JP2012001598A - Metal pigment for automobile exterior metallic coating material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a metal pigment for an automobile exterior metallic coating material, which can prevent a metallic unevenness caused in a very wide area like an automotive body.SOLUTION: The metal pigment for the automobile exterior metallic coating material contains metal particles and a coupling agent that are adsorbed to a surface thereof. The coupling agent is a titanate-based and/or aluminate-based coupling agent.

Description

  The present invention relates to metal pigments used in high-grade metallic paints such as high-grade metallic paints used for painting automobile exteriors such as automobile bodies and exterior parts, metallic paints for repairing automobile exteriors, that is, metal pigments for automotive exterior metallic paints. The present invention also relates to an automobile exterior metallic paint containing the metal pigment and an automobile body or automobile exterior part to which the paint is applied.

  Conventionally, selection of metal pigments has been important to provide a metallic design using paints containing metal pigments typified by aluminum pigments. This is due to differences in the particle size and physical shape of metal pigments. This is because the color tone is influenced by the inherent luster of the metal pigment. However, even if the paint contains the same metal pigment, the final metallic coating film depends on the dispersion state of the metal pigment in the paint or the orientation state of the metal pigment in the form of flakes. It is well known that the finished appearance of is affected.

  The appearance of the coating film using the metallic paint is due to a unique finish with a metallic feeling, but generally an appearance with a better metallic luster is preferred in design. In order to develop such a strong metallic luster, the metallic pigment is not unevenly dispersed in the paint, and in the case of a flaky metallic pigment, the parallel arrangement of layers in the coating film is important. When these states are bad, that is, when the dispersion state of the metal pigment is uneven, for example, when the coating film is observed macroscopically, metallic unevenness is visually recognized or a predetermined metallic glossiness cannot be obtained. Occurs.

  In particular, in metallic paints used for automobile exteriors (automobile exterior metallic paints), high-grade design is required, and the appearance is viewed with a large field of view, in other words, a very wide area is observed. If metallic unevenness that lacks uniformity in the finish of the coating occurs, the design value is impaired.

  As a method for improving the problem of metallic unevenness, Japanese Patent Application Laid-Open No. 2003-147270 (Patent Document 1) proposes an aluminum pigment that suppresses uneven reflection in the field of high-grade metallic paints for automobile bodies, parts, home appliances, and industrial use. Has been. Japanese Patent Application Laid-Open No. 2005-240013 (Patent Document 2) discloses a coating composition containing an aluminum pigment in which a specific amount of resin is formed on the surface of flaky aluminum powder. Furthermore, metallic paint compositions used for automotive base coats for parts and repairs have been proposed, and it is disclosed that the aluminum pigment exhibits extremely excellent orientation and gives a coating film with high glitter and small particle feeling. Has been.

  Japanese Patent Application Laid-Open No. 2003-301132 (Patent Document 3) discloses a glittering water-based colorant composition containing a glittering pigment that has been subjected to a water-repellent treatment with a specific coupling agent, and in particular as such a composition for a writing instrument. A water-based ink composition is proposed. Further, JP-A-2006-328278 (Patent Document 4) discloses an oil-based ink composition containing a luster pigment obtained by treating the surface of a glass flake with a specific coupling agent, particularly printing of gravure ink, flexo ink, and the like. Proposing inks for use.

JP 2003-147270 A JP 2005-240013 A JP 2003-301132 A JP 2006-328278 A

  As a method for improving the problem of metallic unevenness, in the proposal of Patent Document 1, it is not always possible to effectively suppress metallic unevenness of a coating film having a particularly high brightness. Moreover, in the proposal of patent document 2, since it is the method of forming resin on the surface of aluminum powder, the coating film reflecting the reflectance of the original aluminum powder cannot be obtained.

  Furthermore, Patent Document 3 relates to ink for writing instruments, and has a problem of coexistence of color developability with a colorant and glitter with a luster pigment for an area in a very narrow range compared to a car body called handwriting. It is not intended to prevent metallic unevenness of a very wide area such as an automobile body, and does not suggest any solution. Patent Document 4 relates to a printing ink, and it is an object to develop a printing ink that can be easily re-dispersed in a solvent even when a glittering pigment settles in the ink. Similar to No. 3, it is not intended to prevent metallic unevenness of a very wide area like an automobile body, and does not suggest any solution.

  The present invention has been made in view of such a situation, and an object of the present invention is for an automotive exterior metallic paint capable of preventing metallic unevenness occurring in a very wide area portion such as an automobile body. It is to provide a metal pigment.

  The present inventor has made extensive studies to solve the above problems, and obtained the knowledge that it is effective to treat the surface of the metal particles. It was found that it is most effective to use a specific coupling agent among various agents for treating the surface. The present invention has been completed based on this finding.

  That is, the metal pigment for an automotive exterior metallic paint of the present invention includes metal particles and a coupling agent adsorbed on the surface thereof, and the coupling agent includes a titanate coupling agent and / or an aluminate coupling agent. It is characterized by being.

  Here, the composition ratio of the metal particles to the coupling agent is preferably 0.01 to 10 parts by mass of the coupling agent with respect to 100 parts by mass of the metal particles. The metal particles preferably have an aliphatic amine adsorbed on the surface thereof, and are preferably aluminum particles.

