JP2009161830A - Blocked isocyanate group-containing organosiloxane, and composition for metal surface treatment using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a composition for metal surface treatment, from which a chemical film having excellent coating film adhesion and corrosion resistance can be formed. <P>SOLUTION: Blocked isocyanate group-containing organosiloxane comprising as a monomer an organosilane having a hydrolyzable silicon-containing group and a reactive functional group is disclosed, wherein a blocked isocyanate group is comprised as the reactive functional group. A composition for metal surface treatment comprising the blocked isocyanate group-containing organosiloxane and water is also disclosed. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a blocked isocyanate group-containing organosiloxane and a metal surface treatment composition using the same.

  In general, when a metal substrate is coated, surface treatment is performed from the viewpoint of ensuring corrosion resistance and adhesion of the coating film. In particular, when painting metal structures with curved surfaces or bent parts (for example, automobile bodies and other complex metal structures), a reactive surface treatment (chemical conversion) that chemically forms a chemical conversion coating on the metal surface. Processing).

  As an example of the chemical conversion treatment, there is a chromate chemical conversion treatment with chromate. However, the harmful effects of chromium have been pointed out. In recent years, treatment with zinc phosphate-based treatment (zinc phosphate treatment) is known as a treatment agent (surface treatment agent, chemical conversion treatment agent) that does not contain chromium. (Patent Document 1).

  However, the zinc phosphate-based treatment agent has the following problems. First, since it is a highly reactive treatment agent having a high metal ion concentration and an acid concentration, the economical efficiency and workability in wastewater treatment are not good. Second, with the metal surface treatment with a zinc phosphate-based treatment agent, water-insoluble salts are generated and deposited as precipitates, so the cost of removing and discarding such precipitates (sludge) Etc. are required. Thirdly, since phosphate ions may cause a load on the environment due to eutrophication, the waste liquid treatment requires labor and is preferably not used. Fourthly, in the metal surface treatment with a zinc phosphate-based treatment agent, it is necessary to adjust the surface, and the process becomes longer.

  As a treatment agent other than such a zinc phosphate-based treatment agent or a chromate chemical conversion treatment agent, a chemical conversion treatment agent containing a zirconium compound is known (Patent Document 2). Since the chemical conversion treatment agent comprising this zirconium compound is a treatment agent having a metal ion concentration and an acid concentration that are not so high and reactivity is not so high, economical efficiency and workability in wastewater treatment are good. Moreover, it has the property excellent compared with the zinc phosphate type processing agent as mentioned above by the generation | occurrence | production of sludge being suppressed.

Moreover, the chemical conversion treatment agent containing the amino group containing silane coupling agent with the zirconium compound is also provided (patent document 3). According to this chemical conversion treatment agent, zirconium acts as a component for forming a chemical conversion film, and the amino group-containing silane coupling agent acts not only on the surface of the metal substrate but also on the coating film formed after the chemical conversion treatment. Thereby, the adhesiveness of a chemical conversion film and a coating film can be improved.
Japanese Patent Laid-Open No. 10-204649 JP 2003-155578 A Japanese Patent Application Laid-Open No. 2004-218070

However, in the present situation where advanced surface treatment technology is required, development of a metal surface treatment agent that can provide even better coating film adhesion and corrosion resistance is desired.
Then, an object of this invention is to provide the metal surface treating agent which can form the surface protective film which has the outstanding coating-film adhesiveness and corrosion resistance.

In order to solve the above problems, the present inventor has developed a new organosiloxane and completed a surface treatment composition using the organosiloxane.
According to the first aspect of the present invention, an organosiloxane comprising, as a monomer, an organosilane having a hydrolyzable silicon-containing group and a reactive functional group, wherein a blocked isocyanate group is used as the reactive functional group. A blocked isocyanate group-containing organosiloxane is provided.

  According to a second aspect of the present invention, there is provided a metal surface treatment composition comprising the blocked isocyanate group-containing organosiloxane according to the first aspect of the present invention and water.

According to the third aspect of the present invention, the metal surface treatment composition according to the second aspect of the present invention is applied to the metal substrate, and then dried without washing with water to protect the surface of the metal substrate. A method for producing a surface-coated metal substrate is provided, comprising the step of forming a film.
According to the fourth aspect of the present invention, the surface-coated metal further comprises a step of washing the metal substrate with water after contacting the metal surface treatment composition according to the second aspect of the present invention with the metal substrate. A method of manufacturing a substrate is provided.

  According to the fifth aspect of the present invention, after the surface-coated metal substrate is produced by the production method according to the third aspect of the present invention, a paint is applied to the surface of the surface-coated metal substrate to form a coating film. Provided is a method for producing a metal-coated product, comprising a step of forming and a step of heating and drying the coating film.

The blocked isocyanate group-containing organosiloxane used in the present invention has a blocked isocyanate group. This blocked isocyanate group is stably present in the metal surface treatment composition, but when the blocking group is removed by heating or the like, the activity of the isocyanate group is expressed.
Therefore, the metal surface treatment composition according to the present invention containing this blocked isocyanate group-containing organosiloxane is excellent in storage stability as a treatment liquid, and after drying the surface by forming a surface protective film on the metal substrate. By removing the blocking group and expressing the activity of the isocyanate group, a protective film having excellent adhesion and corrosion resistance can be formed on the surface of the metal substrate.

<Blocked isocyanate group-containing organosiloxane>
The blocked isocyanate group-containing organosiloxane according to the present invention (hereinafter also referred to as “organosiloxane A”) comprises at least one organosilane having a hydrolyzable silicon-containing group and a reactive functional group as a monomer. An organosiloxane that contains a blocked isocyanate group as the reactive functional group.
Organosiloxane A is preferably an organosiloxane further containing an amino group and / or a glycidyl group as a reactive functional group (hereinafter also referred to as “organosiloxane B”).
In the following description, organosiloxane A and organosiloxane B may be collectively referred to as organosiloxane. Each of the organosiloxanes A and B may be a single polycondensate composed of a single monomer or a copolycondensate containing a plurality of monomers, and these are collectively referred to as a polycondensate. In some cases, single polycondensation and copolycondensation are collectively referred to as polycondensation.

  Since the organosiloxane acts on both the surface of the metal substrate and the coating film formed after the surface treatment, the adhesion between them can be improved. Such an effect is achieved by the fact that silanol in the organosiloxane acts on the surface of the metal substrate in a hydrogen bond, and that the isocyanate group acts on the coating film in a chemical bond or a hydrogen bond. It is presumed that this occurs because the adhesion between the film and the metal substrate is increased.

In the organosiloxane of the present invention, the isocyanate group (—N═C═O) is blocked like —N—C (═O) —OR (R is a blocking group). It is removed by a subsequent heat-drying treatment to generate an isocyanate group. This highly active isocyanate group is chemically bonded to various functional groups in the coating film (for example, hydroxy group, amino group, etc.), or reacts with another functional group in the chemical conversion film, resulting in higher adhesion. It is considered that a denser chemical film can be formed. Furthermore, it is considered that the detached blocking group (—OR) also contributes to the improvement of corrosion resistance.
Thus, it is thought that the mutual adhesion improves by the organosiloxane contained in the chemical conversion film acting on both the metal substrate and the coating film.

