JPS61181609A - Manufacture of mat to be molded - Google Patents

Abstract

PURPOSE:To obtain a mat having a uniform quality thereby preventing the mat from having any cracks when the mat is deep drawn, by mixing a special fiber material with a resin to produce a mat, and heating and pressing the mat at a temperature within a special range. CONSTITUTION:A dried fiber material made up of a wood fiber, a natural fiber that has a tensile strength greater than that of the wood fiber and is longer than the wood fiber, and a recovered wool is mixed uniformly with a resin material made up of a liquid or fibrous thermoplastic resin and a liquid thermoplastic resin that has a setting temperature higher than the melting point of the first thermoplastic resin, and the mixture is made into a mat by a forming apparatus. After the mat is heated and pressed at a temperature ranging from the melting point of the thermoplastic resin to the setting temperature of the thermoplastic resin, it is cooled so that the fiber materials are fused by the thermoplastic resin to produce a mat that has a specific gravity of 0.01-0.5 and is to be molded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a low specific gravity soft fiberboard using wood fibers, and particularly to a method for producing a forming mat suitable for deep drawing processing.

BACKGROUND OF THE INVENTION Forming mats suitable for deep drawing and methods for producing the same are known.

For example, in Japanese Patent Publication No. 55-40423, essential fibers, synthetic pulp fibers having a stronger tensile strength than the wood fibers, and if desired, long natural fibers are mixed, and a thermosetting resin is added to this mixture. However, a method is disclosed in which a soft fiberboard with a low specific gravity is obtained by performing wet mixing and then papermaking and dehydration.

JP-A No. 59-120440 discloses that undried wood fibers that have been defibrated by steaming and then separated from water vapor are mixed with long fibers with high tensile strength, powdered thermosetting synthetic resin, and powdered or fibrous material. A thermoplastic synthetic resin is added and mixed, the resulting mixture is made into a mat using a cotton-making machine, and the mat is heated at a temperature that does not reach the curing temperature of the thermoplastic resin at several points or more of the thermoplastic synthetic resin. A method for producing a moldable wood fiber mat is disclosed, which comprises heat drying and compressing at a range.

Purpose of the Invention However, in the above-mentioned wet papermaking method, the resin flows out during papermaking and dehydration, so an excessive amount of resin must be added in order to fix the required amount of resin in the mat. . Further, thermal energy and time are wasted due to drying after papermaking. Furthermore, since it is a mixed paper making method, the entanglement between fibers is large, and cracks tend to occur during deep drawing.

The latter method described above is close to the dry method, but since the wood fibers that have been defibrated by steaming are used without drying, they have a moisture content of 40 to 50%, and when mixing the wood fibers and long fibers, the fibers are fibers tend to get tangled, fiber clumps tend to occur, and a homogeneous mat cannot be obtained. Furthermore, it takes a long time to dry the mat, and if the mat is molded and heated and pressed while the moisture content is still high, punctures will occur due to rapid evaporation of the contained moisture. Furthermore, since a powdered resin is used, adhesion and dispersion of the resin to the fibers are poor, making it difficult to obtain a mat of uniform quality.

Particularly when the amount of resin blended is small, it is difficult to uniformly disperse the resin.

Therefore, the object of the present invention is to provide a method for producing a molding mat that eliminates the above-mentioned drawbacks.

Structure of the Invention In the present invention, wood fibers, a dry fiber material consisting of natural fibers having a stronger tensile strength and a longer fiber length than the wood fibers, a liquid or fibrous thermoplastic resin, and the above-mentioned thermoplastic resin are used. A resin material made of a liquid thermosetting resin having a curing temperature higher than the melting point of the plastic resin is mixed uniformly, and the resulting mixture is made into a matte state by forming mW,
The resulting mat is heated and pressed at a temperature above the melting point of the thermoplastic resin and below the curing temperature of the thermosetting resin, and then cooled to fuse the fiber material with the thermoplastic resin. The molding mat has a specific gravity of 0.01 to 0.5.

Since the method of the present invention is a completely dry method, drying of the mat is not necessary, saving thermal energy and time.

Resin materials made of thermoplastic resins and thermosetting resins are mixed with dry fiber materials using a liquid bath or a machine wand, so the fixation rate of the resin materials to the fiber materials is good, and the resin materials are mixed with dry fiber materials. Adhesion and dispersion to the material is uniform.

Since a dry fiber material is used, it is easy to uniformly disperse each e-fiber, and the entanglement between the fibers occurs appropriately, making it easy to obtain a uniform mat.

