WO2014068688A1

WO2014068688A1 - Surface modified metal member obtained using fluorine-containing silane coupling agent

Info

Publication number: WO2014068688A1
Application number: PCT/JP2012/078091
Authority: WO
Inventors: 勝美馬渕
Original assignee: 株式会社日立製作所
Priority date: 2012-10-31
Filing date: 2012-10-31
Publication date: 2014-05-08
Also published as: JPWO2014068688A1

Abstract

An organic layer, in which 6 or more C atoms are linearly bonded, is formed on a corrosion-resistant metal. Methods for that include: (1) a method wherein a silane coupling agent having alkoxy groups at both ends is reacted with a metal; (2) a method wherein an organic material having an OH group at one end and a group that is adsorptive to a metal on the other end is reacted with a metal; (3) a method wherein a compound having an OH group at one end and a COO group, which is adsorptive to a metal, on the other end is reacted with a metal; and (4) a method wherein a silane coupling agent having an alkoxy group at one end and a group that is adsorptive to a metal on the other end is reacted with a metal. A fluorine-containing silane coupling layer is formed on the organic layer. Corrosion of a metal is prevented by forming a fluorine-containing silane coupling layer on an intermediate layer that is formed of an organic material having 6 or more carbon atoms (continuously or discontinuously) in a straight chain.

Description

Surface-modified metal member using fluorine-containing silane coupling agent

The present invention relates to a surface-modified metal member that not only improves corrosion resistance by forming a layer containing fluorine on the metal surface, but also has a surface excellent in heat resistance, water resistance, slidability, and smoothness. .

Conventionally, as a corrosion-resistant surface treatment, an anticorrosion method using a silane coupling agent is known, and Patent Document 1 discloses a specific resin compound (A), a first to third amino group, and a fourth group. A cationic urethane resin (B) having at least one cationic functional group selected from ammonium bases, one or more silane coupling agents (C) having a specific reactive functional group, and a specific acid compound ( E) and a surface treatment agent containing a cationic urethane resin (B) and a silane coupling agent (C) within a predetermined range, and having excellent corrosion resistance, fingerprint resistance, and black resistance. A method for producing a non-chromium surface-treated steel sheet excellent in modification and paint adhesion is disclosed.
Further, Patent Document 2 discloses a method in which a water- and oil-repellent film having a fluorinated hydrocarbon group is chemically bonded to a surface of a base material by a hydrolysis reaction and a hydrolysis condensation reaction of a silane coupling containing fluorine. Is disclosed. In the method of Patent Document 2, the hydrolysis reaction is promoted with hydrochloric acid and an amine catalyst.
Further, Patent Document 3 discloses a method of forming a metal oxide layer between a fluorine-containing silane coupling layer and a base material in order to increase the bonding force between the fluorine silane coupling layer and the base material. Has been.
Metal materials used in various products are required not only to improve corrosion resistance, but also to provide surfaces with excellent heat resistance, solvent resistance, and slidability as needed. However, although these conventional techniques use a trivalent chromium chelate complex or vanadium compound, a self-healing property is low, but a corrosion resistance comparable to a chromate film is obtained, but a thick film of several microns is formed. When the thin film is applied to the thin film because the processing environment is a strong acidic region, the target metal disappears in the middle of the processing process, and even if it does not disappear, a thick product is deposited on the surface. There is a problem that the function of the conventional metal surface is lost.
In addition, the anticorrosion method using a silane coupling agent has not been satisfactory in terms of corrosion resistance, heat resistance, solvent resistance, slidability, and particularly corrosion resistance. Furthermore, since the organofunctional silane does not bind well to the metal surface, there is a problem that it is easily removed by rinsing or the like.

There is a method of forming a fluorine layer in order to give the surface water repellency. In order to form the fluorine layer, a silane coupling agent containing fluorine is used. On the other hand, the anticorrosion action by the silane coupling agent is superior in corrosion resistance when the main chain is longer. From this, it is considered that the corrosion resistance can be improved by treating with a fluorine-containing silane coupling agent having a long main chain because the water-repellent action is superimposed. However, such a compound does not dissolve in a solvent such as alcohol, but dissolves only in a fluorine-based solvent. When a fluorine-based solvent is used, there arises a problem that the adhesion with the metal layer is reduced.
Therefore, it has many problems regarding practical use. Therefore, a surface treatment agent and a surface treatment method that are comprehensively satisfactory are demanded.

