JP2011202047A - Cationic electrocoating composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cationic electrocoating composition capable of forming an excellent coated film with a limited rust-preventing property and rust-preventing property on an untreated steel sheet without containing a harmful material such as a lead compound and a chromium compound.SOLUTION: The cationic electrocoating composition contains (A) a cationic amine-modified epoxy resin (a base resin) obtained by cationizing an amine-modified epoxy resin obtained by reacting an epoxy resin with an amine, (B) a blocked polyisocyanate (a curing agent resin), (C) zinc oxide and (D) zirconium hydroxide. The composition is useful for the electrocoating of the body of an automobile, a component thereof, an electric apparatus or the like.

Description

  The present invention relates to a cationic electrodeposition coating composition capable of exhibiting excellent rust preventive properties, particularly for untreated steel sheets, without containing harmful substances such as lead compounds and chromium compounds.

  Electrodeposition coating has better throwing power and less environmental pollution compared to air spray coating and electrostatic spray coating for automobile body and its parts, and parts with a bag structure such as electric appliances. Therefore, it has been widely put to practical use as a primer coating. And the antirust pigment is added for the purpose of improving the antirust quality further.

  As typical anti-rust pigments, there are lead compounds and chromium compounds. However, in view of recent trends in environmental regulations and legal regulations, paints containing such harmful substances are not preferable. Therefore, in recent years, non-toxic or low-toxic rust preventive pigments have been developed, and cationic electrodeposition coating compositions using these have been put into practical use.

  Patent Documents 1 to 6 can be cited as cationic electrodeposition coating compositions using non-toxic or low-toxic rust preventive pigments. Specifically, for anti-corrosive pigments, Patent Documents 1 and 2 describe bismuth compounds, Patent Document 3 describes tungsten oxide, Patent Document 4 describes condensed aluminum phosphate compounds, and Patent Document 5 describes The phosphate compound is described. However, these technologies are limited to conventional cationic electrodeposition coating compositions that use rust preventive pigments that contain harmful substances such as lead compounds and chromium compounds in terms of rust resistance on untreated steel sheets. There is a problem that sufficient rust preventive power cannot be obtained as compared with products.

  Further, in Patent Document 6, a zirconium compound is described as a rust preventive pigment in addition to a bismuth compound, but the zirconium compound is not superior in rust preventive property than the bismuth compound, and has a limit rust preventive property. The anticorrosive property on the non-treated steel sheet is about the same as the above-mentioned Patent Documents 1 to 5. Therefore, the electrodeposition paint which does not contain harmful substances such as lead compounds and chromium compounds still has insufficient rust prevention performance.

JP 2000-230151 A JP-A-11-106687 JP-A-6-220371 JP 2001-329221 A Japanese Patent Laid-Open No. 9-241546 JP 2000-290542 A

  The present invention was devised in view of the current state of the prior art, and its purpose is to contain no harmful substances such as lead compounds and chromium compounds, and to limit rust prevention and rust prevention on untreated steel sheets. Is to provide a cationic electrodeposition coating composition that exhibits more superior properties than a cationic electrodeposition coating composition using an existing non-toxic or low-toxic rust preventive pigment.

  As a result of diligent studies to achieve the above object, the present invention dramatically improves rust prevention by using zinc oxide and zirconium hydroxide together as a rust preventive agent. By blending with amine-modified epoxy resin (base resin) and blocked polyisocyanate (curing agent), it has superior rust prevention and superior rust prevention on untreated steel sheet compared to existing electrodeposition coating compositions. The inventors have found that this can be achieved, and have completed the present invention.

That is, the present invention has the following configurations (1) to (3).
(1) (A) a cationic amine-modified epoxy resin (base resin) obtained by cationizing an amine-modified epoxy resin obtained by reacting an amine with an epoxy resin, (B) a blocked polyisocyanate (curing agent resin), ( A cationic electrodeposition coating composition comprising C) zinc oxide and (D) zirconium hydroxide.
(2) The epoxy resin of (A) cationic amine-modified epoxy resin (base resin) is an epoxy resin obtained by reacting a glycidyl ether of a polyol, a glycidyl ether of a dihydric phenol and a dihydric phenol. The cationic electrodeposition coating composition as described in (1), which is characterized in that
(3) (B) Blocked polyisocyanate (curing agent resin) is a modified blocked polyisocyanate in which a part of the isocyanate groups of the polyisocyanate are connected with a polyol and the remaining isocyanate groups are blocked with a blocking agent. The cationic electrodeposition coating composition as described in (1) or (2) above.

