JPH09300526A - Cement molded object containing thermoplastic resin and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain homogenous and stable mechanical strength by mixing a thermoplastic resin and hydraulic cement in a specific wt. ratio to mold the resulting mixture into a sheet and treating the sheet with an acidic aq. solution to form an intermediate molded article wherein an inorg. reaction product is precipitated on the cement layer and heating and integrating a plurality of the intermediate articles in a laminated state to cure the intermediate molded articles within a short time. SOLUTION: A mixture of 100 pts.wt. of a thermoplastic resin and 50-600 pts.wt. of hydraulic cement is treated with an acidic aq. soln. to form an inorg. reaction product C from a surface layer (m) to the deep part of an inner layer part (n). A plurality of sheet like intermediate molded articles 1a, 1b, 1c... thus formed are laminated to the integraty heated to obtain a thermoplastic resin-containing cement molded object 1. Therefore, this molded object has intermediate physical properties of a thermoplastic resin and cement and are homogenous in physical properties and can be enhanced in fire retardancy because the inorg. product of the cement layer is present up to the inner layer part of the molded object.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cement molded article containing a thermoplastic resin and a method for producing the same, and more specifically, it is mainly composed of a thermoplastic resin and cement and has intermediate properties between the two and excellent flame retardancy. Further, the present invention relates to a cement molded product containing a thermoplastic resin, which is suitable for applications such as building materials and civil engineering materials, and a method for producing the same.

[0002]

2. Description of the Related Art In recent years, as a cement-based molded product, for example, a plate-shaped material, a block-shaped material, or another form of construction material, a main component, cement, is mixed with a thermoplastic resin,
This was heat-molded, cured with water and cured,
So-called thermoplastic resin-containing cement compacts have been award-winning. This kind of molded product is intermediate in properties between thermoplastic resin and cement and is lightweight, and is expected to exhibit excellent flame retardancy as a material used for interior decoration of buildings. It is what

Conventionally, as a molded article of this type, for example, a mixture of a thermoplastic resin and a hydraulic cement to which a hydrophilic substance is added is heated and kneaded, and then molded, and the molded article is made to absorb water and cured (see, for example, Japanese Patent Laid-Open Publication No. Hei 10 (1999) -242242). 7-10626) is known. This is because the curing step of hydrating and hardening the cement is by means of immersing the intermediate molded product after the heat molding of the mixture in water, and imparting water wettability to the thermoplastic resin by the additive. It is effective from the viewpoint of efficient hydration, but when the desired thickness of the molded body is large, the inner layer part lags behind the surface layer part in curing, and sufficient and homogeneous physical properties are not always obtained. In addition, the flame retardancy is not sufficient.

As another example of this type of molded article, from the standpoint of making a thermoplastic resin flame-retardant, a mixture obtained by adding a calcium compound and a surfactant to a thermoplastic resin is melt-molded to obtain a molded article. A method is known in which the body is treated with an acidic aqueous solution to absorb water and harden (Japanese Patent Publication No. 52-30013). This is to improve flame retardancy by treating a molded body with an acidic aqueous solution to generate a reaction product such as a water-of-crystal-containing calcium compound due to water absorption in the molded body. And the obtained molded body is
Conceptually, as shown in FIG. 2, the molded product (11) is cured by absorption of an acidic aqueous solution from the surface (f) to produce the reaction product (c). This method is also an effective method for improving the physical properties, but like the above example, when the desired thickness of the molded body is large, the inner layer portion (n ') is more than the surface layer portion (m'). The curing is delayed, and the reaction product (c) is generated in the surface layer portion (m ').
However, the phenomenon that the inner layer portion (n ′) is small is large, and the flame retardancy of the entire molded body (11) cannot be expected sufficiently.

As described above, a conventional method by a so-called post-hydration method is used in which a mixture of a thermoplastic resin and cement is molded into a desired shape, and the resulting molded body is treated as it is with water or an acidic aqueous solution and cured. Then, no matter what mixture composition and conditions are selected, it is difficult to homogenize the inner layer portion and the surface layer portion of the molded product, at least in terms of physical properties and flame retardancy. It takes a long time and is uneconomical. In particular, there is a limit to the homogenization of the inner layer portion and the surface layer portion in a thick molded product. On the other hand, with respect to the flame retardancy of this type of molded article, especially the material used for the interior of buildings, the regulations of JIS A 1321 are usually applied, and the evaluation is made based on the results. But,
The molded articles obtained by the above-mentioned conventional methods do not pass the above-specified flame retardant class 3 and have a low evaluation, and the flame retardancy is still insufficient.

