JP7163151B2 - Aqueous antirust surface treatment composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a water-based antirust surface treatment composition and a surface-coated metal member.

Various developments have been made so far in water-based surface treatment agents for treating the surface of metal members. As this type of technology, for example, the technology described in Patent Document 1 is known. Patent Document 1 describes a water-based silicate paint containing an alkali metal silicate, colloidal silica, a silane coupling agent, and water (claim 3 of Patent Document 1).

WO2003/085171

However, as a result of investigation by the present inventor, it was found that the water-based surface treatment agent described in Patent Document 1 has room for improvement in terms of corrosion resistance.

As a result of investigations made by the present inventors, it was found that the corrosion resistance of the film can be improved by adjusting the pH of the aqueous surface treatment agent within an appropriate range, and that the appropriate range of pH according to the components contained in the aqueous surface treatment agent. found that there is
However, as a result of further investigation, it has been found that the pH of the aqueous surface treatment agent after mixing each component varies over time. Even after being stored for about one year after mixing, the pH of the aqueous surface treatment agent continued to change gradually.

Although the detailed mechanism is not clear, in water-based surface treatment agents containing water-soluble transition metal compounds such as titanium chelating agents and phosphoric acid-based rust preventives such as highly condensed phosphates, decomposition of components and decomposed products It is thought that the pH of the water-based surface treatment agent fluctuates over time due to the volatilization of

As a result of further intensive research based on these findings, it was found that the pH can be adjusted within an appropriate range with a pH adjuster, and that an aqueous rust inhibitor containing a silane coupling agent, a water-soluble transition metal compound, a phosphorus-based rust inhibitor and water was used. In the surface treatment composition, by setting the pH in the range of 2.0 to 9.0, it is possible to suppress the generation of red rust in a combined cycle test, so it is possible to improve the corrosion resistance. rice field.

According to the invention,
A water-based rust preventive surface treatment composition used to form a film on the surface of a metal member,
a silane coupling agent;
a water-soluble transition metal compound comprising a water-soluble titanium compound or a water-soluble zirconium compound;
a phosphorus-based rust inhibitor containing a highly condensed phosphate or a polyvalent phosphate;
a solvent comprising water;
and a pH adjuster,
Provided is a water-based rust preventive surface treatment composition having a pH of 2.0 to 9.0 at a liquid temperature of 25°C.

Also according to the present invention,
a metal member;
and a coating formed on the surface of the metal member and comprising the water-based rust preventive surface treatment composition.

INDUSTRIAL APPLICABILITY According to the present invention, a water-based rust preventive surface treatment composition capable of forming a film having high corrosion resistance on the surface of a metal member, and a surface-coated metal member surface-treated using the composition are provided.

It is a schematic diagram which shows the structure of the management system of this embodiment. It is a figure which shows the result of the combined cycle test of each sample. FIG. 4 is a diagram showing changes in pH of each sample when stored for a predetermined period; FIG. 4 is a diagram showing the relationship between the pH of a sample and the results of a combined cycle test;

An outline of the water-based rust preventive surface treatment composition of the present embodiment will be described.
The water-based antirust surface treatment composition of the present embodiment contains a silane coupling agent, a water-soluble transition metal compound containing a water-soluble titanium compound or a water-soluble zirconium compound, and a highly condensed phosphate or polyvalent phosphate. It contains a phosphorus-based rust inhibitor, a solvent containing water, and a pH adjuster. The water-based rust preventive surface treatment composition has a pH within the range of 2.0 or more and 9.0 or less at a liquid temperature of 25°C.

The water-based rust preventive surface treatment composition of the present embodiment (hereinafter sometimes simply referred to as "composition") is suitably used as a water-based rust preventive surface treatment agent for forming a film on the surface of a metal member. be able to.

According to the findings of the present inventors, in a water-based rust preventive surface treatment composition that can be adjusted within an appropriate pH range with a pH adjuster and contains a silane coupling agent, a water-soluble transition metal compound, a phosphorus-based rust preventive agent, and water, It was found that by setting the pH within the range of 2.0 to 9.0, the occurrence of red rust and the like can be suppressed, so that the corrosion resistance of the coating can be improved.

In addition, by controlling the pH in the water-based anticorrosive surface treatment composition within an appropriate range, the composition after mixing each component and the composition after storing for a predetermined period after mixing have reduced corrosion resistance. can be suppressed.

The lower limit of the pH of the water-based rust preventive surface treatment composition is, for example, 2.0 or higher, preferably 3.0 or higher, and more preferably 4.0 or higher. As a result, it is possible to suppress the generation of white rust in the combined cycle test, so that the corrosion resistance can be improved. On the other hand, the upper limit of the pH is, for example, 9.0 or less, preferably 6.8 or less, more preferably 5.5 or less. As a result, it is possible to suppress the generation of red rust in the combined cycle test, so that the corrosion resistance can be improved.

Moreover, it can be an acidic water-based rust preventive surface treatment composition having a pH of 3.0 to 6.8. By making the water-based rust preventive surface treatment composition acidic, each component contained therein is in a more stable state in the solvent, so that the solution stability can be enhanced. Although the detailed mechanism is not clear, it is thought that the corrosion resistance can be improved because the acid moderately dissolves the surface of the metal member, increasing the adhesion of the film to the moderately roughened surface.

In this embodiment, the pH can be measured using a pH meter at a liquid temperature of 25° C.±1° C. of the water-based antirust surface treatment composition. The liquid temperature is usually 25°C, but a variation of about +1°C or -1°C is permissible.

According to this embodiment, it is possible to realize a water-based rust preventive surface treatment composition capable of forming a film having high corrosion resistance on the surface of a metal member.

Hereinafter, each component of the water-based rust preventive surface treatment composition of the present embodiment will be described in detail.

<Silane coupling agent>
The water-based antirust surface treatment composition contains a silane coupling agent.
By using a silane coupling agent, a composition containing a water-soluble transition metal compound, water-dispersible resin or water-soluble resin, or inorganic colloidal particles can be stabilized as an aqueous solution. In addition, since the silane coupling agent can improve the affinity between inorganic colloidal particles such as aqueous colloidal silica and resins such as water-soluble transition metal compounds, water-dispersible resins, or water-soluble resins, stable aqueous solutions can be obtained. (composition) can be formed.
A water-soluble silane coupling agent that can be dissolved in water is used as the silane coupling agent.

The silane coupling agent has, for example, the general formula: (R ¹ ) _m Si(OR ² ) _4-m (wherein R ¹ is a functional group having 1 to 20 carbon atoms, R ² is a lower alkyl group and m is an integer of 0 to 3.) or a compound obtained by hydrolyzing and polycondensing the alkoxysilane is used. The silane coupling agent may be partially hydrolyzed in the composition.

