JPH02307854A - Production of lightweight gypsum-cement mortar formed body - Google Patents

Abstract

PURPOSE:To produce the lightweight formed body excellent in water resistance by mixing hydration-curing gypsum, an anionic copolymer aq. emulsion, portland cement and water under specified conditions and hydration-curing the mixture. CONSTITUTION:From 10 to 100 pts.wt. of hydration-curing gypsum, 2-50wt.%, based on gypsum, of the solid copolymer in an anionic copolymer aq. emulsion obtained by emulsion-polymerizing a mixture of vinyl monomers using an anionic surfactant forming a chelate compd. with Ca ion and contg. 0-0.3wt.% carbonyl group, 100 pts.wt. of portland cement and an appropriate amt. of water are mixed and agitated to obtain a uniform liq. mixture. The liq. mixture is allowed to stand in a mold, kept at a temp. higher than the glass transition temp. (Tg) of the copolymer in the emulsion and lower than (Tg+45 deg.C) and hydration-cured to form a gypsum-cement mortar formed body contg. water which is dried to remove water. The desired formed body is thus obtained.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for producing a lightweight gypsum/cement mortar molded body useful as building materials such as ceiling materials, wall materials, and floor materials, and as core materials for monuments in amusement parks. It is something.

[Prior art]

Add anionic resin aqueous emulsion or nonionic resin aqueous emulsion (solid amount:
~30 parts by weight) and appropriate amount of water (the amount necessary for the hydration hardening reaction of gypsum, usually the theoretical amount of water mixed is 19 parts by weight, the standard amount of water mixed is 40 parts by weight), and the hydration hardening of the gypsum is performed. After the reaction, the density is 1.2-1.8f15! It is known to produce hardened gypsum with improved water resistance and strength (Japanese Patent Application Laid-open Nos. 54-37130, 57-179059, 53-121821, 51-129428,
No. 52-80327, No. 58-36957, No. 49
-17421).

In these conventional techniques, the amount of water (including water in aqueous emulsions) is either the theoretical amount required for hydration of gypsum (water/gypsum 0.186) or the standard mixed water t (water/gypsum 0.4
1), and the density of the cured product is 1.2 to 1.8 f/cj
Since it is not foamed, it lacks lightness and insulation properties.

As a lightweight gypsum molded body to improve this drawback, the present inventors have developed the following: Prisoner component: Hydration-hardening gypsum 100:iii parts (B
) Component: A copolymer aqueous emulsion obtained by emulsion polymerization of a vinyl monomer mixture using an anionic surfactant that forms a chelate compound with calcium ions, and the carboxyl group concentration in the i copolymer is Anionic copolymer which is 0 to 0.3% by weight 1 to 30 parts by weight based on the solid content of the aqueous emulsion copolymer Odor component: Water 0 to appropriate amount (■)
After mixing and stirring the (2) and (2) ingredients to make a uniform mixture, let it stand still in the mold, and adjust the liquid temperature of the mixture of (4), (J3), and (Q) to the aqueous emulsion of the (B) component. higher than the glass transition point (Tg) of the copolymer in (Tg+4s
) A hydration hardening reaction is carried out while maintaining the temperature at a temperature below 0.0°C to retain water to obtain a gypsum molded body, and then the gypsum molded body is dried to scatter water and have a specific gravity of 0.2 to 0. proposed a method for manufacturing lightweight plaster moldings of No. 65 (N Kaisho 63-3).
(See Publication No. 07175).

[Problem that the invention attempts to solve]

This lightweight gypsum molded body is lightweight and has excellent heat insulation properties, but it has poor water resistance and a significant decrease in strength when wet, which poses practical problems when used as a building material in the plumbing field.

[Specific means to solve problem B]

In the present invention, in the method for manufacturing a lightweight gypsum molded body disclosed in Japanese Patent Publication No. 63-307175, water-curable Portland cement is further used in combination to improve the water resistance strength of the molded body obtained.

