JP2008248064A - Electrodeposition coating composition containing starform surfactant - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrodeposition coating composition having defoaming tendency and also suppressing drying unevenness of its own. <P>SOLUTION: The electrodeposition coating composition having defoaming tendency and also suppressing drying unevenness of its own is obtained by including 0.05-10 wt.%, preferably 0.1-5 wt.%, especially preferably 1 wt.% of a starform surfactant based on cationic or anionic electrodeposition coating resin solids. When the surfactant is at less than 0.05 wt.%, the defoaming tendency is insufficient, on the other hand, when at greater than 10 wt.%, the defoaming effect becomes saturated, being meaningless. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electrodeposition coating composition containing a star-shaped surfactant.

  Electrodeposition coating is a coating method performed by immersing an object to be coated in an 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.

  As described above, the electrodeposition coating is performed by immersing the article to be coated in the coating composition. However, air is brought into the electrodeposition coating composition as the coating object is immersed. Therefore, bubbles often occur in electrodeposition coating. The bubbles generated in this way may adhere to the surface of the electrodeposition coating film when the soaked object is pulled up, which may reduce the appearance of the coating film. The generation of bubbles in the electrodeposition coating further has a problem of reducing the workability of the electrodeposition coating.

  Conventional electrodeposition coating compositions have high antifoaming agents (for example, JP 2002-60682 (Patent Document 1) and JP 2004-339364 A) to improve productivity and workability. (Patent Document 2), JP-A-2006-342239 (Patent Document 3), JP-A-11-35857 (Patent Document 4) and JP-A-11-80623 (Patent Document 5) Etc.).

  JP 2002-60682 (Patent Document 1) discloses a compound (A) obtained by addition polymerization of 29 to 46 mol of alkylene oxide having 3 to 4 carbon atoms to 1 mol of sucrose, and 2 carbon atoms. -6 to 25 mol of 55 to 55 mol of C2-C3 alkylene oxide to 1 mol of alcohol having 1 to 3 hydroxyl groups and having a cloud point of 10 to 27 ° C as a constituent component An antifoaming agent is disclosed.

JP 2004-339364 A (Patent Document 2) describes the formula {H- (OA) _n- } _m Q (1) [wherein Q is a non-reducing disaccharide or trisaccharide m primary class. A reaction residue obtained by removing a hydrogen atom from a hydroxyl group, OA is an oxyalkylene group having 2 to 4 carbon atoms, n is an integer of 0 to 100, m is an integer of 2 to 4, and m {H- (OA) _n- } may be the same or different, and the total number of OA (n × m) is 47-100. ] The surfactant which comprises the polyoxyalkylene compound (A) represented by this is disclosed.

  JP-A-2006-342239 (Patent Document 3) discloses an antifoaming agent containing at least one polyoxyalkylene compound.

  Japanese Patent Application Laid-Open No. 11-35857 (Patent Document 4) discloses an antifoaming agent for cathodic deposition type electrodeposition coating material comprising an aliphatic alcohol having 18 or more carbon atoms.

  In JP-A-11-80623 (Patent Document 5), as an antifoaming agent, a compound (A) obtained by addition polymerization of 29 to 46 moles of alkylene oxide having 3 to 4 carbon atoms to sucrose and / or an average carbon number of 12 is disclosed. A compound (B) obtained by addition polymerization of 4 to 8 moles of an alkylene oxide having 2 to 3 carbon atoms to -18 alkylamine is disclosed.

  However, these antifoaming agents having a high defoaming property are often hydrophobic, and adding a hydrophobic antifoaming agent to the electrodeposition coating composition improves the defoaming property, but the electrodeposition coating composition The surface tension of the electrodeposits decreases, leading to a decrease in the wettability of the electrodeposition coating composition with respect to the object. As a result, when the object to be coated is lifted from the electrodeposition tank, the coating liquid adhering to the surface of the object to be coated repels the polka dots, which may cause “dry unevenness” in the resulting electrodeposition coating film. is there. For example, if unevenness of drying occurs after electrodeposition coating on an object such as an automobile body, a coating film to be coated on the coating tends to be defective, and the appearance of the coating film may be greatly deteriorated.

Therefore, in this field, it is difficult to achieve both defoaming properties and uneven drying control, and there is a demand for the development of an electrodeposition coating composition that has antifoaming properties and suppresses uneven drying.
Japanese Patent Laid-Open No. 2002-60682 JP 2004-339364 A JP 2006-342239 A Japanese Patent Laid-Open No. 11-35857 Japanese Patent Laid-Open No. 11-80623

  An object of the present invention is to provide an electrodeposition coating composition that has antifoaming properties and suppresses uneven drying.

  As a result of diligent research in view of the above-mentioned problems, the present inventors have added anti-foaming properties and suppress drying unevenness by adding a star-shaped surfactant to the electrodeposition coating composition. It was found that a composition was obtained. Accordingly, the present invention provides an electrodeposition coating composition comprising a star surfactant.

