JP4324521B2 - Manufacturing method of carbonized board - Google Patents

Description

  INDUSTRIAL APPLICABILITY The present invention is a productive production of carbonized board having excellent heat insulation, moderate strength and elasticity, which can be used for ceiling materials, wall base materials, tatami floors, panel core materials, etc. of buildings such as houses. Regarding the method.

  2. Description of the Related Art Conventionally, a material obtained by carbonizing a plant material such as a wood material has been known as a material having good adsorbability such as heat insulation, humidity control, and VOC (volatile organic compound). For example, Patent Document 1 proposes a carbonized wood fiber heat insulating material in the form of cotton obtained by carbonizing wood fibers obtained by pulverizing used paper such as newspaper. Patent Document 2 proposes a wood fiber board in which wood fibers and fibrous charcoal are molded and integrated with an adhesive.

  However, the carbonized wood fiber heat insulating material described in Patent Document 1 is in a cotton-like form and is used by blowing into the internal space of the outer wall or floor, and therefore cannot be used in the form of a self-supporting board for handling. In addition, its use as a building material is remarkably limited, and there is a problem that special equipment is required for construction.

  In addition, the wood fiberboard described in Patent Document 2 has 50% by weight or less of fibrous charcoal added thereto, so it can be expected to improve adsorption performance and humidity control performance such as VOC to some extent, but its specific gravity is Since it is as high as 0.35 or more, there is a problem that although it has excellent strength properties, it has poor heat insulation.

  Although it is conceivable to form a low specific gravity board excellent in heat insulation using carbonized wood fibers as described in Patent Documents 1 and 2, in this case, the fibers are elasticized by carbonization. However, there is a problem that it is difficult to form a board having a low specific gravity excellent in heat insulation.

On the other hand, JIS A 5905 to defined by the insulation board are designated wood fiber board, its density, for example less than what is 0.27 g / cm ³ used in the tatami core (typically 0.20 g / cm ³ ˜0.25 g / cm ³ ), Class A materials used for heat insulating plates are less than 0.35 (usually about 0.23 g / cm ^{3 to} 0.30 g / cm ³ ), light weight and appropriate strength and elasticity For example, even in the case of a Class A insulation board having a density of 0.27 g / cm ³ , the thermal conductivity is about 0.049 W / mK, which is not sufficient. It was.
JP 2003-251616 A Japanese Patent No. 3523624

  The present invention has been made in view of such problems, and provides a method for producing a carbonized board that is excellent in heat insulation and can produce a carbonized board having moderate strength and elasticity as a board with high productivity. Objective.

In the method for producing carbonized board according to the invention of claim 1, the wood fiber obtained by steaming and defibrating the wood material is steamed in an alkaline solution and then molded, and the total dry density is 0.05 kg / cm ^{3 to} 0.00. It is formed into a 35 kg / cm ³ wood fiber board, and the wood fiber board is heated and carbonized in an inert gas atmosphere.

The method for manufacturing the board according to the invention of claim 2 is the invention of claim 1, the cooking in an alkaline solution, temperature 140 ° C. to 190 ° C., to make a pressure 6kg / cm ² ~9kg / cm ² Features.

A method for producing a carbonized board according to a third aspect of the invention is characterized in that, in the invention according to any one of the first or second aspects, the carbonization treatment is performed under heating at a maximum temperature of 400 ° C to 800 ° C.

According to the invention of claim 1, the wood fiber obtained by steaming and defibrating is further steamed in an alkaline solution and once molded, and a light wood having a total dry density of 0.05 g / cm ^{3 to} 0.35 g / cm ^3. After forming the fiberboard, the wood fiberboard is heated and carbonized in an inert gas atmosphere, so a carbonized board made of carbonized wood fiber that is lightweight, has excellent heat insulation properties, and has an appropriate strength. It can be manufactured with high productivity. In addition, the wood fiber board formed from the wood fiber in which a part of the steam soluble component in the wood material component has been removed in advance by steaming defibration and the ratio of the crystalline cellulose content is high is carbonized. It can be formed into a carbonized board having improved elasticity and moderate elasticity.

