JP3993326B2 - Manufacturing method of wood cement board - Google Patents

Description

【００２３】
一次硬化後における木質セメント板及び得られた木質セメント板製品について試験片（縦４cm×横８cm×厚さ1.2 cm）を切り出し、スパン６cmとして曲げ強度を測定した。結果を表２に示す。
【００２４】
【表２】

【００２５】
表２に示すように、蟻酸カルシウムを使用して製造した実施例１〜３の木質セメント板は、比較例１〜４の木質セメント板と比較して非常に高い曲げ強度を有する。
【００２６】
【発明の効果】
本発明の方法によれば、セメント硬化阻害物質を多量に含む樹種からなる木質補強材を使用した場合であっても、速やかにセメントを硬化させることができるとともに、エトリンガイトの生成を防止することができるため、強度の高い木質セメント板を効率良く製造することができる。また、本発明の方法では、硬化促進剤として蟻酸アルカリ土類金属塩を使用するため、塩化物に起因する錆・腐食、人体に対する悪影響、ダイオキシン等の問題もない。[0001]
[Industrial application fields]
The present invention relates to a method for producing a wood cement board mainly used for buildings.
[0002]
BACKGROUND OF THE INVENTION
The wood cement board is manufactured by a wet method, a dry method, or a semi-dry method using a wood reinforcing material and a cement-based inorganic material as main raw materials. Wood fragments, wood wool, wood pulp, and the like are used as the wood reinforcing material, but recently there is a tendency for wood resources to be insufficient, and saving of wood resources is demanded from the viewpoint of protecting the global environment.
Therefore, in recent years, old materials generated when demolishing wooden buildings to conserve wooden resources, sawdust and scraps generated from the lumbering process, thinned wood from conifers, wooden cement board scrap, etc. The use of wood reinforcements recycled from wood scrap that has been disposed of by incineration is being considered.
[0003]
However, the above wood scrap is composed of a wide variety of tree species. Therefore, the wood scrap is also mixed with a tree species containing a large amount of saccharides and the like which are cement hardening inhibitors, and it is very difficult to remove such tree species from the wood scrap. This is a laborious and difficult task.
Therefore, in order to practically use a wood reinforcing material reclaimed from wood scrap as a raw material for wood cement boards, it is possible to smoothly promote the hardening of the cement even if there is a mixture of tree species that would inhibit the hardening of the cement. You must be able to do it.
[0004]
[Prior art]
Conventionally, in order to eliminate cement hardening inhibition by saccharides contained in wood reinforcement, cement is made by impregnating or mixing metal chlorides such as calcium chloride and magnesium chloride in wood reinforcement as a hardening accelerator. There are provided methods for accelerating the curing of the resin (JP 59-18153, JP 60-118658, etc.).
Saccharides, etc., which are cement hardening inhibitors eluted from the wood reinforcement, cover the periphery of unreacted cement clinker as insoluble matter, but the metal chloride dissolves the insoluble matter, so water from the part where the insoluble matter is dissolved. Once infiltrated, the water and the unreacted cement clinker react to initiate hardening of the cement.
[0005]
[Problems to be solved by the invention]
However, the metal chloride partially dissolves the insoluble matter such as the saccharide, and the hardening of the cement proceeds by the water that has entered from the portion where the insoluble matter is dissolved reacting with the unreacted cement clinker. The curing reaction rate was not large, and therefore it was difficult to say that the above-described metal chloride had a sufficient curing promoting effect. There is also a problem that ettringite is generated during the reaction of the water and the cement clinker, and the strength of the obtained wood cement board is lowered.
Furthermore, the metal chloride has various problems such as rusting of metals such as iron, adverse effects on the human body due to chlorine and chloride, and generation of dioxins during incineration.
Therefore, the subject of this invention is providing the manufacturing method of the wood cement board which can prevent the hardening of a cement rapidly and the production | generation of an ettringite, and does not have the said problem resulting from a chloride.
[0006]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention mixes cement-based inorganic powder with 100 to 50 parts by weight of the cement-based inorganic powder at a mixing ratio of 5 to 50 parts by weight in terms of an absolutely dry state. and a wood reinforcement, hydro to moisture the moisture content in the molding material containing a mixed calcium formate with a mixture ratio of 2 to 3 parts by weight as solid content relative to the cementitious inorganic powder 100 parts by weight A step of forming 15 to 50% by weight, a step of spraying the molding material on the substrate to form the mat, and the mat is heated and pressed together with the substrate at a temperature of 50 to 100 ° C. and a pressing pressure of 2 to 5 MPa. and curing the primary Te, remove the primary cured product obtained from the mold plate, room temperature 2-4 days curing to or 85% RH or more humidity, 150-180 And an autoclave curing step at a temperature of 10 ° C. for 10 to 18 hours .
[0007]
The alkaline earth metal formate is preferably added to the mixture as an aqueous solution, and the amount of the alkaline earth metal formate is 2 to 3 parts by weight with respect to 100 parts by weight of the cementitious inorganic powder. Preferably, the alkaline earth metal formate is calcium formate.
The above-mentioned method for producing a wood cement board is a desirable method especially when the wood reinforcing material contains a tree species containing a large amount of a cement hardening inhibitor.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail.
[Cement-based inorganic powder]
The cement-based inorganic powder used in the present invention is a hydraulic inorganic powder mainly composed of calcium silicate. Examples of such inorganic powder include Portland cement or Portland cement and blast furnace slag. Blast furnace cement mixed with ash, fly ash cement mixed with fly ash, silica cement mixed with silica materials such as volcanic ash and clay, alumina cement, blast furnace slag and the like.
[0009]
[Wood reinforcement]
Examples of the wood reinforcing material used in the present invention include wood flour, wood wool, wood fragments, wood fiber, wood pulp, wood fiber bundle, and the like. The wood reinforcing material includes bamboo fiber, hemp fiber, bacus, rice bran, rice plant. A material mainly composed of lignocellulose such as straw may be mixed. Preferable wood reinforcing materials include a wood piece having a width of 0.5 to 2.0 mm, a length of 1 to 20 mm, an aspect ratio (length / thickness) of 20 to 30, and a branch having a diameter of 0.1 to 2.0 mm and a length of 2 to 35 mm. Or there is a folded and / or bent wood fiber bundle. The wood reinforcing material is usually mixed in an amount of about 5 to 50% by weight with respect to the cement-based inorganic powder in terms of an absolutely dry state.
[0010]
〔aggregate〕
In addition to the cement-based inorganic powder and the wood reinforcing material, an aggregate, particularly a lightweight aggregate may be mixed in the present invention. Examples of the aggregate include quartz sand and quartzite powder, and examples of the lightweight aggregate include pearlite, shirasu balloon, expanded shale, expanded clay, calcined diatomaceous earth, fly ash, and coal galley.
