JPH07252675A - Rust-preventing coating material composition - Google Patents

Abstract

PURPOSE:To obtain the composition having excellent rust preventing properties and adhesion by specifying the ratio of the polystyrene based resin to the asphalt in a composition contg. a polystyrene based resin, asphalt and an inorganic pigment and adding a specified amount of a surfactant to the latter composition. CONSTITUTION:This composition which contains a polystyrene based resin, asphalt and an inorganic pigment and is used for coating reinforcing bars for the reinforcement of ALC is prepared. As the polystyrene based resin, a resin contg. about >=60wt.% polystyrene is used and its content in the composition is adjusted to 20 to 40 pts.wt. based on the 100 pts.wt. of the solid content of the coating material. As the asphalt, natural asphalt, etc., is used and the ratio of the polystyrene based resin to the asphalt is adjusted to 3:1 to 36:1. Further, this composition contains a surfactant in a 0.01 to 5 pts.wt. ratio to the 100 pts.wt. of the total solid content and as the inorganic pigment, minimum, etc., is used. Thus, the objective composition having high adhesion strength and good environmental insulation power under conditions of short drying time can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is a rust-preventive paint excellent in rust-preventing property and adhesiveness, which is applied to reinforcing bars for reinforcing ALC (lightweight cellular concrete), such as reinforcing bars and lath nets. It is about.

[0002]

2. Description of the Related Art ALC panels and the like generally use cement and silica as main raw materials, and if necessary, quicklime, gypsum and the like, add water to form a slurry, and mold them in a mold to cure them in an autoclave. The metal fittings for attaching to reinforcing bars and building structures are
Embedded in LC. Since various gases and liquids easily penetrate into ALC, the reinforcing bars embedded inside are easily corroded, and are usually subjected to rust prevention treatment.

As a rust preventive method for reinforcing reinforcing bars of ALC, there is known a method using a solvent type bituminous rust preventive agent as described in JP-B-50-1581.
This rust preventive agent is composed of a solution of polystyrene resin dissolved in an organic solvent, and has high adhesion strength between the reinforcing bars and ALC and good environmental barrier power.

[0004]

However, in recent years, the requirements for anticorrosion performance and cost of ALC have become more and more strict, and antirust coatings having higher performance in a short drying time are required. In the above-mentioned conventional rust prevention method, the decrease in drying time is accompanied by a decrease in adhesion strength and environmental barrier power,
These requirements were not always met.

Therefore, the present invention aims to solve the problems of the conventional rust preventive method, and under the condition of a short drying time,
An object of the present invention is to provide a rust preventive paint having high adhesion strength and better environmental barrier power.

[0006]

According to the present invention, in a rust preventive coating composition containing polystyrene resin, asphalt and inorganic pigment, the ratio of polystyrene resin to asphalt is 3 to 36 and the total solid content is 100. It is characterized by containing 0.01 to 5 parts by weight of a surfactant with respect to parts by weight. Here, the total solid content indicates the total amount of polystyrene resin, asphalt, and inorganic pigment.

The present invention will be described in detail below. As the polystyrene resin in the rust-preventive coating composition of the present invention, a commercially available ordinary polystyrene resin can be used. For example, polystyrene resin, polystyrene resin containing carboxyl group, butadiene, acrylonitrile and the like copolymerized rubber modified polystyrene resin, polystyrene resin and butadiene, acrylonitrile rubber blended composition and the like, these resins have a polystyrene content of 60 It is preferable that the content is at least wt%. The melt flow index when using these resins is 1.0 to 10
The range of g / min can be used. It is preferable to use a rubber-modified polystyrene resin or a composition obtained by blending a rubber with a polystyrene resin, since mechanical properties such as impact resistance are improved, and good adhesion to reinforcing reinforcing bars and mortar is provided. The amount of the polystyrene resin used is 20 to 100 parts by weight of the solid content of the anticorrosion paint.
40 parts by weight, preferably 25 to 35 parts by weight.

The solvent for dissolving the polystyrene resin is not particularly limited as long as it dissolves the resin and can be easily dried by evaporation or the like when the coating film is dried. Specific solvents include, for example, those mainly containing aromatic solvents such as toluene, xylene, and methylbenzene. Further, a ketone solvent such as methyl ethyl ketone, or a mixed solvent obtained by adding a small amount of polyhydric alcohol to them can be used. The amount of these solvents used is 80 to 400 parts by weight, preferably 100 to 30 parts by weight per 100 parts by weight of the solid content of the anticorrosion paint.
0 parts by weight.

As the asphalt in the anticorrosive coating composition of the present invention, a commercially available ordinary asphalt can be used. For example, natural asphalt, blown asphalt, straight asphalt and the like. The amount of these asphalts to be added is such that the ratio with the above polystyrene-based resin and the value of polystyrene-based resin / asphalt are 3 to 3
6, preferably 4 to 14, more preferably 5 to 10. If the value of polystyrene resin / asphalt is less than 3, it is not preferable because the fluidity of the coating material is lowered, and if it exceeds 36, the adhesive strength is lowered, which is not preferable.

As the surfactant in the rust-preventive coating composition of the present invention, a commercially available ordinary surfactant can be used, and a surfactant soluble in the above solvent is preferable. For example amphoteric surfactants,
There are nonionic surfactants and the like. The amount of pure surfactant used is 1% total solids in terms of fluidity, adhesive strength and environmental barrier.
0.01 to 5 parts by weight, preferably 0.1 to 2 parts by weight, is suitable for 100 parts by weight. If the amount of the surfactant added is less than 0.01 parts by weight, the fluidity of the coating material is lowered, which is not preferable. Further, if the addition amount exceeds 5 parts by weight, the mechanical strength of the coating film decreases, which is not preferable.