That is, the present invention comprises: Ingredients: 10 to 100 parts by weight of hydrated gypsum Component (B): Emulsion polymerization of a vinyl monomer mixture using an anionic surfactant that forms a rechelate compound with calcium ions. Component (b) is an aqueous copolymer emulsion obtained by solid content of an anionic copolymer aqueous emulsion copolymer in which the carboxyl group concentration in the copolymer is 0 to 0.3% by weight. 2 to 50 parts by weight of gypsum (M-5) [However, the amount of anionic surfactant used per 100 parts by weight of the copolymer is 0.6 to 2.5 parts by weight in terms of solid content. JC) Ingredients: Portland cement 100 m0 water
(Above-mentioned amount of eligible bonds), [
F]), Ω and 0 components are mixed and stirred to make a uniform mixture, and then left to stand in a mold to form (4), CB), 0 and ■
A hydration curing reaction is carried out by maintaining the liquid temperature of the mixed liquid of the components at a temperature higher than the glass transition point (Tg) of the copolymer in the aqueous emulsion of the component [F] and below (Tg + 45) ° C. , obtain a gypsum/cement mortar molded body that retains water,
The present invention provides a method for producing a lightweight gypsum/cement mortar molded body, which is characterized in that the molded body is then dried to scatter moisture.

(Hydration-hardening gypsum) As the hydration-hardening gypsum of component (1), α-hemihydrate gypsum, β-hemihydrate gypsum, ■-type anhydrite, and β-anhydrite can be used. These gypsums undergo a hydration reaction and become a hardened product of dihydrate gypsum.

The correlation of these plasters is shown below.

Dry heating α-Ca8041/2HzO,l:uβ-CaSOa Wet heating This hydration-hardening type gypsum of component (4) has a faster hydration-hardening reaction rate than (0-component Portland cement), and the initial shape of the molded body It also has the function of causing cohesive failure of the anionic resin aqueous emulsion of component @) and gelling the uncured gypsum/cement slurry.

(Anionic copolymer aqueous emulsion) Component (6), the anionic copolymer aqueous emulsion, is a copolymer obtained by emulsion polymerization of vinyl monomers using an anionic surfactant that forms a chelate compound with calcium ions. The present invention is an aqueous polymer emulsion, the anionic copolymer aqueous emulsion having a carboxyl group concentration in the copolymer of 0 to 0.3% by weight.

Here, the carboxyl group concentration in the copolymer is the weight percent of the constituent units based on α, β-unsaturated acids in the copolymer, based on the total weight of the vinyl monomers forming the copolymer.
Shown with.

As the α,β-unsaturated acid, acrylic acid, methacrylic acid, fumaric acid, itaconic acid, crotonic acid, maleic anhydride, etc. are used. When the α,β-unsaturated acid is one that provides a copolymer with many carboxyl groups present on the surface of the copolymer particles, such as acrylic acid, itaconic acid, hexamaric acid, and maleic anhydride, carboxyl groups In addition, when providing a copolymer such as methacrylic acid in which many carboxyl groups exist inside the copolymer particles, the carboxyl group concentration should be set to less than 0.1% by weight.
The amount of α,β-unsaturated acid used in emulsion polymerization is adjusted so that it becomes 3% by weight or less.

As described in the above-mentioned publications, calcium ions (Ca) in gypsum react with the carboxyl groups (-COOH) of the copolymer of the resin aqueous emulsion and retard the curing reaction of the gypsum, so the anionic nature of the component @) It is preferable that the resin of the aqueous copolymer emulsion has as few carboxyl groups or acid groups as possible on the particle surface.

Although it is generally stated that ~3 parts by weight of hydrophilic monomers O, S improves the stability against Ca2+, the presence of carboxyl groups shows that curing is not achieved. however,
No influence of OH group or -CON& on Ca2+ was observed.

If it is unavoidable to use an α,β-unsaturated carboxylic acid such as acrylic acid, methacrylic acid, itaconic acid, fumaric acid, maleic anhydride, or crotonic acid as the vinyl monomer, the carboxyl group concentration in the copolymer must be the same as mentioned above. Use so that the concentration is below. If this concentration is exceeded, the Ca++ in the gypsum will be eaten away by the resin of the aqueous emulsion, and the time required for the hydration reaction of the gypsum will become longer, or the gypsum will not harden.

For this reason, as shown in Figure 2, the layer is separated into a hardened gypsum layer (lower layer) and an unhardened gypsum layer, or becomes an unhardened layer entirely.

This Ca+4 is ammonia ion of emulsifier, t", N
By ion exchange and chelation with metal ions such as a and Li, for example, the emulsifier becomes an organic disulfonic acid calcium salt or an organic carboxylic acid calcium salt with reduced hydrophilicity, lowering its surfactant ability and destroying the emulsion. The copolymer particles aggregate and coagulate.

