JPS6258630B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to metal surface treatment compositions. Specifically, it relates to a metal surface treatment composition that provides high corrosion resistance and paint base properties to metal surfaces, has excellent adhesion to metal surfaces, has excellent deep drawing workability, and has excellent blocking resistance. It is something. Conventionally, chromate treatment or phosphate treatment has been carried out for the purpose of imparting corrosion resistance to metal surfaces and providing a coating base for improving adhesion with paints. Among these, the chromate treatment method has fairly good corrosion resistance, but the coating base properties and deep drawing workability are insufficient, and the phosphate treatment method has disadvantages such as insufficient corrosion resistance and deep drawing workability. have. Various methods have been proposed to improve these methods, but they have problems in performance and workability. In view of the current situation, the inventors of the present invention have filed a patent application filed in 1983.
- As No. 143359, water-dispersible silica, tri and/or
Alternatively, a metal surface treatment composition comprising a hydrolyzate of a dialkoxysilane compound, a cationic resin and/or a zwitterionic resin, and a chromium compound in a specific ratio was proposed. This metal surface treatment composition certainly has excellent corrosion resistance, coating base properties, and workability, but
On the other hand, the drawability and blocking resistance were not necessarily satisfactory. The inventors of the present invention have carried out extensive research to solve these current problems, and as a result, have been able to obtain a metal surface treatment composition that is extremely excellent in terms of drawing workability and blocking resistance. Therefore, the object of the present invention is to provide a metal surface treatment composition that imparts high corrosion resistance and coating base properties to metal surfaces, has excellent adhesion to metal surfaces, and also has excellent deep drawability and blocking resistance. It is something to do. That is, in the present invention, water-dispersible silica () is 0.5 in terms of SiO ₂ per metal surface treatment composition.
Amount in the range of ~250g, alkoxysilane compound (a) having a polymerizable unsaturated group (a) 0.1 to 10% by weight, polymerizable unsaturated carboxylic acid (b) 0 to 20% by weight, alkyl group having carbon atoms of 1 to 8 20-99% by weight of (meth)acrylic acid alkyl ester (c), 0-40% by weight of monomer (d) copolymerizable with these (however, (a), (b), (c) and
The sum of (d) is 100% by weight. ) The Tg of the core obtained by multi-stage emulsion polymerization of the monomer component consisting of
Cationic and/or amphoteric acrylic resin () (hereinafter referred to as acrylic resin ()) derived from a multilayer copolymer having a temperature of 10° C. or higher and a Tg of the outermost shell portion of 10° C. or lower. ) from 0.5 to 600
chromium compound () in an amount ranging from 0 to 50 g, and a cationic and/or amphoteric acrylic resin () having a Tg of 10° C. or higher (hereinafter referred to as acrylic resin ()). ) from 0 to 600g
and the amount of the hydrolyzate () of the tri- and/or dialkoxysilane compound (hereinafter referred to as the hydrolyzate ()) in terms of SiO ₂ from 0 to 200.
Contains an amount in the range of g, provided that (), (), (),
The present invention relates to a metal surface treatment composition characterized in that the sum of () and () does not exceed 700g. The water-dispersible silica used in the present invention is generally a condensate of silicic acid and is colloidal silica, and preferably has a particle size of 5 to 100 mμ. Examples of such water-dispersible silica include commercially available products such as "Snowtex O", "Snowtex N", and "Snowtex".
