TWI515275B - Coating, anti-corrosion method and anti-corrosion steel plate - Google Patents

Description

Coating, anti-corrosion method and corrosion resistant steel sheet

This invention relates to a resist treatment, and more particularly to a coating, a resist method, and a resist steel sheet.

Steel sheet is a widely used material and is often used in automotive, home appliance or construction applications. In order to improve the corrosion resistance of the steel sheet during storage, transportation or use, the surface of the steel sheet is usually passivated by using chromate having hexavalent chromium to produce a resist film on the surface of the steel sheet. Passivation treatment with chromate can form a low-cost rare-soluble salt [such as chromium (III) hydroxide; (Cr(OH) ₃ )] on the surface of the steel sheet, thereby providing barrier protection for the steel sheet. )effect. On the other hand, since the hexavalent chromate has a high valence and high solubility, when the resist film formed of the chromate has defects such as cracks or scratches due to an external force, the resist film itself has self-healing ability ( Self-healing ability) to prevent the corrosion reaction from continuing. In addition, the passivation treatment of chromate is inexpensive, so it is suitable for use in industrial processes. However, hexavalent chromium is a toxic carcinogen, causing great harm to both human body and natural ecology. Moreover, the RoHS Directive issued in July 2006 and the OSHA3320-10N Directive, which came into effect in 2006, all explicitly limit the use of hexavalent chromium. Therefore, various non-chrome type passivation treatments need to be developed.

In the general non-chromium type passivation treatment, a phosphate-based treatment solution is used to passivate the steel sheet, or a phosphate-containing polymer resin is used as a passivation film for protecting the steel sheet. However, phosphates containing phosphorus also cause serious pollution to the environment. Therefore, in recent years, a method of coating the surface of a steel sheet with an organic decane compound has been developed to increase the corrosion resistance of the steel sheet.

U.S. Patent No. 5,545,080 and U.S. Patent Publication No. 5,498,481, which are mainly used to treat a cold-rolled steel sheet or an electrogalvanized steel sheet using a mixture comprising a thermosetting resin, a non-hydrolyzed organic decane coupling agent, and a pigment. Wherein, the melting point of the organic decane coupling agent is lower than the curing temperature of the thermosetting resin, so that when the thermosetting resin is hardened, the non-hydrolyzed organic decane coupling agent diffuses to the surface of the cold-rolled steel sheet or the electrogalvanized steel sheet to form a cross-linked layer, thereby increasing Corrosion resistance of cold rolled steel sheets or electrogalvanized steel sheets.

The Republic of China Invention Patent Application No. TW 89101625 treats steel sheets with a solution containing one or more hydrolyzed or partially hydrolyzed amino decanes to provide a long-term corrosion resistance of the steel sheets.

In the technique disclosed in the above-mentioned patent, various anticorrosive methods using an organic decane coupling agent are performed by immersing a steel sheet in a treatment liquid containing an organic decane coupling agent for passivation treatment. However, the passivation treatment by the immersion method is disadvantageous for industrial large-scale or continuous production, and the waste liquid recovery of the treatment liquid also increases the cost of the resist treatment. On the other hand, these treatment liquids have a solid content of only 2.7 wt% to 3.0 wt%, and thus cannot be applied to a roll coating operation which can be industrially produced in a large amount and continuously.

The Republic of China invention patent application No. TW100135279 and the Japanese Patent Publication No. JP2012092444 are made of a resin emulsion, a tetraalkoxy decane, a decane coupling agent having an active hydrogen, a chelating agent, a vanaic acid compound, a titanium compound and water, etc., and have corrosion resistance. Sex paint. However, such a coating has a high resin content and causes a problem of high temperature discoloration after the formation of a coating film.

In view of the above, there is a need to propose a coating, a resisting method, and a resist steel sheet to solve the problem that the passivation treatment using the organic decane coupling agent cannot be applied to the roll coating step and the high resin content of the coating causes high-temperature discoloration.

Accordingly, it is an object of the present invention to provide a coating having a solids content of from 24.00% to 36.00% by weight, which is suitable for use in a mass production process.

Another object of the present invention is to provide a coating which can increase corrosion resistance.

