JPH0147423B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a gypsum plaster composition containing molded anhydrite as a main component, which is particularly suitable for use as a cast flooring material. In Japanese Patent Application No. 54-162858 (Japanese Unexamined Patent Publication No. 56-88858), the present inventors have developed a gypsum plaster composition suitable for cast flooring by adding (a) potassium sulfate to 100 parts by weight of molded anhydrite. 0.2 to 5.0 parts by weight, (b) 0.5 to 10.0 parts by weight of an alkaline substance, and (c) 0 gypsum hemihydrate.
~23.0 parts by weight, (d) 0.05 to 2.0 parts by weight of methyl cellulose and/or hydroxyethyl cellulose, and (v) melamine-formalin condensate sulfonate/polyalkylaryl sulfonate mixing ratio of 85 to 95/15 by weight. A gypsum plaster composition for cast flooring is proposed, which is made by adding 0.5 to 1.5 parts by weight of a melamine-formalin condensate sulfonate to polyalkylaryl sulfonate mixture of 5 to 5. The present invention uses a lignin sulfonate instead of a polyalkylaryl sulfonate in the above composition for a cast bed,
The gist thereof is: A gypsum plaster composition for cast flooring comprising the following components added to 100 parts by weight of molded anhydrite. (i) Potassium sulfate: 0.2 to 5.0 parts by weight; (b) Alkaline substances: 0.5 to 10.0 parts by weight; (c) Gypsum hemihydrate: 0 to 23.0 parts by weight; (d) Methylcellulose and/or hydroxyethylcellulose: 0.05 to 2.0 Weight parts and (e) melamine-formalin condensate sulfonate/
Mixing ratio of lignin sulfonate is 85~ by weight
95/15-5 melamine-formalin condensate sulfonate-lignin sulfonate mixture: 0.3-1.5 parts by weight. It is in. The gypsum plaster composition for cast flooring of the present invention (hereinafter simply referred to as "composition of the present invention") includes:
It is manufactured by adding and mixing predetermined amounts of each of the above components to molded anhydrite. In the present invention, any type of anhydrite that can set and harden through hydration can be used, and suitable examples include phosphoric acid by-product gypsum, natural gypsum, and wet flue gas desulfurization gypsum. In addition to molded anhydrite obtained by firing at a temperature of 500°C or higher, examples include fluoric acid by-product anhydrite and natural anhydrite calcined and crushed. Some phosphoric acid by-product gypsum and fluoric acid by-product gypsum contain acids as impurities, but when such gypsum is used as a raw material, alkaline substances such as caustic potash and caustic soda are added to the gypsum before or after calcining. , slaked lime, quicklime, or similar alkaline substances must be added to neutralize the acid content. Type anhydrite with different crystal shapes, crystal porosity, etc. can be used, and there is no need for special pulverization, and the average particle size is usually 20~20 mm.
Approximately 70μ, standard water content 40±10%, Blaine specific surface area 2000-8000cm ² /g, light bulk density 0.6-0.9
If it falls within the range of g/cm ³ , it can be suitably used, so commercially available powder products can be used as they are. The composition of the present invention contains hydration and hydration of type anhydrite.
Potassium sulfate is included as a component to accelerate the setting rate. As a setting accelerator for molded anhydrite,
Conventionally, water-soluble sulfates such as potassium alum and aluminum sulfate are commonly used, but these water-soluble sulfates make gypsum slurry acidic and corrode metals that come into contact with the slurry and its hardened material. . Therefore, when these sulfates are used as a setting accelerator, it is necessary to neutralize the gypsum slurry by using an anticorrosive agent or an alkaline substance in order to prevent corrosion of metals. When potassium is used, the gypsum slurry usually becomes neutral or alkaline, so in this case, an alkaline substance for neutralizing the slurry is not particularly required, which is economical. In addition, when potassium alum, aluminum sulfate, etc. are added to molded anhydrite together with alkaline substances, aluminum hydroxide precipitates in the gypsum slurry, worsening the fluidity of the slurry and causing the production of hardened products. Although it impairs workability, when potassium sulfate is added to molded anhydrite, hydroxide does not precipitate in the gypsum slurry, not only when it is used alone, but also when used in combination with an alkaline substance, which improves workability. is good. For these reasons, potassium sulfate is particularly suitable as a setting accelerator for type anhydrite. The amount of potassium sulfate used in the composition of the present invention is 0.2 to 5.0 parts by weight based on 100 parts by weight of type anhydrite. If the amount of potassium sulfate used is less than 0.2 parts by weight, the setting rate of molded anhydrite will be extremely slow, and
Even if more than 5.0 parts by weight is used, the setting speed of anhydrite does not increase so much, and it is rather uneconomical. Simply adding potassium sulfate to molded anhydrite is still insufficient to shorten the setting time of anhydrite, and the initial strength of the hardened product is slow to develop.In order to improve this point, the composition of the present invention The substance contains an alkaline substance. Examples of alkaline substances that can be used include caustic potash, caustic soda, slaked lime, quicklime, and dolomite, but the present invention is not limited to these, and these alkaline substances can be used not only individually, but also They can also be used in combination. The amount of alkaline substance used in the present invention is:
The amount is 0.5 to 10.0 parts by weight per 100 parts by weight of type anhydrite. If the amount used is less than 0.5 parts by weight, it cannot be expected to shorten the setting rate of molded anhydrite or accelerate the development of the initial strength of the cured product, and if more than 10.0 parts by weight is used, the strength of the cured product will decrease. do. When a hardened product is produced by adding an alkaline substance containing potassium sulfate and sodium atoms, such as caustic soda or soda carbonate, to molded anhydrite and allowing it to hydrate and coagulate, efflorescence occurs on the surface of the hardened product. When an alkaline substance that does not contain potassium sulfate and sodium atoms, such as caustic potash or potassium carbonate, is added to molded anhydrite and allowed to hydrate and set, no efflorescence phenomenon is observed. Therefore, when the composition of the present invention is used in applications where efflorescence must not occur in the cured product, it is necessary to include an alkaline substance that does not contain sodium atoms in the composition. Note that some types of molded anhydrite may contain alkaline substances; for example, molded anhydrite produced by calcining natural gypsum may contain quicklime and calcium carbonate. Therefore, in the present invention, when such type anhydrite is used, there is no need to use an alkaline substance, or the amount of alkaline substance used can be reduced. When potassium sulfate and an alkaline substance are added to hydrate relatively coarse-grained anhydrite, such as those with a particle size of approximately 30 μm or more, the gypsum slurry may cause breathing (solid-liquid separation), and this When the gypsum slurry causes breathing, the setting speed of the molded anhydrite is delayed and the strength of the cured product is reduced. Therefore, in the composition of the present invention, when a coarse-grained anhydrite source is used as a mold anhydrite source, gypsum hemihydrate is included in the composition to avoid the above-mentioned troubles. Types of hemihydrate gypsum used in this case include α-type hemihydrate gypsum, β-type hemihydrate gypsum, and the like. These gypsum hemihydrates may have different crystal shapes, crystal porosity, etc., and there is no need for special pulverization, and commercially available powder products can be used as they are. The amount of gypsum hemihydrate to be used depends on the particle size and setting rate of the type anhydrite used, but is usually within 23.0 parts by weight per 100 parts by weight of the type anhydrite. If the amount of gypsum hemihydrate used is greater than this, the setting speed of the molded anhydrite will be too fast, making it difficult to handle the gypsum slurry. Note that when potassium sulfate and an alkaline substance are added to hydrate molded anhydrite with a particle size of approximately 30μ or less, the gypsum slurry usually does not cause breathing. When such a type of anhydrite is used as a source, it is not necessary to use gypsum hemihydrate. In addition, when producing molded anhydrite by firing a mixture of gypsum dihydrate and gypsum hemihydrate, manufacturing conditions such as firing temperature, firing time, content of impurities in the raw materials,
Depending on the type of inorganic additive used to lower the firing temperature, gypsum hemihydrate may remain in the product type anhydrite; however, if such type anhydrite is used, gypsum hemihydrate There is no need to use The composition of the present invention further contains methylcellulose or hydroxyethylcellulose in order to prevent the gypsum slurry from bleeding as much as possible. Methylcellulose and hydroxyethylcellulose come in various molecular weights, and the viscosity of their aqueous solutions differs depending on the molecular weight, so the amount to be used will vary depending on the type used, but if the amount used is too small, the gypsum slurry will be prone to breathing. On the other hand, if the amount used is too large, the viscosity of the gypsum slurry will increase and the fluidity will deteriorate. The amount of methylcellulose or/and hydroxyethylcellulose used is typically
The amount used is 0.05 to 2.0 parts by weight per 100 parts by weight, and a particularly preferred amount is such that the viscosity of the gypsum slurry at the initial stage of kneading is 800 to 4000 centipoise when measured with a B-type viscometer. Conventionally, various polymer emulsions, water-soluble synthetic polymers, and water-soluble natural polymers have been used in place of methylcellulose and hydroxyethylcellulose, but none of them are effective unless used in large amounts, or they cannot be dissolved in water. Many of them have drawbacks, such as being time-consuming, and nothing comparable to methylcellulose or hydroxyethylcellulose has been found. In addition, in the composition of this invention, methylcellulose and hydroxyethylcellulose can also be used together. Generally, the fluidity of gypsum slurry improves as the amount of water mixed in increases, so in order to improve workability during construction, the amount of water mixed is increased, but if the amount of water mixed is increased, breathing may occur. In addition, the setting of the gypsum slurry is delayed, requiring a long curing time, and the strength of the resulting cured product is reduced. Therefore, in order to avoid such troubles, it is desirable that the gypsum slurry has good fluidity even when the amount of mixed water is small. Therefore, the composition of the present invention contains a melamine formalin condensate sulfonate to a lignin sulfonate having a mixing ratio of 85 to 95/15 to 5. Contain a mixture. Conventionally, attempts have been made to incorporate melamine-formalin condensate sulfonate and lignin sulfonate into a gypsum plaster composition.