  According to the present invention, without containing harmful substances such as lead compounds and chromium compounds, the limit rust resistance (especially salt water spray test and warm salt water immersion test) and rust resistance on untreated steel sheet (especially In the salt spray resistance test and the warm salt water immersion test), characteristics equivalent to or higher than those of conventional cationic electrodeposition coating compositions using rust preventive pigments containing harmful substances such as lead compounds and chromium compounds are achieved. Therefore, the cationic electrodeposition coating composition of the present invention is extremely useful for electrodeposition coating of automobile bodies, parts thereof, electric appliances and the like.

  The cationic electrodeposition coating composition of the present invention comprises (A) a cationic amine-modified epoxy resin (base resin) obtained by cationizing an amine-modified epoxy resin obtained by reacting an epoxy resin with an amine, and (B) blocking. It contains polyisocyanate (curing agent resin), (C) zinc oxide, and (D) zirconium hydroxide.

[(A) Base resin]
(A) Base resin is a cationic amine-modified epoxy resin obtained by cationizing an amine-modified epoxy resin obtained by reacting an epoxy resin with an amine. The epoxy resin before amine modification is preferably an epoxy resin having two epoxy groups in one molecule on average, and its epoxy equivalent is preferably 400 to 3000, particularly 500 to 1500. The main component constituting the epoxy resin is glycidyl ether of dihydric phenol. Examples of the dihydric phenol include resorcin, hydroquinone, 2,2-bis- (4-hydroxyphenyl) -propane, 4,4′-dihydroxybenzophenone, 1,1-bis- (4-hydroxyphenyl) -methane, 1, 1-bis- (4-hydroxyphenyl) -ethane, 4,4′-dihydroxybiphenyl and the like can be mentioned, but 2,2-bis- (4-hydroxyphenyl) -propane, so-called bisphenol A is particularly preferable. is there.

  (A) Glycidyl ethers, such as a polyol, a polyalkyl polyol, a polyalkylphenol, can also be added to a base resin as a flexible modifier as needed. As the introduction method, these flexible glycidyl ethers are reacted with an excess of a dihydric phenol to obtain an initial condensate, and then the chain length is extended to a target molecular weight by the reaction with a divalent phenol glycidyl ether. The method is exemplified as one having good reaction efficiency, but is not limited thereto. As the dihydric phenol used in the above dihydric phenol or glycidyl ether of dihydric phenol, resorcin, hydroquinone, 2,2-bis- (4-hydroxyphenyl) -propane, 4,4′-dihydroxybenzophenone, Examples include 1,1-bis- (4-hydroxyphenyl) -methane, 1,1-bis- (4-hydroxyphenyl) -ethane, 4,4′-dihydroxybiphenyl, and the like is particularly preferably 2. , 2-bis- (4-hydroxyphenyl) -propane, so-called bisphenol A.

  Moreover, flexibility can be imparted to the hydroxyl group present in the epoxy skeleton, for example, by adding an isocyanate half-blocked with a polyol, and the molecular weight can be adjusted.

  Reactions of diglycidyl ethers such as polyols, polyalkyl polyols, and polyalkylphenols with dihydric phenol diglycidyl ethers and dihydric phenols can be carried out in a solvent-free melt, but a system with a small amount of solvent added. It is also possible to do this. The solvent is not particularly limited as long as it does not react with the epoxy group. The reaction temperature is suitably 70 to 180 ° C.

  As amines to be reacted with the epoxy resin, methylamine, ethylamine, n-propylamine, isopropylamine, monoethanolamine, diethylamine, diethanolamine, N-methylethanolamine, N-ethylethanolamine, ethylenediamine, diethylenetriamine, hydroxyethylaminoethylamine , Ethylaminoethylamine, methylaminopropylamine, dimethylaminopropylamine and the like, or a mixture thereof. In the reaction between the epoxy resin and the amine, the primary amino group may be blocked by reacting with a ketone in advance, and then the remaining active hydrogen may be reacted with the epoxy group.