It is still another object of the present invention to provide a resist method comprising a siloxane compound, an acidic solution, and an organooxane compound, all in accordance with the RoHS Directive issued in July 2006 and the OSHA3320-effective in 2006. 10N instruction.

Still another object of the present invention is to provide a resist steel sheet having corrosion resistance, alkali wash corrosion resistance, electrical conductivity, coating adhesion, anti-blackening property, high temperature discoloration resistance, and self-healing ability in accordance with test standards.

According to the above object of the present invention, there is provided a coating comprising 36.51% by weight to 59.03% by weight of a oxoxane compound, more than 0% by weight and less than 41.41% by weight of an organic siloxane compound, and 22.08% by weight to 24.23% by weight. Acidic solution. Among them, the acidic solution hydrolyzed by oximation And an organic oxoxane compound.

According to an embodiment of the invention, the above-mentioned oxoxane compound comprises tetramethyl orthosilicate (TMOS), ethyltrimethoxysilane, tetraethoxy orthosilicate (TEOS), methyl three. Ethyltrimethoxysilane or ethyltriethoxysilane.

According to an embodiment of the invention, the organooxane compound comprises 3-glycidoxy propyl trimethoxy silane (GPTMS), 3-glycidyloxypropyl triethoxy decane (3-glycidoxy propyl trithoxy silane) or 3-glycidoxy propyl methyl dimethoxy silane.

According to an embodiment of the invention, the acidic solution comprises nitric acid, hydrochloric acid or acetic acid.

According to an embodiment of the invention, the acidic solution comprises an inorganic corrosion inhibitor.

According to an embodiment of the invention, the inorganic corrosion inhibitor comprises cerium nitrate, sodium molybdate or sodium vanadate.

According to an embodiment of the invention, the concentration of the inorganic corrosion inhibitor is from 21.25 mM to 212.5 mM.

According to an embodiment of the present invention, the coating material comprises 36.51% by weight to 59.03% by weight of a oxoxane compound, 16.74% by weight to less than 41.41% by weight of an organic siloxane compound, and 22.08% by weight to 24.23 by weight. % acidic solution.

According to another object of the present invention, a resist method is proposed which is suitable for use in a steel sheet. In the resist method of an embodiment, the following steps are included. The above coatings are provided. A coating step is performed to coat the coating on the steel sheet. The coating steel sheet is subjected to a baking step to form a coating film on the steel sheet, wherein the baking temperature of the baking step is 75 ° C to 121 ° C.

According to an embodiment of the invention, the steel sheet is a hot dip galvanized steel sheet.

According to an embodiment of the invention, the coating step is a roll coating step.

According to still another object of the present invention, a resist steel sheet comprising a steel sheet and a coating film is proposed. The coating film is applied to the steel sheet and contains the above coating.

According to an embodiment of the invention, the steel sheet is a hot dip galvanized steel sheet.

In the present invention, the steel sheet is mainly subjected to passivation treatment by using a siloxane compound, an organic siloxane compound, and an acidic solution, whereby the corrosion resistance, electrical conductivity, and coating adhesion of the steel sheet can be increased. Moreover, the components used in the coating do not contain chromium or phosphorus, so they do not cause serious harm to the human body or the environment. On the other hand, the solid content of the coating can be from 24.00% by weight to 36.00% by weight, so that it is applicable to a large number of industrially and continuously manufactured roll coating processes. In another aspect, the coating may further comprise an inorganic corrosion inhibitor in the acidic solution in addition to the oxoxane compound, the organic siloxane compound, and the acidic solution, so that the resist steel sheet has corrosion resistance and alkali washing according to the test standard. Corrosion resistance, electrical conductivity, coating adhesion, anti-blackening, high temperature discoloration and self-healing ability. Further, since the coating material of the present invention does not have a resin, there is no problem that the resin content is high and high-temperature discoloration occurs.

100‧‧‧ method

110, 120, 130‧ ‧ steps

200‧‧‧resist steel plate

210‧‧‧ steel plate

220‧‧·coating film

The above and other objects, features, advantages and embodiments of the present invention will become more <RTIgt; </ RTI> <RTIgt; </ RTI> <RTIgt; .

2 is a cross-sectional view showing a resist steel sheet according to an embodiment of the present invention.

