JPS6110655A - Corrosion-proof iron wire - 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 [Technical Field] The present invention relates to anti-corrosion reinforcing bars that have been effectively subjected to anti-corrosion treatment.

r obey! i! : Technology, ] Reinforced bars are widely used for reinforcing concrete, but in recent years there has been a problem of deterioration of concrete structures due to corrosion of these reinforcing bars. The causes of corrosion of the reinforcing bars in concrete are that the sand used in concrete turns into sea sand and the salt contained in this sea sand accelerates corrosion, or as the number of marine structures increases, salt directly enters through the concrete and corrodes the reinforcing bars. Reasons include promoting corrosion.

Various anti-corrosion methods have been proposed to prevent the above-mentioned corrosion of reinforcing bars, but among these methods, coating the reinforcing bars themselves with an anti-corrosion material is considered to be the most effective.

The most suitable anticorrosion material is an epoxy resin coating formed by powder coating an epoxy resin coating. That is, this epoxy resin coating has good adhesion and flexibility to reinforcing bars, and also has good alkali resistance and adhesion to concrete.

The thickness of the epoxy resin coating is usually about 100 to 300 microns. If this thickness is too thin, pinholes will occur frequently, resulting in a decrease in anticorrosion performance.On the other hand, if it is too thick, the irregularities on the surface of the reinforcing bars will become small, which will reduce the adhesion strength between the reinforcing bars and concrete, and will also worsen bending workability. Moreover, it has drawbacks such as increased cost. However, the above thickness is 1
Even if the coating is set to about 00 to 300p, pinholes may still occur (if the coating is relatively thin or the reinforcing bars themselves are damaged), or the coating may be damaged during transportation or reinforcing work. This sometimes resulted in defective areas in the coating film where the reinforcing bar body was exposed, resulting in insufficient corrosion protection.

[Object of the Invention] It is an object of the present invention to provide a corrosion-resistant reinforcing bar in which a coating treatment is applied that has a highly reliable anti-corrosion effect even on defective parts of the coating film of the painted reinforcing bar.

[Summary of the invention]

As an anti-corrosion material for preventing corrosion of the defective parts of the coating film of painted reinforcing bars, it is desirable to have a material that adapts well to the irregularities on the surface of the painted reinforcing bars and has good alkali resistance. The inventors investigated anticorrosion materials that satisfy these characteristics and found that an anticorrosion layer containing petrolatum as a main component satisfies the above characteristics. However, this anti-corrosion layer containing petrolatum as a main component is flexible and is easily damaged. Therefore, by providing a retaining tape layer on this anti-corrosion layer to cover and protect the anti-corrosion layer, the anti-corrosion layer and the retaining tape layer work together to provide an anti-corrosive effect on the defective parts of the coating film of the painted reinforcing steel. It was discovered that the coating layer can be highly reliable, and this invention has been completed.

That is, the present invention relates to a coated reinforcing bar in which an anticorrosion coating is provided on the surface of a reinforcing bar body having an uneven surface, and an anticorrosion layer containing petrolatum as a main component provided on the defective coating film on the surface of the coated reinforcing bar and its surrounding area. The present invention also relates to a corrosion-proof reinforcing bar comprising a holding tape layer covering the corrosion-proofing layer.

〔Effect of the invention〕

In the anti-corrosion reinforcing steel of this invention, the anti-corrosion layer containing petrolatum as a main component, which is provided on the coating film defects on the surface of the painted reinforcing bar and its surrounding areas, has good alkali resistance and is flexible, so it is compatible with the uneven surface of the painted reinforcing steel. It blends in and completely covers the defective parts of the paint film. Since this anti-corrosion layer is flexible, it is easily damaged if a direct impact is applied from the outside, but it is covered and protected by the retaining tape layer, and this anti-corrosion layer and the retaining tape layer are integrated against external impacts. This acts as a buffer and prevents the painted reinforcing bars from being damaged.

The anti-corrosion reinforcing bar of the present invention covers the defective parts of the paint film on the surface of the painted reinforcing bar and the surrounding areas with a coating layer with a high anti-corrosion effect, which is a combination of the above-mentioned anti-corrosion layer mainly composed of petrolatum and the holding tape layer. Therefore, corrosion of the reinforcing bar body due to the intrusion of corrosion-causing substances such as moisture and salt from the defective parts of the coating film is effectively prevented.

In addition, the anti-corrosion layer and the holding tape layer made of petrolatum in the anti-corrosion reinforcing steel of the present invention can of course be provided before being transported to the concrete placement site, or may be provided at the concrete placement site during or after the transportation. It can be easily installed at the above-mentioned casting site to repair coating defects on coated reinforcing bars that have been subjected to bending, cutting, welding, etc., resulting in defects in the coating. It becomes a coating layer with high properties.

