JP2008202122A - Method for forming cured electrodeposition coating film and method for forming multiple layer coating film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for forming a coating film, by which a coating film wherein the internal stress is low and the strain is small can be formed. <P>SOLUTION: A method for forming a cured electrodeposition coating film includes a process for immersing an object to be coated into a cation electrodeposition coating material composition and subjecting the object to be coated to electrodeposition coating to form an uncured coating film, and a process for baking and curing the obtained electrodeposition coating film. The cation electrodeposition coating material composition contains a pigment-dispersed paste containing (i) a pigment and (ii) a compound selected from a group comprising fatty acids, fatty acid derivatives, amine compounds, and mixtures of one or two or more kinds of these substances. The pigment (i) contains a black pigment, and the cation electrodeposition coating material composition has a black hue. The solid content in the cation electrodeposition coating material composition is 3-25 parts by weight per 100 parts by weight of the electrodeposition coating material composition, and the internal stress of the obtained cured electrodeposition coating film is 0.05-1.50 kg/mm<SP>2</SP>. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a cured electrodeposition coating film forming method and a multilayer coating film forming method capable of forming a coating film with low internal stress and less distortion.

  Cationic electrodeposition coating is a coating method performed by immersing an object to be coated as a cathode in a cationic electrodeposition coating composition and applying a voltage. In this method, even an object to be coated having a complicated shape can be applied to the details, and can be applied automatically and continuously. It has been widely put into practical use as an undercoating method for objects to be coated. Furthermore, electrodeposition coating can give high anticorrosive properties to the object to be coated, and is excellent in the protective effect of the object to be coated. The cationic electrodeposition coating composition is generally a coating composition containing an amine-modified epoxy resin and a blocked polyisocyanate curing agent.

  The electrodeposition coating film obtained by cationic electrodeposition coating as described above becomes a cured electrodeposition coating film by heating in the baking step. This is because the blocking agent of the block polyisocyanate curing agent is dissociated by heating to regenerate a free isocyanate group, and this isocyanate group reacts with an amine-modified epoxy resin or the like.

  Thus, dissociation of the blocking agent occurs during the heat curing of the electrodeposition coating film. Therefore, the volume of the cured electrodeposition coating film shrinks at least for the dissociated blocking agent. On the other hand, volume shrinkage does not occur in an object to be electrodeposited. For this reason, in the cured electrodeposition coating film, the portion in contact with the object to be coated undergoes volume shrinkage while the movement of the coating film is suppressed, thereby causing distortion in the entire cured coating film. Such distortion in the coating film is generally called internal stress of the coating film.

  On the other hand, the electrodeposition coating method includes anionic electrodeposition coating in addition to cationic electrodeposition coating. This anion electrodeposition coating is a coating method performed by immersing an object to be coated in an anion electrodeposition coating composition as an anode and applying a voltage. This method can be applied automatically and continuously to metals such as aluminum and stainless steel, and thus has been put to practical use in the coating of aluminum sashes and the like. This electrodeposition coating can impart high weather resistance to the printed material and is excellent in the protective effect of the coated material. An anionic electrodeposition coating composition is generally a coating composition containing an acrylic resin and a melamine curing agent or a blocked polyisocyanate curing agent.

  In the electrodeposition coating film obtained by anion electrodeposition coating as described above, the melamine curing agent or block polyisocyanate curing agent blocking agent is dissociated by heating at the time of heat curing, as in the case of cationic electrodeposition. Therefore, also in anionic electrodeposition coating, the volume of the dissociated blocking agent coating film shrinks and internal stress is generated.

  A coating film having a high internal stress is in a state where the distortion of the entire coating film is large, whereby the adhesion between the coating film and the object to be coated is lowered. Therefore, there is a problem that the coating film is easily peeled off due to an impact from the outside, and further, corrosion resistance, moisture resistance and the like are inferior.

Japanese Patent Laid-Open No. 6-340831 (Patent Document 1) discloses an article to be mixed with a steel material and an aluminum material, an alkaline earth metal, a metal silicate composed of zinc, a borate, a chromate, Cationic electricity containing at least one compound selected from molybdate, tungstate and tungstic acid, and having an internal stress of 10 to 50 kgf / cm ² (at a dry film thickness of 20 μm). A cationic electrodeposition coating method characterized by coating a coating material is described (claim 1). However, this method is different from the present invention in that the object to be coated is a mixture of steel material and aluminum material, and that the cationic electrodeposition coating composition used in this method contains a specific inorganic compound. Is different.

  Japanese Patent Application Laid-Open No. 2000-290542 (Patent Document 2) discloses a blocked isocyanate curable cationic electrodeposition coating composition containing a resin having a cationic charge and a blocked isocyanate, which is bismuth silicate (A), bismuth silicate molybdate ( B), bismuth hydroxide (C), and at least one compound selected from the group consisting of zirconium compounds (D), and a cationic electrodeposition coating composition characterized by not containing lead compounds and tin compounds A composition is described (claim 1). The fifth aspect of the invention describes a coating film having an internal stress of 0.5 to 5 MPa made of a cured product obtained by applying and curing a cationic electrodeposition coating composition. In this invention, although the method of setting the internal stress of the coating film within the above range is not specified, it can be judged from the description in the paragraph 0062 that it has been achieved by using an organic zinc compound and / or cuprous oxide. On the other hand, the present invention does not contain such an organic zinc compound and cuprous oxide as essential components.

  JP-A-2005-247992 (Patent Document 3) includes (a) a pigment settling inhibitor selected from the group consisting of fatty acids, fatty acid derivatives, amine compounds, and one or more mixtures thereof; (B) Electrodeposition coating compositions containing pigments are described. However, this invention differs from the present invention in that it does not touch on internal stress at all and is only a description relating to the excellent sedimentation stability of the coating composition.

JP-A-6-340831 JP 2000-290542 A JP-A-2005-247992

  The present invention solves the above-mentioned conventional problems, and an object thereof is to provide a coating film forming method capable of forming a coating film with low internal stress and less distortion.

The present invention
A step of immersing an object to be coated in a cationic electrodeposition coating composition to apply an uncured electrodeposition coating, and a step of baking and curing the obtained electrodeposition coating film,
A cured electrodeposition coating film forming method comprising:
This cationic electrodeposition coating composition is
(I) a pigment, and (ii) a compound selected from the group consisting of fatty acids, fatty acid derivatives, amine compounds and mixtures of one or more thereof,
A cationic electrodeposition coating composition comprising a pigment dispersion paste comprising
This (i) pigment contains a black pigment, the cationic electrodeposition coating composition has a black hue, and the solid content concentration of the cationic electrodeposition coating composition is 100 parts by weight of the electrodeposition coating composition. 3 to 25 parts by weight, and the internal stress of the obtained cured electrodeposition coating film is 0.05 to 1.50 kg / mm ² .
A method for forming a cured electrodeposition coating film is provided, whereby the above object is achieved.

The present invention also provides
A step of immersing an object to be coated in a cationic electrodeposition coating composition to apply an uncured electrodeposition coating, and a step of baking and curing the obtained electrodeposition coating film,
A cured electrodeposition coating film forming method comprising:
This cationic electrodeposition coating composition is
(I) a pigment, and (ii) a compound selected from the group consisting of fatty acids, fatty acid derivatives, amine compounds and mixtures of one or more thereof,
A cationic electrodeposition coating composition comprising a pigment dispersion paste comprising
This (i) pigment contains a black pigment and a white pigment, the cationic electrodeposition coating composition has a gray hue, and the solid content concentration of the cationic electrodeposition coating composition is 100 weights of the electrodeposition coating composition. 3 to 25 parts by weight with respect to parts, and the internal stress of the obtained cured electrodeposition coating film is 0.05 to 0.30 kg / mm ² ,
A method of forming a cured electrodeposition coating film is also provided.

The present invention further includes
A step of immersing an object to be coated in an anionic electrodeposition coating composition to perform uncured electrodeposition coating, and a step of baking and curing the obtained electrodeposition coating film.
A cured electrodeposition coating film forming method comprising:
This anion electrodeposition coating composition is
(I) a pigment, and (ii) a compound selected from the group consisting of fatty acids, fatty acid derivatives, amine compounds and mixtures of one or more thereof,
An anionic electrodeposition coating composition comprising a pigment dispersion paste comprising
This (i) pigment contains a white pigment and optionally a colored pigment, the anionic electrodeposition paint has a white hue, and the solid content concentration of the anion electrodeposition paint composition is the electrodeposition paint composition 3 to 25 parts by weight with respect to 100 parts by weight, and the internal stress of the obtained cured electrodeposition coating film is 0.05 to 4.00 kg / mm ² .
A method of forming a cured electrodeposition coating film is also provided.

  The fatty acid derivative is preferably a fatty acid ester, a fatty acid amide compound, or an ethylene oxide ring-opening adduct of a fatty acid ester or a fatty acid amide compound.

  The fatty acid preferably has 4 to 22 carbon atoms.

  Moreover, it is preferable that the said amine compound couple | bonds a C4-C22 alkyl group with a nitrogen atom.

  It is preferable that the said compound (ii) is contained in the quantity of 0.1-30 weight part with respect to 100 weight part of pigments.

  The solid content concentration of the electrodeposition coating composition is more preferably 3 to 10 parts by weight with respect to 100 parts by weight of the electrodeposition coating composition.

  The present invention further provides a cured electrodeposition coating film formed from the above cured electrodeposition coating film forming method.

The present invention further includes a step of forming a chemical conversion treatment film using a chemical conversion treatment agent before the step of cationic electrodeposition coating, comprising a multilayer coating film forming method,
This chemical conversion treatment agent is a chemical conversion treatment agent containing at least one (A) selected from the group consisting of zirconium, titanium and hafnium, fluorine (B), adhesion and corrosion resistance imparting agent (C),
The adhesion and corrosion resistance imparting agent (C) is the following (a) to (h):
At least one metal ion (a) selected from the group consisting of zinc, manganese, and cobalt ions,
Alkaline earth metal ions (b),
Group 13 element metal ions (c),
Copper ion (d),
Silicon-containing compound (e),
Polyamine water-soluble resin (f),
A water-soluble epoxy compound having an amino group (g), and
Silane coupling agent and / or its hydrolyzate (h):
Including at least one selected from the group consisting of
A method for forming a multilayer coating film is also provided.

  By the method of the present invention, it is possible to form a cured electrodeposition coating film having low internal stress and low distortion. In coating using an electrodeposition coating composition, volume shrinkage occurs during baking and curing. However, in the method of the present invention, it is possible to reduce the influence of this volume shrinkage, and thereby it is possible to form a cured electrodeposition coating film with low internal stress and low distortion. The cured electrodeposition coating film formed by the present invention has high adhesion to an object to be coated, and therefore, the coating film is hardly peeled off by an impact from the outside, and further has an advantage of excellent corrosion resistance, moisture resistance and the like. is doing.

  Moreover, in this invention, a multilayer coating film can also be formed by performing electrodeposition coating after processing a to-be-coated article using a specific chemical conversion treatment agent. The multilayer coating film thus formed is superior in the adhesion between the object to be coated and the coating film, has a merit that the peeling of the coating film due to impact is less likely to occur, and the corrosion resistance, moisture resistance, etc. are also superior. Yes.

Cationic electrodeposition coating composition The cationic electrodeposition coating composition used in the present invention contains a binder resin containing an amine-modified epoxy resin and a blocked polyisocyanate curing agent, a catalyst, and (i) a pigment and (ii) a fatty acid. And a pigment dispersion paste comprising a compound selected from the group consisting of a derivative of a fatty acid, an amine compound, and one or a mixture of two or more thereof. In the present specification, “fatty acid” and “derivative of fatty acid” are sometimes collectively referred to as “fatty acids”.

As the amine-modified epoxy resin, an amine-modified epoxy resin generally used in an electrodeposition coating composition can be used without particular limitation. As the amine-modified epoxy resin, an amine-modified epoxy resin known to those skilled in the art and a commercially available epoxy resin obtained by amine modification can be used.

  A preferred amine-modified epoxy resin is an amine-modified epoxy resin obtained by modifying an oxirane ring in the resin skeleton with an organic amine compound. In general, an amine-modified epoxy resin is produced by opening a ring of an oxirane ring in a starting material resin molecule with a primary amine, a secondary amine, a tertiary amine, and / or an amine such as an acid salt thereof. A typical example of the starting material resin is a polyphenol polyglycidyl ether type epoxy resin which is a reaction product of a polycyclic phenol compound such as bisphenol A, bisphenol F, bisphenol S, phenol novolak, cresol novolak and epichlorohydrin. Examples of other starting material resins include oxazolidone ring-containing epoxy resins described in JP-A-5-306327 and known. These epoxy resins are obtained by a reaction between a diisocyanate compound or a bisurethane compound obtained by blocking an NCO group of a diisocyanate compound with a lower alcohol such as methanol or ethanol, and epichlorohydrin.

  The starting material resin is used by extending the chain with a bifunctional polyester polyol, polyether polyol, bisphenol, dibasic carboxylic acid or the like, if necessary, before the oxirane ring-opening reaction with amines. be able to.

  In addition, prior to the oxirane ring-opening reaction with amines, 2-ethylhexanol, nonylphenol, ethylene glycol mono- acrylate for some oxirane rings for the purpose of adjusting molecular weight or amine equivalent, improving heat flow, etc. Monohydroxy compounds such as 2-ethylhexyl ether, ethylene glycol mono-n-butyl ether, propylene glycol mono-2-ethylhexyl ether can be added and used.

  Examples of amines that can be used for opening an oxirane ring and introducing an amino group include butylamine, octylamine, diethylamine, dibutylamine, methylbutylamine, monoethanolamine, diethanolamine, N-methylethanolamine , N-ethylethanolamine, triethylamine, N, N-dimethylbenzylamine, primary amines such as N, N-dimethylethanolamine, secondary amines or tertiary amines and / or their acid salts. Further, ketimine block primary amino group-containing secondary amine such as aminoethylethanolamine methyl isobutyl ketimine, diethylenetriamine diketimine can also be used. These amines must be reacted with at least an equivalent amount relative to the oxirane ring in order to open all the oxirane rings.

  The number average molecular weight of the amine-modified epoxy resin is preferably in the range of 1,500 to 5,000, more preferably in the range of 1,600 to 3,000. When the number average molecular weight is less than 1,500, physical properties such as solvent resistance and corrosion resistance of the cured coating film may be inferior. If it exceeds 5,000, the viscosity of the resin solution may be difficult to control and synthesis may be difficult, and handling such as emulsification and dispersion of the resulting resin may be difficult to handle. Furthermore, because of its high viscosity, the flowability during heating and curing is poor, and the appearance of the coating film may be impaired.

