JPS6212273B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing an electrodeposition coating composition. Specifically, a mixture consisting of a product of a preliminary reaction between 1,4-addition polybutadiene and an oil component (hereinafter referred to as oil addition reaction) and 1,2-addition polybutadiene is treated with α,β-ethylenically unsaturated The present invention relates to a method for producing an electrodeposition coating composition, which comprises reacting with a polybasic acid or its acid anhydride (hereinafter abbreviated as unsaturated polybasic acid) and then neutralizing it with a basic compound. More specifically, it has excellent corrosion resistance, throwing power, smoothness of the coating film, coverage of the edge of the object to be coated (edge coverage), overcoatability, and stability in the tank, and is odorless and has a wide electrodepositing work area. The present invention relates to a method for obtaining an electrodeposition coating composition. Conventionally, electrodeposition coating compositions using base-neutralized water-dilutable resins, which are reaction products of 1,4-addition polymers, such as 1,4-addition polybutadiene and unsaturated polybasic acids, have been prepared using 1,2-addition polymers. It was known that the corrosion resistance was better than that using type polybutadiene, but
There are various problems such as low hardness of the paint film, curing speed of the paint film surface is faster than internal curing, which causes wrinkles on the paint film surface, poor internal curing property of the paint film, and poor water resistance. It had some problems. Furthermore, the above-mentioned paints had an unsatisfactory finish when applied as a topcoat, and there were problems in particular with respect to topcoatability on sanded surfaces. Further, during baking drying, a bad odor is generated, which is thought to be due to thermal decomposition of the 1,4-addition polybutadiene or volatilization of a trace amount of low molecular weight polybutadiene polymer contained in the resin, which naturally limits its practical use. For the purpose of improving the internal hardening properties of the reaction product of the above-mentioned 1,4 addition type polybutadiene and unsaturated polybasic acid, an oil component is already added or 1,2
Electrodeposition coatings have been proposed whose main component is a product obtained by adding addition type polybutadiene and reacting simultaneously in a three-component system or a four-component system. However, the former method was not practical because the internal hardening property was not sufficiently improved and the corrosion resistance and chemical resistance were reduced.
In addition, the latter does not have sufficient corrosion resistance, chemical resistance, and throwing power, and after electrodeposition coating, water marks are easily visible on the coated surface when washed with water and baked and dried, and the coating film has craters, repellents, etc. It also had the disadvantage of being prone to defects. Furthermore, electrodeposition coating compositions in which the latter resin product is mixed with water-soluble or water-dispersible methylolated phenolic resins are also known (Japanese Patent Publication No. 51-24532).
The above-mentioned drawbacks have not been sufficiently improved, and the coating composition of the electrodeposition bath changes due to long-term electrodeposition coating, making bath management extremely difficult. On the other hand, it is also known that 1,2-addition polybutadiene, 1,4-addition polybutadiene, and an oil component are reacted with α,β-ethylenically unsaturated dicarboxylic acid and then mixed together. It has been found that the properties and smoothness of the coating film are further reduced. In any case, none of the known compositions could prevent the occurrence of bad odor due to the use of 1,4-addition polybutadiene. Furthermore, as polybutadiene, 1,2
Attempts have been made to use materials containing both addition type and 1,4 addition type, but these have been undesirable due to poor corrosion resistance and overcoatability. It is also possible to use 1,2-addition polybutadiene and react it with an unsaturated polybasic acid, but it tends to gel during the reaction, making it difficult to control the reaction to obtain a homogeneous product. Due to the poor impact resistance of the membrane, there was a natural limit to its use alone. In order to solve the above-mentioned problems, the present invention has completed the manufacturing method of the present invention as a result of intensive research. That is, the present invention improves or eliminates various drawbacks of the 1,4 addition type polybutadiene, such as internal hardening properties and odor during baking, and further improves corrosion resistance, throwing power, external finish of the coating film, and the finish of the end surface of the coated object. The object of the present invention is to provide a method for producing an electrodeposition coating composition that has even better coating properties (edge coverage), top coatability, stability of the electrodeposition bath, and coating workability. That is, the present invention provides (i) 1,2 vinyl 2
80-10% by weight of 1,4-addition polybutadiene with less than 50% of total double bonds and an oil component of 20-20% by weight
(ii) (a) carrying out an addition reaction with 90% by weight of the oil addition reaction product;
A step of reacting 94 to 70% by weight of a mixture consisting of 20 to 90% by weight of 1,2-addition polybutadiene with (b) 6 to 30% by weight of α,β-ethylenically unsaturated polybasic acid or its anhydride. , (iii) a step of further reacting water and at least one compound of alcohols as necessary to obtain a resin with an acid value of 40 to 200, and (v) a final neutralization step with a basic compound. The present invention relates to a method for producing a coating composition. The resin composition obtained by the above-mentioned known production method contains an oil component, a 1,4 addition type polymer, and a 1,4-addition polymer.
