JPH0661731B2 - Method for manufacturing wood-based molded body - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a method for producing a wood-based molding, and more specifically, a method for directly producing a heat compression molding using a wood-based molding material to which a binder is added. It is about.

[Conventional technology]

Generally, a wood-based molded product is manufactured by compression-molding a wood-based molded material obtained from a raw material such as wood, for example, a wood fiber, by utilizing its binding property. This wood-based molded product is a so-called hard board, which is more uniform and lighter in weight than plywood and has fewer defects, and has a smooth surface and excellent heat resistance, water resistance, and moisture resistance. Because of its strength, it is widely used as a material for interior materials for construction, furniture, interior base materials for automobiles, and cabinets for TVs and stereos.

As a method for producing this wood-based molded body, for example, wood chips are steamed and defibrated to take out wood fibers, and the wood fibers are mixed with, for example, a synthetic resin and cellulose paper and dispersed in water, followed by pressure filtration. And pressing (so-called papermaking)
Then, the mat (soft fiberboard) thus obtained is subjected to a heat compression molding method, or a wood fiber obtained by steam defibrating wood or the like is added with a binder such as a synthetic resin and mixed, and then layered. And a hot mat roll to form a molding mat, and the molding mat is subjected to heat compression molding.

Explaining an example of the dry matting method, first, the wood chips are put in a steaming tank of a defibration machine, steamed with steam at 160 to 180 ° C. to soften the chips, and the fibers of the wood are easily loosened from each other. Supply to the fine disk,
The defibrated disc is also loosened to obtain a wood fiber. After the defibrated wood fiber is dried with hot air, it is easily deformed from the flat portion during molding, that is, long fibers for improving deep drawability, such as 17% hemp fiber and polypropylene as a thermoplastic resin necessary for matting. Sufficient with 7% fiber, 5-10% binder made of phenolic thermosetting resin or thermoplastic resin, 1-5% water repellent such as rosin or paraffin, and release agent To mix. Next, the wood fibers to which a binder and the like have been added are deposited in layers and subjected to hot roll pressing to form a mat M1 having a thickness of about 10 to 40 mm and easy to carry.

Next, the molding mat M1 is cut into a shape slightly larger than the shape of the completed wood-based molding, and heat-compression-molded by a molding die to obtain a wood-based molding.

[Problems to be solved by the invention]

However, the above-described conventional method for manufacturing a wood-based molded product has the following problems.

That is, in the dry mat method, in order to easily supply the wood fiber to the heat compression molding die, a step of molding the wood fiber into an easy-to-handle mat and a step of cutting this mat into a predetermined shape are required. The number of steps is large and complicated, and a binder such as a thermoplastic resin is required for matting the wood fiber. Also, when the mat is compression molded, the mat is pulled in by the drawing part, so it is necessary to cut the mat a little larger than the completed molded body,
Cutting scraps and derived materials that are cut off after molding are wasted,
There are problems that the yield is poor, the production cost is increased, and a cutting process after molding is required. Furthermore,
In order to improve the deep drawability of mats when producing molded products with deep drawn parts, in addition to wood fibers as mat materials, long fibers such as hemp and thermoplastic resin nets with high raw material prices are used. It is necessary, and when hemp fibers having no adhesiveness are used, it is necessary to add a binder such as a thermosetting resin in a considerably large amount, which also increases the cost.

Further, in the case of producing a molded product having a deep-drawn portion, when the mat contains a large amount of wood fibers, the mat is softened by steam in order to improve the deep-drawing property, and the shape of the molded product is preliminarily prepared in advance. Must be molded.
For this reason, not only the number of processing steps is increased, but also the corner portions where the mat is extended are thinned by deep drawing, and when this preform is compression-molded as it is, the thinned corner portions are reduced. There is also a problem that the density becomes high and the strength of the deep-drawn portion such as the corners of the completed wood-based molded product decreases.

Also, if a large plate with a deep drawn part is formed with a single mat, the mat will be drawn into the deep drawn part, so that it will be torn or folded around the deep drawn part and the wall thickness will become large and blister etc. Occurs, and the desired molded product cannot be obtained. Therefore, it is necessary to apply a patch material made of the same material as the material forming the mat to the deep-drawn portion and then perform compression molding, which complicates the molding operation.

On the other hand, in the wet molding method, a large amount of water is used for papermaking, a large wastewater treatment facility is required, and a molded product having a deep-drawn portion is manufactured using a matte-shaped papermaking product. Since the fibers of the mat are entangled with each other, it is as difficult as or more difficult than the case of the dry mat method described above, and similar problems, for example, the problem that the deep drawing part or its periphery is thinned or torn Have a point.

