JP2017154929A - Polyurethane-based cement composition and concrete floor construction method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyurethane-based cement composition high in glossiness of a cured coated film and high in coated film hardness and a concrete floor construction method thereof.SOLUTION: There are provided a polyurethane-based cement composition containing a water dispersion polyol, polyisocyanate, a diluent, cement and a filler and having a paste shape for applying to thickness of 0.2 mm or more and less than 2.5 mm, the water dispersion polyol consists of castor oil modified polyol and bis (2-butoxyethyl) phthalate, an emulsifier and water, the diluent contains glycol benzoate ester, hydroxyl group equivalent of the water dispersion polyol is 200 to 250 and polyisocyanate has viscosity of 250 to 400 mPa s/23°C and NCO equivalent of 130 to 140 and a concrete floor construction method thereof.SELECTED DRAWING: None

Description

  The present invention comprises a paste-like polyurethane cement comprising a water-dispersed polyol, a polyisocyanate, a diluent, a cement and a filler, and is applied to a floor foundation concrete surface to a thickness of 0.2 mm or more and less than 2.5 mm. The present invention relates to a composition and a concrete floor construction method thereof.

  Conventionally, as a cement composition that easily becomes a uniform mixture and is easy to construct, (a) hydraulic cement, (b) water, (c) cement water reducing agent, and (d) a component that can be cured to become a resin. A cement composition is proposed (Patent Document 1). In addition, as a polyurethane-based cement composition capable of ensuring excellent workability and obtaining a floor surface having an excellent appearance after curing, (a) hydraulic cement, (b) aggregate, (c) isocyanate group A polyurethane-based cement composition comprising, as essential components, a compound comprising: (d) water, (e) a tertiary amine compound catalyst, and (f) an active hydrogen-containing compound (excluding water and a tertiary amine compound catalyst). It has been proposed (Patent Document 2). In addition, by using an isocyanate component containing a specific isocyanate group-terminated prepolymer, a heat-resistant polymer cement composition that does not warp even when cured and contracted without impairing workability, cured coating film appearance, and coating film properties. Hydrophobic polyol selected from polybutadiene-based polyol and hydrogenated polybutadiene-based polyol, which is a polymer cement composition containing hydraulic cement, water, polyol (a), isocyanate compound, and aggregate as essential components A polymer cement composition characterized by containing an isocyanate group-terminated prepolymer obtained by reacting (b) with a diisocyanate compound has been proposed (Patent Document 3).

Moreover, as a polyurethane-based cement composition that retains heat resistance and physical properties and does not impair coating workability and surface appearance, and does not generate warping or cracks on the surface layer even when the coating thickness is 5 mm or less, or shrinks by curing, This composition is composed of a polyol containing at least a water-dispersible polyol, a hydrophobic isocyanate which is polyphenylene polymethyl polyisocyanate, and an aggregate containing hydraulic cement, and is cured on a substrate made of concrete with a coating thickness of 4 mm. The thickness is 4 mm, and curing water at 95 ° C. for 5 minutes and 20 ° C. for 10 minutes is taken as one cycle, and the shrinkage stress after 2000 cycles is 4.0 ± 2.0 N / mm ² and warps after 1300 cycles. A polyurethane-based cement composition has been proposed which is characterized in that no rise or cracks in the surface layer occur. Document 4).

  Further, as a polyurethane cement composition having a glossiness of 5.0 or more and having high stain resistance, that is, high decontamination property, a coating floor material using a polyurethane cement containing hydraulic cement, water, polyol, aggregate, and isocyanate compound. In which the 60 ° specular gloss after curing is 5.0 or more and 90 or less, the polyol is water-dispersible, the isocyanate compound is polymeric MDI, and 2,4′-MDI of this polymeric MDI. A polyurethane-based cement composition having a content of 6% or less and an NCO weight% of 25% or less has been proposed (Patent Document 5, Claim 2).

