WO2008050797A1 - Cationic electrodeposition coating composition and application thereof - Google Patents

Abstract

The invention relates to a cationic electrodeposition coating composition which gives through electrodeposition an uncured coating exhibiting a storage modulus (G') of 80 to 500dyn/cm2 at 140°C and a loss elasticity (G”) of 10 to 150dyn/cm2 at 80°C; and a method of coating with the composition. The G' and G” values can be adjusted by adding crosslinked resin particles having a mean particle size of 1.0 to 3.0μm and/or an inorganic pigment to the coating composition. The invention can attain both excellent surface smoothness of cationic electrodeposition coating film and excellent covering ofedge faces.

Description

 Specification

 Cationic electrodeposition coating composition and its application

 Technical field

 TECHNICAL FIELD [0001] The present invention relates to a cationic electrodeposition coating composition excellent in smoothness and end face coverage and a method for achieving both smoothness and end face coverage of a cationic electrodeposition coating film using the same.

 [0002] The present invention also relates to a cationic electrodeposition coating composition excellent in smoothness and end face coverage, and in particular, a cationic electrodeposition coating composition excellent in smoothness and end face coverage blended with specific crosslinked resin particles, and The present invention relates to a method for achieving both smoothness and end face coverage of a cationic electrodeposition coating film using the same.

 Background art

 [0003] Electrodeposition coating is a coating method performed by immersing an object to be coated in an electrodeposition coating composition and applying a voltage. In this method, even an object having a complicated shape can be painted in detail, and can be painted automatically and continuously, so that large and complex shapes such as automobile bodies can be formed. It is widely used as an undercoating method for objects to be coated.

 [0004] Even electrodeposition coating is a coating coating on an article, so it is naturally desirable that the painted surface be smooth. In addition, the metal punched portion has an acute end surface, and the anticorrosion performance deteriorates unless the coating is sufficiently coated on the portion. Therefore, both surface smoothness and end face coverage are performances required for electrodeposition coatings. On the other hand, surface smoothness is fluidized and smoothed by reducing the viscosity of the uncured coating during bake-curing, but end face coverage is obtained by preventing the viscosity of the uncured coating from decreasing. Is. In other words, end face coverage is required to suppress the sagging of the coating film during curing of the coating film and to leave the coating film on an acute edge surface. That is, smoothness and end face coverage are contradictory performances.

[0005] As a technique for examining the coating film viscosity of the electrodeposition coating film, there is a publication of Japanese Patent Application Laid-Open No. 2002-285077 (Patent Document 1), and the minimum coating film viscosity during the coating film curing process is between 30 and 150 PaS. An electrodeposition coating composition for electric wires characterized by the above is described! /, (Claim 3). Patent Document 1 describes that by adjusting the minimum coating viscosity in the coating curing process, it is possible to improve the edge coverage, etc., which prevents sagging during melting.

[0006] In JP-A-6-65791 (Patent Document 2), an anti-curing primer is applied to a surface of an uncured coating formed by applying a cationic electrodeposition coating, and an intermediate coating or top coating is further applied. In the method of simultaneously curing the three layers, it is disclosed that the cationic electrodeposition paint has a minimum melt viscosity of 10 ⁴ to 10 ⁸ cps when the coating film is cured. It is disclosed that this coating film can shorten the coating process because three layers are baked at a time, is excellent in edge cover property, and the formed multilayer coating film is excellent in finishing strength and chipping resistance. Yes. In this publication, the finish and edge cover properties in a multilayer coating are disclosed.

V, Ru force The finish and edge cover properties of the electrodeposition coating itself have been investigated! On the other hand, in the general paint including the cationic electrodeposition paint of the present invention, the particles described later are used.

V, the control of the viscosity of the coating has been done conventionally!

 [0007] By the way, low ash differentiation has recently been promoted for electrodeposition paints. Low ash differentiation is to reduce the amount of solid components with high specific gravity, such as inorganic pigments, and to prevent precipitation in the solid content of the electrodeposition paint. The low ash differentiation reduces the energy and labor that has been used to stir the electrodeposition bath to prevent sedimentation. Therefore, if the content of the inorganic pigment that meets the above-mentioned requirements for low ash differentiation is decreased, the amount of resin in the paint will be relatively increased, and the viscosity of the uncured coating film obtained by electrodeposition coating will be increased. It cannot be increased appropriately, and as a result, the sagging control at the end face portion cannot be adjusted appropriately, and the end face coverage is reduced.

[0008] On the other hand, the current cationic electrodeposition paint uses a solid content concentration of around 20% by weight, so after electrodeposition coating, it is washed in several stages and is unnecessary for the object to be coated. After the electrodeposition paint attached to the surface, especially its solid content, is completely removed, the baking process is performed. For this reason, a large amount of washing water is used, and the water washing process becomes longer. Recently, it has been desired to reduce these washing water and shorten the washing process. As a means for shortening such a washing step, so-called low solid differentiation that further lowers the solid content concentration of 20% by weight in the paint is required. If this low solidification is performed simply, the solid content in the electrodeposition paint tends to settle due to a decrease in the viscosity of the paint. If the content of the material is reduced, the solid content is more likely to settle. Therefore, in order to prevent such sedimentation, the electrodeposition bath must be agitated, making it difficult to reduce the energy load. In other words, for the purpose of saving energy and shortening the process, it is possible to control the viscoelasticity so that the sedimentation of the paint can be prevented and the end face coverage can be easily performed even with low solidification, and the surface smoothness. An excellent cationic electrodeposition coating is desired!

[0009] In relation to the means for obtaining such paints, that is, paints with improved thixotropy, there are already several technical capabilities S in which crosslinked resin particles are blended in a cationic electrodeposition paint. Japanese Patent Laid-Open No. 2005-23232 (Patent Document 3) shows that fine resin particles with an internal bridge of particle size 0 · 01-0.2 111 are added to the cationic electrodeposition coating composition! / (Patent Document 3 Claim 6). Incorporating such small particle size resin particles into electrodeposition paints has long existed as an improvement in thixotropy.

[0010] JP 2002-212488 A (Patent Document 4) emulsifies an α, β ethylenically unsaturated monomer mixture using an acrylic resin having an ammonium group as an emulsifier for the purpose of improving the anti-mold property of the edge portion. A cationic electrodeposition coating composition containing a crosslinked resin particle obtained by polymerization is disclosed. The resin particles obtained here also have a small particle size of 0.05 to 0.3111. However, when cross-linked resin particles having a force average particle size of 1.0 m or less are blended in the electrodeposition paint, the smoothness of the resulting coating film is lowered.

 Patent Document 1: Japanese Patent Laid-Open No. 2002-285077

 Patent Document 2: JP-A-6-65791

 Patent Document 3: JP 2005-23232 Koyuki

 Patent Document 4: Japanese Patent Laid-Open No. 2002-212488

 Disclosure of the invention

 Problems to be solved by the invention

[0011] As described above, an object of the present invention is to provide a method for achieving both surface smoothness, end face coverage, and contradictory performance in a cationic electrodeposition coating.

[0012] Further, in the present invention, as described above, for the purpose of reducing the solid content concentration of the coating material and for the purpose of low ash differentiation, the coating material is prevented from settling, and the strength and surface smoothness of the cationic electrodeposition coating material are also reduced. The object is to provide a method that achieves compatibility, end face coverage, and conflicting performance. Yes

 Means for solving the problem

[0013] That is, the present invention is a cationic electrodeposition coating composition, and a storage elastic modulus (G) of an uncured deposited coating obtained by electrodeposition coating of the cationic electrodeposition coating composition (G ') is a 80~500dyn / cm ^2, 80. Provided is a cationic electrodeposition coating composition excellent in smoothness and end face coverage, in which a loss bow (G ,,) force in C is 0 to 150 dyn / cm ² .

 [0014] The cationic electrodeposition coating composition comprises a cationic epoxy resin, a block isocyanate curing agent, and, if necessary, resin particles (preferably crosslinked resin particles) and / or a pigment (preferably inorganic pigment). The one containing is preferred!

[0015] Further, the present invention provides an uncured deposition of a cationic electrodeposition coating material in a method for forming a cationic electrodeposition coating film by immersing an object to be coated in a cationic electrodeposition coating composition and applying a voltage. By adjusting the storage elastic modulus (G ′) at 140 ° C. to 80 to 500 dyn / cm ² and the loss elastic modulus (G ″) at 80 ° C. to 10 to 150 dyn / cm ² Provided is a method for achieving both smoothness and end face coverage of a cathodic electrodeposition coating film.

 [0016] The storage elastic modulus and the loss elastic modulus are preferably adjusted by adding cross-linked resin particles or blending an inorganic pigment. In the case of cross-linked resin particles, the average particle diameter is preferably 1.0 to 3.0 111. The addition amount is preferably 3 to 15% by weight in the resin solid content of the cationic electrodeposition coating composition.

 [0017] The adjustment of the storage elastic modulus and the loss elastic modulus with the inorganic pigment is preferably performed by blending the inorganic pigment in an amount of 10 to 20% by weight in the solid content of the cationic electrodeposition coating composition.

 [0018] The storage elastic modulus and loss elastic modulus of both the inorganic pigment and the crosslinked resin particles can be adjusted. The crosslinked resin particles have an average particle diameter of 1.0 to 3. Om, and the inorganic pigment is It is preferable to use it in an amount of 0.5 to 10% by weight in the solid content of the cathodic electrodeposition coating composition!

 [0019] When the storage elastic modulus and loss elastic modulus are adjusted by both the inorganic pigment and the crosslinked resin particles, the crosslinked resin particles are contained in an amount of 3 to 15% by weight in the resin solid content of the cationic electrodeposition coating composition. It is preferable to be blended with.

[0020] In addition, as a result of studying a method for achieving both surface smoothness and end face coverage of a cationic electrodeposition coating material aiming at low solid differentiation and low ash differentiation, the present inventors have determined that specific crosslinked resin particles have It has been found that the object can be achieved easily and easily by blending it into the electrodeposition paint, and the present invention has been achieved.

[0021] Accordingly, the present invention has an average particle size of 1.0 to 3. O ^ m and a thermal softening temperature of 120 to 18;

Provided is a cationic electrodeposition coating composition containing cross-linked resin particles at 0 ° C. and having excellent smoothness and end face coverage.

[0022] The crosslinked resin particles are preferably 3 to 3% of the resin solid content of the cationic electrodeposition coating composition.

It is contained in an amount of 15% by weight.

[0023] The cationic electrodeposition coating composition of the present invention has a low solid content that contains no inorganic pigment in the composition or contains an inorganic pigment at 7% by weight or less in the solid content of the cationic electrodeposition coating composition. The type and low ash type are preferred!

[0024] The cationic electrodeposition coating composition of the present invention preferably has a solid content concentration of 0.5 to 9% by weight.

 [0025] In the present invention, the crosslinked resin particles preferably include suspension polymerization, emulsion polymerization, etc., of the compound (a) having two or more unsaturated double bonds in the molecule and (meth) acrylate (b). Can be obtained using known methods.

In the present invention, the storage elastic modulus (G ′) at 140 ° C. of an uncured deposited coating film obtained by electrodeposition coating with a cationic electrodeposition coating composition is 80 to 500 dyn / cm ² . The loss elastic modulus (G ") at 80 ° C is from 10 to 150 dyn / cm ² .

 [0027] The present invention further provides a cationic electrodeposition-cured coating film having an Ra value of 0.25, im or less indicating the smoothness of the coating film obtained by curing the cationic electrodeposition coating composition.

 [0028] The present invention also relates to a method for forming a cationic electrodeposition coating film by immersing an object to be coated in a cationic electrodeposition coating material and applying a voltage, with an average particle size of 1.0 to 3.O. A method for achieving both the smoothness and the end face coverage of a cationic electrodeposition coating film, which comprises blending crosslinked resin particles having a thermal maturation temperature of 120 to 180 ° C. with a cationic electrodeposition coating composition. provide.

[0029] Further, the present invention relates to a method for forming an electrodeposition coating film using a low ash type and low solid content type cationic electrodeposition coating composition, wherein the average particle size is 1.0 to 3. O ^ m. And crosslinked resin particles having a thermal softening temperature of 120 to 180 ° C. in the resin solid content of the cationic electrodeposition coating composition 3 ~; By adding it in an amount of 15% by weight, the storage modulus (G ') of the uncured deposited coating film at 140 ° C is 80-500 dyn / cm ² , and the loss modulus at 80 ° C (G ")" Is adjusted to 10 to 150 dy n / cm ² to provide a method for forming a cationic electrodeposition coating film with improved smoothness and end face coverage.