As a result of further research on the basis of such a conventional situation, the present inventors formed a comparatively thin intermediate molded product in the production of this type of thermoplastic resin-containing cement molded product. Then, by hydrating this with an acidic aqueous solution to cure it once, and then heating and curing any number of cured intermediate moldings in a laminated form, the curing time can be shortened and the physical properties are uniform and flame retardant. It was found that a thermoplastic resin-containing cement molded product having sufficiently improved properties can be obtained, and the present invention was completed.

[0007]

That is, the present invention is based on the above-mentioned background and in principle utilizes a conventional method for producing a cement molded article containing a thermoplastic resin by a post-hydration method. At the same time, it is possible to cure an intermediate molded product composed of a thermoplastic resin and cement in a short time, has intermediate physical properties between the thermoplastic resin and cement, and has uniform and stable mechanical properties. It is an object of the present invention to provide a thermoplastic resin-containing cement molded product having excellent flame retardancy and a manufacturing method for obtaining the same.

[0008]

In the above object, the first invention of the present invention comprises a mixture of 100 parts by weight of a thermoplastic resin and 50 to 600 parts by weight of hydraulic cement,
A cement containing a thermoplastic resin, characterized in that a plurality of intermediate molded products, which are molded into a sheet and treated with an acidic aqueous solution to precipitate an inorganic reaction product in the cement layer, are laminated and integrated by heating. The main point is the molded body.

Further, a second invention of the present invention is to heat-knead a mixture of 100 parts by weight of a thermoplastic resin and 50 to 600 parts by weight of hydraulic cement to form a sheet-like intermediate molded product, and then form an acidic aqueous solution. The method of manufacturing a cement molded product containing a thermoplastic resin is characterized in that a plurality of the intermediate molded products are laminated on each other and integrated by heating.

That is, according to the present invention, an intermediate molded product obtained by heating and kneading a mixture of a thermoplastic resin and hydraulic cement to form a sheet is treated with an acidic aqueous solution and once hardened, and a cement layer is formed. The main points are to generate an inorganic reaction product and to heat and integrate the cured intermediate molded product in a laminated state.

Then, as shown in FIG. 1, conceptually, the thermoplastic resin-containing cement molded product (1) of the present invention is treated with an acidic aqueous solution to change the surface layer portion (m) to the inner layer portion (n). A plurality of sheet-like intermediate molded products (1a) (1b) (1c) ... In which the inorganic reaction product (C) is deeply formed are laminated and heated and integrated.

Next, the thermoplastic resin used in the present invention will be described. The thermoplastic resin is not particularly limited, and all kinds of thermoplastic resins can be applied. Further, the thermoplastic resins are not limited to the same type, and may be used as a mixture with different types. Furthermore, from the so-called synthetic resin waste material in which thermoplastic resin and thermosetting resin are mixed, thermosetting resin, metal, soil, sand, other dust, and foreign substances are roughly selected and removed, and the remaining thermoplastic resin-based synthesis is performed. It is applicable even if it is a resin waste material.

The main thermoplastic resins will be specifically listed below. Polyethylene, polypropylene, polyvinyl chloride, ethylene-vinyl acetate copolymer, acrylonitrile-butadiene-styrene copolymer, acrylonitrile-acrylic rubber-styrene copolymer. Coal, acrylonitrile-EPDM-styrene copolymer, acrylonitrile-chlorinated polyethylene-styrene copolymer, methylmethacrylate-butadiene-styrene copolymer, ethylene-vinyl chloride copolymer, polyvinylidene chloride, chlorinated polyolefin-butadiene copolymer Polymer, polyacetal,
Polyamide, polyethylene terephthalate, polycarbonate, polystyrene, polymethylmethacrylate, urethane thermoplastic elastomer, polybutylene terephthalate, polyphenylene ether, polyarylate, liquid crystal polymer, polytetrafluoroethylene, polyether ketone, polyether ether ketone, polyether sulfone, Examples thereof include styrene thermoplastic elastomer, olefin thermoplastic elastomer, polyester elastomer, polyamide elastomer, polybutadiene elastomer, vinyl chloride elastomer, and asphalt. Further, examples of the rubber type include natural rubber, styrene-butadiene rubber, butadiene rubber, isoprene rubber, chloroprene rubber, acrylonitrile-butadiene rubber, ethylene-propylene rubber, isobutylene-isoprene rubber and the like.

