JPH04254485A - Waterproof treatment method for high-strength hardened cementitious material - Google Patents

Abstract

PURPOSE:This applicant proposed to provide the water resistant treating method for the high-strength cementitious cured body which further improves the above- mentioned method for improving the water resistance. CONSTITUTION:(1) The water resistant treating method for the high-strength cementitious cured body consisting in mixing hydraulic cement, water and aq. org. polymer, then kneading the mixture under high shearing and further impregnating an isocyanate compd. into the high-strength cementitious cured body obtd. by curing, then bringing this body into contact with steam and heating the body. (2) The water resistant treating method stated in the above-mentioned (1) in which the contact conditions of the cured body and the steam are 50 to 100 deg.C and 70 to 100% humidity.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for treating high-strength hardened cementitious materials with water resistance.

0002

[Prior Art] In recent years, hardened hydraulic cement that exhibits extremely high bending strength has been produced by mixing hydraulic cement, water, and an aqueous organic polymer, and then kneading the mixture under high shear using a mixing roll or the like. Patent Publication No. 59-43431 (Japanese Patent Publication No. 59-43431) published an invention relating to a high-strength hardened cementitious material that was made into a uniform kneaded product using extremely small amounts of water and then hardened.
It is disclosed in the publication number etc. This hardened product weighs 350kg/
Since it exhibits a bending strength of more than cm2 and has a dense surface, it is considered to be applied to building materials, mechanical materials, etc., and some of it has been put into practical use.

However, since this cured product contains an aqueous organic polymer, it has poor water resistance and even after curing, if water is present, it absorbs water, causing swelling, strength reduction, etc. Ta.

In order to solve these problems, the present applicant has impregnated a high-strength cementitious hardened body with an isocyanate compound to form isocyanate groups, urethane bonds, urea bonds, etc. on the surface and inside of the hardened body. JP-A-63-206342 proposed a method for improving the water resistance of a cured product by generating amide bonds, bullet bonds, allophanate bonds, and/or acylurea bonds.

[0005]

SUMMARY OF THE INVENTION The present invention relates to a method for treating high-strength hardened cementitious materials for water resistance, which is a further improvement on this method for improving water resistance.

The method disclosed in Japanese Unexamined Patent Publication No. 63-206342 has various problems in terms of process. For example, if a high-strength cementitious hardened product is impregnated with an isocyanate compound and the next heat treatment is performed without sealing the hardened product after impregnation, such as putting it in a bag, the impregnated isocyanate will be removed from the hardened product. The compound volatilizes and the amount of impregnation is considerably reduced. Therefore, the effect of improving water resistance is reduced. Further, the vapor of the isocyanate compound volatilized within the heating device is discharged from the heating device when the heating device is opened and closed, which irritates the skin and throat of the worker and is harmful to his health.

[0007] Between the impregnation step and the heating step, the cured product after impregnation is kept in a sealed state such as in a bag, and the next heating step is carried out in this state to prevent a decrease in the amount of impregnation. This solves the problem of decreased water resistance improvement effect. However, since the opportunities for workers to come into contact with isocyanate compounds increase, not only do health issues such as skin and throat irritation remain, but the work is extremely cumbersome and inefficient, resulting in process and economic problems. has a big disadvantage.

[0008]

[Means for Solving the Problems] As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that the aqueous organic polymer contained in the high-strength hardened cementitious material and the impregnated isocyanate compound Evaporation of isocyanate is prevented by treating the surface of the cured product with steam before the reaction.
The inventors have discovered that the above-mentioned problems can be solved and have arrived at the present invention.

The invention of the present application provides (1) a high-strength hardened cementitious material obtained by mixing hydraulic cement, water and an aqueous organic polymer, kneading the mixture under high shear using a mixing roll or the like, and further curing the mixture; Impregnating the body with isocyanate compounds,
A method for water-resistant treatment of a high-strength hardened cementitious material, the method comprising: contacting water vapor and then heating;

00
10] (2) The contact condition between the cured body and water vapor is a temperature of 50°C.
-100°C and a humidity of 70-100%, the water resistance treatment method according to (1) above.

The high-strength hardened cementitious material used in the present invention will be explained next. Conventional cement can be used to produce high-strength cementitious hardened bodies. Examples of use include Portland cement, mixed cement, and special cements (ultra-fast hardening cement, alumina cement).
and calcium sulfate hemihydrate cement (hemihydrate gypsum cement).

