JP2011147845A - Highly durable and corrosion resistant steel, and method and apparatus for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide highly durable and corrosion resistant steel having excellent reliability, capable of sustaining adhesion strength to steel for a long time. <P>SOLUTION: The highly durable and corrosion resistant steel includes steel and a resin film formed on the surface of the steel and made to adhere thereto, which resin film is made from a mixture comprising a polyvinyl butyral resin of a butyralization degree of from 40 to 85 mol% with the content of hydroxy groups in its molecule controlled within a range of from 11 to 27 wt.% as its main component, and an organic antioxidant added thereto in an amount of not greater than 5 wt.% relative to the amount of polyvinyl butyral resin. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a highly durable anticorrosive steel material used for, for example, a concrete rebar, a manhole cover, a manufacturing method thereof, and a manufacturing apparatus.

  Conventionally, in order to prevent corrosion of a reinforcing bar for concrete, an epoxy resin powder is adhered to the surface of the reinforcing bar material to form a first epoxy resin film, and zinc powder and an epoxy resin are formed on the first epoxy resin film. There has been proposed a reinforcing bar in which a mixed powder of a powder and a hardener powder is attached to form a second epoxy resin film having countless protrusions (irregularities) made of zinc powder.

  However, since the thermosetting epoxy resin is applied to the reinforcing bars, if the anticorrosion reinforcing bars are bent, cracks and the like are likely to occur in the coating film.

  Usually, when a resin coating film is formed on the surface of a reinforcing bar, the adhesion strength of the concrete to the reinforcing bar decreases to about 85%. As described above, zinc powder is used to increase the concrete adhesion strength, but zinc may be deteriorated by chloride ions. As described above, when the reinforcing bar is bent, cracks and the like are likely to occur in the coating film, and chloride ions enter from the crack and induce further deterioration of the zinc powder. There is a disadvantage that it is not suitable for harbor structures.

  In addition, in the process of manufacturing a coated steel material using a thermosetting resin powder such as an epoxy resin, zinc having a flow index of 5 or less and a particle size of about 100 μm to 2 mm from the melting of the powder coating to the completion of curing. When spraying and fixing inorganic powders such as above onto the above-mentioned resin coating, the melting temperature was controlled by experience, resulting in variations in unevenness due to inorganic powders, variations in concrete adhesion strength, and stable quality rebars. There is a disadvantage that it cannot be obtained.

  FIG. 23 is a manufacturing process diagram of a conventional anticorrosion reinforcing bar, and FIG. 24 is a schematic diagram for explaining powder coating by an electrostatic powder spray method.

  The anticorrosion reinforcing bar by the electrostatic powder spray method goes through processes (hereinafter abbreviated as P) 11 to P20 as shown in FIG.

P11:
In this example, steel bars for reinforced concrete are prepared as steel materials. Details of the steel bars for reinforced concrete are described in JIS G 3112.
P12:
In steel bar acceptance inspection, steel materials that have an unsuitable surface shape for coating due to deformation or the like are excluded.
P13:
By blasting, the mill scale is removed and the surface of the coating is adjusted. The surface roughness of the steel bar after the surface adjustment is about Rmax 30 to 60 μm.
P14:
The steel bar is preheated so that the powder is melt coated in the next powder coating. Preheating is performed at about 200 to 250 ° C. by high frequency induction heating.

P15:
Powder coating is performed by an electrostatic powder spray method, and a resin film made of epoxy resin (thermosetting resin) is formed on the surface of the reinforcing bar. The electrostatic powder spray method will be described later with reference to FIG.
P16:
For those having a small heat capacity such as small diameter steel bars, post-heating is performed as necessary.
P17:
For a large-diameter steel bar or the like having a large heat capacity, an excessive amount of heat is prevented from being supplied to the coating film that has already been cured, and the bar steel is cooled to a temperature at which it can be handled safely. For cooling, an air cooling method or a water cooling method is used.
P18:
The steel bar on which the coating film is formed is inspected for appearance, film thickness, presence / absence of pinholes, bending workability, hardness, impact resistance, and the like.
P19:
Pack the entire bundle of steel bars with cushioning material.

P20:
Ship the packed product.
Next, powder coating by the electrostatic powder spray method will be described with reference to FIG. In the figure, 91 is a powder gun, 92 is a diffuser attached to the tip of the powder gun 91, 93 is a high voltage generator for supplying a high voltage to the diffuser 92, and 94 is an object to be powder coated. In this example, steel bar is the object to be coated. 95 is a powder paint, and 96 is a powder sprayed from the powder gun 91 toward the object 94.

  The powder of epoxy resin is supplied to the powder gun 91 as a powder coating 95 by pneumatic transportation, and is sprayed from the tip of the powder gun 91 toward the object 94 to be coated. A diffuser 92 is attached to the tip of the powder gun 91, and a high voltage is applied to the diffuser 92 from a high voltage generator 93, while the object 94 is grounded.

  Therefore, corona discharge occurs from the diffuser 92 toward the object 94, and the powder 96 supplied to the inside is charged by ion impact (-e) and is applied to the surface of the object 94 by the action of Coulomb force. To be attached. Since the article 94 is preheated to about 200 to 250 ° C. and is in a high temperature state, the adhered powder 96 immediately melts to form a resin coating. By traveling while rotating the object 94, the object 94 having a resin coating formed on the entire periphery can be continuously manufactured.

JP 2003-127282 A JP-A-61-120671

Japan Society of Civil Engineers: Adhesive strength test of epoxy resin-coated reinforcing bars in the design and construction policy of reinforced concrete using epoxy resin-coated reinforcing bars (JSCE-E 516-2003)

  As described above, since the epoxy resin, which is a thermosetting resin, is conventionally applied to the reinforcing bars, if the anticorrosion reinforcing bars are bent, cracks and the like are likely to occur in the coating film, so that a sufficient anticorrosive effect cannot be obtained. have.

  In addition, zinc powder is used to increase the concrete adhesion strength, but zinc may be deteriorated by chloride ions. When the reinforcing bar is bent, cracks and the like are likely to occur in the coating film, and there is a disadvantage that chloride ions enter from the cracks and induce further deterioration of the zinc powder.

  Furthermore, a powder coating film made of a saturated polyester resin is also formed in place of the epoxy resin, but the film made of a saturated polyester resin is not sufficiently resistant to alkali and there is a risk of being attacked by concrete alkali. is there.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a highly durable anticorrosive steel material excellent in reliability and capable of maintaining the adhesive strength with a steel material over a long period of time, a method for manufacturing the same, and a manufacturing apparatus. There is.

In order to achieve the above object, the first means of the present invention comprises:
Steel,
The main component is a polyvinyl butyral resin having a butyralization degree of 40 to 85 mol% and a hydroxyl group content in the molecule of 11 to 27 wt%, and 5 wt% with respect to the polyvinyl butyral resin. It consists of a mixture to which the following organic antioxidant is added, and has a resin film adhered and formed on the surface of the steel material.

The second means of the present invention is:
Steel,
The main component is a polyvinyl butyral resin having a butyralization degree of 40 to 85 mol% and a hydroxyl group content in the molecule of 11 to 27 wt%, and 5 wt% with respect to the polyvinyl butyral resin. It consists of a mixture to which the following organic antioxidants are added, and a resin film formed by adhesion on the surface of the steel material,
It has the inorganic coarse particle body which was fixed by the resin film and formed the innumerable protrusion part which protruded from the surface of the resin film.

  The third means of the present invention is characterized in that, in the first or second means, the content of hydroxyl groups in the molecules of the polyvinyl butyral resin is regulated in the range of 18 to 27% by weight. It is.

