JP2014091887A - Method for manufacturing fiber board and fiber board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a fiber board, which can easily manufacture a fiber board that contains large amounts of resin and has superior strength and dimensional stability even when containing moisture, even though being manufactured through a wet papermaking method, and to provide a fiber board that is manufactured through the method for manufacturing the fiber board and contains relatively large amounts of resin.SOLUTION: The method for manufacturing the fiber board comprises: a first step of forming a first papermaking product 2 from slurry 1 in which a vegetable fiber and a thermosetting resin composition, which are a main component, are dispersed in water, and dehydrating the first papermaking product by cold pressing; a second step of drying a dehydrated second papermaking product 3 at a temperature lower than a curing temperature of the thermosetting resin composition, and selectively reducing moisture from the second papermaking product, after the first step; and a third step of heating and pressure-molding a dried third papermaking product 4, and curing the thermosetting resin composition, after the second step.

Description

  The present invention relates to a fiberboard manufacturing method and a fiberboard.

  Conventionally, fiberboards containing vegetable fibers have been used in a wide range of fields as building materials for residential flooring, wall materials, door materials and the like. The fiberboard is manufactured, for example, by heat-pressing a paper product obtained by paper-making (wet paper-making method) a slurry containing vegetable fibers, an adhesive (resin), a sizing agent, and the like (for example, patent document) 1).

  In order to use the fiberboard obtained by the wet papermaking method as a building material, it is necessary to adjust the resin content to an appropriate level to develop strength and dimensional stability during moisture absorption. On the other hand, if the resin content is low to some extent and a low-viscosity slurry is not used, there may be a problem that handling properties at the time of papermaking deteriorate.

  In the manufacturing method of the fiberboard described in Patent Document 1, the surface layer and the back layer of the paper product are semi-cured by heat-pressing a thermosetting resin composition contained as an adhesive component in the paper product. Then, the thermosetting resin composition in the papermaking is completely cured by hot air drying. For this reason, in the fiberboard described in Patent Document 1, the density of the surface layer and the back layer is high, whereas the core layer has a low density.

JP 2009-107196 A

  However, in the fiberboard manufacturing method described in Patent Document 1, since the paper product is subjected to heat and pressure molding with a high water content, it is not always easy to increase the content of the thermosetting resin composition. In some aspects, it cannot be said that the strength of the fiberboard and the dimensional stability during moisture absorption are good.

  The present invention has been made in view of the circumstances as described above, and easily manufactures a fiberboard having a high resin content and excellent strength and dimensional stability during moisture absorption while being manufactured by a wet papermaking method. It is an object of the present invention to provide a fiberboard manufacturing method that can be used, and a fiberboard manufactured by this fiberboard manufacturing method and having a relatively high resin content.

  In the fiberboard manufacturing method of the present invention, the first paper product is made from a slurry obtained by dispersing the main plant fibers and the thermosetting resin composition in water, and the first paper product is cold-pressed. The first step of dehydration, and after the first step, the dehydrated second paper product is dried at a temperature lower than the curing temperature of the thermosetting resin composition, and moisture is selectively reduced from the second paper product. And a third step of heat-pressing the dried third paper product to cure the thermosetting resin composition after the second step.

In this fiberboard manufacturing method, in the first step, it is preferable to dehydrate until the water content of the first paper product is 60% by mass or less. In this fiberboard manufacturing method, in the second step The second paper product is preferably dried until the water content is 10% by mass or less.

  The fiberboard of the present invention is a fiberboard manufactured by a wet papermaking method from a slurry obtained by dispersing the main plant fibers and a thermosetting resin composition in water, and the resin content is 5% by mass or more. It is characterized by being 40% by mass or less.

  According to the fiberboard manufacturing method and fiberboard of the present invention, it is possible to easily manufacture a fiberboard having a high resin content and excellent strength and dimensional stability during moisture absorption while being manufactured by a wet papermaking method. And a fiberboard having a relatively high resin content can be provided.

It is process sectional drawing which showed schematically the manufacturing method of the fiber board of this invention.

  Hereinafter, the manufacturing method of the fiberboard of this invention is demonstrated in detail along figures.