JP 2007-291531 A Japanese Patent Laid-Open No. 11-158648 JP 2012-35411 A

An object of the present invention is to provide a surface-modified metal member having a surface excellent in heat resistance, solvent resistance, and slidability as well as improving corrosion resistance.

In the surface-modified metal member, an intermediate layer made of an organic material and a silane coupling layer containing fluorine are sequentially laminated on a metal substrate, and the intermediate layer includes at least carbon atoms continuously or discontinuously on a straight chain. 6 or more are connected.

In the method for modifying a surface modified metal member, the intermediate layer is formed of any one of the following (1) to (4) or a combination thereof: Quality method.

(1) A method of reacting a base metal with a silane coupling agent having alkoxy groups at both ends,
(2) A method of reacting an organic substance having an OH group at one end and a group capable of adsorbing with a metal at the opposite end with a base metal,
(3) a method of reacting a base metal with a compound having an OH group at one end and a COO group capable of adsorbing to the base metal at the opposite end;
(4) A method of reacting a base metal with a silane coupling agent having an alkoxy group at one end and a group capable of adsorbing to the base metal at the opposite end

According to the present invention, an intermediate layer having a long molecular main chain is formed as a first step on a metal material, an OH group is introduced on the surface thereof, and then a fluorine-containing silane coupling layer is formed as a second step. Thus, a surface having water repellency, excellent corrosion resistance, and a metal surface function as it is is provided.

The figure which shows the polarization curve measured in 3.5% NaCl solution regarding untreated Al. The figure which shows the analysis result by SIM of the layer formed at the 1st step using BTSPS.

Properties required as a material for coating a metal surface are listed below.
(1) Show the corrosion inhibiting action (overall corrosion) of the target metal or their alloys. Furthermore, high pitting corrosion resistance in a chloride environment is required. Furthermore, the surface having a water repellent function is a factor for improving the corrosion resistance.
(2) A smooth and dense film is formed with as few defects as possible,
(3) It has the function of the metal surface as it is. For example, taking a hard disk as an example, it has a structure that does not cause deterioration of magnetic recording characteristics due to an increase in the magnetic distance between the magnetic head and the magnetic recording medium. If a sensor is taken as an example, it can be mentioned that it has a sensing function as it is.

The corrosive environment is basically the air system or water system, but there are factors such as acidification or alkalinization due to decomposition and dissolution of surrounding substances and air pollutants, contamination of chloride, etc. Corrosion resistance in a saltwater environment is required.

(1) can be achieved by forming a silane coupling layer containing fluorine having a long main chain. As described above, a silane coupling containing fluorine having a long main chain is soluble only in a fluorine-based solvent, and when this is used, there is a problem that adhesion to a metal is lowered. On the other hand, when a fluorine-containing silane coupling agent having a short main chain is used, it dissolves in an organic solvent such as alcohol, and adhesion with a metal is obtained, but there is a problem that corrosion resistance is not sufficient. Therefore, an intermediate layer having a long main chain with high anticorrosion properties is formed on the metal, and a silane coupling layer containing fluorine having a long chain is formed on the metal by reacting with a silane coupling agent containing fluorine. I was able to.

Regarding (2), it is necessary that the film of the intermediate layer has as few defects as possible and should be a smooth and dense film. For example, when bistriethoxysilpropyl tetrasulfide is used as a silane coupling agent containing sulfur, bistriethoxysilpropyl tetrasulfide forms a strong coordination bond with aluminum or an aluminum alloy, and is heat treated to give bistriethoxysil Since propyltetrasulfide molecules also form a covalent bond to form a strong bistriethoxysilpropyltetrasulfide molecular film on the metal surface, a film having excellent adhesion without a very dense defect is formed.

As for (3), as in (2), bistriethoxysilpropyl tetrasulfide is arranged in the molecular order, so that it has a very smooth and functional surface while maintaining a high level of corrosion. It can be suppressed.

As a first step, an intermediate layer having a long molecular main chain is formed (an OH group needs to be introduced on the surface), and then, as a second step, a fluorine-containing silane coupling layer is formed. Details are given below for each step.
[First step]
There are the following four methods for forming an intermediate layer having a long molecular main chain having an OH group on the surface.
(1) A method in which a silane coupling agent having alkoxy groups at both ends is reacted with a metal.