As described above, the isocyanate group which is a reactive functional group having high activity is stably present because it is blocked in the metal surface treatment composition (hereinafter also referred to as “treatment liquid”). Therefore, this processing liquid is excellent in storage stability.
If the storage stability of the treatment liquid is poor, there is a problem that the chemical conversion film having the performance as in the beginning of use cannot be formed due to deterioration in a short time after the start of use. In particular, a metal surface treatment composition for large metal substrates such as automobile bodies and parts has been desired to have a long treatment solution life because of its large treatment bath capacity. This organosiloxane meets these requirements.

  Once the organosilane is polymerized to form an organosiloxane, it is not easily hydrolyzed even when diluted, and is not easily monomerized. The reason why the organosiloxane is stable in an aqueous solution is that the Si—O—Si bond energy of the organosiloxane is very large compared to the Si—O—C bond energy. Therefore, even when blended in the composition for metal surface treatment, the organosiloxane is present in a relatively stable manner and is considered to contribute to improving the adhesion of the chemical conversion film by being effectively incorporated into the chemical conversion film. It is done.

Organosiloxane B contains various functional groups of the coating film when used in a chemical conversion treatment agent by containing amino groups and / or glycidyl groups in addition to blocked isocyanate groups as reactive functional groups. It becomes easier to chemically bond or hydrogen bond with the group, and a chemical conversion film with higher adhesion and affinity to the coating film can be formed.
The amino group or glycidyl group can react with the isocyanate group in the chemical conversion film to form a denser chemical conversion film.

  In addition, in the case of this organosiloxane B containing an amino group, when this is used as a zirconium-based reactive surface treatment agent, the organosiloxane is co-precipitated during the formation of the zirconium conversion film due to the basicity of the amino group. This is thought to facilitate the rapid formation of a chemical conversion film. Furthermore, the neutralization effect of silanol by an amino group (an effect of relaxing the polarization of silanol) is obtained, and it is considered that organosiloxane B exists more stably in an aqueous solution.

  For example, the above-mentioned organosiloxane A is a single or copolycondensate containing at least one isocyanate silane having a blocked isocyanate group and a hydrolyzable silicon-containing group (hereinafter also referred to as “isocyanate silane M1”) as a monomer. It is.

For example, the organosiloxane B includes at least one kind of the isocyanate silane M1, and an organosilane having an amino group and / or glycidyl group and a hydrolyzable silicon-containing group (hereinafter also referred to as “organosilane M2”). It is a copolycondensate used as a monomer.
Alternatively, organosiloxane B is at least one isocyanate silane having a blocked isocyanate group, a hydrolyzable silicon-containing group, an amino group and / or a glycidyl group (hereinafter referred to as “isocyanate silane M3”). Or a copolycondensate containing a monomer as a monomer.

Here, the above-mentioned isocyanate silane M1, organosilane M2, and isocyanate silane M3, which are monomers constituting organosiloxane, may be collectively referred to as “organosilane”. That is, organosilane refers to a reactive monomer that constitutes organosiloxane.
As other monomers other than these organosilanes M1 to M3 used in the case of the copolycondensate, a silane having a polycondensable functional group such as a general alkoxysilane (organosilane M4 described later) is used. Can be mentioned.

The isocyanate silane M1 is a compound having at least one isocyanate group and at least one hydrolyzable silicon-containing group in one molecule. The hydrolyzable silicon-containing group is a hydrolyzable functional group such as —SiOR (R is an alkyl group) and —SiOX (X is a halogen such as Cl).
That is, isocyanate silane M1 is a monovalent substituent such as SiR ₄ (wherein four Rs are each independently hydrogen, hydroxy group, alkyl group, alkoxy group, —OX (X is halogen)), and at least one R Is an alkoxy group or a hydrolyzable group such as —OX, and at least one R includes an isocyanate group.

More specifically, as a preferred example, isocyanate silane M1 can be represented by the following general formula (1).
[Chemical formula 1]
^{_{R 1 m -Si (OR 2)}} 3-m -R 3 -NCO (1)
In the general formula (1), m is 0, 1, or 2, R ¹ represents hydrogen, an alkyl group having 1 to 6 carbon atoms or a hydroxy group, and R ² represents an alkyl group having 1 to 3 carbon atoms. , R ³ represents an alkylene group having 1 to 6 carbon atoms. R ³ is more preferably an alkylene group having 4 to 6 carbon atoms.

  More specific examples of preferred compounds include 3-isocyanatopropyltriethoxysilane and 3-isocyanatopropyltrimethoxysilane.

  The isocyanate silane M1 can be obtained, for example, by reacting an isocyanate group-containing compound with a compound having a functional group capable of reacting with an isocyanate group and a hydrolyzable silicon-containing group. Specifically, for example, isocyanate silane M1 can be synthesized by reacting a diisocyanate such as methylene diisocyanate or tolylene diisocyanate with a silane coupling agent such as aminoalkoxysilane or mercaptoalkoxysilane.

Organosilane M2 is a compound having at least one amino group or glycidyl group and at least one hydrolyzable silicon-containing group in one molecule.
That is, organosilane M2 is a monovalent substituent such as SiR ₄ (wherein four Rs are each independently hydrogen, hydroxy group, alkyl group, alkoxy group, —OX (X is halogen)), and at least one R Is an alkoxy group or a hydrolyzable group such as —OX, and at least one R includes an amino group or a glycidyl group. The amino group may be an N-substituted amino group, but is preferably an —NH ₂ group which is all hydrogen.

More specifically, as a preferred example, the organosilane M2 can be represented by the following general formula (2), for example.
[Chemical formula 2]
^{_{R 1 m -Si (OR 2)}} 3-m -R 3 -Y (2)
In the general formula (2), m is 0, 1, or 2, R ¹ represents an alkyl group having 1 to 6 carbon atoms or a hydroxy group, R ² represents an alkyl group having 1 to 3 carbon atoms, and R 1 ³ represents an alkylene group having 1 to 6 carbon atoms or an iminoalkyl group (—NH—R—), and Y represents an —NH ₂ group or a glycidyl group. Since the imino group is a functional group that contributes to the adhesion of the coating film in the same manner as the amino group, R ³ is preferably an iminoalkyl group.

When Y is a glycidyl group, m is more preferably 0 or 1, and R ³ is more preferably an alkylene group having 3 to 6 carbon atoms.
More specifically, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane and the like can be exemplified as preferable compounds.

When Y is an amine, m = 0, Y is —NH ₂ , R ³ is —C ₃ H ₆ NHC ₂ H ₄ —, and R ² is a methyl group. N- (2-aminoethyl) -3-aminopropyl Trimethoxysilane; or m = 0, Y is —NH ₂ , R ³ is a propylene group, R ² is a methyl group, and 3-aminopropyltriethoxysilane, as well as N- (2-aminoethyl) -3-aminopropyl Methyldimethoxysilane, N- (2-aminoethyl) -3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane and the like are preferable.

  Commercially available silane coupling agents include amino group-containing silane coupling agents KBM-403, KBM-602, KBM-603, KBE-603, KBM-903, KBE-903, KBE-9103, KBM- 573 (manufactured by Shin-Etsu Chemical Co., Ltd.), XS1003 (manufactured by Chisso Corporation), or the like can be used.

Isocyanatosilane M3 is a monovalent substituent such as SiR ₄ (wherein four R's are each independently hydrogen, hydroxy group, alkyl group, alkoxy group, -OX (X is halogen)), and at least one R is an alkoxy group. A group or a hydrolyzable group such as -OX, wherein at least one R contains an isocyanate group, and at least one R contains an amino group or a glycidyl group).