  Further, as a polyurethane-based cement composition having high gloss, a polyurethane-based cement composition containing hydraulic cement, water, a polyol, and an isocyanate compound, wherein the water ratio of water and polyol to the polyol composition is 40 to 10% by weight. A polyurethane-based cement composition characterized in that an emulsion is formed and urea is contained (Patent Document 6).

JP-A-8-169744 JP 11-79820 A JP 2000-72507 A Japanese Patent No. 4480964 JP 2007-254179 A Japanese Patent No. 5389399

  However, the compositions shown in Patent Document 1 to Patent Document 3 have an aggregate particle size of about 3.0 mm shown in the examples (the particle size of silica sand No. 2 in paragraph 0054 of Patent Document 1). In addition, the obtained composition is supposed to extend to a thickness of 5 mm (Patent Document 2, paragraph 0047), and the coating thickness is preferably 3 to 20 mm, and particularly preferably 4 to 7 mm (Patent Document 3, paragraph 0027). ), At least these compositions have a problem that the coating thickness is 3.0 mm or more.

  Further, the polyurethane cement composition of Patent Document 4 is cured at a thickness of 4 mm (Patent Document 4, Claim 1 and Paragraph 0030), and the polyurethane cement composition of Patent Document 5 is similarly cured at a thickness of 4 mm. (Patent Document 5, paragraph 0028), the glossiness is high and only 81.5 is shown. Further, the NCO wt% of the isocyanate compound used in the composition is 25 wt% or less. There is a problem that the JIS K 7215 Type D durometer hardness of the coating film may be less than 80 (Table 1 in the same paragraph). Similarly, the polyurethane-based cement composition of Patent Document 6 is hardened at a thickness of 4 mm (Patent Document 6, paragraph 0026) and has a problem that its glossiness is high and 56.0.

  The problem to be solved by the present invention is a polyurethane-based cement composition comprising a water-dispersed polyol, a polyisocyanate, a diluent, a cement and a filler, and has a thickness of 0.2 mm or more and less than 2.5 mm A polyurethane-based cement composition in which the specular gloss of a 5 ° C cured coating film is 85 or more and the type D durometer hardness of a 23 ° C cured coating film is 80 or more, and a concrete floor construction method thereof It is to provide.

  The invention according to claim 1 is a paste-like polyurethane cement comprising a water-dispersed polyol, a polyisocyanate, a diluent, a cement and a filler, and is applied to a thickness of 0.2 mm or more and less than 2.5 mm. The composition is a water-dispersed polyol comprising a castor oil-modified bifunctional polyol, a castor oil-modified trifunctional polyol, bis (2-butoxyethyl) phthalate, an emulsifier and water, and the diluent includes a benzoic acid glycol ester. The hydroxyl group equivalent of the water-dispersed polyol is 200 to 250, the polyisocyanate has a viscosity of 250 to 400 mPa · s / 23 ° C., an NCO equivalent of 130 to 140, and is cured at 5 ° C. with a thickness of 1.5 mm or more and less than 2.5 mm. JIS K 5600-4-7 60 degree specular gloss of paint film is 85 or more, thickness is 1.5mm or more and less than 2.5mm Providing a polyurethane cement composition characterized by JIS K 7215 Type D durometer hardness of 23 ° C. cured coating film is 80 or more.

  The invention according to claim 2 provides the polyurethane-based cement composition according to claim 1, wherein the polyisocyanate is polymethyl polyphenyl polyisocyanate.

  The invention according to claim 3 is a method in which the polyurethane cement composition according to claim 1 or 2 is applied as an undercoat to the floor concrete surface and cured to a thickness of 0.2 mm or more and less than 0.6 mm. Furthermore, the present invention provides a concrete floor construction method characterized in that the polyurethane-based cement composition is applied as a top coat to a thickness of 1.5 mm or more and less than 2.5 mm.