 The invention's effect

 [0030] According to the present invention, among the dynamic viscoelasticity of the uncured coating film deposited in electrodeposition coating, smoothness and end face coating can be achieved by simultaneously adjusting the loss elastic modulus G "and the storage elastic modulus G '. In the conventional technology, smoothness has been ensured only by controlling the minimum melt viscosity by controlling the complex viscosity * in dynamic viscoelasticity measurement. However, it was found that the above-mentioned smoothness and end face coverage cannot be achieved with only a simple viscosity S. In the present invention, in the dynamic viscoelasticity of the uncured coating film of the cationic electrodeposition paint, When controlling the smoothness, it was found that the loss elastic modulus: G "(viscosity term) was controlled to a specific range. We also found that it is important to control the storage modulus G '(elasticity term) within a specific range when controlling the end face coverage. Furthermore, in the present invention, the loss elastic modulus G "is controlled within a specific range and the storage elastic modulus is simultaneously controlled in order to ensure both smoothness and end face coverage of the electrodeposition coating film, which has been regarded as a reciprocal event. We found that it is important to control G 'to a specific range, and assuming that G "and G' are independent parameters, the electrodeposition obtained by controlling these parameters to a specific range respectively. This achieves both smoothness of the coating film and end face coverage.

 [0031] According to the present invention, both surface smoothness and end face coverage can be achieved by controlling only the loss elastic modulus and storage elastic modulus of the uncured coating film deposited during electrodeposition! It is possible to provide a useful performance inspection or performance management method for cationic electrodeposition paints.

[0032] Further, according to the present invention, crosslinked resin particles having an average particle size of 1.0 to 3. O ^ m and a thermal softening temperature of 120 to 180 ° C are blended in the cationic electrodeposition paint. This makes it possible to achieve both surface smoothness and end face coverage. In the case of a low ash type cationic electrodeposition coating composition, since it is not possible to obtain an increase in the viscosity of the coating film due to the inorganic pigment, it is expected that the end face coverage will be deteriorated. By incorporating it into the electrodeposition paint, the end face coverage is also improved, and the coating performance of the low ash type cationic electrodeposition paint composition is improved. It is effective as a means of maintaining or improving. Here, the low ash type cationic electrodeposition coating composition means that the solid content of the cationic electrodeposition coating composition does not contain any inorganic pigment, or even if it is included, the maximum is 7% by weight in the coating solid content. It means that. Furthermore, the present invention provides a low solid content type cationic electrodeposition coating composition that is more excellent in anti-settling ability than conventional ones and that can achieve both surface smoothness and end face coverage as described above. To do. Here, the low solid content type cationic electrodeposition coating composition means that the solid content concentration of the cationic electrodeposition coating composition is lower than the conventional 20 wt%, specifically 0.5 to 9 wt%. means.

[0033] In the study by the present inventors, the compatibility between surface smoothness and end face coverage can be correlated with the measurement of dynamic viscoelasticity of a deposited electrodeposition coating film obtained by electrodeposition coating. In particular, the loss elastic modulus G "at 80 ° C and the storage elastic modulus G 'at 140 ° C are within the specified range, that is, the loss elastic modulus at 80 ° C is 10 ~; 150 dyn / cm ² , 140 ° In the case of the storage elastic modulus G ′ in C, when the surface elasticity is 80 to 500 dyn / cm ² , both surface smoothness and cross-sectional coverage can be achieved. In the present invention, the average particle diameter is 1.0 to 3. It was found that crosslinked resin particles having an O ^ m and a thermal softening temperature of 120 ° C or higher were blended in the cationic electrodeposition paint.

 Brief Description of Drawings

 [0034] FIG. 1 is a graph showing the behavior of loss modulus (G ") value in dynamic viscoelasticity of five types of paints.

 FIG. 2 is a graph showing the behavior of storage elastic modulus (G ′) values in the dynamic viscoelasticity of five types of paints.

 [Fig. 3] A graph showing the behavior of the complex viscosity (7) * value in the dynamic viscoelasticity of five types of paint.

 FIG. 4A is a graph showing the relationship between the storage elastic modulus (G ′) of some paints at 80 ° C. and the electrodeposited skin.

 [Fig. 4B] A graph showing the relationship between the complex viscosity of some paints at 80 ° C (7) * and the electrodeposition skin.

[Fig. 4C] A graph showing the relationship between the loss elastic modulus (G ") of some paints at 80 ° C and the electrodeposited skin. [Fig. 5A] Draft showing the relationship between storage elastic modulus (G ') at 140 ° C and electrodeposition skin of some paints.

 [Fig. 5B] Draft showing the relationship between the complex viscosity of some paints at 140 ° C (7) *) and the electrodeposition skin.

 [Fig. 5C] Draft showing the relationship between the loss modulus (G ") of some paints at 140 ° C and the electrodeposited skin.

 [Fig. 6A] A graph showing the relationship between the storage elastic modulus (G ') of some paints at 80 ° C and the end face coverage.

 [Fig. 6B] This is a graph showing the relationship between the complex viscosity at 80 ° C (7) * and the end face coverage of several paints.

 [Fig. 6C] This graph shows the relationship between the loss modulus (G ") of some paints at 80 ° C and the end face coverage.

 FIG. 7A is a graph showing the relationship between storage elastic modulus (G ′) at 140 ° C. and end face coverage of several paints.

 [Fig. 7B] This is a graph showing the relationship between the complex viscosity (140) at 140 ° C and end face coverage of several paints.

 FIG. 7C is a graph showing the relationship between the loss elastic modulus (G ") and end face coverage of some paints at 140 ° C.

 FIG. 8 is a graph showing the relationship between the temperature and the storage elastic modulus G ′ for explaining the thermal softening temperature.

FIG. 9 is a diagram schematically showing a 30 micron site from the tip of the cutter knife.

BEST MODE FOR CARRYING OUT THE INVENTION

Dynamic viscoelasticity is an elastic modulus observed when a vibration (periodic) strain or force is applied to a linear viscoelastic body, and is related to frequency and temperature. The following descriptions on dynamic viscoelasticity include: lecture rheology (edited by the Japan Society of Rheology), Chapter 2 Rheology of Polymer Liquids, p31-39 and Introduction to Polymer Chemistry (Seizo Okamura, Akio Nakajima, Shigeharu Onoki, This is based on the contents described in pp. 49-155, Chapter 4 Properties of Polymers, Viscoelasticity, by Nishijima Ankai IJ, Toshinobu Higashimura, and Norio Ise). [0036] Stress and strain at the angular velocity ω (2 π X frequency f) are given by the following equations.

Strain 7 (t) = 7 e (dyn / cm ² )

 o

J heart force σ U) ⁼ σ e dvn / cm

 o

 (Where γ (t) is the strain at time t, σ (t) is the stress at time t, and γ is t = 0

 The strain at 0, σ is the stress at t = 0, and δ is the phase difference. )

 0

 The complex elastic modulus G * at this time is

 G = (σ / γ) β = σ / y) cos ό i sin δ)

 0 0 0 0

 It is represented by Complex viscosity commonly used as a viscosity control factor for paints 7] * =

0 * / ω (Boise) is a quantification of viscoelasticity that has both properties of paint viscosity and elasticity.

 [0037] That is, in the present invention, both smoothness and end face coverage can be achieved by separately treating the viscosity and elasticity and controlling them. To ensure smoothness, it is necessary to control the flow of paint during the baking process. This flow is associated with a viscous property, which is expressed by the following equation based on the relationship between stress and strain.

Loss modulus (viscosity) G "= G * sin S (dyn / cm ² )

 [0038] On the other hand, in order to ensure end face coverage, it is necessary to control the force to stay in place during the baking process, and this force is associated with the inertial properties, which are stress and strain. From the relationship, it is expressed by the following formula.

Storage elastic modulus (elasticity) G '= G * cos 6 (dyn / cm ² )

 [0039] In the case of general paints including cationic electrodeposition paints, the uncured coating film is dominated by the viscosity term in the initial stage of baking and is greatly affected by the loss modulus G ". In the later stage, the uncured coating film melts. After reaching the gel point (apparently connected from end to end) due to pseudo-crosslinking, the elastic term dominates thereafter and is greatly influenced by the storage elastic modulus G '. The relationship between the loss modulus G "(viscosity term) and the storage modulus G '(elastic term) of the viscoelastic behavior in is the temperature at which the loss modulus G" <storage modulus G'. It means a point that changes from dominance to elasticity term dominance.

[0040] In the present invention, the loss elastic modulus G "at a temperature below the gel point (80 ° C) is controlled, and the storage elastic modulus at a temperature above the gel point (140 ° C). Smoothness and end face coating by controlling G ' The present inventors have found that the compatibility of the properties can be achieved and have completed the present invention.

[0041] Here, the present invention will be described by describing the process leading to the completion of the invention. First

As a preliminary experiment, the following was performed.

[0042] V, the viscoelastic behavior was measured with several paints, specifically, conventional paint systems containing pigments, those without them, and those with various crosslinked resin particles. As the temperature rises, the viscosity starts to decrease from 40 to 80 ° C, and the viscosity increases slightly between 80 and 100 ° C, and greatly decreases when the temperature exceeds 100 ° C. Flow. After this flow, the curing reaction starts and the viscosity starts to increase again and gradually increases to around 150 ° C, and then the viscosity rapidly increases and the curing is completed. In order to check the dynamic viscoelasticity of the coating while confirming this, we measured five types of paint! /, Measured using Rheosol-G3000 from UBM Co., Ltd. The strain value γ (t) and the stress-strain phase difference δ with respect to the applied stress value σ (t) were measured at a frequency of 0.02 Hz and a temperature increase rate of 2 ° C / min. From the relationship between the obtained stress value σ (t), strain value γ (t) and phase difference δ, the storage elastic modulus (G '), loss elastic modulus (G ") and complex viscosity (] *) Figures 1 to 3 show the paints used in the following examples: STD is 310-310 (Nippon Paint Co., Ltd .: Cationic electrodeposition paint) ), “Frease f ree” is obtained by removing the pigment component from PN-310! /, (PWC = 0%), and “Resin particles 1” with “Pigment free” and crosslinked resin particles (average particle size; ! ~ 3 μm), 15% by weight of “Resin Particle 2”, “Pigment fr _ee ”, 5% by weight of cross-linked resin particles (average particle diameter lOOnm), “Resin Particle 3” Is a blend of 10% by weight of “pigment free” crosslinked resin particles (average particle diameter lOOnm) different from the crosslinked resin particles used in “resin particle 2”.

[0043] As can be seen from FIGS. 1 to 3, it can be seen that the behavior of each paint varies considerably. Roughly divided into three modes (40 to 80 ° C, 80 to; 100 ° C and 100 ° C or more), the dynamic viscoelasticity is greatly affected by the formulation of the paint, especially the presence of particles, etc. It can be seen that the graph changes with the five types of paint. Therefore, it can be seen that the viscoelastic behavior can be optimally controlled by changing the composition. [0044] In particular, it can be understood that the viscoelastic behavior near 80 ° C and the viscoelastic behavior near 140 ° C are the standards that greatly differ between the respective paints with reference to Figs.

 [0045] Based on this criterion, the following experiment was further performed. PN-310 (Cation Electrodeposition Paint made by Nippon Paint Co., Ltd.) and PN-310 paint with a changed amount of inorganic pigment component, inorganic pigment component is removed from PN-310! Several types of resin particles with different types and blending amounts were prepared and their viscous behavior was measured. From the results of viscoelasticity, Fig. 4 shows three viscoelastic behaviors at 80 ° C, namely G 'value and electrodeposited skin (Fig. 4A), 7] * value, so that changes at each temperature can be easily understood. The electrodeposited skin (Fig. 4B) and G "value and the electrodeposited skin (Fig. 4C) are all displayed, and Fig. 5 also shows three viscoelastic behaviors of 140 ° C, namely the G 'value and the electrodeposited skin ( Fig. 5A), n * value and electrodeposition skin (Fig. 5B) and G "value and electrodeposition skin (Fig. 5C) are all displayed. Electrodeposited skin was represented by surface roughness (Ra). The electrodeposited skin evaluated here means the appearance of the electrodeposited coating film, which will be described later, that is, smoothness, and is indicated by the measured value of the arithmetic average roughness (Ra) of the roughness curve. That is, by looking at the above-mentioned smoothness on the electrodeposited skin, the relationship between the electrodeposited skin and the viscous behavior was observed.

 [0046] As is apparent from the behaviors of Fig. 4 and Fig. 5, it is recognized that there is a certain relationship in the relationship between the viscoelasticity of each measurement point and measurement paint and the electrodeposited skin. (See Fig. 4C). Similarly, the results of measuring the three behaviors of end face coverage and viscoelastic behavior are also shown in FIGS. 6A to C and FIGS. 7A to C. As is clear from FIGS. 6 and 7, it can be seen that the relationship between the storage elastic modulus (G ′) at 140 ° C. and the end face coverage shows a correlation (see FIG. 7A). That is, there is a correlation between changes in the viscosity value and electrodeposition skin (smoothness) or end face coverage. Here, the above-described end face coverage is obtained by an evaluation method described later. The “coverability” shown in FIG. 6 and FIG. 7 is equivalent to “end face coverage” here!

[0047] From this measurement result, the present invention uses a loss elastic modulus (G ") of 80 ° C for electrodeposited skin (smoothness) and a storage elastic modulus (G of 140 ° C for end face coverage). ') Was used as a standard, and this led to the completion of the present invention, and referring to Fig. 4 and Fig. 7 above, the storage elastic modulus (G') and the loss elastic modulus (G " ) Can be selected. That is, G 'at 140 ° C is 80 ~ 500dyn with reference to Fig.7A / cm ² is preferable, and G ″ at 80 ° C. can be selected from 10 to 150 dyn / cm ² (the smaller the electrodeposition skin Ra, the better the smoothness) with reference to FIG. 4C. The storage elastic modulus (G,) is 90 to 500 dyn / cm ² , more preferably 100 to 500 dyn / cm ² , and the loss elastic modulus (G ″) at 80 ° C. is preferably 10 to; 120 dyn / cm ² , more preferably 10 to 100 dyn / cm ² .

