JP2006137059A - Resin coated heavy-duty anti-corrosive steel material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin coated heavy-duty anti-corrosive steel material having excellent cathodic peel resistance in a severe corrosive environment such as soil, rivers, the ocean and the like by achieving the rationalization of the composition of a urethane primer layer to drastically enhancing the cut-off capacity of oxygen necessarily indispensable to a cathodic peeling phenomenon, especially a steel pipe pile, a steel sheet pile, a steel pipe sheet pile and a line pipe embedded in soil. <P>SOLUTION: In the resin coated heavy-duty anti-corrosive steel material constituted by successively laminating a urethane primer layer and a polyurethane anti-corrosive layer on the surface of a substrate steel material and the urethane primer layer comprises a cured material of a polyol and polyisocyanate. The polyol contains a reaction product of xylene diisocyanate and at least one kind of compound selected from the group consisting of polyethylene glycol, polypropylene glycol, glycerine, a trimethylol propane/olefin oxide adduct and an ethylenediamine/olefin oxide adduct. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to a resin-coated heavy anti-corrosion steel material excellent in cathodic peel resistance used under extremely severe conditions such as soil, rivers, and oceans, in particular, steel pipes, steel pipe piles, steel sheet piles, steel pipes. The present invention relates to a sheet pipe embedded in a sheet pile and soil.

For steel structural members such as steel pipes, steel pipe piles, steel pipe sheet piles, and steel sheet piles used in soil, rivers, oceans, and the like, polyurethane-coated steel materials with urethane coating have been used to provide long-term corrosion resistance. In polyurethane-coated steel materials, it is an important role of the coating layer to provide excellent corrosion resistance and corrosion resistance, and in order to guarantee such performance over a long period of time, it is possible to laminate multiple layers of coating layers specialized for individual functions. Has been done.

For example, in order from the base steel material side, a very thin chromate treatment layer directly applied to the base steel material,
A combination of a urethane primer layer having a thickness of 10 to 300 μm and a polyurethane anticorrosive resin layer having a thickness of about 1 to 5 mm is mentioned. In this case, the uppermost polyurethane anticorrosive resin layer is used to block corrosion factors and ensure mechanical impact resistance, the urethane primer layer is used to ensure adhesion to steel, and the lowermost chromate treatment layer is used to form urethane resin. Each contributes greatly to ensuring the durability of steel.

However, in recent years, it has become clear that as various polyurethane-coated steel materials are widely spread in the world, they have a corrosion-proof durability life of about 20 years, compared with 50 years, which is a typical expected service life of port facilities. In other words, the uppermost polyurethane anticorrosive resin layer is actually 20 years in spite of having a material life of about 50 years as a material by adding carbon black as a weathering agent to its stable chemical structure. This is because the chromate treatment layer dissolves and deteriorates due to corrosion factors such as water and oxygen that have entered the interface between the steel material and the primer layer to some extent, so that the entire coating layer peels off and the anticorrosion performance by the coating layer cannot be expected at all. In particular, as described below, it is prominent when combined with cathodic protection (cathodic protection).

Since steel sheet piles, steel pipe piles, line pipes, etc. need to be protected over a long period of several decades or more, the cathodic protection method is applied in combination with corrosion protection by polyurethane resin coating. In the case of construction, if the polyurethane resin has wrinkles that reach the base steel material, the steel material is protected by the cathodic protection effect, but the polyurethane resin coating layer is easily peeled off by the cathodic protection. This phenomenon is known as so-called “cathode peeling” in which oxygen that has permeated through the coating layer is reduced by an anticorrosion current to generate an alkali, and the resin coating layer peels off due to this alkali. Here, the “cathodic anticorrosion method” means an anticorrosion method in which the potential of the steel material is lowered to a lower potential than the potential at which corrosion occurs, and the potential in the transformation region is used. Specifically, a method using a sacrificial anode And there is a method by forced energization.

The cathode peeling phenomenon is a phenomenon that is noticeable when the anticorrosion is used together, but is not necessarily a phenomenon peculiar when the anticorrosion is used together. That is, when a polyurethane-coated steel material with a part of the surface of the base steel material that is not subjected to cathodic protection is immersed in seawater, an anode reaction occurs in which iron elutes on the exposed base steel material surface, and it is close to the exposed part. A cathode reaction in which oxygen is involved, that is, oxygen is reduced, occurs on the surface of the base steel material under the polyurethane coating layer. As a result, alkali accumulation occurs on the surface of the base steel material under the polyurethane coating layer, and a similar cathodic peeling phenomenon occurs although the rate of progress is slower than when using the anticorrosion.

As a known technique for improving the cathode peel resistance of a polyurethane-coated heavy anti-corrosion steel material, Patent Document 1
Is disclosed.

