, with which the particles discharged from the dosing bunker by the supply unit can be supplied to the two scraper belts, in particular alternately. With this configuration, it is possible to distribute particles on two different scraper belts starting from a dosing bunker. In particular, when the two scraper bands are driven in opposite directions, so that the two upper band sections are movable in opposite directions, and between the upper and the lower band section in the manner already described an intermediate bottom is provided, the particles applied via the distribution device on the respective shelves particles to the in transported opposite directions outer ends of the scraper belts and there are each applied to the arranged below the scraper belts screening devices. With appropriate dimensioning of the screen openings of these screening devices, in particular if the size of the screen openings increases in the direction of movement of the lower band sections, the material for the core can be arranged on a moving conveyor belt arranged below the screen devices on which the lower cover layer is already spread are formed in the outer layers of the core, the fine lignocellulose particles A and plastic particles B and in the inner layer of the core, the coarse lignocellulose particles A or plastic particles B are enriched. Instead of a distribution device, for example, two dosing bunkers can be provided, through which the two scraper belts are charged with particles. In all embodiments, the screening device and / or the further screening device is preferably designed as a vibrating screen or as a vibrating vibrating screen. In the process, the bulk material deposited on the screening device is further loosened up, as a result of which fine, then medium-sized particles located at a distance from the screen reach the sieve openings more quickly and through them (see in detail: DE-C-197 16 130).

Another preferred embodiment is the use of a roller spreading system with specially profiled rollers (roller screen). Here, too, a symmetrical structure is preferably selected so that small lignocellulose particles A or small plastic particles B get into the outer regions of the core close to the cover layer and large lignocellulose particles A or large plastic particles B enter the inner region of the core. A particularly preferred embodiment is the use of one or more ClassiFormer ™. Suitable is, for example, the Classiformer CC of Dieffenbacher, which has a symmetrical structure. Alternatively, two Classiformer C can be used, which are arranged behind each other and opposite. The lignocellulose materials according to the invention generally have an average density of 300 to 600 kg / m ³ , preferably 350 to 590 kg / m ³ , particularly preferably 400 to 570 kg / m ³ , in particular 450 to 550 kg / m ³ .

The lignocellulose particles of component A are present in the lignocellulose-containing materials of the core in amounts of from 30 to 98% by weight, preferably from 50 to 95% by weight, more preferably from 70 to 90% by weight, of which the raw material is any kind of wood or its Mixtures, for example, spruce, beech, pine, larch, linden, poplar, eucalyptus, ash, chestnut, fir or their mixtures, preferably spruce, beech or their mixtures, especially spruce, and may, for example Wood parts such as wood layers, wood strips, wood chips, wood fibers, wood dust or mixtures thereof, preferably wood chips, wood fibers, wood dust and mixtures thereof, particularly preferably wood chips, wood fibers or mixtures thereof - as used for the production of chipboard, MDF (medium density fiber) and HDF (High density fiber) - plates - be used. The lignocellulose particles may also be derived from wood-containing plants such as flax, hemp, cereals or other annual plants, preferably flax or hemp. Wood chips are particularly preferably used, as used in the production of particleboard. Substituting mixtures of different lignocellus particles, eg mixtures of wood shavings and wood fibers, or wood shavings and wood dust, the proportion of wood shavings is preferably at least 75 wt .-%, ie 75 to 100 wt .-%, particularly preferably at least 90 wt .-% 90 to 100% by 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 , in particular 0 , 4 to 0.6 g / cm ³ .

Starting materials for lignocellulose particles are usually roundwoods, thinnings, residual wood, forest wood waste, industrial lumber, used wood, production waste from wood-based material production, used wood-based materials and lignocellulose-containing plants. The preparation of the desired lignocellulose-containing particles, for example wood particles such as wood chips or wood fibers, can be carried out by processes known per se (for example M. Dunky, P. Niemz, Holzwerkstoffe and Glues, pages 91 to 156, Springer Verlag Heidelberg, 2002).

