JP2014227434A - HIGHLY CORROSION RESISTANT PAINT COMPOSITION UTILIZING Sn ION - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly corrosion resistant pain composition for suppressing rust on a surface of a steel structure or piping made of common steel or atmospheric corrosion-resistant steel, which progresses in a depth direction.SOLUTION: Provided is a highly corrosion resistant paint composition comprising: (A) an epoxy resin having two or more epoxy groups in one molecule; (B) a modified resin; (C) an amine-based curing agent; (D) stannous sulfate; (E) a rust-preventive pigment; (F) a loading pigment; and (G) a color pigment, and in which the content of the modified resin (B) is 50 to 90 pts.wt. to 100 pts.wt. of the solid content of the epoxy resin (A), the content of the stannous sulfate (D) is 2.0 t 8.0 pts.wt. to 100 pts.wt. of the paint composition, the content of the rust-preventive pigment (E) is 10 to 30 pts.wt. to 100 pts.wt. of the total solid content of the epoxy resin (A), the modified resin (B) and the amine curing agent (C), the loading pigment (F) includes at least one pigment selected from the group consisting of sericite pigment, silicon dioxide pigment and hydrous magnesium silicate, the pigment volume concentration in the paint film to be formed lies in the range of 30 to 50 wt.%, and the value of (the active hydrogen equivalent of the amine curing agent (C))/(the epoxy equivalent of the epoxy resin (A)) lies in the range of 0.4 to 0.8.

Description

  The present invention relates to a highly corrosion-resistant coating material used for maintenance and repair of steel structures and steel pipes made of ordinary steel materials or weather-resistant steel materials in harsh environments such as steelworks, chemical plants, and marine structures.

  Conventionally, a thick film coating system with a modified epoxy resin coating as an undercoat for corrosion prevention of steel structures and steel pipes made of ordinary steel in harsh environments such as steelworks, chemical plants, and marine structures. Have been used, and various top coats are applied as necessary.

  On the other hand, many weather-resistant steel materials are used for steel bridges and the like, which do not require painting due to the protection function of stable rust. However, in the weather resistant steel material, when the formation of stable rust is hindered by a snow melting agent or the like, a surface treatment agent is applied as shown in Patent Document 1. In this case, since the surface treatment agent only needs to be present on the weathering steel material until stable rust is formed, the film thickness is as thin as about 10 to 100 μm, and the resin used as the binder is butyral. Mainly non-crosslinked types such as resin, phenol resin, vinyl ester resin.

  Steel structures and steel pipes made of ordinary steel in steelworks, chemical plants, offshore structures, etc., even if a thick film coating system is adopted, the coating film in service is deteriorated, that is, the coating film is made of steel. It is inevitable that the damage reaches the maximum, and how to suppress the generation of rust from the damage is a problem for the facility manager. The rust spreading in the horizontal direction of the steel material is only deteriorated in the appearance in the initial stage, but the rust progressing in the depth direction is a problem related to the strength reduction and the life of the structure, and countermeasures are required.

  In addition, in repair coating, due to structural restrictions and restrictions on the surrounding environment such as the presence of dangerous materials, highly effective kelen processing operations such as blast processing that generates a large amount of dust and disc sander processing that generates sparks are performed. In most cases, this is not possible, and as a result, rust, chloride, etc. remain on the surface to be coated, and the repair coating film may swell or peel off at an early stage. Furthermore, local deep corrosion under the coating film is also caused by the action of residual rust and chloride.

Patent No. 4687231

  The present invention has been made in view of the problems of the prior art, and its purpose is to suppress rust that progresses in the depth direction of the surface of steel structures or steel pipes made of ordinary steel materials or weather-resistant steel materials. An object of the present invention is to provide a highly corrosion-resistant coating composition and a coating method using the same.

  In order to achieve the above object, the present inventors have made extensive studies on means for suppressing rust that progresses in the depth direction of steel materials. As a result, a specific amount of divalent tin ions (sulfuric acid sulfate) is contained in the coating composition. It has been found that the presence of tin) is important, and that the ratio of the modified resin to the epoxy resin in the coating composition and the pigment volume concentration in the coating film formed are important.

Specifically, the rust suppression mechanism by divalent tin ions in the present invention is as follows.
In an environment with a large amount of flying salt, repeated drying and wetting of the FeCl ₃ solution is an essential condition, and Fe ³⁺ acts as an oxidizing agent in a state where the pH is lowered due to hydrolysis of Fe ³⁺ .
Cathode reaction: Fe ³⁺ + e ⁻ → Fe ²⁺ + 2e ⁻
Anode reaction: Fe → Fe ²⁺ + 2e ⁻
Therefore, the overall reaction of corrosion is 2Fe ³⁺ + Fe → 3Fe ²⁺ .
When Sn is dissolved as Sn ²⁺ , the concentration of Fe ³⁺ is reduced by a reaction of 2Fe ³⁺ + Sn ²⁺ → 2Fe ²⁺ + Sn ⁴⁺ , thereby suppressing the overall reaction. Sn also has an effect of suppressing anodic dissolution. As a result, the presence of divalent tin ions effectively acts as a rust preventive pigment.

The present invention has been completed based on the above findings and has the following configurations (1) to (3).
(1) A highly corrosion-resistant coating composition used on the surface of steel structures or steel pipes made of ordinary steel or weathering steel, wherein the coating composition is (A) two epoxy groups in one molecule Containing epoxy resin, (B) modified resin, (C) amine-based curing agent, (D) stannous sulfate, (E) antirust pigment, (F) extender pigment, and (G) colored pigment, (B) The content of the modified resin is 50 to 90 parts by weight with respect to 100 parts by weight of the solid content of the (A) epoxy resin, and the content of (D) stannous sulfate is 100 parts by weight of the coating composition. 2.0 to 8.0 parts by weight, and (E) the content of the anticorrosive pigment is 100, the total solid content of (A) epoxy resin, (B) modified resin, and (C) amine curing agent. 10 to 30 parts by weight with respect to parts by weight, and (F) extender pigment is sericite pigment, silicon dioxide And at least one pigment selected from the group consisting of hydrous magnesium silicate pigments, the pigment volume concentration in the formed coating film is in the range of 30 to 50% by weight, and (C) amine curing A high corrosion resistance coating composition characterized in that the active hydrogen equivalent of the agent / epoxy equivalent of (A) epoxy resin is in the range of 0.4 to 0.8.
(2) The high corrosion resistance coating composition described in (1) is used as an undercoating paint (I) so that the cured film thickness per one time is 60 to 120 μm, and is applied to the surface of the steel structure or the steel pipe a plurality of times. After coating, at least one type of top coating (II) selected from the group consisting of fluororesin-based paints, acrylic silicon resin-based paints, and polyurethane resin-based paints is applied to the surface so as to have a cured film thickness of 20 to 55 μm. A painting method characterized by painting.
(3) A steel structure or a steel pipe made of ordinary steel or weathering steel, which is coated by the coating method according to (1) or (2).

  According to the present invention, rust that progresses in the depth direction of the surface of a steel structure or a steel pipe made of ordinary steel or weathering steel in a highly corrosive and severe high-fly chloride environment is effectively prevented. It is possible to provide a highly corrosion-resistant paint that can be prevented.

  The highly corrosion-resistant coating composition of the present invention is used on the surface of steel structures or steel pipes made of ordinary steel materials or weather-resistant steel materials, and (A) has two or more epoxy groups in one molecule. It contains an epoxy resin, (B) a modified resin, (C) an amine-based curing agent, (D) stannous sulfate, (E) a calcium-based rust preventive pigment, (F) an extender pigment, and (G) a colored pigment.

  (A) Epoxy resins are generally used as paint resins having excellent water resistance, adhesion, and chemical resistance. For example, “jER1001x75”, “Jer834x90” (manufactured by Mitsubishi Chemical Corporation), “EPICLON860” , “EPICLON1050”, “1055 (manufactured by DIC)”, “ERL-4221”, “same-4229” (manufactured by Union Carbide), “DER-331J” (manufactured by Dow Chemical), “AER260” ( Asahi Kasei Epoxy Co., Ltd.), “Epomic R # 140P” (Mitsui Chemicals Co., Ltd.) and other commercial products are listed. A bisphenol A type epoxy resin having an epoxy equivalent (solid content value) in the range of 200 to 500 is preferred. (A) It is preferable that 10-30 weight part of epoxy resins are mix | blended with respect to 100 weight part of coating compositions.

  (C) As the amine-based curing agent, “sanmide X-2700-49” (manufactured by Air Products Japan), “laccamide N-153-1M-65”, “same 17-202”, “same TD-961” ( DIC), “Tomide 210”, “215X”, “225” (Fuji Kasei), “Versamide 100”, “115”, “125” “230” (Henkel Hakusui) Is mentioned. A polyamidoamine adduct type that reacts with an epoxy resin at room temperature to form a cured coating is preferred.

  The mixing ratio of (A) epoxy resin and (C) amine curing agent is such that the presence of unreacted amine resin does not adversely affect the anticorrosive properties of the coating film and the active hydrogen of the amine resin. In general, the ratio of the amine-based resin is reduced in the ratio of equivalents, but also in the coating composition of the present invention, the value of active hydrogen equivalent / epoxy equivalent is 0.4 / 1 to 0.8 / 1. Preferably, it is set within the range of 0.45 / 1 to 0.75 / 1.

  (B) The modified resin is a liquid or solid non-reactive synthetic resin other than an epoxy resin, which improves the wettability to steel materials and relaxes the internal stress of the epoxy resin, thereby reducing the rust surface and the old coating. It has the effect of improving adhesion to the film. The modified epoxy resin-based paint can maintain a certain degree of flexibility in the coating film over a long period of time. Examples of the modified resin include aromatic hydrocarbon resins (for example, phenol-modified aromatic hydrocarbon resins: Hylenol PL-1000S (manufactured by KOLON CHEMICAL. CP. LTD)), toluene resins, xylene resins, petroleum resins (for example, dicyclopentadiene series). Petroleum resin: Quinton 1500 (manufactured by Nippon Zeon)), coumarone indene resin and the like. (B) It is preferable that the mixture ratio of modified resin is 50-90 weight part with respect to 100 weight part of solid content of an epoxy resin by solid content ratio.

  (D) stannous sulfate is used to suppress the progress of rust in the depth direction, and is preferably 2.0 to 8.0 parts by weight, more preferably 100 parts by weight of the coating composition. Is 3.0 to 7.5 parts by weight, more preferably 4.0 to 7.5 parts by weight. (D) When the blend of stannous sulfate is less than the above ratio, the effect of suppressing rust in the depth direction cannot be obtained, and when it is greater than the above ratio, the coating film has been immersed in water for a long period of time. In such a case, swelling is likely to occur, which is not preferable.

  In the coating composition of the present invention, (E) rust preventive pigment, (F) extender pigment, and (G) colored pigment are used as various pigments used in two-pack type epoxy resin paints for ordinary anticorrosion applications. The

  (E) Examples of the rust preventive pigment include calcium, zinc phosphate, aluminum phosphate, zinc molybdate, and barium metaborate. (E) The compounding quantity of an antirust pigment is 10-30 weight part with respect to 100 weight part of total solid content of (A) epoxy resin, (B) modified resin, and (C) amine type hardening | curing agent, Preferably 10 to 20 parts by weight. (E) When the amount of the rust preventive pigment is less than the above proportion, the effect of suppressing the generation of rust from the scratches on the coating film becomes insufficient. I can't.

  (F) The extender is used to adjust the properties of the paint. In general, in epoxy resin coatings for anticorrosion applications, extender pigments such as barium sulfate, kaolin, mica, clay, sericite, silicon dioxide, hydrous magnesium silicate, etc. are used. At least one extender pigment selected from sericite pigments, silicon dioxide pigments, and hydrous magnesium silicate pigments is used. These extender pigments are preferably 50% by weight or more of the total weight of extender pigments in the coating composition. When it is less than 50% by weight, a sufficient filling effect cannot be obtained, and the coating film strength cannot be obtained.

  (G) The color pigment is for coloring the paint, and the color pigment used for the usual two-pack type epoxy resin paint is used. Examples of such a colored pigment include, but are not limited to, titanium dioxide, carbon black, phthalocyanine blue, red rose, organic yellow pigment, and organic red pigment.

  In the coating composition of this invention, it is preferable that the pigment volume concentration which consists of a stannous sulfate, a rust preventive pigment, an extender pigment, and a coloring pigment in the coating film formed exists in the range of 30 to 50 weight%. When the pigment volume concentration is less than 30%, swelling tends to occur when the coating film is immersed for a long time, while when it is more than 50%, spot rust occurs when the coating film is immersed for a long time. It tends to occur.

  In addition to the components (A) to (G) described above, the coating composition of the present invention includes an anti-sagging agent, an antifoaming agent, a leveling agent, a coupling agent and the like used in ordinary two-pack type epoxy resin coatings. The additive can be used as it is.

  As the solvent used in the coating composition of the present invention, a solvent used for diluting an ordinary two-pack type epoxy resin coating can be used as it is, examples of which are aromatic solvents, ketone solvents, Examples include glycol ether solvents, ester solvents, alcohol solvents, and the like.

  The coating composition of the present invention can be used by being applied a plurality of times, for example, 2 to 3 times, but if it is necessary to match the color tone with the surroundings or to suppress discoloration for a long time, The coating composition of the invention can be used as an undercoat and other suitable topcoat can be used in combination. When the coating composition of the present invention is used as an undercoat paint, it is applied to the surface of a steel structure or a steel pipe so that the cured film thickness per time is 60 to 120 μm. Furthermore, a top coat is applied.

  The top coating material is selected from at least one member selected from the group consisting of a fluorine resin coating material, a polyurethane resin coating material, and an acrylic silicon resin coating material, and the film thickness is preferably 20 to 55 μm. As described above, when the undercoat and topcoat are applied, the peel area ratio in the SAE J2334 test 130 cycle of the multilayer coating film can be less than 2%, and the maximum corrosion depth can be less than 0.4 mm. .

  By painting using the coating composition of the present invention, in steel structures and steel pipes in steelworks, chemical plants, marine structures, etc., even if scratches that reach the steel material enter the coating film, the depth Since the progress of rust in the direction is suppressed, the repair is easy and the facility can be operated for a long time.

  In repair painting, due to structural restrictions and restrictions on the surrounding environment such as the presence of dangerous materials, highly effective kelen processing such as blasting that generates a large amount of dust and disc sandering that generates sparks cannot be performed. Most of the cases. In that case, it becomes a kelen treatment work with a hand tool such as a wire brush treatment or a scraper, and rust, chloride, etc. remain. By applying the coating composition of the present invention, the progress of rust in the depth direction of the steel material is suppressed. The steel material to be coated with the coating composition of the present invention is not only a normal steel material but also a weathering steel material to which a corrosion resistance improving element such as Sn, Cu, Cr, Ni or the like is added.

  Viscosity of 200 to 700 dPa · S for epoxy resins, modified resins, amine-based curing agents, stannous sulfate, calcium-based rust preventive pigments, extender pigments, colored pigments and the like shown in Tables 1 and 2 An undercoat paint was prepared by adding an appropriate amount of solvent and stirring in a uniform state. The content of each component in the table represents parts by weight.

  Air spray so that a predetermined dry film thickness is obtained at 100μm per time on the entire surface of the rusted steel plate (*) from which the created undercoat paint is made from ordinary steel material and rust is removed by wire brush treatment. And applied twice a day. In addition, the top coat was applied by air spray so that the final coat was 25 μm after the undercoat was applied. After the completion of coating, the coating was dried at 23 ° C. for 7 days to form a rust preventive coating on the test plate. In addition, the rust steel plate used what produced the same blast board by carrying out 10 cycles test of SAE J2334.

  The specimens thus prepared were tested for 130 cycles with SAE J2334 (SAE: Society Automotive Engineers), and the maximum corrosion depth of the steel material and the peeled area ratio of the coating film were measured. Similarly, the test plate coated with the top coat film was subjected to 130 cycles of SAE J2334, and the maximum corrosion depth of the steel material and the peeled area ratio of the paint film were measured.

SAE J2334 Wetting: 50 ° C., relative humidity 100%, 6 hours → salt adhesion *: 0.25 hours → Drying: 60 ° C., relative humidity 50%, 17.75 hours * Aqueous solution containing salt of the following weight% composition Spray.
_{0.5% NaCl, 0.1% CaCl 2} , 0.0075% NaHCO 3
It is considered that the wet state of the outdoor environment such as steel structures and steel pipes in steelworks and offshore structures is close to SAE J2334.

  In Table 1, Comparative Examples 1 to 3 and Examples 1 to 3 are examples in which the content of (D) stannous sulfate was changed, and Comparative Examples 4 and 5 and Examples 4 and 5 were (B ) Examples in which the content of the modified resin was changed, Comparative Examples 6 and 7 and Examples 6 and 7 were examples in which the pigment volume concentration was changed, and Comparative Examples 8 to 10 and Examples 8 and 9 were (E) Examples in which the content of the rust preventive pigment is changed. Comparative Examples 11 and 12 and Examples 10 and 11 are (C) an active hydrogen equivalent of an amine curing agent / (A) an epoxy of an epoxy resin. This is an example in which the equivalent value is changed. Examples 12 to 14 are examples of test materials obtained by further applying a top coat onto the undercoat of Example 2.

  From Table 1, Examples 1 to 3 in which the content of (D) stannous sulfate in the mixed paint is within the scope of the present invention, the content of (D) stannous sulfate is outside the scope of the present invention. It can be seen that the maximum corrosion depth and the peeled area ratio are small in both the blast steel plate and the rust steel plate as compared with certain Comparative Examples 1 to 3. This effect is even more remarkable in Examples 2 and 3 where the content of (D) stannous sulfate is in a more preferable range (3.0 to 7.5 parts by weight) for the present invention. Moreover, it turns out that the said effect is show | played similarly from Examples 12-14 even when the top coat is further applied. Furthermore, from Examples 4 to 11 and Comparative Examples 4 to 12, (B) content of modified resin, pigment volume concentration, (E) content of rust preventive pigment, or (C) active hydrogen equivalent of amine curing agent / (A) When the value of the epoxy equivalent of the epoxy resin falls outside the scope of the present invention, it is understood that the above effect is inferior even if the content of stannous sulfate is within the scope of the present invention.

  The paint shown in Table 2 was prepared by changing the type of (A) epoxy resin from that in Table 1. In Table 2, Comparative Examples 13 to 15 and Examples 15 to 17 are examples in which the content of (D) stannous sulfate was changed.

  Also from Table 2, Examples 15 to 17 in which the content of (D) stannous sulfate in the mixed paint is within the scope of the present invention, (D) the content of stannous sulfate is outside the scope of the present invention. Compared with Comparative Examples 13 to 15 in which both the blast steel plate and the rust steel plate have the maximum corrosion depth and the peeled area ratio are small, and this effect is achieved by the fact that the content of (D) stannous sulfate is It turns out that it is still more remarkable in Example 16, 17 which is a more preferable range (3.0-7.5 weight part) for invention.

  The coating composition of the present invention is extremely useful for maintenance and repair including rust control of steel structures and steel pipes made of ordinary steel or weather-resistant steel under harsh environments such as steelworks, chemical plants, and marine structures. Useful.

Claims (3)

  A highly corrosion-resistant coating composition used on the surface of steel structures or steel pipes made of ordinary steel or weathering steel, wherein the coating composition is (A) an epoxy having two or more epoxy groups in one molecule Resin, (B) modified resin, (C) amine-based curing agent, (D) stannous sulfate, (E) antirust pigment, (F) extender pigment, and (G) colored pigment, (B) The content of the modified resin is 50 to 90 parts by weight with respect to 100 parts by weight of the solid content of the (A) epoxy resin, and the content of (D) stannous sulfate is 2 with respect to 100 parts by weight of the coating composition. 0.0 to 8.0 parts by weight, and (E) the content of the anticorrosive pigment is 100 parts by weight of the total solid content of (A) epoxy resin, (B) modified resin, and (C) amine curing agent. 10 to 30 parts by weight of (F) extender pigment is a sericite pigment, a silicon dioxide pigment, And at least one pigment selected from the group consisting of hydrous magnesium silicate pigments, the pigment volume concentration in the formed coating film is in the range of 30 to 50% by weight, and (C) the amine curing agent A high corrosion resistance coating composition, wherein the active hydrogen equivalent / (A) epoxy resin has an epoxy equivalent value in the range of 0.4 to 0.8.   Applying the surface of the steel structure or the steel pipe a plurality of times as the undercoat paint (I) with the highly corrosion-resistant paint composition according to claim 1 so that the cured film thickness per time is 60 to 120 μm, Next, at least one top coat (II) selected from the group consisting of a fluororesin-based paint, an acrylic silicon resin-based paint, and a polyurethane resin-based paint is applied to the surface so as to have a cured film thickness of 20 to 55 μm. A painting method characterized by   A steel structure or steel pipe of ordinary steel material or weathering steel material, which is coated by the coating method according to claim 1 or 2.