The technique described in Patent Document 1 is such that after a urethane primer layer and a urethane anticorrosive layer are sequentially laminated on the steel surface, an aluminum film, polyvinyl chloride film, and polyvinylidene chloride having a moisture permeability of 1 g / m ² · day · mm or less. By sticking a film or a polyester film via an adhesive, the cathode peel resistance of the polyurethane-coated heavy anticorrosive steel material is improved.

However, since the aluminum film corrodes in the marine environment, it cannot be expected to function as a long-term water vapor permeation blocking layer. In addition, a vinyl chloride resin such as a polyvinyl chloride film or a polyvinylidene chloride film is not preferable because it has a large environmental load. On the other hand, polyester films may hydrolyze ester groups when exposed to an environment where water is present for a long period of time. Especially when the above-mentioned anticorrosion is used, hydrolysis is accelerated by the generated alkali. Therefore, the reliability for long-term durability is low.
Japanese Patent Laid-Open No. 08-267661

The present invention achieves excellent resistance in corrosive environments such as soil, rivers and oceans by optimizing the composition of the urethane primer layer and dramatically improving the ability to block oxygen essential for cathodic stripping. An object of the present invention is to provide a resin-coated heavy anticorrosive steel material having a cathode peelability, in particular, a steel pipe pile, a steel sheet pile, a steel pipe sheet pile, and a line pipe embedded in soil.

In order to achieve the above object, the present invention provides a resin-coated heavy anti-corrosion steel material in which a urethane primer layer and a polyurethane anti-corrosion layer are sequentially laminated on the surface of a base steel material, wherein the urethane primer layer is a cured product of a polyol and a polyisocyanate. And the polyol contains xylene diisocyanate and one or more reaction products selected from the following group (A).
(A) group: polyethylene glycol, polypropylene glycol, glycerin, trimethylolpropane-olefin oxide adduct, ethylenediamine-olefin oxide adduct, bisphenol A-olefin oxide adduct, bisphenol F-olefin oxide adduct, aniline-olefin oxide addition , Resorcinol, resorcinol-olefin oxide adduct, triethylenetetramine-olefin oxide adduct, alkanolamine The polyisocyanate is a reaction product of xylene diisocyanate and one or more selected from group (A) above It is preferable to contain.

The cured product is preferably a cured product in which the mixing ratio of polyol and polyisocyanate is 0.8 to 2.0 in terms of the ratio of isocyanate groups in the polyisocyanate to hydroxyl groups in the polyol.

More preferably, the urethane primer layer further contains one or more silane coupling agents selected from the following group (B).
(B) Group: 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2 (aminoethyl) 3-aminopropylmethyldimethoxysilane, N-2 (aminoethyl) 3-aminopropyltrimethoxysilane N-2 (aminoethyl) 3-aminopropyltriethoxysilane, 3-isocyanatopropyltriethoxysilane, the urethane primer layer further comprises titanium oxide, zinc phosphate, calcined gypsum, aluminum dihydrogen triphosphate, silica, zinc oxide and It is more preferable to contain at least one selected from the group consisting of magnesium oxide.

The base steel material is a chromate-coated steel material having a chromate layer on the surface, and the chromium conversion adhesion amount of the chromate layer is preferably 100 to 500 mg / m ² .

  Moreover, it is preferable that the film thickness of a urethane primer layer is 10-300 micrometers, and the film thickness of a polyurethane anti-corrosion layer is 1-5 mm.

According to the present invention, by optimizing the composition of the urethane primer layer and dramatically improving the ability to block oxygen essential for the cathode peeling phenomenon, it is excellent in corrosive environments such as soil, rivers and oceans. Resin-coated heavy anti-corrosion steel material with anti-cathode resistance, especially steel pipe piles,
It has become possible to provide steel sheet piles, steel pipe sheet piles and line pipes embedded in the soil.

  Hereinafter, the present invention will be described in detail.

The present invention relates to a resin-coated heavy anti-corrosion steel material (hereinafter abbreviated as “coated steel material”) having excellent cathode peel resistance.

  FIG. 1 shows an example of a cross section of a resin-coated heavy anticorrosive steel material according to the present invention.

  As shown in FIG. 1, the resin-coated heavy anticorrosive steel material 10 of the present invention has a urethane primer layer 13 and a polyurethane anticorrosive layer 14 via a chromate layer 12 formed on the surface of a base steel material 11 as necessary. Is a coated steel material having a long-term cathode peel resistance by specifying the composition of the urethane primer layer 13 in particular.

Examples of a method for producing such a resin-coated heavy anticorrosive steel material 10 include the following methods. Generally, in order to improve the bond strength between the base steel material and the primer layer, it is important to keep the base steel material surface clean.

In the present invention, the surface property of the base steel material 11 is not particularly limited as long as the oxide layer and oil on the surface can be removed before the resin coating, but for example, JIS B 0601 (1994)
10-point average roughness Rz is 20 to 100 μm (however, reference length: 8 mm, evaluation length: 40
mm. It is optimal to perform steel blasting or steel grid processing. When the ten-point average roughness Rz of the surface of the base steel material 11 is less than 20 μm, the anchoring effect due to the primer being embedded in the irregularities on the surface of the base steel plate is reduced, so the adhesion strength of the primer tends to decrease. In the case of exceeding 100 μm, it becomes difficult to sufficiently cover the surface irregularities of the steel material by the primer, and thus the long-term anticorrosion performance as the coated steel material tends to be lowered. The ten-point average roughness Rz is more preferably 30 to 60 μm.

The urethane primer layer 13 is a cured product of a polyol as a main agent and a polyisocyanate as a curing agent, and the polyol is one or more selected from xylene diisocyanate and the following group (A). It is necessary to contain the reaction product. In the present invention, by limiting the urethane primer layer in this way, the oxygen permeability at room temperature becomes 0.5 (ml · mm) / (m ² · day · atm) or less, and the cathode peel resistance is improved.
(A) group: polyethylene glycol, polypropylene glycol, glycerin, trimethylolpropane-olefin oxide adduct, ethylenediamine-olefin oxide adduct, bisphenol A-olefin oxide adduct, bisphenol F-olefin oxide adduct, aniline-olefin oxide addition Body, resorcinol, resorcinol-olefin oxide adduct, triethylenetetramine-olefin oxide adduct, alkanolamine In addition, polyethylene glycol and polypropylene glycol shall contain diethylene glycol and dipropylene glycol, respectively.

  Furthermore, it is preferable that the polyisocyanate contains a reaction product of xylene diisocyanate and one or more selected from the group (A).

  It is preferable to use a polyisocyanate having a xylene diisocyanate skeleton as a curing agent because intermolecular hydrogen bonds derived from amide groups in the cured product and benzene nuclei block oxygen permeation.

  In the present invention, in the case of a cured product obtained by directly reacting xylene diisocyanate alone with a polyol, since xylene diisocyanate is excessively active, it reacts with moisture in the air and foams to form a continuous primer layer. It is not preferable because it is not done.

  Therefore, it is preferable to use a cured product of a polyisocyanate in which a part of xylene diisocyanate is modified with one or more of the polyols shown in group (A) to reduce the activity, and a similar polyol. Since this cured product is excellent in oxygen barrier properties, a primer layer excellent in resistance to cathode peeling can be obtained. This is because the use of polyols selected from the group (A) minimizes the decrease in oxygen barrier properties due to modification, and the curing shrinkage stress is small.

  By setting at least one, preferably both, of the polyol as the main component and the polyisocyanate as the curing agent of the urethane primer layer to the above composition, the oxygen primer blocking ability of the urethane primer layer as the cured product is increased, Cathode releasability is improved.

The cured product constituting the urethane primer layer 13 is a cured product in which the mixing ratio of polyol and polyisocyanate is 0.8 to 2.0 in terms of the ratio of isocyanate groups in the polyisocyanate to hydroxyl groups in the polyol. preferable. When the ratio is less than 0.8, the function of blocking oxygen permeation tends to be insufficient due to insufficient curing, and when the ratio is more than 2.0, excess isocyanate is moisture in the atmosphere. This is because the function of foaming and blocking oxygen permeation decreases.

In order to further suppress the cathode peeling, the urethane primer layer 13 preferably contains one or more silane coupling agents selected from the following group (B).
(B) Group: 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2 (aminoethyl) 3-aminopropylmethyldimethoxysilane, N-2 (aminoethyl) 3-aminopropyltrimethoxysilane N-2 (aminoethyl) 3-aminopropyltriethoxysilane, 3-isocyanatopropyltriethoxysilane All of the silane coupling agents described in the group (B) are amine groups or hydroxyl groups that react with isocyanate groups. Since the reactive isocyanate group exists in the molecule, these functional groups react with the resin constituting the urethane primer layer, and the silanol group reacts with the surface of the steel material, so that good cathode peel resistance can be obtained. It is preferable that the total addition amount of the silane coupling agent selected from the said (B) group is 1-30 mass parts with respect to 100 mass parts of polyol which is a main ingredient. When the addition amount is less than 1 part by mass, no effect due to the addition of the silane coupling agent is recognized, and when it exceeds 30 parts by mass, an unreacted polyol or polyisocyanate remains excessively. It is not preferable because curing of the primer layer is inhibited.

  Further, when it is necessary to further suppress the cathode peeling, the urethane primer layer 13 is selected from the group consisting of titanium oxide, zinc phosphate, calcined gypsum, aluminum dihydrogen phosphate, silica, zinc oxide and magnesium oxide. It is preferable to contain at least one kind. In addition, it is more preferable to contain these rust preventive pigments in an amount of 10 to 200 parts by mass with respect to 100 parts by mass of the main polyol. If the content is less than 10 parts by mass, the rust preventive effect due to the content will not be recognized. If the content exceeds 200 parts by mass, not only the adhesiveness is lowered but also cured. This is because the urethane primer layer becomes porous and the function of blocking the permeation of oxygen may be reduced.

The film thickness of the urethane primer layer 13 is preferably 10 to 300 μm, and more preferably 40 to 100 μm. If the thickness is less than 10 μm, the function of blocking oxygen permeation may not be sufficiently exhibited. If the thickness exceeds 300 μm, the primer tends to foam when it is cured. In the present invention, the method of forming the urethane primer layer 13 is not particularly limited, but is preferably formed by spray coating or ironing.

  The polyurethane anticorrosion layer 14 is a layer that is laminated immediately above the urethane primer layer 13 and that functions as an anticorrosion layer of the resin-coated heavy anticorrosion steel material 10.

The polyurethane used for the polyurethane anticorrosive layer 14 is not particularly limited. For example, one or more alkyl diols, aniline-ethylene oxide adducts, bisphenol A-ethylene oxide adducts, or bisphenol F-ethylene oxide adducts are suitable for castor oil. Examples thereof include those obtained by curing an amount of mixed polyol with polyphenyl polymethyl polyisocyanate.

  The film thickness of the polyurethane anticorrosive layer 14 is preferably 1 to 5 mm. If the thickness is less than 1 mm, not only the anticorrosion performance decreases, but also the impact resistance of the polyurethane anticorrosion layer tends to decrease. If the thickness exceeds 5 mm, the anticorrosion performance cannot be improved in accordance with the increase in cost. .

In order to prevent UV degradation of the polyurethane anticorrosive layer, it is preferable to blend an ultraviolet absorber, carbon black, a hindered amine light stabilizer HALS (Hindered Amine Light Stabilizer), or the like. In the present invention, the method for forming the polyurethane anticorrosive layer 14 is not particularly limited,
It is preferable to form by spray coating.

Furthermore, in the present invention, before forming the urethane primer layer 13 on the surface of the base steel material, chromate treatment is performed on the surface of the steel material in advance, and instead of the base steel material, a chromate-coated steel material having the chromate layer 12 on the surface is used. You can also. In this case, it is preferable that the chromium conversion adhesion amount of the chromate layer is 100 to 500 mg / m ² . If the chromium equivalent adhesion amount is less than 100 mg / m ² , the adhesion with the urethane primer layer may not be maintained for a long time in a corrosive environment. On the other hand, when the chromium equivalent adhesion amount exceeds 500 mg / m ² , cracking of the chromate layer tends to occur when the chromate layer is baked, and the adhesion of the resin coating layer is remarkably lowered, which is not preferable.

Furthermore, the ratio of trivalent chromium to the total chromium in the chromate layer is preferably 10 to 40%. When the ratio of trivalent chromium to the total chromium is less than 10%, the alkali resistance of the chromate layer is lowered, so that there is a possibility that sufficient cathode peeling resistance as a coated steel material cannot be obtained. On the other hand, when the ratio of trivalent chromium to the total chromium exceeds 40%, the stability of the chromate treatment solution tends to be lowered, and this produces a mass production of coated steel material having uniform cathode separation resistance. It is disadvantageous in some cases.

In the present invention, the steel material arrival temperature during baking of the chromate layer is not particularly specified,
It is preferable to set it as ° C or more. When the baking temperature is less than 80 ° C., the high molecular weight of the chromate is hindered, so that the alkali resistance of the chromate layer is remarkably lowered.

(Polyol synthesis)
A compound selected from the group (A) shown in Table 1 is heated to 90 ° C. in nitrogen in a predetermined reaction vessel, and metaxylene diisocyanate or polyphenyl polymethyl diisocyanate is slowly added dropwise while stirring each by a predetermined amount. Polyols 1 to 15 as the main agents shown in Table 1 were obtained.
(Synthesis of polyisocyanate)
In a predetermined reaction vessel, a compound selected from group (A) shown in Table 2 is heated to 90 ° C. in nitrogen,
Metaisylene diisocyanate or polyphenyl polymethyl diisocyanate was slowly added dropwise while stirring each by a predetermined amount to obtain polyisocyanates No. 1 to 15 as curing agents shown in Table 2.

(Production of coated steel)
Example 1
The surface of the 3W type steel sheet pile (mountain) was subjected to steel blasting to remove the black skin, and the surface was finished to 40-60 μm with a 10-point average roughness Rz. Chromate treatment solution (trade name: Cosmer 100, manufactured by Kansai Paint Co., Ltd.) is diluted to 1/10 with pure water, and the amount of Cr equivalent deposit after baking is 250 mg / m ^2. The ratio of trivalent chromium to total chromium Was spray-applied on the surface of the steel sheet pile so as to be 35%. The steel sheet pile coated with chromate was baked in a heating furnace so that the steel material temperature reached 80 to 100 ° C., and then the urethane primer was applied by spraying so that the dry film thickness was 60 to 100 μm. As a polyol (main agent) of the urethane primer, polyol 1 in Table 1 was used, and 100 parts by mass of zinc phosphate (LF Bowsei ZP-SB: manufactured by Kikuchi Color Co., Ltd.) was blended with 100 parts by mass of polyol 1. As the polyisocyanate (curing agent) of the urethane primer, polyisocyanate 1 which is a reaction product of metaxylene diisocyanate and polyethylene glycol shown in Table 2 was used. The main agent and the curing agent were mixed and applied so that the ratio of the isocyanate group in the curing agent to the hydroxyl group in the main agent was 1.3. The applied primer was dried at room temperature for 2 hours, and then a polyurethane resin (permguard 137: Daiichi Kogyo Seiyaku Co., Ltd.) obtained by curing a polyol prepared by mixing castor oil with an aniline-ethylene oxide adduct with polyphenylpolymethylpolyisocyanate. (Co., Ltd.) was applied with a tip impingement mixed spray so that the film thickness was 3.0 to 3.5 mm, and left for a whole day and night.
Example 2
A resin-coated heavy anticorrosive steel sheet pile was produced in the same manner as in Example 1. However, polyisocyanate 2 in Table 2 was used as a curing agent for the urethane primer.
Example 3
A resin-coated heavy anticorrosive steel sheet pile was produced in the same manner as in Example 1. However, polyisocyanate 3 in Table 2 was used as a curing agent for the urethane primer.
Example 4
A resin-coated heavy anticorrosive steel sheet pile was produced in the same manner as in Example 1. However, polyisocyanate 4 in Table 2 was used as a curing agent for the urethane primer.
Example 5
A resin-coated heavy anticorrosive steel sheet pile was produced in the same manner as in Example 1. However, polyisocyanate 5 in Table 2 was used as a curing agent for the urethane primer.
Example 6
A resin-coated heavy anticorrosive steel sheet pile was produced in the same manner as in Example 1. However, polyisocyanate 6 in Table 2 was used as a curing agent for the urethane primer.
Example 7
A resin-coated heavy anticorrosive steel sheet pile was produced in the same manner as in Example 1. However, polyisocyanate 7 in Table 2 was used as a curing agent for the urethane primer.
Example 8
A resin-coated heavy anticorrosive steel sheet pile was produced in the same manner as in Example 1. However, polyisocyanate 8 in Table 2 was used as a curing agent for the urethane primer.
Example 9
A resin-coated heavy anticorrosive steel sheet pile was produced in the same manner as in Example 1. However, polyisocyanate 9 in Table 2 was used as a curing agent for the urethane primer.
Example 10
A resin-coated heavy anticorrosive steel sheet pile was produced in the same manner as in Example 1. However, polyisocyanate 10 in Table 2 was used as a curing agent for the urethane primer.
Example 11
A resin-coated heavy anticorrosive steel sheet pile was produced in the same manner as in Example 1. However, polyisocyanate 11 in Table 2 was used as a curing agent for the urethane primer.
Example 12
A resin-coated heavy anticorrosive steel sheet pile was produced in the same manner as in Example 1. However, polyisocyanate 12 in Table 2 was used as a curing agent for the urethane primer.
Example 13
A resin-coated heavy anticorrosive steel sheet pile was produced in the same manner as in Example 1. However, polyisocyanate 13 in Table 2 was used as a curing agent for the urethane primer.
Example 14
A resin-coated heavy anticorrosive steel sheet pile was produced in the same manner as in Example 1. However, polyisocyanate 14 in Table 2 was used as a curing agent for the urethane primer.
Example 15
A resin-coated heavy anticorrosive steel sheet pile was produced in the same manner as in Example 1. However, polyol 2 in Table 1 was used as the main component of the urethane primer.