Further, the cement used in the present invention is mainly a hydraulic cement, for example, a normal hydraulic cement of Portland cement type such as Portland cement, blast furnace cement, fly ash cement, white cement, etc. It is a hydraulic cement such as high-strength cement, alumina cement, oxychloride cement, acid-resistant cement, gypsum and the like, and it is composed of two or more components and reacts with water to become hydraulic, for example, activated silica and water. Calcium oxide, activated alumina and calcium hydroxide are also applicable, and it is also possible to apply a mixture of two or more of the above cements.

In the present invention, the acidic aqueous solution used for curing the intermediate molded product is, for example, sulfuric acid or an appropriate amount of inorganic sulfate such as sodium sulfate, potassium sulfate, ammonium sulfate, ferric sulfate, and the like. An aqueous solution of sulfuric acid, an aqueous solution of oxalic acid obtained by dissolving an appropriate amount of an inorganic oxalate such as ammonium oxalate, and ferric oxalate in water, and the concentration thereof is not particularly limited, It shall be determined according to the type and amount of hydraulic cement to be used, the shape of intermediate molded product, the wall thickness, the conditions during hydration, and the degree of formation of reaction products.

Next, in the present invention, the mixing ratio of the thermoplastic resin and the hydraulic cement varies depending on the type of the thermoplastic resin, but the range is the thermoplastic resin 100.
The ratio of hydraulic cement is 50 to 600 parts by weight relative to parts by weight. In this case, if the amount of hydraulic cement exceeds 600 parts by weight, the intermediate molded article is heated and integrated because the absolute amount of the thermoplastic resin is small regardless of the degree of hydration by the acidic aqueous solution and the degree of reaction product formation. If the amount of the thermoplastic resin is less than 50 parts by weight, the absolute amount of the thermoplastic resin increases, which not only hinders the hydration of the hydraulic cement and the formation of the reaction product, but also the thermoplastic cement. You cannot get the desired performance. Therefore, preferably 1 part hydraulic cement to 100 parts by weight thermoplastic resin.
50 to 500 parts by weight.

In addition to the thermoplastic resin and the hydraulic cement, a glass fiber or a metal fiber for improving the brittleness of the desired molded article is added as a mixture for obtaining the intermediate molded article in the present invention. Alternatively, a foaming agent, a pigment, a light stabilizer, a heat stabilizer and the like can be added depending on the application. Then, the mixture is heated and kneaded to form a sheet-shaped intermediate molded product, treated with an acidic aqueous solution and once cured, and then laminated with a glass net or a metal net to form a heat-integrated product. It may be a desired molded body.

The method for producing a thermoplastic resin-containing cement compact according to the present invention will be described below.

First, as a means for mixing the thermoplastic resin and the hydraulic cement, a commonly used mortar mixer or blender is applied. In this case, in order to improve the mixing degree of the thermoplastic resin and the additives other than the hydraulic cement, the thermoplastic resin may be heated to a temperature below the melting temperature, preferably below the heat distortion temperature. Then, as a means for heat-molding the mixture to obtain a thin-layer intermediate molded product, the type of the thermoplastic resin to be used, the mixing ratio, the type and amount of the additive, and the like are expressed, and at the time of heat-molding the mixture. As long as it is a means suitable for thermal properties, all known means for thermoforming thermoplastic resins can be selected.In addition to the method using mixing rolls and calenders, extrusion molding method, injection molding method, compression method A molding method or the like can be applied. For example, the mixture is heated and kneaded with a mixing roll at a temperature equal to or higher than the melting temperature of the thermoplastic resin, and the mixture is rolled into a sheet to obtain an intermediate molded product. It is desirable to make the thickness of the intermediate molded product as thin as possible in order to shorten the curing time due to subsequent hydration, but it is naturally limited in terms of damage during handling, lamination work, etc. The lower limit is 0.1 to 0.3 mm.