NCS”, “Snowtex 20”, “Snowtex C” (manufactured by Nissan Chemical Co., Ltd.), “Cataloid SN”,
"Cataloid Si-500" (manufactured by Catalyst Chemical Industry Co., Ltd.)
etc. In addition, surface-treated colloidal silica such as "Cataloid SA" treated with aluminic acid
(manufactured by Catalysts Kagaku Kogyo Co., Ltd.) etc. can also be used. These may be used as they are, but in order to improve their dispersibility in the metal surface treatment composition, acrylic resins () or amines such as quaternary ammonium salts, which are other essential components of the present invention, may be used. Surface treatment with water-dispersible silica () in advance,
An aziridine derivative such as ethyleneimine may be grafted onto the surface of the water-dispersible silica. The water-dispersible silica () is contained in an amount ranging from 0.5 to 250 g per metal surface treatment composition of the present invention. If the amount is less than 0.5 g, the effect obtained will be insufficient, and if it is used in excess of 250 g, processability will deteriorate, and both are not preferred. The acrylic resin () used in the present invention includes 0.1 to 10% by weight of an alkoxysilane compound (a) having a polymerizable unsaturated group, and a polymerizable unsaturated carboxylic acid.
(b) 0-20% by weight, (meth)acrylic acid alkyl ester in which the alkyl group has 1-8 carbon atoms (c) 20-20% by weight
99% by weight, monomer (d) copolymerizable with these 0-40
% by weight (however, the total of (a), (b), (c) and (d) is 100% by weight)) The core portion obtained by multi-stage emulsion polymerization has a Tg of 15 ℃ or more,
It is a cationic and/or amphoteric acrylic resin derived from a multilayer structure copolymer whose outermost shell has a Tg of 10°C or less. The multi-stage emulsion polymerization referred to here means that first, some components are selected from the monomer components so that the Tg of the polymer is 15°C or higher, and this part of the components is used as the first stage. In this method, emulsion polymerization is carried out using the emulsion polymerization method described above, and in the presence of the obtained polymer (this is referred to as a core portion), the remaining monomer components are used to sequentially perform emulsion polymerization in the second and subsequent stages. At this time, from the second stage onwards, by using the entire amount of the remaining monomer component used in the first stage, 2
The polymerization may be carried out in stages, or may be carried out in three or more stages by appropriately dividing the polymerization. The polymer having the composition of the final stage is called the outermost shell part. In the present invention, it is necessary that the Tg of the outermost shell portion be 10°C or less. As multi-stage emulsion polymerization, generally two to three stages of polymerization are used, and it is preferable that the weight ratio of the core part to the other parts is in the range of 10:90 to 90:10. A polymer obtained by such a method is referred to as a multilayer structure copolymer in the present invention. Specific examples of the polymerizable monomer component constituting the multilayer structure copolymer of the present invention include vinyldimethoxymethylsilane,
Vinyltris(β-methoxyethoxy)silane,
Examples include vinyltriethoxysilane, vinyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, and γ-methacryloxypropylmethyldimethoxysilane. One type or a mixture of two or more of these monomers is used in an amount of 0.1 to 10% by weight based on the total monomer components. If it is less than 0.1%, the adhesion to the substrate and crosslinking properties are insufficient, and
If the amount exceeds 10% by weight, crosslinking will proceed too much and it will not be economical. Typical examples of the polymerizable unsaturated carboxylic acid (b) include acrylic acid, methacrylic acid, and itaconic acid. One or two of these monomers
A mixture of more than one species is used in an amount of 0 to 20% by weight of the total monomers. Polymerizable unsaturated carboxylic acids are used as monomers to impart amphoteric ionicity to resins or to introduce cationic properties through post-reactions, but if the amount exceeds 20% by weight, the water resistance of the resin will decrease. It's undesirable because it makes you feel bad. Typical examples of (meth)acrylic acid alkyl esters (c) in which the alkyl group has 1 to 8 carbon atoms include methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, and methacrylic acid. Methyl, ethyl methacrylate, propyl methacrylate, butyl methacrylate, etc. can be mentioned. One type or a mixture of two or more of these monomers is used in an amount of 20 to 