KR900007079B1 - Method of producing gypsum-foambody - Google Patents

Abstract

The waterproof gypsum-foam body is manufactured by mixing burnt gypsum with 0.5-10 wt.% waterproofing agent and 0.5-10 wt.% calcium hydroxide to the dry powdered gypsum, mixing the mixt. with the foam made of water and foaming-agent, pouring it in a mould, drying at room temp., and demoulding. The foaming agent is polyvinyl alcohol, surfactant or their admixture and the waterproofing agent is the dry mixture powder of aqueous silicon resin and burnt gypsum.

Description

Manufacturing method of water resistant gypsum foam

The present invention relates to a method for producing a low density water resistant gypsum foam obtained by directly mixing powder and bubbles. More specifically, the water-resistant gypsum foam obtained by mixing and casting a powder of calcined gypsum, water repellent, laxative and slaked lime into a bubble of polyvinyl alcohol, a surfactant, or a mixture thereof added with a coagulant is added. It relates to a manufacturing method.

Building insulation is usually divided into inorganic and organic. Currently commercially available inorganic fibrous insulations include expanded polystyrene, urethane foam, urea foam and expanded polyethylene foam.

Important physical properties of building insulation materials include conductivity, combustibility, hazards, heat resistance, workability, and the like, and organic and inorganic insulating materials have advantages and disadvantages for their respective properties. The most important physical property of insulation is that the thermal insulation of organic insulation is superior to that of inorganic. Inorganic insulation, on the other hand, is mainly burned by glass wool, rock wool, etc., and there is little smoke in the fire, but organic insulation is self-extinguishing due to the addition of insulation.

In addition, the inorganic insulating material is a fibrous material, which may cause irritation when it comes into contact with the skin during construction, and when it comes in contact with water, there is a disadvantage of absorbing water by capillary action to lower the thermal insulation performance.

Existing insulation materials have such advantages and disadvantages and should be selected and used in consideration of characteristics such as temperature and place of use. In general, the heat insulating material has a porosity when the weight is reduced to contain air therein.

In addition, the thermal conductivity of the air itself is very low, such as 0.02 Kcal / mh ° C., so that the higher the air content, the better the thermal insulation performance. Therefore, the smaller the density, the smaller the thermal conductivity, so that the thermal insulation performance is improved. In addition, one of the factors affecting the thermal conductivity is moisture. The thermal conductivity of water is 0.5 Kcal / mh ° C., which is very high, and when the heat insulator contains a lot of water, it is replaced with air in the heat insulator, thereby degrading heat insulation performance.

Therefore, the absorbency and moisture permeability of the heat insulating material cause the heat conductivity to increase by containing moisture in the heat insulating material and the surface. Generally, the absorbency and the moisture permeability are higher than those of the inorganic insulating material. Therefore, it is necessary to administer water resistance to the insulation.

Gypsum is widely used as a building interior material because of its excellent insulation, non-combustibility and sound absorption, but it has a high density and lack of heat insulation effect and absorbency because it is weak in contact with water. The place of use has been restricted. Therefore, if a low density gypsum foam is produced and water resistance is given, it can be an excellent heat insulator that can supplement the disadvantages of the existing organic and inorganic heat insulator as an inorganic heat insulator.

Conventionally, the following is a method of weight reduction in order to increase the thermal insulation effect of gypsum.

(1) A method of adding a chemical in the production of gypsum slurry to produce bubbles by the reaction.

(2) A method for producing a gypsum foam by adding a foaming agent such as a surfactant to the gypsum slurry to cause air to be mixed by stirring.

(3) A method of producing a foam by mixing a bubble and a gypsum slurry by first preparing a bubble by using a foaming agent.

However, such a method has never been commercialized as a heat insulating material by lightening only gypsum, and an example of lightening gypsum as a filler mainly based on inorganic fibers such as glass surfaces is shown in the US patent. However, it was not possible to develop a water-resistant gypsum foam using gypsum, the present invention was successful in solving this problem. This will be described below.

In the present invention, a method is adopted by mixing bubbles and gypsum powder, and the foaming solution is used by dissolving a surfactant, polyvinyl alcohol or a mixture thereof and a curing agent in water.

The gypsum foam was prepared by preparing a bubble through a suitable device and then curing the mixture by introducing a gypsum powder mixed with an additive.