  Since the polyurethane-based cement composition of the present invention is paste-like and has a low viscosity, it has an effect that it can be applied to the surface of the floor foundation concrete to a thickness of 0.2 mm or more and less than 2.5 mm using a metal hammer or the like. Further, the JIS K 5600-4-7 60 ° specular gloss of a 5 ° C. cured film having a thickness of 1.5 mm or more and less than 2.5 mm is 85 or more, and a 23 ° C. coating having a thickness of 1.5 mm or more and less than 2.5 mm. Since the film has a JIS K 7215 Type D durometer hardness of 80 or more, there is an effect that the surface of the coating film cured at a low temperature is particularly excellent, and the coating film surface layer has more resin than other parts. As a result, the floor structure finished with the polyurethane-based cement composition is hard to get dirty on the surface of the coating, and the coating does not crack or peel off even when heavy objects are placed or passed There is an effect that.

  In addition, the polyisocyanate has a viscosity of 250 to 400 mPa · s / 23 ° C. and an NCO equivalent of 130 to 140, and since the diluent contains benzoic acid glycol ester, it can be applied at a low temperature of about 5 ° C. in winter. There is an effect that the surface of the coating film is smooth and excellent.

  Moreover, the concrete floor construction method of the polyurethane-based cement composition of the present invention, after first applying the polyurethane-based cement composition of the present invention to a thickness of 0.2 mm or more and less than 0.6 mm as an undercoat and curing, Furthermore, since the polyurethane cement composition is applied as a top coat to a thickness of 1.5 mm or more and less than 2.5 mm, fine pores on the surface of the floor foundation concrete (pores resulting from the microstructure of the concrete) are used as a primer. It is hardened while being filled with the polyurethane cement composition. For this reason, in general, when the top coat is applied directly to the floor concrete surface, the top coat penetrates the base concrete surface and expels air in the fine pores of the base concrete surface. There is an effect that there is no generation of bubbles and pinholes, and there is an effect that the surface of the coating film formed with the polyurethane-based cement composition of the present invention is excellent in aesthetic appearance.

  The present invention will be described in detail below.

  The polyurethane-based cement composition of the present invention contains a water-dispersed polyol, a polyisocyanate, a diluent, a cement and a filler, and is a paste-like polyurethane that is applied to a thickness of 0.2 mm or more and less than 2.5 mm. A cement composition, wherein the water-dispersed polyol comprises a castor oil-modified bifunctional polyol, a castor oil-modified trifunctional polyol, bis (2-butoxyethyl) phthalate, an emulsifier, and water, and the diluent is a benzoic acid glycol ester The water-dispersed polyol has a hydroxyl group equivalent of 200 to 250, the polyisocyanate has a viscosity of 250 to 400 mPa · s / 23 ° C., an NCO equivalent of 130 to 140, and a thickness of 1.5 mm or more and less than 2.5 mm. JIS K 5600-4--7 60 degree specular gloss of cured film at 85 ° C. is 85 or more, thickness 1.5 mm It is a polyurethane-based cement composition having a JIS K 7215 type D durometer hardness of not less than 2.5 mm and a cured coating film of 23 ° C. of 80 or more. Additives such as agents and antifoaming agents can be blended.

  The water-dispersed polyol used in the polyurethane-based cement composition of the present invention comprises castor oil-modified bifunctional polyol, castor oil-modified trifunctional polyol, bis (2-butoxyethyl) phthalate, an emulsifier, and water. The hydroxyl equivalent of the polyol is 200-250. If the hydroxyl equivalent is less than 200, the cured product may shrink and peel from the base, and if it exceeds 250, the coating film hardness will be insufficient. Castor oil-modified bifunctional polyol or castor oil-modified trifunctional polyol is castor oil and its derivatives, for example, diglyceride, monoglyceride of castor oil fatty acid, and mixtures thereof, and is a polyol having 2 or 3 hydroxyl groups.

