JP2000001353A - Hydraulic mixture hardening retarder and treatment of surface of hardened body with the retarder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a hardening retarder for the surface of a hydraulic mixture by which the outline of the periphery of a part subjected to the retardation of hardening (surface-roughened part) is made clear under a uniform depth of a part to be subjected to the retardation of hardening and to treat the surface of a hardened body with the hardening retarder. SOLUTION: This hardening retarder contains a crosslinked body obtd. by crosslinking a polymer having >=60 mgKOH/g acid value and insoluble in neutral water and acidic water through covalent bonds as an essential component. The surface of a hardened body is treated as follows; the hardening retarder is brought into contact with at least a part of the surface of an unhardened hydraulic mixture, the hydraulic mixture is cured for hardening while retarding the hardening of the surface part and the unhardened part in the surface of the resultant hardened body is washed out.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic hardening material setting retarder and a method for treating the surface of a cured product using the setting retarder.

[0002]

2. Description of the Related Art During the construction of concrete, after hardening of all or a part of the surface of a hydraulic admixed material is delayed, the uncured part is washed out and the whole or part of the hardened material surface is roughened. There is a known method for converting the data. One of the purposes of roughening the surface of the cured product is to facilitate post-processing such as joining of concrete, application of a surface finishing material after concrete casting, painting, and the like. It is to modify the concrete surface.

[0003] As a method of retarding the setting of the surface of a hydraulic admixture,
There is a method of spraying a curing retarder on the surface of the cast uncured hydraulic mixture. In this method, it is easy to roughen the entire surface of the cured product, but in order to partially roughen the surface, a coating step for exposing only that portion is required, which is troublesome, and also causes a delay in curing. Since it is difficult to equalize the amount of material sprayed, there is also a problem that the depth of the roughened portion is partially different. The unevenness of the depth of the roughened portion deteriorates the quality of the decorative finish and the paint finish on the surface of the cured product, and adversely affects the surface modification.

[0004] As a method for solving such a problem, Japanese Patent Publication No. 6-51979 and Japanese Patent Application Laid-Open No. Hei 7-300378 disclose a water-soluble low molecular weight material as a material exhibiting a large hardening (setting) retarding effect in a small amount. A method is disclosed in which the surface of an uncured hydraulic admixture is coated with a set retardation sheet (set retardation sheet) obtained by impregnating or applying a substance to a substrate such as paper or nonwoven fabric or polypropylene. According to this method, it is possible to cause curing delay only in the portion where the curing retardation sheet is stuck, and it is easier to partially roughen the surface than in the above-described method. In addition, the distribution of the curing retardant is less likely to be non-uniform.

[0005] However, even with this improved method, there remains a problem in that the depth of the roughened portion becomes non-uniform, and furthermore, a problem arises in the clarity of the contour of the roughened portion. That is,
When the surface of the hydraulic admixture is coated with the curing retardation sheet, water-soluble low-molecular substances having curing (coagulation) retarding ability are easily eluted from the base material to the surface of the hydraulic admixture due to the action of water penetrating the sheet. . The degree of this elution differs depending on the part of the curing retardation sheet. The exuded water-soluble low-molecular substance may move with free water. As a result, the amount of the water-soluble low-molecular substance is partially different in the portion where the curing retardation sheet is in contact, and the concentration of the water-soluble low-molecular substance becomes uneven on the surface of the hydraulic admixture. The problem is that the depth is somewhat uneven (deep or shallow carving occurs). In the peripheral portion of the sheet, the contour of the roughened portion becomes unclear, and there is also a problem that the hardened delayed portion spreads beyond the portion covered by the sheet.

[0006]

SUMMARY OF THE INVENTION In view of the above circumstances, the problem to be solved by the present invention is that the depth of the portion causing the hardening delay is uniform, and the contour of the peripheral portion of the hardening delayed portion (roughened portion). And to provide a method for treating the surface of a cured product using this curing retarder.

[0007]

In order to solve the above-mentioned problems, the present inventors have conducted various studies and experiments. As a result, excessive elution of the setting retarder due to penetration of water is caused by the polymer which is a curing retarder. As a result, the present inventors have found that a substance which does not dissolve in neutral or acidic water can be suppressed by performing a crosslinking treatment, and arrived at the present invention.