The aggregate is usually mixed in an amount of about 5 to 15% by weight based on the total solid content of the mixture.
[0011]
[Third component]
If desired, the above mixture is further mixed with a hardening accelerator such as aluminum sulfate, magnesium sulfate, aluminates, water glass, or a waterproofing or water repellent such as wax, wax, paraffin, surfactant, or silicon. May be.
[0012]
[Alkaline earth metal formate]
In the present invention, an alkaline earth metal formate is added to the above mixture. As described above, saccharides and the like, which are cement hardening inhibitors eluted from the wood reinforcement, cover the unreacted cement clinker as an insoluble matter, but the alkaline earth metal formate is insoluble in the unreacted cement clinker. Since the product is totally decomposed in a short time, the reaction between the unreacted cement clinker and water, that is, the curing reaction can be rapidly advanced. In addition, since ettringite is not generated during the reaction between the cement clinker and the water, the obtained wood cement board can maintain strength over a long period of time.
[0013]
Furthermore, although the saccharides and the like, which are the cement hardening inhibitor, gradually elute from the wood reinforcing material, the alkaline earth formate metal salt has the ability to decompose insoluble materials such as saccharides. According to the earth metal salt, insoluble substances such as saccharides can be reliably decomposed.
As described above, the alkaline earth metal formate in the present invention exhibits an excellent hardening accelerating action particularly in the production of a wood cement board using a wood reinforcing material containing a resin that elutes a cement hardening inhibiting substance.
[0014]
Among the alkaline earth metal formates, it is desirable to use calcium formate from the viewpoint of availability and the above-mentioned hardening promoting action. The alkaline earth metal formate is preferably used as an aqueous solution from the viewpoint of dispersibility and uniformity in the mixture.
The alkaline earth metal formate is preferably added in an amount of 2 to 3 parts by weight as a solid content with respect to 100 parts by weight of the cementitious inorganic powder.
[0015]
[Manufacture of wood cement board]
In the present invention, a wood cement board is produced by a semi-dry method or a dry method.
In the case of the semi-dry method, first, an alkaline earth metal salt of formate and water were added to and mixed with the cement-based inorganic powder and the wood reinforcing material, and, if necessary, an aggregate and a mixture containing the third component. The mat is formed by spreading the molding material on the substrate.
Water is preferably added so that the water content of the mat is 15 to 50% by weight. The order of adding the alkaline earth metal formate and water is not particularly limited, but it is preferable to add both almost simultaneously. As described above, the alkaline earth metal formate is preferably added as an aqueous solution. Alternatively, the alkaline earth metal formate may be dissolved in the above water for addition, and both may be added together.
[0016]
In the case of the dry method, first, an aqueous solution of alkaline earth metal formate (alkaline earth metal formate + water) is added to a mixture containing the above-mentioned cementitious inorganic powder and wood reinforcing material, and optionally aggregate and third component. ), And the resulting molding material is spread on the substrate to form the mat, and water is further added to the mat. Further, the water to be added is preferably added so that the water content of the mat is 15 to 50% by weight.
[0017]
When the mat is formed as described above, the mat is pressed together with the substrate to be primarily cured under heating. The temperature applied in the primary curing is usually 50 to 100 ° C., and the pressing pressure is usually 2 to 5 MPa.
After the primary curing, the obtained primary cured mat is removed from the mold and then subjected to normal temperature curing or autoclave curing. The normal temperature curing is usually performed at normal temperature for 2 to 4 days, and the autoclave curing is normally performed at a humidity of 85% RH or higher and a temperature of 150 to 180 ° C. for 10 to 18 hours. After normal temperature curing or autoclave curing, a surface treatment is performed through a drying process to obtain a product.
[0018]
When a concavo-convex pattern is provided on the surface of the wood cement board, a concavo-convex pattern corresponding to the concavo-convex pattern may be formed on the mold surface of the substrate. Moreover, when manufacturing a smooth wooden cement board without an uneven | corrugated pattern on the surface, you may use a conveyance board directly as a board | substrate.
[0019]
A wood cement board having a two-layer structure or a three-layer structure can also be produced by the method of the present invention described above. In the case of a two-layer structure, a molding material mixed with a wooden reinforcing material with a small particle size is first sprayed on the substrate, and then a molding material mixed with a wooden reinforcing material with a large particle size is sprayed on the two-layer structure. A mat with a structure is formed, and the mat is pressed and heated to form a surface layer portion of a dense structure with a molding material mixed with the wood reinforcing material having a small particle diameter, and the wood reinforcing material having a large particle diameter is mixed. The back layer portion having a rough structure is formed by a molding material.
[0020]
In the case of a three-layer structure, forming a three-layer mat by spraying a molding material mixed with a finer wooden reinforcing material onto a molding material mixed with a wooden reinforcing material with a larger particle diameter, A layer made of a molding material in which the mat is pressed and heated to mix the above-mentioned wood reinforcing material having a large particle diameter is used as a core layer portion, and a layer made of a molding material in which the wood reinforcing material having a fine particle diameter above and below is mixed. Set the front and back layers. Alternatively, two mats having the above two-layer structure may be laminated and pressed and heated so that layers made of a molding material mixed with a wood reinforcing material having a large particle diameter are in contact with each other.
[0021]
【Example】
[Examples 1 to 3, Comparative Examples 1 to 4]
Water was added to the mixture having the composition shown in Table 1 so that the water content was 17% by weight, and the mixture was stirred and homogenized. The obtained molding material was sprayed onto a conveying plate to form a mat, the mat was pressed together with the conveying plate, and was primarily cured at 50 ° C. for 12 hours. Thereafter, the pressed state was released, and naturally cured for 4 days at room temperature, and finally dried at 80 ° C. for 5 hours to obtain a wood cement board product. Portland cement was used as the cement in Table 1, and cypress sapwood was used as the wood flakes.
[0022]
[Table 1]