  The titanate coupling agent preferably contains a hydrocarbon group having 8 or more carbon atoms, and the aluminate coupling agent is a compound represented by the following formula (wherein R is a compound having 8 or more carbon atoms). It is preferably a hydrocarbon group.

  Furthermore, the titanate coupling agent is preferably isopropyl triisostearoyl titanate, and the aluminate coupling agent is preferably a compound represented by the following formula.

  The present invention also provides a method for producing a metal pigment for an automotive exterior metallic paint, wherein the metal particles and the coupling agent are kneaded in a mixed state, or the metal particles are dispersed in an organic solvent. It is related with the manufacturing method including the process stirred while adding the said coupling agent to the made dispersion liquid.

  The present invention also relates to an automobile exterior metallic paint comprising the metal pigment for an automobile exterior metallic paint, and also relates to an automobile body or an automobile exterior part coated with the automobile exterior metallic paint.

  The metal pigment for an automotive exterior metallic paint of the present invention has an excellent effect that metallic unevenness that occurs in a very wide area portion such as an automobile body can be prevented by having the above-described configuration.

  Hereinafter, the metal pigment for automobile exterior metallic paint of the present invention will be described in more detail.

<Metal pigments for automotive exterior metallic paints>
The metal pigment for automobile exterior metallic paint of the present invention contains metal particles and a coupling agent adsorbed on the surface thereof, and the coupling agent is a titanate coupling agent and / or an aluminate coupling agent. It is characterized by that.

  Here, the automobile referred to in the present invention is a concept including a wide range of vehicles such as passenger cars, wagons, trucks, buses, motorcycles, railway vehicles, airplanes, and the like.

<Metal particles>
As the metal particles used in the present invention, any conventionally known metal particles can be used and are not particularly limited. For example, examples of the metal species constituting the metal particles include aluminum, zinc, copper, bronze, nickel, titanium, stainless steel, and alloys of these metals. Among these metal particles, aluminum particles are particularly suitable because they are excellent in metallic luster, are inexpensive and easy to handle because of their low specific gravity. Hereinafter, the case where aluminum particles are used as the metal particles will be described in detail.

  First, the shape of such aluminum particles is not particularly limited. For example, various shapes such as a granular shape, a plate shape, a lump shape, and a flake shape (scale shape) can be adopted. In order to give a feeling, a flake shape is preferable. Moreover, the average particle diameter of the aluminum particles is usually preferably about 1 to 100 μm, more preferably 3 to 60 μm. When the average particle size of the aluminum particles is less than 1 μm, handling in the production process tends to be difficult and the particles tend to aggregate. When the average particle size exceeds 100 μm, the coating film is used when used as a paint. In some cases, the surface is rough and a desirable design cannot be realized.

  Moreover, when the shape of such an aluminum particle is flake shape, the average thickness is not particularly limited, but is preferably 0.005 μm or more, and more preferably 0.02 μm or more. preferable. The average thickness is preferably 5 μm or less, more preferably 3 μm or less. When the average thickness is less than 0.005 μm, it is difficult to handle in the manufacturing process and tends to aggregate, and when the average thickness exceeds 5 μm, the particle feeling (unevenness) of the coating film is conspicuous. In some cases, the hiding power is insufficient and a preferable design cannot be realized.

  The average particle size of the aluminum particles as described above can be obtained by calculating a volume average from a particle size distribution measured by a known particle size distribution measurement method such as a laser diffraction method. The average thickness can be calculated from the hiding power and density of the aluminum particles.

  In the present invention, as the aluminum particles, those having a flake shape as described above can be used. For example, such a flake-shaped aluminum particle is obtained by polishing an aluminum powder as a raw material with a ball mill or the like. It can be obtained by crushing.

  The grinding aid added at the time of grinding may be adsorbed on the surface of the aluminum particles thus obtained. Examples of the grinding aid include fatty amines such as oleic acid and stearic acid, aliphatic amines, aliphatic amides, aliphatic alcohols, ester compounds, and the like. These have the effect of suppressing unnecessary oxidation on the surface of the aluminum particles and improving the gloss. The adsorption amount of the grinding aid is preferably 0.001 to 2 parts by mass with respect to 100 parts by mass of the aluminum particles. When the amount is 2 parts by mass or less, it is advantageous in that the surface gloss is hardly lowered and a coating with a titanate coupling agent and / or an aluminate coupling agent is easily attached. On the other hand, if it is less than 0.001 part by mass, the above effects cannot be expected.

  In addition, when an aliphatic amine is used as a grinding aid, a suitable effect that the titanate coupling agent and / or the aluminate coupling agent is easily adsorbed on the aluminum particle surface is shown. In this case, the aliphatic amine exists in a state of being adsorbed on the surface of the aluminum particles, but the titanate coupling agent and / or the aluminate coupling agent may be adsorbed on the aliphatic amine, It may be substituted with an aliphatic amine and directly adsorbed on the surface of the aluminum particles. Even when the titanate coupling agent and / or the aluminate coupling agent is adsorbed on the aliphatic amine, the expression that these coupling agents are adsorbed on the surface of the metal particles is used in the present invention. Shall be adopted. Moreover, although aluminum particle | grains are illustrated above, aliphatic amine shows the same outstanding effect also in metal particles other than aluminum particle. Accordingly, a preferred embodiment of the metal pigment of the present invention includes an embodiment in which an aliphatic amine is adsorbed on the surface of the metal particles.

