FLAKY TITANATE AND METHOD FOR PRODUCTION THEREOF, AND USE THEREOF

Abstract

Provided is a flaky titanate that exhibits a high weathering resistance while at the same time having the ability to endow a coating film with a silky feeling having a shading feeling and a strong luster feeling, and a method for the production thereof suitable at least for inexpensive industrial production. The flaky titanate contains a basic organic compound wherein the content of basic functional groups thereof is not more than 2.4%, and provides a coating film having a goniospectrophotometric color measured value L* of at least 150. The method for producing a flaky titanate contains a step of classifying a flaking titanate having a basic organic compound at the surface and/or in interlayer position, to bring (D90D10)/D50 in the volume based particle size distribution to 1.5 or less.

Claims

1. A flaky titanate according to claim 2, wherein the flaky titanate has a goniospectrophotometric color measured value L*.sub.1 of 150 or more in the form of a paint film.

2. A flaky titanate comprising a basic organic compound, wherein the basic organic compound has a basic functional group content of 2.4% or less, and wherein the flaky titanate has a goniospectrophotometric color measured value L*.sub.2 of 60 or more in the form of a paint film.

3. A flaky titanate having (D90D10)/D50 of 1.5 or less in a volume particle size distribution measured by a laser diffraction/scattering method, wherein the D10, D50, and D90 express a cumulative 10% particle size, a median size, and a cumulative 90% particle size, respectively.

4. A method for producing a flaky titanate according to claim 3, comprising a step of classifying a flaky titanate having a basic organic compound between layers and/or on a surface thereof, thereby adjusting (D90D10)/D50 in a volume particle size distribution to be 1.5 or less.

5. A method for producing a flaky titanate according to claim 3, comprising a step of performing delamination between layers of a layered titanate with a basic organic compound, wherein the layered titanate has (D90D10)/D50 of 1.5 or less in a volume particle size distribution.

6. A method for producing a flaky titanate according to claim 3, comprising the steps of: obtaining a layered titanate by bringing a metal titanate into contact with an acid compound wherein the metal titanate has (D90D10)/D50 of 1.5 or less in a volume particle size distribution; and performing delamination between layers of the layered titanate with a basic organic compound.

7. The method according to claim 4, further comprising a step of allowing a flaky titanate having a basic organic compound between layers and/or on a surface thereof to exist in an aqueous medium with a pH of 6 or more and less than 10.

8. A luster pigment comprising the flaky titanate according to claim 3.

9. A dispersion liquid comprising at least the flaky titanate according to claim 3 and a dispersion medium.

10. A resin composition comprising at least the flaky titanate according to claim 3 and a resin.

11. A paint composition comprising at least the flaky titanate according to claim 3 and a resin.

12. A plastic resin composition comprising at least the flaky titanate according to claim 3 and a plastic resin.

13. An ink composition comprising at least the flaky titanate according to claim 3, a resin, and a solvent.

14. A luster pigment comprising the flaky titanate according to claim 2.

15. A dispersion liquid comprising at least the flaky titanate according to claim 2 and a dispersion medium.

16. A resin composition comprising at least the flaky titanate according to claim 2 and a resin.

17. A paint composition comprising at least the flaky titanate according to claim 2 and a resin.

18. A plastic resin composition comprising at least the flaky titanate according to claim 2 and a plastic resin.

19. An ink composition comprising at least the flaky titanate according to claim 2, a resin, and a solvent.

20. (canceled).

Description

EXAMPLES

[0149] Hereinafter, the present invention will be described in further detail with reference to examples. However, the present invention is not limited to the examples.

Example 1

[0150] Titanium oxide (Titanium Oxide A-100 manufactured by Ishihara Sangyo Kaisha), potassium carbonate, and lithium carbonate (both reagents manufactured by Kanto Kagaku) were thoroughly mixed in an agate mortar in a mass ratio of 100:40:9.2, and then calcined at 1,150 C. for 5 hours in the atmosphere to synthesize lithium potassium titanate having an orthorhombic lepidocrocite structure (K.sub.0.8Li.sub.0.27Ti.sub.1.73O.sub.4). The obtained lithium potassium titanate was ground in an agate mortar to obtain a lithium potassium titanate powder.

[0151] The obtained lithium potassium titanate powder and four times its mass of a 1.1 N aqueous sulfuric acid solution were mixed, stirred for 30 minutes, and ion-exchanged to obtain a layered titanate. The obtained layered titanate solid was filtrated and washed to obtain a layered titanate cake. The potassium amount included in the layered titanate cake was analyzed with a X-ray fluorescence spectrometer (RIX2100 manufactured by Rigaku). The result was 0.25% as K.sub.2O/TiO.sub.2.

