JPH0514037B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a method for manufacturing an electroplated steel sheet, and particularly to a method for manufacturing an electroplated steel sheet containing organic polymer fine particles. For more details, please refer to automobiles, light electrical equipment,
This invention relates to a method for manufacturing electroplated steel sheets that can be used for precoating, etc. (Prior Art) Electroplated steel sheets are already used in various fields. In particular, electrogalvanized steel sheets are widely used in automobiles, light electrical appliances, and pre-coated metals, and their usage tends to be increasing due to their excellent economic efficiency and corrosion resistance. By the way, plated steel sheets are generally coated on the surface for surface decoration and corrosion protection, but on the other hand, they have the disadvantage of poor secondary adhesion to various coatings. In order to improve this drawback, surface treatment of the steel sheet, composite plating, etc. have been studied, and for example, a composite plating method in which fine polymer particles are contained in the metal plating layer is known. To give a more specific example, there is a known technology in which fine polymer particles are dispersed in a metal plating bath using a cationic surfactant, electroplated, and the fine polymer particles are precipitated within the metal plating layer. It is being (For example, Japanese Patent Publication No. 52-25375). However, in this method, the polymer particles themselves do not have a positive charge, but are given a positive charge by using a cationic surfactant, etc., so the polymer particles may eutectoid only in small amounts, or the added cationic surface There were various unavoidable problems such as the plating solution being contaminated by the activator and the like, and furthermore, the performance of the electroplated steel material was reduced because the cationic surfactant was water-soluble. Furthermore, in order to mechanically grind the polymer resin to be used into powder, it is desirable to reduce the particle size to less than 2 μm, which of course is extremely difficult. In short, the particle size of the polymer resin used is usually too large to be applied to an economical electroplating film thickness (3 μm). In addition, when electroplating is applied continuously to steel plates, etc., there is a problem in that the amount of eutectoid metal and polymer resin particles varies significantly due to differences in the flow rate of the plating solution. Still another method is known, in which electroplating is carried out in a galvanizing bath in which a polymer emulsion obtained using various emulsifiers is dispersed, using a steel material as a cathode (for example, as disclosed in JP-A-55-115993). ).
However, this method also had various problems in terms of the mechanical stability of the emulsion and its stability against electrolytes. Furthermore, other known methods include (i) polymerizing vinyl monomers using a nonionic emulsifier to produce an aqueous dispersion and then mixing it with a cationic emulsifier; (ii) A method of obtaining a cationic aqueous dispersion by emulsion polymerizing vinyl monomers using a cationic polymerization initiator in the presence of a cationic emulsifier or in the coexistence of this and a nonionic emulsifier (e.g. (Japanese Patent Publication No. 54-43555), and (iii) emulsion polymerization of vinyl monomers in the presence of a water-soluble cationic polymer substance such as polyvinylpyridine, and (iv) quaternary ammonium salt-based vinyl monomers. emulsion polymerization of vinyl monomers using a cationic polymerization initiator in the presence of a copolymer consisting of a polymer, a tertiary amine type vinyl monomer, and a nonionic vinyl monomer (for example, 59-142202) method was known. However, in the conventional technology described above, not only does the polymer itself not have cationic properties, but also a large amount of cationic emulsifier is used to disperse the polymer particles, or a water-soluble cationic emulsifier is used as one type of emulsifier. Because molecular substances are used, the resulting cationic aqueous dispersion has poor mechanical stability and stability