Accordingly, the hydraulic admixture curing retarder according to the present invention is a curing retarder used to contact at least a part of the surface of an uncured hydraulic admixture to delay the curing of the surface portion. Material, acid value 60mgK
It is characterized by containing, as an essential component, a crosslinked product obtained by crosslinking a polymer insoluble in neutral or acidic water of OH / g or more through a covalent bond. Further, it is preferable that the curing retarder is in the form of a sheet.

The method for treating the surface of a cured product according to the present invention comprises the steps of:
A method for curing the hydraulic admixture while contacting the curing retarder according to the present invention to delay curing of the surface portion thereof, and then washing out the uncured portion of the cured product surface. .

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Curing retarder and curing retarding sheet [Description of curing retarder] The curing retarder of the present invention uses a crosslinked body as described below as a curing retardant component. May be included. Other curing retardants include, for example, sugars such as sucrose, lactose, maltose, glucose, fructose, glycogen, and organic acids such as gluconic acid, ligninsulfonic acid, tannic acid, humic acid, and glucopeptonic acid, and salts thereof. In addition, there are inorganic acids such as phosphoric acid, boric acid and silicofluoride and salts thereof, and these other curing retarding components can be blended in less than 20% by weight of the total amount of the curing retarding material. By compounding other curing delay components,
Although the effect of retarding curing can be enhanced, when blended in a large amount, the curing retarding depth may become uneven or the contour may become unclear.

The polymer used as a raw material of the crosslinked product (hereinafter sometimes referred to as a raw material polymer) has an acid group, but does not dissolve in neutral and acidic water. Neutral and acidic in the present invention are those having a pH of less than 7.5. The acid value of the raw material polymer may be 60 mg KOH / g or more, preferably 70 to 500 mg KOH / g, more preferably 1 to 500 mg KOH / g.
00 to 300 mgKOH / g, most preferably 100 to 300 mgKOH / g
200 mgKOH / g. The acid value of the starting polymer is 60
If the amount is less than mgKOH / g, it is difficult to sufficiently delay the setting of the hydraulic admixture.

As a specific method for measuring the acid value of the starting polymer, there is, for example, an acid value measuring method described in 4.3 of JIS-K6901 “Test method for liquid unsaturated polyester resin”. In this method, the acid value is measured by dissolving the raw material polymer in a mixed solvent consisting of 7 volumes of toluene and 3 volumes of ethanol. In addition, when the raw material polymer does not dissolve in the above-mentioned mixed solvent, a solvent that can be dissolved may be selected, and measurement may be performed using this.

The type of the raw material polymer is not particularly limited as long as it has the acid value specified above.
-Consisting of an α, β-unsaturated carboxylic acid structural unit having an open carbon-carbon double bond derived from an unsaturated carboxylic acid, or other unsaturated copolymerizable with the α, β-unsaturated carboxylic acid. Examples of the polymer include a polymer derived from a monomer and further containing another monomer structural unit having a carbon-carbon double bond opened.

Examples of the α, β-unsaturated carboxylic acid include α, β-unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, itaconic acid and fumaric acid; and maleic anhydride, itaconic anhydride and the like. α, β-unsaturated carboxylic acid anhydrides; and α, β-unsaturated dicarboxylic acid monoesters such as maleic acid monoester, fumaric acid monoester and itaconic acid monoester. The α, β-unsaturated carboxylic acid may be only one kind,
There may be more than one type. Of these, acrylic acid and / or methacrylic acid are preferably used because they are inexpensive and have good copolymerizability with other unsaturated monomers.

The proportion of the α, β-unsaturated carboxylic acid in the unsaturated monomer is preferably from 7 to 80% by weight, more preferably from 10 to 30% by weight, based on the whole unsaturated monomer. When the proportion of the α, β-unsaturated carboxylic acid is less than 7% by weight, the acid value of the raw material polymer becomes low, and the curing retarding effect of the curing retarder becomes low. When the proportion of the α, β-unsaturated carboxylic acid exceeds 80% by weight, the polymer becomes soluble in neutral and / or acidic water, and particularly when the degree of crosslinking of the crosslinked product is low, the polymer is easily eluted. .