Therefore, a mixture of wood fiber and binder is
It is possible to directly supply into the molding die without matting and perform heat compression molding, but if the wood fiber and the binder are mixed and left to stand, the wood fibers stick together and solidify. It is difficult to fill the mold into the mold without causing uneven density, and a molded product with excellent strength cannot be obtained.

The present invention is to solve the above problems in the prior art, and its purpose is to improve the workability and reduce the production cost, and to provide a molded article having excellent properties such as mechanical properties and appearance. An object of the present invention is to provide a method for producing a wood-based molded product that can be obtained.

[Means for solving problems]

That is, the method for producing a wood-based molded body of the present invention, a wood-based molding material to which a binder is added is sucked with a holding device having a porous suction surface to form a preformed body on the suction surface,
Moving the holding device that holds the preform by suction above the die surface of the molding die, partially aspirating the preform and then placing it on the die surface, and then performing thermocompression molding. Is characterized by.

The wood fiber used in the present invention is one obtained by defibrating wood or the like, and the wood is not particularly limited. For example, red pine,
Examples thereof include cedar, rawan, and beech, and rice straw, flax shell, bagasse, and the like can also be used.

The method for defibrating wood or the like to form wood fibers is not particularly limited, and a method commonly used by those skilled in the art can be used, for example, pressurizing and steaming, and mechanically defibrating with the pressure as it is. Examples of the method include a method of steaming, and a method of mechanically defibrating at atmospheric pressure.

The binder added to the wood fibers complements the bondability of the wood fibers themselves to bond the wood fibers, and the components and amounts thereof are:
There is no particular limitation as long as the wood fibers can be integrally bonded by heat compression to form a molded product having a desired strength. The component may be a natural polymer or a synthetic resin, and examples thereof include a natural polymer such as starch, a thermoplastic resin such as coumarone resin, a thermosetting resin such as a phenol resin and a urea resin. It is preferable to use a water-soluble phenol resin. And these may be used individually or as a mixture.

The binder is preferably added to the wood fiber immediately before forming the preform. When the binder is added to the wood fiber and left to stand, the binder has some tackiness and adhesiveness,
When the wood fibers are solidified in a lump and supplied into the molding die, a portion having a low packing density of the wood fibers is formed, which causes a problem that the strength of the molded product after the thermal compression molding is lowered.

Further, in addition to the binder, additives such as a water repellent and a release agent for improving water resistance may be added.

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

The properties such as the size and shape of the holding device are selected according to the size and shape of the intended wood-based molded product. The holding device may be, for example, a box-shaped device having a bottom portion and a side surface portion, and the suction surface portion provided at an intermediate portion between the upper end and the lower end of the side surface portion.

The space between the suction surface portion and the bottom portion is divided into a plurality of portions by, for example, a partition plate provided in parallel with the side surface portion. A suction pipe is connected to each of the divided spaces so that the suction state can be controlled independently of each other. The partition plate may be arranged so as to increase the suction degree of a portion that is strongly sucked when forming the preform formed on the suction surface, for example, a portion to be deep-drawn. Therefore, the arrangement of the partition plates is determined in accordance with the shape of the wood-based molded product to be manufactured, particularly the shape of the part that is strongly sucked partially, for example, the part that is to be deep-drawn.

Part of the preform is strongly sucked, then placed on the mold surface, and then heat-compressed to integrally bond the wood fibers together and molding. The molding conditions are such that the wood fibers and binder to be used, etc. It is appropriately determined depending on the material, the shape of the molded body, the required strength, etc., but is not particularly limited, but for example, the molding temperature is 100 to 200 ° C., the molding pressure is 20 to 80 kg / c.
The m ² and molding time can be 20 seconds to 10 minutes.

[Action]

Since the method for producing a wood-based molded article of the present invention heat-compresses the wood fiber to which the binder is added, the binder added to the wood fiber complements the bondability of the wood fiber itself, and the wood fiber is integrated. Can be combined.

In addition, since the preforming is partially strongly sucked, the entanglement of the wood fibers in this portion becomes strong. For example, when the strongly sucked portion is the portion to be deep-drawn during thermoforming of the preform, The drawing of the wood fiber into the deep-drawn portion at the time of molding is improved, breakage in the deep-drawn portion is prevented, and the shape of the molded article is improved.

[Embodiment] An embodiment of the present invention will be described below with reference to the drawings.

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

First, the process of manufacturing a wood fiber will be described. As shown in FIG. 6, a chip 1 which is a small piece of wood is defibrator 2
And put it in the steam tank 5 by the screen feeder 4 provided at the bottom of the hopper 3. Steam 1 at 160 to 180 ° C. is supplied from the upper part of the steaming tank 5 to steam the chip 1 to soften it so that the fibers are easily defibrated, and the steamed chip 1 is scraped from the bottom of the steaming tank 5. Disentangled disk 8 with feeder 7
Supply to. Then, the chip 1 is defibrated into the wood fibers 9 by the defibration disk 8 driven by the motor 10 '. The wood fiber 9 thus defibrated is supplied to the dryer 12 shown in FIG. The moist wood fiber 9 is sent to the cyclone 16 while being dried by passing through the meandering drying tube 15 together with the hot air 14 supplied from the dryer 13, and the hot air and the fine powder containing the water 17 are supplied by the cyclone 16. Are removed to obtain dried wood fiber 18.

