JPH0948022A - Manufacture of cured magnesia cement - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable to manufacture cured magnesia having high uniformity of composition which has heretofore been impossible by a conventional method and excellent dimensional stability in a short curing time. SOLUTION: Slurry or paste-like magnesia cement is agitated while varying its temperature in the kneading step, and the temperature is set to about 15 to 50 deg.C at the initial time of the reaction and to about -10 to 30 deg.C at the finishing period of the reaction.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a hardened magnesia cement. More specifically, the present invention relates to a method for producing a hardened magnesia cement that can improve the production efficiency of a hardened magnesia cement useful as a building material and expand the range of use of magnesia cement.

[0002]

2. Description of the Related Art With regard to magnesia cement, a hardened body can be obtained simply by pouring a slurry or paste obtained by mixing a magnesia raw material and an aqueous solution containing magnesium chloride, magnesium sulfate or the like into a mold. Are known. In addition, the cured product is dense and has high strength, and its surface is a mirror surface. Also, it has excellent adhesiveness to wood and the like, and it does not easily ignite due to friction. Further, when it is used on the floor surface, it is easy to obtain a self level.

A hardened body of magnesia cement having such characteristics has hitherto been mixed with a composition according to the purpose in advance so that the raw materials become uniform at the construction site, and the resulting slurry is mixed onto the floor surface as quickly as possible. It is formed by pouring into a mold made in and curing for more than one day. However, although the magnesia cement has many excellent characteristics as compared with other cements, in the conventional method for producing a hardened magnesia product, the heat generated during the hardening process is large and the time required for hardening is long. Further, there is a problem that the expansion is large during the curing process.

When the temperature rises due to heat generation during the curing process, the reaction is accelerated, but this heat generation is 2-3 cm.
Although it does not pose a problem when making a floor with a thickness of 2, the temperature is too high when making a thick product such as a building material, and a large amount of water vapor is generated, which may cause an explosion. Such a phenomenon has been a major obstacle in producing a cured product containing magnesia cement and having excellent heat insulating properties.

Further, the long time required for curing causes the magnesia component to settle out during the curing process, and the composition differs between the upper and lower sides of the cured body, resulting in impaired product uniformity. Further, the large expansion of the cured product in the course of curing is a big problem in manufacturing a product.
However, there is also a report that if the composition is properly controlled, the dimensional stability is superior to other cements. However, the production was still difficult.

In any case, due to the above-mentioned problems, although the magnesia cement has excellent characteristics, its hardened material cannot be widely used as a building material or the like. Therefore, the present invention has been made in view of the above circumstances, it is possible to obtain a magnesia cement hardened product having a uniform composition and excellent dimensional stability without the risk of explosion due to temperature rise. The purpose is to provide a new manufacturing method.

[0007]

In order to solve the above problems, the present invention comprises a step of stirring a magnesia cement component in the form of a slurry or paste while varying the temperature, and a hardened magnesia cement product. To provide a manufacturing method of. The present invention also provides a method for producing a hardened magnesia cement characterized by adding foamed resin particles and hardening them after the stirring step.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, as described above, the temperature is changed when the magnesia cement components are mixed by stirring. That is, stirring is performed while changing the temperature, and while confirming the physical properties such as viscosity, all the components of the magnesia cement cured body including the components such as the filler are sequentially added to prepare a cured body. Therefore, unlike the conventional method, the composition of magnesia cement is not kneaded at once in a short time.

The temperature during stirring can be arbitrarily set in the range of -20 to 110 ° C as required. For example, the temperature can be set high in order to accelerate the reaction in the initial stage of stirring and shorten the reaction time, and can be set low in order to secure the working time during pouring. Specifically, the control temperature during stirring is usually 1 at the initial stage of the reaction in which the viscosity decreases in consideration of workability and the influence of magnesia activity.
5 to 50 ° C, -10 to 30 at the end of the reaction where the viscosity increases
The temperature is set to about ℃, but 20 to 40 at the beginning of the reaction.
It is particularly preferable to set the temperature at 0 ° C and at the end of the reaction at 0 to 25 ° C.

That is, in the present invention, it is essential to control the temperature at the time of stirring based on the knowledge that the stirring of the magnesia cement component accompanying the manufacturing of the cured body greatly affects the characteristics of the cured body and the gain of the manufacturing process. It has a feature. In fact, for example, in the present invention, when the magnesia cement component is continuously stirred at 25 ° C., the viscosity tends to decrease somewhat until about 30 minutes while continuing the heat generation. After about 30 minutes, the viscosity gradually starts to rise, and after about 90 minutes, the viscosity rises rapidly. At this point, it is possible to make a cured product by making final adjustments such as adding fillers and performing casting and casting.

