JP3930841B2 - Reinforcing bar with highly anti-adhesive coating and method for producing the same - Google Patents

Description

  The present invention relates to a reinforcing bar material with an anticorrosion coating with improved adhesion performance to concrete.

Japan Society of Civil Engineers Concrete Library No.58 “Guidelines for Design and Construction of Reinforced Concrete Using Epoxy Resin Painted Reinforcement (draft)” Page 19 Japanese Patent Publication No. 6-16868 JP 2001-90254 A JP 2001-146567 A

  In recent years, corrosion of reinforcing bars has progressed due to the influence of concrete aggregates and the like, and various accidents occur frequently, which has become a problem. Therefore, as can be seen in Patent Document 1 and the like, an epoxy-coated reinforcing bar in which an anticorrosion coating is formed by spraying an epoxy powder coating on the surface of the heated reinforcing bar material to be melted and adhered has been developed. The problem of rebar corrosion seems to have been solved, except for the pinhole problem that inevitably occurs.

  However, as can be seen in Non-Patent Document 1, it is known that when epoxy coating is applied to reinforcing bars, long-term adhesion to concrete is reduced to about 80% of the value of uncoated reinforcing bars and concrete. This has a significant effect on the strength of the concrete structure and is a serious problem with regard to its life.

  The invention described in Patent Document 2 has been proposed in order to solve such a problem, and an anticorrosion coating using a synthetic resin powder coating (specifically, a thermoplastic polyethylene isophthalate terephthalate copolymer). In the reinforcing bar material formed with the above, the surface of the anticorrosion coating is characterized by spraying inorganic particulates such as silica sand, ceramic powder such as alumina powder, glass powder, etc. to improve the adhesion performance to concrete.

  This conventional example will be described with reference to FIG. First, as shown in FIG. 4A, shot blasting is performed on the reinforcing bar 41 to remove rust and dirt on the surface of the reinforcing bar 41 and to roughen the surface of the reinforcing bar 41 to make it rough. Thereafter, as shown in FIG. 4B, the reinforcing bar 41 is heated, and as shown in FIG. 4C, the surface of the reinforcing bar 41 having a predetermined temperature (260 to 400 ° C.) is applied. Then, the synthetic resin powder coating 44 is sprayed to melt and adhere. Then, as shown in FIG. 4D, while the synthetic resin powder coating 44 is in a molten state, the inorganic particulate matter 40a is sprayed and subjected to a cooling process, as shown in FIG. In this way, a rebar material with a highly adhered anticorrosion coating in which the inorganic particulate matter 40a is fixed to the surface of the anticorrosion coating 42 is obtained.

  According to this conventional example, by spraying the inorganic particulate matter 40a while the synthetic resin powder coating 44 is in a molten state, a part of the inorganic particulate matter 40a is buried in the anticorrosion coating 42 and fixed to the anticorrosion coating 42, The other portions are exposed on the anticorrosion coating 42 to form innumerable protrusions (irregularities), and the adhesion performance to the concrete is improved in spite of the reinforcing bars with the anticorrosion coating.

  However, in this conventional example, since different materials are bonded to the surface of the anticorrosion coating 42, it is said that a part of the inorganic particulates 40a is bonded to the anticorrosion coating 42. No, there is a high possibility that the inorganic granular material 40a is peeled off due to contact with other objects, and it is assumed that the adhesion performance is remarkably lowered due to the deterioration of the anticorrosion coating 42 over time.

  In addition, when a synthetic resin powder coating 44 such as an epoxy powder coating is sprayed on the heated reinforcing bar material 41 and melt-bonded to form the anticorrosion coating 42, generally several pinholes per 1 m of the reinforcing bar material are used. (Very small bubbles) are inevitably generated, so pinhole inspection is performed on the entire length of all products, and it is confirmed that the number of pinholes is less than the allowable value before shipping to the factory. However, in the above-mentioned conventional example, since one layer of the anticorrosion coating 42 is formed and the inorganic granular material 40a is sprayed on the surface thereof, the pinhole generated in the one layer of the anticorrosion coating 42 is a weak point in the anticorrosion performance as it is. Will remain as.

  Patent Document 3 does not disclose a technique for increasing the adhesion of reinforcing steel to concrete, but as a rust-proof paint for steel, it does not include conventional solvent-type zinc rich paint or solvent-free zinc rich paint ( Zinc metal powder, zinc-rich powder paint made by mixing epoxy resin and hardener as binder component) and zinc-rich powder paint on steel material heated to 120-250 ° C. A technique for forming an anticorrosion film by spraying with a method such as the above is described.

