JP5185522B2 - Pearl luster pigment, method for producing the same, coating composition and coating composition - Google Patents

Description

  The present invention relates to a pearlescent pigment obtained by coating the surface of a specific flaky substrate (hereinafter sometimes simply referred to as “substrate”) with a metal oxide, a production method thereof, and use thereof.

As pearlescent pigments, those obtained by coating the surface of a substrate such as mica flakes with a metal oxide having a large refractive index such as titanium dioxide are known. In recent years, a pearlescent pigment (Patent Document 1) has been proposed in which flaky alumina flakes with improved smoothness, heat resistance and transparency, which are disadvantages of mica flakes, are used as a substrate. However, when plate-like alumina produced by a hydrothermal method is used as the substrate in the method described in the above-mentioned patent document, the adhesion of the metal oxide particles to the alumina is remarkably inferior, and the metal oxide is agglomerated to form large agglomerated particles. Thus, a pigment having satisfactory glitter is not obtained. In addition, even if metal oxide particles adhere to the plate-like alumina, the metal oxide particles covering the substrate are large, resulting in uniform glitter with no overall particle feeling and smooth and elegant glitter. It was difficult to obtain a certain silky pearl luster, and the design required for various applications could not be sufficiently satisfied.
JP-A-9-255891

As described above, when the conventional pearlescent pigment is coated with a metal oxide using a normal substrate, although the average particle diameter is large and the large substrate particles have a wide reflective area, there is discontinuous strong glitter, Overall, the pearl luster is uneven and lacks smoothness. On the other hand, when a substrate having a small average particle diameter was used, the above-mentioned particle feeling decreased, but a pearly luster having a smooth and elegant glittering silky feeling could not be extracted.
Accordingly, an object of the present invention is to provide a pearlescent pigment having a pearly luster that has a uniform silkiness and an elegant silky feeling as well as sufficiently satisfying the required design properties in view of the above-described state of the prior art. is there.

  Another object of the present invention is to provide a single coating method, a two-coat one-bake coating method, a three-coat two-bake coating method, or at least one layer of at least one arbitrary layer between coats or coat layers laminated. An object of the present invention is to provide a coating composition capable of forming a coating film having characteristic luster in a coating method for forming a nacreous coat layer.

The above object is achieved by the present invention described below.
That is, the present invention is a coating composition comprising a pearlescent pigment and a film-forming resin, wherein the pearlescent pigment has an average particle size of 0. a flaky substrate is 1 to 50 [mu] m, consists of a coating layer comprising at least one metal oxide formed on its surface, the particle diameter of the metal oxide Ri range near the 1 to 500 nm, and, for coating film formed by coating, the ratio of the 45 ° light intensity and 0 ° received light intensity in the elevation angle 0 ° or more as measured by goniophotometer (45 ° / 0 °) and the said der Rukoto 100 or less A coating composition comprising a pearlescent pigment is provided.

In pearlescent pigment constituting the coating composition of the present invention, it metal oxide coating layer is a mixed layer and / or the lamination of two or more metal oxides; group quality aspect ratio (particle diameter / thickness ) Is 5 to 500; the substrate has a mean particle size statistical variation coefficient of 20 to 90; and the average particle size of the pearlescent pigment is preferably 20 to 90.

Further, the present invention activates the surface of a substrate generated by a hydrothermal method in advance , disperses a flaky substrate having an average particle diameter of 0.1 to 50 μm on which the surface has been activated, Metal salt having a particle diameter in the range of 1 to 500 nm is formed on the substrate surface by hydrolyzing the metal salt in the liquid and depositing the generated metal hydroxide or metal oxide on the substrate surface and then heat-treating the deposit. Provided is a method for producing a pearlescent pigment characterized by forming an oxide coating layer. The surface activation is preferably performed by at least one method selected from plasma treatment, ultrasonic treatment, acid treatment, alkali treatment, impact treatment, and chemical etching treatment.

Further, the present invention provides a coating composition characterized by containing said pearlescent pigment and film-forming resin, the paint composition, a liquid and a pearlescent pigment and film-forming resin It is preferable to contain in a medium.

The present invention also provides a coating composition comprising a base coat layer comprising the coating composition of the present invention and a clear coat layer formed on the base coat layer.
In the coating composition, the statistical dispersion value of the reflected light intensity in the photometer is 5 or less; and in the variable angle photometer, the ratio of the 45 ° received light intensity at an elevation angle of 0 ° or more and the 0 ° received light intensity. (45 ° / 0 °) is preferably 100 or less.

  The present invention also provides an arbitrary colored base coat layer formed on the substrate surface, a second base coat layer comprising the coating composition of the present invention formed on the base coat layer, and the second base coat layer. A coating composition comprising the formed clear coat layer; and at least one arbitrary coat layer formed on the surface of the substrate; and the coating composition of the present invention formed on the coat layer or on the coat layer A coating composition comprising at least one layer comprising a product is provided.

  As a result of intensive studies to achieve the object of the present invention, the present inventors have activated the surface of a substrate obtained by a hydrothermal method, and then have at least one particle diameter in the range of 1 to 500 nm. It has been found that the pearl luster pigments coated with various metal oxides and the color appearance of the colored products using the pigments have a design that gives a smooth and elegant glittery silky color tone with no particle feeling. Moreover, when the said various coating films were formed on the base | substrate using the coating composition containing the said pearl luster pigment, this coating film discovered that the favorable design property was fully exhibited.

Next, the present invention will be described in more detail with reference to preferred embodiments.
The hydrothermal method in the present invention is a method for growing a crystal of a substrate such as alumina in a high-temperature and high-pressure solvent. The crystal growth conditions are specific to the chemical structure of the substance constituting the substrate, the solvent used, the temperature, the pressure, etc., and an arbitrary substrate can be synthesized according to the average particle diameter and aspect ratio required for the substrate. The chemical and physical properties of the substrate produced by the hydrothermal method are specific that can only be obtained by hydrothermal methods.