Agitation may be slow enough to prevent sedimentation of the formulation. This slow stirring can not only improve the non-uniformity that has occurred during the reaction in the conventional method, but can stir until the slurry concentration rises, so a composition with a low slurry concentration that could not be prepared by the conventional method, for example, It is possible to create a cured product with a very high water content.

Further, it is possible to control the curing process by controlling the temperature in the curing process after pouring or casting. Specifically, in the case of a composition that generates heat, by setting the pouring and casting temperatures according to the purpose, it is possible to shorten the curing time by utilizing the temperature generated by heat generation. Regarding the production of a cured product by stirring the magnesia cement component which is the subject of the present invention,
Along with a slurry or paste obtained by mixing an aqueous solution containing magnesia cement and magnesium chloride or magnesium sulfate or the like similar to conventional ones, for example, fly ash, rock wool, glass fiber, natural or synthetic organic fiber, or ceramic particles or synthetic The use of fillers such as resin particles and expanded synthetic resin particles, and various components such as a cellulosic viscosity modifier, a flame retardant, a colorant, and a release agent is considered. The compounding ratio thereof can be appropriately selected depending on the purpose and application.

In particular, according to the present invention, after the stirring step is completed, the resin particles for foaming, for example, particles of encapsulated polythylene, etc. are added, and if necessary, a vinyl acetate adhesive or the like is added to cure the resin particles, thereby reducing the weight. However, a cured product excellent in strength, heat resistance and durability can be provided. Hereinafter, the method for producing the hardened magnesia cement of the present invention will be described in more detail with reference to examples.

[0014]

[Example] Commercial active magnesia 1.61K obtained by sintering Australian magnesite as a raw material for compounding
g, magnesium chloride hexahydrate 1.94 kg, water 2.8
8 kg, 75 g of a commercially available vinyl acetate adhesive, and 360 g of a commercially available expanded polystyrene particle having a particle diameter of 2 to 3 mm were prepared.

First, 1.12 kg of water is added to magnesium chloride.
Was added to prepare a magnesium chloride solution. To this solution (2.06 Kg) was added active magnesia (1.61 Kg), and the mixture was reacted with stirring while maintaining the temperature at 40 ° C. The viscosity was 17 cps at the start of the reaction, but 14 cps after 15 minutes
Fell to. After that, the viscosity started to rise, so the temperature was 1
Stirred at 0 ° C. It reached 90 cps after 1 hour and 5 minutes. At this point, 1 kg of magnesium chloride solution was added to the vinyl acetate adhesive and the mixture was bubbled, and the mixture was cooled with stirring. Water 1.76 after 1 hour and 30 minutes from the start of the reaction
Kg was added and cooling and stirring were continued. Reaction start about 2
After a lapse of time, when the viscosity exceeded 200 cps at a temperature of 5.7 ° C., the expanded polystyrene particles were mixed, and an opening 281 mm ×
It was poured into a 346 mm polystyrene square mold and allowed to stand. When a thermometer was inserted in the center of the opening and the internal temperature was observed, the temperature reached 76 ° C. 4 hours and 10 minutes after standing and the resin was hardened. . It was recognized that this molded product had excellent properties as a flooring material for houses.

[0016]

As described in detail above, according to the present invention, a magnesia cured product having high composition uniformity and excellent dimensional stability, which has been impossible by conventional methods, can be produced in a short curing time. It has become possible. There is no risk of explosion due to heat generated during the manufacturing process.

Further, according to the present invention, it becomes possible to improve the production efficiency of the hardened magnesia cement and to expand the range of use of the magnesia cement.

Claims (6)

[Claims] 1. A method for producing a hardened magnesia cement, which comprises a step of stirring a slurry or paste-like magnesia cement component while changing the temperature. 2. The temperature is changed between the step of decreasing the viscosity with stirring and the step of increasing the viscosity.
Manufacturing method. 3. The temperature of the step of decreasing the viscosity is about 15-5.
The manufacturing method according to claim 2, wherein the temperature at 0 ° C and the step of increasing the viscosity is about -10 to 30 ° C. 4. The method according to claim 1, wherein the temperature change is controlled by utilizing the heat generated by stirring. 5. A method for producing a hardened magnesia cement, which comprises adding foamed resin particles and hardening them after completion of the stirring step in any one of claims 1 to 4. 6. The method according to claim 5, wherein the adhesive component is added prior to or simultaneously with the addition of the expanded resin particles.