According to a fourth means of the present invention, in the first to third means, the organic antioxidant is an organic compound having the following molecular structural formula.

In the formula, R1 to R8: a linear or branched alkyl group having 1 to 4 carbon atoms or hydrogen,
l, m, n: each an integer of 1 to 10,
X: N or O heteroatom.

  According to a fifth means of the present invention, in the second to fourth means, the steel material is a reinforcing bar for concrete.

  According to a sixth means of the present invention, in the second to fourth means, the steel material is a stranded wire.

  According to a seventh means of the present invention, in the second to fourth means, the steel material has an edge portion on the surface, and the fine powder of the melt flow inhibitor is dispersed and held in the resin film covering the edge portion. It is characterized by that.

  According to an eighth means of the present invention, in the second to fourth means, the radius of the edge portion of the steel material is 0.5 mm or less.

The ninth means of the present invention includes
A surface adjustment step for adjusting the surface to form a resin film on the surface of the steel material;
A powder coating adhesion process in which a powder coating mainly composed of polyvinyl butyral resin is adhered to the surface of the steel material subjected to surface adjustment by an electrostatic fluidized immersion method;
A resin film forming step for heating and melting the powder coating material on the surface to form a molten resin film on the surface of the steel material by heating and melting the powder coating;
An inorganic coarse particle spraying step of spraying a high-temperature inorganic coarse particle on the molten resin film formed on the surface of the steel material;
By cooling the steel material after spraying the inorganic coarse particles, the resin film in a molten state is solidified, and the sprayed inorganic coarse particles are fixed with a resin film, and the inorganic coarse particles It includes an unevenness forming step of forming a myriad of unevenness by projecting a part of the body from the resin film.

  According to a tenth means of the present invention, in the ninth means, the degree of butyralization of the polyvinyl butyral resin is 40 to 85 mol%, and the hydroxyl group content in the molecule is regulated to a range of 11 to 27 wt%. 5% by weight or less of an organic antioxidant is added to the polyvinyl butyral resin.

  The eleventh means of the present invention is characterized in that, in the ninth means, the hydroxyl group content in the molecule of the polyvinyl butyral resin is regulated in the range of 18 to 27% by weight.

A twelfth means of the present invention is characterized in that, in the tenth or eleventh means, the organic antioxidant is an organic compound having the following molecular structural formula.

In the formula, R1 to R8: a linear or branched alkyl group having 1 to 4 carbon atoms or hydrogen,
l, m, n: each an integer of 1 to 10,
X: N or O heteroatom.

  A thirteenth means of the present invention is the ninth to twelfth means characterized in that the highly durable anticorrosive steel material is a reinforcing steel for concrete.

The fourteenth means of the present invention includes
A steel material carrying-in device for carrying in a long steel material to be processed;
An electrostatic fluidized immersion device for adhering a powder coating mainly composed of polyvinyl butyral resin to the surface of the long steel material;
A heating device that heats and melts the powder paint adhering to the surface of the steel material to form a molten resin film on the surface of the steel material; and
An inorganic coarse particle spraying device for spraying a high-temperature inorganic coarse particle on a molten resin film;
A steel material cooling device for cooling the steel material after spraying the inorganic coarse particles and solidifying the resin film, and fixing the sprayed inorganic coarse particles with the resin film;
A steel material unloading device for unloading the cooled steel material is provided.
Until the steel material carried in from the steel material carrying-in device is carried out from the steel material carrying-out device, the steel material is conveyed in a predetermined direction without rotating.

The fifteenth means of the present invention is the fourteenth means, wherein the electrostatic fluid immersion apparatus is
A lower space into which dry air is sent, and
A porous electrode disposed at the top of the lower space,
A flow space portion provided on the porous electrode and loaded with a powder coating material mainly composed of polyvinyl butyral resin and through which the long steel material is inserted,
A high voltage generator for applying different charges to the porous steel and the long steel material inserted through the flow space, and
Powder coating material supply means for feeding polyvinyl butyral resin powder into the flow space;
A powder coating material recovery means for recovering the powder coating material that has not adhered to the long steel material in the flow space is provided.

According to a sixteenth means of the present invention, in the fourteenth or fifteenth means, the inorganic coarse particle spraying device comprises:
A coarse grain spraying chamber formed so as to surround the entire circumference of the long steel material carrying the molten resin coating, and the inner side facing the long steel material of the coarse grain spraying chamber A narrowed narrow part is formed in the
A mixed flow of high-temperature coarse particles and air is supplied to the coarse-particle spraying chamber, and is injected onto the peripheral surface of the steel material carrying the molten resin film through the narrowed portion. It is characterized by being.

  The present invention is configured as described above, and can provide a highly durable anticorrosive steel material excellent in reliability that can maintain an adhesive strength with a steel material over a long period of time, a manufacturing method thereof, and a manufacturing apparatus.

It is a figure for demonstrating the manufacturing process of the highly durable corrosion-resistant steel materials which concern on embodiment of this invention. It is a schematic block diagram of the whole manufacturing apparatus of the highly durable corrosion-resistant steel materials which concern on embodiment of this invention. It is a schematic block diagram of the electrostatic fluid immersion apparatus used by embodiment of this invention. It is a front view of the coarse grain spraying apparatus used by embodiment of this invention. It is a side view of the coarse grain spraying apparatus. It is a top view of the coarse particle spraying device. It is a perspective view of the coarse grain spraying device. It is a front view of the coarse grain spraying part in the coarse grain spraying apparatus. It is a side view of the coarse grain spraying part. It is the top view which made a part of the coarse grain spraying part the cross section. It is a partially expanded perspective view of the vicinity of the heated air introduction chamber in the coarse particle spraying part. It is an expanded sectional view on the FIG. 8A line. It is a principal part expanded sectional view of the highly durable anti-corrosion steel material which concerns on 1st Example of this invention. It is a principal part expanded sectional view of the highly durable anti-corrosion steel material which concerns on 2nd Example of this invention. It is a principal part expanded sectional view of the highly durable anti-corrosion steel material which concerns on 3rd Example of this invention. It is a principal part expanded sectional view of the highly durable corrosion-resistant steel materials which concern on 4th Example of this invention. It is a partial expansion perspective view of the steel materials embed | buried in concrete. It is a perspective view of the test piece used for the measurement of an edge cover rate. (A), (b) It is a figure for demonstrating an edge cover rate. It is a characteristic view which shows the relationship between the edge part radius (edge R) and edge cover rate at the time of using various powder coating materials. It is a characteristic view which shows the relationship between the mica addition weight part with respect to 100 weight part of (PVB resin powder + antioxidant) of the powder coating which uses mica as a melt flow inhibitor, and an edge cover rate. It is a principal part expanded sectional view of the highly durable anti-corrosion steel material which concerns on 5th Example of this invention. It is a manufacturing-process figure of the conventional anti-corrosion reinforcement. It is the schematic for demonstrating the powder coating by an electrostatic powder spray method.

Next, embodiments of the present invention will be described with reference to the drawings.
FIGS. 13 to 16 are enlarged cross-sectional views of the main part of the highly durable anticorrosive steel material according to the embodiment of the present invention.

(First embodiment)
A highly durable anticorrosive steel material 80 according to the first embodiment shown in FIG. 13 is a resin coating 82 whose main component is a polyvinyl butyral resin (hereinafter abbreviated as PVB resin), which will be described later, on the surface of a steel material 81 such as a steel plate. It has a covered configuration.

