JPH0214309B2 - - 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 in cast flooring. The present inventors proposed a gypsum plaster composition suitable for cast flooring in JP-A-55-109252, in which 0.2 to 0.2 to
5.0 parts by weight, 0.5 to 10.0 parts by weight of one or more alkaline substances that do not contain sodium atoms, and 5.0 to 23.0 parts by weight of gypsum hemihydrate, and if necessary, a known setting retarder, In Japanese Patent Application No. 54-162858, an anhydrite composition comprising appropriate amounts of antifoaming agents, dispersants, admixtures, etc. is prepared by adding (a) 0.2 to 5.0 parts by weight of potassium sulfate to 100 parts of molded anhydrite. , (b) 0.5 to 10.0 parts by weight of an alkaline substance, (c) 0 to 23.0 parts by weight of gypsum hemihydrate, (d) 0.05 parts of methyl cellulose and/or hydroxyethyl cellulose.
~2.0 parts by weight and (v) melamine formalin condensate sulfonate with a mixing ratio of melamine formalin condensate sulfonate/polyalkylaryl sulfonate of 85~95/15~5 by weight ~ polyalkylaryl sulfonate Gypsum plaster compositions for cast flooring were proposed, each characterized by the addition of 0.5 to 1.5 parts by weight of an acid salt mixture. The present invention provides a gypsum plaster composition that has even better performance than the above-mentioned compositions as a cast flooring material, and its gist is as follows:
"Per 100 parts by weight of type anhydrite; (a) 0.2 to 5.0 parts by weight of potassium sulfate; (b) an alkaline substance that does not contain sodium atoms:
0.5 to 10.0 parts by weight, (c) Gypsum hemihydrate within 23.0 parts by weight, (d) Methyl cellulose or/and hydroxyethyl cellulose: 0.03 to 0.3 parts by weight, (e) Melamine-formalin condensate sulfonate/polyalkylaryl sulfonate Or the mixing ratio of lignin sulfonate is 85~100/15~ by weight.
Melamine formalin condensate sulfonate alone or a mixture of melamine formalin condensate sulfonate and polyalkylaryl sulfonate or lignin sulfonate: 0.5 to 0.
1.5 parts by weight, (f) 0.2 to 0.6 parts by weight of sodium sulfate or 0.1 to 0.3 parts by weight of sodium hydroxide, and if necessary, 0 to 2 parts by weight of polyvinyl alcohol. A gypsum blaster composition for poured flooring, which contains appropriate amounts of foaming agents, setting regulators, aggregates, etc. "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 calcining at a temperature of 500 to 1100°C, examples include anhydrite obtained by calcining and pulverizing fluoric acid by-product anhydrite and natural anhydrite. Among phosphoric acid by-product gypsum and fluoric acid by-product gypsum,
Some types of gypsum contain acids as impurities, but when using gypsum like this one as a raw material, the gypsum before or after calcination must contain alkaline substances such as caustic potash, caustic soda, slaked lime, quicklime, and other similar substances. It is necessary to add an alkaline substance to neutralize the acid content. There is no problem in using type anhydrite with different crystal shapes, crystal porosity, etc., and there is no need for special pulverization, and the average particle size is usually 20~20 mm.
