JPH0135960B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for constructing a fiberboard having a multilayer structure with excellent impact resistance, bending resistance, tensile strength, etc. by wet papermaking. Traditionally, wood fiberboards have been made from so-called thermomechanical pulp (TMP), which is made by steaming wood chips and then defibrating them using a disk-cliffing iner.
In addition, it is possible to construct relatively thick products in a single papermaking process, and by changing conditions such as press pressure during construction, it can be used for various purposes such as insulation materials, construction materials, furniture panels, packaging materials, and base materials for various molding materials. A suitable product is manufactured. However, fiberboard made only of thermomechanical pulp is inferior to other wood materials in terms of bending and impact resistance at the same specific gravity, so it is difficult to obtain the desired strength due to the thickness. It is necessary to use a fiberboard formed to be thick or to have a high specific gravity, and there is a desire to develop a fiberboard that is lightweight and has high bending and tensile strength. On the other hand, as a method to eliminate such strength defects of wood fiberboards, it has generally been proposed to manufacture wood fiberboards by mixing long fiber materials with excellent tensile strength such as hemp fibers or synthetic fibers into the thermomechanical pulp. However, when making a fiber mat made by mixing and dispersing long fiber material into thermomechanical pulp, it is necessary to change conditions such as the paper making speed depending on the amount of long fiber material added, or to change the type and amount of binder, etc. Cumbersome operations are required, and the strength performance of the obtained fiberboard is only improved gradually depending on the amount of the fiberboard mixed, and no dramatic improvement can be expected. Furthermore, for various industrial materials such as building materials, furniture materials, packaging materials, molding base materials, etc., depending on the purpose and the area of use, it may not be sufficient to simply improve the strength, and the cosmetic appearance of the surface may be insufficient. Various properties such as flexibility, smoothness, bending workability, bending resistance, and surface impact resistance are often required, and fiberboard with physical properties that meet these required performances can be produced in one production line. It was extremely difficult to form. In order to eliminate such drawbacks and problems, the present invention forms a laminated mat by mixing a wet mat made of thermomechanical pulp with a fibrous slurry mainly made of long fiber material, and The present invention provides a method for constructing a fiberboard having a novel multilayer structure that satisfies the above requirements by laminating, heating, pressing, and integrating a plurality of fiberboards without drying them. An embodiment of the present invention will be explained with reference to the drawings. First, as shown in FIG. 1, a slurry 1a mainly composed of thermomechanical pulp is made into paper using a circular mesh paper making machine to form a wet mat 1 having a desired thickness. At the same time, a fibrous slurry 2a mainly made of a long fiber material consisting of one or a mixture of two or more of kraft pulp, cotton fibers, synthetic fibers, and glass wool is mixed on the surface of the wet pine. A laminated mat 3 provided with a long fiber material layer 2 is formed. A small amount of binder or starch is added as a binding agent to the slurry 1a, which is mainly composed of thermomechanical pulp, and a small amount of fibrous materials such as waste paper and synthetic fibers, and sizing agents such as rosin and wax are added as needed. added. As for the paper-combining method, as shown in the figure, in addition to the method of directly pouring the fibrous slurry 2a onto the wet mat 1 and combining the paper, there is also a method of wetting long fiber material made by a separate fourdrinier machine or the like. A method may be adopted in which the sheets are placed on the wet mat 1 and then combined. Also, during such papermaking, an appropriate adhesive 4 is applied to the interface between the wet mat 1 and the long fiber material layer 2.
may be sprayed with a sprayer 5 or the like to increase the bonding strength between the two. Next, the laminated mat 3 thus made is cut into appropriate lengths, and without drying, a plurality of cut laminated mats 3a, 3 are cut.
A is superimposed to form a laminate 6, and this laminate 6 is inserted between hot plates 7 and 8 of a hot press, heated and pressed to be integrated. At this time, the laminated state of the plurality of laminated mats 3a, 3a depends on the purpose of use of the fiberboard to be obtained.
Furthermore, it is arbitrarily determined depending on the long fiber material used in the papermaking. For example, by using chemical pulp such as kraft pulp, which has long fiber length and strong tensile strength, as the long fiber material, surface smoothness and When trying to obtain a material with excellent bending strength, a plurality of laminated mats 3a, 3a are stacked on top of each other with the long fiber material layer 2 on the top side as shown in FIG. 1, or as shown in FIG. In this way, the outermost laminated mats 3a, 3a are laminated with the long fiber material layers 2, 2 facing outward, respectively, and integrated under heat and pressure. In this case, if a laminated mat made of synthetic fiber alone or mixed with kraft pulp or the like is used as the long fiber material, a fiberboard with improved surface water resistance and water absorption can be obtained. Further, as shown in FIG. 3, long fiber material layers 2, 2
The laminated mats 3a, 3a may be laminated and integrated with each other facing the inner surface. In this case, since the center layer is formed of a long fiber material with strong entanglement, the fibers have excellent bending resistance. In particular, when a material that irritates the skin, such as glass fiber, is used as the long fiber material, it is necessary to form a fiber board with a structure in which the long fiber material layers 2, 2 are arranged on the inner side. It is preferable to do this in terms of handling. After stacking the laminated mats 3a and 3a, as described above, they are inserted between the hot plates 7 and 8 of the hot press and heated and pressed until the specific gravity becomes 0.4 to 1.0. Differently, the fibers at the interface of each laminated mat 3a, 3a are entangled and integrated due to the movement of moisture, etc., and the thermomechanical pulp and long fiber material that constitute each laminated mat 3a, 3a are also entangled. Further, it is possible to obtain a fiberboard having a multilayer structure in which the interlayers are integrated by intertwining of fibers. In addition, when stacking a plurality of laminated mats 3a, if adhesive is applied to the interface of the laminated mats 3a, 3a in advance, and then the laminated mats 3a are laminated, and then heat-pressed, the bonding strength between the laminated mats 3a, 3a is further increased. , strength performance can be further improved. Further, the thickness of the long fiber material layer 2 of the laminated mat is not particularly limited, as it can be determined freely by simply adjusting the supply speed of the slurry 2a depending on the use of the fiberboard, but at least thermomechanical 60 on pulp wet mats 1
It is preferable to combine the sheets at a rate of g/m ² or more, since unevenness will not occur and the strength will be greatly improved. Next, specific examples and comparative examples of the present invention will be shown. Example: A slurry prepared by mixing 98 parts of thermomechanical pulp (TMP), 2 parts of phenol resin, and ±1.5 parts of ban sulfate was made into a wet mat with a fiber amount of 2000 g/m ² by using a circular mesh paper making machine. 98 parts of coniferous kraft pulp, 2 parts of phenolic resin, and vanium sulfate were formed on this wet mat.
Pulp slurry prepared by mixing 1.5 parts of pulp slurry is mixed at a mixing rate of 200 g/ ^m2 , and the resulting laminated mat is cut into appropriate dimensions, and the long fiber material layer is removed without drying. Stack two sheets facing upwards and heat press at 180℃ for 20 minutes.
After heating and pressurizing at Kg/cm ² for 1 minute,
Heat and pressurize at 5Kg/ ^cm2 for 9 minutes, specific gravity 0.8, thickness 5.5
A fiber board was obtained consisting of four layers of mm (thickness of thermomechanical pulp 2.5×2, thickness of long fiber material layer 0.25×2). On the other hand, as Comparative Example A, a slurry mainly composed of the thermomechanical pulp, that is, 98 parts of thermomechanical pulp (TMP), 2 parts of phenol resin,
A wet mat made from a slurry consisting of 1.5 parts of aluminum sulfate and 1.5 parts of aluminum sulfate was heated and pressed under the same conditions as in the above example to form a fiberboard with a specific gravity of 0.8 and a thickness of 5.5 mm. In addition, as Comparative Example B, 89.1 parts of thermomechanical pulp (TMP), 8.9 parts of softwood kraft pulp,
Fiber amount 4400g/m ² from slurry prepared by mixing 2 parts of phenolic resin and 1.5 parts of aluminum sulfate.
A wet mat was made into paper and heated and pressed under the same conditions as in the example to form a fiberboard with a specific gravity of 0.8 and a thickness of 5.5 mm. The physical properties of Examples and Comparative Examples A and B thus obtained are shown below. However, in the example, the long fiber material layer was placed on the tension side and tested.

