JPH0534389B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a surface treatment composition applied to the surface of chromate-treated zinc-plated steel. More specifically, the present invention relates to a zinc-based plating that is applied to the surface of chromate-treated zinc-plated steel to provide the surface with excellent fingerprint resistance, corrosion resistance, solvent resistance, adhesion, and paint base properties. The present invention relates to a composition for surface treatment of steel materials. [Prior Art and its Problems] Zinc-based galvanized steel materials have poor corrosion resistance and coating base properties when left as is, so they are usually treated with chromate or phosphate. Of these, the chromate treatment method provides considerable corrosion resistance, but as a paint base, the adhesion to the paint film is insufficient, and the chromate-treated surface leaves fingerprints during handling. This causes problems in that the commercial value is lost and the corrosion resistance of the part is deteriorated. In order to solve these problems, corrosion resistance and fingerprint resistance can be slightly improved by applying chromate treatment to the surface of zinc-plated steel and then painting with water-soluble resin or emulsion type resin. However, it is still insufficient. This is because water-soluble resins have many hydrophilic groups and have a low molecular weight, resulting in poor water resistance and solvent resistance, and emulsion-type resins generally contain emulsifiers that adversely affect the corrosion resistance of steel materials and adhesion to paint films. [Means for Solving the Problems] As a result of intensive studies to solve the above-mentioned conventional drawbacks, the present invention has been completed. That is, the present invention provides P-OH in a phosphoric acid ester of an epoxy resin produced by esterifying at least a part of the terminal epoxy groups of an epoxy resin with a phosphorus-containing acid.
Using a water-dispersible or water-soluble modified epoxy resin (hereinafter simply referred to as modified epoxy resin) obtained by neutralizing some or all of the groups with a base as an emulsifier,
An emulsion polymer obtained by emulsion polymerization of an ethylenically unsaturated monomer containing 1 to 20% by weight of an α/β-monoethylenically unsaturated carboxylic acid monomer, the water-dispersible or water-soluble modified epoxy resin and the ethylenically unsaturated monomer in a weight percentage of 1/99 to 50/
50, which is applied to the surface of chromate-treated zinc-plated steel. [Operation] P- in the phosphoric acid ester of the epoxy resin produced by esterifying at least a part of the terminal epoxy resin of the epoxy resin with a phosphorus-containing acid.
When part or all of the OH groups are neutralized with a base, a modified epoxy resin having a hydrophilic part and a hydrophobic part in one molecule can be obtained. Therefore, it is presumed that the modified epoxy resin plays a role as a kind of dispersion stabilizer or emulsifier. Therefore, if the modified epoxy resin is used in emulsion polymerization, emulsion polymerization can be carried out without the presence of a conventional emulsifier or the like. When an emulsion polymer using the modified epoxy resin forms a film, the epoxy resin is mixed with the polymer constituting the emulsion polymer and has the characteristics as an epoxy resin, that is, excellent rigidity, adhesion, and corrosion resistance. , impart chemical resistance, etc. to the film. In addition, the phosphorus-containing acid groups of the modified epoxy resin are thought to have the function of improving adhesion to metals and coating base properties, and in fact, the above-mentioned problem of insufficient adhesion to the paint film can be solved. This problem has been solved by the present invention. In addition, by selecting and using an appropriate (meth)acrylic acid ester monomer as the ethylenically unsaturated monomer used in emulsion polymerization, coatings ranging from flexible and stretchy to extremely hard can be produced. can be obtained. By adding ammonium chromate or ammonium dichromate to the composition of the present invention, the surface of zinc-plated steel material that has not been chromate-treated can be chromate-treated at the same time as the resin film is formed, and the steel material can be chromate-treated in advance. The existing chromate layer is further strengthened even in cases where the resin film suppresses the permeation of oxygen, ions, and water, and the corrosion suppressing effect of chromic acid is synergized, and the resin film crosslinks with metal chromium to improve its density. will improve. <Modified epoxy resin> Several proposals have already been made regarding modified epoxy resins (for example, Japanese Patent Application Laid-Open No. 179278/1983), and the epoxy resin used in the present invention is based on such already known epoxy resins. It can be manufactured according to the following method. The outline is as follows. *Epoxy resin The epoxy resin used in the modified epoxy resin of the present invention has the following general formula: In formula (1), X is H or an alkyl group, preferably a lower alkyl group having 4 or less carbon atoms. It has more than one substituted or unsubstituted glycidyl ether group shown in the molecule,
Common epoxy resins obtained by the reaction of epichlorohydrin and bisphenols or polyhydric alcohols, such as diglycidyl ether of bisphenol A, diglycidyl ether of bisphenol F, diglycidyl ether of polyhydric alcohol, and phenol novo. Various resins such as lacquer epoxy resin and diglycidyl ether of alkylene oxide adducts of bisphenols can be used, but diglycidyl ether of bisphenol A is preferably used from the viewpoint of adhesion and corrosion resistance. There is no particular restriction on the epoxy equivalent, but preferably an epoxy equivalent of about 100 to 1,000. *Esterification and neutralization with phosphorus-containing acids Phosphorus-containing acids used as raw materials for modified epoxy resins are acids that have phosphorus atoms in their molecules.
