EP1011940B1 - Method and device for manufacturing moulded bodies from crushed material - Google Patents

Abstract

A particle board, a fiberboard or an oriented strand board (25) is formed by the process according to the invention from a mixture of a comminuted cellulose material and a binder, especially a synthetic resin containing an unsaturated oligimer, that is hardenable by electron radiation. The process of the invention includes first forming a loosely scattered layer (4) of the mixture, e.g. on a conveyor belt, then compressing the layer in a press device (16), after performing a pre-compression in a pre-press in Some embodiments, and rapid setting of the layer (4) by means of electron radiation from an electron radiation device (22). Unlike the known processes that only use a thermosetting binder, the inventive method is hindered neither by heat transfer to the center of the board nor by a non-uniform humidity profile. High quality boards may be produced at a high yield without splitting and these boards require no conditioning storage.

Description

The invention relates to a process for the continuous production of composite wood-like plates, in the wood-like material, an electron beam curing Binder, compression pressure used for compression and electron beam energy for curing , the process of compaction from the process of introducing the electron beam energy is spatially separated.

The invention also relates to a device for continuous production of composite wood-like panels with a conveyor belt for the material, one subsequent pressing device and a subsequent electron beam device.

This method and this device are known from US-A 36 76 283. With this citation layers of wood are joined together to form a plywood panel, whereby the binder present between the layers by means of an electron beam device acting on both sides is cured. A circumferential compression band is slightly inclined arranged above the conveyor belt and forms a narrowing with this Compression gap so that the plywood layers passing through the compression gap are firm be squeezed together. Two consecutive and spaced apart Press roller pairs are said to hold the layers in the compressed or compressed position hold while being irradiated with the electron beam device which is between the arranged two pairs of press rolls and accordingly up to close to the plate arrangement is introduced.

However, the two pairs of press rolls can spring up the plate arrangement in the irradiation area prevent or only partially prevent it in the middle between the pairs of press rolls, if the layers have a corresponding stiffness. Otherwise, the rear one Press roller pair only effective when starting production, while after insertion electron beam hardening may even have a destructive effect on the continuous, already fully hardened plywood board must be expected. In any case but are the known device and the method carried out with it for the Production of chipboard, fiberboard or OSB boards unsuitable, which are made of nonwovens that tend to spring open after compression.

As is generally known, thermal for the production of chipboard or fiberboard curable binders such as urea-formaldehyde resin, melamine-formaldehyde resin, Isocyanates, phenol-formaldehyde resin, etc. used. The hardening corresponds chemically seen a thermally accelerated polymerization or polycondensation reaction. For the production of chipboard, the dried and glued with the binder Chips are fed to large-format stack presses or cycle presses (discontinuous production), or work is carried out in a continuous process (continuous production), e.g. to the Conti-Roll process, where an endless belt of chips forms a pressing section between them progressively approaching conveyor belt runs and / or a nip, whereby the compression is effected.

The production performance of such systems is crucial due to the comparatively slow Curing limited. The limiting factor is especially the transport of the outside heat applied to the center of the plate. The so-called "Steam boost effect" exploited. This causes steam to migrate from the hot due to condensation Plate surface to the middle of the plate and accelerates the heat transfer. This acceleration However, there are physical limits because there is a vapor pressure in the middle of the plate depending on the pressure applied outside and the temperature. If at the end of the pressing process, the pressure applied from the outside drops, the in the The existing vapor pressure of the plate is too high, so that plate bursts occur, namely breaking the plate in the middle of the plate.

An important capacity characteristic of a particleboard or fiberboard production plant is that Press factor, which is the time required for plate hardening to the dimension perpendicular relates to the plate surface. The maximum possible is then calculated from the plate thickness Feed (with continuous production) or the maximum possible number of cycles at Cycle presses and thus the plant capacity. Usual press factors are in the range between 3 and 6 s / mm for Conti-Roll systems and between 5 and 9 s / mm for cycle systems. For example, the curing of a 19 mm plate with a press factor of 5 results s / mm a manufacturing time of 95 seconds.

The steam boost effect, which is advantageous for accelerating curing, has the further effect Disadvantage that the product moisture on the plate surface is almost zero and towards the middle towards what an inhomogeneous moisture profile means. From the point of view of a stable product, however, a homogeneous moisture profile should be aimed for, which can be found in the Practice only stops after storage for several weeks. The processing and in particular the lamination of panels with a clearly inhomogeneous moisture profile to quality problems. In addition, ever increasing system outputs have become one lower product moisture, which is now below the moisture that the Product accepts in everyday use (balancing moisture). So the product strives Absorb moisture from the environment.