In the electrodeposition coating composition of the present invention, the star surfactant is preferably
I) a reaction product of a reactant comprising the following (A) and (B):
(A) a binder of formula I
R ⁴ (Y) ₃ (I)
[Where:
Each Y group is a halogen atom, or one Y group is a halogen atom, the remaining two Y groups represent oxygen atoms, and are bonded to two adjacent carbon atoms of the R ⁴ group to form an epoxy group. Forming,
R ⁴ is an alkanetriyl group containing 3 to 10 carbon atoms];
(B) Compound of formula II
R ³ (EO) _n (PO) _m (BO) _p X (II)
[Where:
R ³ is a substituted or unsubstituted, saturated or unsaturated, aliphatic or araliphatic oxy or thio group having 1 to 36 carbon atoms, or a secondary amino group having 2 to 36 carbon atoms;
n is a number from 0 to 50;
m is a number from 0 to 50;
p is a number from 0 to 50, and X is hydrogen, or may be a mercapto group or an amino group];
Provided that when X is a mercapto group or an amino group, the sum of n, m and p must be at least 1,
In the above case, the molar ratio A: B of (A) and (B) is 0.2: 1 to 5: 1,
II) A reaction product with a reactant selected from the group consisting of epoxy compounds, isocyanate compounds, phosphate compounds, sulfate compounds, silicone compounds, organic acids, acrylates and methylol ureas.

  The present invention can provide an electrodeposition coating composition having antifoaming properties and suppressing unevenness in drying.

  The present invention relates to an electrodeposition coating composition containing a star-shaped surfactant. First, the star-shaped surfactant contained in the electrodeposition coating composition of the present invention will be described in detail.

Star surfactant The star surfactant contained in the electrodeposition coating composition of the present invention is a kind of star polymer,
I) a reaction product of a reaction product comprising the following (A) and (B) (hereinafter sometimes abbreviated as reaction product I);
(A) a binder of formula I
R ⁴ (Y) ₃ (I)
[Where:
Each Y group is a halogen atom, or one Y group is a halogen atom, the remaining two Y groups represent (one) oxygen atoms and are bonded to two adjacent carbon atoms of the R ⁴ group. To form an epoxy group
R ⁴ is an alkanetriyl group containing 3 to 10 carbon atoms];
(B) Compound of formula II
R ³ (EO) _n (PO) _m (BO) _p X (II)
[Where:
R ³ is a substituted or unsubstituted, saturated or unsaturated, aliphatic or araliphatic oxy or thio group having 1 to 36 carbon atoms, or a secondary amino group having 2 to 36 carbon atoms And
n is a number from 0 to 50;
m is a number from 0 to 50;
p is a number from 0 to 50, and X is hydrogen, or may be a mercapto group or an amino group];
Provided that when X is a mercapto group or an amino group, the sum of n, m and p must be at least 1,
In the above case, the molar ratio A: B of (A) and (B) is 0.2: 1 to 5: 1,
II) A reactant selected from the group consisting of an epoxy compound, an isocyanate compound, a phosphate compound, a sulfate compound, a silicone compound, an organic acid, an acrylate, and a methylol urea (hereinafter sometimes abbreviated as “reactant II”)
It is a reaction product.

  The star surfactant used in the present invention has an antifoaming effect in the electrodeposition coating composition, and also has an advantage such as suppression of uneven drying, and other various performances are reduced by the blending thereof. And effective as a surfactant, antifoaming agent, antifoaming agent and / or wetting agent.

  Further, the reaction product I) itself is a polymer surfactant and is also useful as a polymer surfactant.

  In the reaction product of binder (A) and component (B), the molar ratio A: B of (A) and (B) is 0.2: 1 to 5: 1, preferably 0.4: 1 to 2: 1, more preferably 0.6: 1 to 1.4: 1.

  The binder of formula I is preferably epichlorohydrin, but other epihalohydrins may be used. Also, corresponding bromine and iodine compounds may be used in place of chlorine in epihalohydrins and trihaloalkanes. Examples of trihaloalkanes are 1,2,3-trichloropropane, 1,2,4-trichlorobutane, 1,3,6-trichlorohexane and the like.

  In the compound of formula II, EO represents an ethylene oxide residue, PO represents a propylene oxide residue, and BO represents a butylene oxide residue.

When the X group of formula II is a mercapto group, the R ³ group preferably has from 4 to 36 carbon atoms, examples of which include alkoxylated dodecyl mercaptan and alkoxylated 1-hexadecanethiol. However, it is not limited to these.

  The compound of formula II may be alkoxylated or non-alkoxylated secondary amines. When the compound of formula II is a secondary amine, n is a number from 0 to 50, preferably from 1 to 50, m is a number from 0 to 50, and p is from 0 to 50, preferably It is a number from 1 to 50. Examples of secondary amines useful for the purposes of the present invention include, but are not limited to, alkoxylated dibutylamine, alkoxylated dicyclohexylamine, alkoxylated diethylethanolamine, and alkoxylated dioctylamine.

The substituent that may be present in the substituted R ³ group may be one or more substituents, such as halogen substitution (eg, Cl, F, I and Br), mercaptan or thio group, etc. Nitrogen functionality such as amine or amide functionality; alcohol functionality, silicon functionality such as siloxane; ether functionality; or any combination thereof.

When the R ³ group is a substituted group, the substituent is preferably selected from the group consisting of halogen, mercaptan, thio, amine, amide, siloxane and ether groups.

  Of the compounds of formula II, those in which the sum of n, m and p is at least 1, in particular at least 2, are preferred.

When R ³ is a secondary amino group, preferably the amino group contains 4 to 22 carbon atoms.

When X is hydrogen, p is preferably a number from 1 to 50. When R ³ is a secondary amino group, p is preferably a number from 1 to 50.

