JPS6383172A - Weldable rust-inhibiting lubricating film-forming composition and production of surface-treated steel sheet using the same - Google Patents

Abstract

PURPOSE:To provide the title compsn. which allows press working or welding to be conducted without applying any press oil and gives surface-treated steel sheets which can be coated without carrying out any degreasing, by blending a resin compsn. consisting of an org. resin and a curing agent component with an electrically conductive material, a Cr compd. and a lubricating material. CONSTITUTION:100pts.wt. resin compsn. consisting of 60-95pts.wt. org. resin having a functional group such as an OH, COOH or epoxy group selected from the group consisting of an epoxy resin, a polyester resin and an acrylic resin and 40-5pts.wt. curing agent component such as amino resin or a polyisocyanate is blended with 5-200pts.wt. electrically conductive material such as iron phosphide, Ni powder, graphite, etc., 0.2-50pts.wt. lubricating material such as PE wax, MoS2, etc., 1-40pts.wt. in total of a rust inhibitor composed of a chromium compd. (e.g., strontium chromate), a rust-preventing pigment (e.g., zinc phosphate) and silica and optionally 5-30pts.wt. TiO2.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a weldable rust-preventing, lubricating coating-forming composition and a method for producing a surface-treated steel sheet using the same.

[Prior Art] Conventionally, in the metal painting field, such as home appliance manufacturers, building material manufacturers, and steel furniture manufacturers, product painting has generally been done by
The process consists of 6 steps: applying press oil to the steel plate → pressing process → welding → greasing → surface treatment → painting.

[Problems to be solved by the invention] However, the conventional painting method involves 6 steps, which is unsatisfactory in terms of labor saving and productivity, and also requires pollution countermeasures such as wastewater treatment, which increases costs. ing. For this reason, in the metal coating field, there is a strong demand for a surface-treated steel sheet coated with a brimer composition that has the functions of lubricity, weldability, and suitability for top coating.

[Means for Solving the Problems] As a result of repeated research by the present inventors in order to obtain a brimer composition and a surface-treated steel sheet that can solve the problems in the conventional painting process described above and save labor. , a composition formed by blending a conductive substance, a chromium compound, and a lubricating substance with a resin composition having an epoxy resin, a polyester resin, and an acrylic resin as a base resin can be welded and form a rust-preventing and lubricating coating. This discovery led to the completion of the present invention.

Thus, according to the present invention, a conductive substance, a chromium compound, and a lubricating substance are added to a resin composition consisting of an organic resin selected from epoxy resins, polyester resins, and acrylic resins and an amino resin or polyisocyanate as a curing agent component. A weldable, rust-preventing, lubricating coating-forming composition characterized by comprising: an organic resin selected from epoxy resins, polyester resins, and acrylic resins; and an amino resin or polyisocyanate as a curing agent component. A rust-preventing, lubricating, coating-forming composition made by blending a conductive substance, a chromium compound, and a lubricating substance with a resin composition is applied to the surface of a steel plate that has been previously phosphate-treated or chromate-treated. A method of manufacturing a surface-treated steel sheet is provided.

The present invention will be explained in detail below.

The organic resin used in the present invention is selected from epoxy resins, polyester resins, and acrylic resins having functional groups (e.g., hydroxyl groups, carboxyl groups, epoxy groups, etc.) that are reactive with amino resins or polyisocyanates that are curing agent components. be dissolved in an organic solvent, or
Alternatively, a functional group (hydroxyl group, carboxyl group, amino group, etc.) can be introduced into the resin skeleton, and the resin can be neutralized with an acid or alkali to be water-solubilized or water-dispersed for use.

Epoxy resins include straight epoxy resins such as epichlorohydrin type and glycidyl ether type, fatty acid modified epoxy resins, polybasic acid modified epoxy resins, acrylic resin modified epoxy resins, alkyd (or polyester) modified epoxy resins, and polybutadiene modified epoxy resins. , phenol-modified epoxy resin, amino- or polyamino-modified epoxy resin, urethane-modified epoxy resin, etc. are used.

As the polyester resin, generally known resins including alkyd resins can be used, which can be obtained by ordinary synthesis methods.

Examples include oil-modified alkyd resins, rosin-modified alkyd resins, phenol-modified alkyd resins, styrenated alkyd resins, silicone-modified alkyd resins, acrylic-modified alkyd resins, and oil-free alkyd resins (polyester resins).

In addition, acrylic resin can be produced by solution polymerization, emulsion polymerization, or suspension polymerization using ordinary unsaturated ethylenic monomers.
Resins synthesized by the A polymerization method etc., which contain hard monomers such as methacrylate monomers, acrylonitrile, styrene, acrylic ugliness, acrylamide, and vinyltoluene as essential components, and further improve the hardness and flexibility of the resin. The desired resin can be obtained by appropriately blending other unsaturated vinyl monomers for the purpose of imparting properties and crosslinking properties.

