JPH1112018A - Wood cement composition and production of wood cement board by using the composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wood cement composition giving a wood cement board having improved water-permeation resistance and provide a process for producing a wood cement board by using the cement composition. SOLUTION: This wood cement composition is produced by compounding 100 pts.wt. of a cement component composed of Portland cement, alumina cement and anhydrous gypsum and/or hemihydrate gypsum with 0.2-2.0 pts.wt. of an organic carboxylic acid alkali metal salt, 1-50 pts.wt. of wood chips, 10-55 pts.wt. of water and 0.1-20 pts.wt. (in terms of solid component) of a polymer latex consisting of at least one component selected from ethylene-vinyl acetate copolymer emulsion, styrene-butadiene rubber latex, chloroprene rubber latex, polyolefin emulsion and polyurethane emulsion.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wood cement composition which is a raw material for producing a wood cement board mainly used as an exterior material of a building, and a method for manufacturing a wood cement board using the wood cement composition. .

[0002]

2. Description of the Related Art Conventionally, wood cement boards, which are composite moldings of wood materials and cements, have been used as building materials such as exterior materials and interior materials for buildings.

[0003] In order to increase the productivity of the production of the above wood cement board, a production method using alumina cement and a cement component containing a component consisting of anhydrous gypsum and / or hemihydrate gypsum is disclosed in JP-B-59-18339. And Japanese Patent Application Laid-Open No. 4-325202.

[0004]

However, in the conventional manufacturing method, a flake-like mixture obtained by mixing cement, wood chips, and water is deposited on a mold, compressed, formed into a predetermined shape, and then cooled for a predetermined time. Since it is pressurized, heated, cured and demolded, when the compressive force is low, or when the uneven pattern on the surface of the wood cement board to be obtained is deep, the compressive force of the concave portion is insufficient, and the obtained wood cement There has been a problem that the water resistance of the plate tends to deteriorate.

As a solution to the above problem, a method of thickly applying a paint or a water repellent to the surface of a wood cement board has conventionally been adopted. However, this method requires post-processing such as painting, drying and baking. There are problems such as a longer production process and an increase in cost.

The present invention has been made in view of the above circumstances, and has as its object to provide a wood cement composition which provides a wood cement board having improved water permeability, and a wood material using the cement composition. An object of the present invention is to provide a method for manufacturing a cement board.

[0007]

The inventor of the present invention has conducted various studies on the cause of the deterioration of the water permeability of the wood cement board and its countermeasures. As a result, the water permeability is determined by the amount of fine voids existing inside the wood cement board. The amount of voids depends on the size of the flake-like mixture obtained by mixing cement, wood chips, and water, and the smaller the size of the flake-like mixture, the more difficult it is to form voids. It has been found that the size is related to the amount of water used for the cement.

That is, in a wood cement composition for obtaining a conventional wood cement board, a cement component 1 is usually used.
The amount of water used per 100 parts by weight is at least 45 parts by weight. With this formulation, it is difficult to sufficiently reduce the size of the flake mixture, but the amount of water
When it is 0 parts by weight or less, the size of the flake-like mixture is reduced, and when the flake-like mixture is subjected to pressure molding, the flake-like mixture is more effectively united, and the obtained wood cement board becomes denser. It was found that voids were hardly formed, and the invention of claim 1 of the present invention (hereinafter, referred to as present invention 1) was completed.

However, when the amount of water with respect to the cement component is reduced, the familiarity between the used wood chip and the cement is reduced, and the wood chip tends to be exposed on the surface of the wood cement board, so that the desired surface quality (surface smoothness) is obtained. , Surface coating quality, etc.), the surface quality needs to be improved.
The present inventor has also studied this problem and found that it can be solved by adding and mixing 0.1 to 20 parts by weight of a polymer latex with respect to 100 parts by weight of a cement component of a wood cement composition. The invention described in claim 2 (hereinafter referred to as “invention 2”) has been completed. In the case of the present invention 2, it was also found that the surface smoothing effect was exhibited even if the amount of water was increased to 55 parts by weight with respect to 100 parts by weight of the cement component.