The nonoxy and nonthio components of the R ³ group may be any substituted or unsubstituted, saturated or unsaturated organic moiety having 1 to 36 carbon atoms. Thus, the non-thio and non-oxy components of the R ³ aliphatic group have a straight or branched alkyl group, a straight or branched alkenyl or alkynyl group, a saturated carbocyclic moiety, one or more multiple bonds. Unsaturated carbocyclic moiety, saturated heterocyclic moiety, unsaturated heterocyclic moiety having one or more multiple bonds, substituted linear or branched alkyl group, substituted linear or branched alkenyl or alkynyl Groups, substituted saturated carbocyclic moieties, substituted unsaturated carbocyclic moieties having one or more multiple bonds, substituted saturated heterocyclic moieties, and having one or more multiple bonds It may be a substituted unsaturated heterocyclic moiety. Examples of the above include, but are not limited to, alkyl groups having 4 to 22 carbon atoms, alkenyl groups having 4 to 22 carbon atoms, and alkynyl groups having 4 to 22 carbon atoms. R ³ may also be an aralkyl (or aralkyl) group. An aralkyl group is an alkyl-substituted aromatic group (such as a benzyl group) having any valence on an alkyl carbon atom. Alkyl groups having 4 to 12 carbon atoms are preferred, and alkyl groups having 8 to 10 carbon atoms are most preferred. The degree of ethoxylation is preferably 2-50, most preferably 4-50, and the degree of propoxylation and butoxylation may vary from 0-50, preferably from 1-10. is there. The degree of propoxylation and / or butoxylation is determined by the desired degree of solubility or miscibility in the electrodeposition coating composition of the present invention. Solubility or miscibility is ultimately determined by factors such as the number of carbon atoms in R ³ and the relative amounts of EO, PO and BO.

  In the present specification, the multiple bond includes a double bond and a triple bond.

If desired, the binder of formula I and the compound of formula II may be reacted with further other components. Glycidyl ether or glycidylamine may be added to the reaction of Formula I and Formula II. The amount of glycidyl ether or glycidylamine is 1 to 20 mol% based on the number of moles of formula II used in the reaction. When glycidyl ether or glycidyl amine is added to a monofunctional starting material of formula II, the ratio of formula I to the sum of formula II and glycidyl ether or glycidyl amine is preferably between 0.8 and 1.4. is there. Examples of glycidyl ethers include PEG 600 diglycidyl ether, TETRONIC ^™ 701 tetraglycidyl ether, triglycidyl diethanolamine or triglycidyl triethanolamine, polyoxyethylene (POE) 200 tallow amine diglycidyl ether, propoxylated (POP10) trimethylol. Examples include, but are not limited to, propane triglycidyl ether, propoxylated (POP7) pentaerythritol tetraglycidyl ether. Examples of glycidylamine include, but are not limited to, tetraglycidyl 1,6-hexanediamine, tetraglycidyl JEFFAMINE ^™ EDR-148, and tetraglycidylisophoronediamine.

  Then, in a second step, the reaction product I) is reacted with a reactant II) selected from the group consisting of epoxy compounds, isocyanate compounds, phosphate compounds, sulfate compounds, silicone compounds, organic acids, acrylates and methylol ureas. Let

  When reactant II) is an epoxy compound, the epoxy compound may be any epoxy compound other than the binder of formula I. The epoxy compound may have one or more epoxy groups. Preferred compounds have 2 to 22 carbon atoms, preferably 2 to 12 carbon atoms. The epoxy compound is preferably unsubstituted and may be linear or branched and may have one or more double bonds. A preferred epoxy compound is ethylene oxide. These reaction products, particularly those obtained from ethylene oxide, have good water solubility, good detergency and low surface tension, and low foam formation.

  The reaction of reaction product I) with the epoxy compound can proceed satisfactorily at ambient temperature in an inert organic solvent such as a liquid hydrocarbon solvent.

When reactant II) is an isocyanate compound, the isocyanate compound may be an aliphatic or aromatic mono- or polyisocyanate. Aliphatic monoisocyanates, ie having the structural formula: RN═C═O, where R is a C ₁ -C ₂₂ , preferably C ₁ -C ₁₂ straight or branched chain alkyl or alkenyl group. Isocyanates are preferred. Aromatic isocyanates such as toluene diisocyanate and diphenylmethane 4,4-diisocyanate may also be used.

  The reactant II) may also be a reaction product of 1 mol of diol and 1 mol of dicarboxylic acid or anhydride (eg, maleic anhydride).

  The reaction of the isocyanate with the reaction product I) can proceed in an inert solvent such as a liquid hydrocarbon solvent, preferably at a temperature in the range of 50-200 ° C.

  When reactant II) is a phosphate compound, both inorganic and organic phosphate compounds can be used. Examples of the inorganic phosphate compounds include phosphorus pentoxide, phosphoric acid, acid phosphate salts (for example, mono- or disodium or potassium phosphate), and a surfactant having excellent antifoaming properties can be obtained.

Organic phosphate compounds include phosphate esters, ie, the formula: R ¹ OP (O) (OR ″) (OR ″ ′) wherein at least one R group is an organic group and at least 1 One R group is hydrogen, and the remaining R groups represent an organic group or hydrogen]. The organic group is preferably a C ₁ -C ₂₂ , more preferably a C ₁ -C ₁₂ alkyl group. Mono and diaryl phosphates [ie, one or two R groups are aryl groups (such as phenyl or alkyl-substituted phenyl)] may also be used.

