JPH09287079A - Resin chromating composition excellent in malodor characteristic and surface treated metallic plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin chromate composition and a resin chromate treated metallic plate free from the generation of putrefaction odor after aging in a chromate treating solution or after applying the chromate treating solution on the metallic plate, drying and aging. SOLUTION: The coating film of the resin chromating composition consisting essentially of (a) an organic high polymer emulsion prepared by dispersing an organic high polymer containing <=20wt.% (including zero) component, which forms a 3-7C lower monocarboxylic acid in a chromic acid aq. solution and/or a chromate treated coating film, in a water based medium, (b) a water soluble chromium compound and (c) a mineral acid is formed on the metallic plate with the coating weight of 5-300mg/m<2> expressed in terms of metal chromium.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a resin chromate treatment composition which does not generate a rotten odor during operation and has excellent bath stability, and does not generate a rotten odor from a product, and has corrosion resistance,
The present invention relates to a resin chromate-treated metal plate having excellent chromium insolubility, paint adhesion, alkali resistance, and appearance quality.

[0002]

2. Description of the Related Art Chromate treatment has been used for a long time as a simple rust preventive treatment for metal surfaces, and can be roughly classified into electrolytic chromate or reaction chromate containing trivalent chromium as a main component.
There is a coating chromate that contains hexavalent chromium and is dried without being washed with water after coating. In recent years, chromate treatment has been widely used for applications such as home appliances, building materials, and automobiles, and demands for various performances have been made by consumers. For example, uniformity of color tone, appearance quality such as fingerprint resistance, paint adhesion, flat plate corrosion resistance when barely used and corrosion resistance after processing, hardly soluble chromium against dew condensation or alkali degreasing, sliding property during processing, and the like are examples. Among these, there are those which are in principle inconsistent, such as poorly soluble chromium and corrosion resistance after working, and it is technically not easy to express all the performances in a well-balanced manner.

For example, in order to make chromium insoluble in a conventional chromate composed of chromic acid and an inorganic oxide such as silica, it is disclosed in JP-A-3-2156.
As partially described in Japanese Patent Publication No. 83, a method of heating a chromate-treated metal plate at a high temperature of 200 ° C. or higher is known, but it is not economical considering the cost of the drying equipment. Further, the corrosion resistance is rather inferior to that of the chromium-soluble inorganic chromate. On the other hand, there is also known a method in which corrosion resistance and chromium insolubility are both achieved by a two-step treatment in which a metal plate is subjected to an inorganic chromate treatment, dried, and then a resin is applied and dried, but there are also process restrictions and cost. There are problems such as high prices.

Further, as seen in JP-A-4-358082 and JP-A-5-287548, a water-soluble or water-dispersible resin such as polyacrylic acid or a reducing agent such as alcohol is added to a chromate treatment bath. There is also known a method of adding and reducing / fixing hexavalent chromium and crosslinking trivalent chromium in a resin. According to this method, chromium is insolubilized,
Moreover, although the corrosion resistance of the chromate film is improved due to the barrier effect of the resin, a large amount of reducing components are contained in the treatment bath, which causes gelation due to reduction of hexavalent chromium in the bath, resulting in poor bath stability.

Japanese Unexamined Patent Publication (Kokai) No. 5-230666 also has an example of a metal surface treatment composition which has both poor solubility in chromium and high corrosion resistance. This is a resin chromate composition consisting of a carboxylic acid of a specific composition, an organic polymer containing a hydroxyl group, and a water-soluble chromium compound. This composition can be stored for several days even at a temperature of 25 ° C and a relative humidity of 65%. Due to abnormalities such as gelation, sedimentation, separation, etc., it is difficult to withstand long-term continuous operation in a metal surface treatment line where the temperature of the treatment bath reaches 50 ° C.
Moreover, the obtained chromate-treated metal plate is inferior in secondary adhesion to the coating material.

JP-A-63-145785 discloses a composition comprising an acrylic polymer emulsion obtained by emulsion polymerization using a polyoxyethylene-polyoxypropylene block polymer emulsifier and a hexavalent chromium compound. It is disclosed. This composition is 40 ℃ due to the effect of emulsifier
However, it is stable for 3 weeks or more, but the corrosion resistance is poor because the emulsifier becomes a factor that hinders film formation, and the chromium elution amount is large.