99% by weight of the total monomer component. Monomers (d) that can be copolymerized with these include α-olefins such as ethylene, propylene, and isobutylene, vinyl halides such as vinyl chloride and vinyl bromide, vinyl cyanides such as acrylonitrile and methacrylonitrile, and acetic acid. Vinyl, vinyl esters such as vinyl propionate, aromatic vinyls such as styrene, vinyltoluene, α-methylstyrene, vinylidene halides such as vinylidene chloride and vinylidene fluoride, dimethylaminoethyl acrylate, diethylaminoethyl acrylate, dimethylaminoethyl Examples include methacrylate, diethylaminoethyl methacrylate, glycidyl acrylate, glycidyl methacrylate, acrylamide, methacrylamide, and N-methylol acrylamide. One or more of these monomers can be used to make the multilayer copolymer cationic and/or zwitterionic, and to satisfy the requirements for the Tg of the core and outermost shell. It is used in an amount of 0 to 40% by weight of the total mass components. The multilayer structure copolymer is a special acrylic resin that contains a hydrolyzable silicon compound in its molecules, but it also has a Tg of 15°C or higher in the core and a Tg of 10°C or lower in the outermost shell. It is important that The Tg shown here indicates the glass transition point of the copolymer, and it is preferable to actually measure its value, but another method is to use Fox's "Bull, Am, Physics Soc.", Vol. 1. It can be calculated as described in No. 3, p. 123 (1956). If the Tg of the core portion is less than 15°C, the strength of the resulting coating film will be weak, and the coating film will tend to become too soft when heated. Therefore, the metal material coated with the composition, for example, if it is a steel plate, is likely to cause blocking when wound into a coil.
I have a problem with my work. The outermost shell portion must have a Tg of 10°C or less. When the temperature exceeds 10°C, when applied to metal materials, it is difficult to form a film at low temperatures, film defects are likely to occur, and sufficient performance cannot be expected in many cases.
Acrylic resin () has cationic nitrogen in the molecule derived from such a multilayer structure copolymer. Typical cationic resins include, for example, the resins shown in the following items (1) to (3). (1) One or more types selected from vinyl compounds containing an amino ester group such as dialkylaminoalkyl (meth)acrylate, and cationic nitrogen-containing vinyl compounds such as vinylpyridine, vinylimidazole, or their salts. A resin obtained by copolymerization. (2) A resin made by cationizing an acrylic resin copolymerized with glycidyl (meth)acrylate or chloromethyl methacrylate with dimethylamine, diethylamine, ethylenediamine, etc. (3) A resin containing an aminomethyl group obtained by reacting an acrylic resin copolymerized with p-chloromethylstyrene and an amine and/or a polyamine. In addition, an amphoteric ionic resin is a resin having cationic nitrogen and anionic carboxyl group in the molecule, and includes, for example, the resins listed in the following items (4) to (6). I can do it. (4) A resin in which a carboxyl group, which is an anionic group, is introduced into the cationic resin of items (1) to (3) above by a known method (for example, using chromium acetic acid, etc.). (5) Carboxyl group-containing (meth)acrylic resins and basic nitrogen compounds such as aziridine compounds such as ethyleneimine, propyleneimine, hydroxyethylethyleneimine, cyanoethylethyleneimine, 1,6-hexamethylene diethylene urea, and glycidylamine or its salts. A resin containing zwitterionic groups obtained by reaction with a containing alkylating agent. (6) One or more basic nitrogen-containing vinyl compounds such as dialkylaminoalkyl (meth)acrylate, vinylpyridine, vinylimidazole, or their salts, and (meth)acrylic acid, crotonic acid, or maleic acid. A copolymer obtained by using one or more carboxyl group-containing vinyl compounds such as acids as an essential component. etc. can be mentioned. Among these acrylic resins (), the
The resins shown in items (1) and (5) are particularly effective as the resin () in the present invention. In the present invention, as the acrylic resin (), various cationic resins and/or amphoteric ionic resins can be used as exemplified in items (1) to (6) above. However, in the case of a cationic resin, the amount of cationic nitrogen measured by a commonly known method such as colloid titration, conductivity titration, etc. is in the range of 0.01 to 5 mmol per 1 g of the resin. This is desirable. In the case of amphoteric ionic resins, the amount of cationic nitrogen and the amount of carboxyl groups that can be anionized (these amounts can also be measured by colloid titration, conductivity titration, etc.) are determined by 1 g of the resin. Preferably, the amounts range from 0.01 to 5 mmol each. If it is outside this range, the effect as a metal surface treatment composition will be insufficient, which is not preferable. When using the acrylic resin () in the present invention, it may be used as it is, or a part or all of the cationic nitrogen may be replaced with a salt of a mineral or organic acid such as hydrochloric acid, nitric acid, phosphoric acid, or formic acid, or a salt of a quaternary acid. It can be used as a grade ammonium salt, or as ammonia,