The addition rate of the unsaturated polybasic acid to the 2-addition type polybutadiene is different (in the above simultaneous reaction, the addition rate is the fastest for a compound having a conjugated double bond such as tung oil, followed by the 1,4-addition type polybutadiene, 1, The oil component and the polybutadiene are simply mixed or a system containing some reaction products is formed. (In the simultaneous reaction, the addition reaction between the unsaturated polybasic acid, oil, and polybutadiene proceeds predominately in the oil addition reaction between the oil component and polybutadiene). However, in the method of the present invention, the oil component is subjected to a graft reaction with the 1,4 addition type polybutadiene in advance, and therefore the chemical structure of the final water-dispersible resin is completely different from that of the conventional one. Although the present invention does not intend to be bound by theory, it is believed that improvements in the above-mentioned properties as an electrodeposition coating material are achieved due to this difference in resin structure. The 1,4 addition type polybutadiene used in the method of the present invention has an iodine value of 350 or more and has 1,2 vinyl double bonds accounting for 50% of the total double bonds.
Below, preferably 1,2 vinyl double bonds are 10%
A polybutadiene homopolymer with a number average molecular weight of 500 to 5000 consisting of the following, styrene, propene,
It is a copolymer with monomers such as butene-1. Particularly preferred is polybutadiene having an iodine value of 400 or more and having 60% or more of cis 1,4 double bonds and 5% or less of 1,2 vinyl double bonds. The above-mentioned 1,4 addition type polybutadiene having a carboxyl group or a hydroxyl group at the end of the molecular chain can also be used. When the iodine value is less than 350, the curability of the resulting coating film decreases. If the number of 1,2-vinyl double bonds exceeds 50%, it is not preferable because gelation tends to occur during the oil addition reaction with the oil component. If the number average molecular weight of the 1,4-addition polybutadiene is less than 500, the coating film will become brittle, and if it is greater than 5,000, there is a high risk of gelation during the oil addition reaction with the oil component, and the resulting coating film may become brittle. This is not practical because the smoothness of the film decreases. Oil components used in the method of the present invention include (1) For example, linseed oil, soybean oil, dehydrated castor oil,
Natural oils with an iodine value of 100 or more, such as tung oil, safflower oil, sardine oil, herring oil, saury oil, etc. (2) For example, linoleic acid, linoleic acid, oleic acid, α-eleostearic acid, etc. (3) Polyhydric alcohols having 2 to 6 hydroxyl groups in one molecule, such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, pentaerythritol, sorbitol, etc.; e.g. bisphenol Epoxy resins with a molecular weight of 200 to 2000 having one or more epoxy groups in one molecule, such as reaction products of polyhydric phenols and epichlorohydrin; such as styrene-allyl alcohol polymers, etc. 200~2000
and esterified products of polyol resins, etc., with the unsaturated fatty acids, and the esterified products are further combined with other acids such as saturated, unsaturated or aromatic acids such as butyric acid, stearic acid, phthalic acid, isophthalic acid, rosin acid, or benzoic acid. Modified with acids or acid anhydrides of the same group. (4) Boil oil and stand oil obtained by heating the natural oil described in (1) above, dimer of unsaturated fatty acids (dimer acid) described in (2) above, and copolymerization of the natural oil described in (1) above and styrene. styrenated oil, the cyclopentadiene adduct of natural oil (1) or the cyclopentadiene adduct of unsaturated fatty acid (2), and (5) the C ₅ to C ₉ fraction obtained by thermal decomposition of naphtha. Examples include unsaturated petroleum resins (iodine value 100 or more, molecular weight 200 to 5000) obtained by polymerizing olefins, rosin coumarone resins, and the like. These oil components can be used alone or in combination of two or more. In the method of the present invention, the oil addition reaction between the 1,4 addition type polybutadiene and the oil component is carried out as follows. That is, a mixture consisting of 1,4-addition polybutadiene and an oil component is heated to 180 to 320°C, preferably 220 to 280°C, in the presence of an inert gas such as nitrogen gas, and the iodine value reduction rate at the same temperature is determined. , 3% or more40