[0152] The obtained layered titanate cake was redispersed in pure water to be 100 g/L in terms of TiO.sub.2 conversion to give a layered titanate dispersion liquid. The layered titanate dispersion liquid and aqueous ammonia were mixed to adjust the pH to 7.3. Subsequently, per 100 g of TiO.sub.2, 21.4 g of a 90% aqueous solution of 2-amino-2-methyl-1-propanol (0.3 neutralization equivalents relative to hydrogen ions included in the layered titanate) was added and stirred at room temperature for 1 hour to give a flaky titanate dispersion liquid. The pH of the flaky titanate dispersion liquid was 10.5.

[0153] Next, a mesh having an opening size of 45 m was attached to a slurry screener (SS95250 manufactured by Aco Japan Co., Ltd.), then a solution obtained by diluting the obtained flaky titanate dispersion liquid 2-fold with pure water was allowed to flow at 30 L/hour, and the flaky titanate dispersion liquid on the screen and the flaky titanate dispersion liquid under the screen were each recovered. Next, the mesh was changed to an opening size of 20 m, the flaky titanate dispersion liquid under the screen obtained through the 45 m classification was allowed to flow at 20 L/hour, and the flaky titanate dispersion liquid on the screen (expressed as flaky titanate dispersion liquid among sieves) and the flaky titanate dispersion liquid under the screen were each recovered.

[0154] The flaky titanate dispersion liquid among sieves, that is, the flaky titanate dispersion liquid classified through an opening size of 20 m or more and 45 m or less was centrifuged at 10,000 rpm for 10 minutes to give a flaky titanate cake. Next, pure water was added to the flaky titanate cake, and a slurry having a solid content of 8% was prepared. The slurry was spray-dried using a spray dryer (L-8i manufactured by Ohkawara Kakohki Co., Ltd.) under conditions of an inlet temperature of 190 C. and an outlet temperature of 85 C., thereby giving a flaky titanate powder.

Example 2

[0155] A flaky titanate dispersion liquid, a flaky titanate dispersion liquid among sieves, a flaky titanate cake, and a flaky titanate powder were obtained in the same manner as in Example 1, except that the amount of 90% aqueous solution of 2-amino-2-methyl-1-propanol added in Example 1 was changed to 10.7 g per 100 g of TiO.sub.2 (which corresponds to 0.15 neutralization equivalents relative to hydrogen ions included in the layered titanate).

Example 3

[0156] Ion-exchange was performed in the same manner as in Example 1, except that the amount of 1.1-N aqueous sulfuric acid solution used for ion exchange was adjusted, thereby giving a layered titanate cake. The potassium amount included in the layered titanate cake was analyzed with a X-ray fluorescence spectrometer (RIX2100 manufactured by Rigaku). The result was 3.3% as K.sub.2O/TiO.sub.2.

[0157] The obtained layered titanate cake was redispersed in pure water to 8.5% in terms of TiO2 conversion to give a layered titanate dispersion liquid. The layered titanate dispersion liquid and aqueous ammonia were mixed to adjust the pH to 8.7. Subsequently, per 100 g of TiO.sub.2, 21.4 g of a 90% aqueous solution of 2-amino-2-methyl-1-propanol (which corresponds to 0.3 neutralization equivalents relative to hydrogen ions included in the layered titanate) was added and stirred at room temperature for 1 hour to give a flaky titanate dispersion liquid.

[0158] Next, a mesh having an opening size of 10 m was attached to a slurry screener (SS95250 manufactured by Aco Japan Co., Ltd.), then a solution obtained by diluting the obtained flaky titanate dispersion liquid 2-fold with pure water was allowed to flow at 18 L/hour, thereby performing classification. As a result, the flaky titanate dispersion liquid on the screen and the flaky titanate dispersion liquid under the screen were each recovered.

[0159] The flaky titanate dispersion liquid on the screen was diluted 3-fold with pure water, and separated into a precipitate and a supernatant using a centrifuge (SJ10F manufactured by Mitsubishi Kakoki Kaisha, Ltd.). The sediment resulting from centrifugation (flaky titanate cake) was spray-dried using a spray dryer (L-8i manufactured by Ohkawara Kakohki Co., Ltd.) under conditions of an inlet temperature of 190 C. and an outlet temperature of 85 C., thereby giving a flaky titanate powder.

Comparative Example 1

[0160] The flaky titanate dispersion liquid obtained in Example 1 was subjected to centrifugation, slurry preparation, and spray drying in the same manner as in Example 1 except that the classification operation was not performed, thereby giving a flaky titanate cake and a flaky titanate powder.