Examples of other monomers include those having 1 to 18 carbon atoms such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, stearyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, and stearyl methacrylate. Esters of monohydric alcohols with (meth) acrylic acid; acrylonitrile,
Nitrile group-containing vinyl monomers such as methacrylonitrile; amide group-containing vinyl monomers such as acrylamide and methacrylamide; hydroxyl-containing vinyl monomers such as hydroxyethyl acrylate and hydroxypropyl methacrylate; glycidyl methacrylate and the like Epoxy group-containing vinyl monomers; metal salts of α, β-unsaturated carboxylic acids such as zinc acrylate and zinc methacrylate; styrene, α
-Aromatic vinyl monomers such as methylstyrene; aliphatic vinyl monomers such as vinyl acetate; halogen-containing vinyl monomers such as vinyl chloride, vinyl bromide, vinyl iodide, and vinylidene chloride; allyl ether And maleic acid derivatives such as maleic anhydride and dialkyl esters of maleic acid;
Fumaric acid derivatives such as mono- and dialkyl esters of fumaric acid; maleimide derivatives such as maleimide, N-methylmaleimide, stearylmaleimide, N-phenylmaleimide, N-cyclohexylmaleimide; mono- and dialkylesters of itaconic acid, itaconamides, itaconimide Acid, derivatives of itaconic acid esters and itaconic amides; alkenes such as ethylene and propylene; and dienes such as butadiene and isoprene. The other monomer may be only one kind or two or more kinds. Among these, alkyl acrylates and / or alkyl methacrylates can easily obtain esters having various properties, and the hydrophilicity and flexibility of the raw material polymer can be controlled by appropriately combining them. It is preferably used because it has good copolymerizability. In this sense, the (meth) acrylic acid ester is preferably used in an amount of 30% by weight or more based on the whole unsaturated monomer.

(Meth) acrylic monomers such as (meth) acrylic acid and (meth) acrylic acid ester have various preferable properties as described above, and can be obtained easily and inexpensively. Therefore, as the raw material polymer, (meth)
(Meth) acrylic polymers in which the proportion of structural units derived from acrylic monomers accounts for at least 50% by weight of the polymer are preferred.

The weight-average molecular weight of the raw material polymer is not particularly limited, however, since strength and flexibility are increased,
The range of 00 to 300,000 is preferred. The raw material polymer is preferably produced by solution polymerization in an organic solvent. This is because a curing retardation sheet described later can be easily obtained by mixing a crosslinking agent into a solution containing the raw material polymer obtained by the solution polymerization, coating and drying.

Examples of the polymerization method include anionic polymerization, cationic polymerization and radical polymerization, and radical polymerization is preferred. The radical polymerization initiator used in the radical polymerization is not particularly limited, but specific examples thereof include 2,2′-azobisisobutyronitrile and 2,2′-azobis (2,4-dimethylvaleronitrile). Azo initiators such as benzoyl peroxide;
Peroxide initiators such as di-t-butyl peroxide and the like can be mentioned. Two or more of these radical polymerization initiators may be used in combination.

The solvent used in the solution polymerization is not particularly limited as long as it does not hinder the radical polymerization reaction.
Examples include alcohols such as methanol, ethanol, and isopropyl alcohol; aromatic hydrocarbons such as benzene and toluene; ketones such as acetone and methyl ethyl ketone; and aliphatic esters such as ethyl acetate and butyl acetate. Two or more of these solvents may be used in combination.

Examples of the reaction vessel used for producing the raw material polymer include a tank reactor, a kneader, and a tubular reactor such as a static mixer. These reactors can be used together if necessary. A dropping tank is also used as needed. The pressure in the reaction vessel may be any of reduced pressure, normal pressure, and pressurized. The method of crosslinking the raw material polymer by a covalent bond is generally a method of mixing the raw material polymer and a crosslinking agent and causing a reaction (crosslinking reaction).

As the cross-linking agent, a compound having two or more functional groups capable of reacting with an acid group such as a carboxyl group may be used.
There is no particular limitation, and examples thereof include an epoxy-based crosslinking agent such as o-phthalic acid glycidyl ether; an oxazoline-based crosslinking agent such as a polymer having an oxazoline group in a side chain; an aziridine-based crosslinking agent such as an aziridine compound. Further, those having a hydroxyl group, an isocyanate group, or the like as another functional group may be used. Two or more of these crosslinking agents may be used in combination.