Next, the sheet-like intermediate molded product obtained above is treated with an acidic aqueous solution for a certain period of time to cure. The treatment with the acidic aqueous solution is usually performed by immersing the intermediate molded product in the acidic aqueous solution. in this case,
Various conditions such as the type, concentration, treatment temperature, treatment time of the acidic aqueous solution are appropriately determined depending on the thermoplastic resin, the type of hydraulic cement, and the mixing ratio, but when the concentration of the acidic aqueous solution and the treatment temperature are too low. If the concentration of the acidic aqueous solution and the treating temperature are too high, the deterioration of the thermoplastic resin and the elution of the reaction product into the acidic aqueous solution occur. Not preferable. Therefore, for example, polyvinyl chloride resin as a thermoplastic resin,
In the case of treating an intermediate molded product using ordinary Portland cement as a hydraulic cement, when treating with an acidic aqueous solution of sulfuric acid and water, the concentration is 5 to 40%, and the treatment temperature is 20 to 60 ° C. Further, the intermediate molded product treated as described above is washed for the purpose of removing only the reaction product on the surface in order to prevent the lamination property from being hindered in the subsequent heating integration step, and the thermoplastic resin is deteriorated. It is heated to a temperature that does not dry it.

Further, the intermediate molded products which have been treated with the acidic aqueous solution, washed and dried in the above are laminated in an arbitrary number and integrated by heating. As a means for heating and unifying, generally known laminating means can be applied. For example, a method by compression molding or press molding is suitably applied, and heating and integration are performed at a temperature not lower than the melting temperature of the thermoplastic resin. . In this case, the heating temperature is essential to be a temperature equal to or higher than the melting temperature of the thermoplastic resin used as described above, and further set according to the type of each component of the mixture, the mixing ratio, the heat molding means, etc. The temperature can be changed. For example, when the thermoplastic resin is a vinyl chloride resin, the heat molding temperature with a press is set to a temperature in the range of 120 to 180 ° C.

The thickness of the molded body obtained above is not particularly limited, and the thickness can be selected large as long as it does not hinder the operation of heating and unifying, and it can be molded not only in the plate shape but also in the block shape. It is possible to

As described above, the thermoplastic resin-containing cement molded product according to the present invention is a sheet obtained by molding the mixture of the thermoplastic resin and hydraulic cement by heating and kneading the intermediate molded product constituting the cement molded product. Since the inorganic reaction product is deposited on the cement layer by treating the shaped article with an acidic aqueous solution, it has flame retardancy per se, and a plurality of intermediate shaped articles having this flame retardancy are also present. Since the cement molded body containing a thermoplastic resin is formed by heating and integrating the sheets in a laminated form, not only the physical properties are uniform, but also the entire molded body is flame retarded.

[0024]

EXAMPLES Examples of the present invention will be described below together with comparative examples.

The dimensional specifications of the cement molded product containing the thermoplastic resin in the examples are as follows: area 30 cm × 30 c
m and thickness 15 mm.

The evaluation items of the cement molded articles containing the thermoplastic resin obtained in Examples and Comparative Examples are flame retardancy test, lamination property and bending strength, and the test method and evaluation criteria are as follows. The results obtained are summarized in Table 1.

Flame resistance test: JIS A1321, flame resistance 3
Same as class surface test. Criteria for evaluation: Deformation-Presence or absence of significant deformation (No: ○, Yes: ×) Gas-Presence or absence of toxic gas generation (No: ○, Yes: ×) Turtle crack-With a width of 1/10 or more of the total thickness Presence / absence of cracks (No: ○, Yes: X) Melting-Presence of melting over the entire thickness (No: ○, Yes: ×) Afterflame-Presence of afterflame for 30 seconds or more after heating (No: Yes, Yes: ×) exhaust temperature -350 (° C. × min) standard (hereinafter: ○, ultra: ×) fuming coefficient (C _a) -120 reference (hereinafter: ○, ultra: ×) determination of acceptance: evaluation all ○ The case is passed, and the others are rejected. Stackability: According to JIS K6745. However, it was immersed in liquid paraffin at a test temperature of 150 ° C. and a time of 5 minutes. Judgment of Pass / Fail: Those without peeling of layers were judged as pass (◯), and those with peeling of layers were judged as fail (x). Bending strength test: According to JIS K7203.

Example 1 100 parts by weight of polyvinyl chloride resin (degree of polymerization 700),
Ordinary Portland cement 300 parts by weight, tin stabilizer 2
Parts by weight were put into a mixer and mixed by stirring. This mixture was heated and kneaded with a mixing roll at 170 ° C. for 10 minutes and rolled to obtain a sheet-shaped intermediate molded product having a thickness of 0.5 mm.

