JP7747014B2 - Accelerated deterioration test method for coating films - Google Patents
Accelerated deterioration test method for coating filmsInfo
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Description
本発明は、塗膜の劣化促進試験方法に関する。 The present invention relates to a method for accelerated deterioration testing of coating films.
製鉄所では、粗鋼を生産するために、鉱石、石炭、コークス等の原料を荷揚し、ベルトコンベアを用いて運搬する。このとき、ベルト（コンベアベルト）から原料がこぼれて、ベルトコンベアおよび／または架台の躯体上に、ダストとして堆積する場合がある。
このようなダスト（「腐食性ダスト」とも呼ぶ）は、硫黄成分などの腐食成分を含有するため、躯体を構成する鋼板などの金属板に対して、高い腐食性を示す。
In steelworks, raw materials such as ore, coal, and coke are unloaded and transported using belt conveyors to produce crude steel. During this process, raw materials may spill from the belt (conveyor belt) and accumulate as dust on the belt conveyor and/or the frame of the rack.
Such dust (also called "corrosive dust") contains corrosive components such as sulfur, and is therefore highly corrosive to metal plates such as steel plates that make up the building frame.
躯体上に堆積したダストは、降雨などにより水が供給されると、水分を含む。
この場合、ダストの腐食成分と、ダストの水分による濡れ時間の増加とに起因して、一般的な屋外環境下と比較して、最大で約１０倍の速度で、躯体の腐食が進行する。
Dust accumulated on the structure absorbs moisture when water is supplied by rainfall or the like.
In this case, due to the corrosive components of the dust and the increased time spent wet due to the moisture in the dust, corrosion of the structure progresses at a maximum rate approximately 10 times faster than in a typical outdoor environment.
躯体の腐食を防止するには、躯体を構成する部材としてステンレス鋼を用いることが有効であるが、コスト面で実用的でない。このため、例えば、低炭素鋼からなる鋼板の表面が塗膜で覆われた部材が用いられる。
塗膜の劣化進行は長い時間を要することから、塗膜の性能は、塗膜の劣化を人工的に速める塗膜劣化促進試験によって評価される（特許文献１を参照）。
To prevent corrosion of the skeleton, it is effective to use stainless steel for the structural members, but this is not practical from a cost perspective. For this reason, for example, members made of low-carbon steel with the surface covered with a paint film are used.
Since the progression of deterioration of a coating film takes a long time, the performance of the coating film is evaluated by a coating film deterioration acceleration test in which the deterioration of the coating film is artificially accelerated (see Patent Document 1).
従来の塗膜劣化促進試験は、一般的な屋外曝露環境下での塗膜の劣化を想定したものであるため、腐食性ダスト環境下での塗膜の劣化を十分に再現できない。
そこで、本発明は、腐食性ダスト環境下での塗膜の劣化を十分に再現できる、塗膜の劣化促進試験方法を提供することを目的とする。
Conventional accelerated coating deterioration tests are designed to simulate deterioration of coatings under general outdoor exposure environments, and therefore cannot adequately reproduce deterioration of coatings under corrosive dust environments.
Therefore, an object of the present invention is to provide a method for testing accelerated deterioration of a coating film, which can adequately reproduce deterioration of the coating film in a corrosive dust environment.