  As such an aliphatic amine, any of primary amine, secondary amine, and tertiary amine may be used, and one or two or more may be used. Specific examples of the aliphatic amine include, for example, octylamine, laurylamine, myristylamine, stearylamine, oleylamine, N-methyldioctylamine, N-methyldilaurylamine, N-methylditridecylamine, N-methyldistearylamine N-methyldioleylamine, N, N-dimethyllaurylamine, N, N-dimethylmyristylamine, N, N-dimethylpalmitylamine, N, N-dimethylbehenylamine, N, N-dimethylstearylamine, N, Examples thereof include N-dimethyloleylamine.

<Coupling agent>
The coupling agent of the present invention is adsorbed on the surface of metal particles (or on an aliphatic amine) and is a titanate coupling agent and / or aluminate coupling agent. Here, the titanate coupling agent is a coupling agent generally known to have an action of chemically binding an organic material and an inorganic material, and includes titanium as a constituent element. The aluminate coupling agent is a similar coupling agent and contains aluminum as a constituent element.

  As described above, the metal pigment for an automotive exterior metallic paint according to the present invention is characterized in that a specific coupling agent is adsorbed on the surface of the metal particles, and thereby, in a very wide area such as an automobile body. The excellent effect that the metallic unevenness which arises can be prevented is shown. Such a coupling agent has been known to be applied to the surface of metal particles in writing instrument inks and printing inks as in the prior art described above. The effect of preventing the metallic unevenness of the area has been revealed for the first time by the inventor's research, and is an effect that has never been known in the past. Although the detailed mechanism of why such a coupling agent exhibits such an excellent effect has not yet been elucidated, the metal particles are probably coated by the adsorption of the coupling agent on the surface of the metal particles. In the coating film, the metal particles can be arranged more evenly, thereby preventing metallic unevenness in a very wide area such as an automobile body. It is considered a thing.

  In addition, for example, alterations such as oxides of grinding aids used in the grinding process as described above exist on the surface of the metal particles, and the alterations inhibit uniform dispersion of the metal particles in the paint. It is thought that there is an effect. It is considered that the coupling agent of the present invention has an action of substituting such a modified substance and adsorbing it on the surface of the metal particle, and a function of covering such a modified substance and existing on the metal particle. Thus, it is considered that the excellent effect as described above is exhibited.

Here, in the present invention, the fact that the coupling agent is adsorbed on the surface of the metal particles includes the case where it is adsorbed so as to be in contact with the surface of the metal particles, as well as the aliphatic amine present on the surface of the metal particles, the above-mentioned altered substance, etc. It also includes the case of adsorbing on (or covering with other substances) other substances. In the present invention, the fact that the coupling agent is adsorbed on the surface of the metal particles means that, for example, the metal particles before and after the coupling agent is adsorbed on the metal particles are pulverized, and the powdered metal This can be confirmed by compressing the particles at a high pressure using a cylindrical tablet molding machine to make a disk-shaped tablet sample with a smooth surface and measuring the contact angle with water on the sample surface. That is, the contact angle between the metal particles adsorbing the coupling agent and the water on the sample surface is larger than the contact angle between the metal particles not adsorbing the coupling agent and the sample surface. I can guess that. The preparation of such a sample is not particularly limited. For example, “hand press SSP-10A” (trade name) manufactured by Shimadzu GL Corp. was used as a cylindrical tablet molding machine, and the sample was pulverized. By filling 0.3 g of metal particles and pressing at a pressure of 600 N / cm ² , a coin-shaped sample having a diameter of 13 mm and a thickness of 1 mm can be produced. And using this coin-shaped sample, a contact angle with water can be calculated | required with a contact angle meter (Brand name: "Solid-liquid interface analyzer DM-300", the Kyowa Interface Science company make).

  When the specific example of the coupling agent used by this invention is shown, first, as a titanate coupling agent, a conventionally well-known thing can be widely used and what has a hydrocarbon group like an alkyl titanate can be illustrated. More specifically, isopropyl triisostearoyl titanate, isopropyl tri (dioctyl pyrophosphate) titanate, tetraoctyl bis (ditridecyl phosphite) titanate, isopropyl tri-n-dodecylbenzenesulfonyl titanate, bis (dioctyl pyrophosphate) oxyacetate Examples thereof include titanate and tetraisopropylbis (dioctyl phosphite) titanate.

  In particular, the hydrocarbon group contained as a hydrophobic group of the titanate coupling agent preferably has 8 or more carbon atoms (C), and more preferably has 18 or more carbon atoms (C).

  Among the commercially available products, the “Preneact KR 41B” (trade name) manufactured by Ajinomoto Fine Techno Co., Ltd., which has 8 carbon atoms (C), and the hydrocarbon group has 18 carbon atoms (C). An example is “Plenact KR TTS” (trade name) manufactured by Ajinomoto Fine Techno Co., Ltd.