Other organosilanes M4 other than organosilanes M1 to M3 that can be used for a part of organosiloxanes A and B have hydrolyzable silicon-containing groups and are composed of isocyanate groups, amino groups, or glycidyl groups. It is a polycondensable silane containing no reactive functional group.
Specifically, as organosilane M4, vinyltrimethoxysilane, vinyltriethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, p-styryltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-ureidopropyltriethoxysilane, 3-chloropropyl Examples thereof include trimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, bis (triethoxysilylpropyl) tetrasulfide, and the like.

Organosiloxane A can be preferably produced, for example, by blocking the isocyanate group of the isocyanate silane M1 using a blocking agent and hydrolyzing and condensing the resulting blocked isocyanate silane M1. As the monomer, plural kinds of blocked isocyanate silanes M1 may be used, or organosilanes M4 such as alkoxysilanes may be used in combination.
Organosiloxane B is preferably produced, for example, by blocking the isocyanate group of the isocyanate silane M1 using a blocking agent and hydrolyzing and condensing the resulting blocked isocyanate silane M1 with the organosilane M2. Can do. As the monomer, a plurality of types of blocked isocyanate silanes M1 and a plurality of types of organosilanes M2 may be used, or organosilanes M4 such as alkoxysilanes may be used in combination.

  In the case of producing a copolycondensate, for example, an isocyanate group such as isocyanatesilane M1 may be first blocked, hydrolyzed and polycondensed, and then copolycondensed with another organosilane M4.

As a blocking agent for isocyanate silane M1, for example,
monovalent alkyl (or aromatic) alcohols such as n-butanol, n-hexyl alcohol, 2-ethylhexanol, lauryl alcohol, phenol carbinol, methylphenyl carbinol;
Cellosolves such as ethylene glycol monohexyl ether and ethylene glycol mono 2-ethylhexyl ether;
Phenols such as phenol, para-t-butylphenol, cresol;
Oximes such as dimethyl ketoxime, methyl ethyl ketoxime, methyl isobutyl ketoxime, methyl amyl ketoxime, cyclohexanone oxime;
lactams such as ε-caprolactam and γ-butyrolactam;
Can be mentioned. These can be used alone or in combination of two or more. Of these, various alcohols, phenols, and oximes are preferably used.

Blocking may be performed on all isocyanate groups or only on some isocyanate groups. In particular, when an organosiloxane that does not contain a cationic functional group such as an amino group is used as a reactive chemical conversion treatment agent, it is preferable to leave a part of the isocyanate group without blocking it. As a result, the isocyanate group becomes cationic, and the chemical film forming component (zirconium) and the organosiloxane in the treatment liquid can be co-deposited.
Therefore, the blocking agent should just select the reaction equivalent according to the desired degree of blocking, It is preferable to make it react by 0.2-2 equivalent with respect to 1 equivalent of isocyanate groups, 0.5-1.2 More preferably, the reaction is performed in an equivalent amount.

The molecular weight of the organosiloxane is not particularly limited, but when the dimer or higher, more preferably the trimer or higher, forms a chemical film as zirconium or hydroxide or oxide, Since it tends to be taken in, it is preferable in order to improve the adhesion between the coating film and the metal substrate.
Therefore, when the polysilane is subjected to a polycondensation reaction, the organosilane is preferably reacted under a condition that the organosilane is more easily hydrolyzed and polycondensed.

  The conditions under which organosilane is more easily hydrolyzed and polycondensed include, for example, reaction conditions in which the solvent is an alcohol, and reaction conditions by blending organosilane that results in copolycondensation rather than single polycondensation, etc. It is. Further, by reacting under a condition where the organosilane concentration is relatively high, an organosiloxane having a higher molecular weight and a higher polycondensation rate can be obtained. Specifically, it is preferable to carry out polycondensation reaction within a range of organosilane concentration in the range of 5 mass% to 70 mass%, more preferably 5 mass% to 50 mass%, and more preferably 5 mass% to 40 mass%. % Or less is more preferable, and 5% by mass or more and 30% by mass or less is particularly preferable.

Furthermore, in order to obtain a metal surface treatment composition having good storage stability in addition to the above adhesion, it is preferable that the organosiloxane is difficult to dissociate into organosilane.
Organosiloxanes that are difficult to dissociate into organosilanes are those in which siloxane bonds are not easily hydrolyzed, or even if siloxane bonds are hydrolyzed, they are all difficult to be completely hydrolyzed to organosilane monomers. Refers to an organosiloxane that does not easily hydrolyze due to its chemical structure, an organosiloxane that does not dissociate into an organosilane monomer by one hydrolysis.

As organosiloxane that is difficult to dissociate into organosilane,
(I) an organosiloxane that is a polycondensate of isocyanate silane in which the nitrogen atom of the terminal isocyanate group and the silicon atom of the silyl group are separated by 4 atoms or more;
(Ii) an organosiloxane that is a polycondensate of organosilane in which the nitrogen atom of the terminal amino group or the carbon atom of the terminal glycidyl group and the silicon atom of the silyl group are separated by 4 atoms or more;
(Iii) Organosiloxane having a branched structure; and (iv) In the organosiloxane, the proportion of silicon atoms bonded to two or more other silicon atoms via oxygen atoms constituting the siloxane bond is a composition for metal surface treatment. The organosiloxane which is 20 mol% or more with respect to the total molar amount of the silicon atom which the organosiloxane and unreacted organosilane which are contained in a thing have is mentioned.

The “(i) organosiloxane which is a polycondensate of isocyanate silane in which the nitrogen atom of the terminal isocyanate group and the silicon atom of the silyl group are separated by 4 atoms or more” is the general formula (1), R ³ is a group in which 4 or more atoms are bonded.
Such an isocyanate silane may be used in combination with an isocyanate silane that is not (the number of R ³ atoms in the general formula (1) is 3 or less).

The above “(ii) organosiloxane which is a polycondensation product of organosilane in which the nitrogen atom of the terminal amino group or the carbon atom of the terminal glycidyl group and the silicon atom of the silyl group are separated by 4 atoms or more” In the general formula (2), R ³ is a group in which 4 or more atoms are bonded. For example, N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropyltri An ethoxysilane etc. are mentioned. In any of these, since the nitrogen atom of the terminal amino group and the silicon atom of the silyl group are separated from each other by 6 or more atoms, the storage stability of the metal surface treatment composition is improved by using them. . Furthermore, since these organosilanes all have a terminal amino group and an imino group, the adhesion to the coating film is good based on these functional groups.
Such organosilanes and organosilanes that are not (the number of R ³ atoms in the general formula (2) is 3 or less) (for example, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, etc.) ) May be used in combination.

  If the distance between the nitrogen atom of the terminal amino group and the silicon atom of the silyl group is 3 atoms or less, the terminal amino group hydrolyzes the siloxane bond in the diluted aqueous solution, and the silane bond alone as an organosilane rather than as an organosiloxane. In order to stabilize, the dissociation of the organosiloxane is considered to proceed easily, whereas when the distance between the nitrogen atom of the terminal amino group and the silicon atom of the silyl group is 4 or more atoms, the terminal amino group is converted to siloxane. It is presumed that this is because it is difficult to form a structure that easily hydrolyzes the bonded portion and the dissociation of organosiloxane does not proceed easily.

“(Iii) Organosiloxane having a branched structure” means that the organosiloxane has a branched structure instead of a linear structure by polycondensation of organosilane, or the organosilane itself constituting the organosiloxane has a branch. Say things.
When the organosiloxane has a branched structure, the siloxane bond has a three-dimensional structure that is difficult to be hydrolyzed due to steric hindrance, or the organosiloxane having a branched structure cannot be completely decomposed into an organosilane by one hydrolysis. Can be considered.