Examples include orthophosphoric acid, metaphosphoric acid, pyrophosphoric acid, phosphorous acid, polyphosphoric acid, phosphonic acid, phosphinic acid, and orthophosphoric acid is particularly preferred. The phosphoric acid ester of the epoxy resin can be obtained by mixing the epoxy resin and the phosphorus-containing acid and heating and reacting the mixture in the presence or absence of a solvent. When using a solvent, it is preferable to add a small amount of a water-soluble solvent such as methyl ethyl ketone or ethyl cellosolve to the extent that the reaction between the epoxy resin and the phosphoric acids proceeds smoothly. There is no particular restriction on the heating temperature, but it is preferable to carry out the heating at a temperature sufficient to prevent decomposition of the epoxy resin and to complete the reaction in an appropriate time, and generally a temperature of 0°C or higher and 150°C or lower is applied. Neutralization of the phosphoric acid ester with a base may be carried out by a known method, such as ammonia, amine,
Although this can be done using a base such as an alkali metal compound, it is preferable to use ammonia from the viewpoint of corrosion resistance, since it will not volatilize during film formation at room temperature and will not remain in the film. Furthermore, when the membrane is dried by heating, a low boiling point amine may be used. There are no particular restrictions on the degree of neutralization, but it is necessary that the modified epoxy resin has water dispersibility or water solubility, and for this purpose it is appropriate to set the pH to 3 or higher. Specifically, neutralization takes into consideration factors such as the type of monomer to be polymerized and the desired PH value of the polymerization system, and neutralizes the P-OH in the phosphoric acid ester.
This can be carried out by neutralizing part or all of the groups with a base. The modified epoxy resin produced in this manner is water-dispersible or water-soluble, or a mixture thereof, and is preferably used in the present invention. <α/β-monoethylenically unsaturated carboxylic acid monomer and ethylenically unsaturated monomer> Suitable α/β-monoethylenically unsaturated carboxylic acid monomers used in the present invention An example is shown below. Unsaturated basic acids such as acrylic acid and methacrylic acid and their salts, unsaturated dibasic acids such as itaconic acid, fumaric acid, and maleic acid, and their half esters and their salts The above α/β-monoethylenically unsaturated The amount of carboxylic acid monomer must be at least 1% by weight of the total monomer in view of stability when mixed with a chromium compound.On the other hand, if too much is used, the water resistance of the film will deteriorate, so It is desirable to keep it within 20% by weight. Examples of ethylenically unsaturated monomers used in the present invention include the following. These are selected depending on the purpose, copolymerizability, etc., and one or more types are used. 1 α/β-unsaturated carboxylic acid esters, such as methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, cyclohexyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n-methacrylate Alkyl esters of acrylic acid or methacrylic acid such as butyl, isobutyl methacrylate, cyclohexyl methacrylate, 2-ethylhexyl methacrylate, hydroxyalkyl acrylates and methacrylates such as hydroxypropyl acrylate, amino group-containing esters of dimethylaminoethyl methacrylate, Glycidyl group-containing esters such as glycidyl methacrylate, and esters of maleic acid, fumaric acid, and itaconic acid. 2 Amides of α/β-unsaturated acids, such as acrylamide, methacrylamide, maleic acid amide and maleic imide. 3 Substituted amides of unsaturated carboxylic acids, e.g. N-
Methylol acrylamide and methacrylamide, diacetone acrylamide, N-butoxymethyl acrylamide, etc. 4 Vinyl esters such as vinyl acetate, vinyl propionate and vinyl chloride. 5 Nitriles of α/β-unsaturated carboxylic acids, such as acrylonitrile, methacrylonitrile, etc. 6 Vinyl ethers, such as vinyl ethyl ether. 7 Vinyl ketones, such as vinyl methyl ketone. 8 vinylamide, e.g. vinylformamide,
Vinylacetamide etc. 9 Aromatic vinyl compounds, such as styrene, vinyltoluene, etc. 10 Heterocyclic vinyl compounds, such as vinylpyridine, vinylpyrrolidone, etc. 11 Vinylidene halides compounds, such as vinylidene chloride, vinylidene fluoride, etc. 12 Divinyl compounds, such as divinylbenzene,