  Further, when isopropyl triisostearoyl titanate is used as a titanate coupling agent, the effect of suppressing metallic unevenness is particularly high, and can be cited as a suitable example. Why is isopropyl triisostearoyl titanate particularly effective in suppressing metallic unevenness? It is presumed that the surface of the metal particles adsorbed by the coupling agent is strongly hydrophobic because of its long length.

  On the other hand, as the aluminate coupling agent, conventionally known ones can be widely used and are not particularly limited. For example, it is preferable to use a compound having a structure represented by the following formula.

  In the formula, R represents a saturated or unsaturated hydrocarbon group. Alkyl acetoacetate aluminum diisopropylate as represented by the above formula can be mentioned as a particularly suitable example.

  Further, the hydrocarbon group represented by R in the above formula preferably has 8 or more carbon atoms (C), and more preferably 18 or more carbon atoms (C). The use of alkyl acetoacetate aluminum diisopropylate having 18 or more carbon atoms (C) is preferable in that the effect of suppressing metallic unevenness is particularly high.

  Examples of commercially available products include “Plenact AL-M” (trade name) manufactured by Ajinomoto Fine Techno Co., Ltd. having the following structural formula in which the hydrocarbon group of R is carbon number (C) 18. Can do.

  The reason why the alkyl acetoacetate aluminum diisopropylate whose hydrocarbon group of R is carbon number (C) 18 is particularly excellent in the effect of suppressing metallic unevenness is not clear, but the alkyl acetoacetate aluminum diisopropylate is not clear. It is presumed that the hydrophobicity of the surface of the metal particles adsorbed by the coupling agent is increased because the hydrocarbon chain contained on the hydrophobic group side of the rate is long.

  However, it does not deny the use of those having a small carbon number such as ethyl acetoacetate aluminum diisopropylate in which the hydrocarbon group of R is carbon number (C) 2, for example, and these also exhibit the effect of the present invention. it can.

  In the present invention, the composition ratio of the metal particles to the coupling agent is preferably 0.01 to 10 parts by mass of the coupling agent with respect to 100 parts by mass of the metal particles. Although it depends on the specific surface area of the metal particles, the coupling agent is more preferably 0.1 to 5 parts by mass with respect to 100 parts by mass of the metal particles.

  When the composition ratio of the coupling agent is less than 0.01 parts by mass, the effect of improving the arrangement of the metal particles in the coating film is hardly exhibited, and even when the amount exceeds 10 parts by mass, the effect is particularly improved. In some cases, the adhesion of the coating film may be impaired.

  In the present invention, “titanate coupling agent and / or aluminate coupling agent” may be used either of these coupling agents or in combination of both. The various coupling agent compounds contained in each coupling agent can be used alone or in combination of two or more. When using 2 or more types of coupling agent compounds, it is preferable that those total amount is contained in the said range.

<Method for producing metal pigment for metallic paint for automobile exterior>
The metallic pigment for metallic coatings for automobile exteriors of the present invention is produced by adsorbing the titanate coupling agent and / or aluminate coupling agent on the surface of metal particles. The specific method is not particularly limited. For example, when aluminum particles are used as the metal particles, as a grinding aid in the process of grinding the raw aluminum powder into flaky aluminum particles using a ball mill or the like. By using the above coupling agent, the titanate coupling agent and / or the aluminate coupling agent can be adsorbed on the surface of the aluminum particles by kneading the aluminum particles and the coupling agent in a mixed state. .

  Alternatively, after processing the raw aluminum powder into flaky aluminum particles, the aluminum particles and an organic solvent are blended into a paste, and a titanate coupling agent and / or an aluminate coupling agent is added to the paste. The titanate coupling agent and / or the aluminate coupling agent can be adsorbed on the surface of the aluminum particles by kneading the aluminum particles and the coupling agent in a mixed state.

  Furthermore, by adding a titanate coupling agent and / or an aluminate coupling agent to a dispersion obtained by dispersing aluminum particles in an organic solvent, the titanate coupling agent and / or the aluminum particle surface is stirred. An aluminate coupling agent can also be adsorbed.

  The temperature range in which the titanate coupling agent and / or the aluminate coupling agent is adsorbed on the surface of the aluminum particles is not particularly limited, but it is preferably 10 ° C to 150 ° C, more preferably 40 ° C to 100 ° C. It is. When this temperature is less than 10 ° C., the rate at which the coupling agent is adsorbed on the surface of the aluminum particles may be slow. On the other hand, even if this temperature exceeds 150 ° C., the effect is not particularly improved. Therefore, it is preferable to carry out at a temperature of 150 ° C. or less at which good process control can be performed.

  Further, the time of the treatment step for adsorbing the coupling agent on the surface of the aluminum particles is not particularly limited, but it is preferably within the range of 30 minutes to 8 hours, more preferably 1 although it depends on the temperature conditions at the time of adsorption. Time to 5 hours. Even if the time exceeds 8 hours, there is not much difference in the amount of adsorption, and it is advantageous in terms of productivity to carry out within 8 hours. On the other hand, if the time is less than 30 minutes, the coupling agent may not be sufficiently adsorbed. In order to stabilize the adsorption, aging may be performed for a long time (for example, about one week) at a constant temperature (for example, 50 ° C.) after the step of adsorbing the coupling agent.