本発明者らは、鋭意検討した結果、下記構成を採用することにより、上記目的が達成されることを見出し、本発明を完成させた。
すなわち、本発明は、以下の［１］～［７］を提供する。
［１］金属板の表面に塗膜が配置された試験片を、腐食成分を含有する腐食性ダストに埋設して、上記塗膜を上記腐食性ダストと接触させる埋設工程と、上記腐食性ダストに水を噴霧して、上記腐食性ダストに水分を含ませる噴霧工程と、上記試験片および上記腐食性ダストの温度を上昇させて、上記腐食性ダストの水分を上記塗膜が吸収することを促進する湿潤工程と、上記試験片および上記腐食性ダストを乾燥する乾燥工程と、を備える、塗膜の劣化促進試験方法。
［２］上記腐食成分が、硫黄成分である、上記［１］に記載の塗膜の劣化促進試験方法。
［３］上記噴霧工程で噴霧する水が、純水である、上記［１］または［２］に記載の塗膜の劣化促進試験方法。
［４］上記噴霧工程では、上記腐食性ダストの含水率を飽和させる、上記［１］～［３］のいずれかに記載の塗膜の劣化促進試験方法。
［５］上記金属板が、鋼板である、上記［１］～［４］のいずれかに記載の塗膜の劣化促進試験方法。
［６］上記噴霧工程、上記湿潤工程および上記乾燥工程を、それぞれ、下記条件で実施する、上記［１］～［５］のいずれかに記載の塗膜の劣化促進試験方法。
上記噴霧工程：温度２５～６０℃、時間８～１６ｈ
上記湿潤工程：温度４０～６０℃、相対湿度９０～１００％、時間８～１６ｈ
上記乾燥工程：温度５０～７０℃、相対湿度４５～５５％、時間２０～２８ｈ
［７］上記噴霧工程、上記湿潤工程および上記乾燥工程を、それぞれ、下記条件で実施する、上記［１］～［６］のいずれかに記載の塗膜の劣化促進試験方法。
上記噴霧工程：温度３５℃、時間１２ｈ
上記湿潤工程：温度５０℃、相対湿度９５％、時間１２ｈ
上記乾燥工程：温度６０℃、相対湿度５０％、時間２４ｈ
As a result of extensive research, the present inventors have found that the above object can be achieved by employing the following configuration, and have completed the present invention.
That is, the present invention provides the following [1] to [7].
[1] A method for accelerated deterioration testing of a coating film, comprising: an embedding step of embedding a test piece having a coating film disposed on the surface of a metal plate in corrosive dust containing a corrosive component to bring the coating film into contact with the corrosive dust; a spraying step of spraying water onto the corrosive dust to moisten the corrosive dust; a wetting step of increasing the temperature of the test piece and the corrosive dust to promote absorption of the moisture in the corrosive dust by the coating film; and a drying step of drying the test piece and the corrosive dust.
[2] The accelerated deterioration test method for a coating film according to the above [1], wherein the corrosive component is a sulfur component.
[3] The accelerated deterioration test method for a coating film according to the above [1] or [2], wherein the water sprayed in the spraying step is pure water.
[4] The accelerated deterioration test method for a coating film according to any one of [1] to [3] above, wherein in the spraying step, the water content of the corrosive dust is saturated.
[5] The accelerated deterioration test method for a coating film according to any one of [1] to [4] above, wherein the metal plate is a steel plate.
[6] The method for accelerated deterioration testing of a coating film according to any one of [1] to [5] above, wherein the spraying step, the wetting step, and the drying step are each carried out under the following conditions:
The spraying step: temperature 25 to 60°C, time 8 to 16 hours
The above-mentioned wetting step: temperature 40 to 60°C, relative humidity 90 to 100%, time 8 to 16 hours
The drying process: temperature 50 to 70°C, relative humidity 45 to 55%, time 20 to 28 hours
[7] The method for accelerated deterioration testing of a coating film according to any one of [1] to [6] above, wherein the spraying step, the wetting step, and the drying step are each carried out under the following conditions:
The spraying step: temperature 35°C, time 12 hours
Wetting step: temperature 50°C, relative humidity 95%, time 12 hours
Drying step: temperature 60°C, relative humidity 50%, time 24 hours
本発明によれば、腐食性ダスト環境下での塗膜の劣化を十分に再現できる。 The present invention makes it possible to fully reproduce the deterioration of coating films in a corrosive dust environment.
図１は、塗膜劣化促進試験に用いる試験機７を模式的に示す断面図である。
まず、試験機７の内部に配置される、試験ボックス１およびダスト受け２を説明する。
試験ボックス１は、上面が開口した容器であり、その底面には、貫通孔である水抜き孔６が形成されている。
試験ボックス１の素材は、例えば、ポリプロピレン等の樹脂である。図１に示す試験ボックス１は直方体状であるが、試験ボックス１の形状は、これに限定されない。
FIG. 1 is a cross-sectional view that schematically shows a testing machine 7 used in the accelerated coating deterioration test.
First, the test box 1 and the dust pan 2 arranged inside the tester 7 will be described.
The test box 1 is a container with an open top, and a drain hole 6, which is a through hole, is formed in the bottom.