In the so-called resin chromate treatment in which a resin is added to chromic acid, in addition to the problems shown in these known examples, a resin chromate film is formed in a chromate treatment bath and on a metal plate. After that, there is a problem of generating a rotten odor over time,
The present inventors have found out. The putrefactive odor is an unpleasant odor of a kind generated from ginkgo nuts of trees, cheese in the fermentation process, sewage of humans and animals, and the like. This phenomenon occurs remarkably when the metal plates are stored in a stack, for example, when stored in a coil state. The generation of rotten odor in a chromate treatment bath is a problem in the working environment at the manufacturing site, while the generation of rotten odor from a metal plate is a problem at the customer's end, which significantly impairs the commerciality of resin chromate-treated metal plates. Is.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a resin having excellent odor characteristics that does not generate a rotten odor after aging in a chromate treatment bath and after coating and drying the treatment liquid on a metal plate and aging. It is intended to provide a chromate composition and a resin chromate-treated metal plate. Furthermore, while satisfying the above characteristics, a resin chromate composition in which the treatment bath is stable for a long period of time, and appearance quality such as color tone uniformity, fingerprint resistance, paint adhesion, flat plate corrosion resistance when used naked and corrosion resistance after processing, condensation Another object of the present invention is to provide a resin chromate-treated metal plate excellent in properties such as poor solubility of chromium in alkali degreasing.

[0009]

The first aspect of the present invention is (a)
An organic polymer in which an organic polymer containing 20% by weight or less of a component that forms a lower monocarboxylic acid having 3 to 7 carbon atoms in an aqueous chromic acid solution and / or a chromate film is dispersed in an aqueous medium. A resin chromate composition containing a polymer emulsion and (b) a water-soluble chromium compound as main components. The organic polymer (a) is an ethylenically unsaturated compound, and it is preferable that the resin chromate composition further contains (c) a mineral acid.

Of the ethylenically unsaturated compounds, the component which does not form a monocarboxylic acid having 3 to 7 carbon atoms is synthesized from a primary alcohol having 1, 2 or 8 or more carbon atoms and containing a chain isomer. And / or ether synthesized from any secondary alcohol, ester or / and ether synthesized from any secondary alcohol, ester or / and ether synthesized from any tertiary alcohol, and carbon It is still more preferable that the component forming a lower carboxylic acid having a number of 3 to 7 is an ester or / and an ether synthesized from a primary alcohol containing a chain isomer having a carbon number of 3 to 7.

Further, among the above-mentioned ethylenically unsaturated compounds, it is more preferable that the component which does not form a monocarboxylic acid having 3 to 7 carbon atoms is acrylic acid ester and / or methacrylic acid ester. Furthermore, the ethylenically unsaturated carboxylic acid component is added to the ethylenically unsaturated compound in an amount of 10
More than 5% by weight, less than 30% by weight, 5% hydroxyl group-containing monomer component
It is still more preferable to contain less than wt%. When the drying plate temperature does not exceed 90 ° C, it is more preferable that the Tg of the whole organic polymer, that is, the Tgtotal value is from -40 ° C to 20 ° C. The second of the present invention is to coat a film of the composition on a metal plate in an amount of 5 to 300 m in terms of metal chromium.
The surface-treated metal plate is characterized in that it is formed by g / m ² .

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is described in detail below. The present inventors first conducted the following studies in order to clarify the cause of the rotten odor generated in the chromate treatment bath and from the chromate-treated metal plate. First, a resin chromate treatment bath using an acrylic resin containing butyl acrylate, which is generally used as an acrylate ester, as a main component is constructed, and after galvanizing the galvanized steel sheet with the treatment bath, the treated surfaces are treated with each other. The layers were overlapped and left at room temperature for 3 days. The treatment bath was left at room temperature for 1 week.

As a result, it was confirmed that a rotten odor was generated from both the treated steel sheet and the treatment bath. Therefore, when the odor components in the treated steel sheet and the treatment bath were analyzed, it was found that the cause of the rotten odor was butyric acid (C = 4). A similar experiment was conducted with another acrylic ester synthesized from an alcohol having 1 to 8 carbon atoms, that is, methyl acrylate (C = 1),
Ethyl acrylate (C = 2), propyl acrylate (C = 3), pentyl acrylate (C = 5), hexyl acrylate (C = 6), heptyl acrylate (C
= 7), a resin chromate using an acrylic resin containing 2-ethylhexyl acrylate (C = 8) as a main component was used, and a rotten odor was generated only for those having 3 to 7 carbon atoms. It was found to be due to the formation of the corresponding lower monocarboxylic acids, namely propionic acid (C = 3), valeric acid (C = 5), caproic acid (C = 6) and heptanoic acid (C = 7).

Next, when the reaction of formation of these rotten odors in the bath and in the film was analyzed, it was found that the odor generation mechanism was as follows in all cases. First, hydrolysis of an acrylic acid ester, which is a component copolymerized in an organic polymer, produces a primary alcohol having 3 to 7 carbon atoms, that is, propanol, butanol, pentanol, hexanol, and heptanol. These alcohols are then oxidized in the bath and in the coating by the chromic acid component to form lower monocarboxylic acids of the corresponding carbon number. These lower monocarboxylic acids generate a putrid odor.

