JPH0692567B2 - Weldable rust preventive lubricity coating forming composition and method for producing surface-treated steel sheet using the same - Google Patents

Description

TECHNICAL FIELD The present invention relates to a weldable rust preventive lubricity coating forming composition and a method for producing a surface-treated steel sheet using the same.

[Prior Art] Conventionally, in the field of metal coating, for example, home appliance makers, building material makers, and steel furniture makers, product coating is generally
Press oil coating on steel plate → pressing → welding → degreasing → surface treatment → painting.

[Problems to be Solved by the Invention] However, the conventional coating method is unsatisfactory in terms of labor saving and productivity, as many as 6 steps, and it is necessary to take pollution measures such as wastewater treatment, which causes a cost increase. ing. Therefore, in the field of metal coating, the appearance of a surface-treated steel sheet coated with a primer composition having functions of lubricity, weldability, and suitability for top coating is strongly desired.

[Means for Solving Problems] The present inventors have conducted research to obtain a primer composition and a surface-treated steel sheet that solve the problems in the conventional coating process described above and can save labor. A composition in which a conductive material, a chromium compound and a lubricating material are mixed with a resin composition containing an epoxy resin, a polyester resin and an acrylic resin as a base resin is weldable and can form a rust preventive lubricity coating. They have found the present invention and completed the present invention.

Thus, according to the present invention, a resin composition comprising an organic resin selected from an epoxy resin, a polyester resin and an acrylic resin and an amino resin or polyisocyanate which is a curing agent component, is provided with a conductive substance, a chromium compound and a lubricating substance. A weldable rust-preventive lubricity coating-forming composition characterized by being blended with an organic resin selected from an epoxy resin, a polyester resin and an acrylic resin, and an amino resin or polyisocyanate which is a curing agent component. The resin composition, a conductive material, chromium compound and a rust preventive lubricity coating forming composition comprising a lubricating substance is characterized in that it is applied to the steel sheet surface that has been previously phosphate-treated or chromate-treated A method for manufacturing a surface-treated steel sheet is provided.

Hereinafter, the present invention will be described in detail.

The organic resin used in the present invention is selected from an epoxy resin, a polyester resin and an acrylic resin having a functional group (for example, a hydroxyl group, a carboxyl group, an epoxy group, etc.) reactive with an amino resin or a polyisocyanate which is a curing agent component. Or dissolve it in an organic solvent,
Alternatively, a functional group (a hydroxyl group, a carboxyl group, an amino group, etc.) may be introduced into the resin skeleton and neutralized with an acid or an alkali to be water-soluble or water-dispersed for use.

The epoxy resin, epichlorohydrin type, straight epoxy resin such as glycidyl ether type, fatty acid modified epoxy resin, polybasic acid modified epoxy resin, acrylic resin modified epoxy resin, alkyd (or polyester) modified epoxy resin, polybutadiene modified epoxy resin, Phenol-modified epoxy resin, amine- or polyamine-modified epoxy resin, urethane-modified epoxy resin and the like are used.

As the polyester resin, a generally known one obtained by an ordinary synthesis method including an alkyd resin can be used.
Examples thereof include oil-modified alkyd resin, rosin-modified alkyd resin, phenol-modified alkyd resin, styrenated alkyd resin, silicone-modified alkyd resin, acrylic-modified alkyd resin, and oil-free alkyd resin (polyester resin).

The acrylic resin is a resin synthesized by a solution polymerization method, an emulsion polymerization method, a suspension polymerization method, or the like using a usual unsaturated ethylenic monomer, and is a methacrylate monomer, acrylonitrile, or styrene. , Acrylic acid, acrylamide, vinyltoluene and other hard monomers as essential components, and by further blending other unsaturated vinyl monomers for the purpose of imparting resin hardness, flexibility and crosslinkability, The desired resin is obtained. Further, this resin may be modified with other alkyd resin, epoxy resin, phenol resin or the like.

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

The polyisocyanate is preferably blocked, for example, toluidine diisocyanate (TDI), 4,4'-diphenylmethane diisocyanate (MDI), xylene diisocyanate (XDI), hexamethylene diisocyanate (HMDI), isophorone. Examples thereof include those obtained by blocking diisocyanate (IPDI) with phenol, malonic acid diethyl ester, ethyl acetoacetate, acetylacetone, cresol and oxime.

The mixing ratio of the above-mentioned organic resin and curing agent component is in the range of 60/40 to 95/5, preferably 75/25 to 90/10 in terms of solid content weight ratio.

