JPH0223508B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention mainly involves coating the surface of a cement molded product such as a slate tile by applying a cement slurry in which cement and pigment are kneaded together. The present invention relates to a method for manufacturing cement products, and in particular to a method for manufacturing cement molded products that can be reliably colored by applying a thin layer of cement slurry.

[Prior Art and Problems] Conventional methods for coloring the surface of cement products can be broadly classified into two types. There are two methods: one is to paint the surface of a cement product in an uncured state, and the other is to paint the surface after it has hardened. The method of painting hardened cement products uses baking paints such as acrylic resins and acrylic urethane resins as surface paints. This method has the disadvantage that the cement product is dried and cured indoors so that the surface paint can adhere neatly, so curing is time-consuming and the paint is expensive. Furthermore, the cement products produced by this method have the disadvantage that the surface colored layer does not have sufficient weather resistance. In particular, if the curing conditions after painting are poor, the surface paint may deteriorate, change color, or peel off.

In addition, a method has been developed in which cement slurry, which is a mixture of cement, pigment, synthetic resin emulsion, and water, is applied to the surface of a cement molded product immediately after molding to a thickness of several hundred microns.
Publication No. 43437, Publication No. 114886 of 1982).

However, since the cement slurry is applied immediately after molding, this method has the disadvantage that the time required for applying the cement slurry after molding is limited. For this reason, when manufacturing cement products of various shapes, the usage efficiency of cement slurry deteriorates. This is because cement slurry has a short pot life (the time it can be mixed and used). In other words, apart from manufacturing cement molded products of the same standard continuously using a molding machine, when molding tiles at the corners, which are called accessories for slate tiles,
Since the mold is replaced again and again, the application of the cement slurry is interrupted during this time, which has the disadvantage that the cement slurry hardens during this time. Therefore, this method wastes a lot of cement slurry, and its management is extremely difficult.

Therefore, although this method is convenient for mass production of a single product, it has the disadvantage that cement slurries of various shapes cannot be efficiently produced.

Furthermore, the method of applying cement slurry to cement products immediately after forming has the disadvantage that the formed cement products are placed on a receiving iron plate and painted, so the receiving iron plate becomes extremely dirty and it takes time and effort to remove it. Ta.

Furthermore, in this method, since the cement slurry is applied to a cement molded article with a high surface moisture content immediately after molding, it is not possible to increase the moisture content of the cement slurry. For convenient application, high moisture content
A surface paint film of sufficient strength cannot be formed. Furthermore, cement products surface-treated with this method are
Since cement slurry is applied to cement products that contain a large amount of moisture, the moisture contained in the cement products migrates to the surface over time, causing color spots, efflorescence, and other problems such as fading. It was hot.

In order to eliminate this drawback, cement slurry may be applied to the cement molded product after curing. However, even if a cement slurry surface paint is applied to the surface of a cement product after curing, the adhesion of the surface paint is weak, and the hardened surface coloring layer itself is also weak, resulting in a disadvantage in terms of durability.

A technique for applying cement slurry to cement products after curing is disclosed in Japanese Utility Model Application Publication No. 52-68446. In this method, after curing and drying a cement molded product, a mist of water is also sprayed onto the surface to moisten the cement molded product, and a cement slurry is applied to the surface. However, cement molded articles manufactured using this method cannot achieve sufficient strength and durability in the surface colored layer. In particular, this method has the disadvantage that the surface paint of the cement slurry becomes white due to efflorescence over time due to the moisture sprayed on the surface, and is likely to cause colored spots.
In order to avoid this drawback, if the amount of water sprayed on the surface is reduced, the moisture in the cement slurry will be absorbed by the cement molded product, and the moisture required for the hydration reaction of the cement slurry will be insufficient, making it impossible to achieve sufficient hardening strength.

By specifying the moisture distribution inside and on the surface of cement molded products, the present invention has developed a method for applying cement slurry not only to cement molded products after curing, but also to cement molded products immediately after molding. An important objective of the present invention is that the surface paint of the cement slurry can be applied to the cement molded product after curing, so that the surface coloring layer can be applied even more strongly to the cement molded product. To provide a method for producing surface-coated cement molded products that can efficiently and economically apply paint to cement molded products of various shapes without being subject to any restrictions.

Another important object of the present invention is to provide a surface-painted cement molded product that allows cement slurry to firmly adhere to the surface of the cement molded product and to form a uniform, thin and tough surface colored layer over the entire surface. To provide a manufacturing method.

Furthermore, another important object of the present invention is to increase the moisture content of the cement slurry so that the surface paint can be easily applied, the pot life can be extended, and the surface paint can be easily managed. The present invention provides a method for manufacturing a painted cement molded product.