 [0048] When the storage elastic modulus G 'is less than the desirable lower limit, the end face coverage of the obtained electrodeposition coating film may be deteriorated, and when the desirable upper limit is exceeded, smoothness may be decreased. If the loss elastic modulus G "is below the desirable lower limit, the smoothness is improved, but the end face coverage of the resulting electrodeposition coating film may be deteriorated, and if it exceeds the desirable upper limit, the smoothness may be decreased.

 [0049] Here, the storage elastic modulus G 'and the loss elastic modulus G "described above are the elastic moduli of the uncured deposited coating, and the uncured is an electrodeposition coating of a cationic electrodeposition paint. Precipitation coating film obtained in this way It is still baked and cured.

 [0050] As described above, the composition for cationic electrodeposition coating is added or blended with crosslinked resin particles and / or inorganic pigment. In addition to these, an aqueous medium, a cation that is dispersed or dissolved in the aqueous medium. Binder resin containing a functional epoxy resin and a block isocyanate curing agent, a neutralizing acid, and an organic solvent.

 [0051] In order to adjust the viscoelastic behavior, there is a method of adding crosslinked resin particles as a first method. The average particle diameter of the crosslinked resin particles is preferably 1.0 to 3. Om. When this particle size is smaller than 1.O ^ m, the ratio of the surface area increases, and the interaction with the cationic epoxy resin, which is a binder resin component contained in the cationic electrodeposition coating composition, increases, resulting in precipitation. Since the viscosity of the coating film rises rapidly, it becomes difficult to adjust the viscoelastic behavior as described above. On the other hand, when the particle diameter is larger than 3. Οπι, the smoothness decreases due to sedimentation without stirring of the electrodeposition paint and accumulation of particles on the horizontal surface during electrodeposition coating.

[0052] Further, the crosslinked resin particles used in the present invention have a low ash and low solid content cationic electrodeposition coating composition! Is 1.0 to 3. O ^ m, and the thermal softening temperature is 120 ° C or higher, preferably 120 to 180 ° C. Even in the prior art, proposals have been made for blending crosslinked resin particles into a cationic electrodeposition coating composition, but such resin particles have an average particle diameter of less than 1.O ^ m. Most of them. In the prior art, resin particles are simply blended to control the viscosity, so resin particles having an average particle size of less than 1.O ^ m are required. In order to achieve both surface smoothness and end face coverage from the viewpoints of loss elasticity G "at 80 ° C and storage modulus G 'at 140 ° C, in particular, the average particle size is larger than that of the prior art. It is preferable to mix the cross-linked resin particles having a squeezing force and a heat softening temperature of 120 ° C or higher, preferably from 120 to 1800 ° C! /.

 [0053] The average particle size of the crosslinked resin particles used in the present invention is, as described above, a force of 1.0 to 3.O ^ m. The lower limit is preferably 1 · 2111, more preferably 1 · 5 m. On the other hand, the upper limit i is preferably 2.δμΐ ^, more preferably 2 · 2 m. As described above, when it is smaller than 1.ΟΟη, it is not preferable because it falls within the range of the average particle diameter of the resin particles of the prior art and the surface smoothness deteriorates. Cross-linked resin particles having an average particle size greater than 3.0 0 111 suffer from a decrease in smoothness due to sedimentation when the electrodeposition coating is not stirred, or when the particles deposit on the horizontal surface during electrodeposition coating. The average particle size here is measured by the following method.

 [0054] The average particle diameter of the resin particles was measured by a granular particle permeation measurement method using MICROTRAC9340UPA manufactured by Nikkiso Co., Ltd. Further, with this measuring instrument, the particle size distribution of the resin particles was measured, and the average particle diameter at the cumulative relative frequency F (x) = 0.5 was calculated from the measured value. In these measurements and calculations, a solvent (water) refractive index of 1.33 and a resin component refractive index of 1.59 were used.

 [0055] The cross-linked resin particles used in the present invention have a heat softening temperature of 120 to 120 as described above in order to achieve both surface smoothness and end face coverage in a low ash and low solid content cationic electrodeposition coating composition. 180 ° C, but the upper limit is preferably 140 ° C, more preferably 160 ° C. When the heat softening temperature is lower than 120 ° C, the storage elastic modulus G ′ does not reach a predetermined value when an uncured electrodeposition coating film is baked, and the end face coverage cannot be secured. On the other hand, it is practically impossible to synthesize a material in which the thermal softening temperature of the crosslinked resin particles exceeds 180 ° C.

[0056] The thermal softening temperature is a temperature at which the crosslinked resin particles start to soften. That is, G ′ at each temperature of the target bridge resin particle is obtained, and the temperature at the point where the change of G ′ rapidly changes with respect to the temperature change can be obtained in the following manner. Crosslinking resin particle solid A sample obtained by adjusting the concentration of the part to 30% by weight was measured by measuring the temperature dependence using a rotary dynamic viscoelasticity measuring device Rhesol-G3000 (manufactured by UBM). Measure storage elastic modulus G 'from 90 ° C at 5 ° C, frequency 0.02Hz, temperature rise rate 4. Under the conditions of 0 ° C / min. The measurement results are as shown in the graph of Fig. 8. As is clear from FIG. 8, the storage modulus G ′ of the crosslinked resin particles maintains a constant viscosity in the initial temperature range (around 90 to 140 ° C. in FIG. 8), but at a certain temperature (140 ° C. in FIG. 8). The storage elastic modulus G 'begins to decrease at a temperature exceeding C). The temperature at the intersection is defined as the thermal softening temperature by drawing the tangent of the region where the viscosity is constant and the tangent of the region where the viscosity is decreasing.

 [0057] In order to increase the thermal softening temperature of the resin particles, it is necessary to increase the degree of crosslinking of the resin particles. In order to secure the thermal softening temperature region in the present invention, the resin particles need to be crosslinked resin particles. The glass transition temperature is also an index indicating the softening of the resin. However, when the glass transition temperature (Tg) is measured on the cross-linked resin particles, it reaches a level of several hundred degrees (° C). The thermal softening temperature is used in the present invention because the thermal decomposition increases and the softening characteristics of the particles themselves cannot be measured.

[0058] It is essential that the crosslinked resin particles have a crosslinked structure. When there is no cross-linked structure, the value of the storage elastic modulus G ′ at 140 ° C. is less than 80 dyn / cm ² , which is not preferable because end face coverage cannot be ensured. The crosslinked resin particles are preferably used in an amount of 3 to 15% by weight in the resin solid content of the cationic electrodeposition coating composition. If the content of the crosslinked resin particles is less than ¾% by weight, it becomes difficult to achieve both surface smoothness and end face coverage, and if it exceeds 15% by weight, the coating performance such as corrosion resistance may be deteriorated. Here, the above-mentioned “resin solid content” means the solid weight of all resin components (including crosslinked resin particles) contained in the cationic electrodeposition coating composition.

 [0059] The content of the crosslinked resin particles in the present invention is low in ash and low solid content type cationic electrodeposition coating composition, so that both surface smoothness and end face coverage are compatible. Based on the solid content of the resin, the force is preferably 3 to 15% by weight. The lower limit is preferably 4% by weight, more preferably 5% by weight. On the other hand, the upper limit is preferably 10% by weight, more preferably 8% by weight.

[0060] Considering that the average particle size of the crosslinked resin particles is 1.0 to 3.0 m, It is preferable to be produced by turbid polymerization. Production by other methods such as emulsion polymerization is also possible as long as the particle size and heat softening temperature satisfy the above ranges, but suspension polymerization is preferred from the viewpoint of aligning the particle size within a desired range.

[0061] The crosslinked resin particles are not particularly limited, and for example, resin particles made of a resin having a crosslinked structure obtained mainly from an ethylenically unsaturated monomer, and resin particles made of an internally crosslinked urethane resin. To mention fine resin particles made of internally cross-linked melamine resin, the force S is used.

 [0062] The resin having a crosslinked structure obtained mainly from the ethylenically unsaturated monomer is not particularly limited, and includes, for example, a crosslinkable monomer as an essential component and an ethylenically unsaturated monomer. An aqueous dispersion prepared by suspension polymerization of the monomer composition in an aqueous medium, internally crosslinked resin particles obtained by a method such as solvent replacement of the aqueous dispersion, or an aliphatic hydrocarbon, etc. The monomer dissolves but the polymer does not dissolve, such as low SP organic solvents or high SP organic solvents such as esters, ketones, and alcohols. Internally cross-linked resin obtained by a method such as the NAD method or precipitation method that disperses internally cross-linked resin particles obtained by copolymerizing a monomer composition containing an ethylenically unsaturated monomer as an essential component Examples thereof include particles.

 [0063] The ethylenically unsaturated monomer is not particularly limited, and examples thereof include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate. , Alkylesterol of acrylic acid or methacrylic acid such as 2-ethylhexyl (meth) acrylate; styrene, α-methylstyrene, butyltoluene, t-butylstyrene, ethylene, propylene, vinylinole acetate, bininole propionate, acrylonitrile, Examples include mettalylonitrile and dimethylaminoethyl (meth) acrylate. The ethylenically unsaturated monomers may be used in combination of two or more.

 [0064] The crosslinkable monomer is not particularly limited, and examples thereof include a monomer having two or more radically polymerizable ethylenically unsaturated bonds in the molecule and a group capable of reacting with each other. And two types of ethylenically unsaturated group-containing monomers.

[0065] The monomer having two or more radically polymerizable ethylenically unsaturated groups in the molecule that can be used for the production of the internally crosslinked fine resin particles is not particularly limited. For example, ethylene glycol diatalylate, ethylene glycol dimetatalylate, triethylene glycol dimetatalylate, tetraethylene glycol dimethacrylate, 1,3-butylene glycol dimetatalylate, trimethylolpropane tritalylate, trimethylolpropane trimethylate Tartrate, 1,4 butanediol diatalate, neopentyl glycol diatalate, neopentyl glycol dimetatalylate, 1,6-hexanediol diatalate, pentaerythritol diatalate, pentaerythritol retanolate terate, Pentaerythritol tetraatalylate, Pentaerythritol dimetatalylate, Pentaerythritol Retrimetatalylate, Pentaerythritol Tetramethacrylate Talelate, Glycerol Norese Methacrylate, Glycellono Resital Tartrate, Glycello Norelaryloxydimetatalylate, 1, 1, 1 Trishydroxymethinoreethane Diatalylate, 1, 1, 1 Trishydroxymethinoreethane tritalate, 1, 1, 1 Trishydroxymethinoleethane dimetatalylate, 1, 1, 1-trishydroxymethylethane trimethacrylate, 1, 1, 1-trishydroxymethylpropandarate, 1, 1, 1-trishydroxy Polymeric unsaturated monocarboxylic acid esters of polyhydric alcohols such as methylpropane dimetatalylate; polybasic compounds such as triallyl cyanurate, triallyl isocyanurate, triallyl trimellitate, diallyl terephthalate, diallyl phthalate Acid polymerizable unsaturated alcohol Ether; and aromatic substituted with two or more Bulle group di Bulle benzene compounds.

[0066] The combination of the functional groups reacting with each other present in the monomer having two types of ethylenically unsaturated groups, each carrying a group capable of reacting with each other, is not particularly limited. For example, an epoxy group And carboxyl group, amino group and carbonyl group, epoxy group and carboxylic acid anhydride group, amino group and carboxylic acid chloride group, alkyleneimino group and carbonyl group, nonenoalkoxysilane group and carboxyl group, hydroxyl group and isocyanate A combination of glycidinore acrylate and the like can be mentioned. Of these, a combination of an epoxy group and a carboxyl group is more preferable.

[0067] The resin particles comprising the internally crosslinked urethane resin are formed by reacting a polyisocyanate component with a diol having a hydroxyl group at the terminal and a diol having a carboxyl group or an active hydrogen-containing component having a triol. An isocyanate end group-containing polyurethane prepolymer having an acid salt in the side chain is continuously added, and active hydrogen is contained. It is a fine resin particle composed of a polyurethane polymer obtained by reacting with a chain extender.

 [0068] The polyisocyanate component used in the prepolymer is diphenylmethane 4, 4 'isocyanate; hexamethylene diisocyanate, 2, 2, 4 trimethyl hexane diisocyanate, or other aliphatic diisocyanates; Xanthenediisocyanate, 1 isocyanato 3-toisocyanatomethyl-3, 5 trimethylcyclohexane (isophorone diisocyanate), 4, 4'-dicyclohexylmethane diisocyanate, methylcyclodiylene diisocyanate, etc. Can include alicyclic diisocyanates; The polyisocyanate component is more preferably hexamethylene diisocyanate or isophorone diisocyanate.

