Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L63/00—Compositions of epoxy resins; Compositions of derivatives of epoxy resins
  • C08L63/10—Epoxy resins modified by unsaturated compounds
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G18/00—Polymeric products of isocyanates or isothiocyanates
  • C08G18/003—Polymeric products of isocyanates or isothiocyanates with epoxy compounds having no active hydrogen
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G18/00—Polymeric products of isocyanates or isothiocyanates
  • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
  • C08G18/08—Processes
  • C08G18/16—Catalysts
  • C08G18/22—Catalysts containing metal compounds
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G18/00—Polymeric products of isocyanates or isothiocyanates
  • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
  • C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
  • C08G18/2805—Compounds having only one group containing active hydrogen
  • C08G18/2815—Monohydroxy compounds
  • C08G18/283—Compounds containing ether groups, e.g. oxyalkylated monohydroxy compounds
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G18/00—Polymeric products of isocyanates or isothiocyanates
  • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
  • C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
  • C08G18/30—Low-molecular-weight compounds
  • C08G18/32—Polyhydroxy compounds; Polyamines; Hydroxyamines
  • C08G18/3203—Polyhydroxy compounds
  • C08G18/3206—Polyhydroxy compounds aliphatic
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G18/00—Polymeric products of isocyanates or isothiocyanates
  • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
  • C08G18/70—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the isocyanates or isothiocyanates used
  • C08G18/72—Polyisocyanates or polyisothiocyanates
  • C08G18/74—Polyisocyanates or polyisothiocyanates cyclic
  • C08G18/76—Polyisocyanates or polyisothiocyanates cyclic aromatic
  • C08G18/7657—Polyisocyanates or polyisothiocyanates cyclic aromatic containing two or more aromatic rings
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G18/00—Polymeric products of isocyanates or isothiocyanates
  • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
  • C08G18/70—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the isocyanates or isothiocyanates used
  • C08G18/72—Polyisocyanates or polyisothiocyanates
  • C08G18/80—Masked polyisocyanates
  • C08G18/8061—Masked polyisocyanates masked with compounds having only one group containing active hydrogen
  • C08G18/8064—Masked polyisocyanates masked with compounds having only one group containing active hydrogen with monohydroxy compounds

Definitions

• the present invention relates to a cationic electrodeposition resin composition
• a cationic electrodeposition resin composition comprising 30 to 80 parts by weight of a base resin containing a reaction product of sulfide compound and epoxy compound and a reaction product of amine compound and epoxy compound; and 20 to 70 parts by weight of a crosslinking agent resin.
• Electrodeposition paints were introduced in 1970's and applied as anti-corrosion paints for various industries based on automobile industry, and have been widely used for various parts as well as automobile frames because of their effectiveness, uniformity and friendliness to environment.
• Electrodeposition resin which is a main component of electrodeposition paint, is the most important component determining the overall properties of paint.
• Electrodeposition resin generally comprises a base resin and a crosslinking agent resin, and may comprise a curing catalyst.
• Epoxy resin is a representative for base resins used in cationic electrodeposition.
• a crosslinking agent resin capped polyisocyanate is mainly used.
• conventional cationic electrodeposition resins are produced according to a process of mixing an epoxy resin having 180 to 10,000 equivalents in amount of 10 to 90% based on solid content, with bisphenol-A and derivatives thereof or a plasticizer such as modified polyether; reacting amine and diol at 70 to 170 ° C in the presence of excessive solvent; and removing organic solvent contained in the reaction mixture at high temperature by vacuum recovery process; mixing a crosslinking agent resin to the solvent-removed mixture; neutralizing the mixture sufficiently with an organic acid such as formic acid, lactic acid or acetic acid; and dispersing the mixture in water by adding deionized water for 4 to 12 hours.
• an organic acid such as formic acid, lactic acid or acetic acid
• Japanese laid-open publication No. S54-25940 uses a compound containing polysulf ⁇ de bond in order to enhance corrosion resistance, describing an electrodeposition resin composition wherein a polysulfide compound is not reacted with an epoxy compound but reacted with an acid compound during production process or in coating formation procedure at high temperature after simple addition.