  The amine-modified epoxy resin is preferably molecularly designed so that the hydroxyl value is in the range of 50 to 250 mmol / 100 g. If the hydroxyl value is less than 50 mmol / 100 g, poor curing of the coating is caused. On the other hand, if it exceeds 250 mmol / 100 g, excessive hydroxyl groups remain in the coating film after curing, and as a result, the water resistance may decrease.

  The amine-modified epoxy resin is preferably molecularly designed so that the amine value is in the range of 40 to 150 mmol / 100 g. If the amine value is less than 40 mmol / 100 g, the emulsification dispersion failure in the aqueous medium due to the acid treatment described in detail below will be caused. Conversely, if the amine value exceeds 150 mmol / 100 g, excess amino groups will remain in the coating film after curing. The water resistance may decrease.

The block polyisocyanate curing agent cationic electrodeposition coating composition contains a block polyisocyanate curing agent obtained by blocking polyisocyanate with a blocking agent. Here, the polyisocyanate means a compound having two or more isocyanate groups in one molecule. The polyisocyanate may be, for example, any of aliphatic, alicyclic, aromatic and aromatic-aliphatic.

  Specific examples of polyisocyanates include aromatic diisocyanates such as tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), p-phenylene diisocyanate, and naphthalene diisocyanate; hexamethylene diisocyanate (HDI), 2,2,4- C3-C12 aliphatic diisocyanates such as trimethylhexane diisocyanate and lysine diisocyanate; 1,4-cyclohexane diisocyanate (CDI), isophorone diisocyanate (IPDI), 4,4′-dicyclohexylmethane diisocyanate (hydrogenated MDI) , Methylcyclohexane diisocyanate, isopropylidene dicyclohexyl-4,4'-diisocyanate, and 1,3-diisocyanatomethylcyclo Carbon such as xane (hydrogenated XDI), hydrogenated TDI, 2,5- or 2,6-bis (isocyanatomethyl) -bicyclo [2.2.1] heptane (also referred to as norbornane diisocyanate). Aliphatic diisocyanates having a number of 5 to 18; aliphatic diisocyanates having an aromatic ring such as xylylene diisocyanate (XDI) and tetramethylxylylene diisocyanate (TMXDI); modified products of these diisocyanates (urethanes, carbodiimides, Uretdione, uretoimine, burette and / or isocyanurate modified product); and the like. These may be used alone or in combination of two or more.

  Adducts or prepolymers obtained by reacting polyisocyanates with polyhydric alcohols such as ethylene glycol, propylene glycol, trimethylolpropane and hexanetriol at an NCO / OH ratio of 2 or more may also be used as the block polyisocyanate curing agent.

  Preferred specific examples of the aliphatic polyisocyanate or alicyclic polyisocyanate include hexamethylene diisocyanate, hydrogenated TDI, hydrogenated MDI, hydrogenated XDI, IPDI, norbornane diisocyanate, dimer (biuret) and trimer thereof. (Isocyanurate) etc. are mentioned.

  The blocking agent is added to a polyisocyanate group and is stable at ordinary temperature, but can regenerate a free isocyanate group when heated to a temperature higher than the dissociation temperature.

  As a blocking agent, when low temperature curing (160 ° C. or lower) is desired, lactam blocking agents such as ε-caprolactam, δ-valerolactam, γ-butyrolactam and β-propiolactam, and formaldoxime, acetoald It is preferable to use an oxime blocking agent such as oxime, acetoxime, methyl ethyl ketoxime, diacetyl monooxime, and cyclohexane oxime.

Pigment dispersion paste The cationic electrodeposition coating composition used in the present invention contains a pigment. In general, when a pigment is used as a component of an electrodeposition paint, the pigment is dispersed in an aqueous medium at a high concentration together with a resin called a pigment dispersion resin to make a paste. This is because the pigment is in a powder form, and it is difficult to disperse in a single step in a low concentration uniform state used in the electrodeposition coating composition. Such a paste is called a pigment dispersion paste. A pigment dispersion paste generally includes a pigment and a pigment dispersion resin. In the present invention, the pigment dispersion paste further includes (ii) a compound selected from the group consisting of fatty acids, fatty acid derivatives, amine compounds and one or a mixture of two or more thereof. To do.

Pigment (i)
The cationic electrodeposition coating composition of the present invention contains a commonly used pigment. As the pigment, an inorganic pigment, an organic pigment, carbon black, or a combination thereof is contained. Examples of inorganic pigments include, for example, colored pigments such as titanium oxide, iron oxide, calcined pigment, and bengara, extender pigments such as kaolin, talc, aluminum silicate, calcium carbonate, mica, clay, and silica, zinc phosphate, phosphoric acid Protection such as iron, aluminum phosphate, calcium phosphate, zinc phosphite, zinc cyanide, zinc oxide, aluminum tripolyphosphate, zinc molybdate, aluminum molybdate, calcium molybdate and aluminum phosphomolybdate, zinc phosphomolybdate Examples include rust pigments. Examples of organic pigments include phthalocyanine blue, phthalocyanine green, monoazo yellow, disazo yellow, benzimidazolone yellow, quinacridone red, monoazo red, boriazo red, and berylene red. These may be used alone or in combination of two or more.

  When the cationic electrodeposition coating composition used in the present invention has a black hue, black pigments such as carbon black, black iron oxide, and black fired pigment are used as the pigment. In addition to these black pigments, the above extender pigments and rust preventive pigments may be used in combination. In the present specification, the “black color” cationic electrodeposition coating composition is a coating composition obtained by using a cationic electrodeposition coating composition having a Munsell color system brightness of 1-2. Say. The Munsell color system is standardized as JIS Z 8721 (color display method using three attributes). The lightness of the Munsell color system is theoretically divided into 0 to 10 stages, where the smaller the value, the lower the lightness (more black), and the higher the value, the higher lightness (whiter). It shows that.

  In addition, when the cationic electrodeposition coating composition used in the present invention has a gray hue, the pigment includes black pigments such as carbon black, black iron oxide, and black fired pigment, and white pigments such as titanium oxide and zinc oxide. A pigment is used. In addition to these black pigments and white pigments, the above extender pigments and rust preventive pigments may be used in combination. In the present specification, the cationic electrodeposition coating composition having “gray hue” means a coating composition obtained by using a cationic electrodeposition coating composition having a Munsell color system lightness of 3 or more. Say.

  In the cationic electrodeposition coating composition of the present invention, extender pigments such as kaolin, talc, aluminum silicate, calcium carbonate, mica, clay and silica may be used in combination with the black pigment and / or the white pigment. Good. By using these extender pigments, it is possible to improve repellency prevention, chipping resistance, coating film hardness, corrosion resistance, adhesion, etc., and further improve rust prevention properties. A membrane can be obtained. In addition, for example, an anti-corrosion pigment such as aluminum phosphate or calcium molybdate may be used in combination, and by using these anti-corrosion pigments, the electrodeposition coating film having excellent coating film physical properties that has improved the rust prevention property of the coating film The cationic electrodeposition coating composition can be produced.

  The pigment is generally contained in the cationic electrodeposition coating composition in an amount that occupies a lower limit of 1% by weight and an upper limit of 60% by weight with respect to the total solid content of the cationic electrodeposition coating composition. The upper limit is preferably 30% by weight.

Compound (ii)
The cationic electrodeposition coating composition of the present invention comprises a compound (ii) selected from the group consisting of fatty acids, derivatives of fatty acids (both are referred to as fatty acids), amine compounds and one or a mixture of two or more thereof. ). In the present invention, by adding the compound (ii) to the electrodeposition coating composition, it is possible to reduce internal stress derived from volumetric shrinkage that occurs during baking hardening of the electrodeposition coating film. Thereby, distortion of a cured electrodeposition coating film can be made small and the adhesiveness of a coating film and a to-be-coated object can be improved.

  The fatty acids are fatty acids or derivatives thereof as described above. Examples of fatty acids include linear saturated fatty acids, branched saturated fatty acids, and unsaturated fatty acids. Examples of fatty acid derivatives include fatty acid esters obtained by modifying the above fatty acids with alcohol, polyhydric alcohols (glycerin, ethylene glycol, polyethylene glycol, etc.), fatty acid ethylene oxide adducts or fatty acid propylene oxide modified with ethylene oxide or propylene oxide. Adducts, fatty acid amide compounds modified with amine compounds, and polyfunctional fatty acids are included. These fatty acid esters or fatty acid amide compounds also include those obtained by ring-opening addition of ethylene oxide (ethylene oxide ring-opening adduct). These fatty acids contain chemical bonds such as unsaturated bonds, ether bonds and ester bonds, functional groups such as hydroxyl groups, amino groups and carbonyl groups, and heteroatoms such as oxygen, nitrogen, sulfur and halogen in the molecular skeleton. You may go out. Polyfunctional carboxylic acids and the like are also included in the fatty acid derivatives. As fatty acid derivatives, it is more preferable to use fatty acid esters, fatty acid amide compounds, and these ethylene oxide ring-opening adducts.

  The fatty acids used in the present invention are preferably fatty acids having 4 to 22 carbon atoms and derivatives thereof, more preferably fatty acids having 7 to 20 carbon atoms and derivatives thereof.

Specific fatty acids include, for example, the following compounds:
(1) Linear saturated fatty acid arachidic acid, tricosanoic acid, behenic acid, heneicosanoic acid, eicosanoic acid, nonadecanoic acid, stearic acid, heptadecanoic acid, palmitic acid, pentadecanoic acid, myristic acid, tridecanoic acid, lauric acid, capric acid, capryl Acid, octanoic acid, heptanoic acid, hexanoic acid, valeric acid, butyric acid, etc., refined stearic acid (450V, 550V, 700V), etc. manufactured by Kao Corporation;
(2) Branched saturated fatty acid isostearic acid, methyltetradecanoic acid, methylheptadecanoic acid, methyloctadecanoic acid, isovaleric acid and the like;
(3) unsaturated fatty acid oleic acid, ricinoleic acid, linoleic acid, linolenic acid, eleostearic acid, elaidic acid, palmitoleic acid, arachidonic acid, undecenoic acid, sorbic acid, crotonic acid and the like;
(4) Multifunctional carboxylic acid suberic acid, azelaic acid, sebacic acid, brassylic acid, phthalic acid, dodecanedioic acid, tetrahydrophthalic acid, hexahydrophthalic acid, tetrabromophthalic acid, tetrachlorophthalic acid, 3-tert-butyl Adipic acid, trimellitic acid, pyromellitic acid, etc .;
(5) Hetero atom-containing fatty acid hexyloxyacetic acid, dimethylolpropionic acid, dimethylolbutanoic acid, salicylic acid, benzoic acid, p-butoxybenzoic acid, N-acetylglycine, N-acetyl-β-alanine, thioctic acid and the like;
(6) Fatty acid ester (alcohol ester type)
Lion's Kadenax (GS-90, SO-80C), Kao's Rheodor (SP-L10, SP-P10, SP-S10V, SP-S30V, AS-10, AO-10, AO-15V), Kao Rheodor Super SP-L10 manufactured by Kao, Emazol manufactured by Kao Corporation (L-10 (F), P-10 (F), S-10V, O-10V), etc .;
(7) Fatty acid ester (ethylene glycol, polyethylene glycol ester type)
Lion Rionon (DT-600S, DEH-40), Asahi Denka Kogyo Adekaestor (OEG-102, OEG-106), etc .;
(8) Fatty acid methyl ester (ethylene oxide, propylene oxide addition system)
Lion Leo Fat (LA-110M-95, OC-0503M), Kao Emanon (1112,3199,3299,4110, CH-25, CH-40, CH-60 (K), CH-80), etc. (9) Fatty acid ethylene oxide adducts Lion's Esophat (O / 15, O / 20,60 / 15), Asahi Denka Kogyo's Adekaestor (TL-144, TL-161, TL-162, S-60, S-80, T-81, T-82), Kao Rheodor (TW-L120, TW-L106, TW-P120, TW-S120V, TW-S106, TW-S320V, TW-O120V, TW-O106V, TW-O320V, TW-IS399C, 430,440,460), Kao's Leodoll Super TW-L120, etc .;
(10) Fatty acid ester (glycerin ester type)
(11) Fatty acid amide compounds such as Kao's Exel T-95, VS-95, O-95R, 200, 300, 122V, P-40S) and Kao's Rheodor (MS-50, MS-60, MO-60, MS165V) A saturated fatty acid monoamide compound that is lauric acid amide, stearic acid amide, palmitic acid amide, caproic acid amide, caprylic acid amide, capric acid amide, myristic acid amide, stearic acid amide, behenic acid amide, hydroxystearic acid amide and the like;
(12) Unsaturated fatty acid monoamide oleic acid amide, erucic acid amide, ricinoleic acid amide, palmitic acid amide, behenic acid amide, brassinic acid amide, esylic acid amide, linoleic acid amide, linolenic acid amide, rice sugar Examples of these industrial products such as fatty acid amide and palm fatty acid amide include Kao wax (EB-G, EB-P, EB-FF, 85-P, 220, 230-2) manufactured by Kao Corporation, and fatty acid amide manufactured by Kao Corporation. S, T, ON, E), Adekasol YA manufactured by Asahi Denka Kogyo Co., Ltd. and the like;
(13) Saturated fatty acid bisamides that are fatty acid amide compounds, methylene bis-stearic acid amide, ethylene bis-capric acid amide, ethylene bis-lauric acid amide, ethylene bis-stearic acid amide, ethylene bis-isostearic acid amide, ethylene bis-hydroxystearic acid amide, ethylene Bisbehenic acid amide, hexamethylene bisstearic acid amide, hexamethylene bisbehenic acid amide, hexamethylene bishydroxystearic acid amide, N, N′-distearyl adipic acid amide, N, N′-distearyl sebacic acid amide, methylene Bispalmitic acid amide, ethylene bispalmitic acid amide, methylene bisbehenic acid amide, ethylene bisbehenic acid amide, hexaethylene bispalmitic acid amide, etc .;
(14) Unsaturated fatty acid bisamides that are fatty acid amide compounds, ethylene bisoleic acid amide, hexamethylene bisoleic acid amide, N, N′-dioleyl adipic acid amide, N, N′-dioleyl sebacic acid amide, and the like;
(15) Substituted amides which are fatty acid amide compounds N-stearyl stearic acid amide, N-oleyl oleic acid amide, N-stearyl oleic acid amide, N-oleyl stearic acid amide, N-stearyl erucic acid amide, N-oleyl palmitic acid Acid amides;
(16) Aromatic bisamides methylol stearic acid amides which are fatty acid amide compounds; methylol amides such as methylol behenic acid amide, N, N-distearylisophthalic acid amide, metaxylylene bis stearic acid amide;
(18) Branched amides which are fatty acid amide compounds N, N′-2-hydroxyethyl stearic acid amide, N, N′-ethylenebisoleic acid amide, N, N′-xylene bisstearic acid amide, N, N '-Dioleoyl adipic acid amide, N, N'-dioleyl sebacic acid amide, N, N'-distearyl isophthalic acid amide, etc .;
(19) Alkanolamides which are fatty acid amide compounds: coconut oil fatty acid monoethanolamide, lauric acid monoethanolamide, myristic acid monoethanolamide, oleic acid monoethanolamide, coconut oil fatty acid diethanolamide, lauric acid diethanolamide, myristic acid diethanolamide Industrial products such as lime, dioleamide, oleic acid diethanolamide, palm oil fatty acid monopropanolamide, lauric acid monopropanolamide, myristic acid monopropanolamide, oleic acid monopropanolamide, polyoxyalkylene alkanolamide ), Lion's armor slip (CP, E, EY), etc .;
However, it is not limited to these.

