JPH0449455B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a low specific gravity molding mat suitable for deep drawing processing and a method for producing the same.

BACKGROUND ART Conventionally, forming mats suitable for deep drawing processing and methods for manufacturing the same have been known.

For example, in Japanese Patent Publication No. 55-40423, wood fibers, synthetic pulp fibers with a stronger tensile strength than the wood fibers, and, if desired, natural fibers with longer fiber lengths are mixed, and a thermosetting resin is added to this mixture. , discloses a method for obtaining a low specific gravity soft fiberboard 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, and the resulting mixture is made into a pine shape using a cotton-making machine, and then the pine is heated and dried at a temperature that is above the melting point of the thermoplastic synthetic resin but does not reach the curing temperature of the thermoplastic resin. A method of making a compressed wood fiber mat for molding is disclosed.

Problems with the Prior Art In the above-mentioned wet papermaking method, resin flows out during papermaking and dewatering, so an excessive amount of resin must be added in order to fix the required amount of resin in the mat. In addition, thermal energy and time are wasted due to drying after papermaking. Furthermore, since it is wet-formed, the fibers are highly entangled, and cracks tend to occur during deep drawing.

The latter method mentioned above is close to the dry method, but because the wood fibers are used without drying, the wood fibers are 40 to 50%
When wood fibers and long fibers are mixed, the fibers tend to become entangled and fiber clumps occur, making it impossible to obtain a homogeneous mat. Furthermore, if the pine takes a long time to dry and is heated and compacted while the moisture content is still high, banks will occur due to the rapid evaporation of the moisture content. Furthermore, since a powdered resin is used, adhesion and dispersion of the resin to the fibers is poor, making it difficult to obtain a mat of uniform quality. Especially,
When the amount of resin blended is small, it is difficult to uniformly disperse the resin.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a method for manufacturing a molding mat that eliminates the above-mentioned drawbacks.

The applicant has previously filed two patent applications regarding a method of manufacturing a molding mat that solves the above-mentioned problems.

The first application (Japanese Patent Application No. 60-22054) describes wood fibers, natural fibers with stronger tensile strength and longer fiber length than the wood fibers, dry fiber materials made of recycled wool, and liquid or fibrous materials. and a resin material consisting of a thermosetting resin having a curing temperature higher than the melting point of the thermoplastic resin,
The resulting mixture is shaped into a pine using a forming device, and the resulting pine is heated and pressurized within a temperature range above the melting point of the thermoplastic resin and below the curing temperature of the thermosetting resin, and then cooled. The above fiber materials are fused together using thermoplastic resin to create a specific gravity
A method for forming a molding mat of 0.01 to 0.5 is disclosed.

The second application (Japanese Patent Application No. 60-22055) includes:
A method for producing a molding mat similar to that of the first application is disclosed, except that sheet materials are laminated on the front and back sides of the mat formed in the forming step in the method of the first application. There is.

Although these methods solve the above-mentioned drawbacks of the prior art, the products produced by the method of the first application described above have less fiber during deep drawing than the products produced by the method of the second application. It is somewhat easy to break, so there is a limit to deep drawing, and it tends to be difficult to finish the surface of deep drawn products with a smooth finish. Further, the shape retention strength of the molding mat is somewhat inferior to that of the product produced by the method of the second application, and the ease of handling is also somewhat inferior. Further, in the method of the second application mentioned above, sheet-like materials are laminated on both the front and back sides of the mat. However, further research by the applicant has revealed that when using a net-like material, it is not necessarily necessary to laminate the net-like material on both the front and back sides of the mat. That is, the net-like material may be laminated on either the front or back of the fibrous material layer, or may be laminated between two or more layers of fibrous material. Furthermore, it has been found that when a net-like material is used, the processability during deep drawing is good even when only wood fiber is used as the fibrous material. This is because a net-like material adheres better to the fiber material than a sheet-like material such as thin paper or Japanese paper, and therefore the fiber material follows the deformation of the net-like material better during deep drawing. I think that the.

Means for Solving the Problems The molded mat according to the present invention includes at least one fibrous material layer consisting of a fibrous material containing at least wood fibers and a resin material containing at least a thermosetting resin, and at least one layer of a net-like material. The laminate is fused with the resin material. In the laminate, a single layer of a net-like material may be formed on either the front or back of a single fiber material layer, or between a plurality of fiber material layers and/or on either or both of the front and back. One or more layers of the net-like material may be laminated on each other, or vice versa.