  FIG. 1 is a process cross-sectional view schematically showing the fiberboard manufacturing method of the present invention.

  In this fiberboard manufacturing method, as the first step, the first papermaking 2 is made from the slurry 1 in which the main plant fiber and the thermosetting resin composition are dispersed in water, Papermaking 2 is dehydrated with a cold press. After the first step, as the second step, the dehydrated second paper product 3 is dried at a temperature lower than the curing temperature of the thermosetting resin composition, and moisture is selectively reduced from the second paper product 3. Let After the second step, as the third step, the dried third papermaking product 4 is heated and pressed to cure the thermosetting resin composition. In this way, the fiberboard 5 is manufactured.

  Specifically, in the first step, the plant fiber and the thermosetting resin composition are dispersed in water to prepare the slurry 1.

  Any plant fiber can be used without particular limitation as long as it is a plant fiber used for the fiberboard 5. Examples thereof include fibers collected from basts of hemp plants such as kenaf, flax, ramie, cannabis and jute, and fibers collected from stem or leaf muscles of hemp plants such as manila hemp and sisal hemp. Moreover, what used alone or combined these 2 or more types of wood fibers (natural fiber), such as a softwood fiber and a hardwood fiber, is illustrated. Moreover, the fiber which uses agricultural wastes, such as sugarcane, corn, bamboo, and rice, as a raw material like the squeezed residue after boiling sugar from sugarcane is illustrated. Fibers mainly composed of hemp plants, for example, those in which the fibers of hemp plants are 50% by mass or more in the total mass of plant fibers are about 2 to 2% compared to wood fibers such as coniferous fibers and hardwood fibers. It has 14 times higher tensile strength. The fiberboard 5 manufactured by orienting the above plant fibers can effectively utilize the high tensile strength of the plant fibers themselves. That is, the fiberboard 5 having particularly excellent performance with respect to bending performance and length change due to temperature change and humidity change is realized.

  The length of the vegetable fiber is not particularly limited, but is preferably 5 to 100 mm. By using vegetable fibers having a length within the above range, many entanglements of fibers in the fiberboard 5 after the heat and pressure molding are present. Moreover, the adhesion part of the thermosetting resin composition per fiber can also be increased. Furthermore, since the joint part between plant fibers can be reduced, the high tensile strength of the plant fiber itself can be utilized more effectively. For this reason, the fiber board 5 which has the performance more excellent with respect to intensity | strength, surface hardness, the length change by a temperature change or a humidity change, dimensional stability, etc. is implement | achieved.

  The above plant fiber is obtained by mechanically defibrating plant raw materials.

  The vegetable fiber is uniformly dispersed in water at a concentration of 2 to 10% by mass, for example.

  The thermosetting resin composition is mainly composed of a thermosetting resin. A sizing agent or the like can be added to the thermosetting resin composition as necessary. By adding an adhesive, the strength of the board body can be improved and the handling property can be improved.

  As the thermosetting resin, any resin that is usually used for the fiberboard 5 can be used without particular limitation. For example, a thermosetting resin such as a vinyl ester resin, a thermosetting acrylic resin, or an epoxy resin can be used alone. Alternatively, two or more of these can be used in combination.

  As the vinyl ester resin, for example, a bisphenol type vinyl ester resin, a novolac type vinyl ester resin, or a mixture of both can be used.

  Here, the bisphenol-type vinyl ester resin is an addition reaction product of a bisphenol-type epoxy resin and an acid, and both have reactive unsaturated groups only at both ends. As the bisphenol type epoxy resin, various types such as a bisphenol A type, a bisphenol AD type, a bisphenol S type, and a bisphenol F type can be used. Usually, the vinyl ester resin contains a styrene monomer, an acrylic monomer or the like as a crosslinking agent, but its composition is not particularly limited.

  As the thermosetting acrylic resin, for example, what is called an acrylic syrup composed of a mixture of two or more of methyl methacrylate monomer, polyfunctional acrylic monomer, prepolymer, or polymer can be used. Of course, the form is not particularly limited.

  Epoxy resins are generally bisphenol A type epoxy resins, bisphenol F type epoxy resins, novolac type epoxy resins, cyclic aliphatic type epoxy resins, long chain aliphatic type epoxy resins, glycidyl ester type epoxy resins, glycidyl amine type epoxy resins, etc. are categorized. Any epoxy resin can be used.