  The reaction of the phosphate compound with the reaction product I) can proceed in an aqueous medium, optionally in the presence of an alkali metal or alkaline earth metal hydroxide, preferably at a temperature in the range of 300-100 ° C. .

When reactant II) is a sulfate compound, the reactant may be sulfuric acid or an acid sulfate salt (eg, sodium or potassium hydrogen sulfate). The sulfate compound is an organic sulfate, for example, of the formula: HR ¹ SO ₄ [wherein R ¹ is an alkyl or aryl group (such as a C ₁ -C ₂₂ alkyl group, or a phenyl or alkyl-substituted phenyl group)]. Sulfate may be used.

  The reaction of the sulfate compound with reactant I) can be carried out as described above for the phosphate compound.

  When reactant II) is a silicone compound, the silicone compound is preferably a siloxane glycidyl ether (eg, polydimethylsiloxane diglycidyl ether).

  The reaction product of reaction product I) and siloxane glycidyl ether (for example polydimethylsiloxane diglycidyl ether) as reactant II) has excellent antifoaming and wetting properties. These products suppress the generation of bubbles in electrodeposition coating compositions containing other surfactants.

Also, halosilanes, ie, the formula: X ₃ Si (SiH ₂ ) _n (SiY ₃ ) _m wherein each X is hydrogen or halogen and each Y is hydrogen or halogen; provided that at least one X or Y is halogen, n is a number from 0 to 10, and m is 0 or 1.] halosilanes may be used. The halogen is preferably chlorine, and other halogens such as bromine and iodine are also included.

  When reactant II) is an alkoxysilane or halosilane, the resulting product is a polymeric compound having excellent defoaming properties in an electrodeposition coating composition.

The reaction between the reaction product I) and the silicone compound is carried out at a temperature of 30 ° C. to 100 ° C. using a Lewis acid (eg BF ₃ etherate) in an inert organic solvent such as a liquid hydrocarbon solvent.

When reactant II) is an organic acid, the organic acid may be an aliphatic or aromatic mono- or polycarboxylic acid or anhydride. When the organic acid or anhydride is an aliphatic acid, the acid is preferably a fatty acid containing 4 to 22 carbon atoms (for example, n-butyric acid, isobutyric acid, caproic acid, etc.). Dicarboxylic acids and anhydrides include adipic acid and anhydride, malonic acid and anhydride, succinic acid and anhydride, glutaric acid and anhydride, oxalic acid and anhydride, sebacic acid and anhydride, maleic acid and anhydride, Examples include fumaric acid and anhydride. Aromatic acids and anhydrides include benzoic acid and anhydride, phthalic acid and anhydride and isomers thereof, and aliphatic acids having a phenyl substituent (phenylacetic acid and other C ₁ having a phenyl substituent on a carbon atom) -C ₂₂ and aliphatic carboxylic acid).

  The reaction between the reaction product I) and the organic acid is carried out in an aqueous medium containing an alkali or alkaline earth metal hydroxide at a temperature in the range of 300 ° C to 100 ° C.

When reactant II) is an acrylate, the acrylate is preferably of the formula: R—CH═CHCOOR ¹ wherein R is a C ₁ -C ₁₂ alkyl group and R ¹ is hydrogen or C ₁ -C ₁₂ Is an alkyl group, or the COOR ¹ group is instead an acyl halide group]. Acrylic acid, methacrylic acid and acryloyl chloride are preferred for use in the present invention.

  The reaction of reaction product I) with acrylate is carried out in an inert organic solvent such as a liquid hydrocarbon solvent at a temperature of 200-80 ° C.

When reactant II) is methylol urea (H ₂ NCONHCH ₂ OH), the reaction of methylol urea with reaction product I) is preferably carried out in an aqueous medium, preferably in the presence of hydroxides of alkali metals or alkaline earth metals. Below, it can implement at the temperature of 30 to 100 degreeC.

  If reactant II) has more than one reactive group, the reaction product which is a star surfactant can react further. For example, when reactant II) is a diisocyanate and the reaction is carried out at an equivalent ratio of 1OH: 2NCO, the resulting reaction product has one unreacted NCO group. This unreacted NCO group can then react with other reactants (such as hydroxy or amine-containing compounds) to give urethane or urea, respectively. These star-shaped surfactants have properties as polymer surfactants, are useful as surfactants with little foam formation, and as antifoaming agents.

  Commercially available products may be used as the star surfactant, for example, Foam Star W-200, Foam Star W-220, Foam Star A10, Foam Star A32, Foam Star A34, Foam Star A36, Foam Star A38. , Foam Star A12, Star Factor 20, Star Factor 30 (star-surfactant manufactured by Cognis).

  The star surfactant is 0.05 to 10% by weight, preferably 0.1 to 5% by weight, more preferably 0.5 to 3% by weight, based on the resin solid content of the electrodeposition coating composition. Preferably it is 1 weight%. If the content is less than 0.05% by weight, the defoaming effect is not sufficient, and if it exceeds 10% by weight, the effect is saturated and meaningless.

