FI121779B - A method for manufacturing a wood plastic composite material - Google Patents

Description

METHOD FOR THE MANUFACTURE OF WOODEN PLASTIC COMPOSITE MATERIAL

The present invention relates to a process for the production of a wood-plastic composite material, wherein the wood material is a heat-modified wood material which is mixed with the plastic material, and the wood-plastic composite material is prepared from the mixture.

Wood materials, plastics and binders are used as raw materials for wood-plastic composite materials. The materials and substances are mixed together and the resulting pulp is suitably modified at the appropriate temperature to produce the desired product.

Wood-plastic composite materials are intended to provide a variety of adjustable wear-resistant products, replacing e.g. products made from impregnated timber. The advantages of wood-plastic composite material are good resistance to both humidity and impact, environmental friendliness and its recyclability.

15 The wood material of wood-plastic composite material is usually used in the form of chips or chips of normal wood. It is also proposed to use heat-treated wood as chips and chips as wood material. Suitable plastics materials are generally suitable plastic materials such as polyethylene or polypropylene. It is known that the moisture resistance and hardness of a wood-plastic composite are influenced by the properties and concentrations of both the wood material and the plastic material.

In the manufacture of heat modified wood material, the wood material is subjected to high temperatures and, for example, the use of water vapor or can be subjected to various pressures. The purpose is to effectively dry the wood material and to remove its moisture content without substantially changing the dimensions of the wood. In the process, the wood provides useful properties. Heat modified wood pulp material has low humidity and is barely able to absorb moisture and is | well used for eg. for different humid environments. The properties of heat modified qq wood differ greatly in so-called. the properties of normally dried wood.

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§ 30 The disadvantages of existing wood-plastic composite materials are the high amount of plastic material, which has the disadvantage of the "plasticity" of the end product, the high cost of the plastic in the price of the product and, depending on the plastic material, the disposal problem. Another problem is that if the wood material is high, it may react to changing humidity conditions and other external conditions, thus failing to achieve a well-formed shape and size in demanding operating conditions.

It is an object of the invention to provide a process for making wood-plastic composite material which eliminates the problems associated with current methods and products. In particular, it is an object of the invention to provide a process which is inexpensive in terms of material costs, can be manufactured in a more cost-effective manner, and provides a product which is more stable and woody.

The object of the invention is achieved by a process for the production of a wood-plastic composite material 10, which is characterized by what is claimed.

The process of the invention uses a wood-plastic composite material having a wood material content, i.e. a fiber content of about 60-95% by weight of the composition, and milling the thermo-wood material into a powdery material and then mixing it with a bonding material such as plastic material or the like. In the process of the invention, the warm-ash 15 material is ground to a very fine powder. It should be noted that the heat treatment and the control of its process technology and workmanship produce a very fine and floury pulp which is not obtained from ordinary wood by normal methods and normal costs.

The basic idea of the invention is to eliminate the above-mentioned drawbacks by using a very fine-grained raw wood raw material. The properties of heat wood are well suited for this purpose, since the heat wood is homogeneous and uniform and in this form hardly changes due to moisture and other external factors. It is also an advantage that in the production of wood-plastic composite material, the use of by-product heat-wood material and the powder formed therefrom can be used as a by-product. Thus, the powder formed in the production of the heat wood can advantageously be utilized directly on the by-product line of the production of the heat wood, as such, in a very cost-effective manner. In addition, the productive plant can utilize the non-impure material 30 mm left over in the production of the heat wood by grinding it into a suitable powder. It is also possible to utilize such wood material, so-called. junk that would otherwise not even be heat treated, treat it 00 § normally in the heat wood process, grind it into powder and use this

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as wood material. This way all the raw materials can be utilized.

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The process according to the invention produces a heat-wood-based pulp with the necessary amount of plastic material or the like added as a binder, which, by suitable combination and different processing methods, provides the optimum raw material for various uses which have traditionally not been used. The test specimens have been produced with extremely clean, weather-resistant, dimensionally and shape-resistant, woody products - with a small amount of plastic material. Also, the wood's own extracts released during heat treatment can be fed as a binder to the pulp. The powder can be made from solid wood, resulting in good cost efficiency. A further advantage is that the process using a raw material of high quality according to the invention can be used to produce a variety of products to replace existing products.

The process employs plastic materials known per se and previously used in wood-plastic composite materials.