This resin may also be modified with other alkyd resins, epoxy resins, phenolic resins, etc.

Examples of the amino resin used as the curing agent component of the resin described above include conventionally known melamine resins, benzoguanamine resins, urea-formaldehyde resins, etc., and these may be modified with alcohol such as butyl alcohol. .

The polyisocyanate is preferably blocked, such as toluidine diisocyanate (TDI), 4,4'-diphenylmethane diisocyanate (MDI), and xylene diisocyanate (XDI).
, hexamethylene diisocyanate (HMDI), inphorone diisocyanate (IPDI), etc. with phenol,
Examples include those blocked with malonic acid diethyl ester, ethyl acetoacetate, acetylacetone, cresol, and oxime.

What is the blending ratio of the above organic resin and curing agent component?

Solid content weight ratio 60/40 to 9515, preferably 75
The range is from /25 to 90/10.

Next, the conductive substances to be blended into the resin composition comprising the above-mentioned organic resin and curing agent components include, for example, zinc, aluminum, iron, cobalt, nickel, manganese, chromium, molybdenum, tungsten, copper, lead, and tin. metal powders and their alloy powders, conductive carbon, graphite powder, iron phosphide powder, aluminum doped zinc oxide powder, tin oxide
Examples include semiconductor oxides such as titanium oxide, tin oxide-barium sulfate, and nickel oxide-alumina.

These conductive substances can be used alone or in a mixture of two or more, and the blending amount is 5 parts by weight per 100 parts by weight of the resin composition when considering electric resistance weldability and suitability for electrodeposition coating. -200 parts by weight, preferably 20-100 parts by weight.

If the blending amount is 200 parts by weight or more, the workability of the coating film will be extremely poor and the workability of the pre-coated board cannot be improved, and if the blending amount is 5 parts by weight or less, the electrical conductivity will be insufficient.
The wear of the electrode is severe, and continuous welding performance is significantly reduced, and the strength of the welded part is also reduced. Furthermore, the suitability of electrodeposition paints is not sufficient, and uneven coating and pinholes occur, making it impossible to form a practical coating film.

The lubricating substance can be compatible with or dispersed in the resin composition solution, and reduces the frictional resistance between the coating film and the mold without the need for applying press oil during the molding process of the precoated plate. It has the function of preventing wear on the painted surface and the mold.

As such a lubricant, any known lubricant can be used, and those exemplified below can be used.

Hydrocarbon lubricants: e.g. natural paraffin, synthetic paraffin, microwax, polyethylene wax, chlorinated hydrocarbons, fluorocarbons, etc. Fatty acid lubricants: e.g. lauric acid, stearic acid, palmitic acid, oxyfatty acids, etc. Fatty acid amide lubricants: e.g. Stearic acid amide, palmitic acid amide, methyl bis stearamide, ethylene bis stearamide, oleic acid amide, ethyl acid amide, alkylene bis fatty acid amide.

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Alcohol-based lubricants such as lower alcohol esters of fatty acids, polyhydric alcohol esters of fatty acids such as hydrogenated castor oil, glycol esters or polyglycol esters of fatty acids such as ethylene glycol monostearate, ester waxes, etc. Cetyl alcohol, stearyl alcohol, palmityl alcohol, etc. Metal soaps: e.g. calcium stearin, lead stearate, calcium laurate, calcium palmitate, etc. Metal sulfides: molybdenum disulfide, tungsten disulfide, etc. graphite, boron nitride, grease, alkali metal sulfates, etc.

Although these lubricants can be used alone, the performance can be further improved by using two or more of them in combination.

The blending amount of the lubricating substance is 0.2 to 30 parts by weight, V-koma 1-(l±1 to 10 parts by weight, based on 100 parts by weight of the resin composition. The blending amount exceeds 30 parts by weight. This tends to reduce the adhesion and corrosion resistance of the top coat.

On the other hand, if the amount is less than 0.2 parts by weight, sufficient lubricity effect cannot be obtained.

A chromium compound is blended into the composition of the present invention for the purpose of imparting rust prevention properties. Examples of the chromium compound include potassium zinc chromate, strontium chromate, calcium chromate, lead oxychromate, and tetrabasic zinc chromate.

In addition to the chromic acid compound, conventionally known antirust pigments and silica may be blended as required. Examples of such anti-rust pigments include zinc phosphate, lead cyanamide, calcium lead acid, and zinc molybdate.As for silica, water-dispersed colloidal silica is used as isopropanol, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, etc. Examples include organosilica substituted with an organic solvent, water-dispersible silica, and fumed silica.