Comparative Example 2

[0161] The flaky titanate dispersion liquid obtained in Example 2 was subjected to centrifugation, slurry preparation, and spray drying in the same manner as in Example 2 except that the classification operation was not performed, thereby giving a flaky titanate cake and a flaky titanate powder.

Comparative Example 3

[0162] A flaky titanate dispersion liquid was obtained in the same manner as in Example 1, except that the calcination temperature at the time of synthesizing lithium potassium titanate was changed to 1,100 C., and, as a delaminating agent, 3.5 g of n-propylamine was used per 100 g of TiO.sub.2 (which corresponds to 0.08 neutralization equivalents relative to hydrogen ions included in the layered titanate). The flaky titanate dispersion liquid was centrifuged at 10,000 for 10 minutes, and its solid content was recovered, thereby giving a flaky titanate cake.

Measurement of Particle Size Distribution

[0163] The particle size distribution of the flaky titanate in the flaky titanate dispersion liquid was measured by using a laser diffraction/scattering particle size distribution analyzer (LA-950 manufactured by HORIBA, Ltd.). The refractive index was set at 2.50. In Examples I and 2, the flaky titanate dispersion liquids among sieves after classification were used for measurement, while in Example 3, the flaky titanate dispersion liquid on the screen after classification was used.

Measurements of Carbon Amount and Nitrogen Amount

[0164] The flaky titanate cake was dried at 150 C. for 16 hours, and the carbon amount and the nitrogen amount of the resulting sample were analyzed using an elemental analyzer (Vario EL III manufactured by Elementar).

Preparation of Paint 1

[0165] 1.25 g of each of the flaky titanate powders obtained in Examples 1 and 2 and Comparative Examples 1 and 2, 11.9 g of an acrylic silicone resin blend (solid content: 42%) according to the blending ratio of Table 1, and 9.40 g of pure water were placed in a glass vessel and mixed in a paint shaker for 5 minutes, thereby preparing a paint. With respect to the flaky titanate cake obtained in Comparative Example 3, 1.25 g of the cake in terms of its solid content conversion was weighed, and then 11.9 g of an acrylic silicone resin blend (solid content: 42%) according to the blending ratio of Table 1 and 9.40 g of pure water (including moisture included in the flaky titanate cake) were placed in a glass vessel and mixed in a paint shaker for 5 minutes, thereby preparing a paint. The solid content of the flaky titanate cake was calculated from mass changes before and after drying at 150 C. for 16 hours.

Preparation of Paint 2

[0166] 5.0 g of each of the flaky titanate powders obtained in Examples 1, 2, and 3 and Comparative Examples 1 and 2 and 11.9 g of an acrylic silicone resin blend (solid content: 42%) according to the blending ratio of Table 1 were placed in a glass vessel and mixed in a paint shaker for 5 minutes, and then pure water was added to make the paint viscosity 200 mPa.Math.s, thereby preparing a paint. With respect to the flaky titanate cake obtained in Comparative Example 3, 5.0 g of the cake in terms of a solid content conversion was weighed, and then 11.9 g of an acrylic silicone resin blend (solid content: 42%) according to the blending ratio of Table 1 was placed in a glass vessel and mixed in a paint shaker for 5 minutes, and pure water was added to make the paint viscosity 200 mPa.Math.s, thereby preparing a paint. The solid content of the flaky titanate cake was calculated from mass changes before and after drying at 150 C. for 16 hours.

TABLE-US-00001 TABLE 1 Blending Ratio Material Product Name (part by mass) Acrylic silicone Pegar 896 (manufactured by 76 resin Koatsu Gas Kogyo Co., Ltd.) Film-forming aid Texanol (manufactured by 2.9 Eastman Chemical Co.) Defoamer BYK-024 (manufactured by 0.25 BYK-Chemie GmbH) Urethane associative SN Thickener 619N 0.20 thickener (manufactured by Sannopuko, K.K.) Alkali thickener Primal ASE-60 (manufactured 0.25 by Dow Chemical Co.) Water 18.5

Preparation of Paint Film for Luster Evaluation 1

[0167] A paint prepared by the method of Preparation of Paint 1 described above was applied onto a PET film (Lumirror T60 manufactured by Toray Industries, Inc.) using a 3 mil doctor blade and forcedly dried at 60 C. for 30 minutes, thereby preparing a paint film for luster evaluation. In addition, paint films using commercially available pearl mica (Iriodin 6103 or Iriodin 6111 manufactured by Merck) as a luster pigment were also prepared according to the same formulation. Each of them was defined as Reference Examples 1 and 2, and used as evaluation standards for the 3-grade visual evaluation of luster feeling, dense feeling, and particle feeling described below.

