The problem that quasi-solution of the present invention is determined
The purpose of this invention is to provide a kind of pitting of particularly not having, the low-temperature stiffening that the scuff resistance of hardened coating film is good, transparent electrodeposition coating composition.
Solve the way of this problem
The present invention adopts acid number and hydroxyl value high, thereby seeks the solution of above-mentioned problem as the acrylic resin that constitutes the coating resin composition principal constituent.
That is, the present invention relates to contain the transparent electrodeposition coating composition of resin combination, contain in this resin combination: the hydrophilic melamine resin a) acrylic resin of the hydroxyl of the carboxyl of acid number 70~130mgKOH/g and hydroxyl value 90~160mgKOH/g, and b).Above-mentioned a) acrylic resin and b) ratio (weight ratio) of wetting ability melamine resin is 60~80: 40~20 (they are benchmark with the solids component, down with).
The present invention be more particularly directed to above-mentioned transparent electrodeposition coating composition, wherein, the wetting ability melamine resin is that the mol ratio of methoxyl group/butoxy is the melamine resin of methyl/butyl mixed ether modification of 6/4~9/1.
In addition, the above-mentioned transparent electrodeposition coating composition that the present invention relates to, its concentration that is dispersed in the resin combination in the aqueous solvent is that 5~20 weight % constitute.
In addition, the present invention relates to the above-mentioned transparent method of electrodeposition coating composition cataphoretic coating on conductive substrate.
Being particularly related to conductive substrate is the cataphoretic coating method of aluminium.
Embodiment of the present invention
One of feature of electrodeposition coating composition of the present invention is to have low-temperature stiffening, yet so-called low-temperature stiffening of the present invention means below 180 ℃, particularly presents hardenability about 4H~5H after 30 minutes at the temperature sintering below 160 ℃.
Electrodeposition coating composition of the present invention is the acrylic resin with hydroxyl of the carboxyl of acid number 70~130mgKOH/g and hydroxyl value 90~160mgKOH/g as the acrylic resin of the resin combination principal constituent of coating.
In the present invention, so-called acid number, the mg number of the contained needed potassium hydroxide of carboxyl in meaning and among the acrylic resin 1g.In addition, so-called hydroxyl value means the mg number to the needed acetic acid neutral of acrylic resin 1g acetylize potassium hydroxide.
Constitute the acrylic resin in the resin combination of coating composition of the present invention, as long as its acid number and hydroxyl value are in the above-mentioned scope, and be not particularly limited, more preferably acid number 80~120mgKOH/g, hydroxyl value 100~150mgKOH/g.
In addition, the weight-average molecular weight of acrylic resin, preferred 5000~100000, preferred especially 10000~70000.Measuring of the molecular weight distribution of representing with the ratio of weight-average molecular weight and number-average molecular weight, preferred 1~6, more preferably 1~4.The acrylic resin molecular weight is 5000 when following, the emulsion instability, and when greater than 10000 the time, the mobile variation that electrophoresis is filmed.
The acrylic resin that is cooperated in all resins composition solid composition in coating is 60~80 weight %, is preferably 65~75 weight %.When the content of acrylic resin is less than 60 weight %, can't obtain surface hardness and the coating good to the binding property of base material.On the other hand, when greater than 80 weight %, the amount of stiffening agent tails off relatively, can't obtain all good the filming of weathering resistance, water tolerance and surface hardness.
As the polymerizable monomer that is used for importing carboxyl to acrylic resin, can be selected from following monomer: the polymerisable α of ethene such as vinylformic acid, methacrylic acid, toxilic acid, maleic anhydride, fumaric acid, toxilic acid monoesters, methylene-succinic acid, methylene-succinic acid monoesters, Ba Dousuan, methyl-maleic acid, β-unsaturated fatty acids and their mixture.