This is a reaction for forming a normal silane coupling layer. There is a (Z) group between Si and OH or Si and OH, which determines the length of the molecular main chain. Z is a combination of a plurality of CH ₂ , and may contain an S group or an N group. Examples thereof include bistriethoxyethane (BTSE), trimethoxysilpropylamine (BTSPA), and bistriethoxysilpropyl tetrasulfide (BTSPS).

Specifically, these types are bifunctional polysulfursilanes, for example when S is included in a straight chain, and are represented by the structure of (OR) ₃ —Si—Z—Si— (OR) ₃ , respectively. R is an alkyl or acetyl group, Z is -S _X or -QS _X -Q- (wherein each Q is an aliphatic group or an aromatic group, x is an integer of 2 to 9) . R is represented by ethyl, methyl, propyl, isopropyl, butyl, isobutyl, S-butyl, t-butyl and acetyl. Q is C1-C6 alkyl (straight or branched), C1-C6 alkenyl (straight or branched), C1-C6 alkyl substituted with one or more amino groups, substituted with one or more amino groups Represented by C1-C6 alkenyl, benzyl, and benzyl substituted with C1-C6 alkyl. One of the preferred silanes used is bistriethoxysilpropyl sulfide (s) having 2 to 9 sulfur atoms, particularly bistriethoxysilpropyl tetrasulfide having 4 sulfur. In addition, bis (3-triethoxysylpropyl) disulfide, bis (2-triethoxysylethyl) tetrasulfide, chair (4-triethoxysylbutyl) disulfide, bis (3-trimethoxysylpropyl) tetrasulfide Preferred examples include sulfide and bis (2-trimethoxysilethyl) disulfide.

In this step, the molecular main chain of the intermediate layer can be lengthened by performing it a plurality of times, and OH groups can be introduced on the surface thereof. As the solvent used here, since the solubility of some silane coupling agents in water is limited, basically, in order to improve the solubility of the silane coupling agent, the solvent is 1 to Two or more solvents such as alcohols are used. The alcohol further improves the stability of the treatment solution as well as the wettability of the metal substrate. Since the silane coupling agent basically needs to be hydrolyzed, a solvent having high affinity with water is preferable. Specifically, methanol, ethanol, propanol, butanol and isomers thereof, ketones such as acetone, methyl ethyl ketone and diethyl ketone, ethers such as dimethyl ether, ethyl methyl ether, diethyl ether and tetrahydrofuran, ethylene glycol and propylene glycol In addition, glycols such as diethylene glycol are used.

The silane coupling agent described above is at least partially, preferably completely hydrolyzed. The concentration of these silane coupling agents is about 0.05 to 10% by weight, preferably 0.2 to 5% by weight. Since it is necessary to hydrolyze the silane coupling agent, it is necessary to add water. The amount of water to be used is suitably in the range of several% to 20% with respect to the entire processing solution.

This treatment liquid is basically immersed, but can also be applied by spraying or roll coating. The soaking time depends on the concentration, but when the concentration of the silane coupling agent is 1%, 5 hours or more, preferably 10 hours or more is suitable. Moreover, it can achieve also by hold | maintaining to constant potential for a fixed time from a viewpoint of shortening immersion time.

In order to improve the hydrolysis reaction, it is preferable to maintain the pH at 7 or less, and preferably between 2 and 6 if possible. As the pH adjuster, hydroxides such as potassium hydroxide, ammonia, acetic acid, formic acid, sulfuric acid, hydrochloric acid, nitric acid and the like are suitable. If the normal pH of the treatment solution of the present invention (typically 1% bistriethoxysilpropyl tetrasulfide in ethanol solution of about pH 5.2) can be completely hydrolyzed, there is no need for pH adjustment. . After the silane coupling treatment, it is dried by blowing air. Alternatively, it may be dried by maintaining it in a temperature range of room temperature to 50 ° C.

(2) Method of reacting a metal with an organic substance having an OH group at one end and a group capable of adsorbing to the metal at the opposite end M + HS (CH ₂ ) ₁₁ OH → AlS (CH ₂ ) ₁₁ OH

As shown in Mercaptoundecanol, a group capable of binding to a metal at one end of an ethylene chain and a compound having an OH group at the other end are reacted with a metal, as shown in formula (3) So that an intermediate layer having a long molecular main chain having an OH group on the surface can be formed.