When a polymer latex is added to and mixed with the above composition, the polymer latex is adsorbed on the surface of the wood chip, and then the cement component is adsorbed on the polymer latex to leave the wood chip covered with the cement. Becomes For this reason, even if the amount of water is small, the affinity between the wood chip and the cement is improved, and the bonding between the wood chip and the cement is strengthened when pressed, and the surface quality can be secured without the wood chip exposure of the obtained wood cement board surface. .

In order to exhibit this effect more effectively, first, when preparing the wood cement composition, first, wood chips,
It is also preferred that the present inventors pass through a process in which water, an alkali metal salt of an organic carboxylic acid, and a polymer latex are mixed by stirring to form a blend, and then the cement component is added to the blend and stirred and mixed. The invention described in the heading, Claim 4 (hereinafter referred to as the present invention 4) has been completed.

[0012] As described above, the wood cement composition of the present invention 1 comprises a cement component 10 consisting of portland cement, alumina cement and anhydrous gypsum and / or hemihydrate gypsum.
0 parts by weight of an alkali metal salt of an organic carboxylic acid 0.2 to 0.2 parts by weight
2.0 parts by weight, 1 to 50 parts by weight of wood pieces and 10 to 40 parts by weight of water are added and mixed.

The wood cement composition of the present invention 2 comprises 100 parts by weight of a cement component composed of portland cement, alumina cement, anhydrite and / or hemihydrate gypsum,
0.2 to 2.0 parts by weight of an alkali metal salt of an organic carboxylic acid, 1 to 50 parts by weight of a piece of wood, 10 to 55 parts by weight of water and 0.1 to 20 parts by weight of a polymer latex in terms of solid content are added and mixed. It is characterized by having.

The wood cement composition according to claim 3 of the present invention (hereinafter referred to as the present invention 3) is characterized in that the polymer latex used in the present invention 2 is ethylene-vinyl acetate copolymer emulsion, styrene-butadiene rubber latex, chloroprene It is characterized by being at least one selected from rubber latex, polyolefin-based emulsion and polyurethane emulsion.

According to the wood cement composition of the present invention 4, the wood cement composition of the present invention 2 or 3 is prepared by first using wood chips,
Water, an alkali metal salt of an organic carboxylic acid, and a polymer latex are stirred and mixed to form a blend, and then the cement component is added to the blend, and the mixture is stirred and mixed.

The method for producing a wood cement board according to the fifth aspect of the present invention (hereinafter referred to as the fifth aspect of the present invention) relates to the present invention.
Any one of the above wood cement compositions is formed into a predetermined shape under pressure, and then heated and cured.

The portland cement in the cement component used in the present invention 1 to 4 includes, for example, ordinary portland cement, early-strength portland cement, ultra-high-strength portland cement, white portland cement and the like.

As the alumina cement, anhydrous gypsum and / or hemihydrate gypsum in the cement components used in the present invention, those used in conventional wood cement compositions are used. Lime may be contained in the cement component.

An alumina cement in a cement component,
The mixing ratio of the combined component of anhydrous gypsum and / or hemihydrate gypsum and Portland cement is 1: 4 to 4: 1 by weight.
Is preferred. If the amount of alumina cement, anhydrous gypsum and / or hemihydrate gypsum in the cement component is out of this range, the effect of accelerating hardening by heating is reduced, and wood cement is produced using this cement component and wood material. When manufacturing a board, the adhesive force of the cement component to the wood material is not improved, and it is difficult to develop the strength of the obtained wood cement board. Conversely, if the content of the combined components of alumina cement, anhydrous gypsum and / or gypsum hemihydrate exceeds the above range, the content of inexpensive Portland cement decreases and the raw material price increases.

In the alkali metal salts of organic carboxylic acids used in the present invention, examples of the organic carboxylic acids include citric acid, gluconic acid, glutaric acid, glycolic acid, malic acid and the like. Among them, citric acid,
Gluconic acid, glutaric acid, glycolic acid are preferred.
As the alkali metal salt, for example, sodium salt,
And potassium salts.