Both are effective in improving the fluidity of gypsum slurry, but when melamine-formalin condensate sulfonate is used alone, the initial strength of the cured product is insufficiently developed; When used, breathing may occur in the gypsum slurry and the strength of the cured product may decrease significantly. On the other hand, when melamine-formalin condensate sulfonate and lignin sulfonate are mixed in the ratio specified in the present invention and added to molded anhydrite, the gypsum slurry is good even when the amount of water mixed is small. In addition to maintaining liquidity,
When using melamine-formalin condensate sulfonate or lignin sulfonate alone, the initial strength of the cured product develops quickly, the gypsum slurry does not cause bleeding, and the strength of the cured product is sufficiently high. You can get exceptional effects that are impossible to achieve. The amount of the melamine-formalin condensate sulfonate-lignin sulfonate mixture used in the present invention is 0.3 to 100 parts by weight of type anhydrite.
It is 1.5 parts by weight. If the amount used is less than 0.3 parts by weight, if the gypsum slurry is left for a long time, the fluidity will deteriorate and the flow value will decrease, and if the amount used is more than 1.5 parts by weight, the fluidity of the gypsum slurry is good, but the hardened product will deteriorate. strength will decrease. In addition to the above-mentioned components, the composition of the present invention may contain, if necessary, ingredients commonly used in this type of composition in order to improve workability during the production of a cured product and various performances of the cured product. Any known additives such as setting regulators, antifoaming agents, aggregates, etc. can be appropriately blended. Examples of setting regulators (setting retarders) that are usually suitably used include citric acid, maleic acid, sodium tripolyphosphate, phthalic acid, sodium metaphosphate, peptone, and polypeptone. It is particularly advantageous to use peptone, sodium tripolyphosphate, maleic acid, etc., as the strength of the cured product is less likely to decrease, and even a small amount can be effective. When a gypsum slurry is made by adding water to the composition of the present invention, if the amount of water mixed is small, the viscosity of the slurry increases, and depending on the stirring conditions, air bubbles may enter the slurry, which may cause the hardening of the hardened product. Strength may decrease. In order to prevent this, it is preferable to previously incorporate a commercially available antifoaming agent such as an alcohol type, fatty acid ester type, or silicone type into the composition of the present invention. When using the composition of the present invention for constructing a cast floor, examples of the types of aggregates that can be appropriately included in the composition include, for example, wood flour, perlite, lightening materials such as shirasu paroon, and fillers; Sand, cement, etc. are also used. To illustrate the method for applying the composition of the present invention, a gypsum slurry is prepared by charging the composition of the present invention and water into a mixing tank equipped with a stirrer. On the other hand, the surface of base materials such as concrete slabs, PC boards, mortar floors, ALC boards, cellular concrete, etc. is pretreated by spraying or coating with water or polymer emulsion. Next, the gypsum slurry is poured onto the surface of the base material using a raindrop, bucket, or pump to form a horizontal floor surface through natural fluidization. In the composition of the present invention, even when the amount of mixed water is reduced, the gypsum slurry is easily fluidized, and even when left for a long time, there is almost no sedimentation of gypsum or aggregate, and it maintains sufficient self-smoothness. In addition, in the composition of the present invention, the setting speed of the molded anhydrite is fast, the density of the gypsum slurry is uniform, and no bleeding occurs until the composition is hardened. The absence of this breathing further promotes the setting of the type anhydrite, and the hydration setting rate of the composition of the present invention is almost comparable to that of hemihydrate. Furthermore, the cured product obtained by hydrating and coagulating the composition of the present invention quickly develops initial strength, and the strength of the cured product is sufficiently high. Next, the present invention will be explained in more detail with reference to examples, but the present invention is not limited to the following examples unless the gist thereof is exceeded. Example 100 parts by weight of type anhydrite, potassium sulfate, slaked lime, hydroxyethyl cellulose, hemihydrate,
Melmento F10 (product name, Showa Denko K.K. product) as a melamine-formalin condensate sulfonate and Pozolith No. as a lignin sulfonate.