  Further, the aluminum particles used in the above may be subjected to a treatment for suppressing the generation of hydrogen gas due to the reaction with water so that the aluminum particles can be used for water-based paints. A method for suppressing the generation of such hydrogen gas is not particularly limited, and a conventionally known method can be adopted. For example, a method of coating the surface of aluminum particles with a coating of organophosphoric acid or a molybdic acid coating. Can be adopted.

  Moreover, if it is a range which does not prevent the effect of this invention, it can also have the resin film formed by the polymerization reaction in order to provide chemical-resistance to the aluminum particle surface. In this case, it is considered that the coupling agent is adsorbed on the resin film, but even in such a case, the coupling agent is included in the expression of adsorbing on the surface of the metal particle.

  In general, the surface of aluminum particles obtained by grinding using the above-mentioned ball mill contains alterations derived from the grinding step (for example, a compound in which the grinding aid is oxidized). In particular, an altered product having a polar group may adversely affect the dispersion stability of aluminum particles. However, the titanate coupling agent and / or aluminate coupling agent according to the present invention is adsorbed on the surface of the aluminum particle by replacing such a modified material, or adsorbed on the modified material existing on the surface of the aluminum particle. Or to coat the altered product thereof, the dispersion stability of the aluminum particles is improved. In this way, since the aluminum particles are very uniformly dispersed in the paint, the alignment is improved even in the coating film, so that the metallic material generated in a very wide area portion such as an automobile body. It is considered that an excellent effect that unevenness can be prevented is shown.

  In the above, the case where aluminum particles are used as the metal particles has been exemplified. However, the above manufacturing method can be widely applied to metal particles other than aluminum particles. That is, in the method for producing a metallic pigment for an automotive exterior metallic paint according to the present invention, the step of adsorbing the coupling agent on the surface of the metal particles is a step of kneading the metal particles and the coupling agent in a mixed state, or The method includes a step of stirring while adding a coupling agent to a dispersion liquid dispersed in an organic solvent.

<Automotive metallic paint>
The present invention also relates to an automobile exterior metallic paint comprising the metal pigment for automobile exterior metallic paint. Such an automobile exterior metallic paint is a metallic paint used for the exterior of an automobile, and also includes a repair paint.

  In the automotive exterior metallic paint of the present invention, the amount of the metal pigment to be blended is preferably 0.1 to 50 parts by mass, more preferably 1 to 30 parts by mass, per 100 parts by mass of the resin component (solid content). . If the amount of the metal pigment is less than 0.1 parts by mass, the desired design property cannot be obtained, and if it exceeds 50 parts by mass, the sharpness of the coating film may be deteriorated. In addition, if it is in said range, the metal pigment of this invention can also be used in combination of 2 or more types.

  Conventionally known resin components can be used in the automotive exterior metallic paint of the present invention, and are not particularly limited. For example, thermosetting acrylic resin / melamine resin, thermosetting acrylic resin / CAB (Cellulose Acetate Butyrate) / Melamine resin, thermosetting polyester (alkyd) resin / melamine resin, thermosetting polyester (alkyd) / CAB / melamine resin, isocyanate curable urethane resin / room temperature curable acrylic resin, water diluted acrylic emulsion / melamine resin, etc. And can be used alone or in combination of two or more. If necessary, additives such as pigment dispersants, antifoaming agents, anti-settling agents, curing catalysts, other colored pigments, mica, colored mica, different colored aluminum pigments, etc. do not interfere with the effects of the present invention. It can mix | blend in the quantity of the range, for example, about 0.1-5 mass%.

<Automobile body / Automobile exterior parts>
The present invention also relates to an automobile body or an automobile exterior part to which the automobile exterior metallic paint is applied (painted). Here, examples of the automobile exterior component include a bumper, various spoilers, and an antenna.

  The automobile body and automobile exterior parts of the present invention are those in which metallic unevenness is prevented by applying the automotive exterior metallic paint containing the metal pigment for automotive exterior metallic paints of the present invention.

  In addition, a conventionally well-known method can be employ | adopted as the method of apply | coating or painting a vehicle body or a vehicle exterior component using a vehicle exterior metallic paint, and it is not specifically limited. Examples of such a coating method include air spray coating, electrostatic air spray coating, bell-type electrostatic spray coating, and the like.

  As described above, the present invention applies or paints the automobile exterior metallic paint containing the metal pigment for automobile exterior metallic paint of the present invention to the automobile body or the automobile exterior part, thereby causing metallic unevenness on the automobile body or the automobile exterior part. The present invention provides a method for preventing the occurrence. In other words, a step of producing a metal pigment by treating metal particles with a titanate coupling agent and / or an aluminate coupling agent, a step of preparing a metallic paint using the metal pigment, and the metallic paint The present invention provides a method for preventing metallic unevenness including a step of applying or painting an automobile body or an automobile exterior part.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to these. In the examples and comparative examples of the present invention, aluminum particles are used as the metal particles, but similar results can be obtained even when metal particles other than aluminum particles are used. In the following, “%” represents mass% unless otherwise specified.