The use of high-energy electron radiation (gamma rays, X-rays, ionizing Radiation) for curing organic synthetic resins is already known. So in AT 338 499 impregnates chipboard and fiberboard with radiation-curable components described to achieve certain technological properties. Doing so a plate material is produced by conventional methods in the hot pressing process. Subsequently is an impregnation in the alternating printing process with the radiation-curable Components made and their curing carried out using electron beam energy. With this post-treatment, the mechanical properties of the plate and their Dimensional stability can be improved when exposed to water, which is why the actual Board production with a significantly reduced amount of thermally curable binder can be carried out. A mixture is formed as a radiation-curable binder unsaturated oligomers (at least 30% by weight), acrylonitrile (1-30% by weight), not co-polymerizing Additives (maximum 30% by weight) and the rest to 100% by weight vinyl unsaturated monomers. Polyester resins, unsaturated monomers, Acrylic resins, diallyl phthalate prepolymers, an acrylic-modified alkyd, epoxy or Urethane resin proposed. Polymerization accelerators are also used.

This is not about the production of a plate by electron radiation but rather a subsequent refinement in a downstream process by means of electron radiation to improve the sheet properties. The actual plate making is also carried out here using a thermally curable binder and by Heat supply in the press area with a complete hardening of the in the compressed Plate contained binder. This eliminates the aforementioned disadvantages - power limitation due to the heat transfer time, inhomogeneous moisture profile and risk of plate bursts - in principle not eliminated.

From US 3 549 509 it is known to use a molded body using radiation-curable To produce binders. Wood dust or sawdust is treated with a radiation-curable mixed liquid monomer, introduced into a mold, compressed in this and hardened by the action of radiation energy. Radioactive sources are used Electron emitter (e.g. Cobalt 60) or ionizing radiation sources (e.g. X-rays) called. According to the examples given, curing takes place in a cobalt 60 radiation chamber. Methyl acrylate, methyl methacrylate and propyl acrylate are used as radiation-curable monomers suggested.

The curing in a closed form (radiation chamber) and the comparative Slow curing of monomers by gamma radiation is a high-performance production detrimental. Accordingly, this known method is not for production either of comparatively thick plates or moldings made of chips or fibers intended for thin coatings of already dimensionally stable products, which are considered as ersles be inserted into the mold.

The invention has for its object to carry out the method described above and to design the device described at the outset in such a way that plate-shaped Body (molded body) of exact target thickness with high production output, without that a disturbing moisture content as well as an inhomogeneous moisture distribution in purchase must be taken.

This object is achieved with the characterizing features of claims 1 or 2 and Claims 17 or 21 solved.

Accordingly, two approaches are possible according to the invention, both with the power-enhancing electron beam hardening and its low-loss application at a distance work behind the compaction, the state of compaction up to electron irradiation is preserved, either by partial thermal curing during compaction - In this case too, the subsequent electron beam hardening forms the main hardening - or by applying a separate holding pressure in the area of the compression until electron beam hardening takes place.

Appropriate refinements and developments of the method according to the invention result itself from the subclaims.

The invention is based on the fact that the activation and curing of the binder used - in contrast to the thermally curing binders - is carried out by high-energy radiation from an electron beam accelerator. Its performance is essentially determined by two characteristic values: the acceleration voltage in MeV, which is responsible for the range of the energy in the body to be irradiated, and the amount of energy emitted by the radiator to the irradiated body (radiator power, dose amount), which is the product of accelerator voltage and accelerator current is. The emitter power determines the amount of energy introduced into and absorbed by the body, which is responsible for the hardening of the binder. Available accelerator systems with an acceleration voltage of 10 MeV enable a penetration depth of approx. 40 mm when irradiating one side of a plate material, which has a specific weight of 750 kg / m ³ , for example, and when irradiating on both sides with 10 MeV each of approx. 105 mm.

Compared to the previous manufacturing process for particleboard or fibreboard, this shows Process according to the invention have significant advantages. The polymerization of the particular Binder containing oligomers occurs abruptly and is primarily due to the introduction the required polymerization energy (radiation dose in kGy) is determined. The Curing takes place within a few tenths of a second. As a result, press factors of 0.05 s / mm possible, so that there is one for the 19 mm plate already mentioned above Curing time of around 1 second results, compared to 95 seconds with conventional heat curing were.