  The water-dispersed polyol used in the present invention is obtained by emulsifying and dispersing castor oil-modified bifunctional polyol and castor oil-modified trifunctional polyol in water with an emulsifier, and then adding bis (2-butoxyethyl) phthalate to add a hydroxyl equivalent weight. 200 to 250, and then mixing with a diluent containing a benzoic acid glycol ester, a polyisocyanate, cement and a filler, a polyurethane cement composition according to the present invention that has not yet hardened is obtained. In the present invention, this is applied to a thickness of 1.5 mm or more and less than 2.5 mm and cured. In particular, the JIS K 5600-4-7 60 ° specular gloss of the coating film when cured at 5 ° C. is 85 or more. It is a polyurethane-based cement composition having a JIS K 7215 Type D durometer hardness of 80 or more when cured at 0 ° C. If the 60 ° specular gloss is 85 or more, the coating film surface is glossy. If the Type D durometer hardness is 80 or more, the polyurethane cement composition has durability against the load applied to the coating film.

  As the emulsifier used in the water-dispersed polyol, any of synthetic surfactants, resinate surfactants, and protein surfactants can be used. The types of surfactants are anionic surfactants and cationic surfactants. Surfactants, nonionic surfactants, and amphoteric surfactants can be used alone or in combination.

  The content of bis (2-butoxyethyl) phthalate in the water-dispersed polyol is 30 to 50% by weight, and if it is less than 30% by weight, the workability when applied as a polyurethane cement composition to the ground becomes poor. If it exceeds% by weight, the hardness of the cured coating film is insufficient. In addition, the water content of the water-dispersed polyol is 30 to 40% by weight, and if it is less than 30% by weight, the workability when applied to the base as a polyurethane-based cement composition may be poor, and it exceeds 40% by weight. Then, the finish of the cured coating film of the polyurethane cement composition may be poor. In addition to these, a colorant can also be added to the water-dispersed polyol.

  The diluent used in the present invention improves the coating workability and the smoothness of the coating surface when the polyurethane-based cement composition of the present invention is applied and cured at a low temperature of about 5 ° C. in winter. Use for. The diluent is preferably a benzoic acid glycol ester. The benzoic acid glycol ester is a condensed ester compound of benzoic acid and a glycol compound, and diethylene glycol, dipropylene glycol or the like can be used as the glycol compound. As a commercially available benzoic acid glycol ester, there is benzoic acid glycol ester JP120 (trade name, manufactured by J-Plus Co., Ltd.), which is a mixture of diethylene glycol dibenzoate and dipropylene glycol dibenzoate.

  The blending amount of the diluent is preferably 2 to 5 parts by weight in a total of 100 parts by weight of the water-dispersed polyol, polyisocyanate, and diluent, and if less than 2 parts by weight, the coating workability and the smoothness of the coating film surface are preferred. When the content exceeds 5 parts by weight, the JIS K 7215 Type D durometer hardness of the cured coating film at 23 ° C. decreases.

  The polyisocyanate used in the polyurethane-based cement composition of the present invention has good workability, fast curing at low temperature, and high hardness of the coating film after curing. The NCO equivalent is preferably 100 to 150. When the NCO equivalent is less than 100, the finish of the cured coating film is poor, and when the NCO equivalent exceeds 150, the coating film hardness is insufficient. Further, the viscosity of the polyisocyanate is preferably 250 to 400 mPa · s / 23 ° C. If the viscosity is less than 250 mPa · s / 23 ° C., the hardness of the cured coating film may be insufficient, and if it exceeds 400 mPa · s / 23 ° C., 5 The coating workability and the smoothness of the coating film surface at the time of applying and curing at a low temperature of about ℃ are poor. If the viscosity is 250 to 400 mPa · s / 23 ° C. and the NCO equivalent is 130 to 140, the thickness of other aliphatic polyisocyanates, aromatic polyisocyanates, alicyclic polyisocyanates, etc. is 1.5 mm or more. If the 60 ° specular gloss of a 5 ° C cured coating of less than 5 mm is 85 or more and the type D durometer hardness of the 23 ° C cured coating is 80 or more, it can be used. The viscosity said here is a viscosity at 60 rpm in rotor No. 3 with a BM viscometer.