The amount of the crosslinking agent is not particularly limited, but is, for example, 0.2 to 20% by weight, preferably 0.5 to 10% by weight, based on the raw material polymer. If the amount of the cross-linking agent is less than 0.2% by weight, the degree of cross-linking of the cross-linked product will be low, and curing may be delayed to an undesired portion. On the other hand, if the amount of the cross-linking agent exceeds 20% by weight, the degree of cross-linking of the cross-linked product will be too high, and the penetration of the hydraulic admixture will be insufficient, and hardening delay on the surface of the hydraulic admixture will hardly occur. .

The crosslinking reaction may be performed in a solvent. As such a solvent, for example, the above-mentioned solvent used when producing a raw material polymer by solution polymerization can be used. The temperature of the crosslinking reaction is, for example, 100 ° C. or higher when an epoxy-based crosslinking agent is used, and is not particularly limited when an oxazoline-based crosslinking agent is used, and may be room temperature.

When the crosslinking reaction is slow, a crosslinking catalyst is used.
As the crosslinking catalyst, for example, when an epoxy crosslinking agent is used, a quaternary ammonium salt such as trimethylbenzylammonium chloride and tetramethylammonium chloride; and a tertiary ammonium salt such as benzylamine, tributylamine and tris (dimethylamino) methylphenol Amines; and imidazole compounds such as 2-methylimidazole and 2-methyl-4-ethylimidazole. Two or more of these crosslinking agents may be used in combination.

The form of the curing retarder of the present invention is not particularly limited, and examples thereof include powder, sheet, and film. Of these,
The sheet-like material is easy to handle and can easily treat the surface of the cured product. The curing retardant according to the present invention uses a crosslinked polymer as a curing retarding component, so that even when it comes into contact with alkaline water derived from concrete,
Excessive elution does not occur, so that the depth of the part for which curing is delayed is uniform over the entire surface, and the boundary between the roughened part and the non-roughened part becomes clear. Although the polymer has an acid group and sufficiently exerts a curing retarding action, unlike the above-mentioned known water-soluble curing retarding components, the polymer has a property of not dissolving in neutral and acidic water, and therefore, according to the present invention. The curing retardant does not elute the curing retarding component even when wet with ordinary water such as rainwater,
Good preservability.

[Explanation of the curing retardation sheet] The curing retardation sheet is a sheet-like curing retardation material, and is easy to handle. By applying this sheet to the surface of the cured product described later, the surface of the cured product can be easily treated. be able to. This sheet uses a base material in the sense of imparting strength to the sheet, facilitating construction, etc., and has applied or impregnated the base material with a curing retarder containing a crosslinked body as an essential component. Usually, it may be in the form of a film that does not use a substrate, or may be a film obtained by laminating this film on a substrate.

The curing retardation sheet may contain additional components other than the components constituting the curing retarder described above. Such additives include kaolin,
Fillers such as asbestos and mica; dioctyl phthalate;
Plasticizers such as acetyl tributyl citrate; and lubricants such as stearyl alcohol, stearic acid, stearic amide, and calcium stearate.

The thickness of the film composed of the curing retarder or the composition containing the above-mentioned additive component is not particularly limited, but is preferably 20 to 200 μm, and is preferably 3 to 200 μm.
0-100 μm is more preferred. If the thickness is within the above range, workability during use is good and it is economical. As a method of forming a film, for example, a method of forming a film while cross-linking the raw material components of the crosslinked body can be exemplified. Specifically, there is a so-called solution casting method in which a mixture of a solvent and a raw material component containing a polymer and a cross-linking agent is applied and then the solvent is evaporated at room temperature or under heating.

In the case where the curing retardation sheet is of a type using a substrate, examples of the substrate include, in addition to cellulosic paper, a sheet of a thermoplastic resin or a thermosetting resin. There is no particular limitation on the thickness of the substrate. As a method of impregnating and coating the substrate, for example,
After coating or impregnating the raw material component of the crosslinked material on the base material, a method of crosslinking by heating or the like can be used. The coating method and the impregnation method are not particularly limited, and examples thereof include a method using a coating machine, a roller, a brush, a spray, and the like. Impregnation amount,
The application amount is, for example, 20 to 300 g / m ² .

