JPH0679807B2 - Flexible wood fiberboard and method for producing the same - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a wood fiber board having flexibility by a dry manufacturing method and a manufacturing method thereof.

(Prior art) Use of wood board or wood board, that is, plywood or hard fiber board, for the purpose of building materials that require curved surface processing, packing materials for coating along the curved surface of automobile interior materials, etc. In such a case, since these materials have poor flexibility, they are cut into narrow widths and then joined, or a flexible sheet such as rubber or cloth bonded in parallel with a small space is used. Alternatively, a means has been adopted in which those arranged in parallel on the adherend are fastened with another fastening material such as a wire or a belt. These methods have drawbacks in that the processing, construction method, and use method of materials are complicated and there are many steps. Moreover, there is a problem that the finish is not beautiful and the adhesion and covering property is poor. The hard fiber board is made by wet papermaking method or dry manufacturing method, in which phenolic resin and waterproofing agent are added to wood fiber defibrated from wood chips, the resin is hardened by hot pressing and the fiber is bonded, and it is called "hard board". As it can be said, it is not flexible and has the drawbacks of the wood board as it is. It is known that a soft fiber, that is, a wood fiberboard having a low density by a wet papermaking method, is given a latex to improve embossability, but a fiberboard having flexibility is known. Has not been done.

(Problems to be Solved by the Invention) It is an object of the present invention to provide a fiber board having flexibility by overcoming the above-mentioned drawback of the hard fiber board having almost no flexibility and impact absorbing ability. Another problem is how to advantageously manufacture a fiber board having the desired flexibility.

(Means and Actions for Solving Problems) According to the present invention, during the defibration of steamed wood chips, synthetic rubber latex is added in an amount of 3% by weight or more based on the solid content of wood fibers, and then air flow drying is performed. Bending characterized by using the obtained wood fiber with a water content of 6 to 10% and accumulating this wood fiber in a mat shape under the conditions of flat plate pressing pressure of 50 to 80 kg / cm ² and heating temperature of 120 to 180 ° C. A method for producing a hard wooden fiber board having flexibility, and a wooden hard fiber board having a thickness of 2.5 to 5.0 mm and a flexibility coefficient of 2.5 to 6.5 obtained by this dry manufacturing method.

Conventional hard fiber board manufacturing methods include a wet method for making a mat before hot pressing and a dry method for making a mat before hot pressing, but a wet method is often used. In the wet papermaking method, wood chips obtained by defibrating wood chips with a defibrating machine are dispersed in water several tens to several hundred times, and the slurry is mixed with phenol resin, wax and other waterproofing agents and other additives, and then sulfuric acid is added. After adding a band to fix phenol resin and other additives to the wood fiber, pour the slurry over the running wire mesh and let water flow down and remove by suction. Let it be a fiberboard. In the case of the dry method, the resin liquid is added to the defibrated fibers, and the sufficiently dried one is blown, collected by suction on the running wire net and accumulated in layers to form a mat, which is hot pressed to form a fiber board. .

In the present invention, a synthetic rubber latex is adopted as the fiber binder instead of the phenol resin. The addition of the synthetic latex to the wood fiber can be carried out by any of the wet papermaking method and the dry method. However, in the wet papermaking method, a large amount of water is removed even if it is fixed by the sulfuric acid band, so that 100% of the added synthetic rubber latex cannot be fixed on the wood fiber and 20% or more of the synthetic rubber latex flows out. It causes economic and process disadvantages. Also, during the drying of moisture in the mat due to heat and pressure, the latex easily migrates to the surface of the mat as the moisture moves. For this reason, the internal bond is insufficient, and it breaks due to bending. Furthermore, since the synthetic rubber latex is diluted with a large amount of water, it penetrates into the wood fibers and is intervened between the fibers to contribute to the flexibility. Therefore, it is extremely difficult to manufacture a flexible fiber board to which synthetic rubber latex is added by the wet papermaking method. On the other hand, in the dry manufacturing method, the disintegrated wood fiber is sprinkled with synthetic rubber latex and immediately dried, so that the concentration of the latex at the time of contact with the fiber is extremely high as compared with the case of wet papermaking and is dried as it is. Therefore, fibers having synthetic rubber attached to the surface can be obtained. It was found that the fibrous plate obtained by hot-pressing this contributes sufficiently to the bending property and the shock absorbing property because the synthetic rubber is uniformly distributed in the layer and intervenes between the fibers. Therefore, the dry manufacturing method is adopted in the present invention.

As the wood fiber used in the present invention, wood fiber obtained by a known method such as wood chips being steamed in a continuous steamer and then defibrated by a refiner or the like can be used. This wood fiber may be mixed with vegetable fiber such as waste paper, hemp, bagasse, straw, or synthetic fiber. or,
As the synthetic rubber latex, a latex of styrene-butadiene type, acrylonitrile-butadiene type, methacrylate butadiene type, chloroprene type synthetic rubber or a modified product thereof can be used.