butanediol dimethacrylate etc. 13 α-Olefins, such as ethylene, propylene, etc. 14 Diolefins, such as butadiene, isoprene, etc. 15 Acrylic compounds such as allyl acetate, allyl alcohol and diallyl phthalate. By combining various of these monomers, for example, by combining acrylic ester to give a soft polymer and methacrylic ester or styrene to give a hard polymer, it is possible to change from hard resin to soft resin, from normal temperature drying to heat drying. It is possible to obtain various types of resins, and by using reactive monomers, it is also possible to make bake-curable resins, which can provide various properties in addition to the properties of modified epoxy resins. . <Emulsion Polymerization Method> The amount of modified epoxy resin used in the method for producing an emulsion polymer according to the present invention is determined by weight percentage of modified epoxy resin/ethylenic unsaturated monomer=
It can be used in the range of 1/99 to 50/50, but
More preferably, the range is from 3/97 to 25/75.
If the modified epoxy resin is less than 1/99, the dispersion stability of the monomer will not be sufficient and polymerization will not proceed smoothly, and the resulting emulsion polymer will not exhibit the characteristics of an epoxy resin very well. Modified epoxy resin
When the ratio is more than 50/50, there is too much epoxy resin, which tends to cause gelation during polymerization. As a method for producing the emulsion polymer of the present invention, a method similar to a known method may be used. For example, a glass flask is charged with deionized water and a modified epoxy resin, and a base is used to adjust the pH of the system to be suitable for polymerization.
Adjust to 3.0 to 9.0 to create a dispersion with a solid content of 0.1 to 40%. Next, the mixture is degassed with nitrogen gas, and ethylenically unsaturated monomers are sequentially charged while stirring while heating, and a polymerization reaction is carried out according to a conventional method. At this time, the monomers may be added all at once, divided, or continuously.
As the radical generation catalyst, hydrogen peroxide, t-butyl hydroperoxide, ammonium persulfate, potassium persulfate, etc. are diluted with deionized water and added dropwise or all at once, and the reaction temperature is preferably
2 at 100℃ or less, more preferably 30 to 90℃
Polymerize over an hour. In this case, if a reducing agent such as sodium sulfite, ferrous sulfate, or Rongarit is used in combination, the polymerization reaction can proceed smoothly even at low temperatures. After the polymerization is completed, if desired, neutralization is performed with a base to adjust the pH to 5 to 10 to obtain a stable milky white emulsion polymer. At this time, if ammonia water or amine is used, preferably PH
It is best to adjust it to 6-8. Emulsion polymers can usually be obtained at concentrations below 60% solids. <Addition of chromium compound> If the zinc-plated steel material to which the composition of the present invention is to be applied has not been chromate-treated, or if the chromate layer on the surface of the steel material is not sufficiently thick even if it has been chromate-treated, , a chromium compound is further added to the composition of the invention. In other words, the zinc-plated steel materials targeted by the present invention are those that have been previously treated with chromate, and the chromate blended into the composition of the present invention can be used simultaneously with the formation of a coating film during the painting process. Any of those treated with chromate may be used. The amount of ammonium chromate or ammonium dichromate used in the present invention is preferably 0.01 to 20%, more preferably 0.3 to 15%, based on the solid content of the resin. If it is less than 0.01%, the effect of adding ammonium chromate or ammonium dichromate cannot be obtained;
If the amount is more than 1, it will be too crosslinked with the resin, making it difficult to obtain a good film. On the other hand, a problem arises in that excess chromium is easily eluted. The ammonium chromate or ammonium dichromate used in the present invention is usually preferably added in the form of an aqueous solution. The concentration may be lower than the solubility, but preferably 5 to 20%. As for the addition method, it is preferable to add it little by little at a low temperature of 5 to 30°C while stirring. Solutions of the emulsion polymers of the present invention with ammonium chromate or ammonium dichromate are stable over a wide range of concentrations over long periods of time. Incidentally, in the present invention, addition of the above-mentioned chromium compound is not necessarily essential. There are cases where the addition of the chromium compound is not necessary, for example, when the chromate layer on the surface of the steel material is thick and the steel material itself has sufficient corrosion resistance. <Uses> In addition to ammonium chromate or ammonium dichromate, the emulsion polymer of the present invention further contains crosslinking agents such as urea resins and melamine resins, other water-soluble organic resins such as phenolic resins and epoxy resins,