  The amination in which the epoxy resin and the amine are reacted can be carried out in a solvent or in a melt without a solvent, and the reaction temperature is suitably 40 to 150 ° C.

  The amine-modified epoxy resin can be cationized by neutralizing the amino group with a protonic acid. Preferred examples of the protonic acid include formic acid, lactic acid, acetic acid, propionic acid, citric acid, malic acid, sulfamic acid, and the like, or a mixture thereof. The neutralization degree of the acid is preferably 15 to 85%.

[(B) Curing agent resin]
(B) The curing agent resin is a blocked polyisocyanate obtained by reacting a polyisocyanate and a blocking agent. The polyisocyanate is an aromatic or aliphatic (including alicyclic) polyisocyanate, such as 2,4- or 2,6-tolylene diisocyanate and a mixture thereof, p-phenylene diisocyanate, diphenylmethane-4,4 ′. -Diisocyanate, polymethylene polyphenyl diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, 1,3 or 1,4-bis- (isocyanate methyl) -cyclohexane, dicyclohexylmethane-4,4'-diisocyanate, bis- ( Isocyanatomethyl) -norbornane, 3 or 4-isocyanatomethyl-1-methylcyclohexyl isocyanate, m- or p-xylylene diisocyanate, m- or p Tetramethylxylylene diisocyanate, more may be mentioned biuret modified product or an isocyanurate modified product of the isocyanate.

  Furthermore, what connected a part of isocyanate group of the said isocyanate with the polyol can be mentioned. For example, ethylene glycol, propylene glycol, 1,6-hexanediol, neopentyl glycol, diethylene glycol, triethylene glycol, low molecular diols such as 1,4-cyclohexanediol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polylactone Examples thereof include oligomeric diols such as diols, polyisocyanates linked with polyols such as trimethylolethane, trimethylolpropane, and pentaerythritol, and mixtures thereof.

  Examples of the blocking agent include aliphatic alcohol compounds such as methanol, ethanol, n-butanol and 2-ethylhexanol, cellosolve compounds such as ethylene glycol monobutyl ether and ethylene glycol monohexyl ether, diethylene glycol monoethyl ether and diethylene glycol monobutyl ether. Carbitol compounds, oxime compounds such as acetone oxime, methyl ethyl ketone oxime and cyclohexanone oxime, lactam compounds such as ε-caprolactam, phenol compounds such as phenol, cresol and xylenol, active methylene such as ethyl acetoacetate and diethyl malonate Mention may be made of group-containing compounds.

  The reaction between the polyisocyanate and the blocking agent can be carried out in a solvent or in a melt. Solvents used for the reaction include solvents that do not react with polyisocyanates, such as ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclopentanone, cyclohexane, and isophorone, and aromatics such as benzene, toluene, xylene, chlorobenzene, and nitrobenzene. Examples thereof include hydrocarbons, cyclic ethers such as tetrahydrofuran, and halogenated hydrocarbons such as chloroform. Although there is no limitation in particular about reaction temperature, Preferably it is 30-150 degreeC.

[(C) Zinc oxide]
(C) A commercial item can be used for zinc oxide, for example, 1 type of zinc oxide prescribed | regulated by JISK-1410, 2 types of zinc oxide, and 3 types of zinc oxide can be mentioned.

[(D) Zirconium hydroxide]
Examples of (D) zirconium hydroxide include R zirconium hydroxide and NN zirconium hydroxide manufactured by Daiichi Elemental Chemical Co., Ltd. Zirconium hydroxide is insoluble in water and does not dissolve or ionize in the paint. (D) Zirconium hydroxide is different from zirconyl nitrate, zirconyl acetate, zirconyl sulfate and the like which are ionized when mixed with water.

  Since the cationic electrodeposition coating composition of the present invention uses zinc oxide and zirconium hydroxide in combination, it has the limit of rust resistance (particularly salt spray resistance test and warm salt immersion test) and rust resistance on an untreated steel sheet. (In particular, salt spray resistance tests and warm salt water immersion tests), the same or better characteristics than conventional cationic electrodeposition coating compositions using rust preventive pigments containing harmful substances such as lead compounds and chromium compounds have been achieved. The When zinc oxide or zirconium hydroxide is used alone, the effects of the present invention are not achieved.