The method for producing the flexible fiber board of the present invention will be described below. To facilitate the defibration of wood chips, it is steamed and then defibrated through a refiner to produce wood fibers. A required amount of synthetic rubber latex is injected into the fibers being defibrated so that they are evenly attached to the fibers during the defibration process. The amount of the synthetic rubber latex used may be 3% or more based on the weight of the solid content relative to the wood fiber, and the practical range is 3 to 40%, preferably 3 to 10%. A synthetic rubber latex having a concentration of 20 to 40% is supplied, and the synthetic rubber latex is applied to wood fiber as it is or after being diluted appropriately. Since the wood fiber to which the synthetic rubber latex is attached still contains a considerable amount of water, in order to remove it, the wood fiber is dried with an air flow dryer using hot air to a water content of 6 to 10%.

The dry fibers thus obtained are collected and laminated on a running wire net to obtain a wood fiber mat to which synthetic rubber is attached. Next, this wood fiber mat is cut into a certain length and 120-180
Insert into a multi-stage plate press heated to ℃, press pressure 50 ~
A wood fiber board having flexibility is obtained by heating and pressing at 80 kg / cm ² .

The pressing temperature is set to 120 to 180 ° C in order to promote the plasticization of the cellulose in the wood fiber by heating to soften the lignin and tightly bond the fibers. It is preferable that the synthetic rubber is aged at 180 ° C or higher. Absent. The greater the water content of the wood fiber to be pressed is, the more effective it is for plasticizing the fiber components.

The flexibility coefficient of the fiber board obtained by the present invention, that is, the ease of bending was determined as follows.

The bending coefficient was defined as the slope of the straight line obtained by plotting the load per cross section of the sample against the logarithm of the amount of bending mm, which was measured by applying a load to the center point of a sample having a width of 2 cm and a span of 15 cm. About dry fiberboard thickness 3.59mm (S35), 2.83mm (S3) with phenolic fiber as binder, fiberboard thickness 4.3mm (B4), 3.23mm (B3) of the present invention The plot is shown in FIG.

It has been shown that the product of the present invention has a large flexural flexibility with a small force. The flexibility coefficient of each sample in the figure is S35
1.82, S3 is 2.10, B4 is 3.77, B3 is 5.26. By the same test, it was revealed that the fiber board of the present invention had a flexural coefficient of 2.5 or more in the thickness range of 5.0 to 2.5 mm. When the amount of synthetic rubber latex added is about several percent, the value is in the range of about 2.5 to 6.6.

Examples 1 to 2 Continuously steamed wood chips were defibrated with a defibration machine, and fibers obtained by adding and mixing 25% SBR latex in the defibration to a solid content weight ratio of 4.5% and 8% were dried by air flow. 130-1 in the device
It was dried to a water content of 8% with hot air at a temperature of 40 ° C. A mat formed by using a dry mat production apparatus of a dry fiberboard manufacturing machine using this dry fiber has a pressing temperature of 150 ° C. and a pressing pressure of 7
Pressed under conditions of 0kg / cm ² and pressing time of 4 minutes, thickness 3.5mm
And fiberboard. The physical properties of the fiber board obtained are shown in Table 1.

Comparative Example 1 In the same manner as in Example 1, except that a phenol resin aqueous solution having a concentration of 20% was added to the fiber in an amount of 3% by weight of solid content and 1% of wax was added in place of the SBR latex in Example 1, was used. A dry fiberboard having a thickness of 3.5 mm was obtained.

The maximum radius of curvature was calculated from the deflection test result.

(Effects) As described above, the flexible wood fiberboard of the present invention has excellent flexibility, good impact absorption, and members that require curved surface processing, such as building materials, automobile interior materials, and coating along curved surfaces of articles. It can be advantageously used as a material for packaging, such as packaging material.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between the amount of deflection and the load of the wood fiberboard of the present invention and a comparative fiberboard.

Claims (2)

[Claims] 1. A wood fiber having a water content of 6 to 10% obtained by adding 3% or more of a synthetic rubber latex to a wood fiber in a solid content weight ratio during defibration of steamed wood chips and then air-drying. A method for producing a hard wood fiberboard having flexibility, which comprises hot-pressing the wood fibers in a mat form and pressing them at a flat plate pressing pressure of 50 to 80 kg / cm ² and a heating temperature of 120 to 180 ° C. 2. A wood fiber having a water content of 6 to 10% obtained by adding 3% or more of a synthetic rubber latex to a wood fiber in a solid content weight ratio during the defibration of steamed wood chips and then air drying. Is a fiberboard molded by a dry manufacturing method,
A wooden hard fiber board having flexibility, which has a flexibility coefficient of 2.5 to 5.0 mm and a flexibility coefficient of 2.5 to 6.5.