If the diameter is about 70 μm and the standard water content is within the range of 40±10%, it is suitably used, and commercially available powder products can be used as they are. Furthermore, particles having a particle size of several μm, such as gypsum produced by hydrofluoric acid, are also used. 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. Conventionally, water-soluble sulfates such as potassium alum and aluminum sulfate have been generally used as setting accelerators for molded anhydrite. However, these sulfates make the gypsum slurry acidic, so the slurry and its hardened product are corrodes metals that come into contact with it. Therefore, when these sulfates are used as setting accelerators,
To prevent corrosion of metals, it is necessary to neutralize the gypsum slurry by adding an alkaline substance or to use an anticorrosive agent. Furthermore, when water is added to type anhydrite to which these sulfates are added together with alkaline substances,
Aluminum hydroxide is formed and precipitated in the resulting gypsum slurry, deteriorating the fluidity of the slurry and impairing workability during production of the cured product. In contrast, when potassium sulfate is used as a setting accelerator, the resulting gypsum slurry typically
It is neutral or alkaline. Therefore, in this case, there is no need for an alkaline substance for neutralizing the gypsum slurry, which is economical. In addition, in the case of potassium sulfate, not only when used alone but also when used in combination with an alkaline substance, hydroxide does not precipitate in the gypsum slurry and the fluidity of the slurry is not deteriorated, resulting in good workability. 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 invention is 0.2 to 5.0 parts by weight per 100 parts by weight of type anhydrite. If the amount of potassium sulfate used is less than 0.2 parts by weight, the effect of increasing the setting rate of molded anhydrite is small, and even if it is used in a large amount exceeding 5.0 parts by weight, the setting rate of molded anhydrite will not increase so much. It is uneconomical. Simply adding potassium sulfate to molded anhydrite is still insufficient to shorten the setting time of molded anhydrite, and the initial strength of the resulting hardened product is slow to develop. The composition of the invention contains an alkaline substance that does not contain sodium atoms. Alkaline substances containing potassium sulfate and sodium atoms in anhydrite, such as sodium hydroxide,
When hydrating and condensing by adding sodium carbonate or the like, efflorescence may occur on the surface of the resulting cured product. On the other hand, when potassium sulfate and an alkaline substance that does not contain sodium atoms are added to molded anhydrite and hydrated and solidified, no efflorescence phenomenon is observed on the surface of the resulting cured product. Examples of alkaline substances that do not contain sodium atoms used in the composition of the present invention include potassium hydroxide, potassium carbonate, slaked lime, quicklime, and dolomite, but the present invention is not limited to these. do not have. These alkaline substances can be used alone or in combination of two or more. In the composition of the present invention, the amount of the alkaline substance that does not contain sodium atoms is
It is 0.5 to 10.0 parts by weight per 100 parts by weight. If the amount is less than 0.5 parts by weight, it cannot be expected to shorten the setting time of molded anhydrite or accelerate the development of initial strength of the hardened product. Furthermore, if more than 10.0 parts by weight is used, the strength of the cured product obtained will decrease. Depending on the type, type anhydrite may contain alkaline substances that do not contain sodium atoms; for example, type anhydrite manufactured from natural gypsum may contain a considerable amount of lime. There is. When such type of anhydrite is used in the composition of the present invention, it is not necessary to add an alkaline substance that does not contain sodium atoms, or the amount of the alkaline substance added can be reduced. The particles are relatively coarse, e.g. the particle size is approx.
When anhydrous gypsum with a diameter exceeding 30 μm is hydrated by adding potassium sulfate and an alkaline substance that does not contain sodium atoms, the gypsum slurry may cause breathing (solid-liquid separation). When the gypsum slurry causes breathing, setting and hardening of the molded anhydrous gypsum is delayed and the strength of the resulting cured product is reduced. Therefore, when coarse-grained type anhydrite is used in the composition of the present invention, 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 vacancies, 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 molded anhydrite used, but is usually within 23.0 parts by weight per 100 parts by weight of molded anhydrite. If the amount of gypsum hemihydrate used exceeds this, the setting rate of the molded anhydrite becomes excessive, and the fluidity of the gypsum slurry decreases over time, making it difficult to handle. In addition, when anhydrous gypsum with a particle size of approximately 30 μm or less is hydrated by adding potassium sulfate and an alkaline substance that does not contain sodium atoms,
It has a fast setting speed and does not cause breathing. Therefore, when such type of anhydrite is used in the composition of the present invention, it is not necessary to use gypsum hemihydrate. In addition, when molded anhydrite is produced by firing gypsum dihydrate or a mixture of gypsum dihydrate and gypsum hemihydrate, the manufacturing conditions such as firing temperature, firing time, content of impurities in the raw materials, etc. In the end,
Gypsum hemihydrate may remain in the molded anhydrite obtained. Even when such type of anhydrite is used, it is not necessary to add hemihydrate. The composition of the present invention further contains methylcellulose and/or hydroxyethylcellulose in order to prevent the occurrence of a bleeding phenomenon in the gypsum slurry. Since the viscosity of an aqueous solution of methylcellulose and hydroxyethylcellulose differs depending on their molecular weight, the amount used varies depending on the type used. If the amount used is too small, the resulting gypsum slurry will be prone to breathing, or the aggregate and gypsum will settle, resulting in a short retention time of fluidity of the gypsum slurry, resulting in poor workability. On the other hand, if the amount used is too large, the viscosity of the gypsum slurry will increase, making it difficult for breathing and sedimentation of aggregate, gypsum, etc., but the fluidity will deteriorate. The amount of methylcellulose or/and hydroxyethylcellulose used in the composition of the present invention is usually 0.03 to 100 parts by weight of type anhydrite.