The amount of plastic material used in the process of the invention is relatively small and may preferably be from about 0% to about 40% by weight of the composition, depending on the intended use. The content of the other binder may preferably be from 0 to 10% by weight. Thus, the process according to the invention achieves a significant cost advantage since the proportion of cheaper fiber raw material is significantly higher than before, but still achieves the same good properties in terms of moisture resistance and dimensional stability as when using a conventional fiber raw material and a larger plastic portion. The price of a plastic raw material is about ten times that of a fiber raw material. This makes the product affordable and manufacturing cost effective. The product retains a woody appearance, is a natural and ecological appearance and the color of the product can be changed by heat treatment to the degree of heat treatment without the need for dyes. In addition, the product is durable and easy to work with and has a smooth surface. Disposal of the product after use is not as problematic as in products with a higher V content. Another advantage is that when the final product has a high proportion of wood, the heat and cold conductivity of the product is closer to the normal | 30 thermal conductivity properties of wood than in a product with a high proportion of plastic material jjq.

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§ Polyethylene and others may be used as binder for certain applications.

£ 3 corresponding blowing agents / binders.

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In solid wood production, the LW process allows for accelerated processing without weights, disregarding the deformation of the wood, and grinding without wetting and balancing. The raw material then becomes junk.

In various embodiments of the invention, the amount of wood material and plastic material may vary within the limits set forth above, depending on the intended use and requirements.

As a working application example, an application containing 80% by weight of heat-treated wood material powder, 18% by weight of polyethylene or polypropylene resin and 2% by weight of a coupling agent maleic anhydride can be presented. Comparative tests have shown that the performance of the material alloy at this alloy ratio 10 is at a very different level and much better than that of the material alloy made from ordinary wood pulp. In another embodiment, 90% by weight of heat-treated wood material powder, 9% by weight of a plastic raw material and 1% by weight of another binder are used. When the wood material content is high (e.g. 80-95% by weight), the product is more woody in character and appearance than if the wood material-15 content is low.

In other embodiments of the process, the proportion of wood material may vary from 60 to 95% by weight, the proportion of plastic material may vary from 0 to 40% by weight and the content of other binder may vary from 5 to 10% by weight.

In the process of the invention, a suitable wood material is used.

In the heat treatment process, wood material is heated for different periods of time at different temperatures. In one method, the wood is placed in a heat treatment room which is raised rapidly at a temperature of about 100 ° C, and then the temperature is raised to -10 ° C. up again about 120-130 ° C. In the next step, the temperature is raised to about 210-220 ° C for a while. At the end, the wood is cooled to C 1 V and the temperature lowered to a controlled temperature. This process takes about o 36 hours. In order to obtain good quality thermo-modified wood material, the timber must be handled carefully and the temperatures and processing times constantly monitored.

cv cv § 30 After the heat treatment process, the heat modified timber is inspected and

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° Any damaged or discolored timber is removed. Thereafter, the heat modified wood blade is processed as desired according to the end use. At this stage, the production becomes pieces of wood, a bunch of sawdust and sawdust.

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In the process according to the invention, these heat-modified wood production residues, i.e. pieces of wood, cutter sawdust, sawdust, broken wood, discolored wood, are taken as raw material for the process and utilized because they are heat-treated wood. In the method, said. the wood 5 is ground to a fine powder, plastic material and / or other alloy material is added thereto, the mixture is heated to a suitable temperature and formed into products of the desired shape.

It is also possible to heat-treat the so-called. obsolete timber, that is, timber that does not provide appropriate products. Such timber is e.g. sa-10 fun waste, branches, tops. When such wood is subjected to heat treatment, it is essential that the wood be capable of being dry, but that it may develop cracks or deformation during drying. Hereby, the heat treatment time can be considerably reduced and the heat treatment can be carried out, for example, in about 18 hours, which is about half the time of the above heat treatment process. In this way, wood material can be obtained in a cost-effective and fast manner, which can be used as a raw material for the process of this application.

The invention is not limited to the preferred embodiments shown, but may vary within the scope of the inventive idea of the claims.

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Claims (3)

1. A process for producing a composite material, in which the method is used as heating wood material as wood material which is mixed with plastic material, and from the mixture is made wood-plastic composite material, characterized in that the heating wood material is ground into finely divided powdery form and then mixed with plastic material. , and that the proportion of the wood material in the wood-plastic composite is about 80-95% by weight of the mixture weight. Process according to claim 1, characterized in that the proportion of plastic material is about 9-18% by weight of the mixture weight. 10 Process according to Claim 2, characterized in that the proportion of binder other than plastic material is 0-10% by weight of the weight of the mixture. o δ CM CM δ X cc CL 00 CM CM O 00 O O CM