against electrolytes, and even if these can be mixed into the plating solution, there is a risk of contamination of the plating solution with the emulsifier. However, various drawbacks such as a decline in the performance of the plated steel sheets were unavoidable. (Means for Solving the Problems) The present invention has been made in view of the prior art as described above. That is, by first dispersing a cationic aqueous dispersion with a high polymerization rate and excellent stability in a metal plating bath and then electrolyzing it, an electroplated steel sheet with excellent adhesion to the top coating film can be produced. It provides: More specifically, the present invention involves dispersing a cationic aqueous dispersion made of a polymer containing a quaternary ammonium salt in its main chain in a metal plating solution, and simultaneously depositing the aqueous dispersion particles together with the metal on a cathode by electrolysis. The present invention relates to a method for producing an electroplated steel sheet containing organic polymer fine particles. The cationic aqueous dispersion used in the method of the present invention is an aqueous dispersion of fine particles in which the polymer itself has cationic properties. Such aqueous dispersions include, for example, α, β
- A quaternary ammonium salt monomer having a monoethylenically unsaturated carbonyl group is one component, and the monomer is copolymerizable with other α,β-monoethylenically unsaturated monomers. Examples include aqueous dispersions of copolymers. Examples of the quaternary ammonium salt monomer having an α,β-monoethylenically unsaturated carbonyl group include 2-hydroxy-3-methacryloxypropyltrimethylammonium chloride;
2-hydroxy-3-methacryloxypropyltrimethylammonium methylbenzenesulfonate, 2-hydroxy-3-methacryloxypropyldimethylhydroxyethylammonium chloride, 2-hydroxy-3-methacryloxypropyldimethylhydroxyethylammonium methylbenzenesulfonate Acid salt, trimethylaminoethyl acrylamide chloride, trimethylaminoethyl methacrylamide chloride, trimethylaminopropylacrylamide chloride, trimethylaminopropyl methacrylamide chloride, trimethylaminopropylacrylamide bromide, trimethylaminopropyl methacrylamide bromide, trimethylaminobutylacrylamide methyl sulfate Phate, trimethylaminobutyl methacrylamide methyl sulfate, trimethylaminomethyl acrylate chloride, trimethylaminomethyl chloride, trimethylaminoethyl acrylate, trimethylaminoethyl chloride, diethylmethylaminoethyl chloride, diethylmethylaminoethyl methacrylate chloride , trimethylaminopropyl chloride, trimethylaminopropyl chloride methacrylate, and the like. These monomers can be used alone or as a mixture of two or more. In order to obtain a cationic aqueous dispersion with a particularly high polymerization rate, it is preferable to use a quaternary ammonium salt monomer having an α,β-monoethylenically unsaturated carbonyl group represented by the following general formula. General formula: (In the formula, X is CI ^- , Br ^- , I ^- , SO ₄ H ^- , SO ₄ ^-
- represents at least one anion selected from the group of anions consisting of CH ₃ SO ₄ ^- , and CH ₃ COO ^- . R ₁ represents a hydrogen atom or a methyl group, A represents -O- or -NH-, R ₂ represents a chain or branched alkyl group having 1 to 18 carbon atoms, R ₃ , R ₃ ' , R ₃ ″ may be the same or different;
Each represents an alkyl group having 1 to 4 carbon atoms which may have a hydroxyl group as a substituent, or a phenyl group which may have an alkyl group having 1 to 9 carbon atoms as a substituent. ) Specific examples of the monomer include trimethylaminoethyl acrylamide chloride,
Trimethylaminoethyl chloride methacrylamide,
Trimethylaminopropylacrylamide chloride,
Trimethylaminopropyl methacrylamide chloride, trimethylaminopropylacrylamide bromide, trimethylaminopropyl methacrylamide bromide, trimethylaminobutylacrylamide methyl sulfate, trimethylaminobutyl methacrylamide methyl sulfate, trimethylaminomethyl acrylate chloride, trimethylamino chloride Examples include methyl methacrylate, trimethylaminoethyl acrylate chloride, trimethylaminoethyl methacrylate chloride, diethylmethylaminoethyl acrylate chloride, diethylmethylaminoethyl methacrylate chloride, trimethylaminopropyl acrylate chloride, trimethylaminopropyl methacrylate chloride, etc.