The amount is 0.3 parts by weight, and a particularly preferred amount is such that the gypsum slurry has an initial viscosity of 800 to 4000 centipoise when measured with a B-type viscometer. Depending on the type of anhydrite type used, if a large amount of methylcellulose or hydroxyethylcellulose is added, the initial strength of the resulting cured product will be low. In order to prevent this, the present invention includes polyvinyl alcohol in the composition of the present invention in such cases. There are polyvinyl alcohols with various molecular weights, and the viscosity of an aqueous solution thereof varies depending on the molecular weight, so the amount used varies depending on the type used. If too little is used, the gypsum slurry will be prone to breathing. On the other hand, if the amount used is too large, the fluidity of the slurry not only deteriorates over time, but also loses fluidity altogether. The amount of polyvinyl alcohol used in the composition of the present invention is 0 to 100 parts by weight of molded anhydrite.
2 parts by weight. In a preferred embodiment, the amount of methylcellulose and/or hydroxyethylcellulose used is the minimum necessary amount that does not cause the gypsum slurry to breathe, and polyvinyl alcohol is added thereto for reinforcement. In general, the fluidity of gypsum slurry improves as the amount of water mixed in increases, so in order to improve the workability of pumping and pouring during construction, the amount of water mixed is increased. If the amount is increased, breathing of the gypsum slurry will occur, the hydration and setting of the gypsum will be delayed, requiring a long curing time, and the strength of the resulting hardened product will decrease, so in order to avoid such problems, ,
It is desirable that the gypsum slurry has good fluidity even if the amount of mixed water is small. Therefore, in the composition of the present invention, a melamine formalin condensate sulfonate/polyalkylaryl sulfonate or a lignin sulfonate having a mixing ratio of 85 to 100/15 to 0 by weight is included. The melamine-formalin condensate sulfonate alone or a mixture of a melamine-formalin condensate sulfonate and a polyalkylaryl sulfonate or a lignin sulfonate are contained. Previous attempts have been made to incorporate melamine formalin condensate sulfonate, polyalkylaryl sulfonate, and lignin sulfonate into gypsum plaster, and all of these are effective in improving the fluidity of gypsum slurry. When melamine-formalin condensate sulfonate is used alone, the initial strength of the cured product obtained is insufficient,
On the other hand, when a polyalkylaryl sulfonate or a lignin sulfonate is used alone, bleeding of the gypsum slurry may occur or the strength of the cured product may decrease significantly. According to the research of the present inventors, when a melamine formalin condensate sulfonate and a polyalkylaryl sulfonate or a lignin sulfonate are mixed in the ratio specified in the present invention and added to molded anhydrite, Even when the amount of mixed water is small, the gypsum slurry maintains good fluidity and does not cause breathing, and the resulting hardened product quickly develops initial strength.