Therefore, in the present invention, an organic polymer in which the total amount of components forming a lower monocarboxylic acid having 3 to 7 carbon atoms is 20% by weight or less is mixed with a water-soluble chromium compound to prepare a resin chromate composition. And When the total amount is zero, there is no rotten odor and it is most preferable, but when it is 10% by weight or less, almost no rotten odor is felt. On the other hand, if it exceeds 20% by weight, the rotten odor is not suppressed. Therefore, carbon number 3-7
In the present invention, the total amount of the lower monocarboxylic acid-forming components of 20% by weight or less means that including zero. The type of organic polymer is not particularly limited, but an ethylenically unsaturated compound is preferable. The method for dispersing the organic polymer emulsion in the aqueous medium is not particularly limited, either, an emulsion composed of only a hydrophobic component and dispersed by an emulsifier, or a dispersion of a hydrophobic component and a hydrophilic component dispersed by an emulsifier. Emulsion,
It may be any of emulsions composed of a hydrophobic component and a hydrophilic component and dispersed without using an emulsifier.

Next, the inventors of the present invention have made extensive studies to obtain a resin chromate composition having excellent stability that can withstand continuous operation in a metal surface treatment line. As a result, it was found effective to add mineral acids such as phosphoric acid, sulfuric acid, nitric acid and hydrochloric acid to the chromate bath. When the organic polymer is an ethylenically unsaturated compound, a hydroxyl group-containing component and an ethylenically unsaturated carboxylic acid component are contained as hydrophilic components, and the former is less than 5% by weight (including zero),
It was found that by setting the total of both to more than 10% by weight, a bath life of 1 month or more can be obtained even at 50 ° C. Next, when the poorly soluble chromium of the resin chromate-treated metal plate was investigated, the chromium elution amount decreased as the amount of the hydroxyl group-containing component in the organic polymer increased, and the hydroxyl group-containing component was less than 5% by weight (including zero). In the case of (4), it was found that the elution of chromium is sufficiently suppressed by making the ethylenically unsaturated carboxylic acid component less than 30% by weight.

Next, a study was conducted to improve the adhesion of the resin chromate-treated metal plate to the coating material, particularly the secondary adhesion (wet durability). As a result, it was confirmed that the ethylenically unsaturated carboxylic acid component in the organic polymer It was found that if the amount exceeds 10% by weight, good adhesion can be obtained. On the other hand, if it exceeds 30% by weight, corrosion resistance and alkali resistance are deteriorated. To further balance paint secondary adhesion, corrosion resistance, and alkali resistance, use an ethylenically unsaturated carboxylic acid component of 12% by weight.
As described above, it is more preferable to set it to 18% by weight or less.

The above resin components will be described in more detail below. Examples of the organic polymer usable in the present invention include acrylic acid and / or methacrylic acid ester, carboxylic acid vinyl ester, vinyl ether,
Examples include ethylenically unsaturated compounds such as styrene, acrylamide, acrylonitrile and vinyl halide, and epoxies, urethanes and polyesters. Among these, for (meth) acrylic acid ester, carboxylic acid vinyl ester, and vinyl ether, the alcohol, which is a raw material for their synthesis, is liberated in the chromic acid bath by hydrolysis, oxidative decomposition, etc., and further oxidized to lower carboxylic acid. Therefore, the following should be used because it may cause a rotten smell.

That is, an ester or / and ether synthesized from a primary alcohol having a carbon number of 1, 2 or 8 and containing chain isomers, an ester or / and an ether synthesized from any secondary alcohol, One or more of the esters and / or ethers synthesized from any tertiary alcohol. The chain isomer is a general term for isomers resulting from the difference in the structure of the carbon chain, and 2-methyl-1-propanol for 1-butanol, 3-methyl-1-butanol and 2,2-dimethyl- for 1-pentanol. 1-Propanol is an example. It should be noted that secondary alcohols and tertiary alcohols can be used without limitation in the number of carbon atoms, since carboxylic acids are hardly generated even when they are oxidized in chromic acid.

Specific examples of the alkyl group / allyl group of the primary alcohol include methyl, ethyl, 2-ethylhexyl, lauryl, stearyl, octyl, isooctyl,
Nonyl, isononyl, dodecyl, dimethylaminoethyl, diethylaminoethyl, tert-butylaminoethyl, benzyl, etc., and the alkyl group / allyl group of the secondary alcohol includes isopropyl, sec-butyl, cyclohexyl, cyclopentenyl, phenyl, etc. Examples of the alkyl group / allyl group of the primary alcohol include tert-butyl and the like.

On the other hand, a component which causes a bad smell and cannot be contained in the organic polymer in an amount of more than 20% by weight means a primary alcohol having a carbon number of 3 to 7 and a chain isomer. , I.e., n-propanol, n-butanol,
An ester or / and an ether formed from a linear primary alcohol such as n-pentanol, n-hexanol, or n-heptanol and a branched primary alcohol such as isobutanol or isopentanol.

