JPS5913476B2 - Manufacturing method for wood cement moldings - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a wood cement molded product used as a building material or the like.

Conventionally, wood cement molded products called wood wool cement boards, wood chip cement boards, etc. have been mainly used as building materials, but these have good fire safety, ease of processing such as cutting and nailing, and durability. It has advantages such as being excellent in
It is a powerful material whose usage is expected to increase in the future.

However, this wood cement molded product has a very serious manufacturing drawback.

The first is the fact that depending on the type of wood, components eluted from the wood may inhibit cement hardening.

This fact has been well known for a long time, and it is said that among the eluted components, organic substances such as sugars mainly inhibit the hardening of cement.

Although leached components can be found to some extent in almost all wood species, it has been found that there are significant differences depending on the wood species within the practical range, especially in terms of the types and amounts of components that have a negative effect on cement hardening. There is.

For example, in general, coniferous trees such as hemlock, rainbow pine, and red pine are suitable, but cedar and larch are not suitable, and broad-leaved trees are suitable, such as redwood and beech, but melabi and the like cannot be used at all.

Furthermore, there are many cases where the same wood can be used as a core material but not as a sapwood, or vice versa, and the reality is that the types of wood that can be used safely are extremely limited.

A second drawback is that the productivity of wood cement molded products is very low.

Commonly used cement takes a long time to harden, and for this reason, in the conventional manufacturing of wood cement moldings, various measures have been taken, such as adding hardening accelerators, but it takes at least one day and night from molding to demolding. I had to leave it alone.

This requires equipment, labor, and a large storage area, leading to high costs.

It is also possible to manufacture wood cement molded products using heat-curing cement, but cement mixtures mixed with wood materials have very poor thermal conductivity, and conventional heat press and steam heat molding methods are not suitable. Due to the difference in thermal expansion caused by the temperature difference between the surface layer and the inside of the molded product, a shift occurs between the surface layer and the inside layer, resulting in a decrease in strength, and the strength also decreases due to the influence of the components eluted from the wood. is unavoidable.

Due to the above two major drawbacks, although wood cement molded products have excellent properties and are basically a combination of inexpensive materials such as cement and wood, they are relatively expensive as products. Moreover, it can be said that this trend is becoming stronger due to the recent economic situation5.

This invention was made in view of the above points, and the gist thereof is to provide heat-curing cement, shredded wood material,
A molding material made by mixing water is interposed between two electrodes,
The method of manufacturing a wood cement molded product is characterized in that the molding material is heated and hardened by passing an electric current between the electrodes.

In this invention, heat-curing cement is defined as calcium sulfoaluminate (calcium sulfoaluminate) that rapidly forms when heated above a certain temperature.
3CaO-A1203・3CaS04・30~32H2
0) refers to a cement composition that has the property of producing needle-like crystals and hardening.

Examples of this heat-curing cement include portland cement (ordinary portland cement, early strength portland cement, ultra early strength portland cement, white portland cement, etc.), alumina cement, anhydrite, or (and) hemihydrate gypsum as the main component. Examples include mixed compositions in which slaked lime is added depending on the situation, and more preferably an alkali metal salt of an organic carboxylic acid or an alkali metal salt of phosphoric acid is added.

The desirable composition range of the above mixed composition includes 50 to 96 parts by weight (80 to 96 parts by weight) of Portland cement;
25-2.0 parts by weight of alumina cement (10-2.0 parts by weight), 15-1.5 parts by weight (5-1.5 parts by weight) of anhydrite or/and hemihydrate, and 10-0 parts by weight of slaked lime. Department (
5 to 0 parts by weight) (more preferred ranges are in parentheses), and 0.2 to 2.0 parts by weight of an alkali metal salt of organic carboxylic acid or an alkali metal salt of phosphoric acid to 100 parts by weight of this mixture. Adding 0.4 to 2.5 parts by weight is preferable because it extends the pot life of the cement paste and further improves the strength of the molded product when heated and hardened.

In this invention, wood chips of various types of wood, wood flour, wood wool, etc. are used as the wood material cut into pieces.