Import carboxyl, make the acid number of acrylic resin reach 70~130mgKOH/g, preferred 80-120mgKOH/g.Be lower than at 70 o'clock at acid number, lose low-temperature stiffening, the physical properties of filming, particularly hardness after the sclerosis are not really high.In addition, when acid number during greater than 130mgKOH/g, the water tolerance of filming becomes bad, is not preferred.
The purpose that imports hydroxyl toward acrylic resin is to improve and intermiscibility as the melamine resin of stiffening agent, to improve reactivity.In addition, be used to improve degree of crosslinking and scuff resistance.In order to import hydroxyl, also can with the polymerizable monomer with hydroxyl, for example, the monomer that is selected from beta-hydroxyethyl (methyl) acrylate, hydroxypropyl (methyl) acrylate, vinyl carbinol, hydroxyl butyl (methyl) acrylate, trade mark プ ラ Network セ Le FM1~5 (ダ イ セ Le chemistry) and their mixture carries out copolymerization.
Import hydroxyl in the acrylic resin of the present invention, make hydroxyl value reach 90~160mgKOH/g, preferably reach 100~150mgKOH/g.When hydroxyl value is lower than 90mgKOH/g, sclerous reaction can not fully take place, hardness descends, and chemical proofing is bad.On the other hand, when greater than 160mgKOH/g, during unreacted hydroxyl remained in and films, water tolerance, weathering resistance became bad.
In addition, in acrylic resin of the present invention, also can copolymerization N hydroxymethyl acrylamide and/or N-butoxymethyl acrylamide.The addition of these acid amides compositions is 2~10 weight % to the total monomer weight that forms acrylic resin, preferred 3~5 weight %.By with these acid amides composition copolymerization because crosslinking reaction takes place acrylic resin each other, so cross-linking density uprises, water tolerance and chemical proofing etc. improves.
As the acrylic component of acrylic resin of the present invention, can adopt following any: (methyl) methyl acrylate, (methyl) ethyl propenoate, (methyl) isopropyl acrylate, (methyl) isobutyl acrylate, (methyl) n-butyl acrylate, (methyl) cyclohexyl acrylate and (methyl) lauryl acrylate, (methyl) glycidyl acrylate.In addition, acrylic resin of the present invention, in the scope of not damaging electrophoretic paint characteristic of the present invention, also can with following monomer copolymerization: vinylbenzene, alpha-methyl styrene, vinyl acetate between to for plastic, vinyl propionate, vinylchlorid, vinylidene chloride, (methyl) vinyl cyanide, vinyl fluoride, vinylidene, 2-Ethylbenzyl (methyl) acrylate etc.The content of these monomer components is to be preferred below the 20 weight % in acrylic resin.
Acrylic resin can adopt known any methods such as solution polymerization, letex polymerization, suspension polymerization to make.Particularly, adopt the water-miscible solvent of pure series solvent, cellosolve series solvent, Trivalin SF series solvent, dimethyline series solvent and cellosolve acetate series solvent etc., the solution polymerization process that preferably adds various monomers and initiator carries out polymerization.
Used initiator when making acrylic resin, can adopt that to be suitable for common synthetic any, for example, can enumerate azo based compound, disulphide based compound, sulfide-based compound, sulfone based compound, diazonium based compound, nitroso compound, superoxide based compound.
In coating of the present invention, the carboxyl of acrylic resin neutralizes with following alkaline matter etc., for example uses ammonia; Aliphatics amines such as Trimethylamine 99, mono aminoethane, diethylamine, triethylamine, tripropyl amine, tri-isopropyl amine, dibutyl amine, dibutylamine, Tributylamine, hexahydroaniline, dicyclohexyl amine, diethyl cyclohexylamine, methoxyl group Isopropylamine, 2-amino-methyl propyl alcohol, 2-dimethylamino-2-methyl-1-propanol, morpholine, N-ethylmorpholine; Alcaminess such as thanomin, diethanolamine, trolamine, monomethyl-ethanolamine, dimethylethanolamine, dibutyl thanomin etc., and use also can as water soluble resin.