  In addition, the number of isocyanate groups of the polyisocyanate with respect to one hydroxyl group of the water-dispersed polyol used in the present invention is preferably 1.5 to 2.5. Fine foaming due to carbon dioxide gas may occur in the cured coating film.

  The cement used in the polyurethane-based cement composition of the present invention is intended to impart an aesthetic appearance by applying the polyurethane-based cement composition of the present invention to floor foundation concrete, so that a specific color tone can be imparted mainly. It is preferred to use white Portland cement. In addition, ordinary Portland cement, alumina cement, blast furnace cement, and early-strength Portland cement can be used in combination. The blending amount of cement is 5 to 20 parts by weight in 100 parts by weight of the whole composition. If the amount is less than 5 parts by weight, the surface finish of the coating film is poor, and if it exceeds 20 parts by weight, the workability when applied to the base is poor.

The filler used in the polyurethane cement composition of the present invention is preferably cinnabar sand in order to improve the coating workability at a low temperature of about 5 ° C., and in particular, the polyurethane system according to the present invention as a particle size. When it is applied as a composition with a thickness of 1.5 mm, it may be of such a size that the filler particles do not appear as irregularities on the surface of the coating film, and the average particle diameter D ₅₀ by 50% weight integration is 100. ˜500 μm is preferred. The average particle diameter D ₅₀ workability becomes poor at the time of applying to the substrate as a polyurethane-based cement composition is less than 100 [mu] m, the average particle diameter D ₅₀ is 500μm greater than the coating when subjected coated in a thickness of 1.5mm In some cases, the film surface is uneven, or minute protrusions due to the filler are generated to make the film surface non-smooth and to reduce gloss. As a commercially available filler that satisfies these conditions, there is Tohoku cinnabar No. 6 (trade name, manufactured by Tohoku cinnabar Co., Ltd., average particle diameter D ₅₀ : about 340 μm).

  The blending amount of the filler is 25 to 45 parts by weight in 100 parts by weight of the whole composition, and particularly when the polyurethane-based cement composition of the present invention is applied as a primer to a thickness of 0.2 mm or more and less than 0.6 mm. Is preferably 25 to 40 parts by weight, and when the polyurethane cement composition of the present invention is applied as a top coat to a thickness of 1.5 mm or more and less than 2.5 mm, it is preferably 35 to 45 parts by weight. When applying as an undercoat, if the filler is less than 25 parts by weight, the filling of fine holes on the surface of the underlying concrete is insufficient, and if it exceeds 40 parts by weight, the coating workability is poor. When applying as a top coat, if the filler is less than 35 parts by weight, the viscosity of the composition is too low and the coating workability when applied with a hammer is poor, and if it exceeds 45 parts by weight, the smoothness of the cured coating film Is insufficient.

  In addition to the above, slaked lime is preferably added to the polyurethane cement composition of the present invention. The slaked lime absorbs carbon dioxide gas generated by the urea reaction between polyisocyanate and water, and the carbon dioxide gas generated until the composition is applied on the floor foundation concrete and hardens, concentrates on a specific part, resulting in a coating film. This has the effect of suppressing the occurrence of swelling by pushing up the. As a compounding quantity of slaked lime, 1-5 weight part is preferable with respect to 100 weight part of the whole composition. If the amount is less than 1 part by weight, the above effect may be insufficient, and if it exceeds 5 parts by weight, the coating workability may be insufficient.

  When applying the polyurethane-based cement composition of the present invention to floor foundation concrete, first, a brittle layer such as latency on the floor foundation concrete surface is removed by polishing or the like. Next, the paste-like polyurethane cement composition of the present invention is applied as an undercoat to a thickness of 0.2 mm or more and less than 0.6 mm and cured, and then the paste-like polyurethane cement composition of the present invention is overcoated. As a result, it is applied to a thickness of 1.5 mm or more and less than 2.5 mm. The coating is preferably performed using a metal hammer or the like, and the coating thickness after curing is approximately 1.7 mm to 3.1 mm.