  The amine compound is preferably an amine compound in which an alkyl chain having 4 or more carbon atoms is bonded to a nitrogen atom. There may be one alkyl chain bonded to the nitrogen atom, or two or more alkyl chains may be bonded. As these amine compounds, any of primary, secondary and tertiary amines may be used. These amine compounds may have a plurality of amino groups in the skeleton, or the skeleton itself may be modified with ethylene oxide or the like. The amine compound used in the present invention preferably has 4 to 22 carbon atoms in the alkyl chain, more preferably 7 to 20 carbon atoms in the alkyl chain.

Specific examples of amine compounds include the following:
(1) Primary amine compound (1-1) Aliphatic mono- and polyamine compounds
n-butylamine, amylamine, n-hexylamine, heptylamine, n-octylamine, nonylamine, laurylamine, tetradecylamine, cetylamine, stearylamine, 2,4-butanediamine, 1,6-hexamethylenediamine, 1, Aliphatic primary amine compounds such as 8-octamethylenediamine,
(1-2) Alicyclic mono- and polyamine compounds cyclohexylamine, 1,3- and 1,4-diaminocyclohexane, 1,3- and 1,4-bis (aminomethyl) cyclohexane, 3-aminomethyl-3, Alicyclic primary amine compounds such as 5,5-trimethyl-1-aminocyclohexane, bis (4-aminocyclohexyl) methane, 1-methyl-2,4-diaminocyclohexane, 1-methyl-2,6-diaminocyclohexane Kind,
(1-3) Aromatic mono- and polyamine compounds aniline, meta and paratoluidine, naphthylamine, 1,3- and 1,4-phenylenediamine, 1-methyl-2,4-diaminobenzene, 1-methyl-2,6 -Aromatic primary amine compounds such as diaminobenzene, 2,4,-and 4,4, -diaminodiphenylmethane, 4,4, -diaminobiphenyl, 1,5- and 2,6-naphthalenediamine,
(1-4) Aralkyl mono and polyamine compounds
Aralkyl primary amine compounds such as 1,3- and 1,4-bis (aminomethyl) benzene, 1,5- and 2,6-bis (aminomethyl) naphthalene,
These industrial products include Lion's Armin CD, OD, TD, HT, 8D, 12D, 14D, 16D, 18D), Kao's Farmin (CS, 08D, 20D, 80, 86T, O, T), etc. Listed;
(2) Secondary amine compounds di-n-butylamine, diisoamylamine, dibenzylamine, methyldiethylethylenediamine, methylaniline, piperidine, 1,2,3,4-tetrahydroisoquinoline, 6-methoxy-1,2,3 Secondary amines such as, 4-tetrahydroisoquinoline, morpholine, N-methyl-glucamine, glucosamine, t-butylamine,
These industrial products include Kao's Farmin (D86) and the like;
(3) tertiary amine compounds such as tri (n-butyl) amine, tetramethylethylenediamine, 1-methylpiperidine, 1-methylpyrrolidine, 4-dimethylaminopyridine, triethylenediamine, bisdimethylaminoethyl ether, triisopropanolamine, etc. Grade amines,
These industrial products include Lion's Armin (DMMCD, DMTD, DMMHTD, DM12D, DM14D, DM16D, DM18D, DM22D, M2HT, M2O, M210D), Kao's Farmin (DM24C, DM0898, DM1098, DM2098, DM2465, DM2463) DM2458, DM4098, DM4662, DM6098, DM6875, DM8680, DM8098, DM2285, M2-2095, T-08) and the like;
(4) Alkanolamine Kao Aminone (PK-02S, L-02), etc .;
(5) Modified amine (5-1) Alkylamine ethylene oxide adduct Lion Esomin (C / 12, C / 15, C / 25, T / 12, T / 15, T / 25, S / 15, S / 25, O / 12, O / 17, O / 20, HT / 12, HT / 14, HT / 17), Lion esomide (HT / 15, HT / 60, O / 15), Asahi Denka Kogyo Co., Ltd. Made Adekasol (CO, COA, CMA, YA-6), Kao Amit (105,320);
However, it is not limited to these.

  These fatty acids and amine compounds may be used either alone or in combination of two or more.

  Although the mechanism of action by which the internal stress of the cured electrodeposition coating film is lowered by adding fatty acids or an amine compound is not clear, in the electrodeposition coating composition of the present invention, for example, the fatty acid is a monomolecular film with respect to the pigment. It is thought that the arrangement of such a structure or a structure like a bimolecular film is taken. And this structure arrangement | positioning relaxes the volume shrinkage at the time of baking hardening of an electrodeposition coating film, Therefore It is thought that the internal stress of a hardening electrodeposition coating film is reduced. The fatty acids or amine compounds used in the present invention have a high ability to be arranged in a structure such as a molecular film with respect to the pigment, so that it is considered that the internal stress can be effectively reduced.

Preparation of Pigment Dispersion Paste Pigment dispersion paste comprises (i) a pigment, (ii) a fatty acid, a derivative of fatty acid, an amine compound and a compound selected from the group consisting of one or more of them, and a pigment dispersion resin Can be prepared by dispersing in an aqueous medium.

  Examples of the pigment dispersion resin that can be used for the preparation of the pigment dispersion paste include a modified epoxy resin having a quaternary ammonium group, a primary amino group, and / or a tertiary sulfonium group.

  The modified epoxy resin having a quaternary ammonium group can be prepared by reacting an epoxy resin with a mixture of a tertiary amine and a neutralizing acid. Examples of the epoxy resin used for the preparation include polyglycidyl ether type epoxy resins such as bisphenol A, bisphenol F, bisphenol S, phenol novolac, and cresol novolac. These epoxy resins preferably have an epoxy equivalent of 180 to 1000. Moreover, as a tertiary amine, a C1-C6 thing is preferable. The tertiary amine may have a hydroxyl group.

  When the epoxy resin has a hydroxyl group, it may be a urethane-modified epoxy resin in which a blocked isocyanate group is introduced by reacting a half-blocked isocyanate and a hydroxyl group. Half-blocked isocyanate is prepared by partially blocking the polyisocyanate. As polyisocyanate, the above-mentioned polyisocyanate can be used. Examples of the blocking agent used for the preparation of the half-blocked isocyanate include lower aliphatic alkyl monoalcohols having 4 to 20 carbon atoms. The reaction between the epoxy resin and the half-blocked isocyanate is preferably carried out by maintaining at 140 ° C. for about 1 hour.

  There is no restriction | limiting in particular as a neutralizing acid used by mixing with a tertiary amine, Specifically, it is inorganic acid or organic acid like hydrochloric acid, nitric acid, phosphoric acid, formic acid, acetic acid, lactic acid, etc. The reaction between the neutralized salt of tertiary amine thus obtained and the epoxy resin can be carried out by a conventional method. For example, the epoxy resin is dissolved in a solvent such as ethylene glycol monobutyl ether, the resulting solution is heated to 60 to 100 ° C., and a neutralized acid salt of a tertiary amine is added dropwise to the acid value of 1. The reaction mixture is kept at 60-100 ° C. until

  The modified epoxy resin having a primary amino group can be prepared by using the above-described epoxy resin and a polyamine having a primary amino group and a secondary amino group. In addition, polyamine preliminarily ketiminates the primary amino group. The ketimine polyamine and the epoxy resin are reacted, and after the reaction, the ketimine block is removed to regenerate the primary amino group, and neutralize it to produce an ammonium salt of the primary amine. Examples of polyamine compounds that can be used include diethylenetriamine, aminoethylethanolamine, aminoethylpiperazine, and the like. These polyamines are reacted with ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone to form ketiminated polyamines. The reaction between the ketiminated polyamine and the epoxy resin can be carried out, for example, at 80 to 150 ° C. for 0.5 to 6 hours.

  The modified epoxy resin having a quaternary ammonium group or a primary amino group thus obtained may be used as a pigment dispersing resin, or these resins may be mixed and used at an appropriate ratio. .

  Furthermore, a modified epoxy resin having a quaternary ammonium group or a primary amino group or a mixture of these modified epoxy resins having a tertiary sulfonium group may be used for pigment dispersion. The modified epoxy resin having a tertiary sulfonium group can be prepared in the same manner as the modified epoxy resin having a quaternary ammonium group, except that a sulfide is used instead of a tertiary amine. From the viewpoint of pigment dispersibility, it is preferable to use a resin having a quaternary ammonium group for pigment dispersion.

  A pigment dispersion paste can be prepared by dispersing the thus obtained pigment dispersion resin, pigment (i), and compound (ii) in an aqueous medium. The pigment dispersion resin is preferably used in an amount of 20 to 40 parts by weight based on 100 parts by weight of the pigment (i). Moreover, it is preferable to use 0.1-30 weight part of compound (ii) with respect to 100 weight part of pigment (i).

  After mixing a predetermined amount of the pigment dispersion resin, the pigment (i), and the compound (ii), until the particle size of the pigment in the mixture reaches a predetermined uniform particle size, a usual mill such as a ball mill or a sand grind mill is used. A pigment dispersion paste can be obtained by dispersing using a dispersing device. In addition, when a cationic electrodeposition coating composition contains the following curing catalyst, you may add when creating this pigment dispersion paste.

Other ingredients
Curing Catalyst In the cationic electrodeposition coating composition of the present invention, a curing catalyst can be added to promote dissociation of the blocking agent of the blocked polyisocyanate curing agent. The curing catalyst used in the present invention is not particularly limited as long as it promotes dissociation of the blocking agent of the curing agent, and a typical catalyst includes a tin catalyst. Examples of the tin catalyst include solid catalysts such as dibutyltin oxide, dioctyltin oxide, monobutyltin oxide and mixtures thereof, liquid tin catalysts such as dibutyltin dilaurate, and mixtures thereof.

  The said curing catalyst is mix | blended in the quantity of 0.5-10 mass% with respect to the resin solid content in an electrodeposition coating material, Preferably it is 1-5 mass%.

Cationic acrylic resin The cationic electrodeposition coating composition of the present invention may contain a cationic acrylic resin as necessary. This is because by including the cationic acrylic resin, it is possible to prevent a decrease in oil repellency that may occur when the content of the inorganic pigment is low. The cationic acrylic resin can be prepared by a ring-opening addition reaction between an acrylic copolymer containing a plurality of oxirane rings in the molecule and an amine. Such acrylic polymers include (i) glycidyl (meth) acrylate and (ii) hydroxyl group-containing acrylic monomers such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, Plaxel FA and FM It is obtained by copolymerizing an addition reaction product of 2-hydroxyethyl (meth) acrylate and caprolactone known as a series with (iii) other acrylic and / or non-acrylic monomers. Examples of other acrylic and non-acrylic monomers are methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) ) Acrylate, t-butyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, styrene, vinyl ketone, α-methylstyrene, (meth) acrylonitrile, (meth) acrylamide, Such as vinyl acetate.

  This oxy ring-containing acrylic resin is composed of a primary amine, a secondary amine, or a tertiary amine acid salt in the same manner as when an oxirane ring of an epoxy resin is opened with an amine to introduce a cationic group. Ring-opening by the reaction with can be made a cationic acrylic resin.

  As another method, a cationic acrylic resin can be directly produced by copolymerizing an acrylic monomer having an amino group with another monomer. In this case, N, N-dimethylaminoethyl (meth) acrylate, N, N-di-t-butylaminoethyl (meth) instead of glycidyl (meth) acrylate previously used for the production of the oxirane ring-containing acrylic resin. Cationic acrylic resins are obtained directly by using acrylic monomers containing amino groups such as acrylates and copolymerizing them with acrylic monomers containing hydroxyl groups and other acrylic and / or non-acrylic monomers.

  The cationic acrylic resin is a conventional method so that the number average molecular weight of the polymer is in the range of 1,000 to 20,000, preferably 2,000 to 10,000, more preferably 5,000 to 10,000. Can be obtained by copolymerizing the monomers.

  When the cationic acrylic resin is used, the blending amount is preferably 10 to 100 parts by weight with respect to 100 parts by weight of the resin solid content in the electrodeposition paint.

Cationic electrodeposition coating composition The cationic electrodeposition coating composition of the present invention comprises an amine-modified epoxy resin and a block polyisocyanate curing agent dispersed in an aqueous medium (cationic main emulsion), a pigment dispersion paste, and deionized water. In addition, a cationic acrylic resin and a block polyisocyanate curing agent (sub-emulsion) dispersed in an aqueous medium as required can be prepared by mixing them at a predetermined ratio.

  As the aqueous medium, ion-exchanged water, pure water or the like can be used. The aqueous medium may contain a small amount of alcohols as required. The aqueous medium contains a neutralizing agent in order to improve the dispersibility of the amine-modified epoxy resin. Neutralizing agents are inorganic or organic acids such as hydrochloric acid, nitric acid, phosphoric acid, formic acid, acetic acid, lactic acid. The amount is that which achieves a neutralization rate of at least 20%, preferably 30-60%.

  The amount of the block polyisocyanate curing agent reacts with active hydrogen-containing functional groups such as primary, secondary or / and tertiary amino groups and hydroxyl groups in the amine-modified epoxy resin during curing to give a good cured coating film. In general, the weight ratio of amine-modified epoxy resin to block polyisocyanate curing agent is generally in the range of 90/10 to 50/50, preferably 80/20 to 65/35. The binder resin containing the amine-modified epoxy resin and the blocked polyisocyanate curing agent is generally an electrodeposition coating composition in an amount that occupies 25 to 85% by weight, preferably 40 to 70% by weight of the total solid content of the electrodeposition coating composition. Contained in the product.

