JP2008291225A - Water absorption preventive material for civil engineering and building material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a water absorption preventive material forming a deep penetration layer of alkylalkoxysilane and/or its condensate on the surface layer part of a civil engineering and building material in application to it for giving a high water repellant property and preventing penetration of a deterioration factor such as water and salt for the long term. <P>SOLUTION: This water absorption preventive material for the civil engineering and building material comprises alkylalkoxysilane and/or its condensate (A), organic bentonite (B) formed by bringing montmorillonite to reaction with quaternary ammonium ions and having 33-50% of ignition loss at 1,000°C, a polar solvent (C), and hydrophobic silica powder (D). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a water absorption preventing material for civil engineering and building materials.

Conventionally, it has been widely known that alkyl alkoxysilanes and / or condensates thereof are useful as a water absorption preventing material for civil engineering and building materials. Generally, these alkyl alkoxysilanes and / or condensates thereof are variously used. Organic solvent type water absorption preventing materials diluted with organic solvents and emulsion type water absorption preventing materials obtained by emulsifying alkylalkoxysilanes and / or their condensates in water are used. However, most of the organic solvent type or emulsion type water absorption preventive materials have an active ingredient of 50% by weight or less and the remainder is occupied by an organic solvent or water, so the solution viscosity is as low as 100 mPa · s or less, Since the amount of the active ingredient that can be applied at one time is as small as 40 to 80 g / m ² , it is necessary to apply ^two to five times in order to apply the specified amount (200 to 300 g / m ² ). In addition, due to its low viscosity, when applied to a substrate, loss due to sagging flow is likely to occur on the vertical surface, and application to the ceiling surface is impossible, and there are many restrictions in terms of workability. Yes. Furthermore, when these organic solvent type or emulsion type water absorption preventing materials are applied to the base material, the alkyl alkoxysilane and / or a part of the condensate thereof volatilizes out of the base material. In addition, there is a problem that the entire amount of the condensate and / or the condensate thereof cannot be infiltrated into the base material and a deep permeation layer of alkylalkoxysilane and / or the condensate thereof cannot be formed in the base material. In order to solve such problems, attempts have been made to increase the amount of coating, but the number of coatings increases, resulting in an increase in operating costs, which is not economical.

On the other hand, in order to solve the above-mentioned problem, a water absorption preventing material in which at least one of an inorganic mineral, a water soluble polymer and a water absorbent resin and a polar solvent are added to an alkylalkoxysilane and / or a condensate thereof has been proposed. (See Patent Document 1). However, this water absorption preventive material tends to have a slightly weak water repellency after applying the base material, and tends to have a weak salt permeation suppressing effect when exposed for a long period of time.
JP 2003-221576 A

  The object of the present invention is to suppress the volatilization of alkyl alkoxysilane and / or its condensate when applied to civil engineering building materials, and almost the entire amount of alkyl alkoxysilane and / or its condensate penetrates deeply into civil engineering and building materials. In addition, a deep permeation layer of alkylalkoxysilane and / or its condensate can be formed on the surface layer of civil engineering and building materials to provide high water repellency and to prevent the intrusion of deterioration factors such as water and salt over a long period of time. The object is to provide a water absorption preventing material.

  As a result of intensive studies, the present inventors have found that (A) an alkylalkoxysilane and / or a condensate thereof, and (B) an organic bentonite obtained by reacting montmorillonite with a quaternary ammonium ion, the ignition loss at 1000 ° C. When a water absorption preventive material composed of (C) a polar solvent and (D) a hydrophobic silica powder is used, the volatilization of the alkylalkoxysilane and / or its condensate can be suppressed. It has been found that almost the entire amount of alkoxysilane and / or its condensate penetrates deeply into the civil engineering and building material, and forms a deep penetrating layer of alkylalkoxysilane and / or its condensate on the surface layer of the civil engineering and building material. It came to complete.

