JPH0565455B2 - - Google Patents

Description

[Detailed description of the invention]

<Industrial Application Field> The present invention relates to a method for producing a wood cement board by compacting a mixture obtained by kneading wood materials such as wood chips and wool, cement, and water, and then curing and hardening the mixture. More specifically, the present invention relates to a method for manufacturing wood cement boards in which a metal compound is mixed into kneading water so that the cement hardens quickly. <Prior Art and its Problems> A method for producing a wood cement board is well known, in which a mixture obtained by kneading a wood material, cement, and water is pressed and molded, and then cured and hardened to form a board. However, in the manufacture of such wood cement boards, there is a problem that the hardening of the cement is inhibited by components extracted from the wood materials used, and as a result, the strength of the wood cement boards is significantly reduced. There is. To address these problems, conventional methods have been to select tree species to be used as wood materials, that is, to use ones with fewer wood extracts.
At present, it is extremely difficult to stably obtain such high-quality wood materials, and this also causes an increase in price. Methods have also been proposed in which a fast-setting cement, a super-fast-setting cement, a thermosetting cement, or the like, which has a fast hardening speed, is used as the cement. This is based on the idea of allowing cement to harden before the above-mentioned wood extract components inhibit cement hardening, but in this case as well, it is possible to completely suppress the hardening inhibition caused by wood extract components. This will reduce the strength of the wood cement board. Additionally, these types of cement are expensive and less economical. Several attempts have been made to suppress the inhibition of cement hardening by wood extract components. It is presumed that this inhibition of cement hardening due to wood extracted components is due to harmful components extracted from wood materials being eluted into cement slurry water during kneading and inhibiting cement hardening. However, since the specific mechanism has not yet been elucidated, all conventional solutions have been piecemeal and have not provided a fundamental solution. for example,
Chlorides such as calcium chloride and magnesium chloride,
Alternatively, a method of pre-treating the wood with water glass or the like has been proposed, but this method has not always been sufficiently effective. Also known are methods in which wood materials are pretreated with a sulfate such as magnesium sulfate or calcium sulfate and a carboxylic acid, and a method in which wood materials are pretreated with an aluminum salt of a strong acid and an acetate. Although these methods are effective in preventing the elution of extracted components from wood materials, they require a complicated process of pre-treating the wood materials, and in both cases, multiple types of substances are mixed in the pre-treatment. It has disadvantages from a practical and economical point of view, such as the need to use the system as a secondary device. <Means for Solving the Problems> Apart from the technical field to which the present invention pertains, the present inventor has discovered that even in plywood formwork, components eluted from wood inhibit the cement hydration reaction, resulting in poor curing. In view of this, after conducting various studies on this phenomenon, we found that water-soluble extracted components contained in wood, such as cellulose, lignin, tannin, humic acid, and sugars, are absorbed by the water in the cement slurry at the interface with cement. These extracted components combine with Ca ²⁺ , K ⁺ , and Na ⁺ released from cement to form salts.
It has been found that as the cement particles are covered with this salt, the subsequent hydration reaction of the cement is suppressed. In other words, a normally cured dry mortar contains a large amount of K ₂ SO ₄ , Na ₂ SO ₄ , and Ca(OH) ₂ , but in the case of poorly cured mortar, the amount of these components decreases. In mortar with markedly poor curing, these materials were hardly present, and instead, a large amount of ettringite was observed.
This is dissolved into the liquid phase during cement hydration.
Should crystallize as K ₂ SO ₄ , Na ₂ SO ₄ , Ca(OH) ₂
Na ⁺ , K ⁺ , and Ca ²⁺ are adsorbed by the above-mentioned extract components eluted from the wood or chemically bonded to form complex salts, so they cannot crystallize, and at that time, excess SO ₄ ^{2 -} is presumed to have crystallized into ettringite. Based on the above findings, we have repeatedly considered from a chemical standpoint the means to prevent wood extracts from combining with free ions from cement to form complex salts, and have found that wood extracts are more stable than these free ions. By pre-binding a high degree of complex salt with the generated metal ions, the wood extract components can be more stably chelated with the metal ions, and as a result, binding with free ions can be prevented. It has been found that inhibition of cement hardening can be prevented. A patent application was filed on April 18, 1985 (Japanese Patent Application No. 89246/1989) for a plywood coated or impregnated with a metal compound powder or aqueous solution on at least one surface of the veneer. The present invention was created to apply this technical concept to wood cement boards, and after kneading wood materials, cement, and water to form a mixed mat,
When the mixed pine is compacted and further cured to produce a wood cement board, a metal compound that combines with wood extract components to form a highly stable complex is mixed into the kneading water. The purpose is to provide a method for manufacturing wood cement boards. Preferably, the metal compound is added as an aqueous solution to the kneading water, and this is added to the mixture of wood material and cement and kneaded. The metal compound used in the present invention is one that binds to extracted components such as cellulose, lignin, tannin, and sugars in wood materials to form a highly stable complex. The present invention combines wood extract components that are about to be eluted into cement slurry water from wood materials with metal ions of a metal compound in advance, thereby inhibiting the bonding of the wood extract components and cement free ions and the curing of cement based on this. Therefore, the metal compounds used elute metal ions that are soluble in water and have higher stability than free cement ions, and combine with wood extract components to form poorly soluble complex salts. It must be something that causes the generation of In other words, the extracted components trying to be eluted from the wood material come into contact with and combine with the metal compounds mixed in the water in the slurry at the interface with the cement slurry, and are eluted into the water in the slurry, or the subsequent water/alkali. It creates a chemically stable complex salt that does not dissolve in water or the like. In the present invention, one or more metal compounds selected from sulfates, chlorides, hydroxides, etc. of iron, copper, zinc, or lead may be used alone or in combination, or as metal compounds that perform such actions. Mix and use. Wooden materials include wood chips, wood wool, and the like. Portland cement is usually used as the cement. According to the method of the present invention, the adverse effect of inhibiting cement hardening due to components extracted from wood can be sufficiently suppressed, so there is no need to use expensive cement such as ultra-fast hardening or fast hardening cement or thermosetting cement. There is little sex. In addition, in the method of the present invention, since the metal compound is mixed into the cement mixing water, as described above, the metal compound comes into contact with the wood material at the interface thereof to form a complex salt, and the extracted components from the wood material. At the same time, the metal compound can act as a cement hardening accelerator. especially,
Sulfuric acid compounds of metals such as Zn, Pb, and Cu are known as quick-setting agents that promote the hydration reaction of cement. The mixture thus obtained is made into a mixed mat shape using a forming device, then made into a standard size, pressed and molded, and further cured and cured to obtain a wood cement board according to the present invention. <Function> When manufacturing wood cement boards, the metal compound mixed in the mixing water comes into contact with wood materials such as wood chips and wool, and combines with components extracted from the wood material at their interface to form stable complex salts. form. Therefore, these wood extracted components do not combine with free ions from cement, and a wood cement board with excellent strength can be obtained without inhibiting cement hardening. The added metal compound also acts as a cement hardening accelerator. <Test Example> The influence of various metal compounds on the inhibition of cement hardening by wood extract components was tested. A mixture of cement and standard sand at a ratio of 1:2 was mixed with various solutions at a water/cement ratio of 0.65 to prepare various green mortars, and these were placed in iron molds (1 x 1 x 4 cm). and temperature 20
After curing for one day in a constant temperature bath at 80% humidity and 20°C, various mortar test specimens were obtained. The mixed solution is 10×10×1
Various copper compounds, zinc compounds, lead compounds, and aluminum compounds were added to the wood extract obtained after soaking 18 cm of plywood in saturated Ca(OH) ₂ solution for 48 hours.
They were added in proportions of 0.1%, 0.3%, 0.5% and 1.0%. For comparison, mortar specimens prepared by blending solutions to which these metal compounds were not added were also prepared. Table 1 summarizes the results of measuring the compressive strength of these mortar specimens after curing and hardening for a predetermined period of time.