  The electrodeposition coating composition of the present invention is not particularly limited as long as it is an electrodeposition coating composition containing the above-mentioned star-shaped surfactant. For example, the above-mentioned star-shaped surfactant is added to a conventionally known electrodeposition coating composition. It may be added to prepare the electrodeposition coating composition of the present invention. The electrodeposition coating composition of the present invention may be either a cation type or an anion type, and the cationic electrodeposition coating composition is preferred from the viewpoint of providing a coating film excellent in corrosion resistance. Hereinafter, the cationic electrodeposition coating composition which is a preferred embodiment of the present invention will be described in detail.

Cationic Electrodeposition Coating Composition A preferred embodiment of the present invention includes a cationic electrodeposition coating composition comprising a star surfactant (detailed above), a cationic epoxy resin and a blocked isocyanate curing agent. Hereinafter, the cationic epoxy resin, the blocked isocyanate curing agent and other optional components contained in the cationic electrodeposition coating composition will be described in detail.

Cationic epoxy resin A typical cationic epoxy resin is an amine-modified epoxy resin. 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 of an epoxy resin 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.

  The following formula described in JP-A-5-306327

[Wherein, R independently represents a residue obtained by removing a glycidyloxy group of a diglycidyl epoxy compound, R ′ independently represents a residue obtained by removing an isocyanate group of a diisocyanate compound, and n represents a positive integer. The oxazolidone ring-containing epoxy resin represented by the above formula may be used for the preparation of an amine-modified epoxy resin to prepare an amine-modified oxazolidone ring-containing epoxy resin. This is because a coating film having excellent heat resistance and corrosion resistance can be obtained. As a method for introducing an oxazolidone ring into an epoxy resin, for example, a blocked isocyanate curing agent blocked with a lower alcohol such as methanol and a polyepoxide are heated and kept in the presence of a basic catalyst, and a lower alcohol produced as a by-product is used as a system. The method of distilling from the inside is mentioned. It is known that an epoxy resin containing an oxazolidone ring can be obtained by reacting a bifunctional epoxy resin with a diisocyanate blocked with a monoalcohol (ie, bisurethane). Specific examples and production methods of this amine-modified oxazolidone ring-containing epoxy resin are described in, for example, paragraphs 0012 to 0047 of JP-A No. 2000-128959 and are publicly known.

  The epoxy resin as a starting material is chain extended with a bifunctional polyester polyol, polyether polyol, bisphenol, dibasic carboxylic acid, etc., if necessary, before the oxirane ring-opening reaction with amines. Can be used.

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

  Examples of amines that can be used for opening an oxirane ring of an epoxy resin and introducing an amino group include butylamine, octylamine, diethylamine, dibutylamine, methylbutylamine, monoethanolamine, diethanolamine, N- Mention may be made of primary amines, secondary amines or tertiary amines such as methylethanolamine, N-ethylethanolamine, triethylamine, N, N-dimethylbenzylamine, N, N-dimethylethanolamine and / or their acid salts. it can. 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 1500 to 5000, and more preferably in the range of 1600 to 3000. 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 blocked isocyanate curing agent cationic electrodeposition coating composition contains a blocked isocyanate 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 isocyanate 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.

  A blocked isocyanate curing agent is a compound in which a free isocyanate group of an isocyanate group terminal precursor is reacted with an active hydrogen group-containing compound (blocking agent) to make it inactive at room temperature. When heated, the blocking agent dissociates. The isocyanate group is regenerated.

  Examples of the blocking agent for the blocked isocyanate curing agent include aliphatic or heterocyclic alcohols such as 1-chloro-2-propanol, n-propanol, furfuryl alcohol, and alkyl group-substituted furfuryl alcohol, phenol, m-cresol, Phenols such as p-nitrophenol, p-chlorophenol and nonylphenol, oximes such as methyl ethyl ketone oxime, methyl isobutyl ketone oxime, acetone oxime and cyclohexane oxime, active methylene compounds such as acetylacetone, ethyl acetoacetate and ethyl malonate, ε -Caprolactam, δ-valerolactam, caprolactams such as γ-butyrolactam, aliphatic alcohols such as methanol, ethanol, isopropanol, benzyl alcohol Possible aromatic alcohols, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, and the like ethers such as diethylene glycol monomethyl ether. These blocking agents may be used alone or in combination of two or more.

Pigment Further, the electrodeposition coating composition of the present invention may contain a commonly used pigment. Examples of pigments that can be used include commonly used inorganic pigments, such as colored pigments such as titanium white (titanium dioxide), carbon black and bengara; kaolin, talc, aluminum silicate, calcium carbonate, mica and clay. Extender pigments; zinc phosphate, iron phosphate, aluminum phosphate, calcium phosphate, zinc phosphite, zinc cyanide, zinc oxide, aluminum tripolyphosphate, zinc molybdate, aluminum molybdate, calcium molybdate and aluminum phosphomolybdate And anticorrosive pigments such as aluminum zinc phosphomolybdate, bismuth hydroxide, bismuth oxide, basic bismuth carbonate, bismuth nitrate, bismuth benzoate, bismuth citrate, and bismuth silicate.

  In the cationic electrodeposition coating composition of the present invention, the pigment is added to the electrodeposition coating composition in an amount of 1 to 35% by weight, preferably 2 to 30% by weight, based on the total solid content of the electrodeposition coating composition. Contained.

Pigment-dispersed paste When a pigment is used as a component of an electrodeposition coating composition, generally, the pigment is dispersed in an aqueous medium at a high concentration in advance together with a resin called a pigment-dispersed resin to form a paste. Such a paste is generally called a pigment dispersion paste.