 [0069] The diol having a hydroxyl group at the terminal is not particularly limited, and examples thereof include a polyester resin having a molecular weight of 100 to 5,000, a polyester resin, a polycarbonate resin, and a polycarbonate resin. The diol having a hydroxyl group at the terminal is not particularly limited, and examples thereof include polyethylene glycol, polypropylene glycol, polytetramethylene glycolate, polybutylene adipate, polyhexamethylene adipate, polyneopentinorea dipate, and polystrength prolatatone diol. And poly-3-methylvalerolatatondiol, polyhexamethylene carbonate, and the like.

[0070] The carboxyl group-containing diol is not particularly limited, and examples thereof include dimethylolacetic acid, dimethylolpropionic acid, and dimethylolbutyric acid. Of these, dimethylolpropionic acid is preferable.

[0071] The triol is not particularly limited, and examples thereof include trimethylolpropane, trimethylolethane, glycerin polystrength prolataton triol, and the like. By using triol, the inside of urethane resin particles takes a cross-linked structure.

[0072] The fine resin particles composed of the internally cross-linked melamine resin are not particularly limited. For example, the melamine resin and the polyol are dispersed in water in the presence of an emulsifier, and then dispersed in the particles formed by the dispersion. Examples thereof include internally cross-linked melamine resin particles obtained by performing a cross-linking reaction between a polyol and a melamine resin. [0073] The melamine resin is not particularly limited, and examples thereof include G, Tree, Tetra, Pentahexer methylol melamine and alkyl etherated products thereof (alkyl is methyl, ethyl, propyl, isopropyl, butyl, isobutynole) and the like. The ability to raise S. Examples of the melamine resin that are commercially available include Cymel 303, Simenore 325, and Cymenole 156 manufactured by Mitsui Cytec.

[0074] The polyol is not particularly limited, and examples thereof include triol having a molecular weight of 500, 3000, tetrolol and the like. Polyol ether triol and polyethylene ether triol are more preferred as the polyol.

 [0075] The above-mentioned crosslinked resin particles are obtained by isolating finely crosslinked resin particles by a method such as mouth-mouthing, spray drying, freeze drying, etc., and pulverizing them to an appropriate particle size using a mill or the like. Even if it is used in a state, the obtained aqueous dispersion may be used as it is or after replacing the medium by solvent replacement.

 [0076] As a second method for adjusting the viscoelastic behavior, the amount of inorganic pigment is 10 20 wt% (hereinafter sometimes referred to as "PWC") in the solid content of the cationic electrodeposition coating composition. There is a method to use in. In conventional cationic electrodeposition coatings, the PWC is more than 20% by weight and not more than 25% by weight, and the strength of the PWC that cannot achieve both smoothness and end face coverage is 10 to 20% by weight. It is possible to achieve both of these performances by using the above. Here, PWC refers to the ratio of the resin component and pigment component contained in the cationic electrodeposition coating composition to the solid content. If the PWC of the inorganic pigment is less than 10% by weight, the resin content will increase, and the resin will soften as the temperature rises, so the desired high viscosity cannot be obtained. Can not do it. On the other hand, if the PWC exceeds 20% by weight, the amount of pigment increases, and the fusing effect of the resin cannot be obtained. As a result, the high viscosity is not exhibited, and it becomes difficult to control the viscoelasticity. For inorganic pigments, as described above, the force S that PWC affects the viscous behavior, and its particle size does not significantly affect the viscous behavior.

[0077] The inorganic pigment used here is not particularly limited as long as it is a pigment usually used in an electrodeposition coating composition. Examples of pigments include commonly used inorganic pigments, e.g. colored pigments such as titanium white and bengara; kaolin, talc, aluminum silicate, charcoal Extender pigments such as calcium phosphate, myrtle and clay; zinc phosphate, iron phosphate, anolenium phosphate, calcium phosphate, zinc phosphite, zinc cyanide, zinc oxide, aluminum tripolyphosphate, zinc molybdate, molybdic acid Examples include aluminum, calcium molybdate, aluminum phosphomolybdate, zinc aluminum phosphomolybdate, bismuth compounds, and antifungal pigments such as cerium compounds.

 [0078] A third method for adjusting the viscoelastic behavior is to use the crosslinked resin particles and an inorganic pigment in combination. In this case, the average particle diameter of the crosslinked resin particles is 1.0 to 3.0, and the amount used is 3 to 15% by weight in the solid content of the paint. On the other hand, the amount of inorganic pigment used can be reduced in the solid content of the cationic electrodeposition coating composition (PWC) O. 5 to 10% by weight. The lower limit is preferably 1% by weight, more preferably 2% by weight. On the other hand, the upper limit is preferably 7% by weight, more preferably 5% by weight. If it is used in an amount exceeding 10% by weight, the amount of pigment will increase more than necessary, and the horizontal appearance may deteriorate due to sedimentation of the pigment. On the other hand, if it is less than 0.5% by weight, the color hiding property may be lowered.

 [0079] By using both the inorganic pigment and the crosslinked resin particles, the amount of the inorganic pigment can be further reduced, and as a result, reduction of energy and labor for preventing sedimentation of the solid content of the electrodeposition paint is expected. it can. In addition, if the viscoelastic behavior is adjusted using only crosslinked resin particles without using inorganic pigments, it is possible to greatly reduce the energy and labor for preventing sedimentation of the solid content. If inorganic pigments are not included! / Or include! / Even in very small amounts, the objects to be coated are washed with water after electrodeposition coating, but the washing process is greatly shortened. A great effect can be achieved, such as simplification of equipment and reduction of resource use.

 [0080] Next, components used in a general cationic electrodeposition coating composition will be described.

 [0081] Cationic electrodeposition coating composition

The composition for cationic electrodeposition coating composition contains an aqueous medium, a power to disperse in the aqueous medium, or a binder resin containing a dissolved cationic epoxy resin and a block isocyanate curing agent, a neutralizing acid, and an organic solvent. . The cationic electrodeposition coating composition may further contain an inorganic pigment, but the amount thereof is preferably 7% by weight or less based on the solid content of the cationic electrodeposition coating composition. As mentioned above, when promoting low ash differentiation, it is better not to include inorganic pigments. Good. In the present invention, as described above, in order to achieve both surface smoothness and end face coverage in a low ash and low solid content cationic electrodeposition coating composition, the specific crosslinked resin particles are added to the cationic electrodeposition coating composition. You may mix | blend with.

 [0082] Cationic epoxy resin

 The cationic epoxy resin used in the present invention includes an epoxy resin modified with amine. Cationic epoxy resins typically have the ability to open with active hydrogen compounds that can introduce cationic groups into all of the epoxy rings of bisphenol type epoxy resins, or some epoxy rings to other It is produced by opening a ring with an active hydrogen compound and opening the remaining epoxy ring with an active hydrogen compound capable of introducing a cationic group.

 [0083] A typical example of the bisphenol type epoxy resin is a bisphenol A type epoxy resin or a bisphenol F type epoxy resin. As the former commercial product, YD-7011R (manufactured by Tohto Kasei Co., Ltd., epoxy equivalent 460 to 490), Epicot 828 (manufactured by Yuka Shell Epoxy, epoxy equivalent 180 to 190), Epico Epoxy equivalent 450-500), Epico pancake 0 (same as epoxy equivalent 3000-4000), etc., and the latter commercially available products such as Epicoat 807, (epoxy equivalent 170).

 [0084] The following formula described in JP-A-5-306327:

[0085] [Chemical 1]

0-C /

 C-G

 / \ / \

 -CH

 \ / \ / 0 0

[0086] [wherein R is a residue obtained by removing / resolving the glycidyloxy group of the diglycidyl epoxy compound, R ′ is a residue obtained by removing the isocyanate group of the diisocyanate compound, and n is a positive integer. To do. An oxazolidone ring-containing epoxy resin represented by the above formula may be used as a cationic epoxy resin. This is because a coating film having excellent heat resistance and corrosion resistance can be obtained.

[0087] As a method for introducing an oxazolidone ring into an epoxy resin, for example, a block isocyanate curing agent blocked with a lower alcohol such as methanol and a polyepoxide are heated and kept in the presence of a basic catalyst to produce a by-product. The lower alcohol to be distilled from the system It is obtained by.

 [0088] It is known that an epoxy resin containing an oxazolidone ring can be obtained by reacting a difunctional epoxy resin and a diisocyanate blocked with a monoalcohol (ie, bisurethane). Specific examples and production methods of this oxazolidone ring-containing epoxy resin are described in, for example, paragraphs 0012 to 0047 of JP-A-2000-128959 and are publicly known.

 [0089] These epoxy resins may be modified with an appropriate resin such as polyester polyol, polyether polyol, and monofunctional alkylphenol. Epoxy resins also have the ability to extend the chain using the reaction of epoxy groups with diols or dicarboxylic acids.

 [0090] These epoxy resins are active hydrogen compounds such that after ring opening, an amine equivalent of 0.3-3 Omeq / g is obtained, and more preferably 5-50% of them are occupied by primary amino groups. It is desirable to open the ring at.

 [0091] The active hydrogen compound into which a cationic group can be introduced includes primary amines, secondary amines, tertiary amine acid salts, sulfides and acid mixtures. In order to prepare a primary, secondary or / and tertiary amino group-containing epoxy resin, primary amine, secondary amine, or tertiary amine acid salts are used as active hydrogen compounds capable of introducing cationic groups.

 [0092] Specific examples include butylamine, octylamine, jetylamine, dibutylamine, methylbutyramine, monoethanolamine, diethanolamine, N-methylethanolamine, triethylamine hydrochloride, N, N dimethyl monoethanolamine acetate, jetyl disulfide In addition to acetic acid mixtures, there are secondary amines that are blocked from primary amines such as ketimine of aminoethylethanolamine and diketimine of diethylenetriamine. Amines can be used in combination of several types.

 [0093] Boucuccin isocyanate curing agent

The polyisocyanate for obtaining the block isocyanate curing agent of the present invention refers to a compound having two or more isocyanate groups in one molecule. The polyisocyanate may be, for example, any of aliphatic, alicyclic, aromatic and aromatic aliphatic. [0094] Specific examples of polyisocyanates include aromatic diisocyanates such as tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), p-phenylene diisocyanate, and naphthalene diisocyanate. 1 to 4 aliphatic diisocyanates such as hexamethylene diisocyanate (HDI), 2,2,4-trimethylhexane diisocyanate, lysine diisocyanate and the like; -Cyclohexane diisocyanate (CDI), isophorone diisocyanate (IPDI), 4,4'-dicyclohexylenomethane diisocyanate (hydrogenated MDI), methylcyclohexane diisocyanate, isopropylidene Cyclohexyl, 4,4'-diisocyanate, and 1,3-diisocyanatomethylcyclohexane (hydrogenated XDI), hydrogenated TDI, 2,5- Aliphatic diisocyanates having 5 to 18 carbon atoms such as 2,6-bis (isocyanatomethyl) bibicyclo [2.2.1] heptane (also called norbornane diisocyanate); Aliphatic diisocyanates having aromatic rings such as cyanate (XDI) and tetramethylxylylene diisocyanate (TMXDI); modified products of these diisocyanates (eg urethanates, carpositimides, uretdiones, uretonimines) , Burette and / or isocyanurate modified product); These can be used alone or in combination of two or more.

 [0095] An adduct or prepolymer obtained by reacting a polyisocyanate with a polyhydric alcohol such as ethylene glycol, propylene glycol, trimethylolpropan or hexanetriol at an NCO / OH ratio of 2 or more is also cured with a block isocyanate. May be used in preparations.

 [0096] A blocking agent is added to a polyisocyanate group and is stable at room temperature, but can regenerate a free isocyanate group when heated to a temperature higher than the dissociation temperature.

 [0097] As the blocking agent, the use of a commonly used ε-force prolatatam, ptylcete solve, or the like is performed with a force S.

 [0098] When the crosslinked resin particles are used as a component of the cationic electrodeposition paint, they may be blended at any stage of producing the electrodeposition paint, but a method of adding directly to the produced cationic electrodeposition paint is preferable. good.

 [0099] Inorganic pigment

The electrodeposition coating composition used in the present invention may contain a commonly used inorganic pigment. When using as a low ash type, do pigments, especially inorganic pigments, reduce the blending amount? It is better not to mix. Examples of inorganic pigments include commonly used inorganic pigments, for example, colored pigments such as titanium white and bengara; extender pigments such as kaolin, talc, aluminum silicate, calcium carbonate, my strength and clay; zinc phosphate , Iron phosphate, aluminum phosphate, calcium phosphate, zinc phosphite, zinc cyanide, zinc oxide, aluminum tripolyphosphate, zinc molybdate, aluminum molybdate, calcium molybdate and aluminum phosphomolybdate, zinc aluminum phosphomolybdate And antibacterial pigments such as bismuth oxide, bismuth hydroxide, basic bismuth carbonate, bismuth nitrate and bismuth sulfate.

[0100] Such an inorganic pigment is 7% by weight or less, preferably 5% by weight or less, more preferably 3% by weight or less based on the solid content of the coating resin in the cationic electrodeposition coating composition. The weight percent of this resin solids is also called PWC. If the inorganic pigment concentration exceeds 7% by weight, low ash differentiation cannot be achieved sufficiently, and the energy burden for preventing sedimentation will increase.