  The present invention has been made in consideration of the above-mentioned matters. The purpose of the present invention is to form a two-layered upper and lower anti-corrosion coating on the surface of the reinforcing bar material by spraying a powder coating material, so that the anti-corrosion coating is inevitable. To provide a highly reinforcing anticorrosive coating-coated reinforcing bar that can increase the adhesion to concrete by forming numerous countless protrusions with the second anticorrosive coating and simultaneously solving the problem of pinholes that occur is there.

In order to achieve the above object, technical measures taken by the present invention are as follows. That is, the reinforcing bar with a highly adhered anticorrosive coating according to the present invention is formed on the surface of the reinforcing bar with the first anticorrosive coating by the epoxy powder coating, and on the first anticorrosive coating, the zinc metal powder , the epoxy resin, and the curing agent. The second anticorrosion film is formed by a powder coating formed by mixing the two, and the adhesiveness to the concrete is enhanced by innumerable protrusions formed by the second anticorrosion film (claim 1).

According to the present invention, a method of manufacturing a reinforcing bar material with a high adhesion anticorrosive coating heats the reinforcing bar material, and sprays an epoxy powder coating onto the reinforcing bar material while the surface temperature of the reinforcing bar material is 250 to 390 ° C. The first anticorrosive film is formed by mixing the zinc metal powder, the epoxy resin as the binder component, and the curing agent on the surface of the first anticorrosive film in a molten state. The zinc-rich powder coating is sprayed and melted to form the second anticorrosion coating, and then the first and second anticorrosion coating reinforcing bars are cooled, and the countless number formed by the second anticorrosion coating A highly reinforcing anticorrosive coated reinforcing bar material having protrusions is produced (claim 2 ).

  According to the reinforcing material with a high adhesion anticorrosive film of the present invention, even if pinholes are generated in the first anticorrosive film of the first layer, the second anticorrosive film is formed on the first anticorrosive film in a molten state. The pinhole of the first anticorrosion coating is repaired. Even if the pinhole remains unrepaired, the probability that the pinhole of the first anticorrosion coating and the pinhole of the second anticorrosion coating match is almost zero, so the anticorrosion caused by the pinhole of the first anticorrosion coating The weak point on performance is covered with the second anticorrosion coating, and the weak point on the anticorrosion performance due to the pinhole of the second anticorrosion coating is covered with the first anticorrosion coating. As a result, high anticorrosion performance can be secured.

Still, a second anticorrosion film made of a powder paint in which zinc metal powder , an epoxy resin and a curing agent are mixed is formed on the first anticorrosion film made of the epoxy powder paint, and formed by the second anticorrosion film. Since the adhesion to concrete is increased by countless protrusions, there is no risk of protrusions coming off due to contact with other objects, as in the case of forming protrusions by adhering another granular material to the surface of the anticorrosion coating, High adhesion performance can be secured over many years.

According to the method for manufacturing a reinforcing bar with a highly adhered anticorrosive coating according to the present invention, the reinforcing bar with a highly adhered anticorrosive coating according to claim 1 can be manufactured. That is, the reinforcing bar material is heated to 250 to 390 ° C., which is higher than the general baking temperature (120 to 250 ° C.) of the zinc rich powder paint as seen in Patent Document 3, and under this high temperature condition, In addition to spraying an epoxy powder coating to form a first anticorrosion coating, subsequently, zinc metal powder and a binder component are formed on the surface of the first anticorrosion coating in a molten state under the same high temperature conditions. since forming the second corrosion protective coating by spraying zinc rich powder paint epoxy resin and a curing agent and is formed by mixing the binder component of the powder coating (epoxy resin and curing agent), common powder coating softened than for, by the viscosity decreases sufficiently, zinc metal powder is a solid component of the powder coating is lifted locally, rigid protrusions in a state of being coated with the binder component be expressed It will be. In addition, since the first anticorrosion coating and the second anticorrosion coating are adhered in a molten state, they exhibit the same properties as a single layer coating and do not peel between the first and second anticorrosion coatings.

In addition, since the viscosity of the binder component is too high at 250 ° C. or lower, no protrusion appears in the second anticorrosive film, and at 390 ° C. or higher, the viscosity of the binder component is too low, and the zinc metal which is a solid component of the powder coating material The powder is exposed on the surface of the second anticorrosion coating, and the protrusions coated with the binder component do not appear. In other words, it is impossible to form a strong protrusion that is difficult to peel off.