  The pigment dispersion paste is prepared by dispersing a pigment together with a pigment dispersion resin in an aqueous medium. In general, the pigment dispersion resin is a cationic polymer such as a cationic or nonionic low molecular weight surfactant or a modified epoxy resin having a primary amino group, a quaternary ammonium group and / or a tertiary sulfonium group. Is used. As the aqueous medium, ion-exchanged water or water containing a small amount of alcohol is used. Generally, the pigment dispersion resin is used at a solid content ratio of 5 to 40 parts by weight, and the pigment is used at a solid content ratio of 10 to 30 parts by weight.

  After the pigment dispersion resin and the pigment are mixed in an amount of 10 to 1000 parts by weight with respect to 100 parts by weight of the resin solid content, a ball mill, a sand grind mill, etc. until the particle size of the pigment in the mixture reaches a predetermined uniform particle size. To obtain a pigment-dispersed paste.

Other Components The electrodeposition coating composition of the present invention may contain a dissociation catalyst for dissociating the blocking agent of the blocked isocyanate curing agent in addition to the above components. As such a dissociation catalyst, organic tin compounds such as dibutyltin laurate, dibutyltin oxide and dioctyltin oxide, amines such as N-methylmorpholine, and metal salts such as strontium, cobalt, cerium and copper can be used. The concentration of the dissociation catalyst is preferably 0.1 to 6 parts by weight based on 100 parts by weight of the total of the cationic epoxy resin and the blocked isocyanate curing agent in the cationic electrodeposition coating composition.

Preparation of cationic electrodeposition coating composition The cationic electrodeposition coating composition comprises a star-shaped surfactant, a cationic epoxy resin and a blocked isocyanate curing agent, and optionally a pigment dispersion paste in an aqueous medium (for example, deionized water, ion It can be prepared by dispersing, emulsifying or dissolving in exchanged water, general industrial water, etc. (but not particularly limited). Moreover, normally, a neutralizing agent may be contained in the aqueous medium in order to improve the dispersibility of the cationic 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 blocked isocyanate curing agent is sufficient to react with active hydrogen-containing functional groups such as primary, secondary or / and tertiary amino groups and hydroxyl groups in the cationic epoxy resin during curing to give a good cured coating film. It should be sufficient, generally expressed as a weight ratio of cationic epoxy resin to curing agent (cationic epoxy resin / curing agent), generally 90 / 10-50 / 50, preferably 80 / 20-65 / 35. Range. The binder resin containing the cationic epoxy resin and the blocked isocyanate 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 cationic electrodeposition coating composition. Contained in the product.

The coating object is not particularly limited as long as it is a metal product that can be electrodeposited.

  Examples of the material for the metal product include metals such as iron, steel, copper, aluminum, magnesium, tin, and zinc, and alloys containing these metals. Specific examples of metal products include automobile bodies such as passenger cars, trucks, motorcycles, and buses, and parts for automobile bodies. As these metal products, those subjected to chemical conversion treatment such as phosphate in advance are particularly preferable.

Electrodeposition coating formationGeneral electrodeposition coating involves the steps of immersing the object to be coated in an electrodeposition coating composition, and applying a voltage between the object to be coated and the anode to deposit a film. The process to make. The energization time varies depending on the electrodeposition conditions, but can generally be 2 to 4 minutes. As the applied voltage, a voltage of 50 to 450 V is generally applied between the object to be coated as a cathode and the anode. If the applied voltage is less than 50V, electrodeposition may be insufficient, and if it exceeds 450V, the coating film may be destroyed and an abnormal appearance may be obtained. The liquid temperature of the coating composition in the electrodeposition tank at the time of electrodeposition coating is usually adjusted to 10 to 45 ° C. The film thickness of the electrodeposition coating film is preferably 10 to 30 μm. When the film thickness is less than 10 μm, the rust prevention property is insufficient, and when it exceeds 30 μm, the paint is wasted. It hardens | cures by baking at 120-260 degreeC, Preferably it is 140-220 degreeC for 10 to 30 minutes, and a cured electrodeposition coating film is obtained.

  INDUSTRIAL APPLICABILITY The present invention can provide an electrodeposition coating composition that has foam properties and suppresses uneven drying due to the structural characteristics of the star-shaped surfactant.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated further in detail, this invention is not limited to these Examples. In the examples, “parts” means “parts by weight” unless otherwise specified.

Production Example 1 Production of amine-modified epoxy resin In a flask equipped with a stirrer, cooling tube, nitrogen introduction tube, thermometer and dropping funnel, 940 parts of liquid epoxy, 61.4 parts of methyl isobutyl ketone (hereinafter abbreviated as MIBK) and 24.4 parts of methanol were charged. The reaction mixture was heated from room temperature to 40 ° C. with stirring, and then 0.01 part of dibutyltin laurate and 21.75 parts of tolylene diisocyanate (hereinafter abbreviated as TDI) were added. The reaction was continued for 30 minutes at 40-45 ° C. The reaction was continued until the absorption based on the isocyanate group disappeared in the measurement of IR spectrum.

  To the reaction product, 82.0 parts of polyoxyethylene bisphenol A ether and 125.0 parts of diphenylmethane-4,4'-diisocyanate were added. The reaction was performed at 55 ° C. to 60 ° C. and continued until absorption based on the isocyanate group disappeared in the measurement of IR spectrum. Subsequently, the temperature was raised, 2.0 parts of N, N-dimethylbenzylamine was added at 100 ° C., held at 130 ° C., methanol was fractionated using a fractionation tube and reacted, and the epoxy equivalent was 284. .