[Means to solve conventional problems] A cement molded product made by kneading aggregate, cement, and water and molded into a predetermined shape is heated at a temperature x time.
Curing is carried out at 150°C or higher, preferably 250°C or higher, and more preferably 300°C or higher. Curing includes autoclave curing, steam curing, natural curing, underwater curing,
Either moist curing is acceptable. The cured molded product is coated with cement slurry with the internal moisture content adjusted to within the range of 6.5% to 9%, and with a dry color on the surface.

A mixture of cement, pigment, synthetic resin emulsion, and water is used in the cement slurry, and the mixing ratio of the synthetic resin emulsion is adjusted to a range of 5 to 15 parts by weight based on 100 parts by weight of cement.

[Operations and Effects] This invention allows molded cement products to be heated to 150°C.
After curing for more than an hour, the internal moisture content is 6.5 to 9%.
Cement slurry is applied to the surface as a dry color. The cement product to which the cement slurry is applied in this state contains a relatively large amount of water inside, and a layer with relatively low water content is provided on the surface surrounding it. .

When a cement slurry is applied to this wet cement product, immediately after application, the water contained in the cement slurry is absorbed by the surface portion of the cement product. Therefore, a cement slurry with a high moisture content can be used as a cement slurry to be applied to a cement product, thereby improving the fluidity of the cement slurry before application. Therefore, the advantage of being able to uniformly apply the cement slurry to the surface of the cement molded product in a thin film is realized.

Immediately after the cement slurry is applied, water in the cement slurry penetrates into the cement molded product, and at this time, the water acts as a transport medium and fine particles of cement penetrate into the surface of the cement product. Furthermore, since the cement product is not in a completely hardened state, the cement that permeates from the cement slurry and the cement product harden together, thereby preventing delamination. For this reason,
The adhesion of surface paint is improved, and a durable and strong colored surface layer can be formed.

Furthermore, a notable feature of the present invention is that it can effectively prevent moisture contained in cement products from adversely affecting surface coatings. In other words, if a cement product contains a large amount of water,
This moisture migrates to the surface and causes efflorescence in the surface paint. This is because the water that migrates from the inside of the cement product to the surface is highly alkaline, which causes efflorescence to occur in the surface paint. However, the cement product to which the cement slurry is applied by the method of the present invention has a region with a relatively high moisture content inside, which is surrounded by a region with a relatively low moisture content. In this state, the cement product can slow down and reduce the movement of moisture from the inside to the surface, even in areas where the surface moisture is low. When surface migration of water is slowed down and reduced, the cement slurry hardens without coming into contact with surface migration water, but rather with water being absorbed. The cement slurry containing the synthetic resin emulsion that is completely cured in this state can prevent subsequent water permeation, and can minimize the occurrence of efflorescence.

That is, the method for manufacturing a cement product of the present invention has contradictory characteristics by realizing a unique water distribution state. It has the features of both ease of application of cement slurry and prevention of efflorescence.

Furthermore, at temperatures above 150℃, the moisture content is 6.5 to 9.
% cured cement products have the advantage that the cement hardens to some extent and retains its shape by itself, making it easier and more efficient to apply cement slurry than to molded products immediately after molding.

Furthermore, the manufacturing method of the present invention can store a considerable amount of molded cement molded products and efficiently surface-treat them continuously at one time, so it can efficiently surface-treat cement molded products manufactured in small quantities in a wide variety of products. Moreover, it is also possible to use cement slurry with a short pot life effectively without wasting it.

[Preferred embodiment] Examples of the present invention will be described below.

Cement, hard fine aggregate such as silica sand, and water are kneaded and then molded into a predetermined shape using a mold to obtain a cement molded product. The shape of the cement molded product can be shaped like a thick slate tile, a corrugated shape, or a flat plate shape, depending on the purpose.

The amount of aggregate mixed into the cement molded product is 64 or less by weight to 33 of the cement material, but 40
It can also be used within the range of ~80.

The molded cement molded product is formed by temperature x time.
Cured at 150℃ or more. In cement molded products that are cured at 150°C or more, the cement hardens to some extent and retains its shape.

Furthermore, if it is cured over 250℃, it will harden even more.
Items cured at 300°C or higher exhibit ideal shape retention.

In the inventor's experiments, the temperature was 5°C or higher and the humidity was approximately 70°C.
% indoors until the temperature x time reached 300°C, the internal moisture content was 8.53 to 9.07%. Furthermore, when cured at 300°C under the same temperature and humidity conditions, the moisture content of the cement molded product decreased to 6.82-7.56%. Furthermore, this cement molded product is
When cured at 2500℃ at a temperature of 60℃ or higher and a humidity of 70%, the moisture content inside the cement molded product will be 5.69 to 6.56.
%.

