JPS62138204A - Manufacture of wooden series molded body - Google Patents

Abstract

PURPOSE:To obtain a molded body prominent in properties such as mechanical property, appearance or the like, by a method wherein wooden series molding material is sucked by a holding device having porous sucking surface to form a preliminary molded body on the sucking surface, subsequently, a part, to be drawn by deep drawing upon hot-press molding is strongly sucked further. CONSTITUTION:Wood fibers 18 are thrown into an accumulating vessel 19 while air is blown into the vessel through holes 21 provided on a porous plate 20 to flow the wooden fibers. The wood fibers 18 are adhered to a wire net 25 in a holding device 24 to form a preliminary formed body M2. The inside of the holding device 24 is partitioned by partitioning plates 26 and the degree of suction of respective chamgers is controlled by vacuum lines 27, 28 29 to regulate the properties, such as the thicknesses of respective parts of the prelimi nary formed body or the like. Subsequently, the preliminary formed body M2 is moved onto a mold surface 33 and a part M3, to be drawn deeply, is further strongly sucked to enhance the mutual entangling of the wood fibers. The break age of a deep drawing section in next hot-press molding process is prevented in such manner and molding property may be improved.

Description

[Detailed description of the invention] (Field of industrial application) The present invention relates to a method for producing a wood-based molded product, and more specifically, a method for directly producing a heat-compression molded product using a wood-based molding material to which a binder has been added. It is about the method.

[Conventional technology]

Generally, a wood-based molded body is manufactured by compression molding a wood-based molding material, such as wood fiber, obtained from a raw material such as wood, utilizing its own bonding properties. This wood-based molded body is a so-called hardboard, which is more uniform in material than plywood, is lighter, has fewer defects, has a smooth surface, and is highly heat resistant, water resistant, and moisture resistant. It is used as an interior material for construction because it is strong despite its thickness.
It is widely used as a material for furniture, automobile interior materials, cabinets for televisions and stereos, etc.

The method for producing this wood-based molded product is, for example, by steaming and defibrating wood chips to extract wood fibers, mixing the wood fibers with, for example, synthetic resin and cellulose paper and dispersing them in water, followed by pressure filtration. and pressing (so-called paper making)
Then, the resulting mat (soft fiberboard) is molded using a wet molding method, or the wood fiber obtained by steaming and defibrating wood is mixed with a binder such as a synthetic resin. Examples include a dry matting method in which the material is then deposited in a layered manner, hot roll pressed to form a molding mat, and this molding mat is heat compression molded.

To explain an example of the dry matting method, first, wood chips are placed in a steaming tank of a decomposition machine and steamed at 160 to 180 degrees Celsius to soften the chips and make it easier for the wood fibers to loosen from each other. After that,>! The wood fibers are supplied to a four-way disk and loosened by the fibrillation disk to obtain wood fibers. After drying the defibrated wood fibers with hot air, they are made into long fibers that can be easily deformed from the bent part during molding, i.e., to improve deep drawability.・As moldable resin, polypropylene range λ fiber 7chi, phenolic thermosetting resin and heat iiJ ifi are used.
5 to 10 parts of a binder made of a synthetic resin or the like, 1 to 5 parts of a water repellent such as rosin or paraffin, and a shaving material are thoroughly mixed.

Next, this wood fiber with a binder added thereto is deposited in layers and hot roll pressed to a thickness of lO~4 as shown in Figure 8.
To form a mat Ml of approximately 0.0 cm, which is easy to carry.

Next, the above-mentioned molding pine) Ml is cut into pieces slightly larger than the shape of the completed wood-based molded body, and is subjected to heat compression molding using a mold to obtain a wood-based molded body.

[Problem that the invention seeks to solve]

However, the conventional method for producing a wood-based molded article as described above has the following problems.