The technical content, structural features, achieved goals and effects of the present invention will be described in detail below with reference to embodiments of the present invention.

In one embodiment of the present invention, the coating comprises 36.51% by weight to 59.03% by weight of a oxoxane compound, more than 0% by weight and less than 41.41% by weight of an organic oxoxane compound, and 22.08% by weight to 24.23% by weight of acidity. Solution.

In one example, the oxoxane compound may be a structure represented by the following formula (I): (R ¹ ) _a -Si-(OR ² ) _b (I) In the formula (I), R ¹ represents a carbon number of An alkyl group of 1 to 4, or an oxyalkyl group having a carbon number of 1 to 4; R ² represents an alkyl group having 1 to 4 carbon atoms; a is an integer of 0 to 1; and b is an integer of 3 to 4, and The sum of a and b is 4. In an exemplary embodiment, the oxoxane compound may comprise tetramethoxynonane, ethyltrimethoxydecane, tetraethoxydecane, methyltriethoxydecane or ethyltriethoxydecane.

In one example, the organooxane compound may be a structure represented by the following formula (II): R ³ -(CH ₂ ) _m -X-(CH ₂ ) _n -Si-(OR ⁴ ) ₂ (R ⁵ ) (II) In the formula (II), R ³ represents an alkyl group having 1 to 4 carbon atoms, or an alkenyl group having 1 to 4 carbon atoms, an amine group or an epoxy group; and R ⁴ represents a carbon number of 1 to 4 Alkyl; R ⁵ represents an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms; X is -CH ₂ - or -O-; m is an integer of 0 or 1; It is an integer from 0 to 3. In an exemplary embodiment, the organooxane compound may comprise 3-glycidyloxypropyltrimethoxydecane, 3-glycidyloxypropyltriethoxydecane or 3-glycidyloxypropylmethyl Dimethyl decane.

The acidic solution is required to have a hydrolyzable siloxane compound and a hydrolyzable organic siloxane compound. In one example, the acidic solution comprises nitric acid, hydrochloric acid or acetic acid. In an exemplary embodiment, nitric acid can reduce the time required to hydrolyze the siloxane compound to reduce manufacturing costs. In another example, the acidic solution has a pH of less than or equal to 5 to provide a preferred acid catalyst effect.

The oxoxane compound hydrolyzed by the acidic solution may have the structure represented by the following formula (III): (R ⁶ ) _a -Si-(OR ⁷ ) _b (III) in the formula (III), and R ⁶ represents the carbon number An alkyl or alcohol group of 1 to 4; and R ⁷ represents a hydrogen group.

The organooxane compound hydrolyzed by the acidic solution may have the structure represented by the following formula (IV): R ³ -(CH ₂ ) _m -X-(CH ₂ ) _n -Si-(OH) ₂ (R ⁸ ) (IV) In the formula (IV), R ⁸ represents an alkyl group or a hydroxyl group having a carbon number of 1 to 4.

In one example, the acidic solution also contains an inorganic corrosion inhibitor. One In an exemplary embodiment, the inorganic corrosion inhibitor comprises cerium nitrate, sodium molybdate or sodium vanadate. In another exemplary embodiment, the concentration of the inorganic corrosion inhibitor is from 21.25 mM to 212.5 mM.

Hereinafter, a method of preparing a coating material according to an embodiment of the present invention will be described. First, the oxoxane compound, the organic siloxane compound and the acidic solution are uniformly mixed in an environment of 20 ° C to 40 ° C for 0.5 hours to 48 hours to hydrolyze the oxoxane compound and the organic siloxane compound, the acidic solution, The coating of the examples of the invention was prepared. After testing, the coating of the present embodiment can have a solid content of 24.00 wt% to 36.00 wt%, which is suitable for a roll coating step which can be industrially produced in large quantities and continuously, and thus can be applied to a mass production process.