  The contents of zinc oxide and zirconium hydroxide used in the cationic electrodeposition coating composition of the present invention are not particularly limited, but are preferably 0.1 each for 100 parts by weight of the total resin solid content in the coating composition. -15 parts by weight, more preferably 0.1-10 parts by weight of each. In addition, the content ratio of (A) cationic amine-modified epoxy resin (base resin) and (B) blocked polyisocyanate (curing agent resin) in the coating composition is 90 to 40/10 to 10 in terms of solid content weight ratio. 60, preferably 85-40 / 15-60, more preferably 80-55 / 20-45.

  In addition to the components (A), (B), (C) and (D) described above, the cationic electrodeposition coating composition of the present invention may further contain conventional coating additives such as titanium white and carbon as required. Color pigments such as black and bengara, body pigments such as kaolin, talc, aluminum silicate, calcium carbonate, mica, clay, silica, zinc phosphate, iron phosphate, aluminum phosphate, calcium phosphate, aluminum tripolyphosphate, zinc molybdate, Additives such as rust preventive pigments such as aluminum molybdate, calcium molybdate, and bismuth compounds, antifoaming agents, repellency inhibitors, aqueous solvents, curing catalysts, and the like can be contained. In addition, other resins such as acrylic resin, polyester resin, urethane resin, and butadiene resin can be contained.

[Preparation of electrodeposition coating composition]
The method for preparing the cationic electrodeposition coating composition of the present invention is not particularly limited. For example, (A) the base resin and (B) the curing agent resin are charged into a reaction vessel, and after stirring and mixing, Acid is added to cationize the amino group of the amine-modified epoxy resin, and water is added to prepare an emulsion. On the other hand, (A) a base resin is added with acid and water to prepare a water-soluble vehicle. (C) Zinc oxide and (D) Zirconium hydroxide and, if necessary, color pigments and additives are added, and then dispersed to a required particle size with a disperser such as a sand mill to prepare a pigment paste. Thus, it can prepare by mixing the obtained emulsion and pigment paste, respectively.

[About painting methods]
The cationic electrodeposition coating composition of the present invention can be usually applied to the surface of a desired base by known cationic electrodeposition coating in a state dispersed in water. Specifically, the solid content concentration of the paint is preferably about 5 to 40% by weight, more preferably 15 to 25% by weight, the pH is adjusted to 5 to 8, the bath temperature is 15 to 35 ° C., and the load voltage is 100. Under the condition of ~ 450V, the object to be coated can be applied as a cathode. After the coated object is washed with water, a cured coating film can be obtained by baking at 100 to 200 ° C. for 10 to 30 minutes in a baking oven. Although the film thickness of the coating film obtained from the cationic electrodeposition coating composition of the present invention is not particularly limited, 5 to 60 μm, preferably 10 to 40 μm is appropriate for the cured coating film.

  The excellent effects of the cationic electrodeposition coating composition of the present invention are shown by the following examples, but the present invention is not limited thereto.

(Manufacture of base resin A1)
Base resin A1 was manufactured by the method shown below using the raw materials shown in Table 1. Raw materials (1), (2), and (3) were charged into a 3 liter four-necked flask equipped with a stirrer, a thermometer, and a cooling tube, and the temperature was raised to 150 ° C. by stirring and heating. After holding at 150 ° C. for 6 hours, the raw material (4) was gradually added and cooled to 80 ° C. Next, the raw material (5) was charged and the temperature was raised to 100 ° C. After holding at 100 ° C. for 2 hours, it was cooled to 80 ° C. and taken out. The obtained base resin A1 had a solid content of 70%.

(Manufacture of base resin A2)
Base resin A2 was manufactured by the method shown below using the raw materials shown in Table 2. Raw materials (1), (2), (3), and (4) were charged into a 5-liter four-necked flask equipped with a stirrer, thermometer, and cooling tube, and the temperature was raised to 150 ° C. by stirring and heating. . After holding at 150 ° C. for 6 hours, the raw material (5) was gradually added and cooled to 80 ° C. Next, the raw material (6) was charged and the temperature was raised to 100 ° C. After holding at 100 ° C. for 2 hours, it was cooled to 80 ° C. and taken out. The obtained base resin A2 had a solid content of 70%.