  Substrates obtained by the hydrothermal method include alumina, boehmite, iron oxide, hydroxyapatite, zirconia, titanate, titanium oxide, cobalt hydroxide hydroxide, calcium silicate, etc., but particle uniformity and smoothness Any substrate may be used as long as it has heat resistance, transparency, and the required design properties, and alumina that satisfies the above conditions in a well-balanced manner is preferable. Such preferable flaky alumina substrates are known per se, for example, trade names: YFA-02050 (average particle size 2.0 μm, aspect ratio 50), YFA-07070 (average particle size 7.0 μm, aspect ratio 70). ), YFA-05070 (average particle diameter 5.0 μm, aspect ratio 70), YFA-10030 (average particle diameter 10.0 μm, aspect ratio 27), etc., for example, obtained from Kinsei Matech Corporation and used in the present invention. be able to.

  The average particle size of the substrate is 0.1 to 50 μm, preferably 0.3 to 30 μm, and more preferably 0.5 to 20 μm. When the average particle diameter exceeds 50 μm, the pearl luster pigment obtained is strongly reflected and unfavorable in that the silky color tone is impaired. On the other hand, if the average particle size is less than 0.1 μm, scattered light is strong, and the resulting pearlescent pigment is not preferable in that it impairs the silky color tone. Further, the aspect ratio of the substrate is 5 to 500, preferably 7 to 300, and more preferably 10 to 200. When the aspect ratio of the substrate is less than 5, it is not preferable in that the orientation is poor and it is difficult to obtain interference light (pearly luster) in the obtained pearl luster pigment. On the other hand, when the substrate aspect ratio exceeds 500, the circulation is performed. It is not preferable in that the substrate is easily broken during handling, such as during stirring and dispersion.

  The particle size distribution of the substrate has a statistical variation coefficient (CV value) of 20 to 90, preferably 25 to 80, more preferably 30 to 70. The CV value indicates the percentage of the standard deviation and the average particle size in the particle size distribution, and indicates the degree of dispersion of the particle size distribution. The particle size distribution was measured using a Multisizer3 COULTER COUNTER manufactured by BEKMAN COULTER, and the statistical variation coefficient was calculated together.

  When the CV value of the substrate is 20 or more, the balance between small particle diameter particles that generate scattered light and particles that generate slightly stronger reflected light is good, and a silky color tone can be obtained in the resulting pearlescent pigment. On the other hand, when the CV value of the substrate is less than 20, the particle size distribution of the substrate is extremely sharp, but both the small particle size substrate particles that generate scattered light and the large particle size substrate particles that generate slightly stronger reflected light are both present. This results in a decrease in the balance between scattered light and reflected light, and the resulting pearlescent pigment loses a silky color tone. On the other hand, if the CV value of the substrate exceeds 90, the balance between the scattered light and the reflected light is lost, and the silky color tone is similarly impaired in the obtained pearl luster pigment.

  The pearlescent pigment of the present invention can be obtained by activating the surface of the substrate and then coating the surface with at least one metal oxide. In the pearlescent pigment of the present invention, the particle diameter of the metal oxide needs to be 1 to 500 nm, preferably 3 to 300 nm, more preferably 5 to 200 nm. When the particle diameter of the metal oxide covering the substrate is 1 to 500 nm, the crystallinity of the metal oxide is high, and the refractive index inherent to the metal oxide is sufficiently developed. The top surface of the pearlescent pigment coating is smooth and has sufficient reflected light, resulting in satisfactory interference colors, no graininess, and a smooth and elegant glitter that has a higher silky feel. The design property to be satisfied can be sufficiently satisfied.

  In addition, said particle diameter refers to the particle diameter of the metal oxide particle after a hydrolysis or a sintering, or the aggregate of a metal oxide particle. The particle diameter of the metal oxide was calculated from an average value of 50 arbitrary particles selected from an image photograph of FE-SEM S-4800 (manufactured by Hitachi).

  When the particle diameter of the metal oxide exceeds 500 nm, the unevenness of the surface of the metal oxide layer is remarkably increased, and the reflected light is greatly reduced in the pearlescent pigment, so that a sufficient interference color does not occur. On the other hand, when the particle diameter of the metal oxide is less than 1 nm, the crystallinity of the metal oxide is remarkably lowered, and the refractive index inherent to the metal oxide is not obtained, and as a result, sufficient interference color does not occur in the pearlescent pigment. Therefore, even if the coating thickness of the metal oxide is limited, a sufficient interference color cannot be obtained unless the particle diameter of the metal oxide forming the coating layer is controlled.

  A pearlescent pigment with an interference color can be obtained by increasing the amount of coating by increasing the amount of the coating with the metal oxide. Further, a reddish or black pearlescent pigment can be obtained by coating the surface of the substrate with a colored metal oxide such as iron oxide. Further, a pearlescent pigment with higher saturation can be obtained by adsorbing fine particles of a coloring pigment described later on the surface of the pearlescent pigment.

Furthermore, the pearlescent pigment of the present invention is obtained by coating the above-mentioned substrate surface with a mixture of two or more kinds of metal oxides, or by layering and coating with two or more kinds of metal oxide layers step by step. Can do. By these mixture coating or laminated coating, physical properties that cannot be obtained with only one kind of metal oxide, such as light resistance and water resistance, can be improved. In particular, pearlescent pigments with higher luster can be obtained by sequentially laminating two or more metal oxides and increasing the layer.
Furthermore, the pearlescent pigment of the present invention preferably has a statistical variation coefficient (CV value) of 20 to 90 in its particle size distribution. The reason is the same as in the case of the substrate.

  Next, the manufacturing method of the pearl luster pigment of this invention is demonstrated. The pearlescent pigment of the present invention can be obtained by coating the surface of the substrate with a metal oxide having a particle diameter of 1 to 500 nm.

  Common pearlescent pigments can control the particle size of the metal oxide after hydrolysis or sintering after adhering to the substrate and the cohesiveness of the particles, and arrange the metal oxide particles on the substrate surface. is necessary. However, in the method described in Patent Document 1, the particle size, aggregation control and arrangement control of the metal oxide are practically impossible, and a pearlescent pigment having sufficient interference light cannot be obtained. The reason is that the substrate produced by the hydrothermal method is extremely excellent in surface smoothness, so that the adsorption ability of the metal oxide to the surface is low, and the aggregation of the metal oxides easily proceeds. As a result, the metal oxide exists as a huge aggregate and has a low adsorptivity to the substrate surface. Even when adsorbed, the coating thickness of the metal oxide is non-uniform and the top surface of the coating is uneven, so that the reflected light is greatly reduced and a sufficient interference color does not occur.