  In order to obtain an organosiloxane having a branched structure, means for adjusting the organosilane concentration to 3% by mass or more and / or adjusting the pH to 6 to 14 in the polycondensation reaction are effective. If the concentration of the organosilane is less than 3% by mass, polycondensation may not proceed easily. If the pH is less than 6, polycondensation tends to proceed linearly. The organosilane concentration at this time is preferably 5% by mass or more, more preferably 10% by mass or more. Moreover, pH at this time becomes like this. Preferably it is 7-13, More preferably, it is 8-13.

In the organosiloxane of the above (iv), “the silicon atom bonded to two or more other silicon atoms via the oxygen atom constituting the siloxane bond” is as follows. For example, when the organosiloxane is a polycondensate of an organosilane having three alkoxy groups bonded to a silicon atom, that is, polycondensation of an organosilane in which m is 0 in the above general formula (1) or (2) When it is a product, “in the organosiloxane, a silicon atom bonded to two other silicon atoms via an oxygen atom constituting a siloxane bond” means that three alkoxy groups obtained by hydrolysis of these alkoxy groups. Among the silanol groups, a silicon atom having one silanol group that is not condensed to form a siloxane bond is applicable.
Further, “in the organosiloxane, a silicon atom bonded to other three silicon atoms through an oxygen atom constituting a siloxane bond” means that among these three silanol groups obtained by hydrolysis of these alkoxy groups. This corresponds to a silicon atom having zero silanol groups which are not condensed to form a siloxane bond.

  When the organosiloxane is a polycondensate of an organosilane having two alkoxy groups bonded to a silicon atom, that is, a polycondensate of an organosilane in which m is 1 in the above general formula (1) or (2) Sometimes, in "organosiloxane, a silicon atom bonded to two other silicon atoms through an oxygen atom constituting a siloxane bond" includes two silanol groups obtained by hydrolysis of the alkoxy group. This corresponds to a silicon atom having zero silanol groups which are not condensed to form a siloxane bond.

  The presence of this “silicon atom bonded to two or more other silicon atoms through an oxygen atom constituting a siloxane bond in an organosiloxane” indicates that the organosiloxane is at least a trimer or more. Is. In organosiloxane, the fact that the ratio of the trimer or higher multimer is large is considered to improve not only the adhesion but also the storage stability of the metal surface treatment composition. As a mechanism for improving the storage stability, when the organosiloxane is a trimer or more, it is easy to have a structure in which the siloxane bond is not easily hydrolyzed. In this case, it is assumed that not all of them are dissociated into organosilane.

The ratio of the above “silicon atom bonded to two or more other silicon atoms through oxygen atoms constituting the siloxane bond in the organosiloxane” is determined by the ratio between the organosiloxane contained in the metal surface treatment composition and the unreacted Preferably it is 20 mol% or more with respect to the total amount of silicon atoms which organosilane has, More preferably, it is 25 mol% or more, More preferably, it is 30 mol% or more, More preferably, it is 35 mol% or more. Especially preferably, it is 40 mol% or more.
Here, in the metal surface treatment composition, unreacted organosilane in the polycondensation reaction during the synthesis of organosiloxane may be present, but the total amount of silicon atoms includes silicon atoms of these unreacted organosilanes. It is a thing. The unreacted organosilane refers to an organosilane that has not been polycondensed, and includes organosilane that has been hydrolyzed after being once converted to organosiloxane by polycondensation.

  As described above, it is considered that the storage stability is improved if the degree of polymerization of the organosiloxane is large. Therefore, “organosiloxane is bonded to three or more other silicon atoms via oxygen atoms constituting the siloxane bond. The ratio of “the silicon atom” is preferably 10 mol% or more, more preferably 15 mol, based on the total amount of silicon atoms contained in the organosiloxane and the unreacted organosilane contained in the metal surface treatment composition. % Or more, more preferably 20 mol% or more, still more preferably 30 mol% or more, and particularly preferably 50 mol% or more.

If the organosiloxane satisfies any one of the above (i) to (iv), a metal surface treatment composition having good storage stability can be obtained. Among the above (i) to (iv) It is more preferable to satisfy 2 or more.
For example, the organosiloxane is more preferably the organosiloxane of (ii) and (iii). This is because a tetramer or higher multimer has a branched structure, so that it is considered to have a three-dimensional structure that is more difficult to dissociate.
Further, the organosiloxane is more preferably the organosiloxane of (i) and the organosiloxane of (ii) and / or (iii). In this case, in addition to the three-dimensional structure that is difficult to dissociate into organosilane, the effect of having four or more atoms in the main chain between the nitrogen atom of the terminal amino group and the silicon atom of the silyl group is obtained.

<Composition for metal surface treatment>
The metal surface treatment composition is used for metal surface treatment, and contains the blocked isocyanate group-containing organosiloxane (that is, organosiloxane A and / or organosiloxane B) and water. This composition is further diluted and prepared with water as necessary at the time of use, and used for metal surface treatment as a metal surface treatment liquid.

When this metal surface treatment composition is used as a reactive chemical conversion treatment agent, it is preferable to include a zirconium compound as a chemical conversion film forming component. By forming a chemical conversion film containing zirconium as the metal substrate is etched, the corrosion resistance and wear resistance of the metal substrate can be improved.
The zirconium compound is not particularly limited, and examples thereof include alkali metal fluorozirconates such as K ₂ ZrF _6, fluorozirconates such as (NH ₄ ) ₂ ZrF ₆ , and soluble fluorozirconates such as H ₂ ZrF _6. , Zirconium fluoride, zirconium oxide, zirconyl nitrate, zirconium carbonate, and the like. These are used alone or in combination of two or more.

The organosiloxane content in the composition for metal surface treatment when subjected to surface treatment (that is, at the time of use) is preferably 1 ppm or more and 2000 ppm or less in terms of silicon element.
The zirconium compound content in the treatment liquid at the time of use is preferably 10 ppm or more from the viewpoint of securing a sufficient film amount on the metal substrate in terms of metal element. The upper limit is not particularly limited, but it is preferably 10,000 ppm or less because further effects cannot be expected even if it is contained more than that. More preferably, it is 50 ppm or more and 1000 ppm or less in terms of metal element, and more preferably 50 ppm or more and 600 ppm or less in terms of metal element.

  The metal surface treatment composition may further contain unreacted organosilane (including organosilane generated by hydrolysis as described above) in the polycondensation reaction during synthesis of organosiloxane. Like organosiloxane, unreacted organosilane is considered to contribute to the improvement of adhesion when incorporated into the chemical conversion film. However, the number of reactive functional groups per molecule of the organosiloxane formed by polycondensation is greater than the number of reactive functional groups that the unreacted organosilane has per molecule. Is interposed between the metal substrate and the coating film, thereby bringing about adhesion that cannot be obtained with unreacted organosiloxane.

  Therefore, when the metal surface treatment composition contains an unreacted organosilane, the polycondensation rate of the organosiloxane represented by the following formula (1) is an important factor for improving the adhesion. That is, the adhesion can be improved by appropriately controlling the polycondensation rate of the organosiloxane.

[Equation 1]
Polycondensation rate (%) = organosiloxane mass × 100 / (unreacted organosilane mass + organosiloxane mass) (1)
In the above mathematical formula (1), the mass of the organosiloxane is the mass of a dimer or higher organosiloxane and does not include the mass of the unreacted monomer.