(Production of curing agent resin B1)
Curing agent resin B1 was manufactured by the method shown below using the raw materials shown in Table 3. Raw materials (1) and (2) were charged into a 5 liter four-necked flask equipped with a stirrer, a thermometer, and a cooling tube, and the temperature was raised to 100 ° C. by stirring and heating. Thereafter, while keeping the temperature in the flask at 100 ° C., a solution of the raw material (4) previously dissolved in the raw material (3) was charged over 1 hour and reacted at 100 ° C. for 2 hours. Next, the raw material (5) was added dropwise over 1 hour while maintaining the same temperature. After the addition, the material (5) was further maintained at 100 ° C. for 2 hours, and then cooled to 80 ° C. and taken out. The obtained curing agent resin B1 had a solid content of 75%.

(Production of curing agent resin B2)
Curing agent resin B2 was manufactured by the method shown below using the raw materials shown in Table 4. Raw materials (1), (2), and (3) were charged into a 3 liter four-necked flask equipped with a stirrer, a thermometer, and a cooling tube, and the temperature was raised to 100 ° C. by stirring and heating. Thereafter, while keeping the temperature in the flask at 100 ° C., a solution of the raw material (5) previously dissolved in the raw material (4) was charged over 1 hour and reacted at 100 ° C. for 2 hours. Subsequently, the same temperature was maintained, and the raw material (6) was dropped over 1 hour. After dropping, the raw material (6) was further maintained at 100 ° C. for 2 hours, and then cooled to 80 ° C. and taken out. The obtained curing agent resin B2 had a solid content of 75%.

[Preparation of Emulsion E1]
857 parts by weight of base resin A1, 400 parts by weight of curing agent resin B1, and 50 parts by weight of propylene glycol monophenyl ether were charged into a reaction vessel equipped with a stirrer, a thermometer, a cooler, and a decompression device. After thorough mixing, 35.6 parts by weight of 50% lactic acid was added to the reaction vessel, stirred at 40 to 70 ° C. for 30 minutes, and then 701 parts by weight of deionized water was added. Subsequently, emulsification was performed at the same time while removing a predetermined amount of solvent at about 70 ° C. under a pressure of 300 to 600 mmHg (gauge pressure). Thereafter, 1296 parts by weight of deionized water was added to obtain an emulsion E1 having a solid content of 30%.

[Preparation of Emulsion E2]
857 parts by weight of base resin A2, 400 parts by weight of curing agent resin B1, and 50 parts by weight of propylene glycol monophenyl ether were charged into a reaction vessel equipped with a stirrer, a thermometer, a cooler, and a decompression device. After thorough mixing, 35.6 parts by weight of 50% lactic acid was added to the reaction vessel, stirred at 40 to 70 ° C. for 30 minutes, and then 701 parts by weight of deionized water was added. Subsequently, emulsification was performed at the same time while removing a predetermined amount of solvent at about 70 ° C. under a pressure of 300 to 600 mmHg (gauge pressure). Thereafter, 1296 parts by weight of deionized water was added to obtain an emulsion E2 having a solid content of 30%.

[Preparation of Emulsion E3]
857 parts by weight of the base resin A2 and 400 parts by weight of the curing agent resin B2 were charged into a reaction vessel equipped with a stirrer, a thermometer, a cooler, and a decompression device. After thorough mixing, 35.6 parts by weight of 50% lactic acid was added to the reaction vessel and stirred at 40-70 ° C. for 30 minutes, and then 751 parts by weight of deionized water was added. Subsequently, emulsification was performed at the same time while removing a predetermined amount of solvent at about 70 ° C. under a pressure of 300 to 600 mmHg (gauge pressure). Thereafter, 1296 parts by weight of deionized water was added to obtain an emulsion E3 having a solid content of 30%.

[Preparation of pigment paste]
Each raw material was charged into a container with the formulation shown in Table 5 and Table 6, and sufficiently stirred with a dissolver, and then dispersed with a horizontal sand mill until the particle gauge particle size became 10 μm or less, thereby obtaining pigment pastes P1 to P10.