It may be mixed with a water-dispersible or water-soluble inorganic substance such as colloidal silica, and on the other hand, an inhibitor such as a pigment such as titanium oxide or calcium carbonate, a general rust preventive pigment, or a primary rust preventive agent may be added. Also,
A thickener, a dispersant, a film-forming aid, an antifoaming agent, an organic solvent, etc. may be added. As a surface treatment method for the zinc-plated steel material using the treatment bath of the present invention thus prepared, conventional methods such as brush coating, spray coating, roll coating, and dip coating can be used. Note that the zinc-based plated steel material may be subjected to phosphate treatment. Drying is usually performed at room temperature to
Dry at a temperature of 200°C for about 5 seconds to 15 minutes. For example, when a crosslinking agent such as the above-mentioned urea resin or melamine resin is added, drying and baking hardening are performed at a temperature of about 100 to 200°C. The film thickness is usually adjusted to about 0.1 to 20 μm as a dry film thickness. [Effects of the Invention] Therefore, in the present invention, a modified epoxy resin having excellent rigidity, adhesion, corrosion resistance, chemical resistance, etc. is used as a dispersion stabilizer or emulsifier without using a usual emulsifier. Accordingly, the film has excellent rigidity, adhesion, corrosion resistance, chemical resistance, water resistance, etc. Furthermore,
Because of the phosphorus-containing acid groups contained in the modified epoxy resin, the film has excellent adhesion to metals and excellent coating base properties. In the present invention, by selecting an appropriate ethylenically unsaturated monomer during polymerization, a wide range of films ranging from flexible films to hard films can be obtained. Furthermore, by adding ammonium chromate or ammonium dichromate, the corrosion resistance of zinc-plated steel can be further improved, and the solvent resistance can also be improved. This provides a zinc-plated steel material with excellent anti-fingerprint properties. Furthermore, the emulsion polymer of the present invention has little foaming, low odor, and good mechanical stability. Next, the present invention will be explained in more detail with reference to Examples and Comparative Examples. Parts and percentages used below are by weight unless otherwise specified.
shall be shown. Example 1 35 parts of bisphenol A diglycidyl ether (epoxy equivalent: 250) was dissolved in 15 parts of ethyl cellosolve, and 3 parts of orthophosphoric acid was further mixed with the solution, reacted at 50°C for 3 hours, and then dissolved at 80°C. The temperature was raised to 0.degree. C. and the reaction was further carried out for 5 hours to obtain a phosphoric acid esterified epoxy resin. The epoxy resin has a solid content
70%, varnish acid value 140, and viscosity 200 ps. After adding 7 parts of 25% ammonia water to this and stirring well,
Add 1183 parts of deionized water and add another 25% while stirring.
The pH of the system was adjusted to 6.0 with aqueous ammonia, and the phosphoric acid esterified epoxy resin was dispersed in water. The above dispersion was transferred to a flask equipped with a stirrer, a cooling tube, and a temperature control device, and the temperature was raised to 65° C. while stirring. Then, keep the temperature at 65℃ and add 350 parts of ethyl acrylate and 315 parts of ethyl methacrylate.
part, mixed ethylenically unsaturated monomer consisting of 35 parts of methacrylic acid, t-butyl hydroperoxide
An aqueous solution of 3.5 parts of Rongalit in 53 parts of deionized water and an aqueous solution of 3.5 parts of Rongalit in 53 parts of deionized water are each added dropwise through separate addition funnels over a period of 4 hours. After the dropwise addition was completed, stirring and heating were continued for 2 hours to complete the reaction, and an emulsion polymer having a pH of 5.0 and a solid content of 35% was obtained. Thereafter, the pH of the system was adjusted to 7.5 with 25% aqueous ammonia. This emulsion polymer
An aqueous ammonium chromate solution adjusted to 200 g/210 g was gradually added at room temperature while stirring.