 [0101] When a pigment is used as a component of an electrodeposition paint, generally, the pigment is dispersed in an aqueous medium at a high concentration in advance to form a paste (pigment dispersion paste). This is because the pigment is in a powder form and it is difficult to disperse it in a single step in a low concentration uniform state used in the electrodeposition coating composition. In general, such a paste is called a pigment dispersion paste!

 [0102] The pigment dispersion paste is prepared by dispersing a pigment together with a pigment dispersion resin in an aqueous medium. As the pigment dispersion resin, a cationic polymer such as a cationic or nonionic low molecular weight surfactant or a modified epoxy resin having a quaternary ammonium group and / or a tertiary sulfone group is generally used. Use. As the aqueous medium, ion exchange water or water containing a small amount of alcohol is used.

 [0103] Generally, the pigment-dispersed resin is used in an amount of a solid content ratio of 20 to 100 mass parts with respect to 100 mass parts of the pigment. After the pigment dispersion resin and the pigment are mixed, the pigment is dispersed using a normal dispersing device such as a ball mill or a sand grind mill until the particle size of the pigment in the mixture reaches a predetermined uniform particle size. Obtain a dispersion paste.

[0104] The cationic electrodeposition coating composition used in the present invention includes, in addition to the above components, organic tin compounds such as dibutyltin laurate, dibutyltin oxide, and dioctyltin oxide, N-methyl An amine such as lumorpholine, or a metal salt such as strontium, cobalt, or copper may be included as a catalyst. These can act as a catalyst for the dissociation of the blocking agent of the curing agent. The concentration of the catalyst is preferably 0.;! To 6 parts by mass with respect to 100 solid parts by mass of the total of the cationic epoxy resin and the curing agent in the electrodeposition coating composition.

[0105] Preparation of cationic electrodeposition coating composition

 The cationic electrodeposition coating composition of the present invention comprises the above-described cationic epoxy resin, block isocyanate curing agent, and optionally crosslinked resin particles and / or pigment dispersion paste and catalyst. It can be prepared by dispersing in. Usually, the aqueous medium contains a neutralizing acid in order to neutralize the cationic epoxy resin and improve the dispersibility. The neutralizing acid is an inorganic or organic acid such as hydrochloric acid, nitric acid, phosphoric acid, formic acid, acetic acid, lactic acid, sulfamic acid, or acetylidaricin. The aqueous medium in this specification is water or a mixture of water and an organic solvent. It is preferable to use ion exchange water as water. Examples of organic solvents that can be used include hydrocarbons (eg, xylene or tonoleene), alcohols (eg, methyl alcohol, n-butyl alcohol, isopino pinoleanolenoconole, 2-ethylenohexenoreanonoleconole). , Ethylene glycol, propylene glycol), ethers (eg, ethylene glycol monoethyl ether, ethylene glycol monobutino enoate, ethylene glycol monohexeno enoate, propylene glycol eno eno enoenoate) , 3-methylolene 3-methoxybutanol monoole, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether), ketones (eg, methyl isobutyl ketone, cyclohexanone, isophorone, acetylacetone), Ethers (e.g., ethylene glycol monomethyl E chill ether acetate, ethylene glycol mono butyl ether acetate) or mixtures thereof.

 [0106] The cationic electrodeposition coating composition of the present invention may contain cross-linked resin particles. However, the addition method may be any of the steps for producing the electrodeposition coating. It is preferable to add it directly to the produced cationic electrodeposition coating.

[0107] The amount of the block isocyanate curing agent reacts with active hydrogen-containing functional groups such as primary, secondary amino groups and hydroxyl groups in the cationic epoxy resin at the time of curing to give a good cured coating film. Should generally be sufficient for cationic epoxy resins and block isocyanates It is generally in the range of 90/10 to 50/50, preferably 80/20 to 65/35, expressed as a weight ratio of solids to the curing agent (epoxy resin / curing agent). The amount of neutralizing acid is that which is sufficient to neutralize at least 20%, preferably 30-60%, of the cationic groups of the cationic epoxy resin.

 [0108] The organic solvent is indispensable as a solvent when preparing resin components such as a force thione epoxy resin and a block isocyanate curing agent, and a complicated operation is required for complete removal.

 [0109] When an organic solvent is contained in the cationic epoxy resin as the binder resin component, the fluidity of the coating film during film formation is improved, and the smoothness of the coating film is improved.

 [0110] Examples of the organic solvent usually contained in the coating composition include ethylene glycol monobutyl etherol, ethylene glycol monohexenoleenotenole, ethylene glycol monoethylenohexenoxenoreethenole, and propylene glycolenolemonobutinorein. Examples include tenole, dipropylene glycol monobutyl ether, propylene glycol monophenyl ether.

 [0111] In addition to the above components, the cationic electrodeposition coating composition may contain commonly used coating additives such as a plasticizer, a surfactant, an antioxidant, and an ultraviolet absorber.

 [0112] When the cationic electrodeposition coating composition of the present invention is intended for low solid differentiation, its solid content concentration is 20% by weight or less. Specifically, the solid content concentration of the paint is preferably 0.5 to 9% by weight, and the lower limit thereof is preferably 2% by weight, more preferably 4% by weight. On the other hand, the upper limit is preferably 7% by weight, more preferably 6% by weight. If the solid content concentration is less than 0.5% by weight, a normal coating film cannot be formed. If the solid content concentration is more than 9% by weight, the water washing process is shortened in the cationic electrodeposition coating line, which is the effect of low solid differentiation, and the equipment is reduced. It becomes impossible to obtain effects such as simplification. Here, the solid content concentration refers to the concentration in the coating of the total solid content weight of the pigment component and the resin component (including the crosslinked resin particle component) contained in the cationic electrodeposition coating composition. If the solid content is thus low, the conductivity of the cationic electrodeposition paint may be reduced. Therefore, it is preferable to add a conductivity control agent separately.

[0113] The conductivity control agent used in the present invention is not particularly limited as long as it is a material that adjusts the conductivity of the cationic electrodeposition paint to a desired range, but an amine value of S200 to 500 mmol / 100 g is used. What is comprised from the amino-group containing compound which has is preferable. As long as the conductivity control agent for cationic electrodeposition coating materials of the present invention is prepared so that the amine value is within the above range, any amino group-containing material may be used, but usually an amine-modified epoxy resin or an amine-modified acrylic resin is used. preferable. Further, the conductivity control agent for cationic electrodeposition paints of the present invention may be neutralized with an acid, if necessary. The amine value is preferably 250 to 450 mmol / 100 g, and more preferably 300 to 400 mmol / 100 g. If the amine value is less than 200 mmol / 100 g, the necessary addition amount for adjusting the liquid conductivity of the low solid content cationic electrodeposition coating to the optimum value increases, which may impair the corrosion resistance. On the other hand, if it exceeds 500 mmol / 100 g, the precipitation property is lowered and the desired throwing power cannot be obtained. In addition, the suitability of the galvanized steel sheet also decreases.

 [0114] The conductivity control agent is a compound having a low molecular weight to a high molecular amino group, and usually includes a high molecular weight compound such as a amine-modified epoxy resin or a amine-modified acrylic resin. Examples of the low molecular weight amino group-containing compound include monoethanolamine, diethanolamine, and dimethylbutylamine.

 [0115] Preferred are high molecular weight amino group-containing compounds, particularly amine-modified epoxy resins and amine-modified acrylic resins. The amine-modified epoxy resin can be obtained by modifying an epoxy group of an epoxy resin with an amine compound. Epoxy resins can be used in general, but are bisphenol type epoxy resin, t-butylcatechol type epoxy resin, phenol nopolac type epoxy resin, cresol nopolac type epoxy resin, and molecular weight is 500-20000. Those having the following are preferred. Of these epoxy resins, phenol nopolac type epoxy resins and cresol nopolac type epoxy resins are both desirable. In particular, these epoxy resins are commercially available. Examples thereof include phenol nopolac type epoxy resin DEN-438 manufactured by Dow Chemical Japan, and taresol nopolak type epoxy resin YDCN-703 manufactured by Tohto Kasei Co., Ltd.

[0116] These epoxy resins may be modified with a resin such as polyester polyol, polyether polyol, and monofunctional alkylphenol. Epoxy resins can also be chain-extended using the reaction of epoxy groups with diols or dicarboxylic acids. [0117] As the amine-modified acrylic resin, for example, a homopolymer of dimethylaminoethyl methacrylate, which is an amino group-containing monomer, or a copolymer with another polymerizable monomer may be used as it is, or glycidyl methacrylate. It can be obtained by modifying the glycidyl group of a homopolymer of a rate or a copolymer with another polymerizable monomer with an amine compound.

 [0118] Examples of the compound that introduces an amino group into an epoxy resin or an acrylic resin containing an epoxy group include primary amines, secondary amines, and tertiary amines. Specific examples thereof include butynoreamine, talented cutinoleamine, jetinoreamine, butinoreamine, dimethylenobutynoamine, monoethanolamine, diethanolamine, N-methylethanolamine, triethylamine hydrochloride, N, N-dimethylethanolamine. In addition to acetates, jetyl disulfide'acetic acid mixtures, etc., primary amines such as aminoethylethanolamine diketimines and primary alkylamine blocked secondary amines such as diketimines of jetylhydroamine are listed. A plurality of amines may be used.

 [0119] As described above, the number average molecular weight of these amine-modified epoxy resins and amine-modified acrylic resins is preferably 500 to 20,000. If the number average molecular weight is less than 500, corrosion resistance may be impaired, and although the reason is not clear, a decrease in throwing power and a decrease in suitability for galvanized steel sheets are observed. If the number average molecular weight is greater than 20000 !, there is a risk of causing a decrease in the finished appearance.

 [0120] These amine-modified epoxy resin and amine-modified acrylic resin can be used after neutralization with a neutralizing acid in advance. Acids used for neutralization are inorganic acids or organic acids such as hydrochloric acid, nitric acid, phosphoric acid, sulfamic acid, formic acid, acetic acid, and lactic acid.

 [0121] Method of applying cationic electrodeposition coating composition

 The cationic electrodeposition coating composition is electrodeposited on an object to form an electrodeposition coating film. The material to be coated is not particularly limited as long as it is electrically conductive, and examples thereof include iron plates, steel plates, aluminum plates, those obtained by surface treatment thereof, and molded products thereof.

[0122] Electrodeposition of the cationic electrodeposition coating composition is usually carried out by applying a voltage of 50 to 450 V between the object to be coated as the cathode and the anode. If the applied voltage is less than 50V, electrodeposition is insufficient, and if it exceeds 450V, the coating is destroyed and the appearance becomes abnormal. During electrodeposition coating, the bath temperature of the coating composition is usually adjusted to 10 to 45 ° C. [0123] The electrodeposition coating step includes a step of immersing an object to be coated in a cationic electrodeposition coating composition, and a step of applying a voltage between the above object to be coated as a cathode and an anode to deposit a film. Composed. The time for applying the voltage varies depending on the electrodeposition conditions. In general, the force is 2 to 4 minutes.

[0124] The film thickness of the electrodeposition coating film can be generally formed in the range of 5 to 2511 m. If the film thickness is less than 5 μm, the anti-mold property may be insufficient. If the film thickness exceeds 25 m, the film thickness is more than necessary to obtain the coating film performance. The film resistance of the electrodeposition coating film is preferably 1000 to 1600 kQ / cm ² at a film thickness of 15 111. Film resistance of the coating film is in a state that is not obtained sufficient electric resistance is less than 10 00k Ω / cm ^2, there is a possibility that poor throwing, also more than 1600k Ω / cm ² when the film appearance May be inferior. The film resistance of the coating film is more preferably 1100-1500 kQ / cm ² .

 [0125] The film resistance value of the coating film can be obtained by the following formula from the residual current value (A) of the coating film at the final coating voltage (V).

 Membrane resistance (FR) = V / A

 [0126] The electrodeposition coating film obtained as described above is 120 to 260 after completion of the electrodeposition process, or after being washed with water. C, preferably 140-220. It is hardened by baking with C for 10 to 30 minutes to obtain a cured electrodeposition coating film.

 [0127] The cured electrodeposition coating film of the present invention has an Ra value that is used for evaluation of surface smoothness with high surface smoothness, and is preferably 0.25 mm or less, more preferably 0.20 mm or less. is there. The lower limit is preferably zero. The Ra value was measured in accordance with JIS-B0601 using an evaluation type surface roughness measuring machine (manufactured by Mitutoyo Corporation, SURFTEST SJ-201P). Ra value force S The smaller the roughness, the better the appearance of the coating film with less unevenness.

[0128] In the present invention, in the method of forming a cationic electrodeposition coating film by immersing an object to be coated in the cationic electrodeposition coating material and applying a voltage, the cationic electrodeposition coating material has an average particle size of 1.0. Provided is a method for achieving both the smoothness and end face coverage of a cationic electrodeposition coating film characterized by containing crosslinked resin particles having a viscosity of ˜3.0 m and a thermal softening temperature of 120 to 180 ° C. Further, in the present invention, the above-mentioned specific crosslinked resin particles are added to the cationic electrodeposition paint as an additive even in a low solid content type and low ash content type cationic electrodeposition paint. In addition to improving the ability to prevent sedimentation of the solid content of the electrodeposition paint, it is possible to achieve both surface smoothness and end face coverage. In this case, the blending amount is 3 to 15% by weight based on the solid content of the cationic electrodeposition paint.