[Structure of the invention]

The roughening process on the surface of the reinforcing bar body used in this invention is intended to increase the adhesion strength between the reinforcing bar and concrete and improve the reinforcing effect on concrete.

FIG. 1 (Al) and FIG. 1 031 are a front view and a side view showing an example of a reinforcing bar body whose surface is textured, and there is a pair of longitudinally continuous protuberances 1 a on the left side and right side. , 1 a are formed, and a plurality of protrusions], b, lb... are formed at predetermined intervals alternately in the circumferential direction, and a reinforcing bar main body 1 It shows.

The shape of the uneven processing applied to the reinforcing bar body is not limited to that shown in FIG. 1 (A and (Bl) above,
For example, a spiral shape, a screw thread shape, a diagonal thread shape, etc. can be mentioned. The thickness of the reinforcing bar main body is determined depending on the purpose, but normally one with a diameter of about 6 to 50 mm is used.

In addition, the degree of unevenness on the surface of the reinforcing bar body is determined by JIS-G-3112 etc. according to the thickness of the reinforcing bar body, and the height of the convex part is 0.3 to 5 mm, as shown in Figure 1 above ( A)
, (B), the distance between the convex portions in the circumferential direction is about 4.4 to 36+++ m.

A coated reinforcing bar can be obtained by providing an anticorrosive coating on the surface of the reinforcing bar body. This anticorrosive coating is not particularly limited as long as it is flexible and has good adhesion to the reinforcing steel body, and more preferably has good alkali resistance and adhesion to concrete, such as epoxy resin, urethane, etc. Examples include coating films made of resin such as resin. Among these coatings, coatings made of epoxy resin with excellent corrosion resistance are preferred because they have particularly good properties. Methods such as solution coating, powder coating, and melt coating are used, but powder coating is preferred among these.The thickness of this anticorrosive coating is usually 100 to 30 mm.
It is recommended that the thickness be approximately 0/20" (if this thickness is too thin, pinholes will occur frequently and the anti-corrosion performance will deteriorate, so it is undesirable; on the other hand, if it is too thick, the unevenness of the surface of the painted reinforcing bars will become small, making it difficult to adhere to the concrete. This is not preferable because the strength decreases, the bending workability deteriorates, and the cost increases.

The anti-corrosion reinforcing bar of the present invention has a structure in which an anti-corrosion layer containing petrolatum as a main component and a retaining tape layer covering this anti-corrosion layer are provided on the defective part of the coating film on the surface of the painted reinforcing bar and its surrounding area. The above-mentioned coating film defects include pinholes, scratches during transportation or bending, joints such as welding or gas pressure welding, and cut parts where the reinforcing bar body is exposed. Further, the above-mentioned peripheral area refers to the area near the defect, which is usually about 1 to 10 cm from the periphery of the defective area, but it may be narrower or wider than this.

Petrolatum, the main component of the above-mentioned anticorrosive layer, is a grease-like substance extracted from petroleum and has a melting point of 38 to 60°C, and has been known for a long time as an anticorrosive material. The above-mentioned anti-corrosion layer is formed using a flexible composition in which organic additives such as polybutene and anti-aging agents and inorganic additives such as calcium arsenate, silica and alumina are blended with petrolatum.

The amount of the above-mentioned organic additive varies depending on the purpose and type of use, but it is usually about 20 to 250 parts by weight, preferably 30 to 1 part by weight, per 100 parts by weight of the above petrolatum.
The amount is 80 parts by weight. The amount of the inorganic additive used is usually 10 to 1 part by weight per 100 parts by weight of the petrolatum.
The amount is 50 parts by weight, preferably 50 to 120 parts by weight.

In addition, in this invention, the total amount of other additives added to 100 parts by weight of petrolatum is generally 20 to 30 parts by weight.
0 parts by weight, preferably 50 to 200 parts by weight. The above additives used with petrolatum in this invention have the strength of petrolatum.

It is used to improve hardness, heat resistance, etc., and generally speaking, the greater the amount added, the harder the material will be.

The flexibility of the flexibility composition composed of the above-mentioned components is usually preferably about 1.2 to 1.7. The degree of flexibility here refers to the diameter of the sample that expanded when a cylindrical sample made of the above flexible composition was molded to a diameter of 20 mm and a height of 5 mm, and was placed on a press plate and a load of 3 kg was applied at 20°C. is expressed as a ratio of the original diameters. The above-mentioned cylindrical sample is formed by using an aluminum plate with a thickness of 2 gates as a press plate, and placing 3 to 9 weights on the upper aluminum plate.