Specific examples of the silane coupling agent represented by the above general formula include Si(OCH ₃ ) ₄ , Si(OC ₂ H ₅ ) ₄ , CH ₃ Si(OCH ₃ ) ₃ , CH ₃ Si(OC ₂ H5) ₃ , _C2H5Si (OCH3) ₃ , _{C2H5Si ( OC2H5} ) _{3 , CH2 (} O) _{CHCH2O ( CH2} ) _{3Si (} OCH3) _{3 ,} CH ₂ =C( _CH3 )COO( _CH2 )3Si(OCH3) ₃ , _CH2 =CHCOO _{( CH2} )3Si ₍ OCH3) _{3 ,} H2N _{( CH2} ) _{3Si ( OCH3} ) ₃ , HS(CH ₂ ) ₃ Si(OCH ₃ ) ₃ , OCN(CH ₂ ) ₃ Si(OC ₂ H ₅ ) ₃ and the like.

In the above chemical formula, functional groups in R ¹ include, for example, vinyl, 3-glycidoxypropyl, 3-glycidoxypropylmethyl, 2-(3,4-epoxycyclohexyl)ethyl, p-styryl, 3-methacryloxypropyl, 3-methacryloxypropylmethyl, 3-acryloxypropyl, 3-aminopropyl, N-2-(aminoethyl)-3-aminopropyl, N-2-(aminoethyl)-3-amino Examples include groups such as propylmethyl, N-phenyl-3-aminopropyl, N-(vinylbenzyl)-2-aminoethyl-3-aminopropyl, 3-ureidopropyl, 3-mercaptopropyl, 3-isocyanatopropyl.

Specific examples of lower alkyl groups in the above chemical formula include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, sec-butyl, n-pentyl, 1-ethylpropyl, Linear or branched alkyl groups such as isopentyl and neopentyl can be mentioned.

The water-soluble silane coupling agent may include, for example, a silane coupling agent having an epoxy group as a functional group (epoxysilane) or a silane coupling agent having an amino group as a functional group (aminosilane). Among these, it is more preferable to use epoxysilane from the viewpoint of corrosion resistance.

Examples of the epoxysilane include glycidyl or epoxy group-containing trimethoxysilane such as 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, and 2-(3,4-epoxycyclohexylethyl)trimethoxysilane. Alkoxysilane compounds can be mentioned.

The content of the silane coupling agent is, for example, 1% by mass to 20% by mass, preferably 2% by mass to 15% by mass, more preferably 2% by mass to 15% by mass, in terms of solid content, based on the entire water-based antirust surface treatment composition. 3% by mass to 10% by mass. By appropriately adjusting the content of the silane coupling agent, a coating having excellent corrosion resistance can be realized.
In the present specification, "-" means including upper and lower limits unless otherwise specified.

<Water-soluble transition metal compound>
The water-based antirust surface treatment composition contains a water-soluble transition metal compound. Water-soluble transition metal compounds include water-soluble titanium compounds or water-soluble zirconium compounds. Water-soluble transition metal compounds can be dissolved in water. By using a water-soluble transition metal compound, chemical bonding with the silane coupling agent or other components contained therein is promoted, and a film with high strength is formed. From the viewpoint of enhancing corrosion resistance, a water-soluble titanium compound can be used.

The water-soluble titanium compound may include one or more selected from the group consisting of inorganic titanium compounds, peroxotitanates, amine water-soluble titanates, and chelate titanates (water-soluble titanium chelating agents). Specific examples of the water-soluble titanium compound include inorganic titanium compounds such as titanium trichloride, titanium tetrachloride, titanium sulfate, and titanium oxychloride, inorganic or chelate peroxotitanates, and amines. For example, amine water-soluble titanate obtained by reacting titanium alkoxide with water, oxycarboxylic acid chelate titanium coordinated with oxycarboxylic acid such as lactic acid, malic acid, citric acid, tartaric acid, gluconic acid and glycol, Chelate titanates (water-soluble titanium chelating agents) such as alkanolamine chelate titanium in which alkanols such as monoethanolamine, diethanolamine and triethanolamine are coordinated can be included.
The water-soluble zirconium compound may have the same structure as the water-soluble titanium compound, and may be selected from the group consisting of inorganic zirconium compounds, peroxozirconates, amine-based water-soluble zirconates, and chelate-based zirconates. can include one or more

The water-based rust preventive surface treatment composition contains, as curing components, organic titanium compounds such as organic titanium alcosides, organic titanium chelates and organic titanium acylates, and organic compounds such as organic zirconium alcosides, organic zirconium chelates and organic zirconium acylates. It may contain an organic transition metal compound such as a zirconium compound. By including this curing component, it is possible to obtain a structure in which the component in the film structure and the curing component are crosslinked, or a self-crosslinking structure.

As the titanium chelating agent, for example, an organic compound represented by the general formula: Ti(X) ₄ and an oligomer thereof can be used. X in the above general formula is selected from a hydroxyl group, a lower alkoxy group and a chelating substituent, and the four X's may be the same or different.

Examples of the lower alkoxy groups include alkoxy groups having 6 or less, preferably 4 or less carbon atoms such as methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobutoxy and tert-butoxy.
The chelating substituent is, for example, a group derived from an organic compound capable of forming a chelate. Examples of organic compounds having a chelate-forming ability include β-diketones such as acetylacetone, alkylcarbonylcarboxylic acids such as acetoacetic acid and their esters, and alkanolamines such as triethanolamine.
Specific examples of the chelating substituent include lactate, ammonium lactate, triethanolamine, acetylacetonate, acetoacetate, ethylacetoacetate and the like.

An example of the titanium chelating agent is titanium triethanolamine chelated with triethanolamine. TC-400 (titanium diisopropoxytriethanolamine) manufactured by Matsumoto Fine Chemical Co., Ltd., which is an example of titanium triethanolamine, exhibits alkalinity when dissolved in water. On the other hand, there is titanium lactate ammonium salt composed of titanium lactate chelated with lactic acid and the ammonium salt of titanium lactate. TC-310 manufactured by Matsumoto Fine Chemical Co., Ltd., which is an example of titanium lactate ammonium salt, exhibits an acidic pH when dissolved in water, and TC-300 is neutralized with ammonium and exhibits a generally neutral pH. .

As the titanium chelating agent, it is preferable to use one in which the chelating substituent is lactate (lactate ion) from the viewpoint of improving the liquid stability of the water-based rust preventive surface treatment composition.

The titanium chelating agent undergoes a cross-linking reaction with the aforementioned silane coupling agent when the water-based rust preventive surface treatment composition is applied to the metal member and then subjected to conditions at room temperature or higher. This promotes chemical bonding with the silane coupling agent and other components contained therein, forming a film with high strength.

The content of the water-soluble transition metal compound is, for example, 0.5% by mass to 5% by mass, preferably 1% by mass to 4% by mass, in terms of solid content, relative to the entire water-based antirust surface treatment composition. More preferably, it is 1.5% by mass to 3% by mass.

The content of the water-soluble transition metal compound is, for example, 10 parts by mass to 100 parts by mass, preferably 15 parts by mass to 70 parts by mass, in terms of solid content, with respect to 100 parts by mass of the silane coupling agent. More preferably, it is 20 parts by mass to 50 parts by mass.