• a polysulfide compound is not reacted with an epoxy compound but reacted with an acid compound during production process or in coating formation procedure at high temperature after simple addition.
• the effect of improving corrosion resistance is unsatisfactory.
• US patent No. 4,771,087 describes an electrodeposition resin comprising a capped polyisocyanate curing agent containing hydroxyl and primary or secondary amine to improve curing property, more specifically, wherein a composition containing 20 to 70 % of polyether polyol or 0 to 70 % of phenol diglycidyl ether, comprises an intermediate obtained by reacting epoxy resin having 180 to 10,000 equivalents to give 360 to 20,000 epoxy equivalents at 120 to 200 " C and one or more secondary phenol. The adduct of polyether polyol and epoxy is useful as binder.
• an intermediate containing polyether polyol component is applied to a conventional bisphenol-A type epoxy resin in amount of 10 to 90 %, excellent flexibility can be obtained with showing good mechanical properties, compared with an epoxy resin composition without polyether polyol component.
• the polyether polyol tends to show low resistances to water and corrosion because of its own characteristics.
• Japanese laid-open publication Nos. H4-91170 and H5- 155980 use a polyamide resin as a base resin in order to enhance corrosion resistance and curing property of edge, but have problems such as appearance deterioration and lack of flexibility since the polyamide resin increases the crosslinking rate during the formation of coating layer.
• a plasticizer is co-used to resolve such problem, but the plasticizer causes another problem of lowering resistance to water and corrosion.
• the present inventors have developed a cationic electrodeposition resin composition comprising a base resin containing a reaction product of sulfide compound and epoxy compound with good smoothness and flexibility of coating.
• the present inventors have also developed a cationic electrodeposition resin composition preferably comprising a crosslinking agent resin containing a reaction product of glycidyl ether- amine derived polyol compound and capped polyisocyanate.
• the present inventors have also developed a cationic electrodeposition resin composition preferably comprising a curing catalyst resin containing barium metal suitable to adjust curing rate.
• the cationic electrodeposition resin composition according to the present invention can be produced by using conventional production facilities, not specially- designed facilities and can improve smoothness, corrosion resistance and flexibility.
• the purpose of the present invention is to provide a high- functional cationic electrodeposition resin composition having improved smoothness, corrosion resistance and flexibility.
• the present invention relates to a cationic electrodeposition resin composition
• a cationic electrodeposition resin composition comprising 30 to 80 parts by weight of a base resin containing a reaction product of sulfide compound and epoxy compound and a reaction product of amine compound and epoxy compound; and 20 to 70 parts by weight of a crosslinking agent resin.
• an electrodeposition resin comprises a base resin and a crosslinking agent resin.
• the base resin for general electrodeposition resin is a component constituting a final coating layer together with a crosslinking agent resin.
• the characteristics of the final coating layer are determined according to the chemical and physical properties of the base resin.
• Epoxy compound is mostly used as main component of the base resin since it provides the final coating layer with good corrosion resistance, adhesion property and heat resistance.
• the epoxy compound reacts with amine compound to provide hydroxyl groups which are necessary for the reaction with dissociated isocyanate groups of curing agent in coating process.
• Epoxy compounds particularly have good corrosion resistance, and so are most generally used in a coating of materials requiring corrosion resistance.
• general epoxy resins have a demerit of low flexibility.
• the base resin used in the present invention contains a reaction product of sulfide compound and epoxy compound, and a reaction product of amine compound and epoxy compound.
• the base resin in the present invention contains a reaction product of sulfide compound and epoxy compound, and so improves the smoothness and flexibility of coating layer.
• the sulfide compound used in the present invention is a compound having two or more mercaptan groups.
• the molecular weight of the sulfide compound is 150 to 8,500, preferably 300 to 5,000, and more preferably 500 to 2,000. If the molecular weight of the sulfide compound is less than 150, the flexibility becomes insufficient and so chipping and mechanical properties become lowered. Jf the molecular weight is greater than 8,500, there is a problem of gellation during reaction or storage due to high viscosity and high molecular weight of final product.
• the preferable sulfide compound in the present invention is, but not limited thereto, one or more compounds selected from the group consisting of compounds of the following Formula 1.