The lignocellulose particles E are present in the outer layers in amounts of from 70 to 99% by weight, preferably from 75 to 97% by weight, particularly preferably from 80 to 95% by weight. They consist of at least 25% by weight, ie from 25 to 100% by weight, of lignocellulose-containing chips, in particular wood chips, preferably at least 75% by weight, ie from 75 to 100% by weight, particularly preferably at least 95% by weight , ie 95 to 100 wt .-%, most preferably exclusively, so 100 wt .-%, lignocellulosic shavings, in particular wood chips used. As raw materials, lignocellulose-containing materials, in particular wood from all sub- Component A listed Lignocellulose- or wood sources are used. The preparation for the desired lignocellulose-containing particles can be carried out as described for component A. The average density of component E 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 ,

Component A may contain the usual small amounts of water from 0 to 10% by weight, preferably 0.5 to 8% by weight, particularly preferably 1 to 5% by weight (in a customary low fluctuation range of 0 to 0.5 Wt .-%, preferably 0 to 0.4 wt .-%, particularly preferably 0 to 0.3 wt .-%). This quantity refers to 100% by weight of absolutely dry wood substance and describes the water content of component A after drying (according to customary methods known to the person skilled in the art) immediately before mixing with the first component or the first component component or the first mixture selected from B. In a preferred embodiment, component E may comprise small amounts of water of from 0 to 10% by weight, preferably from 0.5 to 8% by weight, particularly preferably from 1 to 5% by weight (in a customary minor amount) Fluctuation range from 0 to 0.5 wt .-%, preferably 0 to 0.4 wt .-%, particularly preferably 0 to 0.3 wt .-%). This quantity refers to 100% by weight of absolutely dry wood substance and describes the water content of component E after drying (by customary methods known to the person skilled in the art) immediately before mixing with the first component or component component or mixture selected from F and G.

As expanded plastic particles (component B) are expanded plastic particles, preferably expanded thermoplastic plastic particles having a bulk density of 10 to 150 kg / m ³ , preferably 30 to 130 kg / m ³ , more preferably 35 to 1 10 kg / m ³ , in particular 40 up to 100 kg / m ³ (determined by weighing a defined volume filled with the bulk material). Expanded plastic particles B are generally in the form of spheres or beads having an average diameter of 0.01 to 50 mm, preferably 0.25 to 10 mm, particularly preferably 0.4 to 8.5 mm, in particular 0.4 to 7 mm inserted. In a preferred embodiment, the spheres have a small surface per volume, for example in the form of a spherical or elliptical particle, and are advantageously closed-cell. The open cell content according to DIN ISO 4590 is generally not more than 30%, ie 0 to 30%, preferably 1 to 25%, particularly preferably 5 to 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. Well suitable such polymers are, for example, polyketones, polysulfones, polyoxymethylene, PVC (hard and soft), polycarbonates, polyisocyanurates, polycarbodiimides, polyacrylimides and polymethacrylates, polyamides, polyurethanes, aminoplast resins and phenolic resins, styrene homopolymers (im Also referred to hereinafter as "polystyrene" or "styrene polymer"), styrene copolymers, C 2 -C 10 -olefin homopolymers, C 2 -C 10 -olefin copolymers and polyesters. For the preparation of said olefin polymers it is preferred to use the 1-alkenes, for example ethylene, propylene, 1-butene, 1-hexene, 1-octene.

Furthermore, the polymers, preferably the thermoplastics which underlie the expandable or expanded plastic particles B), can contain conventional 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, are added together or spatially separated as additives.

Component B can usually be obtained as follows: Suitable polymers can be expanded with an expansible medium (also called "propellant") or containing an expansible medium by the action of microwave, heat energy, hot air, preferably steam, and / or pressure change (often as "foamed") (Kunststoff Handbuch 1996, Volume 4 "Polystyrene", Hanser 1996, pages 640 to 673 or US-A-5,112,875), which generally expands the propellant, the particles This expansion can be carried out in conventional frothing devices, often referred to as "pre-expanders". Such prefoamers can be installed fixed 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", generally contain no cell structures, in contrast to the expanded plastic particles. %, preferably 0.5 to 4% by weight, particularly preferably 1 to 3% by weight, based on the total mass of plastic and blowing agent The resulting expanded plastic particles can be stored temporarily or used further without further intermediate steps to produce the component B according to the invention ,

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, preferably n-pentane, isopentane, neopentane and cyclopentane, more preferably a commercially available pentane isomer mixture of n-pentane and iso-pentane. The content of blowing agent in the expandable plastic particles is generally in the range of 0.01 to 7 wt .-%, preferably 0.01 to 4 wt .-%, particularly preferably 0.1 to 4 wt .-%, in each case based on the propellant-containing expandable plastic particles. In a preferred embodiment, styrene homopolymer (also referred to herein simply as "polystyrene"), styrene copolymer or mixtures thereof are used as the only plastic in component B.