Aqueous organic polymers are used to produce high strength cementitious hardened bodies. The water-based organic polymer is added for the purpose of improving the kneadability of the hydraulic cement. Furthermore, it is presumed that the aqueous organic polymer also helps improve the mechanical properties of the obtained high-strength cementitious hardened product. Water-based organic polymers that can be used include water-soluble organic polymers (e.g., water-soluble proteins, soluble starches, water-soluble cellulose derivatives, partially saponified polyvinyl acetate, sodium polyacrylate, polyethylene oxide, polyacrylamide) and organic polymers. Examples include aqueous dispersions of rubber latex, acrylic emulsions, vinyl acetate emulsions, vinyl chloride emulsions, and ethylene-vinyl acetate emulsions, but use of partially saponified polyvinyl acetate is particularly preferred.

[0013] In order to improve the physical properties of the high-strength hardened cementitious material obtained, or to improve the physical properties of the aqueous organic polymer to be blended, the high-strength hardened cementitious material can be produced. Various additives can be added to improve workability during processing. Examples of such additives include flame retardants, low smoke additives, ultraviolet absorbers, plasticizers, admixtures usually added to hydraulic cement, hydration retardants, hydration accelerators, and even particulates. inorganic and organic fillers, inorganic and organic fibrous fillers.

The hydraulic cement, water-based organic polymer, and additives are kneaded with water to form a hydraulic cement mixture. Usually, powdered solid raw materials excluding liquid raw materials such as water are put into a mixer, then liquid raw materials such as water are added and mixed, and the resulting mixture is transferred to a powerful kneader for further kneading. Examples of powerful kneading machines are kneaders, Banbury mixers, wet pan mixers, mixing rolls, Cunet machines, pug mills, and screen extruders. By using a powerful kneader, the amount of air bubbles contained in the hydraulic cement mixture to be kneaded will be reduced, and sufficient kneading can be achieved even with a small amount of water used during kneading. As a result, it becomes easy to obtain a cured hydraulic cement body with high bending strength. The sufficiently kneaded hydraulic cement mixture is formed into a plate shape and further rolled using a calendar roll or the like. Next, this hydraulic cement rolling body is hardened. For curing, conventional curing methods such as atmospheric curing, humid air curing, underwater curing, and autoclave curing are used. Moreover, the hydraulic cement rolling body before being cured may be heated and pressed in the surface direction to promote hardening. After curing, drying is generally performed. Drying further increases the strength of the cured hydraulic cement. In this way, a high-strength hardened cementitious body used in the method of the present invention is produced.

Next, in order to improve the water resistance of the high-strength hardened cementitious material, the high-strength hardened cementitious material is impregnated with an isocyanate compound. Impregnation can be done by placing a liquid isocyanate compound or a solution of an isocyanate compound dissolved in a solvent in a container and immersing the high-strength cementitious material, or by soaking a liquid isocyanate compound or a solution of an isocyanate compound dissolved in a solvent in a container. It is applied by a roll coater, flow coater, spray or brush method. In order to promote the penetration of isocyanate compounds or isocyanate compound solutions into high-strength hardened cementitious materials, methods of applying pressure or applying ultrasonic vibration during dipping or application, or after dipping or application are used. May be adopted.

[0016] In order to allow the isocyanate compound to penetrate into the high-strength hardened cementitious material, it is preferable to use an isocyanate compound with low viscosity. Isocyanate compounds with high viscosity are used after being diluted with a solvent to lower the viscosity.

[0017] There are no particular limitations on the isocyanate compound used. Examples of isocyanate compounds used include:
Monoisocyanates (e.g. phenyl isocyanate, p
-Chlorphenylisocyanate, o-chlorophenylisocyanate, m-chlorphenylisocyanate,
3,4-dichlorophenylisocyanate, 2,5-dichlorophenylisocyanate, methyl isocyanate, ethyl isocyanate, n-butyl isocyanate,
n-propyl isocyanate, octadecyl isocyanate), diisocyanate (e.g. 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4
, 4'-diphenylmethane diisocyanate, dianisidine diisocyanate, o-tolylene diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, 1,5-naphthalene diisocyanate,
Transvinylene diisocyanate, lysine isocyanate, isophorone diisocyanate, dimeryl diisocyanate, trimethylhexamethylene diisocyanate, 3,3'-dimethyldiphenylmethane 4,4'-diisocyanate, isopropylidene bis(4- cyclohexyl isocyanate), hydrogenated 4,4'-diphenylmethane diisocyanate, hydrogenated tolylene diisocyanate), triisocyanate (e.g. triphenylmethane triisocyanate, tris(4-phenylisocyanate thiophosphate)) , polyisocyanates (e.g. polymethylene polyphenylisocyanate), and dimers thereof (e.g. N,N'(4,4'-dimethyl 3,3
'-diphenyl diisocyanate) uredione) and trimers (e.g. 4,4',4''-trimethyl 3,3',3''-
triisocyanate (2,4,6-triphenyl cyanurate), and derivatives thereof (eg, carbodiimide-modified isocyanate).

