JP5901143B2 - Water absorption prevention material for civil engineering and building materials - Google Patents

Description

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

Conventionally, it is widely known that alkylalkoxysilanes and / or condensates thereof are useful as water absorption preventing materials for civil engineering and building materials. Generally, these alkylalkoxysilanes and / or condensates thereof are used. An organic solvent type water absorption preventing material diluted with various organic solvents, an emulsion type water absorption preventing material obtained by emulsifying an alkylalkoxysilane and / or its condensate in water, and the like are used. However, most of the organic solvent type or emulsion type water absorption preventive materials have an active ingredient of 50% by mass or less and the remainder is occupied by the organic solvent or water, so the solution viscosity is as low as less than 100 mPa · s, The amount of active ingredient that can be applied at one time is as low as 40 to 80 g / m ² . Therefore, in order to apply a specified amount (about 200 to 300 g / m ² ), it is necessary to apply ^two to five times. In addition, since the viscosity is low, 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, so there are many restrictions in terms of workability and problems. It has become. Furthermore, when these organic solvent-type or emulsion-type water absorption preventing materials are applied to the substrate, the alkylalkoxysilane and / or a part of the condensate thereof volatilizes out of the substrate. In addition, the entire amount of the condensate and / or the condensate thereof cannot be infiltrated into the base material, and there is a problem that a deep permeation layer of the 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 problems, 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, when this water absorption preventing material is applied to the surface of a civil engineering and building material, the swollen inorganic mineral is dried and contracted to generate cracks on the coated surface. In particular, at a low temperature such as winter, the degree of shrinkage tends to be large, and cracks tend to increase. When cracks occur on the coated surface, the coating film is peeled off or whitened, resulting in a problem that the design of the appearance is deteriorated.

JP 2003-221576 A

  The object of the present invention is not only to maintain water absorption prevention performance for a long period of time when applied to civil engineering and building materials, but also to prevent peeling and whitening of the coating surface, and to prevent water absorption that can obtain a deeper penetration depth To provide materials.

  As a result of intensive studies in view of the above problems, the present inventors have found that alkylalkoxysilane and / or its condensate (A), thixotropic agent (B), polar solvent (C) and hydrophobic silica powder (D). Using the water absorption preventive material that includes not only maintaining water absorption preventive performance for a long time, but also preventing the occurrence of cracks on the coated surface, preventing peeling and whitening of the coating film, and obtaining a deeper penetration depth I found that I can do it. The present invention has been completed by further research based on such knowledge.

That is, this invention includes the civil engineering building material by which the water absorption preventing material for civil engineering and building materials which concerns on the following items 1-10, and this absorption inhibiting material for civil engineering and building materials were apply | coated.
Item 1. (A) an alkylalkoxysilane and / or a condensate thereof,
(B) thixotropic agent,
0 to 5 parts by mass of (C) polar solvent with respect to 100 parts by mass of the alkylalkoxysilane and / or its condensate (A), and 100 parts by mass of the alkylalkoxysilane and / or its condensate (A). Water-absorbing material for civil engineering and building materials comprising 0 to 2 parts by mass of (D) hydrophobic silica powder.
Item 2. The water absorption for civil engineering and building materials according to Item 1, wherein the content of the thixotropic agent (B) is 0.1 to 20 parts by mass with respect to 100 parts by mass of the alkylalkoxysilane and / or its condensate (A). Prevention material.
Item 3. The water absorption prevention for civil engineering and building materials according to Item 1 or 2, wherein the content of the polar solvent (C) is 1 to 5 parts by mass with respect to 100 parts by mass of the alkylalkoxysilane and / or its condensate (A). Wood.
Item 4. The content of the hydrophobic silica powder (D) is 0.1 to 2 parts by mass with respect to 100 parts by mass of the alkylalkoxysilane and / or its condensate (A), Water absorption prevention material for civil engineering and building materials.
Item 5. The alkylalkoxysilane has the general formula (1):
R ¹ _n Si (OR ² ) _4-n (1)
(Wherein n R ^{1 s} are the same or different and each may have a substituent, each having 1 to 20 carbon atoms; 4-n R ^{2 s} are the same or different and each have a carbon number; 1-4 alkyl groups; n is 1 or 2)
Item 5. The water absorption preventive material for civil engineering and building materials according to any one of Items 1 to 4, which is a compound represented by:
Item 6. Item 6. The water absorption preventing material for civil engineering and building materials according to Item 5, wherein the substituent that R ¹ may have is a vinyl group, an epoxy group, a methacryloxy group, an acryloxy group, an amino group, a chloropropyl group, or an isocyanate group. .
Item 7. Item 7. The water absorption preventing material for civil engineering and building materials according to any one of Items 1 to 6, wherein the polar solvent (C) is alcohol.
Item 8. The water absorption preventive material for civil engineering and building materials according to any one of Items 1 to 7, wherein the viscosity at 20 ° C is from 100 to 10,000 mPa · s.
Item 9. The civil engineering building material with which the water absorption preventive material for civil engineering building materials in any one of claim | item 1 -8 was apply | coated.