The polycondensation rate of the organosiloxane represented by the formula (1) is preferably 40% or more, more preferably 50% or more, and further preferably 70% or more from the viewpoint of improving adhesion. 80% or more is even more preferable.
Evaluation of the polycondensation rate of the organosiloxane is carried out by measuring ²⁹ Si-NMR of the organosiloxane. Specifically, the silicon silane of the organosilane as a raw material is not bonded to other silicon atoms constituting the organosiloxane as an unreacted organosilane (monomer), and the other as a polycondensate organosiloxane as described above. The polycondensation rate can be determined from Equation (1).

In the organosiloxane, the mass ratio of the organosilane trimer or higher to the unreacted organosilane and organosilane dimer is preferably 1 or more from the viewpoint of further improving the adhesion.
Analysis of organosilane dimers (dimers) and multimers (polymers) is carried out by ²⁹ Si-NMR measurement in the same manner as in the evaluation of the polycondensation rate.

  The content of organosiloxane (including unreacted organosilane) in the metal surface treatment composition is preferably 1 ppm or more from the viewpoint of adhesion in terms of silicon element, and the balance between the obtained effect and economic efficiency To 2000 ppm or less. The organosiloxane content is more preferably 5 ppm or more and 500 ppm or less, and still more preferably 10 pm or more and 200 ppm or less.

  The mass ratio of the zirconium element contained in the zirconium compound to the silicon element contained in the organosiloxane (including unreacted organosilane) is the viewpoint of ensuring the formation of a chemical conversion film in which zirconium and the organosiloxane are incorporated in a balanced manner. Therefore, it is preferably 0.5 or more, more preferably 500 or less.

  In the case of the reactive type, the pH of the metal surface treatment composition is preferably 1.5 or more and 6.5 or less, because the metal substrate that is the object to be treated must be etched, and is 2.0 or more. It is more preferably 5.0 or less, and further preferably 2.5 or more and 4.5 or less. If the pH is less than 1.5, etching may be excessive and sufficient film formation may not be performed, and the film may become non-uniform, which may adversely affect the appearance of the film. On the other hand, if the pH exceeds 6.5, etching may be insufficient and a good chemical conversion film may not be obtained. This pH can be adjusted as appropriate using acidic compounds such as nitric acid and sulfuric acid, and basic compounds such as sodium hydroxide, potassium hydroxide and ammonia.

  In a preferred embodiment, the metal surface treatment composition further contains a fluorine compound as a free fluorine component. The elemental fluorine generated from the fluorine compound serves as a complexing agent for zirconium in addition to the role as an etching agent for the metal substrate. The fluorine compound that is a supply source of elemental fluorine is not particularly limited. For example, fluorides such as hydrofluoric acid, ammonium fluoride, boron fluoride acid, ammonium hydrogen fluoride, sodium fluoride, sodium hydrogen fluoride, and the like. Can be mentioned. It is also possible to use a complex fluoride as a supply source, for example, hexafluorosilicate, specifically, silicofluoric acid, zinc silicofluoride, manganese silicofluoride, silicohydrofluoric acid. Examples thereof include magnesium, nickel silicohydrofluoride, iron silicohydrofluorate, calcium silicohydrofluoride, and the like.

  The concentration of fluorine ions in the free state (content of free fluorine element) in the metal surface treatment composition at the time of use is preferably 0.01 ppm or more and 100 ppm or less, and preferably 0.1 ppm or more and 20 ppm or less. Is more preferable. The content of this free fluorine element can be determined by measuring with a meter having a fluorine ion electrode. If the content of the free fluorine element in the metal surface treatment composition is less than 0.01 ppm, the composition may become unstable and precipitation may occur, and the etching power may be reduced and the film may not be sufficiently formed. is there. On the other hand, if the content of the free fluorine element exceeds 100 ppm, there is a possibility that the film formation of zirconium is not sufficiently performed due to excessive etching.

  In another preferred embodiment, the metal surface treatment composition further comprises magnesium, zinc, calcium, aluminum, gallium, indium, copper, iron, manganese, nickel, cobalt, cerium, strontium, rare earth elements, tin, bismuth. And at least one metal element ion selected from the group consisting of silver. Any of these metal elements can improve the adhesion and corrosion resistance of the coating film.

In another preferred embodiment, the metal surface treatment composition is at least one selected from the group consisting of a nonionic surfactant, an anionic surfactant, a cationic surfactant, an amphoteric surfactant, and a chelating agent. It further includes seed additives. In the case of containing a surfactant, it is preferable in that a good chemical conversion film can be formed even if the metal substrate is not previously degreased and cleaned. When a chelating agent is contained, it is preferable in terms of uniform precipitation of zirconium.
Conventionally known surfactants and chelating agents can be used. Examples of the chelating agent include gluconic acid, aspartic acid, diethylenetriaminepentaacetic acid, and methanesulfonic acid.

In still another preferred embodiment, the metal surface treatment composition may contain an oxidizing agent for promoting a film forming reaction. As this oxidizing agent, nitric acid, nitrous acid, sulfuric acid, sulfurous acid, persulfuric acid, phosphoric acid, carboxylic acid group-containing compound, sulfonic acid group-containing compound, hydrochloric acid, bromic acid, chloric acid, hydrogen peroxide, HMnO ₄ , HVO ₃ , H ₂ WO ₄ , and H ₂ MoO ₄ , and salts of these oxygen acids. These oxidizing agents can be blended alone or in combination.

The metal surface treatment composition as described above can be used as a coating-type treatment agent or a reaction-type treatment agent containing a chemical film-forming component.
Here, the coating-type treatment agent is a type that performs surface treatment by applying a treatment agent to a metal substrate and then drying it without forming it with water to form a surface protective film. is there. For example, an anticorrosion paint is mentioned as an example, and it is preferably used for anticorrosion treatment of corrosion resistant steel sheets such as galvanized steel sheets and galvanium steel sheets (Al-Zn hot dip steel sheets).

On the other hand, the reactive treatment agent refers to a treatment agent that reacts a metal substrate and a treatment agent to deposit a chemical conversion film as a surface protective film. In the case of the reaction type, a thinner chemical conversion film can be deposited using a treatment liquid having a concentration lower than that of the coating type. The contact between the reactive treatment agent and the metal substrate is usually performed by immersing the article to be coated in the treatment agent, and a chemical film with high adhesion is formed by the reaction. Water washing is performed.
Specifically, when surface treatment of a metal substrate is performed with a metal surface treatment composition containing zirconium, a dissolution reaction (etching) of the metal constituting the metal substrate occurs. When the metal dissolution reaction occurs, when zirconium fluoride is contained, the metal ions eluted in the metal surface treatment composition extract the fluorine of ZrF ₆ ²⁻ and the pH of the interface rises. Thus, zirconium hydroxide or oxide is deposited on the surface of the metal substrate.

  Thus, the metal surface treatment composition according to one embodiment of the present invention can be used as a reactive chemical conversion treatment agent, and is suitable for chemical conversion treatment of a metal substrate having a complicated shape. Regarding the metal to be treated, in addition to the above-mentioned corrosion-resistant steel sheet, it is also characterized by being suitable for iron-based substrates such as iron plates that have been difficult to form a uniform chemical conversion film with excellent adhesion and corrosion resistance. It is.

<Method for producing surface-coated metal substrate>
The method for producing a surface-coated metal base material is obtained by treating the surface of a metal base material with the metal surface treatment composition according to the present invention, and protecting the surface of the metal base material from the metal surface treatment composition. Coating the layer. The surface protective layer may be formed of either a coating type or a reactive type processing agent.