% or less, preferably 5% or more and 30% or less. If the iodine value reduction rate is less than 3%, the effects of the present invention will not appear. If the iodine value reduction rate exceeds 40%, it is not preferable because there is a high risk of gelation during the addition reaction with the unsaturated polybasic acid. The end point of the reaction can be determined visually when the reaction system, which is slightly cloudy at the beginning of the reaction, turns transparent. Incidentally, the iodine value reduction rate is expressed by the following formula. Iodine value reduction rate = [Iodine value of the resin composition before reaction] - [Iodine value of the resin composition after reaction] / [Iodine value of the resin composition before reaction] x 100 When halogen is applied to a sample with saturated bonds, the amount of halogen absorbed is converted into iodine, and is expressed as the number of grams of iodine consumed per 100 g of sample, indicating the degree of unsaturation of the sample. It is particularly preferable that the oil addition reaction is carried out under reduced pressure and low-boiling components are distilled off during the heating reaction. In the above oil addition reaction, the blending ratio of 1,4 addition type polybutadiene and oil component is 80 to 10/20 by weight.
~90. If the oil component is less than the above blending ratio, the dispersibility, internal hardening properties, etc. of the pigment will decrease. vice versa,
If the oil component exceeds the above blending ratio, the throwing power and corrosion resistance will decrease. In particular, it is preferable that the above blending weight ratio is 65-20/35-80. The above oil addition reaction may be carried out using a small amount of radical initiator (for example, benzoyl peroxide, methyl ethyl ketone peroxide, cyclohexanone peroxide, t-butyl hydroperoxide, p-menthane hydroperoxide, cumene hydroperoxide) in the amount of 0.01 to 2% by weight. oxide, di-t-butyl peroxide, dicumyl peroxide, etc., or an azo compound such as azobisisobutyronitrile) by heating to a temperature higher than the decomposition temperature of the radical initiator, It is also possible to carry out the reaction at a relatively low temperature of 60 to 150°C. Particularly in this reaction, it is preferable to dilute the resin with 50 to 400 parts by weight of an inert solvent such as xylene or toluene based on 100 parts by weight of the resin solid content to reduce the risk of gelation. After the reaction is complete,
These diluting solvents are removed by vacuum distillation or the like. Next, the product of the oil addition reaction (hereinafter referred to as oil addition product), 1,2 addition type polybutadiene and α,β ethylenically unsaturated polybasic acid or its anhydride (hereinafter referred to as unsaturated polybutadiene) (referred to as basic acid). The 1,2 addition type polybutadiene used in the method of the present invention has an iodine value of 400 or more, contains vinyl double bonds in 50% or more of the total double bonds, preferably 60% or more, and has a number average molecular weight of 500 to 5000. butadiene homopolymers and copolymers with vinyl monomers such as styrene. Moreover, those having a carboxyl group or a hydroxyl group at the end of the molecular chain can also be used. When the iodine value is less than 400, the curability of the resulting coating film decreases. In addition, when the vinyl double bond content is less than 50%, the resulting coating film becomes soft,
Moreover, it is not preferable because the gloss and image clarity of the top coating film are reduced. Furthermore, if the number average molecular weight is less than 500, the resulting coating film will become brittle, while if it is greater than 5000, there is a risk of gelation during the reaction with the unsaturated polybasic acid, and the resulting electrodeposition coating film will become brittle. The smoothness of the surface decreases. As mentioned above, the 1,2 addition type polybutadiene used in the method of the present invention is an essential component for improving the hardness, internal curability and overcoatability of the coating film. The α,β ethylenically unsaturated polybasic acid or its anhydride (unsaturated polybasic acid) used in the present invention is