(3) one terminal OH group, the process M + HO (CH ₂₎ reacting a metal compound having a COO group capable of adsorbing to the metal on the opposite end _{^{_{15 COO - → MOOOC (CH 2}}} ) 15 OH + OH - (4) Formula
Like hydroxyhexadecanoic acid, a compound having a COO group capable of binding to a metal at one end of an ethylene chain and an OH group at the other end is reacted with a metal to obtain the formula (4) Thus, an intermediate layer having a long molecular main chain having an OH group on the surface can be formed.

(4) A method of reacting a metal with a silane coupling agent having an alkoxy group at one end and a group capable of adsorbing a metal at the opposite end.

Since isocyanate groups, amino groups, and mercapto groups can be bonded to metals, one end is an alkoxy group, and a silane coupling agent having these groups capable of adsorbing to the metal at the opposite end is reacted with the metal to the surface. An intermediate layer having an OH group and a long molecular main chain can be formed (formulas 5 and 6 indicate the case of an isocyanate group). Specifically, these types are X— (CH 2) n —Si—R 3, where X is SH, NH ₂ , or NCO, and each of the three R is independently an alkoxy group, an alkyl group, and a hydrogen N is an integer from 0 to 10. As this type of silane to be used, for example, when it has an SH group, it is represented by 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropylmethyldimethoxysilane, and mercaptoethyltriethoxysilane. Since the main chain of the silane coupling agent represented here is short with propyl, it is necessary to repeat the treatment a plurality of times to make the main length longer.

Regarding the solvent, since the solubility of some silane coupling agents in water is limited with respect to the solvent used here, basically, in order to improve the solubility of the silane coupling agent, A solvent such as one or two or more alcohols is used as the solvent. The alcohol further improves the stability of the treatment solution as well as the wettability of the metal substrate. Since the silane coupling agent basically needs to be hydrolyzed, a solvent having high affinity with water is preferable. Specifically, methanol, ethanol, propanol, butanol and isomers thereof, ketones such as acetone, methyl ethyl ketone and diethyl ketone, ethers such as dimethyl ether, ethyl methyl ether, diethyl ether and tetrahydrofuran, ethylene glycol and propylene glycol In addition, glycols such as diethylene glycol are used.

The above silane coupling agent is at least partially, preferably completely hydrolyzed. The concentration of these silane coupling agents is about 0.05 to 10% by weight, more preferably 0.2 to 5% by weight. Since it is necessary to hydrolyze the silane coupling agent, it is necessary to add water. The amount of water to be used is suitably in the range of several% to 20% with respect to the entire processing solution.

By performing heat treatment after the first step, the first step layer can be strengthened and the corrosion resistance can be improved. As the heat treatment, a temperature of 100 to 200 ° C. and a time of 30 minutes to 2 hours are preferable, and a temperature of 100 to 150 ° C. and a time of 30 minutes to 1 hour are more preferable. Even in this case. The hydroxyl groups on the surface are not lost.

In the first step, similar results can be obtained by combining the processes (1) to (4) described above. For example, an intermediate layer having a long molecular main chain having an OH group on the surface can be formed by reacting hydroxyhexadecanoic acid with a metal substrate and further reacting BTSE thereon.

[Second step]
In this step, a fluorine-containing silane coupling layer is reacted with the surface formed in the first step. In the first step, since the metal surface is an OH group, it is reacted with a fluorine-containing silane coupling agent.

By such a minimum of two steps, an organic layer in which fluorine groups are introduced on the long surface of the molecular main chain can be formed. It becomes possible to further strengthen the film in order to bond the intermolecular molecules located on the side of the Si group. Corrosion resistance can be improved by performing a heat treatment as a post-treatment after these two steps. As the heat treatment, a temperature of 100 to 200 ° C. and a time of 30 minutes to 2 hours are preferable, and a temperature of 100 to 150 ° C. and a time of 30 minutes to 1 hour are more preferable.

Examples of the fluorine-containing silane coupling agent used include perfluorodecyltrimethoxysilane, perfluorodecyltriethoxysilane, trifluoropropyltrimethoxysilane, trifluoropropyltriethoxysilane, perfluorooctyltrimethoxysilane, and perfluorooctyl. Examples include triethoxysilane, perfluorododecyltrimethoxysilane, perfluorododecyltriethoxysilane, perfluoropentyltriethoxysilane, and perfluoropentyltrimethoxysilane.