It is possible to use two or more of these chromium compounds, anti-rust pigments and silica as a mixture, and the amount of the chromium compounds, anti-rust pigments and silica can be determined by considering the suitability for electric resistance welding and electrocoating, including the anti-rust pigments and silica. , 1 to 40 parts by weight, preferably 5 to 20 parts by weight, per 100 parts by weight of the resin composition.

If the blending amount exceeds 40 parts, the electrodes during electric resistance welding will be severely worn out, resulting in a significant decrease in the number of consecutive welds and the strength of the welded part. Furthermore, suitability for electrodeposition coating is also reduced.

Titanium oxide can be added to the composition of the present invention, if necessary, in order to impart hiding properties. There are two types of titanium oxide: rutile type and anatase type, but 7-natase type titanium oxide is preferable from the viewpoint of electrical conductivity. The blending amount of titanium oxide is 5 to 30 parts by weight per 100 parts by weight of the resin composition.
Parts by weight.

The steel sheet used for carrying out the present invention may be a steel sheet material itself, and may also include a galvanized steel sheet, a zinc-iron alloy plated steel sheet, a zinc-nickel alloy plated steel sheet, a zinc-manganese alloy plated steel sheet, a zinc-aluminum alloy plated steel sheet, Zinc-cobalt-
The plating components of chromium alloy plated steel sheets and any of these steel sheets include Ni, Fe, Mn, Mo, Co, AjL.
, Cr, etc. may be added to one or more types of elements, and furthermore, it may be a composite plated steel sheet with two or more layers of the same or different types of plating as described above. A plating film can be obtained in which two or more layers of Fe-Zn alloy plating with different Fe contents are applied.

The surface of the above-mentioned steel sheets is treated with phosphates such as iron phosphate, zinc phosphate, iron-zinc phosphate, calcium phosphate, etc., or chromic acid,
Chromate treatments such as chromate chromate and electrolytic chromate are applied.

The composition obtained according to the present invention is made into a paint in a solvent type or aqueous solution type (or water dispersion type) by a conventional method, and the solid content concentration is 10 to 60% by weight, preferably 20 to 40% by weight.
A weight percent solution is prepared and applied to the steel plate by a conventionally known method to perform metal surface treatment. The coating film thickness in this case is not particularly limited, but the dry film thickness is usually 0.
．． It is preferable to set it as 5-10 microns.

As the coating method, for example, brush coating, spray coating, roll coating, dip coating, etc. can be used, so it can be applied to a wide range of applications such as coil coating, complex shapes, outdoor structures, etc.

To cure the composition of the present invention, 1. Depending on the type and properties of the organic resin, it may be cured by heating or drying at room temperature, for example, at a temperature of room temperature to 300° C. for about 10 seconds to 30 minutes.

The surface-treated steel sheet thus obtained has lubricating properties, but in order to provide further lubricity, the above-mentioned lubricating substance that does not inhibit the suitability for top coating is coated with a roll coater, spray, etc. You can.

[Function and effect] The weldable rust-preventing, lubricating coating-forming composition obtained by the present invention contains a lubricating substance as well as a conductive substance, so a surface-treated steel sheet coated with this composition is resistant to press oil. Of course, press processing is possible without the need for coating.
It can also be welded and can be painted without a degreasing process, which is a big advantage for home appliance manufacturers and others in shortening the process.

[Example] Hereinafter, the present invention will be specifically explained with reference to Examples.

Examples 1 to 30 and Comparative Examples 1 to 6 (1) Preparation of test pieces (1-1) Degreasing treatment Various steel plates were degreased with a silicate-based alkaline cleaner (CG561B, manufactured by Nippon CB Chemical Co., Ltd.).

(1-2) Application of chromate The chromate-based coating treatment agent shown below was applied using a roll coater to give a chromium content of 50 ag and 100 mg, and dried at an ambient temperature of 200°C for 30 seconds (
S14 plate reached temperature 100°C).

Cosmer 150 Cosmer 200 manufactured by Kansai Paint ■ Kansai Paint Stock (1-3) Formation of coating film Next, the compositions shown in Tables 1 and 2 were applied with a bar coater and coated at an ambient temperature of 320°C for 50 seconds. (Temperature reached at steel plate: 210° C.) It was dried.

(2) Performance test The test pieces described above were subjected to the following tests to evaluate their performance. The results are shown in Table-3.

(2-1) Welding test Continuous spot welding test was performed under the following conditions: two sheets were stacked, 100 spot welds were performed on this, and then 30 x 100 mm
Stack two plates cut into one piece and spot weld them at one point.
Evaluation was made based on the number of dots until a tensile shear strength of 400 kg or more was achieved.

Application of coating: A chromate layer and a film layer of the composition of the present invention are formed on both sides.