(Second embodiment)
A highly durable anticorrosive steel material 80 according to the second embodiment shown in FIG. 14 covers the surface of a steel material 81 such as a steel plate with a resin coating 82 containing PVB resin as a main component, and has a predetermined particle size on the resin coating 82. The inorganic coarse particles 83 are fixed by spraying.

(Third embodiment)
A highly durable anticorrosive steel material 80 according to the third embodiment shown in FIG. 15 has a resin coating 82 whose main component is PVB resin on the surface of a steel material 81 made of a stranded wire formed by twisting a plurality of strands 84. In addition, the inorganic coarse particles 83 having a predetermined particle diameter are sprayed and fixed to the resin coating 82.

(Fourth embodiment)
A highly durable anticorrosive steel material 80 according to the second embodiment shown in FIG. 16 covers the surface of a steel material 81 such as a steel bar or a steel wire with a resin coating 82 containing PVB resin as a main component, and the resin coating 82 has a predetermined thickness. The inorganic coarse particles 83 having a particle diameter are fixed by spraying.

  In the case of the second to fourth embodiments, a part of the inorganic coarse particles 83 sprayed as shown in the figure protrudes from the surface of the resin film 82 to form innumerable protrusions (unevenness). Further, in the case of the third embodiment shown in FIG. 15, the resin film 82 also enters the valley portion formed between the strand 84 and the strand 84 at the outer periphery, and the resin coating 82 is applied to the steel material 81. Is in good contact.

  Although not shown, depending on the application, the highly durable anticorrosive steel material 80 having a configuration in which the surface of the steel material 81 made of the stranded wire is covered with a resin coating 82 containing PVB resin as a main component can be used as it is. .

  As the steel material 81, for example, various steel materials such as a steel bar, a deformed steel bar, a screw steel bar, a steel wire, a stranded wire formed by twisting a plurality of strands, a steel plate, a steel pipe, H steel, and an angle are used.

  The PVB resin is a polymer compound having a three-dimensional structure obtained by condensing polyvinyl alcohol and an aldehyde using an acid catalyst such as hydrochloric acid, sulfuric acid or nitric acid. As the aldehyde, an aldehyde having 2 to 6 carbon atoms is preferable, and n-butyraldehyde is particularly preferable among them.

  This PVB resin film has good adhesion to metals and inorganic coarse particles, has no deterioration even when exposed outdoors for a long period of time, has excellent weather resistance, and can sufficiently withstand the alkalinity of concrete. Have.

  The degree of butyralization of the PVB resin is 40 to 85 mol%, preferably 50 to 85 mol%. When the degree of butyralization is in the above-mentioned range, the powder coating material has excellent fluidity, and a resin film having a uniform film thickness and no pinholes can be formed. The content of vinyl ester units is 0.1 to 30 mol%, the content of vinyl alcohol units is 10 to 50 mol%, the degree of polymerization is 200 to 1700, preferably 250 to 1000, and the acid value is 0.7 mgKOH / g or less. It is.

  The content of hydroxyl groups in the PVB resin molecule is 11 to 27% by weight, preferably 18 to 27% by weight, and more preferably 18 to 21% by weight. If the hydroxyl group content in the molecule is less than 11% by weight, the adhesive strength to the steel material is insufficient because the hydroxyl group content is originally low, whereas if the hydroxyl group content in the molecule exceeds 27% by weight, It becomes water-absorbing and causes a decrease in adhesive strength. Therefore, by regulating the hydroxyl group content in the molecule to a range of 11 to 27% by weight, the adhesive strength with the steel material is strong and a high anticorrosive effect is exhibited over a long period of time.

  The PVB resin is preferably in the form of aggregated particles of primary particles. The average particle size of the primary particles is 5 μm or less, and the maximum particle size is 10 μm or less. The average particle size of the aggregated particles is 150 μm or less, and the maximum particle size is 250 μm or less. The average particle size of the aggregated particles is preferably 130 μm or less, and more preferably 100 μm or less. In addition, a primary particle is a particle | grains produced | generated initially in the acetalization reaction of polyvinyl alcohol here.

  The powder coating having such a particle diameter has excellent fluidity, can form a resin film having a uniform film thickness and no pinholes, has high adhesive strength with steel, and has a high anticorrosion effect.

  An antioxidant is added in the range of 0.02 to 5% by weight with respect to the PVB resin. When the content of the antioxidant is less than 0.02% by weight, the effect of the antioxidant is not sufficiently exhibited, and the bending resistance of the resin film is not sufficient. On the other hand, when the content of the antioxidant is more than 5% by weight, pinholes are generated in the resin film, or the adhesive strength of the resin film to the steel material tends to be lowered.

  The molecular weight of the antioxidant is 380 to 1000, preferably 400 to 800, and more preferably 600 to 800. When an antioxidant having a molecular weight of 380 or more is used, the bending resistance of the resin coating is further improved, the resin coating is not easily peeled off or cracked against the steel material, and the flowability when the resin is melted is good. It is possible to form a resin film without any. When the molecular weight exceeds 1000, the compatibility with the PVB resin decreases, and it becomes difficult to form a good resin film.

  The melting point of the antioxidant is 80 to 230 ° C, preferably 90 to 180 ° C. When having such a melting point, dry blending with PVB resin powder is possible.

Specifically, an organic compound having the following molecular structural formula is preferable as the antioxidant.

In the formula, R1 to R8: a linear or branched alkyl group having 1 to 4 carbon atoms or hydrogen,
l, m, n: each an integer of 1 to 10,
X: N or O heteroatom.

  Examples of the linear or branched alkyl group having 1 to 4 carbon atoms include methyl, ethyl, propyl, i-propyl, n-propyl, i-butyl, n-butyl, and t-butyl.

Specific examples of the antioxidant include, for example, hexamethylenebis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate],
O 3,9-bis {1,1-dimethyl-2- [β- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy] ethyl} 2,4,8,10-tetraoxaspiro [5,5] -undecane,
O N, N'-hexane-1,6-diylbis [3- (3,5-di-t-butyl-4-hydroxyphenylpropionamide)],
1,3,5-tris (4-t-butyl-3-hydroxy-2,6-xylylmethyl) -1,3,5-tridiamine-2,4,6- (1H, 3H, 5H) -trione,
2,6-di-t-butyl-4- [4,6-bis (octylthio) -1,3,5-triazinylamino] phenol,
1,3,5-tris (3,5-di-t-butyl-4-hydroxybenzyl) -1,3,5-tridiamine-2,4,6- (1H, 3H, 5H) -trione,
○ 4,4'-Butyldenbis (6-t-butyl-3-methylphenol)
And so on.

  In addition to this antioxidant, other antioxidants or phosphorus heat stabilizers, hydroxylamine heat stabilizers, sulfur heat stabilizers and the like can be used in combination.

  As the inorganic coarse particle 83, for example, one kind or a mixture of two or more kinds selected from alumina, ceramic, silica sand, glass, iron, stainless steel and the like are used. The average particle size of the inorganic coarse particles 83 used is 50 μm to 1 mm, preferably 100 μm to 1 mm.

(Manufacturing process of highly durable anti-corrosion steel)
FIG. 1 is a diagram for explaining a manufacturing process of a highly durable anticorrosive steel material according to an embodiment of the present invention.

  The highly durable anticorrosive steel material according to the embodiment of the present invention is obtained through the steps P1 to P10 shown in FIG.