As the solvent, acetone, benzene, toluene, nitrobenzene, dibutyl ether, methyl ethyl ketone, dioxane, acetonitrile, benzyl cyanide, anizole, monochlorobenzene, xylene, butyl acetate, ethyl acetate, tetrahydrofuran, etc. are used.

In order to increase the reaction rate between the isocyanate compound and the aqueous organic polymer, a catalyst can be added to the isocyanate compound or the isocyanate compound solution. The catalyst is preferably a catalyst for polyurethane. The catalyst used is an amine type (e.g. 1,4-diazabicyclo(2,2,2)octane, PMDETA, N,N
-dimethylcyclohexylamine, N-methyldicyclohexylamine), DBU type (e.g. 1,8-diaza-bicyclo[5,4,0]undecene-7 and its salts),
Examples include metals (eg stannath octoate, dibutyltin dilaurate) and others (eg butadiene sulfone, esters of inorganic acids, oxyacids, phosphoric acid or boric acid).

The hardened high-strength cementitious body impregnated with the isocyanate compound is then brought into contact with water vapor. The contact conditions are preferably a temperature of 50 to 100°C and a humidity of 70 to 100%. If the temperature is less than 50°C, a long treatment time will be required to eliminate the odor of the isocyanate compound. If the humidity is less than 70%, the amount of isocyanate compounds that evaporate during steaming increases. The time required for the steam treatment is usually one hour or more.

The high-strength hardened cementitious material impregnated with the isocyanate compound and brought into contact with water vapor is further heated in order to accelerate the reaction of the isocyanate compound. The heating temperature and heating time vary depending on the isocyanate compound, solvent, catalyst, etc. used, but even when no catalyst is used,
When heated at 100°C, the reaction proceeds sufficiently within 20 hours.

The high-strength hardened cementitious body thus obtained exhibits a bending strength of 350 kg/cm 2 or more and is also excellent in water resistance. Next, the present invention will be explained with reference to examples.

[0023]

[Example] Examples 1 and 2 100 parts by weight (250 g) of alumina cement (manufactured by Asahi Glass Co., Ltd., trade name Asahi Alumina Cement No. 1) and 3 parts by weight (7.5 g) of partially saponified polyvinyl acetate (Japanese) 11 parts by weight (27 parts by weight) was mixed in a planetary mixer for 4 minutes.
．． A solution consisting of 5g) of water and 0.3 parts by weight (0.75g) of glycerin was added and mixed for an additional 4 minutes.

[0024] This mixture was mixed with a pair of rolls at a rotation ratio of 1:1.
．． Kneading was carried out for 5 minutes using a mixing roll set at 12, and the resulting kneaded product was formed into a sheet-like molded product with a width of about 160 mm, a length of about 180 mm, and a thickness of about 3.4 mm.

[0025] This molded body was rotated between a pair of rolls at a rotation ratio of 1:1.
Rolling is done using a calendar roll set to a width of approximately 1
The rolled body had a length of 65 mm, a length of about 185 mm, and a thickness of about 3.2 mm.

[0026] This rolled body was heated at a temperature of 80°C and a pressure of 30 kg/
After pressurizing and heating for 10 minutes under the condition of cm2, the sample was left standing for 24 hours in an atmosphere with a temperature of 20° C. and a relative humidity of 50% for curing. After curing, it was dried by maintaining it at a temperature of 80° C. for 24 hours to obtain a high-strength hardened cementitious body with a width of about 170 mm, a length of about 180 mm, and a thickness of about 3.0 mm.

The obtained high-strength hardened cementitious body was immersed for 30 minutes in a vat filled with hexamethylene diisocyanate (Example 1) and tolylene diisocyanate (Example 2). After immersion, it was subjected to steam treatment for 4 hours in a dryer at a temperature of 60°C and a humidity of 80%, and then heated in a dryer at 100°C for 20 hours.