  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 the following general formula (1):
R ¹ _n Si (OR ² ) _4-n (1)
(Wherein n R ^{1 s} are the same or different and each may have a substituent, each having 1 to 20 carbon atoms; 4-n R ^{2 s} are the same or different and each have a carbon number; 1-4 alkyl groups; n is 1 or 2)
Is preferably used.

Examples of the alkyl group having 1 to 20 carbon atoms in R ¹ include, for example, methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, Examples include dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, and octadecyl group. Among these, from the viewpoint of increasing the water-absorbing property of the water-absorbing material for civil engineering and building materials obtained, since the hydrophobicity of the substituent is high, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group Groups and the like are preferred.

The alkyl group having 1 to 20 carbon atoms in R ¹ may have a substituent. Specific examples of such a substituent include a vinyl group, an epoxy group, a methacryloxy group, an acryloxy group, an amino group, a chloropropyl group, and an isocyanate group. When these substituents are included, the number of substituents is usually one.

Examples of the alkyl group having 1 to 4 carbon atoms in R ² include a methyl group, an ethyl group, a propyl group, and a butyl group. Among these, a methyl group, an ethyl group, a propyl group, and the like are preferable from the viewpoint of high reactivity of the alkylalkoxysilane, easy condensation, and high water absorption prevention properties of the resulting water absorption prevention 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 Decyltriethoxysilane, heptadecyltrimethoxysilane, heptadecyltriethoxysilane, octadecyltrimethoxysilane, octadecyltriethoxysilane, dimethyldimethoxysilane, octylmethyldimethoxysilane, octadecylmethyldimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxy Lan, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, N-2- (aminoethyl) -3-aminopropylmethoxy Silane, N-2- (aminoethyl) -3-aminopropylethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-chloropropyltrimethoxysilane, 3-isocyanatopropylate Silane and the like.

Among these, it is easy to obtain, and from the viewpoint of increasing the water absorption preventing property of the obtained water absorption preventing material for civil engineering and building materials, the alkyl group represented by R ¹ in the general formula (1) has 6 or more carbon atoms. In addition, hexyltrimethoxysilane, hexyltriethoxysilane, octyltrimethoxysilane, octyltriethoxysilane, decyltrimethoxysilane, or the like having 1 to 3 carbon atoms in the alkyl group represented by R ² are preferably used. These alkyl alkoxysilanes can also be used as a partial condensate or a mixture. Furthermore, these alkyl alkoxysilanes and / or their condensates may be used alone or in combination of two or more.

(B) Thixotropic agent As the thixotropic agent (B), specifically, hydrogenated castor oil type, amide wax type, polyethylene oxide type, polyolefin type, sulfate ester type, dimer acid ester type, polycarboxylic acid type, Examples include organic thixotropic agents such as vegetable oil polymerized oils. These thixotropic agents may be used alone or in combination of two or more. Among these, an amide wax type thixotropic agent having good compatibility with the alkylalkoxysilane and / or its condensate (A) and being easily swelled is preferable. Although there are inorganic thixotropic agents as thixotropic agents, it is preferable to use organic thixotropic agents from the viewpoint of improving peeling and whitening.