Used as a species or a mixture of two or more. Further, other α,β- which is copolymerizable with the quaternary ammonium salt monomer having the α,β-monoethylenically unsaturated carbonyl group used in obtaining the cationic aqueous dispersion. Examples of monoethylenically unsaturated monomers include (A) aromatic vinyl compounds such as styrene, α-methylstyrene, vinyltoluene, monochlorostyrene, and divinylbenzene; (B) vinyl acetate, vinyl propionate, and vinyl butyrate. (C) α,β-monoethylenically unsaturated nitriles such as acrylonitrile and methacrylonitrile, (D)
Methyl acrylate, methyl acrylate, propyl acrylate, isopropyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, glycidyl acrylate, methyl methacrylate, ethyl methacrylate, Propyl methacrylate, isopropyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate,
α,β-monoethylenically unsaturated carboxylic acid esters such as 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, and glycidyl methacrylate; (E) α such as dialkyl fumarate, dialkyl maleate, and dialkyl itaconate; , β-monoethylenically unsaturated dicarboxylic acid dialkyl ester, (F) acrylamide, N-methylolacrylamide, N-methylolmethacrylamide, N-methoxymethylacrylamide, N-methoxymethacrylamide, etc. Saturated amides and their N-substituted derivatives, (G) dimethylaminomethylacrylamide, dimethylaminomethylmethacrylamide, diethylaminomethylacrylamide, diethylaminomethylmethacrylamide, dimethylaminopropylacrylamide, dimethylaminopropylmethacrylamide, dimethylaminoethyl acrylate , α,β-monoethylenically unsaturated amines such as dimethylaminoethyl methacrylate, dimethylaminopropyl methacrylate, diethylaminoethyl acrylate, and diethylaminoethyl methacrylate. These monomers may be used alone or as a mixture of two or more. The cationic aqueous dispersion preferably contains the quaternary ammonium salt monomer having the α,β-monoethylenically unsaturated carbonyl group and the other α,β-monoethylenically unsaturated carbonyl group.
β-monoethylenically unsaturated monomer and the former 0.1
~15% by weight, the latter 99.9~85% by weight, and the average particle size is 0.01~2.0μm
belongs to. In the above weight ratio, if the former is less than 0.1% by weight, the polymerization rate will decrease and the obtained particle size will increase, resulting in a marked decrease in the stability of the aqueous dispersion and agglomeration when added to the plating liquid. If the plating solution is stirred and heated, it tends to fuse easily, and conversely, if it exceeds 15% by weight, the resulting particle size will become smaller, but the amount of water-soluble components will increase, causing agglomeration when added to the plating solution. In addition, the water resistance of the resulting plated steel sheet and the secondary adhesion of the top coat film are reduced. Therefore, in either case, outside the range is not very preferable. The preferable weight ratio of the former and the latter in the above range is 1 to 10% by weight for the former and 99 to 90% by weight for the latter. As a method for obtaining the above-mentioned cationic aqueous dispersion, the α , 0.1 to 15% by weight of a quaternary ammonium salt monomer having a β-monoethylenically unsaturated carbonyl group, and other α,β-
A method in which 100 parts by weight of a monomer consisting of 99.9 to 85% by weight of a monoethylenically unsaturated monomer is copolymerized is preferred. As the polymerization initiator used in the above method, polymerization initiators such as potassium persulfate, ammonium persulfate, benzoyl peroxide, and azobisisobutyronitrile can also be used; In order to reduce the amount of aggregates generated, cationic polymerization initiators such as 2,2'-azobis(2-amidinopropane) hydrochloride, 2,2'-azobis(2-amidinopropane)
Preference is given to using the acetate salt, 2,2'-azobis(N,N'-dimethyleneisobutyramidine) hydrochloride. The cationic polymerization initiator is used in an amount of 0.1 to 3% by weight based on the total monomers used during polymerization. Water as a polymerization medium in the polymerization method;
The ratio of total monomer amounts is 100 parts by weight of monomer to about 100 to 1900 parts by weight of water. In other words, the heating residue of the final cationic aqueous dispersion is
A proportion of 50% by weight is preferred. If the polymerization is carried out at a ratio such that the heating residue becomes 50% by weight or more within the above range, it is not preferable because a large amount of aggregates will be generated in the system. On the other hand, the lower the heating residue during polymerization, the less aggregates will be generated. This is both undesirable as it dilutes it. The above-mentioned cationic aqueous dispersion can be obtained at a polymerization rate of about 98% by weight by emulsion polymerization at a reaction temperature of about 55 to 90° C. for about 2 to 10 hours using a known dropping method. In the above polymerization method, the quaternary ammonium salt monomer having an α,β-monoethylenically unsaturated carbonyl group is difficult to dissolve in other monomers, so it is added in advance to a portion of the water used as the polymerization medium. Preferably, it is dissolved and added dropwise at the same time as the other monomers through a separate dropping funnel. Incidentally, a commonly used chain transfer agent such as dodecyl mercaptan may be used in combination during the polymerization reaction. As described above, the cationic aqueous dispersion used in the method of the present invention has cationic properties in the polymer fine particles themselves, so that the purpose of the present invention can be achieved even without the use of a cationic surfactant (soap-free). This method is characterized in that it does not cause contamination of the plating solution or deterioration of the performance of the formed film. Therefore, in order to reduce the particle size of the polymer particles and to reduce the amount of aggregates generated during polymerization, a very small amount of non-ionic material such as polyoxyethylene nonyl phenyl ether or polyoxyethylene lauryl ether may be used. Surfactants, cationic surfactants such as lauryltrimethylammonium chloride can also be used. However, the added surfactant can contaminate the plating solution, and since the surfactant is water-soluble, the performance of the plated steel sheet cannot be avoided, so the amount added is large relative to the total monomer. Both are up to 5% by weight. The cationic aqueous dispersion as described above has α,β-
It is a copolymer with a number average molecular weight of approximately 1,500 to 10,000, in which a quaternary ammonium salt monomer having a monoethylenically unsaturated carbonyl group is copolymerized as one component of the copolymer, and the particles are cationic. Even without using any surfactant, it can be stably dispersed in water due to its self-emulsifying effect. It is also stable in the plating solution and stable against vigorous mechanical agitation, so it is particularly preferred for the method of the present invention. Furthermore, when the Metsuki liquid is heated and used,
In particular, the glass transition temperature of the copolymer is 20° higher than the operating temperature.