In the present invention,, in the solids component of all resins composition, cooperate 20~40 weight %, preferably cooperate 25~35 weight % as the wetting ability melamine resin of stiffening agent.When the amount of stiffening agent is lower than 20 weight %, can not cause sufficient curing reaction, on the other hand, when being higher than 40 weight %, filming becomes really up to the mark, and cementability and flexibility descend.
As the wetting ability melamine resin that stiffening agent uses, preferably adopt the melamine resin of common methyl/butyl mixed ether modified version.
At this moment, the ratio of methoxyl group/butoxy that also can adopt methyl/butyl mixed ether modification is more than 6: 4, and is preferred more than 7: 3, the modification melamine resin until 9: 1.When this ratio is lower than 6: 4, pitting there is detrimentally affect.
Above-mentioned melamine resin can be divided into high imido fundamental mode alkyl oxide melamine resin, methylol type alkyl etherification melamine resin, alkyl etherification melamine resin, mixed alkyl etherificate melamine resin etc., can use anyly, can suitably select according to sintering temperature, the physical properties of filming.Melamine resin with imino-and methylol, general water tolerance is low, considers that from the water tolerance of filming alkyl etherification melamine resin, mixed alkyl etherificate melamine resin are preferred.
As the abovementioned alkyl etherification melamine resin, can enumerate with normal-butyl, isobutyl-carry out the butylated melamine resins of etherificate, with methyl etherified methylated melamines resin and with the methyl/butyl complex etherified melamine resin of methyl, normal-butyl, isobutyl-etherificate.The commodity of selling on the market as above-mentioned methylated melamines resin, for example, can enumerate methoxyl group/isobutoxy mol ratio is that the mol ratio of 60/40 サ イ メ Le 238, methoxyl group/butoxy is that the mol ratio of 60/40 サ イ メ Le 235, methoxyl group/butoxy is that the mol ratio of 65/35 サ イ メ Le 231, methoxyl group/butoxy is that the mol ratio of 40/60 サ イ メ Le 236, methoxyl group/butoxy is 70/30 サ イ メ Le 266,277 (above any Mitsui サ イ テ Star Network society system that is); ス ミ マ-Le 50B (Sumitomo Chemical society system) etc.
As the commercial goods of above-mentioned butylated melamines, for example, can enumerate マ イ コ-ト 506 (Mitsui サ イ テ Star Network society system), ユ-バ Application 20SE, ユ-バ Application 20N-60 (chemical society system is pressed in Mitsui east) etc.
Commercially available prod as above-mentioned methylated melamines resin, for example, can enumerate サ イ メ Le 303 (Mitsui サ イ テ Star Network society system), ス ミ マ-Le M30W, M40S, M50W (being Sumitomo Chemical society system), メ ラ Application 622,623 (be Hitachi and change into industrial society system) etc.
In coating of the present invention, above-mentioned resin combination can be dispersed in the aqueous medium and use, and the solid component content in the coating is 5~20 weight %, preferred about 7~15 weight %.
Coating of the present invention is transparent electrodeposition coating composition.Here so-called transparent means the coating that does not contain body pigment and tinting pigment.
In electrophoretic paint of the present invention, as required, can also cooperate tinting material normally used additive in addition.
In addition, the invention provides and a kind of above-mentioned transparent electrodeposition coating composition is coated on electrophoresis coating process on the conductive substrate.In electrophoresis coating process of the present invention, be not particularly limited, but preferred 10~30 ℃ of electrophoresis chamber temperature, preferred 50~300 volts of impressed voltage, preferred 1~10 minute of coating time.
As the conductive substrate of applied material, can enumerate iron plate, steel plate, aluminium sheet and surface treated material thereof, or its goods, yet, be not particularly limited as long as there is electroconductibility to use.Aluminium is particularly preferred.