Furthermore, due to the rigidity of the natural long fibers and the flexibility of the recycled fibers, the resulting mat for molding is easy to handle and cracks can be prevented during deep drawing.

Furthermore, since recycled wool is used, material costs are also reduced.

Although the configuration of the present invention has been generally explained above, the present invention will be explained in more detail based on examples below.

Description of Examples The fiber material used in the present invention has a fiber length of 2 to 3.
■■ Wooden fiber with strong tensile strength and rigidity of 20
-Natural long fibers such as hemp, palm, and coconut fibers of about 8011, with strong tensile strength and flexibility of 20 to 80 mus
This is recycled wool containing cotton, synthetic fibers, etc., with a certain fiber length.

Wood fibers are obtained by defibrating wood chips of softwood, hardwood, etc., which are commonly used as raw materials for fiberboards, by a conventional method and drying to a moisture content of around 8%.

Recycled wool is made from scraps of cloth and can be obtained relatively inexpensively. The synthetic fibers mixed in the recycled wool generally serve as a thermoplastic resin material, which will be described later.

The blending ratio of these three types of fiber materials is wood fiber 40 to 9
0wt%, natural long line 1!1~301wt%, curled hair 9~5
It is preferable to set it to 0 wt%. If the content of natural long fibers is 1 t% or less, the intertwining between the vA fibers in the formed mat will be weak, the rigidity of the mat will be low, and handling will be difficult. Moreover, when the natural long fiber content is 30 wt% or more, the rigidity becomes too high and the formability during deep drawing becomes poor. However, these upper and lower limits are not critical.

If the amount of recycled hair is 9 wt % or less, the entanglement between the fibers in the formed mat will be weak and flexibility will not be obtained. or,
When the amount of recycled hair exceeds 50 wt%, the formed mat becomes too soft and is inconvenient to handle. However, these upper and lower limits are also not critical.

These fiber materials are preferably mixed in a dry state, and the mixing order is preferably that the wood fibers are mixed with the natural long fibers, and then the recycled fibers are mixed. This facilitates uniform mixing. Mixing may be effected satisfactorily, for example, by passing through a finer with wide disc spacing; however, other conventional methods may also be used.

The synthetic resin materials used in the present invention include a liquid or fibrous thermoplastic resin and a liquid thermosetting resin that has a curing temperature higher than the melting point of the thermoplastic resin.

The thermoplastic resin used may be ethylene vinyl acetate resin, polyethylene resin, vinyl acetate resin, latex, etc. When thermoplastic resin is used in fibrous form,
Fiber length is 80■■ or less, ta111 diameter 00lIII
It is preferable to use the following, and it is also preferable to mix it with the above-mentioned uAI111 material. As the thermosetting resin, phenol resin, melamine resin, etc. may be used.

The addition ratio of each synthetic resin is 0.5 to 10 wt% of thermoplastic resin and 3 to 10 wt% of thermosetting resin to the total amount of fiber material.
About 30 wt% is desirable, however, the amount of thermoplastic resin added is preferably adjusted depending on the amount of synthetic fibers contained in the recycled fiber material.

The amount of thermoplastic resin mixed is 0.5 wt% or less,
The fusion between the fibers in the formed mat is insufficient, resulting in weak shape retention and inconvenience in handling. Moreover, if the thermoplastic resin exceeds 10 wt%, the resin will ooze out during deep drawing, and the resin will adhere to the molding die, resulting in poor mold release properties.

If the amount of thermosetting resin mixed is less than 3 wt%, the strength of the molded product will be low when the molding mat is molded, and if it exceeds 30 wt%, there will be no problem in terms of strength, but it will cause problems with the fiber material. During mixing, fiber clumps occur due to adhesion between fibers, making it difficult to form a uniform mat.

In order to mix the liquid synthetic resin with the fiber material, for example, it is best to mix it as a mist while blowing the mixed fiber material.
However, it may be mixed in when mixing the fiber materials.

The mixture of fiber material and synthetic resin material thus obtained is
The material is formed into a mat using a forming device commonly used in the dry method. At this stage, the mat does not have the ability to hold its own shape.

The resulting matte material is heat-pressed by hot pressing at a temperature above the melting point of the thermoplastic resin and below the curing temperature of the thermosetting resin. As a result, the thermoplastic resin melts and flows between the fibers and adheres to them, and the fibers in the mat are then brought into close contact with each other by cooling.

The molding mat thus obtained has sufficient strength to withstand handling like a rattan during transportation and molding.