  Therefore, if the substrate produced by the hydrothermal method is coated with a metal oxide by a known technique and the adsorption capacity of the substrate surface is not improved even if the coating thickness is limited, the metal oxide of the coating layer is not formed. The particle size and its cohesiveness cannot be controlled, and a pearlescent pigment having a sufficient interference color cannot be obtained.

  In the present invention, it has been found that metal oxide particles can be finely and uniformly adsorbed onto the substrate surface by previously activating the surface of the substrate generated by the hydrothermal method. The surface activation is performed by, for example, plasma treatment such as thermal plasma treatment, low-temperature plasma treatment, ultrasonic treatment, acid treatment, alkali treatment, media dispersion treatment, high-pressure impact treatment, sandblast treatment, etc., ozone treatment, electric treatment There exist chemical etching processes, such as a chemical process, These are individual or the combination of 2 or more types is mentioned.

  Process gases used for plasma treatment include nitrogen, ammonia, nitrogen / hydrogen mixed gas, oxygen, ozone, water vapor, carbon monoxide, carbon dioxide, nitrogen monoxide, nitrogen dioxide and other oxygen-containing gases, helium, argon, neon Fluorination of carbon tetrafluoride, carbon hexafluoride, propylene hexafluoride, etc. at a volume ratio of 1/2 or less relative to rare gases such as xenon, halogen gases such as fluorine, chlorine and iodine, and oxygen-containing gases A single gas or a combination of two or more such as a mixed gas in which carbon gas is mixed may be mentioned.

  Examples of the plasma generating means include, for example, a method of plasma decomposition by applying a direct current to a gas, a method of plasma decomposition by applying a high frequency voltage to a gas, a method of plasma decomposition of a gas by electron cyclotron resonance, and a hot filament. For example, a method of thermally decomposing gas can be used.

The processing gas pressure at the time of the plasma processing is preferably 1 × 10 ^{−4 to} 100 Torr because an expensive vacuum chamber or evacuation apparatus is required if the processing pressure is low. The actual process gas pressure is appropriately determined by the excitation means within said pressure range, the device is simple and relatively process that also plasma can be generated in a high state of the gas pressure direct current or high-frequency current applied can 1 × 10 the ^{- 2 to} 100 Torr is more preferable.

  The input power required for the plasma treatment varies depending on the electrode area and shape. However, the plasma density is reduced when it is low, and the treatment takes time. When it is high, the treatment is nonuniform.

  When the electrode structure used for the plasma treatment is a parallel plate type, a coaxial cylindrical type, a curved opposed plate type, or a hyperboloid opposed parallel type, a voltage is applied by a capacitive coupling method. In addition, in the case of applying a high frequency voltage, it can be applied in an inductive manner using an external electrode. The distance between the electrodes is appropriately determined depending on the processing pressure and the substrate. However, since the plasma density decreases and high power is required as the length increases, it is preferable to make the plasma processing as short as possible.

  The plasma treatment time is determined by the input power. However, if the time is shorter, the degree of activation of the substrate is not sufficient, and even if it is too long, a significant improvement in the degree of activation of the substrate cannot be expected. 60 minutes is preferred. Further, the temperature during the plasma treatment does not necessarily need to be heated or cooled.

  The plasma treatment needs to be performed uniformly over the entire surface of the flaky substrate. Therefore, it is preferable to perform the plasma treatment while rotating the flaky substrate. Examples of such a stirring method include a method of sealing a flaky substrate in a container and rotating the whole container, a method of mixing by vibration, and the like, which are determined as appropriate depending on the particle diameter of the flaky substrate, the processing amount, and the like.

  The ultrasonic oscillator used for the ultrasonic treatment only needs to have an oscillation frequency in the range of 50 Hz to 100 KHz and an output in the range of 20 to 1000 W. If the oscillation frequency is lower than 50 Hz, the surface uniformity of the energy distribution of the ultrasonic wave striking the flaky substrate is significantly reduced, resulting in poor activation. On the other hand, if the oscillation frequency is higher than 100 KHz, the overall energy density is significantly reduced, and similarly, the substrate activation is poor. Even within the above range, cavitation may occur depending on the tank structure, tank material, or type of dispersion medium used. In this case, it is desirable to raise the oscillation frequency or lower the output so that cavitation does not occur.

  In the present invention, the ultrasonic vibration may be given continuously or intermittently, but may be given by adjusting to an appropriate condition in the above-mentioned frequency range of 50 Hz to 100 KHz and output of 20 to 1000 W. preferable.

  Acids used in the acid treatment include inorganic acids such as hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, and carbonic acid; organic acids such as acetic acid, citric acid, and benzoic acid; and resin acids such as acrylic acid and rosin. Examples of the alkali used in the alkali treatment include alkali salts such as caustic soda and caustic potash, alkaline earth salts such as calcium hydroxide, weak bases such as ammonia, sodium carbonate, aniline and phenol, alone or 2 More than one type of combination can be mentioned.

  In the acid treatment or alkali treatment, the acid or alkali solution concentration may be in the range of 0.1 to 99% by mass and the temperature may be in the range of 5 to 95 ° C, but the efficient treatment temperature is more preferably 15 to 70 ° C. The treatment time is appropriately determined depending on the concentration and temperature, but is preferably in the range of 5 minutes to 6 hours. In the acid or alkali treatment, the same treatment may be repeated twice or more, or alternately one or more treatments may be repeated. Moreover, since acid treatment or alkali treatment adjusts pH, a pH buffer material may be used, and a surfactant or an organic solvent may be used in combination as an auxiliary agent.

