JP2001040339A - Penetrative water absorption inhibitor for exposed concrete - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a penetrative water absorption inhibitor that gives to exposed concrete water repellency high enough to inhibit rain water from entering it through pinholes even in heavy rain and is excellent in the ability to fix an organic matter by reaction and in adhesion to a top coat material and capable of long-term storage. SOLUTION: This inhibitor is prepared by emulsifying a polyalkylhydrogensiloxane in a (meth)acrylic acid ester resin emulsion. It is suitable that the content of the polyalkylhydrogensiloxane is 30-80 pts.wt. per 100 pts.wt. (meth)acrylic acid ester resin solids of the emulsion.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a permeated water-absorbing material for exposed concrete as a coating material in the field of transparent coating utilizing the base pattern and texture of the exposed concrete.

[0002]

2. Description of the Related Art A permeable water-absorbing material for exposed concrete is applied to the surface of exposed concrete to prevent the penetration of water in rainy weather. Conventionally, as such a permeable permeable water-absorbing material for exposed concrete, as a solvent-based resin, silane-based, siloxane-based, silicone-based, acrylic-based, acrylic silicone-based, polyester-based resin, as a water-based resin, Although resins such as silicone, silane, and fluorine are used, their waterproofness is not yet complete. These conventional permeated water-absorbing materials for exposed concrete, in the case of rainy weather,
In the case of light rain, the water repellency of the permeable water-absorbing material is superior, and water does not penetrate into the concrete, but in the case of heavy rain, water pressure higher than the water-repellent power of the permeable water-absorbing material is applied, Water easily penetrates into the concrete, and the concrete surface gradually becomes wet color, and the appearance is significantly impaired.

By the way, in exposed concrete,
3-4mm or more for small area construction, 5 for large area construction
The pinholes of up to 6 mm or more are filled with a cement-based or resin-based repair material. However, if all the pinholes including the small pinholes are filled with the repair material, the pattern and texture of the exposed concrete are lost, which is not appropriate. Therefore, small pinholes are always attached to the surface of the exposed concrete.
Even if concrete is treated with a permeable water-absorbing preventive material and then coated with a clear overcoating material such as an aqueous acrylate resin emulsion, solvent-based acrylic silicone resin, or fluorine-based resin, a considerable amount of pinholes will occur. At this point, the top coat is left uncoated by the air pressure inside the pinhole. Therefore, even if the above-mentioned clear coating material is applied, in the case of heavy rain, water penetrates from the pinhole, and the concrete surface becomes wet.

Conventionally used permeable water-absorbing materials for exposed concrete generally have a small amount of the active ingredient of the water-repellent (the content of the water-repellent to the solid content of the base agent is 3%).
~ 7%). This is because when the amount of the active ingredient is increased, the water repellency is improved, but the adhesion to the clear topcoat material is significantly reduced. Many of the conventionally used water repellents have a large drawback that they are easily volatilized, have poor reaction fixability to inorganic substances, and easily flow out by rainwater. An alkoxysilane having a molecular weight of 200 or more is mentioned as a type having a high reaction sticking property to inorganic substances. However, this type has a short usable time after emulsification and dispersion in an acrylate resin emulsion as a base agent. In each case, it is necessary to emulsify and disperse the alkoxysilane in the acrylate-based resin emulsion, and work management such as the mixing ratio is troublesome in the work on site.

[0005]

Therefore, the present invention has a sufficient water repellency to prevent water from penetrating from a pinhole even in a heavy rain, has an excellent reaction fixation property to inorganic substances, and has an excellent coating property. It is an object of the present invention to provide a permeated water-absorbing material for exposed concrete, which has excellent adhesion to water and can be stored for a long time.