Please refer to FIG. 1. FIG. 1 is a flow chart showing a resist method 100 according to an embodiment of the invention. In one example, the resist method 100 can be applied to a steel sheet. In an exemplary embodiment, the steel sheet is a hot dip galvanized steel sheet. When the resist method 100 is implemented, a coating, such as the coating of the above examples, may be provided as described in step 110. The ingredients relating to this coating and the manner in which it is prepared have been described in detail in the preceding paragraphs and will not be further described herein. Next, a coating step 120 is performed, and the coating is applied to the surface of the steel sheet. In one example, the coating step 120 is a roll coating step. Thereafter, the coated steel sheet is subjected to a baking step 130 to form a coating film on the steel sheet. In some embodiments, the baking temperature of the baking step 130 is from 75 ° C to 121 ° C. In one example, the baking temperature is from 93 °C to 110 °C. In summary, the resist method 100 is mainly formed by applying the coating of the step 120 and baking of the step 130 to form a coating film having a resist effect on the surface of the steel sheet.

Thus, it can be seen that the resist method 100 of an embodiment of the present invention is used. The coating contains a siloxane compound, an acidic solution, and an organic siloxane compound, and does not contain hexavalent chromium and phosphorus components harmful to the human body and the environment, so the resist steel sheet obtained by the resist method 100 conforms to July 2006. The RoHS Directive and the OSHA3320-10N Directive, which came into effect in 2006.

Referring to FIG. 2, FIG. 2 is a cross-sectional view showing a resist steel sheet 200 according to an embodiment of the present invention. The steel sheet 200 includes a steel sheet 210 and a coating film 220. In an example, the steel sheet 210 may be a hot dip galvanized steel sheet. The coating film 220 is coated on the steel sheet 210, and the coating film 220 is formed using the coating material of the embodiment of the present invention. The composition of the coating of the embodiment of the present invention and the preparation method thereof are described in detail in the foregoing paragraphs, and thus will not be described again.

Several examples and comparative examples are listed below, thereby demonstrating that the resist steel sheet according to the embodiment of the present invention does have corrosion resistance, alkali-washing resistance, electrical conductivity, coating adhesion, anti-blackening property, and anti-corrosion according to the test standard. High temperature discoloration and self healing ability.

In the first embodiment, a hot dip galvanized steel sheet (for example, manufactured by China Iron and Steel Co., Ltd.) and a coating material are provided, wherein the coating material comprises 36.51 wt% of tetraethoxydecane and 41.41 wt% of 3-glycidyloxypropyltrimethoxy. Base decane (hereinafter referred to as GPTMS) and 22.08% by weight of an acidic solution (pH 1). Thereafter, the surface of the hot dip galvanized steel sheet is subjected to degreasing and decontamination treatment. Next, the coating was applied to the surface of the hot dip galvanized steel sheet by a roll coating bar. Next, the hot-dip galvanized steel sheet coated with the coating was continuously baked at a baking temperature of 100 ° C for 12 seconds, and the test piece of Example 1 was completed.

The preparation methods of Examples 2 to 7 are similar to Example 1, except that Examples 2 to 7 differ from Example 1 in that Examples 2 to 7 are used differently. Coating composition. Please refer to the table below for detailed coating composition.

In Comparative Example 1, only a hot-dip galvanized steel sheet which had been subjected to degreasing and decontamination treatment was provided as a test piece, that is, the test piece of Comparative Example 1 was a hot-dip galvanized steel sheet which was not subjected to a resist treatment.

The coating composition used in Comparative Example 2 does not contain GPTMS, and the detailed coating composition is as shown in Table 1 above.

A plurality of tests were performed on Examples 1 to 7 and Comparative Examples 1 and 2, and the test items were as follows.

The corrosion resistance tests were performed on Examples 1 to 7 and Comparative Examples 1 and 2, and the corrosion resistance test was carried out by ASTM B117-03 standard test method, and Examples 1 to 7 and Comparative Example 1 were evaluated visually. 2 test the rust area of the test piece. The time at which the rust area of the test piece was not more than 5% of the total surface area of the test piece was visually observed. Please refer to Table 1 above for the test results.

Conductivity tests were performed on Examples 1 to 7 and Comparative Examples 1 and 2. When the conductivity test was performed, the test pieces of Examples 1 to 7 and Comparative Examples 1 and 2 were cut so that the length, width, and thickness of the test pieces were 150 mm, 100 mm, and 1 mm, respectively. Next, a surface resistance meter (for example, a Loresta resistance meter supplied by Mitsubishi Corporation, Japan) was used to randomly measure the resistance values of the three test pieces, and the average value of the resistance values at the three places was calculated. If the average value is less than or equal to 10 ^-3 Ω, it is judged that the conductivity is good, and it is marked as "○"; and if the average value is more than 10 ^-3 Ω, it is judged that the conductivity is not good, and it is marked as "x". Please refer to the above table 1 for the test results.