Preparation of Paint Film for Luster Evaluation 2

[0168] A paint prepared by the method of Preparation of Paint 2 described above was applied onto a PET film (Lumirror T60 manufactured by Toray Industries, Inc.) using a spray gun and forcedly dried at 60 C. for 30 minutes, thereby preparing a paint film having a film thickness of 10 m.

Evaluation of Shading Feeling 1

[0169] The black ground of a black-and-white chart was applied to the back side of a paint film prepared by the method of Preparation of Paint Film for Luster Evaluation 1 described above. By using a goniospectrophotometric color measurement system (Model GCMS-3 manufactured by Murakami Color Research Laboratory Co., Ltd.), a light source was irradiated from a direction of 45 , and the L* values of the highlights (light-receiving angle 40 and light-receiving angle 50) and the shade (light-receiving angle 65) were measured. The L* of the shade was subtracted from the maximum highlight L* to calculate L*.sub.1, and the shading feeling was evaluated.

Evaluation of Shading Feeling 2

[0170] The white ground of a black-and-white chart was applied to the back side of a paint film prepared by the method of Preparation of Paint Film for Luster Evaluation 2 described above. By using a multi-angle colorimeter (BYK-mac i manufactured by BYK-Gardner), a light source was irradiated from a direction of 45, and the L* values of the highlight (light-receiving angle 30) and the shade (light-receiving angle 65) were measured. The L* of the shade was subtracted from the L* of the highlight to calculate L*.sub.2, and the shading feeling was evaluated.

Evaluation of Luster Feeling

[0171] The luster feeling of the prepared paint film was visually evaluated. The luster feeling is an index that indicates the degree of metallic brightness that a paint film has, and was scored on a 3-grade scale from 1 (high) to 3 (low).

Evaluation of Silky Feeling (Dense Feeling, Particle Feeling)

[0172] The silky feeling of the prepared paint film was visually evaluated. As silky feeling indexes, two of dense feeling and particle feeling were employed. The dense feeling refers to a silk-like seamless and smooth design, and was scored on a 3-grade scale from 1 (high) to 3 (low). The particle feeling refers to a design that appears as if each of the particles independently glitters, and was scored on a 3-grade scale in which a case giving no particle feeling is evaluated as 1 and a case giving strong glittering feeling as 3.

Measurement of Particle Thickness

[0173] A paint film prepared for luster evaluation was cut with a microtome, and the cross-section was observed under a scanning electron microscope (S-4800 manufactured by Hitachi High-Technologies Corporation). The thicknesses of 50 flaky titanate particles observed were measured, and their average was defined as the thickness of flaky titanate particles.

Preparation of Paint Film for Weather Resistance Evaluation

[0174] The above paint was applied onto a dull steel plate using a bar coater No. 60 and forcedly dried at 60 C. for 30 minutes to form a luster paint film. Next, a commercially available base compound and curing agent for a two-pack curable urethane resin paint were mixed to prepare a topcoat paint. The paint was applied onto the above luster paint film using a bar coater No. 60, forcedly dried at 80 C. for 30 minutes to form a topcoat, thereby giving a paint film for weather resistance evaluation.

Evaluation of Weather Resistance

[0175] The L-, a-, and b-values on Hunter colorimetric system of a paint film were measured using a spectrophotometer (SD 5000 manufactured by Nippon Denshoku Industries Co., Ltd.). The weather resistance of a paint film was evaluated through an accelerated exposure test. The test was performed using a sunshine weather meter (Model WEL-SUN-HC manufactured by Suga Test Instruments Co., Ltd.) under the following conditions: black panel temperature of 633 C.; light source of carbon arc lamp; and shower spraying of 12 minutes out of 1 hour. The L-, a-, and b-values were measured every certain period of time by the same method as above. From the L-, a-, and b-values after 300 hours from the accelerated exposure and the L-, a-, and b-values before the accelerated exposure test, a color difference E was calculated. Calculation was performed as follows: E=[(L).sup.2+(a).sup.2+(b).sup.2].sup.(1/2).

Analysis of Cs Content

[0176] A flaky titanate powder was analyzed using a X-ray fluorescence spectrometer (RIX2100 manufactured by Rigaku Co.) to determine the Cs content.