Specific examples of the ethylenically unsaturated compound components corresponding to the above are shown in Table 1. Organic polymers are emulsions consisting of only hydrophobic components and dispersed with an emulsifier, emulsions consisting of hydrophobic and hydrophilic components and dispersed with an emulsifier, and dispersions consisting of hydrophobic and hydrophilic components without using an emulsifier. Any of the above emulsions may be used. Examples of the ethylenically unsaturated carboxylic acid component of the organic polymer include acrylic acid, methacrylic acid, and ethylenically unsaturated monocarboxylic acids such as crotonic acid, itaconic acid, maleic acid, and ethylenically unsaturated dicarboxylic acids such as fumaric acid. And one or two selected from alkali metal salts, ammonium salts, organic amine salts of those carboxylic acids.
One or more kinds can be used, but acrylic acid and / or methacrylic acid are preferable.

As the hydroxyl group-containing component in the organic polymer,
2-Hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, 3-hydroxybutyl (meth) acrylate, 2,2-bis (hydroxymethyl) acrylate
Ethyl, (meth) acrylic acid 2,3-dihydroxypropyl, (meth) acrylic acid-3-chloro-2-hydroxypropyl, and other (meth) acrylic acid hydroxyesters, allyl alcohols, and N-methylolacrylamide, N -A monomer having a reducing hydroxyl group of alcohol amides such as butoxymethylol (meth) acrylamide, and glycidyl (meth) acrylate, allyl glycidyl ether, β-methylglycidyl (meth) which can be expected to have the same reactivity as the hydroxyl group in an acidic solution. ) Acrylate, a monomer having a glycidyl group such as 3,4-epoxycyclohexylmethyl (meth) acrylate,
One kind or two or more kinds selected from aldehyde group-containing monomers such as acrolein can be used.
Particularly preferred is 2-hydroxyethyl (meth) acrylate, and / or glycidyl (meth) acrylate. In addition, the above (meta) represents the thing which does not have meta or / and meta. The solid content concentration of the organic polymer in the aqueous medium can be appropriately selected within a range that does not hinder stable dispersion, but is usually about 5 to 50% by weight.

[0024]

[Table 1]

Further, when the present inventors intend to form a film at a plate temperature of less than 90 ° C. in the drying step of the chromate treatment line, the T of the organic polymer obtained by the following formula is obtained.
It has been found that the gtotal value needs to be 20 ° C. or lower. If it is higher than this, whitening or the like occurs due to defective film formation, and sufficient corrosion resistance cannot be obtained. On the other hand, Tgtot
If the al value is less than −40 ° C., the chromate film becomes tacky even after drying, and fingerprint marks may remain, or sticking (blocking) may occur when the plates are stacked. It is more preferable to set the Tg total value to −20 ° C. or higher and 10 ° C. or lower in order to achieve a higher degree of film-forming property, fingerprint resistance, and blocking resistance.

[0026]

[Equation 2]

Tg total is Tg of the whole organic polymer.
(Glass transition temperature), Tgi is Tg of i component, and Φi is i
The volume fraction of the components (substantially the same as the weight fraction), n represents the total number of monomer components. When drying at a high temperature of 90 ° C. or higher is possible, it is not necessary to limit the Tg total value of the organic polymer within the above range.

Next, as the water-soluble chromium compound in the present invention, chromic anhydride, potassium (di) chromate,
Chromic acid such as sodium (di) chromate, ammonium (di) chromate, barium chromate, and strontium chromate, chromate and dichromate, and reduced chromic acid obtained by partially reducing these with starch, alcohol, or the like. Chromates can be used. Chromic acid (salt)
The reduction rate is not particularly limited, but it is preferable to select it according to the following criteria when there is a performance to which special importance is attached. That is, when importance is placed on the poor chromium insolubility, it is preferable to select from the range of the reduction ratio of 20 to 100%, while when importance is placed on the corrosion resistance of the processed portion, it is preferable to select from the range of the reduction ratio of 0 to 70%. .

The amount ratio of the water-soluble chromium compound and the organic polymer emulsion in the resin chromate composition can be appropriately selected, but usually the weight of the water-soluble chromium compound in terms of CrO ₃ and the solid content of the organic polymer emulsion. By weight ratio of 1:
It is about 1 to 1:20. The thickness of the resin chromate can be selected as appropriate, but is usually about 0.1 to 5 μm. Bath concentration of chromic acid in this case, coating methods, chromic acid / resin ratio may vary depending on the thickness desired, within the scope of 5 to 100 g / l at approximately CrO ₃ terms. The concentration of the organic polymer in the bath also varies in the same manner as described above, but is generally about 10 to 300 g / l in terms of solid content.

As the mineral acid added to the resin chromate, phosphoric acid, sulfuric acid, hydrochloric acid, nitric acid and the like can be used, but phosphoric acid is preferable from the viewpoint of corrosion resistance and bath stability.
The amount added is not particularly limited, but in order to optimize the bath stability, it is advantageous to add 1.2 times or more the chromic acid concentration in the bath (calculated as CrO ₃ ) in terms of H ₃ PO _4. On the other hand, in order not to impair the corrosion resistance, H ₃ PO ₄
It is advantageous that the concentration is 4 times or less of the chromic acid concentration in the bath (calculated as CrO ₃ ). In addition to these, an inorganic sol such as silica, alumina, titania and zirconia, a fluoride and the like can be contained in the resin chromate composition and the coating, if necessary. In particular, the addition of colloidal silica has the effect of improving corrosion resistance and paint adhesion.