  The electrodeposition paint can contain conventional paint additives such as water-miscible organic solvents, surfactants, antioxidants, and UV absorbers.

  In the cured electrodeposition coating film forming method of the present invention, a cationic electrodeposition coating composition having a solid content concentration of 3 to 25 parts by weight with respect to 100 parts by weight of the electrodeposition coating composition is used. When a cationic electrodeposition coating composition having such a solid content concentration is used, a cured electrodeposition coating film having low internal stress and less distortion is formed by including compound (ii). This makes it possible to obtain a cured electrodeposition coating film having excellent adhesion to an object to be coated.

  The solid content concentration of the cationic electrodeposition coating composition may be about 3 to 10 parts by weight with respect to 100 parts by weight of the electrodeposition coating composition. Such a cationic electrodeposition coating composition is generally referred to as a low solid content cationic electrodeposition coating composition. Such a low solid content type cationic electrodeposition coating composition has the advantage that no precipitate is formed or the amount of the precipitate is small. Electrodeposition baths used for electrodeposition coating are large-scale equipment that can immerse large objects such as automobile bodies, so the energy required for circulation and agitation, equipment related to it, and maintenance of that equipment The cost of this will be enormous. Such circulation, agitation, and the reduction or elimination of these devices greatly contribute to energy saving in electrodeposition coating. For this reason, it is required that the electrodeposition coating composition does not cause sediment or has little sediment. In this case, by using the low solid content type cationic electrodeposition coating composition, it is possible to reduce or eliminate the circulation, stirring, and these devices in the electrodeposition tank. In particular, it is more preferable to use such a low solid content type cationic electrodeposition coating composition in an electrodeposition coating composition having a gray hue.

Method of forming cured electrodeposition coating film The electrodeposition coating composition of the present invention is electrodeposited onto an article to be coated by a method well known to those skilled in the art to form a cured coating film. It is preferable that a surface treatment such as a chemical conversion treatment is performed in advance on an object to be coated when this cationic electrodeposition coating composition is used for electrodeposition coating. Examples of the object to be coated include cold-rolled steel sheet, hot-rolled steel sheet, stainless steel, electrogalvanized steel sheet, hot-dip galvanized steel sheet, zinc-aluminum alloy-based steel sheet, zinc-iron alloy-based steel sheet, zinc-magnesium alloy-based steel sheet. Steel materials such as zinc-aluminum-magnesium alloy plated steel plate, aluminum-based plated steel plate, aluminum-silicon alloy-plated steel plate, tin-based plated steel plate, lead-tin alloy-plated steel plate, chromium-based plated steel plate, and these steel plates Steel material that has been subjected to chemical conversion treatment, and the like.

  In electrodeposition coating, an uncured electrodeposition coating film is formed by immersing an object to be coated in a cationic electrodeposition coating composition as a cathode and then applying a voltage between the anode and depositing a film. The The time for applying the voltage varies depending on the electrodeposition conditions, but can generally be 2 to 4 minutes.

  The film thickness of the electrodeposition coating film is preferably 5 to 25 μm as a dry film thickness, and more preferably about 20 μm. If the film thickness is less than 5 μm, the rust prevention property may be insufficient, and if it exceeds 25 μm, the paint may be wasted.

  The electrodeposition coating film obtained as described above is cured or electrodeposited by baking at 120 to 260 ° C., preferably 140 to 220 ° C. for 10 to 30 minutes after completion of the electrodeposition process or after washing with water. A coating film is formed.

When the coating film obtained from the cationic electrodeposition coating composition used in the present invention has a black hue, the internal stress of the obtained cured electrodeposition coating film is 0.05 to 1.50 kg / mm ^2. Condition. When the internal stress of the cured electrodeposition coating film exceeds 1.50 kg / mm ² , the adhesion between the article to be coated and the cured electrodeposition coating film becomes low, and the coating film is easily peeled off due to impact. Furthermore, it will be inferior to corrosion resistance and moisture resistance.

  In the present invention, by preparing an electrodeposition coating composition using a pigment dispersion paste containing compound (ii), the internal stress of the cured electrodeposition coating film can be controlled within the above range. The internal stress of the cured electrodeposition coating film can be measured using an analytical instrument such as a stress analyzer.

When the coating film obtained from the cationic electrodeposition coating composition used in the present invention has a gray hue, the internal stress of the cured electrodeposition coating film obtained is 0.05 to 0.30 kg / mm ^2. preferable. When the internal stress of the cured electrodeposition coating film exceeds 0.30 kg / mm ² in the gray electrodeposition coating composition, the adhesion between the article to be coated and the cured electrodeposition coating film may be lowered.

  As a reason why the internal stress of the cationic electrodeposition coating composition having a gray hue is lower than the internal stress of the cationic electrodeposition coating composition having a black hue, white pigments such as titanium oxide are so-called hard particles. This is considered to be because it has a function of filling the space derived from the dissociated blocking agent in the coating film, thereby suppressing the shrinkage of the coating film.

Anionic electrodeposition coating composition The electrodeposition coating composition used in the method of the present invention may be an anionic electrodeposition coating composition. Hereinafter, the anionic case will be described.

  The anionic electrodeposition coating composition of the present invention can be formed by replacing the cationic resins of the cationic electrodeposition coating composition with anionic. Hereinafter, only parts different from the cationic electrodeposition coating composition will be described.

In the anionic resin anionic electrodeposition coating composition, an anionic resin is used instead of the cationic resin. As the anionic resin used in the present invention, a resin having a carboxyl group and optionally further a hydroxyl group, which is well known in the field of electrodeposition coating, can be used. As the anionic resin, for example, an acrylic resin having a carboxyl group or a polyurethane resin having a carboxyl group is preferably used, and an acrylic resin having a carboxyl group and a hydroxyl group or a polyurethane resin having a carboxyl group and a hydroxyl group is particularly preferably used. This is because the coating film is excellent in weather resistance and smoothness.

  Examples of the acrylic resin having a carboxyl group and a hydroxyl group include, for example, a carboxyl group-containing unsaturated monomer, a hydroxyl group-containing acrylic monomer, and, if necessary, other polymerizable monomers. A copolymer obtained by radical polymerization of a monomer can be used.

  The carboxyl group-containing unsaturated monomer is a compound having at least one carboxyl group and polymerizable unsaturated bond in one molecule, for example, (meth) acrylic acid, itaconic acid, maleic acid, caprolactone-modified carboxyl group Examples thereof include (meth) acrylic monomers.

  A hydroxyl group-containing acrylic monomer is a compound having at least one hydroxyl group and a polymerizable unsaturated bond in one molecule. For example, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meta ) Hydroxyalkyl (meth) acrylates such as acrylates; (poly) ethylene glycol mono (meth) acrylates, (poly) alkylene glycol mono (meth) acrylates such as (poly) propylene glycol mono (meth) acrylates; Monomers and β-propiolactone, dimethylpropiolactone, butyrolactone, γ-valerolactone, γ-caprolactone, γ-caprolactone, γ-laurolactone, ε-caprolactone, δ-caprolactone, etc. Examples of commercially available products include Plaxel FM1 (trade name, caprolactone-modified (meth) acrylic acid hydroxyesters), Plaxel FM2 (same as left), and Placcel FM3 (same as left). ), Plaxel FA1 (same as left), Plaxel FA2 (same as left), Plaxel FA3 (same as left), and the like.

The other polymerizable monomer is a compound having at least one polymerizable unsaturated bond in one molecule other than the above carboxyl group-containing unsaturated monomer and hydroxyl group-containing acrylic monomer, For example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, hexyl (meth) acrylate, octyl (meth) acrylate, lauryl (meth) acrylate , (meth) alkyl or cycloalkyl esters of C ₁ -C ₁₈ (meth) acrylic acid such as cyclohexyl acrylate; styrene, alpha-methyl styrene, aromatic polymerizable monomers such as vinyl toluene; (meth) acrylic (Meth) acrylamido such as acid amide, N-butoxymethyl (meth) acrylamide, N-methylol (meth) acrylamide And derivatives thereof; (meth) acrylonitrile compounds; γ- (meth) acryloxypropyltrimethoxysilane, γ- (meth) acryloxypropylmethyldimethoxysilane, γ- (meth) acryloxypropyltriethoxysilane, vinyltrimethoxy Examples include alkoxysilyl group-containing polymerizable monomers such as silane.

  As a blending ratio of these monomers, it is preferable to use the carboxyl group-containing unsaturated monomer within the range of 3 to 30% by weight, particularly 4 to 20% by weight, based on the total weight of the monomers. The hydroxyl group-containing acrylic monomer is preferably used in the range of 3 to 40% by weight, particularly 5 to 30% by weight, based on the total weight of the monomers.

  A conventionally known solution polymerization method or the like can be adopted as a method for radically copolymerizing these monomers.

  Examples of the polyurethane resin having a carboxyl group and a hydroxyl group include those obtained by subjecting a polyisocyanate compound, polyols and dihydroxycarboxylic acid to a urethanization reaction by an equivalent ratio of excess hydroxyl group by a one-shot method or a multistage method. It is done.

  The polyisocyanate compound is a compound having two or more isocyanate groups in one molecule, and examples thereof include aliphatic diisocyanates such as hexamethylene diisocyanate, trimethylhexane diisocyanate, and lysine diisocyanate; cyclohexane diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, and methylcyclohexyl. An alicyclic diisocyanate such as silylene diisocyanate is preferably used.

  Polyols are compounds having two or more hydroxyl groups in one molecule, for example, polymerization or copolymerization (blocking) of alkylene oxide (ethylene oxide, propylene oxide, butylene oxide, etc.) and / or heterocyclic ether (tetrahydrofuran). Or random) polyether diols obtained by, for example, polyethylene glycol, polypropylene glycol, polyethylene-propylene (block or random) glycol, polytetramethylene ether glycol, polyhexamethylene ether glycol, polyoctamethylene ether glycol, etc .; dicarboxylic acid (Adipic acid, succinic acid, sebacic acid, glutaric acid, maleic acid, fumaric acid, phthalic acid, etc.) and glycol (ethylene glycol, propylene glycol, Diol, hexanediol, neopentyl glycol, bishydroxymethylcyclohexane and the like) polyester diols obtained by condensation polymerization such as polyethylene adipate, polybutylene adipate, polyhexamethylene adipate, polyneopentyl adipate, polyethylene-butylene adipate, Examples include polyneopentyl-hexyl adipate and the like; polylactone diols such as polycaprolactone diol and poly-3-methylvalerolactone diol; polycarbonate diols; a mixture of two or more selected from these. These polyols can generally have a number average molecular weight in the range of 500 or more, preferably 500 to 5000, more preferably 1000 to 3000.

  As the polyols, low molecular weight polyols having two or more hydroxyl groups in one molecule and having a number average molecular weight of less than 500 can also be used. Specifically, glycols and their alkylene oxide low molar adducts (molecular weight less than 500) mentioned above as raw materials for polyester diols; trihydric alcohols such as glycerin, trimethylolethane, trimethylolpropane and the like and their low alkylene oxides. Mole adduct (molecular weight less than 500); a mixture of two or more selected from these, and the like.

  In a system in which a polyol having a number average molecular weight of 500 or more and a low molecular weight polyol having a number average molecular weight of less than 500 are used in combination, the composition ratio of these two polyols is 80 based on the total amount of both polyols. ˜99.9% by weight, in particular 90 to 99.5% by weight, the latter being preferably in the range of 20 to 0.1% by weight, in particular 10 to 0.5% by weight.

  Dihydroxycarboxylic acid is a compound having two hydroxyl groups and one carboxyl group in one molecule, and examples thereof include dimethylolacetic acid, dimethylolpropionic acid, dimethylolbutyric acid, and dimethylolbutanoic acid.

  The urethanation reaction with the polyisocyanate compound, polyols and dihydroxycarboxylic acid described above can be carried out by a method known per se.

In the curing agent anionic electrodeposition coating composition, examples of the curing agent for the anionic resin include melamine resin and block polyisocyanate.

As the melamine resin, ether in which part or all of the methylol group of methylolmelamine obtained by reacting melamine with formaldehyde or the like is modified with one or more alcohols selected from C _{1 to} C ₁₀ monoalcohols. A melamine resin can be used. The melamine resin may contain an imino group, a methylol group, or other functional groups.

  As the block polyisocyanate, the block polyisocyanate curing agent exemplified in the above cationic electrodeposition coating composition can be used.

(I) Pigment and (ii) Compound (i) The pigment and (ii) compound used in the anion electrodeposition coating composition are the same as those in the cationic electrodeposition coating composition. In addition, when the anion electrodeposition coating composition used by this invention has a white hue, white type | system | groups, such as a titanium oxide and a zinc oxide, are used as a pigment. In addition to these, a small amount of a yellow pigment or a blue or red pigment may be used. Further, the extender pigment, the rust preventive pigment and the like may be used in combination as in the cationic electrodeposition coating composition.

When the anionic pigment-dispersed paste electrodeposition paint contains a pigment, it is preferable to prepare the pigment in the form of a pigment-dispersed paste from the viewpoint of easy dispersion of the pigment. An anionic pigment dispersion paste can be prepared by dispersing a pigment in an anionic pigment dispersion resin. As the pigment, the pigments exemplified in the above cationic electrodeposition coating composition can be used.

  For example, a modified acrylic resin having an acrylic ester, acrylic acid and an azonitrile compound can be used as the anionic pigment dispersion resin. As the aqueous medium, the above-mentioned aqueous medium, for example, ion exchange water or the like is used.

  An anionic pigment dispersion paste can be prepared by adding the above-mentioned anionic pigment dispersion resin, a pigment and a neutralizing agent, and dispersing or dissolving them.

  Generally, the anionic pigment dispersion paste is prepared to a solid content of 35 to 70% by weight, preferably 40 to 65% by weight.

  An anionic pigment dispersion paste is prepared by mixing an anionic pigment dispersion resin and a pigment, and, if necessary, a neutralizing agent such as triethylamine and an aqueous medium, and then the pigment in the mixture has a predetermined uniform particle size. Until it becomes, it can disperse | distribute and obtain using normal dispersion apparatuses, such as a ball mill and a sand grind mill.