  The impact treatment is a method of physically activating the substrate. Specific methods include a method of partially scraping the substrate surface by shaking and collision, and a method of polishing by rotation. Examples of the treatment method satisfying these include dispersion impact treatment such as homogenizer, dissolver, sand mill, high speed stirrer, paint conditioner, high pressure impact treatment such as high pressure homogenizer, sand blast treatment, jet mill treatment and the like.

  The substrate concentration in the liquid medium in the impact treatment is 1 to 200% by mass, preferably 5 to 150% by mass. If it is less than 1% by mass, the impact efficiency is poor, whereas if it exceeds 200% by mass, the viscosity increases and the impact treatment becomes difficult. Glass beads, steel balls, zirconia beads, and the like can be used for the impact treatment that requires media during the impact treatment, and the mass ratio of the media to the substrate is 0 to 1,000 mass%, preferably 0 to 500 mass%. In addition, when the substrate surface is sufficiently activated by the collision between the substrates, it is not particularly necessary to use media.

  The impact treatment may use a pH buffer material, and may further use a surfactant, an organic solvent, or the like as an auxiliary agent. The impact treatment time is determined by the substrate concentration and the type and amount of the media. However, if the time is shorter, the substrate activation level is not sufficient, and even if it is too long, the substrate activation level cannot be expected to improve significantly. Specifically, 1 to 60 minutes is preferable. In the physical activation process, if the impact strength of the substrate is increased, the substrate may be destroyed in addition to surface activation of the substrate. In this case, the particle size distribution and the CV value are greatly increased. Attention to change is necessary.

  In addition, conventionally known methods can be widely used for chemical etching treatments such as ozone treatment, UV treatment, and electrochemical treatment.

  The pearl luster pigment of the present invention can be obtained by a known method of the surface-treated substrate, for example, a method of thermally hydrolyzing a metal salt such as titanium, zirconium, tin, or iron in water in which the substrate is dispersed, or an alkali. The above-mentioned metal hydrated oxide is adsorbed onto a substrate with a particle diameter of 1 to 500 nm by a method such as neutralization hydrolysis using, and then fired. Further, by performing this firing step in a reducing atmosphere, the metal oxide becomes low-order titanium oxide or low-order iron oxide, and a blackish pearlescent pigment can be obtained. In addition to using a metal oxide, other design properties can also be imparted by a known method.

The metal atom amount of the water-soluble metal salt necessary for obtaining pearl luster (interference color) is 2.0 × 10 ⁻⁵ mol to 2.0 × 10 ⁻¹ mol per 1 m ^{2 of} the flaky substrate, more preferably 4. From 0 × 10 ⁻⁵ mol to 1.0 × 10 ⁻¹ mol. When the metal atomic weight is less than 2.0 × 10 ⁻⁵ mol, the flaky substrate cannot be coated and no interference light is generated. On the other hand, if the amount of metal atoms exceeds 1.0 × 10 ⁻¹ mol, the flaky substrate can be coated, but cracks are likely to occur in the coating layer after firing, resulting in inconvenience in that the interference light intensity decreases. It is.

  Next, the coating composition of the present invention will be described. The coating composition of the present invention contains the pearlescent pigment of the present invention and a film-forming resin, and preferably contains the pearlescent pigment and the film-forming resin in a liquid medium. Examples of the film-forming resin used here include conventionally known paint fields such as acrylic resin, acrylic melamine resin, vinyl chloride-vinyl acetate copolymer resin, alkyd resin, polyester resin, polyurethane resin and amino resin. However, the film-forming resin used in the present invention is not limited to the above-described resins.

  As the solvent for dissolving or dispersing the pearlescent pigment and the film-forming resin, those conventionally known for paints are used. Specific examples include water, toluene, xylene, butyl acetate, methyl acetate, acetone, methyl ethyl ketone, methyl isobutyl ketone, methanol, ethanol, butanol, cyclohexane and the like. These solvents may be used as a mixed solvent. Good.

  In the coating composition of the present invention, the pearlescent pigment of the present invention is used in a proportion of 0.005 to 50 parts by mass, preferably 0.1 to 30 parts by mass with respect to 100 parts by mass of the film-forming resin. . If the amount of the pearlescent pigment used is less than 0.005 parts by mass, the coating composition intended by the present invention cannot be obtained. Moreover, when the usage-amount of a pearl luster pigment exceeds 50 mass parts, although the coating composition made into the objective of this invention is obtained, since the physical property of a coating film falls, it is unpreferable.

  In the present invention, the pearl luster pigment may be used alone or in combination with other pigments. As the coloring pigment that may be used in combination, pigments used in ordinary paints can be used. Specifically, for example, phthalocyanine pigments, quinacridone pigments, perylene pigments, anthraquinone pigments, DPP pigments, Examples thereof include metal complex pigments, transparent iron oxide pigments, carbon black, titanium oxide, and zinc oxide. In addition, examples of the metal powder pigment include aluminum powder, copper powder, and stainless steel powder. Among these, aluminum powder is most commonly used. Moreover, a metal colloid etc. can also be used as a special metal pigment. As the mica pigment used in the present invention, conventionally known mica pigments can be widely used, and examples thereof include transparent pearl mica and colored mica. Furthermore, examples of the light interference pigment include interference mica, interference alumina, interference silica (interference glass) and the like. In addition to the coating composition of the present invention, a filler, an antistatic agent, a stabilizer, an antioxidant, an ultraviolet absorber and the like can be blended as necessary.

  When the coating composition of the present invention contains the pearlescent pigment of the present invention and another pigment, a base coating containing the pearlescent pigment of the present invention and a base coating containing the other pigment are prepared. In addition, these two kinds of base paints can be arbitrarily mixed to form a paint, or a pearlescent pigment and another pigment may be mixed from the beginning to form a paint.

  The coating composition obtained in this way is applied by spray coating, electrostatic coating, flow coating, roll coating, etc. on a substrate such as a metal plate, glass, ceramic, or plastic plate that has been subjected to a ground treatment as necessary. Dry and crosslink to form a colored coat layer.