If the temperature is lower than ℃, the copolymer particles added to the plating solution may fuse together. In this case, if the glass transition temperature of the copolymer is raised to near the operating temperature, the plating solution containing the aqueous dispersion will remain stable even when heated or stirred vigorously at that temperature.
It is stable without aggregation or fusion. Therefore, it is preferable to appropriately select the monomer for obtaining the copolymer in accordance with the operating temperature of the plating solution to prevent fusion of the copolymer particles. In particular, by using a monomer with a long side chain as a component of the copolymer, it is possible to prevent particles from fusing together. The method of the invention is effective for all electroplating methods. Furthermore, when using acidic zinc chloride baths, acidic zinc sulfate baths, zinc alloy plating baths made by adding salts such as nickel, cobalt, chromium, etc. to these baths, and acidic baths such as nickel sulfate baths and copper sulfate baths, is even more effective. As for the method of adding the cationic aqueous dispersion to the plating solution, if a highly concentrated cationic aqueous dispersion is added to the plating solution without stirring, the aqueous dispersion may aggregate. Therefore,
It is preferable that the concentration of the aqueous dispersion is adjusted to a range of about 10 to 15% by weight based on the heating residue, and added to the plating solution being stirred. Furthermore, if the plating liquid containing the cationic aqueous dispersion foams when stirred vigorously, add an antifoaming agent such as silicone, or use ultrasonic waves at about 20Hz to defoam. Good too. Even if the amount of the cationic aqueous dispersion added to the plating solution is 1 g/resin content, it has the same effect.
In order to increase the effect of addition, it is preferable that the amount of resin added to the aqueous dispersion is in the range of 5 to 50 g. There is no particular deadline as a condition for Metsuki. That is, it can be carried out under substantially the same conditions as those normally employed without the addition of an aqueous dispersion. Specifically, the pretreatment of the material to be plated involves solvent degreasing,
Perform electrolytic degreasing and pickling in the usual manner, bath temperature during electroplating is 20-60℃, current density is 1-100A/d.
Do it in ^m2 . Thus, the bare corrosion resistance of the electroplated steel sheet obtained as a result of the implementation of the method of the present invention is comparable to that of the galvanized steel sheet that does not contain an aqueous dispersion, but it is furthermore If paints that are normally applied to galvanized steel sheets, such as resin-based baking paints, polyester resin-based baking paints, and epoxy resin-based baking paints, are applied on the plated steel sheets without pretreatment such as phosphate treatment or chromate treatment, the paint Adhesion to the film, processability, water resistance, corrosion resistance, etc. are significantly improved, and in particular, the secondary adhesion of the coating film after immersion in boiling water is recognized to be dramatically improved. Hereinafter, the details of the present invention will be explained with reference to Examples. In the examples, "parts" or "%" are expressed as "parts by weight" or "% by weight." Example 1 241.5 parts of deionized water was placed in a 5-necked flask equipped with two dropping funnels, a condenser, a thermometer, and a stirring bar, and heated to 73°C in a water bath. 2′-azobis(2-
0.5 part of (amidinopropane) hydrochloride was added, and while the reaction temperature was kept at 73°C, the following monomers were simultaneously added dropwise over 2 hours. First dropping funnel Methyl methacrylate 54.0 parts 2-ethylhexyl methacrylate 37.0 parts 2-hydroxyethyl methacrylate 4.0 parts Second dropping funnel Trimethylaminoethyl chloride methacrylate
5.0 parts Deionized water 60.0 parts After the dropwise addition, the reaction temperature was raised to 84°C in about 30 minutes.