Such polystyrene and / or styrene copolymer can be prepared by all known in the art polymerization process, see, for. 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 manner known per se by suspension polymerization or by extrusion processes.

In the suspension polymerization, styrene can, if appropriate with the addition of further comonomers, be polymerized in aqueous suspension in the presence of a customary suspension stabilizer by means of free-radical-forming catalysts. The propellant and optionally further customary additives may be initially introduced into the polymerization, added to the batch in the course of the polymerization or after the end of the polymerization. The resulting peribular, impregnated with blowing agent, expandable styrene polymers can be separated after the polymerization from the aqueous phase, washed, dried and sieved.

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

The preferred or particularly preferred expandable styrene polymers or expandable styrene copolymers described above 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-A-5,112,875, which is incorporated herein by reference.

As described, styrene copolymers can also be used. These styrene copolymers advantageously have at least 50% by weight, ie 50 to 100% by weight, preferably at least 80% by weight, ie 80 to 100% by weight, of copolymerized styrene based on the mass of the plastic (without blowing agent ) on. As comonomers come z. For example, α-methylstyrene, core-halogenated styrenes, acrylonitrile, esters of acrylic or methacrylic acid of alcohols having 1 to 8 C 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 branching, 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. 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-a-methylstyrene copolymers, acrylonitrile-butadiene-styrene polymers (ABS), styrene-acrylonitrile (SAN ), Acrylonitrile-styrene-acrylic esters (ASA), methyl acrylate-butadiene-styrene (MBS), methyl methacrylate-acrylonitrile-butadiene-styrene (MABS) polymers or mixtures thereof or with polyphenylene ether (PPE).

Plastic particles, particularly preferably styrene polymers or styrene copolymers, in particular styrene homopolymers having a molecular weight in the range from 70,000 to 400,000 g / mol, more preferably 190,000 to 400,000 g / mol, very particularly preferably 210,000 to 400,000 g / mol, are preferably used.

These expanded polystyrene particles or expanded styrene copolymer particles may be further used without or with further blowing agent reduction measures to produce the lignocellulosic material. The expandable polystyrene or expandable styrene copolymer or the expanded polystyrene or expanded styrene copolymer usually has an antistatic coating.

As a rule, the expanded plastic particles B are also in the unmelted state after compression to the ligococellulose material, which means that the plastic particles B as a rule have not penetrated or impregnated into the lignocellulosic particles but are distributed between the lignocellulosic particles. Usually, the plastic particles B can be separated from the lignocellulose by physical methods, for example after comminution of the lignocellulose material.

The total amount of the expanded plastic particles B, based on the total dry mass of the core, is generally in the range of 1 to 25 wt .-%, preferably 3 to 20 wt .-%, particularly preferably 5 to 15 wt .-%. It has proved to be advantageous to match the dimensions of the above-described expanded plastic particles B 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 in accordance with DIN 66165, Parts 1 and 2.

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 A, preferably wood particles, 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, preferably 0.3 to 3 and more preferably 0.5 to 2.75.

Highly suitable lignocellulose materials is obtained if the lignocellulose for the d 'values according to Rosin Rammler-Sperling-Bennet, preferably wood particles A and the particles B of the expanded plastic particles following relationship: d' of the particles A <2.5 ^χ d 'of the particle B, preferably d' of the particles A <2.0 ^χ d 'of the particles 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 particle B. The total amount of the binder C, based on the total mass of the core is in the range of 1 to 50 wt .-%, preferably 2 to 15 wt .-%, particularly preferably 3 to 10 wt .-%. The total amount of binder F, based on the total dry mass of the outer layers) is in the range of 1 to 30 wt .-%, preferably 2 to 20 wt .-%, particularly preferably 3 to 15 wt .-%. The binders of component C or of component F can be selected from the group consisting of aminoplast resin, phenoplast resin and organic isocyanate having at least two isocyanate groups, identical or different binders or binder mixtures of components C and F, preferably the same, more preferably in both cases aminoplast, can be used. In the case of aminoplasts or phenoplasts, the weight specification refers to the solids content of the corresponding component (determined by evaporation of the water at 120 ° C., within 2 h according to 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 (polymeric diphenylmethane diisocyanate), to the isocyanate component per se, that is, for example, without a solvent or emulsifier.