Utilizing the aggregation and coagulation of the copolymer particles, the entire system is kept in a gel state until the hydration-curable gypsum hardens, and a hydration-cured gypsum/cement mortar molded body is obtained while retaining water.

Examples of emulsifiers include organic sulfonic acid salts such as lauric acid sulfonic acid under, stearic acid under, polyoxyethylene alkyl ether sulfate under, polyoxyethylene alkylphenyl ether sulfonic acid under, alkanesulfonic acid under, and alkylbenzenesulfonic acid under. ;Fatty acid metal salts such as aliphatic soaps, fatty acid sarcosides, and rosin acid soaps;These Na
.

As substitutes, K", NH4", sulfate ester type anionic surfactants or fatty acid derivatives having alkanolamine ions can be used.

These anionic emulsifiers have a solid content of 0.6 to 2 parts by weight per 100 parts by weight of the resulting aqueous emulsion copolymer.
．． It is used in a proportion of 5 parts by weight. If the emulsifier is used more frequently, the destructive effect of the emulsifier is small, and the expected aggregation of the copolymer particles does not occur partially or at all, and the hydration hardening reaction of the gypsum is inhibited.

If the amount is too small, the polymerization stability and storage stability of the aqueous copolymer emulsion will be low, and the copolymer particles will rapidly agglomerate, causing problems in the stability of mixing with gypsum.

That is, if it is less than 0.6 parts by weight, the copolymer particles will aggregate or the rate of aggregation will be rapid, making it difficult to maintain a uniform mixture of gypsum, Portland cement, copolymer aqueous emulsion, and water. When gypsum and portland cement are hydrated and hardened under static conditions, the volume ratio of the supernatant water layer is 35 to 50% when the water separates from the hardened gypsum or portland cement, and the volume ratio is 35 to 50%. (See figure) Water is not used effectively. For this reason, the density of the resulting lightweight five-arm cement mortar molded product tends to exceed xt/di, and the effect of improving the weight is small. Incidentally, when no emulsion is used, the density of the lightweight gypsum molded body obtained is 1 to 1.2 f/-.

If the amount exceeds 2.5 parts by weight, it will take time for the copolymer particles in the emulsion to coagulate and solidify, and depending on the constituent components of the copolymer in the emulsion, a part of the copolymer emulsion may turn into a hardened slag into gypsum/cementum. /8 (lower layer) and a separate layer (upper layer), and gypsum and portland cement form an unhardened middle layer (see Figure 2) separately from the hardened gypsum/cement mortar NJ (lower layer). Japanese hardening gypsum, Portland cement and anionic copolymer aqueous emulsions are not effectively utilized.

In addition to the anionic emulsifier, a nonionic surfactant such as polyoxyethelesia alkyl ether, polyoxyethylene alkylphenyl ether, polyoxyethylated castor oil, etc. may be used in combination.

This nonionic emulsifier is not affected by the aggregation effect of Ca or the like and has the ability to stabilize the copolymer resin particles from C,2+. In addition, it is stable and effective during polymerization of resin emulsions, and is effective as a dispersant for inorganic mixtures other than gypsum and various fibers.

However, if more than 2% is used, part of the resin emulsion cannot be coagulated, so it is better to use as little as possible. For this reason, it is preferable to blend a 7-ion emulsifier during or after polymerization in a range of 0 to 2% based on the copolymer particles of component (B).

Vinyl monomers that give the anionic copolymer include acrylic acid alkyl esters, methacrylic acid alkyl esters (these alkyl groups have 1 to 8 carbon atoms): 2-hydroxyethyl acrylate, 2-hydroxyethyl acrylate, and these. Methacrylate equivalents; esters such as acrylamide, methacrylamide, vinyl chloride, vinylidene chloride, ethylene, acrylonitrile, methyl methacrylate, vinyl acetate, styrene, acrylic acid, methacrylic acid, itaconic acid, fumaric acid, crotonic acid,
Maleic anhydride etc. can be used, and two of these vinyl monomers can be used.
The glass transition point of the copolymer particles of the resulting aqueous emulsion is preferably -30°C to +30°C.
The vinyl monomer is selected so that the number of carboxyl groups in the copolymer falls within the above-mentioned range. Note that if the so-called reactive emulsifiers such as sodium vinyl sulfonate and sodium vinylsulfonate are anions, they are treated as anionic emulsifiers.