  Hereinafter, it demonstrates concretely in an Example and a comparative example.

<Example>
A mixture of castor oil-modified bifunctional polyol and castor oil-modified trifunctional polyol is composed of 20% by weight, 40% by weight of bis (2-butoxyethyl) phthalate, 38% by weight of water, and 2% by weight of an emulsifier. Add 85 parts by weight of water-dispersed polyol A to 7 parts by weight of colored toner (pigment concentration: 80% by weight) and 8 parts by weight of JP120 (trade name, manufactured by J-Plus Co., Ltd.) as a diluent to make 100 parts by weight of the base. Using polymethylpolyphenyl polyisocyanate having an NCO equivalent of 135 and a viscosity of 300 mPa · s / 23 ° C. (BM type viscometer, rotor No. 3, 60 rpm) as the isocyanate to 100 parts by weight of a curing agent, 30% by weight of commercially available white cement Tohoku cinnabar No. 6 is made into 200 parts by weight of a powder part in which 65% by weight and 5% by weight of slaked lime are uniformly mixed. Part, 100 parts by weight of the curing agent and 200 parts by weight of the powder part are uniformly mixed to form an undercoat of the polyurethane cement composition of the example, and 100 parts by weight of the main agent, 100 parts by weight of the curing agent and 275 parts by weight of the powder part. Were uniformly mixed to form a top coat of the polyurethane cement composition of the example.

<Comparative Example 1>
Instead of the main agent used in the examples, a mixture of castor oil-modified bifunctional polyol and castor oil-modified trifunctional polyol was 20% by weight, bis (2-butoxyethyl) phthalate 40% by weight, water 38% by weight, and emulsifier 2. 90 parts by weight of water-dispersed polyol A having a hydroxyl equivalent weight of 225, 7 parts by weight of colored toner (pigment concentration: 80% by weight) and 3 parts by weight of JP120 (trade name, manufactured by J-Plus Co., Ltd.) as a diluent Is added to make 100 parts by weight of the main agent, and polyisocyanate having an NCO equivalent of 135 and a viscosity of 600 mPa · s / 23 ° C. (BM type viscometer rotor No. 3, 60 rpm) is used as the polyisocyanate. A powder in which 30% by weight of commercial white cement, 65% by weight of Tohoku cinnabar No. 6 and 5% by weight of slaked lime are uniformly mixed. 200 parts by weight, 100 parts by weight of the main agent, 100 parts by weight of the curing agent, and 200 parts by weight of the powder part are uniformly mixed to form an undercoat of the polyurethane-based cement composition of Comparative Example 1, and 100 parts by weight of the main agent and the curing agent 100 Part by weight and 275 parts by weight of the powder part were mixed uniformly to form an overcoat of the polyurethane cement composition of Comparative Example 1.

<Comparative example 2>
In place of the polyisocyanate used in the examples, an NCO equivalent of 135 and a viscosity of 600 mPa · s / 23 ° C. (BM type viscometer rotor No. 3 60 rpm) polymethylphenyl polyisocyanate was used to make the curing agent 100 parts by weight, 100 parts by weight of the main agent and 100 parts by weight of the powder are the same as in the examples, and 100 parts by weight of the main agent, 100 parts by weight of the curing agent, and 200 parts by weight of the powder part are uniformly mixed to undercoat the polyurethane cement composition of Comparative Example 2. Then, 100 parts by weight of the main agent, 100 parts by weight of the curing agent, and 275 parts by weight of the powder part were uniformly mixed to form an overcoat of the polyurethane cement composition of Comparative Example 2 Example.