In the method for manufacturing molded mat according to the present invention,
A fibrous material containing at least wood fibers and a resin material containing at least a thermosetting resin are uniformly mixed, the resulting mixture is formed to form at least one fibrous material layer, and in the forming step, at least one fibrous material layer is formed. The net-like material is laminated on at least one of the front and back surfaces of the fiber material layer, or between multiple fiber material layers and/or on at least one of the front and back surfaces, and the resulting laminate is made of thermosetting resin. Heating at a temperature lower than the curing reaction initiation temperature and at a temperature higher than the temperature at which at least a part of the resin material exhibits plasticity, applying pressure, and then cooling to fuse the fiber material and the net-like material. There is.

The fiber material may be wood fiber only, or it may be made of relatively rigid materials such as hemp, shiro, palm, etc., which have higher tensile strength than wood fibers and have a short fiber length. It is relatively flexible, such as long natural fibers and recycled fibers, and has higher tensile strength than wood fibers, and is a mixture of either or both of long natural and synthetic fibers. Also good.

As the resin material, only a thermosetting resin may be used, or a thermoplastic resin having a melting point lower than the curing temperature of the resin may be used.

As the net-like material, various materials can be used depending on the purpose of the molding mat and the above-mentioned laminated state.

DESCRIPTION OF THE EMBODIMENTS The fiber material used in the present invention may be solely wood fibers commonly used as fiberboard raw materials. Wood fibers are, for example, softwood,
Wood chips such as hardwood are defibrated into fibers of about 2 to 15 mm using a conventional method, and the fibers are dried to a moisture content of about 8%.

Alternatively, in addition to the above-mentioned wood fibers, long fibers having a higher tensile strength may be mixed and used. For example, one or both of relatively rigid natural fibers such as hemp, hemp, palm, etc. and relatively soft fibers such as recycled wool may be used in combination. These long fibers are preferably about 20 to 80 mm. Highly rigid long fibers function as aggregates, and flexible long fibers provide good intertwining between fibers and provide strength against bending and tension, and the two complement each other to increase the shape retention strength of pine. .

The resin material is uniformly mixed into the fiber material as described above. As the resin material, thermosetting resins such as urea resins, melamine resins, and phenol resins are essential. These resins may be in any of liquid, powder, and fibrous forms. However, when using a powdered thermosetting resin, it is preferable to use it together with a liquid thermoplastic resin.

Alternatively, a thermosetting resin as described above and a thermoplastic resin having a melting point lower than its curing temperature may be mixed. Examples of thermoplastic resins include vinyl acetate resin, ethylene vinyl acetate resin, polyethylene resin, and latex.

These resin materials may be added when the wood chips are defibrated, or may be added to the fiber material using a mixing device. When a thermosetting resin is used alone, it is preferably about 3 to 30 wt% based on the fiber material. If it is less than 3wt%, the strength of the molded product itself will be low, and if it is more than 30wt%, there will be no problem in terms of quality, but the cost will be high. The amount of thermoplastic resin added is preferably about 0.5 to 10 wt% based on the fiber material.
In this case, the amount of thermosetting resin added may be about the same as in the case of single use. Although the lower limit of 0.5wt% thermoplastic resin is not critical, the melting of only the thermoplastic resin will result in insufficient fusion, and it will be necessary to also utilize the fusion power of the thermosetting resin, making the use of a mixture less meaningful. becomes. Furthermore, if it is added in excess of 10 wt%, it tends to adhere to the hot platen or mold during heating and pressurization or deep drawing of the product (poor mold releasability), leading to a decline in productivity and quality.

The mixture thus obtained is formed into a mat shape by a forming device.

At this time, the procedure is changed depending on the number of layers of fiber material and the number of layers of net-like material. When each layer is single, either the net-like material 2 is fed in advance and the fibrous material layer 1 is formed thereon (see FIG. 1a), or vice versa. When laminating two layers of the net-like material 2 on both sides of a single fiber material layer 1 (see FIG. 1c), the net-like material 2 is fed in advance (see FIG. 1d). Then, a fibrous material layer 1 is formed thereon, and then a net-like material 2 is formed again.
place it on top of it. When laminating one layer of net-like material 2 between two fibrous material layers 1 (see Fig. 1b), after forming the first fibrous material layer 1, the net-like material 2 is placed on top of it. Place the second
What is necessary is to form the fiber material layer 1. Fiber material layer 1
Needless to say, it is possible to make the net layer 2 and the net layer 2 into a plurality of layers by using the above-mentioned combination (see FIGS. 1e and 1f).

