JPH0688260A - Rust preventing method for alc reinforcing bar or the like - Google Patents

Abstract

PURPOSE:To prevent rusting ALC reinforcing bars by applying a rust preventive obtained by adding a silicone oil into a solution of a polystyrene based resin and an organic solvent onto the surface. CONSTITUTION:The rust preventive obtained by adding the silicone oil into the solution made by dissolving the polystyrene based resin such as polystyrene resin, a rubber modified polystyrene resin and a blended composition of polystyrene resin with rubber or the like in the organic solvent is applied on the surface of the ALC reinforcing bars. As a result, a rust preventing method for ALC reinforcing bars having excellent sticking strength and environment interrupting ability is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anticorrosion method for reinforcing bars for ALC (lightweight cellular concrete), and more specifically, an AL having excellent adhesion strength and environmental barrier power (antirust persistence).
The present invention relates to a rust prevention method for reinforcing bars for C.

[0002]

2. Description of the Related Art ALC panels and the like are generally made of cement and silica stone powder as main raw materials. If necessary, quicklime powder, gypsum, etc. are added, water is added to form a slurry, and the mixture is molded in a mold and autoclaved for curing. Although it is made by means of that, reinforcing bars and metal fittings for attaching to building structures are embedded in the ALC at that time, but steel is usually used as the material of these reinforcing steel bars and metal fittings. The surface is previously subjected to anticorrosion treatment.

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

[0004]

However, in recent years A
The requirements for the performance and cost of anticorrosion of LC are becoming more and more strict, and there is a demand for an anticorrosion method having higher performance by using a smaller amount of anticorrosive agent. I couldn't meet all of those requirements. Therefore, the present invention aims to solve the problems of the conventional rust preventive method, and to provide a rust preventive method having a high adhesion strength and a good environmental barrier power by using less rust preventive agent. Is an issue.

[0005]

The rust preventive method of the reinforcing bar for ALC of the present invention to achieve the above object is a rust preventive agent in which silicone oil is added to a solution of polystyrene resin dissolved in an organic solvent. It is characterized in that the surface of the reinforcing muscles for ALC is coated. In a preferred embodiment of the present invention, an inorganic pigment, asphalt or the like is further added to the rust preventive agent.

In yet another preferred embodiment, A
In the case of forming a rust preventive coating by coating a rust preventive agent on the surface of the reinforcing bars of LC to prevent rust, the lower coating film which comes into contact with the reinforcing bars as the rust preventive coating and at least one layer above it An upper layer coating film is formed, in which case the lower layer coating film is formed by a solution of polystyrene resin dissolved in an organic solvent or a rust preventive agent in which 0.5 wt parts or less of silicone oil is added to the solution. It is formed by a rust preventive agent in which 0.1 to 8 parts by weight of silicon oil is added to a solution in which a base resin is dissolved in an organic solvent.

The present invention will be described in detail below. As the polystyrene resin in the rust preventive used in the present invention, a commercially available ordinary polystyrene resin can be used. Examples thereof include polystyrene resin, rubber-modified polystyrene resin, and a composition obtained by blending polystyrene resin and rubber. The melt flow index when using these resins can be in the range of 1.0 to 10 g / min. In the case of forming the rust preventive coating film in two or more layers, it is preferable to use a rubber-modified polystyrene resin or a composition obtained by blending a polystyrene resin and rubber for the lower layer coating film. The amount of these polystyrene-based resins used is 15 to 37 parts by weight per 100 parts by weight of the solid content of the rust inhibitor,
It is preferably 20 to 30 parts by weight.

The silicone oil preferably has a viscosity of about 10 to 500 centistokes. Specific silicone oils include, for example, dimethyl silicone oil (polydimethylsiloxane), methylphenyl silicone oil, cyclic polydimethylsiloxane, methyl hydrogen silicone oil, and modified silicone oil obtained by modifying the methyl group of dimethyl silicone oil. Can be used.

The amount of these silicone oils used is preferably 0.1 to 0.5 parts by weight per 100 parts by weight of the rust preventive agent when the rust preventive coating film is formed in a single layer. When forming two or more layers, the lower coating film, that is, the lowermost layer is 0.5
wt part or less, 0.5 to 8 wt parts for the intermediate layer and the uppermost layer,
It is preferably 0.5 to 5 parts by weight. The lower limit of these is determined by the environmental barrier effect, and the upper limit is determined by the bond strength.

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 may be used. The amount of these solvents used is 80 to 400 parts by weight, preferably 100 to 300 parts by weight per 100 parts by weight of the solid content of the rust inhibitor.
wt part.

If desired, an inorganic pigment may be further added to the rust preventive agent used in the present invention. Examples of the inorganic pigments include lead compound pigments such as red lead and chromate pigments such as zinc chromate, pigments such as zinc phosphate, zinc white, rouge, slaked lime, talc, clay and silica powder. An extender pigment or a thixotropic pigment such as diatomaceous earth or white carbon (fine powder of SiO ₂ ) can be used. The amount of these inorganic pigments used can be variously changed depending on the purpose. For example, the solid content of the rust inhibitor is 100 wt.
Per part: 0 for lead compound pigments and chromate pigments
˜50 parts by weight, 0 to 30 parts by weight for pigments such as zinc phosphate and slaked lime, 0 to 30 parts for extender pigments such as talc
0 to 10w in the case of pigments such as wt parts and thixotropic pigments such as diatomaceous earth
It is about t.