In addition to the mixture of heat-curing cement, wood material, and water, the present invention also uses molding materials such as waterproofing agents, water repellents, foaming agents, corrosion inhibitors for wood materials, and combustion inhibitors. , and mixtures with various aggregates, fibers, and other substances for the purpose of reinforcement and weight increase.

In this invention, a molding material having the composition as described above is placed in a mold whose inner surface is made of an insulating material, and the molding material is placed between two metal endless bands each serving as an electrode, by passing an electric current between two electrodes provided in the mold. During the transfer, the molding material is cured by heating, and the temperature at this time is preferably 60°C to 90°C.

If the temperature is lower than 60°C, the curing speed of the molding material will be slow;
When heated at a higher temperature than C, the molded product obtained tends to have low long-term strength.

Under such conditions, the molding material is generally cured to the extent that it can be removed from the mold within about one hour from the start of heating.

FIG. 1 shows an example of the method of this invention, in which numeral 1 is a mold made of an insulating material, and electrodes 2, 2 are each provided with metal plates on one opposing inner surface.

The molding material A having the above-mentioned composition is put into the mold 1, and the pressure plate 3 is moved by the pressure device 4 to perform pressure molding. Molding material A is heated from the inside to 60° C. to 90° C. by Joule heat generated through electric current.

The molded product A is uniformly heated and hardens rapidly, and the wood cement molded product can be removed from the mold 1 within one hour at the latest.

The wood cement molded product taken out from mold 1 can be cut into thin plates and made into multiple wood cement boards if necessary.

In this embodiment, the mold 1 is made of an insulating material, but the mold 1 may be made of an insulating material only on the inner surface, or the electrode plates 2 and 2 may be made of an insulating material.
Of course, they may be provided vertically and horizontally.

FIG. 2 shows an example in which a plurality of plate-shaped wood cement moldings are manufactured at the same time.

An electrode 2 of one metal plate is provided on the lower surface of the mold 1.

The mixture A1 is put thereon to a predetermined thickness, and then the metal plate 5 is laid down.

This process is then repeated one after another for metal plates 5, 5...
A plurality of molding material layers A, , A+...
... is formed, and the other electrode plate 2 is installed on the uppermost surface.

If necessary, a pressurizing plate 3 connected to a pressurizing device 4 is provided on the upper electrode plate 2 so that the electrode plate 2 can be pressurized.

A current is passed between the electrodes 2, 2, and each molding material layer A1. A...
... is heated and hardened, and then demolded to obtain a plurality of plate-shaped wood cement molded products.

Note that if a relief pattern is applied to the surface of the metal plate, a patterned molded product can be obtained.

As in this example, when the electrode plate and the partitioning metal plate are held horizontally and the molding material layer is formed horizontally, the longitudinal direction of the wood material is arranged horizontally so that it almost coincides with the longitudinal direction, which is preferable in terms of strength. Get results.

FIG. 3 shows an example of continuous production of plate-shaped wood cement moldings.

6 is a rotating endless band, and 3 are placed at intervals above it.
Two endless belts? , 8.9 are provided so as to be rotatable and capable of suppressing the molding material A that is supplied to and transferred to the endless band 6 below.

The running surfaces of the lower endless band 6 and the upper third endless band 9 are made of metal and are also used as electrodes, and the molding material A transferred between them is heated and hardened by the current flowing between both electrodes. Obtain a plate-shaped wood cement molding.

The molding material A supplied to the lower endless belt 6 by the upper first and second endless belts 7 and 8 is sequentially pressurized and molded into a plate shape of a predetermined thickness; It is a device for cutting things.

In the method of this invention, the molding material containing heat-curing cement and shredded wood material is heated by an electric current passed between the electrodes, so it is heated uniformly and efficiently from the inside, and the hardening-inhibiting components of the wood material are substantially heated before they are eluted. Curing progresses over time and a molded product is obtained, and the range of use of the wood material is expanded without restrictions on the species of wood, making it more economical.
A wood cement molded product with excellent strength can be obtained.

Furthermore, according to the heating method, it is not only easy to control the heating conditions, but also improves the problem that heating methods from outside the mold have poor thermal efficiency for molding materials containing wood materials with low thermal conductivity. It is also advantageous in terms of equipment.

Next, an example will be described.

In these examples, parts by weight are simply referred to as parts.