The material of the test box 1 is, for example, a resin such as polypropylene. The test box 1 shown in Fig. 1 has a rectangular parallelepiped shape, but the shape of the test box 1 is not limited to this.
ダスト受け２は、試験ボックス１と同様に、上面が開口した容器である。ただし、ダスト受け２の底面には、貫通孔が形成されていない。
ダスト受け２の素材、形状などは、試験ボックス１と同じであってもよい。図１に示すダスト受け２は、試験ボックス１と同じ形状である。
The dust receiver 2 is a container with an open top, similar to the test box 1. However, the dust receiver 2 does not have a through-hole formed in the bottom surface.
The material, shape, etc. of the dust pan 2 may be the same as those of the test box 1. The dust pan 2 shown in FIG.
より詳細には、図１に示すように、まず、試験機７の内部の底面上に、ダスト受け２を配置し、その上に、試験ボックス１を重ねる。次いで、試験ボックス１の底面上に、網５を載せる。網５の素材は、例えば、ポリプロピレン等の樹脂である。
網５の上に、ダスト４の一部を、床敷材として敷き詰める。次いで、床敷材（ダスト４）の上に、試験片３を配置する。その後、残りのダスト４を、試験ボックス１の内部に装入して、試験片３を覆う。こうして、試験ボックス１の内部に、試験片３が埋設した状態で、ダスト４が収容される。
1, first, the dust tray 2 is placed on the bottom surface inside the tester 7, and the test box 1 is placed on top of that. Next, the net 5 is placed on the bottom surface of the test box 1. The net 5 is made of a resin such as polypropylene.
A portion of the dust 4 is spread on top of the net 5 as bedding. Next, the test specimen 3 is placed on top of the bedding (dust 4). After that, the remaining dust 4 is placed inside the test box 1 to cover the test specimen 3. In this way, the dust 4 is contained inside the test box 1 with the test specimen 3 buried inside.
ダスト４は、硫黄成分などの腐食成分を含有する腐食性ダストであり、例えば、製鉄所において、粗鋼を生産するためにベルトコンベアを用いて運搬される、鉱石、石炭、コークス等の原料に由来する。
具体的には、これらの原料のうち、運搬の際にベルトから落下してベルトコンベア等の躯体（フレーム）上に堆積したものを、腐食性ダストとして用いればよい。
例えば、コークスに由来するダスト（コークスダスト）は、腐食成分として硫黄成分を含有する。
The dust 4 is corrosive dust containing corrosive components such as sulfur components, and originates from raw materials such as ore, coal, and coke that are transported using conveyor belts in steel mills to produce crude steel.
Specifically, among these raw materials, those that fall off the belt during transportation and accumulate on the frame of the belt conveyor or the like can be used as the corrosive dust.
For example, dust derived from coke (coke dust) contains sulfur components as corrosive components.
試験片３は、ベルトコンベア等の躯体を構成する部材の一部を想定したものであり、金属板と、その表面（片面または両面）に配置された塗膜とを有する。
金属板としては、例えば、躯体に用いられる従来公知の鋼板が挙げられ、その具体例としては、ＳＳ材（一般構造用圧延鋼材）、ＳＭ材（溶接構造用圧延鋼材）などの低炭素鋼板が挙げられる。これらの低炭素鋼板と成分組成がほぼ同等であるＳＰＣＣ材（冷間圧延鋼板）を用いてもよい。
塗膜となる塗料としては、例えば、変性エポキシ樹脂塗料、ポリウレタン樹脂塗料、シリコーン樹脂塗料、有機系ジンクリッチペイント、無機系ジンクリッチペイント等の従来公知の塗料が適宜用いられ、市販品を用いてもよい。
塗膜は、２種以上の塗料を順次塗布して形成される複数層の塗膜であってもよい。
塗膜の厚さ（膜厚）は、例えば、１００～４００μｍであるが、これに限定されない。
The test piece 3 is intended to be a part of a member constituting the frame of a belt conveyor or the like, and has a metal plate and a coating film disposed on its surface (one side or both sides).
Examples of the metal plate include conventionally known steel plates used for the frame, and specific examples thereof include low-carbon steel plates such as SS material (rolled steel for general structure) and SM material (rolled steel for welded structure). SPCC material (cold-rolled steel plate), which has a chemical composition similar to that of these low-carbon steel plates, may also be used.