Welding #1: Projection-35 (manufactured by Dengensha) Pressure crab 200kg Current near, OKA Current application time: 10 cycles Electrode: DEMI RAS, WA4RD2 b
2 (manufactured by Dengensha) (2-2) Processing test Perform punching cup drawing using a blank diameter of 12c+a and a die diameter of 5.0ca+φ, peel off the processed part three times with cellophane tape, and remove the coating film as shown below. Workability was evaluated based on the amount of peeling.

Peeling amount (mg) - (Blank weight) - (Cup weight after peeling) Workability evaluation O: Peeling amount of film 5 mg or less X: Drawing process impossible (2-3) Corrosion resistance test O Salt water spray test J I 5- In the method according to Z-2371, the coated plate was left in the apparatus for a certain period of time and then taken out and the condition of the coated surface was observed.

0 cycle test 35% NaCfL, 35℃ Salt spray test 2 hours -60℃
The condition of the coated surface was observed after 150 cycles of 4 hours of wet section test at -40° C. and 100% RH for 2 hours of drying.

Corrosion resistance evaluation O: Red rust occurrence area ratio O%Δ: /
/ 1-5% X: tt 5% or more (2-4) Humidity a
! ! Place the test coated plate in a humid test box at 49±1℃ and 100%RH.
After leaving it for 000 hours, take it out and leave it at room temperature for 24 hours.
11 lines perpendicular to the coating surface at 1 mm intervals,
Then, use a sharp knife to make straight openings that reach the base surface, and process to obtain 100 squares. Next, apply cellophane adhesive tape with a width of 20 mm to the surface of the coating at the squares. Press it firmly with your hand to make it dense, then quickly peel it off and check the number of gobans that remain without being removed.
The test results were displayed using that number.

Wet test evaluation O: Only flaking is observed Δ: Partial flaking is observed <99/100~B0/ ×: Much exposed area is observed (80/100~0/Zoo) 1) Mitsui Manufactured by Toatsu ■, trade name Akey 8200 pieces 2) Manufactured by Hooker Chemical Co., trade name Ferrophos HR5-213
1 *3) Manufactured by Inco, trade name Nickel Powder No.

4) Manufactured by Gifu Serax Co., Ltd., product name TE-10P-
5) However, for the water-dispersed acrylic resins of Examples 19 to 24, Mobil Q, a product of Mobil Chemical Company, was used.
A dispersion) Zero 6) Teikoku Kako ■, trade name Titanium White JA-1 Wood 7) Toyo Ink ■, trade name BOX-5084 (acrylic emulsion) 80 parts by weight and Mitsui Toatsuoki, trade name UFR-6
5 (methylated urea resin), 20 parts by weight (solid content).

8) Manufactured by Dainippon Ink Co., Ltd., product name M-6402 (980 parts by weight of oil-free polyester and Dainippon Ink Co., Ltd.,
Product name Beckamine P-196 (urea resin) 20 parts by weight (
solid content).

8) Manufactured by Kansai Paint Company, undercoat primer for general color tanning 10) Manufactured by Kansai Paint Company, undercoat primer for processing applications

Claims (1)

[Claims] 1. A resin composition consisting of an organic resin selected from epoxy resins, polyester resins, and acrylic resins and an amino resin or polyisocyanate as a curing agent component, and a conductive substance, a chromium compound, and a lubricating substance. 1. A weldable rust-preventing, lubricating, coating-forming composition comprising: 2. The weldable rust-preventing, lubricating coating-forming composition according to claim 1, wherein the conductive substance comprises carbon black, graphite, metal powder, semiconductor oxide, and iron phosphide. 3. The lubricating substance is a hydrocarbon-based lubricant, a fatty acid-based lubricant, a fatty acid amide-based lubricant, an ester-based lubricant, an alcohol-based lubricant,
The weldable rust-preventing, lubricating coating-forming composition according to claim 1, which comprises metal soaps and metal sulfides. 4. Weldable rust-preventing, lubricating coating forming property according to claim 1, wherein the chromium compound is composed of strontium chromate, potassium zinc chromate, tetrabasic zinc chromate, calcium chromate, and lead oxychromate. Composition. 5. A resin composition consisting of an organic resin selected from epoxy resins, polyester resins, and acrylic resins and an amino resin or polyisocyanate as a curing agent component, mixed with a conductive substance, a chromium compound, and a lubricating substance. A method for producing a surface-treated steel sheet, which comprises applying a rust-lubricious coating-forming composition to the surface of a steel sheet that has been previously phosphate-treated or chromate-treated. 6. The method for manufacturing a surface-treated steel sheet according to claim 4, further comprising applying a lubricating substance to the surface of the surface-treated steel sheet.