It is also possible to add basic substances such as amines and polyamines. The acrylic resin () is contained in an amount ranging from 0.5 to 600 g, preferably from 1 to 400 g per metal surface treatment composition of the present invention. If the amount is less than 0.5 g, the adhesion between the resulting metal surface treatment composition and the metal surface will be insufficient. Conversely, when a large amount exceeding 600 g is used, the liquid stability of the composition deteriorates. The chromium compound () used as necessary in the present invention is generally well-known.
CrO ₃ , Cr(NO ₃ ) ₃ , CrCl ₃ , Cr ₂ (SO ₄ ) ₃・
18H ₂ O, CrPO ₄・6H ₂ O; chromates such as potassium chromate and ammonium chromate; water-soluble chromium compounds such as dichromates such as potassium dichromate, ammonium dichromate, and sodium dichromate; Water-insoluble chromium compounds such as strontium chromate, lead chromate, zinc chromate, etc. can be used. Among them, water-soluble chromium compounds such as chromic anhydride, chromate, and dichromate are preferred because they improve corrosion resistance even in small amounts. These chromium compounds () may be used alone or in combination of two or more, but the amount ranges from 0 to 50 g, preferably 0.1 g per metal surface treatment composition of the present invention.
Contains an amount of ~20g. Next, the acrylic resin () added as necessary is a cationic and/or amphoteric acrylic resin with a Tg of 10°C or higher, and is obtained by various conventionally known emulsion polymerization methods. Typical examples include the resins listed in sections (1) to (6) above, among which resins listed in section (1) or (5) above are used. A resin is preferable. However, it is not necessary to have a multilayer structure like the acrylic resin (). In acrylic resin (),
The amount of cationic nitrogen is preferably in the range of 0.01 to 3 mmol, more preferably 0.01 to 1 mmol, per gram of the resin. In the case of an amphoteric ionic resin, the amount of cationic nitrogen and the amount of anionizable carboxyl group are each 0.01 per gram of the resin.
Preferably, the amount is in the range from 3 mmol to 0.01 mmol to 1 mmol. Outside this range,
The effect as a metal surface treatment composition is insufficient and is therefore undesirable. The acrylic resin () is contained in an amount ranging from 0 to 600 g per metal surface treatment composition, and has the function of improving blocking resistance when the treated steel sheet is wound into a coil, and also prevents crosslinking. Since it has a small amount of thermoplasticity, it also works to improve drawing workability. It also works to improve the water resistance of the paint film. In the present invention, a hydrolyzate () of a tri- and/or dialkoxysilane compound is added as necessary, and the tri- and/or dialkoxysilane compound is one or two organic atoms per silicon atom. A silane compound in which a group and three alkoxy groups are bonded, and specific examples thereof include vinyldimethoxymethylsilane, methyltriethoxysilane, vinyltriethoxysilane, vinyl-tris-(β-methoxyethoxy)silane, and γ. -Methacryloxypropyltrimethoxysilane, β-
(3,4-epoxycyclohexyl)-ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-chloropropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, γ-aminopropyltriethoxysilane, N- (β-aminoethyl)-γ-aminopropyltrimethoxysilane, γ-ureidopropyltrimethoxysilane, γ-aminopropylmethyldiethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-mercaptopropylmethyldimethoxysilane , γ-(3-aminoethyl)-aminopropylmethyldimethoxysilane,
Examples include γ-chloropropylmethyldimethoxysilane. To obtain the hydrolyzate () of these tri- and/or dialkoxysilane compounds, hydrolysis may be carried out in a mineral acid such as hydrochloric acid, phosphoric acid, or sulfuric acid, or an organic acid such as formic acid or acetic acid using a conventional method. . At this time, the hydrolysis may be carried out in the coexistence of water-dispersible silica () or may be carried out alone. In some cases, acrylic resin () may be used in the coexistence, or water-dispersible silica () and acrylic resin () may be used together.