As the paint to be applied to the coating film, for example, a conventionally known paint such as a modified epoxy resin paint, a polyurethane resin paint, a silicone resin paint, an organic zinc-rich paint, or an inorganic zinc-rich paint may be appropriately used, and commercially available products may also be used.
The coating film may be a multi-layer coating film formed by sequentially applying two or more types of coating material.
The thickness of the coating film (film thickness) is, for example, 100 to 400 μm, but is not limited to this.
ところで、試験ボックス１の底面には、貫通孔である水抜き孔６が形成されているため、試験ボックス１の内部に収容されたダスト４は、水抜き孔６から落下し得る。
しかし、試験ボックス１の底面上には、網５が配置されているため、網５によって、ダスト４の落下が防止される。このため、網５の網目は、ダスト４が通過しにくいサイズおよび形状を、適宜選択することが好ましい。
The test box 1 has a drain hole 6 formed in the bottom thereof, which is a through hole, so that the dust 4 contained inside the test box 1 can fall through the drain hole 6 .
However, since a net 5 is placed on the bottom surface of the test box 1, the dust 4 is prevented from falling by the net 5. For this reason, it is preferable to appropriately select the size and shape of the mesh of the net 5 so that the dust 4 cannot easily pass through.
試験機７の内部の上面側には、噴霧設備８が設けられている。噴霧設備８は、下方に向けて、水９を噴霧する。水９としては、塩水ではなく、純水を用いる。
試験機７は、噴霧設備８を駆動でき、かつ、内部の温度および湿度などの条件を適宜変更できればよく、例えば、ＪＩＳ Ｋ ５６００－７－９に準拠する試験機（ＣＣＴ試験機など）を用いてもよい。
A spraying device 8 is provided on the upper surface side inside the testing machine 7. The spraying device 8 sprays water 9 downward. Pure water, not salt water, is used as the water 9.
The tester 7 may be any tester that can drive the spraying equipment 8 and can appropriately change the internal conditions such as temperature and humidity, and may be, for example, a tester (such as a CCT tester) that complies with JIS K 5600-7-9.
このような構成において、塗膜劣化促進試験を実施するには、まず、上述したように、試験ボックス１に収容されたダスト４に、試験片３を埋設して、試験片３の塗膜とダスト４と接触させる（埋設工程）。 To conduct an accelerated coating deterioration test using this configuration, first, as described above, the test piece 3 is embedded in the dust 4 contained in the test box 1, so that the coating on the test piece 3 comes into contact with the dust 4 (embedding process).
この状態で、試験機７の噴霧設備８を駆動して、試験ボックス１に収容されたダスト４に水９を噴霧し、ダスト４に水分を含ませる（噴霧工程）。
噴霧工程では、ダスト４の含水率が飽和するまで、ダスト４に水分を含ませることが好ましい。なお、噴霧工程では、ダスト４だけでなく、試験片３の塗膜にも、水分を含ませてもよい。ダスト４などに吸収されなかった余分な水９は、試験ボックス１の底面に形成された水抜き孔６を通過して、ダスト受け２に落下する。
In this state, the spraying equipment 8 of the tester 7 is driven to spray water 9 onto the dust 4 contained in the test box 1, thereby absorbing moisture into the dust 4 (spraying step).
In the spraying step, it is preferable to moisten the dust 4 until the moisture content of the dust 4 reaches saturation. Note that in the spraying step, not only the dust 4 but also the coating film of the test piece 3 may be moistened. Excess water 9 that is not absorbed by the dust 4 passes through drainage holes 6 formed in the bottom surface of the test box 1 and falls into the dust receiver 2.
更に、試験機７の内部（すなわち、試験片３およびダスト４）の温度を、室温（例えば２５℃）よりも上昇させて、ダスト４の水分を試験片３の塗膜に吸収させ、この吸収を促進する（湿潤工程）。
噴霧工程と湿潤工程とは、同じ工程であってもよい。
その後、試験片３（特に塗膜）およびダスト４を乾燥する（乾燥工程）。
Furthermore, the temperature inside the testing machine 7 (i.e., the test piece 3 and the dust 4) is raised above room temperature (e.g., 25°C) to cause the moisture in the dust 4 to be absorbed into the coating film of the test piece 3 and promote this absorption (wetting step).