<Preparation of water-based paint>
<Preparation of rheology control agent (Composition 1)>
15.0 parts by mass of a polyamide rheology control agent (manufactured by Enomoto Kasei Co., Ltd., trade name “DISPARON AQ600”), 5.0 parts by mass of butyl cellosolve, and 80.0 parts by mass of ion-exchanged water are stirred and mixed for 1 hour. Thus, a rheology control agent (Composition 1) was prepared.

<Preparation of resin solution (Composition 2)>
40.6 parts by weight of acrylic copolymer (Neuplex, trade name “Setaqua 6802”), 24.5 parts by weight of polyurethane dispersion A (Bayer Material Science, trade name “Bayhydrol XP2621”), 6.0 parts by weight Polyurethane dispersion B (trade name “Bayhydrol PT241” manufactured by Bayer Material Science), 2.8 parts by mass of melamine resin solution (trade name “Cymel327” manufactured by Mitsui Cytec Co., Ltd.), 7.7 parts by mass of butyl cellosolve, 0 4 parts by mass of an antifoam leveling agent (manufactured by Enomoto Kasei Co., Ltd., trade name “AQ7120”) and 18.0 parts by mass of ion-exchanged water were mixed and stirred for 30 minutes to form a resin solution (Composition 2 ) Was prepared.

<Preparation of metallic base (Composition 3)>
To an aluminum paste containing a metal pigment (aluminum pigment) produced in each of the examples and comparative examples described below in which the nonvolatile content is 10 parts by mass, a dispersant (trade name “AQ320” manufactured by Enomoto Kasei Co., Ltd.) Metallic base (Composition 3) was prepared by adding 0 parts by mass and butyl cellosolve to 30.00 parts by mass with stirring for 10 minutes.

<Preparation of automotive exterior metallic paint>
25.6 parts by mass of the metallic base (composition 3) is added to 200.0 parts by mass of the resin solution (composition 2) and mixed with stirring for 10 minutes. Next, after gradually adding 25.0 parts by mass of the rheology control agent (Composition 1), the mixture is further stirred for 10 minutes. Thereafter, a 10% dimethylethanolamine aqueous solution is added so that the pH of the mixture becomes 8.3 ± 0.1, and the mixture is further stirred and mixed for 10 minutes. Finally, the viscosity becomes a reference value (Brookfield viscometer (Toki Sangyo Co., Ltd., trade name “TV-10M”) using an M3 spindle and a measured value at 60 rpm is 500 to 600 mPa · sec). Thus, an appropriate amount of ion-exchanged water was added, and the mixture was stirred and mixed for 10 minutes or more to prepare an automotive exterior metallic paint.

<Preparation of clear coat paint>
51.2 parts by mass of polyacrylate (manufactured by Bayer Material Science, trade name “Desmophen A870BA”), 0.5 parts by weight of additive A (manufactured by Borchers, trade name “Baysilone Paint Additive OL17” in 10% xylene) 0.5 parts by weight of additive B (Monsanto, 1% xylene solution of “Modaflow”), 5.3 parts by weight of additive C (Ciba Spezialitatenchemie Lampertheim, 10% xylene of trade name “Tinuvin292”) Solution) 10.7 parts by mass of additive D (manufactured by Ciba Spezialitatenchemie Lampertheim, 10% xylene solution of trade name “Tinuvin 1130”), 10.0 parts by mass of diluent A (1-methoxypropyl acetate: solvent naphtha = 1: 1), and 2.2 parts by mass of diluent B (butyl glycol acetate) are stirred and mixed for 30 minutes. Then, isocyanurate (manufactured by Sumika Bayer Urethane Co., Ltd., trade name “Sumijour N3300”) and mixed solvent (butyl acetate: solvent naphtha = 1: 1) diluted to 9: 1 in the mixture By adding 5 parts by mass and mixing and stirring for 30 minutes, a clear coat paint was prepared.

<Coating conditions>
Air spray gun Weider W-101 (Anest Iwata Co., Ltd.) for 0.3 × 200 × 300mm tin plate (product name “P-32 board” manufactured by Nippon Route Service Co., Ltd.) with intermediate coating Each of the above-mentioned paints was applied using an automatic coating device for test panel equipped with a recicoater (Kansai Paint Co., Ltd.).

The painting conditions are as follows: indoor temperature 22 ± 1 ° C, indoor relative humidity 50 ± 5% RH
Reciprocator speed: 19m / min Conveyor moving speed: 0.9m / min Spraying distance: 18cm
Atomization pressure: 0.4 MPa
After coating with a metallic paint for automobile exterior so that the dry film thickness becomes 19 ± 1 μm, flash off at 80 ° C. for 5 minutes, and then the clear coat paint has a dry film thickness of 30 ± 3 μm. The coating was performed as follows. The baking conditions were 130 ° C. for 30 minutes.

<Measurement of color tone and metallic unevenness>
With a metallic unevenness measuring apparatus (manufactured by Toyo Aluminum Co., Ltd.) capable of measuring a coated plate coated under the above-mentioned coating conditions by the method disclosed in JP2009-069138A, highlight brightness L value and metallic unevenness V _A value was measured. The measurement was carried out under the following conditions for the central region of the coated plate.