Next, the conductive substance blended in the resin composition comprising the above-mentioned organic resin and curing agent component is, for example, zinc, aluminum, iron, cobalt, nickel, manganese, chromium, molybdenum, tungsten, copper, lead, tin, etc. Metal powder and alloy powders thereof, conductive carbon, graphite powder, iron phosphide powder, aluminum-doped zinc oxide powder, tin oxide-
Titanium oxide, tin oxide-barium sulfate, nickel oxide-
Examples thereof include semiconductor oxides such as alumina.

These conductive substances can be used alone or in combination of two or more, and the compounding amount thereof is 5 with respect to 100 parts by weight of the resin composition in consideration of electric resistance weldability and suitability for electrodeposition coating. ˜200 parts by weight, preferably 20 to 100 parts by weight.

When the blending amount is 200 parts by weight or more, the workability of the coating film is significantly deteriorated, and the workability of the precoated plate cannot be endured. On the other hand, if the amount is 5 parts by weight or less, the electrical conductivity is insufficient, the electrode is severely worn, the continuous weldability is significantly reduced, and the strength of the welded portion is also reduced. In addition, the suitability for electrodeposition coating is not sufficient, and uneven coating, pinholes, etc. occur and a practical coating film is not formed.

Lubricating substances are compatible or dispersible in the resin composition solution, and do not require the application of a press oil during the molding process of the precoated plate, and have the function of reducing the frictional resistance between the coating film and the mold. Therefore, it has an effect of preventing abrasion of the coated surface and the mold.

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

Hydrocarbon lubricants: for example, natural paraffin, synthetic paraffin, microwax, polyethylene wax, chlorinated hydrocarbons, fluorocarbons, etc., fatty acid lubricants: for example, lauric acid, stearic acid, palmitic acid, oxyfatty acids, etc. Fatty acid amide lubricants: for example Stearic acid amide, palmitic acid amide, methyl bis stearoamide, ethylene bis stearoamide, oleic acid amide, esyl acid amide, alkylene bis fatty acid amide, etc.

Ester lubricants: lower alcohol esters of fatty acids such as butyl stearate, 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 Alcoholic lubricants such as cetyl alcohol, stearyl alcohol, palmityl alcohol, etc. Metal soaps such as calcium stearate, lead stearate, calcium laurate, calcium palmitate, etc. Metal sulfides: molybdenum disulfide, tungsten disulfide , Others: Graphite, fluorinated graphite, boron nitride, grease, alkali metal sulfate, etc.

These lubricants can be used alone, but can be further improved by using two or more kinds in combination.

The blending amount of the lubricating substance is 100 parts by weight of the resin composition.
0.2 to 30 parts by weight, preferably 1 to 10 parts by weight. If the blending amount exceeds 30 parts by weight, the adhesion and corrosion resistance of the top coating film tend to decrease.

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 added to the composition of the present invention for the purpose of imparting rust prevention. Examples of the chromium compound include zinc potassium chromate, strontium chromate, calcium chromate, lead oxychromate, and tetrabasic zinc chromate.

In addition to the chromic acid compound, conventionally known anticorrosion pigments and silica can be blended as necessary. Examples of such rust preventive pigments include zinc phosphate, lead cyanamide, lead acid calcium, and zinc molybdate. As silica, water-dispersed colloidal silica is isopropanol, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, or other organic solvent. Examples thereof include organosilica and water-dispersible silica substituted with, and fumed silica.

These chromium compounds, rust preventive pigments and silica can be used as a mixture of two or more types, and the blending amount is in consideration of suitability for electric resistance welding and electrodeposition coating including rust preventive pigments and silica. , 1 to 40 parts by weight, preferably 5 to 20 parts by weight, based on 100 parts by weight of the resin composition. If the amount is 40 parts or more, the resistance of the electrode during electric resistance welding will be severely worn, the number of continuous dots will be significantly reduced, and the strength of the weld will also be reduced. In addition, the suitability for electrodeposition coating is also reduced.

Titanium oxide may be added to the composition of the present invention, if necessary, in order to impart hiding property. Titanium oxide includes rutin type and anatase type, but anatase type titanium oxide is preferable from the viewpoint of electrical conductivity. The compounding amount of titanium oxide is 5 to 30 parts by weight with respect to 100 parts by weight of the resin composition.

The steel plate used for carrying out the present invention may be a steel plate material itself, or a galvanized steel plate, a zinc-iron alloy plated steel plate, a zinc-nickel alloy plated steel plate, a zinc-manganese alloy plated steel plate, a zinc-aluminum alloy plated steel plate, It is preferable to use zinc-cobalt-chromium alloy-plated steel sheets, and further, to add any one or more elements such as Ni, Fe, Mn, Mo, Co, Al and Cr to the plating components of these arbitrary steel sheets. Further, it may be a composite plated steel sheet in which two or more layers of the same kind or different kinds of plating as described above are applied. For example, it is possible to form a plating film in which two or more layers of Fe-Zn alloy plating having different Fe contents are applied.