The spraying step and the wetting step may be the same step.
Thereafter, the test piece 3 (particularly the coating film) and the dust 4 are dried (drying step).
ここで、噴霧工程、湿潤工程および乾燥工程を実施する理由について説明する。 Here, we will explain why we perform the spraying, wetting, and drying processes.
まず、降水量＞０ｍｍ／ｈまたは相対湿度（ＲＨ）＞８０％の環境を「濡れ」環境と定義する。一方、濡れ環境を満たさない環境を「乾燥」環境と定義する。
試験片の塗膜は、濡れ環境では吸水し、乾燥環境では乾燥される。
First, an environment with precipitation >0 mm/h or relative humidity (RH) >80% is defined as a "wet" environment, while an environment that does not meet the wet condition is defined as a "dry" environment.
The coating on the test specimen absorbs water in a wet environment and dries in a dry environment.
本発明者らは、塗膜を水に接触させた状態で恒温恒湿槽に入れ、濡れ環境および乾燥環境において、各温度での塗膜質量の経時的な変化を測定し、塗膜の含水率を求めた。更に、下記式に基づいて、塗膜の拡散係数Ｄ（単位：ｍ２／ｓ）を求めた。
（Ｍｔ／Ｍ∞）＝（４／Ｌ）×（Ｄｔ／π）２
ｔ：経過時間（単位：ｓ）
Ｍｔ：経過時間ｔでの塗膜の含水率
Ｍ∞：塗膜の飽和含水率
Ｌ：塗膜の厚さ（単位：ｍ）
Ｄ：拡散係数（単位：ｍ／ｓ２）
The present inventors placed the coating film in contact with water in a thermo-hygrostat, measured the change in coating mass over time at each temperature in a wet environment and a dry environment, and calculated the water content of the coating film. Furthermore, the diffusion coefficient D (unit: m2 /s) of the coating film was calculated based on the following formula:
(M t /M ∞ )=(4/L)×(Dt/π) 2
t: elapsed time (unit: s)
Mt : Moisture content of the coating film at elapsed time t M∞ : Saturated moisture content of the coating film L: Thickness of the coating film (unit: m)
D: Diffusion coefficient (unit: m/s 2 )
図２は、塗膜の拡散係数と温度との関係を示すグラフである。
図２に示すように、塗膜が吸水する場合も、塗膜が乾燥される場合も、温度が上昇するに伴い、拡散係数が増加している。同じ温度どうしで比べると、拡散係数は、塗膜が乾燥される場合の方が、塗膜が吸水する場合よりも大きい傾向にある。
塗膜が吸水する場合、水分子は、高分子体からなる塗膜の高分子網を進展させながら、塗膜の内部に進入するため、拡散係数は相対的に小さいと考えられる。一方、塗膜が乾燥される場合は、進展された高分子網から水分子が排出されるため、拡散係数は相対的に大きいと考えられる。
このような拡散係数の差を踏まえると、吸水の挙動は、濡れ環境が連続する時間（連続濡れ時間）に大きく影響されることが分かる。
FIG. 2 is a graph showing the relationship between the diffusion coefficient of the coating film and the temperature.
As shown in Figure 2, the diffusion coefficient increases with increasing temperature, both when the coating film absorbs water and when the coating film is drying. When comparing at the same temperature, the diffusion coefficient tends to be larger when the coating film is drying than when the coating film absorbs water.
When a coating film absorbs water, the water molecules penetrate into the coating film while expanding the polymer network of the coating film, which is made of polymers, and the diffusion coefficient is thought to be relatively small.On the other hand, when a coating film dries, the water molecules are expelled from the expanded polymer network, and the diffusion coefficient is thought to be relatively large.
Considering this difference in diffusion coefficient, it is clear that the water absorption behavior is greatly affected by the duration of the continuous wet environment (continuous wetting time).
