JPS605085A - Corrosion prevention for cementitious substance structure - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a corrosion protection method that increases the durability of cementitious material structures against chemical agents.

Conventionally, the surface of a concrete structure is left as it is, subjected to a surface treatment such as applying mortar, or further coated with tiles, decorative boards, etc. depending on the purpose. Because it is costly to apply covering materials such as tiles and decorative boards to the surface of concrete structures, in most facilities such as sewage treatment facilities and chemical factories, the surface of concrete structures is left as is or mortar is applied. It is. However, in such cases, it is known that tin is damaged by chemical agents, resulting in significant deterioration and reduced durability; however, no inexpensive corrosion prevention method has been developed to date. .

In addition, the surface of concrete structures is sometimes painted with epoxy resin or urethane resin, but the durability of the paint is lower than that of concrete, so repainting is necessary every few years. there were.

It is an object of the present invention to provide an economical and easy method for increasing the corrosion resistance of cementitious material structures against chemical agents.

The corrosion prevention method for cementitious material structures of the present invention involves coating the surface of the cementitious material structure with a paint that allows carbon dioxide gas and/or carbonate ions to pass through, but does not allow calcium ions to pass through, and prevents calcium ions from eluting. The structure is characterized in that the surface of the structure is converted to calcite using carbon dioxide gas and/or carbonate ions that have passed through the coating film of the paint.

The present invention will be explained in more detail below.

It is generally known that Portland cement is hardened using the following formula.

3C3S+6H20-+C, 52H3+3Cn (OH
I 22C2S+4H20→C3S2H3+Ca(oH
)2 The Ca(OH)2 generated at this time is about 0.0% in the air.
Calcium carbonate is produced using carbon dioxide gas containing 3% or carbonic acid dissolved in water as shown in the following formula.

This calcium carbonate generally has a calcite crystal system.

Ca (OH)2 + CO2 → CaCOO1 (,.

Normally, the rate of calcification of carbonate (calcitization) is extremely slow, and it is said that it takes about 5 years for it to progress from the surface of a cementitious material structure to a depth of 1 am. Therefore, during this period, there have been many cases where cementitious material structures are eroded before they are sufficiently converted into calcite.

For example, in sewage treatment plants, facilities built during the fortune-telling era are still being used without any damage to this day, whereas settling tanks in newly constructed sewage treatment plants are severely damaged. be. This is because phosphorus compounds and sulfur compounds caused by detergents and other chemical agents have been increasing in sewage in recent years, and these compounds are increasing the amount of carbon in cementitious materials.
It is thought that it reacts with a (OHI2) and damages and deteriorates cementitious materials. However, in sewage facilities built in ancient times, hardening of cementitious materials was completed before phosphorus compounds and sulfur compounds increased. This is thought to be due to the fact that calcium carbonate in the cementitious material gradually turns into calcite over a long period of time and becomes a dense structure, which is not damaged even if phosphorus and sulfur compounds increase later. .

In the present invention, by forming a coating film on the surface of a cementitious material structure that allows carbonic acid and/or carbonate ions to pass through but does not allow calcium ions to pass through, the cementitious material is sufficiently calcified while preventing the initial elution of calcium ions. Make it into a website. This calcite formation can be completed during the durability period of the paint film (therefore, even after the paint film has peeled off, the calcite layer can provide corrosion protection. It can significantly improve the pot resistance of objects.

Conventionally, the direction of paint research and development has been to form a complete coating film and suppress permeability as much as possible. The focus of the present invention is to reverse this idea and utilize a coating film that allows permeation of carbonic acid and/or carbonate ions.

It is preferable that the profit-making resin for the coating material used in the present invention be selected from those having a water absorption in the range of 0.05 to 30%, particularly 0.1 to 20%. If the water absorption rate is too low, permeation of carbon dioxide gas and/or carbonate ions will be poor, and if it is too high, calcium ions will permeate, and calcite formation may not be sufficiently advanced.