Hydrolysis may be carried out in the coexistence of both. These hydrolysates () are per metal surface treatment agent.
It is used in an amount ranging from 0 to 200 g in terms of SiO ₂ . When used in an amount of 200 g or less, it works to further improve blocking resistance, corrosion resistance, solvent resistance, water resistance, etc. Water-dispersible silica (), acrylic resin (),
When obtaining a composition consisting of a chromium compound (), an acrylic resin (), and a hydrolyzate of a tri- and/or dialkoxysilane compound () having the above specified ratio, these and water may be mixed in any order. . Moreover, as a mixing method, a usual method can be used. The scope of the present invention is not limited by these mixing order or method. Furthermore, tannic acid, gallic acid, thiourea, etc., which are generally known as components of rust preventive agents, may be added to the metal surface treatment composition of the present invention. Furthermore, by using a water-insoluble or water-dispersible inorganic substance in combination, it is possible to improve the surface condition and corrosion resistance of the metal to be coated. Such water-insoluble or water-dispersible inorganic substances include finely powdered silica, talc, diatomaceous earth, calcium carbonate, clay, titanium dioxide, aluminum silicate,
Examples include aluminum phosphate, alumina sol, magnesia sol, titania sol, and zirconia sol. Further, the amount used is preferably 50 g or less per 1 metal surface treatment composition of the present invention. The metal surface treatment composition of the present invention obtained in this way has excellent water resistance, alkali resistance, corrosion resistance, and coating base, due to the integrated action of water-dispersible silica () and acrylic resin (). sex,
It has drawing workability, blocking resistance, and workability,
Furthermore, by appropriately adding a chromium compound (), an acrylic resin (), or a hydrolyzate of tri- and/or dialkoxysilane (),
It exhibits even better drawing workability, blocking resistance, and corrosion resistance. The metal surface treatment composition of the present invention includes metals such as iron, steel, alloy steel, zinc, zinc alloy, aluminum, aluminum alloy; and iron, steel, alloy steel, zinc,
Can be used for metal materials such as metal coatings coated with zinc alloys, aluminum, aluminum alloys, etc., and exhibits particularly excellent effects on metal materials plated with zinc or alloyed zinc. It is. Moreover, these metal materials can be used in various shapes such as plate, pipe, and wire. To use the metal surface treatment composition of the present invention,
After coating the surface of a metal material at room temperature to 150°C, preferably room temperature to 70°C, by brush coating, spray coating, roll coating, dipping, etc., it is sufficient to simply dry it at a temperature above room temperature for several seconds to several minutes. In this case, sufficient effects can be obtained with a coating film having a thickness of about 0.1 to 5 μm. Metal materials treated with the composition obtained in this way have excellent water resistance, alkali resistance, solvent resistance, corrosion resistance, paint base properties, and drawing processability, making them useful and suitable for various uses. It is a great product. Hereinafter, the present invention will be explained in more detail using specific examples, but the present invention is not limited to the examples in any way. Note that % in Reference Examples and Examples indicates weight %. Example 1 466 parts of deionized water and 2 parts of an anionic emulsifier were added to a flask equipped with a stirrer, a reflux condenser, a thermometer, a nitrogen inlet tube, and a dropping funnel, and the temperature was raised to 70°C. Next, after adding 2 parts of ammonium persulfate, 28.0 parts of styrene, methyl methacrylate
27.5 parts, butyl acrylate 39 parts, acrylic acid 6 parts
and 0.5 parts of vinyltrimethoxysilane were added over 1 hour to carry out the first stage emulsion polymerization. After further polymerization for 1 hour, a monomer mixture consisting of 30 parts of styrene, 60 parts of butyl acrylate, 9 parts of acrylic acid, and 1 part of vinyldimethoxymethylsilane was added over a period of 1 hour to form a second stage (outermost shell part). (constituting) was subjected to emulsion polymerization to obtain a multilayer polymer with a Tg of approximately 19°C in the core and approximately -12°C in the outermost shell. Next, 7 parts of ethyleneimine and 16 parts of deionized water were added to this polymer, and 3 parts of it was heated at 50°C.