 Example

 [0129] The following examples further illustrate the present invention, but the present invention is not limited thereto. Unless otherwise specified, “parts” represents parts by weight.

[0130] Production Example 1A Production of block isocyanate curing agent

 Hexamethylene diisocyanate trimer (Coronate HX: manufactured by Nippon Polyurethane Co., Ltd.) in a flask equipped with a stirrer, cooler, nitrogen injection tube, thermometer and dropping funnel

While stirring and bubbling nitrogen, 87.0 parts of methyl ethyl ketoxime was added dropwise from the dropping funnel over 1 hour. The temperature was increased from 50 ° C to 70 ° C. Thereafter, the reaction was continued for 1 hour, and the reaction was continued until the absorption of NCO groups disappeared with an infrared spectrometer. Thereafter, 0.74 parts of n-butanol and 39.93 parts of methyl isobutyl ketone were prepared to make a nonvolatile content of 80%.

 [0131] Production Example 2 Production of A-amine-modified epoxy resin emulsion

 In a flask equipped with a stirrer, cooler, nitrogen inlet tube and dropping funnel, 2, 4/2, 6 tolylene diisocyanate (80/20 wt%) 71.34 parts, methyl isobutyl ketone 111.98 parts, While weighing out 0.22 parts of dibutyltin dilaurate and stirring and nitrogen bubbling, 14.24 parts of methanol was added dropwise from a dropping funnel over 30 minutes. The temperature rose from room temperature to 60 ° C due to heat generation. Thereafter, the reaction was continued for 30 minutes, and then 46.98 parts of ethylene glycol mono-2-ethylhexyl ether was added dropwise from the dropping funnel over 30 minutes. The temperature rose to 70-75 ° C due to heat generation. After continuing the reaction for 30 minutes, add 41 · 25 parts of Bisphenol A propylene oxide (5 mol) adduct (BP-5Ρ, Sanyo Chemical Industries Co., Ltd.), raise the temperature to 90 ° C, and measure the IR spectrum The reaction was continued until the NCO group disappeared.

 [0132] continued! /, Bisphenol A type epoxy resin with an epoxy equivalent of 475 (YD manufactured by Tohto Kasei Co., Ltd.)

7011R) 475. 0 咅 free from calorie, uniformly melted quickly, 130. C force, et al 142. The temperature was raised to C, and water was removed from the reaction system by azeotropy with Ml BK. After cooling to 125 ° C, benzyldimethyl 1. 107 parts of lumine were added and an oxazolidone ring formation reaction was carried out by a methanol removal reaction. The reaction was continued until an epoxy equivalent of 1140.

 [0133] After cooling to 100 ° C, 24 · 56 parts of N-methylethanolamine, 11 · 46 parts of diethanolamine and 26 · 08 parts of aminoethylethanolamine ketimine (78/8% methyl isobutyl ketone solution) were added. In addition, the reaction was carried out at 110 ° C for 2 hours. Thereafter, 20.74 parts of ethylene glycol mono-2-ethylhexyl ether and 12.85 parts of methyl isobutyl ketone were diluted by dilution and adjusted to 82% non-volatile matter. The number average molecular weight (GPC method) was 1380, and the amine equivalent was 94.5 meq 100 g.

 [0134] In a separate container, 145.11 parts of ion-exchanged water and 5.04 parts of acetic acid were weighed and heated to 70 ° C. 320.11 parts of the above amine-modified epoxy resin (75.0 parts as solids) A mixture of 190.38 parts of the block isocyanate curing agent of Production Example 1A (25.0 parts as a solid content) was gradually added dropwise and stirred to disperse uniformly. After that, ion exchange water was added to adjust the solid content to 36%.

 [0135] Production Example 3A Production of pigment-dispersed resin

 A flask equipped with a stirrer, cooler, nitrogen injection tube, thermometer and dropping funnel was charged with 382.20 parts of bisphenol A type epoxy resin (trade name DER—331J) with an epoxy equivalent of 188 and bisphenol A111.98 parts. The sample was weighed, heated to 80 ° C., and uniformly dissolved. Then, 1 · 53 parts of a 2-ethyl-4-methylimidazole 1% solution was added and reacted at 170 ° C. for 2 hours. After cooling to 140 ° C, 196.50 parts of 2-ethylhexanol half-blocked isophorone diisocyanate (nonvolatile content 90%) was added and reacted until the NCO group disappeared. To this was added 205.00 parts of dipropylene glycol monobutyl ether, followed by addition of 408.00 parts of 1- (2-hydroxyethylthio) -2-propanol and 134.00 parts of dimethylolpropionic acid. Calored 144.00 parts of exchanged water and reacted at 70 ° C. The reaction was continued until the acid value was 5 or less. The obtained resin varnish was diluted with ion exchange 11 SO-SO part to a non-volatile content of 35%.

 [0136] Production Example 4A Production of pigment dispersion paste

In a sand grind mill, 120 parts of the pigment-dispersed resin varnish obtained in Production Example 3A, 100 parts of kaolin, 92 parts of titanium dioxide, 8.0 parts of dibutyltinoxide and ion-exchanged water 184 Part was dispersed until the particle size became 10 πι or less to obtain a pigment dispersion paste. (Solid content 48%)

 [0137] Production Example 5Α Production of crosslinked resin particles

 In a reaction vessel, 120 parts of butyl solvate was placed and stirred at 120 ° C with heating. This was a mixture of 2 parts t-butyl peroxy 2-ethylhexanoate and 10 parts butylcetosolve and glycidinoremethalate 15 咅 ^ 2 ethinorehexinoremethalate 50 咅 ^ 2-hydroxy A monomer mixture having an SP value of 1 consisting of 20 parts of tilmetatalylate and 15 parts of η-butylmetatalylate was added dropwise over 3 hours. After aging for 30 minutes, a mixed solution of 0.5 parts of t-butylperoxy-2-ethylhexanoate and 5 parts of butyl cellosolve was added dropwise over 30 minutes, and after aging for 2 hours, the mixture was cooled. To this, 7 parts of N, N dimethylaminoethanol and 15 parts of a 50% aqueous lactic acid solution were added, and the mixture was heated and stirred at 80 ° C. for quaternization. When the acid value became 1 or less and the increase in viscosity stopped, heating was stopped to obtain an acrylic resin having an ammonium group. The number of ammonium groups per molecule of the acrylic resin having ammonium groups was 6.0.

 [0138] To the reaction vessel, 120 parts of an acrylic resin having an ammonium group and 270 parts of deionized water were added, and the mixture was heated and stirred at 75 ° C. 2,2′azobis (2- (2 imidazoline 2 yl) propane) 1. 5 parts of a 100% neutralized aqueous solution of acetic acid was added dropwise over 5 minutes. After aging for 5 minutes, 30 parts of methyl metatalylate was added dropwise over 5 minutes. After aging for an additional 5 minutes, 170 parts of acrylic resin having ammonium groups and 250 parts of deionized water were mixed together. 170 parts of methinore methacrylate, 40 parts of styrene, 30 parts of methanolate, 30 parts of glycidyl methacrylate. A pre-emulsion obtained by adding and stirring an α, β ethylenically unsaturated monomer mixture consisting of 5 parts of a rate and 30 parts of neopentyldalycol dimetatalylate was added dropwise over 40 minutes. The mixture was cooled to obtain a dispersion of crosslinked resin particles 1. The dispersion of the obtained crosslinked resin particles had a nonvolatile content of 35%, ρΗ was 5.0, and the average particle size was lOOnm.

 [0139] Production Example 6A Production of non-crosslinked resin particles

2 parts of lauroyl peroxide was dissolved in a mixed solution of 104 parts of styrene, 20 parts of 2-ethylhexyl methacrylate and 76 parts of laurinomethacrylate. This is Polyburu Arco (Gousenol GH-17, manufactured by Nippon Gosei Co., Ltd.) 8 parts of an aqueous solution prepared by dissolving in deionized water is added to 497 parts with stirring. Disperser) A suspension was produced at 3500 rpm.

 [0140] This suspension was subjected to suspension polymerization for 5 hours at a stirring speed of 150 rpm and a reaction temperature of 81 to 83 ° C using a normal batch-type reaction vessel. After cooling, the obtained dispersion was 200 mesh. Filtration through a net gave non-crosslinked resin particles. The obtained non-crosslinked resin particle dispersion had a non-volatile content of 30% and an average particle size of 3 Hm.

 [0141] Example 1A

 Mixing 2222 parts of the emulsion obtained in Production Example 2A and 417 parts of the pigment dispersion paste obtained in Production Example 4A with 2361 parts of ion-exchanged water, PWC = 16.5%, crosslinked resin particles 0 A cationic electrodeposition coating composition having a weight percentage of 20% by weight was obtained.

[0142] Comparative Example 1A

 Production Example 2 738 parts of emulsion obtained in A and 4 parts of dibutyltinoxide were mixed with 4598 parts of ion-exchanged water to obtain a cationic battery having PWC = 0%, crosslinked resin particles 0% by weight, and solid content 5% by weight. A coating composition was obtained.

[0143] Comparative Example 2A

 702 parts of the emulsion obtained in Production Example 2A, 38 parts of the crosslinked resin particles obtained in Production Example 5A and 4 parts of dibutyltinoxide, and 4596 parts of ion-exchanged water were mixed, and PWC = 0%, crosslinked resin particles. A cationic electrodeposition coating composition having 5% by weight and a solid content of 5% by weight was obtained.

[0144] Comparative Example 3 A

 Mixing 665 parts of the emulsion obtained in Production Example 2A and 76 parts of the crosslinked resin particles obtained in Production Example 5A and 4 parts of dibutyltin oxide and 4596 parts of ion-exchanged water, PWC = 0%, crosslinked resin particles A cationic electrodeposition coating composition having 10% by weight and a solid content of 5% by weight was obtained.

[0145] Comparative Example 4A

Mixing 665 parts of the emulsion obtained in Production Example 2A, 89 parts of the non-crosslinked resin particles obtained in Production Example 6A and 4 parts of dibutyltinoxide, and 4582 parts of ion-exchanged water, PWC = 0%, non- A cationic electrodeposition coating composition having 10% by weight of crosslinked resin particles and 5% by weight of solid content was obtained. [0146] Comparative Example 5 A

 389 parts of the emulsion obtained in Production Example 2A and 125 parts of the pigment dispersion paste obtained in Production Example 4A were mixed with 3486 parts of ion-exchanged water, PWC = 25%, crosslinked resin particles 0% by weight, A cationic electrodeposition coating composition having a solid content of 5% by weight was obtained.

[0147] Example 2 A

702 parts of emulsion obtained in Production Example 2A, cross-linked resin particles (cross-linked resin particles mainly composed of methyl methacrylate; manufactured by Toyobo Co., Ltd., Tuftic ^(ffi) F-200) and dibutyl tin ^oxide 4 And 4592 parts of ion-exchanged water were mixed to obtain a cationic electrodeposition coating composition having PWC = 0%, crosslinked resin particles 5% by weight, and solid content 5% by weight.

[0148] Example 3A

665 parts of the emulsion obtained in Production Example 2A, crosslinked resin particles (crosslinked resin particles mainly composed of methyl methacrylate; 84 parts of Tuftic ^(ffi) F-200, manufactured by Toyobo Co., Ltd.), and dibutyltinoxide 4 And 4587 parts of ion-exchanged water were mixed to obtain a cationic electrodeposition coating composition having PWC = 0%, crosslinked resin particles 10% by weight, and solid content 5% by weight.

[0149] Example 4A

628 parts of emulsion obtained in Production Example 2A, cross-linked resin particles (cross-linked resin particles mainly composed of methyl methacrylate; Toyobo Co., Ltd., Tuftic ^(ffi) F-200) 127 parts and dibutyl tin ^oxide 4 parts and 4581 parts of ion-exchanged water were mixed to obtain a cationic electrodeposition coating composition having PWC = 0%, bridge resin particles 15% by weight, and solid content 5% by weight.

[0150] Example 5 A

 628 parts of emulsion obtained in Production Example 2A, crosslinked resin particles (crosslinked resin particles mainly composed of styrene monomer; manufactured by Soken Chemical Co., Ltd., Chemisnow SX500H, average particle diameter 3 m), 40 parts, and dibutyltinoxide 4 parts and 4668 parts of ion-exchanged water were mixed to obtain a cationic electrodeposition coating composition having PWC = 0%, crosslinked resin particles 15% by weight, and solid content 5% by weight.

 [0151] Example 6A

567 parts of the emulsion obtained in Production Example 2A, 54 parts of the pigment dispersion paste obtained in Production Example 4A and crosslinked resin particles (crosslinked resin particles mainly composed of styrene monomer; Soken Chemical) Co., Ltd., Chemisnow SX500H, average particle size 3 m) 40 咅 and 4739 交換 water exchanged water are mixed, PWC = 8%, cross-linked resin particles 15 wt%, solid content 5 wt% A cationic electrodeposition coating composition was obtained.