Embodiment (synthesizing of acrylic resin 1)
The reaction vessel of packing into as Virahol 32 weight parts of solvent and ethylene glycol butyl ether 33 weight parts, be heated to 90~100 ℃, when slowly refluxing with 3 hours inward drip styrene 10 weight parts, methyl methacrylate 27 weight parts, isobutyl acrylate 15 weight parts, ethyl propenoate 8 weight parts, hydroxy ethyl methacrylate 24 weight parts, methacrylic acid 13 weight parts and N-butoxymethyl acrylamide 4 weight parts monomer and as the mixture of Diisopropyl azodicarboxylate 2.0 weight parts of polymerization starter.After dripping termination, continue reaction 1 hour again, then,, reacted again 2 hours with Diisopropyl azodicarboxylate 0.5 weight part and Virahol 1.0 weight parts of dropping in 1.5 hours as initiator.The nonvolatile component of resulting acrylic paint is 60%, hydroxyl value 100mgKOH/g, acid number 80mgKOH/g, weight-average molecular weight 30000.(synthesizing of acrylic resin 2)
Virahol 32 weight parts and the ethylene glycol butyl ether 33 weight parts reaction vessel of packing into, be heated to 90~100 ℃, when slowly refluxing with 3 hours inward drip styrene 13 weight parts, methyl methacrylate 10 weight parts, isobutyl acrylate 22 weight parts, hydroxy ethyl methacrylate 33 weight parts, methacrylic acid 18 weight parts and N-butoxymethyl acrylamide 4 weight parts monomer and as the mixture of Diisopropyl azodicarboxylate 2.0 weight parts of polymerization starter.Continue reaction 1 hour again after dripping termination, then,, reacted again 2 hours with azo-bis-isobutyl cyanide 0.5 weight part and Virahol 1.0 weight parts of dropping in 1.5 hours as initiator.The nonvolatile component of resulting acrylic paint is 60%, hydroxyl value 150mgKOH/g, acid number 120mgKOH/g, weight-average molecular weight 35000.(synthesizing of acrylic resin 3)
Virahol 32 weight parts and the ethylene glycol butyl ether 33 weight parts reaction vessel of packing into, be heated to 90~100 ℃, when slowly refluxing with 3 hours inward drip styrene 6 weight parts, methyl methacrylate 50 weight parts, isobutyl acrylate 10 weight parts, hydroxy ethyl methacrylate 10 weight parts, ethyl propenoate 12 weight parts, methacrylic acid 8 weight parts and N-butoxymethyl acrylamide 4 weight parts monomer and as the mixture of Diisopropyl azodicarboxylate 2.0 weight parts of polymerization starter.Continue reaction 1 hour again after dripping termination, then,, reacted again 2 hours with azo-bis-isobutyl cyanide 0.5 weight part and Virahol 1.0 weight parts of dropping in 1.5 hours as initiator.The nonvolatile component of resulting acrylic paint is 60%, hydroxyl value 40mgKOH/g, acid number 50mgKOH/g, weight-average molecular weight 30000.(synthesizing of acrylic resin 4)
Virahol 32 weight parts and the ethylene glycol butyl ether 33 weight parts reaction vessel of packing into, be heated to 90~100 ℃, when slowly refluxing with 3 hours inward drip styrene 6 weight parts, methyl methacrylate 23 weight parts, isobutyl acrylate 28 weight parts, hydroxy ethyl methacrylate 33 weight parts, methacrylic acid 6 weight parts and N-butoxymethyl acrylamide 4 weight parts monomer and as the mixture of Diisopropyl azodicarboxylate 2.0 weight parts of polymerization starter.Continue reaction 1 hour again after dripping termination, then,, reacted again 2 hours with azo-bis-isobutyl cyanide 0.5 weight part and Virahol 1.0 weight parts of dropping in 1.5 hours as initiator.The nonvolatile component of resulting acrylic paint is 60%, hydroxyl value 150mgKOH/g, acid number 50mgKOH/g, weight-average molecular weight 35000.(synthesizing of acrylic resin 5)
Virahol 32 weight parts and the ethylene glycol butyl ether 33 weight parts reaction vessel of packing into, be heated to 90~100 ℃, when slowly refluxing with 3 hours inward drip styrene 12 weight parts, methyl methacrylate 26 weight parts, isobutyl acrylate 32 weight parts, hydroxy ethyl methacrylate 17 weight parts, methacrylic acid 9 weight parts and N-butoxymethyl acrylamide 4 weight parts monomer and as the mixture of Diisopropyl azodicarboxylate 2.0 weight parts of polymerization starter.Continue reaction 1 hour again after dripping termination, then,, reacted again 2 hours with azo-bis-isobutyl cyanide 0.5 weight part and Virahol 1.0 weight parts of dropping in 1.5 hours as initiator.The nonvolatile component of resulting acrylic paint is 60%, hydroxyl value 80mgKOH/g, acid number 80mgKOH/g, weight-average molecular weight 30000.