Thus, by forming the second anticorrosion film on the first anticorrosion film, not only can the problem of pinholes inevitably generated in the anticorrosion film be solved, but also under a high temperature condition of 250 to 390 ° C, Zinc rich powder paint containing zinc metal powder is sprayed to cause protrusions to appear on the second anticorrosion coating itself, so there is no risk of protrusion peeling off, and there is no highly adherent anticorrosion coating rebar with high adhesion performance. It can be manufactured.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited thereby.

  FIG. 1 is a schematic cross-sectional view of a main part showing an example of a reinforcing bar with a highly adherent anticorrosive coating according to the present invention, and FIG. 2 is a key for explaining the adhesion performance between a reinforcing bar with a highly adherent anticorrosive coating and concrete C. It is typical sectional drawing of a part. 1 and 2, reference numeral 1 denotes a reinforcing bar material (for example, deformed reinforcing bar), and its surface 1a is a rough surface roughened by shot blasting. 2 is a first anticorrosion coating with an epoxy powder coating formed on the surface 1a of the reinforcing bar 1, 3 is a second anticorrosion coating with a zinc rich powder coating formed on the first anticorrosion coating 2, It has innumerable protrusions 3a formed by the first anticorrosion coating 2 itself, and these protrusions 3a bite into the concrete C so that they adhere firmly to the concrete C (stronger than in the case of unpainted reinforcing bars). Has been.

  Zinc rich powder coating is a solventless powder coating in which zinc metal powder, which is a solid component, and epoxy resin, which is a binder component, and a curing agent are mixed. The blending ratio is set to 86% by weight of zinc metal powder, 14% by weight of epoxy resin and curing agent, for example. 3a is an infinite number of protrusions formed by the second anticorrosive coating 3, and zinc metal powder, which is a solid component of the zinc rich powder coating, is coated with an epoxy resin and a curing agent, which are binder components of the zinc rich powder coating. It is in the state.

  Next, the manufacturing method of said rebar with a highly adherent anticorrosion coating will be described with reference to FIG. First, as shown in FIG. 3A, shot blasting is performed on the reinforcing bar material 1 to remove rust and dirt on the surface 1a of the reinforcing bar material 1, and the surface 1a of the reinforcing bar material 1 is roughened and roughened. .

  After that, as shown in FIG. 3B, the reinforcing bar 1 is heated to 250 to 390 ° C. by a known heating means.

  Next, as shown in FIG. 3C, the epoxy powder coating material 4 is sprayed on the surface 1a of the reinforcing bar 1 heated to 250 to 390 ° C. to be melt-adhered, and shown in FIG. As described above, the first anticorrosive film 2 having a thickness of 150 to 200 μm is formed.

  And on the surface of the 1st anti-corrosion coating 2 in a molten state on the same temperature conditions (250-390 degreeC), the zinc metal powder a as a solid component is 86 weight%, the epoxy resin b as a binder component, and a hardening | curing agent. The second anticorrosive coating 3 is formed by spraying the zinc rich powder coating 5 in which c is set to 14% by weight to be melted and adhered, and then the first and second anticorrosion coating reinforcing bars are cooled. As shown in FIG. 3E, a reinforcing bar material with a highly adhered anticorrosion coating having innumerable protrusions 3a formed by the second anticorrosion coating 3 is manufactured.

  According to the above manufacturing method, the reinforcing bar 1 is heated to 250 to 390 ° C., which is higher than the general baking temperature (120 to 250 ° C.) of the zinc rich powder coating as shown in Patent Document 3. The surface of the first anticorrosion coating 2 in a molten state is not only formed by spraying the epoxy powder coating 4 under the high temperature conditions to form the first anticorrosion coating 2 but also under the high temperature conditions (250 to 390 ° C.). In addition, since the second anticorrosive coating 3 is formed by spraying the zinc rich powder coating 5, the binder component (epoxy resin b and the curing agent c) of the zinc rich powder coating 5 is a general one using a zinc rich powder coating. As a result of softening and lowering of viscosity than in the case of typical powder coating, the zinc metal powder a which is a solid component of the zinc rich powder coating 5 is locally lifted and is firmly coated with the binder component. So that the protrusions (3a) are expressed.

  In this way, the second anticorrosion coating 3 is formed by spraying the zinc rich powder coating 5 on the first anticorrosion coating 2 in a molten state under a high temperature condition of 250 to 390 ° C. Therefore, the second anticorrosion coating 3 is formed. Since the protrusion 3a can be developed on the coating 3 itself, and there is no possibility that the protrusion 3a peels off, high adhesion performance can be ensured.