<Phosphate rust inhibitor>
The water-based rust preventive surface treatment composition contains a phosphoric acid-based rust preventive.
The phosphoric acid-based rust inhibitor may contain a highly condensed phosphate or a polyvalent phosphate.
The water-based antirust surface treatment composition may contain either one of the highly condensed phosphate and the polyvalent phosphate, or may contain both.

The water-based antirust surface treatment composition can contain a highly condensed phosphate.
The highly condensed phosphate is a salt of a highly condensed product formed by dehydration condensation of four or more phosphoric acids. By using a highly condensed phosphate, the corrosion resistance of the coating made of the composition can be improved as compared with the case of using orthophosphoric acid, pyrophosphoric acid, triphosphoric acid and salts thereof.

The degree of condensation of phosphoric acid (the number of structural units derived from phosphoric acid in the molecule) of the highly condensed phosphate is, for example, 4 or more, preferably 5 or more, and more preferably 6 or more. Thereby, corrosion resistance can be improved. On the other hand, the upper limit of the degree of condensation is not particularly limited, but may be, for example, 50 or less, 40 or less, or 30 or less.

As the highly condensed phosphate, for example, one having a linear structure, a cyclic structure, or a network structure in which a linear structure and a cyclic structure are mutually bonded can be used. Among these, the highly condensed phosphate preferably has a cyclic structure or network structure.

Examples of the highly condensed phosphate having a linear structure include tetrapolyphosphate, pentapolyphosphate, and hexapolyphosphate.
Examples of highly condensed phosphates having a cyclic structure include tetrametaphosphate, pentametaphosphate, hexametaphosphate, and octametaphosphate.
Examples of highly condensed phosphates having a network structure include ultraphosphates. Ultraphosphate hydrolyzes in an aqueous solution to form a mixture of highly condensed phosphate having a linear structure and highly condensed phosphate having a cyclic structure.
In addition, ultraphosphates, for example, have an average degree of condensation of 10 or more, and are usually traded as having a distribution of the degree of condensation.

Among these, the highly condensed phosphate preferably contains at least a highly condensed phosphate having a cyclic structure. A highly condensed phosphate having a cyclic structure and a highly condensed phosphate having a chain structure may be used in combination. Corrosion resistance can be further enhanced by using a highly condensed phosphate having a cyclic structure.
In addition to the high condensed phosphate, the water-based rust preventive surface treatment composition of the present embodiment may contain other low condensed phosphate as long as the effects of the present invention are exhibited.

As a result of studies by the present inventors, when using a low condensed phosphate with a small number of condensations of phosphoric acid such as normal orthophosphoric acid, orthophosphate, diphosphate and triphosphate in the composition, It was found that there is room for improvement in the corrosion resistance of the film.
On the other hand, by using a high condensed phosphate, it is possible to impart a high rust prevention effect to the metal member as compared with the case where only orthophosphoric acid, orthophosphate or low condensed phosphate is used. Do you get it.

The highly condensed phosphates are constructed as salts of condensed phosphoric acid anions and corresponding cations.
As the cation of the highly condensed phosphate, sodium ion, potassium ion, lithium ion, calcium ion, magnesium ion, ammonium ion and the like can be employed. From the viewpoint of availability and solubility in water, the cation is preferably sodium ion or potassium ion. That is, highly condensed sodium phosphate or highly condensed potassium phosphate can be used as the highly condensed phosphate.

The content of the highly condensed phosphate is, for example, 0.1% by mass to 2.0% by mass, preferably 0.2% by mass to 1.5% by weight, more preferably 0.3% to 1.0% by weight. Corrosion resistance can be improved by making it more than the said lower limit. The storage stability of the composition can be enhanced by making it equal to or less than the above upper limit.

The content of the highly condensed phosphate contained in the water-based antirust surface treatment composition is analyzed by known methods such as GPC (gel permeation chromatography) analysis and HPLC (high performance liquid chromatography) analysis. be able to.

The water-based antirust surface treatment composition can contain a polyvalent phosphate.
The polyvalent phosphate ester is a compound having a plurality of phosphate ester residues. The phosphate ester residue has a phosphate monoester structure or a phosphate diester structure. The alcohol moiety forming the phosphate ester residue may be any of primary alcohol, secondary alcohol and tertiary alcohol.
Specific examples of the polyvalent phosphate include phytic acid.

The content of the polyvalent phosphate ester is, for example, 0.1% by mass to 2.0% by mass, preferably 0.15% by mass to 1.5% by weight, more preferably 0.20% to 1.0% by weight. Corrosion resistance can be improved by making it more than the said lower limit. The storage stability of the composition can be enhanced by making it equal to or less than the above upper limit.

The total content of the highly condensed phosphate or polyvalent phosphate is, for example, 0.1% by mass to 3.0% by mass, preferably in terms of solid content, relative to the entire water-based antirust surface treatment composition. is 0.15% by mass to 2.0% by mass, more preferably 0.3% by mass to 1.0% by mass. Corrosion resistance can be improved by making it more than the said lower limit. By adjusting the content to be equal to or less than the above upper limit value, the physical properties of the film can be balanced.

Further, the total content of the highly condensed phosphate or polyvalent phosphate is, for example, 2 parts by mass to 20 parts by mass, preferably 3 parts in terms of solid content, with respect to 100 parts by mass of the silane coupling agent. 18 parts by mass to 18 parts by mass, more preferably 5 to 15 parts by mass.

The water-based rust preventive surface treatment composition of the present embodiment has a film structure with excellent corrosion resistance by using a highly condensed phosphate or a polyvalent phosphate in combination with a silane coupling agent and a water-soluble transition metal compound. can be realized, it is possible to improve the rust resistance of the metal member.

Although the detailed mechanism is not clear, a film having a crosslinked structure is formed by a dehydration condensation reaction between a hydrolyzed condensate of a silane coupling agent and a water-soluble transition metal compound. By appropriately coordinating phosphate ions derived from highly condensed phosphates or polyvalent phosphate esters to the transition metal atoms of , the denseness of the film can be increased, resulting in a film structure with excellent corrosion resistance. It is considered feasible.
Also, among the transition metal atoms, by using titanium, the rust prevention effect can be enhanced compared to zirconium, which is another transition metal atom. Although the detailed mechanism is not clear, it is thought that the use of titanium makes the film structure more dense.

<Solvent>
The aqueous antirust surface treatment composition described above contains a solvent containing water. This solvent may be composed of an aqueous solvent containing only water, or may be composed of an aqueous mixed solvent containing water and a hydrophilic solvent other than water.

Examples of the water include city water, distilled water, and ion-exchanged water.

Examples of the hydrophilic solvent include polar organic solvents such as alcohols. From the viewpoint of solution stability, the aqueous mixed solvent may be composed of a mixed solvent of water and alcohol. The content ratio of water in the water-based mixed solvent can be determined in consideration of the chemical properties and blending amounts of each component in the water-based rust preventive surface treatment composition.

Examples of the alcohol include low boiling point alcohols having a boiling point of less than 100° C. such as methanol, ethanol, n-propyl alcohol and iso-propyl alcohol, iso-butanol, methyl cellosolve, ethyl cellosolve and propylene glycol monomethyl ether (PGME). , butyl cellosolve, ethylene glycol mono-tertiary butyl ether (ETB), diformaldehyde methoxy ethanol, etc. can be used. These may be used alone or in combination of two or more.