In the usual thermal hardening, the water is on the one hand used to transport heat into the Plate center advantageous, but when lowering the pressure due to the risk of space disadvantageous, it hardly affects the method according to the invention. The risk of moisture shifting is not given as there is no one-sided thermal load on the product acts, which is the cause of the moisture migration in the product to the cold middle of the plate out there. In the product itself, absorption of the incident radiation or due to the polymerization no critical temperature increase, which is the build up of a significant Would allow water vapor pressure. There is a risk of disk space therefore not. Maturation times of several days as with the usual production are necessary are therefore not necessary what regarding the storage space requirement and the bound Capital is beneficial.

Unsaturated oligomers are suitable as binders for electron beam curing. It can be advantageous to add these monomers to the type and degree of polymerization to influence the binder. Accordingly, these monomers are also called Called crosslinker. Crosslinkers have mono- (e.g. HDDA), di- (DPGDA), tri- (e.g. TMPTA) or polyfunctional groups. The choice of the networker in coordination with the unsaturated oligomer in terms of the mixing ratio and in terms of Combination of different crosslinkers influences the properties of the manufactured one Molded body or plate, e.g. Flexural strength, transverse tensile strength, flexural modulus, durability against the effects of humidity and water).

For the investigated oligomers and mixtures of oligomers with crosslinking agents is complete Curing requires a radiation dose between 70 and 100 kGy. Applicable unsaturated oligomers are e.g. Polyester resins, acrylic resins, diallyl phthalate prepolymers, acrylic modified alkyd, epoxy or urethane resins. These are in contrast to the Condensation resins usually used free of formaldehyde (test according to DIN EN 120 with photometric evaluation) and enable a connection that is resistant to boiling water of the composite in the sense of EN 1087 part 1.

Already in the usual production by means of heat hardening, efforts are made to harden in Perform the moment of greatest compression of the molded body or the plate or at least initiate, so that the form or dimensional stability is guaranteed and none Springback occurs when the pressure decreases. When it comes to electron beam curing the sudden hardening is advantageous in this regard. On the other hand is the introduction the radiation energy in the area of the high pressure is inappropriate, as far as the mechanical one Load according to thick steel plates or other pressurization devices are present, which have a significant steel-absorbing effect and which Reduce the penetration depth of the radiation. In this context it was found that a holding pressure is sufficient to ensure the maximum material compression before curing, which is significantly below the (maximum) baling pressure. It is therefore advantageous that Curing at a correspondingly low holding pressure outside of which the electron beams weakening pressing device, for example, in the conti-roll process at a distance behind the narrowest press nip.

In the interest of unimpeded or unimpaired irradiation with electron energy can also be done in two stages with a first shape-stabilizing thermal partial hardening Press pressure and a subsequent electron beam curing free of external pressurization be worked. Of course, this requires the use of a binder with a proportion of binder that is thermally curable. There is an admixture for this of commonly used thermosetting binder.

However, the addition also comes as a variant for thermal partial curing or initial curing an organic peroxide (e.g. TBPEH), which together with the binder is introduced and the crosslinking of the binder is initialized under the action of temperature. This is also a two-stage hardening process, with the first stage being below Exposure to pressure and heat an initial hardening or partial hardening with stabilization the compacted form, and in a second stage without external influence of Pressure the complete curing or polymerization of the binder by electron beam energy he follows. The thermal initial hardening only serves to fix the Material in the compressed layer and can take place at a comparatively low temperature, so that the aforementioned technological disadvantages of thermal hardening are limited being held.

Another variant of partial thermal hardening is the hardening of the top layers only by pressure and temperature. These hardened cover layers can have a thickness of 1 mm to several mm. The binder in these top layers cannot be made from one in the electron beam curable binder, from a mixture of a thermally curable Binder and a binder curable in the electron beam or from a mixture made of a binder curable in the electron beam with an organic peroxide consist. The binder for the portion of the product other than the top layers is an im Electron beam curable binder or a mixture of a thermally curable and a part curable in the electron beam.

The thermal hardening of the cover layers does not have to be complete crosslinking of the binder lead, especially if the binder used via an im Electron beam curable portion. Rather, the duration of exposure to temperature is even desirable to keep the top layers as short as possible to avoid the Exposure to adverse plate properties to be expected as low as possible to keep. The thermal partial hardening is followed by a final hardening of the product by the action of electron beam energy, this depending on the requirements of the Product properties optionally under the influence of a compared to the first stage thermal hardening can already take place at reduced holding pressure or without pressure.