Measurement conditions:
(Optical geometric conditions and measured values)
L ^* (CIELAB 1976 brightness) was measured at an incident angle of −45 degrees and a light receiving angle of 40 degrees, with the normal of the painted plate being 0 degrees.

(Measurement interval and colorimetry)
On the coordinates of the coated plate of vertical x horizontal = 200 mm x 300 mm, four rows are measured at 35 mm intervals in the vertical axis direction, and seven rows are measured at 35 mm intervals in the horizontal axis direction (points where the vertical axis and horizontal axis intersect). Was selected. Then, at each measurement location, color measurement was performed by setting six directions with a plane including the incident optical axis, the normal line, and the light receiving optical axis as measurement surfaces. Note that the measurement planes in six directions were set to have a normal line at each measurement location and intersect each other at 60 °.

(L value)
4 rows × 7 columns × 6 directions = 168 L ^* were averaged, and the average value showed the glitter of the coating film. The higher the average value, the better the glitter.

(V _A value)
The size of metallic unevenness obtained by measurement in 4 rows x 7 columns x 6 directions is shown, and the larger the value, the larger the unevenness.

(S / N ratio)
The SN ratio obtained by dividing the L value by the square root of the _VA value was calculated as the orientation characteristic quality of the aluminum pigment. This SN ratio is determined by dividing the L value indicating the glitter of the coating film by the metallic unevenness index to determine the value of the L value. The smaller the metallic unevenness element, which is the denominator, that is, the smaller the metallic unevenness, and the higher the numerator L value, the more excellent the glittering feeling of the coating film compared to the metallic unevenness. That is, the larger the SN ratio, the better the orientation characteristic quality of the aluminum pigment, and the better the glittering feeling of the metallic coating film.

<Examples 1-6 and Comparative Examples 1-2>
<Example 1>
In a cylindrical ball mill with a diameter of 500 mm and a length of 180 mm, 40 kg of steel balls with a diameter of 1.2 mm as grinding media, 1000 g of raw aluminum powder with an average particle size of 7.3 μm, and 5 mineral spirits as an organic solvent. Liter and 80g of laurylamine as a grinding aid, respectively, and ground for 8 hours at a rotational speed of 40 rpm (2/3 of the critical rotational speed), thereby adsorbing laurylamine, an aliphatic amine, on the surface Particles (aluminum particles) were obtained.

  After completion of the grinding process, the slurry containing aluminum particles in the ball mill was washed out with mineral spirit, and sequentially passed through 150, 350, and 400 mesh vibrating screens, and the passed slurry was solid-liquid separated with a pan filter. Thereafter, 1000 g (nonvolatile content, that is, aluminum content of 85%) of the obtained filter cake containing aluminum particles was transferred into a kneader mixer, and an aluminate coupling agent (manufactured by Ajinomoto Fine Techno Co., Ltd., trade name “Plenact AL”) -M ", alkyl acetoacetate aluminum diisopropylate, active ingredient 99% or more) 17.00 g is dissolved in 30 g of mineral spirits and added with aluminum particles and a coupling agent at 10 ° C to 20 ° C in a mixer with a temperature adjusting jacket. Was kneaded for 10 minutes in a mixed state. Thereby, 2.0 mass parts of the coupling agent is added to 100 mass parts of the aluminum particles.

  Thereafter, the mixer was heated for 30 minutes through warm water through a temperature adjustment jacket, and the actual temperature of the contents was adjusted to a range of 80 to 85 ° C. Thereafter, kneading was continued for 1 hour and 30 minutes. Next, cooling water is passed through the temperature adjustment jacket to cool the kneaded product to 20 ° C. or less over 30 minutes, and mineral spirits are added to supplement the amount of the mixed solvent volatilized by heating, and the non-volatile content becomes 75%. Adjusted as follows. Thereafter, the contents were taken out of the mixer and filled into a storage metal container. Furthermore, the aluminumate coupling agent which is the metal pigment for automobile exterior metallic paints of the present invention includes an aluminum pigment adsorbed on the surface of aluminum particles by heating this in a temperature-controlled room adjusted in advance to 50 ° C. for 150 hours. An aluminum paste was obtained.

The average particle size (D ₅₀₎ of the obtained aluminum pigment was 22.5. The average particle size was measured by a particle size distribution meter (device name: Microtrac particle size distribution meter HRA, model number: 9320-X100, company name: Nikkiso Co., Ltd.). The same applies to Examples 2 to 6 and Comparative Examples 1 and 2 below.

<Example 2>
Except for the amount of aluminate coupling agent used in Example 1 being 8.50 g, an aluminum paste containing an aluminum pigment, which is a metallic pigment for automotive exterior metallic paints of the present invention, was used in the same manner as Example 1. Obtained. The average particle diameter (D ₅₀ ) of the obtained aluminum pigment was 22.5 μm.

<Example 3>
Except that the amount of the aluminate coupling agent used in Example 1 was 0.85 g, an aluminum paste containing an aluminum pigment, which is a metal pigment for automotive exterior metallic paints of the present invention, was used in the same manner as in Example 1. Obtained. The average particle diameter (D ₅₀ ) of the obtained aluminum pigment was 22.5 μm.