実環境での連続濡れ時間は、２４～４８ｈが多い。そこで、実環境を再現する観点から、ダストに埋設した試験片を、下記条件を満たす濡れ環境に曝露し、その後、下記条件を満たす乾燥環境に曝露する試験（吸水乾燥挙動テスト）を実施した。
・濡れ環境：温度２５℃、相対湿度９５％、時間４８ｈ
・乾燥環境：温度３０℃、相対湿度６０％、時間１２０ｈ
In actual environments, the continuous wetting time is often 24 to 48 hours. Therefore, in order to reproduce the actual environment, a test (water absorption and drying behavior test) was conducted in which test specimens buried in dust were exposed to a wet environment that met the following conditions, and then exposed to a dry environment that met the following conditions.
- Wet environment: temperature 25°C, relative humidity 95%, time 48 hours
Dry environment: temperature 30°C, relative humidity 60%, time 120 hours
図３は、吸水乾燥挙動テストの結果を示すグラフである。横軸が経過時間（単位：ｈ）、縦軸が塗膜およびダストの水分飽和率を示す。水分飽和率は、飽和含水量に対する各経過時間での含水量の割合である。
吸水乾燥挙動テストにおいては、まず、濡れ環境の開始時点で、試験片が埋設されたダストに給水した。コークスを搬送するベルトコンベアの躯体に堆積するダストを想定して、ダストの層さを、３５ｍｍとした。
濡れ環境では、塗膜だけでなく、ダストも吸水する。このため、図３に示すように、乾燥環境に移行してからも、ある経過時間までは、ダストの水分を塗膜が吸収するため、塗膜の吸水が進む（塗膜の水分飽和率が上昇する）ことが分かる。
Figure 3 is a graph showing the results of the water absorption and drying behavior test. The horizontal axis shows the elapsed time (unit: h), and the vertical axis shows the moisture saturation rate of the coating film and dust. The moisture saturation rate is the ratio of the moisture content at each elapsed time to the saturated moisture content.
In the water absorption and drying behavior test, water was first supplied to the dust in which the test specimens were embedded at the start of the wet environment. The dust layer thickness was set to 35 mm, simulating the dust that accumulates on the body of a belt conveyor transporting coke.
In a wet environment, not only the coating film but also the dust absorbs water. As a result, as shown in Figure 3, even after the environment is changed to a dry environment, the coating film continues to absorb the moisture from the dust, and the coating film continues to absorb water (the moisture saturation rate of the coating film increases) for a certain period of time.
このような塗膜の拡散係数と温度との関係（図２）および吸水乾燥挙動テストの結果（図３）を踏まえて、本発明者らは、上述した噴霧工程、湿潤工程および乾燥工程を実施することを想到した。
これらの工程を実施することにより、実環境における塗膜およびダストの吸水乾燥挙動が再現されるので、実環境と高い相関を有しつつ、短時間で、腐食性ダスト環境下での塗膜の劣化を十分に再現できる。
Based on the relationship between the diffusion coefficient of the coating film and temperature (FIG. 2) and the results of the water absorption and drying behavior test (FIG. 3), the present inventors came up with the idea of carrying out the above-mentioned spraying step, wetting step, and drying step.
By carrying out these steps, the water absorption and drying behavior of the coating film and dust in a real environment can be reproduced, making it possible to sufficiently reproduce the deterioration of the coating film in a corrosive dust environment in a short period of time while having a high correlation with the real environment.
噴霧工程、湿潤工程および乾燥工程について、温度、湿度、時間などの条件は、塗膜の特性などに基づいて適宜設定されるが、それぞれ、下記条件で実施することが好ましい。これにより、腐食性ダスト環境下での塗膜の劣化をより十分に再現できる（後述する［実施例］を参照）。 The conditions for the spraying, wetting, and drying processes, such as temperature, humidity, and time, are set appropriately based on the properties of the coating film, but it is preferable to carry out each process under the conditions listed below. This allows for more accurate reproduction of the deterioration of the coating film in a corrosive dust environment (see the Examples section below).