The mixed solution thus obtained is used as composition (A).
shall be. Example 2 Same method as Example 1, but mixed ethylenically unsaturated monomers were prepared from 150 parts of ethyl acrylate, 200 parts of n-butyl acrylate, 150 parts of styrene, 165 parts of ethyl methacrylate, and 35 parts of methacrylic acid. An emulsion polymer having a pH of 5.0 and a solid content of 35% was obtained. Then, adjust the pH of the system with 25% ammonia water.
Adjusted to 7.5. To this emulsion polymer, an aqueous ammonium chromate solution adjusted to 200 g/210 was gradually added at room temperature while stirring. The mixed solution thus obtained is referred to as composition (B). Example 3 The method was the same as in Example 1, but the mixed ethylenically unsaturated monomer was replaced with a mixture consisting of 350 parts of ethyl acrylate, 315 parts of ethyl methacrylate, and 35 parts of acrylic acid, and the solid content was adjusted to PH4.0. A 35% emulsion polymer was obtained. Then, adjust the pH of the system with 25% ammonia water.
Adjusted to 7.5. To this emulsion polymer, an aqueous ammonium chromate solution adjusted to 200 g/210 was gradually added at room temperature while stirring. The mixed solution thus obtained is referred to as composition (C). Example 4 The method was the same as in Example 1, but the mixed ethylenically unsaturated monomer was replaced with a mixture consisting of 350 parts of ethyl acrylate, 280 parts of ethyl methacrylate, and 70 parts of methacrylic acid, and the pH 4.5 solid content was A 35% emulsion polymer was obtained. Then, adjust the pH of the system with 25% ammonia water.
Adjusted to 7.5. To this emulsion polymer, an aqueous ammonium chromate solution adjusted to 200 g/210 was gradually added at room temperature while stirring. The mixed solution thus obtained is referred to as composition (D). Example 5 490 parts of bisphenol A diglycidyl ether (epoxy equivalent 250) was dissolved in 210 parts of ethyl cellosolve in a beaker, 42 parts of orthophosphoric acid was further mixed with the solution, and the reaction was carried out at 50°C for 3 hours. Subsequently, the temperature was raised to 80° C. and the reaction was continued for an additional 5 hours to obtain a phosphoric acid esterified epoxy resin. The epoxy resin has a solid content of 70%, a varnish acid value of 140, and a viscosity of 200 ps.
It was hot. After adding 7 parts of 25% ammonia water and stirring well, add 4403 parts of deionized water and adjust the pH of the system with 25% ammonia water while stirring.
The phosphoric acid esterified epoxy resin was adjusted to 6.0 and dispersed in water. Thereafter, emulsion polymerization was performed in the same manner as in Example 1 using the same composition and amount of mixed monomers to obtain an emulsion polymer with a pH of 5.0 and a solid content of 20%. Thereafter, the pH of the system was adjusted to 7.5 with 25% aqueous ammonia. To this emulsion polymer, an aqueous solution of ammonium chromate adjusted to 200 g/120 g was gradually added at room temperature while stirring. The mixed solution thus obtained is referred to as composition (E). Examples 6 to 10 A chromate-treated electrogalvanized steel material (width: 20 g/m ² on one side) measuring 150 mm long x 70 mm wide x 0.8 mm thick was degreased by a conventional method and dried to form a test plate. did. Each of the surface treatment compositions (A) to (E) of the present invention was coated on this steel material using a bar coater, and dried at 150° C. for 60 seconds to obtain a surface treated plate. Coating film thickness is approx.
It was 1.5μ. In order to examine the fingerprint resistance of these surface-treated boards, they were stamped with artificial perspiration and the stains were visually evaluated on a five-point scale. Rating: 5 (substantially no fingerprint marks are attached ←-→ Rating: 1 (fingerprint marks are extremely clear)) To check solvent resistance, a rubbing test was performed with absorbent cotton impregnated with 1.1.1 trichloroethane. ○...No change △...Slight elution ×...