Examples include maleic acid, fumaric acid, itaconic acid, maleic anhydride, and itaconic anhydride. Also, a mixture of two or more of these acids may be used. The reaction of the oil addition product with the 1,2 addition type polybutadiene and the unsaturated polybasic acid is carried out as follows. That is, a system consisting of a mixture of these is heated to 140 to 230°C, preferably 160 to 210°C, in the presence of an inert gas such as nitrogen gas, and at the same temperature, the unreacted unsaturated polybasic acid is reduced to 1% or less. , preferably 0.3% or less. The reaction time varies depending on the reaction temperature, but is generally 2 to 10 hours. If the reaction temperature of this system is lower than 140°C, the reactivity of the unsaturated polybasic acid will decrease, the reaction time will become longer, and it will be impractical from an economic point of view. On the other hand, if the temperature is higher than 230°C, there is a risk of gelation, and it is difficult to obtain a smooth coating film. Furthermore, if 1% or more of unreacted unsaturated polybasic acid is present, the corrosion resistance of the electrodeposited coating will deteriorate, which is undesirable. The composition of the mixed system consisting of the oil addition product, 1,2 addition type polybutadiene and unsaturated polybasic acid in the above reaction is 80 to 10/20 in weight ratio of oil addition product/1,2 addition type polybutadiene. The weight ratio of the mixture to the unsaturated polybasic acid is 94-70/6-30, preferably 90-80/10-20. In the above, if the oil addition product exceeds the above weight ratio, the internal curing properties and overcoating properties of the coating film will decrease, and conversely, if it decreases, the pigment dispersibility of the coating material and the flexibility of the coating film will decrease. Furthermore, since the amount of 1,2-addition polybutadiene is relatively increased, gelation tends to occur during the reaction of the mixed system, and the smoothness of the resulting coating film may deteriorate, making it impossible to conduct a homogeneous reaction. On the other hand, if the amount of unsaturated polybasic acid used exceeds the above range, there is a risk of increased viscosity or gelation, and it is also difficult to obtain a smooth electrodeposited coating, which is not preferable. On the other hand, if the amount is less than the above range, the water dispersibility or water solubility will decrease, making it impossible to form an electrodeposition coating composition. In addition, an inert solvent that does not participate in the reaction is used to prevent the reaction from becoming non-uniform due to an increase in viscosity during this reaction, and to wash off unsaturated polybasic acid that has adhered to the reaction vessel due to volatilization into the reaction system. (e.g. xylene, toluene, etc.) based on the total amount of the reaction system.
It can be added in an amount of 10% by weight or less. If the amount of the inert solvent used is more than 10% by weight, the stability of the electrodeposition bath will decrease if the inert solvent is not removed after the reaction, so an operation to remove the solvent will be required. This is not desirable because it complicates the process. In addition, as a gelling inhibitor for the reaction system mentioned above,
Hydroquinone, t-butyl-hydroxytoluene, t-amylhydroquinone, 2,6-di-t
-Butyl-4-methylphenol, 2,4-di-
At least one of methyl-6-t-butylphenol, diphenylamine, diphenylenediamine derivatives, iron naphthenate, steel naphthenate, and the like can also be used. The anti-gelling agent can be used in an amount of 0.01 to 2% by weight based on the resin component (solid content). In the present invention, as described above, by reacting 1,4-addition type polybutadiene and an oil component in advance, a resin product with a chemical structure different from conventional ones (hereinafter referred to as an unsaturated polybasic acid adduct) can be produced. ) is formed, which is thought to have improved the drawbacks of conventional electrodeposition paints. In the method of the present invention, if the skeleton of the unsaturated polybasic acid adduct obtained by the above reaction contains an acid anhydride group, it may be further hydrolyzed with water or partially hydrolyzed with alcohol. Can be esterified. By carrying out this ring-opening reaction, water dispersibility, coating workability, throwing power, and coating film performance are further improved. First, in order to open the ring using water, an acid anhydride group 1
Mix 0.8 to 4 moles of water per mole and heat to 50 to 160°C. At this time, tertiary amine (e.g. triethylamine, tributylamine, etc.) is used as a catalyst.