Among these, methanol, ethanol, n-propyl alcohol, iso-propyl alcohol, n-butyl alcohol, s-butyl alcohol and t-butyl alcohol due to high availability and high solubility for each component It can contain one or two or more alcohols selected from the group consisting of: In addition, by using low boiling point alcohols such as methyl alcohol (boiling point: 64.7°C), ethyl alcohol (boiling point: 78.37°C), and iso-propyl alcohol (boiling point: 82.4°C), a lower temperature environment It becomes possible to form a coating film under a dry environment.

In this embodiment, by using alcohol, the solubility of each component can be improved, and the storage stability of the water-based rust preventive surface treatment composition obtained can be improved. Although the reason is not clear, the use of the mixed solvent containing water and alcohol can improve the rust prevention performance of the coating formed on the surface of the metal member having the zinc surface. In addition, since alcohol can suppress foaming of the water-based rust preventive surface treatment composition, it is possible to suppress non-uniformity of the siliceous coating due to bubbles entering the coating film.

The content of the alcohol is, for example, 1% by mass to 25% by mass, preferably 3% by mass to 20% by mass, more preferably 5% by mass to 15% by mass, relative to the entire water-based antirust surface treatment composition. be. The long-term storage stability of the water-based rust preventive surface treatment composition can be enhanced by setting the value within such a numerical range.

In addition, the content of the alcohol is, for example, 1% by mass to 40% by mass, preferably 2% by mass to 35% by mass, more preferably 3% by mass, relative to the total content of 100% by mass of the water and alcohol. ~25% by mass. The long-term storage stability of the water-based rust preventive surface treatment composition can be enhanced by setting the value within such a numerical range.

The total content of the silane coupling agent, the water-soluble transition metal compound and the phosphorus-based rust preventive agent is, for example, 3% by mass to 40% by mass in terms of solid content with respect to the entire aqueous rust preventive surface treatment composition, It is preferably 4% to 30% by mass, more preferably 5% to 20% by mass.
By setting the solid content in the water-based antirust surface treatment composition within an appropriate range, the solution stability can be enhanced and the coating can stably exhibit corrosion resistance.

<pH adjuster>
The water-based antirust surface treatment composition contains a pH adjuster.
As the pH adjuster, a known pH adjuster may be appropriately used, and an acidic compound or a basic compound is used. Either a strong or weak acidic compound or a strong or weak basic compound may be used, or a combination of these may be used.

Examples of the acidic compound include hydrochloric acid, nitric acid, sulfuric acid, citric acid, tartaric acid, lactic acid, glycolic acid, sodium citrate, sodium lactate, succinic acid, formic acid, acetic acid, sodium acetate, fumaric acid, malic acid, phosphoric acid, and the like. is mentioned.

Examples of the basic compound include sodium hydroxide, potassium hydroxide, calcium hydroxide, magnesium hydroxide, sodium hydrogen carbonate, disodium hydrogen phosphate, sodium carbonate, potassium carbonate, calcium carbonate, ammonium carbonate, ammonia, morpholine, mono Ethanolamine, dimethylethanolamine, diethanolamine, dimethylamine, diethylamine, triethanolamine, trimethylamine, triethylamine.

As the pH adjuster, from the viewpoint of stability, inorganic acids such as hydrochloric acid, sulfuric acid, and nitric acid, organic acids such as citric acid, acetic acid, and formic acid, alkali metal salts such as sodium hydroxide and potassium hydroxide, sodium hydrogen carbonate, and the like. carbonate, ammonia, monoethanolamine, dimethylethanolamine, triethanolamine, amines such as triethylamine.

<Inorganic colloidal particles>
The water-based antirust surface treatment composition can contain inorganic colloidal particles.
The inorganic colloidal particles are composed of inorganic particles dispersed in water.
By using inorganic colloidal particles, the strength of the film can be increased.

For example, inorganic oxide particles are used as the inorganic particles. The inorganic particles are composed of, for example, one or more selected from the group consisting of SiO ₂ , Al ₂ O ₃ , TiO ₂ , ZrO ₂ , Fe ₂ O ₃ and composites thereof. Specific examples of the inorganic colloidal particles include aqueous colloidal silica and aqueous alumina sol.

By using water-based colloidal silica, the strength of the film obtained from the water-based rust preventive surface treatment composition can be further improved. Moreover, since the dispersibility in the composition can be enhanced, a silica film in which the silica particles are uniformly dispersed in the film can be formed.

The stable pH range of the aqueous colloidal silica is on the acidic side, the neutral side, or the alkaline side. Among these, from the viewpoint of solution stability of the composition, aqueous colloidal silica that is stabilized at an acidic pH can be used.

The inorganic particles have an average particle size of, for example, 1 to 200 nm, preferably 3 to 100 nm. By using nano-sized inorganic particles, aggregation and sedimentation can be suppressed when an aqueous mixed solvent of water and alcohol is used, and a composition excellent in liquid stability can be prepared. In addition, it is possible to improve the antirust performance of products surface-treated with the composition.

By using inorganic colloidal particles such as aqueous colloidal silica, a stronger film structure can be realized.
Although the detailed mechanism is not clear, it is thought that inorganic particles such as silica are appropriately arranged in the spaces in the film, so that the density of the film such as silica film increases and the corrosion resistance improves.

The content of the inorganic colloidal particles is, for example, 0.5% by mass to 15% by mass, preferably 0.8% by mass to 13% by mass, in terms of solid content, based on the entire water-based antirust surface treatment composition. More preferably, it is 1.0% by mass to 12% by mass. By adjusting the amount to be equal to or higher than the above lower limit, appropriate strength can be imparted to the film. By adjusting the content to be equal to or less than the above upper limit value, the physical properties of the film can be balanced.

The content of the inorganic colloidal particles is, for example, 10 parts by mass to 400 parts by mass, preferably 15 parts by mass to 250 parts by mass, more preferably 15 parts by mass to 250 parts by mass, in terms of solid content, with respect to 100 parts by mass of the silane coupling agent. is 20 parts by mass to 190 parts by mass.

<Resin>
The water-based antirust surface treatment composition may contain a water-dispersible resin or a water-soluble resin. A water-dispersible resin is composed of a resin that disperses in water. A water-soluble resin is composed of a resin that dissolves in water. By using these resins, it becomes easy to control the thickness of the coating film. In addition, it becomes possible to improve the abrasion resistance of the coating film and to reduce the hardness of the coating film. For example, when a film is formed on the surfaces of fastener parts such as bolts and nuts, the coefficient of friction of the film can be reduced. From the viewpoint of film formability and corrosion resistance, it is preferable to use a water-dispersible resin.

The resin constituting the water-dispersible resin or water-soluble resin may be appropriately selected from resins that can be dissolved or dispersed in water. Resins, boiled oils, oil-based varnishes, amino resins, urethane resins, vinyl resins, fluorine resins, silicone resins, or modified products thereof can be used. Rubber components such as chlorinated rubber and cyclized rubber can also be used as this resin. These may be used alone or in combination of two or more.

