JPS63202405A - Manufacture of woody formed item - Google Patents

Abstract

PURPOSE:To improve the productivity and to stabilize the quality by a method wherein forming base material, in the central part of the layer of which more resin is contained than in its surface layer part, is formed with a hot press. CONSTITUTION:A woody forming base material, the surface layer of which contains less resin and the central part of the layer of which contains more resin, is formed with a hot press. Under the condition just mentioned above, the solidification of the surface layer part of the base material is retarded, and a gas unpermeable film becomes hand to be produced, and consequently almost all the gaseous reaction product and water content in the base material are discharged outside the base material. Accordingly, no degassing operation becomes necessary and the forming cycle can be shortened to a far greater extent, and the productivity is improved, and at the same time the occurrence of defectives can be brought to nearly null and the yield is remarkably improved.

Description

[Detailed description of the invention] [Field of industrial use] The present invention relates to a method for manufacturing wood-based molded products.

[Conventional technology]

Wood-based molded products made mainly of chips such as wood chips are widely used as so-called hardboard materials for construction and furniture, and recently have also been used for automobile door trims and the like.

Conventionally, in order to manufacture the above-mentioned wood-based molded product, a wood-based resin-impregnated fiber is first manufactured. That is, the wood chips are steamed to a state where the fibers are easy to separate, then they are rubbed together with the drive disk of a defibrator to defibrate them, and then sent through a drying tube to a cyclone with hot air to dry and remove fine powder. After adding hemp fibers, etc., a binder made of phenolic thermosetting resin, thermoplastic synthetic resin, etc. is added, and the mixture is uniformly mixed and stirred.

Next, a molding mat 1 is manufactured using the resin-impregnated fiber obtained as described above using a mat manufacturing apparatus 2 as shown in FIG. In this mat manufacturing apparatus 2, the transport pipe 3
Resin-impregnated fibers 5a and 5b are supplied to hoppers 4a and 4b through a and 3b, and the fibers 5a and 5b are scattered from the bottoms of these hoppers 4a and 4b to deposit them on a driving belt conveyor 6. The accumulated fibers 5 are made into a flat plate by passing between the pinching rollers 7..., and finally from both upper and lower surfaces by hot pressure rollers 8, 8 provided on the feed side of the pinching rollers 7... The molding mat 1 is obtained by hot pressing. Note that hopper 4. ．．
The method of installing two 4b fibers in series and depositing them twice is because if a large amount of fibers with different lengths and thicknesses are deposited at once, the resulting mat will have uneven density. This is to avoid this. The molding mat 1 obtained as described above is easy to handle, is stored on the side of the mat, and is transported in this mat state as needed.

In order to manufacture a wood-based molded product using the above-mentioned molding mat 1, for example, when hot-pressing an automobile door trim, it is necessary to cut the molded product into a size slightly larger than the shape of the finished molded product. This mat was then hot press molded into a predetermined shape using a mold heated to about 170 to 200°C.

[Problem that the invention seeks to solve]

However, since the above-mentioned molding mat had resin uniformly distributed throughout the interior thereof, the method of manufacturing a wood-based molded article using the mat had the following problems.

That is, during hot press molding, the molding mat comes into contact with the mold surface, but the thickness of the mat is usually 5 to 20 mm, and the porosity is high, so the heat of the mold is absorbed into the inside of the mat. It's not easy to convey. For this reason, the reaction progresses rapidly on the surface layer of the mat, which is heated quickly, and the reaction gas and moisture generated inside the mat are released to the outside of the mat.
is likely to occur. Molded products with gas pockets have deteriorated strength properties! 7. Also, the appearance becomes poor due to blistering, deformation, etc. In order to avoid this, conventional methods have been to increase the pressurization time and gradually heat the product, or to release the press during the molding process to vent gas. FIG. 4 is a diagram showing the pressure pattern, where the vertical axis shows the press pressure due to die operation, the horizontal axis shows the molding time, and the valley part L of the graph
l*i, * indicates the time of degassing. However, such a molding method has problems in that the molding cycle is long, resulting in poor productivity and unstable quality.

The present invention was made to solve these problems, and its purpose is to stably produce high-quality wood-based molded products with high productivity without causing gas pockets in the molded products. It is an object of the present invention to provide a method that can be easily manufactured.

[Means for solving problems]

The method for producing a wood-based molded article of the present invention that can achieve the above object is characterized by hot press molding a laminated wood-based molded base material containing a large amount of resin in the surface layer and the center of the thigh layer. do.

That is, in order to obtain a high-quality wood-based molded product, it is essential to use a wood-based molding base material to which a predetermined amount of resin is added, but it is essential to change the distribution of resin in the molded base material. In other words, it was discovered and completed that the above-mentioned problems could be solved by using a wood molded base material containing less resin in the surface layer part and more resin in the center part of the layer.