<Example 4>
In place of the aluminate coupling agent used in Example 1, a titanate coupling agent (manufactured by Ajinomoto Fine Techno Co., Ltd., trade name “Plenact KR TTS”, isopropyl triisostearoyl titanate, active ingredient 80% or more) Except for using 17.00 g, everything else was carried out similarly to Example 1, and obtained the aluminum paste containing the aluminum pigment which is a metal pigment for the automotive exterior metallic paints of this invention. The average particle diameter (D ₅₀ ) of the obtained aluminum pigment was 22.5 μm.

<Example 5>
In place of the aluminate coupling agent used in Example 1, titanate coupling agent (manufactured by Ajinomoto Fine Techno Co., Ltd., trade name “Plenact KR 41B”, tetraisopropylbis (dioctylphosphite) titanate, active ingredient 80 Except that 17.00 g was used, an aluminum paste containing an aluminum pigment that was a metal pigment for automobile exterior metallic paint of the present invention was obtained in the same manner as in Example 1. The average particle diameter (D ₅₀ ) of the obtained aluminum pigment was 22.5 μm.

<Example 6>
The metal for automotive exterior metallic paints of the present invention is the same as in Example 1 except that 80 g of oleic acid is used in place of laurylamine used in Example 1 as a grinding aid and the grinding time is 10 hours. An aluminum paste containing an aluminum pigment as a pigment was obtained. The average particle diameter (D ₅₀ ) of the obtained aluminum pigment was 22.7 μm.

<Comparative Example 1>
In Example 1, except that an aluminate coupling agent is not added, everything else is the same as Example 1, and an aluminum paste containing an aluminum pigment in which the coupling agent is not adsorbed on the surface of the aluminum particles is obtained. It was. The average particle diameter (D ₅₀ ) of the obtained aluminum pigment was 22.5 μm.

<Comparative example 2>
In Example 6, except that no aluminate coupling agent was added, everything else was the same as in Example 6, and an aluminum paste containing an aluminum pigment in which the coupling agent was not adsorbed on the surface of the aluminum particles was obtained. It was. The average particle diameter (D ₅₀ ) of the obtained aluminum pigment was 22.7 μm.

<Evaluation>
Using the aluminum paste containing the aluminum pigment of each example and each comparative example, an automotive exterior metallic paint was produced under the conditions as described above, and the automotive exterior metallic paint and clear coat paint were similarly applied under the same conditions as described above. A painted plate was prepared by painting.

And about each coating board, L value, _VA value, and SN ratio were calculated | required and evaluated by said method. The results are shown in Table 1.

As is clear from Table 1, the _VA values of Examples 1 to 6 are all less than 2.0, and are smaller than the _VA values of Comparative Examples 1 and 2, and metallic unevenness is prevented. It could be confirmed. Moreover, also in S / N ratio, all Examples 1-6 showed a bigger value than Comparative Examples 1-2, and it has confirmed that the orientation characteristic quality of an aluminum pigment was favorable and was excellent in the brightness.

  Therefore, the metallic pigment for automotive exterior metallic paints of the present invention has excellent effects of being excellent in glitter and capable of preventing metallic unevenness that occurs in a very wide area such as an automobile body. It is clear.

  Although the embodiments and examples of the present invention have been described as described above, it is also planned from the beginning to appropriately combine the configurations of the above-described embodiments and examples.

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

Claims (11)

Including metal particles and a coupling agent adsorbed on the surface thereof,
The coupling agent is a metal pigment for automobile exterior metallic paint, which is a titanate coupling agent and / or an aluminate coupling agent.   The metal for automobile exterior metallic paint according to claim 1, wherein the composition ratio of the metal particles to the coupling agent is 0.01 to 10 parts by mass of the coupling agent with respect to 100 parts by mass of the metal particles. Pigments.   The metal pigment for an automotive exterior metallic paint according to claim 1 or 2, wherein an aliphatic amine is adsorbed on the surface of the metal particles.   The metal pigment for automotive exterior metallic paint according to any one of claims 1 to 3, wherein the metal particles are aluminum particles.   The metal pigment for automotive exterior metallic paint according to any one of claims 1 to 4, wherein the titanate coupling agent includes a hydrocarbon group having 8 or more carbon atoms. The metal pigment for automotive exterior metallic paint according to any one of claims 1 to 5, wherein the aluminate coupling agent is represented by the following formula (wherein R represents a hydrocarbon group having 8 or more carbon atoms). .

  The metal pigment for automotive exterior metallic paint according to any one of claims 1 to 6, wherein the titanate coupling agent is isopropyl triisostearoyl titanate. The metal pigment for automotive exterior metallic paint according to any one of claims 1 to 7, wherein the aluminate coupling agent is represented by the following formula.

A method for producing a metal pigment for an automotive exterior metallic paint according to any one of claims 1 to 8,
A vehicle exterior metallic including a step of kneading the metal particles and the coupling agent in a mixed state, or a step of stirring while adding the coupling agent to a dispersion in which the metal particles are dispersed in an organic solvent. A method for producing a metal pigment for paint.   An automobile exterior metallic paint comprising the metal pigment for an automobile exterior metallic paint according to any one of claims 1 to 8.   An automobile body or an automobile exterior part to which the automobile exterior metallic paint according to claim 10 is applied.