It is preferable to use Next, ring-opening of the acid anhydride group using an alcohol is accomplished by blending 0.8 to 2.0 mol of the alcohol to 1 mol of the acid anhydride group and heating the mixture to 50 to 160°C. At this time, if the heating temperature is lower than 50°C or higher than 160°C, the same drawbacks as in the case of ring opening using water will occur. Furthermore, if the amount of alcohol added is less than 0.8 mol, the amount of acid anhydride groups remaining will be large, resulting in poor stability of the aqueous dispersion.
In this case, if polyhydric alcohol is used, there is a risk that the viscosity will increase significantly and gelation will occur. On the other hand, if the amount of alcohol added exceeds 2.0 moles, the amount of unreacted alcohol will increase, which will affect the throwing power, surface smoothness, water resistance, and image clarity of the electrodeposition coating during electrodeposition coating. This is not preferable because it lowers the temperature. Alcohols that can be used in the ring-opening reaction include primary or secondary monohydric alcohols having 18 or fewer carbon atoms, such as methyl alcohol, ethyl alcohol, propyl alcohol, butyl alcohol, octyl alcohol,
These include aliphatic alcohols such as n-undecyl alcohol, n-dodecyl alcohol, cetyl alcohol, and stearyl alcohol, aromatic alcohols such as benzyl alcohol, cycloaliphatic alcohols such as cyclohexyl alcohol, and ethylene glycol monoalkyl ethers. Dihydric to tetrahydric alcohols such as ethylene glycol, propylene glycol, neopentyl glycol, glycerin, trimethylolpropane and trimethylolethane, pentaerythritol, etc. can be used. Furthermore, fatty acids having 18 carbon atoms or less and having an alcoholic hydroxyl group in the molecule, such as castor oil fatty acids, can also be used. Also, these alcohols may be used in combination.
Tertiary monohydric alcohols are not suitable for use because they have poor reactivity with acid anhydride groups. However, polyhydric alcohols having a valence of 5 or more tend to gel and are difficult to use alone, but can be used if mixed with a monohydric alcohol to reduce the average functionality to 4 or less. In addition, when using a monohydric alcohol having 5 or less carbon atoms among the above-mentioned alcohols, the amount is 2.0 per mole of acid anhydride group.
It is permissible to add more than mol. In addition, in this ring-opening reaction, it is also possible to open a part of the acid anhydride group with water and the rest with alcohol. The resin obtained by the ring-opening reaction has an acid value of 40 to 200, preferably 50 to 180. If the acid value is less than 40, the water dilutability is poor even though it has been neutralized with a basic compound, and if the acid value is more than 200, the coating efficiency (Coulombic efficiency), corrosion resistance, and water resistance decrease, making it impractical. Unsaturated polybasic acid adduct with ring-opened acid anhydride group obtained as described above In order to facilitate handling of this product, it does not inhibit water dispersibility per 100 parts by weight and has electrodeposition coating properties. Addition of solvents that do not have an adverse effect on the product, such as monohydric alcohols with 5 or less carbon atoms, ethylene glycol monoalkyl ethers, diacetone alcohol, diacetone alcohol methyl ether, ketones, esters, etc., in an amount of 50 parts by weight or less. can do. Next, an electrodeposition coating composition is obtained by neutralizing the unsaturated polybasic acid adduct with a basic compound such as ammonia, organic amines, or alkali metal hydroxide. Basic compounds as neutralizing agents that can be used for this neutralization include alkanolamines such as monoethanolamine, diethanolamine, and triethanolamine, triethylamine, diethylamine, monoethylamine, diisopropylamine,
Alkylamines with an alkyl group having 4 or less carbon atoms such as trimethylamine and diisobutylamine, alkyl alkanolamines such as dimethylaminoethanol, organic amines such as alicyclic amines such as cyclohexylamine, alkalis such as caustic soda and caustic potash. metal hydroxide,
Such as ammonia. These neutralizing agents can be used alone or in combination until the pH of the electrodeposition coating composition falls within the range of 6.0 to 9.6. In order to further improve the internal curability, corrosion resistance and chemical resistance of the electrodeposition coating composition obtained by the method of the present invention, a crosslinking agent such as a phenol resin and an amino resin may be used in combination. As the phenolic resin, oil-soluble phenolic resins, water-dispersible phenolic resins, and water-soluble phenolic resins can be used, but water-soluble methylolated phenolic resins and etherified phenolic resins are particularly preferred. As the oil-soluble phenolic resin, for example, a novolak type phenolic resin can be used. The water-dispersible or water-soluble methylolated phenolic resins include, for example, phenols such as phenol, p-cresol, p-tert-butylphenol, amylphenol, p-phenylphenol, bisphenol A, and formaldehyde. A resol type methylolated phenol resin having at least one methylol group and 1 to 3 phenol nuclei in one molecule, which is obtained by reaction in the presence of an alkali catalyst, can be used. Those having four or more phenol nuclei are undesirable because they reduce water dispersibility and water solubility. Furthermore, an etherified phenol resin in which the above-mentioned methylol group is partially or completely etherified with a low molecular weight alcohol can be suitably used. The above amino resins include melamine-formaldehyde, urea-formaldehyde, and melamine-formaldehyde.