Embodiment 1
Add triethylamine in 81 weight parts of above-listed synthetic acrylic resin 1 lacquer and make neutralization ratio reach 35% (carboxyl is reached 0.35 equivalent), in addition uniform mixing.Toward wherein adding サ イ メ Le 285 (methoxyl group/butoxy is than=7/3 (weight ratios) for Mitsui サ イ テ Star Network society system, melamine resin) 19 weight parts earlier, stirred 10 minutes.Under agitation, make the aqueous dispersions that solids component is 50 weight %, as electrophoretic paint stoste toward wherein slowly adding deionized water.
In addition, add triethylamine, deionized water in this stoste, the solution of making neutralization ratio 70%, solids component 8 weight % is for electrophoresis.
This electrophoretic paint is adjusted to 20 ℃, on the 6063S aluminium alloy plate, carry out the anodised aluminium tunicle and handle (alumina coating thickness: 9 μ m), then, carry out sealing of hole and handle (dipping is 3 minutes in 80 ℃ of hot water), apply 100~200V volts DS, electrophoresis coating 3 minutes makes to reach dry film thickness 8~10 μ m.
After the electrophoresis coating, in being adjusted to 20 ℃ water-bath,, obtain hardened coating film after 3 minutes, carrying out drying in 30 minutes in 160 ℃ of sintering through the aluminium alloy plate dipping of coating.
Embodiment 2
Except that adopting acrylic resin 2 as the acrylic resin, make electrophoretic paint similarly to Example 1, carry out electrophoresis coating and washing, sintering.Comparative example 1
Except that adopting acrylic resin 3 as the acrylic resin, make electrophoretic paint similarly to Example 1, carry out electrophoresis coating and washing, sintering.Comparative example 2
Except that adopting acrylic resin 4 as the acrylic resin, make electrophoretic paint similarly to Example 1, carry out electrophoresis coating and washing, sintering.Comparative example 3
Except that adopting acrylic resin 5 as the acrylic resin, make electrophoretic paint similarly to Example 1, carry out electrophoresis coating and washing, sintering.Comparative example 4
Remove and adopt acrylic resin 4 as acrylic resin, employing サ イ メ Le 235 (Mitsui サ イ テ Star Network society systems, methoxyl group/butoxy is than=4/6 (weight ratio)) as beyond the melamine resin, make electrophoretic paint similarly to Example 1, carry out electrophoresis coating and washing, sintering.
Adopt the electrophoretic paint of making in embodiment 1 and 2, the comparative example 1~4, by the stability in the running of pump distributivity (Port Application プ シ エ ア) evaluation coating, in addition, to the performance of hardened coating film by pencil hardness and scuff resistance evaluation hardness, estimate hardening as salt tolerant acidity and strong basicity resisting, and, by melamine resin being dripped the Evaluation for Uniformity pitting of filming of filming when going up to unhardened.
The character of used various resins is shown in table 1 in embodiment and the comparative example.