  Thereafter, the reaction mixture was diluted with MIBK until the nonvolatile content was 95%, and 268.1 parts of bisphenol A and 93.6 parts of 2-ethylhexanoic acid were added. The reaction was performed at 120 ° C. to 125 ° C., and when the epoxy equivalent reached 1320, the reaction mixture was diluted with MIBK until the nonvolatile content was 85%, and the reaction mixture was cooled. 93.6 parts of MIBK-blocked primary amine of diethylenetriamine and 65.2 parts of N-methylethanolamine were added and reacted at 120 ° C. for 1 hour. Thereafter, an oxazolidone ring-containing modified epoxy resin having a cationic group (resin solid content: 85%) was obtained.

Production Example 2 Production of Blocked Isocyanate Curing Agent 1330 parts of crude MDI and 276.1 parts of MIBK and 2 parts of dibutyltin laurate were charged into a reaction vessel and heated to 85 to 95 ° C., and then an ethylene glycol monobutyl ether solution of caprolactam (equivalent amount) (Ratio 20/80) 1170 parts were added dropwise over 2 hours. After completion of dropping, the temperature was raised to 100 ° C. and kept for 1 hour. In the measurement of IR spectrum, it was confirmed that the absorption based on the isocyanate group had disappeared, and thereafter, 347.6 parts of MIBK was added to obtain a blocked isocyanate curing agent.

Production Example 3 Production of Pigment Dispersion Resin A reaction vessel equipped with a stirrer, a cooling pipe, a nitrogen introduction pipe and a thermometer was charged with 2220 parts of isophorone diisocyanate (hereinafter abbreviated as IPDI), 342.1 parts of MIBK, heated to dibutyl at 50 ° C. Then, 2.2 parts of tin laurate was added, and 878.7 parts of methyl ethyl ketone oxime (hereinafter abbreviated as MEK oxime) was charged at 60 ° C. Thereafter, the mixture was kept at 60 ° C. for 1 hour, and it was confirmed that the NCO equivalent was 348, and 890 parts of dimethylethanolamine was added. Incubate at 60 ° C. for 1 hour, and after confirming that the NCO peak has disappeared by IR, add 1872.6 parts of 50% lactic acid and 495 parts of deionized water while cooling so as not to exceed 60 ° C. Got. Then, 870 parts of TDI and 49.5 parts of MIBK were charged in different reaction vessels, and 667.2 parts of 2-ethylhexanol was added dropwise over 2.5 hours so as not to be 50 ° C. or higher. After the completion of dropping, 35.5 parts of MIBK was added and kept warm for 30 minutes. Thereafter, it was confirmed that the NCO equivalent was 330 to 370, and half-block polyisocyanate was obtained.

  In a reaction vessel equipped with a stirrer, a cooling tube, a nitrogen introduction tube and a thermometer, 940.0 parts of liquid epoxy and 38.5 parts of methanol were diluted, and 0.1 part of dibutyltin dilaurate was added thereto. After raising the temperature to 50 ° C., 87.1 parts of TDI was added and the temperature was further raised. At 100 ° C., 1.4 parts of N, N-dimethylbenzylamine was added, and the mixture was kept at 130 ° C. for 2 hours. At this time, methanol was fractionated by a fractionation tube. This was cooled to 115 ° C., and MIBK was charged to a solid content concentration of 90%. Then, 270.3 parts of bisphenol A and 39.2 parts of 2-ethylhexanoic acid were added and heated and stirred at 125 ° C. for 2 hours. Half block polyisocyanate 516.4 parts was added dropwise over 30 minutes, and then heated and stirred for 30 minutes. 1506 parts of polyoxyethylene bisphenol A ether was gradually added and dissolved. After cooling to 90 ° C., the above-described quaternizing agent was added, and the acid value of 2 or less was confirmed while maintaining the temperature at 70 to 80 ° C. to obtain a pigment dispersion resin. (Resin solid content 30%)

Production Example 4 Production of Pigment Dispersion Paste 106.9 parts of pigment dispersion resin obtained in Production Example 3 in a sand grind mill, 1.6 parts of carbon black, 40 parts of kaolin, 55.4 parts of titanium dioxide, aluminum phosphomolybdate 3 parts, dibutyltin oxide and 13 parts of deionized water were added and dispersed until the particle size became 10 μm or less to obtain a pigment dispersion paste (solid content 60%).

Example 1
Production of cationic electrodeposition coating composition To 100 parts of the amine-modified epoxy resin obtained in Production Example 1, 1.1 parts of Foam Star W-220 (manufactured by Cognis Co., Ltd., ethylene oxide and butylene oxide-modified star polymer) are added in advance. , Mixed. 101.1 parts of the obtained mixture and 26.6 parts of the blocked isocyanate curing agent obtained in Production Example 2 were mixed so as to be uniform. Further, 3% of 2-ethylhexyl glycol added to the resin solid content was neutralized with glacial acetic acid so that the milligram equivalent of acid per 100 g of resin solid content was 33, and further ion-exchanged water was slowly added for dilution. By removing MIBK under reduced pressure, a binder resin emulsion having a solid content of 36% was obtained.