Moreover, it was found that the strength of the cured product was sufficiently high. Note that depending on the type of anhydrite type used, sufficiently satisfactory effects may be obtained even without the use of polyalkylaryl sulfonate or lignin sulfonate, so the composition of the present invention When such gypsum is used as a raw material, only melamine-formalin condensate sulfonate is used. In the composition of the present invention, the amount of melamine formalin condensate sulfonate alone or a mixture of melamine formalin condensate sulfonate and polyalkylaryl sulfonate or lignin sulfonate used is usually 100 parts by weight of type anhydrite. around
It is 0.5 to 1.5 parts by weight. If the amount is less than 0.5 parts by weight, the fluidity of the gypsum slurry may deteriorate if a long period of time has passed after slurry preparation, or if more than 50% by weight of sand is added to the molded anhydrite as aggregate. Flow value decreases. Moreover, when more than 1.5 parts by weight is used, the fluidity of the gypsum slurry is good, but the strength of the cured product decreases, which is not preferable. The composition of the present invention contains potassium sulfate and an alkaline substance that does not contain sodium atoms in order to increase the hydration and setting rate of the molded anhydrite and to accelerate the initial strength development of the cured product.
Depending on the type of molded anhydrite used, even if a large amount of these accelerators is added, the initial strength of the cured product may not develop quickly. In the present invention, in order to prevent the occurrence of such problems, sodium sulfate or aluminum hydroxide is included in the composition of the present invention. In the composition of the present invention, the amount of sodium sulfate used is 0.2 to 0.6 parts by weight per 100 parts by weight of type anhydrite, and the amount of sodium hydroxide used is 0.1 to 0.6 parts by weight.
It is 0.3 parts by weight. If the amount of sodium sulfate used is less than 0.2 parts by weight, it will not have the effect of accelerating the development of initial strength of the resulting cured product, and if it is used in a large amount exceeding 0.6 parts by weight, the development of initial strength will be accelerated, but It is not desirable because it causes efflorescence on the body. The same thing can be said about the amount of sodium hydroxide used. 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. Setting regulators (setting retardants) that are usually suitably used include citric acid, maleic acid, sodium tripolyphosphate, phthalic acid, sodium metaphosphate,
Examples include peptone, polypeptone, etc., especially,
It is advantageous to use peptone, sodium tripolyphosphate, maleic acid, etc. because the strength of the cured product is less reduced and even a small amount can have a regulating effect. When a gypsum slurry is prepared 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 be mixed into the slurry, which may cause the hardening of the hardened product. Strength may decrease. In order to prevent this, it is preferable to previously include a commercially available antifoaming agent such as alcohol, fatty acid ester, or silicone in the composition of the present invention. When the composition of the present invention is used in the construction of a poured-rolled floor, examples of aggregates that can be appropriately included in the composition include, for example, wood flour, perlite, lightening materials such as whitebait balloons, and bulking materials, as well as sand. , cement, etc. are also used. The embodiment of construction using the composition of the present invention will be illustrated. A gypsum slurry is prepared by mixing the composition of the present invention and water in 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, allowing natural flow to form a horizontal hardened floor surface. In the composition of the present invention, even when the amount of mixed water is reduced, the gypsum slurry is easily fluidized, and there is almost no sedimentation of gypsum or aggregate even when left for a long time.