That is, this invention provides the water absorption preventive material for civil engineering and building materials as shown below.
Item 1. (A) alkylalkoxysilane and / or its condensate, (B) an organic bentonite obtained by reacting montmorillonite with a quaternary ammonium ion and having a loss on ignition at 1000 ° C. of 33 to 50%, (C) A water absorption preventing material for civil engineering and building materials comprising a polar solvent and (D) hydrophobic silica powder.
Item 2. (A) An alkylalkoxysilane and / or its condensate 85 to 95% by weight, (B) an organic compound obtained by reacting montmorillonite with a quaternary ammonium ion and having an ignition loss at 1000 ° C. of 33 to 50% Item 2. The water absorption preventing material for civil engineering and building materials according to Item 1, comprising 1 to 13% by weight of bentonite, (C) 1 to 13% by weight of a polar solvent, and (D) 0.1 to 2% by weight of hydrophobic silica powder.
Item 3. The alkylalkoxysilane is represented by the general formula (1);
R ¹ _n Si (OR ² ) _4-n (1)
Item 1 in which R ¹ represents an alkyl group having 1 to 20 carbon atoms, R ² represents an alkyl group having 1 to 4 carbon atoms, and n is 1 or 2. Or the water absorption preventive material for civil engineering and building materials of 2.
Item 4. Item 4. The water absorption preventive material for civil engineering and building materials according to any one of Items 1 to 3, wherein the polar solvent is alcohol.
Item 5. Item 5. The water absorption preventing material for civil engineering and building materials according to any one of Items 1 to 4, wherein the viscosity at 20 ° C is 1,000 to 10,000 mPa · s.

  Hereinafter, the present invention will be described in detail.

(A) Alkylalkoxysilane and / or its condensate The alkylalkoxysilane used in the present invention is not particularly limited, but a compound represented by the following general formula (1) is preferably used.
R ¹ _n Si (OR ² ) _4-n (1)
In the formula, R ¹ represents an alkyl group having 1 to 20 carbon atoms, and R ² represents an alkyl group having 1 to 4 carbon atoms. n is 1 or 2.

  Examples of the alkyl group having 1 to 20 carbon atoms include methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, and tridecyl group. Tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group and the like. Among these, from the viewpoint of increasing the hydrophobicity of the substituent and increasing the water repellency of the resulting water absorption preventing material for civil engineering and building materials, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group Is preferred.

  Examples of the alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, a propyl group, and a butyl group. Among these, a methyl group, an ethyl group, and a propyl group are preferable from the viewpoint of high reactivity of the alkylalkoxysilane, easy condensation, and high water repellency of the resulting water absorption preventing material for civil engineering and building materials.

  Specific examples of such alkylalkoxysilanes include methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, propyltrimethoxysilane, propyltriethoxysilane, butyltrimethoxysilane, and butyltriethoxy. Silane, pentyltrimethoxysilane, pentyltriethoxysilane, hexyltrimethoxysilane, hexyltriethoxysilane, heptyltrimethoxysilane, heptyltriethoxysilane, octyltrimethoxysilane, octyltriethoxysilane, nonyltrimethoxysilane, nonyltriethoxy Silane, decyltrimethoxysilane, decyltriethoxysilane, undecyltrimethoxysilane, undecyltriethoxysilane, dodecyltrimethyl Xysilane, dodecyltriethoxysilane, tridecyltrimethoxysilane, tridecyltriethoxysilane, tetradecyltrimethoxysilane, tetradecyltriethoxysilane, pentadecyltrimethoxysilane, pentadecyltriethoxysilane, hexadecyltrimethoxysilane, hexa Examples include decyltriethoxysilane, heptadecyltrimethoxysilane, heptadecyltriethoxysilane, octadecyltrimethoxysilane, octadecyltriethoxysilane, dimethyldimethoxysilane, octylmethyldimethoxysilane, octadecylmethyldimethoxysilane, and the like.