[0023]
A test piece (length 4 cm × width 8 cm × thickness 1.2 cm) was cut out from the wood cement board and the obtained wood cement board product after primary curing, and the bending strength was measured with a span of 6 cm. The results are shown in Table 2.
[0024]
[Table 2]

[0025]
As shown in Table 2, the wood cement boards of Examples 1 to 3 manufactured using calcium formate have a very high bending strength as compared with the wood cement boards of Comparative Examples 1 to 4.
[0026]
【The invention's effect】
According to the method of the present invention, it is possible to quickly harden cement and prevent the formation of ettringite even when a wood reinforcing material made of a tree species containing a large amount of a cement hardening inhibitor is used. Therefore, a high-strength wood cement board can be produced efficiently. Further, in the method of the present invention, since the alkaline earth metal formate is used as a curing accelerator, there are no problems such as rust / corrosion due to chlorides, adverse effects on human bodies, dioxins and the like.

Claims (1)

Cement-based inorganic powder , wood reinforcing material mixed at a mixing ratio of 5 to 50 parts by weight in terms of absolute dryness with respect to 100 parts by weight of the cement-based inorganic powder, and the cement-based inorganic powder Adding water to a molding material containing calcium formate mixed at a mixing ratio of 2 to 3 parts by weight as a solid content with respect to 100 parts by weight to a moisture content of 15 to 50% by weight;
A step of forming a mat by spraying the molding material on a substrate,
The mat, and curing the primary and heated pressing temperature 50 to 100 ° C., with the substrate in clamping pressure 2 to 5 MPa,
The resulting primary cured product removed from the mold plate, room temperature 2-4 days curing to or 85% RH or more humidity, 150-180 An autoclave curing step at a temperature of 10 ° C. for 10 to 18 hours ;
A method for producing a wood cement board, comprising: