JP2018043347A - Coating film structure - Google Patents
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- 239000011248 coating agent Substances 0.000 title claims abstract description 270
- 238000000576 coating method Methods 0.000 title claims abstract description 270
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 83
- 229920006395 saturated elastomer Polymers 0.000 claims abstract description 72
- 239000000463 material Substances 0.000 claims abstract description 18
- 229910052751 metal Inorganic materials 0.000 claims abstract description 7
- 239000002184 metal Substances 0.000 claims abstract description 7
- 239000000843 powder Substances 0.000 claims description 16
- 239000003822 epoxy resin Substances 0.000 claims description 8
- 229920000647 polyepoxide Polymers 0.000 claims description 8
- 229920001169 thermoplastic Polymers 0.000 claims description 7
- 239000004416 thermosoftening plastic Substances 0.000 claims description 7
- 239000002904 solvent Substances 0.000 claims description 6
- 229920002037 poly(vinyl butyral) polymer Polymers 0.000 claims description 5
- 229920005989 resin Polymers 0.000 claims description 5
- 239000011347 resin Substances 0.000 claims description 5
- 229920013716 polyethylene resin Polymers 0.000 claims description 2
- 230000007797 corrosion Effects 0.000 abstract description 20
- 238000005260 corrosion Methods 0.000 abstract description 20
- 238000004519 manufacturing process Methods 0.000 abstract description 4
- 239000003973 paint Substances 0.000 description 33
- 238000009792 diffusion process Methods 0.000 description 12
- 239000004698 Polyethylene Substances 0.000 description 7
- -1 polyethylene Polymers 0.000 description 7
- 229920000573 polyethylene Polymers 0.000 description 7
- 238000004088 simulation Methods 0.000 description 6
- 238000012360 testing method Methods 0.000 description 6
- 229910000831 Steel Inorganic materials 0.000 description 5
- 238000001035 drying Methods 0.000 description 5
- 239000010959 steel Substances 0.000 description 5
- 230000000694 effects Effects 0.000 description 4
- 229920000642 polymer Polymers 0.000 description 4
- 238000010586 diagram Methods 0.000 description 3
- 238000002844 melting Methods 0.000 description 3
- 230000008018 melting Effects 0.000 description 3
- 238000000034 method Methods 0.000 description 3
- 230000008961 swelling Effects 0.000 description 3
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- 239000011521 glass Substances 0.000 description 2
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- 229920005749 polyurethane resin Polymers 0.000 description 2
- JOYRKODLDBILNP-UHFFFAOYSA-N Ethyl urethane Chemical compound CCOC(N)=O JOYRKODLDBILNP-UHFFFAOYSA-N 0.000 description 1
- 229910001335 Galvanized steel Inorganic materials 0.000 description 1
- JHWNWJKBPDFINM-UHFFFAOYSA-N Laurolactam Chemical compound O=C1CCCCCCCCCCCN1 JHWNWJKBPDFINM-UHFFFAOYSA-N 0.000 description 1
- 229920000299 Nylon 12 Polymers 0.000 description 1
- 230000005856 abnormality Effects 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 239000011230 binding agent Substances 0.000 description 1
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- 238000004132 cross linking Methods 0.000 description 1
- 238000007598 dipping method Methods 0.000 description 1
- 229920006334 epoxy coating Polymers 0.000 description 1
- 239000008397 galvanized steel Substances 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 239000001034 iron oxide pigment Substances 0.000 description 1
- 239000012528 membrane Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
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- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
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Abstract
Description
本発明は、鋼材などの金属表面を保護するために用いられる塗膜構造に関するものである。 The present invention relates to a coating film structure used for protecting a metal surface such as a steel material.
設備・構造物には多くの鋼材が用いられているが、屋外で用いられているため、用いられている鋼材の腐食を防ぐことが重要となる。このような目的のために、塗膜が用いられている。例えば防食塗料による塗膜は、被塗装物に水や酸素、塩分といった腐食に寄与する因子の供給を遮断する塗膜を形成することにより、被塗装物を腐食から守っている。 Many steel materials are used for facilities and structures, but since they are used outdoors, it is important to prevent corrosion of the steel materials used. For such purposes, a coating film is used. For example, a coating film made of an anticorrosive paint protects the object to be coated from corrosion by forming a film on the object to be coated that blocks the supply of factors that contribute to corrosion such as water, oxygen, and salt.
しかし、塗膜は、上述した腐食因子を完全に遮断できるわけではなく、塗膜中を拡散して塗膜/被塗装物界面まで腐食因子が到達すると、塗膜と被塗装物との界面で腐食が発生し、塗膜下膨れなどが発生することがある。この対策として、第１に、塗膜をより厚くすることで、塗膜と被塗装物との界面へ腐食因子が到達しにくくする対策がとられている。第２に、拡散係数の低い塗料の開発がなされている。 However, the coating film cannot completely block the above-mentioned corrosion factors. When the corrosion factor reaches the interface between the coating film and the object to be coated by diffusing in the film, Corrosion may occur and swelling under the coating film may occur. As a countermeasure, firstly, a countermeasure is taken to make the corrosion factor difficult to reach the interface between the coating film and the object to be coated by making the coating film thicker. Secondly, paints with a low diffusion coefficient have been developed.
塗膜を厚くする対策は、ある程度までは有効である。しかしながら、塗料を厚く塗りすぎると塗料が硬化する過程や、硬化後の温度変化により、割れや剥がれが生じる可能性が高くなるという問題が新たに発生する。また、一度に厚く塗れない塗料は、塗装回数が増加することになり、作業工数が増加してコストが増加するという問題も発生する。 The measure to thicken the coating film is effective to some extent. However, if the paint is applied too thickly, there is a new problem that the possibility of cracking and peeling increases due to the process of curing the paint and the temperature change after curing. In addition, a paint that cannot be applied thickly at a time increases the number of times of coating, which increases the number of work steps and increases the cost.
第２の拡散係数の低い塗料については、塗料においてバインダとして用いられる樹脂の拡散係数を低下させるために、この樹脂の架橋密度を上げることが考えられる。しかし、架橋密度を上げると樹脂が固く脆くなり、塗膜と被塗装物の線膨張係数の違いにより、温度の変化により塗膜と被塗装物との界面で発生する歪み応力に柔軟に対応できず、割れたり剥がれたりしやすくなるという問題が発生する。 For paints with a low second diffusion coefficient, it is conceivable to increase the crosslinking density of the resin in order to reduce the diffusion coefficient of the resin used as the binder in the paint. However, when the crosslink density is increased, the resin becomes harder and more brittle, and due to the difference in the linear expansion coefficient between the paint film and the object to be coated, it is possible to flexibly cope with the strain stress generated at the interface between the paint film and the object to be coated due to temperature changes. However, the problem that it is easy to crack or peel off occurs.
また、塗料中に鱗片状の雲母状酸化鉄顔料や鱗片状のアルミニウム粒子顔料、ガラスフレーク（鱗片状ガラス）などを添加することで、迂回効果により塗膜としての各種腐食因子の拡散係数を低減する塗料なども開発されている。しかし、このような材料を添加した塗膜は、塗料（材料）のコストが上昇し、また、作業性が低下するなどの問題がある。 Also, by adding scaly mica-like iron oxide pigments, scaly aluminum particle pigments, glass flakes (flaky glass), etc. in the paint, the diffusion coefficient of various corrosive factors as a coating film is reduced by the detour effect. Paints to be used have also been developed. However, a coating film to which such a material is added has problems such as an increase in the cost of the paint (material) and a decrease in workability.
本発明は、以上のような問題点を解消するためになされたものであり、材料や製造コストの上昇および作業性の低下を抑制した状態で、被塗装物の腐食がより効果的に防げるようにすることを目的とする。 The present invention has been made to solve the above-described problems, and it is possible to more effectively prevent the corrosion of an object to be coated in a state in which an increase in materials and manufacturing costs and a decrease in workability are suppressed. The purpose is to.
本発明に係る塗膜構造は、金属から構成された構造体の表面に形成された第１塗膜と、第１塗膜より外側に形成された第２塗膜とを備え、第１塗膜は、第２塗膜より飽和含水量が高い。 The coating film structure according to the present invention includes a first coating film formed on the surface of a structure composed of a metal, and a second coating film formed outside the first coating film. Has a higher saturated water content than the second coating film.
上記塗膜構造において、第２塗膜の飽和含水率は、第１塗膜の飽和含水率の１／２以下とされていればよい。また、第２塗膜の飽和含水率は、第１塗膜の飽和含水率の１／５以下とされていればよい。 In the above-mentioned coating film structure, the saturated moisture content of the second coating film only needs to be ½ or less of the saturated moisture content of the first coating film. Moreover, the saturated moisture content of a 2nd coating film should just be made into 1/5 or less of the saturated moisture content of a 1st coating film.
上記塗膜構造において、第１塗膜の飽和含水率は５％以下とされ、第２塗膜の飽和含水率の１０％以下とされていればよい。また、第１塗膜の飽和含水率は３％以下とされ、第２塗膜の飽和含水率の１５％以下とされていればよい。 In the coating film structure, the saturated moisture content of the first coating film may be 5% or less, and may be 10% or less of the saturated moisture content of the second coating film. In addition, the saturated moisture content of the first coating film may be 3% or less and may be 15% or less of the saturated moisture content of the second coating film.
上記塗膜構造において、第１塗膜は、水系エポキシ樹脂から構成され、第２塗膜は、強溶剤系エポキシ樹脂から構成されていればよい。 In the coating film structure, the first coating film may be composed of a water-based epoxy resin, and the second coating film may be composed of a strong solvent-based epoxy resin.
上記塗膜構造において、第１塗膜は、熱可塑性ポリビニルブチラール樹脂粉体塗料から形成され、第２塗膜は、熱可塑性ポリエチレン樹脂粉体塗料から形成されていればよい。 In the coating film structure, the first coating film may be formed from a thermoplastic polyvinyl butyral resin powder coating material, and the second coating film may be formed from a thermoplastic polyethylene resin powder coating material.
以上説明したように、本発明によれば、被塗装物となる金属から構成された構造体の表面に、第１塗膜および第２塗膜を重ねて形成し、第１塗膜は、第２塗膜より飽和含水量が高いものとしたので、材料や製造コストの上昇および作業性の低下を抑制した状態で、被塗装物の腐食がより効果的に防げるという優れた効果が得られる。 As described above, according to the present invention, the first coating film and the second coating film are formed on the surface of the structure composed of the metal to be coated, Since the saturated water content is higher than that of the two coating films, it is possible to obtain an excellent effect that corrosion of the object to be coated can be more effectively prevented in a state in which an increase in materials and manufacturing costs and a decrease in workability are suppressed.
以下、本発明の実施の形態について図を参照して説明する。図１は、本発明の実施の形態における塗膜構造の構成を示す断面図である。この塗膜構造は、金属から構成された構造体１０１の表面に形成された第１塗膜１０２と、第１塗膜１０２より外側に形成された第２塗膜１０３とを備える。また、この塗膜構造においては、第１塗膜１０２は、第２塗膜１０３より飽和含水量が高いものとなっている。なお、第２塗膜１０３は、第１塗膜１０２より薄く形成されていればよい。
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing a configuration of a coating film structure in an embodiment of the present invention. The coating film structure includes a
以下、より詳細に説明する。塗膜の乾燥時の重さをｍ0、ある程度吸水した塗膜の重さをｍ、塗膜がそれ以上水を吸収できなくなった際の塗膜の重さをｍ∞とすると、ある程度吸水した塗膜の含水率Ｍは、「Ｍ（％）＝１００×（ｍ−ｍ0）／ｍ0」で表すことができる。また、飽和含水率Ｍ∞は、「Ｍ∞（％）＝１００×（ｍ∞−ｍ0）／ｍ0」で表すことができる。 This will be described in more detail below. If the weight of the coating when dried is m 0 , the weight of the coating that absorbs water to some extent is m, and the weight of the coating when the coating can no longer absorb water is m ∞ , it absorbs water to some extent. The moisture content M of the coating film can be represented by “M (%) = 100 × (m−m 0 ) / m 0 ”. The saturated water content M ∞ can be expressed by “M ∞ (%) = 100 × (m ∞ −m 0 ) / m 0 ”.
硬化後にＭ∞が３％の塗膜Ａ（第２塗膜）を形成する塗料Ａと、硬化後にＭ∞が１５％の塗膜Ｂ（第１塗膜）を形成する塗料Ｂとがある。この組み合わせでは、塗膜Ａの飽和含水率は、塗膜Ｂの飽和含水率の１／５となっている。塗料Ａは、例えば強溶剤系エポキシ樹脂塗料であり、塗料Ｂは例えば水系エポキシ樹脂塗料である。 And coating A where M ∞ forms 3% of the coating film A (second coating) After curing, M ∞ after curing is a coating material B to form a 15% coating B (first coating). In this combination, the saturated moisture content of the coating film A is 1/5 of the saturated moisture content of the coating film B. The paint A is, for example, a strong solvent-based epoxy resin paint, and the paint B is, for example, a water-based epoxy resin paint.
塗装物（塗膜）が降雨などにより濡れた場合、塗膜中を塗膜／被塗装物界面に向かって水が拡散していくが、この挙動はフィックの法則に従う。前述の塗膜Ａ、塗膜Ｂについて、物質の濃度ｕの非定常拡散はフィックの第２法則により，一次元では次のように表せる。 When a coated object (coating film) gets wet due to rain or the like, water diffuses in the coating film toward the coating film / coating object interface, and this behavior follows Fick's law. With respect to the aforementioned coating film A and coating film B, the unsteady diffusion of the substance concentration u can be expressed in one dimension as follows according to Fick's second law.
この式を差分法の陽解法を用いて表現し、乾燥塗膜が水に濡れた場合の塗膜の深さにおける含水率をシミュレーションした。塗膜Ａのシミュレーション結果を図２に示し、塗膜Ｂのシミュレーション結果を図３に示す。図２，図３において、Ｘ軸は０μｍが水／塗膜界面からの距離であり、１２５μｍの位置が塗膜／被塗装物界面である。拡散係数は、塗膜Ａ、塗膜Ｂとも５×１０-14ｍ2／ｓとした。 This equation was expressed using an explicit method of the difference method, and the moisture content at the depth of the coating film when the dried coating film was wet with water was simulated. The simulation result of the coating film A is shown in FIG. 2, and the simulation result of the coating film B is shown in FIG. In FIG. 2 and FIG. 3, 0 μm is the distance from the water / coating interface and the position of 125 μm is the coating / coating interface on the X axis. The diffusion coefficient was 5 × 10 −14 m 2 / s for both coating film A and coating film B.
図２、図３に示すように、塗膜Ａ、塗膜Ｂとも時間経過とともに、水／塗膜界面から塗膜／被塗装物界面へ水が拡散していっていることがわかる。塗膜Ａは、飽和含水率が３％であり、無限の時間が経過した後には含水率は全ての点で３％となる。塗膜Ｂは、飽和含水率が１５％であり、無限の時間が経過した後には含水率は全ての点で１５％となる。 As shown in FIGS. 2 and 3, it is understood that water is diffusing from the water / coating interface to the coating / coating object interface with time in both coating A and coating B. The coating film A has a saturated moisture content of 3%, and after an infinite time has elapsed, the moisture content becomes 3% in all respects. The coating film B has a saturated moisture content of 15%, and after an infinite time has elapsed, the moisture content becomes 15% in all respects.
塗膜Ａ、塗膜Ｂの同じ時間経過後の含水率の曲線は相似形であり、拡散係数が同じであれば、飽和含水率に比例して縦軸の値が大きくなる。このため、飽和含水率が異なっても拡散係数が同じであれば、同じ時間経過後の塗膜の各地点における含水進行率「含水率Ｍ ／飽和含水率Ｍ∞）も同じとなる。 The moisture content curves of the coating film A and the coating film B after the same time elapse are similar, and if the diffusion coefficient is the same, the value on the vertical axis increases in proportion to the saturated moisture content. For this reason, if the diffusion coefficient is the same even if the saturated moisture content is different, the moisture content progression rate “moisture content M 1 / saturated moisture content M ∞ ” at each point of the coating film after the same time has also become the same.
塗膜Ａと塗膜Ｂとを比較すると、塗膜／被塗装物界面（ｘ＝１２５μｍ地点）の含水率Ｍは、明らかに飽和含水率Ｍ∞が１５％の塗膜Ｂの方が多い。しかし、実際に塗料Ａにより塗装した塗装試験片、および塗料Ｂにより塗装した塗装試験片を、「JIS K 5600-7-9サイクルＡ」に規定される複合サイクル試験で２０００時間（３か月弱）の試験を実施し、３〜４日おきに観察したところ、塗膜Ｂの方の防食性が劣ることはなく、塗膜Ａと塗膜Ｂの防食性は同等であった。また、両塗膜ともほぼ同時期に膨れが発生した（塗料Ａは４０日目、塗料Ｂは４３日目）。 When the coating film A and the coating film B are compared, the moisture content M at the coating film / object interface (x = 125 μm point) is obviously more in the coating film B having a saturated moisture content M ∞ of 15%. However, a paint test piece actually painted with paint A and a paint test piece painted with paint B were subjected to a combined cycle test specified in “JIS K 5600-7-9 cycle A” for 2000 hours (less than 3 months). ) And was observed every 3 to 4 days, the anticorrosion properties of the coating film B were not inferior, and the anticorrosion properties of the coating film A and the coating film B were equivalent. In addition, swelling occurred in both coating films at almost the same time (paint A was on the 40th day, paint B was on the 43rd day).
従って、発明者らは、塗膜／被塗装物界面の含水率Ｍが、単純に塗膜／被塗装物界面での腐食に寄与しているわけではないと考えた。 Therefore, the inventors considered that the moisture content M at the coating film / object interface does not simply contribute to the corrosion at the coating film / object interface.
高分子材料中の水分子には、高分子鎖と水素結合などで結合している結合水と、自由な水分子（自由水）があり、塗料において自由水は少ないことが報告されている（非特許文献１参照）。さらに、結合水は、強結合の水と弱結合の水の２種類に区別される。塗膜中に拡散により浸入した水は、当初は強結合水となり、次いで弱結合水となり、この後、自由水となることが報告されている。また、飽和含水した場合でも、自由水の割合は少ないことが報告されている。 It is reported that water molecules in polymer materials include bound water bonded to polymer chains by hydrogen bonds, etc., and free water molecules (free water), and there is little free water in paints ( Non-patent document 1). Further, the bound water is classified into two types of strongly-bonded water and weakly-bonded water. It has been reported that water that has penetrated into the coating film by diffusion initially becomes strongly bound water, then weakly bound water, and then free water. Moreover, it is reported that the ratio of free water is small even when saturated water is contained.
以上のことをまとめると、含水進行率（含水率Ｍ／飽和含水率Ｍ∞）の値が低いうちは、塗膜中に存在する水は結合水となり、含水の進行がさらに進むにつれ、自由水が存在するようになる。 To summarize the above, while the water content progression rate (water content M / saturated water content M ∞ ) is low, the water present in the coating film becomes bound water, and as the water content progresses further, free water Comes to exist.
前述したように、飽和含水率が大きく異なっても拡散係数が同じであれば、同じ時間経過後の塗膜の各地点における含水進行率（含水率Ｍ／飽和含水率Ｍ∞）も同じとなる。 As described above, when the diffusion coefficient is the same even if the saturated moisture content is greatly different, the moisture content progression rate (moisture content M / saturated moisture content M ∞ ) at each point of the coating film after the same time has also become the same. .
塗膜Ａと塗膜Ｂとで性能に有意な差が見られなかったことから、塗膜／被塗装物界面の腐食において重要な事項は、塗膜／被塗装物界面の「含水率Ｍ」ではなく、塗膜／被塗装物界面の含水進行率（含水率Ｍ／飽和含水率Ｍ∞）であると考えられる。 Since there was no significant difference in performance between coating film A and coating film B, an important matter in the corrosion of the coating film / coating object interface was “moisture content M” of the coating film / coating object interface. Instead, it is considered that it is the water content progression rate (water content M / saturated water content M ∞ ) at the coating film / object interface.
次に、被塗装物の上に塗料Ｂを塗布・乾燥して塗膜Ｂを形成した後、この上に塗料Ａを塗布乾燥させて塗膜Ａを形成した場合の塗膜（塗膜構造）についてシミュレーションした。シミュレーション結果を図４に示す。塗膜Ａの厚さは２５μｍ、塗膜Ｂの厚さは１００μｍとし、塗膜構造の合計厚さは１２５μｍである。 Next, after coating B is applied and dried on the object to be coated to form a coating film B, coating film A is formed by coating and drying coating A on the coating film (coating structure). Simulated about. The simulation results are shown in FIG. The thickness of the coating film A is 25 μm, the thickness of the coating film B is 100 μm, and the total thickness of the coating film structure is 125 μm.
拡散により移動する水の量は水の濃度（含水率）の勾配に比例するので、飽和含水率３％の塗膜Ａが塗膜Ｂの上に形成されている時、塗膜Ｂは飽和含水率１５％であるにもかかわらず、３％以上の含水率にならない。従って、塗膜Ｂの飽和含水率は１５％なので、塗膜Ｂ／被塗装物の界面の含水進行率（含水率Ｍ／飽和含水率Ｍ∞）は０．２以上にはならない。 Since the amount of water that moves due to diffusion is proportional to the gradient of water concentration (water content), when a coating film A having a saturation moisture content of 3% is formed on the coating film B, the coating film B has a saturated moisture content. Even though the rate is 15%, the water content is not 3% or more. Therefore, since the saturated moisture content of the coating film B is 15%, the moisture content progression rate (moisture content M / saturated moisture content M ∞ ) at the interface of the coating film B / the object to be coated does not become 0.2 or more.
図４に示すように、５０時間経過後に含水率は約２％なので、含水進行率（含水率Ｍ／飽和含水率Ｍ∞）は約０．１３となる。含水進行率（含水率Ｍ／飽和含水率Ｍ∞）が低い場合、この水は全て結合水であると考えられることから、腐食は進行しにくくなる。 As shown in FIG. 4, after 50 hours, the water content is about 2%, so the water content progression rate (water content M / saturated water content M ∞ ) is about 0.13. When the water content progression rate (moisture content M / saturated water content M ∞ ) is low, all of this water is considered to be bound water, so that corrosion is difficult to proceed.
ただしこれは、塗膜中に水が理想的に均一に分散している場合であり、実際は上記のシミュレーションのようにはならない。なぜなら、塗膜中には、体積顔料などの添加物の存在や、また塗料自身の高分子鎖の存在により、水が存在できない場所が存在しており、微視的には含水率が高い部分と低い部分が混在しているためである（前述の３％や１５％といった含水率は塗膜バルクの平均的な含水率である）。 However, this is a case where water is ideally uniformly dispersed in the coating film, and the simulation is not actually performed as described above. Because there are places where water cannot exist due to the presence of additives such as volume pigments and the presence of polymer chains in the coating itself, there are microscopically high water content parts. This is because the moisture content such as 3% or 15% is an average moisture content of the coating film bulk.
従って、実際には塗膜Ａと塗膜Ｂとの界面で微視的には含水率が３％より高い部分があるので、塗膜Ｂの含水率は３％より高くなる。実際にこのような塗膜に、長時間、吸水させて重さを測定すると、塗膜Ｂの含水率は３％以上となることがわかる。 Accordingly, there is actually a portion where the moisture content is higher than 3% microscopically at the interface between the coating film A and the coating film B, so that the moisture content of the coating film B is higher than 3%. Actually, when such a coating film is allowed to absorb water for a long time and its weight is measured, it is found that the moisture content of the coating film B becomes 3% or more.
以上のことより、塗膜Ａは断面積において飽和含水率１００％の部分が３％、飽和含水率０％の部分が９７％で、平均的な飽和含水率が３％となっている塗膜と仮定し、塗膜Ｂは断面積において飽和含水率１００％の部分が１５％、飽和含水率０％の部分が８５％で、平均的な飽和含水率が１５％となっている塗膜であると仮定し、前述の塗膜Ａと塗膜Ｂの複合塗膜の塗膜構造の吸水挙動をシミュレーションし直した。このシミュレーション結果を図５に示す。 In view of the above, the coating film A has a cross-sectional area of 3% at a saturated moisture content of 100%, 97% at a saturated moisture content of 0%, and an average saturated moisture content of 3%. Assuming that, in the cross-sectional area, the coating film B is a coating film having a saturated moisture content of 100% at 15%, a saturated moisture content of 0% at 85%, and an average saturated moisture content of 15%. Assuming that there was, the water absorption behavior of the coating film structure of the composite coating film of coating film A and coating film B described above was re-simulated. The simulation result is shown in FIG.
図５に示すように、塗膜／被塗装物界面の含水率は３％以上となり、実際の含水挙動をよく模擬できている。図２、図３に示すように、５０時間経過後の含水率Ｍは、塗膜Ａが約２％、塗膜Ｂが約１０％であり、含水進行率（含水率Ｍ／飽和含水率Ｍ∞）は、いずれも約２／３である。これらに対し、図５に示すように塗膜Ａと塗膜Ｂとを重ねた塗膜構造においては、塗膜／被塗装物界面の含水率約５％であり、含水進行率（含水率Ｍ／飽和含水率Ｍ∞）は約１／３と、塗膜Ａや塗膜Ｂを単独で同じ厚さ塗装した場合の半分程度となる。 As shown in FIG. 5, the moisture content at the coating film / object interface is 3% or more, and the actual moisture behavior is well simulated. As shown in FIG. 2 and FIG. 3, the moisture content M after 50 hours is about 2% for the coating film A and about 10% for the coating film B, and the moisture content progression rate (moisture content M / saturated moisture content M). ∞ ) is about 2/3 in all cases. On the other hand, in the coating film structure in which the coating film A and the coating film B are overlapped as shown in FIG. / Saturated water content M ∞ ) is about 1/3, which is about half that when coating A and coating B are individually coated with the same thickness.
図５の結果は極端な例であり、実際の塗膜は図４の結果と図５の結果との中間の形態をとると考えられる。すると、実際の５０時間経過後の含水進行率（含水率Ｍ／飽和含水率Ｍ∞）は０．１３〜約１／３（０．３３）となり、塗膜Ａおよび塗膜Ｂを単独で用いた場合の約２／３（０．６７）と比較して、塗膜Ａと塗膜Ｂとを重ねた塗膜構造は、大幅に低い値となる。 The result of FIG. 5 is an extreme example, and it is considered that the actual coating film takes an intermediate form between the result of FIG. 4 and the result of FIG. Then, the actual water content progression rate after 50 hours (water content M / saturated water content M ∞ ) was 0.13 to about 1/3 (0.33), and the coating film A and the coating film B were used alone. Compared with about 2/3 (0.67) in the case of the coating film, the coating film structure in which the coating film A and the coating film B are overlapped has a significantly low value.
また、上述同様のシミュレーションを、飽和含水率５％の塗膜Ｃ、飽和含水率１０％の塗膜Ｄを用いた実施した結果、塗膜Ｃを塗膜Ｄの上に形成した塗膜構造は、塗膜Ｃおよび塗膜Ｄを単独で用いた場合に比較し、５０時間経過後の塗膜／鋼材界面の含水進行率が０．１程度低下することを確認した。この組み合わせでは、塗膜Ｃの飽和含水率は、塗膜Ｄの飽和含水率の１／２となっている。 Moreover, as a result of carrying out the same simulation as described above using the coating film C having a saturated moisture content of 5% and the coating film D having a saturation moisture content of 10%, the coating film structure in which the coating film C was formed on the coating film D was As compared with the case where the coating film C and the coating film D were used alone, it was confirmed that the water content progression rate at the coating film / steel material interface after 50 hours was reduced by about 0.1. In this combination, the saturated moisture content of the coating film C is ½ of the saturated moisture content of the coating film D.
以上の結果より明らかなように、塗膜Ａの部分の飽和含水率が低いと塗膜Ａの部分が律速的な状態となり、塗膜Ａから塗膜Ｂへの水の供給速度が遅くなる。塗膜Ｂの飽和含水率は高い（＝多くの水を吸水できる）ため、塗膜Ａから塗膜Ｂへの水の供給速度が遅い場合、塗膜Ｂ／被塗装物界面の含水進行率（含水率Ｍ／飽和含水率Ｍ∞）は高くなりにくい（＝塗膜／被塗装物界面での腐食が進行しにくい）ことがわかる。 As is clear from the above results, when the saturated moisture content of the coating film A portion is low, the coating film A portion is in a rate-determining state, and the water supply rate from the coating film A to the coating film B is slow. Since the saturated moisture content of the coating film B is high (= a large amount of water can be absorbed), when the water supply rate from the coating film A to the coating film B is slow, the moisture content progression rate at the coating film B / coating object interface ( It can be seen that the water content M / saturated water content M ∞ ) is not easily increased (= corrosion at the coating film / coating object interface is unlikely to proceed).
次に、実際に塗膜を形成した実験の結果について説明する。実験においては、平面形状７０ｍｍ×１５０ｍｍ、板厚３．２ｍｍの溶融亜鉛めっき鋼板を用いた。この鋼板に対し、塗料Ａを厚さ１２５μｍ塗布して乾燥して塗膜Ａを形成した第１サンプル、塗料Ｂを１２５μｍ塗布して乾燥した塗膜Ｂを形成した第２サンプル、塗料Ｂを１００μｍ塗布して乾燥して塗膜Ｂを形成し、この上に塗料Ａを２５μｍ塗布して乾燥して塗膜Ａを形成した第３サンプルを作製した。 Next, the results of an experiment in which a coating film was actually formed will be described. In the experiment, a hot dip galvanized steel sheet having a planar shape of 70 mm × 150 mm and a plate thickness of 3.2 mm was used. A first sample in which paint A was applied to the steel sheet with a thickness of 125 μm and dried to form a coating film A, a second sample in which paint B was applied to a coating with a thickness of 125 μm and a dried coating film B was formed, and paint B was 100 μm. The coating B was formed by coating and drying, and a third sample in which the coating A was formed by applying 25 μm of the coating A and drying it was prepared.
これら３つのサンプルについて、「JIS K 5600-7-9サイクルＡ」に規定される複合サイクル試験で２０００時間の試験を実施した。試験の結果、第１サンプルおよび第２サンプルについては、塗膜下で腐食が進行して膨れが発生した。これに対し、第３サンプルについては、異常が見られなかった。 These three samples were subjected to a 2000 hour test in the combined cycle test specified in “JIS K 5600-7-9 cycle A”. As a result of the test, as for the first sample and the second sample, the corrosion progressed under the coating film and the swelling occurred. On the other hand, no abnormality was observed for the third sample.
このように、同じ塗膜厚さであっても、飽和含水率の異なる塗膜を重ねて塗膜構造とすることで、各々の塗膜と単独として用いる場合より、防食性を向上させることができることが、実験の結果において実証された。 Thus, even if it is the same coating film thickness, it is possible to improve the anticorrosion property by using the coating film structure by overlapping the coating films having different saturated moisture contents, compared with the case where each coating film is used alone. The ability to do so has been demonstrated in experimental results.
塗膜構造としては、下層の第１塗膜の方が、上層の第２塗膜より飽和含水量が高いことが重要であり、第１塗膜としては、具体的には水系エポキシ樹脂塗料、水系ポリウレタン樹脂塗料などによる塗膜とすればよい。また、上層の第２塗膜としては、具体的には強溶剤系フッ素樹脂塗料、強溶剤系ポリウレタン樹脂塗料、強溶剤系エポキシ樹脂塗料などによると膜とすればよい。 As the coating film structure, it is important that the lower first coating film has a higher saturated water content than the upper second coating film. Specifically, as the first coating film, a water-based epoxy resin paint, What is necessary is just to set it as the coating film by a water-based polyurethane resin coating material. Further, the upper second coating film may be a film according to a strong solvent type fluororesin paint, a strong solvent type polyurethane resin paint, a strong solvent type epoxy resin paint or the like.
また、塗装後もしくは塗装中に塗料が分離し、飽和含水率の低い層が飽和含水率の高い層の上側に形成されるように塗料を設計して塗膜を形成してもよい。具体的には例えばポリエチレン粉末とポリビニルブチラール粉末を混合した熱可塑性紛体塗料、ポリエチレン粉末とナイロン粉末を混合した熱可塑性紛体塗料などが好適に用いられる。例えば、ポリエチレン粉末とポリビニルブチラール粉末もしくはポリエチレン粉末とナイロン１２粉末を体積比率１：１で混合し、２５０℃にて流動浸漬法で焼き付け塗装した後、常温になるまで空冷して塗膜構造を作製すればよい。 Alternatively, the coating may be formed by designing the coating so that the coating is separated after coating or during coating, and the layer having a low saturated moisture content is formed above the layer having a high saturated moisture content. Specifically, for example, a thermoplastic powder coating in which polyethylene powder and polyvinyl butyral powder are mixed, and a thermoplastic powder coating in which polyethylene powder and nylon powder are mixed is preferably used. For example, polyethylene powder and polyvinyl butyral powder or polyethylene powder and nylon 12 powder are mixed at a volume ratio of 1: 1, baked and coated at 250 ° C. using a fluidized dipping method, and then air-cooled to room temperature to produce a coating film structure. do it.
このように２種類の粉末を混合した熱可塑性紛体塗料は、焼き付け後、冷却して硬化する際に融点の低いもの（この場合ポリエチレン）が最上層に多く含まれるようになることから、飽和含水率が低く、融点の低いポリエチレンと、飽和含水率が高く、融点がポリエチレンより高いポリビニルブチラールやナイロンの組み合わせが適している。 Since the thermoplastic powder paint in which two kinds of powders are mixed in this way is often filled with a low melting point (in this case, polyethylene) in the uppermost layer when cooled and cured after baking, A combination of polyethylene having a low rate and a low melting point and polyvinyl butyral or nylon having a high saturated water content and a melting point higher than that of polyethylene is suitable.
上述した塗料以外においても、飽和含水率の低い層が飽和含水率の高い層の上側に形成されるように塗料および塗膜構造を設計すれば、同様の効果が期待できることは容易に類推できる。 In addition to the coating materials described above, it can be easily analogized that the same effect can be expected if the coating material and the coating film structure are designed so that the layer having a low saturated water content is formed above the layer having a high saturated water content.
また、上述では、説明を簡易にするため、２層の場合について説明を実施したが、３層以上の塗膜構造の場合にも、飽和含水率の低い層が飽和含水率の高い層よりも上の層となるように塗膜構造を設計することで、同様の効果が期待できることは容易に類推できる。また、飽和含水率の低い層と飽和含水率の高い層は直接接していなくてもよく、間に他の層（塗料）を挟んでもよい。また飽和含水率の高い層と被塗装物についても直接接していなくてもよく、間に他の層（塗料）を挟んでもよい。 In addition, in the above description, the case of two layers has been described in order to simplify the description. However, even in the case of a coating structure of three layers or more, a layer having a low saturated moisture content is higher than a layer having a high saturated moisture content. It can be easily analogized that the same effect can be expected by designing the coating film structure so as to be the upper layer. Further, the layer having a low saturated moisture content and the layer having a high saturated moisture content may not be in direct contact with each other, and another layer (paint) may be sandwiched therebetween. Further, the layer having a high saturated moisture content may not be in direct contact with the object to be coated, and another layer (paint) may be sandwiched therebetween.
以上に説明したように、本発明によれば、被塗装物となる金属から構成された構造体の表面に、第１塗膜および第２塗膜を重ねて形成し、第１塗膜は、第２塗膜より飽和含水量が高いものとしたので、材料や製造コストの上昇および作業性の低下を抑制した状態で、被塗装物の腐食がより効果的に防げるようになる。 As described above, according to the present invention, the first coating film and the second coating film are formed on the surface of the structure composed of the metal to be coated, Since the saturated water content is higher than that of the second coating film, it is possible to more effectively prevent the corrosion of the object to be coated in a state in which an increase in materials and manufacturing costs and a decrease in workability are suppressed.
従来は、膜厚を厚くし、また材料における拡散係数を下げることにより、塗膜の腐食因子が塗膜／被塗装物 界面へ到達しにくくするアプローチで防食性を高めていた。これに対し、発明者らは、被塗装物側の層は飽和含水率が高い層（第１塗膜）、この上を覆う層（第２塗膜）は飽和含水率が低い層とすることにより、塗膜と被塗装物との界面での含水進行率（含水率／飽和含水率）が高くなりにくくなり、腐食を抑制することで防食性を高められることを見出した。塗膜と被塗装物との界面まで水が到達しても、含水進行率が低いうちは水分子が周囲の高分子鎖と水素結合し、腐食が進行しにくいことから、防食性の高い塗膜構造が実現できる。 In the past, by increasing the film thickness and lowering the diffusion coefficient in the material, the anticorrosion property was improved by an approach that makes it difficult for the corrosion factor of the coating to reach the coating film / object interface. On the other hand, the inventors have determined that the layer on the object side is a layer having a high saturated moisture content (first coating film), and the layer covering the layer (second coating film) is a layer having a low saturated moisture content. As a result, it has been found that the moisture content progression rate (moisture content / saturated moisture content) at the interface between the coating film and the object to be coated is less likely to be high, and the corrosion resistance can be improved by suppressing corrosion. Even when water reaches the interface between the coating film and the object to be coated, while the water content progression rate is low, water molecules are hydrogen-bonded to the surrounding polymer chains and corrosion does not proceed easily. A membrane structure can be realized.
なお、本発明は以上に説明した実施の形態に限定されるものではなく、本発明の技術的思想内で、当分野において通常の知識を有する者により、多くの変形および組み合わせが実施可能であることは明白である。 The present invention is not limited to the embodiment described above, and many modifications and combinations can be implemented by those having ordinary knowledge in the art within the technical idea of the present invention. It is obvious.
１０１…構造体、１０２…第１塗膜、１０３…第２塗膜。 101 ... Structure, 102 ... First coating film, 103 ... Second coating film.
Claims (7)
前記第１塗膜より外側に形成された第２塗膜と
を備え、
前記第１塗膜は、前記第２塗膜より飽和含水量が高いことを特徴とする塗膜構造。 A first coating film formed on the surface of a structure composed of metal;
A second coating film formed outside the first coating film,
The first coating film has a saturated water content higher than that of the second coating film.
前記第２塗膜の飽和含水率は、前記第１塗膜の飽和含水率の１／２以下とされていることを特徴とする塗膜構造。 In the coating film structure according to claim 1,
The coating film structure characterized in that the saturated moisture content of the second coating film is ½ or less of the saturated moisture content of the first coating film.
前記第２塗膜の飽和含水率は、前記第１塗膜の飽和含水率の１／５以下とされていることを特徴とする塗膜構造。 In the coating film structure according to claim 2,
The coating film structure characterized in that the saturated moisture content of the second coating film is 1/5 or less of the saturated moisture content of the first coating film.
前記第１塗膜の飽和含水率は５％以下とされ、前記第２塗膜の飽和含水率の１０％以下とされていることを特徴とする塗膜構造。 In the coating film structure according to claim 2,
The coating film structure characterized in that the saturation moisture content of the first coating film is 5% or less and the saturation moisture content of the second coating film is 10% or less.
前記第１塗膜の飽和含水率は３％以下とされ、前記第２塗膜の飽和含水率の１５％以下とされていることを特徴とする塗膜構造。 In the coating film structure according to claim 3,
The coating film structure characterized in that the saturation moisture content of the first coating film is 3% or less and 15% or less of the saturation moisture content of the second coating film.
前記第１塗膜は、水系エポキシ樹脂から構成され、
前記第２塗膜は、強溶剤系エポキシ樹脂から構成されている
ことを特徴とする塗膜構造。 In the coating film structure according to any one of claims 1 to 5,
The first coating film is composed of a water-based epoxy resin,
The said 2nd coating film is comprised from strong solvent type epoxy resin. The coating-film structure characterized by the above-mentioned.
前記第１塗膜は、熱可塑性ポリビニルブチラール樹脂粉体塗料から形成され、
前記第２塗膜は、熱可塑性ポリエチレン樹脂粉体塗料から形成されている
ことを特徴とする塗膜構造。 In the coating film structure according to any one of claims 1 to 5,
The first coating film is formed from a thermoplastic polyvinyl butyral resin powder coating,
The said 2nd coating film is formed from the thermoplastic polyethylene resin powder coating material. The coating-film structure characterized by the above-mentioned.
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS61110545A (en) * | 1984-11-02 | 1986-05-28 | 川崎製鉄株式会社 | Rust-proof coated steel material |
| JPH10264301A (en) * | 1997-03-26 | 1998-10-06 | Kurimoto Ltd | Method for corrosion-proof coating of steel pipe, and steel pipe provided with corrosion-proof coating |
| JP2009023472A (en) * | 2007-07-19 | 2009-02-05 | Kuraray Co Ltd | Cart coated with polyvinyl acetal powder coating |
| JP2012158705A (en) * | 2011-02-02 | 2012-08-23 | Nippon Telegr & Teleph Corp <Ntt> | Powder coating |
| WO2013065452A1 (en) * | 2011-10-31 | 2013-05-10 | 三菱重工業株式会社 | Composition for lining and lining method |
-
2016
- 2016-09-12 JP JP2016177332A patent/JP2018043347A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS61110545A (en) * | 1984-11-02 | 1986-05-28 | 川崎製鉄株式会社 | Rust-proof coated steel material |
| JPH10264301A (en) * | 1997-03-26 | 1998-10-06 | Kurimoto Ltd | Method for corrosion-proof coating of steel pipe, and steel pipe provided with corrosion-proof coating |
| JP2009023472A (en) * | 2007-07-19 | 2009-02-05 | Kuraray Co Ltd | Cart coated with polyvinyl acetal powder coating |
| JP2012158705A (en) * | 2011-02-02 | 2012-08-23 | Nippon Telegr & Teleph Corp <Ntt> | Powder coating |
| WO2013065452A1 (en) * | 2011-10-31 | 2013-05-10 | 三菱重工業株式会社 | Composition for lining and lining method |
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