A product obtained by partially or completely etherifying the methylol group of the urea-formaldehyde reaction product with a low molecular weight alcohol can be used. The alcohol used in the etherification is preferably one having 4 or less carbon atoms. The amount of the crosslinking agent used is preferably 1 to 10/99 to 90 in weight ratio to the unsaturated polybasic acid adduct (solid content). If the amount of the crosslinking agent is less than the above range, the effect of addition will not be recognized, and conversely, if it is more than the above range, the corrosion resistance of the coating film and the stability of the electrodeposition bath will decrease, which is not preferable. . In addition, the crosslinking agent and the unsaturated polybasic acid adduct before neutralization were heated at 80 to 150°C.
It is preferable to carry out dissolution or co-condensation while heating at room temperature, since the improvement effect is particularly remarkable and the stability of the electrodeposition bath is further improved. This method is particularly suitable for oil-soluble crosslinking agents. The co-condensate is used after being neutralized with a basic compound to be water-solubilized or water-dispersed as described above. The electrodeposition coating composition obtained by the method of the present invention is used after mixing and dispersing a pigment, if necessary. The electrodeposition coating composition thus obtained forms a homogeneous coating film when it is prepared in a bath and energized using the article to be coated as an anode. The electrodeposition coating composition obtained by the method of the present invention has good stability in the electrodeposition bath, and has excellent anticorrosion properties and good throwing power even when electrodeposited on any material such as untreated steel plate or chemically treated steel plate. It has excellent properties such as hardness, smoothness, and hardenability. Therefore, it is possible to apply a top coat directly to the electrodeposition coating without polishing or intermediate coating, and the gloss and sharpness of the resulting coating are extremely good, making it suitable for high-grade finishing coatings. Optimal. Further, by using the electrodeposition coating composition obtained by the method of the present invention, electrodeposition coating can be performed at a high breakdown voltage, and therefore, the applicable coating voltage can be applied over a wider range than before. As described above, the electrodeposition coating composition obtained by the method of the present invention also has a wide range of workability. As mentioned above, the electrodeposition coating composition obtained by the method of the present invention suffers from odor during baking and drying, poor internal curing properties, and water resistance, which were considered to be disadvantages of electrodeposition coatings made from 14-added polybutadiene. This problem was solved all at once, and the resulting coating film had particularly excellent smoothness, physical properties, corrosion resistance, edge coverage, and overcoatability. Furthermore, due to the unique resin structure resulting from the prior grafting reaction of the 1,4 addition type polybutadiene and the oil component, the electrodeposition coating composition had good uniformity and high pigment inclusion. The present invention will be explained below with reference to Examples. In the examples, "parts" and "%" represent "parts by weight" and "% by weight," respectively. Example 1 Iodine number 450, number average molecular weight 1600, double bond
127.5 parts of 1,4 addition type polybutadiene with 74% cis 1,4 type double bonds, 25% trans 1,4 type double bonds, and 1% 1,2 vinyl type double bonds, and a viscosity of 5000 cps (25 ℃), 127.5 parts of thermally polymerized linseed oil with an iodine value of 130 and an acid value of 11 were charged into a reaction vessel equipped with a stirrer, a thermometer, a nitrogen gas introduction pipe, a pressure reducing device communication pipe, and a reflux condenser. Replace the air with nitrogen gas, heat in a silicone oil bath while continuing to stir and introduce nitrogen gas, raise the temperature to 250 °C in 2 hours, reduce the pressure inside the container to about 100 mmHg, and keep at 25.0 °C for 4 hours to react. Well then. The obtained oil addition compound has a viscosity of 3500 cps (25.0°C), an iodine value of 272, and an acid value.