Then, an acidic aqueous solution containing 20% by volume of sulfuric acid was prepared, and the above-mentioned intermediate molded product was immersed in this for 7 days. In the intermediate molded product after completion of the immersion, the surface layer portion having a thickness of 100 μm was discolored to white, and the portion was analyzed by an X-ray diffraction apparatus. As a result, formation of calcium sulfate was confirmed. Further, the surface of this intermediate molded product was washed and then dried in an oven at 60 ° C. for 2 days.

Next, 30 sheets of the sheet-shaped intermediate molded product obtained above were laminated, and this was molded at a temperature of 1 by a compression molding machine.
Compression molding at 70 ° C. and a pressure of 20 kg / cm ² for 20 minutes,
A molded body having a thickness of 15 mm was obtained.

The obtained molded product was evaluated for each of the evaluation items described above, and the results are shown in Table 1. The sample passed the flame-retardant class 3 of the flame-retardant test, and was sufficiently practical for bending strength.

Example 2 Pelletized low density polyethylene (concentration 0.91) 10
To 0 parts by weight, 550 parts by weight of ordinary Portland cement was put into a mixer and mixed by stirring. This mixture was heated and kneaded at 140 ° C. for 10 minutes with a mixing roll and rolled to obtain a sheet-shaped intermediate molded product having a thickness of 0.5 mm.

Then, in the same manner as in Example 1, sulfuric acid 20
A volume% acidic aqueous solution was prepared, and the above-mentioned intermediate molded product was immersed in this for 7 days. After the completion of the immersion, the intermediate molded product had a surface layer portion having a thickness of 125 μm which turned white due to the formation of calcium sulfate as in Example 1. Further, the surface of this intermediate molded product was washed and then dried in an oven at 60 ° C. for 2 days.

Next, 30 sheets of the sheet-shaped intermediate molded product obtained above were laminated, and this was laminated at a temperature of 1 by a compression molding machine.
Compression molding at 50 ° C. and a pressure of 15 kg / cm ² for 20 minutes,
A molded body having a thickness of 15 mm was obtained.

The molded body thus obtained was evaluated in the same manner as in Example 1, and the results are shown in Table 1. The sample passed the flame-retardant class 3 of the flame-retardant test, and was sufficiently practical for bending strength.

Example 3 80 parts by weight of polyvinyl chloride resin (degree of polymerization 700) and 20 parts by weight of chlorinated vinyl chloride resin (degree of chlorination 68%), 200 parts by weight of alumina cement, 2.5 parts by weight of tin stabilizer. Parts were put into a mixer and mixed by stirring. This mixture was heated and kneaded with a mixing roll at 170 ° C. for 10 minutes and rolled to obtain a sheet-shaped intermediate molded product having a thickness of 0.5 mm.

Then, in the same manner as in Example 1, sulfuric acid 20
A volume% acidic aqueous solution was prepared, and the above-mentioned intermediate molded product was immersed in this for 7 days. After the completion of the immersion, the intermediate molded product had a surface layer portion having a thickness of 90 μm that turned white due to the formation of calcium sulfate as in Example 1. Further, the surface of this intermediate molded product was washed and then dried in an oven at 60 ° C. for 2 days.

Next, 30 sheets of the sheet-shaped intermediate molded product obtained as described above were laminated, and this was molded by a compression molding machine at a temperature of 1
Compression molding at 70 ° C. and a pressure of 20 kg / cm ² for 20 minutes,
A molded body having a thickness of 15 mm was obtained.

The obtained molded product was evaluated for each of the above evaluation items, and the results are shown in Table 1. The sample passed the flame-retardant class 3 of the flame-retardant test, and was sufficiently practical for bending strength.

Comparative Example 1 Except for adding 40 parts by weight of the ordinary Portland cement in Example 1, exactly the same as in Example 1,
A laminate having a thickness of 15 mm was obtained. The results, as also shown in Table 1, were those that failed the flame retardancy class 3 of the flame retardancy test.

Comparative Example 2 A laminate having a thickness of 15 mm was obtained in exactly the same manner as in Example 1 except that the amount of ordinary Portland cement added in Example 1 was 650 parts by weight. As shown in Table 1, the result was that it passed the flame-retardant class 3 of the flame-retardant test, but the stackability was unsuccessful.