噴霧工程の温度は、２５～６０℃が好ましく、３０～４０℃がより好ましく、３５℃が更に好ましい。噴霧工程の時間は、８～１６ｈが好ましく、１０～１４ｈがより好ましく、１２ｈが更に好ましい。
湿潤工程の温度は、４０～６０℃が好ましく、４５～５５℃がより好ましく、５０℃が更に好ましい。湿潤工程の相対湿度は、９０～１００％が好ましく、９３～９８％がより好ましく、９５％が更に好ましい。湿潤工程の時間は、８～１６ｈが好ましく、１０～１４ｈがより好ましく、１２ｈが更に好ましい。
乾燥工程の温度は、５０～７０℃が好ましく、５５～６５℃がより好ましく、６０℃が更に好ましい。乾燥工程の相対湿度は、４５～５５％が好ましく、４８～５３％がより好ましく、５０％が更に好ましい。乾燥工程の時間は、２０～２８ｈが好ましく、２２～２６ｈがより好ましく、２４ｈが更に好ましい。
The temperature in the spraying step is preferably 25 to 60° C., more preferably 30 to 40° C., and even more preferably 35° C. The time for the spraying step is preferably 8 to 16 hours, more preferably 10 to 14 hours, and even more preferably 12 hours.
The temperature in the wetting step is preferably 40 to 60° C., more preferably 45 to 55° C., and even more preferably 50° C. The relative humidity in the wetting step is preferably 90 to 100%, more preferably 93 to 98%, and even more preferably 95%. The duration of the wetting step is preferably 8 to 16 hours, more preferably 10 to 14 hours, and even more preferably 12 hours.
The temperature in the drying step is preferably 50 to 70° C., more preferably 55 to 65° C., and even more preferably 60° C. The relative humidity in the drying step is preferably 45 to 55%, more preferably 48 to 53%, and even more preferably 50%. The time for the drying step is preferably 20 to 28 hours, more preferably 22 to 26 hours, and even more preferably 24 hours.
以下に、実施例を挙げて本発明を具体的に説明する。ただし、本発明は、以下に説明する実施例に限定されない。 The present invention will be specifically explained below using examples. However, the present invention is not limited to the examples described below.
まず、ダストおよび試験片を準備した。
ダストとしては、硫黄成分を含有するコークスダストを用いた。
試験片の金属板としては、鋼板（冷延鋼板）であるブラスト処理を施したＳＰＣＣ材を用いた。この鋼板に、下記表１に示す塗料を塗布して、塗膜を形成し、基準仕様および仕様１～３の試験片を得た。
試験片は、後述する試験に供する前に、加工して、人工欠陥を付与した。
First, the dust and test specimens were prepared.
As the dust, coke dust containing sulfur components was used.
The metal plate used for the test specimens was a steel plate (cold-rolled steel plate) made of SPCC material that had been subjected to blasting treatment. The paints shown in Table 1 below were applied to this steel plate to form coatings, and test specimens of the standard specification and specifications 1 to 3 were obtained.
The test specimens were processed to have artificial defects before being subjected to the tests described below.
図１に基づいて説明した試験機（ＪＩＳ Ｋ ５６００－７－９に準拠した試験機）を用いて、塗膜劣化促進試験を実施した。
すなわち、試験片をダストに埋設した状態で、噴霧設備から純水を噴霧した（噴霧工程）。次いで、試験機の内部の温度を上昇させて、ダストの水分を塗膜が吸収することを促進した（湿潤工程）。その後、試験片およびダストを乾燥した（乾燥工程）。
噴霧工程、湿潤工程および乾燥工程は、下記条件で実施した。
・噴霧工程：温度３５℃、時間１２ｈ
・湿潤工程：温度５０℃、相対湿度９５％、時間１２ｈ
・乾燥工程：温度６０℃、相対湿度５０％、時間２４ｈ
噴霧工程の時間を短縮するため、ダストの厚さは１０ｍｍとした。噴霧工程では、純水の噴霧量を３±１ｍＬ／ｈ／８０ｃｍ２とし、ダストの含水率が飽和するまで純水を噴霧した。
The coating deterioration accelerated test was carried out using the test machine (test machine conforming to JIS K 5600-7-9) explained based on FIG.
Specifically, pure water was sprayed onto the test specimen buried in dust (spraying process). The temperature inside the tester was then raised to promote the absorption of moisture from the dust into the coating (wetting process). After that, the test specimen and dust were dried (drying process).
The spraying step, wetting step and drying step were carried out under the following conditions.
・Spraying process: Temperature 35℃, time 12 hours
Wetting process: temperature 50°C, relative humidity 95%, time 12 hours
Drying process: temperature 60°C, relative humidity 50%, time 24 hours
In order to shorten the time for the spraying process, the thickness of the dust was set to 10 mm. In the spraying process, the amount of pure water sprayed was set to 3±1 mL/h/80 cm2, and pure water was sprayed until the moisture content of the dust reached saturation.