[0006]

Means for Solving the Problems To solve the above problems, the present inventors have proposed that polyalkyl hydrogen siloxane, particularly polymethyl hydrogen siloxane, has a strong water repellent property and can be used for concrete. Focusing on its excellent reaction fixability due to hydrogen bonding, intensive studies were conducted. When polymethyl hydrogen siloxane is exposed as it is to the raw solution and applied to the concrete surface as a permeable water-absorbing material for concrete, the treated surface has extremely poor adhesion to the topcoat material, contrary to its excellent water repellency. A big problem arises. However, they have found that this problem can be solved by using the (meth) acrylate-based resin emulsion used as a clear overcoating material in combination, and completed the present invention. That is, the permeable water-absorbing material for exposed concrete according to the present invention is:
It is characterized in that a polyalkylhydrogensiloxane is emulsified and dispersed in a (meth) acrylate resin emulsion. Here, the content of the polyalkylhydrogensiloxane is 3 parts by weight based on 100 parts by weight of the solid content of the (meth) acrylate-based resin in the (meth) acrylate-based resin emulsion.
The range is preferably 0 to 80 parts by weight. Further, the polyalkyl hydrogen siloxane is preferably polymethyl hydrogen siloxane. Further, the polymethylhydrogensiloxane has a viscosity of 10 to 50.
The temperature may be in the range of cSt (25 ° C.).

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below. The permeable water-absorbing material for exposed concrete of the present invention is a composition in which a polyalkyl hydrogen siloxane is emulsified and dispersed in a (meth) acrylate resin emulsion. Such a composite composition is extremely stable in an aqueous emulsion state mediated by water, and has stable quality even when stored at room temperature for a long time (about one year).

[0008] The (meth) acrylate resin emulsion (hereinafter referred to as "acrylate resin emulsion") is obtained by emulsion polymerization of a monomer group mainly composed of acrylic acid, methacrylic acid, and derivatives thereof. Or a resin emulsion obtained by emulsion polymerization of the above monomer group and a monomer copolymerizable with the above monomer group. Specifically,
The main copolymerizable monomers include styrene, vinyl acetate, maleic ester, ethylene and the like. However, considering the condition of clear application to exposed concrete, it was copolymerized only with the monomer group consisting of acrylic acid, methacrylic acid, and their derivatives from the viewpoint of maintaining the colorless and transparent property of the weather-resistant surface, especially the coating film. A resin emulsion is optimal. Such an acrylic ester-based resin emulsion is also used as a clear topcoat material for exposed concrete, and has waterproofness and adhesion to concrete.

The polyalkyl hydrogen siloxane is obtained by substituting all the dialkyl siloxane units of the poly dialkyl siloxane with alkyl hydrogen units, and a typical one is polymethyl hydrogen siloxane. This polymethyl hydrogen siloxane is a colorless, odorless, low-viscosity liquid. Hereinafter, polymethyl hydrogen siloxane will be described as a typical example. Its chemical formula is as follows.

[0010]

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The liquid viscosity of polymethylhydrogensiloxane is suitably from 10 to 50 cSt (25 ° C.) from the viewpoint of both permeability and water repellency into the pinhole on the concrete surface. A liquid having a viscosity of less than 10 cSt is easily volatilized, so the loss increases, and the water repellency is not sufficient. On the other hand, if it exceeds 50 cSt, the permeability of the concrete surface into the pinholes becomes insufficient, and it becomes impossible to prevent water penetration during rainy weather.

The amount of the polymethyl hydrogen siloxane used is 3 parts by weight based on 100 parts by weight of the acrylate resin solid content in the acrylate resin emulsion.
0 to 80 parts by weight is suitable. If the amount is less than 30 parts by weight, the water repellency is not sufficient. On the other hand, when the amount exceeds 80 parts by weight, the water repellency is further improved, but the adhesion to a clear top coating material (such as an acrylic ester resin emulsion) which is finally applied on the surface of the permeable water absorption preventing material is reduced. It is not appropriate because it comes.

As a method of emulsifying and dispersing polymethyl hydrogen siloxane in an acrylate resin emulsion, a method of directly emulsifying and dispersing polymethyl hydrogen siloxane in an acrylate resin emulsion using a stirring mixer or the like, Gensiloxane is once emulsified and dispersed in an emulsifier aqueous solution,
There are two methods: an indirect method of adding the emulsion to the acrylate resin emulsion and mixing.

In the latter indirect method, as the emulsifier for aqueous emulsification of polymethylhydrogensiloxane, nonionic alone or nonionic / anion combined emulsifier is preferable. Suitable emulsifiers include polyoxyethylene alkyl ethers, polyoxyethylene alkyl allyl ethers, polyoxyethylene derivatives, oxyethylene / oxypropylene block copolymers for nonionics, and polyoxyethylene alkyl ether sulfates and polyoxyethylene alkyl ethers for anionics. Oxyethylene alkyl allyl ether sulfate and the like.