The amount of the resin chromate composition deposited on the metal surface is preferably 5 to 300 mg / m ² in terms of metal chromium. If it is less than 5 mg / m ² , the corrosion resistance is insufficient, and if it exceeds 300 mg / m ² , it is not economical. As the chromate treatment method for the metal surface, a usual method such as coating with a roll coater, coating with a ringer roll, coating with dipping and air knife squeezing, coating with a bar coater, coating with a spray, or brush coating can be used. Further, the drying after coating may be a usual method.

The metal plate to which the present invention can be applied is a galvanized steel plate, an alloy plated steel plate of zinc and a metal such as nickel, iron, aluminum, chromium, titanium, magnesium, manganese, an aluminum or aluminum alloy plated steel plate, Lead or a lead alloy plated steel sheet, tin or a tin alloy plated steel sheet, and further a plated steel sheet in which a small amount of a third metal or / and an inorganic substance such as silica, alumina, zirconia or titania is dispersed in these plated layers, a cold rolled steel sheet, Examples include hot rolled steel plate, silicon steel plate, zinc or zinc alloy plate, aluminum or aluminum alloy plate, magnesium or magnesium alloy plate, titanium or titanium alloy plate, and stainless plate.

[0033]

Next, the present invention will be described by way of examples. Example 1 (1) Synthesis of organic polymer Thirteen kinds of organic polymers composed of main components as shown in Tables 1 to 13 were synthesized. When multiple components were labeled, the synthesis was performed using equal amounts of each. For 1-9, they were dispersed in the aqueous medium without emulsifier by copolymerizing with acrylic acid (20% by weight) by the following procedure. That is, 500 parts of deionized water (parts by weight; the same applies hereinafter) was placed in a reaction vessel and the liquid temperature was raised to 60 ° C., and 300 parts of a mixture of monomers and acrylic acid shown in Table 2 and 3 parts of ammonium persulfate ( (Dissolved in 97 parts of deionized water) and 3 parts of acidic sodium sulfite (dissolved in 97 parts of deionized water) were added dropwise in parallel while stirring so as to finish in 2 hours, and subsequently stirred at 60 ° C. for 3 hours. While carrying out a polymerization reaction, an emulsion was synthesized.

On the other hand, about 10-13, it was synthesized by the following procedure using an emulsifier. An aqueous solution prepared by dissolving 6 parts of sodium dodecylbenzenesulfonate as an emulsifier in 494 parts of deionized water (weight part; the same applies hereinafter) was added, and the liquid temperature was 60 ° C.
To a mixture of the monomers shown in Table 2
Parts, 3 parts of ammonium persulfate (dissolved in 97 parts of deionized water), and 3 parts of acidic sodium sulfite (dissolved in 97 parts of deionized water) were added in parallel at the same time with stirring so as to be completed in 2 hours. Then, a polymerization reaction was carried out while stirring at 60 ° C. for 3 hours to synthesize an emulsion. 14-3
1 uses the same organic polymer as 1, 2 and 6, but the metal plate coated with the resin chromate composition is different.

(2) Resin chromate composition Chromic anhydride is 15 g / l in terms of CrO ₃ and phosphoric acid is H
A resin chromate composition containing 18 g / l in terms of ₃ PO ₄ and 75 g / l in terms of solid content of the organic polymer emulsion shown in Table 2 was prepared. (3) Types of metal plates The following metal plates were used for the chromate treatment. The size was 180 mm × 300 mm. EG: Electrogalvanized steel sheet GI: Hot-dip galvanized steel sheet SZ: Hot-dip aluminum alloy plated steel sheet (AL / Z
n = 5/95) CR: Cold rolled steel plate AL: Aluminum plate TI: Titanium plate SI: Silicon steel plate

(4) Chromate treatment method After the surface of a metal plate is cleaned, it is immersed in a resin chromate bath, and the adhesion amount is 40 mg in terms of metal Cr by an air knife.
/ M ² was treated on one side and dried at an ultimate plate temperature of 60 ° C. The film thickness was about 0.5 μm. (5) Sensory test for rotten odor of metal plate 20 pieces of the metal plate after chromate treatment were stacked so that the treated surfaces were in contact with each other, and the four corners were fixed with a vise and left at room temperature for 1 week. After this, remove the vise,
Immediately after the treatment surface was opened, the presence or absence of putrefaction odor was examined by 10 test subjects, and the judgment was made according to the following criteria. ◯: Less than 2 people felt putrid odor △: 2 or more and less than 5 people felt putrid odor ×: 5 or more people felt putrid odor

(6) Quantification of odorous components in resin chromate composition and sensory test for rotten odor 100 cc of resin chromate liquid was taken at 50 ° C.
After storage for a week, the components in the bath were quantitatively analyzed by a gas chromatograph / mass spectrometer (GC / MS). In addition, the presence or absence of rotting odor was examined by 10 test subjects. The criterion is (5)
Is the same as The results are shown in Tables 2 and 3. Table 3 shows the results of analyzing the amounts of lower carboxylic acids produced in the baths of Nos. 1 to 13 in Table 2. In any of the metal plates, when the organic polymer contains a monomer component synthesized from a primary alcohol having 3 to 7 carbon atoms, a rotten odor is generated. Also,
For these, the formation of the corresponding lower carboxylic acid was recognized even in the chromate bath, and the bath had a rancid odor.