Example 16
A resin-coated heavy anticorrosive steel sheet pile was produced in the same manner as in Example 1. However, polyol 3 in Table 1 was used as the main component of the urethane primer.
Example 17
A resin-coated heavy anticorrosive steel sheet pile was produced in the same manner as in Example 1. However, polyol 4 in Table 1 was used as the main component of the urethane primer.
Example 18
A resin-coated heavy anticorrosive steel sheet pile was produced in the same manner as in Example 1. However, polyol 5 in Table 1 was used as the main component of the urethane primer.
Example 19
A resin-coated heavy anticorrosive steel sheet pile was produced in the same manner as in Example 1. However, polyol 6 in Table 1 was used as the main component of the urethane primer.
Example 20
A resin-coated heavy anticorrosive steel sheet pile was produced in the same manner as in Example 1. However, polyol 7 in Table 1 was used as the main component of the urethane primer.
Example 21
A resin-coated heavy anticorrosive steel sheet pile was produced in the same manner as in Example 1. However, polyol 8 in Table 1 was used as the main component of the urethane primer.
Example 22
A resin-coated heavy anticorrosive steel sheet pile was produced in the same manner as in Example 1. However, polyol 9 in Table 1 was used as the main component of the urethane primer.
Example 23
A resin-coated heavy anticorrosive steel sheet pile was produced in the same manner as in Example 1. However, polyol 10 shown in Table 1 was used as the main component of the urethane primer.
Example 24
A resin-coated heavy anticorrosive steel sheet pile was produced in the same manner as in Example 1. However, polyol 11 shown in Table 1 was used as the main component of the urethane primer.
Example 25
A resin-coated heavy anticorrosive steel sheet pile was produced in the same manner as in Example 1. However, polyol 12 in Table 1 was used as the main component of the urethane primer.
Example 26
A resin-coated heavy anticorrosive steel sheet pile was produced in the same manner as in Example 1. However, the polyol 13 in Table 1 was used as the main component of the urethane primer.
Example 27
A resin-coated heavy anticorrosive steel sheet pile was produced in the same manner as in Example 1. However, polyol 14 in Table 1 was used as the main component of the urethane primer.
Example 28
A resin-coated heavy anticorrosive steel sheet pile was produced in the same manner as in Example 1. However, the main component and the curing agent of the urethane primer were blended so that the ratio of the isocyanate group in the curing agent to the hydroxyl group in the main component was 0.8.
Example 29
A resin-coated heavy anticorrosive steel sheet pile was produced in the same manner as in Example 1. However, the main component and the curing agent of the urethane primer were blended so that the ratio of the isocyanate group in the curing agent to the hydroxyl group in the main component was 2.0.
Example 30
A resin-coated heavy anticorrosive steel sheet pile was produced in the same manner as in Example 1. However, as a rust preventive pigment, a blend of aluminum dihydrogen phosphate, silica and zinc oxide (trade name: K-WHITE # 85, manufactured by Teika Co., Ltd.) is 100 parts by weight with respect to 100 parts by weight of polyol as a main ingredient. What was partly blended was used.
Example 31
A resin-coated heavy anticorrosive steel sheet pile was produced in the same manner as in Example 1. However, as the rust preventive pigment, a mixture of 100 parts by mass of tripolyaluminum dihydrogen phosphate (trade name: k-fresh IOP, manufactured by Teika Co., Ltd.) with respect to 100 parts by mass of the polyol as the main agent was used.
Example 32
A resin-coated heavy anticorrosive steel sheet pile was produced in the same manner as in Example 1. However, as the rust preventive pigment, a mixture of 100 parts by mass of titanium oxide (D-918: manufactured by Sakai Chemical Co., Ltd.) with respect to 100 parts by mass of the polyol as the main agent was used.
Example 33
A resin-coated heavy anticorrosive steel sheet pile was produced in the same manner as in Example 1. However, as the rust preventive pigment, an anhydrous gypsum blended with 100 parts by mass with respect to 100 parts by mass of the main polyol was used.
Example 34