 [0152] With respect to the cationic electrodeposition coating composition thus obtained, the loss elastic modulus at 80 ° C, storage elastic modulus at 140 ° C, smoothness and end face coverage of dynamic viscoelasticity were determined by the following methods. Evaluation was performed.

 [0153] Measurement of Loss Modulus and Storage Modulus of Electrodeposition Coating

 A tin plate is dipped in the cationic electrodeposition paint obtained above, and an electrodeposition coating film is formed by coating at a coating voltage such that the film thickness after baking is Ιδΐη. The electrodeposition paint composition was removed. Next, after removing moisture, the uncured coating piece was immediately taken out without drying, and a sample was prepared. The sample obtained in this manner was subjected to temperature-dependent measurement in dynamic viscoelasticity using a rotational dynamic viscoelasticity measuring device Rheosol-G3000 (manufactured by UBM). The measurement was performed at 5 deg and a frequency of 0.02 Hz. The prepared sample was set and the measurement temperature was kept at 50 ° C. After the measurement was started, the viscosity of the coating film was measured when the electrodeposition coating film spread uniformly in the cone plate.

 [0154] The view of snow

 The appearance of the electrodeposition coating film was evaluated by measuring the arithmetic average roughness (Ra) of the roughness curve. An uncured electrodeposition coating obtained by immersing a cold-rolled steel sheet treated with zinc phosphate in the cationic electrodeposition coating obtained above and coating it at a coating voltage such that the film thickness after baking is 15 m. The membrane was baked at 160 ° C for 10 minutes. Thereafter, the Ra value of this cured electrodeposition coating film was measured using an evaluation type surface roughness measuring instrument (SURFTEST SJ-201P, manufactured by Mitutoyo Corporation) in accordance with JIS-B0601. 2. Using a sample with a 5mm width cut-off (5 compartments), measurement was performed 7 times, and the Ra value was obtained by averaging the top and bottom. The results are shown in Table 1. It can be said that the smaller the Ra value, the better the appearance of the coating film with less unevenness.

 [0155] End ffi covering 'Gunpeira ¼

A cationic knife electrodeposition coating composition is immersed in a coating material of a cutter knife (OLFA: LB 50K) that has been treated with zinc phosphate, and a voltage is applied between the coating material and the anode as a cathode. Deposit the film. The electrodeposition conditions were applied voltage and time adjusted so that the deposited film thickness was カ ッ タ ー δΐη on the cutter knife. The obtained electrodeposition coating film was washed with water and baked at 160 ° C. for 10 minutes to obtain a cured electrodeposition coating film.

 [0156] Fold the center of the cutter knife coated with the electrodeposition coating film, and measure the film thickness of the electrodeposition coating film coated on the 30-micron region from the tip of the cutter knife (sharp corner) (manufactured by Keyence Corporation: VH—8000). Figure 9 schematically shows the 30 micron area from the tip of the cutter knife.

[0157] [Table 1]

[0158] As is apparent from Table 1 above, the dynamic viscoelastic loss elastic modulus (G ") and storage elastic modulus (G,) in the specified ranges have smoothness and end face coverage! Specifically, Comparative Example 1A has a storage elastic modulus (G ′) that is out of the range of the present invention, and its end face coverage is not good. 2A is a mixture of the crosslinked resin particles of Production Example 5A, but both the loss elastic modulus (G ") and storage elastic modulus (G ') are out of the scope of the present invention, and smoothness and end face coverage are also included. Not good. Similar to Comparative Example 2A, Comparative Example 3A is also composed of the crosslinked resin particles of Production Example 5A, and the average particle diameter of the crosslinked resin particles used here is as small as lOOnm and loss modulus (G ") In Comparative Example 4A, the non-crosslinked particles are blended, and the value of the storage elastic modulus (G ′) is out of the range of the present invention. Further, Comparative Example 5A is outside the scope of the present invention in terms of the power loss elastic modulus (G ") containing inorganic pigments instead of resin particles, and as a result, smoothness is poor. not good. Further, Example 1A contains the pigment of Production Example 4A, which falls within the scope of the present invention, and has excellent smoothness and end face coverage. In Examples 2A to 6A, the storage elastic modulus (G ′) and the loss elastic modulus (G ″) are controlled within the scope of the present invention by blending specific particles, and both smoothness and end face coverage are achieved. Both are excellent.

 [0159] Production Example 1B Production of block isocyanate curing agent

 Hexamethylene diisocyanate trimer (Coronate HX: manufactured by Nippon Polyurethane Co., Ltd.) in a flask equipped with a stirrer, cooler, nitrogen injection tube, thermometer and dropping funnel

While stirring and bubbling nitrogen, 87.0 parts of methyl ethyl ketoxime was added dropwise from the dropping funnel over 1 hour. The temperature was increased from 50 ° C to 70 ° C. Thereafter, the reaction was continued for 1 hour, and the reaction was continued until the absorption of NCO groups disappeared with an infrared spectrometer. Thereafter, 0.74 parts of n-butanol and 39.93 parts of methyl isobutyl ketone were prepared to make a nonvolatile content of 80%.

 Production Example 2B Production of emulsion containing amine-modified epoxy resin and block isocyanate curing agent

In a flask equipped with stirrer, cooler, nitrogen inlet tube and dropping funnel, 2, 4/2, 6 Tolylene diisocyanate (80 / 20wt%) 71. 34 parts, 111.98 parts of methyl isobutyl ketone and 0 · 02 parts of dibutyltin dilaurate were weighed out, stirred and bubbled with methanol. The portion was dropped from the dropping funnel over 30 minutes. The temperature rose from room temperature to 60 ° C due to heat generation. Thereafter, the reaction was continued for 30 minutes, and then 46.98 parts of ethylene glycol mono-2-ethylhexyl ether was added dropwise from the dropping funnel over 30 minutes. The temperature rose to 70-75 ° C due to heat generation. After continuing the reaction for 30 minutes, add 41 · 25 parts of Bisphenol A propylene oxide (5 mol) adduct (BP-5Ρ, Sanyo Chemical Industries Co., Ltd.), raise the temperature to 90 ° C, and measure the IR spectrum The reaction was continued until the NCO group disappeared.

 [0161] Continued! /, Bisphenol A type epoxy resin with epoxy equivalent of 475 (YD manufactured by Tohto Kasei Co., Ltd.)

 7011R) 475. 0 咅 free from calorie, uniformly melted quickly, 130. C force, et al 142. The temperature was raised to C, and water was removed from the reaction system by azeotropy with Ml BK. After cooling to 125 ° C, 1.107 parts of benzyldimethylamine was added, and an oxazolidone ring formation reaction was carried out by a demethanol reaction. The reaction was continued until an epoxy equivalent of 1140.

 [0162] After cooling to 100 ° C, add 24 · 56 parts of N-methylethanolamine, 11 · 46 parts of diethanolamine and 26 · 08 parts of aminoethylethanolamine ketimine (78 · 8% methylisobutylketone solution) And reacted at 110 ° C for 2 hours. Thereafter, 20.74 parts of ethylene glycol monoethyl hexyl ether and 12.85 parts of methyl isobutyl ketone were diluted and adjusted to 82% non-volatile matter. A number-average molecular weight (GPC method) of 1380 and an amine equivalent of 94.5 meq / 100 g was obtained.

 [0163] 145.11 parts of ion-exchanged water and 5.04 parts of acetic acid were weighed in a separate container and heated to 70 ° C. 320.11 parts of the above amine-modified epoxy resin (75.0 parts as solids) And a mixture of 190.38 parts (25.0 parts as a solid content) of the block isocyanate curing agent of Production Example 1B was gradually added dropwise and stirred to disperse uniformly. After that, ion exchange water was added to adjust the solid content to 36%.

 [0164] Production Example 3B Production of pigment-dispersed resin varnish

A flask equipped with a stirrer, cooler, nitrogen injection tube, thermometer and dropping funnel was charged with 382.20 parts of bisphenol A type epoxy resin (trade name DER—331J) with an epoxy equivalent of 188 and bisphenol A111.98 parts. Weigh out, heat up to 80 ° C, dissolve uniformly, 1 · 53 parts of a 1% solution of 2-ethyl-4-methylimidazole was added and reacted at 170 ° C for 2 hours. After cooling to 140 ° C, 196.50 parts of 2-ethylhexanol half-blocked isophorone diisocyanate (non-volatile content 90%) was added and reacted until the NCO group disappeared. To this was added 205.00 parts of dipropylene glycol monobutyl ether, followed by 1408 (2 hydroxyethylthio) -2-propanol 408.00 parts and 134.00 parts of dimethylolpropionic acid. 144.00 parts were burned and reacted at 70 ° C. The reaction was continued until the acid value was 5 or less. The obtained resin varnish was diluted with ion exchange 11 SO-SO part to a non-volatile content of 35%.

[0165] Production Example 4B Production of pigment dispersion paste

In a sand grind mill, add 120 parts of the pigment-dispersed resin varnish obtained in Production Example 3B, 100.0 parts of kaolin, 92.0 parts of titanium dioxide, 8.0 parts of dibutyltinoxide, and 18 4 parts of ion-exchanged water. Dispersed to 10 πι or less to obtain a pigment dispersion paste (solid content 48%) ₀

 Production Example 5] Production of Comparative Crosslinked Resin Particles

 In a reaction vessel, 120 parts of butyl solvate was placed and stirred at 120 ° C. This is a mixture of 2 parts t-butyl peroxy 2-ethylhexanoate and 10 parts butylcetosolve and glycidinoremethalate 15 咅 ^ 2 ethinorexenoremethalate 50 咅 ^ A monomer mixture consisting of 20 parts of tilmetatalylate and 15 parts of η-butylmetatalylate was added dropwise over 3 hours. After aging for 30 minutes, a solution prepared by mixing 0.5 part of t-butylperoxy-2-ethylhexanoate and 5 parts of butylcellosolve was dropped in 30 minutes, and after aging for 2 hours, the mixture was cooled. N, N dimethylaminoethanol (7 parts) and 50% aqueous lactic acid solution (15 parts) were added thereto, and the mixture was heated and stirred at 80 ° C. Heating was stopped when the acid value became equal to or lower and the viscosity increase stopped, and an acrylic resin having an ammonium group was obtained. The number of ammonium groups per molecule of the acrylic resin having ammonium groups was 6.0.

[0167] 120 parts of an acrylic resin having an ammonium group and 270 parts of deionized water were added to a reaction vessel, and the mixture was heated and stirred at 75 ° C. 2,2′azobis (2- (2 imidazoline 2 yl) propane) 1. 5 parts of 100% neutralized aqueous solution of acetic acid was added dropwise over 5 minutes. Aging for 5 minutes Then, 30 parts of methyl metatalylate was added dropwise over 5 minutes. After aging for an additional 5 minutes, 170 parts of acrylic resin having ammonium groups and 250 parts of deionized water were mixed together. 170 parts of methinore methacrylate, styrene 40, 30 n-phenolate methacrylate, glycidyl methacrylate A pre-emulsion obtained by adding and stirring an ethylenically unsaturated monomer mixture consisting of 5 parts of talylate and 30 parts of neopentyldalycol dimetatalylate was added dropwise over 40 minutes. As a result, a dispersion of the crosslinked resin particles 1 was obtained.The dispersion of the obtained crosslinked resin particles had a non-volatile content of 35%, a pH of 5.0, and an average particle size of 0.1 μm. The average particle size was measured as follows.

 [0168] The average particle diameter of the resin particles was measured by a granular particle permeation measurement method using MICROTRAC9340UPA manufactured by Nikkiso Co., Ltd. Further, with this measuring instrument, the particle size distribution of the resin particles was measured, and the average particle diameter at the cumulative relative frequency F (x) = 0.5 was calculated from the measured value. In these measurements and calculations, the refractive index of the solvent (water) 1.33 and the refractive index of the resin component 1.59 were used.

 [0169] Production Example 6B

 A flask equipped with a reflux condenser and a stirrer was charged with 295 parts of methylisoptyl ketone (hereinafter abbreviated as “MIBK”), 37.5 parts of methinorethananolamine, and 52.5 parts of diethanolamine. Hold at 100 ° C. To this, 205 parts of cresol nopolac epoxy resin (product name: YDCN-703, manufactured by Tohto Kasei Co., Ltd.) is gradually added. The molecular weight was measured and found to be 2,100. The amine value (MEQ (B)) of the obtained amino-modified resin was measured and found to be 340 mmol / 100 g.

 [0170] 5.5 parts of formic acid and 1255.4 parts of deionized water are added to 140 parts of the above amino-modified resin solution and stirred for 30 minutes while maintaining the temperature at 80 ° C. The organic solvent was removed under reduced pressure to obtain a conductivity control agent having a solid content of 5.0%.