P1:
In this embodiment, a steel bar for reinforced concrete is prepared as a steel material. Details of the steel bars for reinforced concrete are described in JIS G 3112.
P2:
In steel bar acceptance inspection, steel materials that have an unsuitable surface shape for coating due to deformation or the like are excluded.
P3:
Impeller-type blasting is used to remove the mill scale and to adjust the surface as a paint base. The standard of the degree of rust removal is defined as SSPC-SP10 in ASTM A 775-81 (SSPC: Steel Structures Painting Council Specification). Rust removal will be carried out to Near White Metal. For the determination of the degree of rust removal, SSPC-Vis 1 (SIS 055900) or NACE TM-01-075 No. 2 is used. The surface roughness after the surface adjustment is about Rmax 30 to 60 μm.

P4:
The steel material is passed through an electrostatic fluidized immersion apparatus, and a powder paint mainly composed of PVB resin is adhered to the outer peripheral surface of the steel material. The electrostatic fluid immersion apparatus will be described later with reference to FIG.
P5:
The steel material with the PVB resin powder coating adhered is passed through a high-frequency heating device and heated to 200-300 ° C. above the melting temperature (about 160 ° C.) of the PVB resin powder coating, whereby the PVB resin powder coating is obtained. Melt to form a molten resin film.

P6:
By passing the steel material carrying the resin film in a molten state through a spraying device, the inorganic coarse particles heated in advance are sprayed on the steel material. The spraying device will be described later with reference to FIGS.
P7:
By cooling the steel material after spraying the inorganic coarse particles, the resin film in the molten state is solidified, and the sprayed inorganic coarse particles are fixed with the resin film. A part of the inorganic coarse particles protrudes from the resin coating, and becomes a steel material having innumerable irregularities. As a cooling method, air cooling or water cooling is used.
P8:
The steel material carrying the inorganic coarse particles is inspected for appearance, film thickness, presence / absence of pinholes, bending workability, hardness, impact resistance, and the like.
P9:
The entire bundle of steel materials is packed with cushioning material.
P10:
Ship the packed product.

(Schematic configuration of high durability anticorrosion steel production equipment)
FIG. 2 is a schematic configuration diagram of the entire manufacturing apparatus for a highly durable anticorrosive steel material according to an embodiment of the present invention.

As shown in FIG. 1, a highly durable anticorrosive steel material manufacturing apparatus 100 includes a steel material carrying-in device 1 mainly composed of a conveyor, an electrostatic fluidized immersion device 2, a high-frequency heating device 3, and an inorganic coarse particle spraying device 4. And a steel material unloading device 5 composed of a conveyor, and are installed in the above-described order along the conveying direction X of the long steel material 6 as shown in the figure to constitute one production line.
In the present embodiment, a conveyor is used as the steel material conveying device, but a conveying device having another configuration such as a roller for nipping and conveying the steel material can also be used.

The electrostatic fluidized immersion apparatus 2 has a powder coating fluid tank 7 inside, and performs the above-described P4 (attachment of powder coating mainly composed of PVB resin).
The high-frequency heating device 3 has a high-frequency heating coil 8 inside, and performs the above-described P5 (melting of PVB resin powder paint).
The inorganic coarse particle spraying device 4 has an inorganic coarse particle spray gun 9 and a cooling chamber 10 inside, and performs the above-described P6 (inorganic coarse particle spraying) and P7 (cooling).
And from the steel material carrying-out apparatus 5, the resin film solidifies and the highly durable anti-corrosion-treated steel material 6 which fixed the sprayed inorganic coarse particle body with the resin film is continuously carried out.

  In this way, a series of highly durable anti-corrosion treatments of the steel material 6 are performed. As shown in FIG. 2, the steel material 6 passes through the flow tank 7, the high-frequency heating coil 8, and the spray gun 9. Thus, the highly durable anticorrosion treatment is performed without rotating the steel material 6. Moreover, between the said steel material carrying-in apparatus 1 and the steel material carrying-out apparatus 5, the elongate steel material 6 is conveyed in the tension | tensile state, without loosening.

  In the conventional manufacturing apparatus (manufacturing method) shown in FIG. 24, it is necessary to convey the object 94 while rotating, so that the mechanism of the manufacturing apparatus becomes complicated, or the long object 94 is bent and high. There is a disadvantage that the durable anticorrosion treatment is uneven. On the other hand, in the manufacturing apparatus (manufacturing method) of the present invention, since it is not necessary to rotate the steel material 6 that is the object to be coated, the apparatus is simplified, the manufacturing efficiency is good, and the steel material 6 is uniform and high. It has the feature that high-quality and durable anti-corrosion treatment is performed.

(Schematic configuration of electrostatic fluid immersion device)
FIG. 3 is a schematic configuration diagram of the electrostatic fluid immersion apparatus 2 used in the embodiment of the present invention.

  As shown in the figure, the fluid tank 7 is disposed in a powder recovery cover 11. A space 12 is formed in the lower part of the fluid tank 7, a dry air blower pipe 13 is connected to the lower space 12, and a blower 14 is provided at the base of the dry air blower 13.

  A porous electrode 15 is disposed above the space 12, and the porous electrode 15 is connected to the negative electrode of the high voltage generator 16. A porous plate 17 is disposed on the porous electrode 15, and an upper portion of the porous plate 17 serves as a fluidized space portion 19 that forms a fluidized bed of the powder 18. A powder paint supply pipe 20 is connected to the flow space 19, and a blower 21 is provided at the base of the powder paint supply pipe 20.

  A long steel material (rebar) 6 is inserted through the flow space 19, and the steel material (rebar) 6 is grounded while being conveyed. A sampling tube 22 is inserted into the flow space 19, and a powder amount detector 23 is provided at the base of the sampling tube 22.

  A powder recovery tube 24 is connected to the upper part of the powder recovery cover 11, and an attracting machine 25 is provided in the powder recovery tube 24.

  Dry air 26 is supplied from the blower 14 through the dry air blow pipe 13 to the lower space 12 of the fluid tank 7, while the powder 18 is passed from the blower 21 through the powder coating material supply pipe 20 to the flow space. 19 is supplied and filled.

  The dry air 26 supplied to the lower space portion 12 rises through the porous electrode 15 and the porous plate 17, fluidizes innumerable powders 18 in the flow space portion 19 to form a fluidized bed, The steel material (rebar) 6 is immersed in the floating layer of the powder 18 formed in a cloud shape formed on the fluidized bed. Although the boundary between the fluidized bed of the powder 18 and the cloud-like floating layer is not clear, there is a difference in the concentration distribution of the powder 18 between the fluidized bed and the cloud-like floating layer.

  By applying a high voltage (for example, 30 to 120 KV) to the porous electrode 15 by the high voltage generator 16, the dry air 26 passing through the porous electrode 15 is ionized, whereby the powder 18 has a negative charge. Have. On the other hand, the steel material (rebar) 6 is held at a positive charge by the high voltage generator 16. By passing the steel material (rebar) 6 having a positive charge through the floating layer of the powder 18 having a negative charge, the powder 18 is electrostatically attached to the peripheral surface of the steel material (rebar) 6. Charge stabilizes. As described above, the steel material (rebar) 6 passes through the floating layer, so that the powder 18 also circulates well toward the upper side of the steel material (rebar) 6, and the powder 18 extends around the entire circumference of the steel material (rebar) 6. Adheres almost uniformly.

The powder 18 that has not adhered to the steel material (rebar) 6 is recovered from the upper part of the powder recovery cover 11 through the powder recovery tube 24, and is sent to the steel material (rebar) 6 again although not shown. In the powder coating method by the electrostatic spray method shown in FIG. 24, the powder 56 made of a thermosetting resin such as an epoxy resin is electrostatically sprayed on the object 94 that has been heated in advance to a high temperature state. The powder 56 that does not undergo a slight curing reaction due to the heat generated from the article 94 to be coated. Therefore, the reuse of the collected powder 56 is avoided because it causes a deterioration in the quality of the resin coating, and therefore the yield of the powder 56 is at most about 70%.