The degree of flexibility of the above flexibility composition can be easily adjusted by changing the types and amounts of various additives added to the petrolatum. If this flexibility is too low, it will be difficult to adapt to the irregularities on the surface of the painted reinforcing bars, which is undesirable. If it is too high, the workability when providing a corrosion protection layer on the surface of the painted reinforcing bars will deteriorate, and the function as a cushioning material will deteriorate, so it is not desirable. do not have.

In order to use this flexible composition to provide an anticorrosion layer on the paint film defect area and its surrounding area on the surface of the above-mentioned painted reinforcing steel, this composition may be applied directly to the surface of the above-mentioned painted reinforcing steel; The composition may be applied to one side of a retaining tape constituting the retaining tape layer shown below, and then wrapped together with the retaining tape around the surface of the painted reinforcing bar from the composition side.

The thickness of the anti-corrosion layer provided in this way is usually 5.
The thickness is approximately 0.00 to 3,000 μm, and is provided so as to completely cover defective parts of the coating film and usually fill in the recesses of the painted reinforcing bars. At this time, if a gap occurs between the surface of the painted reinforcing bar and the anti-corrosion layer, this gap tends to become a water supply and may adversely affect the anti-corrosion performance, so such a gap should be avoided.

Since the thicker the reinforcing bar body, the deeper the recess becomes, it is preferable to adjust the composition of the flexible composition so that a thick anticorrosion layer can be formed.

The holding tape layer covering the above-mentioned anti-corrosion layer is provided to protect the anti-corrosion layer since it is flexible. As the holding tape constituting this holding tape layer, a polymer film, an adhesive tape having a polymer film as a support and an adhesive layer provided on one side thereof, or the like is used.

The above-mentioned polymer film is not particularly limited as long as it can fulfill the protective function of the above-mentioned anti-corrosion layer, but in order to enhance the anti-corrosion effect, a film with good alkali resistance and flexibility is preferable. Examples of the polymer film include films made of butyl rubber, polyethylene, polyvinyl chloride, and the like. The above-mentioned adhesive tape is one in which a conventional adhesive layer made of a butyl rubber adhesive, a natural rubber adhesive, etc. is provided on one side of this polymer film.

To provide the above-mentioned retaining tape layer, the above-mentioned retaining tape may be wound in a sushi-wrap or spiral shape on the anti-corrosion layer provided on the surface of the painted reinforcing bars, or the above-mentioned retaining tape may be formed into a tube shape and then A method of fitting the above-mentioned anti-corrosion layer to cover it, or a method of applying a flexible composition to form an anti-corrosion layer on one side of the above-mentioned retaining tape and then wrapping the above-mentioned composition side around the surface of the painted reinforcing bar as described above. be.

The thickness of the holding tape layer formed in this way is usually 100 to 1,000. It is preferable to set it to about l'1. If this thickness is too thin, the protective function for the anticorrosion layer will be insufficient, which is not preferable, and if it is too thick, the workability of winding it around the surface of the anticorrosion reinforcing bar will be poor, which is not preferable.

The above-mentioned petrolatum-based anti-corrosion layer and holding tape layer can be provided before transporting the concrete to the concrete placement site, and may also be subjected to processing such as bending, welding, gas pressure welding, cutting, etc. during or after the above-mentioned transport. It can be easily installed at the site where concrete is placed in the areas where the coating film is defective and its surrounding areas, thereby reliably preventing corrosion of the reinforcing bar body caused by the defective areas of the coating film. At the same time, it also functions as a buffer material, preventing external shocks from being directly transmitted to the painted reinforcing steel.

In addition, in this invention, as described above, the reliability of the anti-corrosion effect is increased by providing the above-mentioned petrolatum-based anti-corrosion layer and retaining tape layer on the defective parts of the coating film on the surface of the painted reinforcing bars and the surrounding areas thereof. However, from the viewpoint of improving reliability, the above-mentioned anti-corrosion layer and holding tape layer may be provided on the entire surface of the painted reinforcing bars as necessary. However, when provided over the entire surface, it is desirable to set the thickness of the anti-corrosion layer and the holding tape layer so that the surface of the anti-corrosion reinforcing bar has an uneven shape so as to maintain adhesive strength with the concrete. Additionally, even if there are no coating defects on the surface of the painted reinforcing bars, the anti-corrosion layer and retaining tape layer can be provided in locations that are susceptible to external shocks and function as a buffer, thereby increasing the reliability of the anti-corrosion effect. can.