A resin-coated heavy anticorrosive steel sheet pile was produced in the same manner as in Example 1. However, as the rust preventive pigment, a mixture of 3 parts by mass of tripolyaluminum dihydrogen phosphate (trade name: k-fresh IOP, manufactured by Teika Co., Ltd.) with respect to 100 parts by mass of the main polyol is used.
Example 35
A resin-coated heavy anticorrosive steel sheet pile was produced in the same manner as in Example 1. However, as the rust preventive pigment, a mixture of 200 parts by mass of aluminum dihydrogen triphosphate (trade name: k-fresh IOP, manufactured by Teika Co., Ltd.) with respect to 100 parts by mass of the polyol as the main agent was used.
Example 36
A resin-coated heavy anticorrosive steel sheet pile was produced in the same manner as in Example 1. However, the Cr conversion adhesion amount of the chromate film was 100 mgCr / m2.
Example 37
A resin-coated heavy anticorrosive steel sheet pile was produced in the same manner as in Example 1. However, the Cr conversion adhesion amount of the chromate film was 500 mgCr / m2.
Example 38
A resin-coated heavy anticorrosion steel sheet pile was produced in the same manner as in Example 1. However, 5-aminopropyltrimethoxysilane (KBM-903: manufactured by Shin-Etsu Chemical Co., Ltd.) as a silane coupling agent was added to the primer layer in an amount of 5 parts by weight based on 100 parts by weight of the main polyol. .
Example 39
A resin-coated heavy anticorrosion steel sheet pile was produced in the same manner as in Example 1. However, 5-aminopropyltriethoxysilane (KBE-903: manufactured by Shin-Etsu Chemical Co., Ltd.) as a silane coupling agent was added to the primer layer in an amount of 5 parts by weight based on 100 parts by weight of the main polyol. .
Example 40
A resin-coated heavy anticorrosion steel sheet pile was produced in the same manner as in Example 1. However, N-2 (aminoethyl) 3-aminopropylmethyldimethoxysilane (KBM-602: manufactured by Shin-Etsu Chemical Co., Ltd.) is used as a silane coupling agent in the primer layer with respect to 100 parts by weight of the main polyol. 5 parts by weight were added.
Example 41
A resin-coated heavy anticorrosion steel sheet pile was produced in the same manner as in Example 1. However, N-2 (aminoethyl) 3-aminopropyltrimethoxysilane (KBM-603: manufactured by Shin-Etsu Chemical Co., Ltd.) is used as a silane coupling agent in the primer layer with respect to 100 parts by weight of the main polyol. 1 part by weight was added.
Example 42
A resin-coated heavy anticorrosion steel sheet pile was produced in the same manner as in Example 1. However, N-2 (aminoethyl) 3-aminopropyltriethoxysilane (KBE-603: manufactured by Shin-Etsu Chemical Co., Ltd.) is used as a silane coupling agent in the primer layer with respect to 100 parts by weight of the main polyol. 30 parts by weight were added.
Example 43
A resin-coated heavy anticorrosion steel sheet pile was produced in the same manner as in Example 1. However, 5 parts by weight of 3-isocyanatopropyltriethoxysilane (KBE-9007: manufactured by Shin-Etsu Chemical Co., Ltd.) as a silane coupling agent was added to the primer layer with respect to 100 parts by weight of the main polyol.
Example 44
A resin-coated heavy anticorrosive steel sheet pile was produced in the same manner as in Example 1. However, polyisocyanate 15 in Table 2 was used as a curing agent for the urethane primer.
Comparative Example In the same manner as in Example 1, a resin-coated heavy anticorrosive steel sheet pile was produced. However, the polyol 15 in Table 1 was used as the main component of the urethane primer, and the polyisocyanate 1 in Table 2 was used as the curing agent. The main agent and the curing agent were mixed so that the ratio of the isocyanate group in the curing agent to the hydroxyl group in the main agent was 1.3.
(Measurement of oxygen permeability of urethane primer layer)
On the polyethylene terephthalate film (trade name: Lumirror sheet, manufactured by Toray Industries, Inc.) with a film thickness of 100 μm, the primer used in each of Examples 1 to 43 and Comparative Examples 1 and 2 was applied to about 10 μm, and 2 at room temperature. Air dried day and night. The oxygen permeability of this resin film was measured indoors at 23 ° C. using an oxygen permeability meter (trade name: GPM-200, manufactured by Lyssy). Using the following formula, the oxygen permeability P of the primer layer alone was determined by subtracting the oxygen permeability value of the polyethylene terephthalate alone measured in advance.