Emulsion polymerization is carried out by a conventional method, and the resin solid content concentration in the resulting copolymer aqueous emulsion is 20 to 65% by weight.
The particle size of the copolymer particles is generally 0.03 to 3 microns.

The use of this anionic copolymer aqueous emulsion is as follows:
Although it is largely affected by the vinyl monomer cone constituting the copolymer, the solid content is generally 2 to 50 parts by weight per ioo parts by weight of hydration-curable gypsum of the Ω component. If the amount exceeds 50 parts by weight, an aqueous copolymer emulsion of N (upper layer) is formed separately from the gypsum/Portland cement layer (lower layer) containing the emulsion (see Figure 3), and the emulsion is not used effectively. If it is less than 2 parts, the dispersion effect is small.

As mentioned above, the amount of emulsion used in plaster is largely affected by the type of vinyl monomer that makes up the copolymer of the emulsion, and in general, those with functional groups such as acid groups, hydroxyl groups, and amide groups are better. , the upper limit of the amount used tends to be lower than that of copolymers that do not have these functional groups.

(Portland cement) Portland cement with Ω component improves the strength of molded objects,
Contributes to improved water resistance. As the Portland cement, white Portland cement, ordinary Portland cement, early strength Portland cement, ultra early strength Portland cement, moderate heat Portland cement, white Portland cement, etc. are used.

Father, Portland cement and other hydraulic cements such as alumina cement, blast furnace slag cement, silica cement, pozzolanic cement, fly ash cement,
Mixtures with Roman cement and mainline cement can also be used. (Water) Water not only contributes to the hydration hardening reaction of gypsum and Portland cement, but also serves as a dispersion medium for gypsum and Portland cement until the gypsum hardens, and also serves as a filler to obtain the desired density.

In general, when a large amount of water is used, a lightweight gypsum/cement mortar molded body with a lower compaction density (lighter weight) tends to be obtained. The disadvantage is that the amount of water layer increases.

The sum of the amounts of water in the Ω component and the water in the emulsion of the component (B) is preferably 150 to 750 parts by weight, based on 100 parts by weight of the sum of the amounts of Portland cement used as a plaster removal component in the Ω component. is 200 to 350 parts by weight. If the amount is too small, the resulting lightweight gypsum-cement mortar molded product will have a high density, and even if it exceeds 750 parts by weight, the improvement in the lightweight effect of the resulting lightweight gypsum-cement mortar molded product will be small, and the amount of water to be separated will increase. Note that this density is also related to the amount of components (used in the water layer).

(Optional components) In addition to the above (A), (B), C) and 0 components, if necessary, retardants such as lefunic acid and tartaric acid, lightweight aggregates such as clay and whitebait, fibers such as organic and inorganic metals, hollow Glass R'4 filler, starch, polyvinyl alcohol, methyl cellulose, protective colloid agents such as droxyethyl cellulose, component (B) emulsion breaking agent MgO, C
aO13r(OH)z, Mg COa, Ca(OH)z
Fillers such as organic/inorganic pigments, calcined lei, vermiculite powder, rhinilite, expanded polystyrene particles, reinforcing fibers such as nylon fibers, polyester fibers, and pulp may also be blended.

(Forming method) (4) Component gypsum, (B) component copolymer aqueous emulsion, (0 component Portland cement, Ω component water,
After adding other optional ingredients and stirring to make a uniform mixture, the mixture is poured into a mold and left to stand.

For mixing, these components may be added into the mold and then stirred.

The curing time of the plaster/cement mixture is within 60 minutes, preferably 20 to 40 minutes.

By the way, a liquid mixture consisting of (E) gypsum, (B) emulsion, (C) Portland cement, and ■water is (B)
It is best to mix a mixture of ) and 0 and a mixture of (b) and ・C) and cast the mixture, but the temperature of this mixture (before the hydration of plaster or cement heats up) is , (the temperature is higher than the glass transition point (Tg) of the copolymer particles of the intestinal component emulsion and below "Tg + 45°C".

The temperature of the liquid is immediately after mixing, and after that, as a matter of course, heat is generated due to the curing reaction and the temperature rises automatically.