  The coating film formed by applying the coating composition of the present invention to a substrate has a smooth and elegant silky color tone without particle feeling as compared with a conventional titanium oxide-coated pearlescent pigment. Because of the above properties, at least one layer of the pearl of the present invention is provided on a single coating method, a two-coat one-bake coating method, a three-coat two-bake coating method, or at least one arbitrary layer between coats or coat layers laminated. In a coating method in which a coating layer is formed from a coating composition containing a luster pigment, a coating film having excellent characteristics that is not found in a coating film obtained from a conventional coating composition can be formed.

  In addition, the above-mentioned colored coat layer is used as a base coat layer, and a clear coat agent prepared by dissolving or dispersing a resin having low compatibility with the above-described film-forming resin in an organic solvent is applied to the base coat layer, followed by heat treatment after drying. A coating film can also be formed. The coating film formed by applying the coating composition of the present invention to a substrate has no grain feeling and has a smooth and elegant silky glitter. That is, since the pearl luster pigment of the present invention has uniform particles, there is no partial strong glitter due to large particles, and it has continuous and uniform glitter. Furthermore, the balance between reflected light and scattered light is good, and it provides a smooth and elegant silky feel.

  A partial strong glitter occurs because the light incident on the coating film is specularly reflected by the pearlescent pigment. By measuring the specular reflection light intensity of the continuous coating surface, statistically calculating the degree of dispersion of the reflection intensity, that is, the degree of dispersion, and comparing the dispersion values, partial strong radiance and uniform The difference from glitter can be quantified. The photometer is not particularly limited as long as it can measure the specular reflected light intensity of the continuous coating film surface, but a photometer capable of measuring the reflection intensity while moving the sample surface in the X-axis direction in the apparatus is preferable. As a specific example, a 3D variable angle photometer GP-200 manufactured by Murakami Color Research Laboratory satisfies the above measurement conditions.

  When the dispersion value quantified is 5 or less, the coating film made of the coating composition of the present invention obtains a smooth brilliancy that is uniform and free of particle feeling in the visual sense. Thus, it is impossible to obtain a uniform and smooth glitter without grain feeling.

  The light incident on the coating film is divided into specularly reflected light and scattered light and reflected outside the coating film. The balance between the regular reflection light and the scattered light provides a smooth and elegant silky color tone. Light other than regular reflection is scattered in all directions and exists as three-dimensional scattered light. By capturing the specularly reflected light and these three-dimensional scattered light three-dimensionally, it is possible to reproduce a sensation close to that seen by humans. These above-mentioned reflected lights can be measured with a photometer shown in the apparatus. The photometer is not particularly limited as long as the reflection intensity can be measured while changing the light receiving angle at an arbitrary elevation angle, but a three-dimensional goniophotometer capable of continuously measuring reflected light is preferable. As a specific example, a 3D variable angle photometer GP-200 manufactured by Murakami Color Research Laboratory satisfies the above measurement conditions.

  The silky feeling of the coating is measured by measuring the intensity of reflected light and scattered light at an arbitrary elevation angle using a three-dimensional goniophotometer. The reflection intensity at the 0 ° light receiving angle that is the scattered light can be measured and quantified by the intensity ratio (45 ° / 0 °) between 45 ° and 0 °. When the reflection intensity ratio (45 ° / 0 °) between the light-receiving angle of 45 ° and the light-receiving angle of 0 ° is 100 or less, the coating film made of the coating composition of the present invention has a smooth and elegant silky brightness. However, when the reflection intensity ratio (45 ° / 0 °) between the light receiving angle of 45 ° and the light receiving angle of 0 ° is larger than 100, it is impossible to obtain a silky glittering feeling in the visual feeling.

  The pearlescent pigment of the present invention is oriented and does not lose its surface smoothness even when the particles are small, the aspect ratio is large, and the content in the coating film is large. In addition, because it is a pearlescent pigment that uses chemically uniform plate-like particles produced by the hydrothermal method, its optical characteristics are also unique, it has an excellent balance between reflected light and diffused light, and is smooth and free of particle feeling. An elegant silky lustre and excellent finish can be obtained. On the other hand, in the coating color using a general pearlescent pigment, when the average particle size is reduced, the plate-like particles are non-uniform and the aspect ratio is small, so the fine pigment is not oriented in the coating film, There are drawbacks that the brightness is remarkably lowered and the smoothness of the clear finish is impaired. In addition, the balance between reflected light and scattered light is poor in optical characteristics, and an elegant silky feeling cannot be obtained.

  The pearl luster pigment of the present invention is extremely excellent as a pigment for ceramics, plastics, inks, toners, inkjet inks, and cosmetics. Further, depending on the application, treatments such as water resistance, weather resistance, chemical resistance, discoloration resistance, and high dispersibility are appropriately applied and used for each application.

EXAMPLES Next, although an Example and a comparative example demonstrate this invention further in detail, this invention is not limited by these Examples. In the text, “part” or “%” is based on mass.
[Production example of pearlescent pigment]
Example 1
20 g of YFA-02050 (trade name) (produced by Kinsei Matech Co., Ltd., average particle diameter of 2.0 μm, aspect ratio of 50, CV value of 45) which is a plate-like alumina (hydrothermally generated alumina) produced by a hydrothermal method The flask was put in a 1 liter flask, and the pressure in the flask was reduced to 0.05 Torr. Then, under an oxygen atmosphere, the input power was 40 W at 0.11 Torr, and 13.56 MHz by a powder plasma processing apparatus (“PT-500” manufactured by Samco International). The plasma treatment was performed at room temperature for 5 minutes.

  In another 1-liter flask, 20 g of sodium sulfate (anhydrous) is added to 300 ml of demineralized water and dissolved by stirring. To this solution, 20 g of the plate-like alumina subjected to the above plasma treatment is added and stirred and dispersed. To this dispersion, 28 g of a titanium chloride solution having a titanium concentration of 16.5% is injected and stirred, heated and refluxed for 4 hours. Thereafter, the insoluble solid was separated by filtration, washed with water, dried, and further heat treated at 700 ° C. for 1 hour. Water was added to the treated product to dissolve the free salt while stirring, and then the insoluble solid was separated by filtration, washed with water and dried to obtain titanium oxide-coated plate-like alumina (Example 1). .