Among these, it is easy to obtain, and from the viewpoint of increasing the water repellency of the water-absorbing material for civil engineering and building materials obtained, the carbon number of the alkyl group represented by R ¹ in the general formula (1) is 6 or more. Preferable examples include hexyltrimethoxysilane, hexyltriethoxysilane, octyltrimethoxysilane, octyltriethoxysilane, and decyltrimethoxysilane in which the alkyl group represented by R ² has 1 to 3 carbon atoms. These alkyl alkoxysilanes can also be used as partial condensates or mixtures.

  The proportion of the alkylalkoxysilane and / or the condensate thereof is preferably 85 to 95% by weight based on the total weight of the water absorption preventive material, and 88 to 94 from the viewpoint of easy penetration into a civil engineering building material. More preferably, it is% by weight. If the ratio is less than 85% by weight, it may be necessary to increase the amount of the polar solvent added in order to adjust the viscosity range for obtaining the water absorption preventing material, which may be unfavorable in terms of environment. On the other hand, when the ratio exceeds 95% by weight, the viscosity is lowered, and workability may be adversely affected.

(B) Organic bentonite The organic bentonite used in the present invention is not particularly limited as long as the loss on ignition at 1000 ° C. is 33 to 50%. However, the hydrophobic property of the water absorption preventing material for civil engineering and building materials obtained is not limited. From the viewpoint of increasing the water repellency by increasing the ignition loss, it is preferable that the loss on ignition is 34 to 49%.

  Examples of the organic bentonite whose ignition loss at 1000 ° C. is 33 to 50% are mainly composed of montmorillonite which is a natural hydrophilic layered clay mineral, and trimethylstearylammonium, dimethylstearylbenzylammonium, Examples include those obtained by reacting quaternary ammonium ions such as octadecylammonium ion to make them hydrophobic.

  Such organic bentonites are generally commercially available. For example, Sven WX (loss on ignition 39.0%), Sven N-400 (loss on ignition 39.3%), Sven NX (loss on ignition 41.8). %), Sven NZ (37.9% loss on ignition) (both products of Hojun Co., Ltd.) and the like.

  When the water absorption preventive material of the present invention is applied to civil engineering and building materials, the alkylalkoxysilane and / or the condensate thereof penetrates into the base material, while the organic bentonite remains on the base material surface. As a result, the organic bentonite acts like a so-called “lid” and suppresses the volatilization of the alkylalkoxysilane and / or its condensate that has been penetrating into the civil engineering and building materials. It is thought that it can be infiltrated. At this time, the loss on ignition when the organic bentonite is heated to 1000 ° C. is 33 to 50%, in other words, the organic component content is as high as 33 to 50%, so that the alkylalkoxysilane is arranged between the bentonite layers. The water absorption preventing material has a high viscosity. As a result, it is hardly affected by the temperature during the coating operation, can be applied well even at a high temperature of 30 ° C. or higher, and can be applied at 0 ° C. without freezing. Furthermore, since the surface water repellency becomes extremely good, not only the permeation suppression of water over a long period of time, but also the permeation suppression effect of chloride ions can be improved.

  If the loss on ignition at 1000 ° C. is less than 33%, the resulting water absorption preventive material has a low viscosity, and there is little coating amount that can be applied at one time. Loss is large and adversely affects the workability of coating. Moreover, the surface water repellency after application | coating is weak, and there is no persistence. Furthermore, a phenomenon that the effect of suppressing the penetration of chloride ions is inferior. On the other hand, when the ignition loss at 1000 ° C. exceeds 50%, the content of montmorillonite, which is a layered viscosity mineral, is reduced, so that the thickening effect is reduced. In this case, the viscosity of the obtained water absorption preventing material is also reduced. . In particular, when coating is performed under a high temperature condition of 30 ° C. or more, there are many losses due to sagging flow, which adversely affects coating workability. Moreover, the surface water repellency after application | coating is weak, and there is no persistence. Furthermore, a phenomenon that the effect of suppressing the penetration of chloride ions is inferior.