 [0171] Example 1B

628 parts of emulsion obtained in Production Example 2B, 127 parts of crosslinked resin particles (crosslinked resin particles mainly composed of methyl methacrylate monomer; GM-0105 (trade name) manufactured by Ganz Kasei Co., Ltd.) and 4 parts of dibutyltinoxide Then, 4581 parts of ion-exchanged water was mixed to obtain a cationic electrodeposition coating composition having PWC = 0%, resin particles 15% by weight, and solid content 5% by weight. [0172] Example 2B

628 parts of emulsion obtained in Production Example 2B, cross-linked resin particles (cross-linked resin particles mainly composed of methyl methacrylate; Tofubo Co., Ltd., Tuftic ^(SW) F-200) 127 parts and dibutyl tin oxide 4 parts and 4581 parts of ion-exchanged water were mixed to obtain a cationic electrodeposition coating composition having PWC = 0%, bridge resin particles 15% by weight, and solid content 5% by weight.

[0173] Example 3B

561 parts of the emulsion obtained in Production Example 2B and 19 parts of the pigment dispersion paste obtained in Production Example 4B, and crosslinked resin particles (crosslinked resin particles mainly composed of methyl methacrylate monomer; Toyobo Co., Ltd.) 114 parts of Toughtic ⁽ registered trademark ^ -200), 3 parts of dibutyltinoxide, 4303 parts of ion-exchanged water, PWC = 3%, crosslinked resin particles 10% by weight, solid content 5% by weight A cationic electrodeposition coating composition was obtained.

[0174] Example 4B

578 parts of the emulsion obtained in Production Example 2B and 360 parts of the conductivity control agent obtained in Production Example 6B (solid content 5%), and crosslinked resin particles (crosslinked resin particles mainly composed of methyl methacrylate monomer; Toyo Made by Spinning Co., Ltd., 127 parts Tuftic ⁽ registered trademark ^ -200), 4 parts dibutinole stanoxide, 4331 parts ion-exchanged water, PWC = 0%, cross-linked resin particles 15% by weight, solid content A 5 wt% cationic electrodeposition coating composition was obtained.

[0175] Comparative Example 1B

 2444 parts of the emulsion obtained in Production Example 2B and 250 parts of the pigment dispersion paste obtained in Production Example 4B were mixed with 2346 parts of ion-exchanged water and 10 parts of dibutyltin oxide to obtain a cation battery having a solid content of 20% by weight. A coating composition was obtained.

[0176] Comparative Example 2B

 738 parts of emulsion obtained in Production Example 2B and 4 parts of dibutyltinoxide were mixed with 4598 parts of ion-exchanged water. A weight% cationic electrodeposition coating composition was obtained.

[0177] Comparative Example 3B

702 parts of the emulsion obtained in Production Example 2B and 38 parts of the crosslinked resin particles and 4 parts of dibutyltinoxide obtained in Production Example 5B were mixed with 4596 parts of ion-exchanged water, and PWC = A cationic electrodeposition coating composition having 0%, 5% by weight of crosslinked resin particles and 5% by weight of solid content was obtained.

[0178] Comparative Example 4B

 Mixing 665 parts of the emulsion obtained in Production Example 2B and 76 parts of the crosslinked resin particles and 4 parts of dibutyltinoxide obtained in Production Example 5B, and 4596 parts of ion-exchanged water, PWC = 0%, crosslinked resin particles A cationic electrodeposition coating composition having 10% by weight and a solid content of 5% by weight was obtained.

[0179] Comparative Example 5B

579 parts of emulsion obtained in Production Example 2B, crosslinked resin particles (crosslinked resin particles mainly composed of styrene monomer; 38 parts by Chemisnow ^(ffi) SX130M, manufactured by Soken Chemical Co., Ltd.) and 4 parts of dibutyltinoxide Then, 4388 parts of ion-exchanged water were mixed to obtain a cationic electrodeposition coating composition having PWC = 0%, crosslinked resin particles 15% by weight, and solid content 5% by weight.

 [0180] With respect to the cationic electrodeposition coating composition thus obtained, the loss elastic modulus at 80 ° C and the storage elastic modulus at 140 ° C, smoothness and end face coverage, etc. in dynamic viscoelasticity were determined by the following methods. Evaluation was performed.

 [0181] Measurement of the rate of unsuccessful and unaccompanied thunderstorms

 A tin plate is dipped in the cationic electrodeposition paint obtained above, and an electrodeposition coating film is formed by coating at a coating voltage such that the film thickness after baking is Ιδΐη. The electrodeposition paint composition was removed. Next, after removing moisture, the uncured coating piece was immediately taken out without drying, and a sample was prepared. The sample obtained in this way was subjected to temperature-dependent measurement in dynamic viscoelasticity using Rheosol-G3000 (manufactured by UBM), a rotary dynamic viscoelasticity measuring device. Setting conditions: strain 0.5 deg, frequency 0 The storage elastic modulus (G ') and loss elastic modulus (G ") were measured at 02Hz and the heating rate of 2.0 ° C / min.

 [0182] Raijing 'Appearance of coated film (smooth † raw) evaluation

The appearance of the electrodeposition coating film was evaluated by measuring the arithmetic average roughness (Ra) of the roughness curve. An uncured electrodeposition coating film obtained by immersing a cold-rolled steel sheet treated with zinc phosphate in a cationic electrodeposition coating and applying a coating voltage that gives a film thickness of 15 / ^ 111 after baking. Bake for 10 minutes at ° C. Thereafter, the Ra value of the uncured electrodeposition coating film was measured using an evaluation type surface roughness measuring machine (SURFTEST SJ-201P, manufactured by Mitutoyo Corporation) in accordance with JIS-B0601. 2. Using a sample with a 5mm width cut-off (5 compartments), measure 7 times and Ra value was obtained by the average. The results are shown in Table 2 and Table 3. It can be said that the smaller the Ra value, the better the appearance of the coating film with less unevenness. Specifically, if the Ra value is less than 0.25 111, it is a pass.

 [0183] The flat appearance of Shenyang individual,)

 A cold-rolled steel sheet treated with zinc phosphate is immersed horizontally in the cationic electrodeposition paints obtained in the production examples and comparative examples, and a coating voltage is applied so that the film thickness after baking is 15 m. An uncured electrodeposition coating is obtained. After the obtained uncured electrodeposition coating film was baked at 160 ° C for 10 minutes, using the surface roughness measuring instrument, the arithmetic average of the roughness curve was used in the same manner as the above-described appearance evaluation of the electrodeposition coating film. Roughness (Ra) was measured.

 [0184] When the depositing property of the electrodeposition paint is inferior, the sedimentation component accumulates on the horizontal part during electrodeposition coating, and the horizontal appearance (smoothness) is worse than the vertical appearance (smoothness). For the evaluation of sedimentation, a pass / fail judgment was made based on the obtained horizontal appearance Ra value and vertical appearance Ra value under the following conditions.

 Sedimentation evaluation

 ○ (Pass): Horizontal Ra value Vertical Ra value = less than 0.05 m

 X (fail): Horizontal Ra value Vertical Ra value = 0.05 m or more

[0185] Measurement of heat softening humidity

 A sample obtained by adjusting the cross-linked resin particles to a solid content concentration of 30% by weight was measured by temperature dependency measurement using Rheosol-G3000 (manufactured by UBM), which is a rotary dynamic viscoelasticity measuring device. The storage elastic modulus G ′ was measured from 90 ° C under the measurement conditions of strain 0.5 deg., Frequency 0.02 Hz, and heating rate 4.0 ° C / min. The measurement results are shown in a graph as shown in FIG. 8, and the tangent of the region where the viscosity is constant and the tangent of the region where the viscosity is lowered are drawn, and the temperature at the intersection is defined as the thermal softening temperature.

[0186] Edge ffi covering

 End face coverage evaluation was performed as described above. Fig. 9 schematically shows the 30-micron area from the tip of the cutter knife. If this film thickness is 7.8 111 or more, it passes.

[0187] Method for measuring average particle size of crosslinked fat particles

The average particle diameter of the crosslinked resin particles used in the above examples and comparative examples was measured as follows. The average particle size of the crosslinked resin particles was measured by a granular particle permeation measurement method using MICROTRAC9340UPA manufactured by Nikkiso Co., Ltd. In addition, with this measuring instrument, the particle size distribution of the crosslinked resin particles was measured, and the average particle size at the cumulative relative frequency F (x) = 0.5 was calculated from the measured values. In these measurements and calculations, the solvent (water) refractive index 1.33 and the resin refractive index 1.59 were used.

[Table 2]

 Examples Examples Examples Examples Examples

 1 B 2 B 3 B 4 B

 Inorganic pigment amount (%) 0 0 3 0

 Cross-linked resin Cross-linked resin Cross-linked resin Cross-linked resin

 Particle # 3 Particle # 4 Particle # 4 Particle # 4

 Cross-linking

 Quantity (%) 15 1 5 10 15

 Oil

 德 Medium Large Large Large

 Particle

 Thermal softening temperature 120 140 140 140

 Particle size

 2. 0 2. 0 2. 0 2. 0

 Conductivity agent 〇

 Melting 80 ° C / G value 113 107 90 99

 Viscosity 140 / G 'value 125 475 222 188

 Sedimentation evaluation ○ ○ ○ ○

 Smoothness Ra (C / 0 = 2.5) 0. 21 0. 23 0. 23 0. 22

 End face coverage (/ m) 7. 8 8. 0 7. 9 7. 8

[Table 3]

[0190] 架橋度は熱軟化温度測定より、熱軟化温度別に表記した。

[0190] The degree of cross-linking was expressed by thermal softening temperature based on thermal softening temperature measurement.

 High degree of crosslinking; thermal softening temperature 140 ° C or higher

 Degree of cross-linking: thermal softening temperature of 120 ° C or more, less than 140 ° C

 Low degree of crosslinking; thermal softening temperature 120 ° C or less

[0191] Crosslinked resin particles # 1: Crosslinked resin particles obtained in Production Example 5B

 Crosslinked resin particles # 2: Chemisnow SX—130M (trade name) manufactured by Soken Chemical Co., Ltd.

 Crosslinked resin particle # 3: GM — 0105 (trade name) manufactured by Ganz Kasei

 Crosslinked resin particle # 4: Toyobo F-200 (trade name)

[0192] As is apparent from Table 2 and Table 3 above, crosslinked resin particles having an average particle size of 1.0 to 3.0 m and a thermal softening temperature of 120 to 180 ° C even with low ash differentiation and low solid differentiation As a result of blending, it was found that, as in Comparative Example 1B, which is an example of a conventional paint, excellent performance in smoothness and end face coverage was exhibited. Comparative Example 1B contains a conventional inorganic pigment that does not contain resin particles, and has good surface smoothness and end face coverage, but its ash content (Ash content) is high, so its sedimentation evaluation is poor. Comparative Example 2B does not contain inorganic pigments or resin particles, and has excellent smoothness S and end face coverage becomes very poor. Comparative Examples 3B to 5B contain resin particles, but the particle size is small (Comparative Examples 3B and 4B), the force is! /, The thermal softening temperature is small! /, (Comparative Example 5B) is there. Comparative Examples 3B to 5B showed a tendency that both the end face coverage and the surface smoothness were not good.

Claims

The scope of the claims [1] A cationic electrodeposition coating composition, wherein an uncured deposited coating obtained by electrodeposition coating of the cationic electrodeposition coating composition has a storage elastic modulus (G ′) at 140 ° C. of 80 to A cationic electrodeposition coating composition having excellent smoothness and end face coverage, which is 500 dyn / cm ² and has a loss elastic modulus (G ″) at 80 ° C. of 10 to; 150 dyn / cm ² .  [2] The cationic electrodeposition coating composition according to claim 1, wherein the cationic electrodeposition coating composition contains a cationic epoxy resin, a block isocyanate curing agent, and, if necessary, crosslinked resin particles and / or an inorganic pigment component. . [3] A method for forming a cationic electrodeposition coating film by immersing an object to be coated in a cationic electrodeposition coating composition and applying a voltage thereto. The storage elastic modulus (G ') at 140 ° C is adjusted to 80 to 500 dyn / cm ² and the loss elastic modulus (G ") at 80 ° C is adjusted to 10 to 150 dyn / cm ² To achieve both smoothness and end face coverage of the cationic electrodeposition coating.  [4] The method according to claim 3, wherein the storage elastic modulus and loss elastic modulus are adjusted by adding crosslinked resin particles having an average particle diameter of 1.0 to 3.0 am to the cationic electrodeposition coating composition.  5. The method according to claim 4, wherein the crosslinked resin particles are added in an amount of 3 to 15% by weight in the resin solid content of the cationic electrodeposition coating composition.  6. The method according to claim 3, wherein the storage elastic modulus and loss elastic modulus are adjusted by using an inorganic pigment in an amount of 10 to 20% by weight in the solid content of the force thione electrodeposition coating composition.  [7] Crosslinked resin particles having an average particle size of 1.0 to 3.0 am are added to the cationic electrodeposition coating composition, and the inorganic pigment is added to the solid content of the cationic electrodeposition coating composition from 0.5 to The method according to claim 3, wherein the storage elastic modulus and the loss elastic modulus are adjusted by blending in an amount of 10% by weight.  8. The method according to claim 7, wherein the crosslinked resin particles are added in an amount of 3 to 15% by weight in the resin solid content of the cationic electrodeposition coating composition.