The already partially hardened top layers simplify the application of a holding pressure in the Kind that on a form-stabilizing tape or a similar in function and effect Device in the field of electron beam exposure can be completely dispensed with or these can be dimensioned much weaker and therefore none or one clearly reduced absorption of the electron beam energy in the band or in the devices follows, which enables an improved use of the electron beam energy in the product. in the In the case of two-stage hardening, the effects of temperature favor the surface properties of the product (coatability, achievable density and density distribution).

The inventive method is particularly suitable for the production of Chipboard, fiberboard or OSB. But it is also on other cellulosisclies or the like Material in particle or piece form applicable, in which a mutual Connection is achieved by a binder. Examples are the production of Plywood panels, sheet-like products made of paper or paper chips, textile fibers, Bark or also certain waste fractions such as plastic waste or composite materials Plastic and paper or cardboard.

The following Examples 1 to 5 relate to tests to demonstrate the improved mechanical-technological Properties of the invention with electron beam energy hardened chip bodies:

example 1

To investigate the radical hardening by organic peroxides, which was provided as a supplementary measure, 100 parts of top layer chips from industrial chip drying were mixed with 20 parts of binder (urethane acrylate) and 0.7 parts of organic peroxide (TBPEH) in a stirrer and then in a laboratory press (size 33x33 cm ) 150 ° C for 10 minutes and a specific pressure of 13 N / mm ² exposed. The mechanical-technological properties were as follows: sample Density [kg / m ³ ] Thickness [mm] Solid resin on atro%] Transverse tensile strength [N / mm ² ] Residual moisture [%] peroxide 1019/20 1006 3.16 20.8 1.5 4.0 TBPEH

Example 2

10 parts of binder (urethane acrylate) and 0.4 part of organic peroxide (TBPEH) were applied to the chips on 100 parts of industrially dried middle layer chips in a gluing drum by air atomization. In a laboratory press, 40x40 cm plates were produced at 150 ° C for 5 minutes and a specific pressing pressure of 10 N / mm ² . The production was carried out to set a uniform plate thickness with spacer strips. In an analogous manner, comparison plates were produced with a UF resin as a binder (sample series A). The mechanical-technological properties were as follows: sample Density [kg / m ² ] Thickness [mm] Solid resin on atro%] Transverse tensile strength [N / mm ² ] Residual moisture [%] Peroxide or binder 1019/21 676 15.6 10.4 0.68 4.0 TBPEH A 680 16.0 11.0 0.60 5.5 UF

The two panels gave comparable results in terms of transverse tensile strength.

The samples of Examples 3 to 5 below are round samples with a diameter of approx. 110 mm, they were used in an electron beam accelerator system with a Accelerator voltage of 10 MeV and a current of approx. 1.5 mA corresponding to one average lamp power of 15 kW cured.

Example 3

Industrially dried middle layer chips were fractionated before further processing and the screenings with a mesh size of 2 to 4 mm were used. This was followed by gluing in a laboratory glue drum of 100 parts of chips with 10 parts of binder (epoxy acrylate) and 1 part of crosslinker (HDDA, TMPTH, DPGDA according to the sample series K, L and M). The glue was applied hot at approx. 80 ° C binder temperature by atomization through a two-component nozzle. The chip moisture was about 4% based on the dry matter. The glued chip was pressed into round shapes and cured by means of an electron beam at a dose (determined on the sample surface) of approx. 110 kGy. Comparative test specimens were produced in an analogous manner with urea-formaldehyde binder (UF) (100 parts of chips, 10 parts of solid resin, ammonium sulfate as the hardness component in accordance with sample series J). The mechanical-technological properties were compared: sample Quetz standardized to 450 kg / m ³ [N / mm ² ] Cross cooker [N / mm ² ] 2-hour swelling [%] 24-hour swelling [%] Density [kg / m ³ ] Solid resin on atro [%] Formaldehyde [mg / 100g] Residual moisture [%] Crosslinker or binder K1 / 2 0.317 0.101 5.1 8.8 409 11.0 <0.5 10.0 TMPTA 0.131 4.6 8.7 429 11.0 <0.5 10.0 IMPTA L1 / 2 0.344 0.120 3.6 9.6 448 11.0 <0.5 10.0 DPGDA 0.173 3.2 8.8 451 11.0 <0.5 10.0 DPGDA M1 / 2 0.319 0.130 3.2 8.8 445 11.1 <0.5 10.0 HDDA 0.136 3.1 10.4 462 11.1 <0.5 10.0 HDDA J1 / 2 0.292 --- 9.6 15.0 457 10.8 5.7 6.0 UF

It can be seen in comparison for the samples hardened in the electron beam that the same Degree of gluing the cross tensile strength is higher, the samples a cooking cross tensile strength and the 2-hour swelling is reduced. It should be noted that the urea-formaldehyde binder a cross cooking tensile strength test does not permit (the sample loosens when cooking). The formaldehyde content of the radiation-hardened samples was below the detection limit of 0.5 mg per 100 g plate according to EN 120.