• n represents an integer of 0 to 50.
• the preferable molecular weight of the epoxy compound which reacts with the sulfide compound and the amine compound explained below is 180 to 2,000, more preferably 180 to 1,500, and still more preferably 180 to 1,000. If the molecular weight of the epoxy compound is less than 180, the flexibility and corrosion resistance may become insufficient. If the molecular weight is greater than 2,000, there may be a difficulty in handling during production process due to high viscosity.
• the preferable epoxy compound in the present invention is, but not limited thereto, independently one or more compounds selected from the group consisting of (i) a compound of the following Formula 2; (ii) a mixture of compounds of the following Formulas 2 and 3; and (iii) a reaction product of a compound of the following Formula 4 and one or more of aforesaid (i) and (ii).
• R3 represents Ci 7-35 phenolic ether.
• aryl means an aromatic ring such as phenyl or naphthalene.
• the compounds of the Formulas 2 to 4 are the following Formulas 5 to 7, respectively.
• the preferable reaction product of sulfide compound and epoxy compound in the present invention comprises, but not limited thereto, a compound of the following Formula 8 or 9.
• Rl represents Ci -20 alkyl
• R2 represcnis C 1 - 5 alkyl
• R3 represents Cn -3 phenolic ether
• n represents an integer of O to 50.
• the more preferable reaction product of sulfide compound and epoxy compound in the present invention comprises a compound of the following Formula 10 or 11.
• R2 represents Ci -5 alkyl and n represents an integer of O to 50.
• R2 represents Ci -5 alkyl and m represents an integer of O to 6.
• each compound of the Formulas 8 to 11 may be present in a form independently combined with other sulfide compound or epoxy compound.
• the amine compound which reacts with the epoxy compound to be used in a base resin for electrodeposition resin composition, is well known in this field of art.
• the preferable amine compound in the present invention is, but not limited thereto, one or more compounds independently selected from the group consisting of HO-R5-NH-R5- OH and (CH 3 ) 2 N-R5-NH 2 where each R5 independently represents C] -8 alkyl.
• the amount of the sulfide compound is preferably 10 to 30 % by weight, more preferably 10 to 25 % by weight, and still more preferably 10 to 20 % by weight, based on the base resin.
• the amount of the sulfide compound is less than 10 % by weight, the improvement in smoothness, flexibility and corrosion resistance of coating may become insufficient. If the amount of the sulfide compound is greater than 30 % by weight, there may be a difficulty in handling due to high viscosity of the reaction product.
• the amount of the epoxy compound is preferably 40 to 80 % by weight, more preferably 50 to 80 % by weight, and still more preferably 60 to 80 % by weight, based on the base resin. If the amount of the epoxy compound is less than 40 % by weight, the curing property and corrosion resistance of coating may be lowered due to deficiency of hydroxyl groups which are necessary for the reaction with the crosslinking agent resin.
• the amount of the epoxy compound is greater than 80 % by weight, there may be a difficulty in handling due to high viscosity of the reaction product, and the flexibility and weatherability of the coating may also be lowered.
• the amount of the amine compound is preferably 10 to 30 % by weight, more preferably 10 to 25 % by weight, and still more preferably 10 to 20 % by weight, based on the base resin. If the amount of the amine compound is less than 10 % by weight, the curing property and corrosion resistance of coating may be lowered due to deficiency of hydroxyl groups which are necessary for the reaction with the crosslinking agent resin.
• the amount of the reaction product of sulfide compound and epoxy compound is preferably 30 to 70 % by weight, more preferably 30 to 50 % by weight, and still more preferably 30 to 40 % by weight, based on the base resin. If the amount of the reaction product of sulfide compound and epoxy compound is less than 30 % by weight, the improvement in flexibility and corrosion resistance of coating may become insufficient. If the amount of the reaction product of sulfide compound and epoxy compound is greater than 70 % by weight, there may be a difficulty in handling due to high viscosity of the reaction product.
• the amount of the reaction product of amine compound and epoxy compound is preferably 30 to 70 % by weight, more preferably 50 to 70 % by weight, and still more preferably 60 to 70 % by weight, based on the base resin. If the amount of the reaction product of amine compound and epoxy compound is less than 30 % by weight, the improvement in smoothness, flexibility and corrosion resistance of coating may become insufficient. If the amount of the reaction product of amine compound and epoxy compound is greater than 70 % by weight, the reaction stability and storage stability of the final electrodeposition resin may be lowered.