In the method used in the present invention, it is difficult to prevent foam breakage and uniform mixing when gypsum powder and bubbles are mixed, and it is not easy to determine the addition amount of gypsum powder according to the bubble amount, but it is uniform depending on the performance of the powder adder and the mixer. Gypsum foam can also be obtained. However, the foaming agent solution used should have a high foaming force so that bubbles are not destroyed when mixing the foam and gypsum powder, and the foam should be finely and uniformly distributed in the gypsum.

When manufacturing the gypsum foam according to the present invention, it is to mix the gypsum powder and air bubbles, so that an appropriate amount of a slow release agent must be added so as not to be cured during the work, and to have a uniform physical property after curing is completed before the bubble is destroyed after molding. Hardener should be added for the purpose. Sulfates are generally used as a coagulant accelerator.

As a coagulation promoter, it is preferable to neutralize aluminum sulfate, potassium alum, sulfuric acid, and sulfuric acid with triethanolamine, and to neutralize sulfuric acid with monoethanolamine. In addition, animal protein hydrolyzate was used as a slowing agent to obtain the time required for the work, and the water-resistant agent used to give the water resistance effect was mixed with a water-soluble silicone resin and hydrated lime and dried powder. At this time, it is preferable to add slaked lime to improve the water resistance, but since it affects the hardening of the gypsum, when a certain amount or more is used, the physical properties deteriorate.

Gypsum raw material uses gypsum obtained by indirect firing of gypsum from phosphate plant with totarikiln. To the gypsum plaster is added 0.1-0.5% of the gypsum usage, and 1-5% of the water-resistant agent is added to the gypsum to thoroughly mix and prepare gypsum powder. On the other hand, when a solution in which a foaming agent and a curing agent are dissolved is sprayed together with air through a bubble generator, uniform bubbles having a density of 0.08-0.l2g / cm ³ are generated.

The resulting bubbles and gypsum powder are thoroughly stirred and poured into a wooden frame to be molded and left for 1 week at room temperature, followed by drying to obtain a low density or water resistant gypsum foam.

The surface generator required for the experiment consists of a liquid pump that carries the foam solution at a constant speed, and a foam generator that mixes and foams the foam solution and air. In addition, a screw stirrer and a pin stirrer were used to mix the gypsum powder and the bubbles.

Important in this experiment is the bubble density and stability. The density of bubbles is determined by the conditions for preparing the bubbles such as the concentration and composition of the foaming agent and the condensation accelerator of the foaming agent solution, the flow rate of the foaming agent solution, and the pressure of the solution and air. In addition, bubble stability changes with the kind of foaming agent used.

As the foaming agent used in the present invention, a surfactant and polyvinyl alcohol were used alone or in combination thereof. As the surfactant, nonionic polyoxyethylene, alkylphenyl ether, or cationic polyoxyethylene alkyl ether sulfonate was used, and polyvinyl alcohol was used for each type having different hydrolysis degree and molecular weight.

In addition, in order to express the water resistance to the gypsum body, which is a characteristic of the present invention, a water-soluble silicone resin and slaked lime are mixed as a water-resistant agent, and dry powder is used in a weight ratio of 1 to 5% by weight, and calcium hydroxide is added to the gypsum to improve water resistance. 0-10% by weight to weight ratio was added.

The mechanism by which the water-soluble silicone resin reacts with the calcium hydroxide to express water resistance cannot be elucidated clearly. Even if the manufactured product is used, the effect is similar.

In particular, the present invention can change the density and strength of the gypsum foam by adjusting the concentration and the amount of foaming agent, it can be seen that the strength and lowering the density while reducing the amount of foaming agent compared to other existing foaming methods.

An embodiment of the present invention will be described in detail as follows. However, the present invention is not limited to the examples.

Example 1

Gypsum powder is prepared by mixing 250 g of gypsum and 0.25 g of a slow release agent (animal protein hydrolyzate). The foaming solution is made by dissolving 3 g of polyvinyl alcohol and 6 g of a coagulant accelerator (aluminum sulfate) in 49 lg of water. This foaming agent solution is taken through a bubble generator to 280 g of bubbles having a density of 0 09 g / cm ³ in a mixer, and the plaster powder is added and stirred for about 3 minutes. After stirring, the gypsum bubble slurry was cast on a wooden frame, and left to dry for 1 week. The results are shown in Table 1.

Example 2

In Example 1, 5 g of polyvinyl alcohol and 5 g of a coagulant accelerator were dissolved in 490 g of water to obtain a bubble having a density of 0.10 g / cm ³ , and then the same procedure as in Example 1 was carried out. The results are shown in Table 1.