Preparation of anionic electrodeposition coating composition The anionic electrodeposition coating composition of the present invention is prepared by dispersing the above-mentioned anionic resin and anionic pigment dispersion paste in an aqueous medium. Usually, the aqueous medium contains a neutralized base (amine or alkali compound) in order to neutralize the anionic resin and improve the dispersibility. Specifically, the amine used as the neutralizing base has a low molecular weight with 3 or less carbon atoms, and is different from the compound (ii) described above. When the number of carbon atoms is such, the interaction with the resin becomes larger than the interaction with the pigment, so that the effect as the compound (ii) is lost. Examples of neutralizing bases include ammonia; diethylamine, ethylethanolamine, diethanolamine, monoethanolamine, monopropanolamine, isopropanolamine, ethylaminoethylamine, hydroxyethylamine, diethylenetriamine and other organic amines; sodium hydroxide, potassium hydroxide, etc. Basic compounds such as alkali metal hydroxides. The aqueous medium is water or a mixture of water and the above organic solvent. It is preferable to use ion exchange water as water.

  In the preparation of the anionic electrodeposition coating composition of the present invention, the compound (ii) can be added at any dispersion / mixing stage. Compound (ii) is preferably added to the above anionic pigment dispersion paste and then mixed with other components such as an anionic main emulsion. In addition, the compounding quantity of a fatty acid or an amine compound is the same as the case of a cationic electrodeposition coating composition.

  The amount of the curing agent is generally 90/10 to 50/50, preferably in the range of 80/20 to 50/50, expressed as a solid weight ratio (anionic resin / curing agent) between the anionic resin and the curing agent. is there. The amount of neutralizing base is that which is sufficient to neutralize at least 30%, preferably 50-120% of the anionic groups of the anionic resin.

  In the cured electrodeposition coating film forming method of the present invention, an anionic electrodeposition coating composition having a solid content concentration of 3 to 25 parts by weight with respect to 100 parts by weight of the electrodeposition coating composition is used. In the case of using an anionic electrodeposition coating composition having such a solid content concentration, a cured electrodeposition coating film having low internal stress and less distortion is formed by including compound (ii). This makes it possible to obtain a cured electrodeposition coating film having excellent adhesion to an object to be coated.

  The solid content concentration of the anion electrodeposition coating composition may be about 3 to 10 parts by weight with respect to 100 parts by weight of the electrodeposition coating composition. Such an anionic electrodeposition coating composition is generally referred to as a low solid content type anionic electrodeposition coating composition. Such a low solid content type anionic electrodeposition coating composition is an electrodeposition coating composition that does not cause precipitation or has little precipitation. Even in anionic electrodeposition coating, the electrodeposition bath used for electrodeposition coating is a large-scale facility that can immerse large objects such as aluminum sashes. The cost of equipment and maintenance of the equipment is enormous. Such circulation, agitation, and the reduction or elimination of these devices greatly contribute to energy saving in electrodeposition coating. For this reason, it is required that the electrodeposition coating composition does not cause sediment or has little sediment. In this case, by using the low solid content type anion electrodeposition coating composition, it is possible to reduce or eliminate the circulation, stirring and these devices in the electrodeposition tank. In particular, it is more preferable to use such a low solid content type anionic electrodeposition coating composition in an electrodeposition coating composition having a white hue.

Method of forming cured electrodeposition coating film The electrodeposition coating composition of the present invention is electrodeposited onto an article to be coated by a method well known to those skilled in the art to form a cured coating film. The electrodeposition coating of the anion electrodeposition coating composition is usually performed by applying a voltage of 1 to 400 V between the object to be coated as the anode and the cathode. During electrodeposition coating, the bath temperature of the coating composition is adjusted to 10 to 45 ° C, preferably 15 to 30 ° C, and pH is adjusted to 6.0 to 9.0, preferably 7.0 to 8.0.

  The electrodeposition process includes a process of immersing a coating object in the anionic electrodeposition coating composition, and a process of depositing a film by applying a voltage between the coating object as an anode and a cathode. Moreover, although the voltage application time varies depending on the electrodeposition conditions, it can generally be set to 30 seconds to 5 minutes. After completion of the electrodeposition process, the cured coating film is obtained by baking at 100 to 200 ° C., preferably 120 to 180 ° C., for 10 to 60 minutes as it is or after washing with water.

  The obtained film thickness is preferably 5 to 30 μm, particularly 7 to 20 μm, as a cured coating film.

When the coating film obtained from the anion electrodeposition coating composition used in the present invention has a white hue, the internal stress of the obtained cured electrodeposition coating film is 0.05 to 4.00 kg / mm ^2. Condition. When the internal stress of the cured electrodeposition coating exceeds 4.00 kg / mm ² , the adhesion between the article to be coated and the cured electrodeposition coating is lowered, and the coating is easily peeled off by impact. Furthermore, it will be inferior to corrosion resistance and moisture resistance. In the present invention, by preparing an electrodeposition coating composition using a pigment dispersion paste containing compound (ii), the internal stress of the cured electrodeposition coating film can be controlled within the above range. The reason why the upper limit of the internal stress value of the cured electrodeposition coating film is high in the case of using the anion electrodeposition coating composition is that the anionic resin contained in the anion electrodeposition coating composition is a cationic electrodeposition coating composition. This is probably because the adhesion performance with the object to be coated is higher than that of the amine-modified epoxy resin contained therein.

Multilayer coating film forming method In the present invention, it is more preferable to form a chemical conversion treatment film on an object to be coated using a chemical conversion treatment agent, particularly before performing electrodeposition coating using a cationic electrodeposition coating composition. By forming a chemical conversion treatment film in advance on the object to be electrodeposited according to the present invention, the adhesion of the obtained cured electrodeposition coating film to the object to be coated can be further improved.

The chemical conversion treatment agent that can be used in the present invention is:
A chemical conversion treatment agent containing at least one selected from the group consisting of zirconium, titanium and hafnium (A), fluorine (B), adhesion and corrosion resistance imparting agent (C),
The adhesion and corrosion resistance imparting agent (C) are the following (a) to (h):
At least one metal ion (a) selected from the group consisting of zinc, manganese, and cobalt ions,
Alkaline earth metal ions (b),
Group 13 element metal ions (c),
Copper ion (d),
Silicon-containing compound (e),
Polyamine water-soluble resin (f),
A water-soluble epoxy compound having an amino group (g), and
Silane coupling agent and / or its hydrolyzate (h):
Including at least one selected from the group consisting of
Chemical conversion treatment agent. This chemical conversion treatment agent is characterized by substantially not containing phosphate ions or harmful heavy metal ions.

At least one selected from the group consisting of zirconium, titanium and hafnium (A)
At least one (A) selected from the group consisting of zirconium, titanium and hafnium contained in the chemical conversion treatment agent is a chemical conversion treatment film forming component. A chemical conversion treatment film containing at least one (A) selected from the group consisting of zirconium, titanium, and hafnium is formed on the object to be coated, thereby improving the corrosion resistance and wear resistance of the object to be coated. Adhesiveness with the coating film formed can be improved.

The zirconium source is not particularly limited, and examples thereof include alkali metal fluorozirconates such as K ₂ ZrF ₆ ; fluorozirconates such as (NH ₄ ) ₂ ZrF ₆ ; fluorozirconate acids such as H ₂ ZrF _6, etc. And soluble fluorozirconate, etc .; zirconium fluoride; zirconium oxide and the like.

The titanium source is not particularly limited. For example, alkali metal fluorotitanate, fluorotitanate such as (NH ₄ ) ₂ TiF ₆ ; soluble fluorotitanate such as fluorotitanate such as H ₂ TiF _6, etc .; titanium fluoride A titanium oxide can be mentioned.

The source of hafnium is not particularly limited, and examples thereof include fluorohafnate acids such as H ₂ HfF ₆ ; hafnium fluoride. The supply source of at least one (A) selected from the group consisting of zirconium, titanium, and hafnium is selected from the group consisting of ZrF ₆ ²⁻ , TiF ₆ ²⁻ , and HfF ₆ ²⁻ because of its high film forming ability. Preferred is a compound having at least one of the following.

  The content of at least one (A) selected from the group consisting of zirconium, titanium and hafnium contained in the chemical conversion treatment agent is preferably in the range of a lower limit of 20 ppm and an upper limit of 10,000 ppm in terms of metal. If it is less than the lower limit, the resulting chemical conversion film has insufficient performance, and if it exceeds the upper limit, no further effect can be expected, which is economically disadvantageous. The lower limit is more preferably 50 ppm, and the upper limit is more preferably 2000 ppm.

Fluorine (B)
Fluorine (B) contained in the chemical conversion treatment agent plays a role as an etching agent for the object to be coated. The fluorine supply source is not particularly limited, and examples thereof include fluorides such as hydrofluoric acid, ammonium fluoride, fluorinated boronic acid, ammonium hydrogen fluoride, sodium fluoride, and sodium hydrogen fluoride. . Examples of the complex fluoride include hexafluorosilicate, and specific examples thereof include hydrofluoric acid, zinc silicofluoride, manganese silicofluoride, magnesium silicofluoride, and hydrosilicofluoride. Examples thereof include nickel, iron silicohydrofluorate, and calcium silicohydrofluoride.

Adhesion and corrosion resistance imparting agent (C)
The chemical conversion treatment agent that can be used in the present invention further contains an adhesion and corrosion resistance imparting agent (C). In the present invention, the adhesion and corrosion resistance-imparting agent (C) contains at least one selected from the group consisting of the following (a) to (h). By adding the adhesion and corrosion resistance imparting agent (C), the stability of the chemical conversion treatment film and the adhesion of the coating film are improved, and the iron-based base material that has been unsuitable for the treatment with the conventional surface treatment agent comprising a zirconium compound. In contrast, an excellent chemical conversion treatment film can be formed.

  At least one metal ion (a) selected from the group consisting of the zinc ion, manganese ion, and cobalt ion is a metal ion having a divalent or trivalent valence, respectively. Among the above ions, zinc ions are preferable. The content of the chemical conversion treatment agent is preferably in the range of a lower limit of 1 ppm and an upper limit of 5000 ppm. If it is less than 1 ppm, the corrosion resistance of the resulting chemical conversion film is lowered, which is not preferable. If it exceeds 5000 ppm, further improvement of the effect is not observed, which is economically disadvantageous, and the adhesion after coating may be lowered. The lower limit is more preferably 20 ppm, and the upper limit is more preferably 2000 ppm.

  The alkaline earth metal ion (b) is not particularly limited, and examples thereof include magnesium ion, calcium ion, barium ion, strontium ion, etc. Among them, magnesium ion is preferable. The content of the alkaline earth metal ion is preferably in the range of a lower limit of 1 ppm and an upper limit of 5000 ppm. If it is less than 1 ppm, the corrosion resistance of the resulting chemical conversion film is lowered, which is not preferable. If it exceeds 5000 ppm, further improvement of the effect is not observed, which is economically disadvantageous, and the adhesion after coating may be lowered. The lower limit is more preferably 20 ppm, and the upper limit is more preferably 2000 ppm.

  Examples of the group 13 element metal ions (c) include aluminum ions, gallium ions, and indium ions. Among them, aluminum ions are preferable. The content of the metal ions of the group 13 element in the periodic table is preferably in the range of a lower limit of 1 ppm and an upper limit of 5000 ppm. If it is less than 2 ppm, the corrosion resistance of the resulting chemical conversion film is lowered, which is not preferable. If it exceeds 1000 ppm, further improvement of the effect is not seen, which is economically disadvantageous, and the adhesion after coating may be lowered. The lower limit is more preferably 5 ppm, and the upper limit is more preferably 2000 ppm.

  The content of the copper ion (d) is preferably in the range of a lower limit of 0.5 ppm and an upper limit of 100 ppm. If it is less than 0.5 ppm, the corrosion resistance of the resulting chemical conversion film is lowered, which is not preferable. When it exceeds 100 ppm, there is a possibility that a negative effect is brought about on the zinc-based substrate and the aluminum-based substrate. The lower limit is more preferably 2 ppm, and the upper limit is more preferably 50 ppm. In particular, the copper ion has a high effect of stabilizing the chemical conversion treatment film by displacement plating on the surface of the object to be coated, so that it is estimated that a high effect can be obtained in a small amount as compared with other components.

  The supply source of each of the components (a), (b), (c), and (d) is not particularly limited. For example, it is blended in the chemical conversion treatment agent as nitrate, sulfate, or fluoride. Can do. Of these, nitrate is preferable because it does not adversely affect the chemical reaction.

  The silicon-containing compound (e) is not particularly limited, and examples thereof include silica such as water-dispersible silica, water-soluble silicate compounds such as sodium silicate, potassium silicate and lithium silicate, silicate esters, diethyl Examples thereof include alkyl silicates such as silicate. Among these, silica is preferable because it has an effect of improving the barrier property of the chemical conversion treatment film, and water-dispersible silica is more preferable because of its high dispersibility in the chemical conversion treatment agent. The water-dispersible silica is not particularly limited, and examples thereof include spherical silica, chain silica, and aluminum-modified silica that are low in impurities such as sodium. The spherical silica is not particularly limited. For example, “Snowtex N”, “Snowtex O”, “Snowtex OXS”, “Snowtex UP”, “Snowtex XS”, “Snowtex AK”, “Snow” Examples include colloidal silica such as Tex OUP, Snowtex C, and Snowtex OL (all manufactured by Nissan Chemical Industries, Ltd.) and fumed silica such as Aerosil (produced by Nippon Aerosil Co., Ltd.). Can do. The chain silica is not particularly limited, and examples thereof include silica sols such as “Snowtex PS-M”, “Snowtex PS-MO”, and “Snowtex PS-SO” (all manufactured by Nissan Chemical Industries, Ltd.) Can be mentioned. Examples of the aluminum-modified silica include commercially available silica sols such as “Adelite AT-20A” (manufactured by Asahi Denka Kogyo Co., Ltd.). Although the said silicon containing compound may be used independently, when using it in combination with the metal ion of (a)-(d) mentioned above, the outstanding effect is exhibited.

  The content of the silicon-containing compound (e) is preferably in the range of a lower limit of 1 ppm and an upper limit of 5000 ppm as a silicon component. If it is less than 1 ppm, the corrosion resistance of the resulting chemical conversion film is lowered, which is not preferable. If it exceeds 5000 ppm, further improvement of the effect is not observed, which is economically disadvantageous, and the adhesion after coating may be lowered. The lower limit is more preferably 5 ppm, and the upper limit is more preferably 2000 ppm. In addition, it is thought that the adhesiveness imparting components (a) to (e) have an effect of imparting corrosion resistance at the same time.