FIG. 2 is a partial cross-sectional view showing an example of anti-corrosion reinforcing bars of the present invention using the reinforcing bar bodies shown in FIGS. 1(A) and CB), and more specifically corresponds to the longitudinal cross-section of FIG. This shows the structure of anti-corrosion reinforcing bars. In the figure, 1 is the reinforcing bar body whose surface has an uneven shape, and 2 is an anticorrosion coating film provided on the entire surface of the reinforcing bar body 1 while maintaining the above-mentioned uneven shape. Reference numeral 3 indicates a painted reinforcing bar consisting of the above-mentioned reinforcing bar body 1 and an anticorrosive coating film 2, and 4 indicates a coating film defect portion occurring on the surface of this painted reinforcing bar 3. Reference numeral 5 denotes an anticorrosion layer mainly composed of petrolatum, which covers the coating film defect portion 4 and its surrounding area, and is provided so as to fill in the recesses on the surface of the painted reinforcing bar 3. Reference numeral 6 denotes a holding tape layer provided to cover the entire surface of the anti-corrosion layer 5, and protects the anti-corrosion layer 5.

The anti-corrosion reinforcing bars of the present invention constructed as described above have been effectively anti-corrosion treated and therefore are highly reliable as reinforcing bars for concrete.

〔Example〕

Examples of this invention will be described below. In addition, in the following, parts mean parts by weight.

Example A reinforcing bar body (diameter 1jjtm, length 50cm,
Height of the protrusions is 1.0m, distance between the protrusions in the circumferential direction is 11m)
The entire surface of the steel bar was powder coated with an epoxy resin powder coating to form an anticorrosive coating made of epoxy resin with a thickness of 200 pn, thereby obtaining a coated reinforcing bar.

The above epoxy resin powder coating is bisphenol A.
It is made by blending 100 parts of type epoxy resin (epoxy equivalent: 650), 1 part of dicyandiamide, 2 parts of 2-methylimidazole, 5 parts of finely powdered silica, and 1 part of a fluidity regulator.

The above-mentioned painted reinforcing bar was bent at -10°C so that the radius of curvature at the bending point of the reinforcing bar was 8 times the diameter of the reinforcing bar, and a crack was generated in the anticorrosive coating at a portion extending approximately 5 cIn at the bending point. .

On the other hand, a flexible composition (flexibility as described above of 1.3) consisting of 100 parts of petrolatum (melting point 45°C), 80 parts of butyl rubber, and 50 parts of silica was prepared to a thickness of 100°C. A holding tape with a flexible composition layer having a width of 20 mm was obtained by coating one side of the polyvinyl chloride film of ``'' to a thickness of 2 mm.

Wrap this retaining tape with a flexible composition layer around the bent part of the painted reinforcing bar in a half-wrap while pressing down so as to embed the irregularities on the surface of the painted reinforcing bar, completely covering the area where the anti-corrosion coating is coated and the surrounding area. The corrosion-resistant reinforcing bars of this invention were obtained.

When this anti-corrosion reinforcing bar was left for 1,000 hours at 35°C under sprayed saline solution with a concentration of 5% by weight, there was no deterioration of the anti-corrosion coating as well as the anti-corrosion layer, and no rust was observed on the main body of the reinforcing bar. Ta.

Further, when the above-mentioned anti-corrosion reinforcing bars were left in a 15% by weight aqueous caustic soda solution at 20°C for 1,000 hours, good anti-corrosion effects were obtained in the same manner as above.

[Brief explanation of the drawing]

Fig. 1(A) is a front view showing an example of a reinforcing bar main body constituting the anti-corrosion reinforcing bar of the present invention, Fig. 1 @) is a side view of the reinforcing bar main body shown in Fig. 1(A) above, and Fig. 2 is a Above figure 1 (A)
, Q3) is a partial sectional view showing an example of the anti-corrosion reinforcing bar of the present invention using the reinforcing bar main body shown in FIG. 1...Reinforcing bar body, 2...Anti-corrosion coating, 3. Painted reinforcing bar,
4. Paint film defect area, 5. Corrosion protection layer, 6... Retaining tape layer Patent applicant Nitto Electric Industry Co., Ltd. m1 Figure a

Claims (2)

[Claims] (1) Painted reinforcing bars with an anti-corrosion coating on the surface of the reinforcing bar body with an uneven surface, an anti-corrosion layer mainly composed of petrolatum provided on the coating film defects on the surface of the painted reinforcing bars and the surrounding areas, and Anti-corrosion reinforcing steel consisting of a retaining tape layer covering an anti-corrosion layer. (2) The anti-corrosion reinforcing bar according to claim (1), wherein the anti-corrosion coating is an epoxy resin coating.