Then, the wood fibers 18 are put into the deposition container 19 shown in FIG. 2, and air is blown into the deposition container 19 through the holes 21 provided in the perforated plate 20 to make it flow. In addition, 22 is a support part, 23 is an air inlet, and the arrow in a figure shows the flow direction of air.

The flowing wood fibers 18 are suctioned and attached onto the metal net 25 of the holding device 24 to form the 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 the vacuum lines 27, 28 and 29 to form a part of the wall surface of each room of the wire net 25. By controlling the suction degree of the portion, the properties such as the wall thickness of each portion of the preform are adjusted. Next, the holding device 24 is moved by the cylinders 30 and 31 onto the wall surface 33 of the lower mold 32 shown in FIG.

Then, the portion of the preform M2 that is largely deformed during forming, that is, the portion M3 to be deep-drawn is further strongly sucked to strengthen the entanglement of the wood fibers.

Then, the suction is weakened or stopped, and the lower die 32 is placed on the die surface 33 as shown in FIG. Next, the lower mold 32 and the upper mold 35, which are heated to 180 to 200 ° C. by the hot plate 34, are fitted by lowering the upper mold 35. At this time, gas is generated, so the mold is opened to release the gas.
Fit the upper and lower molds. In this way, precompression and degassing were repeated several times, and then the upper mold 35 was removed as shown in FIG.
And the lower mold 32 for compression. M2 'indicates a derivative material. Then, the mold was opened and the product was taken out to obtain a wood-based molded product M4 shown in FIG.

〔The invention's effect〕

As described above, in the method for manufacturing a wood-based molding of the present invention, the wood-based molding material containing the binder is sucked by the holding device having a porous suction surface to form a pre-molded body on the suction surface. In order to move the preformed body sucked and held by the holding device to above the mold surface of the molding die, partially suck the preformed body and then place the preformed body on the mold surface, and then heat compression molding , For example, when the portion to be deep-drawn is strongly sucked during thermoforming of the preform, the entanglement between the wood-based molding materials such as the wood fibers becomes deeper and the fracture at the deep-drawn portion is prevented. It is possible to prevent and improve the moldability and to improve the properties such as the mechanical properties and the appearance of the molded product.

Further, compared with the conventional matt method, the step of matting the wood fibers and the step of cutting the mat and the equipment for them are not required, so the workability and productivity at the time of molding are improved, and the cutting waste and mat of the mat are further improved. Since there is no derived material at the time of molding, the yield can be improved and the raw material cost can be reduced.

Furthermore, since the preform is formed by the holding device and directly supplied into the mold without matting the wood-based molding material, the filling amount of the wood-based molding material, that is, the packing density and the wall thickness of the preform are controlled. It can be easily changed, and a wood-based molded product having desired properties can be easily obtained.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a state in which a preformed body sucked and held by a holding device is moved onto a mold surface of a molding die in an embodiment of a method for manufacturing a wood-based molded body of the present invention, and FIG. In the embodiment shown in FIG. 1, a cross-sectional view showing a state in which a preformed body is formed on the suction surface portion of a holding device, and FIG. 3 is a mold surface of a lower die of the preformed body in one embodiment of the method of the present invention. FIG. 4 is a cross-sectional view showing a state in which it is placed on top, FIG. 4 is a cross-sectional view showing a state in which the preform shown in FIG. 3 is heat-compressed, and FIG. 5 is a wood material manufactured by one embodiment of the method of the present invention. 6 is a perspective view of an example of a defibrating machine used to obtain a wood fiber that is a raw material of a wood-based molded body, FIG. 7 is a schematic configuration diagram showing a dryer for wood fibers, FIG. 8 is a perspective view of an example of a mat made of wood fibers. In the figure, 18 ... Wood fiber 19 ... Deposition container 24 ... Holding device 32 ... Lower mold 33 ... Mold surface 35 ... Upper mold M2 ... Preform M3 ... Part to be deep-drawn M4 ... Wood-based molding

Claims (1)

[Claims] 1. A wood-based molding material to which a binder is added is sucked by a holding device having a porous suction surface portion to form a preform on the suction surface portion, and the preform is suction-held. A holding device is moved above the mold surface of the molding die, the preform is partially strongly sucked and then placed on the mold surface, and then hot compression molding is performed. Production method.