Phenoplasts are synthetic resins that are obtained by condensation of phenols with aldehydes and can be modified if necessary. In addition to unsubstituted phenol and phenol derivatives can be used for the production of phenoplasts. These derivatives can be cresols, xylenols or other alkylphenols, for example p-tert-butylphenol, p-tert-octylphenol and p-tert-nonylphenol, arylphenols, for example phenylphenol and naphthols, or divalent phenols, for example resorcinol and Bisphenol A, be. The most important aldehyde for the production of phenoplasts is formaldehyde, which can be used in various forms, for example as an aqueous solution, or in solid form as paraformaldehyde, or as a formaldehyde-releasing substance. Other aldehydes, for example, acetaldehyde, acrolein, benzaldehyde or furfural, and ketones can also be used. Phenoplasts can be modified by chemical reactions of the methylol groups or the phenolic hydroxyl groups and / or by physical dispersion in a modifier (EN ISO 10082). Preferred phenolic resins are phenol-aldehyde resins, most preferably phenol-formaldehyde resins (also called PF resins) are e.g. from Kunststoff-Handbuch, 2nd edition, Hanser 1988, Volume 10 "Duroplast", pages 12 to 40 known.

As aminoplast resin, it is possible to use all the aminoplast resins known to those skilled in the art, preferably those known for the production of wood-based materials. Such resins and their preparation are described, for example, in Ullmann's Enzyklopadie der technischen Chemie, 4th, revised and expanded edition, Verlag Chemie, 1973, pages 403 to 424 "Aminoplasts" and Ullmann's Encyclopedia of Industrial Chemistry, Vol. A2, VCH Verlagsgesellschaft, 1985, Pages 1 15 to 141 "Amino Resins" as well as 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) , They are usually polycondensation products of compounds having at least one, optionally partially substituted by organic radicals, amino group or carbamide group (the carbamide group is also called carboxamide group), preferably carbamide group, preferably urea or melamine, and an aldehyde, preferably formaldehyde. Preferred polycondensation are urea-formaldehyde resins (UF-resins), melamine-formaldehyde resins (MF-resins) or melamine-containing urea-formaldehyde resins (MUF-resins), particularly preferred urea-formaldehyde resins, for example Kaurit ^® glue types from BASF SE.

Particularly preferred are polycondensation products in which the molar ratio of aldehyde to the optionally partially substituted with organic radicals amino group or carbamide group in the range of 0.3: 1 to 1: 1, preferably 0.3: 1 to 0.6: 1, particularly preferably 0.3: 1 to 0.55: 1, very particularly preferably 0.3: 1 to 0.5: 1. If the aminoplasts are used in combination with isocyanates, the molar ratio of aldehyde to the optionally partially substituted with organic radicals amino group or carbamide group in the range of 0.3: 1 to 1: 1, preferably 0.3: 1 to 0.6 : 1, more preferably 0.3: 1 to 0.45: 1, most preferably 0.3: 1 to 0.4: 1.

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

The solids content of the liquid aqueous aminoplast resin can be determined according to Günter Zeppenfeld, Dirk Grunwald, adhesives in the wood and furniture industry, 2nd edition, DRW-Verlag, page 268. The components of the binder C and the binder F can be used alone, so for example aminoplast resin or organic isocyanate or PF resin as the sole constituent of the binder C or the binder F. The resin components of the binder C and the binder F but can also are used as a combination of two or more components of the binder C and / or the binder F, preferably these combinations contain an aminoplast resin and / or phenoplast resin.

In a preferred embodiment, the binder C used may be a combination of aminoplast and isocyanate. In this case, the total amount of the aminoplast resin in the binder C based on the total dry weight of the core in the range of 1 to 45 wt .-%, preferably 4 to 14 wt .-%, particularly preferably 6 to 9 wt .-%. The total amount of the organic isocyanate, preferably of the oligomeric isocyanate having 2 to 10, preferably 2 to 8 monomer units and an average of at least one isocyanate group per monomer unit, more preferably PMDI is in the binder C, based on the total dry weight of the core in the range of 0.05 to 5 wt .-%, preferably 0.1 to 3.5 wt .-%, particularly preferably 0.5 to 1, 5 wt .-%. The components D and G may each independently or different, preferably the same, known in the art hardener or mixtures thereof. These are usually used when the binder C or F contains aminoplasts or phenolic resins. These hardeners are preferably added to the binder C or F, for example in the range from 0.01 to 10% by weight, preferably 0.05 to 5% by weight, particularly preferably 0.1 to 3% by weight. based on the total amount of aminoplast resin or phenoplast resin.