The alkali metal salt of the organic carboxylic acid is
It is used to extend the pot life of the cement mixture obtained by mixing the wood component and water with the cement component.
If the amount is less than 0.2 parts by weight, the effect of extending the pot life will be insufficient, and if it exceeds 2.0 parts by weight, the effect of extending the pot life will not be increased. Is limited to

If the amount of water with respect to 100 parts by weight of the cement component of the wood cement composition of the present invention 1 is less than 10 parts by weight, the cement will be hard to cure, and if it exceeds 40 parts by weight, the effect of improving the water permeability will be lost. It is limited to 10 to 40 parts by weight. Preferably it is 12 to 35 parts by weight.

When the amount of water with respect to 100 parts by weight of the cement component of the wood cement compositions of the present inventions 2 and 3 is less than 10 parts by weight, the cement is hard to cure, and when it exceeds 55 parts by weight, the effect of improving the water permeability is lost. Therefore, it is limited to 10 to 55 parts by weight. Preferably it is 10 to 40 parts by weight.

Since the wood chips used in the present invention contain a small amount of water, they have a function of suppressing the temperature rise of the obtained wood cement board. Therefore, the amount of wood chips per 100 parts by weight of the cement component of the wood cement compositions of the present inventions 1 to 4 is 1
If the amount is less than 10 parts by weight, the fire resistance of the obtained wood cement board is reduced. If the amount is more than 50 parts by weight, the strength of the wood cement board is reduced. As the wood chips, conifers (such as hemlock, spruce, red pine, etc.),
Those obtained from broadleaf trees (beech, merabi, etc.) can be used.

Examples of the polymer latex used in the present invention 2 include vinyl acetate copolymer emulsion, polyolefin emulsion such as polyethylene and vinyl acetate ethylene copolymer, (meth) acrylic acid copolymer emulsion, and styrene butadiene rubber. Latex, acrylonitrile butadiene rubber latex, chloroprene rubber latex, methyl methacrylate butadiene rubber latex, polyurethane emulsion, and the like may be used, and these may be used alone or in combination of two or more.

Among them, at least one selected from ethylene vinyl acetate copolymer emulsion, styrene butadiene rubber latex, chloroprene rubber latex, polyolefin emulsion and polyurethane emulsion is preferable.

To the polymer latex, a rosin-based, terpene-phenol-based, petroleum-based tackifying resin, a plasticizer such as phthalic acid ester or oleic acid, etc. are added to improve the bonding strength between the wood chip and cement. May be. Further, a preservative, an antioxidant and the like are added as required.

When the weight of the polymer latex in terms of solid content is less than 0.1 part by weight based on 100 parts by weight of the cement component of the wood cement composition of the present invention 2, the effect of improving the bonding strength between the wood chips and the cement is not obtained. If the amount exceeds 20 parts by weight, the size of the flakes of the flake-like mixture increases, and the water-permeability of the obtained wood cement board decreases, so that the amount is limited to 0.1 to 20 parts by weight.

As a method for producing the wood cement board of the fifth invention, for example, the wood cement compositions of the first to fourth inventions are
After being deposited on a mold, compressed and formed into a predetermined shape, a method of applying pressure and heating for a predetermined period of time to cure and remove the mold is used.
If necessary, moisture removal may be performed by heating and drying after demolding.

[0030]

The wood cement composition of the present invention comprises a cement component consisting of Portland cement, alumina cement, anhydrite and / or hemihydrate gypsum in 100 parts by weight of an alkali metal salt of an organic carboxylic acid. Parts by weight, 1 to 50 parts by weight of wood chips and 10 to 40 parts by weight of water were added and mixed, so that the size of the flake shape of this composition was small, and the composition was obtained by press molding. The wood cement board has a dense structure and few voids, so that the water resistance is improved.