  As the thixotropic agent (B), a known one may be used, or a commercially available one may be used. As what is marketed, for example, Talen 5400-25 (manufactured by Kyoeisha Chemical Co., Ltd .; Amide Wax), Talen 5500-25 (manufactured by Kyoeisha Chemical Co., Ltd .; Amide Wax), Flownon SA-300 (Kyoeisha) Chemical Co., Ltd .; polyethylene oxide), Disparon (registered trademark) 4300 (manufactured by Enomoto Kasei Co., Ltd .; hydrogenated castor oil), Disparon (registered trademark) 6820-20M (manufactured by Enomoto Kasei); Amide wax ), Disparon (registered trademark) 4200-20 (manufactured by Enomoto Kasei Co., Ltd .; polyethylene oxide type), A-S-A T-20 (manufactured by Ito Oil Co., Ltd .; hydrogenated castor oil system), A-S-A T-1700 (made by Ito Oil Co., Ltd .; Amide wax type), ASAD-10A (made by Ito Oil Co., Ltd .; polyethylene oxide type), etc. are mentioned. It is. Among these, Talen 5400-25 and Disparon (registered trademark) 6820-20M are particularly good.

  By including the thixotropic agent (B), the penetration depth can be improved when the water absorption preventing material of the present invention is applied to civil engineering and building materials. The reason is not necessarily clear, but is considered as follows. When the water absorption preventing material of the present invention is applied to civil engineering and building materials, the alkylalkoxysilane and / or its condensate (A) penetrates into the civil engineering and building materials. On the other hand, the thixotropic agent (B) remains on the civil engineering and building material surface. In particular, when organic thixotropic agents are used as the thixotropic agent (B), these have a large molecular weight, so that they tend to hardly penetrate into civil engineering and building materials. As a result, the thixotropic agent (B) acts like a so-called “lid” and suppresses the volatilization of the alkylalkoxysilane and / or its condensate (A) that is penetrating into the civil engineering and building materials. In addition, almost all of the alkylalkoxysilane and / or its condensate (A) can penetrate into the civil engineering and building materials, and since the alkylalkoxysilane and / or its condensate (A) is less likely to volatilize, it prevents water absorption. Can be maintained for a long time.

  The content of the thixotropic agent (B) can appropriately increase the viscosity to facilitate application to civil engineering and building materials, deepen the penetration depth, and maintain water absorption prevention performance for a longer time. From the viewpoint, 0.1 to 20 parts by mass is preferable with respect to 100 parts by mass of the alkylalkoxysilane and / or its condensate (A), and workability is obtained by giving an appropriate viscosity to the obtained water absorption preventing material for civil engineering and building materials. 5 to 15 parts by mass is more preferable from the viewpoint of improving the viscosity.

(C) Polar solvent In the present invention, the polar solvent (C) is not necessarily essential, but the viscosity of the water-absorbing material for civil engineering and building materials to be obtained is appropriately controlled to increase the amount of application at one time. It is preferable that the polar solvent (C) is contained because the property can be improved.

  The polar solvent (C) used in the present invention is not particularly limited, and examples thereof include alcohols such as methanol, ethanol and isopropyl alcohol; ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone; and nitriles such as acetonitrile. . Among these, alcohols, particularly ethanol, isopropyl alcohol, and the like are preferably used from the viewpoint of industrial availability and economic efficiency. These polar solvents (C) may be used individually by 1 type, and may be used in combination of 2 or more type.

  The content of the polar solvent (C) is moderately increased from the viewpoint of facilitating application to civil engineering and building materials, and relative to 100 parts by mass of the alkylalkoxysilane and / or its condensate (A). 0-5 mass parts is preferable, and 1-3 mass parts is more preferable from a viewpoint which gives moderate viscosity to the water absorption preventive material for civil engineering and building materials obtained, and improves workability | operativity.

(D) Hydrophobic silica powder In the present invention, the hydrophobic silica powder (D) is not necessarily essential, but improves the dispersibility of the thixotropic agent (B) and improves water absorption prevention after construction. Therefore, it is preferable to include the hydrophobic silica powder (D).

The hydrophobic silica powder (D) 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 hydrophilic silica (SiO 2). ₂ ) After obtaining, silanes; those treated with siloxanes such as dimethyldichlorosilane, dimethylpolysiloxane, methacryloxysilane, hexamethyldisilazane, and the like are listed.