Evaluation result with following evaluation method is shown in table 2.The evaluation method of hardened coating film [hardness]
According to JIS K5400, carry out the test of cut value with pencil, hardness is not represented by the highest pencil hardness of cut with filming.[hardening]
1. salt tolerant acidity:
According to JIS K8602, in 20 ℃ 5% aqueous hydrochloric acid, make contact after 192 hours, by the visual inspection film coated surface, with spot corrosion grade (JIS K8681 :) expression to the corroded area percentage of test face.
2. strong basicity resisting:
According to JIS K8602, in 20 ℃ 5% aqueous sodium hydroxide solution, make contact after 192 hours, by the visual inspection film coated surface, with spot corrosion grade (JIS K8681 :) expression to the corroded area percentage of test face.[scuff resistance]
Vibration shape product dyed thereby friction firmness trier (the smart mechanism of Dae Young Co., Ltd.'s science is done manufacturing) is learned in employing, behind round 200 times of the corrugated cardboard that applies the 800g loading, and visual valuation film coated surface state.
Zero: do not have and hinder or vestige.
△: 1~3 place left and right sides scar is arranged.
*: the remarkable scar in several places is arranged.
* *: has banded scar.[pitting (melamine resin intermiscibility)]
Aluminium test piece (the alumina coating item for disposal of JIS H4000:A6063S), after assigned voltage energising 2 minutes down, washing, placed 30 minutes in room temperature, make the film coated surface drying.Then, drip melamine resin (サ イ メ Le 285: Mitsui サ イ テ Star Network society system), carry out sintering in 160 ℃, be coated with membrane stage behind the visual valuation sintering toward film coated surface.
Zero: depression, impression etc. do not take place.
△: see few depression, impression.
*: produce depression, impression.The method for estimating stability of operating electrophoretic paint [pump distributivity]
Make coating 1L circulation after 1 hour with イ ワ キ マ グ ネ Star ト pump (MD-15-RN), carry out the electrophoresis coating by following order.
1. violent stirring coating before electrophoresis coating.
2. in the electrophoresis that holds above-mentioned electrophoretic paint is bathed, put into the aluminium test piece (the alumina coating item for disposal of JISH4000:A6063S) that is converted into the L font, stopped to stir 5 minutes.
3. under the voltage of regulation, switched on 2 minutes, carry out the electrophoresis coating, washing back sintering.
Such sintering, hardened filmed carry out visual observation, estimate depression, impression etc. whether occur unusually, as the yardstick of paint stability in service.
Judge 10 points of no problem, carry out 10 hierarchy level evaluations.
Table 1
| The official uses the characteristic of resin |
Embodiment | Comparative example |
????1 | ????2 | ????1 | ????2 | ????3 | ????4 |
Acrylic resin | Acid number | ????80 | ????120 | ????50 | ????50 | ????80 | ????50 |
Hydroxyl value | ????100 | ????150 | ????40 | ????150 | ????80 | ????150 |
Melamine resin | ???MeO/BuO | ????7/3 | ????7/3 | ????7/3 | ????7/3 | ????7/3 | ????4/6 |
Table 2
| Embodiment | Comparative example |
????1 | ????2 | ????1 | ????2 | ????3 | ????4 |
Hardness | 160 ℃ * 30 minutes | ????5H | ????5H | ????3H | ????4H | ????3H | ????4H |
180 ℃ * 30 minutes | ????6H | ????6H | ????4H | ????5H | ????4H | ????5H |
Salt tolerant acidity | 192 hours | ????10 | ????10 | ????8.0 | ????0.0 | ????7.0 | ????0.0 |
Strong basicity resisting | 192 hours | ????9.8 | ????9.8 | ????8.0 | ????6.0 | ????6.0 | ????5.0 |
Scuff resistance | ????○ | ????○ | ????×× | ????△ | ????× | ????△ |
The pump distributivity | ????10 | ????10 | ????1 | ????7 | ????5 | ????3 |
The melamine resin pitting | ????○ | ????○ | ????× | ????△ | ????△ | ????× |