• the amount of the base resin used in the cationic electrodeposition resin composition according to the present invention is 30 to 80 parts by weight, preferably 50 to 75 parts by weight, and more preferably 60 to 70 parts by weight. If the amount of the base resin is less than 30 parts by weight, the smoothness, flexibility and corrosion resistance decrease. If the amount of the base resin is greater than 80 parts by weight, the curing property becomes problematic.
• Crosslinking agent resin
• Electrodeposition resins generally comprise a base resin and a crosslinking agent resin, and may comprise a curing catalyst.
• the crosslinking agent resin reacts with the base resin and forms final coating layer. More specifically, isocyanate groups contained in the crosslinking agent resin react with hydroxyl groups contained in the base resin at given temperature or higher to form a stable coating layer.
• a crosslinking agent resin having capped isocyanate system is used and forms a coating layer together with the component in the base resin by urethane reaction at a higher temperature than the given temperature, providing functions such as good curing property, corrosion resistance, water resistance, etc.
• the crosslinking agent resin used in the present invention contains a reaction product of glycidyl ether-amine derived polyol compound and capped polyisocyanate compound; 30 to 80 parts by weight of a base resin, and the glycidyl ether-amine derived polyol compound is derived from a Mannich reaction product of phenol compound, amine compound and formalin.
• Mannich reaction is a reaction between aldehyde group-containing compound, primary or secondary amine compound, and phenol compound.
• a composition comprising active hydrogen of amine compound through Mannich reaction is widely used as low-temperature curing agent for conventional epoxy paints. It has been known that if such Mannich reaction product comprising active hydrogen of amine compound is introduced into an epoxy curing agent, good curing property is obtained at room temperature and low-temperature.
• Mannich modified glycidyl ether-amine derived polyol type compound containing reactive hydroxyl group is preferably used, which is obtained by removing active hydrogen of amine compound from a Mannich reaction product and through further reaction after Mannich reaction and so may have various structures and applications.
• the present invention introduces the glycidyl ether-amine derived polyol compound into the crosslinking agent resin in the electrodeposition resin composition and induces a urethane reaction with isocyanate group to obtain a coating of good curing property. As a result, the present invention can improve the corrosion resistance.
• the phenol compound used in Mannich reaction may be selected, but not limited thereto, from the group consisting of cresol, butyl phenol, octyl phenol, nonyl phenol and phenol, preferably from the group consisting of octyl phenol, nonyl phenol and phenol, and more preferably from the group consisting of nonyl phenol and phenol.
• the phenol compound can be used alone or in mixture of two compounds selected from the above group.
• the amine compound used in Mannich reaction is preferably aliphatic or aromatic amine compound, more preferably selected from the group consisting of ethylene diamine, trimethylene diamine, hexamethylene diamine, octamethylene diamine, diethyl ene triamine, triethylene tetramine, tetraethylene pentamine and metaxylene diamine.
• the amine compound can be used alone or in mixture of two or more compounds selected from the above group.
• the amount of the phenol compound used in Mannich reaction is 20 to 50 % by weight, preferably 25 to 45 % by weight, and more preferably 30 to 40 % by weight, based on the amount of Mannich reaction product. If the amount of the phenol compound is less than 20 % by weight, corrosion resistance may be lowered. If the amount of the phenol compound is greater than 50 % by weight, viscosity and degree of curing may be increased excessively.
• the amount of the amine compound used in Mannich reaction is 20 to 50 % by weight, preferably 25 to 45 % by weight, and more preferably 30 to 40 % by weight, based on the amount of Mannich reaction product.
• the amount of the amine compound is less than 20 % by weight, unreacted material remains in the reaction product and so sufficient coating properties may not be obtained. If the amount of the amine compound is greater than 50 % by weight, urea functional groups are formed and so insoluble particles may be generated during or after the reaction.