  The ratio of the organic bentonite is preferably 1 to 13% by weight of the total weight of the water absorption preventive material. From the viewpoint of improving workability by giving an appropriate viscosity to the obtained water absorption preventive material for civil engineering and building materials, 2 More preferably, it is 10 to 10 weight%, and it is especially preferable that it is 3 to 9 weight% from an economical viewpoint. If the proportion is less than 1% by weight, even if the obtained water absorption preventing material is applied to the substrate, the alkylalkoxysilane and / or the condensate thereof volatilizes and cannot penetrate deeply into the substrate. There is a possibility that the water absorption preventing performance cannot be maintained for a long time. Moreover, when a ratio exceeds 13 weight%, the viscosity of the water absorption preventive material obtained will become high too much, and there exists a possibility that the construction to a base material may become difficult.

(C) Polar solvent The polar solvent used in the present invention is not particularly limited, but includes alcohols such as methanol, ethanol and isopropyl alcohol, ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone, and nitriles such as acetonitrile. Can be mentioned. Among these, ethanol and isopropyl alcohol are preferably used from an industrial viewpoint because they are easily available industrially.

  In this invention, these polar solvents can also be used individually by 1 type, or can also use 2 or more types together.

  The proportion of the polar solvent is preferably 1 to 13% by weight based on the total weight of the water absorption preventive material. From the viewpoint of improving workability by imparting an appropriate viscosity to the obtained water absorption preventive material for civil engineering and building materials, 2 It is more preferably 10 to 10% by weight, and particularly preferably 2 to 8% by weight from the viewpoint of easy penetration deeply when applied to civil engineering and building materials. If the ratio is less than 1% by weight, the viscosity of the resulting water absorption preventing material is low, the coating amount that can be applied at one time is small, and when coating is performed under high temperature conditions of 30 ° C or more, there is a lot of loss due to dripping flow. May adversely affect workability. Also, when the ratio exceeds 13% by weight, the viscosity of the resulting water absorption preventing material is low, the coating amount that can be applied at one time is small, and further, when applied under a high temperature condition of 30 ° C. or more, there is a loss due to sagging flow. In many cases, the coating workability may be adversely affected.

(D) Hydrophobic silica powder The hydrophobic silica powder used in the present invention is not particularly limited. For example, the raw material silicon tetrachloride is produced by a dry method such as a flame method at 1000 ° C. or higher, and is hydrophilic. Examples of the silica (SiO ₂ ) obtained after surface treatment with siloxanes such as silanes, dimethyldichlorosilane, dimethylpolysiloxane, methacryloxysilane, hexamethyldisilazane, and the like can be given.

  Such hydrophobic silica powder is generally commercially available, and examples thereof include Aerosil R805, Aerosil R972, Aerosil R711, Aerosil R202, Aerosil RY50, Aerosil RY300, and Aerosil RX300 (all products of Nippon Aerosil Co., Ltd.). It is done.

  These hydrophobic silica powders may be used singly or in combination of two or more.

Furthermore, the hydrophobic silica powder used in the present invention preferably has a particle diameter of 7 to 40 μm and a specific surface area of 50 to 300 m ² / g. The particle size and specific surface area tend to be inversely proportional, and a small particle size means a large specific surface area. If this particle size is less than 7 μm (specific surface area exceeds 300 m ² / g), the surface of the civil engineering / construction material on which the obtained water absorption preventive material for civil engineering / construction material is constructed is insufficient, and the role of UV protection Function may be degraded. On the other hand, if the particle diameter exceeds 40 μm (the specific surface area is less than 50 m ² / g), the formation of irregularities on the surface of the civil engineering and building materials becomes excessive, and the design may be deteriorated. Among hydrophobic silica powders having a particle diameter of 7 to 40 μm and a specific surface area of 50 to 300 m ² / g, among the above-mentioned products on the market, Aerosil R805, Aerosil R972, Aerosil R711, Aerosil R202 (any Are products of Nippon Aerosil Co., Ltd.).