5L (trade name, Nisso Master Builders Co., Ltd. product) was added in the proportions listed in Table 1, and Sannopco 14HP (trade name, Sannopco Co., Ltd. product) was added as an antifoaming agent.
0.05 part by weight was added and mixed well to produce the gypsum plaster composition for cast flooring of the present invention. Next, to 100 parts by weight of this composition, 100 parts by weight of a mixture of commercially available silica sand No. 5 and No. 6 in a weight ratio of 1:1 as an aggregate and 43 parts by weight of water were added and mixed, and then kneaded. I made slurry. The viscosity and flow value of the slurry thus obtained and the compressive strength of the cured product were measured, and the presence or absence of sedimentation of sand in the slurry and the occurrence of breathing were also observed. In addition, the viscosity of the slurry was measured using a B-type viscometer.
Measurements were taken immediately after the slurry was kneaded and at the time when it was allowed to stand for 60 minutes after kneading. In addition, the gypsum slurry was flowed down using a glass funnel onto a glass plate placed horizontally (the distance between the glass plate and the lower end of the funnel leg was 25 mm,
The inner diameter of the funnel leg is 8mm, and the amount of slurry used is 100mm.
ml) The width of the spread was taken as the flow value, and was used as an evaluation item indicating the fluidity of the slurry. In addition, the compressive strength of the cured product is 40mm
After pouring into a mold with dimensions of (height) x 40 m (width) x 160 m (length) and allowing it to solidify and harden, measurements were taken 24 hours later. The results obtained are shown in Table 1. Note that "out" in the column of "viscosity" in Table 1 indicates that the slurry viscosity exceeded 20,000 cps and could not be measured.

【table】

[Table] In Table 1, Experiments No. 1 to No. 8 are control examples. Experiments No. 1 to No. 3 are the results when using melamine-formalin condensate sulfonate alone, and the flow value tends to improve as the amount added increases, but the compressive strength is low at 50 Kg/ ^cm2 . Become. on the other hand,
If the amount added is reduced, the strength will be 140Kg/ ^cm2 ~ 160Kg/
^cm2 , but it loses fluidity after 60 minutes of kneading, making it unsuitable for cast flooring. On the other hand, in Experiments No. 4 to No. 6, lignin sulfonate was used alone, and as the amount added increased, the flow value became extremely good, but the compressive strength was 0 to 18 Kg/cm ²
And small breathing occurs. Experiments No. 7 and No. 8 were conducted when the mixing ratio of melamine-formalin condensate sulfonate/lignin sulfonate was outside the range of the mixing ratio of the present invention, and the flow value of the slurry and the compressive strength of the cured product were The temperature may be low and/or breathing may occur. Experiments No. 9 to No. 27 are the results for the compositions of the present invention. The mixing ratio of melamine formalin condensate sulfonate/lignin sulfonate was approximately 95/5 (Experiment No. 9-11, 19-21) and 90/10, respectively.
(Experiment No. 12-14, 22-24), and 85/15 (Experiment No.
15-17, 25-27) Type anhydrite mixture
The cases where 0.35, 0.70, and 1.15 parts by weight of each were added per 100 parts by weight are shown. The fluidity of each composition slurry is good, and neither sand settling nor breathing occurs, and the compressive strength of the resulting cured product is greatly improved.
Suitable as a cast flooring material.

Claims (1)

[Scope of Claims] A gypsum plaster composition for cast flooring, comprising the following components added per 100 parts by weight of Type 1 anhydrite. (i) Potassium sulfate: 0.2 to 5.0 parts by weight; (b) Alkaline substances: 0.5 to 10.0 parts by weight; (c) Gypsum hemihydrate: 0 to 23.0 parts by weight; (d) Methylcellulose and/or hydroxyethylcellulose: 0.05 to 2.0 Weight parts and (e) melamine-formalin condensate sulfonate/
Mixing ratio of lignin sulfonate is 85~ by weight
95/15-5 melamine-formalin condensate sulfonate-lignin sulfonate mixture: 0.3-1.5 parts by weight.