The amount of weight loss due to heating after steam treatment and the water resistance of the obtained cured product were tested. For the water resistance test, three specimens with a width of 20 mm and a length of 180 mm were cut out from the obtained cured product, and in order to test changes due to immersion in water, they were immersed in a constant temperature water bath at 20 ° C, and changes in length and weight were measured. did. The results are shown in Table 1 along with the weight loss during heating.

[0029]

[Table 1]

Comparative Examples 1 and 2 A high-strength cementitious hardened body was produced in the same manner as in Example 1, and the hardened body was treated with an isocyanate compound (hexamethylene diisocyanate in Comparative Example 1, tolylene diisocyanate in Comparative Example 2). After soaking in a polyethylene bag (width approx. 210 mm)
, about 30 mm in length and about 0.1 mm in thickness), and the same procedure as in Examples 1 and 2 was carried out except that heating was performed in a dryer at 100° C. without steam treatment. weight loss during heating;
Table 1 shows the changes in length and weight due to immersion in water.

Comparative Examples 3 and 4 A high-strength cementitious hardened body was produced in the same manner as in Example 1, and the hardened body was treated with an isocyanate compound (hexamethylene diisocyanate in Comparative Example 3, tolylene diisocyanate in Comparative Example 4). The same procedure as in Examples 1 and 2 was performed except that after immersion in water, the sample was heated in a dryer at 100° C. without being subjected to steam treatment. Table 1 shows the change in length and weight due to immersion in water, and the weight loss upon heating.

Examples 3 to 12 High-strength hardened cementitious bodies were produced in the same manner as in Example 1, and after immersion in hexamethylene diisocyanate, steam treatment was performed at a temperature of 50 to 100°C and a humidity of 70 to 100%. The other operations were the same as in Example 1. The amount of evaporation of hexamethylene diisocyanate (weight loss during steam treatment) and the odor disappearance time of hexamethylene diisocyanate depending on the temperature and humidity during steam treatment were measured. The results are shown in Table 2.

[0033]

[Table 2]

Comparative Examples 5 to 9 High-strength hardened cementitious bodies were produced in the same manner as in Example 1, and after immersion in hexamethylene diisocyanate, steam treatment was performed at a temperature of 30 to 80°C and a humidity of 50 to 100%. The other operations were the same as in Example 1. The amount of evaporation of hexamethylene diisocyanate (weight loss during steam treatment) and the odor disappearance time of hexamethylene diisocyanate depending on the temperature and humidity during steam treatment were measured. The results are shown in Table 3.

[0035]

[Table 3]

[0036]

[Effects of the Invention] The effects of the present invention are as follows. (1) Compared to the case where a high-strength cementitious hardened body is impregnated with an isocyanate compound and the hardened body is heat-treated in the next step without sealing the hardened body after impregnation, such as putting it in a bag, the hardened body There is no decrease in the amount of impregnation due to volatilization of the impregnated isocyanate compound. Therefore, the water resistance of the high-strength hardened cementitious material does not deteriorate. Further, the vapor of the isocyanate compound volatilized within the heating device is not discharged from the heating device when the heating device is opened and closed, and does not irritate the skin and throat of the worker.

(2) Compared to the case where the cured product after impregnation is kept in a sealed state such as in a bag between the impregnation step and the heating step, and then the cured product kept in the sealed state is heat-treated. , it is possible to significantly reduce the chances of workers coming into contact with isocyanate compounds, which solves the health problem of workers' skin and throat irritation.

(3) Impregnation, steam treatment, and heating can be performed in one treatment chamber, which is extremely simple.

(4) A typical product of high-strength hardened cementitious material has a size of 60 cm x 60 cm x 3 cm or more and a weight of 3
．． The method of the present invention is suitable for industrially processing large quantities of extremely large products weighing 8 kg or more at the same time.

Claims (2)

[Claims] Claim 1: After mixing hydraulic cement, water, and an aqueous organic polymer, the mixture is kneaded under high shear using a mixing roll, etc., and further hardened to obtain a high-strength cementitious hardened product, in which an isocyanate compound is added. A method for water-proofing a high-strength hardened cementitious material, which comprises impregnating it, then contacting it with water vapor, and then heating it. 2. The water resistance treatment method according to claim 1, wherein the conditions for contacting the cured product with water vapor are a temperature of 50 to 100° C. and a humidity of 70 to 100%.