Examples of the inorganic pigment in the rust-preventive coating composition of the present invention include lead compound pigments such as red lead, chromate pigments such as zinc chromate, zinc phosphate, zinc white, rouge, and slaked lime. Further, a pigment such as talc, clay, silica stone powder, or an extender pigment such as diatomaceous earth, white carbon (SiO ₂ fine powder) or the like can be used. The composition of these inorganic pigments is 1 to 50 parts by weight in the case of the lead compound pigment or chromate pigment, 1 to 30 parts by weight in the case of pigment such as phosphate or slaked lime, and 1 to 30 in the case of extender pigment such as talc. In the case of the extender pigment such as diatomaceous earth, the amount is about 1 to 10 parts by weight, and a particle size of 30 μm or less is preferable in order to obtain a good environmental barrier power.

The method for producing the rust-preventive coating material of the present invention is such that asphalt, a surfactant and an inorganic pigment are sequentially added to a solution prepared by dissolving a polystyrene resin in a solvent while stirring, and then a dispersion treatment such as a sand mill and an attritor is carried out. It is manufactured by adjusting the viscosity to a suitable level for coating with a solvent. In the use of this rust preventive paint, this rust preventive paint is used as an undercoating film in contact with ALC reinforced rebars, and after drying, a solution prepared by dissolving at least one layer of a polystyrene resin in an organic solvent is used as an overcoating film. It is preferably applied.

Since ALC is alkaline and is aged in an autoclave during production, it is exposed to high temperature and high pressure conditions. Therefore, anticorrosion paints for reinforcing reinforcing bars of ALC are required to have alkali resistance and heat resistance. INDUSTRIAL APPLICABILITY The rust preventive paint of the present invention, which uses a polystyrene resin for the resin component, has excellent alkali resistance and heat resistance and is suitable as a rust preventive agent for ALC reinforced rebars. It is preferable to use as.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples.

[0015]

EXAMPLES Table 1 shows the compositions of the anticorrosive paints used in Examples 1 to 4 and Comparative Examples 1 to 3. The solvent used in all compositions was 120 parts by weight of an aromatic solvent (Shell Chemical Shell Zol A) per 100 parts by weight of the solid content of the anticorrosion paint. As the polystyrene, high impact polystyrene containing butadiene rubber (Asahi Kasei polystyrene 475D) is used,
As the asphalt, blown asphalt (Nippon Oil Blow 10-20) was used. The composition of the inorganic pigment is common,
In 100 parts by weight of the solid content of anticorrosion paint, 12.5 parts by weight of talc, 42.5 parts by weight of slaked lime, and 11 parts by weight of red lead. The amount of the surfactant added is shown in parts by weight of pure content relative to 100 parts by weight of the total solid content, and Examples 1, 2, and 4 are amphoteric surfactants (manufactured by Kao Corporation, Homogenol L-95), Example 3 is a nonionic surfactant (Lion Akzo Co., Ltd.).
Manufactured by ETHOMEN T / 12) were used.

[0016]

[Table 1]

5 mmφ with 7 groups prepared as reinforcing bars
The reinforcing bars of No. 1 were immersed in anticorrosive paints having various compositions shown in Table 1 and dried with hot air at 90 ° C for 5 minutes. Next, it was immersed in a polystyrene resin solution for top coating and similarly dried with hot air at 90 ° C. for 5 minutes. The composition of the polystyrene resin solution for top coating is polystyrene (Asahi Kasei Polystyrene 666) 3
0 parts by weight, aromatic solvent (Shell Chemical Shell Zol A) 7
0 part by weight was used. After being left at room temperature for 15 minutes, each rust-proofed reinforcing bar was set in a separate mold, and a lightweight cellular concrete mortar was added, which was mixed so that the bulk specific gravity after foaming would be 0.5. After the foaming was completed and the mortar was hardened, autoclave curing was carried out at 180 ° C. for 12 hours to prepare 7 types of ALC molded bodies.

From each ALC molded body after curing, 150 mm in length × 75 mm in width × 5 length so that the reinforcing bar is almost in the center.
Four test pieces each having a size of 00 mm were cut out and an adhesion test was conducted. In the adhesion test, the reinforcing bars were exposed leaving 200 mm in the lengthwise direction, and the strength when pulling out the reinforcing bars was measured. The results of the adhesion strength are shown in Table 2 as an average value.

Further, from each ALC molded body after curing, the reinforcing bar is approximately in the center and the length is 40 mm × width 40 mm ×
Four test pieces each having a length of 160 mm were cut out to test the environmental barrier power. The test was a rust acceleration test under the following cycle conditions. Rust acceleration test cycle conditions 1) Salt water (3%) immersed for 8 hours (room temperature) 2) Dry at 70 ° C for 16 hours At the end of 10 cycles of the rust acceleration test, remove the test piece and destroy the mortar part to rebar. The area rust rate was measured by an image analyzer. The results of the rust rate are shown in Table 2 as an average value.

[0020]

[Table 2]

[0021]

EFFECTS OF THE INVENTION According to the coating composition of the present invention, as compared with the prior art, under a condition of a short drying time, high adhesive strength and
Since it is possible to obtain a rust-preventive coating film having better environmental shielding properties, it is suitable as a rust-preventive coating composition.

Claims (1)

[Claims] 1. A rust preventive coating composition containing polystyrene resin, asphalt and inorganic pigment, wherein the ratio of polystyrene resin to asphalt is 3 to 36, and 0.01 to 5 relative to 100 parts by weight of total solid content. An anticorrosive coating composition comprising a part by weight of a surfactant.