(Example 2)
20 g of hydrothermally produced alumina YFA-07070 (trade name) (manufactured by Kinsei Matech Co., Ltd., average particle size 7.0 μm, aspect ratio 70, CV value 44) was placed in a 1 liter flask and 300 ml of demineralized water was added. Add and disperse with stirring. Ultrasonic treatment was performed at room temperature for 15 minutes using an ultrasonic treatment apparatus ("UD-200" manufactured by Tommy Industries Co., Ltd.) at an input power of 180 W and a frequency of 20 kHz. Thereafter, 20 g of sodium sulfate (anhydrous) is added and dissolved by stirring. 20 g of titanium chloride solution having a titanium concentration of 16.5% is poured into this dispersion and stirred, heated and refluxed for 4 hours. The insoluble solid was then filtered off, washed with water, dried, and further heat treated at 700 ° C. for 1 hour. Water was added to the resulting treated product to dissolve the free salt while stirring, and then the insoluble solid was separated by filtration, washed with water and dried to obtain titanium oxide-coated plate-like alumina (Example 2). .

(Example 3)
20 g of hydrothermally generated alumina YFA-05070 (trade name) (manufactured by Kinsei Matec Co., Ltd., average particle size 5.0 μm, aspect ratio 70, CV value 37) was placed in a 1 liter flask, and 300 ml of demineralized water was added. Add and disperse with stirring. To this, 20 g of 35% hydrochloric acid was injected, and acid treatment was performed at room temperature for 15 minutes.

  Next, 40 g of sodium sulfate (anhydrous) is added and dissolved by stirring. To this dispersion, 30 g of a titanium chloride solution having a titanium concentration of 16.5% and 1.9 g of a 50% stannic chloride solution are injected and stirred, heated and refluxed for 4 hours. Further, the insoluble solid was separated by filtration, washed with water, dried, and further heat-treated at 800 ° C. for 30 minutes. Water was added to the treated product to dissolve the free salt while stirring, and then the insoluble solid was separated by filtration, washed with water and dried to form a titanium oxide-tin oxide mixed coated plate-like alumina (Example 3). Got.

Example 4
20 g of YFA-02050 (trade name), which is hydrothermally generated alumina, is placed in a 1-liter flask, and 300 ml of demineralized water is added and dispersed by stirring. To this, 10 g of caustic soda was injected, and alkali treatment was performed at room temperature for 15 minutes. Next, the pH is adjusted to 2 using 35% hydrochloric acid, and 40 g of sodium sulfate (anhydrous) is added and dissolved by stirring. Into this dispersion, 28 g of a titanium chloride solution having a titanium concentration of 16.5% and 1.0 g of a 50% stannic chloride solution are injected and stirred, heated and refluxed for 4 hours.

  Next, the insoluble solid was separated by filtration, washed with water, dried, and further heat-treated at 800 ° C. for 30 minutes. Water was added to the treated product to dissolve the free salt while stirring, and then the insoluble solid was separated by filtration, washed with water and dried to form a titanium oxide-tin oxide mixed coated plate-like alumina (Example 4). Got.

(Example 5)
20 g of YFA-07070 (trade name), which is hydrothermally produced alumina, is placed in a 1 liter flask, and 300 ml of demineralized water is added and dispersed by stirring. Ultrasonic treatment was performed at room temperature for 15 minutes using an ultrasonic treatment apparatus ("UD-200" manufactured by Tommy Industries Co., Ltd.) at an input power of 180 W and a frequency of 20 kHz. Thereafter, 20 g of nitric acid was injected, and acid treatment was performed at room temperature for 15 minutes.

  To this dispersion, 1.0 g of a 50% stannic chloride solution is poured and stirred, and the pH is adjusted to 6.0 with a sodium hydroxide solution. Thereafter, the insoluble solid was separated by filtration, washed with water, and dried to obtain a tin oxide-coated plate-like alumina. 20 g of sodium sulfate (anhydrous) is dissolved in 300 ml of demineralized water, and the crushed tin oxide-coated plate-like alumina is added to and dispersed therein. 20 g of titanium chloride solution having a titanium concentration of 16.5% is injected and stirred, heated and refluxed for 4 hours. Thereafter, the insoluble solid was separated by filtration, washed with water, dried, and further heat treated at 800 ° C. for 1 hour. Water was added to the treated product and the free salt was dissolved while stirring, and then the insoluble solid was separated by filtration, washed with water, and dried to form a plate-like alumina coated with tin oxide and titanium oxide (Example 5). Got.

(Example 6)
20 g of YFA-07070 (trade name), which is hydrothermally generated alumina, was placed in a 250 ml polybin, 100 ml of demineralized water and 100 g of 2 mm glass beads were added, and impact treatment was performed with a paint conditioner for 30 minutes. Thereafter, the dispersion is added to 200 ml of demineralized water and stirred. Into the above dispersion, 1.0 g of 50% stannic chloride solution is poured and stirred, and adjusted to pH 6.0 with sodium hydroxide solution. Thereafter, the insoluble solid was separated by filtration, washed with water, and dried to obtain a tin oxide-coated plate-like alumina.

  20 g of sodium sulfate (anhydrous) is dissolved in 300 ml of demineralized water, and the crushed tin oxide-coated plate-like alumina is added to and dispersed therein. 20 g of titanium chloride solution having a titanium concentration of 16.5% is injected and stirred, heated and refluxed for 4 hours. Thereafter, the insoluble solid was separated by filtration, washed with water, dried, and further heat treated at 800 ° C. for 1 hour. Water was added to the resulting treated product and the free salt was dissolved while stirring, and then the insoluble solid was separated by filtration, washed with water and dried to form a plate-like alumina coated with tin oxide and titanium oxide (Example 6). Got.