  The polyamine water-soluble resin (f) has the following formula (1):

And / or the following formula (2)

A resin having at least a part of the resin skeleton. The chemical conversion treatment film made of the resin is considered to be capable of forming a chemical conversion treatment film having high adhesion to the article to be coated and the coating film by the action of the amino group contained in the resin. The manufacturing method of the said water-soluble resin (f) is not specifically limited, It can manufacture by a well-known method.

  The water-soluble resin (f) is represented by the following formula (1)

A polyvinylamine resin which is a polymer consisting only of structural units represented by:
And / or the following formula (2)

A polyallylamine resin, which is a polymer composed only of structural units represented by:
Is particularly preferred. The said polyvinylamine resin and polyallylamine resin have the advantage that it is excellent in the effect which improves adhesiveness especially. It does not specifically limit as said polyvinylamine resin, Commercially available polyvinylamine resin, such as PVAM-0595B (made by Mitsubishi Chemical Corporation), can be used. The polyallylamine resin is not particularly limited. For example, a commercially available polyallylamine resin such as PAA-01, PAA-10C, PAA-H-10C, PAA-D11HCl (all manufactured by Nittobo Co., Ltd.) is used. Can do. Further, a polyvinylamine resin and a polyallylamine resin may be used in combination.

  The above-mentioned polyamine water-soluble resin (f) is modified by a method such as acetylation of a part of the amino group of the polyvinylamine resin and / or polyallylamine resin within the range not impairing the object of the present invention, Those partially or wholly neutralized with an acid, those crosslinked with a crosslinking agent within a range not affecting the solubility, and the like can also be used.

  The water-soluble polyamine resin (f) preferably has an amino group within a range of 0.01 mol as the lower limit and 2.3 mol as the upper limit per 100 g of the resin. If it is less than 0.01 mol, a sufficient effect cannot be obtained, which is not preferable. If it exceeds 2.3 mol, the intended effect may not be obtained. The lower limit is more preferably 0.1 mol.

  It is preferable that content of the said polyamine water-soluble resin (f) in the chemical conversion treatment agent concerning this invention exists in the range of a minimum of 5 ppm and a maximum of 5000 ppm by solid content. If it is less than 5 ppm, a chemical conversion film having sufficient coating film adhesion cannot be obtained. If it exceeds 5000 ppm, film formation may be hindered. The lower limit is more preferably 10 ppm, and the upper limit is more preferably 500 ppm.

  The polyamine water-soluble resin (f) preferably has a number average molecular weight in the range of a lower limit of 500 and an upper limit of 500,000. If it is less than 500, a chemical conversion film having sufficient coating film adhesion cannot be obtained, which is not preferable. If it exceeds 500,000, film formation may be inhibited. The lower limit is more preferably 5000, and the upper limit is more preferably 70000.

The water-soluble epoxy compound (g) having an amino group is not particularly limited as long as it has a solubility sufficient to dissolve a necessary amount in the chemical conversion treatment agent. The amino group is not particularly limited, and examples thereof include -NH ₂ group, monoalkylamino group, dialkylamino group, monohydroxyamino group, dihydroxyamino group, and other compounds having primary to tertiary amines. Can do.

  The water-soluble epoxy compound (g) having an amino group may have an epoxy resin as a skeleton. The epoxy resin is not particularly limited. For example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, hydrogenated bisphenol A type epoxy resin, hydrogenated bisphenol F type epoxy resin, bisphenol A propylene oxide addition type epoxy resin, bisphenol Examples thereof include F-propylene oxide addition type epoxy resins. Of these, bisphenol F type epoxy resins are preferable, and bisphenol F epichlorohydrin type epoxy resins are preferable.

  The reaction for introducing an amino group into the epoxy resin forming the skeleton is not particularly limited, and examples thereof include a method of mixing an epoxy resin and an amine compound in a solvent.

  It is preferable that the said chemical conversion treatment agent contains the said water-soluble epoxy compound (g) which has an amino group in solid content in the range whose lower limit is 20 ppm and whose upper limit is 5000 ppm. If it is less than 20 ppm, there is a possibility that proper post-coating performance may not be obtained in the obtained chemical conversion film, and if it exceeds 5000 ppm, there is a possibility that the chemical conversion film is not efficiently formed. A more preferred lower limit is 50 ppm, and a more preferred upper limit is 1000 ppm.

  It is preferable that the water-soluble epoxy compound (g) having an amino group further has an isocyanate group. By having the isocyanate group, a cross-linking reaction is caused with the epoxy compound, which is preferable in that the physical properties of the film are improved. The isocyanate group is preferably a blocked isocyanate group blocked with a blocking agent. By blocking, it can mix | blend stably in a chemical conversion treatment agent.

  The blocked isocyanate group can be introduced into the epoxy compound by reacting a polyisocyanate compound in which a part of the isocyanate group is blocked with the epoxy compound. The polyisocyanate is not particularly limited, and examples thereof include aliphatic diisocyanates such as hexamethylene diisocyanate (including trimer), tetramethylene diisocyanate, and trimethylhexamethylene diisocyanate, isophorone diisocyanate, 4,4′-methylenebis (cyclohexyl). And alicyclic polyisocyanates such as isocyanate), aromatic diisocyanates such as 4,4′-diphenylmethane diisocyanate, tolylene diisocyanate, and xylylene diisocyanate.

  The blocking agent is not particularly limited, and examples thereof include monovalent alkyl (or aromatic) alcohols such as n-butanol, n-hexyl alcohol, 2-ethylhexanol, lauryl alcohol, phenol carbinol, and methylphenyl carbinol. Cellosolves such as ethylene glycol monohexyl ether and ethylene glycol mono 2-ethylhexyl ether; phenols such as phenol, para-t-butylphenol and cresol; dimethyl ketoxime, methyl ethyl ketoxime, methyl isobutyl ketoxime, methyl amyl ketoxime, Examples include oximes such as cyclohexanone oxime; lactams represented by ε-caprolactam and γ-butyrolactam. Oxime and lactam blocking agents dissociate at low temperatures, and are more preferable from the viewpoint of resin curability.

  As the water-soluble epoxy compound (g) having an amino group, commercially available products such as Adeka Resin EM-0436 series, Adeka Resin EM-0436F series, Adeka Resin EM0718 series (all manufactured by Asahi Denka Kogyo Co., Ltd.) can also be used. .

  The water-soluble epoxy compound (g) having an amino group may further contain a phosphorus element. The phosphorus element is preferably contained in the soluble epoxy compound having the amino group as a phosphate group. The phosphate group may be partially alkylated. The phosphate ester group can be introduced into the epoxy compound by a reaction between the epoxy group and a phosphate compound.

  By blending the silane coupling agent and / or the hydrolyzate (h) thereof with the chemical conversion treatment agent, the resulting chemical conversion treatment film and the object to be coated are adsorbed in a hydrogen bond, and stability and adhesion are improved. It is thought to improve.

  The silane coupling agent is not particularly limited, and examples thereof include vinyltrimethoxysilane, vinyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ sold by Shin-Etsu Chemical, Nippon Unicar, Chisso, Toshiba Silicone and the like. -Aminopropylethoxysilane, N- [2- (vinylbenzylamino) ethyl] -3-aminopropyltrimethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyl Methyldiethoxysilane, γ-methacryloxypropyltriethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyltrimethoxysilane, 2- (3 4 Epoxycyclohexyl) ethyltrimethoxysilane, N-β (aminoethyl) γ-aminopropyltrimethoxysilane, N-β- (aminoethyl) -γ-aminopropyltriethoxysilane, N-β- (aminoethyl) -γ -Aminopropylmethyldimethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane and the like can be mentioned. Among these, it is more preferable to use an aminosilane coupling agent having an amino group because it has a particularly excellent effect in improving adhesion.

  The hydrolyzate of the silane coupling agent can be produced by a conventionally known method, for example, a method of dissolving the amino group-containing silane coupling agent in ion-exchanged water and adjusting the acidity with an arbitrary acid. . Examples of the hydrolyzate of the silane coupling agent include KBP-90, KBP-60, KBP-40, KBP-41, KBP-43, KBP-44, and X-12-414 (all manufactured by Shin-Etsu Silicone). Commercially available products can also be used. Of these, KBP-90 is preferable from the viewpoint of improving adhesion.

  The content of the silane coupling agent and / or the hydrolyzate (h) thereof in the chemical conversion treating agent according to the present invention is preferably in the range of a lower limit of 5 ppm and an upper limit of 5000 ppm. If it is less than 5 ppm, a chemical conversion treatment film having sufficient adhesion cannot be obtained. If it exceeds 5000 ppm, film formation may be hindered. The lower limit is more preferably 30 ppm, and the upper limit is more preferably 2000 ppm.

  Each of the components (a) to (h) may be used alone, but may be used in combination of two or more components as necessary. When two or more components are used at the same time, the content of each component is preferably within the above range, and the total amount of each component is not particularly limited. Particularly preferred combinations are (a) + (b), (a) + (b) + (d) + (f), (a) + (b) + (c) + ((f) or (g) ), (A) + (b) + ((e), (f) or (h)), (a) + (b) + (e) + ((f), (g) or (h)) Can be mentioned.

Chemical conversion reaction accelerator The chemical conversion treatment agent according to the present invention may further contain a chemical conversion reaction accelerator as required. By containing a chemical conversion reaction accelerator, the problem that the film thickness of the chemical conversion treatment film obtained becomes non-uniform depending on the location can be solved. When an object having an edge portion is treated with a surface treatment agent made of a conventional zirconium compound, an anodic dissolution reaction occurs selectively at the edge portion, so that the cathode reaction tends to occur near the edge portion. A film tends to be deposited in the vicinity. On the other hand, since the anodic dissolution reaction hardly occurs in the flat portion of the object to be coated, deposition of the film is suppressed. For this reason, a nonuniformity arises in the chemical conversion treatment film obtained. The chemical conversion reaction accelerator in the present invention is a compound used to solve the above-described problems, and when added to the chemical conversion treatment agent, the difference in chemical conversion treatment reaction between the edge portion and the flat portion described above is caused. The chemical conversion treatment can be performed without any problem.

  The chemical conversion reaction accelerator includes nitrite ion, nitro group-containing compound, hydroxylamine sulfate, persulfate ion, sulfite ion, hyposulfite ion, peroxide, iron (III) ion, iron citrate compound, bromate ion, It is at least one selected from the group consisting of perchlorate ion, chlorate ion, chlorite ion, ascorbic acid, citric acid, tartaric acid, malonic acid, succinic acid and salts thereof, among others, etching In order to accelerate the reaction efficiently, those having an oxidizing action or organic acids are preferred. By blending these chemical conversion reaction accelerators with the chemical conversion treatment agent, it is possible to adjust the unevenness of film deposition and obtain a good chemical conversion treatment film without unevenness even at the edge portion and the flat portion of the object to be coated.

The supply source of the nitrite ions is not particularly limited, and examples thereof include sodium nitrite, potassium nitrite, and ammonium nitrite. The nitro group-containing compound is not particularly limited, and examples thereof include nitrobenzenesulfonic acid and nitroguanidine. It is not particularly limited as the source of the persulfate ion, for _example, a _{Na 2 S 2 O 8, K} 2 S 2 O 8 or the like. The supply source of the sulfite ion is not particularly limited, and examples thereof include sodium sulfite, potassium sulfite, and ammonium sulfite. The supply source of the hyposulfite ion is not particularly limited, and examples thereof include sodium hyposulfite, potassium hyposulfite, and ammonium hyposulfite. It does not specifically limit as said peroxide, For example, hydrogen peroxide, sodium peroxide, potassium peroxide etc. can be mentioned.

  The supply source of the iron (III) ions is not particularly limited, and examples thereof include iron (III) nitrate, iron (III) sulfate, and iron (III) chloride. The iron citrate compound is not particularly limited, and examples thereof include iron ammonium citrate, sodium iron citrate, and potassium iron citrate. The source of bromate ions is not particularly limited, and examples thereof include sodium bromate, potassium bromate, and ammonium bromate. The supply source of the perchlorate ion is not particularly limited, and examples thereof include sodium perchlorate, potassium perchlorate, and ammonium perchlorate.

  The supply source of the chlorate ion is not particularly limited, and examples thereof include sodium chlorate, potassium chlorate, and ammonium chlorate. The supply source of the chlorite ion is not particularly limited, and examples thereof include sodium chlorite, potassium chlorite, and ammonium chlorite. It does not specifically limit as said ascorbic acid and its salt, For example, ascorbic acid, sodium ascorbate, potassium ascorbate, ammonium ascorbate etc. can be mentioned. It does not specifically limit as said citric acid and its salt, For example, a citric acid, sodium citrate, potassium citrate, ammonium citrate etc. can be mentioned. The tartaric acid and its salt are not particularly limited, and examples thereof include tartaric acid, ammonium tartrate, potassium tartrate, sodium tartrate and the like. It does not specifically limit as said malonic acid and its salt, For example, malonic acid, ammonium malonate, potassium malonate, sodium malonate, etc. can be mentioned. The succinic acid and its salt are not particularly limited, and examples thereof include succinic acid, sodium succinate, potassium succinate, ammonium succinate and the like. Although the chemical conversion reaction accelerator mentioned above may be used independently, two or more components may be used as needed.

  The compounding amount of the chemical conversion reaction accelerator in the chemical conversion treating agent according to the present invention is in the range of a lower limit of 1 ppm and an upper limit of 5000 ppm. If it is less than 1 ppm, a sufficient effect cannot be obtained, which is not preferable. If it exceeds 5000 ppm, film formation may be hindered. The lower limit is preferably 3 ppm, and more preferably 5 ppm. The upper limit is preferably 2000 ppm and more preferably 1500 ppm.

Preparation of the chemical conversion treatment agent The chemical conversion treatment agent can be prepared by mixing the components (A), (B) and (C) in an aqueous solvent. As the aqueous solvent, tap water, ion-exchanged water, pure water or the like can be used without particular limitation. The aqueous solvent may contain a small amount of alcohols as required. In addition, it is preferable that the chemical conversion treatment agent concerning this invention is a thing which does not contain a phosphate ion substantially. The phrase “substantially free of phosphate ions” means that the phosphate ions are not contained so much as to act as a component in the chemical conversion treatment agent. Since the chemical conversion treatment agent according to the present invention does not substantially contain phosphate ions, the chemical conversion treatment agent does not substantially use phosphorus that causes environmental load, and occurs when a zinc phosphate treatment agent is used. Generation of sludge such as iron phosphate and zinc phosphate can be suppressed.