[0038]

[Table 2]

[0039]

[Table 3]

Example 2 (1) Synthesis of organic polymer An organic polymer composed of the components shown in Table 4 was synthesized. Here, what is shown as a main component is a component that did not generate a putrid odor in Example 1. Also,
In addition to these, the components generating a rotten odor are added in the amounts shown in the table. It was dispersed in an aqueous medium without emulsifier by copolymerizing it with 20% by weight of methacrylic acid. The synthetic method is the same as the resin numbers 1 to 9 (Table 2) of Example 1.

(2) Resin chromate composition Partially reduced chromic acid (reduction ratio 20%) was added to CrO._ThreeConverted to 3
0g / l, phosphoric acid H _ThreePO_Four55g / l in conversion, Table 4
100 g of the organic polymer emulsion shown in Fig.
A bath containing the resin chromate composition containing 1 / l was prepared. (3) Kind of metal plate EG: (electrogalvanized metal plate as a metal plate for chromate treatment
A steel plate) was used. (4) Chromate treatment method Coating was performed with a bar coater and drying was performed at a plate temperature of 120 ° C. Attached
The amount deposited is 100 mg / m in terms of metal Cr.^Two , The film thickness is about 1.
It was 5 μm.

(5) Sensory test of putrid odor of metal plate Tested and judged in the same manner as in Example 1. (6) Sensory test for rotten odor of chromate bath A similar test to the sensory test of Example 1 was carried out to make a determination.
The results are shown in Table 4. It can be seen that the spoilage odor is suppressed in both the metal plate and the chromate bath when the content of the component in which the oxidation product generates a spoilage odor in the organic polymer is 20% by weight or less.

[0043]

[Table 4]

Example 3 (1) Synthesis of Organic Polymer The organic polymers having the compositions shown in Tables 5 and 6 were used without using an emulsifier.
Polymerized. The synthetic method was the same as Example 1 except that the emulsifier was not used.
(Table 2, 1 to 9). However, hydrophilic
Acrylic acid or methacrylic acid
Was. (2) Resin chromate composition Partially reduced chromic acid (reduction rate 55%)_Three2 in conversion
0g / l, phosphoric acid H _ThreePO_Four45g / l in conversion, table
The organic polymer emulsions shown in 5 and 6 are converted into solid content of 8
0 g / l, and colloidal silica SiO_TwoConverted to 3
A resin chromate composition containing 0 g / l was bathed.

(3) Kind of Metal Plate EG (electrogalvanized steel plate) was used as a metal plate for chromate treatment. (4) Chromate treatment method After immersing a metal plate in a resin chromate bath, one side treatment was performed with an air knife so that the adhesion amount was 50 mg / m ^{2 in} terms of metal Cr, and the plate was dried at a plate temperature of 80 ° C. Thickness is about 0.7 μm
Met.

(5) Performance Evaluation Method Performance evaluation was performed on the following items. 1) Odor of metal plate: tested and judged in the same manner as in Example 1. 2) Bath stability: The resin chromate bath was put in a dryer at 50 ° C., and the number of days until abnormalities such as gelation, sedimentation and separation occurred was recorded. 3) Flat plate corrosion resistance: The area ratio of rust generated after spraying 5% salt water at 35 ° C. on the sample was examined. The spraying time is 8
The white rust occurrence area rate was measured by day. ◎ No rust occurrence 〇 Rust occurrence rate less than 5% △ Rust occurrence rate 5% or more, less than 20% × Rust occurrence rate 20% or more

4) Corrosion resistance of processed part: height 7 at the center of sample
mm of Erichsen processing was performed, and a salt spray test was performed in the same manner as 3), and then the rust generation area ratio of the processed portion was examined. In addition,
The spraying time was 4 days, and the white rust generation area ratio of the processed part was measured. ◎ No rust occurrence 〇 Rust occurrence rate less than 5% △ Rust occurrence rate 5% or more, less than 20% × Rust occurrence rate 20% or more

5) Chromium elution: The sample was placed in boiling water for 3 times.
Soaking for 0 minutes, the rate of change in the amount of chromium deposited before and after that (ΔC
(r = amount of reduced chromium / initial amount of deposited chromium) was measured. ◎ ΔCr <5% ○ 5% ≦ ΔCr <10% Δ 10% ≦ ΔCr <20% × 20% ≦ ΔCr