(Example 7, Example 8)
20 g of YFA-10030 (trade name) (manufactured by Kinsei Matec Co., Ltd., average particle diameter 10.0 μm, aspect ratio 27, CV value 50), which is hydrothermally generated alumina, is placed in a flask having an internal volume of 1 liter. After reducing the pressure to 05 Torr, a high frequency voltage of 13.56 MHz was applied by a powder plasma processing apparatus (“PT-500” manufactured by Samco International Co., Ltd.) with an input power of 40 W in a steam atmosphere at 0.11 Torr, and at room temperature for 5 minutes. Plasma treatment was performed. In another 1-liter flask, 20 g of sodium sulfate (anhydrous) is added to 300 ml of demineralized water and dissolved by stirring. To this solution, 20 g of plasma-treated plate-like alumina is added and dispersed by stirring.

  Separately, a solution A was prepared by dissolving 50 g of a titanium chloride solution having a titanium concentration of 16.5% in 300 ml of demineralized water. After adjusting the pH of the plate-like alumina dispersion to 2.0 with hydrochloric acid and heating to 80 ° C., it takes 4 hours until the substrate obtains a silver interference color at a constant rate with a metering pump. inject. During this time, 10% sodium hydroxide solution was added to maintain the pH in the dispersion at 2.0, and the temperature in the dispersion was also maintained at 80 ° C.

  Solution A was injected until the substrate obtained a silver interference color, then heated and refluxed for 1 hour. Thereafter, the insoluble solid was separated by filtration, washed with water, dried, and further heat treated at 700 ° C. for 1 hour. Water was added to the treated product to dissolve the free salt while stirring, and then the insoluble solid was separated by filtration, washed with water, and dried to obtain titanium oxide-coated plate-like alumina (Example 7). . A titanium oxide-coated plate-like alumina (Example 8) was obtained in the same manner as in Example 7, except that the hydrothermally generated alumina was changed to YFA-07070 (trade name).

(Comparative Example 1)
20 g of sodium sulfate (anhydrous) is added to 300 ml of demineralized water and dissolved with stirring. To this solution, 20 g of plate-like alumina A (average particle size 55 μm, aspect ratio 30, CV value 95) which is not a hydrothermal product is added and stirred and dispersed. 30 g of titanium chloride solution having a titanium concentration of 16.5% is poured into this dispersion and stirred, heated and refluxed for 4 hours. Thereafter, the insoluble solid was separated by filtration, washed with water, dried, and further heat treated at 700 ° C. for 1 hour. Water was added to the resulting treated product to dissolve the free salt while stirring, and then the insoluble solid was separated by filtration, washed with water and dried to obtain titanium oxide-coated plate-like alumina (Comparative Example 1). .

(Comparative Example 2)
20 g of sodium sulfate (anhydrous) is added to 300 ml of demineralized water and dissolved with stirring. To this solution, 20 g of plate-like alumina B (average particle size 10 μm, aspect ratio 4.0, CV value 60) which is not a hydrothermal product is added and stirred and dispersed. 30 g of titanium chloride solution having a titanium concentration of 16.5% is poured into this dispersion and stirred, heated and refluxed for 4 hours. Thereafter, the insoluble solid was separated by filtration, washed with water, dried, and further heat treated at 700 ° C. for 1 hour. Water was added to the treated product to dissolve the free salt while stirring, and then the insoluble solid was separated by filtration, washed with water and dried to obtain titanium oxide-coated plate-like alumina (Comparative Example 2). .

(Comparative Example 3)
Titanium oxide-coated plate-like alumina (Comparative Example 3) was obtained in the same manner as in Example 1 except that plate-like alumina (YFA-02050) not subjected to plasma treatment was used.
(Comparative Example 4)
A titanium oxide-coated plate-like alumina (Comparative Example 4) was obtained in the same manner as in Example 2 except that plate-like alumina (YFA-07070) not subjected to ultrasonic treatment was used.

(Comparative Example 5)
A titanium oxide-tin oxide mixed coated plate-like alumina (Comparative Example 5) was obtained in the same manner as in Example 3 except that plate-like alumina without acid treatment (YFA-05070) was used.

(Comparative Example 6)
A titanium oxide-tin oxide mixed coated plate-like alumina (Comparative Example 6) was obtained in the same manner as in Example 4 except that plate-like alumina (YFA-02050) not subjected to alkali treatment was used.
(Comparative Example 7)
A commercial product Iriodin 225WII (trade name) (manufactured by Merck Japan Ltd.) in which mica is coated with titanium oxide is referred to as Comparative Example 7.

  The average particle diameter (μm), aspect ratio and CV value of the substrates used in Examples 1 to 8 and Comparative Examples 1 to 6, and the pearlescent pigment metal obtained in Examples 1 to 8 and Comparative Examples 1 to 7 The particle diameter (nm) and CV value of the oxide were determined and summarized in Table 1. The average particle diameter and aspect ratio were calculated from the average value of 50 arbitrary particles selected from an image photograph taken with a scanning electron microscope ERA-8000 (manufactured by ELIONIX). The CV value is a value obtained by measuring a statistical variation coefficient by measuring using a Multisizer3 COULTER COUNTER manufactured by BEKMAN COULTER. The particle diameter of the metal oxide was calculated from the average value of 50 arbitrary particles selected from an image photograph of FE-SEM S-4800 (manufactured by Hitachi).

[Production example of paint for automobiles]
This example shows an example of production and evaluation when the pearl luster pigment of the present invention is used as a coating composition. Formulation examples in evaluation are summarized in Table 2.

  Each of the above blends A to H is subjected to a simple dispersion treatment with a sand mill, and 50 parts of each of the blends A to H and 50 parts of the blend P are uniformly mixed to form a coating composition A to H (Table 3). (Containing 8.55 parts of pearlescent pigment per 100 parts of coating composition). (These are referred to as Example paints A to H.)

  Each of the above blends I to O is subjected to a simple dispersion treatment with a sand mill, and 50 parts of each of the blends I to O and 50 parts of the blend P are uniformly mixed to form a coating composition I to O (Table 3). (Containing 8.55 parts of pearlescent pigment per 100 parts of coating composition). (These are referred to as comparative example paints I to O.)

  Each of the Example paints A to H obtained in Examples 1 to 8 and the Comparative paints I to O obtained in Comparative Examples 1 to 7 were applied to a black color paper. The coating was carried out with a 6 bar coater. After drying at room temperature for 30 minutes, a coating sample was prepared by baking and curing at 120 ° C. for 30 minutes.