It is desirable that the net-like material used here has a tensile strength of about 3 kg/cm ² or more. If the tensile strength is less than 3 kg/cm ² , the net-like material itself may be cut by the tensile force applied by the mold during deep drawing, resulting in cracks in the mat, or Matsutto is torn apart. However, the above-mentioned strength changes depending on where in the laminate the net-like material is provided. That is, when the net layer does not come into direct contact with the forming surface of the forming die during deep drawing, the tensile strength of the net-like material itself decreases as the distance between the forming surface and the net layer increases. It is clear that lower is better.

As for the material of the net-like article, any of synthetic fiber nets, glass fiber nets, cheesecloth, metal nets, etc. can be used. However, it is desirable to have a net-like material and structure that flexibly adapts to the molding die when the product is deep-drawn. For example, when using a thermoplastic resin net that has a melting point higher than the heating temperature used during heating and pressurization at the final stage of the molding mat manufacturing process and approximately the same as the curing temperature of the thermosetting resin, In the heating and pressing process during the production of molding mats, the mat may soften but not melt, and therefore the net structure can be maintained in the molding mat product. This improves the shape retention strength and handling properties of the product. Furthermore, when such a molding mat is deep-drawn, the net-like material is melted by heating above the curing temperature of the thermosetting resin, and therefore, the net-like material is particularly suitable for molding. When laminated on the surface of the mat, the surface of the molded product can be made smooth.

Further, when the net-like material is laminated within the layers of the molding mat, the material of the net-like material is preferably set at a temperature higher than the curing temperature of the thermosetting resin. This preserves the net structure in the product after deep drawing the molding mat, increasing the strength of the product.

The laminate obtained as described above is heated and pressed by a hot pressing device to obtain a mat for molding. The heating temperature at this time needs to be equal to or higher than the curing reaction initiation temperature of the thermosetting resin. The lower limit of this heating temperature is, when a thermosetting resin is used alone as the resin material, the heating temperature should be higher than the temperature at which the resin exhibits plasticity, thereby preventing fusion between the fibers and between the fibers and the net-like material. It becomes possible.

Further, when a thermoplastic resin is mixed as the resin material, the above-mentioned heating temperature needs to be at least higher than the melting point of the thermoplastic resin. As mentioned above,
When the amount of thermoplastic resin added is small, the thermosetting resin can also be used for fusion by heating at a temperature higher than the temperature at which the thermosetting resin exhibits plasticity.

The pressure can be adjusted as appropriate depending on the use of the molding mat, but in the case of a molding mat for deep drawing, it is preferable to set the pressure such that the specific gravity of the product is about 0.01 to 0.5. If the specific gravity is less than 0.01, even if it has shape retention ability, it will be too flexible and difficult to handle during transportation or molding, and if it is more than 0.5, the deep drawing processability will be poor.

The molding mat thus obtained has sufficient shape retention and tensile strength to withstand transportation and handling during molding.

When molding the molding mat, pressure is applied at a temperature higher than the curing temperature of the thermosetting resin. At this time, the thermosetting resin is once melted to break the fusion between the fibers and between the fibers and the net, allowing their mutual movement. The same applies when a thermoplastic resin is used in combination, since its melting point is selected to be lower than the curing temperature of the thermosetting resin. Thus, when compressed by the mold, the fibers conform to the molding surface and are also pushed or pulled by the deformation of the net and follow suit. Therefore, the force applied locally by the deep drawing die is easily transmitted to the surrounding area, and it conforms well to the die. As the curing reaction progresses, the fiber material and the net-like material are finally firmly fixed within the mat.

Effects Since the method of the present invention is a completely dry method, there is no need to dry the pine after forming, which saves thermal energy and time. In addition, there is no loss of resin material due to the addition of an excessive amount of resin in the wet method or the resin flowing out during dehydration, and the resin material can be saved.

Uniform mixing of fiber material and resin material results in liquid,
This can be achieved by appropriately using powdered, fibrous, etc. resins, or by using different mixing methods.