The wood cement composition of the present invention 2 comprises 100 parts by weight of a cement component composed of portland cement, alumina cement, and anhydrous gypsum and / or hemihydrate gypsum.
0.2 to 2.0 parts by weight of an alkali metal salt of an organic carboxylic acid, 1 to 50 parts by weight of a piece of wood, 10 to 55 parts by weight of water and 0.1 to 20 parts by weight of a polymer latex in terms of solid content are added and mixed. As a result, the affinity between the wood chip and the cement is improved, the bond between the wood chip and the cement is strengthened when pressed, and the wood chip is not exposed on the surface of the obtained wood cement board, so that the surface quality can be secured.

In the wood cement composition of the present invention 3, the polymer latex to be used is at least one selected from ethylene vinyl acetate copolymer emulsion, styrene butadiene rubber latex, chloroprene rubber latex, polyolefin emulsion and polyurethane emulsion. Since it is the wood cement composition of the second aspect of the present invention, the above-mentioned effects are further exhibited.

The wood cement composition of the present invention 4 is the wood cement composition of the present invention 2 or 3, which comprises:
Water, an alkali metal salt of an organic carboxylic acid and a polymer latex are stirred and mixed to form a composition, and then the cement component is prepared through a step of being added to the composition and stirring and mixing. The polymer latex is adsorbed over the surface of the wood chip, and then the cement component is adsorbed to the polymer latex, and the wood chip is covered with cement, the affinity between the wood chip and the cement is improved, and pressure molding is performed. Then, the bond between the wood chips and the cement is strengthened, and the wood chips are not exposed on the surface of the obtained wood cement board, so that the surface quality is good.

The method for producing a wood cement board according to the fifth aspect of the present invention comprises:
Since it is a method in which any of the wood cement compositions of the present invention 1 to 4 is press-formed into a predetermined shape and then cured by heating, a wood cement board excellent in water resistance can be manufactured with high productivity. . In addition, when any of the wood cement compositions of the present inventions 2 to 4 is used, a wood cement board having good surface quality can be manufactured with high productivity.

[0035]

BEST MODE FOR CARRYING OUT THE INVENTION

[Cement component] The cement components used in each of the Examples and Comparative Examples were all the same composition and had the following composition. 62.5 parts by weight of early strength Portland cement, 18.7 parts by weight of alumina cement, 11.3 parts by weight of gypsum hemihydrate, 7.5 parts by weight of slaked lime, 100 parts by weight in total.

[Other Ingredients] In each of the examples and comparative examples, finely divided wood chips were used, and sodium citrate was used as an alkali metal salt of an organic carboxylic acid. Tables 1 and 2 show the amounts of wood chips, sodium citrate, water and polymer latex in each of Examples and Comparative Examples. However, the amount of the polymer latex was shown in parts by weight in terms of solid content.

[Preparation of Wood Cement Composition] In each of Examples and Comparative Examples, preparation was made by the following preparation method A, B or C. The preparation method is shown in Tables 1 and 2. Preparation method A: Of the listed ingredients, wood chips, water and sodium citrate were charged into the mixing tank and stirred and mixed, then the cement component was added and mixed by stirring to obtain a flake-like mixture. Was. Preparation method B: Among the listed ingredients, first, the indicated amounts of wood chips, water, sodium citrate and polymer latex were put into a mixing tank, and the mixture was thoroughly stirred and mixed to form a compound. The indicated amount was added and mixed with stirring to obtain a flaky mixture. Preparation method C: Of the ingredients described, wood chips, water and sodium citrate were charged into a mixing tank and mixed with stirring, then a cement component was added and mixed with stirring, and finally a polymer latex was added. The mixture was added and mixed to obtain a flaky mixture.

[Press molding and heat treatment] The wood cement composition of each of the Examples and Comparative Examples, which were made into the above-mentioned flaky mixture, was deposited on an aluminum mold to which a release agent was applied. It was squeezed from the top and flattened, and a 12-mesh wire net was placed on it, and the pressure was 30 kg / cm ² and the temperature was 96.
Pressurized at 12 ° C for 12 minutes. After demolding, the mixture was heated at 100 ° C. for 1 hour to adjust the water content.