  On the other hand, in the present invention, since the electrostatic fluidized immersion apparatus 2 is used, there is no thermal influence on the powder 18, so that the powder 18 is not altered and 100% of the recovered powder 18 is reused. In addition, the quality of the resin coating is stable even with the reused powder 18. Moreover, according to this electrostatic fluid immersion apparatus 2, since powder coating can be performed in the fluid tank 7 without scattering many powders in air | atmosphere, the working environment can be improved.

  The filling state of the powder 18 in the fluidized tank 7 is monitored by a powder amount detector 23. Based on the detection result of the powder amount detector 23, the conveying speed of the steel material (rebar) 6 and the dry air By adjusting the blowing amount, the supply amount of the powder 18, and the recovery amount of the powder 18, the adhesion amount of the powder 18 to the steel material (rebar) 6 can be controlled. In this embodiment, the adhesion amount of the powder 18 to the steel material (rebar) 6 is controlled such that the thickness of the resin coating formed by heating and melting the powder 18 is 220 ± 40 μm. Application is possible.

(Configuration of inorganic coarse particle spraying device)
4 to 7 are views for explaining the inorganic coarse particle spraying device 4, FIG. 4 is a front view of the spraying device 4, FIG. 5 is a side view of the spraying device 4, and FIG. 6 is a spraying device. FIG. 7 is a perspective view of the spraying device 4.

  A heated air generating unit 31 is installed inside a frame-shaped base 30, and an air supply pipe 33 provided with a filter unit 32 is connected to the inlet side of the heated air generating unit 31. Although not shown, a blower and a heater for heating are installed inside the heated air generator 31.

  A vertical moving frame 35 is provided on the upper portion of the base 30 via a pantograph type lifting means 34, and on the vertical moving frame 35, two pieces extending in a vertical direction toward the plane of FIG. 5. Guide rails 36 are laid at predetermined intervals. On these two guide rails 36, a coarse particle spraying portion 37 is mounted. A coarse particle supply unit 39 is provided near the coarse particle spraying unit 37.

  A heated air supply pipe 38 extends from the heated air generating unit 31 toward the coarse particle spraying unit 37. Further, a coarse particle transport pipe 40 extends from the coarse particle supply unit 39 toward the coarse particle spraying unit 37, and on the contrary, heating from the coarse particle spraying unit 37 toward the coarse particle supply unit 39. An air recycle pipe 41 and a coarse particle recycle pipe 42 extend respectively.

  The coarse particle supply unit 39 includes a coarse particle supply pipe 48 (see FIG. 7) for supplying the coarse particles 47 to the coarse particle supply unit 39 and a transportation air supply for supplying coarse particle transportation air 43. A tube 44 is connected.

  The room temperature air 45 sucked by a blower (not shown) installed in the heated air generation unit 31 passes through the filter unit 32, and dust and the like in the air 45 are removed, so that the heated air generation unit 31 is heated by an internal heater (not shown) to become heated air 46 of 100 to 200 ° C., and is supplied to the coarse particle spraying portion 37 through the heated air supply pipe 38.

  On the other hand, as shown in FIG. 7, the coarse particles 47 are supplied and stored in the coarse particle supply unit 39 through the coarse particle supply pipe 48. The heated air 46 used in the spraying of the coarse particles 47 is recovered and supplied to the coarse particle supply unit 39 through the heated air recycling pipe 41, whereby the coarse particles 47 in the coarse particle supply unit 39 are 100%. Heat to above ℃.

  The coarse particle transport air 43 is supplied to the coarse particle supply unit 39 through the supply pipe 44 at a predetermined speed, and the coarse particles 47 in the coarse particle supply unit 39 are blown through the coarse particle transport tube 40. It is transported to the attaching part 37 and involved in the spraying of the coarse particles 47. The coarse particles 47 that have not adhered to the steel material (rebar) 6 are collected and returned to the coarse particle supply unit 39 through the coarse particle recycling pipe 42 to be reused.

  As shown in FIGS. 4 and 7, a steel material insertion hole 49 is formed in the coarse grain spraying portion 37 in the horizontal direction, and a steel material (rebar) 6 carrying a molten resin film on the peripheral surface is the steel material. Coarse particles 47 are sprayed on the resin film while passing through the insertion hole 49. The inner diameter of the steel material insertion hole 49 is designed such that the coarse particles 47 sprayed on the resin film are not scraped off.

  Due to the action of the elevating means 34 and the guide rail 36, the position of the coarse grain spraying portion 37 is adjusted in the vertical direction and the horizontal direction, and the center portion of the steel material insertion hole 49 provided in the coarse grain spraying portion 37. Steel material (rebar) 6 passes through. As described above, since the steel material (rebar) 6 is conveyed in a tensioned state, the position of the steel material (rebar) 6 in the steel material insertion hole 49 hardly changes.

(Configuration of coarse particle spraying part)
8 to 12 are diagrams for explaining the details of the coarse particle spraying portion 37, FIG. 8 is a front view of the coarse particle spraying portion 37, and FIG. 9 is a side view of the coarse particle spraying portion 37. 10 is a top view in which a part of the coarse-grained body spraying part 37 is taken as a cross section, FIG. 11 is a partially enlarged perspective view in the vicinity of the heated air introduction chamber in the coarse-grained body spraying part 37, and FIG. It is an expanded sectional view on the A line.

  A box-shaped heated air introduction chamber 51 is attached to a predetermined position of one side plate 50 a in the coarse particle spraying portion 37, and a tip end portion of the heated air supply pipe 38 is connected to the heated air introduction chamber 51. . As shown in FIGS. 8, 10, and 11, the tip of the coarse particle transport pipe 40 extends through the substantially central portion of the heated air introduction chamber 51 to the inside of the side plate 50 a.

  A plurality (eight in this embodiment) of heated air introduction holes 52 are formed at equal intervals around the portion of the side plate 50a through which the coarse particle transport pipe 40 passes.

  A coarse particle spraying chamber 53 is formed between one side plate 50a of the coarse particle spraying portion 37 and the other side plate 50b opposite to the one side plate 50a. Is inserted (see FIGS. 8, 10 and 12). That is, the coarse particle spray chamber 53 is formed so as to surround the periphery of the steel material 6.

  As shown in FIG. 10 and FIG. 12, as shown in FIG. 10 and FIG. 12, the narrow particle forming member 54 having a tapered cross section, such as a convex shape, and the narrow particle forming member 54. Further, the taper-shaped narrowing member 55 attached to the distal end of the taper is provided. The steel material 6 is inserted through the central portion of the narrowing member 55, and the coarse particle spray gun 9 (see FIG. 2) surrounds the entire circumference of the steel material 6 with the narrow forming member 54 and the narrowing member 55. Is configured.

  As shown in FIGS. 8 and 9, a box-shaped recovery chamber 56 is provided below the coarse particle spraying chamber 53, and the coarse particle spraying chamber 53 and the recovery chamber 56 are connected by a recovery passage 57. As shown in FIGS. 10 and 12, in the central portion of the narrowing member 55, the coarse particles 47 are sprayed onto the steel material 6, and the coarse particles 47 and the heated air 46 that have not adhered to the steel material 6 are collected. Is provided with an opening 58, and the opening 58 is connected to the recovery passage 57.

  The coarse particles 47 sent through the coarse particle transport pipe 40 are ejected into the coarse particle spray chamber 53. On the other hand, the heated air 46 sent through the heated air supply pipe 38 is introduced into the heated air introduction chamber 51, then passes through the plurality of heated air introduction holes 52, and is dispersed in the coarse particle spray chamber 53. Is done. Here, the heated air 46 and the coarse particles 47 are mixed to form a uniform mixed flow 59, which reaches the entire coarse particle spray chamber 53.