• the amount of the formalin used in Mannich reaction is 15 to 45 % by weight, preferably 20 to 40 % by weight, and more preferably 25 to 35 % by weight, based on the amount of Mannich reaction product. If the amount of the formalin is less than 15 % by weight, unreacted amine may be generated in large quantity. If the amount of the formalin is greater than 45 % by weight, there is a risk of gellation since viscosity may be increased excessively.
• Mannich reaction product may be produced according to the phenol compound and the amine compound.
• Preferable Mannich products have, but not limited thereto, a structure of the following Formula 12.
• each of R6 independently represents phenol compound, preferably cresol, butyl phenol, octyl phenol, nonyl phenol or phenol.
• the glycidyl ether-amine derived polyol compound used in the crosslinking agent resin is a reaction product of Mannich reaction product, hydroxyl-containing amine compound and glycidyl ether compound.
• the hydroxyl-containing amine compound is preferably hydroxyl-containing aliphatic or aromatic amine compound, more preferably selected from the group consisting of monoethanolamine, diethanolamine, monoisopropanolamine, diisopropanolamine, monoethylethanolamine and monomethylethanolamine, and still more preferably selected from the group consisting of ethyl ethanolamine and methyl ethanolamine.
• the glycidyl ether compound is preferably selected from the group consisting of phenyl glycidyl ether and butyl glycidyl ether.
• the amount of the hydroxyl-containing amine compound is 8 to 30 parts by weight, preferably 11 to 27 parts by weight, and more preferably 14 to 24 parts by weight, based on 100 parts by weight of total solid weight of the Mannich reaction product. If the amount of the hydroxyl-containing amine compound is less than 8 parts by weight, reactive terminal hydroxyl groups are not sufficient and so the curing reaction with isocyanate groups may not be conducted fully. If the amount of the hydroxyl- containing amine compound is greater than 30 parts by weight, stability of the reaction product may be lowered.
• the amount of the glycidyl ether compound is 40 to 70 parts by weight, preferably 44 to 64 parts by weight, and more preferably 48 to 60 parts by weight, based on 100 parts by weight of total solid weight of the Mannich reaction product.
• Preferable glycidyl ether-amine derived polyol compounds derived from Mannich reaction product useful in the present invention have, but not limited thereto, a structure of the following Formula 13.
• each of R6 independently represents phenol compound, preferably cresol, butyl phenol, octyl phenol, nonyl phenol or phenol; each of R7 independently represents glycidyl ether compound, preferably butyl glycidyl ether or phenyl glycidyl ether; and R8 represents hydroxyl-containing amine compound, preferably monoethanolamine, diethanolamine, monoisopropanolamine, diisopropanolamine, monoethylethanolamine or monomethylethanolamine.
• the amount of the glycidyl ether-amine derived polyol compound used to the crosslinking agent resin in the present invention is 1 to 20 % by weight, preferably 1 to 10 % by weight, and more preferably 1 to 5 % by weight, based on amount of the crosslinking agent resin. If the amount of the glycidyl ether-amine derived polyol compound is less than 1 % by weight, effect of improving curing property is not sufficient. If the amount of the glycidyl ether-amine derived polyol compound is greater than 20 % by weight, the appearance may be deteriorated due to increased viscosity and fast initial curing.
• the capped polyisocyanate which can react with the glycidyl ether-amine derived polyol compound containing Mannich reaction product according to the present invention, can be selected freely from those known as useful to cationic electrodeposition resin composition.
• the capped polyisocyanate is preferably, but not limited thereto, a reaction product of diisocyanate compound and hydroxyl-containing acrylate compound or alcohol compound.
• the amount of the capped polyisocyanate is 80 to 99 % by weight, preferably 90 to 99 % by weight, and more preferably 95 to 99 % by weight, based on the amount of the crosslinking agent resin. If the amount of the capped polyisocyanate is less than 80 % by weight, there may be a problem of uncuring. If the amount of the capped polyisocyanate is greater than 99 % by weight, the curing becomes faster but the corrosion resistance may be lowered.
• the diisocyanate compound is preferably aliphatic or aromatic diisocyanate compound, and more preferably selected from the group consisting of 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 4,4'-methylene bis(phenyl diisocyanate), tetramethylene diisocyanate and hexamethylene diisocyanate.