A water-dispersible silicone resin can be used as the silicone resin.
The water-dispersible silicone resin is dispersed in water to form a silicone resin emulsion. The water-dispersible silicone resin can be emulsified with, for example, a nonionic surfactant or an anionic surfactant to form a silicone resin emulsion.

The water-dispersible silicone resin may have a polyorganosiloxane skeleton in the main chain in the molecule. From the viewpoint of film-forming properties and corrosion resistance, the water-dispersible silicone resin may be a self-crosslinking or condensed silicone resin having a crosslinkable functional group such as an alkoxy group in the molecule. From the viewpoint of heat resistance, a silicone resin having an aromatic group such as a phenyl group in the molecule can be used as the water-dispersible silicone resin. In addition, depending on the purpose, the functional groups provided in the molecule of the water-dispersible silicone resin include amino groups, epoxy groups, mercapto groups, long-chain alkyl groups, and the like. The water-dispersible silicone resin may have one or more of the above functional groups in its molecule.

Among these, polyacrylic acid resins, polyester resins, epoxy resins, polyvinyl butyral resins, phenolic resins, and the like are used as water-soluble or water-dispersible resins from the viewpoint of availability and ease of film thickness adjustment. It is preferable to use one or two or more resins selected from the group consisting of modified resins.
From the viewpoint of corrosion resistance, a water-dispersible polyacrylic acid resin or a water-dispersible polyester resin, more preferably a water-dispersible polyacrylic acid resin can be used.
Examples of modified resins (modified resins) include those obtained by subjecting specific resins to silyl modification, phosphoric acid modification, silane modification, and the like.

Although the detailed mechanism is not clear, the water-dispersible resin is softened by heating and almost all of it is incorporated into the film. It is not considered to be For this reason, it is considered that the use of a water-dispersible resin can further enhance the corrosion resistance of the coating as compared with the water-soluble resin.

The content of the above-mentioned water-dispersible resin or water-soluble resin is, for example, 0.5% by mass to 15% by mass, preferably 0.8% by mass, in terms of solid content, with respect to the entire water-based antirust surface treatment composition. ~13% by mass, more preferably 1% to 10% by mass. By making the amount equal to or higher than the above lower limit, the wear resistance and corrosion resistance of the film can be improved. By adjusting the content to be equal to or less than the above upper limit value, the physical properties of the film can be balanced.

The content of the water-dispersible resin or water-soluble resin is, for example, 5 parts by mass to 150 parts by mass, preferably 10 parts by mass to 130 parts by mass, in terms of solid content, with respect to 100 parts by mass of the silane coupling agent. parts by weight, more preferably 20 to 110 parts by weight.

(other ingredients)
The water-based antirust surface treatment composition may contain other additives in addition to the above components.
As other additives, various additives that are usually contained in surface treatment agents can be used. agents and the like. These may be used alone or in combination of two or more. The amount of the additive to be added can be appropriately set according to the application.

Examples of the lubricant include waxes such as polyethylene wax, paraffin wax, and oxidized polyolefin wax.

Examples of the antiseptic agent include isothiazoline compounds.

As an example of the water-based rust preventive surface treatment composition (water-based rust preventive agent) of the present embodiment, all components contained in the composition may be composed of water-soluble components or water-dispersible components. That is, the water-based rust preventive surface treatment composition can be composed of an aqueous solution containing only water-soluble components or water-dispersible components.

In the technical field of water-based rust preventive agents, the content of chromium components in water-based rust preventive agents is restricted from the viewpoint of consideration for the environment. things exist.

On the other hand, the water-based rust preventive surface treatment composition of the present embodiment can be applied to a chromium-free rust preventive agent by making it substantially free of chromium components such as hexavalent chromium and trivalent chromium. . This makes it possible to realize a water-based rust preventive surface treatment composition with reduced environmental load.

From the viewpoint of further improving rust prevention properties, it is possible to include a necessary amount of trivalent chromium. It is preferably limited to 0.5% by mass or less, more preferably 0.5% by mass or less, further preferably 0.1% by mass or less, and substantially free of is particularly preferred.
In this specification, the amounts of hexavalent chromium and trivalent chromium refer to the content of chromium salts having a specific valence.

Next, a method for producing the water-based antirust surface treatment composition of the present embodiment will be described.
The water-based rust preventive surface treatment composition can be prepared by mixing each component and then adjusting the pH with a pH adjuster.
The order in which each component is mixed is not limited and can be mixed in any order.

A film can be formed on the surface of a metal member by a known method using the water-based antirust surface treatment composition. For example, a film can be formed by applying a water-based rust preventive surface treatment composition to the surface of a metal member and drying it. This makes it possible to provide the metal member with antirust performance.

As the coating method, an appropriate method can be used according to the size and shape of the metal member. Examples include immersion, roll coating, spraying, brush coating, spin coating, etc. Various methods can be adopted depending on the situation.

Moreover, it can be made into a firm film|membrane by drying by heat processing.
As the conditions for the heat treatment, for example, the conditions of room temperature or higher and 250° C. or lower can be adopted, and the treatment can be performed for 5 minutes or longer and 240 minutes or shorter.
In addition, by appropriately adjusting the component composition in the water-based antirust surface treatment composition, the heating conditions at a low temperature such as room temperature or higher and 120° C. or lower than the high temperature heating conditions such as 180° C. or higher and 220° C. or lower. However, a firm coating can be formed.

As described above, it is possible to obtain a surface-coated metal member including a metal member having a coating formed on the surface thereof by the water-based rust preventive surface treatment composition.

The surface-coated metal member of the present embodiment can include a metal member and a coating formed on the surface of the metal member and made of the water-based rust preventive surface treatment composition.

The metal material that constitutes the metal member can be appropriately set according to the application. products, etc.

Among these, the water-based rust preventive surface treatment composition of the present embodiment can be suitably used for metal members having a plating layer containing zinc or chromium on the surface. By further forming a film comprising a water-based antirust surface treatment composition on the surface of a metal member having a sacrificial anticorrosion effect such as a plating layer containing zinc or chromium, the rust prevention property of the surface of the metal member can be further enhanced. .

Although the detailed mechanism is not clear, silicon atoms derived from the silane coupling agent in the composition and transition metal atoms derived from the water-soluble transition metal compound are chemically bonded to the surface of the metal member via oxygen atoms. It is also believed that the physical bonding between the film and the metal surface increases the adhesion between the film and the surface of the plating layer of the metal member. Therefore, the anti-corrosion performance of the plating layer can be further enhanced.

Examples of the coating layer include JIS H 8641: hot dip galvanizing, JIS H 8610: electrogalvanizing, JIS H 8625: chromate film (including trivalent Cr), JIS G 3313: electrogalvanized steel sheet, JIS G 3302. : Hot-dip galvanized steel sheet and the like.

In addition, the thickness of the film in the surface-coated metal member can be appropriately set depending on the application. 1.0 μm or more, more preferably 1.0 μm or more. On the other hand, the thickness of the film may be, for example, 50 μm or less, 30 μm or less, or 20 μm or less.