P = X × P0 / (P0−X)
Where X is the measured value, P0 is the oxygen permeability of the polyethylene terephthalate film alone,
P represents the oxygen permeability of the primer layer alone. The calculated P is a film thickness of 1 mm and an area of 1 m.
^{2 In} Table 3, converted to daily values.
(Evaluation of resistance to cathode peeling)
Each of the resin-coated heavy anti-corrosion steel materials produced in the manner shown in Examples 1 to 43 and Comparative Examples 1 and 2 was cut out by saw cutting to obtain 7 test pieces each having a size of 100 mm × 100 mm.

For two test pieces each having a size of 100 mm × 100 mm, a cylindrical steel tension jig having a cross-sectional area of 1 cm ² was bonded with an epoxy adhesive, and then adhered to the polyurethane anticorrosive layer around the steel jig. The incision reaching the steel surface was made with a ruter. Initial adhesion strength of polyurethane coating layer (N
/ Cm ² ) was measured with a tensile tester (tensile speed: 5 mm / min) to obtain an average.

With respect to each of five test pieces of size: 100 mm × 100 mm, the four end surfaces of the cut sample were polished, and then a resin-coated lead wire was attached to one portion of the cut surface using an aluminum rivet. After the aluminum rivet portion was sealed with an epoxy-based adhesive, the back surface (the surface steel material surface not coated with the polyurethane anticorrosive layer) and the three end surfaces were sealed with a silicon sealant for all the samples. Once the sealant is completely dry, blown air at 60 ° C 3
It was immersed in a mass% NaCl aqueous solution for 180 days. At that time, one end of the lead wire was connected to a potentiostat, a platinum electrode was used as the counter electrode, and a voltage was applied to the exposed steel surface of the unsealed end surface so that the potential was −1.0 V vs SCE. . The test piece was taken out after being immersed for 180 days, and the resin coating layer was forcibly peeled from the exposed end face of the resin-coated steel material, and the distance at which the steel surface was exposed at the peeling interface was measured with calipers. Here, the average value of five test pieces at the distance at which the steel surface was exposed was evaluated as the resistance to cathode peeling. Note that the area where the steel surface is exposed in this stripping operation is a site where the adhesion of the resin coating layer is lost, so that substantial anticorrosion performance can no longer be expected. It can be determined that it has cathode peelability.

  The evaluation results are shown in Tables 2 and 3.

In any of the test pieces of Examples 1 to 43 and Comparative Example 1, the initial adhesion strength was as good as 1000 N / cm ² or more, and the peeling interface after the test was cohesive failure of the polyurethane anticorrosive layer.

However, in the comparative example in which the reaction product of xylene diisocyanate and one or more selected from the group (A) is not used as the polyol (main agent) of the urethane primer, the oxygen permeability of the primer layer is 0.5 (ml · mm ) / (M ² · day · atm), the steel surface exposure distance after immersion for 180 days at 60 ° C becomes longer, and the cathode peel resistance is inferior.

On the other hand, about Examples 1-43 using the reaction product of xylene diisocyanate and 1 or more types selected from the said (A) group as a polyol (main ingredient) of a urethane primer or a polyisocyanate (curing agent) of a urethane primer. Each primer layer exhibited a small oxygen permeability of 0.5 (ml · mm) / (m ² · day · atm) or less, and as a result, a resin-coated heavy anti-corrosion steel material excellent in cathode peel resistance was obtained.

According to the present invention, by optimizing the composition of the urethane primer layer and dramatically improving the ability to block oxygen essential for the cathode peeling phenomenon, it is excellent in corrosive environments such as soil, rivers and oceans. Resin-coated heavy anti-corrosion steel material with anti-cathode resistance, especially steel pipe piles,
It has become possible to provide steel sheet piles, steel pipe sheet piles and line pipes embedded in the soil.

1 is a cross-sectional view of a resin-coated heavy anticorrosive steel material according to the present invention.

Explanation of symbols

10 Resin coated heavy duty steel
11 Base steel
12 Chromate layer
13 Urethane primer layer
14 Polyurethane anticorrosion layer

Claims (6)

In the resin-coated heavy anti-corrosion steel material in which a urethane primer layer and a polyurethane anti-corrosion layer are sequentially laminated on the surface of the base steel material,
The urethane primer layer is a cured product of polyol and polyisocyanate, and the polyol contains xylene diisocyanate and one or more reaction products selected from the following group (A). Characteristic resin-coated heavy anti-corrosion steel.
(A) group: Polyethylene glycol, polypropylene glycol, glycerin, trimethylolpropane-olefin oxide adduct, ethylenediamine-olefin oxide adduct, bisphenol A-olefin oxide adduct, bisphenol F-olefin oxide adduct, aniline-olefin oxide addition , Resorcinol, resorcinol-olefin oxide adduct, triethylenetetramine-olefin oxide adduct, alkanolamine   The resin-coated heavy anti-corrosion steel material according to claim 1, wherein the polyisocyanate contains a reaction product of xylene diisocyanate and one or more selected from the group (A).   The cured product is a cured product in which the mixing ratio of polyol and polyisocyanate is 0.8 to 2.0 in terms of the ratio of isocyanate groups in the polyisocyanate to hydroxyl groups in the polyol. The resin-coated heavy-duty anticorrosive steel material described in 1. The resin coating according to any one of claims 1 to 3, wherein the urethane primer layer further contains one or more silane coupling agents selected from the following group (B). Heavy anti-corrosion steel.
(B) Group: 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2 (aminoethyl) 3-aminopropylmethyldimethoxysilane, N-2 (aminoethyl) 3-aminopropyltrimethoxysilane N-2 (aminoethyl) 3-aminopropyltriethoxysilane, 3-isocyanatopropyltriethoxysilane The urethane primer layer further contains at least one selected from the group consisting of titanium oxide, zinc phosphate, calcined gypsum, aluminum dihydrogen triphosphate, silica, zinc oxide, and magnesium oxide. 5. The resin-coated heavy anti-corrosion steel material according to any one of 4 above. The said base steel material is a chromate coating steel material which has a chromate layer on the surface, and the chromium conversion adhesion amount of the said chromate layer is 100-500 mg / m < ² >, Any one of Claims 1-5 characterized by the above-mentioned. The resin-coated heavy anti-corrosion steel material described.

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