Example 1 100 parts of heat-curing cement consisting of 50 parts of ultra-early strength Portland cement, 25 parts of alumina cement, 15 parts of gypsum hemihydrate, 10 parts of slaked lime, and 1 part of sodium citrate, 40 parts of larch wood chips, and 60 parts of water. This molding material was put into the mold of the apparatus shown in Fig. 1, and the external resistance was adjusted so that a current of 25 A would flow while the molding material was pressed at 23 ky/i, and an AC voltage of 100 μ was applied between both electrodes. added.

After 5 minutes, the current was stopped and the molding material temperature was 77°C), and when the mold was removed after 5 minutes, the specific gravity was 1, ■, and the bending strength was 75k.
g/cmt (immediately after demolding) was obtained.

Example 2 50 parts of water was added to 100 parts of heat-curing cement consisting of 96 parts of ultra-early strength Portland cement, 2.2 parts of alumina cement, 1.5 parts of gypsum hemihydrate, 0.3 parts of slaked lime, and 0.8 parts of sodium citrate. The molding material, which was mixed with 40 parts of cedar chips, was molded using the apparatus shown in FIG.

In other words, a 3.2 mm thick iron plate was used for the partition,
10 layers of molding material were formed, and while compressed with a pressure of 10 kg/i, an AC voltage of 100 μ was applied between both electrodes to 2 OA.
passed the electric current.

After 15 minutes, the power supply was stopped and the molding material temperature was 70°C). When the mold was removed 5 minutes after the power supply was stopped, 10 wood cement boards with a specific gravity of 0.98 and a bending strength of 20 kg/cr7t (immediately after removal from the mold) were formed. Obtained.

Example 3 100 parts of heat-curing cement consisting of 82 parts of ultra-early strength Portland cement, 9 parts of alumina cement, 5.4 parts of gypsum hemihydrate, 3.6 parts of slaked lime, and 0.16 parts of sodium citrate, 50 parts of water, and larch wood. The molding material mixed with 40 parts of chips was molded using the apparatus shown in FIG.

At this time, the endless band was rotated at a speed of 0.5 m/min, the pressing force by the third endless band 9 was 15 kg/i, and the electrode had a pressure of 3 OA.
When a current of 40 μm was applied (ac voltage of 40 μm), the temperature of the molded material was raised to 80° C., and it was possible to cut the molded material after traveling an additional 3 m.

10 is a cutting device.

The molded product thus obtained had a specific gravity of 1.03 and a bending strength of 4.
2 kg/cyit (immediately after amputation).

Comparative Example A molding material prepared by adding 100 parts of ultra early strength Portland cement, 50 parts of water, and 40 parts of cedar chips was formed into 10 layers using the apparatus shown in FIG.
kg/ffl while tightening and without heating with electricity, 20
After leaving the mold in a room at 265% RH for 3 days, the molded wood cement board had a bending strength of 2/i.
Met.

From the above examples, it can be seen that according to the method of the present invention, molded products with excellent strength can be obtained regardless of the species of the wood material.

[Brief explanation of drawings]

1 to 3 are vertical cross-sectional front views of examples of apparatus for carrying out the method of the present invention, respectively. 1...type, 2...electrode, 6,7,8,
9... Endless band, A, A1... Molding material.

Claims (1)

[Claims] 1. A molding material made by mixing heat-curing cement, shredded wood material, and water is interposed between two electrodes, and the molding material is formed by passing an electric current between the electrodes. A method for producing a wood cement molded product, characterized by curing it by heating. 2. A wood cement molded product according to claim 1, characterized in that the molding material is placed in a mold having at least an inner surface made of an insulating material and having electrodes facing each other and hardened by heating. Production method. 3. The method of manufacturing a wooden cement molded article according to claim 1, wherein the molding material is sandwiched between two metal endless bands serving as electrodes and hardened by heating. 4. The method for manufacturing a wooden cement molded article according to claim 2, wherein the molding material placed in the mold is divided into a plurality of layers by interposing metal. 5. Claims 1, 2, and 3, characterized in that the heat-curable cement contains an alkali metal salt of an organic carboxylic acid or an alkali metal salt of phosphoric acid.
4. A method for producing a wood cement molded product according to item 4.