  Although it does not specifically limit as a metal base material, For example, a steel plate, an aluminum plate, etc. can be mentioned. The steel sheet includes any of a cold-rolled steel sheet or a hot-rolled steel sheet, and a mild steel sheet or a high-tensile steel sheet, and is not particularly limited. For example, an iron-based substrate (iron-based metal substrate), an aluminum-based substrate ( Examples thereof include an aluminum-based metal substrate), a zinc-based substrate (zinc-based metal substrate), and a magnesium-based substrate (magnesium-based metal substrate). An iron-based substrate is a substrate (metal substrate) made of iron and / or an alloy thereof, an aluminum-based substrate is a substrate (metal substrate) made of aluminum and / or an alloy thereof, and a zinc-based substrate The base material (metal base material) which consists of zinc and / or its alloy is meant. The magnesium-based substrate means a substrate (metal substrate) made of magnesium and / or an alloy thereof.

  Furthermore, the present invention can also be applied to a metal substrate composed of a plurality of metal substrates such as an iron-based substrate, an aluminum-based substrate, and a zinc-based substrate. In particular, automobile bodies and parts for automobiles are composed of various metal base materials such as iron, zinc, and aluminum. By using the metal surface treatment composition, a chemical conversion film having sufficient adhesion Can be formed, and good corrosion resistance can be imparted.

It does not specifically limit as an iron-type base material, For example, a cold-rolled steel plate, a hot-rolled steel plate, etc. can be mentioned.
The aluminum-based substrate is not particularly limited, and examples thereof include a 5000-series aluminum alloy, a 6000-series aluminum alloy, aluminum-plated steel sheets such as aluminum-based electroplating, hot dipping, and vapor deposition plating.
The zinc-based substrate is not particularly limited, and examples thereof include galvanized steel sheet, zinc-nickel plated steel sheet, zinc-iron plated steel sheet, zinc-chromium plated steel sheet, zinc-aluminum plated steel sheet, zinc-titanium plated steel sheet, zinc- Examples thereof include zinc-based electroplating such as magnesium-plated steel sheet and zinc-manganese-plated steel sheet, zinc such as hot-dip plating, vapor-deposited steel sheet, and zinc-based alloy-plated steel sheet.
The magnesium-based substrate is not particularly limited, and examples thereof include Mg-Al-based alloy AM100A, Mg-Al-Zn-based alloy A291D, and Mg-Zn-based alloy ZK51A.
There are various types of high-strength steel sheets depending on strength and manufacturing method, and examples include JSC440J, 440P, 440W, 590R, 590T, 590Y, 780T, 780Y, 980Y, 1180Y, and the like.

The method of applying the metal surface treatment composition to the metal substrate is not particularly limited, but in the case of a coating type, for example, a dipping method, a spray method, a roll coating method, a bar coating method, and a sink A roll coating method and a bar coating method are particularly preferable from the viewpoint that a coating method or the like can be applied and the thickness of the surface protective film after drying can be strictly controlled.
Also in the case of the reaction type, it is not particularly limited, and examples thereof include a dipping method, a spray method, a roll coating method, and a pouring treatment method.

  In the case of the reactive type, the metal surface treatment composition can also be applied by electrolytic treatment using the metal substrate as a cathode. In this case, a hydrogen reduction reaction occurs at the metal substrate interface which is the cathode, and the pH rises. As the pH increases, the stability of the compound containing zirconium element at the cathode interface decreases, and a surface treatment film (chemical conversion film or surface protective film) is deposited as an oxide or a hydroxide containing water.

  The temperature of the treatment liquid in the surface treatment in the case of the reaction type is preferably in the range of 20 ° C. or higher and 70 ° C. or lower, and more preferably in the range of 30 ° C. or higher and 50 ° C. or lower. If it is less than 20 ° C., sufficient film formation may not be performed. On the other hand, if it exceeds 70 ° C., no further effect can be obtained.

  In the case of the reactive type, the surface treatment time is preferably in the range of 2 seconds to 1100 seconds and more preferably in the range of 30 seconds to 120 seconds. If it is less than 2 seconds, it is difficult to obtain a sufficient coating amount, and even if it exceeds 1100 seconds, it may be difficult to obtain further effects.

  After the metal surface treatment composition is applied to a metal substrate to form a surface protective film, it can be dried by heating. The heating temperature is preferably a temperature at which the isocyanate group can be deblocked, and is preferably 110 ° C. or higher and 240 ° C. or lower, for example.

  Prior to the surface treatment, the metal substrate is preferably cleaned by a degreasing treatment. Furthermore, it is preferable that a water washing process is performed after degreasing. These degreasing treatments and water washing treatments are performed to remove oil and dirt adhering to the surface of the metal substrate, and usually 30 ° C. to 55 ° C. with a degreasing agent such as a phosphorus-free and nitrogen-free degreasing cleaning solution. Immersion treatment is performed at a temperature of about several minutes. If desired, a preliminary degreasing process can be performed before the degreasing process. The water washing treatment after the degreasing treatment is performed by spraying at least once with a large amount of washing water in order to wash the degreasing agent with water.

  As described above, when the metal surface treatment composition contains an optional surfactant, a good film can be formed without degreasing and cleaning the metal substrate in advance. That is, in this case, the metal substrate is degreased simultaneously in the application (contact) step of the treatment liquid.

  The water washing treatment after the surface treatment that can be carried out in the case of the reaction type can be carried out a plurality of times, and the final water washing in that case is preferably carried out with pure water. In the water washing treatment after the surface treatment, either spray water washing or immersion water washing may be used, and these methods may be combined for water washing.

In order to improve the corrosion resistance of ferrous metal substrates such as cold-rolled steel sheets, hot-rolled steel sheets, cast iron and sintered materials, to form uniform surface treatment films, and to obtain good adhesion, The surface treatment film layer formed on the surface of the metal substrate preferably contains 10 mg / m ² or more of zirconium element and 0.5 mg / m ² or more of silicon element in terms of metal element. Containing zirconium element 20 mg / ^{m 2} or more, more preferably having a surface treatment coating layer containing the silicon element 1 mg / ^{m 2} or more, and containing zirconium element 30 mg / ^{m 2} or more, the silicon element 1.5 mg / It is more preferable to have a surface treatment film layer containing m ² or more.

For the purpose of giving good corrosion resistance to zinc-based metal substrates such as zinc or galvanized steel sheets, galvannealed steel sheets, etc. The coating amount of the surface treatment film layer formed on the substrate surface preferably contains 10 mg / m ² or more of zirconium element and 0.5 mg / m ² or more of silicon element. Containing zirconium element 20 mg / ^{m 2} or more, more preferably having a surface treatment coating layer containing the silicon element 1 mg / ^{m 2} or more, further contains a zirconium element 30 mg / ^{m 2} or more, the silicon element 1 It is further preferable to have a surface treatment film layer containing 5 mg / m ² or more.

For the purpose of providing good corrosion resistance to aluminum metal substrates such as aluminum castings and aluminum alloy plates, in order to form a uniform chemical conversion film and obtain good adhesion, it is formed on the surface of aluminum metal substrates. The coating amount of the surface treatment coating layer preferably contains 5 mg / m ² or more of zirconium element and 0.5 mg / m ² or more of silicon element. Containing zirconium element 10 mg / ^{m 2} or more, and more preferably has a surface treatment coating layer containing the silicon element 1 mg / ^{m 2} or more.