For the purpose of imparting rust prevention and coating groundability to the surface of the above steel sheet, phosphate treatment of conventionally known iron phosphate, zinc phosphate, zinc iron phosphate, calcium phosphate, etc., chromic acid, chromium chromate , Chromate treatment such as electrolytic chromate is applied.

The composition obtained according to the present invention is made into a solvent-less or aqueous solution type (or water dispersion type) by a conventional method,
A solution having a solid content concentration of 10 to 60% by weight, preferably 20 to 40% by weight is prepared, and the steel sheet is coated by a conventionally known method for surface treatment of metal. In this case, the coating film thickness is not particularly limited, but it is usually preferable that the dry film thickness is 0.5 to 10 μm.

As a coating method, for example, a brush coating method, a spray coating method, a roll coating method, a dipping coating method, or the like can be used, and thus it can be applied to a wide range of applications such as coil coating, complex shapes, and outdoor structures.

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

The surface-treated steel sheet thus obtained has lubricity, but in order to impart further lubricity, the above-mentioned lubricity substance that does not impair the suitability for top coating is applied by a roll coater, spray, etc. May be.

[Effect] Since the weldable rust preventive lubricity coating forming composition obtained by the present invention contains a conductive substance as well as a lubricating substance, the surface-treated steel sheet coated with this composition has Of course, press work is possible without the need for coating,
Since welding is possible and coating can be performed without taking a degreasing process, there is a great merit that the process can be shortened for home appliance makers and the like.

[Examples] Hereinafter, the present invention will be specifically described 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 sheets were degreased with a silicate-based alkaline cleaner (CC561B, manufactured by Japan CB Chemicals).

(1-2) Application of chromate The chromium chromate-based coating type treatment agent shown below was applied by a roll coater so that the amount of chromium would be 50 mg and 100 mg, and dried at an ambient temperature of 200 ° C for 30 seconds (a steel plate reaching temperature 1
00 ℃).

Cosmer 150 manufactured by Kansai Paint Co., Ltd. Cosmer 200 manufactured by Kansai Paint Co., Ltd. (1-3) Formation of coating film Next, the compositions shown in Tables 1 and 2 were applied with a bar coater, and the coating was performed at 320 ° C. 50 seconds at ambient temperature (Steel plate temperature 2
10 ° C) and dried.

(2) Performance test The following test was performed on the test piece to evaluate the performance. The results are shown in Table-3.

(2-1) Welding test A continuous spot welding test was performed under the following conditions to perform secondary stacking, 100-point spot welding was performed on it, and then two sheets cut into 30 x 100 mm were stacked and 1-point spot welding was performed on them. It was evaluated by the number of hit points until a tensile shear strength of 400 kg or more was secured.

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

Welding machine: Projection-35 (manufactured by Dengen) Pressing force: 200 kg Current: 7.0 kA Energizing time: 10 cycles Electrode: DEMIRAS, WA4RD2b2 (manufactured by Dengen) (2-2) Processing test Blank diameter 12 cm, die diameter 5.0 A punched cup was punched with cmφ, and the processed portion was repeatedly peeled off with a cellophane tape three times, and the workability was evaluated by the peeling amount of the coating film as follows.

Peeling amount (mg) = (blank weight)-(cup weight after peeling) Workability evaluation ◯: Peeling amount of film 5 mg or less ×: Impossible to draw (2-3) Corrosion resistance test Salt spray test JIS-Z-2371 By the method. After leaving the coated plate for a certain period of time, the coated plate was taken out and the state of the coated surface was observed.

Cycle test 35% NaCl, 35 ℃ Salt spray test 2 hours -60 ℃ Drying 2 hours-
A wet test at 40 ° C. and 100% RH for 4 hours was set as one cycle, and the coated surface state after 150 cycles was observed.

Corrosion resistance evaluation ○: Red rust occurrence area ratio 0% △: 〃 1-5% ×: 〃 5% or more (2-4) Wetting test Place the coated plate in a humidity test box of 49 ± 1 ° C, 100% RH for 1000 hours. After taking it out and leaving it at room temperature for 24 hours, make 11 straight lines on the surface of the coating film at intervals of 1 mm and make a straight incision reaching the ground surface with a sharp knife. After processing so that the eyes can be obtained, the cellophane adhesive tape with a width of 20 mm is pressed firmly against the surface of the coating film in the eye-catching area by hand to bring it into close contact. The number was examined and the test result was displayed by the number.

Wet test evaluation ○: No peeling is recognized (100/100) △: Partial peeling is recognized (99/1
00 to 80/100) ×: Many peeling areas are recognized (80/1
00 ~ 0/100)

Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location C23F 11/00 B 8414-4K

Claims (6)

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