By hardener for the aminoplast resin component or for the phenolic resin component herein are meant any chemical compounds of any molecular weight which cause or accelerate the polycondensation of aminoplast resin or phenol formaldehyde resin. A well-suited group of curing agents for aminoplast resin or phenolic resin are organic acids, inorganic acids, acid salts of organic acids and acid salts of inorganic acids, or acid-forming salts such as ammonium salts or acid salts of organic amines. The components of this group can of course also be used in mixtures. Examples are 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 or mixtures thereof. A preferred group of curing agents for aminoplast resin or phenoplast resin are inorganic or organic acids such as nitric acid, sulfuric acid, formic acid, acetic acid and polymers with acid groups such as homo- or copolymers of acrylic acid or methacrylic acid or maleic acid.

Phenolic resins, preferably phenol-formaldehyde resins, can also be cured alkaline. Carbonates or hydroxides such as potassium carbonate and sodium hydroxide are preferably used.

Further examples of curing agents for aminoplast resins are disclosed in M. Dunky, P. Niemz, Holzwerkstoffe und Leime, Springer 2002, pages 265 to 269 and further examples of curing agents for phenolic resins, preferably phenol-formaldehyde resins are from M. Dunky, P. Niemz, Holzwerkstoffe and Glues, Springer 2002, pages 341-352.

The lignocellulose materials according to the invention may contain further commercially available additives known to those skilled in the art as component D or component G independently of one another, identical or different, preferably identical, additives in amounts of 0 to 10% by weight, preferably 0.5 to 5% by weight preferably 1 to 3 wt .-%, for example, water repellents such as paraffin emulsions, antifungal agents, formaldehyde scavengers, for example urea or polyamines, and flame retardants. In the material according to the invention, the ratio Z of the weight ratio X of expanded plastic particles to lignocellulose particles in the outer regions of the core ("outer") is the weight ratio Y of expanded plastic particles to lignocellulose particles. In the inner region of the core ("inner") 1, 05: 1 to 1000: 1, preferably 1, 1: 1 to 500: 1, particularly preferably 1, 2: 1 to 200: 1. In a further preferred embodiment this ratio Z is 0.001: 1 to 0.95: 1, preferably 0.002: 1 to 0.9: 1, more preferably 0.005: 1 to 0.8: 1.

The thickness of the lignocellulosic materials according to the invention with inhomogeneously distributed in the core present expanded plastic particles varies with the field of application and is usually in the range of 0.5 to 100 mm, preferably in the range of 10 to 40 mm, in particular 15 to 20 mm.

Lignocellulose materials, for example wood-based materials, are a cost-effective and resource-saving alternative to solid wood and have gained great importance, in particular in furniture construction, in laminate flooring and as building materials. As starting materials are usually wood particles of different strengths, eg. As wood chips or wood fibers from various woods. Such wood particles are usually compressed with natural and / or synthetic binders and optionally with the addition of further additives to plate or strand-shaped wood materials.

Lightweight wood-based materials are of great importance for the following reasons:

Light wood materials lead to an easier handling of the products by the

End customers, for example, when packing, transporting, unpacking or building 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.

For example, light wood-based materials can lead to lower energy consumption of these means of transport when used in means of transport. Furthermore, using light wood materials, for example, material-consuming decorative parts, thicker worktops and cheeks in kitchens, can be produced more cheaply.

For many applications, for example in the bathroom or kitchen furniture sector or in interior design, lightweight and economical lignocellulose-containing materials with improved mechanical properties, for example improved flexural strengths, are sought. In addition, such materials should have the best possible surface quality in order to be able to apply coatings, for example a coating, with good properties. Examples

1 . Production of the expanded plastic particles

The starting material was the expandable polystyrene Kaurit® Light 200 from BASF SE. The polystyrene particles were treated with steam in a batch prefoamer and foamed to a bulk density of 50 g / l. The resulting expanded plastic Fabric particles (component B) were stored for 7 days at room temperature in an air-permeable cloth bag prior to further use.

2. Production of wood-based materials

For each wood-based panel three different mixtures of the starting materials were produced.

Blend 1: components E, F, G for the topcoats

Mixture 2: Components A, B, C, D for the outer region of the core

Mixture 3: components A, B, C, D for the inner region of the core

For Comparative Example 1, the component B is omitted, that is, the mixtures 2 and 3 then contain only the components A, C and D. The mixtures were each prepared in a laboratory mixer, wherein the solid components are initially charged and mixed. The liquid ingredients were premixed in a vessel and then sprayed.

