JPH0222005A - Wooden molded piece - Google Patents

Abstract

PURPOSE:To provide a wooden molded piece in which elongation or shrinkage is reduced due to moisture absorption or discharge by compression molding mixture of 5-30wt.% of glass fiber and wooden molded material to which binder or the like is added to wooden fiber. CONSTITUTION:Wooden fiber is supplied to a blender, approx. 5-30wt.% of phenol resin is added as a binder, and approx. 0.5-5wt.% of polyethylene oxide wax is added as inner mold release agent, thereby obtaining wooden molded material. On the other hand, after glass fiber is dipped in aqueous solution containing 5-30wt.% of phenol resin as solid content, it is dried, cut in length of 20-100mm, thereby obtaining chop strand. Then, wooden molding material and the glass fiber are agitated, mixed, and the mixture is scattered to a scattering vessel 3 and a laminating vessel 4 under a hopper 2. A predetermined quantity of the mixture is deposited to form a material assembly of predetermined shape, and compression molded between a lower mold 8 and an upper mold 9.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a wood-based molded article used for interior parts of automobiles, cabinets of electrical appliances, and the like.

(Prior Art) As a wood-based molded product, so-called hardboard is well known and has been used for a long time as a base material for interior parts of automobiles, cabinets of electrical appliances, and the like. This hardboard is generally produced through a process in which a binder is added to wood fibers obtained by defibrating wood chips, etc., these are made into a mat by papermaking or roll pressing, and the mat is fed into a mold and compression molded. (For example, JP-A-52-11
0785, JP-A-58-13480, etc.). Recently, a method for manufacturing a wood-based molded body has been established in which the matting process is omitted and the wood-based molding material is supplied directly or aggregated into a predetermined shape to a mold and compression molded (for example, in Japanese Patent Application Laid-Open No. (See JP-A-80-259372, JP-A-82-90203, JP-A-82-134215, etc.).

(Problem to be solved by the invention) By the way, the wood-based molded article obtained as described above is
The wood fibers that make up this wood have a characteristic of being highly water absorbing, and this characteristic has caused various problems.

For example, this wood-based molded body may be used in the automobile 2 shown in FIG.
For example, when applied to a ceiling base material 21 with a density of 0.
When a wet-cooling-heat cycle test was performed using a base material molded to a thickness of 4cm at 45g/cm2, as shown in Figure 16,
Depending on the part, it hangs down more than 10m, and in this case,
Since the ceiling base material 21 comes into contact with the head of the person seated on the vehicle, it becomes impossible to apply the mouth moving vehicle 20 to the ceiling base material 21. In addition, the wet/cool/heat repeated test is performed at 50°.
C9 Relative Humidity 95% TE Hold for 23.5 hours, then next knee 3
0°(! Thea.

One cycle consisted of holding for 5 hours and then holding at 85°C for 15.5 hours. The numbers on the horizontal axis in FIG. 16 above represent the respective part numbers attached to the ceiling base material 21 shown in FIG. 15.

In addition, as shown in FIGS. 13 and 14, if this ceiling base material 21 is to have a butt structure flush with the center pillar garnish 23 inside the automobile body 22 to give a sense of continuity to the interior, Since the dimensional change between the dry state and the dry state is large (more than 0.5%), a relatively large gap χ has to be provided at the abutting portion, which impedes the design. Therefore, attempts have been made to cover and hide the abutting part with another garnish, but in this case,
Not only does this result in an increase in the number of parts and the number of assembly steps, but the sense of continuity in the interior is lost, resulting in dissatisfaction with the design.

The present invention was made to solve the above-mentioned conventional problems, and an object of the present invention is to provide a wood-based molded article whose dimensions and shape can be stably maintained regardless of changes in the environment.

(Another Means to Solve the Problems) In order to solve the above problems, the present invention incorporates 5 to 30 wt.
The gist is that the mixture is compression molded.

In the present invention, the dispersion form of the glass fibers is not particularly limited, and for example, the glass fibers may be uniformly dispersed in the wood-based molding material or may be dispersed in a layered manner.

Furthermore, in the present invention, the binder added to the wood fibers is
There are no particular limitations on the type, as long as it supplements the bonding properties of the wood fiber itself and binds the wood fiber and the glass fiber, such as natural polymers such as starch, thermoplastic resins such as coumaron resin, etc. , thermosetting resins such as phenolic resins and urea resins. Further, in addition to the binder, for example, an internal mold release agent, a water repellent, etc. can be added to the wood fiber.

In the present invention, in order to facilitate addition and dispersion, the glass fibers added to the wood-based molding material are so-called chopped strands, which are made by bundling the necessary number of monofilaments with a binding agent and cutting them into a predetermined length. It is preferable to use strands. In this case, the number of monofilaments constituting the chopped strand is 100 to 600,
And its length is preferably 20 to 100 mm. Further, in order to supplement the bond between the glass fiber and the wood fiber, the glass fiber can be impregnated with a binder in advance.