  Such hydrophobic silica powder (D) is generally commercially available. For example, Aerosil (registered trademark) R805, Aerosil (registered trademark) R972, Aerosil (registered trademark) R711, Aerosil (registered trademark) R202, Aerosil ( Registered trademark) RY50, Aerosil (registered trademark) RY300, Aerosil (registered trademark) RX300 (all are products of Nippon Aerosil Co., Ltd.), and the like. These hydrophobic silica powders (D) may be used alone or in combination of two or more.

Furthermore, the hydrophobic silica powder (D) used in the present invention sufficiently exhibits the role function of protecting from ultraviolet rays by sufficiently forming irregularities on the civil engineering and building material surface on which the obtained water absorption preventive material is constructed, From the viewpoint of not deteriorating the designability and not affecting workability, it is particularly preferable that the average secondary particle diameter is 7 to 40 μm and the specific surface area is 50 to 300 m ² / g. The particle diameter and the specific surface area tend to be inversely proportional, and a small particle diameter means that the specific surface area is large. The particle diameter of the hydrophobic silica powder (D) can be measured by, for example, a Coulter counter or a laser diffraction particle size distribution measuring method, and the specific surface area can be measured by, for example, the BET method. As the hydrophobic silica powder (D) having a particle size of 7 to 40 μm and a specific surface area of 50 to 300 m ² / g, among the commercially available products, Aerosil (registered trademark) R805, Aerosil ( Registered Trademark) R972, Aerosil (Registered Trademark) R711, Aerosil (Registered Trademark) R202 (all of which are products of Nippon Aerosil Co., Ltd.).

  The content of the hydrophobic silica powder (D) improves the dispersibility of the thixotropic agent (B) and suppresses powdering to facilitate the preparation of the water absorption preventing material, and improves the water absorption preventing property after construction. From the viewpoint, 0 to 2 parts by mass, particularly 0.1 to 2 parts by mass is preferable with respect to 100 parts by mass of the alkylalkoxysilane and / or its condensate (A), and when preparing a water absorption preventing material for civil engineering and building materials From the viewpoint of protecting the surface of civil engineering and building materials on which the obtained water absorption preventive material is constructed, 0.2 to 1.5 parts by mass is more preferable, and from an economic viewpoint, 0.3 to 1.5 parts by mass are preferable. Particularly preferred.

  The water absorption preventive material for civil engineering and building materials of the present invention includes, for example, alkylalkoxysilane and / or its condensate (A) and thixotropic agent (B), and optionally a polar solvent (C), and hydrophobic silica powder. (D) can be produced by mixing and dispersing at room temperature using a stirrer having a strong shearing force such as a homomixer, an ultra dissolver, or a high-pressure homogenizer.

  The viscosity of the water-absorbing material for civil engineering and building materials of the present invention is preferably 100 to 10,000 mPa · s at 25 ° C., from the viewpoint of improving the fluidity and improving workability while sufficient coating amount for one application. 500 to 7000 mPa · s is more preferable. The viscosity in the present invention is, for example, a B-type viscometer (manufactured by Tokyo Keiki Co., Ltd.), measuring temperature 25 ° 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, conventionally known or commercially available antiseptics, fungicides, algaeproofing agents, antproofing agents, ultraviolet absorbers and the like are added as secondary agents. Also good.

  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 200 to 500 g per 1 m ² . Moreover, even if it is reapplied to the surface once applied, it can be applied twice or more 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 during application work, and can be applied in a temperature range of 0 to 40 ° C. In addition, when the water absorption preventive material for civil engineering and building materials of the present invention is applied, due to good water absorption prevention and penetration into the base material, rainwater leakage due to severe wind and rain, deterioration of the material due to acid rain, impregnation of dirt, Various problems caused by saltwater damage caused by seawater and antifreezing agents, frost damage in cold regions, white water caused by elution of salt in materials, and the like 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 can prevent the occurrence of cracks on the coated surface is not clear, but is presumed to be based on the following. That is, normally, immediately after application of the water absorption preventing material for civil engineering and building materials, the swollen inorganic mineral is dried and contracted, and cracks occur on the coated surface. In particular, this tendency becomes large in winter, often causing peeling, whitening, and the like, and the appearance is often impaired. At this time, if the water absorption preventive material for civil engineering and building materials contains a thixotropic agent instead of an inorganic mineral, it is presumed to be gentle and slow drying and to promote the penetration of the water absorption preventive component into the inside of the frame. .