Elution To check corrosion resistance, a salt spray test was conducted according to JIS-Z-2371, and the area where white rust occurred was evaluated using a 10-point scale. In other words, a score of 10 indicates no white rust, and a score of 9 indicates up to 10% white rust (the same criteria apply hereinafter). In order to check the paint base properties, after applying melamine alkyd resin paint (baked at 130℃ for 20 minutes, film thickness 20μ, pencil hardness H to 2H), we conducted a goblin test and a goblin Erichsen test to check the damage on the painted surface. was determined. *Round test: Make 11 vertical and horizontal cuts in the paint film at 1m/m intervals to create 100 rows, then apply sellotape to the marks and instantly peel them off. *Erichsen test with gongs As shown above, cut the goblets and extrude 7m/m using an Erichsen extruder, then apply sellotape and peel off instantly. The number of remaining Gobanales was evaluated using a 10-point scale (10 points indicate 100 remaining Gobanales). Example 11 A composition obtained by replacing ammonium chromate in composition (A) with ammonium dichromate was applied and tested in the same manner as in Example 6. Example 12 A phosphate-treated electrogalvanized steel material (width: 20 g/m ² on one side) measuring 150 mm long x 70 mm wide x 0.8 mm thick was degreased and dried in a conventional manner to prepare a test plate. This steel material was coated with the surface treatment composition (A) of the present invention using a bar coater, and dried at 150°C for 60 seconds to obtain a surface treated plate. The coating film thickness was approximately 1.5μ. The rest of the test was carried out in the same manner as in Example 6. Example 13 An untreated electrogalvanized steel material (length 150 x width 70 x plate thickness 0.8 mm) that has not been subjected to chromate treatment or phosphate treatment (fabric weight on one side 20 g/m ² ) was degreased and dried by a conventional method. This was used as a test board. Applying the surface treatment composition (A) of the present invention to this steel material using a bar coater,
Drying was performed at 150°C for 60 seconds to obtain a surface-treated board. The coating film thickness was approximately 1.5μ. The rest of the test was carried out in the same manner as in Example 6. Comparative Example 1 The method was the same as in Example 1, but the mixed ethylenically unsaturated monomer was replaced with a mixed solution consisting of 350 parts of n-butyl acrylate, 175 parts of ethyl methacrylate, and 175 parts of methacrylic acid, and a pH 3.5 solid solution was prepared. An emulsion polymer having a type content of 35% was obtained. After that, the system was washed with 25% ammonia water.
The pH was adjusted to 6.5. 200g/ of this emulsion polymer
Ammonium chromate aqueous solution adjusted to 210
was gradually added while stirring at room temperature. The mixed solution thus obtained is referred to as composition (F).
This comparative example is a case where the amount of methacrylic acid in the mixed monomers is above the range of the present invention (25%). Comparative Example 2 The same method as in Example 1 was used, but the mixed ethylenically unsaturated monomer was replaced with a mixture consisting of 350 parts of ethyl acrylate and 350 parts of ethyl methacrylate, and the pH was 4.0.
An emulsion polymer with a solids content of 35% was obtained. Thereafter, the pH of the system was adjusted to 7.5 with 25% ammonia water. When an aqueous solution of ammonium chromate 210 adjusted to 200 g/ml was gradually added to this emulsion polymer at room temperature while stirring, the liquid instantly turned into a gel. This comparative example is a case in which the mixed monomer does not contain an α/β-monoethylenically unsaturated carboxylic acid monomer. Comparative Example 3 3.5 parts of bisphenol A diglycidyl ether (epoxy equivalent 250) was dissolved in 1.5 parts of ethyl cellosolve in a beaker, 0.3 parts of orthophosphoric acid was further mixed with the solution, and the reaction was carried out at 50°C for 3 hours. Subsequently, the temperature was raised to 80°C, and the reaction was continued for an additional 5 hours to obtain a phosphoric acid esterified epoxy resin. The epoxy resin has a solid content of 70%, a varnish acid value of 140, and a viscosity of 200 ps.
It was hot. After adding 7 parts of 25% ammonia water and stirring well, add 1080 parts of deionized water and bring the pH of the system to 6.0 with further 25% ammonia water while stirring.
The phosphoric acid esterified epoxy resin was dispersed in water. After that, emulsion polymerization was carried out in the same manner as in Example 1, using the same composition and amount of mixed monomers.