Specific examples of base resins include acrylic resins, for example, neutral monomers such as acrylic esters, methacrylic esters (hereinafter simply referred to as (meth)acrylic acid),
Monomers containing acid groups and acid anhydride groups, such as sutyrene, include (meth)acrylic acid, iconic acid, maleic acid, and maleic anhydride; monomers containing hydroxyl groups include (meth)acrylic acid, droxyethyl, ( meth) hydroxypropyl acrylate, etc., monomers containing epoxy groups such as glycidyl methacrylate, nitrogen-containing monomers such as (meth)acrylamide; urethane resins, such as oil-modified urethane resins, 1-component moisture-curing polyurethane resins, 2 Liquid catalyst-curing polyurethane resin, two-component polyurethane resin, thermosetting one-component polyurethane resin, etc.; epoxy resin, such as epichlorohydrin/bisphenol A
type, novolak type, β-methyl epicro type, brominated type, cycloaliphatic type (cyclic oxirane type, glycidyl ether type, glycidyl ester type), acyclic aliphatic type (polyglycol ether type, glycol ether type), aliphatic non- Epoxidized saturated compounds (epoxidized polybutadiene), epoxidized fatty acid esters (epoxidized natural oils and fats)
, polycarboxylic acid ester type, aminoglycidyl type, chlorinated type, resorcin type, epoxy tar modified type, etc. Epoxy resins consisting of aliphatic diamines, amide polyamines, polyamides, etc.; Polyester resins, e.g. Unsaturated polyester resins, alkyd resins, oil-free alkyd resins, linear polyester resins, etc.; amino resins, such as butylated melamine resins; vinyl resins, such as vinyl acetate resins, vinyl butyral resins, vinyl chloride resins, vinyl chloride copolymers Polymer resins, such as vinyl acetate and copolymers with (meth)acrylic acid; nylon resins, nylon copolymer resins,
Examples include copolymer resins such as 6,6 nylon, 6 nylon, and 6.10 nylon; and fluororesins such as 1-fluorocarbon resin and 2-fluorocarbon resin. Among these, preferred are methacrylic acid resin, unsaturated polyester resin, vinyl chloride copolymer resin, bisphenol type epoxy resin, and polyurethane resin.

Pigments that have as little hiding power as possible are used as pigments that can be used in the preparation of the paint used in the present invention.

Such pigments include carbonate lime powder, precipitated calcium carbonate, clay, silica, white carbon, diatomaceous earth, talc, magnesium carbonate, alumina white, zinc white, lead white, etc. Especially, carbonate lime powder, precipitated calcium carbonate are suitable for the purposes of the present invention. Sulfates and barium salts such as gypsum, barium sulfate, barium carbonate, and lead sulfate are not preferred because they react with cementitious material structures.

In preparing the paint, the following ingredients are used: a base resin, a pigment, a solvent such as quidylol, doluol, methyl isobutyl ketone, a plasticizer such as dimethyl phthalate, dimethyl phthalate, tricresyl phosphate, a dispersant such as the product name "Anti-Taylor U", etc. ”, “lactimon” or rBY
KP-104” (Both B Y K Maeli
(manufactured by Nckrodt), emulsifiers such as sodium dodecylbenzenesulfonate, polyoxyethylene nonylphenyl ether, alkylpyridium salts, curing agents,
For example, polyisocyanate resin, trade name [Parnock D-800J, rBurnock D-7'5, OJ,
"Parnock DN950" (Both BYK-Mae
I1 (manufactured by Nekrodt), etc. are appropriately blended as necessary, and the mixture is dispersed and kneaded using a roll mill, flat stone mill, ball mill, or the like. The blending ratio is not particularly critical, but 10 to 10 parts by weight of pigment per 100 parts by weight of base resin.
300 parts by weight, and about 01 to 300 parts by weight of other additive components.

However, when carrying out the present invention, it is also possible to apply two or more types of paint over each other. In this case, it is preferable to use an undercoat based on a resin with a higher water absorption rate.

When applying the anticorrosion method of the present invention, a specimen is prepared with the same composition as the cementitious material structure actually used, and is left in the same environment as that in which it will actually be used. The degree of calcite formation, that is, the degree of selective permeability of the coating film, can be determined by sampling up to 1 cm of the surface of the specimen after leaving it for an appropriate period of time, for example, one year, and performing thermogravimetric analysis.

That is, calcium hydroxide undergoes a dehydration reaction at 400 to 500°C, and calcium carbonate undergoes a decarboxylation reaction at 650 to 90°C to reduce weight.

The amount of calcium hydroxide and calcium carbonate can be determined from this weight loss. Measured by this method, 1
If more than 5% (weight) of calcite is converted into calcite per year and the amount of calcium hardly changes, calcite with sufficient corrosion resistance will be formed in a few years.

The present invention will be explained below with reference to examples. Note that parts and percentages are based on weight.

Example 1 A white acrylic resin paint was made with the following composition.

Acrylic resin face (product name [Acrydec A-180
J] 1' 60 parts calcium carbonate (product name "Niscallon #200J"), 25 parts additive (product name "Anti-Tera Ujl" 1.0 parts (product name rBYK-P104)
"l" 1. o part doluol 13 100 parts 1) Manufactured by Dainippon Ink & Chemicals Co., Ltd. 2) Manufactured by Sankyo Seifun Co., Ltd. 314) Part of acrylic resin face and pigments, additives and solvents manufactured by B Y K-Maelinckrodt Co., Ltd. I premixed some of it and put it in a dispersion machine, and after dispersing, I made my own paint using the remaining acrylic resin face and solvent.

Note that the water absorption rate of the acrylic resin was 0.15%.

The acrylic resin paint thus prepared was applied to a mortar specimen (10 cm + φ x 20 cm L, 50 parts of Portland cement, 100 parts of fine aggregate) to an average thickness of 3.0 haze, and immersed in water at 20±10°C.