Since the water-based antirust surface treatment composition of the present embodiment can impart excellent antirust properties to metal members, it can be applied to a wide range of applications. It can be used for applications exposed to water, building members, electronic members, and the like. That is, it is expected that the water-based rust preventive surface treatment composition of the present embodiment can be developed for various industrial applications handling metal members.

The uses listed here are examples of embodiments in which the present invention is used, and it goes without saying that the present invention can be applied to uses other than these.

The water-based rust preventive surface treatment composition of the present embodiment can be used continuously for a long period of time as a surface treatment agent by appropriately controlling its pH and solid content concentration. By replenishing the pH adjuster and each component in a timely manner to adjust the pH and solid content concentration in the composition within an appropriate range, for example, it can be used for several months to about a year or more. It is possible.

A method for managing the above composition and a management system for realizing the method will be described below.

The method for managing the water-based rust preventive surface treatment composition of the present embodiment includes a measurement step of measuring at least pH as state data of the composition, and a supply condition of the pH adjuster based on the measured value of pH and the control range of pH. and a supply step of supplying the pH adjuster based on the supply conditions.

The supply conditions can be set using the difference between the pH measurement value and the pH control range. If the measured pH value is high, the setting is such that an acidic compound is used as the pH adjuster, and if the measured pH value is low, a basic compound is selected.
The pH control range can be set to, for example, 2.0 to 9.0, preferably 3.0 to 6.8, and more preferably 4.0 to 5.5. The pH control range can be set in advance according to the components contained in the composition, the properties of the composition, and the like.
As described above, the pH can be measured using a pH meter at a liquid temperature of 25°C ± 1°C.

In the above management method, the measuring step measures pH and solid content concentration as state data of the composition, and the supply condition determining step includes supply conditions for supplying the components of the composition based on the solid content concentration control range. may be determined, and the feeding step may feed the components of the composition based on the feeding conditions.

As components of the above composition, each component may be used alone, or a mixture thereof may be used. Pre-prepared replenishing compositions may also be used.
The control range of the solid content concentration is, for example, 5% to 45% by mass, preferably 8% to 35% by mass, more preferably 13% by mass, in terms of solid content, with respect to the entire water-based antirust surface treatment composition. % to 25% by mass.

With the above management method, it is possible to appropriately manage the pH and solid content concentration of the treatment composition immediately before it is used for the surface treatment of metal members, so that production variations can be reduced and the yield can be improved.

The management method described above can realize both storage and continuous use of the treatment composition in the chemical bath (tank). After use for a predetermined period of time, the processing composition may be discharged and the inside of the chemical bath may be cleaned.

FIG. 1 is a diagram showing the configuration of a management system 10 of this embodiment. The management system 10 includes a chemical bath 100 and a liquid supply device 200 .

The chemical bath 100 may consist of a container that holds a processing composition. The inner surface of the container may be surface-treated by a known method.

The liquid supply device 200 has a measuring unit 210 that measures at least the pH as the state of the treatment composition in the chemical bath 100, and determines the supply condition of the pH adjuster based on the measured pH value and the pH control range. and a supply unit 230 for supplying the pH adjuster to the chemical bath 100 based on the supply conditions.

The measuring section 210 can measure the state of pH, solid content concentration, liquid temperature, etc., and outputs measured value data to the supply condition determining section 220 .

The supply condition determining unit 220 receives the measured value data, and uses the received measured value data to set supply conditions for supplying the pH adjuster and each component of the composition. Information (for example, tables and functions) for determining supply conditions from measured value data may be stored in the liquid supply device 200 or may be stored in an external storage of the liquid supply device 200, for example. As described above, the supply conditions include at least one control parameter for adjusting the state of the treatment composition, such as a pH control range, a solids concentration control range, and the like.

The supply unit 230 has a liquid supply mechanism, and supplies the pH adjuster and each component of the composition into the chemical liquid bath 100 according to the supply conditions output from the supply condition determination unit 220 .
The liquid supply mechanism may comprise at least two tanks, a first dunk filled with a pH adjusting agent and a second tank filled with a replenishing composition.

The supply condition determining unit 220 is realized, for example, by reading a predetermined program by a central processing unit (CPU) of a computer. This program is stored, for example, in a computer memory device or an external storage.

Further, according to the present embodiment, the computer determines the supply conditions of the pH adjuster or each component of the composition to be supplied to the treatment composition using the pH and solid content concentration that indicate the state of the treatment composition. It is possible to provide a program to have the function to

The management system 10 of this embodiment can be used in combination with a metal member manufacturing system. The metal member manufacturing system manufactures plate members such as plated steel sheets and metal members such as processed members such as bolts and nuts. .

The chemical bath 100 and the liquid supply device 200 that constitute the management system 10 can be installed side by side with the manufacturing equipment that constitutes such a manufacturing system. Both can be co-located in the same building. As a result, the chemical tank 100 can be installed adjacent to the heat treatment equipment, so that the treatment composition can be directly supplied to the heat treatment line.

By constructing the management system 10 near the facility where the treatment composition is used in this way, production variations can be reduced and the yield can be improved.

It should be noted that the present invention is not limited to the above-described embodiments, and includes modifications, improvements, etc. within the scope of achieving the object of the present invention.
Examples of reference forms are added below.
1. A water-based rust preventive surface treatment composition used to form a film on the surface of a metal member,
a silane coupling agent;
a water-soluble transition metal compound comprising a water-soluble titanium compound or a water-soluble zirconium compound;
a phosphorus-based rust inhibitor containing a highly condensed phosphate or a polyvalent phosphate;
a solvent comprising water;
and a pH adjuster,
A water-based rust preventive surface treatment composition having a pH of 2.0 to 9.0 at a liquid temperature of 25°C.
2. 1. A water-based rust preventive surface treatment composition according to
A water-based rust preventive surface treatment composition having a pH of 3.0 to 6.8 and being acidic.
3. 1. or 2. A water-based rust preventive surface treatment composition according to
A water-based rust preventive surface treatment composition, wherein the pH adjuster contains an acidic compound.
4. 1. ~3. The water-based rust preventive surface treatment composition according to any one of
The total content of the silane coupling agent, the water-soluble transition metal compound, and the phosphorus-based rust preventive agent is 3% by mass or more and 40% by mass or less with respect to the entire water-based antirust surface treatment composition. Antirust surface treatment composition.
5. 1. ~ 4. The water-based rust preventive surface treatment composition according to any one of
The water-based rust preventive surface treatment composition, wherein the polyvalent phosphate contains phytic acid.
6. 1. ~ 5. The water-based rust preventive surface treatment composition according to any one of
The water-based rust preventive surface treatment composition, wherein the highly condensed phosphate contains a highly condensed phosphate having a cyclic structure.
7. 1. ~6. The water-based rust preventive surface treatment composition according to any one of
The phosphorus-based rust inhibitor contains the highly condensed phosphate and the polyvalent phosphate,
A water-based rust preventive, wherein the total content of the highly condensed phosphate and the polyvalent phosphate is 0.1% by mass or more and 3.0% by mass or less with respect to the entire aqueous rust-preventive surface treatment composition. A surface treatment composition.
8. 1. ~7. The water-based rust preventive surface treatment composition according to any one of
An aqueous antirust surface treatment composition comprising inorganic colloidal particles.
9. 1. ~8. The water-based rust preventive surface treatment composition according to any one of
An aqueous rust preventive surface treatment composition, wherein the solvent is an aqueous mixed solvent containing water and alcohol.
10. 1. ~ 9. The water-based rust preventive surface treatment composition according to any one of
A water-based antirust surface treatment composition comprising a water-dispersible resin or a water-soluble resin.
11. 10. A water-based rust preventive surface treatment composition according to
The water-based antirust surface treatment composition, wherein the water-dispersible resin contains at least one selected from the group consisting of polyacrylic acid resin, polyester resin, epoxy resin, polyvinyl butyral resin, phenolic resin, and modified products thereof.
12. 1. ~ 11. The water-based rust preventive surface treatment composition according to any one of
A water-based antirust surface treatment composition containing no chromium component.
13. 1. ~12. The water-based rust preventive surface treatment composition according to any one of
A water-based anticorrosion surface treatment composition having a plating layer containing zinc or chromium on the surface of the metal member.
14. a metal member;
1. formed on the surface of the metal member; ~ 13. A surface-coated metal member, comprising a film made of the water-based antirust surface treatment composition according to any one of .