  The water absorption preventive material of the present invention is very excellent in permeability to civil engineering and building materials, and by providing a deep penetration layer in the surface layer portion of the civil engineering and building materials, it imparts high water absorption preventive properties and for a very long time. In order to prevent the intrusion of water, salt, etc., and also to prevent the occurrence of cracks on the coating surface, and to prevent peeling and whitening of the coating film, civil engineering and building materials can be used for a long time without changing the material base and texture. Can be protected.

  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
Decyltrimethoxysilane 100 parts by mass, thixotropic agent ("Dispalon (registered trademark) 6820-20M" manufactured by Enomoto Kasei Co., Ltd.); 7.7 parts by mass, isopropyl alcohol 1.6 parts by mass and hydrophobicity 0.5 parts by mass of silica powder (“Aerosil (registered trademark) 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 25 ° C. of the obtained water absorption preventing material was 700 mPa · s.

Example 2
100 parts by weight of octyltrimethoxysilane, 8.9 parts by weight of a thixotropic agent (“Tarene 5400-25” manufactured by Kyoei Chemical Co., Ltd .; Amide wax system), 1.1 parts by weight of isopropyl alcohol and hydrophobic silica powder (Japan) 1.1 parts by mass of “Aerosil (registered trademark) R805” manufactured by 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 25 ° C. of the obtained water absorption preventing material was 1000 mPa · s.

Example 3
100 parts by weight of hexyltrimethoxysilane, 7.7 parts by weight of a thixotropic agent (“Tarene 5400-25” manufactured by Kyoei Chemical Co., Ltd .; amide wax system), 1.7 parts by weight of isopropyl alcohol and hydrophobic silica powder (Japan) 1.1 parts by mass of “Aerosil (registered trademark) R805” manufactured by 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 25 ° C. of the obtained water absorption preventing material was 800 mPa · s.

Comparative Example 1
100 parts by weight of octyltriethoxysilane, 8.9 parts by weight of organic bentonite (“Esben N-400” manufactured by Hojun Co., Ltd.), 1.1 parts by weight of isopropyl alcohol and hydrophobic silica powder (manufactured by Nippon Aerosil Co., Ltd.) 1.1 parts by weight of “Aerosil (registered trademark) R805”) was stirred at high speed using a homomixer to obtain a comparative water absorption preventing material. The solution viscosity at 25 ° C. of the obtained water absorption preventing material was 1500 mPa · s.

Comparative Example 2
100 parts by weight of hexyltrimethoxysilane, 7.8 parts by weight of organic bentonite (“Esben NX” manufactured by Hojun Co., Ltd.), 2.2 parts by weight of dimethyl sulfoxide and “Aerosil (manufactured by Nippon Aerosil Co., Ltd.)” (Registered trademark) R805 ") 1.1 parts by mass were stirred at high speed using a homomixer to obtain a comparative water absorption preventing material. The solution viscosity at 25 ° C. of the obtained water absorption preventing material was 1600 mPa · s.

Comparative Example 3
100 parts by mass of hexyltrimethoxysilane, 1.7 parts by mass of isopropyl alcohol and 1.1 parts by mass of hydrophobic silica powder (“Aerosil (registered trademark) R805” manufactured by Nippon Aerosil Co., Ltd.) are stirred at high speed using a homomixer. Thus, a water absorption preventing material for comparison was obtained. The solution viscosity at 25 ° C. of the obtained water absorption preventing material was 30 mPa · s.

[Test Example 1]
A mortar plate according to JIS R 5201 (70 mm × 70 mm × 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 a 70 mm mortar plate. A 300 g / m ² coating was applied to a 70 mm surface (applying only one surface). The obtained specimen was cured for 7 days in a thermostatic oven at a temperature of 23 ° C. and a relative humidity of 50% RH, and then the penetration depth and the water absorption ratio were measured.