  The proportion of the hydrophobic silica powder is preferably 0.1 to 2% by weight of the total weight of the water absorption preventive material, dispersibility when preparing the water absorption preventive material for civil engineering and building materials, and obtained for civil engineering and building materials. From the viewpoint of civil engineering and building material surface protection in which a water absorption preventing material is applied, it is more preferably 0.2 to 1.8% by weight, and particularly from an economic viewpoint, it is 0.3 to 1.5% by weight. preferable. When the ratio is less than 0.1% by weight, the dispersibility of the organic bentonite is poor, and it takes time to prepare the water absorption preventing material, and the water repellency after construction may be lowered. On the other hand, if the ratio exceeds 2% by weight, powdering at the time of preparing the water absorption preventing material is intense, and the working environment may be deteriorated.

  The water absorption preventive material for civil engineering and building materials of the present invention includes, for example, (A) an alkylalkoxysilane and / or a condensate thereof, (B) an organic bentonite, (C) a polar solvent, and (D) a hydrophobic silica powder at room temperature. Below, it can manufacture by carrying out mixing and dispersion | distribution using stirrers with strong shearing force, such as a homomixer, an ultradisperser, and a high-pressure homogenizer.

The viscosity of the water absorption preventive material for civil engineering and building materials of the present invention is preferably 1,000 to 10,000 mPa · s, more preferably 1,100 to 7,000 mPa · s at 20 ° C. If the viscosity at 20 ° C. is less than 1,000 mPa · s, a viscosity of 500 mPa · s or more cannot be secured when the temperature during the application operation is 30 ° C. or more, and 200 g or more is applied per 1 m ² by one application. It may be difficult to do so and workability may be adversely affected. On the other hand, if the viscosity at 20 ° C. exceeds 10,000 mPa · s, the fluidity is lost and the coating operation may be difficult.

  The viscosity in the present invention is a B-type viscometer (manufactured by Tokyo Keiki Co., Ltd.), measuring temperature 20 ° C., rotor No. 4. The value measured under the condition of 30 rpm.

  When preparing the water absorption preventing material for civil engineering and building materials of the present invention, a preservative, a fungicide, an algae, an ant, an ultraviolet absorber and the like may be added as a secondary agent.

  In order to apply the water absorption preventive material of the present invention to civil engineering and building materials, any of rollers, brushes, sprays, and the like can be used, but application with a mastic roller is preferred. Moreover, as a drying method after coating, it may be allowed to stand at room temperature for drying, or may be sun drying or heat drying.

In general, the water absorption preventing material for civil engineering and building materials of the present invention can be applied in an amount of 300 to 500 g per 1 m ² at a time. Further, even if re-application is performed on the surface once applied, it can be applied two or more times without causing repelling because it does not contain water in the composition. The penetration depth at this time increases as the number of coatings increases. Due to this feature, the water absorption preventive material for civil engineering and building materials of the present invention is not only applied to newly constructed civil engineering and building materials, but is also reapplied after several years to the civil engineering and building materials to which the water absorbing preventive material of the present invention is applied when newly installed. It is also possible.

  Civil engineering and building materials to which the water absorption preventing material of the present invention is applied include, for example, exposed concrete, lightweight concrete, precast concrete, lightweight foamed concrete (ALC), mortar, joint mortar, asbestos cement board, pulp cement board, wood wool cement board , Cement-based extruded plate, glass fiber cement plate (GRC), carbon fiber cement plate, calcium silicate plate, gypsum board, hardboard, plaster, gypsum plaster, dolomite plaster, block, brick, tile, tile, natural stone, Artificial stone, glass wool, rock wool, ceramic fiber and the like can be mentioned. Moreover, even if it uses for the material which has organic materials, such as a timber, a plywood, and a particle board, the water absorption preventive material of this invention does not have a problem.

  The water absorption preventive material for civil engineering and building materials of the present invention is hardly affected by the temperature at the time of application work, and can be applied in a temperature range of 0 ° C to 40 ° C. In addition, when the water absorption preventive material for civil engineering and building materials of the present invention is applied, it has good water repellency and permeability to the inside of the base material, resulting in rainwater leakage due to severe wind and rain, material deterioration due to acid rain, contamination of soil, seawater In addition, various problems caused by salt damage caused by an antifreezing agent, frost damage in a cold region, water such as white flower caused by elution of salt in a material can be solved over a long period of time.