• the hydroxyl-containing acrylate compound is preferably 2-hydroxyethyl methacrylate.
• the alcohol compound is preferably selected from the group consisting of ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, trimethylol propane and propylene glycol.
• the amount of the crosslinking agent resin used in the cationic electrodeposition resin composition according to the present invention is 20 to 70 parts by weight, preferably 25 to 50 parts by weight, and more preferably 30 to 40 parts by weight. If the amount of the crosslinking agent resin is less than 20 parts by weight, the curing temperature increases and the corrosion resistance decreases according to uncuring. If the amount of the crosslinking agent resin is greater than 70 parts by weight, the appearance is deteriorated because of high curing density, and the corrosion resistance decreases because of lack of epoxy ingredient in main material.
• the present electrodeposition resin composition separately comprises a curing catalyst resin containing curing catalyst.
• a metal used as a curing catalyst is independently added to an electrodeposition resin, the reaction stability, storage stability, filtering property and the like of the electrodeposition resin become lowered.
• Such problems of lowering the reaction stability, storage stability, filtering property and the like can be resolved by preparing a curing catalyst resin containing metal salt or metal chelate as curing catalyst independently and adding it to electrodeposition resin.
• the function of curing catalyst is to enhance a reaction of hydroxyl groups in the base resin and isocyanate gioups in the crosslinking agent resin.
• the curing catalyst can be selected properly to lower the reaction temperature.
• the cationic electrodeposition resin composition according to the present invention preferably comprises a curing catalyst resin containing metal, in order to control the curing rate.
• the metal used to the curing catalyst resin may be selected from the group consisting of zirconium, zinc, calcium, lead, tin, bismuth, cobalt, titanium, aluminum, chrome and barium, and the metal may be present in salt or chelate form. More preferably, the metal salt or metal chelate is barium hydroxide, phenol-barium salt or phenol-barium chelate. Still more preferably, the curing catalyst resin containing metal contains phenol-barium salt or phenol-barium chelate.
• the amount of the metal used to the curing catalyst resin is 1 to 20 % by weight, preferably 3 to 15 % by weight, and more preferably 5 to 10 % by weight, based on the amount of the curing catalyst resin. If the amount of the metal is less than 1 % by weight, the curing property is not sufficient. If the amount of the metal is greater than 20 % by weight, the curing rate becomes too fast and the appearance becomes deteriorated.
• the amount of the curing catalyst resin containing metal used in the cationic electrodeposition resin composition according to the present invention is 0.1 to 10 parts by weight, preferably 0.1 to 7 parts by weight, and more preferably 0.1 to 5 parts by weight, based on 100 parts by weight of total amount of the base resin and the crosslinking agent resin. If the amount of the curing catalyst resin containing metal is less than 0.1 parts by weight, the temperature required for the reaction of hydroxyl groups in the base resin and isocyanate groups in the crosslinking agent resin is elevated, resulting in cost increase due to additional energy consumption. If the amount of the metal is greater than 10 parts by weight, the content of curing catalyst becomes greater than appropriate amount required for the reaction, and so there may be a problem in storage stability due to the increase of precipitation amount of the curing catalyst during storage of electrodeposition resin.
• a glycidyl ether-amine derived polyol compound derived from a Mannich reaction product was prepared from the components shown in TABLE 1 according to the process explained below.
• the reaction mixture was cooled to 110 ° C , and diluted with methoxypropanol (G) to terminate the reaction.
• the reaction was conducted carefully since the reaction mixture tended to boil up during the reaction.
• the product obtained as above had a solid content of 70 %.
• a crosslinking agent resin used in the present invention was prepared from the components shown in TABLE 2 according to the process explained below.
• the reaction mixture was cooled to 80 ° C or less by natural cooling manner with diluting with methoxypropanol (F) to complete the preparation process. During the reaction, the temperature of the reaction mixture was controlled to be 85 ° C or less.
• the prepared resin had a solid content of 85 %.
• a general crosslinking agent resin used in the present invention was prepared from the components shown in TABLE 3 according to the process explained below.
• Example 4 As a curing catalyst resin containing metal, a phenol-barium salt resin was prepared from the components shown in TABLE 4 according to the process explained below.