In particular, wood fibers impregnated with 25% or less of the required amount of resin are deposited, on top of which 50% or more of the required amount of resin is added, and then on top of that, 25% or less of the required amount of resin is impregnated. It is preferable to use a mat-like wood-based molded base material containing a predetermined amount of resin obtained by depositing and compressing wood-based fibers.

[For production]

If configured as described above, the solidification of the surface layer portion of the wood-based molded base material to be hot press-molded will be delayed. This is because there is less resin in the surface layer. Therefore, an impermeable film is formed on the surface layer of the molded substrate, and most of the reaction gas and moisture inside can leak out of the molded substrate. Although the resin distribution in the molded substrate is non-uniform, the resin flows under heat and pressure, and eventually becomes uniform in the molded product.

〔Example〕

An embodiment of the method for manufacturing a wood-based molded product according to the present invention will be described below with reference to the drawings. In this embodiment, the conventional method was used except that the molding mat used and the pressure pattern during hot press molding were different. Since they are almost the same, we will mainly explain their differences here.

FIG. 1 is a diagram schematically showing the method for manufacturing a molding mat according to this embodiment, and in the figure, the same reference numerals as those in FIG. 5 indicate the same functional members. Here, each hopper 4a, 4b is placed on a rotating belt conveyor 6.
The wood fibers 5a and 5b respectively sprayed from are impregnated with less than half of the conventional amount of resin, that is, less than half of the required amount in total, and the missing resin 9 is in liquid or powder form.
The trap is such that resin is supplied from a resin supply device 10 provided between both hoppers 4a and 4b. As a result, a large amount of the resin is distributed at the boundary between the lower deposited fiber E and the upper deposited fiber F, and the molding mat 1 manufactured by compressing the deposited fiber 5 with a roller is shown in FIG. As shown in the cross section in the compression direction, a large amount of resin is distributed near the center. In FIG. 2, numeral 11 indicates a heavily impregnated layer on the flank.

When this molding mat is used, moisture and generated gas inside the mat can be leaked out until the end of heating compression molding due to the above-mentioned action.
Molding can be performed using a pressure pattern as shown in the figure, and release of the press for degassing can be omitted.

It should be noted that the above-mentioned example shows one embodiment of the method of the present invention, and as long as it does not depart from the purpose, structure, and effects of the present invention,
You are free to make any modifications or changes. For example, a large number of fiber dispersion hoppers may be installed above a belt conveyor, and wood fibers with various amounts of resin impregnation are sequentially laminated to form a fiber deposit containing a large amount of resin in the center of the layer to form a mat. good. Alternatively, the fiber deposit containing a large amount of resin in the center of the layer may be transported as it is to a mold using a suitable holder and directly hot press-molded without being matted.

〔Effect of the invention〕

According to the method of manufacturing a wood-based molded article, the present invention has the following effects.

First, since there is no fear of gas bubbles in the molded product, the degassing operation that conventionally required 1 to 4 hours per molding is no longer necessary, and the molding time is reduced from the conventional 70 to 180 seconds to 55 seconds.
It can be shortened to ~60 seconds. In other words, the molding cycle can be significantly shortened and productivity can be improved.

In addition, although conventional efforts have been made to prevent the occurrence of defective products by worsening the molding cycle, the occurrence of defective products due to gas blisters due to changes in the molding base material and conditions was unavoidable, but the method of the present invention According to the method, this can be almost completely eliminated, and the yield rate is significantly improved.

Furthermore, according to the method of the present invention, a molding base material (molding mat) whose quality is stable in the compression direction is used, so not only can molded products of constant quality be mass-produced, but the physical properties of the molded products can also be improved. However, it is possible to make the product board thickness smaller than before.

As a result of the above, manufacturing costs can be dramatically reduced, and high-quality wood-based molded products can be provided at low cost.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a method for manufacturing a molding mat according to an embodiment of the method for manufacturing a wood-based molded product of the present invention, FIG. 2 is a cross-sectional view of the molding mat, and FIG. FIG. 4 is a graph showing a pressure pattern during such heat compression molding; FIG. 4 is a graph showing a conventional pressure pattern; FIG. . In the figure, 1...Molding mat (wooden molding base material) 2...Matt manufacturing device 5@, 5b...Resin-impregnated fiber 6...Belt conveyor 9...Resin 11...Massive resin impregnation Layer patent applicant Toyota Motor Corporation representative Patent attorney Yumi Sae and 2 others Figure 1 Figure 4

Claims (2)

[Claims] (1) A method for producing a wood-based molded product, characterized by hot press molding a laminated wood-based molded base material containing a larger amount of resin in the center of the layer than in the surface layer. (2) Depositing wood fibers impregnated with 25% or less of the required amount of resin, adding 50% or more of the required amount of resin on top of that, and further impregnating 25% or less of the required amount of resin on top of that. manufacturing a wood-based molded article according to claim 1, which comprises heat press molding a mat-like wood-based molding base material containing a predetermined amount of resin obtained by depositing wood fibers and compressing the deposited wood fibers; Method.