In the present invention, the method of supplying the mixture of wood-based molding material and glass fiber to the mold can be arbitrary: it can be supplied after it has been matted, it can be supplied directly as a powder, or it can be supplied directly as a powder. It may be supplied after being assembled into a predetermined shape separately. The mixture supplied into the mold is compression molded into a predetermined shape, and at this time, it may be heated if necessary.

(Function) In the wood-based molded article having the above structure, by adding glass fiber to the wood-based molding material, it is possible to reduce the expansion and contraction of the wood fibers due to moisture absorption and discharge, and the difference between wet and dry times. dimensional change becomes smaller. In addition, the strength is increased and the overall rigidity is increased, and deformation such as sagging that is likely to occur due to environmental changes is suppressed. However, if the amount of glass m-fiber added to the wood-based molding material is less than 5z, it will be difficult to obtain the desired effect, while if it exceeds 30x, the cost will increase significantly in proportion to the effect. ~30
It was set as wt%.

(Example) Hereinafter, an example of the present invention will be described based on the accompanying drawings.

FIG. 1 shows an embodiment of a wood-based molded article according to the present invention. In the figure, the wood-based molded product indicated by P has glass fibers uniformly dispersed in wood fibers a. Such a wood-based molded product P is made by adding a predetermined amount of glass fibers to a wood-based molding material made of wood fibers a and a binder, etc., to form a mixture, and then gathering this mixture into a predetermined shape to form a mold. , thickness 2.0~8.0mm, density 0.2~
It is formed by hot compression molding to give a weight of about 0.9 g/cm2.

Hereinafter, a manufacturing method in which the above-mentioned wood-based molded body P is applied to the above-mentioned ceiling base material will be specifically explained.

First, wood fibers are fed into a blender (not shown), and a phenolic resin (for example, manufactured by Gunei Chemical Co., Ltd.) is added as a binder to the blender (not shown).
A wood-based molding material is obtained by adding 5 to 30 wt % of dry weight of PL4830) and 0.5 to 5 wt % of an oxidized polyethylene wax (for example, Polylon 383 manufactured by Middle East Yushi Co., Ltd.) as an internal mold release agent. On the other hand, as glass fiber,
A strand consisting of monofilament with a diameter of 6 to 15 gm (for example, NEC roving series manufactured by Nippon Electric Glass Co., Ltd.) is prepared, immersed in an aqueous solution containing a phenolic resin of 5 to 30 wt% as a solid content, dried, and further 20 gm in diameter. Cut to ~100 mm length to obtain chopped strands. Next, the wood-based molding material and glass fiber prepared as described above are pneumatically fed into a pipe (not shown) at a predetermined mixing ratio, stirred and mixed in the pipe to form a mixture, and then this mixture is is supplied to the molding process shown in FIG.

In the molding process, first, the mixture of the wood-based molding material and glass fibers is supplied to the hopper 2 of the collecting device 1, and is spread into the sprinkling container 3 and the laminated container 4 below the hopper 2. A perforated plate 5 made of punched metal or the like is stretched inside the laminated container 4, and the dispersed mixture is deposited on this perforated plate 5 one after another. The laminated container 4 has the same cross-sectional area as the ceiling base material, and a material aggregate W of a predetermined shape is formed by depositing a predetermined amount of the mixture.Next, the formation of this material aggregate W Wait for this, separate the laminated container 4 from the dispersion container 3, and separate the retainer 6 from the laminated container 3 using suction power.
The material assembly W is transferred to. Thereafter, the retainer 6 is moved to the mold 7, the suction is released, and the material aggregate W is thrown into the mold 7. The mold 7 consists of a lower mold 8, an upper mold 8, and a holding frame lO, and is heated to a predetermined temperature (180 to
230°C). The material aggregate put into the mold is thermally compression molded by lowering the upper mold 8, thereby obtaining a ceiling base material with a thickness of 4 mm and a density of about 0.35 g/cm2.

Next, various tests were conducted on the ceiling base material obtained as described above, and the results are described below.

First, bending tests were conducted on ceiling base materials obtained by standardizing the amount of glass fiber added to LOwtX and varying the number of monofilaments in one bundle of strands.

The bending test was conducted using a three-point bending test method with a span of 100cm.
The bending speed was 50I1 m/sin. For comparison, a test was also conducted on a conventional ceiling base material (density 0.45 g/cm2) to which no glass fiber was added. Figure 2 shows the test results. It shows that the bending strength depends on the number of monofilaments in one bundle of strands, and the highest value is reached when the number is between 200 and 800. When it exceeds , it decreases rapidly. When the number of fibers is between 200 and 600, the bending strength is improved by more than 20% compared to that without glass fibers, and it has become clear that glass fibers greatly contribute to improving the strength.

The number of monofilaments in one bundle of strands is 3.
The dimensional changes between wet and dry conditions were measured for ceiling base materials obtained by varying the amount of glass fiber added to the wood-based molding material. Figure 3 shows the results, and it shows that the dimensional change rate decreases as the amount of glass fiber added increases up to about 30%, and the amount of glass fiber added is 5 to 30 wH. It has become clear that it is desirable to do so.