Since the net-like material is used, the bond between the fiber material and the net becomes even stronger, and especially when the net-like material is laminated between the fiber material layers, there is a bond between the fibers of the fiber material layers on both sides through the mesh of the net. Since fusion occurs, it becomes even stronger. As a result, the molding mat according to the present invention does not generate cracks during deep drawing.

When a net-like material is laminated on the surface of the laminate, a thermoplastic material having a melting point similar to the curing temperature of the thermosetting resin is used as the material for the net-like material after deep drawing processing. It can give the product surface smoothness.

When a net-like material is laminated within the layers of a laminate, by selecting a material with a melting point higher than the curing temperature of the thermosetting resin, the net structure will be preserved in the product after deep drawing. This can increase the strength of the product.

By using a net-like material, a mat for deep drawing can be obtained using only wood fibers without mixing long fiber materials.

A wide variety of molding mats can be provided by selecting the fiber material, resin material, net-like material, and lamination arrangement.

[Brief explanation of the drawing]

Figures 1a to 1f show some examples of variations in the laminated structure of the molding mat according to the invention. Explanation of symbols: 1...Fiber material layer, 2...Net layer (net-like material).

Claims (1)

[Scope of Claims] 1 A laminate of at least one fiber material layer consisting of a fiber material containing at least wood fiber and a resin material containing at least a thermosetting resin, and at least one layer of a net-like material is A molding mat characterized by being fused with materials. 2. The molding mat according to claim 1, wherein the fiber material is made of a mixture of relatively short wood fibers and relatively long long fibers that have a stronger tensile strength than the wood fibers. Characteristic molding pine. 3. The molding mat according to claim 2, wherein the long fibers are natural long fibers such as hemp, hemp, palm, etc. 4. The molding mat according to claim 2, wherein the long fibers are recycled fibers. 5. The molding mat according to claim 2, wherein the long fibers are a mixture of natural fibers such as hemp, hemp, palm, etc., and recycled wool. 6. The molding mat according to any one of claims 1 to 5, wherein the resin material comprises a thermosetting resin and a thermoplastic resin having a melting point lower than the curing temperature of the resin. A molding mat characterized by being a mixture of. 7. Uniformly mixing a fibrous material containing at least wood fibers and a resin material containing at least a thermosetting resin, forming the resulting mixture to form at least one fibrous material layer, and in the forming step, at least A sheet of net-like material is laminated on at least one of the front and back sides of the fiber material layer or between multiple fiber material layers, and the resulting laminate is heated at a temperature lower than the curing reaction initiation temperature of the thermosetting resin. 1. A method for producing a molding mat, which comprises heating the resin material at a temperature higher than a temperature at which at least a portion thereof exhibits plasticity, applying pressure, and then cooling the resin material to fuse the fiber material and the net-like material. 8. In the method described in claim 7,
A method for producing mat for molding, characterized in that the fiber material is a mixture of relatively short wood fibers and relatively long long fibers having a higher tensile strength than the wood fibers. 9. In the method recited in claim 8,
A method for producing mat for molding, characterized in that the long fibers are natural fibers such as hemp, hemp, palm, etc. 10. A method for manufacturing mat for molding according to claim 8, characterized in that recycled wool is used as the long fibers. 11. A method for producing pine for molding according to claim 8, characterized in that the long fibers are a mixture of natural fibers such as hemp, hemp, palm, etc., and recycled wool. 12. In the method according to any one of claims 7 to 11, the resin material includes a thermosetting resin and a thermoplastic resin having a melting point lower than the curing temperature of the resin. A method for producing a molding mat, characterized in that the heating temperature of the laminate is lower than the curing reaction start temperature of the thermosetting resin and higher than the melting point of the thermoplastic resin. 13. The method according to any one of claims 7 to 12, characterized in that the net-like material has a tensile strength of 3 kg/cm ^{2 or} more at room temperature. A method of manufacturing pine for molding. 14 Among claims 7 to 13,
In the method described in any one of the above, the net-like material laminated on the surface of the laminate is a net-like material made of a thermoplastic material having a melting point approximately equal to the curing temperature of the thermosetting resin. A method for manufacturing pine for molding, characterized by: 15 Among claims 7 to 14,
In the method according to any one of the above, the net-like material laminated on the inner layer or back surface of the laminate is a net-like material made of a material having a melting point higher than the heating temperature used during the molding process of the molding mat. A method for producing a molding mat characterized by using.