The reaction was carried out at that temperature for 90 minutes. The obtained cationic aqueous dispersion had no monomer odor, had almost no aggregates even when filtered through a 300-mesh wire mesh, had a polymerization rate of 99%, and was in good condition. The properties of the aqueous dispersion include a heating residue of 24.8% and a viscosity of
7.4 cps (25° C.), PH 4.1, average particle diameter 0.07 μm, number average molecular weight 2,600, and weight average molecular weight 75,000. This aqueous dispersion was diluted with deionized water to a heating residue of 15% and used for plating solution addition. Add 67g of this diluted aqueous dispersion (resin content: 10g) to zinc chloride.
Even when the copolymer particles were added to an electrogalvanizing solution containing 200 g of potassium chloride and 300 g of potassium chloride and vigorously stirred at 50° C., the copolymer particles remained stable without agglomerating or fusing. Using ^this plating solution, the plating layer was approximately
A 3 μm electrogalvanized steel sheet was obtained. The plated steel plate was coated with an acrylic resin baking paint, and the secondary adhesion of the coating film was tested after 2 hours of immersion in boiling water, and the results were very good. [100/100 remaining number of grid marks at 1 mm intervals: Displayed in the same manner below. ] For comparison, a plated steel plate was obtained in the same manner as above without adding an aqueous dispersion, and then tested in the same manner. Even after 30 minutes of immersion in boiling water, the secondary adhesion was very poor. [Goban number remaining 0/
100] Also, the amount of the aqueous dispersion added was 7 g (resin content 1
g) and 200g (resin content 30g), but
The plating solution was similarly stable, and the adhesion of the acrylic resin baking paint film to the plated steel sheet obtained from the plating solution after immersion in boiling water was as good as described above. Example 2 67 g of the aqueous dispersion prepared in Example 1 (resin content: 10
g), zinc sulfate 250g/, sodium sulfate 30g
g/, ammonium sulfate 20g/ to electrolytic galvanizing solution, bath temperature 40℃, current density 20A/d.
An electrolytic galvanized steel sheet having a plating layer of approximately 3 ^μm was obtained under a current flow time of 36 seconds. This plated steel plate was coated with an acrylic resin baking paint, and the secondary adhesion was tested after being immersed in boiling water for 2 hours, and the results were very good. For comparison, a plated steel plate was obtained in the same manner as above without adding an aqueous dispersion, and then tested in the same manner, but the secondary adhesion was very poor even after 30 minutes of immersion in boiling water. Example 3 67 g of the aqueous dispersion prepared in Example 1 (resin content: 10
g), zinc sulfate 270g/, nickel chloride 60
Electrolytic zinc plating layer of approximately 3 μm was added to an electrolytic nickel plating solution containing 30 g/g of boric acid and 30 g/dm of boric acid at a bath temperature of 40°C, a current density of 20 A/dm ² , and a current application time of 36 seconds.
A nickel alloy plated steel plate was obtained. This plated steel plate was coated with an acrylic baking paint, and the secondary adhesion was tested after being immersed in boiling water for 2 hours, and the results were very good. [Goban eyes remaining number 100/
[100] For comparison, a plated steel plate was obtained in the same manner as above without adding an aqueous dispersion, and then tested in the same manner, but the secondary adhesion was very poor even after 30 minutes of immersion in boiling water. [Remaining number of gobans 0/100] Example 4 241.5 parts of deionized water was placed in a 5-necked flask equipped with two dropping funnels, a condenser, a thermometer, and a stirring bar, and heated to 73°C in a water bath. , 2,2′-azobis(2-
0.5 part of (amidinopropane) hydrochloride was added, and the following monomers were simultaneously added dropwise over 2 hours while maintaining the reaction temperature at 73°C. First dropping funnel Methyl methacrylate 58.0 parts 2-ethylhexyl methacrylate 40.0 parts Dodecyl mercaptan 0.1 part Second dropping funnel Trimethylaminoethyl methacrylate chloride 2.0 parts Deionized water 60.0 parts After the addition is complete, the reaction temperature is raised to 84°C in about 30 minutes. Raise,
The reaction was carried out at that temperature for 90 minutes. The obtained cationic aqueous dispersion had no monomer odor, had almost no aggregates even when filtered through a 300-mesh wire mesh, had a polymerization rate of 98.5%, and was in good condition. The properties of the aqueous dispersion are: heating residue: 24.6%, viscosity:
4.0 cps (25°C), pH 4.1, average particle diameter 0.17 μm, number average molecular weight 3000, and weight average molecular weight 73000. This aqueous dispersion was diluted with deionized water to a heating residue of 15% and used for plating solution addition. Add 67g of this diluted aqueous dispersion (resin content: 10g) to zinc chloride.