That is, in the dry matting method, in order to easily feed the wood fibers into a hot compression mold, there are two steps: forming the wood fibers into a mat that is easy to handle, and shaping this mat into a predetermined shape. It requires many manufacturing steps and is complicated, and in order to make the wood fibers into a mat, a binder such as a thermoplastic resin is required. Also, when compression molding the mat, the mat is pulled in by the receptacle, so it is necessary to cut the mat slightly larger than the finished molded product, which results in wasted cutting and derived materials that are cut off after molding. , yield is poor, production cost increases,
There is a problem in that a cutting process is required after molding. Furthermore, when manufacturing a molded product with a deep-drawn part, in addition to wood fibers, long fibers such as hemp or thermoplastic resin nets, which are expensive raw materials, are used as the mat material in order to improve the deep-drawability of the mat. If non-adhesive hemp fibers are used, it is necessary to add a binder such as a thermosetting resin in a fairly large amount, which also increases the cost.

In addition, when producing a molded article having a deep-drawn part, if the mat contains a large amount of wood fibers, the mat may be softened with steam to improve deep-drawability.
It must be preformed into the shape of the molded body. This not only increases the number of processing steps, but also reduces the thickness of the corners where the mat has been stretched due to deep drawing.
If this preform is compression-molded as it is, there is a problem that the thinned corners and the like will have a low density, and the strength of the deep-drawn parts such as the corners of the completed wood-based molded body will be reduced.

In addition, when a large plate-shaped body with a deep-drawn part is formed using a single mat, the mat is drawn into the deep-drawn part, causing it to tear or fold around the deep-drawn part, resulting in increased wall thickness and blistering. As a result, the desired molded product cannot be obtained. For this reason, it is necessary to apply a patch material made of the same material as the material from which the mat was formed to the deep-drawn portion and then perform compression molding, which makes the molding work complicated.

-The wet forming method uses a large amount of water and requires large-scale wastewater treatment equipment. Because the fibers of the mat are entwined with each other,
It is as difficult as or more difficult than the dry matting method described above, and has the same problem 1, for example, the deep drawing part or its surroundings become thinner or tear.

Therefore, a mixture of wood fiber and binder is used.
It is conceivable to heat compression mold by directly feeding the wood fibers into the mold without forming a mat, but if the wood fibers and binder are mixed and left to stand, the wood fibers will stick to each other and clump together. It is difficult to fill the mold without uneven density, and a molded product with excellent strength cannot be obtained.

The present invention is intended to solve the above-mentioned problems in the prior art, and its objectives are to: 1) improve workability, reduce production costs, and produce molded products with excellent properties such as mechanical properties and appearance; It is an object of the present invention to provide a method for manufacturing a wood-based molded article that can be obtained.

[Means for solving problems]

That is, the method for manufacturing a wood-based molded article of the present invention is as follows.

A wood-based molding material to which a binder has been added is sucked by a holding device having a porous suction surface to form a preform on the suction surface, and the holding device that has suctioned and held the preform is used as a mold. It is characterized in that the preform is moved above the mold surface, and the part to be deep-drawn during hot compression molding of the preform is further strongly suctioned, and then dropped onto the mold surface, and then hot compression molded.

The wood fiber used in the present invention is obtained by defibrating wood etc., and the wood is not particularly limited, such as Japanese red pine, Japanese red pine, etc.
Cedar, lauan, beech, etc. can be used, and rice straw, flax husks, bagasse, etc. can also be used.

The method of knotting wood or the like to form wood fibers is not particularly limited, and methods commonly used by those skilled in the art can be used. For example, steaming under pressure and mechanical defibration under the same pressure. Examples include a method of steaming and then mechanically forming 'Pi6 fibers under normal pressure.

The binder that adds 'lfS to the wood fibers is a substance that binds the wood fibers by overcoming the bonding properties of the wood fibers themselves, and its components and i! is not particularly limited as long as wood fibers can be integrally bonded by thermal compression to form a molded product with desired strength. The component may be a natural polymer or a synthetic resin, and examples thereof include natural polymers such as starch, thermoplastic resins such as coumaron resin, thermosetting resins such as phenol resin, and urea resin. Preferably, water-soluble phenolic resins are used. Therefore, these may be used alone or as a mixture.