Example 4

The samples were produced in a manner analogous to that described in Example 3, but the degree of gluing was reduced by 50%. The mechanical-technological properties were compared: sample Transverse tension normalized to 450 kg / m ³ [N / mm ² ] Cooking squeeze [N / mm ² ] 2-hour swelling [%] 24-hour swelling [%] Density [kg / m ³ ] Solid resin on atro [%] Formaldehyde [mg / 100g] Residual moisture [%] Crosslinker N1 / 2 0.265 0.076 6.3 11.3 428 5.5 <0.5 10.0 TMPTA 0.118 9.6 15.0 477 5.5 <0.5 10.0 TMPTA O1 / 2 0.265 0.074 10.0 12.2 462 5.6 <0.5 10.0 DPGDA 0.077 8.1 11.6 436 5.6 <0.5 10.0 DPGDA P1 / 2 0.291 0.085 6.8 12.6 466 5.5 <0.5 10.0 HDDA 0.075 5.8 10.8 418 5.5 <0.5 10.0 HDDA J1 / 2 0.292 --- 9.6 15.0 457 10.8 5.7 6.0 UF

It can be seen in comparison for the samples hardened in the electron beam that at clearly the cross-tensile strength drops by up to 9.3%, a cooking cross-tensile strength is still given and is 50% lower than the values in Example 3. The The formaldehyde content of the radiation-hardened samples was below the detection limit of 0.5 mg per 100 g plate according to EN 120.

Example 5

The binder was compared to Examples 3 and 4 in this case in the form of a 25% emulsion (for the purpose of improved distribution) of a melamine acrylate in the cold state upset. The water introduced by the emulsion increased the moisture in the chips in the glued state still considerable. In the conventional manufacturing process with usual Binders can only be pronounced with such chip moisture low pressing temperature and the associated long pressing time.

The mechanical-technological properties were compared: sample Transverse tension normalized to 450 kg / m ³ [N / mm ² ] Cross cooker [N / mm ² ] 2-hour swelling [%] 24-hour swelling [%] Density [kg / m ³ ] Solid resin on atro [%] Formaldehyde [mg / 100g] Residual moisture [%] binder R1 / 2 0.277 0.091 3.0 8.4 494 4.8 <0.5 20.8 emulsion 0.086 3.0 8.6 470 4.8 <0.5 20.8 emulsion J 1/2 0.292 --- 9.6 15.0 457 10.8 5.7 6.0 UF

Despite the high residual board moisture and low degree of gluing, the transverse tensile strength for R comparable to UF-bound test specimens and lies in the range of the samples from example 4. The low 2-hour swelling is striking for the R series.

Abbildung 1

eine Vorrichtung zur kontinuierlichen Herstellung von Span- oder Faserplatten unter Verwendung einer Vorpresse und mit beidseitiger Elektronenbestrahlung;

Abbildung 2

eine Vorrichtung wie in Abbildung 1, bei der jedoch die Hauptpresse anders ausgebildet ist;

Abbildung 3

eine der Abbildung 1 entsprechende Vorrichtung jedoch ohne Vorpresse;

Abbildung 4

eine Abbildung 3 entsprechende Vorrichtung mit einseitiger Elektronenbestrahlung;

Abbildung 5

eine Abbildung 1 entsprechende Vorrichtung, bei der jedoch im Bereich der Elektronenbestrahlung ein Haltedruck auf die verdichtete Platte aufgebracht wird;

Abbildung 6

eine Vorrichtung mit einer Presse, die von einer Umlenktrommel großen Durchmessers, mit dieser zusammenarbeitenden Druckrollen und einem Druckband gebildet ist, wobei eine einseitig wirkende Elektronenstrahleinrichtung vorgesehen ist; und

Abbildung 7

eine weitgehend Abbildung 2 entsprechende Vorrichtung, die der kombinierten thermischen und Elektronenstrahl-Härtung dient, wobei letztere in einer der Preßvorrichtung nachgeschalteten getrennten Einheit durchgeführt wird.