Furthermore, in order to form a uniform chemical conversion film and obtain good adhesion for the purpose of imparting good corrosion resistance to magnesium-based metal substrates such as magnesium alloy plates and magnesium castings, The coating amount of the surface treatment coating layer to be formed preferably contains 5 mg / m ² or more of zirconium element and 0.5 mg / m ² or more of silicon element. Containing zirconium element 10 mg / ^{m 2} or more, and more preferably has a surface treatment coating layer containing the silicon element 1 mg / ^{m 2} or more.

In any metal substrate, there is no particular upper limit of the coating amount of the surface treatment coating layer, but if the coating amount is too large, cracks are likely to occur in the surface treatment coating layer, and it is difficult to obtain a good coating. Become. In this respect, the coating amount of the surface treatment coating preferably contains 1 g / m ² or less, more preferably 800 mg / m ² or less of zirconium in terms of metal element.

  In any metal substrate, the mass ratio of zirconium element to silicon element in the surface treatment film is preferably 0.5 or more and 50 or less. If it is less than 0.5, corrosion resistance and adhesion cannot be obtained. If it exceeds 50, cracks are likely to occur in the surface-treated film layer, making it difficult to obtain a uniform film.

After the surface coating, the metal substrate may be further contacted with an acidic aqueous solution containing at least one selected from the group consisting of cobalt, nickel, tin, copper, titanium and zirconium. By including this acid contact step, the corrosion resistance of the chemical conversion film can be further enhanced.
The source of at least one selected from the group consisting of cobalt, nickel, tin, copper, titanium and zirconium, which are metal elements, is not particularly limited, but is easily available. , Chlorides, nitrates, oxynitrates, sulfates, oxysulfates, carbonates, oxycarbonates, phosphates, oxyphosphates, oxalates, oxyoxalates, organometallic compounds, etc. it can.

  The pH of the acidic aqueous solution containing the metal element is preferably 2-6. PH of acidic aqueous solution is phosphoric acid, nitric acid, sulfuric acid, hydrofluoric acid, hydrochloric acid, organic acid, etc., sodium hydroxide, potassium hydroxide, lithium hydroxide, alkali metal salt, ammonia, ammonium salt, amines It can adjust with alkalis, such as.

Alternatively, the metal substrate after the surface treatment may be brought into contact with a polymer-containing liquid containing at least one of a water-soluble polymer compound and a water-dispersible polymer compound. By including this polymer-containing liquid contact step, the corrosion resistance of the chemical conversion film can be further enhanced.
The water-soluble polymer compound and the water-dispersible polymer compound are not particularly limited. For example, polyvinyl alcohol, poly (meth) acrylic acid, a copolymer of acrylic acid and methacrylic acid, ethylene and (meth) acrylic acid , Copolymers with acrylic monomers such as (meth) acrylates, copolymers of ethylene and vinyl acetate, polyurethane, amino-modified phenol resins, polyester resins, epoxy resins, tannins, tannic acid and salts thereof, Phytic acid is mentioned.

<Manufacturing method of metal coating>
The method for producing a metal-coated product comprises forming a coating film by applying an arbitrary paint on the surface of the surface-coated metal substrate produced by the method for producing a surface-coated metal substrate, that is, a surface protective film, and It includes heating and drying the coating film.

In the case of the surface treatment by the reactive type, the water washing treatment can be performed after the surface treatment. After the water washing treatment, if necessary, it may be dried according to a known method. However, if the next process is an aqueous coating process, the process proceeds to the next painting process without performing the drying treatment after the water washing treatment. be able to. That is, a wet-on-wet coating method can be employed.
Therefore, for vehicle exteriors such as automobile bodies and motorcycle bodies, which are metal structures having curved surfaces and bent parts, various parts, etc., are subjected to reactive surface treatment and are always dried before electrodeposition coating. If a wet-on-wet coating method is employed, a series of processes from the surface treatment process to the electrodeposition coating process can be shortened.
Examples of the coating film include coating films formed by conventionally known coating materials such as solvent coating materials, water-based coating materials, and powder coating materials in addition to electrodeposition coating.

  In the case of electrodeposition coating, cationic electrodeposition coating using a metal substrate as a cathode is preferable. In general, the cationic electrodeposition coating is made of a resin having a functional group that is reactive or compatible with an isocyanate group. Therefore, an organosiloxane containing an isocyanate group contained in a metal surface treatment composition that is a chemical conversion treatment agent. It is because the adhesion between the electrodeposition coating film and the chemical conversion film can be further enhanced by the function. The cationic electrodeposition coating is not particularly limited, and examples thereof include known cationic electrodeposition coatings composed of an aminated epoxy resin, an aminated acrylic resin, a sulfoniumated epoxy resin, and the like.

After coating, the coating film is heat-dried (baked). By this heat treatment, not only the coating film but also the surface protective film in the lower layer thereof is heated, the blocked isocyanate group of the organosiloxane is removed to form an isocyanate group, and the adhesion between the metal substrate and the coating film and A film having good corrosion resistance can be formed.
In this case, the temperature of the heat drying is not particularly limited, but is preferably a temperature at which deblocking occurs, for example, 110 ° C. or higher and 240 ° C. or lower. The heating time is not particularly limited, but is preferably about 2 to 120 minutes.

  EXAMPLES Next, although an Example and a comparative example are given and this invention is demonstrated more concretely, this invention is not limited only to these Examples. Unless otherwise specified, “part” represents mass part, and “%” represents mass%.

<Metal base material>
Commercial hot-dip galvanized steel sheet (GI, manufactured by Nippon Test Panel Co., Ltd., 70 mm × 150 mm × 0.8 mm), and commercially available cold-rolled steel sheet (SPC, manufactured by Nippon Test Panel Co., Ltd., 70 mm × 150 mm × 0.00 mm). 8 mm) was prepared as a metal substrate.
Each metal substrate was subjected to degreasing treatment at 40 ° C. for 2 minutes using an alkali degreasing agent “Surf Cleaner EC92” (manufactured by Nippon Paint Co., Ltd.) as a pretreatment.
After degreasing, it was immersed and washed in a water washing tank, and then spray washed with tap water for about 30 seconds.

<Production of blocked isocyanate silane M1>
(1) As isocyanate silane, 100 parts of KBE9007 (3-isocyanatopropyltriethoxysilane, effective concentration 100%, manufactured by Shin-Etsu Chemical Co., Ltd.) was used and heated to 80 ° C. Then, 40.8 parts of methyl ethyl ketoxime (reagent) was dripped uniformly over 60 minutes from the dropping funnel in nitrogen atmosphere. After further aging for 60 minutes, a blocked isocyanate silane (Example 1) was obtained.

(2) As isocyanate silane, 100 parts of KBE9007 (same as above) was used and heated to 80 ° C. Thereafter, a mixed solution of 100 parts of methyl isobutyl ketoxime (reagent) and 69 parts of orthoparaphenol (reagent) was uniformly added dropwise from a dropping funnel over 60 minutes in a nitrogen atmosphere. After further aging for 60 minutes, a blocked isocyanate silane (Example 2) was obtained.

<Manufacture of organosiloxane A>
After 30 parts of the above blocked isocyanate silane (Example 1) was uniformly dropped over 60 minutes from a dropping funnel into a mixed solvent of 35 parts of deionized water and 35 parts of ethanol, the reaction was performed at 25 ° C. for 24 hours in a nitrogen atmosphere. went. Thereafter, the reaction solution was depressurized to evaporate ethanol, and deionized water was further added to obtain organosiloxane A (single polycondensate) having an active ingredient of 30%. Here, the active ingredient means a non-volatile ingredient (the same applies hereinafter).