  The reason why the water absorption preventing material for civil engineering and building materials of the present invention forms a deep permeation layer and imparts high water repellency is not clear, but is presumed to be based on the following. That is, by applying a high concentration of alkylalkoxysilane and / or its condensate on the surface of civil engineering and building materials, a deeper permeable water absorption preventing layer is formed. Since the uneven layer is formed on the surface of the material, it is considered that not only high water repellency is imparted, but also a protective layer resistant to ultraviolet rays, temperature, salt and the like can be formed.

  The water absorption preventive material of the present invention is very excellent in permeability to civil engineering and building materials, and provides a high water repellency by forming a deep osmotic layer on the surface layer of civil engineering and building materials, and also provides water for a very long period of time. In addition, it can prevent the invasion of salt and the like, and can protect civil engineering and building materials for a long time without changing the material base and texture.

  EXAMPLES Hereinafter, although this invention is demonstrated in more detail with an Example and a comparative example, this invention is not limited to these Examples at all.

Example 1
90 parts by weight of decyltrimethoxysilane, 6 parts by weight of organic bentonite (“Esven N-400” manufactured by Hojun Co., Ltd., 39.3% loss on ignition at 1000 ° C.), 3.5 parts by weight of isopropyl alcohol, and hydrophobic silica 0.5 parts by weight of powder (“Aerosil R972” manufactured by Nippon Aerosil Co., Ltd.) was stirred at high speed using a homomixer to obtain the water absorption preventing material of the present invention. The solution viscosity at 20 ° C. of the obtained water absorption preventing material was 1,600 mPa · s, and the solution viscosity at 30 ° C. was 1,100 mPa · s.

Example 2
88 parts by weight of octyltriethoxysilane, 7 parts by weight of organic bentonite (“Esben NX” manufactured by Hojun Co., Ltd., 41.8% loss on ignition at 1000 ° C.), 4 parts by weight of isopropyl alcohol, and hydrophobic silica powder (Nippon Aerosil) 1 part by weight of “Aerosil R805” manufactured by Co., Ltd. was stirred at high speed using a homomixer to obtain the water absorption preventing material of the present invention. The resulting water absorption preventing material had a solution viscosity at 20 ° C. of 2,000 mPa · s and a solution viscosity at 30 ° C. of 1,500 mPa · s.

Example 3
90 parts by weight of hexyltrimethoxysilane, 7 parts by weight of organic bentonite (“Esben NX” manufactured by Hojun Co., Ltd., 41.8% loss on ignition at 1000 ° C.), 2 parts by weight of isopropyl alcohol, and hydrophobic silica powder (Nippon Aerosil) 1 part by weight of “Aerosil R805” manufactured by Co., Ltd. was stirred at high speed using a homomixer to obtain the water absorption preventing material of the present invention. The resulting water absorption preventing material had a solution viscosity at 20 ° C. of 2,000 mPa · s and a solution viscosity at 30 ° C. of 1,500 mPa · s.

Comparative Example 1
A mixed solution of 90 parts by weight of hexyltrimethoxysilane, 9 parts by weight of isopropyl alcohol, and 1 part by weight of hydrophobic silica powder (“Aerosil R805” manufactured by Nippon Aerosil Co., Ltd.) was prepared to obtain a water absorption preventing material. The solution viscosity at 20 ° C. of the water absorption preventing material was 30 mPa · s, and the solution viscosity at 30 ° C. was 20 mPa · s.

Comparative Example 2
85 parts by weight of hexyltrimethoxysilane, 10 parts by weight of organic bentonite (“Organite” manufactured by Hojun Co., Ltd., 28.9% loss on ignition at 1000 ° C.), 4 parts by weight of ethanol, and hydrophobic silica powder (Nippon Aerosil ( 1 part by weight of “Aerosil R805” manufactured by the same company was stirred at high speed using a homomixer to obtain a water absorption preventing material. The resulting water absorption preventing material had a solution viscosity at 20 ° C. of 680 mPa · s and a solution viscosity at 30 ° C. of 300 mPa · s.