  Examples of the epoxy resin curing agent include amine-based curing agents such as diethylenetriamine, triethylenetetramine, metaphenylenediamine, diaminodiphenylmethane, and diaminophenylsulfone. Moreover, acid anhydride type curing agents such as phthalic anhydride, tetra- and hexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methyl nadic anhydride, pyromellitic anhydride, HET anhydride, dodecenyl succinic anhydride and the like are exemplified. Moreover, the polyamide type hardening | curing agent etc. which are formed as a condensate of a dimer acid and a polyamine are illustrated.

  Usually, an amine-based curing agent is selected for a room temperature to medium temperature curing system, and an acid anhydride curing agent is selected for a high-temperature system, which can obtain a molded product with a slow curing reaction and a small molding distortion even with a large molded product.

  In addition to the vinyl ester resin, the thermosetting acrylic resin, or the epoxy resin as described above, the resin can be used in combination of two or more kinds, and an optimum blending that meets the desired product quality is considered.

  Such a thermosetting resin composition is also uniformly dispersed in water like the vegetable fiber.

  Slurry 1 can be made by a known method such as a round net method or a long net method.

  The obtained first papermaking 2 is dehydrated by a cold press. In the cold press, for example, a continuous press device that conveys the first paper product 2 while applying pressure to a gap between a pair of steel belts, or a multi-stage press device that presses the first paper product 2 between metal plates. Etc. can be used. The dehydrating conditions are not particularly limited, but a range of a molding pressure of 0.5 to 4 MPa at room temperature is preferably exemplified. The pressing time can be appropriately set according to the plate thickness and the molding conditions in the subsequent fiberboard 5 forming step. For example, 1 to 5 minutes is exemplified. Due to the dewatering of the first papermaking 2 by such a cold press, the handleability of the second papermaking 3 after dehydration is improved. For this reason, the following 2nd process can be performed smoothly. The water content of the second papermaking 3 after dehydration is preferably 60% by mass or less.

  In the second step, the second paper product 3 is dried, and water is removed from the second paper product 3 by removing moisture while leaving the thermosetting resin. For example, a drying furnace can be used for drying at this time. The drying conditions are not particularly limited as long as the drying temperature is equal to or lower than the curing temperature of the thermosetting resin composition in the third papermaking 4, but a temperature range of 60 to 120 ° C is preferable. It is preferable that the moisture content of the 3rd papermaking 4 after drying is 10 mass% or less. This is because it is difficult for the thermosetting resin to flow out together with moisture during the heat and pressure molding of the third papermaking 4 in the third step.

  In a 3rd process, the 3rd papermaking 4 is heat-press-molded, and a thermosetting resin composition is hardened. In heat-pressure molding, for example, a continuous press device that conveys the third paper product 4 while applying pressure to a gap between a pair of heated steel belts, or a third paper product 4 between a plurality of heated hot plates. A multi-stage press device or the like that pressurizes the substrate can be used. The molding conditions are not particularly limited, but examples include a molding temperature of 80 to 220 ° C. and a molding pressure of 0.5 to 4 MPa. The molding time can be appropriately set in consideration of the plate thickness, molding temperature, and the like.

The fiberboard 5 obtained after such heat-press molding has a resin content of 5% by mass or more and 40% by mass or less, and has a higher resin content than conventional products. Although there is no restriction | limiting in particular in the thickness of the fiber board 5, 1-12 mm is illustrated, for example. Considering the strength characteristics, dimensional stability, and the like of the fiberboard 5, it is preferable that the thickness is 1.5 mm or more. The density of the fiberboard 5 is not particularly limited, but can be within a range of 650 to 950 kg / m ³ in order to obtain a fiberboard 5 having a balance between strength characteristics and dimensional stability. In order to further improve the strength characteristics, the density of the fiberboard 5 is preferably in the range of 700 to 900 kg / m ³ .