Even when the copolymer particles were added to an electrolytic galvanizing solution containing 200 g of potassium chloride and 300 g of potassium chloride, and were stirred vigorously at 50° C., the copolymer particles remained stable without agglomerating or fusing. Using this plating liquid, bath temperature is 50℃,
An electrogalvanized steel sheet with a plating layer of approximately 5 μm was obtained at a current density of 30 A/dm ² and a current application time of 40 seconds. The plated steel plate was coated with an acrylic resin baking paint, and the secondary adhesion of the coating film was tested after 2 hours of immersion in boiling water, and the results were very good. [Remaining number of gobans 100/100] Example 5 251.8 parts of deionized water was placed in a 5-necked flask equipped with two dropping funnels, a condenser, a thermometer, and a stirring bar, and heated to 73°C in a water bath. , 2,2′-azobis(2-
0.5 part of (amidinopropane) hydrochloride was added, and the following monomers were simultaneously added dropwise over 2 hours while maintaining the reaction temperature at 73°C. First dropping funnel Methyl methacrylate 52.0 parts 2-ethylhexyl methacrylate 34.0 parts Dihydroxyethyl methacrylate 4.0 parts Dodecyl mercaptan 0.1 parts Second dropping funnel Trimethylaminoethyl methacrylate chloride
10.0 parts Deionized water 50.0 parts After the dropwise addition, the reaction temperature was raised to 84°C in about 30 minutes.
The reaction was carried out at that temperature for 90 minutes. The obtained cationic aqueous dispersion had no monomer odor, had almost no aggregates even when filtered through a 300-mesh wire mesh, had a polymerization rate of 99%, and was in good condition. Comparative Example 1 Zinc chloride 200g/potassium chloride 300g/The following aqueous dispersion (heating residue 15%, resin content 10%) mixed in advance in electrogalvanizing solution 1 having the above composition.
g) was added with stirring to prepare a plating bath. Synthetic rubber latex CROSLENE CMX−05
22g [Heating residue 45.5%, PH7, particle size 0.4μm: Takeda Pharmaceutical Co., Ltd.] Cationic surfactant Cortamine 24P 2g [Lauryltrimethylammonium chloride active ingredient 27%: Kao Soap Co., Ltd.] Deionized Water 43g Using this plating bath, bath temperature 25℃, current density
The plating layer is approximately 3μm at 30A/dm ² and 24 seconds of current.
Electrogalvanized steel sheets were obtained. The plated steel plate was coated with an acrylic resin baking paint, and the secondary adhesion of the coating film was tested after 2 hours of immersion in boiling water, but the adhesion was poor. [Number of remaining Goban eyes
50/100] Furthermore, in this plating bath, when the bath temperature was set to 50°C, the aqueous dispersion was fused and could not be redispersed. Comparative Example 2 Zinc chloride 200g/potassium chloride 300g/The following aqueous dispersion (heating residue 15%, resin content 10%) mixed in advance in electrogalvanizing solution 1 having the above composition.
g) was added with stirring to prepare a plating bath. Acrylic resin fine powder Plex 4885F 10g [Particle size 2μm: Manufactured by Rohm GmdH, West Germany] Cationic surfactant Cortamine 24P 2g Deionized water 55g Using this plating bath, bath temperature 25℃, current density
The plating layer is approximately 3μm at 30A/dm ² and 24 seconds of current.