6) Secondary adhesion of coating material: A melamine alkyd coating material was applied to a sample in an amount of 20 μm, dried, and then immersed in boiling water for 30 minutes. Immediately, the peeled area ratio of the coating film was examined by a cross-cut peeling test (1 mm cross-cut 10 × 10, tape peeling). When the peeling test is performed without immersion in boiling water, paint adhesion (primary adhesion) is obtained regardless of which resin is used.
Was good and was at the ◎ level. ◎ Peeling rate <5% 〇 5% ≦ Peeling rate <10% △ 10% ≦ Peeling rate <20% × 20% ≦ Peeling rate

7) Alkali resistance: The rate of change in the amount of chromium deposited (ΔCr = amount of reduced chromium / initial amount of chromium deposited) was measured before and after spraying the sample with an alkaline degreasing solution of pH 10 for 3 minutes. ◎ ΔCr <5% ○ 5% ≦ ΔCr <10% Δ 10% ≦ ΔCr <20% × 20% ≦ ΔCr

8) Color tone: The yellowness YI of the sample was measured. The smaller the YI, the more uniform the white appearance. ◎ YI <-1 〇 -1 ≦ YI <1 Δ 1 ≦ YI <5 × 5 ≦ YI

9) Fingerprint resistance: A real fingerprint is pressed on the sample,
The conspicuousness was visually evaluated. ◎ No fingerprint traces can be discerned. 〇 Fingerprint traces are faint. △ Fingerprint traces can be easily identified. B. Table 7 shows the result in which fingerprint traces are noticeable even at a long distance. As is apparent from the table, the product of the present invention has no odor problem and is excellent in any of bath stability, flat plate corrosion resistance, processed part corrosion resistance, paint adhesion, alkali resistance, color tone and fingerprint resistance.

[0053]

[Table 5]

[0054]

[Table 6]

[0055]

[Table 7]

Example 4 (1) Synthesis of Organic Polymer Organic polymerization having the composition shown in Tables 5 and 6 in the same manner as in Example 3
The body was polymerized without emulsifier. (2) Resin chromate composition Partially reduced chromic acid (reduction rate 40%) is added to CrO._Three5 in conversion
0g / l, phosphoric acid H _ThreePO_Four90g / l in conversion, table
The organic polymer emulsions shown in 5 and 6 are 1 in terms of solid content.
20 g / l, and colloidal silica SiO_TwoIn conversion
A bath containing a resin chromate composition containing 50 g / l was prepared.

(3) Kinds of Metal Plates The following metal plates were used for the chromate treatment. GI: hot-dip galvanized steel sheet GA: hot-dip galvanized steel sheet (Fe / Zn = 15 /
85) SZ: Hot-dip zinc aluminum alloy plated steel sheet (AL / Z
n = 5/95)

(4) Chromate treatment method With a Ringer roll, the adhesion amount was 65 mg in terms of metal Cr.
/ M ² and then dried at a plate temperature of 80 ° C. The film thickness was about 0.5 μm. (5) Performance Evaluation Method Evaluation was performed in the same manner as in Example 3. The results are shown in Tables 8 and 9. As is clear from the table, the present invention shows excellent performance when applied to any metal plate and has no odor problem.

[0059]

[Table 8]

[0060]

[Table 9]

Example 5 (1) Kind of organic polymer Selected from Table 5 and Table 6 and used. (2) Resin chromate composition Partially reduced chromic acid (reduction rate 70%) is added to CrO._Three2 in conversion
0g / l, phosphoric acid H _ThreePO_Four50g / l in conversion, organic
Contains 140g / l of polymer emulsion in terms of solid content
A bath containing the resin chromate composition was prepared. (3) Types of metal plates EG, GI, G are used as metal plates for chromate treatment.
A and SZ were used.

(4) Chromate treatment method After immersing a metal plate in a resin chromate bath, one-side treatment is performed with an air knife so that the adhesion amount becomes 100 to 300 mg / m ^{2 in} terms of metal Cr, and the plate is dried at a plate temperature of 60 to 120 ° C. did.
The film thickness was about 1.7 to 5 μm. (5) Performance Evaluation Method Evaluation was performed in the same manner as in Example 3. The results are shown in Table 10. In any of the metal plates, when dried at a plate temperature of less than 90 ° C., the Tg and Tg total of the entire organic polymer are 20.
It is necessary to be less than or equal to ° C. On the other hand, the drying plate temperature is 90
This does not apply if the temperature exceeds ℃.

[0063]

[Table 10]

Example 6 (1) Kind of organic polymer Selected from Tables 5 and 6 and used. (2) Resin chromate composition Partially reduced chromic acid (reduction rate 30%) is added to CrO._Three1 in conversion
0g / l, phosphoric acid H _ThreePO_Four30g / l in conversion, organic
200 g / l of polymer emulsion in terms of solid content,
Idal silica is SiO_TwoResin containing 20g / l in conversion
The chromate composition was bathed. (3) Types of metal plates EG, GI, G as alloy plates for chromate treatment
A and SZ were used.