<Manufacture of organosiloxane B>
(1) 6 parts of the above-mentioned blocked isocyanate silane (Example 1) and 14 parts of aminosilane “KBE903” (3-aminopropyl-triethoxysilane, effective concentration 100%, manufactured by Shin-Etsu Chemical Co., Ltd.) as organosilane M2. Was added dropwise from a dropping funnel into a mixed solvent of 40 parts of deionized water and 40 parts of ethanol over 60 minutes, and then reacted at 60 ° C. for 24 hours in a nitrogen atmosphere. Then, ethanol was evaporated by reducing the pressure of the reaction solution, and deionized water was further added to obtain organosiloxane B (copolycondensation product 1) having an active ingredient of 10%.

(2) To a mixed solution of 15 parts of the blocked isocyanate silane (Example 2) and 64 parts of KBE903 (same as above) as organosilane M2, 25 parts of deionized water was uniformly dropped over 60 minutes from the dropping funnel. Then, reaction was performed at 25 degreeC under nitrogen atmosphere for 24 hours. Thereafter, the reaction solution was depressurized to evaporate ethanol, and deionized water was added to obtain organosiloxane B (copolycondensation product 2) containing 75% of the active ingredient.

(3) 15 parts of the above-mentioned blocked isocyanate silane (Example 1) and epoxy silane “KBM403” (3-glycidoxypropyltrimethoxysilane, effective concentration 100%, manufactured by Shin-Etsu Chemical Co., Ltd.) as organosilane M2 A mixed solution of 15 parts was uniformly dropped from a dropping funnel into a mixed solvent of 35 parts of deionized water and 35 parts of ethanol over 60 minutes, and then reacted at 60 ° C. for 24 hours in a nitrogen atmosphere. Thereafter, the reaction solution was depressurized to evaporate ethanol, and deionized water was further added to obtain organosiloxane B (copolycondensation product 3) having an active ingredient of 30%.

<Preparation of metal surface treatment composition>
Using the obtained organosiloxane A or B, metal surface treatment compositions (treatment solutions) having the compositions shown in Tables 1 and 2 were prepared. Deionized water was used as water, and zircon hydrofluoric acid (reagent) was used as zirconium. Sn was tin sulfate, Al was aluminum nitrate, Cu was copper nitrate, Zn was zinc nitrate, and Mg was magnesium nitrate. DTPA (diethylenetriaminepentaacetic acid) and taurine (reagent) are chelating agents.
In the comparative example, aminosilane “KBE-903” (same as above), epoxy silane “KBM-403” (same as above), or “Surf Coat CMML705” (manufactured by Nippon Paint) was used as a silane.

  The metal element concentration in the treatment liquid was measured using a plasma emission spectroscopic analyzer (device name: (ICP) UPO-1 MARKII, manufactured by Kyoto Koken Co., Ltd.).

  In the examples and comparative examples in Table 2, the pH of the prepared metal surface treatment composition was adjusted to 3.5 with an aqueous sodium hydroxide solution, and further with sodium acid fluoride so that the free fluorine ion was 5 ppm. It was adjusted.

<Manufacture of surface-coated metal substrate>
The treatment liquids of the examples and comparative examples in Table 1 were used as bar coater No. 4 was applied to the surface of the GI steel sheet, and then heated and dried at 120 ° C. for 30 seconds to form a film having a solid content of 0.5 g / m ² .

The treatment liquids of Examples and Comparative Examples in Table 2 were adjusted to 30 ° C., and a metal substrate (SPC) was immersed therein for 60 seconds to perform chemical conversion treatment. The metal substrate after the chemical conversion treatment was sprayed with tap water for 30 seconds, and then sprayed with ion exchange water for 10 seconds.
The metal substrate after the water washing treatment was dried at 40 ° C. for 10 minutes in an electric drying furnace. The coating amount (mg / m ² ) of the obtained chemical coating was measured using “XRF1700” (Shimadzu Corporation X-ray fluorescence analyzer).

<Manufacture of metal coatings>
A cationic electrodeposition paint “Powernics 110” (manufactured by Nippon Paint Co., Ltd.) was applied to each wet metal substrate subjected to a water washing treatment after the chemical conversion treatment to form an electrodeposition coating film. The dry film thickness after electrodeposition coating was 20 μm. Then, after washing each metal base material with water, the test plate was obtained by heating and baking at 170 degreeC for 20 minutes.

As a solvent paint, Olga Select OST900 White “manufactured by Nippon Paint” was used and applied to a dry film thickness of 30 μm to obtain a test plate.
As the water-based acrylic paint, Ode Eco Line OEL100 “manufactured by Nippon Paint” was used, and this was applied to a dry film thickness of 30 μm to obtain a test plate.

The following tests were performed on the test plates obtained in the examples and comparative examples.
<Primary rust prevention test>
The test piece after the surface treatment was sprayed with salt water (5% NaCl) for 24 hours in a 35 ° C. atmosphere, and then the primary rust prevention performance was evaluated. ◎ No rust generated, わ ず か slightly generated (less than 20% of surface area) ◯, rust generated about 20% to less than 50% of surface area △, about 50% of surface area The case where rust was generated almost over the entire surface was rated as x.

<SST (salt spray test)>
A 10 cm long scratch reaching the metal base material was put in the coating film with a cutter, sprayed with salt water (5% NaCl) for 840 hours in a 35 ° C. atmosphere, and then the tape was peeled off. When the maximum peel width on one side of the coating film from the scratch was less than 1 mm, ◎ was evaluated as 1 mm or more and less than 3 mm, Δ was evaluated as 3 mm or more and less than 6 mm, and X was evaluated as 6 mm or more.
The obtained results are shown in Table 1 and Table 2 together.

The surface-coated metal base material obtained in the above examples had sufficient coating film adhesion and corrosion resistance.
Therefore, the composition for surface treatment according to the present invention is preferably used in the field where the coating treatment is subsequently performed, such as a vehicle body before painting, a vehicle outer body such as a motorcycle body, various parts, a container outer surface, and a coil coating. used. In particular, it is preferably used for surface treatment of large parts such as automobile bodies that require a long treatment liquid life.

Claims (8)

  A blocked isocyanate group-containing organosiloxane having an organosilane having a hydrolyzable silicon-containing group and a reactive functional group as a monomer, the block having a blocked isocyanate group as the reactive functional group.   The blocked isocyanate group-containing organosiloxane according to claim 1, wherein the blocked isocyanate group-containing organosiloxane further contains an amino group and / or a glycidyl group as a reactive functional group.   A metal surface treatment composition comprising the blocked isocyanate group-containing organosiloxane according to claim 1 or 2, and water.   The metal surface treatment composition according to claim 3, further comprising a zirconium compound.   A surface-coated metal base material comprising a step of forming a surface protective film on the metal base material by applying the composition for metal surface treatment according to claim 3 or 4 to the metal base material and then drying without washing with water. Manufacturing method.   A method for producing a surface-coated metal substrate, further comprising the step of washing the metal substrate with water after the metal surface treatment composition according to claim 3 or 4 is brought into contact with the metal substrate. After producing the surface-coated metal substrate by the production method according to claim 5 or 6,
The manufacturing method of a metal coating thing including the process of apply | coating a coating material on the surface of the said surface coating metal base material, and forming the coating film, and the process of heat-drying the said coating film.   The method for producing a metal coated product according to claim 7, wherein the step of forming the coating film is performed by cationic electrodeposition coating.