The liquid temperature during mixing of the gypsum mixture is an important factor in the present invention, and the fusing power of the aqueous emulsion copolymer particles of component (B) is effectively utilized.

For this reason, the liquid temperature is set higher than the Tg (glass transition point) of the copolymer and within a temperature that is 45° C. higher than the glass transition point. At temperatures below Tg, the copolymer particles do not exhibit any fusing strength. At temperatures lower than Tg, even if the copolymer particles in the emulsion are subjected to the agglomeration effect due to α, etc., the adhesion between the copolymer particles in the emulsion and between the copolymer particles and gypsum, Portland cement, and various additive components will decrease. (Film-forming power) cannot be expected, and the gypsum components from the mixed solution of (To), (B), C) and 0 proceed to settle, resulting in large separation of water. However, even if the liquid temperature is below Tg before the water hardens, after mixing, as time passes and the hydration reaction of the gypsum progresses, heat is generated and the temperature of the mixed liquid/liquid may rise and exceed 1. Until then, it is not practical because it is necessary to stir the liquid to make a homogeneous mixture so as not to cause separation.

Next, KrTg + 4s°C" If the temperature is high, the copolymer particles of component (B) will be extremely soft, so when mixed, the small particles of the copolymer will correct the agglomeration, and at the same time the copolymer will Copolymer particles are formed at the moment of mixing and fusion of particles occurs.
The gypsum and portland cement may coagulate to form a gum-like substance, or the liquid may significantly thicken, making it impossible to obtain a lightweight gypsum/cement mortar molded body with the desired density.

The temperature of the hydration curing reaction of the liquid mixture is preferably Tg+(1
0-30)°C is good.

The measurement of the glass transition point (Tg) tends to vary depending on the measurement method and conditions, but in the present invention, a DuPont differential thermal analyzer 109 is used.
Measurement was carried out using Type 0 at a temperature increase rate of 10° C./min.

Hydration reaction begins at the same time as gypsum (4) is mixed with water.
Ca2+ ions are released. Ca2+ from gypsum replaces the metal ion or ammonium ion of the anionic emulsifier that controls the emulsifying function in the emulsion, and the emulsifier becomes a hydrophobic salt. At the same time as the particles are agglomerated, the copolymer 6 gypsum particles bond together, increasing the viscosity of the mixture, coagulating it, and fixing the gypsum 1. The gypsum fixed with the copolymer particles 1 undergoes a rapid hydration reaction and solidifies into hydrated stone If (CaSO3.2 H2O), yielding a gypsum/cement mortar molded body (3) that retains water. Then, by taking out the water-retaining gypsum/cement mortar molded body (3) from the mold 4, drying and curing it, and scattering the water, a lightweight gypsum/cement mortar molded body t*(5) can be obtained. Yes, it can be done (see Figure 1).

During drying (curing) of this water, and even after drying, the water hardening reaction of Portland cement continues, increasing the strength of the lightweight gypsum-cement mortar molded body.

During aggregation and coagulation of the copolymer particles of the emulsion, excess water may be separated and become a supernatant liquid 6. Of course,
As mentioned above, depending on the type and composition ratio of vinyl monomers constituting the emulsion copolymer and the type of emulsifier,
The form shown in FIG. 3 may also be shown.

＠Quantity To improve the surface strength of the plaster/cement mortar molded product, place pulp paper, non-woven fabric, etc. on the bottom of the mold 4 in advance.
It is preferable to lay a glass nonwoven fabric or the like. It is also possible to solidify it on a cement base material such as concrete or a slate board, or on a metal plate, or a sandwich structure of these may be used.

In the present invention, since the density is very low, the contact density with these pulps, etc. is reduced, so if the fibers, etc. on the surface that comes into contact with the mixture are napped, the adhesive strength can be further improved.

Hereinafter, the present invention will be explained in more detail with reference to Examples. Note that parts and percentages in the examples are based on weight unless otherwise specified.

Example 1 Temperature controller, squirrel-shaped stirrer, reflux condenser, supply container,
The following raw materials were charged into a reaction vessel equipped with a thermometer and a nitrogen inlet tube.

water 200
35% aqueous solution of the sodium salt of the ester of p-nonylphenol in sulfuric acid (anionic emulsifier A) reacted with 20 moles of pentatylene oxide
3.9 parts Then, after purging the inside of the reaction vessel with nitrogen gas, 10% of the feed I shown below was added, and the mixture was heated to 90°C.