  The mixed flow 59 increases the flow rate by passing through the narrow portion at the tip of the narrow forming member 54, and further passes through the narrowing member 55 that gradually narrows in a tapered shape, thereby further increasing the flow rate of the mixed flow 59. It becomes a jet jet.

  Since the resin film that has been melted by the high-frequency heating device 3 (see FIG. 2) is formed on the entire circumferential surface of the steel material 6 that passes through the center of the narrowing member 55, the coarse particles sprayed from the narrowing member 55 The body 47 adheres to bite into the resin film of the steel material 6. Since the spraying of the coarse particles 47 is performed simultaneously over the entire peripheral surface of the steel material 6, the adhesion state of the coarse particles 47 is substantially uniform.

  When the coarse particles 47 at room temperature are sprayed on the molten resin film, the surface of the resin film immediately cools and solidifies, so that the coarse particles 47 do not sufficiently bite into the resin film. It is difficult to fix 47 securely. On the other hand, the present embodiment sprays the mixed flow 59 of the coarse particles 47 preheated to 100 ° C. or higher and the heated air 46 of 100 to 200 ° C. onto the molten resin film. And the fixed state of the coarse particles 47 is stable.

  The coarse particles 47 and the heated air 46 that have not adhered to the steel material 6 are sent to the recovery chamber 56 through the recovery passage 57, where they are separated into the heated air 46 and the coarse particles 47, as shown in FIG. The heated air 46 is sent to the coarse particle supply unit 39 through the heated air recycle pipe 41, and the coarse particle 47 is sent to the coarse particle supply unit 39 through the coarse particle recycle pipe 42 and reused. Is done.

Next, specific examples of the present invention will be described.
(Concrete example)
D19 steel bar was used as a steel material for reinforced concrete, and the surface was adjusted by blasting. The surface roughness after the surface adjustment was about Rmax 30 to 60 μm.

This steel material is passed through the electrostatic fluid immersion apparatus 2 shown in FIG. 3, and a powder paint mainly composed of PVB resin is attached to the outer peripheral surface of the steel material 6.
The degree of butyralization of the PVB resin was 68 mol%, the hydroxyl group content in the molecule was 20 wt%, the average particle size of primary particles was 4 μm, and the average particle size of aggregated particles was 83 μm.

  As an antioxidant, N, N′-hexane-1,6-diylbis [3- (3,5-di-t-butyl-4-hydroxyphenylpropionamide) is used as an antioxidant with respect to 100 parts by weight of the PVB resin powder. And 0.5 parts by weight of the mixture was dry blended, and the mixed powder was supplied to the electrostatic fluidized immersion apparatus 2.

  The outer peripheral surface of the steel material 6 that has passed through the electrostatic fluid immersion apparatus 2 is made of PVB resin and N, N′-hexane-1,6-diylbis [3- (3,5-di-t-butyl-4- A powder paint with hydroxyphenylpropionamide)] (antioxidant) is deposited with a film thickness of 220 ± 40 μm.

  Next, the steel material 6 is passed through the high-frequency heating device 3 and heated to about 200 to 300 ° C., thereby melting the PVB resin powder paint and having a substantially uniform film thickness without any pinholes. Form. Subsequently, the steel material 6 carrying the molten resin film is supplied to the inorganic coarse particle spraying device 4.

In the coarse particle spraying device 4, alumina # 80 (average particle size: 210 μm), which is an inorganic coarse particle heated to about 150 ° C., is placed on the peripheral surface of the steel material 6 together with heated air of 100 to 200 ° C. By spraying uniformly and immediately cooling in the cooling chamber 10, the resin film 82 in the molten state is solidified, and the sprayed inorganic coarse particles 83 are fixed by the resin film 82. As shown in FIG. 14, the inorganic coarse particles 83 partly protrude from the resin coating 82 and become a highly durable anticorrosive steel material 80 having innumerable irregularities.

  For the highly durable anti-corrosion steel material obtained in this specific example and other steel materials, the bond strength of the epoxy resin-coated reinforcing bars defined in the “Design and Construction Guidelines for Reinforced Concrete Using Epoxy Resin Rebars” at the Japan Society of Civil Engineers The results of “Test” (JSCF-E 516-2003) are shown in Table 1 below.

  The coated steel bar in the table indicates that the D19 steel bar is used as it is without forming the PVB coating. Painted bar steel is made of PVB resin and N, N′-hexane-1,6-diylbis [3- (3,5-di-t-butyl-4-hydroxyphenylpropionamide) without spraying the inorganic coarse particles. ] (D19 steel bar having a resin film formed of a mixture with (antioxidant)) is used. The steel bar of the present invention indicates the steel bar obtained in the specific example.

Three steel bars are prepared and tested, and the maximum bond stress Tmax of each bar, the average value Tmax (Ave) of the maximum bond stress of the three steel materials, and the maximum bond stress average of the coated steel bars The strength ratio of the coated steel bar and the steel bar of the present invention when Tmax (Ave) is set to 100 is shown in the table.

  As is clear from this table, the coated bar steel has a polyvinyl butyral resin film formed on the surface, so the adhesion stress to concrete is almost the same as that of the painted bar steel, but the present bar steel is a painted bar steel. In addition, the maximum adhesion stress degree can be increased by 6 times or more as compared with painted bar steel, and it can be used especially for reinforced concrete.

  In addition, this test is a test for reinforced concrete, and the steel bar of the present invention has excellent adhesion stress strength to concrete, but PVB resin and N, N′-hexane-1,6-diylbis [ 3- (3,5-di-t-butyl-4-hydroxyphenylpropionamide)] (antioxidant) is a coated bar steel formed with a resin film, and the bond strength between the steel material and the resin film is also high. In addition, the resin coating itself is chemically stable for a long time.

Table 2 shows the results of measuring the adhesive strength to steel materials by changing the hydroxyl group content in the PVB resin molecules.

As is apparent from this table, the hydroxyl group content in the PVB resin molecule is 11 to 27% by weight (samples 1 to 3), preferably 18 to 27% by weight (samples 2 and 3), Preferably, 18 to 21% by weight (sample 3) has a high adhesive strength with a steel material and can exhibit a high anticorrosion effect over a long period of time. Although not described, when the hydroxyl group content in the molecule is less than 11% by weight or exceeds 27% by weight, the adhesive strength to the steel material is smaller than 6 kg / cm ² even under the same test conditions, which is sufficient. Adhesive strength cannot be obtained.

  In addition, in the said Example, although the powder coating which has PVB resin as a main component was performed on the surface of steel materials using the electrostatic fluid immersion apparatus shown in FIG. 3, PVB resin was used as the main component on the surface of steel materials by the electrostatic coating method. It is also possible to perform powder coating.

  FIG. 17 is a partially enlarged perspective view of a linear or bar-shaped steel material 81 embedded in concrete. As shown in the figure, this type of steel material 81 has a plurality of vertical ribs 85 continuously extending along the longitudinal direction of the steel material 81 on the outer peripheral surface of the steel material 81 and a predetermined length along the longitudinal direction of the steel material 81. And a transverse rib 86 extending in the circumferential direction with a spacing of.

  The plurality of vertical ribs 85 extending in the longitudinal direction of the steel material 81 are provided to increase the bending strength of the steel material 81, and the horizontal ribs 86 are provided to increase the pulling strength from the concrete. When the ribs 85 and 86 are provided in this way, edges 87 are formed on the ridge lines of the ribs 85 and 86, respectively.