(4) Chromate treatment method The amount of adhesion is 3 to 30 in terms of metallic Cr by a roll coater.
It was treated so as to have a concentration of mg / m ² and dried at a plate temperature of 150 ° C. The film thickness was about 0.1 to 1.3 μm. (5) Performance Evaluation Method Evaluation was performed in the same manner as in Example 3. The results are shown in Table 11. It can be seen that in any metal plate, excellent performance is exhibited when the Cr deposition amount is 5 mg / m ² or more.

[0066]

[Table 11]

[0067]

EFFECTS OF THE INVENTION According to the present invention, after aging in a chromate treatment bath and after coating and drying a metal plate with the treatment bath and aging, decomposition of the resin component by a chromic acid compound
It does not generate a rotten odor derived from oxidation, and it has high stability in chromate treatment baths, which were difficult to achieve in the prior art, and high chromium elution and corrosion resistance of treated metal plates. Satisfaction level, paint adhesion,
It is possible to provide a resin chromate-treated metal plate having excellent alkali resistance, fingerprint resistance, and color tone uniformity.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shin Yamazaki 3-35-1, Ida, Nakahara-ku, Kawasaki-shi, Kanagawa Nippon Steel Co., Ltd. Technical Development Division (72) Teruaki Izaki, Tobata-ku, Kitakyushu, Fukuoka 1-1 Hibatacho Inside Nippon Steel Co., Ltd. Yawata Works (72) Inventor Kotaka Hayashi 1 Fuji Town, Hirohata-ku, Himeji City, Hyogo Prefecture Shin-Nippon Steel Co., Ltd. Hirohata Works (72) Inventor Shinichi Suzuki 5-3 Tokai-cho, Tokai-shi, Aichi Nippon Steel Co., Ltd. Inside the Nippon Steel Co., Ltd. (72) Inventor Yujiro Miyauchi 1 Kimitsu, Kimitsu-shi, Chiba Inside Nippon Steel Co., Ltd. (72) Inventor Kengo Yoshida 20-1 Shintomi, Futtsu-shi, Chiba Nippon Steel Co., Ltd.Technology Development Division (72) Inventor Chizo Takahashi 3-10-10 Kaneokahigashi-cho, Okayama-shi, Okayama (72) Inventor small Toshio Shima Okayama, Okayama Prefecture Kanaokahigashi-cho 3-chome No. 11

Claims (8)

[Claims] 1. An organic polymer having a content of 20% by weight or less in a component (a) which forms a lower monocarboxylic acid having 3 to 7 carbon atoms in an aqueous chromic acid solution and / or a chromate film. A resin chromate composition comprising an organic polymer emulsion dispersed in an aqueous medium and (b) a water-soluble chromium compound as main components and having excellent odor characteristics. 2. The resin chromate composition having excellent odor characteristics according to claim 1, wherein the organic polymer as the component (a) is an ethylenically unsaturated compound and further contains (c) a mineral acid. Stuff. 3. The component which does not form a monocarboxylic acid having 3 to 7 carbon atoms in the ethylenically unsaturated compound as the component (a) has a carbon number of 1, 2 or 8 and contains a chain isomer. One or more of ester or / and ether synthesized from primary alcohol, ester or / and ether synthesized from any secondary alcohol, ester or / and ether synthesized from any tertiary alcohol And a component for producing a lower carboxylic acid having 3 to 7 carbon atoms is an ester or / and an ether synthesized from a primary alcohol containing a chain isomer having 3 to 7 carbon atoms. Claim 2
A resin chromate composition having excellent odor characteristics described. 4. The component (a) which does not form a monocarboxylic acid having 3 to 7 carbon atoms in the ethylenically unsaturated compound is an acrylic acid ester and / or a methacrylic acid ester. A resin chromate composition having excellent odor characteristics according to claim 3. 5. The ethylenically unsaturated compound as the component (a) contains the ethylenically unsaturated carboxylic acid component in an amount of more than 10% by weight and 30% or less.
The resin chromate composition having excellent odor characteristics according to claim 3 or 4, which contains less than 5% by weight and less than 5% by weight of a hydroxyl group-containing monomer component. 6. In the ethylenically unsaturated compound as the component (a), the Tg total value given by the following formula is −40.
6. The temperature is not less than 20 ° C and not more than 20 ° C.
A resin chromate composition having excellent odor characteristics described. [Equation 1] Tg total represents Tg (glass transition temperature) of the entire organic polymer, Tgi represents Tg of the i component, Φi represents volume fraction of the i component (substantially the same as weight fraction), and n represents the total number of monomer components. 7. A coating of the resin chromate composition according to claim 1 on a metal plate in an amount of 5 to 300 in terms of metal chromium.
A surface-treated metal plate characterized by being formed in mg / m ² . 8. The resin chromate composition according to claim 6 is applied onto a metal plate and dried at a plate temperature of less than 90 ° C. to form a film of 5 to 300 mg / m ^{2 in} terms of metal chromium. Surface-treated metal plate characterized by.