The concentration of phosphorus compounds in water was 10-40 ppm, the concentration of sulfur compounds was 20-100 ppm, and the concentration of nitrogen compounds was 02-20 ppm.

After 12 months, it was taken out of the water, the surface was scraped to a thickness of 1 um, and thermal polymerization analysis revealed that it had become 48% calcite. Furthermore, the amount of calcium did not change.

The results of differential thermogravimetric analysis are shown in the attached drawings. The measurement conditions were as follows.

Example 2 A white epoxy resin paint was prepared from the following composition.

Main agent: Epoxy resin face (product name [Epicote 100
1-75
K-P104J) 0.5 parts Kijirol 5 parts Cellosolve 2 parts Curing agent: Polyamide curing agent (trade name: Persamide 415
J) 5'236 xylol 6 parts n-butanol -- 100 parts 1) Manufactured by Yuka Shell Epoxy Co., Ltd. 2) ~ 4) B Y K -M ael 1nckr
A part of epoxy resin face manufactured by ODT Co., Ltd. 51 II, manufactured by Shikasei Kogyo Co., Ltd., calcium carbonate, an additive, and a part of a solvent were used to disperse in a dispersion machine. A paint was prepared with the remaining resin face and solvent. A curing agent was prepared by mixing a polyamide curing agent and a solvent. At the time of use, the main agent and curing agent were mixed together.

Note that the water absorption rate of the epoxy resin was 0.023%.

When the same test as in Example 1 was conducted, the calcite formation was 2.
It was 4%. Calcium levels remained unchanged.

Example 3 A white urethane resin paint was prepared from the following composition.

Urethane resin face (product name: Burnock Dy1-65
2JJ lls O part Calcium carbonate (trade name "Softon 1200") 23 30 parts Tolu 10 100 parts 1) Manufactured by Dainippon Ink & Chemicals Co., Ltd. 2) Part of urethane resin face and pigment manufactured by Nanboku Funka Co., Ltd. After dispersion using a dispersing machine, a paint was prepared using the remaining solvent. Since urethane resin paint has a limited pot life, it was used for painting within 24 hours after manufacture.

Note that the water absorption rate of the urethane resin was 18%.

When the same test as in Example 1 was conducted, the calcite formation was 54%. Calcium levels remained unchanged.

Example 4 A white vinyl resin paint was prepared from the following composition.

Vinyl resin face (product name [Vinyroll 92TJ)”
25 parts calcium carbonate (product name [Softon 15oOJ)]
”' 23 parts Additive (product name “Lactimon”) 3
ゝ 10 parts (trade name [Anti-Taylor PJ)” 1.0 parts possible 1111J (dimethyl phthalate) 1 3m acetate 13 parts MIBK (methyl isobutyl ketone) 8 parts Doluol 18 parts Kijirole 8 parts 100 parts 1) Showa Kobunshi Manufactured by Kagaku Co., Ltd. 2) Manufactured by Bihoku Funka Co., Ltd. 3) 4) Manufactured by BYK-Maelinckrodt A part of the vinyl resin face, an additive, a plasticizer, and a part of the solvent are used in a dispersion machine, and after dispersion, the remaining resin is A paint was prepared using fest and a solvent.

Note that the water absorption rate of the vinyl resin was 18%.

When the same test as in Example 1 was conducted, calcite formation was 6
It was 3%. First, the amount of calcium did not change.

Example 5 A white polyester resin paint was prepared from the following composition.

Polyester resin face (product name: Polyset PS-6
120J) 1'71.6 parts accelerator (trade name rPT-
42J)' 0.7 part (product name rPT-2sJ
) ” 0.3 parts hardening agent (product name rCT-3J)
0.4 parts Calcium carbonate 15 parts Tar 10 parts Additive (Product name rBYK-P] 04J) 5'1.0 part (Product name "Lactimon J") 6'-Shibu 100 parts 1) to 4) A polyester resin manufactured by Hitachi Chemical Co., Ltd. (516) manufactured by BYK-Maelinekrodt, pigments and additives was dispersed in a dispersion machine to form the main agent.When using the paint, the remaining curing agent and accelerator were used to prepare the paint. did.

Note that the water absorption rate of the polyester resin was 0.3%.

When the same test as in Example 1 was carried out, the amount of calcite formation was 19%, and the amount of calcium was unchanged but 0.

[Brief explanation of the drawing]

The attached drawing is a graph showing the analysis results of a specimen to which the anticorrosion method of the present invention was applied. Patent applicant Hazama Gumi Co., Ltd.-ζ1

Claims (1)

[Claims] A paint that allows carbon dioxide gas and/or carbonate ions to pass through but not calcium ions is applied to the surface of a cementitious material structure, and calcium ions pass through the surface of the structure and through the coating film of the paint without eluting calcium ions. A corrosion prevention method for cementitious material structures, characterized by converting them into calcite using carbon dioxide gas and/or carbonate ions.