After reacting for a period of time, it was neutralized with ammonia to a pH of 9.0 to obtain an amphoteric ionic acrylic resin (2) having a solid content of 30%. To 600 parts of the resulting amphoteric ionic acrylic resin (), 100 parts of water-dispersible silica () (trade name, Snowtex O, 20% SiO ₂ product) and 5
Water-dispersible silica () is prepared by adding 2 parts of % chromic anhydride and bringing the total volume to 1 part with deionized water.
A metal surface treatment composition was obtained containing 20 g/in terms of SiO ₂ , 180 g/in an amphoteric ionic acrylic resin (), and 0.1 g/in a chromium compound (in terms of SiO 2 ). This composition will be referred to as Composition A. Example 2 In the same manner as in Example 1, 55 parts of methyl methacrylate and 39 parts of butyl acrylate were prepared in the first stage.
The second stage contains 4 parts of methyl methacrylate, 81 parts of butyl acrylate, 14 parts of acrylic acid and γ-methacryloxypropyltrimethoxysilane. Consisting of 1 part silane, Tg of core part is approximately 24℃, outermost shell part is approximately -35℃
After synthesizing a multilayer structure polymer at a temperature of 30.degree. C., a cationization reaction was carried out with 6 parts of ethyleneimine, and after neutralization with ammonia, an amphoteric ionic acrylic resin () with a solid content of 30% and a pH of 9.0 was obtained. Water-dispersible silica ()
(Product name: Snowtex C, SiO ₂ 20% product) 200
530 parts of the above-mentioned acrylic resin () and 20 parts of 5% chromic anhydride, and the whole was diluted with deionized water.
By making water-dispersible silica ()
40g/ in terms of SiO ₂ , 160g/acrylic resin () and 1 chromium compound ()
A metal surface treatment composition containing g/g/g was obtained. This composition will be referred to as Composition B. Example 3 In the first stage, 55 parts of methyl methacrylate, 33 parts of butyl acrylate, and 10 parts of acetate of dimethylaminoethyl methacrylate were prepared in the same manner as in Example 1 except that a nonionic emulsifier and a cationic emulsifier were used as emulsifiers. The second stage contains 5 parts of methyl methacrylate, 75 parts of butyl acrylate, 5 parts of acetate of dimethylaminoethyl methacrylate, and 2 parts of γ-methacryloxypropyltrimethoxysilane.
A cationic acrylic system with a solid content of 30% and a pH of 5.0, with a core Tg of approximately 27°C and an outermost shell Tg of approximately -30°C, consisting of 14 parts and 1 part of γ-methacryloxypropyltrimethoxysilane. Resin () was obtained. next,
300 parts of water-dispersible silica (trade name, Snowtex C, 20% SiO ₂ product) was treated with a quaternary ammonium salt. The water-dispersible silica () treated with this quaternary ammonium salt is added to the acrylic resin () 460.