  The chemical conversion treatment agent according to the present invention preferably has a pH in a range with a lower limit of 1.5 and an upper limit of 6.5. If it is less than 1.5, the etching becomes excessive and a sufficient film cannot be formed. If it exceeds 6.5, etching becomes insufficient and a good film cannot be obtained. The lower limit is more preferably 2.0, and the upper limit is more preferably 5.5. The lower limit is more preferably 2.5, and the upper limit is more preferably 5.0. In order to adjust the pH, acidic compounds such as nitric acid and sulfuric acid, and basic compounds such as sodium hydroxide, potassium hydroxide and ammonia can be used.

Formation of the chemical conversion film The method for forming the chemical conversion film on the surface of the object to be coated using the chemical conversion agent is not particularly limited, and the chemical conversion treatment agent and the surface of the object to be coated are subjected to normal processing conditions. This can be done by contacting. The treatment temperature in the chemical conversion treatment is preferably within a range of a lower limit of 20 ° C. and an upper limit of 70 ° C. The lower limit is more preferably 30 ° C, and the upper limit is more preferably 50 ° C. The chemical conversion time in the chemical conversion treatment is preferably in the range of a lower limit of 5 seconds and an upper limit of 1200 seconds. The lower limit is more preferably 30 seconds, and the upper limit is more preferably 120 seconds. The chemical conversion treatment method is not particularly limited, and examples thereof include a dipping method, a spray method, and a roll coating method.

  The surface of the object to be coated is preferably subjected to a degreasing treatment and a water washing treatment after degreasing in advance before the chemical conversion treatment. Moreover, after the chemical conversion treatment, it is preferable to perform a post-chemical conversion water washing treatment. Here, the degreasing treatment is performed to remove oil and dirt adhering to the surface of the object to be coated, and is usually performed at 30 to 55 ° C. with a degreasing agent such as a phosphorus-free and nitrogen-free degreasing cleaning solution. An immersion treatment of about a minute is performed. If desired, a preliminary degreasing process can be performed before the degreasing process.

  The post-degreasing rinsing treatment is performed by performing spraying once or more with rinsing water in order to wash the degreasing agent after the defatting treatment with water.

  The post-chemical water washing treatment is performed once or more so as not to adversely affect the adhesion, corrosion resistance, and the like after the subsequent various coatings. In this case, it is appropriate that the final water washing is performed with pure water. In this post-chemical conversion water washing treatment, either spray water washing or immersion water washing may be used, and these methods may be combined for water washing. In addition, the chemical conversion treatment using the chemical conversion treatment agent according to the present invention does not perform the necessary surface conditioning treatment in the method of treatment using a zinc phosphate chemical conversion treatment agent that has been practically used. Therefore, the chemical conversion treatment film can be formed on the object to be coated with fewer steps.

  In the chemical conversion treatment using the chemical conversion treatment agent according to the present invention, the drying step after the post-chemical conversion water washing treatment is not necessarily required. Even if the chemical conversion treatment film is wet without performing the drying step, it does not affect the performance obtained by coating. Moreover, when performing a drying process, it is preferable to perform cold air drying, hot air drying, etc. When performing hot air drying, in order to prevent decomposition | disassembly of organic content, 300 degrees C or less is preferable.

  The chemical conversion treatment agent according to the present invention is capable of imparting sufficient coating film adhesion even to an iron-based substrate that has been unsuitable for pretreatment with a conventional chemical conversion treatment agent composed of zirconium or the like. For this reason, it has excellent properties in that it can be used for the treatment of an object to be treated that contains an iron-based substrate at least partially.

The chemical conversion treatment film obtained by the chemical conversion treatment agent according to the present invention has a lower limit of 0.1 mg / m ² , the upper limit of the total amount of the metal contained in the chemical conversion treatment agent and the amount of carbon contained in the epoxy compound. It is preferable to be within the range of 500 mg / m ² . If it is less than 0.1 mg / m ² , a uniform chemical conversion treatment film cannot be obtained, which is not preferable. If it exceeds 500 mg / m ² , it is economically disadvantageous. The lower limit is more preferably 5 mg / m ² , and the upper limit is more preferably 200 mg / m ² .

In addition, as a chemical conversion treatment agent which does not contain a phosphate ion, a harmful heavy metal ion, etc., the zirconium containing chemical conversion treatment agent which does not contain the adhesiveness and corrosion resistance imparting agent conventionally used is mentioned, for example. In the case of treating an object to be coated using such a zirconium-containing chemical conversion treatment agent, the metal ions eluted in the chemical conversion treatment agent extract ZrF ₆ ^2- fluorine ions, or the increase of the interface pH causes the zirconium It is considered that a hydroxide or oxide is generated, and this zirconium hydroxide or oxide is deposited on the surface of the object to be coated.

  However, when such a zirconium-containing chemical conversion treatment agent is used, there are problems such as occurrence of uneven thickness of the chemical conversion treatment film, and in particular, sufficient adhesion cannot be obtained with an iron-based substrate. Such a problem of unevenness in the thickness of the film is derived from the difference in the amount of film deposited at a portion having a different shape, such as an edge portion or a flat portion of an object to be coated.

  In addition, in the case of processing a workpiece with a zirconium-containing chemical conversion treatment agent that does not contain adhesion and corrosion resistance imparting agents instead of the zinc phosphate treatment that is widely used as a chemical conversion treatment method, it is sufficient particularly for an iron-based substrate. Inadequate coating film adhesion cannot be obtained. By using the chemical conversion treatment agent according to the present invention, the above-described problems are solved, and the chemical conversion treatment has sufficient stability and coating film adhesion to an iron-based substrate without causing unevenness of the film. A film can be formed.

  The chemical conversion treatment agent according to the present invention is a chemical conversion treatment agent containing at least one selected from the group consisting of zirconium, titanium, and hafnium as a film forming component. By using this chemical conversion treatment agent, it is possible to suppress unevenness of the chemical conversion treatment film due to a deviation in the amount of the film deposited on the object to be coated, thereby obtaining a chemical conversion treatment film having good performance. Furthermore, the chemical conversion treatment agent according to the present invention improves the stability of the chemical conversion treatment film, so that a coating film can be applied even to an iron-based substrate that has been unsuitable for pretreatment with a chemical conversion treatment agent made of zirconium or the like. A chemical conversion film having excellent adhesion can be formed.

  Further, since the chemical conversion treatment agent does not substantially contain phosphate ions, it has an advantage that the load on the environment is small and sludge (sludge) is not generated. Furthermore, since the chemical conversion treatment using the chemical conversion treatment agent does not require a surface adjustment step, the chemical conversion treatment of the object to be coated can be performed with fewer steps. Before forming a cured electrodeposition coating film according to the present invention, a chemical conversion treatment film is formed on the article to be coated using the chemical conversion treatment agent, and a multilayer coating film comprising the chemical conversion treatment film and the cured electrodeposition coating film is formed. By forming, in addition to the above-mentioned advantages, it is possible to obtain a coating film having excellent adhesion to the object to be coated and corrosion resistance.

  The following examples further illustrate the present invention, but the present invention is not limited thereto. In the examples, “parts” and “%” are based on weight unless otherwise specified.

Production Example 1 Preparation of Cationic Resin A reaction vessel equipped with a stirrer, a cooling tube, a nitrogen introduction tube, and a thermometer, Epicoat 1001 (Oilized Shell Epoxy, bisphenol A type epoxy resin having an epoxy equivalent of 475) 99.8 Part, Epicoat 1004 (manufactured by Yuka Shell Epoxy, bisphenol A type epoxy resin having an epoxy equivalent of 950), 55 parts of nonylphenol, 193.3 parts of methyl isobutyl ketone (MIBK) and 4.5 g of benzyldimethylamine were added. , And reacted at 140 ° C. for 4 hours to obtain a resin having an epoxy equivalent of 1175. Here, 69.1 parts of ethylene glycol n-hexyl ether, 35.4 parts of MIBK solution (solid content 78% by weight) of MIBK ketimine product of 2-aminoethylethanolamine, 26.5 parts of N-methylethanolamine and 37 of diethanolamine 37 .1 part was added. This was reacted at 120 ° C. for 2 hours to obtain the desired resin.

Production Example 2 Preparation of Cationic Acrylic Resin In a flask equipped with a stirrer, cooling tube, nitrogen introduction tube and dropping funnel, 50.7 parts of styrene, 10.0 parts of methyl methacrylate, 20.1 parts of n-butyl acrylate, 2 -A mixture of 10.2 parts of hydroxyethyl methacrylate, 9.2 parts of glycidyl methacrylate, and 4.0 parts of t-butyl peroctoate was dropped from a dropping funnel over 3 hours. After completion of dropping, the mixture was kept at 115 ° C. for about 1 hour, 0.5 part of t-butyl peroctoate was dropped, and kept at 115 ° C. for about 30 minutes to obtain a resin solution having a solid content of 65%. A resin solution having a number average molecular weight (Mn) of 5000 was obtained. After cooling, 5.1 parts of N-methylethanolamine was added thereto and reacted at 120 ° C. for 2 hours under a nitrogen atmosphere to obtain a cationic acrylic resin solution having a solid content of about 66%.

Production Example 3 Preparation of Block Polyisocyanate Curing Agent In a five-necked flask equipped with a reflux condenser, a stirrer, a dropping funnel and a nitrogen introduction tube, 199.1 parts of hexamethylene diisocyanate trimer (Coronate EH) and methyl isobutyl ketone 31.6 parts were charged and heated to 40 ° C. in a nitrogen atmosphere. To this was added 0.2 part of dibutyltin dilaurate, and further 87.0 parts of methylethylketoxime was added dropwise over 2 hours from the dropping funnel. After completion of the addition, the reaction was carried out at 70 ° C. until the peak of the isocyanate group disappeared by IR spectrum. It was. After completion of the reaction, 38.1 parts of methyl isobutyl ketone and 1.6 parts of butanol were added and cooled to obtain a block polyisocyanate crosslinking agent having a solid content of 80%.

Production Example 4 Preparation of Epoxy Resin Pigment Dispersion Resin 382 parts of Epicoat 828 and 118 parts of bisphenol A were placed in a reaction vessel and heated to 150 to 160 ° C. in a nitrogen atmosphere. The reaction mixture was reacted at 150-160 ° C. until the epoxy equivalent reached 500. Subsequently, after cooling the reaction mixture to 140 to 145 ° C., 203 parts of 2-ethylhexanol half-blocked toluene diisocyanate was added. The reaction mixture was kept at 140-145 ° C. for about 1 hour and then 209 parts dipropylene glycol monobutyl ether was added. Next, the reaction mixture was cooled to 90 ° C. or lower, and 272 parts of 1- (2-hydroxyethylthio) propan-2-ol, 134 parts of dimethylolpropionic acid, and 144 parts of deionized water were added. This mixture was reacted at 65 to 75 ° C. until an acid value of about 8 was obtained to obtain a pigment dispersing resin. This was cooled and diluted with deionized water to a solids content of 30% to obtain a varnish for pigment dispersion.

Production Example 5 Preparation of Cationic Main Emulsion The cationic resin of Production Example 1 and the polyisocyanate cross-linking agent of Production Example 3 are mixed at a solid content of 70:30, and acetic acid is added so that the neutralization rate is 40%. Then, the mixture was slowly diluted by mixing in deionized water, and then methyl isobutyl ketone and deionized water were removed so that the non-volatile content was 37% by mass to obtain a cationic main emulsion.

Production Example 6 Preparation of Cationic Acrylic Resin Emulsion In the same manner as in Production Example 5, an emulsion having a non-volatile content of 33% containing the cationic acrylic resin of Production Example 2 and the crosslinking agent of Production Example 3 in a ratio of 70:30 as a solid content. It was created.

Production Example 7 Preparation of Pigment Dispersion Paste (Black) A cationic pigment dispersion paste was prepared by dispersing the following blending amount.

  In the above table, carbon black: MA-100 manufactured by Mitsubishi Chemical Corporation.

Production Example 8 Preparation of Pigment Dispersion Paste (Gray) A cationic pigment dispersion paste was prepared by dispersing the following blending amount.

  In the above table, carbon black: manufactured by Mitsubishi Chemical Corporation, MA-100, titanium oxide: manufactured by Ishihara Sangyo Co., Ltd., Type CR-97.

Comparative Production Example 1 Preparation of Pigment Dispersion Paste (Black) A cationic pigment dispersion paste was prepared by dispersing the following blending amount.

  In the above table, carbon black: MA-100 manufactured by Mitsubishi Chemical Corporation.

Comparative Production Example 2 Preparation of Pigment Dispersion Paste (Gray) A cationic pigment dispersion paste was prepared by dispersing the following blending amount.

  In the above table, carbon black: manufactured by Mitsubishi Chemical Corporation, MA-100, titanium oxide: manufactured by Ishihara Sangyo Co., Ltd., Type CR-97.

Production Example 9 Preparation of chemical conversion treatment agent Zircon hydrofluoric acid and amino group-containing silane coupling agent (h) KBM-603 (N-2 (aminoethyl) 3-aminopropyltrimethoxysilane: effective concentration 100%: A chemical conversion treatment agent was prepared using Shin-Etsu Chemical Co., Ltd.). These were added to ion-exchanged water and mixed so that the zirconium concentration was 100 ppm and the amino group-containing silane coupling agent concentration was 100 ppm, and then adjusted to pH 4 using sodium hydroxide to obtain a chemical conversion treatment agent. .

Example 1
10.8 parts by weight of the cationic main emulsion of Production Example 5, 0.5 parts by weight of the cationic acrylic resin emulsion of Production Example 6, 1.9 parts by weight of the pigment dispersion paste of Production Example 8, and 86.8 parts by weight of deionized water Parts were mixed to obtain a cationic electrodeposition coating composition having a gray hue. The obtained cationic electrodeposition coating composition had a solid content of 5% by weight.

Using the resulting cationic electrodeposition coating composition, electrodeposition was applied to a cold-rolled steel sheet that had been degreased and zinc phosphate-treated so that the thickness of the cured electrodeposition coating film was 20 μm. After washing with water, baking was performed at 140 ° C. for 20 minutes to obtain a cured electrodeposition coating film.

Example 2
32.4 parts by weight of the cationic main emulsion of Production Example 5, 1.6 parts by weight of the cationic acrylic resin emulsion of Production Example 6, 5.6 parts by weight of the pigment dispersion paste of Production Example 8, and 60.4 parts by weight of deionized water Parts were mixed to obtain a cationic electrodeposition coating composition having a gray hue. The obtained cationic electrodeposition coating composition had a solid content of 15% by weight.