The specific gravity of the molding mat is preferably about 0.01 to 0.5. When the specific gravity becomes 0.01 or less, the fossa becomes high,
Although it has the ability to hold shape, it is difficult to handle (and the specific gravity is 0.
When it is 5 or more, deep drawing formability deteriorates.

When molding a molding mat, it is heated and pressurized at a temperature higher than the curing temperature of the thermosetting resin, and since this temperature is higher than the melting point of the thermoplastic resin, the fibers in the mat are tightly bonded. The thermoplastic melts, breaking the bonds between the fibers and thus allowing movement between the fibers during molding. The thermosetting resin is then cured to firmly bond the fibers within the molded mat.

Below, some examples of the invention are presented.

Example 1 Coniferous wood chips were defibrated and dried in a conventional manner to obtain wood fibers with a water content of 10%. 75w of the obtained wood fiber
5wt% hemp fiber with fiber length of 50cm, fiber length of 30cm
Mix in a mixing device so that the weight of the fibers is 201%, and 5ffi amount of liquid ethylene vinyl acetate resin as a thermoplastic resin and 12 wt% of liquid phenol resin as a thermosetting resin with respect to the total amount of the above fiber material. was added to obtain a homogeneous mixture.

The resulting mixture was heated using a conventional forming device for 10 minutes.
A mat with a thickness of 0.0 yen was formed, and the resulting mat was heated by hot pressing at a temperature of 110°C and a pressure of 2 kg/cJ.
This was pressed for minutes to obtain a molding mat having a thickness of 10 mm and a specific gravity of 0.3.

This molding mat was heated and pressure molded for 2 minutes at a temperature of 220° C. and a pressure of 30 kg/cJ using male and female molds with a radius of curvature of 50 mm.

Thus, the thickness is 3II■, the specific gravity is 1, and the bending strength is 500 kg.
A deep-drawn product of 501 cm and having physical properties of /cJ was obtained without any cracks.

Example 2 90wt% of wood fibers similar to Example 1, 1w of natural long fibers
A molding mat having a thickness of 5 mm and a specific gravity of 0.5 was obtained in the same manner as in Example 1 using 9 wt % of recycled hair. This molding mat was cut to a width of 41 cm, both ends were fixed with the clamps of a tensile testing machine, and a load was applied to the center of the mat, and it was confirmed that it had the strength to withstand a load of 25 kg/cJ to 30 k@/d. .

The resulting molding mat was close to the limit for deep drawing of 50 mm.

Example 3 Wood fiber 40wt% similar to Example 1, natural long fiber 10
A mat for molding having a thickness of 5 cm-1 and a specific gravity of 0.08 was obtained in the same manner as in Example 1 using 50 wt% of recycled hair.

This molding mat was cut to a width of 4 cs, both ends were fixed with clamps of a tensile tester, and a load was applied to the center of the mat, and it was found that it had strength to withstand a load of 3 kg/cJ. This strength is sufficient to withstand handling for transportation and molding. The obtained molding mat is 5o■
It was found that a titrated molded product could be obtained by the deep drawing process described in (2) without causing any cracks.

Claims (4)

[Claims] (1) A dry fiber material consisting of wood fibers, natural fibers with stronger tensile strength and longer fiber length than the wood fibers, and recycled fibers, and a liquid or fibrous thermoplastic resin, which has a melting point higher than the melting point of the thermoplastic resin. A resin material made of a liquid thermosetting resin having a curing temperature is mixed uniformly, the resulting mixture is made into a mat shape using a forming device, and the resulting mat is heated to a temperature equal to or higher than the melting point of the thermoplastic resin and at the temperature above the temperature range. It is characterized by heating and pressurizing within a temperature range below the curing temperature of the curable resin, and then cooling to fuse the above-mentioned fiber material with a thermoplastic resin to form a mat for molding with a specific gravity of 0.01 to 0.5. A method for producing a molding mat. (2) The method according to claim 1, characterized in that when mixing the fiber materials, the wood fibers and natural long fibers are first mixed, and then the recycled fibers are mixed. A method for manufacturing mats for molding. (3) The method according to claim 1 or 2, wherein the length of the wood fiber is 2 to 3 mm, the length of the natural long fiber is 20 to 80 mm, and the length of the curled hair is 2 to 3 mm. is 20-8
A method for producing a molding mat characterized by having a thickness of 0 mm. (4) The method according to any one of claims 1 to 3, wherein the blending amount of the fiber material is 40 to 90% by weight of wood fibers and natural length in the same dry state. Fiber 1~
A method for producing a mat for molding, characterized in that the content of the mat is 30% by weight and the recycled hair content is 9 to 50% by weight.