After 2 hours of dropping the monomer, the system became milky white and the PH
5.0 An emulsion polymer with a solids content of 35% was obtained. then 25%
The pH of the system was adjusted to 7.5 with aqueous ammonia. To this emulsion polymer, an aqueous ammonium chromate solution adjusted to 200 g/210 was gradually added at room temperature while stirring. The mixed solution thus obtained is referred to as composition (G). In this comparative example, the ratio of modified epoxy resin and ethylenically unsaturated monomer was 1/99.
This is the case below. Comparative Example 4 840 parts of bisphenol A diglycidyl ether (epoxy equivalent 250) was dissolved in 360 parts of ethyl cellosolve in a beaker, 71.4 parts of orthophosphoric acid was further mixed with the solution, and the reaction was carried out at 50°C for 3 hours. Subsequently, the temperature was raised to 30°C, and the reaction was continued for an additional 5 hours to obtain a phosphoric acid esterified epoxy resin. The epoxy resin has a solid content of 70%, a varnish acid value of 140, and a viscosity of 200 ps.
It was hot. After adding 7 parts of 25% ammonia water and stirring well, 6323 parts of deionized water was added, and while stirring, the pH of the system was brought to 6.0 with 25% ammonia water.
The phosphoric acid esterified epoxy resin was dispersed in water. After that, emulsion polymerization was carried out in the same manner as in Example 1, using the same composition and amount of mixed monomers.
The system gelled during the polymerization. In this comparative example, the ratio of modified epoxy resin and ethylenically unsaturated monomer was
This is a case of 50/50 or more. Comparative Example 5 700 parts of deionized water was put into a flask equipped with a stirrer, a cooling tube, and a temperature control device, and the temperature was raised to 65° C. while stirring. Then, while maintaining the temperature at 65°C, an anionic surfactant (trade name "Levenol WZ" manufactured by Kao Atlas Co., Ltd., 25% Add 3 parts of solution), 273 parts of deionized water, monomer emulsion pre-emulsified in a homomixer, an aqueous solution of 3.5 parts of t-butyl hydroperoxide dissolved in 154 parts of deionized water, and 3.5 parts of Rongarit. Each aqueous solution in 154 parts of deionized water is added dropwise through a separate addition funnel over a period of 4 hours. After the dropwise addition, stirring and heating were continued for 2 hours to complete the reaction, and the solid content was reduced to PH5.0.
A 35% emulsion polymer was obtained. Thereafter, the pH of the system was adjusted to 7.5 with 25% aqueous ammonia. To this emulsion polymer, an aqueous ammonium chromate solution adjusted to 200 g/210 was gradually added at room temperature while stirring. The mixed solution thus obtained is referred to as composition (H). This comparative example is a case where the modified epoxy resin of the present invention was not used as an emulsifier. Comparative Examples 6 to 8 The compositions (F) to (H) were applied and tested in the same manner as in Example 6. Comparative Example 9 A solution obtained by removing the aqueous ammonium chromate solution from Composition A was applied and tested in the same manner as in Example 6. Comparative Example 10 A chromate-treated electrogalvanized steel material (width: 20 g/m ² on one side) measuring 150 mm long x 70 mm wide x 0.8 mm thick was degreased and dried in a conventional manner to form a test plate. Tested without applying anything. Comparative Example 11 A commercially available electrogalvanized plate treated with zinc phosphate was degreased and dried in a conventional manner to prepare a test plate, and the test plate was tested without coating anything thereon.

[Table] Table 1 shows that the film obtained by applying the composition obtained by the method of the present invention to the surface of zinc-plated steel has good fingerprint resistance, corrosion resistance, solvent resistance, and paint base properties. I understand that.

Claims (1)

[Claims] 1 P- in the phosphoric acid ester of an epoxy resin produced by esterifying at least a part of the terminal epoxy groups of the epoxy resin with a phosphorus-containing acid.
Using a water-dispersible or water-soluble modified epoxy resin obtained by neutralizing some or all of the OH groups with a base as an emulsifier, 1 to 20% by weight of α/β-monoethylenically unsaturated carboxylic acid monomer is added. An emulsion polymer obtained by emulsion polymerization of an ethylenically unsaturated monomer containing the following: wherein the ratio of the water-dispersible or water-soluble modified epoxy resin to the ethylenically unsaturated monomer is 1/99 by weight percentage. A composition for surface treatment of chromate-treated zinc-plated steel materials, which is based on an emulsion polymer in the range of ~50/50.