Next, the amount of glass fiber added is lOwtX, 1 of the strand.
The same wet/cool/heat cycle test as explained in the conventional section was conducted on the ceiling base materials obtained by uniformizing the number of monofilaments in the bundle to 300. Figure 4 shows the test results corresponding to Figure 15 above, and it shows that the amount of sagging remains within 4cm even after two cycles of testing, indicating that the ceiling base material made only of wood fibers will sag. Quantity 10m
It was confirmed that it was significantly smaller than m or more (Fig. 16). This was brought about by the above-mentioned increase in bending strength, that is, rigidity, and decrease in the rate of dimensional change when wet and dry, and it became clear that there would be no problem in applying it to ceiling base materials.

Next, a sound absorption coefficient measurement test was conducted on the ceiling base material subjected to the above-mentioned wet-cooling-heat repeated test.

For comparison, a test was also conducted on a conventional ceiling base material (density 0.45 g/cm2) to which no glass fiber was added. FIG. 5 shows the test results, in which line A represents the ceiling base material according to the present invention, and line B represents the ceiling base material to which no glass fiber is added. This revealed that the ceiling base material according to the present invention has a higher sound absorption coefficient at each frequency than a conventional ceiling base material to which no glass fiber is added. This difference in sound absorption coefficient is caused by the difference in density, and the strength of the present invention does not decrease even if the density is lowered.
This result can be said to reflect the usability of the ceiling base material.

As you can see, the dispersion form of the glass m fibers in the wood-based molded body P can take various forms as shown in Figs. 7 to 11 instead of the form shown in Fig. 1.

In other words, glass fibers are selectively arranged on both sides of wood fiber a to create a three-layer structure (Fig. 7), or glass fibers are selectively arranged on one side of wood fiber a to create a two-layer structure (Fig. 7). (Figure 8). In the case of a three-layer structure, the rigidity of the molded body P is further increased, while in the case of a two-layer structure, sagging can be more effectively prevented by utilizing the difference in dimensional changes on both sides. In addition, in the case of the above-mentioned two- or three-layer structure, the phenol resin impregnated into the glass fibers deteriorates the mold release properties, so as shown in Figure 9 or Figure 1O, wood fibers are added to the outside of the glass fibers. A can be arranged thinly so that the glass fiber glass does not come into direct contact with the mold. In order to disperse the glass fibers in a layered manner, for example, in the above embodiment, the wood-based molding material and the glass fibers are selectively dispersed onto the perforated plate 5 using the laminating device 1. All you have to do is deposit it. Furthermore, the above-mentioned wood-based molded product P is usually put into practical use by pasting a skin such as fabritta, but if the skin is pasted and then stacked, there is a risk that the skin will be contaminated with wood fibers etc. Therefore, as shown in FIG. 11, a nonwoven fabric (sheet) S of polyester or the like may be pasted on the opposite side of the molded body P in advance. In the above embodiment, this sheet S can be integrally molded by setting it on the opposite concave surface of the material assembly W put into the mold 7.

(Effects of the Invention) As explained above in detail, the wood-based molded article according to the present invention has a dimensional change between wet and dry times due to the addition of a predetermined amount of glass fiber to the wood-based molded material. As the resistance decreases, the strength improves and becomes stable against changes in the environment, resulting in the effect of significantly increasing durability and reliability. Furthermore, since the strength is improved, it is also possible to lower the density of the molded body, which not only contributes to weight reduction but also contributes to improved sound absorption.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing an example of a wood-based molded article according to the present invention, FIG. 2 is a graph showing the correlation between the bundle size of glass fibers added to the wood-based material and bending strength, and FIG. Figure 3 is a graph showing the correlation between the amount of glass fiber added to the wood-based molding material and the dimensional change rate. Graph showing sound absorption coefficient measurement results for wood-based molded bodies, No. 6
The figure is a schematic diagram showing an example of the manufacturing process for obtaining a real wood-based molded product, and FIGS. 7 to 11 are cross-sectional views showing modified examples of the dispersion state of glass fibers in the wood-based molded product according to the present invention. , FIG. 12 is a perspective view showing an example of application of a wood-based molded body to an automobile ceiling base material, FIG. 13 is a side view showing an enlarged view of the main part of FIG. 12,
FIG. 14 is a cross-sectional view thereof, FIG. 15 is a plan view of a ceiling base material subjected to a wet/cool/heat cycle test, and FIG. 16 is a graph showing the results of a wet/cool/heat cycle test of a conventional ceiling base material. P...Wood-based molded body a...Wood fiber b...Glass fiber pierced Kitomo 〇- One IH side < Geiq Akai @ Kitomo σ11-

Claims (1)

[Claims] (1) A wood-based molded body made by compression molding a mixture of a wood-based molding material in which 5 to 30 wt % of glass fiber is added to a wood-based molding material in which a binder and the like are added to wood fibers.