• a reaction product of a base resin containing a reaction product of sulfide compound and epoxy compound and a general crosslinking agent resin was prepared from the components shown in TABLE 5 according to the process explained below.
• Neodecanoic acid glycidyl ester having terminal epoxy group (Molecular weight: 240; Resolution Co., Ltd.)
• Example 3 The reaction product of Example 3 (G) was added at 110 ° C and the reaction mixture was maintained for 30 minutes. With cooling the reaction mixture by adding and mixing formic acid (H) and deionized water (I), the deionized water (J) was added slowly for 3 hours to disperse the reaction mixture in water. During the dispersion step, the reaction mixture was cooled to 50 ° C or less by occasional injection of cooling water since the higher temperature than 50 ° C for a long time decreased the stability of water dispersion. After completing the dispersion step, nitrogen was injected for 10 minutes to remove air bubbles in the reaction mixture, and the reaction mixture was kept for 2 hours. In the above process, since exothermic reaction heat after the amine addition was generated vigorously, the temperature elevation was controlled in consideration of such spontaneous heat generation. The product obtained as above had a solid content of 36 %.
• a cationic electrodeposition resin composition comprising a general base resin and a crosslinking agent resin containing a glycidyl ether-amine derived polyol derived from a Mannich reaction product, was prepared from the components shown in TABLE 6 according to the process explained below. [TABLE 6]
• a cationic electrodeposition resin composition comprising a base resin containing a reaction product of sulfide compound and epoxy compound and a crosslinking agent resin containing a glycidyl ether-amine derived polyol derived from a Mannich reaction product, was prepared from the components shown in TABLE 7 according to the process explained below.
• Example 2 The reaction product of Example 2 (G) was added at 110 ° C and the reaction mixture was maintained for 30 minutes. With cooling the reaction mixture by adding and mixing formic acid (H) and deionized water (I), the deionized water (J) was added slowly for 3 hours to disperse the reaction mixture in water. During the dispersion step, the reaction mixture was cooled to 50 ° C or less by occasional injection of cooling water since the higher temperature than 50 ° C for a long time decreased the stability of water dispersion. In the above process, since exothermic reaction heat after the amine addition was generated vigorously, the temperature elevation was controlled in consideration of such spontaneous heat generation. The prepared resin had a solid content of 36 %.
• a cationic electrodeposition resin composition comprising a base resin containing a reaction product of sulfide compound and epoxy compound and the phenol-barium salt resin of Example 4 as curing catalyst resin, was prepared from the components shown in TABLE 8 according to the process explained below.
• Neodecanoic acid glycidyl ester having terminal epoxy group (Molecular weight: 240; Resolution Co., Ltd.)
• Example 3 The reaction product of Example 3 (G) was added at 110 ° C and the reaction mixture was maintained for 30 minutes. With cooling the reaction mixture by adding and mixing formic acid (H) and deionized water (I), the reaction product of Example 4 (J) was added and the deionized water (K) was added slowly for 3 hours to disperse the reaction mixture in water. During the dispersion step, the reaction mixture was cooled to 50 ° C or less by occasional injection of cooling water since the higher temperature than 50 ° C for a long time decreased the stability of water dispersion. In the above process, since exothermic reaction heat after the amine addition was generated vigorously, the temperature elevation was controlled in consideration of such spontaneous heat generation. The prepared resin had a solid content of 36 %.
• a cationic electrodeposition resin composition comprising a base resin containing a reaction product of sulfide compound and epoxy compound, the crosslinking agent resin of Example 2 containing a glycidyl ether-amine derived polyol derived from a Mannich reaction product and the phenol-barium salt resin of Example 4 as curing catalyst resin, was prepared from the components shown in TABLE 9 according to the process explained below.
• Neodecanoic acid glycidyl ester having terminal epoxy group (Molecular weight: 240; Resolution Co., Ltd.)