上述した塗膜劣化促進試験とは別に、試験片をダスト（厚さ：３５ｍｍ）に埋設した状態で、実際の屋外に曝露する現地曝露試験も実施した。
試験後、試験片における人工欠陥の膨れ面積を計測した。基準仕様の膨れ面積に対する膨れ面積の割合を相対寿命として求めた。
図４は、基準使用および仕様１～３の試験片の相対寿命を示すグラフである。
図４に示すように、基準仕様および仕様１～３の相対寿命の大小関係は、実施例と現地曝露試験とでほぼ一致していた。すなわち、実施例の塗膜劣化促進試験では、実環境と高い相関を有しつつ、短時間で、腐食性ダスト環境下での塗膜の劣化を十分に再現できた。
In addition to the above-mentioned accelerated coating deterioration test, a field exposure test was also carried out in which the test specimens were buried in dust (thickness: 35 mm) and exposed to actual outdoor conditions.
After the test, the blister area of the artificial defect in the test piece was measured, and the ratio of the blister area to the blister area of the standard specification was calculated as the relative life.
FIG. 4 is a graph showing the relative lifespan of the standard use and specification 1-3 test specimens.
As shown in Figure 4, the relative lifespans of the standard specification and specifications 1 to 3 were almost identical between the example and the field exposure test. In other words, the accelerated coating degradation test of the example was able to sufficiently reproduce the degradation of the coating in a corrosive dust environment in a short period of time, while showing a high correlation with the actual environment.
１：試験ボックス
２：ダスト受け
３：試験片
４：ダスト（腐食性ダスト）
５：網
６：水抜き孔
７：試験機
８：噴霧設備
９：水
1: Test box 2: Dust receiver 3: Test piece 4: Dust (corrosive dust)
5: Net 6: Drainage hole 7: Testing machine 8: Spraying equipment 9: Water
Claims (7)
前記腐食性ダストに水を噴霧して、前記腐食性ダストに水分を含ませる噴霧工程と、
前記試験片および前記腐食性ダストの温度を上昇させて、前記腐食性ダストの水分を前記塗膜が吸収することを促進する湿潤工程と、
前記試験片および前記腐食性ダストを乾燥する乾燥工程と、
を備える、塗膜の劣化促進試験方法。 an embedding step of embedding a test piece having a coating film disposed on the surface of a metal plate in corrosive dust containing a corrosive component to bring the coating film into contact with the corrosive dust;
a spraying step of spraying water onto the corrosive dust to moisten the corrosive dust;
a wetting step of increasing the temperature of the test piece and the corrosive dust to promote absorption of moisture from the corrosive dust by the coating;
a drying step of drying the test piece and the corrosive dust;
A coating film deterioration accelerated test method comprising:
前記噴霧工程：温度２５～６０℃、時間８～１６ｈ
前記湿潤工程：温度４０～６０℃、相対湿度９０～１００％、時間８～１６ｈ
前記乾燥工程：温度５０～７０℃、相対湿度４５～５５％、時間２０～２８ｈ 3. The accelerated deterioration test method for a coating film according to claim 1, wherein the spraying step, the wetting step, and the drying step are each carried out under the following conditions:
The spraying step: temperature 25 to 60°C, time 8 to 16 hours
The moistening step: temperature 40 to 60°C, relative humidity 90 to 100%, time 8 to 16 hours
The drying step: temperature 50 to 70°C, relative humidity 45 to 55%, time 20 to 28 hours
前記噴霧工程：温度３５℃、時間１２ｈ
前記湿潤工程：温度５０℃、相対湿度９５％、時間１２ｈ
前記乾燥工程：温度６０℃、相対湿度５０％、時間２４ｈ 3. The accelerated deterioration test method for a coating film according to claim 1, wherein the spraying step, the wetting step, and the drying step are each carried out under the following conditions:
The spraying step: temperature 35°C, time 12 hours
Wetting step: temperature 50°C, relative humidity 95%, time 12 hours
Drying step: temperature 60°C, relative humidity 50%, time 24 hours
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