EXAMPLES The present invention will be described in detail below with reference to Examples, but the present invention is not limited to the description of these Examples.

Information on each component shown in Table 1 is as follows.
(Silane coupling agent)
・ Epoxysilane 1: 3-glycidoxypropyltriethoxysilane (manufactured by Asahi Kasei Wacker Silicone Co., Ltd., GF-82)
(Water-soluble resin)
・Polyester resin 1: Water-soluble polyester resin (Plascoat Z565, manufactured by GOO CHEMICAL CO., LTD.)
(Water-dispersible resin)
- Polyacrylic acid resin 1: water-dispersible acrylic resin (manufactured by Stahl Polymers)
(Water-soluble transition metal compound)
- Titanium chelating agent 1: Titanium lactate ammonium salt (manufactured by Matsumoto Fine Chemicals, TC-300)
(Inorganic colloidal particles)
- Aqueous colloidal silica 1: (manufactured by Nissan Chemical Industries, Ltd., Snowtex ST-O, acidic sol, particle size: 20 nm)
(Phosphorus rust inhibitor)
・ Highly condensed phosphate 1: Ultra sodium phosphate (manufactured by Kanto Chemical Co., Ltd., network structure in which linear and cyclic ones are mutually bonded)
・ Polyvalent phosphate ester 1: Phytic acid (manufactured by Fuso Chemical Co., Ltd.)
(Preservative)
- Isothiazoline compound 1: Isothiazoline compound (manufactured by Sanai Oil Co., Ltd., IT-25XA)
(solvent)
・Water 1: ion-exchanged water ・Alcohol 1: isopropyl alcohol (manufactured by Daishin Kagaku Co., Ltd.)

The contents of non-solvent components (silane coupling agents, water-soluble resins, water-dispersible resins, water-soluble transition metal compounds, inorganic colloidal particles, phosphorus-based rust inhibitors, and antiseptics) in Table 1 are It represents the solid content conversion value in the surface treatment composition.

[Preparation of water-based antirust surface treatment compositions of samples 1 to 6]
An aqueous solution was obtained by weighing each component according to the compounding ratio (% by mass) shown in Table 1 and mixing each component using a stirrer.
The pH of the resulting aqueous solution was measured immediately after mixing using a pH meter (manufactured by Horiba Estec, product name: glass electrode type hydrogen ion concentration indicator D-51) at a liquid temperature of 25°C.
To the resulting aqueous solution, a 1M hydrochloric acid aqueous solution or a 1M sodium hydroxide aqueous solution is added as a pH adjuster to adjust the pH so that it falls within the pH control range shown in Table 1. A rust surface treatment composition was obtained.
The pH of the obtained water-based antirust surface treatment composition was periodically measured during the storage period after mixing and before use, and a pH adjuster was used so that the pH was within the pH control range shown in Table 1. to control the pH.

Using the water-based rust preventive surface treatment compositions of Samples 1 to 6, the following <continuous salt spray test: SST test> was performed, and the test time (h) at which white rust occurred was measured. Table 1 shows the results.

<Continuous salt spray test: SST test>
An iron hexagon bolt half screw (dimension: M8L35) with a galvanized surface was prepared.
The prepared hexagonal bolt was immersed for 30 seconds in the water-based rust preventive surface treatment composition. After immersion, the hexagonal bolt was taken out and drained for 5 minutes. After that, the hexagonal bolt was heat-treated at 120° C. for 10 minutes to form a silica film made of the water-based rust preventive surface treatment composition on the surface of the hexagonal bolt, thereby preparing a test sample.
Using the obtained test sample, a salt spray test (SST, test temperature: 35° C.) was performed in accordance with JIS Z2371, and the test time (h) at which white rust occurred was measured.

[Preparation of water-based antirust surface treatment composition for combined cycle test]
After diluting the obtained water-based rust preventive surface treatment composition of sample 5 with ion-exchanged water so that the solid content is 20% by mass, a 1M hydrochloric acid aqueous solution or a 1M sodium hydroxide aqueous solution is added as a pH adjuster. was added, ph = 1.8 (sample 7), ph = 2.2 (sample 8), ph = 3.2 (sample 9), ph = 4.4 (sample 10), ph = 5.5 (Sample 11) and ph=6.5 (Sample 12) were prepared.
The following <combined cycle test: CCT test> was performed using the aqueous rust preventive surface treatment compositions of Samples 7 to 12 immediately after preparation. The results are shown in samples 7-12 of Table 2, FIG.

In addition, in the following <combined cycle test: CCT test>, a hexagonal bolt with no silica film formed on the surface without using the water-based rust preventive surface treatment composition was used as a test sample, and the evaluation was performed in the same manner. did The results are shown in Table 2 and Figure 2 as "Blank".

<Combined cycle test: CCT test>
Five unichromate-treated flanged hexagon bolts (dimension: M6L25) were prepared. The water-based antirust surface treatment composition was diluted 80% with water, and the prepared hexagon bolts were immersed in the solution for 30 seconds. . After immersion, the hexagonal bolt was taken out and drained for 5 minutes. After that, the flat plate was heat-treated at 120° C. for 10 minutes to form a silica film made of the water-based antirust surface treatment composition on the surface of the hexagonal bolt to prepare a test sample.
Using the obtained test samples, a combined cycle test was performed according to JASO M 609, and the number of test cycles at which white rust or red rust occurred was measured.
In addition, the number of hexagon bolts with white rust or red rust was measured at 9, 24 and 30 cycles.
Evaluation criteria are as follows.
◎: 1 or less white rust ○: 2 or more white rust △: 2 or more red rust ×: All 5 are red rust

Based on the results in Table 2, it was shown that the water-based rust preventive surface treatment compositions of Samples 8 to 12 were able to suppress the generation of red rust in the combined cycle test compared to Sample 7 and blank. It was also shown that the water-based rust preventive surface treatment compositions of Samples 9 to 12 can suppress the generation of white rust in the combined cycle test compared to Sample 8.