Feed I Water 206
35% aqueous fy of the above anionic emulsifier, 19 parts styrene 192 parts acrylic acid n-
Butyl 194 parts Acrylamide
14 parts.

Furthermore, after charging 10% of 2.5 parts of potassium persulfate dissolved in 85 parts of water (feed U) into the container, all of the remaining feed I and 90% of feed .The feed was fed into the container over a period of 5 hours, and after the feeding was completed, the feed I was kept at the same temperature for 2 hours to polymerize the anionic resin aqueous emulsion (Tg - 87°C) with a -COOH content of 0% by weight. Obtained.

Examples 2 to 9 Aqueous emulsions of copolymer particles having the physical properties shown in the same table were obtained by varying the type of vinyl monomer and the type and amount of emulsifier as shown in il.

Note that the nonionic emulsifier was first charged into the reaction container.

(Left below) Examples 1 to 11, Comparative Examples 1 to 9 Zoo part of C-class ρ hemihydrate gypsum from Riku Kagaku Kogyo ■, 10 parts of the copolymer aqueous emulsion obtained in Example 1, ordinary Portland cement and lightweight aggregate 1 Winry) C8-50'' (trade name of Ijite Kasei ■) and water at 20℃ in the proportions shown in Table 2.
This was mixed uniformly for 2 minutes using a stirrer to obtain a mixed solution.

This liquid mixture was injected into the mold and allowed to stand still.

The mold was left at 25° C. for about 60 minutes, and heat generation was observed about 30 minutes after the gypsum hydration reaction took place. The volume ratio of the aqueous layer in the supernatant layer after 60 minutes was as shown in Table 2.

Then, after leaving it for 1 hour, the plaster/cement mortar molded body holding the solidified water was removed from the mold and placed in the atmosphere (45
The molded body was dried for 10 hours at
A lightweight cement mortar molded body having a density and compressive strength (C1) shown in Table 2 and having a density and compressive strength (C1) shown in Table 2 was obtained.

The compressive strength (C2) measured after this lightweight gypsum/cement mortar molded body was immersed in water at 20° C. (in a humid atmosphere) for 16 hours was as shown in Table 2.

(The following is a blank space) Examples 12 to 19 Light-weight gypsum/cement mortar having the physical properties shown in Table 3 was obtained in the same manner as in Example 1, except that the composition of the mixed liquid was changed as shown in Table 3.

(Effects) In the present invention, by using gypsum and Portland cement together, it is possible to obtain a lightweight gypsum/cement mortar molded body that is lightweight and has excellent water resistance.

(Margin below)

[Brief Description of the Drawings] Figure 1 is a flow sheet diagram showing the manufacturing process of the lightweight gypsum/cement mortar molded body of the present invention, and Figures 2 and 3 are
FIG. 2 is a cross-sectional view showing a dispersion state of a mixed liquid when gypsum, Portland cement, and a resin emulsion are mixed and the mixed liquid is left to stand. Patent applicant Mitsubishi Yuka Verdate Co., Ltd. Agent
Patent Attorney Tadashi Hase Daido Takaya Yamamoto Figure 2

Claims (1)

[Claims] 1), Component (A): 10 to 100 parts by weight of hydration-curable gypsum Component (B): A mixture of vinyl monomers using an anionic surfactant that forms a chelate compound with calcium ions. A copolymer aqueous emulsion obtained by emulsion polymerization of an anionic copolymer aqueous emulsion copolymer in which the carboxyl group concentration in the copolymer is 0 to 0.3% by weight. 2 to 50% by weight of gypsum [However, the amount of the anionic surfactant used per 100 parts by weight of the copolymer is 0.6 to 2.5 parts by weight in terms of solid content. ] Component (C): 100 parts by weight of Portland cement (D) Appropriate amount of water Mix the above components (A), (B), (C) and (D),
After stirring to make a uniform mixture, leave it in the mold, (A)
, the temperature of the mixture of components (B), (C) and (D) is (
Forming a plaster/cement mortar that retains water by carrying out a hydration curing reaction at a temperature higher than the glass transition point (Tg) of the copolymer in the aqueous emulsion of component B and below (Tg + 45)°C. A method for producing a lightweight plaster/cement mortar molded body, which comprises obtaining a molded body, and then drying the molded body to scatter water.