Exemplary embodiments of the device according to the invention are explained in more detail below with the aid of a schematic drawing:

illustration 1

a device for the continuous production of chipboard or fiberboard using a pre-press and with double-sided electron radiation;

Figure 2

a device as in Figure 1, but the main press is different;

Figure 3

a device corresponding to Figure 1 but without a pre-press;

Figure 4

a device corresponding to Figure 3 with one-sided electron radiation;

Figure 5

a device corresponding to Figure 1, in which, however, a holding pressure is applied to the compacted plate in the area of electron radiation;

Figure 6

a device with a press, which is formed by a deflection drum of large diameter, with this cooperating pressure rollers and a printing belt, wherein a single-acting electron beam device is provided; and

Figure 7

a device largely corresponding to Figure 2, which is used for combined thermal and electron beam curing, the latter being carried out in a separate unit connected downstream of the pressing device.

The statements according to Figures 1 to 4 do not correspond to the invention according to the Claims.

According to Figure 1, a container-shaped spreader 1 is provided, which with Electron radiation hardenable binder glued cellulosic material 2 (wood chips, Wood fibers). This material 2 is in a uniform distribution on a continuous revolving band 3 poured on which a loose scattering layer 4 forms. This is pre-compressed in a pre-press 5.

The pre-press 5 has an upper pre-compression band in a mirror-symmetrical design and arrangement 6 and a lower pre-compression band 7, which via deflection rollers 8, Tension rollers 9 as well as top pressure rollers 10 and bottom pressure rollers 11 circulate. The conveyor belt 3 with the scattering layer 4 runs between the pre-compression belts 6 and 7, which approach each other in the direction of transport, which is indicated by the in Transport direction decreasing distance between the opposite ones Form rollers 10 and 11 is reached. In this way, a diffusion layer 4 is formed thinner precompacted layer 12.

The conveyor belt 3 runs over deflection rollers 13 and a rigid table 14 in the area the task of the material 2 and support rollers 15 behind the pre-press 5. In the direction of transport behind the pre-press 5 there is a pressing device 16 (main press), which is formed by an upper drum 17 and a lower drum 18, the press nip 19 run through from the upper run of the conveyor belt 3 with the pre-compressed layer 12 is, so that from this the compressed layer 20 is formed, which with the conveyor belt 3rd runs over the support rollers 21, the compressed layer 20 due to springback receives a slightly larger thickness than corresponds to the dimension of the press nip 19.

The conveyor belt 3 with the compressed layer 20 then passes through an electron beam device 22, which has an upper electron beam accelerator 23 and a lower electron beam accelerator 24 includes facing each other. By the sudden Hardening of the binder mixed with the material 2 by electron radiation a hardened layer is formed on the electron beam device 22 from the compressed layer 20 Plate 25 (endless plate), the support rollers 26 of the final production (cross cutting, Surface grinding) is supplied.

The device according to Figure 2 largely corresponds to the device described above match. In this respect - as with the following illustrations - the same Reference numerals are used and will not be described again. The difference to Figure 1 is that instead of the pressing device 16 a different trained press device 27 is provided. This press device 27 is after Conti-Roll process performed while working, but can be carried out significantly shorter than it is usually the case with thermal curing processes.

The pressing device 27 comprises an upper belt 28 and a lower belt 29, which are connected to deflection rollers 30 circulate. Within the upper band 28 is an endless sequence of upper ones Rolling rods 31 are provided, and in a corresponding manner is within the lower band 29th an endless row of lower roller bars 32 is provided, the roller bars each over Rotate pulleys 33. The upper roller bars 31 is an upper pressure plate 34 with upper ones Assigned printing cylinders 35, while the lower roller rods 32 a lower pressure plate 36 is associated with lower pressure cylinders 37. The pressure plates 34 and 36 are in Transport direction inclined slightly converging, so that a tapering press nip 38 results which is traversed by the conveyor belt 3 with the pre-compressed layer 12. By appropriate pressurization of the pressure cylinders 35 and 37, the Effect coming pressure of the pressing device 27 and thus the compression process adapt to the respective conditions and specifications.

In comparison to Figure 1, the pre-press 5 is missing in the device according to Figure 3. Accordingly, the scattering layer 4 is fed directly to the pressing device 16 and into the compressed layer 20 converted.

The device according to Figure 4 differs from that of Figure 3 only in that a simplified electron beam device 39 is provided, which only one Has electron beam accelerator 23, the compressed layer 20 only from the top irradiated here. Of course it would also be possible to have radiation exclusively from the Bottom to be provided.