Moreover, since the wood fiber obtained by steaming and defibrating the wood fiber further steamed in an alkaline solution can be used, the proportion of crystalline cellulose can be further increased. In addition to the effect of the invention of claim 1 Thus, a carbonized board having further excellent strength and elasticity can be formed.

According to the invention of claim 2, in the invention of claim 1 , the optimum temperature and pressure conditions for steaming in the alkaline solution are adopted. In addition to the effect of the invention of claim 1 , in the alkaline solution Steaming can be performed efficiently with high productivity.

According to the invention of claim 3, in the invention of claim 1 or 2 , the carbonization treatment is performed under heating at a maximum temperature of 400 ° C. to 800 ° C., whereby the invention of claim 1 or 2 is performed. In addition to the above effect, the carbonization can be performed with higher productivity.

  Embodiments of the present invention will be described below. In addition, this invention is not limited to the following embodiment at all. In the present invention, various kinds of coniferous wood, hardwood, thinned wood, wood construction waste, wood scraps, waste pallets, waste formwork, and other wooden industrial waste materials, such as chip shapes using chippers and flakers, etc. This wood piece is made of wood pieces, put into a digester according to a conventional method, steamed by processing at high temperature and high pressure in the presence of steaming liquid, and the cooked wood pieces are defibrated with a pulper or refiner. To obtain wood fiber.

  In this case, it is desirable that wood fibers have a length of about 2.0 mm to 30 mm and occupy most of them. When many things less than 2.0 mm or more than 30 mm are contained, the moldability when forming into a wood fiber board using a wet or dry molding apparatus to be described later is deteriorated, and fine wood fibers particularly less than 2.0 mm are formed. If the number is increased, the strength and elasticity of the carbonized board obtained are lowered, which is not preferable.

  Next, the wood fiber obtained above is put into a steaming apparatus such as a digester, immersed in a mixed alkaline aqueous solution of sodium hydroxide and sodium sulfide, and steamed at high temperature and high pressure. In addition to the mixed alkaline aqueous solution described above, an alkaline aqueous solution prepared by mixing sodium carbonate, sodium sulfate, sodium sulfite or the like alone or in combination can also be used as the alkaline aqueous solution. The active alkali concentration in the alkaline aqueous solution is desirably about 40 g to 70 g per liter of the alkaline aqueous solution. Further, the ratio of the activated alkali to the wood fibers is preferably about 10 to 25% by weight based on the total dry weight of the wood fibers.

  If the active alkali concentration in the aqueous alkali solution is less than 40 g per liter of the aqueous alkali solution, it is not preferable because much processing time is required and the productivity is lowered, and if it exceeds 70 g, the processing cost increases. Further, when the weight ratio of the active alkali to the total dry wood fiber is less than 15% by weight, the unreacted wood component is not preferable, and when it exceeds 25 g, the unreacted alkali component is increased.

Also, high-temperature and high-pressure treatment of during cooking of the wood fibers, the maximum temperature of 140 ° C. to 190 ° C. preferably 170 ° C. to 180 ° C. digester such closed container, maximum pressure is 6kg / cm ² ~9kg / cm ² preferably It is carried out at 7kg / cm ² ~8kg / cm ² about the conditions. If the maximum temperature is less than 140 ° C., the elution of the eluted components by the alkaline cooking liquid such as lignin is not preferable, and if it exceeds 190 ° C., decomposition of cellulose proceeds, which is not preferable. Further, if the maximum pressure is less than 6 kg / cm ² , it is not preferable because much processing time is required, and if it exceeds 9 kg / cm ² , it is not preferable because high energy is required.

  In this way, the wood fibers obtained by steaming and defibrating the wood pieces are further steamed with an alkaline aqueous solution, so that some of the components other than cellulose in the wood fibers are further removed and the fibers are more cellulose-rich. Therefore, it can be formed into a good wood fiber capable of expressing appropriate strength and elasticity (flexibility) and heat insulation during carbonization of the wood fiber board described later.

  In addition, as a wood fiber, what is obtained by steaming and defibrating a small piece of wood without steaming with the alkaline aqueous solution can also be used. In addition, waste paper fibers obtained by defibrating waste paper or cardboard with hydropulper, coconut shell fibers, bagasse fibers, kenaf fibers, and other plant fibers can also be used as wood fibers in a broad sense in the same manner as wood fibers.