For curing of cement molded products, steam curing, natural curing, autoclave curing, underwater curing, and moist curing can be used. However, before curing in water, it is better to harden the cement to some extent by other curing methods.

The cement molded product cured in this state was soaked in water for over 30 minutes to allow water to penetrate inside. After the water has been absorbed inside, the surface of the cement molded product is forcedly blown, or left in dry air, or the water adhering to the surface is wiped with a water-absorbing material such as cloth to remove the water adhering to the inside. After adjusting the moisture content to 6.5-9.0%,
Apply cement slurry surface paint.

A state in which the surface of a cement molded product has become a dry color means a state in which the surface of a cement molded product, which had been a wet color after molding, has changed to a white dry color.

Instead of immersing the cement molded product in water, supplying moisture to the interior can also be achieved by sprinkling water on the surface for a certain period of time.

Cement molded products cured in extremely humid conditions have a high internal moisture content after curing. If the internal moisture content is higher than 7.8%, forcefully blow air to the surface without necessarily submerging it with water or sprinkling it with water.
Alternatively, this can be left under dry air for a certain period of time to give a dry color to the surface, and then a cement slurry can be applied.

After curing, the surface of the cement molded product from which the water adhering to the surface has been removed is coated with cement slurry to an average thickness of 50 to 500 microns, preferably 150 to 400 microns, using a spray gun or ricing gun. Apply paint.

The surface paint consists of 100 parts by weight of Portland cement, 10 parts or less of pigment, 5 to 15 parts of synthetic resin emulsion, 40 parts or less of water with a water temperature of 15°C or less, and if necessary, a small amount of antifoaming agent. Knead to make cement slurry.

Fly ash may be used in some portions of Portland cement.

As the synthetic resin emulsion, for example, synthetic rubber emulsions such as acrylic emulsion, ethylene vinyl acetate copolymer emulsion, polyvinyl acetate, vinyl acetate acrylic copolymer, epoxy resin, and styrene-butadiene can be used.

Synthetic resin emulsions, in their hardened state, block the permeation of moisture, prevent cracks, and are effective in preventing efflorescence. If the mixing amount is too small, cracks and efflorescence may occur, and if it is too large, the amount of cement decreases and the strength of the cement after hardening decreases.

To prolong the pot life of cement slurry, cold water is used and the temperature is maintained at 30°C even during use.
It is best to keep it below ℃. When the cement slurry was kneaded with tap water at 30°C without cooling, the temperature of the cement slurry became high due to the hydration reaction, and the pot life was about 15 minutes. On the other hand, cement slurry that is mixed with cold water and kept at a temperature of 24.5℃ after mixing has a viscosity of 1600CP and 60℃ immediately after mixing.
After a few minutes, the temperature of the cement slurry rose to 30°C, and the viscosity remained almost unchanged at 1500CP.

Cement molded products coated with a cement slurry surface coating are coated with a resin coating, i.e., a top coat, to a thickness of 5 to 30 microns, preferably 10 to 20 microns, and maintained at a temperature of 20°C or higher and a humidity of 80% or higher. Let it cure and harden for over 10 hours.

For the top coat, synthetic resin paints such as solvent-based, acrylic emulsion-based, and acrylic-based paints can be used.

When the surface of the cement slurry is covered with a top coat, the surface coloring paint of the cement slurry remains more beautiful and does not deteriorate for a long time.

Claims (1)

[Claims] 1. After kneading aggregate, cement, and water and molding the mixture into a cement molded product of a certain shape, a surface paint of cement slurry is applied to the surface of the cement molded product that has not completely hardened. In the manufacturing method for surface-coated cement molded products, a mixture of cement, pigment, synthetic resin emulsion, and water is used in the cement slurry, and the mixing ratio of the synthetic resin emulsion is 100 parts by weight of cement. It is adjusted to a range of 5 to 15 parts by weight,
Furthermore, the molded cement molded product was cured at a temperature x time of 150℃ or more to reduce the internal moisture content to 6.5%.
A method for producing a surface-coated cement molded product, characterized in that the surface is coated with a cement slurry adjusted to a range of 9% or less and the surface is dried in color. 2. A method for producing a surface-coated cement molded product according to claim 1, which comprises applying a surface paint after natural curing, steam curing, autoclave curing, underwater curing, or wet curing to a cement molded product. 3. The surface coating according to claim 1, wherein the cement molded product is immersed in water to adjust the internal water content before the surface coating is applied, and then the surface water is removed and the surface coating is applied. A method for manufacturing cement molded products.