Coating adhesion tests were performed on Examples 1 to 7 and Comparative Examples 1 and 2. The coating adhesion test is based on the ASTM D3359-97 standard test method. The approximate test procedure is as follows. First apply acrylic paint resin to the real The test pieces of Examples 1 to 7 and Comparative Examples 1 and 2 were placed. After the acrylic paint resin is dried, 11 scratches are scraped on the test piece with a hundred-square knife, and then another 11 scratches are scraped on the test piece in the direction of the 90-degree angle with the previous scratch mark. The film on the test piece was cut into 100 square films. Next, a 25 mm scotch tape was attached to the test piece, and the scotch tape was quickly peeled off, and the degree of peeling of the film on the test piece was visually observed. If the edge of the checker film is smooth and does not fall off, according to the ASTM D3359-97 standard test method, it can be judged that the test piece has a grade of 5B, and is marked as "○". If the edge of the checker film has a small part peeled off, and the damaged area of the checker film is less than or equal to 5% of the total area of the checker film, according to the ASTM D3359-97 standard test method, the test piece can be judged to have a grade of 4B. It is marked as "△". If the edge of the checker film falls off and the damage area of the checker film is greater than 5% of the total area of the checker film, according to the ASTM D3359-97 standard test method, the test piece can be judged to have a grade of 3B or less. It is marked as "X". Please refer to the above table 1 for the test results.

The alkali wash corrosion resistance tests were carried out on Examples 4 to 7. The test pieces of Examples 4 to 7 were immersed in a commercial alkali washing solution of about 65 ° C for about 2 minutes. The rust areas of the test pieces of Examples 4 to 7 were evaluated visually after 24 hours using the ASTM B117-03 standard test method. The smaller the rust area, the better the corrosion resistance. Wherein, if the rust area of the test piece is less than or equal to 5% of the total surface area of the test piece, it is judged to have alkali washing corrosion resistance, and is marked as "○". If the rust area is greater than 5% of the total surface area of the test piece, it is judged that it has no alkali wash corrosion resistance and is marked as "x". Please refer to Table 1 above for the test results.

Examples 4 to 7 were tested for resistance to high temperature discoloration. The test pieces of Examples 4 to 7 were baked in an oven at a temperature of about 450 ° C for about 5 minutes. After the baking was completed, the surface of each test piece was visually observed for discoloration. If the surface is not discolored, it is judged to have high temperature discoloration resistance and is marked as "○". If the surface is discolored, it is judged that it does not have high temperature discoloration resistance and is marked as "x".

Examples 4 to 7 were tested for resistance to blackening. The test pieces of Examples 4 to 7 were placed in a constant temperature and humidity chamber at a temperature of about 50 ° C and a humidity of about 98% for about 10 days, and then a color difference meter (for example, Spectrophotometer CM-2600D supplied by Konica Minolta, Japan). The color difference meter detects the black-and-white discoloration (ie, |ΔL|) of each test piece. If |ΔL|<10, it is judged to have anti-blackening property, and it is marked as "○"; and if |ΔL|≧10, it is judged that it does not have anti-blackening property, and it is marked as "x".

Examples 4 to 7 were tested for self-healing ability. When the self-healing ability test was performed, the test pieces of Examples 4 to 7 were cut, respectively, so that the length, width, and thickness of the test pieces were 150 mm, 100 mm, and 1 mm, respectively. The end portions and the rear side portions of each test piece are sealed with anti-plating tape, and then each test piece is cut with a sharp knife to seal the front side portion without the anti-plating tape, so that the front side portion is formed into a "x" type scratch damage area. And the scratched area of the scratch needs to penetrate into the steel plate under the zinc layer, and the width of the scratch is about 100 micrometers. Thereafter, the rust lengths of the test pieces of Examples 4 to 7 were evaluated visually after 24 hours using the ASTM B117-03 standard test method. If the rust length of the test piece is less than 5% of the total scratch length of the test piece, it is judged to have self-healing ability and is marked as "○". If the test piece is rusted 5% or more of the total scratch length of the test piece and less than 50% of the total scratch length of the test piece, and also determined to have self-healing ability, marked as "△" and if the test piece has a rust length of 50% or more. The total scratch length of the test piece is judged as having no self-healing ability and is marked as "X". Please refer to Table 1 above for the test results.