Examples 1-9, Comparative Examples 1-5
In the composition shown in Table 7 and Table 8, 431 parts by weight of pigment paste, 431 parts by weight of deionized water, and 16 parts by weight of zinc oxide and zirconium hydroxide as shown in Tables 7 and 8 are added to 1948 parts by weight of the emulsion. Thus, the cationic electrodeposition paints of Examples 1 to 9 and Comparative Examples 1 to 5 were obtained.

[Test plate preparation method]
Using the above-mentioned cationic electrodeposition coating, the carbon electrode as an anode, a degreased cold rolled steel sheet (manufactured by Partec Co., Ltd., 0.8 × 70 × 150 mm, no chemical conversion treatment) as a cathode, and a film after baking Electrodeposition coating was performed under the condition that the thickness was 15 μm, and baking was performed at 170 ° C. for 20 minutes to obtain test plates.

The following (1) to (5) were evaluated with respect to the electrodeposited test plate.
(1) Coated surface smoothness Ra (center line average roughness) of the coated surface of the test plate was measured with a surface roughness meter (manufactured by Mitutoyo Corporation) and evaluated. When Ra is 0.15 μm or less, ◎, when 0.15 to 0.20 μm, ◯, when 0.20 to 0.25 μm, Δ, and when 0.25 μm or more, ×.
(2) Solvent resistance The coating film on the test plate was wiped with a solvent of ethanol / acetone (weight ratio 1/1).
(3) Salt spray resistance
It carried out according to JIS-Z-2731. A scratch reaching the substrate was put on the electrodeposited surface with a cutter knife, and the rust width after 480 hours was evaluated. The smaller the rust width, the better the performance.
(4) Salt water immersion test
After dipping the test plate in 50%, 5% saline for 480 hours, washing with water and air-drying, applying cellophane adhesive tape to the entire test surface so as not to contain air bubbles, and then peeling off the tape The ratio (%) of the coating film peeled area to the entire surface was measured. The smaller the peeled area, the better the performance.
(5) Combined cycle test The combined cycle tester was set to the following conditions, and scratches reaching the substrate were put on the electrodeposition coating surface with a cutter knife, and the rust width after the 20 cycle test was evaluated with 24 hours as one cycle. The smaller the rust width, the better the performance.
<Composite cycle test conditions>
Salt water spray (50 ° C 4 hours) → Forced drying (70 ° C 5 hours) → Wet (50 ° C 12 hours) → Forced drying (70 ° C 2 hours) → Natural drying (20-30 ° C 1 hour) or more as one cycle repeat.

[Evaluation results]
Tables 9 and 10 show the coating film performance evaluation results of Examples 1 to 9 and Comparative Examples 1 to 5.

  As can be seen from the results of Tables 9 and 10, in Examples 1 to 9 in which zinc oxide and zirconium hydroxide were used in combination, in Comparative Example 1 to 5 in the salt spray resistance test, the warm salt water immersion test, and the combined cycle test, The result is excellent rust prevention performance. Particularly in Examples 6 to 9 in which the polyol component is contained in at least one of (A) the base resin and (B) the curing agent resin, the combined cycle test shows even better results.

The cationic electrodeposition coating composition of the present invention is a conventional cationic electrodeposition coating composition containing a rust preventive pigment such as a lead compound or a chromium compound in the limit of rust prevention and rust prevention on an untreated steel sheet. Since the characteristics equivalent to or better than those using paint are achieved, it is useful for electrodeposition coating of automobile bodies, parts thereof, electric appliances and the like.

Claims (3)

  (A) Cationic amine-modified epoxy resin (base resin) obtained by cationizing an amine-modified epoxy resin obtained by reacting an amine with an epoxy resin, (B) Blocked polyisocyanate (curing agent resin), (C) Oxidation A cationic electrodeposition coating composition comprising zinc and (D) zirconium hydroxide.   (A) The epoxy resin of a cationic amine-modified epoxy resin (base resin) is an epoxy resin obtained by reacting a glycidyl ether of a polyol, a glycidyl ether of a dihydric phenol and a dihydric phenol. The cationic electrodeposition coating composition according to claim 1.   (B) The blocked polyisocyanate (curing agent resin) is a modified blocked polyisocyanate in which a part of the isocyanate groups of the polyisocyanate is linked with a polyol and the remaining isocyanate groups are blocked with a blocking agent. The cationic electrodeposition coating composition according to claim 1 or 2.