By adding 1 part and 10 parts of 5% chromic anhydride and bringing the whole to 1 part with deionized water, the water-dispersible silica () was converted to 60 g/SiO ₂ , the acrylic resin () was 138 g/and the chromium compound. ()of
A metal surface treatment composition containing 0.5 g/metal was obtained.
This composition will be referred to as Composition C. Example 4 After reacting 200 parts of an emulsion polymer with a solid content of 40% and having a Tg of about 13°C obtained from 60 parts of methyl methacrylate, 38.8 parts of 2-ethylhexyl acrylate and 1.2 parts of acrylic acid with 0.57 parts of ethyleneimine. , neutralized with ammonia to obtain a zwitterionic acrylic resin () with a solid content of 40% and a pH of 8.5. To this, 267 parts of the acrylic resin () obtained in Example 2,
200 parts of water-dispersible silica (trade name, Snowtex C, 20% SiO ₂ product) and 5% chromic anhydride 10
Convert water-dispersible silica () to SiO ₂ by adding 1 part and bringing the whole to 1 with deionized water.
A metal surface treatment composition containing 40 g/acrylic resin (2), 80 g/1 chromium compound (2), and 80 g/1 acrylic resin (2) was obtained. This composition is referred to as Composition D. Example 5 In Example 4, a hydrolyzate of γ-glycidoxypropyltrimethoxysilane was further added, and the amount of water-dispersible silica () was 40 g/SiO _{2 .}
, Acrylic resin () 80g/, Chromium compound () 0.5g/, Acrylic resin ()
A metal surface treatment composition containing 80 g/hydrolyzate V and 5 g/hydrolyzate V in terms of SiO ₂ was obtained. This composition is referred to as Composition E. Comparative Example 1 In Example 1, the same amounts of methyl methacrylate, acrylic acid and vinyltrimethoxysilane were used as in Example 1, and the ratio of styrene and butyl acrylate in the monomer composition was Part Tg
was changed to about 0°C, and the Tg of the outermost shell was changed to about 0°C, and a multilayer structure copolymer was synthesized. Subsequently, in the same manner as in Example 1, water-dispersible silica () was mixed with SiO A metal surface treatment composition containing 180 g/ampholytic acrylic resin and 0.1 g/chromium compound ( ₂₎ was obtained. Comparative Example 2 In Example 2, the composition of the monomers used was mixed in the first stage and the second stage and emulsion polymerized in one stage,
Water-dispersible silica () was prepared in the same manner as in Example 2 except that an emulsion polymer with a Tg of about -12°C was used.
40g/acrylic resin converted to SiO ₂ 160g
A metal surface treatment composition was obtained containing 1 g/g/g of the chromium compound () and 1 g/g of the chromium compound (). Comparative Example 3 Example 4 except that methyl methacrylate/2-ethylhexyl acrylate/acrylic acid copolymer having a Tg of 0°C was used instead of the amphoteric ionic acrylic resin () used. Using the same method as in 4, water-dispersible silica () was converted to SiO ₂ at 40 g/acrylic resin () and chromium compound () was 0.5 g/in terms of SiO 2 .
A metal surface treatment composition containing 80 g/g of acrylic resin and 80 g/g of acrylic resin was obtained. Example 6 In Example 2, water-dispersible silica () was prepared in the same manner as in Example 2 except that chromic anhydride was not used.
A metal surface treatment composition was obtained containing 40 g of SiO ₂ and 160 g of acrylic resin. This composition is referred to as Composition F. Comparative Example 4 In Comparative Example 2, water-dispersible silica () was prepared in the same manner as Comparative Example 2 except that chromic anhydride was not used.