[Table] Regarding the compressive strength in Table 1, × marks indicate no increase in strength compared to mortar prepared using a solution containing no metal compounds, and ○ marks indicate a slight increase in strength. The ◎ marks indicate those in which the strength increased significantly. Moreover, the numerical value shown in the box under the mark ◎ is the amount of metal compound added when the strength development reaches the maximum. From the results shown in Table 1, although the effect is not necessarily constant depending on the type of metal compound or the amount added, it is generally found that mixing these metal compounds can inhibit the cement hardening effect of wood extract components. It is known that it can be suppressed. In particular, copper compounds include copper chloride and copper sulfide, zinc compounds include zinc sulfate, lead compounds include lead chloride and lead sulfate, aluminum compounds include aluminum chloride and aluminum sulfate, and iron compounds include iron chloride. ,
It was found that each had a remarkable inhibitory effect. Furthermore, when we investigated the fine structure of the mortar specimens in which these remarkable inhibitory effects were obtained using a scanning electron microscope, we found that in both cases, gel-like particles were adsorbed and chemical bonding was observed. Polymerized fibrous, granular, or lumpy products were confirmed. This is because metal ions such as Fe, Cu, Zn, Pb, and Al, which have greater stability than the ions Ca ²⁺ , K ⁺ , Na ⁺ , etc. released from cement into the liquid phase, elute from the added metal compounds. It was determined that these metal ions were complex salts produced by combining with wood extract components. <Example> Compound Merapi wood chips: 20% Portland cement: 38% Water: 40% Metal compounds: 2% According to the above formulation, each metal compound is dissolved in water to make an aqueous solution, and the aqueous solution is made into a mixture of wood chips and cement. After addition and mixing, the mixture was molded and cured using a conventional method to obtain a wood cement board. The metal compounds used were copper sulfate, copper nitrate, zinc chloride, aluminum sulfate,
and ferric chloride. Also under similar conditions, the same amount of metal compound (aluminum sulfate)
A wood cement board obtained by impregnating a piece of wood with the same material, and a wood cement board obtained by increasing the amount of water without mixing any metal compounds were used for comparison. After curing the wood cement board according to the present invention and the comparative material thus obtained, the bending strength was measured after one week, two weeks, and four weeks using a conventional method. The results are shown in Table 2.