Red rust is the rust of the material itself, such as bolts, and may cause deterioration in the functionality of the material. White rust is basically dissolved zinc to form zinc hydroxide, and has a sacrificial anti-corrosion function that suppresses corrosion of materials.

<Observation of pH over time>
For the obtained water-based rust preventive surface treatment compositions of Samples 1 and 2, no pH adjuster was added during the storage period after mixing, and at room temperature (25 ° C.), a lidded storage container (100 mL polyethylene bottle, AS ONE manufactured by I-BOY). The pH of Samples 1 and 2 in the storage container was periodically measured using a pH meter (manufactured by Horiba Estec, product name: glass electrode type hydrogen ion concentration indicator D-51) at a liquid temperature of 25°C. The results are shown in FIG.

Based on the results of FIG. 3, in the water-based rust preventive surface treatment compositions of samples 1 and 2, when stored in a storage container at room temperature (25 ° C.) without adding a pH adjuster, the pH was shown to fluctuate. Decomposition of components contained in the water-based anticorrosive surface treatment composition, volatilization of decomposed products, and the like are considered to be factors that cause the pH to fluctuate.

<pH management>
After adjusting the pH of the water-based rust preventive surface treatment composition of sample 5 to 4.3, it was stored at room temperature (25°C) in a covered storage container (100 mL polyethylene bottle, I-BOY manufactured by AS ONE). and stored for 2 months. It showed pH=5.8 after 2 months. Immediately thereafter, the pH was readjusted to 4.5 using a 1M hydrochloric acid aqueous solution as a pH adjuster.

The above <combined cycle test: CCT test> was performed on Sample 5 at the initial stage (pH = 4.3), after 2 months (pH = 5.8), and after pH readjustment (pH = 4.5), and red rust was observed. was measured. The results are shown in FIG.

Based on the results of FIG. 4, in the water-based rust preventive surface treatment composition of sample 5, even if the pH is outside the control range shown in Table 1 due to storage for a predetermined period, the pH is readjusted using a pH adjuster. can. Sample 5 after the pH readjustment showed a pH level equivalent to that of the initial period, and it was shown that the effect of suppressing the generation of red rust in the combined cycle test recovered to the same extent as compared with the initial period.

<Evaluation of phosphorus-based rust inhibitor>
In the resulting water-based rust preventive surface treatment composition of Sample 4, the content ratio of the ion-exchanged water (solvent) and the phosphorus-based rust preventive agent in the composition was adjusted so that highly condensed phosphorus in 100% by mass of the composition After changing the content ratio (% by mass) of the acid salt 1 (sodium ultraphosphate) and the polyvalent phosphate ester 1 (phytic acid) to the values shown in Table 3, a pH adjuster was added to obtain 4 The pH was adjusted to be within the range of 0 to 4.5, and samples 13 to 17 of water-based rust preventive surface treatment compositions were obtained.
Using the water-based rust preventive surface treatment compositions of Samples 13 to 17 immediately after pH adjustment, the above <continuous salt spray test: SST test> was performed, and the test time (h) at which white rust occurred was measured. Table 3 shows the results.

The water-based rust preventive surface treatment compositions of Samples 4, 14, 16 and 17 increased the total content ratio of the highly condensed phosphate and the polyvalent phosphate as compared with Sample 13, resulting in white rust generation. can be suppressed.
In addition, the water-based rust preventive surface treatment compositions of Samples 4, 14, 16 and 17 were shown to be able to suppress the generation of white rust by increasing the content ratio of the polyvalent phosphate ester compared to Sample 15. was done.

From the above, considering the results of the above combined cycle test, the water-based rust preventive surface treatment compositions of Examples 1 to 5 have a pH within an appropriate range compared to Comparative Examples 1 and 2. , it was found that the corrosion resistance of the film can be improved because the generation of red rust can be suppressed. By treating the surface with such a water-based rust preventive surface treatment composition, it is possible to improve the rust preventiveness of the metal member.

10 Management system 100 Chemical tank 200 Liquid supply device 210 Measurement unit 220 Supply condition determination unit 230 Supply unit

Claims (12)

A water-based rust preventive surface treatment composition used to form a film on the surface of a metal member,
a silane coupling agent;
a water-soluble transition metal compound comprising a water-soluble titanium compound or a water-soluble zirconium compound;
a phosphorus-based rust inhibitor containing a highly condensed phosphate and a polyvalent phosphate;
a solvent comprising water;
and a pH adjuster,
The total content of the highly condensed phosphate and the polyvalent phosphate is 0.1% by mass or more and 3.0% by mass or less with respect to the entire water-based rust preventive surface treatment composition,
A water-based rust preventive surface treatment composition having a pH of 2.0 to 9.0 at a liquid temperature of 25°C. The aqueous rust preventive surface treatment composition according to claim 1,
A water-based rust preventive surface treatment composition having a pH of 3.0 to 6.8 and being acidic. The water-based rust preventive surface treatment composition according to claim 1 or 2,
A water-based rust preventive surface treatment composition, wherein the pH adjuster contains an acidic compound. The aqueous rust preventive surface treatment composition according to any one of claims 1 to 3,
The total content of the silane coupling agent, the water-soluble transition metal compound, and the phosphorus-based rust preventive agent is 3% by mass or more and 40% by mass or less with respect to the entire water-based antirust surface treatment composition. Antirust surface treatment composition. The aqueous rust preventive surface treatment composition according to any one of claims 1 to 4,
The water-based rust preventive surface treatment composition, wherein the polyvalent phosphate contains phytic acid. The aqueous rust preventive surface treatment composition according to any one of claims 1 to 5,
The water-based rust preventive surface treatment composition, wherein the highly condensed phosphate contains a highly condensed phosphate having a cyclic structure. The aqueous rust preventive surface treatment composition according to any one of claims 1 to 6 ,
An aqueous antirust surface treatment composition comprising inorganic colloidal particles. The aqueous rust preventive surface treatment composition according to any one of claims 1 to 7 ,
An aqueous rust preventive surface treatment composition, wherein the solvent is an aqueous mixed solvent containing water and alcohol. The water-based rust preventive surface treatment composition according to any one of claims 1 to 8 ,
A water-based antirust surface treatment composition comprising a water-dispersible resin or a water-soluble resin. The aqueous rust preventive surface treatment composition according to claim 9 ,
The water-based antirust surface treatment composition, wherein the water-dispersible resin contains at least one selected from the group consisting of polyacrylic acid resin, polyester resin, epoxy resin, polyvinyl butyral resin, phenolic resin, and modified products thereof. The aqueous rust preventive surface treatment composition according to any one of claims 1 to 10 ,
A water-based antirust surface treatment composition containing no chromium component. The aqueous rust preventive surface treatment composition according to any one of claims 1 to 11 ,
A water-based anticorrosion surface treatment composition having a plating layer containing zinc or chromium on the surface of the metal member.

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