The following was performed as the corrosion evaluation of the sample subjected to the above treatment. As samples, the following samples were used unless otherwise specified.
(1) Aluminum and aluminum alloys:
After sputtering titanium oxide as an adhesion layer on a silicon wafer, the target aluminum or aluminum alloy was sputtered thereon to form a sample.
(2) Iron:
Regarding iron, after polishing SS400 with emery paper, it was finished to a mirror surface by buffing. After polishing, the mixture was degreased using acetone in combination with ultrasonic waves.
(3) Copper After sputtering TaN as an adhesion layer on a silicon wafer, the target copper or copper alloy was sputtered thereon to form a sample.

The corrosion resistance of Al and Al alloy was evaluated by the following two methods.
(1) Electrochemical test: 1 cm ^{2 of} the sample subjected to the two-stage treatment and heat treatment was left, and the other portions were sealed. It was immersed in a 3.5% NaCl aqueous solution. After dipping for 10 minutes, when the potential was stabilized, the potential was scanned at a scanning rate of 30 mV / min in the anode direction with reference to a potential of -100 mV lower than the immersion potential, and the current was measured. After the measurement, the corrosion current density was determined using Tafel's relational expression. The potential at which the current abruptly rises was defined as the pitting corrosion potential. When the potential was -500 mV or more, the pitting corrosion resistance was good. The more noble this potential, the better the pitting corrosion resistance.
(2) Immersion test A sample subjected to silane coupling treatment and heat treatment was immersed in a 3.5% NaCl solution. The presence or absence of pitting corrosion was observed with an optical microscope. Those that did not change were represented by ◯, those that did not generate pitting corrosion but those that had a discoloration range were represented by Δ, and those in which pitting corrosion was confirmed were represented by ×.

Hereinafter, specific examples to which the present invention is applied will be described with reference to tables. Although not specifically described, the processing temperature and test temperature are all 25 ° C. The corrosion resistance of iron and nickel was evaluated by the following method.
(1) Electrochemical test: 1 cm ^{2 of} the sample subjected to the two-stage treatment and heat treatment was left, and the other portions were sealed. It was immersed in an aqueous borate buffer solution containing 0.1M chloride ions. When immersed for 10 minutes and the potential was stabilized, the potential was scanned at a scanning rate of 30 mV / min in the anode direction with reference to a potential of -100 mV lower than the immersion potential, and the current was measured. After the measurement, the corrosion current density was determined using Tafel's relational expression.
(2) Immersion test: A sample subjected to two-stage treatment and heat treatment was immersed in a 3.5% NaCl solution. The presence or absence of pitting corrosion was observed with an optical microscope. Those that did not change were represented by ◯, those that did not generate pitting corrosion but those that had a discoloration range were represented by Δ, and those in which pitting corrosion was confirmed were represented by ×.

The corrosion resistance of copper was evaluated by the following method.
(1) Electrochemical test: 1 cm ^{2 of} the sample subjected to the two-stage treatment and heat treatment was left, and the other portions were sealed. It was immersed in 0.5M Na ₂ SO ₄ aqueous solution. When immersed for 10 minutes and the potential was stabilized, the potential was scanned at a scanning rate of 30 mV / min in the anode direction with reference to a potential of -100 mV lower than the immersion potential, and the current was measured. After the measurement, the corrosion current density was determined using Tafel's relational expression.

Hereinafter, specific examples to which the present invention is applied will be described with reference to tables. Although not specifically described, the processing temperature and test temperature are all 25 ° C.
(Regarding Al material)
[Comparative Example 1-6 Example 1-9]
Table 1 relates to (1) the method of reacting a silane coupling agent having alkoxy groups at both ends with a metal. Isopropyl alcohol was used as the solvent. The concentration of the reagent used in each step is 1.0 vol%. 10% water is also added for hydrolysis.

The polarization curve for untreated Al measured in 3.5% NaCl solution is shown in FIG. The pitting corrosion potential when not treated is -665 mV (Ag / AgCl KCl saturated electrode standard). The corrosion current density is 0.0072 μA / cm ² . If the corrosion current density is lower than this, it means that the overall corrosion is suppressed, and if the pitting potential is +, the pitting corrosion is suppressed.

¡Two steps of the first step and the second step were performed. Heat treatment was performed at 100 ° C. for 1 hour between the first step and the second step. Also, heat treatment was performed each time when the treatment was performed a plurality of times in each step. The polarization curve in a 3.5% NaCl solution of the sample subjected to the two-stage treatment was measured, and the corrosion current density and the pitting corrosion potential were calculated therefrom. The results are shown in Table 1.