It is preferable to add the binder to the wood fibers immediately before forming the preform. If you add a binder to wood fibers and leave it for a while, the binder has some tackiness and adhesive properties, so the wood fibers will solidify into a lump, and when fed into the mold, the wood fibers will not be filled. A place with low density is created,
This causes problems such as a decrease in the strength of the molded product after hot compression molding.

Furthermore, in addition to the binder, additives such as a water repellent agent and a mold release agent may be added to improve water resistance.

The porous suction surface of the holding device can be formed, for example, by a metal plate or plastic plate with a large number of holes, or a wire mesh.

The size, shape, and other properties of the holding device are selected in accordance with the size and shape of the intended wood-based molded article. The holding device may be, for example, box-shaped having a bottom part and a side part, and the above-mentioned suction surface part is provided at an intermediate part between the upper end and the lower end of the side part.

The space between the suction surface part and the bottom part is divided into a plurality of parts by, for example, a partition plate provided parallel to the side part. Suction piping is connected to each of the divided spaces so that the suction state can be controlled independently of each other. The partition plate is preferably arranged so as to increase the degree of suction in the portion to be deep drawn during molding of the preform formed on the suction surface.

Therefore, the arrangement of the partition plates is determined depending on the properties of the wood-based molded product to be manufactured, especially the shape of the portion to be deep drawn.

During hot compression molding of the preform, the part to be deep drawn is strongly suctioned, the suction is released and the preform is dropped onto the surface of the mold, and then hot compressed to unite the wood*fibers and molded. However, the conditions for this molding are appropriately determined depending on the materials used such as the Kigataka fiber and binder, the shape of the molded product, the required strength, etc., and are not particularly limited, but for example, the molding temperature is 100 to 200 ° C. Molding pressure 20-80Kg/cm'
, the molding time can be 20 seconds to 10 minutes.

[Effect]

In the method for producing a wood-based molded article of the present invention, wood fibers with a binder added thereto are heat compression molded, so the binder added to the wood 4Rfa supplements the bonding properties of the wood fibers themselves, making the wood fibers integrally formed. Can be combined.

In addition, since the area to be deep-drawn during hot-press molding of the preform is strongly suctioned, the intertwining of the wood fibers in this area becomes stronger, and the drawing of the wood fibers into the deep-drawn area during forming is improved. To prevent breakage at a deep drawing part and to improve the shape of a molded article.

〔Example〕

An embodiment of the present invention will be described below based on the drawings.

Although this embodiment is an example in which the present invention is applied to a door trim substrate having an armrest of an automobile, the present invention is not limited to this.

First, the process of manufacturing wood fibers will be explained.

As shown in Figure 6, chips l, which are small pieces of wood
is put into the hopper 3 of the cracker 2, and supplied to the steaming tank 5Vc by the screw feeder 4 provided at the bottom of the hopper 3. Steam 6 at a temperature of 160 to 180°C is supplied from the top of the steaming tank 5 to steam the Teppu 1 to soften it so that the fibers can be easily defibrated, and the steamed Teppu 1 is fed from the bottom of the steaming tank 5 to a screw feeder. 7 to the solution 1 disk 8. Then, the tep l is defibrated into wood fibers 9 by a defibrating disk 8 driven by a motor 10'. The wood fibers 9 defibrated in this manner are supplied to a dryer 12 shown in FIG. 7 via a pressure feed pipe 11 by a pressure feeder 1°. The above damp tree x4. The fibers 9 are passed through a meandering drying c#t 15 together with the hot air 14 supplied from the dryer 13, and sent to the cyclone 16 while being dried.The cyclone 16 removes the hot air containing moisture 17 and fine powder, and the dried wood fibers are dried. Get 18.

Next, the wood'X-reinforced fibers 18 are placed in a composting chamber η19 shown in FIG. 2, and air is blown through the holes 21 provided in the perforated plate 20 to make them flow. Note that 22 is a support part, 23 is an air inlet, and the arrow in the figure indicates the direction of air flow.