Maintains good self-smoothness. Furthermore, in the composition of the present invention, the setting speed of the molded anhydrite is high, the density of the gypsum slurry is homogeneous, and no breathing occurs at all until the gypsum slurry is set and hardened. This absence of breathing further accelerates the setting of the type anhydrite, so that 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 exhibits initial strength quickly, has sufficiently high strength, and does not exhibit efflorescence. The ratio of each additive to the molded anhydride in the composition of the present invention is such that settling and breathing of gypsum and aggregate do not occur in the composition slurry, and the compressive strength ( A value exceeding 15 Kg/cm ² was obtained (one day after curing) and a range without efflorescence was selected. Next, the present invention will be specifically explained with reference to Examples. The present invention is not limited to the following examples unless it exceeds the gist thereof. Example: 100 parts by weight of each type of anhydrite was mixed with various additives in the proportions shown in Table 1, and in addition, 0.05 parts by weight of Sannopco 14HP (trade name, product of Sannopco Co., Ltd.) was added as an antifoaming agent. and mixed well to obtain various gypsum compositions. To each 100 parts by weight of each composition, 100 parts by weight of commercially available silica sand No. 5 was added as an aggregate, and 45 parts by weight of water were added and kneaded to prepare a gypsum composition slurry. In addition, "Melment F10" (trade name, Showa Denko K.K.) is a melamine-formalin condensate sulfonate.
product), polyalkylaryl sulfonate "Maginon 100" (product name, Yamasou Chemical Co., Ltd. product), and lignin sulfonate salt "Pozolith No.5L" (product name, Nisso Master Builders Co., Ltd. product) ) was used. The viscosity, flow value, and compressive strength of the cured product of the obtained gypsum composition slurry were measured, and the presence or absence of breathing in the gypsum composition slurry was determined.
The presence or absence of aggregate settling and the occurrence of efflorescence in the hardened body were observed, and the obtained results are shown in Table 1. The viscosity of the gypsum composition slurry was measured using a B-type viscometer immediately after the slurry was kneaded and at each time point when the slurry was allowed to stand for 60 minutes after kneading. In addition, the flow value of the gypsum composition slurry is determined by placing the gypsum composition slurry (100 ml) horizontally on a glass plate using a glass funnel (inner diameter of funnel leg: 8 mm).
(distance between the glass plate and the lower end of the funnel leg: 25 mm), and the spreading width of the slurry was measured and used as a flow value, which was used as an evaluation item indicating the fluidity of the slurry. In addition, the compressive strength of the cured product is determined by molding the gypsum composition slurry (dimensions: height 40 x width 40 x length 160, mm)
Measurements were taken 24 hours after pouring into a container and allowing it to set and harden. In Table 1, Experiment Nos. 1 to 22 are control examples, and Experiments Nos. 23 to 40 are the columns of the present invention. The gypsum compositions shown in Experiment Nos. 1 to 22, which lacked the requirements of the compositions of the present invention, did not cure, or even when cured, the strength of the cured product obtained was low, or the cured product had efflorescence. However, the desired results of the present invention could not be obtained in either case. On the other hand, in the composition of the present invention,
As shown in Nos. 23 to 40, the slurry maintains good fluidity due to the synergistic effect of each added component, and there is no sedimentation or breathing of the aggregate, and the resulting hardened product is compressible. The strength was high and no efflorescence was observed.

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[Table] Note: ×…Yes, ○…No]

Claims (1)

[Claims] Per 100 parts by weight of type 1 anhydrite; (a) 0.2 to 5.0 parts by weight of potassium sulfate; (b) an alkaline substance that does not contain sodium atoms:
0.5 to 10.0 parts by weight, (c) Gypsum hemihydrate within 23.0 parts by weight, (d) Methyl cellulose or/and hydroxyethyl cellulose: 0.03 to 0.3 parts by weight, (e) Melamine-formalin condensate sulfonate/polyalkylaryl sulfonate Or the mixing ratio of lignin sulfonate is 85~100/15~ by weight.
Melamine formalin condensate sulfonate alone or a mixture of melamine formalin condensate sulfonate and polyalkylaryl sulfonate or lignin sulfonate: 0.5 to 0.
1.5 parts by weight, (f) 0.2 to 0.6 parts by weight of sodium sulfate or 0.1 to 0.3 parts by weight of sodium hydroxide, and if necessary, 0 to 2 parts by weight of polyvinyl alcohol. A gypsum plaster composition for cast-iron floors, which is made by blending appropriate amounts of additives, setting regulators, aggregates, etc.