• Example 2 The reaction product of Example 2 (G) was added at 110 ° C and the reaction mixture was maintained for 30 minutes. With cooling the reaction mixture by adding and mixing formic acid (H) and deionized water (I), the reaction product of Example 4 (J) was added and the deionized water (K) was added slowly for 3 hours to disperse the reaction mixture in water. During the dispersion step, the reaction mixture was cooled to 50 ° C or less by occasional injection of cooling water since the higher temperature than 50 ° C for a long time decreased the stability of water dispersion. In the above process, since exothermic reaction heat after the amine addition was generated vigorously, the temperature elevation was controlled in consideration of such spontaneous heat generation. The prepared resin had a solid content of 36 %.
• reaction product of a general base resin and a general crosslinking agent resin was prepared from the components shown in TABLE 10 according to the process explained below.
• each cationic electrodeposition resin composition was prepared by homogeneously mixing the cationic electrodeposition resin obtained according to Examples 5 to 9 and Comparative Example 1 , respectively, with a pigment paste composition in a mixing ratio of 4 to 1 for 24 hours.
• the pigment paste composition used in the preparation of the cationic electrodeposition resin compositions was prepared according to the process explained below.
• YD-128 which is a liquid epoxy resin
• 290 parts by weight of bisphenol-A, 89 parts by weight of dimethylethanolamine and 260 parts by weight of polymethylene polyphenyl isocyanate were added, and reacted at 150 ° C for 2 hours.
• 80 parts by weight of acetic acid was added and the reaction mixture was diluted with 300 parts by weight of deionized water to produce a pigment dispersion resin.
• Electrodeposition coatings were performed with static voltage of 300V for 2 minutes on a cold roll steel sheet (90mm X 200mm) which had been surface-treated with zinc phosphate-based surface-treating agent, by using the cationic electrodeposition coating compositions of Examples 10 to 14 and Comparative Example 2, respectively.
• the coating layer formed was rinsed with water, and baked in an oven at 160 ° C for 20 minutes to form a coating layer of uniform thickness.
• the obtained electrodeposition coating was tested, and the test results of the coating properties are shown in TABLE 11 below.
• MIBK Rubbing The coating to be tested was rubbed with a fabric or tissue dipped in a solvent (methyl isobutyl ketone) until the coating was damaged. "20 times or more" means that the coating was undamaged by at least 20 times of rubbing, indicating that the coating was cured.
• the cationic electrodeposition paints containing the water- dispersion resin according to the present invention exhibited improved coating characteristics, as compared with that of Comparative Example 2 which was a IT) conventional art.
• As measurement items for indicating smoothness of coating larger value of Gloss and smaller value of Ra mean better smoothness of coating.
• the gloss values of Examples 10 to 14 are larger than that of Comparative Example 2 and the roughness values of Examples 10 to 14 are smaller than that of Comparative Example 2, which means that the smoothness of the coating according to the present invention is relatively better than conventional one.
• the measured values of Impact and Cupping indicate flexibility of the coating. Larger values of Impact and Cupping mean better flexibility of coating.
• the measured values of Impact and Cupping of Examples 10 and 12 to 14 are larger than those of Comparative Example 2, which means that the flexibility of the coating according to the present invention is relatively better than conventional one.
• the number of MIBK Rubbing indicates curing property of the coating. It was confirmed that the coatings of Examples 10 to 14 and Comparative Example 2 exhibited equivalent curing property.
• Corrosion resistance is evaluated by the salt mist test. Smaller value of salt mist test result means better corrosion resistance. As shown in TABLE 11, Examples 10 to 14 exhibited better corrosion resistance than Comparative Example 2. Therefore, it was confirmed that the coating formed from the cationic electrodeposition resin composition according to the present invention has better smoothness, corrosion resistance and flexibility, as compared with a coating formed from conventional electrodeposition resin composition.
• the present invention relates to a high-functional cationic electrodeposition resin composition having improved smoothness, corrosion resistance and flexibility.
• the present composition which comprises a base resin containing a reaction product of sulfide compound and epoxy compound in addition to a conventional epoxy-amine reaction product and preferably further comprises a crosslinking agent resin containing a reaction product of glycidyl ether-amine derived polyol compound derived from Mannich reaction product and capped polyisocyanate compound or a curing catalyst resin containing metal, can provide improved smoothness, corrosion resistance and flexibility of coating, compared with a conventional cationic electrodeposition resin composition.

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• 2006
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