The curing retardation sheet is formed by impregnating and applying one side of a film composed of a curing retardation material or a composition obtained by blending the above-mentioned additional components with the curing retardation material or the composition obtained by blending the curing retardation material or the above-mentioned additional components. Alternatively, a pressure-sensitive adhesive sheet type in which a pressure-sensitive adhesive layer is formed on one surface of a substrate on which the film is laminated, may be used. This is because, if the pressure-sensitive adhesive layer is formed, the curing retardation sheet can be easily attached to the surface of the concrete casting formwork. The pressure-sensitive adhesive layer may be partially formed on one surface of the sheet. As an adhesive, for example,
Natural rubber adhesive, SIS or SBR synthetic rubber adhesive, acrylic adhesive, vinyl acetate adhesive, polyvinyl alcohol adhesive, EVA adhesive, urethane adhesive, acrylic soluble alkali etc. An adhesive can be used. When the pressure-sensitive adhesive is an alkali-soluble pressure-sensitive adhesive or a water-soluble pressure-sensitive adhesive such as an acrylic resin, it is easy to peel off the sheet from the mold after use of the curing retardation sheet,
A special operation for removing the adhesive layer is not required. There is no particular limitation on the method for forming the pressure-sensitive adhesive layer.
There is a method in which the pressure-sensitive adhesive is applied to a film or a base material by a coating machine such as a hot melt coater, a Revas coater, a gravure coater, or a bar coater.

The curing retardation sheet is applied to the surface of the uncured hydraulic admixture to delay the curing of the hydraulic admixture at the contacted portion, and then the surface of the cured product is washed to clean the uncured admixture. The hydraulic mixture is washed out and the surface of the cured product is roughened. The roughened portion facilitates post-processing such as joining of concrete, sticking of a surface finishing material to concrete, and painting. Cut the curing retardation sheet into a desired shape, apply curing to the desired portion of the hydraulic admixture to cause a curing delay, and if this portion is washed out, only this portion is roughened and a pattern appears on the surface of the cured product. . If the hardening-delayed portion is made deeper, the roughened portion appears as a concave portion after washing, and the pattern can be more clearly expressed by the concave portion. If you use this curing delay sheet,
The cured product can also be surface-modified.

The curing retardation sheet can be used for purposes other than such surface roughening. The curing retardation sheet has a curing retarder obtained by cross-linking the polymer as an essential component, so that even in contact with concrete-derived alkaline water, excessive elution does not occur. The entire surface is uniform, and the boundary between the roughened portion and the non-roughened portion becomes clear. The polymer has an acid group and sufficiently exerts a curing retarding action, but unlike the water-soluble curing retarding component used in the known curing retarding sheet described above, has a property of not being dissolved in neutral and acidic water. Therefore, the curing retardation sheet according to the present invention does not cause the elution of the curing retardation component even when wet with ordinary water such as rainwater, does not easily block, has excellent storage stability, and has extremely good handleability. Therefore, treatment of the surface of the cured product can be easily performed. Method for Treating Hydraulic Admixture Surface The treatment method according to the present invention includes a curing step of curing the hydraulic admixture while leaving an uncured portion on the surface, and a washing step of washing out the uncured portion.

Hydraulic admixtures include Portland cement,
It contains hydraulic cement such as mixed cement and water, and if necessary, additives such as admixtures and aggregates such as sand and gravel. In the curing step, the setting retarder according to the present invention is brought into contact with a necessary portion of the surface of the uncured hydraulic mixture. The contact here is performed by, for example, spraying, coating, or applying a curing retardant. Hereinafter, the case where the curing delay sheet is used will be described. When using a mold in the curing process, a curing retardation sheet is attached in advance to a required portion of the inner surface of the mold, and then a hydraulic admixture is poured into the uncured hydraulic admixture. The curing delay sheet will hit. Then, the curing retardant component of the curing retardation sheet inhibits the hydration reaction of the hydraulic admixture, which is a mixture of water, cement, bone, and the like. Therefore, the hardening of the hydraulic admixture is delayed at the surface portion touched by the hardening delay sheet. The thickness (depth) of the uncured portion is controlled by changing the type and amount of the crosslinked material. In the curing step, a raw material component of the curing retarder containing the polymer and the cross-linking agent may be directly applied to a required portion of the inner surface of the mold to form a layer of the curing retarder on the spot.

