JPH04325202A - Manufacture of hard cement chip board - Google Patents

Abstract

PURPOSE:To provide a manufacture of a hard cement chip board with good various properties such as density and bending strength. CONSTITUTION:A thermosetting component consisting mainly of alumina cement and anhydrous gypsum and/or hemihydrate gypsum, a cement composite containing portland cement, chipped wood pieces and water are blended, and after these mixtures are press-molded into a predetermined form and before the mixtures start hardening reaction, pressure is released for a short period of time or subjected to decompression and then the aforegoing composite is heat-solidified for manufacturing a hard cement chip board. By the pressure releasing or decompressing process, since moisture, air, or the like contained in the mixtures become possible to be removed efficiently from the mixtures, air or the like becomes difficult to stay in the hard cement chip board manufactured herein, as a result, the various properties of density, bending strength, and the like become possible to be improved.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a method for manufacturing hard wood cement boards that are mainly used as building materials for exterior walls, etc., and in particular can improve various properties such as density and bending strength of the hard wood cement boards. This invention relates to a method for manufacturing hard wood cement boards.

0002

[Prior art] This type of hard wood cement board is
It is known to be obtained by mixing shredded wood, cement, and water, press-molding the mixture into a predetermined shape, and curing the mixture.

However, depending on the type of wood used in this hard wood cement board, components eluted from the wood may inhibit the hardening of the cement, which limits the types of wood that can be used and also prevents the hardening of the wood. The disadvantage was that it took a long time to complete, resulting in poor productivity.

[0004] Therefore, as a method for manufacturing hard wood cement boards that eliminates these drawbacks, the Japanese Patent Publication No. 59-18339
In the publication, a cement composition containing Portland cement and a thermosetting component mainly composed of alumina cement and anhydrite or (and) hemihydrate is mixed with shredded wood chips and water. A manufacturing method is described in which a hard wood cement board is obtained by pressure-molding a mixture of the following into a predetermined shape and heating and curing it under pressure conditions. That is, in this manufacturing method, by applying the above-mentioned cement composition, which has the property of increasing its hardening speed when heated above a certain temperature, the hardening of the cement composition is achieved before the curing-inhibiting components of the wood are substantially eluted. This method expands the types of wood that can be used, improves productivity, and reduces manufacturing costs.

[0005]

[Problems to be Solved by the Invention] By the way, when manufacturing hard wood cement boards using the conventional method, as shown in the graph of FIG. As shown in the graph of Figure 3, when the thickness of the mixture reaches a predetermined value by pressure molding, the pressure is gradually lowered and the thickness is maintained constant, and the mixture is heated and hardened to form a hard wood cement board. A method is used to find the

However, when a hard wood cement board is manufactured by such a method, there are many voids because a large amount of bulky wood chips are mixed in the composition, and the hard wood cement board produced is There was a problem in that air was included in the material, resulting in poor properties such as density and bending strength.

[0007] Although it is possible to improve the properties slightly by setting the pressure during heat curing to a higher pressure, there are certain limitations, and there are problems such as the need for a new expensive pressurizing device that can generate high pressure. There was a point.

The present invention was made in view of the above-mentioned problems, and its object is to create a hard material that does not require an expensive pressurizing device and has excellent properties such as density and bending strength. An object of the present invention is to provide a method for easily manufacturing wood chip cement boards.

[0009]

[Means for Solving the Problems] That is, the present invention provides a cement composition comprising Portland cement and a thermosetting component mainly composed of alumina cement and anhydrite or (and) hemihydrate, and The method is based on the method of manufacturing a hard wood cement board by mixing wood chips and water, pressure molding the mixture into a predetermined shape, and heating and curing it under pressure conditions, and after pressure molding the above mixture. It is characterized by a brief release or vacuum of pressure before the mixture begins the curing reaction.

[0010] When releasing or reducing the pressure on the mixture in such technical means, it is desirable to heat the mixture within a temperature range in which the mixture does not undergo a curing reaction. This is because heating can remove moisture and the like contained in the mixture with higher efficiency.