As shown in Comparative Example 2-4, when BTSPS, BTSPA, and BTSE were each treated alone, the corrosion current density decreased slightly, but the pitting potential remained almost unchanged, so there was no significant change in corrosion resistance. . Comparative Example 5 is a case where BTSE treatment is performed once as the first step and then treatment with trifluoropropyltrimethoxysilane as the second step. Both the corrosion current density and the pitting potential are obtained from BTSE alone. The corrosion resistance is improved, but it is not sufficient. This is because the silane coupling layer formed in the first step, which is the intermediate layer formation, is thin. Even if the treatment time is extended to 24 h for the purpose of increasing the thickness (Comparative Example 6), there is almost no change in the corrosion resistance. Therefore, the BTSE process was repeated a plurality of times, that is, after the first layer was formed, it was attempted to stack by reacting the OH group outside the first layer with BTSE in the second process. As a result, as shown in Example 3, as a result of three attempts, the corrosion current density was remarkably reduced, and the pitting potential was greatly shifted to the + side, and the corrosion resistance was greatly improved. When BTSPS and BTSPA are used for the first step and trifluoropropyltrimethoxysilane is used for the second step, the corrosion resistance is improved even if the number of treatments is one in the first step (Examples 1 and 2). I was able to. Even when perfluorodecyltrimethoxysilane and perfluorododecyltriethoxysilane were used for the fluorine-containing silane coupling agent used in the second step, the same results as when treated with trifluoropropyltrimethoxysilane were obtained. (Example 4-9). From this, it can be understood that at least 6 or more C atoms are necessary in the straight chain in the intermediate layer (layer formed in the first step).

However, when aminopropyltrimethoxysilane is used instead of the fluorine-containing silane coupling agent in the second step, the corrosion resistance is clearly worse compared to Example 7, and the advantage is obtained when a fluorine-containing silane coupling agent is used for the outermost layer. Sex is confirmed.

FIG. 2 shows the SIM analysis result of the layer formed in the first step using BTSPS. Since the thickness of the layer is about 5.5 nm, it can be seen that the thickness of at least the intermediate layer needs to be 5 nm or more.

Table 2 shows the corrosion behavior of samples subjected to various treatments when immersed in salt water. Even when the two-stage treatment was not performed and when the two-stage treatment was performed, the corrosion resistance was poor when BTSE was used only once in the first-stage treatment, and the occurrence of corrosion was confirmed within a few days. On the other hand, when treated under the conditions shown in the examples, no corrosion was observed even after 20 days. Even under the conditions of Comparative Example 7, the improvement in corrosion resistance is not so remarkable. From this, it can be seen that a structure having an intermediate layer having a long main chain and having a silane coupling layer containing fluorine in the outer layer exhibits excellent corrosion resistance.

[Comparative Example 5, Example 10-12]
Table 3 relates to (2) a method of reacting a metal with an organic substance having an OH group at one end and a group capable of adsorbing a metal at the opposite end. Isopropyl alcohol was used as the solvent. Comparative Example 8 is a case of treatment with mercaptoundecanol, but sufficient corrosion resistance cannot be obtained by the treatment of only this step. The same applies even if the treatment time is extended to 24 h (Comparative Example 9). However, as shown in Example 10-12, the corrosion resistance could be remarkably improved by forming the fluorine-containing silane coupling layer in the second step. Mercaptoundecanol contains 11 C in the main chain portion, and this condition satisfies the above-mentioned condition that “at least 6 C is required”. Even when perfluorodecyltrimethoxysilane and perfluorododecyltriethoxysilane were used for the fluorine-containing silane coupling agent used in the second step, the same results as when treated with trifluoropropyltrimethoxysilane were obtained. (Example 11-12)

[Comparative Example 10, Example 13-15]
Table 4 relates to a method of reacting a metal with a compound having an OH group at one end and a COO group capable of adsorbing a metal at the opposite end. Isopropyl alcohol was used as the solvent. Comparative Example 10 is a case of treatment with hydroxyhexadecanoic acid, but sufficient corrosion resistance cannot be obtained by the treatment of only this step. The same applies even if the treatment time is extended to 24 h (Comparative Example 11). However, as shown in Example 10-12, the corrosion resistance could be remarkably improved by forming the fluorine-containing silane coupling layer in the second step. Hydroxyhexadecanoic acid contains 16 C in the main chain portion, and this condition satisfies the above-mentioned condition that “at least 6 C are required”. Even when perfluorodecyltrimethoxysilane and perfluorododecyltriethoxysilane were used for the fluorine-containing silane coupling agent used in the second step, the same results as when treated with trifluoropropyltrimethoxysilane were obtained. (Example 14-15)