In the curing step, in the present invention, a crosslinked product obtained by crosslinking a raw material polymer is essential as a curing retarding component, so that excessive elution hardly occurs.
As described above, the entire cast hydraulic mixture is cured while delaying the curing of at least a part of the surface of the hydraulic mixture. At this time, if the water content is insufficient, the hydration reaction is unlikely to occur, so that water may be sprayed on the uncured hydraulic admixture before and / or after the curing retardation sheet is applied to the surface of the hydraulic admixture. The curing method is not particularly limited, and a natural curing method, a steam curing method, a pressure curing method, or the like can be used. The curing time may be such that the uncured portion of the surface can be easily removed by washing with water, and the entire portion other than the uncured portion is sufficiently cured. This time is about 8 to 50 hours at room temperature in the natural curing method.

The washing step is a step of washing uncured portions by washing the surface of the cured product of the hydraulic mixture with water,
For example, the cleaning is performed by spraying a cleaning liquid containing water and, if necessary, an emulsifier or the like onto the surface of the cured product at a high pressure, or by applying the cleaning liquid to the surface of the cured product and rubbing the surface of the cured product with a rotating brush or the like. By this washing, the uncured hydraulic admixture is removed from the uncured portion on the surface of the cured product, and a cured retardation portion such as a roughened portion or a concave portion appears on the cured product surface.

[0037]

The following examples are illustrative of the present invention and do not limit the scope of the present invention. Example 1 570 g of methyl ethyl ketone was charged into a 2-liter glass reactor equipped with a thermometer, a stirrer, a dropping funnel, a gas inlet tube and a reflux condenser, and the temperature was raised to a temperature at which methyl ethyl ketone was refluxed. Subsequently, 240 g of methyl methacrylate, 126 g of methyl acrylate,
144 g of ethyl acrylate and 90 g of methacrylic acid were mixed and mixed with 2,2'-azobisisobutyronitrile (AI
A raw material solution in which 3 g of (BN) was dissolved was charged into a dropping funnel, 30% of the raw material solution was dropped into the reactor, and the reaction was continued until methyl ethyl ketone was refluxed again by heat of polymerization. From the point at which reflux began again, the remaining 70% of the raw material liquid was uniformly dropped into the reactor over 2 hours. 30 minutes and 60 minutes after the completion of the dropping of the raw material, an AIBN solution obtained by dissolving 0.6 g of AIBN in 15 g of methyl ethyl ketone was dropped into the reactor, and the reaction was terminated 2 hours after the completion of the dropping of the AIBN solution. Until the completion of the polymerization, the reactor was kept at a temperature at which methyl ethyl ketone was refluxed to produce a polymer. This polymer had an acid value of 94 mgKOH / g and was hydrophilic, but was insoluble in water having a pH of less than 7.5.

A solution containing the obtained polymer (solid concentration 5
(0 wt%), 30 g of a crosslinking agent obtained by diluting o-phthalic acid diglycidyl ester (Denacol EX721, manufactured by Nagase Kasei Kogyo Co., Ltd.) 10 times with acetone (1.125 g, 0.1125 g of crosslinking agent) was added. The mixture was stirred until. The obtained cross-linking agent-containing polymer solution was weighed to 7
It was applied to 0 g / m ² kraft paper using an applicator so as to have a dry thickness of 62.5 μm and air-dried. Thereafter, the mixture was heated at 60 ° C. for 15 minutes using an oven, and then heated at 150 ° C. for 5 minutes to complete the cross-linking, and a cured retardation sheet (1) containing a retarder was obtained.

The hardening delay sheet was adhered to the inner wall surface of the plastic container with a double-sided tape so that the surface of the obtained hardening delay sheet (1) on which the hardening material was formed faced the inside (the mortar side) of the plastic container. . Mortar (hydraulic mixture) consisting of 28 parts by weight of ordinary Portland cement, 56 parts by weight of Toyoura standard sand and 16 parts by weight of water is poured into this container, cured for 3 days, demolded, and the surface of the obtained cured product Was washed with water using a brush.

Thereafter, the uniformity of the curing retardation treatment, the depth of the curing retardation portion, the clarity of the boundary between the roughened portion and the non-roughened portion, and the blocking property were evaluated. The results are as shown in Table 1. (Examples 2 to 6) Example 1 was repeated except that the amount of the crosslinking agent and the heating conditions in the oven were changed to those shown in Table 1.
After the curing retardation sheets (2) to (6) were obtained in the same manner as in Example 1, each performance was evaluated in the same manner as in Example 1, and the results are shown in Table 1.