  Using the obtained cationic electrodeposition coating composition, coating was performed in the same manner as in Example 1 to obtain a cured electrodeposition coating film.

Example 3
29.6 parts by weight of the cationic main emulsion of Production Example 5, 3.7 parts by weight of the cationic acrylic resin emulsion of Production Example 6, 10.8 parts by weight of the pigment dispersion paste of Production Example 8, and 55.8 parts by weight of deionized water Parts were mixed to obtain a cationic electrodeposition coating composition having a black hue. The obtained cationic electrodeposition coating composition had a solid content of 15% by weight.

  Using the obtained cationic electrodeposition coating composition, coating was performed in the same manner as in Example 1 to obtain a cured electrodeposition coating film.

Example 4
The degreased cold-rolled steel sheet was immersed in the chemical conversion treatment agent of Production Example 9 (temperature: 40 ° C.) for 60 seconds to form a chemical conversion treatment film. The coating amount of the chemical conversion treatment film was 40 mg / m ² . The coating amount is included in the chemical conversion treatment agent using “XRF1700” (Shimadzu X-ray fluorescence analyzer) after the cold-rolled steel sheet after washing with water is dried at 80 ° C. for 5 minutes in an electric drying furnace. The total amount of metal was analyzed. The obtained object to be coated was then sprayed with tap water for 30 seconds and further sprayed with ion-exchanged water for 10 seconds.

  Then, electrodeposition coating was performed without passing through a drying process. In the electrodeposition coating, the cationic electrodeposition coating composition prepared in Example 1 was used. Electrodeposition coating was performed in the same manner as in Example 1 to form a cured electrodeposition coating film to obtain a multilayer coating film.

Comparative Example 1
A cationic electrodeposition coating composition having a gray hue was prepared in the same manner as in Example 1 except that 1.9 parts by weight of the pigment dispersion paste of Comparative Production Example 2 was used. The obtained cationic electrodeposition coating composition had a solid content of 5% by weight.

  Using the obtained cationic electrodeposition coating composition, coating was performed in the same manner as in Example 1 to obtain a cured electrodeposition coating film.

Comparative Example 2
A cationic electrodeposition coating composition having a gray hue was prepared in the same manner as in Example 2 except that 5.6 parts by weight of the pigment dispersion paste of Comparative Production Example 2 was used. The obtained cationic electrodeposition coating composition had a solid content of 15% by weight.

  Using the obtained cationic electrodeposition coating composition, coating was performed in the same manner as in Example 1 to obtain a cured electrodeposition coating film.

Comparative Example 3
A cationic electrodeposition coating composition having a black hue was prepared in the same manner as in Example 3 except that 10.8 parts by weight of the pigment dispersion paste of Comparative Production Example 1 was used. The obtained cationic electrodeposition coating composition had a solid content of 15% by weight.

  Using the obtained cationic electrodeposition coating composition, coating was performed in the same manner as in Example 1 to obtain a cured electrodeposition coating film.

  The following evaluation tests were carried out in the above examples and comparative examples.

Measurement of internal stress of coating film A coating film was formed on one side of the test strip in the same manner as in the above Examples and Comparative Examples except that a Be-Cu test strip was used as an object to be coated. After baking and hardening, warpage (open leg state) generated on the test strip was measured using a deposit stress analyzer (manufactured by Electrochemical Co., Ltd.). In addition, the schematic explanatory drawing about the curvature (open leg state) of a test strip is shown in FIG. The numerical value (mm) of the warp (open leg state) was “U”, and the internal stress of the coating film was calculated from the following formula. The results obtained are shown in Table 5.

S = 53.0 × {(U × K) / (T × D)} (unit: kg / mm ² )
S: Internal stress K: Test strip correction factor T: Film thickness (mm)
D: Density of precipitates

The lightness of the Munsell color system of the cured electrodeposition coating film obtained by the hue example and comparative example of the cationic electrodeposition coating composition was measured using the “Minolta spectrocolorimeter CM-2002” (trade name, manufactured by Minolta Co., Ltd.). Measurement was performed using a color difference meter.

Salt spray test A salt spray test was conducted for 240 hours in accordance with JIS Z-2371. The tape was peeled off at the cross cut portion of the test piece subjected to the spray test, and the resulting peel width (mm) was measured. It can be said that it is a coating film which is excellent in corrosion resistance, so that this peeling width is small.

Production Example 10
Preparation of resin for dispersing anionic pigment Disperse 700 parts by weight of isopropyl alcohol in a 2 L reaction vessel equipped with a stirrer, a cooling pipe, a nitrogen introduction pipe, and a thermometer connected to a temperature controller, and heat to 80 ° C. in a nitrogen atmosphere. did. In a reaction vessel, 210 parts by weight of methyl methacrylate, 196 parts by weight of butyl acrylate, 140 parts by weight of styrene, 84 parts by weight of 2-hydroxyethyl methacrylate, 70 parts by weight of acrylic acid, and 7 parts by weight of azobisdimethylvaleronitryl The solution was dropped at a constant rate over 3 hours, and then kept at 80 ° C. for 2 hours, whereby an acrylic copolymer for pigment dispersion having a solid content of 50%, an acid value of 78 mgKOH / g, a hydroxyl value of 52 mgKOH / g, and a weight average molecular weight of 28000 was obtained. A polymer resin (an anionic pigment dispersing resin) was obtained.

Production Example 11
Preparation of anionic pigment dispersion paste Anionic pigment dispersion resin of Production Example 10 (solid content 50%, molecular weight 28000, acid value 78, hydroxyl value 52), 100 parts titanium oxide (Taipeku CR-95, Ishihara Sangyo Co., Ltd.) 120 parts) and 5 parts of triethylamine and 115 parts of deionized water were added to obtain an anionic pigment dispersion paste having a solid content of 50%.

Production Example 12
Preparation of acrylic copolymer resin A 2 L reaction vessel equipped with a stirrer, a cooling tube, a nitrogen introduction tube, and a thermometer connected to a temperature controller was charged with 700 parts of isopropyl alcohol and heated to 80 ° C. in a nitrogen atmosphere. 322 parts of methyl methacrylate (MMA), 140 parts of butyl acrylate (nBA), 105 parts of styrene (St), 84 parts of 2-hydroxyethyl methacrylate (HEMA), 49 parts of acrylic acid (AA), azobisdimethylvaleronitrile An acrylic copolymer resin having an acid value of 55 mgKOH / g, a hydroxyl value of 52 mgKOH / g, and a weight average molecular weight of 30000 is obtained by dropping 7 parts of the mixed solution at a constant rate in 3 hours and then holding at 80 ° C. for 2 hours. It was.

Example 5
While mixing and stirring 313 parts of the acrylic copolymer resin of Production Example 12, 86 parts of Cymel 285-100 (manufactured by Cytec Co., Ltd.) which is a melamine resin as a curing agent, and 11 parts of triethylamine, the anionic pigment dispersion paste of Production Example 11 In contrast, 255 parts of heptanoic acid in an amount of 2% by weight with respect to the contained pigment was added, mixed and stirred, and 3035 parts of ion-exchanged water was further added to prepare an anionic electrodeposition coating composition. did. The solid content of the obtained anionic electrodeposition coating composition was 10% by weight.

  The obtained anion electrodeposition coating composition was coated on a silver base material obtained by subjecting a 6063S aluminum alloy plate to an alumite treatment (alumite film thickness 9 μm) and sealing treatment (immersion in hot water at 85 ° C. for 3 minutes). A DC voltage of 150 to 250 V was applied for 3 minutes, and electrodeposition was applied to achieve a predetermined film thickness. Thereafter, baking was performed at 180 ° C. for 30 minutes and drying was performed to obtain a cured electrodeposition coating film. About the obtained cured electrodeposition coating film, the internal stress was measured in the same manner as described above. Furthermore, after performing a CASS test for 240 hours according to JIS H8681, it evaluated based on the rating number chart. These evaluation results are shown in Table 6. The rating number is one of the methods for evaluating the state of occurrence of rust after accelerated corrosion resistance test such as salt water injection test and cast test. Corrosion area ratio (%) or color, size and number of test surface It is obtained from the standard photos rated by. In this evaluation, a state where no rust is generated is evaluated as “10”.

Comparative Example 4
An anionic electrodeposition coating composition was prepared in the same manner as in Example 5 except that heptanoic acid was not added to the anionic pigment dispersion paste of Production Example 11, and coating film formation and evaluation were performed. The evaluation results are shown in Table 6.

As shown in Table 5 and Table 6, the method of the present invention can reduce the internal stress of the coating film obtained in both black and gray cationic electrodeposition coating compositions and white anionic electrodeposition coating compositions. confirmed. Furthermore, according to the present invention, it was confirmed that effects such as an improvement in corrosion resistance such as a reduction in the peel width after the salt spray test and an improvement in the rating number after the CASS test can be obtained with a decrease in internal stress.

  By the method of the present invention, it is possible to form a cured electrodeposition coating film having low internal stress and low distortion. The cured electrodeposition coating film formed according to the present invention has high adhesion to an object to be coated, and therefore, the coating film is hardly peeled off by an impact from the outside, and further has the advantage of excellent corrosion resistance, moisture resistance, etc. Have.

  Furthermore, in this invention, a multilayer coating film can also be formed by performing electrodeposition coating after processing a to-be-coated article using a specific chemical conversion treatment agent. The multilayer coating film thus formed is superior in the adhesion between the object to be coated and the coating film, has a merit that the peeling of the coating film due to impact is less likely to occur, and the corrosion resistance, moisture resistance, etc. are also superior. Yes. This chemical conversion treatment agent does not contain harmful heavy metal ions that adversely affect the environment, and the burden on the environment is reduced. Further, this chemical conversion treatment agent does not generate sludge in the chemical conversion treatment step. For this reason, there is an advantage that the processing is performed more simply. By the method of the present invention, a coating film excellent in coating film adhesion and the like can be more easily formed without adversely affecting the environment.

It is a schematic explanatory drawing about the curvature state (open leg state) of a test strip.

Explanation of symbols

  1 ... coated film, 3 ... coated material.

Claims (10)

A step of immersing an object to be coated in a cationic electrodeposition coating composition to apply an uncured electrodeposition coating, and a step of baking and curing the obtained electrodeposition coating film,
A cured electrodeposition coating film forming method comprising:
The cationic electrodeposition coating composition is:
(I) a pigment, and (ii) a compound selected from the group consisting of fatty acids, fatty acid derivatives, amine compounds and mixtures of one or more thereof,
A cationic electrodeposition coating composition comprising a pigment dispersion paste comprising
The (i) pigment contains a black pigment, the cationic electrodeposition coating composition has a black hue, and the solid content concentration of the cationic electrodeposition coating composition is 100 parts by weight of the electrodeposition coating composition. 3 to 25 parts by weight, and the internal stress of the obtained cured electrodeposition coating film is 0.05 to 1.50 kg / mm ² .
Cured electrodeposition coating film forming method. A step of immersing an object to be coated in a cationic electrodeposition coating composition to apply an uncured electrodeposition coating, and a step of baking and curing the obtained electrodeposition coating film,
A cured electrodeposition coating film forming method comprising:
The cationic electrodeposition coating composition is:
(I) a pigment, and (ii) a compound selected from the group consisting of fatty acids, fatty acid derivatives, amine compounds and mixtures of one or more thereof,
A cationic electrodeposition coating composition comprising a pigment dispersion paste comprising
The (i) pigment contains a black pigment and a white pigment, the cationic electrodeposition coating composition has a gray hue, and the solid content concentration of the cationic electrodeposition coating composition is 100 weights of the electrodeposition coating composition. 3 to 25 parts by weight with respect to parts, and the internal stress of the obtained cured electrodeposition coating film is 0.05 to 0.30 kg / mm ² ,
Cured electrodeposition coating film forming method. A step of immersing an object to be coated in an anionic electrodeposition coating composition to perform uncured electrodeposition coating, and a step of baking and curing the obtained electrodeposition coating film.
A cured electrodeposition coating film forming method comprising:
The anion electrodeposition coating composition is:
(I) a pigment, and (ii) a compound selected from the group consisting of fatty acids, fatty acid derivatives, amine compounds and mixtures of one or more thereof,
An anionic electrodeposition coating composition comprising a pigment dispersion paste comprising
The (i) pigment contains a white pigment and optionally a colored pigment, the anionic electrodeposition paint has a white hue, and the solid content concentration of the anion electrodeposition paint composition is the electrodeposition paint composition 3 to 25 parts by weight with respect to 100 parts by weight, and the internal stress of the obtained cured electrodeposition coating film is 0.05 to 4.00 kg / mm ² .
Cured electrodeposition coating film forming method.   The method for forming a cured electrodeposition coating film according to any one of claims 1 to 3, wherein the fatty acid derivative is a fatty acid ester, a fatty acid amide compound, or an ethylene oxide ring-opening adduct of a fatty acid ester or a fatty acid amide compound.   The cured electrodeposition coating film forming method according to claim 4, wherein the fatty acid has 4 to 22 carbon atoms.   The cured electrodeposition coating film forming method according to any one of claims 1 to 3, wherein the amine compound is bonded to a nitrogen atom with an alkyl group having 4 to 22 carbon atoms.   The method for forming a cured electrodeposition coating film according to any one of claims 1 to 3, wherein the compound (ii) is contained in an amount of 0.1 to 30 parts by weight with respect to 100 parts by weight of the pigment.   The method for forming a cured electrodeposition coating film according to any one of claims 1 to 3, wherein the solid content concentration of the electrodeposition coating composition is 3 to 10 parts by weight with respect to 100 parts by weight of the electrodeposition coating composition.   A cured electrodeposition coating film formed from the cured electrodeposition coating film forming method according to claim 1. A method for forming a multilayer coating film, further comprising a step of forming a chemical conversion treatment film using a chemical conversion treatment agent before the step of electrodeposition coating according to claim 1 or 2.
The chemical conversion treatment agent is a chemical conversion treatment agent containing at least one (A) selected from the group consisting of zirconium, titanium and hafnium, fluorine (B), adhesion and corrosion resistance imparting agent (C),
The adhesion and corrosion resistance-imparting agent (C) are the following (a) to (h):
At least one metal ion (a) selected from the group consisting of zinc, manganese, and cobalt ions,
Alkaline earth metal ions (b),
Group 13 element metal ions (c),
Copper ion (d),
Silicon-containing compound (e),
Polyamine water-soluble resin (f),
A water-soluble epoxy compound having an amino group (g), and
Silane coupling agent and / or its hydrolyzate (h):
Including at least one selected from the group consisting of
A method for forming a multilayer coating film.

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