The iodine value reduction rate was 6.2% in a clear liquid with a rating of 5.3. This oil addition compound has 90 1,2 vinyl type double bonds with an iodine value of 420 and a number average molecular weight of 2000.
255 parts of 1,2 addition type polybutadiene containing %,
12 parts of xylene, 0.72 parts of copper naphthenate and 90 parts of maleic anhydride were heated to 190°C in a nitrogen stream for 2 hours.
The temperature was raised to 100%, and the reaction was continued for an additional 4 hours until the amount of unreacted maleic anhydride was reduced to 0.2% or less. The reaction product was allowed to cool, and when the temperature reached 130°C, 70 parts of n-amyl alcohol was added, and the ring was opened by an esterification reaction at 130°C for 2 hours. The product had an acid value (solid content) of 79, and was diluted with ethylene glycol monoethyl ether to prepare a varnish with a solid content of 75%. A mixture of 133 parts of this varnish, 20 parts of titanium oxide, 5 parts of lead silicate, 1 part of carbon black, and 0.5 parts of strontium chromate was kneaded in a ball mill until the degree of pigment dispersion (measured with a grind gauge) was 10.
A mill base of μ was obtained. Then, 0.7 equivalents of triethylamine was added to the acid number of the mill-base resin, diluted to 14% solids with deionized water, and 48%
The mixture was stirred for a period of time to obtain an electrodeposition coating composition. of this paint
The pH was 8.2. Examples 2 to 6 Electrodeposition coating compositions were produced in the same manner as in Example 1 under the conditions shown in Table 1. However, the partially butyl etherified melamine resin of Example 5 was mixed with a varnish, and the same amount of various pigments as in Example 1 were kneaded and dispersed with respect to 100 parts of the solid content of this mixed varnish. Comparative Examples 1 to 9 Electrodeposition paints were prepared in the same manner as in Example 1 under the conditions shown in Table 2. However, in Comparative Examples 1 to 8, all of the components () to () were simultaneously reacted at once, and in Comparative Example 9, the components () to () were reacted in advance, and then the resulting reaction product was The () components were reacted. still,
Comparative Example 6 gelled during the maleation reaction, and Comparative Examples 7 and 8 gelled during the oil addition reaction and could not be formed into a paint. The paints obtained in each of the above Examples and Comparative Examples were tested for electrodeposition coating properties, coating film properties, etc. The results are shown in Table 3.

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Claims (1)

[Scope of Claims] 1 (i) 1, with a number average molecular weight of 500 to 5000 and in which 1,2 vinyl double bonds account for 50% or less of all double bonds;
80-10% by weight of 4-addition polybutadiene and oil component
(ii) (a) carrying out an addition reaction with 20 to 90% by weight of the oil addition reaction product;
A step of reacting 94 to 70% by weight of a mixture consisting of 20 to 90% by weight of 1,2-addition polybutadiene with (b) 6 to 30% by weight of α,β-ethylenically unsaturated polybasic acid or its anhydride. , (iii) a step of further reacting with water and at least one compound of alcohols to obtain a resin with an acid value of 40 to 200, if necessary, and (iv) a final step of neutralization with a basic compound. Method for producing a coating composition. 2 The iodine value reduction rate of the oil addition reaction product is 3
40% of the electrocoating composition according to claim 1.