[Comparative Example 7, Examples 16-18]
Table 5 relates to a method of reacting a metal with a silane coupling agent having an alkoxy group at one end and a group capable of adsorbing a metal at the opposite end. Isopropyl alcohol was used as the solvent. Comparative Example 12 shows a case where the first step was treated with mercaptopropyltrimethoxysilane once and the second step was treated with perfluorodecyltrimethoxysilane. In this case, sufficient corrosion resistance is not obtained, but this is because the thickness of the intermediate layer formed in the first step is not sufficient (three C) as described above. Even when the treatment in the first step is repeated twice and the thickness of the intermediate layer is C6 (Comparative Example 13), sufficient corrosion resistance cannot be obtained. However, when a fluorine-containing silane coupling layer is formed thereon (Example 16), sufficient corrosion resistance is obtained. The same applies when isocyanate propyltriethoxysilane and aminopropyltrimethoxysilane are used in the first step instead of mercaptopropyltrimethoxysilane.

[Example 19]
The present embodiment relates to a processing method using multi-steps in which (Table 6), (2) and (1) are used in combination. Isopropyl alcohol was used as the solvent. That is, this is a case where a fluorine-containing silane coupling layer is formed as the outermost layer after the intermediate layers are formed by laminating different substances in a plurality of steps of the first and second steps. Excellent corrosion resistance can be obtained. In this case, the number of C in the intermediate layer is 18, which satisfies the above-described condition that “at least 6 C is required”. Further, by sandwiching the BTSE layer, a strong film is formed to form a bond with the side at the Si portion of BTSE.

(Fe material)
Although this example was performed for SS400, similar results were obtained for nickel. In order to efficiently form an organic layer on iron, it is necessary that an immobile film is formed on the iron. Therefore, before the first step, a non-moving body film was formed by a constant potential method in an aqueous borate solution. In the case where only hydroxyhexadecanoic acid in the first step is reacted after the non-passive film treatment (Comparative Example 15), sufficient corrosion resistance cannot be obtained as in the case of only the passive treatment (Comparative Example 14). Corrosion resistance can be improved by forming a fluorine-containing silane coupling layer after activating treatment + hydroxyhexadecanoic acid treatment (Examples 20-22).

Table 8 shows the corrosion behavior when samples subjected to various treatments were immersed in salt water. In the case of only the passivation treatment and the one treated with hydroxyhexadecanoic acid, corrosion resistance was poor and occurrence of corrosion was confirmed in several days. On the other hand, when treated under the conditions shown in Example 20-22, no corrosion was confirmed even after 20 days.

(For copper materials)
Although the present Example was implemented regarding copper, the same result was obtained also about various copper alloys. Only mercaptoundecanol (Comparative Example 15) does not provide sufficient corrosion resistance, but the corrosion resistance can be improved by laminating a fluorine-containing silane coupling layer (Examples 23-25).

Claims

On the metal substrate, an organic intermediate layer and a fluorine-containing silane coupling layer are sequentially laminated, and the intermediate layer is connected continuously or discontinuously on a straight chain with at least 6 carbon atoms connected. A surface-modified metal member.
In the method for modifying a surface-modified metal member in which an intermediate layer made of an organic material and a silane coupling layer containing fluorine are sequentially laminated on a metal substrate,
The method for modifying a surface-modified metal member, wherein the intermediate layer is formed of any one of the following (1) to (4) or a combination thereof.
(1) A method of reacting a base metal with a silane coupling agent having alkoxy groups at both ends,
(2) A method of reacting an organic substance having an OH group at one end and a group capable of adsorbing with a metal at the opposite end with a base metal,
(3) a method of reacting a base metal with a compound having an OH group at one end and a COO group capable of adsorbing to the base metal at the opposite end;
(4) A method of reacting a base metal with a silane coupling agent having an alkoxy group at one end and a group capable of adsorbing to the base metal at the opposite end
3. The silane coupling layer according to claim 2, wherein the silane coupling layer is formed by a hydrolysis reaction and a dehydration condensation reaction of a fluorine-based silane coupling agent having a hydroxyl group and a fluorinated hydrocarbon group on the intermediate layer. A surface modification method for a surface modified metal member.