  For these coated samples, the uniformity of glitter was visually observed and a three-dimensional goniophotometer (GP-200, manufactured by Murakami Color Research Laboratory) was used to measure reflected light, A light source, incident angle 45 °, light receiving angle 45 °. The sample was measured under the conditions of a light receiving slit of 0.4 mm square, a sample surface X-axis movement of 40 mm, and data sampling at an interval of 0.1 mm, and a statistical dispersion value of the light receiving intensity was calculated. The measurement apparatus is shown in FIG. 1, an example of the graph obtained by the measurement is shown in FIG.

  Furthermore, using a visual and three-dimensional goniophotometer (Murakami Color Research Laboratory, GP-200) for a smooth state without particle feeling, reflected light measurement, A light source, incident angle 45 °, receiving angle 45 ° and 0 ° The measurement was performed under the condition of an elevation angle of 2.5 °, and the reflection intensity ratio (45 ° / 0 °) was calculated. The measurement apparatus is shown in FIG. 1, an example of the graph obtained by the measurement is shown in FIG.

  The example paint has a lower dispersion value showing variation in glitter than the comparative paint, and has a uniform glitter overall. In addition, the example paint has a lower reflection intensity ratio at the light receiving angles of 45 ° and 0 ° than the comparative example paint, and has a smooth silky feeling that balances regular reflection light and scattered light.

  Furthermore, even in cosmetics, plastics, ceramics, inks, toners, and inkjet ink compositions containing the pearlescent pigment of the present invention, the silky feeling that is uniform and smooth and elegant with no particle feeling overall. And can fully satisfy the required design properties.

  The pearl luster pigment of the present invention has a uniform brightness as a whole and a silky color tone that is smooth and elegant with no particle feeling. In addition to the fields of paints, building materials, inks, toners, inkjet inks, cosmetics, etc., it is most suitable for fields that require design.

It is a figure which shows a measuring apparatus. It is a measurement graph of the reflection intensity change with respect to the X-axis movement distance. It is a measurement graph of a three-dimensional variable angle luminous intensity change (elevation angle 2.5 degrees).

Explanation of symbols

1: Light source 2: Sample 3: Light receiver 4: X axis 5: Y axis 6: Z axis 7: Incident angle 8: Light reception angle 9: Elevation angle 10: Comparative example paint O
11: Example paint C
12: Example paint A

Claims (15)

The surface of the alumina substrate or boehmite substrate produced by the hydrothermal method is activated in advance by at least one method selected from plasma treatment, ultrasonic treatment, acid treatment, alkali treatment, impact treatment and chemical etching treatment , and the surface Is dispersed in water, the metal salt is hydrolyzed in the dispersion, and the resulting metal hydroxide or metal oxide is applied to the surface of the substrate. After depositing, the deposit is heat-treated to form a metal oxide coating layer containing titanium oxide having a particle diameter in the range of 1 to 500 nm on the substrate surface. . Surface activation of the alumina substrate, a plasma treatment, ultrasonic treatment, acid treatment, a manufacturing method of the pearlescent pigment according to claim 1 carried out at least one method selected alkali treatment and impact treatment or al.   The formation of the metal oxide coating layer is carried out by coating with a mixture of two or more metal oxides and / or stepwise coating of two or more metal oxide layers and mixing the metal oxide coating layers The method for producing a pearlescent pigment according to claim 1 or 2, wherein the layer is a layer and / or a laminate.   The method for producing a pearlescent pigment according to any one of claims 1 to 3, wherein the flaky substrate has an aspect ratio (particle diameter / thickness) of 5 to 500.   The method for producing a pearlescent pigment according to any one of claims 1 to 4, wherein the flaky substrate has a statistical variation coefficient of an average particle diameter of 20 to 90. A coating composition comprising a pearlescent pigment and a film-forming resin, the surface of which the pearlescent pigment is produced by a hydrothermal method , plasma treatment, ultrasonic treatment, acid treatment, alkali treatment, impact treatment and the average particle diameter comprising activated with at least one method selected from chemical etching process includes a flaky alumina substrate or boehmite substrate is 0.1 to 50 [mu] m, at least titanium oxide formed on the surface A coating layer made of a metal oxide, the particle diameter of the metal oxide is in the range of 1 to 500 nm, and the coating film formed by coating has an elevation angle of 0 ° or more measured with a goniophotometer. A coating composition comprising a pearlescent pigment, wherein the ratio of 45 ° light receiving intensity to 0 ° light receiving intensity (45 ° / 0 °) is 100 or less. The coating composition containing the nacreous pigment according to claim 6, wherein the alumina substrate is activated by at least one method selected from plasma treatment, ultrasonic treatment, acid treatment, alkali treatment and impact treatment. . The coating composition comprising the pearlescent pigment according to claim 6 or 7 , wherein the metal oxide coating layer is a mixed layer and / or a laminate of two or more kinds of metal oxides. The coating composition according to any one of claims 6 to 8 , wherein a statistical variation coefficient of an average particle diameter of the pearlescent pigment is 20 to 90. The coating composition according to any one of claims 6 to 9 , comprising a pearl luster pigment and a film-forming resin in a liquid medium. A coating composition comprising a base coat layer comprising the coating composition according to any one of claims 6 to 10 , and a clear coat layer formed on the base coat layer. Statistical variance value of the reflected light intensity in the photometer is the coating composition of claim 1 1 5 or less. In goniophotometer, the ratio of the 45 ° light intensity and 0 ° received light intensity in the elevation angle 0 ° or more (45 ° / 0 °) is, the coating composition according to claim 1 1 or 1 2 is 100 or less . An arbitrary colored base coat layer formed on the substrate surface, a second base coat layer comprising the coating composition according to any one of claims 6 to 10 formed on the base coat layer, and the second base coat A coating composition comprising a clear coat layer formed on the layer. 11. At least one arbitrary coating layer formed on the substrate surface, and at least one layer comprising the coating composition according to any one of claims 6 to 10 formed on the coating layer or on the coating layer. A coating composition comprising:

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