  In addition, since the second anticorrosion coating 3 is formed by spraying the zinc rich powder paint 5 on the first anticorrosion coating 2 in the molten state, even if a pinhole occurs in the first anticorrosion coating 2 of the first layer. By forming the second anticorrosion coating 3 on the pinhole of the first anticorrosion coating 2, the pinhole of the first anticorrosion coating 2 is restored, even if the pinhole remains unrepaired. Since the probability that the hole and the pinhole of the second anticorrosion coating 3 match is almost zero, the second anticorrosion coating 3 covers the weak point in the anticorrosion performance due to the pinhole of the first anticorrosion coating 2, The weak point in the anticorrosion performance resulting from the pinhole of the anticorrosion coating 3 is covered by the first anticorrosion coating 2, and as a result, high anticorrosion performance can be ensured.

  By the way, D25 (mm) rebar with anti-corrosion coating and D25 (mm) uncoated rebar manufactured by the above method were used as test specimens, and a bond strength test between the rebar and concrete was conducted by a pull-out test. However, the following results were obtained. The test method was in accordance with the Japan Society of Civil Engineers standard "JSCE-G503 pullout test adhesion strength test method for reinforcing steel and concrete", and the degree of adhesion stress when the free end slip was 0.002D = 0.05 mm was obtained. . The degree of adhesion stress was determined by the following equation.

In the above formula, τ: degree of adhesion stress (N / mm ² )
P: Tensile load (N)
D: Nominal diameter of the reinforcing bar (mm)
α: Correction factor for compressive strength of concrete

  Table 1 shows the results of the adhesion strength test of the rebar material with a highly adhered anticorrosion coating.

  Table 2 shows the results of the adhesion strength test for uncoated reinforcing bars.

  Table 3 shows the adhesion stress-slip amount curve of the rebar with a highly adhered anticorrosion coating.

  Table 4 shows adhesion stress-slip amount curves of unpainted reinforcing bars.

  From these tables, the long-term adhesion strength of the rebar with a highly adherent anticorrosion coating according to the present invention is about 1.5 to 2.5 times, even when compared to uncoated rebar with higher adhesion strength than epoxy resin-coated rebar. It can be seen that it increases. This means that the problem of the epoxy resin-coated reinforcing bar whose long-term adhesion strength is reduced has been completely solved.

  Moreover, when the anticorrosion performance was compared with other anticorrosion coated reinforcing bars, the results shown in Table 5 were obtained. Of the specimens shown in Table 5, the coated coated reinforcing bar A is a reinforcing bar with a highly anticorrosive coating produced by the method of the present invention, and the coated coated reinforcing bar B is an epoxy resin coated reinforcing bar.

1 is a schematic cross-sectional view of a reinforcing bar with a highly adherent anticorrosive coating according to the present invention. BRIEF DESCRIPTION OF THE DRAWINGS It is typical sectional drawing explaining the adhesion performance of the reinforcing material with a high adhesion anti-corrosion film concerning this invention, and concrete. It is explanatory drawing of the manufacturing method of the rebar with a high adhesion anti-corrosion film concerning the present invention. It is explanatory drawing of the manufacturing method of the conventional rebar material with a highly adhesion anti-corrosion coating.

Explanation of symbols

1 Rebar material
2 First anticorrosion coating
3 Second anticorrosion coating
3a protrusion

Claims (2)

The first anticorrosion film by the epoxy powder coating is formed on the surface of the reinforcing bar material, and the second anticorrosion film by the powder coating in which zinc metal powder , epoxy resin and curing agent are mixed on the surface of the first anticorrosion film. Reinforcing bar material with a high adhesion anticorrosion coating, characterized in that the adhesion to concrete is enhanced by countless protrusions formed by the second anticorrosion coating. While the reinforcing bar material is heated and the surface temperature of the reinforcing bar material is 250 to 390 ° C., the first anticorrosive coating is formed by spraying an epoxy powder paint on the reinforcing bar material to be melted and adhered, and this temperature condition Then, a zinc rich powder coating material in which a zinc metal powder, an epoxy resin as a binder component, and a curing agent are mixed is sprayed on the surface of the first anticorrosive coating in a molten state to melt and adhere to the second. Forming the anticorrosion coating, and then cooling the reinforcing bars with the first and second anticorrosion coatings to produce a highly adherent anticorrosion coating with reinforcing coatings with innumerable protrusions formed by the second anticorrosion coating. The manufacturing method of the reinforcing bar with the anticorrosion film characterized by the above .

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