The device according to Figure 5 is a further development of the device according to Figure 1, one in the region of the electron beam device 22 from the conveyor belt 3 is provided with the compressed layer 20 holding pressure device 40 which has two holding conveyor belts, namely an encircling upper holding conveyor belt 41, which is guided over deflection rollers 42 and, as shown, the pressing device 16 passes through, and a lower holding conveyor belt, which is formed here by the conveyor belt 3.

In the exemplary embodiment according to Figure 5, the area of the electron beam device 22 a holding pressure lying below the pressing pressure of the pressing device 16 on the compressed Layer 20 applied. For this purpose, a vacuum device 43 for forming one of the compressed layer 20 passed through vacuum zone 44, so that the outside atmospheric pressure acting on the conveyor belts 3 and 41 delivers the holding pressure which a thickness of the compressed layer 20 corresponding to the press nip 19 during the electron irradiation backs up.

In the device according to Figure 6, the conveyor belt 3 and the table 14 are through a short feed conveyor 45 replaced. This leads to the scattering layer 4 Press device 46, to which a deflection drum 47 of large diameter belongs whose half circumferential length is a press belt 48 with radial spacing to form a long one Press nip 49 rotates with. The press belt 48 is on the back in the area of the press nip 49 supported by pressure rollers 50 which apply the compression pressure. The press belt 48 runs over an upper deflection pressure roller 51 and a lower deflection pressure roller 52, which the Deflection drum 47 are arranged adjacent and according to the arrows can be preloaded, and via further deflection rollers 53.

At the end of the press nip 49 is an electron beam device 54 with an electron beam accelerator 55 arranged, the last between the two in the circumferential direction Pressure rollers 50 is placed. In addition, an opposing electron accelerator could be arranged within the deflection drum 47 (not shown).

The indicated displacement of the deflection pressure rollers 51 and 52 allows a corresponding one Apply tension to the press belt 48. The actual compaction of the spreading layer 4, as shown, takes place mainly in the area of the lower deflection pressure roller 52 and possibly also in the area of the front pressure rollers 50 in the circumferential direction of the rear pressure rollers, the press belt 48 at a constant distance from the deflection drum 47 is held, the press belt 48 exercises in the area of the electron beam device 54 only a holding function to prevent the compressed layer 20 from springing open To prevent hardening in the area of the electron beam accelerator 55. The hardened Plate 25 (endless plate) is then removed via support rollers 26.

The device according to Figure 7 is largely the one already based on Figure 2 described device with a comparatively short pressing device 27 ' (Conti-Roll process). Deviatingly, the material is loaded 2 ', the not only radiation-curable binders but also thermally curable binders added is sufficient for a form-stabilizing partial hardening (pre-hardening). Accordingly heat is supplied via the pressure plates 34 and 36 to the pressing device 27 'and Partial curing is already brought about by reaction of only the thermally curable binder. The result is a partially hardened endless plate 56, which is shown in the usual manner is cut to length by means of a diagonal saw 57 into partially hardened individual plates 58, which in one Intermediate stack 59 are deposited without being already radiation-hardened.

Rather, radiation curing takes place in a separate unit 60 connected downstream Electron beam device 61, with an upper electron beam accelerator 62 and a lower electron beam accelerator 63, between which the partially hardened Single plates 58 are guided on support rollers 64, so that fully hardened individual plates 65 arise, in which the radiation-curable binder now also reacts chemically has, so that the individual plates 65 have their final strength. You will then be on one Finished stack 66 filed.

With a corresponding arrangement of the electron beam device 61, the radiation curing could also directly behind the pressing device 27 'before or after cutting to length the diagonal saw 57 (not shown). This arrangement is particularly suitable for the process variant of partial thermal hardening of the two cover layers and one Final hardening of the material using electron beam energy. The application of a holding pressure In the area of the electron beam, a device shown in Figure 5 can be used 40 done.

Claims (23)

1. Method of continuous production of composite woodlike boards, using woodlike material, an electron-beam-curing binder, compressive pressure for compaction and electron beam energy for curing, with spatial separation of the process of compaction from the process of introducing the electron beam energy, characterized

   a) in that the woodlike material is used in the form of a web of chips or fibres and

   b) in that the state of compaction of the web following compaction and before and during electron beam curing is secured by applying a holding pressure to the web.
2. Method of continuous production of composite woodlike boards, using woodlike material, an electron-beam-curing binder, compressive pressure for compaction and electron beam energy for curing, with spatial separation of the process of compaction from the process of introducing the electron beam energy, characterized

   a) in that the woodlike material is used in the form of a web of chips or fibres,

   b) in that not only the electron-beam-curing binder but also heat-curing binder is admixed to the woodlike material and