Example 7 To 30 g of the polymer solution used in Example 1, 0.1125 g of a polymer having an oxazoline group (Epocloth RS-1205T, manufactured by Nippon Shokubai, oxazoline equivalent 555) as a crosslinking agent was added. After stirring until uniform, a cured retardation sheet (7) coated with a curing retardant was obtained in the same manner as in Example 1, and each performance was evaluated in the same manner as in Example 1. The results are shown in Table 1. It was shown to.

Examples 8 to 12 In the same manner as in Example 1 except that the amount of the crosslinking agent and the heating conditions in the oven were changed to those shown in Table 1, the curing retardation sheets (8) to (8) were used.
After obtaining (12), each performance was evaluated in the same manner as in Example 1, and the results are shown in Table 1. (Comparative Example 1) A comparative curing retardation sheet (1) was obtained in the same manner as in Example 1 except that no crosslinking agent was added to the polymer solution, and each performance was evaluated in the same manner as in Example 1. The results are shown in Table 1.

(Comparative Example 2) A comparative curing retardation sheet (2) was obtained in the same manner as in Example 2 except that no crosslinking agent was added to the polymer solution. Was evaluated, and the results are shown in Table 1.

[0044]

[Table 1]

As seen from the above, the curing retardation sheet containing the curing retardant has uniform curing retardation treatment, can adjust the depth of the curing retardation portion, and has excellent boundary definition. . The setting retardation sheet also does not cause blocking. The evaluation criteria for the uniformity, boundary clarity, and blocking property of the curing retardation treatment in Table 1 above are as follows. Uniformity of curing delay treatment ○: The curing delay portion has a uniform depth over the entire surface.

Δ: In the hardening-delayed portion, a part of a deeply or shallowly carved portion is slightly observed. X: Many deeply carved or shallow carved parts are seen in the hardening delay part. Boundary clarity ：: The boundary between the cured retardation part and the normal cured part can be clearly distinguished.

：: Although the boundary between the hardened delayed portion and the normal hardened portion is clear, slight discoloration is seen in the portion adjacent to the hardened delayed portion. Δ: The boundary between the hardened delayed portion and the normal hardened portion is almost clear, but the surface of the portion adjacent to the hardened delayed portion is slightly brittle. ×: The boundary between the hardened delayed portion and the normal hardened portion is unclear, and the brittle portion is spread on the surface around the hardened delayed portion. Blocking property ○: No blocking ×: Blocking

[0048]

According to the present invention, if the curing retarder is used,
The depth of the part for which the curing is delayed is uniform, and the outline of the periphery of the part for which the curing is delayed becomes clear. In the curing retarder according to the present invention, since a crosslinked product is used as a curing retarding component, excessive elution does not occur, and furthermore, the starting polymer of the crosslinked product has a property of not being dissolved in neutral and acidic water. Even when wet with rainwater or the like, dissolution of the curing retarding component does not occur, and the storage stability is good. When the curing retardant is in the form of a sheet, the above-mentioned effect is exhibited, the handling is easy, and the treatment of the surface of the cured product can be easily performed.

According to the method for treating the surface of a cured product according to the present invention, the depth of the portion for which curing is delayed can be made uniform, and the outline of the periphery of the portion for which curing is delayed can be clarified.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Masuji Izumibayashi 5-8 Nishiburi-cho, Suita-shi, Osaka Nippon Shokubai Co., Ltd. F-term (reference) 4G012 RB02

Claims (4)

[Claims] Claims: 1. A curing retarder used to contact at least a part of the surface of an uncured hydraulic admixture to delay curing of the surface part, wherein the curing retarder has an acid value of 60 mg KOH.
A hydraulic admixture hardening retarder comprising, as an essential component, a crosslinked product obtained by crosslinking a polymer that is insoluble in neutral / acidic water or more via a covalent bond. 2. The polymer according to claim 1, wherein said polymer is obtained by polymerizing an unsaturated monomer having an α, β-unsaturated carboxylic acid ratio of 7 to 80% by weight. Curing retarder. 3. The curing retarder according to claim 1, which is in the form of a sheet. 4. The method according to claim 1, wherein at least a part of the surface of the uncured hydraulic admixture is brought into contact with the curing retarder according to any one of claims 1 to 3 to delay the curing of the surface. A method for treating the surface of a cured product, in which curing is performed to cure the hardened mixture, and then the uncured portion of the surface of the cured product is washed out.