  As described above, in the present invention, powder coating mainly containing PVB resin is applied to the surface of a steel material, and then heated to melt the resin powder to form a molten resin film. According to the results of various experiments by the inventors, when the resin film is formed, the film thickness of the resin film becomes thinner than desired at the edge 87 (pointed portion) as described above, or pinholes are generated. I understood.

  Next, the result of examining the covering property (edge cover property) of the resin film at the edge portion will be described.

The powder paint used is as follows.
○ Powder coating A
With respect to 100 parts by weight of PVB resin powder having a butyralization degree of 68 mol%, a hydroxyl group content in the molecule of 20% by weight, an average particle size of primary particles of 4 μm, and an average particle size of aggregated particles of 83 μm, A dry blend of 0.5 part by weight of N, N′-hexane-1,6-diylbis [3- (3,5-di-t-butyl-4-hydroxyphenylpropionamide)] as an antioxidant.

○ Powder coating B
3 parts by weight of fine powder of iron oxide having an average particle size of 0.5 μm as a melt flow inhibitor is mixed with 100 parts by weight of the powder coating A.

○ Powder paint C
A mixture of 5 parts by weight of mica fine powder having an average particle size of 21 μm as a melt flow inhibitor with respect to 100 parts by weight of the powder coating A.

○ Powder coating D
10 parts by weight of mica fine powder having an average particle diameter of 21 μm as a melt flow inhibitor is mixed with 100 parts by weight of the powder coating material A.

○ Powder paint E
5 parts by weight of mica fine powder having an average particle diameter of 41 μm as a melt flow inhibitor is mixed with 100 parts by weight of the powder coating material A.

○ Powder coating F
10 parts by weight of mica fine powder having an average particle diameter of 41 μm as a melt flow inhibitor is mixed with 100 parts by weight of the powder coating material A.

  FIG. 18 is a perspective view of a test piece 101 used for measuring the edge cover ratio, and a cubic steel test piece 101 having a square with a side of 10 mm and a length of 100 mm was used. This test piece 101 simulates the vertical rib 85 shown in FIG. In addition, as the test piece 101, three types of edge radius R (see FIG. 18) were prepared: R = 0.1 mm, R = 0.5 mm, and R = 1.0 mm.

  The powder coatings A to F are individually adhered to the surface of the test piece 101 using the electrostatic fluid immersion apparatus, heated at 280 ° C. for 3 seconds, and then cooled by air cooling, as shown in FIG. As shown, a resin film 102 was formed on the surface of the test piece 101.

  19A and 19B are diagrams for explaining the edge cover ratio. First, as shown in FIG. 19A, the dimensions of the portion a and the portion b of the test piece 101 before the resin film 102 is formed are measured. Thereafter, as shown in FIG. 19B, a resin coating 102 is formed on the entire test piece 101, and the dimensions of the a ′ portion and the b ′ portion of the test piece 101 are measured. A micrometer was used to measure these dimensions. The edge coverage was obtained by the following formula.

Edge cover rate = [(b′−b) / 2] / [(a′−a) / 2] × 100
Therefore, the numerator in this formula is the resin film thickness at the edge portion of the test piece 101, and the denominator is the resin film thickness at the flat portion of the test piece 101.

  FIG. 20 is a characteristic diagram showing the relationship between the edge radius (edge R) and the edge coverage when various powder paints are used. Curves A, B, C, D, E, and F in the figure are characteristic curves of various powder coatings A, B, C, D, E, and F, and are associated with signs.

  As is apparent from this figure, when no melt flow inhibitor is contained as in the powder coating material A, the edge cover ratio is low, and the film thickness at the edge portion is thinner than the flat portion. When the radius R is 0.5 mm or less, the edge coverage tends to be less than 50%.

  On the other hand, those containing a melt flow inhibitor, such as the powder coatings B to F, have a high edge cover rate as a whole, and even edge portions having a radius R of 0.1 mm are particularly edged. The coverage can be ensured to 50% or more.

  FIG. 21 is a characteristic diagram showing the relationship between the number of parts by weight of mica added and the edge cover ratio with respect to 100 parts by weight of (PVB resin powder + antioxidant) of the powder coating using mica as the melt flow inhibitor.

  Curve G in the figure is a mixture of test piece 101 having an edge radius R of 0.1 mm mixed with mica fine powder having an average particle diameter of 21 μm, and curve H has an edge radius R of 1.0 mm. Mica fine powder having an average particle diameter of 21 μm mixed on the test piece 101, curve I is a fine powder of mica having an average particle diameter of 41 μm on the test piece 101 having an edge radius R of 0.1 mm. A curve J is a characteristic curve of a mixture of fine mica powder having an average particle diameter of 41 μm on a test piece 101 having a radius R of an edge portion of 1.0 mm. In addition, the values of the lower and lower X marks on the line of 0 parts by weight of mica added in the figure indicate the radius R of the edge portion using the powder coating material A that does not contain the melt flow inhibitor (mica). Shows the edge coverage when a resin film is formed on a test piece having a radius R of 1.0 mm and a test piece having a radius R of 1.0 mm.

As is apparent from this figure, when mica is used as a melt flow inhibitor, a high edge cover ratio can be obtained by adding 5 to 10 parts by weight of mica to 100 parts by weight of (PVB resin powder + antioxidant). It can be secured.

  As the melt flow inhibitor, for example, fine powders of inorganic compounds such as iron oxide, mica (amica), alumina, ceramic, calcium carbonate, titanium oxide, and bon black are used.

  FIG. 22 is an enlarged cross-sectional view of the main part of the highly durable anticorrosive steel material according to the fifth embodiment of the present invention. A plurality of (two in this embodiment) vertical ribs 85 continuously extending along the longitudinal direction of the steel material 81 on the outer peripheral surface of the linear or rod-shaped steel material 81 embedded in the concrete, and the steel material 81 Transverse ribs (not shown) extending in the circumferential direction are provided at predetermined intervals along the longitudinal direction.

  The plurality of vertical ribs 85 extending in the longitudinal direction of the steel material 81 are provided to increase the bending strength of the steel material 81, and the horizontal ribs are provided to increase the pulling strength from the concrete. When ribs are provided in this way, edges 87 are formed on the ridge lines of the ribs.

  Thus, on the surface of the steel material 81 having ribs, a resin film 82 in which a melt flow inhibitor 88 made of fine powder of an inorganic compound such as iron oxide or mica (mica) is dispersed and held is formed.

  In the present embodiment, the inorganic coarse particles 83 are not held on the resin coating 82, but the inorganic coarse particles 83 can be sprayed and held as necessary.

  As an example of a steel material having an edge portion, an example in which a rib is formed on the outer peripheral surface of a linear or rod-shaped steel material has been shown. However, the present invention can also be applied to a steel material having other edge portions such as a prismatic steel material. It is.

  In the above embodiment, the steel material for reinforced concrete, that is, the reinforcing bar, has been described. However, the present invention is not limited to this. For example, a manhole cover, a grating, a step such as a step board or a ladder, a handrail, a port structure, a fence It can be applied in various technical fields such as rockfall protection fences, windbreak fences, rockfall protection nets, falling ball protection nets, cable protection pipes, steel plates for pressure receiving plates, sabo dams, drainage wells, and concrete utility poles.