  The measurement method for each item is as follows. Before each measurement, four surfaces (70 mm × 20 mm surfaces) which are side surfaces when the coated surface is the top surface were sealed with an epoxy resin. In the evaluation of the water absorption ratio, an uncoated sample was used as a control. Further, the water absorption ratio was measured before and after the accelerated weathering test.

(1) Penetration depth 70 mm x 70 mm x 20 mm test piece is divided into two so that two of 70 mm x 35 mm x 20 mm can be obtained, water is sprayed on the divided surface, and 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.

(2) Water absorption ratio The test specimen and the uncoated specimen were immersed in water with the coating surface down (immersion depth 5 mm), taken out from the water after one day, and the excess water was wiped off with a dry cloth. (G) was measured and the water absorption ratio was calculated by the following equation.

  Water absorption ratio = [mass after water immersion of coated specimen (g) −mass before water immersion of coated specimen (g)] / [mass after water immersion of uncoated specimen (g) −uncoated specimen Mass before water immersion (g)]

  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 carried out for 2000 hours under the test conditions of rain for 12 minutes in 60 minutes. The water absorption ratio of the specimen after the accelerated weather resistance test was evaluated in the same manner as described above. The results are shown in Table 1.

  In addition, when both the water absorption ratio before an accelerated weathering test and after an accelerated weathering test are 0.1 or less (especially 0.05 or less), it can be judged that it is excellent in water absorption prevention property. The results are shown in Table 1.

[Test Example 2]
Use a mortar plate (70 mm x 70 mm x 20 mm) according to JIS R 5201 for 24 hours in a thermostatic oven at a temperature of 10 ° C (trade name of Espec Co., Ltd .: Platinums K-PL). Then, 300 g / m ^{2 of} the water absorption preventing material obtained in Examples and Comparative Examples was applied to a 70 mm × 70 mm surface of the mortar plate (only one surface was applied). The obtained specimen was cured for 1 month in a constant temperature and humidity chamber at 10 ° C., and then the state of peeling and whitening was observed.

(3) Peeling and whitening test The coated surface of the obtained specimen was visually observed. The evaluation criteria were as follows. The results are shown in Table 1.
Evaluation of peeling ○: No peeling on the specimen surface ×: Evaluation of whitening where peeling occurs on the specimen surface ○: No whitening on the specimen surface ×: Whitening occurs on the specimen surface

  From Table 1, the water absorption preventing materials of Examples 1 to 3 not only maintain the water absorption preventing performance for a long period of time, but also prevent the occurrence of cracks on the coating surface, prevent peeling and whitening of the coating film, and even deeper It can be seen that the penetration depth is obtained.

Claims (5)

(A) an alkylalkoxysilane and / or a condensate thereof,
0.1 to 20 parts by mass of (B) hydrogenated castor oil type, amide wax type, polyethylene oxide type, polyolefin type, sulfate ester type, based on 100 parts by mass of the alkyl alkoxysilane and / or its condensate (A) , At least one organic thixotropic agent selected from the group consisting of dimer acid ester-based, polycarboxylic acid-based, and vegetable oil polymerized oil-based thixotropic agents;
1 to 5 parts by mass of (C) polar solvent with respect to 100 parts by mass of the alkylalkoxysilane and / or its condensate (A), and 100 parts by mass of the alkylalkoxysilane and / or its condensate (A) A water absorption preventive material for civil engineering and building materials comprising 0.1 to 2 parts by mass of (D) hydrophobic silica powder. The alkylalkoxysilane has the general formula (1):
R ¹ _n Si (OR ² ) _4-n (1)
(Wherein n R ^{1 s} are the same or different and each may have a substituent, each having 1 to 20 carbon atoms; 4-n R ^{2 s} are the same or different and each have a carbon number; 1-4 alkyl groups; n is 1 or 2)
The water absorption preventing material for civil engineering and building materials according to claim 1, which is a compound represented by the formula: The water absorption preventive material for civil engineering and building materials according to claim 1 or 2 , wherein the polar solvent (C) is alcohol. The water absorption preventive material for civil engineering and building materials according to any one of claims 1 to 3 , wherein the viscosity at 20 ° C is 100 to 10,000 mPa · s. A civil engineering and building material to which the water absorption preventing material for civil engineering and building material according to any one of claims 1 to 4 is applied.