Although not essential components, pigments such as titanium oxide and iron oxide, fillers such as calcium carbonate, silica and clay, sodium polyphosphate, and polycarboxylic acid surfactants can be added as necessary. Pigment dispersants, thickeners such as hydroxyethylcellulose and polyacrylates, organic solvents such as toluene, xylene and ethyl acetate, and preservatives and fungicides.

[0016]

When the permeable water-absorbing material for exposed concrete according to the present invention is applied to the concrete surface, the polymethyl hydrogen siloxane is released from the emulsified system in the drying stage and immediately in the concrete (surface including pinholes). Penetrate into Next, the polymethyl hydrogen siloxane that has penetrated into the concrete can coat the inorganic substance at a high density, and the hydrogen bonding with the inorganic substance proceeds efficiently, and the remarkable water repellency is permanently exhibited. .

The mechanism for developing and maintaining strong water repellency when the polymethyl hydrogen siloxane is exposed and applied to the concrete surface can be explained as follows. That is, when the composition containing polymethylhydrogensiloxane is applied to the concrete surface and dried and comes into contact with air, Si-H bonds in the polymethylhydrogensiloxane molecules react as shown in Chemical formula 2. New siloxane bond between molecules (Si-OS
i), and eventually form a three-dimensional silicone structure.

[0018]

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Then, H atoms in hydroxyl groups (-OH) existing on the surface of the concrete (hardened cement paste, aggregate, etc.), O atoms in polymethyl hydrogen siloxane molecules, and siloxane newly formed between the molecules. A hydrogen bond is formed between the O atom in the bond (Si-O-Si) and a three-dimensional structure in which hydrophobic methyl groups are oriented outward to cover the concrete surface, thereby firmly contacting the concrete surface. It is believed that they combine with each other and exhibit permanent water repellency.

On the other hand, since the acrylate resin emulsion has a large particle diameter (0.1 to 0.3 μm),
Even if applied to the concrete surface, it cannot penetrate into the concrete. However, since the mixture from the concrete interface to the surface of the coating film is in a mixed state with polymethyl hydrogen siloxane, the composite composition (acrylate resin emulsion + polymethyl hydrogen siloxane) is dried and Is strongly bonded to concrete by the adhesive force of the acrylate resin. In addition, the adhesiveness to various overcoating materials such as an acrylate resin emulsion applied thereafter is also good.

[0021]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but these are exemplifications and do not limit the scope of the present invention.

[Preparation of Permeable Water Absorption Prevention Material for Exposed Concrete] (1) Method of Emulsifying and Dispersing Polymethyl Hydrogensiloxane Directly in Acrylic Ester Resin Emulsion Examples 1-3 in Table 1 and Comparative Examples 1-4 Based on the recipe
Using a disper-type forced stirring mixer, polymethyl hydrogen siloxane is converted to an acrylate resin emulsion (trade name "Movinyl 700" manufactured by Clariant Polymer Co., Ltd. (main component: copolymer of methyl methacrylate and butyl acrylate, solid Min. 47%)). Next, a predetermined amount of water was added to dilute the mixture to obtain a blended preparation of a permeated water-absorbing material for exposed concrete having an acrylic ester resin solid content of about 10 to 17%. (2) Indirect method of adding a polymethyl hydrogen siloxane once emulsified and dispersed in an emulsifier aqueous solution to an acrylate resin emulsion, based on the compounding tables of Examples 4 to 5 and Comparative Examples 8 to 11 in Table 2. The polymethyl hydrogen siloxane is emulsified and dispersed in the aqueous emulsifier solution using a disper-type forced stirring mixer, and then this emulsion is added to the acrylate resin emulsion together with a predetermined amount of water, and the acrylate resin solid is added. About 10 to 16% per minute of a blended preparation of a permeated water-absorbing material for exposed concrete was obtained. (3) Heated storage stability In order to evaluate the warmed storage stability of the blended preparation, the blended preparations of (1) and (2) above should be used in accordance with JIS K5960, which stipulates indoor home wall paint. It was housed in a container, sealed, and stored at a temperature of 50 ° C. for 7 days.