[Evaluation of Water Permeation Resistance] The wood cement boards obtained in the above-described Examples and Comparative Examples were subjected to JISA.
The water permeability was measured based on the 5400 funnel test. As the water permeation amount, the reduced water volume (ml) in the funnel was used as the evaluation value as it was, and the measured values are shown in Tables 1 and 2. [Evaluation of surface quality of wood cement board] Similarly, the amount of wood chips exposed on the surface of each wood cement board of each of Examples and Comparative Examples was visually observed. , And those of defective were determined as x, and are shown in Tables 1 and 2, respectively.

[0040]

[Table 1]

[0041]

[Table 2]

As can be seen from Tables 1 and 2, the wood cement board obtained from the wood cement composition in which the amount of water is smaller than that of the prior art has improved water permeability. In addition, the surface of the wood cement board obtained from a system obtained by further adding a polymer latex to the above composition has little exposure of wood chips, and the surface smoothness is secured. A wood cement board obtained from a composition containing a large amount of a polymer latex has poor water resistance.

[0043]

According to the first aspect of the present invention, the wood cement board obtained by using the first aspect of the present invention has a dense structure, a small amount of voids, and has excellent water permeability. .
Therefore, it is not necessary to apply a paint or a water repellent on the surface of the wood cement board in order to ensure water resistance.

According to the second aspect of the present invention, the wood cement board obtained by using the second aspect of the present invention has improved adaptability between the wood piece and the cement, and has a stronger bond between the wood piece and the cement. It has excellent water permeability and good surface condition.

[0045] Since the present invention 3 is configured as described above, the wood cement board obtained by using the present invention 3 further exerts the above-mentioned effects.

According to the fourth aspect of the present invention, the wood cement board obtained by using the fourth aspect of the present invention has a structure in which the polymer latex is first adsorbed on the surface of the piece of wood, and then the polymer latex is applied to the polymer latex. The cement component is adsorbed, and the wood chips are covered with cement, the affinity between the wood chips and the cement is improved, the bond between the wood chips and the cement is strengthened, and the surface condition is further improved while having excellent water resistance. It will be good.

Since the fifth aspect of the present invention has the above-described structure, according to the production method of the fifth aspect, a wood cement board excellent in water resistance can be produced with high productivity. In addition, when any of the wood cement compositions of the present inventions 2 to 4 is used, a wood cement board having good surface quality can be manufactured with high productivity.

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Claims (5)

[Claims] 1. 0.2 to 2.0 parts by weight of an alkali metal salt of an organic carboxylic acid and 1 to 50 parts by weight of wood per 100 parts by weight of a cement component composed of portland cement, alumina cement, gypsum anhydrite and / or gypsum hemihydrate Part and water 10
A wood cement composition, wherein about 40 parts by weight are added and mixed. 2. 100 parts by weight of cement component consisting of Portland cement, alumina cement, and anhydrous gypsum and / or hemihydrate gypsum, 0.2 to 2.0 parts by weight of an alkali metal salt of an organic carboxylic acid, 1 to 50 parts by weight of wood Parts, water 10
55 parts by weight and polymer latex are 0.1
A wood cement composition characterized by being added and mixed in an amount of up to 20 parts by weight. 3. The polymer latex is at least one selected from the group consisting of ethylene vinyl acetate copolymer emulsion, styrene butadiene rubber latex, chloroprene rubber latex, polyolefin emulsion and polyurethane emulsion.
The wood cement composition of the above. 4. A wood chip, water, an alkali metal salt of an organic carboxylic acid and a polymer latex are stirred and mixed to form a composition, and then the cement component is added to the composition and the mixture is stirred and mixed. The wood cement composition according to claim 2 or 3, wherein: 5. A method for producing a wood cement board, comprising press-molding the wood cement composition according to claim 1 into a predetermined shape, followed by heating and curing.