It was spruce with a moisture content of 3.5% used (components A and E). The binder used was Kaurit® glue 347 with a solids content of 67% from BASF SE (components C and F). For the mixture 1, 10 parts by weight of water and 1 part by weight of 52% strength ammonium nitrate solution were added to the glue before application to the solid constituents of the mixture (in each case based on 100 parts by weight of Kaurit® glue 347). For mixtures 2 and 3, 4 parts by weight of 52% strength ammonium nitrate solution were added to the glue before application to the solid constituents of the mixtures (based on 100 parts by weight of Kaurit® glue 347). The amount of size liquor is adjusted to give a degree of gluing of 8.5%, ie 8.5 parts by weight of glue (based on solid substance) per 100 parts by weight of E (based on solid substance) in the mixture 1 or 8.5 parts by weight of glue (based on solid substance) per 100 parts by weight of the mixture of A and B (based on solid substance) in the mixtures 2 and 3.

Subsequently, the mixtures were stacked in a 30 x 30 cm form so that in a symmetrical structure a chip cake with 5 layers was formed (sequence: mixture 1, mixture 2, mixture 3, mixture 2, mixture 1). The amounts were chosen such that the weight ratio of the layers (based on dry matter) was 12.5: 18.8: 37.5: 18.8: 12.5.

In Examples 2 to 8, the mass ratio of the total amount of Component B contained in the inner three layers to the total amount of Component A contained in the inner three layers is equal to (based on solid substance). The total weight of the wood-based material mat was chosen such that at the end of the pressing process the desired density results at a nominal thickness of 16 mm.

The chip cake was then cold precompressed and pressed in a hot press. In this case, a thickness of 16 mm was set. The pressing temperature was 210 ° C, the pressing time 150 s.

3. Investigation of wood-based materials

3.1 Density

The density was determined 24 hours after preparation according to EN 1058.

3.2 transverse tensile strength

The transverse tensile strength was determined in accordance with EN 319. 3.3 Bending strength and flexural modulus of elasticity

The determination of the bending strength and the bending modulus of elasticity was carried out according to DIN EN 310

3.4 Screw withdrawal resistance

The screw withdrawal resistance was determined according to DIN EN 320. Only the screw withdrawal resistances for the surfaces were measured.

3.5 Lifting strength

The determination of the peel strength as a measure of the surface quality was carried out according to DIN EN 31 1.

Examples

Examples 1 and 2: Comparative Examples without expanded plastic particles or with homogeneous distribution of the plastic particles in the core

Examples 3 to 8 Examples of the invention

a) this comparative example contains no expanded plastic particles (component B)

Claims

claims

1 . Lignocellulosic materials with one core and two outer layers, in the core A) 30 to 98% by weight of lignocellulose particles;

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

D) 0 to 10 wt .-% additives and in the outer layers

E) 70 to 99% by weight of lignocellulose particles,

F) 1 to 30 wt .-% of one or more binders selected from the group consisting of aminoplast resin, phenol-formaldehyde resin and organic isocyanate having at least two isocyanate groups and

G) 0 to 10 wt .-% additives, characterized in that the lignocellulose particles of the outer layers E contain at least 25 wt .-% lignocellulose-containing chips and that the expanded

Plastic particles B are distributed inhomogeneously in the core.

2. A process for the preparation of lignocellulose-containing materials according to claim 1, by mixing the components E, F and G for the outer layers and components A, B, C and D for the core, characterized in that one comprises an inhomogeneous mixture of the components A and B generated.

3. A process for the production of lignocellulose-containing materials according to any one of claims 1 or 2, by mixing the components E, F and G for the outer layers and components A, B, C and D for the core, characterized in that the Material for the core is scattered so that an inhomogeneous mixture of components A and B is formed.

4. A process for the preparation of lignocellulose-containing materials according to claim 2 or 3, characterized in that one obtains the inhomogeneous mixture of components A and B by successively sprinkling different mixtures with different ratios A to B.

5. A process for the preparation of lignocellulose-containing materials according to any one of claims 2 to 4, characterized in that one obtains the inhomogeneous mixture of the components A and B by separating scattering of the mixture comprising A, B, C and D. Use of the lignocellulose-containing materials according to one of claims 1 to 5 in furniture construction, for laminate flooring and for building materials.

Use of the lignocellulose-containing materials according to one of claims 1 to 5 for the production of boards for furniture construction, for laminate flooring and for building materials.