40g/acrylic resin converted to SiO ₂
A metal surface treatment composition containing 160g/containing was obtained. Examples 7 to 12 and Comparative Examples 5 to 9 Using commercially available electrogalvanized steel sheets (trade name: ZINKOTE, manufactured by Nippon Steel Co., Ltd.) that were chromate-treated and having a thickness of 0.6 mm, Examples 1 to 1 were prepared. Using the composition obtained in 6 and the compositions obtained in Comparative Examples 1 to 4, respectively,
After spray coating to a film thickness of approximately 2.0μ, heat at 100℃.
Drying was performed for 60 seconds to obtain a surface-treated board. Table 1 shows the test results of these treated plates. The evaluation was conducted as follows. Γ Primary corrosion resistance: A salt spray test was conducted according to JISZ-2371, and the area where white rust occurred was evaluated in %. Γ3T bending workability: The bent surface was crimped with adhesive tape and then peeled off, and evaluated using a 10-point (full-point) system. Γ Drawing workability: After applying oil, using a square head of 50 mm x 50 mm, drawing to a depth of 30 mm with 50 kg of wrinkles suppressed, degreased, and adhesive tape was crimped and peeled off to evaluate its inner and outer surfaces. ◎…no peeling, ○…almost no peeling,
△...Partly peeled off, ×...Full surface peeled off. Γ Blocking resistance: 50% of treated plate coated on both sides
Cut into pieces of mm x 50 mm and stack 4 pieces at 50°C.
After crimping for 20 minutes under a pressure of 1000 kg/cm, the blocking property was measured. ◎...No blocking, ○...Slight blocking, △...Part of the coating film is blocked and peeled off. ×…Full surface blocking Γ Paint adhesion: Commercially available melamine-alkyd resin
90℃ x 20 to make PWC50% film thickness about 25μ
After baking for a minute, Erichsen was extruded to 7 mm, cellophane tape was pressed and then peeled off, and evaluation was made on a 10-point scale (full score).

[Table] From the above test results, it can be seen that the metal surface treatment composition of the present invention is excellent and that the treated galvanized steel is extremely useful. Example 13 Commercially available zinc-aluminum alloy plated steel sheet with a thickness of 0.6 mm (trade name: Super Zinc, manufactured by Nippon Steel Corporation)
After treating the composition (D) obtained in Example 4 to a film thickness of 2 μm, the primary corrosion resistance and blocking resistance were tested in the same manner as in Example 7. Commercially available zinc-aluminum alloy plated steel sheets showed rust on the entire surface after 24 hours, but composition (D)
After 96 hours, no rust was observed on the treated products, and no abnormality was observed in the blocking test.

Claims (1)

[Claims] 1 Water-dispersible silica () per metal surface treatment composition is 0.5 to 0.5 in terms of SiO ₂
Amount in the range of 250 g, alkoxysilane compound having polymerizable unsaturated groups (a) 0.1 to 10% by weight, polymerizable unsaturated carboxylic acid (b)
0 to 20% by weight, (meth)acrylic acid alkyl ester (c) in which the alkyl group has 1 to 8 carbon atoms 20 to 99
% by weight, monomer (d) copolymerizable with these 0 to 40% by weight (however, the total of (a), (b), (c) and (d) is 100% by weight) A cationic and/or copolymer derived from a multilayer structure copolymer obtained by multi-stage emulsion polymerization of monomer components, in which the core portion has a Tg of 15°C or higher and the outermost shell has a Tg of 10°C or lower. Zwitterionic acrylic resin () in an amount ranging from 0.5 to 600 g, chromium compound () in an amount ranging from 0 to 50 g, cationic and/or zwitterionic acrylic resin () with a Tg of 10°C or higher. ) in an amount in the range of 0 to 600 g, and the hydrolyzate of tri- and/or dialkoxysilane compound () in an amount of 0 to 600 g in terms of SiO ₂
Contains an amount in the range of 200g, provided that (), (),
A metal surface treatment composition characterized in that the total of (), () and () does not exceed 700g.