If desired, asphalt may be added to the rust preventive agent used in the present invention for the purpose of further improving the environmental barrier power of the coating film. It is particularly preferable to add this asphalt to the lower layer coating film when the rust preventive coating film is formed in two or more layers. The amount of asphalt added is preferably about 0 to 15 parts by weight per 100 parts by weight of the solid content of the rust preventive agent.

In the rust preventive method of the present invention, the thickness of the coating film formed on the surface of the supplementary streak is preferably about 70 to 150 μm. When the coating film is formed in multiple layers, it is preferable that the lower coating layer has a thickness of about 40 to 120 μm and the thickness ratio of the lower coating layer to the upper coating layer is about 4: 6 to 7: 3.

[0014]

EXAMPLES Examples of the present invention will be described below.

[0015]

[Examples 1 to 7 and Comparative Example 1] Six groups of 6 mmφ reinforcing bars prepared as reinforcing bars were each immersed in a rust preventive solution for undercoating and dried by hot air at 80 ° C to form a lower layer coating film. The composition of the rust preventive liquid for undercoating is common, and high impact polystyrene (Asahi Kasei Polystyrene 475D) 10
wt part, aromatic solvent (Shell Chemical Shell Sole A) 60
wt part, talc 5 wt part, slaked lime 17 wt part, red lead 4 w
Part t, Asphalt (Nippon Petroleum Bron 10-20) 4w
It consists of the t part.

Next, it was dipped in a rust preventive solution for top coating of various compositions and dried under the same conditions to form an upper coating film. The composition of the rust preventive liquid for the top coating was 30 wt parts of polystyrene (Asahi Kasei Polystyrene 666) and 70 wt parts of the aromatic solvent (Shell Chemical Shell Zol A) as Comparative Example 1, and various amounts as shown in Table 1 were used. What added the silicone oil was made into Examples 1-5. Then, each of the rustproofed reinforcing bars was set in a separate mold, and aerated concrete mortar was added so that the bulk specific gravity after foaming was 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 6 types of ALC molded bodies.

From each ALC molded body after curing, the reinforcing bars are placed in the substantially central part, and the length is 100 mm × width 100 mm ×
Five test pieces each having a length of 600 mm were cut out to perform an adhesion strength test. In the adhesive strength test, the reinforcing bar was exposed leaving 200 mm in the length direction, and the strength when pulling out the reinforcing bar was measured. The results of the adhesion strength are shown in Table 1 as an average value.

Further, from each of the ALC molded bodies after curing, the reinforcing bars are placed substantially in the center portion, and the length is 40 mm × width 40 mm ×.
Five test pieces each having a length of 160 mm were cut out to test the environmental barrier power. The test is JIS A54
It was performed by counting the rusting rate after one month by the rust prevention test method of 16. Table 1 shows the results of rust rate as average values
Shown in.

[0019]

[Table 1]

In addition, the rust preventive liquid for undercoat in Example 1
In addition to silicone oil (dimethyl silicone oil 1
00 cst / 25 ° C.) at 0.1 wt part (Example 6),
0.3 wt parts (Example 7) undercoat of composition added respectively
I made a lower layer coating film with a rust preventive liquid for
A test piece was prepared in the same manner as in Example 1, and an adhesion test and a rust test were performed.
Test was carried out. As a result, the adhesive strength of Examples 6 and 7 was
17.5 kg / mm each ², 17.1 Kg / mm²And
The rust rate was 0% in all cases.

[0021]

Examples 8 and 9 and Comparative Example 2 To the rust preventive agent having the same composition as the undercoat of Example 1, silicon oil was added in an amount of 0.1 wt% (Example 8) and 0.3 wt% (Example 9), respectively. Using a rusting agent, rust-proofing treatment was applied to only the lower coating layer in the same manner as in Example 1, and 5 test pieces were prepared in the same manner as in Example 1. However, the thickness of the coating film was about 130 to 140 μm.
An adhesion test and a rusting test were performed on these test pieces in the same manner as in Example 1. As a result, each adhesion strength of Example 8 and 9 17.4 kg / mm ^2, a 17.2 kg / mm ^2, Hatsusabiritsu was 0% none.

Further, as Comparative Example 2, the rust preventive agent having the same composition as that of the undercoat of Example 1 was used, and the rust preventive treatment was applied to only the undercoat layer in the same manner as in Example 1, and the same method as in Example 1 was used. Then, 5 test bodies were prepared. An adhesion test and a rusting test were performed on these test pieces in the same manner as in Example 1. As a result, the adhesive strength was 17.8 Kg / mm ² , but the rusting rate was 2.5%.

[0023]

EFFECTS OF THE INVENTION According to the rust preventive method of the reinforcing bar for ALC of the present invention, a high adhesion strength between the reinforcing bar and the ALC is obtained, and the use of less rust preventive agent provides good environmental shielding. The effect of having power can be produced.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical display location C09D 5/08 PQA 6904-4J 125/04 PFB 9166-4J E04C 5/01 2118-2E

Claims (2)

[Claims] 1. A method for rustproofing ALC reinforcing bars, which comprises coating the surface of a reinforcing bar for ALC with a rust preventive agent in which silicone oil is added to a solution in which a polystyrene resin is dissolved in an organic solvent. 2. A method for forming a rust preventive coating by coating a rust preventive agent on the surface of a reinforcing bar for ALC to form a rust preventive film. At least one upper layer coating film is formed, the lower layer coating film is formed by dissolving a polystyrene resin in an organic solvent or a rust preventive agent in which 0.5 wt parts or less of silicone oil is added to the solution. The upper coating film is formed by a rust preventive agent in which 0.1 to 8 parts by weight of silicon oil is added to a solution of polystyrene resin dissolved in an organic solvent.
Method for rustproofing reinforcement bars.