  Next, a wood fiber composition obtained by adding a wood fiber composition obtained by adding an additive such as a binder to the wood fiber obtained as described above, using a known wet papermaking method or dry papermaking method, etc. To form.

  When using a binder, for example, when forming a wood fiber board by a wet papermaking method, starches such as corn starch, thermoplastic resins such as polyvinyl alcohol and ethylene vinyl alcohol, or phenol resins, melamine resins, urea resins, urea- A binder made of a thermosetting resin such as melamine isocyanate resin or a mixed resin thereof can be added to the slurry, usually about 1 to 10% by weight with respect to the wood fiber. Moreover, when shape | molding a wood fiber board with a dry-type papermaking method, the said starches, a melamine resin, etc. can be normally added and used about 5 to 30 weight% with respect to wood fiber. In addition to the binder, a flame retardant, a water resistant agent, a fixing agent, a water repellent, and the like can be added as necessary as additives.

Wood fiber board which is molded in this way, the entire dry density in the range of 0.05g / cm ³ ~0.35g / cm ³ particularly 0.10g / cm ³ ~0.35g / cm ³ Is preferred. When the density is less than 0.05 g / cm ³ , the strength properties of the carbonized board obtained by the carbonization process described later are deteriorated and are not easily damaged, and the density exceeds 0.35 g / cm ³ . And, since the heat insulation of the carbonized board obtained becomes low, it is not preferable.

  As such a fiberboard, an insulation board such as a tatami board or a class A insulation board, which is specified in JIS A 5905 and is commercially available, can also be used.

  Next, the wood fiber board is carried into a known carbonization furnace such as an indirect heating type or a direct heating type, and the air in the carbonization furnace is replaced with an inert gas such as nitrogen gas, followed by heating, and the wood fiber board is sufficiently To form a carbonized board.

  The carbonization conditions are not particularly limited, but in order to improve production efficiency, heating is performed so that the maximum temperature reaches 400 ° C to 800 ° C, preferably 600 ° C to 800 ° C. By maintaining the close temperature for about 30 minutes to 100 minutes, a carbonized board made of wood fiber board that is well carbonized can be produced with high productivity.

  Next, examples of the present invention will be described.

Example 1
Coniferous wood fibers obtained by steaming and defibrating wood chips made of coniferous materials such as pine and cedar are placed in a sealed pressure vessel together with a steaming aqueous solution containing 3.75% by weight sodium hydroxide and 1.25% by weight sodium sulfide. Supplied.

Here, the steaming aqueous solution is adjusted so that the weight of the active alkali is 50 g with respect to 1 liter of the steaming aqueous solution, and the weight of the active alkali with respect to the weight of the total dry wood fiber is 20% by weight. The amount of the steaming aqueous solution and the amount of wood fiber were adjusted so that the degree of sulfidation was 25% by weight. The degree of sulfidization is the content of sodium sulfide in the alkaline solution, and is derived from Na ₂ S / (NaOH + Na ₂ S) × 100 (%).

Next, the inside of the sealed container is heated and pressurized to maintain the maximum temperature of 170 ° C. for about 90 minutes under the high temperature and high pressure conditions of the maximum temperature of 170 ° C. and the maximum pressure of 7 kg / cm ^2. did.

Next, 95 parts by weight of the wood fiber obtained above and 5 parts by weight of corn starch (Nissan Corn Starch Y: manufactured by Nippon Shokuhin Kako Co., Ltd.) are mixed and stirred with a large amount of water to prepare a slurry of wood fiber. Was formed into a wet mat and dried with a dryer at 150 ° C. to 170 ° C. to obtain a wood fiber board having a thickness of 12 mm and a density of 0.07 g / cm ³ .

  Next, the obtained wood fiberboard is supplied to an indirect heating type carbonization furnace, and after the air in the carbonization furnace is replaced with nitrogen gas, the temperature in the carbonization furnace becomes 600 ° C. at a temperature rising rate of 5 ° C./1 minute. After that, the inside of the carbonization furnace was maintained at the above-mentioned temperature of about 600 ° C. for about 60 minutes to prepare a carbonized board.