Comparative Example 3
85 parts by weight of octyltrimethoxysilane, 11 parts by weight of organic bentonite (“Esben” manufactured by Hojun Co., Ltd., 29.9% loss on ignition at 1000 ° C.), 3.9 parts by weight of isopropyl alcohol, and hydrophobic silica powder (Japan) 0.1 part by weight of “Aerosil R805” manufactured by Aerosil Co., Ltd. was stirred at high speed using a homomixer to obtain a water absorption preventing material. The resulting water absorption preventing material had a solution viscosity at 20 ° C. of 830 mPa · s and a solution viscosity at 30 ° C. of 450 mPa · s.

Comparative Example 4
88 parts by weight of hexyltrimethoxysilane, 10 parts by weight of organic bentonite (“Esben NZ70” manufactured by Hojun Co., Ltd., 51.4% loss on ignition at 1000 ° C.), 3 parts by weight of isopropyl alcohol, and hydrophobic silica powder (Nippon Aerosil) 1 part by weight of “Aerosil R805” manufactured by Co., Ltd. was stirred at high speed using a homomixer to obtain a water absorption preventing material. The solution viscosity at 20 ° C. of the obtained water absorption preventing material was 500 mPa · s, and the solution viscosity at 30 ° C. was 100 mPa · s.

Comparative Example 5
Using a homomixer, 90 parts by weight of hexyltrimethoxysilane, 7 parts by weight of organic bentonite (“Esben NX” manufactured by Hojun Co., Ltd., 41.8% loss on ignition at 1000 ° C.), and 3 parts by weight of isopropyl alcohol were mixed at high speed. The water absorption preventive material was obtained by stirring. The solution viscosity at 20 ° C. of the obtained water absorption preventing material was 1,800 mPa · s, and the solution viscosity at 30 ° C. was 1,200 mPa · s.

[Test example]
A mortar plate according to JIS R 5201 (70 × 70 × 20 mm) dried at 60 ° C. for 48 hours was used as a specimen, and the water absorption preventive material obtained in Examples and Comparative Examples was used as the test sample. It apply | coated once on the surface of x70 mm (only 1 surface is apply | coated). When the coating amount at this time did not reach 400 g / m ² , overcoating was performed again, and overcoating was performed until the final coating amount reached 400 g / m ² . The obtained specimen was cured for 7 days in a constant temperature and humidity chamber at a temperature of 20 ° C. and a relative humidity of 65% RH, and then water repellency, penetration depth, water absorption ratio, water absorption ratio in alkaline water, and chloride ion penetration depth. Was measured. At this time, the control was nothing applied. In addition, before each measurement, four surfaces (70 × 20 mm surfaces) serving as side surfaces when the coated surface was the upper surface were sealed with an epoxy resin. The measurement method of each item is as follows, and the water repellency and the water absorption ratio were measured before and after the accelerated weather resistance test.

(1) Water Repellency A 2 mm diameter water drop was placed on the specimen, and the contact angle was measured with a contact angle measuring device (Kyowa Interface Science Co., Ltd., contact angle meter S-150). The evaluation criteria were as follows.
◎: Water droplet contact angle of 135 ° or more ○: Water droplet contact angle of less than 120 to 135 ° △: Water droplet contact angle of less than 80 to 120 ° ×: Immediate water absorption without forming water droplets When the angle is 135 ° or more, it can be determined that the water repellency is very excellent. The results are shown in Table 1.

  Further, the specimen was used with a sunshine weather meter (trade name of Suga Test Instruments Co., Ltd .: Ducycle sunshine super long life weather meter WEL-SUN-DCH type), black panel temperature: 63 ° C., humidity: 50%. Rainfall conditions: The accelerated weather resistance test was conducted for 5,000 hours under the test conditions of rain for 12 minutes out of 60 minutes. The water repellency of the specimen after the accelerated weathering test was evaluated in the same manner as described above. The results are shown in Table 1.