Comparative Example 3 In Example 1, 30 sheets of the intermediate molded product having a thickness of 0.5 mm obtained with the mixing roll were laminated as they were,
Compression molding was performed under the same conditions as in Example 1 to obtain a laminate having a thickness of 15 mm.

The laminate obtained above was immersed in the same acidic aqueous solution as used in Example 1 for 7 days. After the completion of the dipping, the layer having a thickness of 100 μm in the surface layer changed its color to white due to the formation of calcium sulfate, but the inner layer had no similar color change due to calcium sulfate.

The obtained laminate was evaluated in the same manner as the molded product of Example 1, and the results are shown in Table 1. The sample failed the flame retardancy class 3 of the flame retardancy test, and the bending strength was lower than that of any of the molded products of Examples 1 to 3.

Comparative Example 4 In Example 1, 30 sheets of the intermediate molded product having a thickness of 0.5 mm obtained with the mixing roll were laminated as they were,
Compression molding was performed under the same conditions as in Example 1 to obtain a laminate having a thickness of 15 mm.

The laminate obtained above was immersed in water for 7 days. The above-mentioned laminate after the completion of the immersion is about 1.5 from the surface layer.
Up to mm, the whitening phenomenon of calcium hydroxide was caused by hydration, but the inside was not changed and the hydration was incomplete.

The resulting laminate was evaluated in the same manner as the molded product of Example 1, and the results are shown in Table 1. The sample failed the flame-retardant grade 3 of the flame-retardant test and had a bending strength lower than that of any of the molded products of Examples 1 to 3.

[0048]

[Table 1]

[0049]

Industrial Applicability As described above, the thermoplastic resin-containing cement molded product according to the present invention comprises a mixture of a thermoplastic resin and hydraulic cement, is molded into a sheet and is treated with an acidic aqueous solution to form a cement layer. Since a plurality of intermediate molded products in which the inorganic reaction product has been deposited are heated and integrated in a laminated form, they have intermediate physical properties between the thermoplastic resin and cement, and their physical properties are uniform. In addition, since the inorganic reaction product of the cement layer is present even in the inner layer portion of the molded body, flame retardancy is enhanced. Further, the production of a thermoplastic resin-containing cement molded body of the present invention, using a mixture of a thermoplastic resin and hydraulic cement is kneaded by heating to form a sheet, then using an intermediate molded product treated with an acidic aqueous solution. By adopting the means of heat-integrating in a laminated form, the inorganic reaction product can easily be present in the cement layer of the inner layer portion of the molded body, and the molded body is not affected by the thickness of the molded body. There is an effect that flame retardancy can be imparted to the.

[Brief description of drawings]

FIG. 1 is a sectional view showing a cement molded product containing a thermoplastic resin according to the present invention.

FIG. 2 is a cross-sectional view showing a conventional cemented product containing a thermoplastic resin.

[Explanation of symbols]

 1 ... Cement molding containing thermoplastic resin 1a, 1b, 1c ... Intermediate molding C ... Inorganic reaction product

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akimasa Masunaga 33-66, Fukui City, Fukui Prefecture 33 Fukubi Chemical Industry Co., Ltd. (72) Inventor Kiyoshi Akita Thirty-eight companies town, Fukui City 33 characters 66 Fukubi Chemical Industry Co., Ltd.

Claims (3)

[Claims] 1. An intermediate product comprising a mixture of 100 parts by weight of a thermoplastic resin and 50 to 600 parts by weight of hydraulic cement, molded into a sheet and treated with an acidic aqueous solution to deposit an inorganic reaction product on a cement layer. A cement molded product containing a thermoplastic resin, wherein a plurality of molded products are laminated and integrally heated. 2. A mixture of 100 parts by weight of a thermoplastic resin and 50 to 600 parts by weight of hydraulic cement is kneaded by heating to form a sheet-like intermediate molded product, which is then treated with an acidic aqueous solution, and then the intermediate molded product. 2. A method for producing a cement molded product containing a thermoplastic resin, which comprises laminating a plurality of the sheets with each other and integrally heating them. 3. The method for producing a cement molded product containing a thermoplastic resin according to claim 2, wherein the surface of the intermediate molded product treated with the acidic aqueous solution is washed with water and the subsequent step is continued.