As shown in the above Table 1, although Examples 1 to 7 and Comparative Examples 1 and 2 both passed the tests of conductivity and coating adhesion. However, for the test results of the corrosion resistance, it was found that the corrosion resistance of Comparative Example 1 was remarkably poor. Although Comparative Example 2 was able to pass the 24-hour corrosion resistance test, the corrosion resistance was still inferior to the test pieces of Examples 1 to 7. Therefore, it can be confirmed that the resist steel sheet of the embodiment of the present invention does not only meet the corrosion resistance, coating adhesion and conductivity of the test standard, but also further increases the resistance of the resist steel sheet by adding an organic siloxane compound to the coating. Corrosive.

On the other hand, Examples 4 to 7 all passed the tests of corrosion resistance, alkali-washing corrosion resistance, electrical conductivity, coating adhesion, anti-blackening property, and high-temperature discoloration resistance, and thus the resist steel sheet of the embodiment of the present invention It does avoid the problem of high temperature discoloration. It is worth mentioning that Examples 5 to 7 also passed the test of self-healing ability. This is because in the test pieces of Examples 5 to 7, the composition of the coating further contained an inorganic corrosion inhibitor of cerium nitrate. In addition, when the concentration of cerium nitrate is higher, the corrosion resistance of the test piece is also increased. In summary, the addition of the inorganic corrosion inhibitor not only allows Examples 5 to 7 to have self-healing ability, but also enhances the corrosion resistance of the test piece by increasing the concentration of the inorganic corrosion inhibitor.

Although the present invention has been disclosed in the above embodiments, it is not used The invention is defined by the general knowledge of the present invention, and various modifications and refinements can be made without departing from the spirit and scope of the invention. The scope is defined.

100‧‧‧ method

110, 120, 130‧ ‧ steps

Claims (10)

A coating comprising: 36.51% by weight to 59.03% by weight of a oxoxane compound, wherein the siloxane compound is selected from the group consisting of ethyltrimethoxydecane, methyltriethoxydecane or ethyltriethoxy. a group consisting of decane; greater than 0% by weight and less than 41.41% by weight of an organooxane compound, wherein the organomethoxyalkane compound comprises 3-glycidyloxypropyltrimethoxydecane, 3-glycidyl ether Oxypropyl triethoxy decane or 3-glycidyloxypropyl methyl dimethyl decane; and an acidic solution of 22.08% by weight to 24.23% by weight, wherein the acidic solution comprises nitric acid or hydrochloric acid, and the acidic solution hydrolyzes the A oxoxane compound and the organic siloxane compound. The coating of claim 1 wherein the acidic solution comprises an inorganic corrosion inhibitor. The coating of claim 2, wherein the inorganic corrosion inhibitor comprises cerium nitrate, sodium molybdate or sodium vanadate. The coating of claim 2, wherein the concentration of the inorganic corrosion inhibitor is from 21.25 mM to 212.5 mM. The coating material according to claim 1, comprising: 36.51% by weight to 59.03% by weight of a oxoxane compound; 16.74% by weight to less than 41.41% by weight of the organooxane compound; and 22.08% by weight to 24.23% by weight of the acidic solution. An anti-corrosion method for a steel sheet, the method comprising: providing a coating according to any one of claims 1 to 5; performing a coating step to coat the coating on the steel sheet; The steel sheet coated with the coating is subjected to a baking step to form a coating film on the steel sheet, wherein one of the baking steps is baked at a temperature of 75 ° C to 121 ° C. The method of resisting according to claim 6, wherein the steel sheet is a hot dip galvanized steel sheet. The method of resisting according to claim 6, wherein the coating step is a roll coating step. A resist steel sheet comprising: a steel sheet; and a coating film coated on the steel sheet and comprising the coating material according to any one of claims 1 to 5. The anti-corrosive steel sheet according to claim 9, wherein the steel sheet is a hot dip galvanized steel sheet.