Electrogalvanized steel sheets were obtained. The plated steel plate was coated with an acrylic resin baking paint, and the secondary adhesion of the coating film was tested after 2 hours of immersion in boiling water, but the adhesion was poor. [Number of remaining Goban eyes
20/100] Comparative Example 3 Zinc chloride 200g/potassium chloride 300g/20g of a nonionic aqueous dispersion (heating residue 45%) pre-emulsion polymerized with the following composition was added to electrolytic galvanizing solution 1 having the above composition while stirring. and prepared a plating bath. Methyl acrylate 30 parts Methyl methacrylate 14 parts Methacrylic acid 1 part Water 54 parts Ammonium persulfate 0.05 parts Alkylaryl polyether 10 parts Using this plating bath, bath temperature 25℃, current density
The plating layer is approximately 3μm at 30A/dm ² and 24 seconds of current.
Electrogalvanized steel sheets were obtained. The plated steel plate was coated with an acrylic resin baking paint, and the secondary adhesion of the paint film was tested after 2 hours of immersion in boiling water, but the adhesion was poor (remaining number of gobbles: 60/1).
00). Comparative Example 4 An attempt was made to obtain a cationic aqueous dispersion containing tertiary amino groups in the copolymer particle skeleton using the following formulation and conditions. A 5-neck flask equipped with two dropping funnels, a condenser, a thermometer, and a stirrer was charged with 110.9 parts of deionized water and heated to 73°C in a water bath. After 5 minutes had elapsed, the following monomers were simultaneously added dropwise over 2 hours while maintaining the reaction temperature at 73°C. First dropping funnel Methyl methacrylate 56.0 parts 2-ethylhexyl methacrylate 38.0 parts 2-hydroxyethyl methacrylate 4.0 parts Dodecyl mercaptan 0.1 parts Second dropping funnel Dimethylaminoethyl methacrylate 2.0 parts Deionized water 40.0 parts Adding monomers Agglomeration of the dispersion began midway, and by the time the dropwise addition was complete, stirring became difficult, and the entire dispersion had become aggregates. A normal aqueous dispersion could not be obtained. Comparative Example 5 Polymerization was carried out in the same manner as in Comparative Example 4, except that 6.0 parts of lauryltrimethylammonium chloride as a cationic surfactant was mixed in advance in the flask, and a normal aqueous dispersion was obtained. The aqueous dispersion (heated residue 40%, resin content 10 g) was added to electrogalvanizing solution 1 consisting of 200 g of zinc chloride/300 g of potassium chloride with stirring to prepare a plating bath. After obtaining an electrogalvanized steel sheet in the same manner as in Comparative Example 4, the same adhesion test was conducted, but the adhesion was very poor (number of remaining goblets 40/100). Furthermore, when the plating bath temperature was set to 50°C, the aqueous dispersion was fused and could not be redispersed.

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Claims (1)

[Claims] 1. A method characterized by dispersing a cationic aqueous dispersion made of a polymer containing a quaternary ammonium base in a metal plating solution, and simultaneously depositing the aqueous dispersion particles together with the metal on a cathode by electrolysis. A method for producing an electroplated steel sheet containing organic polymer fine particles. 2 A cationic aqueous dispersion consisting of a polymer containing a quaternary ammonium base is
% by weight of a quaternary ammonium salt monomer having an α,β-monoethylenically unsaturated carbonyl group;
The organic polymer according to claim 1, comprising copolymer particles with an average particle diameter of 0.01 to 2.0 μm and 99.9 to 85% by weight of other α,β-monoethylenically unsaturated monomers. A method for producing an electroplated steel sheet containing fine particles. 3 The quaternary ammonium salt monomer having an α,β-monoethylenically unsaturated carbonyl group has the general formula: (In the formula, x: CI ^- , Br ^- , I ^- , SO ₄ H ^- ,
represents at least one anion selected from the group consisting of SO ₄ ^-- , CH ₃ SO ₄ ^-- , and CH ₃ COO ^-- , R: hydrogen atom or methyl group, A: -O- or -NH- R ₂ : represents a chain or branched alkyl group having 1 to 18 carbon atoms, R ₃ , R ₃ ′, R ₃ ″: may be the same or different, each substituted with a hydroxyl group (Indicates an alkyl group having 1 to 4 carbon atoms which may be a substituent, or a phenyl group which may have an alkyl group having 1 to 9 carbon atoms as a substituent.) A method for producing an electroplated steel sheet containing the organic polymer fine particles according to item 2.