[0011] Here, as the Portland cement constituting a part of the above cement composition, ordinary Portland cement, early strength Portland cement, ultra early strength Portland cement, white Portland cement, etc. can be used as in the past.

[0012] Furthermore, any wood material can be used to form the wood piece. Incidentally, waste materials such as end chips and scraps generated during the manufacture of hard wood cement boards may be used together with the above-mentioned wood material.

Furthermore, slaked lime, lime, etc., which are thermosetting components, may be added to the cement composition, and waterproofing agents,
Water repellents, foaming agents, wood chip corrosion inhibitors, combustion inhibitors, etc. may be added, and materials such as various aggregates and fibers may be mixed with the wood chips for the purpose of reinforcement and weight increase. good.

[0014]

[Operation] According to such technical means, after the mixture of cement composition, shredded wood chips and water is molded under pressure, the pressure is released for a short time before this mixture starts the hardening reaction. Since the pressure is reduced, moisture and air contained in the mixture can be efficiently removed from the mixture.

[0015]

[Examples] Examples of the present invention will be described in detail below.

[0016] First, wood chips are made into flakes with a thickness of 0.5 mm to 1.0 mm, a length of 20 mm or less, and a width of 10 mm.
Create flakes of less than mm in size and mix them with the cement composition shown below and water: cement composition: flakes: water = 1
They were mixed in a ratio of 0:3:4.5.

(Cement composition) Early strength Portland cement: 50 parts by weight Alumina cement: 15 parts by weight Half water Gypsum: 9 parts by weight Slaked lime
: 6 parts by weight Sodium citrate : 0.72 parts by weight Next, this mixture was filled into a metal mold, and a heating plate with a width of 1300 mm and a length of 3000 mm heated to 80°C was placed on top of the mold for 1000 m
The sample was pressurized under the conditions of 100,000 ton, and heated and pressurized in this state for 3 minutes, then the pressure was released and the sample was left for 30 seconds.

[0018] This depressurization treatment removed a large amount of moisture contained in the mixture, making it possible to fill the above-mentioned mold with the mixture at a higher density.

[0019] Then, again at 80°C and 1000 tons
The mixture was heated and pressed for 10 minutes under the following conditions, and then dried to obtain a hard wood cement board. Note that FIG. 1 is a graph diagram showing changes in the set pressure over time during the manufacturing process.

[0020] The density and bending strength (according to JISA1408 bending test method for architectural boards) of the obtained hard wood cement board were measured, and the density was 1.18, and the bending strength was 109 kg.
/cm2.

[Comparative Example] A hard wood cement board was manufactured under substantially the same conditions as in the example except that the same mixture as in the example was applied and the pressure was not released for 30 seconds.

[0022] When the density and bending strength of the obtained hard wood cement board were measured, the density was 1.0.
7. The bending strength was 87 kg/cm2, which was inferior in characteristics to the hard wood cement board according to the example.

[0023]

According to the present invention, after pressure molding a mixture of a cement composition, shredded wood chips and water, and before this mixture starts a hardening reaction, the pressure is released for a short period of time. Since the pressure is reduced, moisture and air contained in the mixture can be efficiently removed from the mixture.

[0024] Therefore, since it becomes difficult for air etc. to remain in the manufactured hard wood cement board, it has the effect of improving various properties such as density and bending strength of the hard wood cement board with a simple operation. There is.

[Brief explanation of drawings]

FIG. 1 is a graph diagram showing the relationship between manufacturing time and set pressure during that time in an example.

FIG. 2 is a graph diagram showing the relationship between manufacturing time and set pressure during that time in a conventional example.

FIG. 3 is a graph diagram showing the relationship between manufacturing time and set pressure during that time in a conventional example.

Claims (1)

[Claims] Claim 1: A cement composition containing Portland cement and a thermosetting component mainly composed of alumina cement and anhydrite or (and) hemihydrate is mixed with shredded wood chips and water; In the method of manufacturing a hard wood cement board by pressure molding a mixture of the above into a predetermined shape and heating and curing it under pressure conditions, after the mixture is pressure molded and before this mixture starts a curing reaction, A method for manufacturing hard wood cement board, characterized by releasing or reducing pressure for a short time.