The obtained carbonized board according to Example 1 had a thickness of 10 mm and a density of 0.05 g / cm ³ . And thermal conductivity was measured based on JIS A 1412-2. Moreover, the compression elasticity test was done based on JISL1097, and the compression rate and its recovery rate were measured. The results are shown in Table 1.

(Example 2)
The coniferous wood fiber obtained in the same manner as in Example 1 is steamed with the same alkali steaming solution as in Example 1 in a sealed pressure-resistant container under the same conditions as in Example 1, and the same alkali steaming treated wood as in Example 1. Fiber was obtained.

Next, 85 parts by weight of the wood fiber obtained above and 15 parts by weight of corn starch used in Example 1 were mixed and dried, and then exposed to 150 ° C. steam and hot air to cure the corn starch. A wood fiber board having a thickness of 25 mm and a density of 0.08 g / cm ³ was obtained.

  Next, after supplying the obtained wood fiber board to an indirect heating type carbonization furnace and replacing the air in the carbonization furnace with nitrogen gas, until the inside of the carbonization furnace reaches 800 ° C. at a temperature rising rate of 5 ° C./min. The temperature was raised, and then the inside of the carbonizing furnace was maintained at the above temperature of about 800 ° C. for about 60 minutes to prepare a carbonizing board according to Example 2.

The obtained carbonized board had a thickness of 20 mm and a density of 0.06 g / cm ³ . Then, the thermal conductivity was measured in the same manner as in Example 1. The results are shown in Table 1.

(Example 3)
The coniferous wood fiber obtained by steaming and defibrating the wood chips used in Example 1 was wet-made in the same manner as in Example 1 without being steamed with an alkaline aqueous solution as in Example 1, and then dried. Thus, a wood fiber board having a thickness of 12 mm and a density of 0.07 g / cm ³ was obtained.

The obtained wood fiberboard was carbonized in the same manner as in Example 1 to obtain a carbonized board according to Example 3 having a thickness of 10 mm and a density of 0.05 g / cm ³ . The obtained carbonized board was measured for thermal conductivity in the same manner as in Example 1, and the compression rate and its recovery rate were measured by a compression elasticity test. The results are shown in Table 1.

(Comparative Example 1)
The wood fiber board obtained in Example 3 that is not carbonized and has a thickness of 12 mm and a density of 0.07 g / cm ³ is referred to as Comparative Example 1, and the wood fiber board according to Comparative Example 1 is compared with Example 1 Similarly, the thermal conductivity was measured. The results are shown in Table 1.

(Comparative Example 2)
The wood fiber board obtained in Example 2 that has not been carbonized and has a thickness of 25 mm and a density of 0.08 g / cm ³ is referred to as Comparative Example 2, and the wood fiber board according to Comparative Example 2 is Similarly, the thermal conductivity was measured. The results are shown in Table 1.

As is clear from Table 1, in Examples 1 to 3 and Comparative Examples 1 and 2, the thermal conductivity is significantly smaller in Examples 1 to 3 although the densities are almost the same. The heat insulation of the wood fiber board was greatly improved by carbonization.

  Further, in the examples, from the comparison between the examples 1 and 3, the recovery rate is higher in the example 1 although the compression rate is lower in the example 1 than in the example 3. Therefore, if the wood fiber that is usually obtained is steamed with an alkali solution and formed into a wood fiber board, and the wood fiber board is carbonized, the carbonized board has good elasticity. It turns out that you can get.

Claims (3)

The wood fiber obtained by steaming and defibrating the wood material is cooked in an alkaline solution and then molded to form a wood fiber board having a total dry density of 0.05 g / cm ^{3 to} 0.35 g / cm ^3. A carbonized board manufacturing method comprising heating a fiberboard in an inert gas atmosphere to perform carbonization. The cooking in an alkaline solution, temperature 140 ° C. to 190 ° C., the method for manufacturing the board according to claim 1, characterized in that a pressure ^{6kg / cm 2 ~9kg / cm 2} . The carbonization board manufacturing method according to any one of claims 1 and 2 , wherein the carbonization is performed under heating at a maximum temperature of 400C to 800C.