[Preparation of test piece for performance evaluation]
(2) The mixed preparations (each after storage at a temperature of 50 ° C. for 7 days) were set on a sidewalk paving stone concrete plate (30 cm × 30 cm).
Approximately 15 g is applied to the mold release surface (30 cm × 30 cm) of the form (cm × 5 cm) and dried at room temperature for one day. In the case of using only polymethylhydrogensiloxane (Comparative Examples 6 to
In 7), about 20 g was applied to a concrete plate as it was.
Next, about 30 g of a clear overcoating material based on an acrylate resin emulsion (the same trade name “Movinyl 700”) was applied thereon, and dried at room temperature for 3 days.

[Performance evaluation method] (1) Watering test assuming heavy rain As described above, a slab of sidewalk paving stone concrete with a permeable water-absorbing preventive material, then a topcoat material applied and dried, was set up approximately vertically.
Set the hose port connected from the water tap about 1 m from the concrete surface. Here, the faucet is opened to the full water pressure, and the hose mouth is narrowed, and the heavy rain of side-hitting is sprayed on the application surface for about 60 seconds, similar to a large typhoon. The evaluation method of the water hanging test is as follows. ：: No change in appearance △: Water penetrates from the pinhole and the surrounding area becomes wet color ×: Water penetrates into most of the concrete surface and becomes wet color

(2) Adhesion to Topcoating Material After the watering test of the above item (1), after drying at room temperature for 3 days, a forced peeling test using a cellophane tape is performed. 20mm x 20mm on clear clear top coat in dry state
Paste the cellophane tape and press firmly with your finger. Next, this cellophane tape is forcibly peeled off at a stretch, and the state of adhesion is evaluated. Such an adhesion test was carried out at three arbitrary points on each test piece. The evaluation method is as follows. ：: The release surface is the interface between the clear coating material and the cellophane tape ×: The release surface is the interface between the permeable water-absorbing material and the clear coating material △: Mixed of ○ and ×

[0026]

[Table 1]

[0027]

[Table 2]

From the results shown in Tables 1 and 2, Example 1
It can be seen that all of the samples using Nos. 5 to 5 have good water repellency and adhesion to the topcoat material. As described above, even after storage at 50 ° C. for 7 days, it has good performance, and it can be seen that the storage stability under heating is excellent. The performance is stable even under the more severe condition of 50 ° C. for 7 days compared to the condition of holding at 35 ° C. for 90 days, which is the test condition of the heated storage stability according to the general test method of paint (JIS K5400). It is said that those that clear the conditions for 7 days can be stored at room temperature for one year in the coatings industry, and it can be seen that those of this example are excellent in long-term storage.

[0029]

As described above, according to the permeable water-absorbing material for exposed concrete of the present invention, even in the case of heavy rain, it has sufficient water repellency without water permeating from pinholes, The original dry color can be maintained. In addition, it has excellent reaction fixability to inorganic substances and excellent adhesion to an overcoat material. Further, since long-term storage is possible, construction management on site is easy.

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Kohei Nagano 1314 Kaminishicho, Hamamatsu-shi, Shizuoka Nichie Yoshida Co., Ltd. F-term (reference) 4H020 BA02 BA32 4J038 CG031 CG141 DL042 MA08 MA10 PC04

Claims (4)

[Claims] 1. A permeable water-absorbing material for exposed concrete, wherein a polyalkylhydrogensiloxane is emulsified and dispersed in a (meth) acrylate resin emulsion. 2. The content of the polyalkyl hydrogen siloxane is 30 to 80 parts by weight based on 100 parts by weight of the solid content of the (meth) acrylate resin in the (meth) acrylate resin emulsion. The permeable water absorption preventing material for exposed concrete according to claim 2, which is 3. The permeable water-absorbing material for exposed concrete according to claim 1, wherein the polyalkyl hydrogen siloxane is polymethyl hydrogen siloxane. 4. The permeable water-absorbing material for exposed concrete according to claim 3, wherein the polymethylhydrogensiloxane has a viscosity of 10 to 50 cSt (25 ° C.).