(2) Penetration depth The test piece of 70 × 70 × 20 mm is divided into two so that two pieces of 70 × 35 × 20 mm in size can be obtained, and water is sprayed on the divided surface, so that the water absorption preventing material penetrates. The thickness of the portion (the portion where water does not penetrate) was measured. The results are shown in Table 1.

(3) Water absorption ratio Specimens and uncoated specimens were immersed in water with the coating surface down (immersion depth 5 mm), taken out of the water after one day, and excess water was wiped off with a dry cloth, and then weight (G) was measured and the water absorption ratio was calculated by the following equation.
Water absorption ratio = [weight of the coated specimen after water immersion (g) −weight of the coated specimen before water immersion (g)] / [weight of the uncoated specimen after water immersion (g) −uncoated specimen Weight before water immersion (g)]
In addition, when a water absorption ratio is 0.1 or less, it can be judged that it is excellent in water absorption prevention property. The results are shown in Table 1.

  Further, the water absorption ratio of the specimen after the accelerated weather resistance test was performed for 5,000 hours in the same manner as described above was evaluated in the same manner as described above. The results are shown in Table 1.

(4) Water absorption ratio in alkaline water The test specimen and the uncoated specimen were immersed in a saturated Ca (OH) ₂ aqueous solution with the coated surface down (immersion depth 5 mm), and taken out from the solution after 1 day. After the excess liquid was wiped off with a dry cloth, the weight (g) was measured, and the water absorption ratio was calculated by the following equation.
Water absorption ratio = [weight after immersion of coated specimen (g) −weight before immersion of coated specimen (g)] / [weight after immersion of uncoated specimen (g) −before immersion of uncoated specimen Weight (g)]
In addition, when a water absorption ratio is 0.1 or less, it can be judged that it is excellent in water absorption prevention property. The results are shown in Table 1.

(5) Chloride ion penetration depth After the specimen was immersed in a 3% NaCl aqueous solution for 30 days with the coated surface down, the specimen was divided into two parts, and a 0.1 N-AgNO ₃ solution and A 0.1% sodium fluorescein solution was sprayed, and the thickness of the colored portion (portion where chloride ions permeated) was measured. In addition, when the penetration depth of chloride ions is 2 mm or less, it is judged that the salt blocking property is very excellent. The results are shown in Table 1.

  From Table 1, the water absorption preventing materials of Examples 1 to 3 are effective in reducing the water absorption ratio in alkaline water and suppressing the penetration of chloride ions because the water repellency is good and the penetration depth is deep. Further, it can be seen that the water absorption preventing performance can be maintained over a long period of time.

Claims (5)

  (A) alkylalkoxysilane and / or its condensate, (B) an organic bentonite obtained by reacting montmorillonite with a quaternary ammonium ion and having a loss on ignition at 1000 ° C. of 33 to 50%, (C) A water absorption preventing material for civil engineering and building materials comprising a polar solvent and (D) hydrophobic silica powder.   (A) An alkylalkoxysilane and / or its condensate 85 to 95% by weight, (B) an organic compound obtained by reacting montmorillonite with a quaternary ammonium ion and having an ignition loss at 1000 ° C. of 33 to 50% The water absorption preventive material for civil engineering and building materials according to claim 1, comprising 1 to 13% by weight of bentonite, (C) 1 to 13% by weight of a polar solvent, and (D) 0.1 to 2% by weight of hydrophobic silica powder. The alkylalkoxysilane is represented by the general formula (1);
R ¹ _n Si (OR ² ) _4-n (1)
(Wherein R ¹ represents an alkyl group having 1 to 20 carbon atoms, R ² represents an alkyl group having 1 to 4 carbon atoms, and n is 1 or 2). The water absorption preventing material for civil engineering and building materials according to 1 or 2.   The water absorption preventive material for civil engineering and building materials according to any one of claims 1 to 3, wherein the polar solvent is alcohol.   The water absorption preventing material for civil engineering and building materials according to any one of claims 1 to 4, wherein the viscosity at 20 ° C is 1,000 to 10,000 mPa · s.