<Evaluation items and evaluation methods>

<Compressive strength>
According to JIS K 6911 5.19 compressive strength, the top coats of the polyurethane cement compositions of Examples, Comparative Examples 1 and 2 were cured in a shape of 25.4 × 12.7 × 12.7 mm. Compressed at a loading speed of 1 mm / min after curing at 23 ° C. for 7 days, and measured the compressive strength (N / mm ² ).

<Adhesiveness>
Example, Comparative Example 1 and Comparative Example, which were uniformly mixed on the surface of a dried concrete flat plate of 300 mm x 300 mm x 60 mm thick (5% or less in a ket moisture meter HI-520 concrete range) of JISA 5371 at 23 ° C The polyurethane-based cement composition of Example and Comparative Example in which the undercoat of the polyurethane-based cement composition of Example 2 was applied with a gold trowel so as to have a thickness of 0.4 mm, cured for 24 hours, and then uniformly mixed. The top coat was applied with a gold trowel to a thickness of 1.6 mm, cured for 24 hours, and then cured for 7 days. Thereafter, the adhesion strength (N / mm ² ) between the 40 × 40 mm portion of the water-based polyurethane composition and the concrete flat plate was measured with a Kenken-type adhesive strength tester. As for the fracture state, 100% cohesive fracture of the ground concrete was evaluated as “good”, and the others were evaluated as “poor”.

<Specular gloss>
The undercoat of Example, Comparative Example 1 and Comparative Example 2 was applied to a fiber reinforced cement board of 0.4 mm thickness under 5 ° C. to a thickness of 0.4 mm. Each of the top coats of Comparative Example 2 was applied to a thickness of 1.6 mm and cured, and after curing for 24 hours, the 60-degree specular gloss specified in JISK 5600-4-7 was measured.

<Coating hardness>
About the hardened | cured material of the polyurethane-type cement composition of the Example before a measurement of the said compressive strength under 23 degreeC, the comparative example 1, and the comparative example 2, the type D durometer hardness prescribed | regulated to JISK7215 was measured.

<Surface property>
After applying the undercoat of Example, Comparative Example 1 and Comparative Example 2 to a thickness of 0.4 mm on a fiber reinforced cement board of JISA 5430 having a thickness of 20 cm × 20 cm × 0.4 mm at 5 ° C. and 23 ° C., respectively, The top coats of Examples, Comparative Examples 1 and 2 were each applied to a thickness of 1.6 mm and cured, and after curing for 24 hours, the state of the coating film surface was visually observed. A smooth sample was shown as “◯”, and a non-smooth sample with waviness on the coating film surface was shown as “X”.

<Evaluation results>
The evaluation results are shown in Table 1.

Claims (3)

  A paste-like polyurethane cement composition comprising a water-dispersed polyol, a polyisocyanate, a diluent, a cement and a filler, and applied to a thickness of 0.2 mm or more and less than 2.5 mm. The polyol is composed of castor oil-modified bifunctional polyol, castor oil-modified trifunctional polyol, bis (2-butoxyethyl) phthalate, emulsifier and water, the diluent contains benzoic acid glycol ester, and the hydroxyl equivalent of the water-dispersed polyol is Polyisocyanate has a viscosity of 250 to 400 mPa · s / 23 ° C., an NCO equivalent of 130 to 140, and a JIS K 5600-4 of a 5 ° C. cured coating film having a thickness of 1.5 mm or more and less than 2.5 mm. -7 JI of a 23 ° C. cured coating film having a 60 ° specular gloss of 85 or more and a thickness of 1.5 mm or more and less than 2.5 mm Polyurethane cement composition K 7215 Type D durometer hardness is equal to or less than 80.   2. The polyurethane cement composition according to claim 1, wherein the polyisocyanate is polymethyl polyphenyl polyisocyanate. After the polyurethane cement composition according to claim 1 or 2 is applied as an undercoat to the floor base concrete surface to a thickness of 0.2 mm or more and less than 0.6 mm, the polyurethane cement composition is further cured. A concrete floor construction method characterized in that the coating is finished with a thickness of 1.5 mm or more and less than 2.5 mm.