[Table] As is clear from the above table, the fiberboards obtained in the Examples of the present invention exhibited superior physical properties in terms of both bending strength and impact resistance compared to the fiberboards of Comparative Examples A and B. Ta. As described above, the present invention provides a wet mat made of thermomechanical pulp, on at least one side of which is coated with a fibrous material mainly consisting of a long fiber material consisting of kraft pulp, cotton fiber, synthetic fiber, glass wool alone or in a mixture thereof. A method of constructing a fiberboard having a multilayer structure, which comprises: mixing slurry to form a laminated mat, and then laminating a plurality of the laminated mats without drying and heat-pressing them to integrate them. Therefore, it is possible to easily obtain a fiberboard with excellent bending strength and impact resistance by integrally layering the thermomechanical pulp and the long fiber material layer in multiple layers, and in this case, the long fiber material layer By making the surface cosmetic, smoothness,
While it is possible to form a fiberboard with excellent bending properties, it is also possible to form a fiberboard with excellent bending resistance by disposing a long fiber material layer in the inner layer. It is something that can be easily obtained.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and FIG. 1 is a simplified side view showing the construction process, and FIGS.
The figures are explanatory views showing different overlapping states of the laminated mats. 1... wet mat, 2... long fiber material layer,
3a...Laminated mat, 6...Laminated body.

Claims (1)

[Scope of Claims] 1. A fibrous slurry mainly consisting of a long fiber material consisting of kraft pulp, cotton fiber, synthetic fiber, glass wool alone or a mixture thereof, on at least one side of a wet mat made from thermomechanical pulp. A method for producing a fiberboard having a multilayer structure, which comprises: forming a laminated mat by combining the laminated mats, and then laminating a plurality of the laminated mats without drying and heat-pressing them to integrate them. 2. A method for manufacturing a fiberboard having a multilayer structure according to claim 1, characterized in that the laminated mats are laminated and integrated by applying an adhesive to their interfaces. 3. Production of a fiberboard having a multilayer structure according to claim 1 or 2, characterized in that the laminated mat is laminated and integrated so that at least one of the long fiber material layers is on the outer surface side. Method. 4. A method for producing a fiberboard having a multilayer structure according to claim 1 or 2, characterized in that the laminated mat is laminated and integrated so that the long fiber material layer faces the inner surface. 5 Claims 1 and 2, characterized in that the material is heated and pressed until the overall specific gravity becomes 0.4 to 1.0.
A method for manufacturing a fiberboard having a multilayer structure according to item 1, 3 or 4.