  1730 parts of this emulsion and 295 parts of the pigment dispersion paste obtained in Production Example 4, 1970 parts of ion-exchanged water, 20 parts of 10% aqueous cerium acetate solution and 10 parts of dibutyltin oxide were mixed to obtain a solid content of 20% by weight. A cationic electrodeposition coating composition was obtained.

Comparative Examples 1-4: Preparation of Comparative Electrodeposition Coating Composition According to Example 1, instead of Foam Star W-220 (manufactured by Cognis, ethylene oxide and butylene oxide modified star polymer), EFKA-2526 (manufactured by EFKA) , Acrylic surfactant) (comparative example 1), BYK-011 (manufactured by Big Chemie, acrylic surfactant) (comparative example 2), SN-005S (manufactured by San Nopco, sucrose surfactant) (comparative) Comparative electrodeposition coating compositions 1-4 were prepared using Example 3) and DF-110D (Air Products, acetylene surfactant) (Comparative Example 4), respectively.

Electrodeposition coating method Electrodeposition coating composition obtained above from cold-rolled steel sheet (JIS G3141 standard product, 150 × 70 × 0.8 mm) subjected to zinc phosphate chemical conversion treatment (SD-5350 manufactured by Nippon Paint Co., Ltd.) The film was immersed in an object and electrodeposition-coated so that the film thickness of the dried coating film was 20 μm, which was baked and cured at 160 ° C. for 15 minutes to form an electrodeposition coating film.

  About the electrodeposition coating material composition of the Example or the comparative example, antifoaming property (foaming time), drying unevenness, and coating film appearance were evaluated. The results are shown in Table 1 below.

Defoamer Foam Star W-220: Cognis, ethylene oxide and butylene oxide modified star polymer EFKA-2526: Efka, acrylic surfactant BYK-011: Big Chemie, acrylic interface Activator SN-005S: manufactured by San Nopco, sucrose surfactant DF-110D: manufactured by Air Products, acetylene surfactant

Defoaming (defoaming time)
As evaluation of antifoaming property, the antifoaming time was measured according to the following method.
Method for Measuring Defoaming Time The electrodeposition coating compositions of the above Examples and Comparative Examples were respectively No. Pour into a 4 Ford cup and drop the paint from a height of 1 m onto a graduated cylinder (inner diameter: 5 cm). The volume (foaming amount) of foam generated at this time was measured [(foaming amount) = (capacity of foam paint + capacity of liquid paint) − (capacity of liquid paint)], and then the foam disappeared and the paint The time until the liquid level is visible is measured as defoaming time.

Dry spot
Evaluation of unevenness of drying After the electrodeposition coating according to the above-mentioned electrodeposition coating method, the steel plate is immediately pulled up from the electrodeposition coating liquid and left as it is for a predetermined time without being washed with water. After leaving, washing with water, setting, and after baking hardening for 1, 3 and 5 minutes according to the above electrodeposition coating method, dry unevenness is evaluated.
Evaluation criteria for dry spot ○: No abnormality on the entire surface (polka dots) ○: Upper 5% abnormality (polka dots)
○ △: Upper 10% abnormality (polka dot trace)
Δ: Upper 30% abnormality (polka dot trace)
Δ ×: Upper 50% abnormal (polka dot trace)
×: Full surface abnormality (polka dot trace)
The upper portion indicates the area ratio of the upper (upper) portion of the steel sheet when a cold-rolled steel sheet (JIS G3141 standard product, 150 × 70 × 0.8 mm) is pulled up from the electrodeposition coating liquid.

Appearance of coating film As the coating film appearance, the presence or absence of repellency and the presence or absence of rough skin (appearance that the coating film surface contracted) were visually determined.
Evaluation criteria for coating film appearance : 0: repellency number 0, no skin roughness △: cissing number 1-5, no skin roughness △: cissing number 1-5, skin roughness △ ×: cissing number 6-20
×: Full face repelling

  According to the present invention, it is possible to provide an electrodeposition coating composition having antifoaming properties and suppressing drying unevenness.

Claims (2)

  An electrodeposition coating composition containing a star-shaped surfactant. The star-shaped surfactant is
I) a reaction product of a reactant comprising the following (A) and (B):
(A) a binder of formula I
R ⁴ (Y) ₃ (I)
[Where:
Each Y group is a halogen atom, or one Y group is a halogen atom, the remaining two Y groups represent oxygen atoms, and are bonded to two adjacent carbon atoms of the R ⁴ group to form an epoxy group. Forming,
R ⁴ is an alkanetriyl group containing 3 to 10 carbon atoms];
(B) Compound of formula II
R ³ (EO) _n (PO) _m (BO) _p X (II)
[Where:
R ³ is a substituted or unsubstituted, saturated or unsaturated, aliphatic or araliphatic oxy or thio group having 1 to 36 carbon atoms, or a secondary amino group having 2 to 36 carbon atoms;
n is a number from 0 to 50;
m is a number from 0 to 50;
p is a number from 0 to 50, and X is hydrogen, or may be a mercapto group or an amino group];
Provided that when X is a mercapto group or an amino group, the sum of n, m and p must be at least 1,
In the above case, the molar ratio A: B of (A) and (B) is 0.2: 1 to 5: 1,
The electrodeposition coating composition according to claim 1, which is a reaction product with a reactant selected from the group consisting of II) epoxy compounds, isocyanate compounds, phosphate compounds, sulfate compounds, silicone compounds, organic acids, acrylates and methylol ureas. object.