   c) in that in the course of compaction there is first of all a dimensionally stabilizing partial heat-cure before full curing is accomplished by means of the electron beam energy.
3. Method according to Claim 2, characterized in that the partial heat-cure is confined to the outer layers of the shaped article.
4. Method according to Claim 2 or 3, characterized in that, based on the dry mass of the material, the fraction of the heat-curable binder is between 0.5 and 20% by weight, preferably between 1 and 10% by weight, and the fraction of the radiation-curable binder is between 0.5 and 20% by weight, preferably between 1 and 10% by weight.
5. Method according to one of Claims 2 to 4, characterized in that the heat-curing fraction is a binder such as phenol-formaldehyde resin, tannin resin, urea-formaldehyde resin, melamine-formaldehyde resin or mixtures or mixed resins thereof.
6. Method according to one of Claims 2 to 4, characterized in that the heat-curing fraction is a binder such as isocyanate resin.
7. Method according to Claim 6, characterized in that the isocyanate resin is a PMDI.
8. Method according to Claim 2, characterized in that the material is admixed not only with the binder which cures by electron beam energy but also with peroxide, and in that, with the shaped article under external pressure, the binder is first of all given a dimensionally stabilizing partial cure in the form of free-radical curing by means of peroxide, by supplying heat, before full curing is accomplished by means of electron beam energy.
9. Method according to Claim 8, characterized in that the peroxide used comprises organic peroxide.
10. Method according to one of Claims 1 to 9, characterized in that the binder used which cures by electron beam energy comprises a synthetic resin which includes an unsaturated oligomer.
11. Method according to Claim 10, characterized in that a monomer is added as a cure-accelerating crosslinker to the oligomer.
12. Method according to Claim 10 or 11, characterized in that the fraction of binder, based on the dry mass of the material, is between 0 and 30% by weight, preferably between 1 and 10% by weight, for the unsaturated oligomer and between 0 and 20% by weight, preferably between 0 and 5% by weight, for the crosslinker.
13. Method according to Claim 11 or 12, characterized in that the crosslinkers used comprise monomers containing mono-, bi-, tri- or polyfunctional groups or a mixture of these monomers.
14. Method according to Claim 13, characterized in that the functional groups of the monomers are composed of monomers with vinylic unsaturation.
15. Method according to one of Claims 10 to 14, characterized in that the unsaturated oligomers used comprise synthetic resins having polymerizable C-C double bonds, from the group of the unsaturated polyester resins, ether acrylates, epoxy acrylates, urethane acrylates, or of the unsaturated acrylate resins.
16. Method according to one of Claims 1 to 15, characterized in that it is used to produce chipboard, fibreboard or OSB boards.
17. Device for continuous production of composite woodlike boards, having a conveyor belt (3, 45) for the material, a downstream compression means (16, 46) and a downstream electron beam installation (22, 54), characterized in that in order to accomplish the method according to Claim 1

    a) the conveyor belt (3, 45) is assigned a broadcasting means (1) for applying the material and

    b) in the region of the electron beam installation (22, 54) there is a holding pressure means (40; 47, 48) for applying a holding pressure which holds the compacted boardlike article (20) at the target thickness during irradiation.
18. Device according to Claim 17, characterized in that the holding pressure means (40; 47, 48) comprises at least one holding conveyor belt (41; 48) which can be pressed against the boardlike article (20).
19. Device according to Claim 17 or 18, characterized in that the holding pressure means (47, 48) comprises a guide pulley (47) and a holding conveyor belt (48) passed around the said pulley (47), which bear against opposite sides on the boardlike article (20).
20. Device according to Claim 18 or 19, characterized in that the holding pressure means (40) comprises a vacuum installation (43) which is connected to the interspace (vacuum zone 44) traversed by the boardlike article (20) so that atmospheric pressure presses against the holding conveyor belt (41).
21. Device for continuous production of composite woodlike boards, having a conveyor belt (3) for the material, a compression means (27') and a downstream electron beam installation (61), characterized in that in order to accomplish the method according to Claim 2

    a) the conveyor belt (3) is assigned a broadcasting means (1) for applying the material and

    b) the compression means (27') is assigned a heating installation for introducing heat into the compacted boardlike article (12).
22. Device according to one of Claims 17 to 21, characterized in that the electron beam installation (22, 61) has two electron beam accelerators (23, 24; 62, 63) which are arranged on opposite sides of the conveyor track.
23. Device according to one of Claims 17 to 22, characterized in that the electron beam installation (61) is configured as a separate unit (60) downstream of the compression means (27').

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