Example 3

In Example 1, when preparing a foaming agent solution, 10g of polyvinyl alcohol and 5g of a coagulant accelerator were dissolved in 485g of water to obtain a bubble having a density of 0.08g / cm ³ , and the others were carried out in the same manner as in Example 1. The results are shown in Table 1.

Example 4

In preparing the foaming solution in Example 1, 7.5 g of polyvinyl alcohol and 2 g of a coagulant accelerator (sulfuric acid) were dissolved in 490.5 g of water to obtain a bubble having a density of 0.08 g / cm ³ , and the others were the same as in Example 1. Conduct. The results are shown in Table 1.

Example 5

In preparing the foaming solution in Example 1, 5 g of polyvinyl alcohol and 7.5 g of a coagulant accelerator (aluminum sulfate) were dissolved in 487.5 g of water to obtain a bubble having a density of 0.1 lg / cm ³ . It was carried out. The results are shown in Table 1.

TABLE 1 Experimental Results of Gypsum Foams by the Dry Method

Table 1 shows some of the results obtained by directly mixing gypsum powder and bubbles to obtain a low density gypsum foam. The important thing is that the conductivity of physical properties is less than 0.05 kca1 / mh ℃ can replace the existing organic and inorganic insulation. However, the water resistance is not imparted to this product, so that there is an improvement in absorbency, hygroscopicity, and the like.

Example 6

Gypsum powder is made by thoroughly mixing 250 g of hydrated gypsum, 0.75 g of laxative (animal protein hydrolyzate), 1 g of hydrated lime, and 3.5 g of water-resistant agent (made by drying a powder of water-soluble silicone resin and hydrated lime). In addition, 2 g of polyvinyl alcohol and 3.5 g of a coagulation accelerator (aluminum sulfate) are dissolved in 195 g to form a foaming agent solution. The foaming solution is taken from a foaming device by taking 192.5 g of bubbles having a density of 0.10 g / cm ³ , and stirring the plaster powder over 2 minutes while stirring. . The results are shown in Table 2.

Example 7

5.25 g of a water-resistant agent is prepared in the production of gypsum powder, and the same as in Example 6. The results are shown in Table 2.

Example 8

In preparing gypsum powder, 7.0 g of a water-resistant agent was used, and the same as in Example 6. The results are shown in Table 2.

Example 9

8.75 g of a water-resistant agent is used in the manufacture of gypsum powder, and the same as in Example 6. The results are shown in Table 2.

Example 10

In the manufacture of gypsum powder, 3.5 g of a water-resistant agent and 0.25 g of a laxative agent were used, and the same procedure as in Example 6 was performed without using slaked lime. The results are shown in Table 2.

Example 11

When preparing gypsum powder, 2.5 g of calcined lime and 0.25 g of a laxative agent are taken, and others are carried out in the same manner as in Example 6. The results are shown in Table 2.

Example 12

When preparing gypsum powder, 5 g of calcined lime and 0.25 g of a laxative agent are taken, and others are carried out in the same manner as in Example 6. The results are shown in Table 2.

TABLE 2 Experimental Results of Water-Resistant Gypsum Foam by the Dry Method

Absorption rate, however, is calculated from the volume of water absorbed after the specimen has been in water for 24 hours.

According to the above experimental results, when the amount of calcium hydroxide added is 0.4%, the amount of water resistant agent is required to be 2.1% or more, and when the amount of water resistant agent is added to 1.4%, the amount of calcium hydroxide must be 1% or more to satisfy the water resistance effect. Experimental results according to the amount of water-resistant and calcium hydroxide show that the effect on the use of potassium hydroxide is greater than the effect on the water-based agent.

Claims (4)

A method for producing a water-resistant gypsum foam by mixing bubbles with a mixture of calcined gypsum, a water repellent, and calcium hydroxide. Polyvinyl alcohol, surfactant, or a mixture thereof is used as a foaming agent, The manufacturing method of the water-resistant gypsum foam of Claim 1 characterized by the above-mentioned. A water-resistant gypsum foam according to claim 1, wherein the water-soluble silicone resin and hydrated lime are mixed and dried to add 0.5-10% by weight to gypsum in powder form. The method for producing a water-resistant gypsum foam according to claim 1, wherein as the metal hydroxide salt, calcium hydroxide is added in a weight ratio to gypsum 0.5-10%.