The flowing wood fibers 18 are sucked and adhered onto the wire mesh 25 of the holding device [24] to form a preform M2. The inside of the holding device 24 is divided into a plurality of rooms by a partition plate 26, and the degree of vacuum in each room is adjusted by vacuum lines 27, 28 and 29, and the part of the wire mesh 25 that forms part of the wall of each room is controlled. The degree of suction is controlled to adjust the properties of the inner ring of each part of the -C preform. Next, the holding device 24 is moved onto the mold surface 33 of the lower mold 32 shown in FIG. 1 by the cylinders 30 and 31 while the preform M2 is being sucked and held.

Next, the portion M3 that is largely deformed during molding of the preform M2, that is, the portion M3 to be deep drawn, is further strongly sucked to strengthen the intertwining of the wood fibers.

Thereafter, the suction is weakened or stopped, and the mold is dropped onto the mold surface 33 of the lower mold 32, as shown in FIG. Then, the hot plate 34
The lower mold 32 and upper mold 35 heated to ~200° C. are fitted together by lowering the upper mold 35. At this time, gas is generated, so the mold is opened to release the gas, and the upper and lower molds are fitted together. After repeating the preliminary compression and degassing several times in this way, the upper mold 35 and lower mold 3 are assembled as shown in FIG.
Compress with 2. M2' indicates a derived material. Next, the mold was opened and the product was taken out to obtain a wood-based molded product M4 shown in FIG.

〔Effect of the invention〕

As described above, the method for producing a wood-based molded body according to the present invention involves sucking a wood-based molding material to which a binder has been added using a holding device having a porous suction circuit, and placing a preform on the suction surface. The preform formed and held by suction in a holding device is moved above the mold surface of the mold, and the part of the preform to be deep drawn during hot compression molding is dropped onto the hind mold surface, which is further strongly suctioned. This is followed by hot compression molding, which strengthens the intertwining of the wood-based molding material, e.g., wood fibers, in the area to be deep-drawn, which prevents breakage at the deep-drawn area and improves formability, as well as improving the mechanical properties of the molded product. It is possible to improve properties such as appearance and appearance.

In addition, compared to the conventional matting method, there is no need for the process of matting Kiga Tairui, the process of cutting the mat, and the equipment involved, which improves workability and productivity during molding, and also eliminates the cutting waste of the mat. Also, since there is no derivative material during molding, the yield rate can be improved and raw material costs can be reduced.

Furthermore, since a preform is formed by a holding device without matting the wood-based molding material and is fed into the ll1f welding mold, it is easy to adjust the filling amount of the wood-based molding material, that is, the packing density, and the wall thickness of the preform. It is possible to easily obtain a wood-based molded article with desired properties.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view showing a state in which a preformed body suctioned and held by a holding device is moved onto the mold surface of a mold, in an embodiment of the method for producing a wood-based molded body according to the present invention; FIG. 2 is a sectional view showing a state in which a preform is formed on the suction surface portion of the holding device in the embodiment shown in FIG. 1; FIG. 3 is a sectional view showing a state in which a preform is dropped onto the mold surface of a lower mold in an embodiment of the method of the present invention, and FIG. 4 is a state in which the preform shown in FIG. 3 is thermally compressed. FIG. FIG. 5 shows F! according to an embodiment of the method of the present invention. Fig. 6 is a perspective view of an example of M-fine used to obtain wood fibers that are the raw material for wood-based moldings, and Fig. 7 shows a dryer for wood-based fibers. FIG. 8 is a perspective view of an example of a mat made of wood Ix fibers. In the figure, 18... Wood fiber 19... Depositing container 24... Holding device 32... Lower mold 33... Mold surface 35. ... Upper mold M2 ... Preform M3 ... Portion to be deep drawn M4 ... Wooden molded object #! ? Applicant Toyota Motor Corporation Figure 3 Figure 41 (1 Regrettably Figure 5 Figure 6-4 Figure 7 Figure 8

Claims (1)

[Claims] A wood-based molding material to which a binder has been added is sucked by a holding device having a porous suction surface to form a preform on the suction surface, and the holding device that has suctioned and held the preform is used as a mold. A wood-based molding characterized in that the preform is moved above the mold surface, and the part to be deep-drawn during hot compression molding of the preform is further strongly suctioned, and then dropped onto the mold surface, and then hot compression molded. How the body is manufactured.