  In the fiberboard manufacturing method described above, prior to heat-pressure molding, the dewatered second paper product 3 is dried at a temperature not higher than the curing temperature of the thermosetting resin composition to selectively reduce moisture. Therefore, it becomes possible to increase the resin content of the fiberboard 5 as compared with the conventional wet papermaking method. In addition, it is possible to easily manufacture the fiberboard 5 having excellent strength and dimensional stability during moisture absorption. The fiberboard 5 can be suitably used in a wide range of fields as a building material such as a flooring material for a house, a wall material, and a door material.

Although an Example is shown below, the manufacturing method and fiberboard of the fiberboard of this invention are not limited to this.
<Example>
As a vegetable fiber, a fiber bundle collected from kenaf was mechanically defibrated to obtain a kenaf fiber having a fiber length of 10 to 50 mm. A slurry in which kenaf fiber and a phenol resin as a thermosetting resin were uniformly dispersed in water was prepared. The phenol resin in the slurry was resin solid content of 40% by mass, and paper was made from this slurry by a conventional method to obtain a first paper product. This first papermaking product was cold-pressed by a press device under conditions of a pressure of 3 MPa and a time of 3 minutes, and dehydrated until the water content became 60% by mass. The second paper product after dehydration had good handling properties. This second papermaking product was dried by blowing hot air at 100 ° C., which is lower than the curing temperature of the phenolic resin, for 10 minutes in a drying furnace to selectively reduce moisture. The 3rd papermaking after drying was heat-press-molded with the press apparatus on conditions of temperature 200 degreeC, pressure 3MPa, and time 3 minutes. Thus, a fiberboard having a thickness of 1.5 mm and a density of 800 kg / m ³ was obtained.
<Comparative example>
A fiberboard was produced using kenaf fibers obtained in the same manner as in the examples. Prior to hot pressing, the paper product was the same as in the example except that the paper product was not dried. A fiberboard having a density of 800 kg / m ³ was obtained.

  About the fiberboard obtained by the Example and the comparative example, resin content, bending strength, and the moisture absorption length change rate were measured, and the physical property was evaluated.

  The bending strength and the rate of change in moisture absorption length were measured in accordance with the methods specified in JIS A 5905 (fiberboard).

  The evaluation results are shown in Table 1.

  As shown in Table 1, when the resin content in the fiberboard was calculated by measuring the weight before and after the acetone extraction, the resin content of the fiberboard obtained in the example was 20% by mass. The bending strength was 40 MPa, and the rate of change in moisture absorption length was 0.10%.

  On the other hand, the resin content of the fiberboard obtained in the comparative example was 0.50% by mass. The bending strength was 30 MPa, and the rate of change in moisture absorption length was 0.30%.

  The fiberboards obtained in the examples had a higher resin content and better bending strength and moisture absorption length change rate than the fiberboards obtained in the comparative examples. From this, prior to heat-pressure molding, by drying the paper product after dehydration at a temperature below the curing temperature of the thermosetting resin composition, and selectively reducing the moisture, In comparison, it was confirmed that the resin content of the fiberboard can be increased. Thus, since the resin content was increased, it was also confirmed that the strength and dimensional stability of the fiberboard were improved.

DESCRIPTION OF SYMBOLS 1 Slurry 2 1st papermaking 3 2nd papermaking 4 3rd papermaking 5 Fiber board

Claims (4)

A first step of making a first paper product from a slurry obtained by dispersing the main plant fiber and thermosetting resin composition in water, and dehydrating the first paper product by a cold press;
After the first step, the dehydrated second paper product is dried at a temperature equal to or lower than the curing temperature of the thermosetting resin composition, and the second step of selectively reducing moisture from the second paper product; ,
After the second step, a third step of heat-pressing the dried third paper product and curing the thermosetting resin composition;
The manufacturing method of the fiber board characterized by including.   The method for producing a fiberboard according to claim 1, wherein, in the first step, dehydration is performed until a moisture content of the first papermaking product is 60% by mass or less.   2. The method for producing a fiberboard according to claim 1, wherein in the second step, drying is performed until a moisture content of the second papermaking product is 10% by mass or less. A fiberboard manufactured by a wet papermaking method from a slurry obtained by dispersing the main vegetable fiber and thermosetting resin composition in water, and the resin content is 5% by mass or more and 40% by mass or less. A fiberboard characterized by.

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