  1: Steel material carrying device, 2: Electrostatic fluid immersion device, 3: High frequency heating device, 4: Inorganic coarse particle spraying device, 5: Steel material carrying device, 6: Steel material, 7: Fluid tank, 8: High frequency heating coil , 9: inorganic coarse particle spray gun, 10: cooling chamber, 11: powder recovery cover, 12: lower space, 13: dry air blow pipe, 14: blower, 15: porous electrode, 16: high voltage Generator: 17: Porous plate, 18: Powder, 19: Fluid space part, 20: Powder coating supply pipe, 21: Blower, 22: Sampling pipe, 23: Powder quantity detector, 24: Powder recovery Tube: 25: Attractor, 26: Dry air, 30: Base, 31: Heated air generating section, 32: Filter section, 33: Air supply pipe, 34: Lifting means, 35: Vertical moving frame, 36: Guide rail 37: Coarse-grain body spraying part, 38: Heated air supply pipe, 39: Coarse-grain body supply part, 0: Coarse grain transport pipe, 41: Heated air recycle pipe, 42: Coarse grain recycle pipe, 43: Coarse grain transport air, 44: Transport air supply pipe, 45: Normal air, 46: Heated air 47: Coarse grain body, 48: Coarse grain supply pipe, 49: Steel material insertion hole, 50: Side plate, 51: Heated air introduction chamber, 52: Heated air introduction hole, 53: Coarse grain spraying chamber, 54: Narrow forming member, 55: narrowing member, 56: recovery chamber, 57: recovery passageway, 58: port opening, 59: mixed flow, 80: highly durable anticorrosion steel, 81: steel, 82: resin coating, 83: inorganic coarse Granules, 84: strands, 85: longitudinal ribs, 86: transverse ribs, 87: edges, 88: melt flow inhibitor, 100: production apparatus for highly durable anticorrosive steel materials, X: transport direction of steel materials.

Claims (16)

Steel,
The main component is a polyvinyl butyral resin having a butyralization degree of 40 to 85 mol% and a hydroxyl group content in the molecule of 11 to 27 wt%, and 5 wt% with respect to the polyvinyl butyral resin. A highly durable anticorrosive steel material comprising a resin film formed by adhering to the surface of the steel material, comprising a mixture to which the following organic antioxidant is added. Steel,
The main component is a polyvinyl butyral resin having a butyralization degree of 40 to 85 mol% and a hydroxyl group content in the molecule of 11 to 27 wt%, and 5 wt% with respect to the polyvinyl butyral resin. It consists of a mixture to which the following organic antioxidants are added, and a resin film formed by adhesion on the surface of the steel material,
A highly durable anticorrosive steel material, characterized by having an inorganic coarse particle fixed with the resin coating and forming innumerable protrusions protruding from the surface of the resin coating.   The highly durable anticorrosive steel material according to claim 1 or 2, wherein the content of hydroxyl groups in the molecule of the polyvinyl butyral resin is regulated to be in a range of 18 to 27% by weight. Steel material. The highly durable anticorrosive steel material according to any one of claims 1 to 3, wherein the organic antioxidant is an organic compound having the following molecular structural formula.

In the formula, R1 to R8: a linear or branched alkyl group having 1 to 4 carbon atoms or hydrogen,
l, m, n: each an integer of 1 to 10,
X: N or O heteroatom.   The highly durable anticorrosive steel material according to any one of claims 2 to 4, wherein the steel material is a rebar for concrete.   The high durability corrosion-resistant steel material according to any one of claims 2 to 4, wherein the steel material is a stranded wire.   5. The highly durable anticorrosive steel material according to claim 2, wherein an edge portion is formed on the surface of the steel material, and a fine powder of a melt flow inhibitor is dispersed and held in the resin film covering the edge portion. A highly durable anti-corrosive steel material characterized by   The highly durable anticorrosive steel material according to claim 7, wherein a radius of an edge portion of the steel material is 0.5 mm or less. A surface adjustment step for adjusting the surface to form a resin film on the surface of the steel material;
A powder coating adhesion process in which a powder coating mainly composed of polyvinyl butyral resin is adhered to the surface of the steel material subjected to surface adjustment by an electrostatic fluidized immersion method;
A resin film forming step for heating and melting the powder coating material on the surface to form a molten resin film on the surface of the steel material by heating and melting the powder coating;
An inorganic coarse particle spraying step of spraying a high-temperature inorganic coarse particle on the molten resin film formed on the surface of the steel material;
By cooling the steel material after spraying the inorganic coarse particles, the resin film in a molten state is solidified, and the sprayed inorganic coarse particles are fixed with a resin film, and the inorganic coarse particles The manufacturing method of the highly durable corrosion-resistant steel material characterized by including the uneven | corrugated formation process which protrudes a part of body from a resin film and forms innumerable unevenness | corrugation.   The method for producing a highly durable anticorrosive steel material according to claim 9, wherein the degree of butyralization of the polyvinyl butyral resin is 40 to 85 mol%, and the hydroxyl group content in the molecule is restricted to a range of 11 to 27 wt%. And 5% by weight or less of an organic antioxidant is added to the polyvinyl butyral resin.   10. The method for producing a highly durable anticorrosive steel material according to claim 9, wherein the content of hydroxyl groups in the molecules of the polyvinyl butyral resin is regulated within a range of 18 to 27% by weight. A method for producing corrosion-resistant steel. The method for producing a highly durable anticorrosive steel material according to claim 10 or 11, wherein the organic antioxidant is an organic compound having the following molecular structural formula.

In the formula, R1 to R8: a linear or branched alkyl group having 1 to 4 carbon atoms or hydrogen,
l, m, n: each an integer of 1 to 10,
X: N or O heteroatom.   The method for producing a highly durable anticorrosive steel material according to any one of claims 9 to 12, wherein the highly durable anticorrosive steel material is a reinforcing bar for concrete. A steel material carrying-in device for carrying in a long steel material to be processed;
An electrostatic fluidized immersion device for adhering a powder coating mainly composed of polyvinyl butyral resin to the surface of the long steel material;
A heating device that heats and melts the powder paint adhering to the surface of the steel material to form a molten resin film on the surface of the steel material; and
An inorganic coarse particle spraying device for spraying a high-temperature inorganic coarse particle on a molten resin film;
A steel material cooling device for cooling the steel material after spraying the inorganic coarse particles and solidifying the resin film, and fixing the sprayed inorganic coarse particles with the resin film;
A steel material unloading device for unloading the cooled steel material is provided.
A highly durable anticorrosive steel material in which the steel material is conveyed in a predetermined direction without rotating until the steel material carried in from the steel material carry-in device is carried out from the steel material carry-out device. Manufacturing equipment. In the manufacturing apparatus of the highly durable anti-corrosion steel material according to claim 14, the electrostatic fluid immersion apparatus includes:
A lower space into which dry air is sent, and
A porous electrode disposed at the top of the lower space,
A flow space portion provided on the porous electrode and loaded with a polyvinyl butyral resin powder coating inside and through which the elongated steel material is inserted,
A high voltage generator for applying different charges to the porous steel and the long steel material inserted through the flow space, and
Powder coating material supply means for feeding polyvinyl butyral resin powder into the flow space;
An apparatus for producing a highly durable anticorrosive steel material, comprising powder paint recovery means for recovering the powder paint that has not adhered to the long steel material in the flow space. In the manufacturing apparatus of the highly durable corrosion-resistant steel material according to claim 14 or 15, the inorganic coarse particle spraying device includes:
A coarse grain spraying chamber formed so as to surround the entire circumference of the long steel material carrying the molten resin coating, and the inner side facing the long steel material of the coarse grain spraying chamber A narrowed narrow part is formed in the
A mixed flow of high-temperature coarse particles and air is supplied to the coarse-particle spraying chamber, and is injected onto the peripheral surface of the steel material carrying the molten resin film through the narrowed portion. An apparatus for producing a highly durable anti-corrosion steel material.

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