[0177] The particle size distribution measurement results of the examples and the comparative examples are shown in Table 2. The results of the evaluation of L*.sub.1 (and L*.sub.2), luster feeling, and silky feeling are shown in Table 3. The thickness of the flaky titanate particles of Example 1 was 0.1 m, the thickness of the flaky titanate particles of Comparative Example 1 was 0.1 m, and the thickness of the flaky titanate particles of Comparative Example 3 was 0.7 m. The Cs amount of the flaky titanate powder obtained in Example 1 was the detection limit (0.01 mass %) or less.

TABLE-US-00002 TABLE 2 D10 D50 D90 D99 (m) (m) (m) (D90 D10)/D50 (m) Example 1 12.8 26.7 52.5 1.49 76.7 Example 2 13.6 25.4 43.9 1.19 69.1 Example 3 15.7 33.0 61.0 1.38 100.4 Comparative 16.6 38.0 76.2 1.57 137 Example 1 Comparative 18.2 43.5 86.7 1.57 151 Example 2 Comparative 10.5 20.0 43.5 1.65 77.1 Example 3

TABLE-US-00003 TABLE 3 Silky feeling Luster Dense Particle L*.sub.1 L*.sub.2 feeling feeling feeling Example 1 172 69 1 1 1 Example 2 170 64 1 1 1 Example 3 66 1 1 1 Comparative 175 73 1 2 2 Example 1 Comparative 175 69 1 3 3 Example 2 Comparative 126 30 3 3 1 Example 3 Reference 166 54 1 3 3 Example 1 Reference 130 31 3 1 1 Example 2

[0178] The samples of Examples 1 and 2 and Comparative Examples 1 and 2 all have a L*.sub.1 of 150 or more (L*.sub.2 of 60 or more) and have a shading feeling and a luster feeling. However, the silky feeling was more excellent in Examples 1 to 3 where (D90D10)/D50 was adjusted to 1.5 or less by a classification operation than in Comparative Examples 1 and 2. In Comparative Example 3, L*.sub.1 (and L*.sub.2) was low, and both the shading feeling and the luster feeling were poor. In addition, as a result of visual observation, its silky feeling was lowest. As shown in the reference examples, there is no commercially available pearl mica capable of achieving both a luster feeling and a silky feeling. However, it can be seen that the flaky titanates of Examples 1 to 3 each exhibit a unique design feeling that has a high dense feeling and almost no particle feeling, while having a luster feeling and a shading feeling.

[0179] Table 4 shows the carbon amount, basic functional group content, nitrogen amount, and weather resistance (E) of each sample. The basic functional group content (%) in Example 1 using 2-amino-2-methyl-1-propanol as a delaminating agent was calculated according to the following general formula: (the number of basic functional groups per one molecule of the basic organic compound)(carbon amount (mass %))/{(atomic weight of carbonthe number of carbon atoms per one compound)/(formula weight of TiO.sub.2)}, and thus was calculated as 1(0.910)/{(12.04)/79.9}=1.51%. The basic functional group content (%) in Comparative Example 3 using n-propylamine as a delaminating agent was calculated according to the following general formula: (the number of basic functional groups per one molecule of the basic organic compound) x ((carbon amount (mass %))/(atomic weight of carbonthe number of carbon atoms per one compound) /(formula weight of TiO.sub.2), and thus was calculated as 1(1.11)/{(12.03)/79.9}=2.46%.

TABLE-US-00004 TABLE 4 Carbon Basic functional Nitrogen amount (%) group content (%) amount (%) E Example 1 0.910 1.51 3.34 1.03 Example 2 0.775 1.29 3.64 1.06 Example 3 1.22 2.04 2.69 1.00 Comparative 3.42 5.69 3.50 1.55 Example 1 Comparative 3.47 5.78 3.29 1.56 Example 2 Comparative 1.11 2.46 3.38 1.57 Example 3

[0180] In Examples 1 to 3, the basic functional group content was reduced to 2.4% or less as a result of the classification operation, E was lower as compared with the comparative examples, and the weather resistance was improved. In all the comparative examples, the basic functional group content was more than 2.4%, and the weather resistance was insufficient.

INDUSTRIAL APPLICABILITY

[0181] The present invention can provide a flaky titanate that is capable of giving a silky feeling with a strong luster feeling and a shading feeling to a paint film and at the same time exhibits high weather resistance; and a method for producing the same, which is inexpensive and suitable for industrial production. In addition, the present invention can give an even higher silky feeling with a further increased dense feeling and a reduced particle feeling to a paint film. Therefore, the flaky titanate of the present invention is suitable as a luster pigment, and can be used as one blended in a paint composition, an ink composition, a plastic resin composition, or the like. As a result, an article having a unique design feeling unavailable so far can be put to practical use.