[Table] From the results shown in Table 2, the comparative materials produced without the addition of metal compounds did not have sufficient bending strength, whereas the materials according to the present invention all showed a remarkable increase in strength. Ta. This is considered to be because, in the case of the present invention, the effect of inhibiting cement hardening due to wood extract components was eliminated by the addition of the metal compound, and sufficient hardening was achieved. Furthermore, even when compared with a comparative material obtained by impregnating a piece of wood with a metal compound, the wood cement board obtained by the method of the present invention had excellent bending strength at all ages. In particular, in the case of the present invention, it was confirmed that the initial strength development was excellent, and the effect of accelerating cement hardening by the added metal compound was obtained. Note that aluminum salts such as aluminum chloride and aluminum sulfate are effective in preventing cement hardening inhibition caused by wood extract components, but
On the other hand, it increases the viscosity of the cement and requires an extremely large stirring force to mix it with the wood material, making it difficult to mix uniformly. If the mixing is uneven, there will be areas where only the wood material hardens without enough cement entering.
The strength of the wood cement board obtained is uneven,
There is a problem that if a large bending load is applied to a part with low strength, it will easily break. For this reason, these aluminum salts are not used as metal compounds in the present invention. <Effects of the Invention> According to the present invention as described above, extracted components such as cellulose, lignin, tannin, and sugars from wood materials such as wood chips and wool used for manufacturing wood cement boards are not mixed into the kneading water. The extracted components are combined with the extracted metal compounds at their interfaces to form a highly stable insoluble complex, which effectively prevents the extracted components from eluting into the moisture of the cement slurry, and prevents cement hardening due to the extracted components of the wood. Does not cause any hindrance. Therefore, a wood cement board with excellent strength can be manufactured. Furthermore, in the method of the present invention, since the metal compound is mixed into the kneading water, the cement hardening promoting action of the metal compound can be utilized at the same time, and in addition to suppressing the cement hardening inhibition described above. It achieves remarkable effects. Since the wood cement board manufactured by the present invention progresses in hardening at an early stage, handling during manufacturing is improved, such as being able to be transported to the next process more quickly. Furthermore, compared to the method of impregnating a piece of wood with a metal compound, this method has the advantage that it is possible to obtain the same effect of inhibiting cement hardening with a smaller amount of metal compound, and is superior in economical efficiency.

Claims (1)

[Claims] 1. After kneading wood materials, cement and water to form a mixed mat, the mixed mat is pressed and molded,
Further, when curing and hardening to produce a wood cement board, a metal compound consisting of one or more substances selected from sulfides, chlorides, or hydroxides of iron, copper, zinc, or lead is mixed into the kneading water. A method for producing a wood cement board, characterized in that the metal compound combines with an extracted component from a wood material to form a highly stable complex, thereby preventing inhibition of cement hardening by the extracted component.