LIQUID DISPERSION OF FLUORIDE PARTICLES, COMPOSITION FOR FORMING OPTICAL FILM, AND OPTICAL FILM

Abstract

Provided are a liquid dispersion of fluoride particles having a refractive index lower than that of, for example, magnesium fluoride, the liquid dispersion being excellent in dispersibility and suitable for production of an optical film such as an antireflection film; a composition for forming an optical film; and an optical film. A liquid dispersion of fluoride particles according to the present invention contains: fluoride particles; an anionic surfactant as a dispersant for the fluoride particles; and an organic solvent, wherein the fluoride particles contain at least aluminum, an alkali metal, and an alkaline earth metal as an optional element in a composition of the fluoride particles, and the fluoride particles are dispersed in the organic solvent.

Claims

1. A liquid dispersion of fluoride particles, the liquid dispersion comprising: fluoride particles; an anionic surfactant as a dispersant for the fluoride particles; and an organic solvent, wherein the fluoride particles contain at least aluminum, an alkali metal, and an alkaline earth metal as an optional element in a composition of the fluoride particles, and the fluoride particles are dispersed in the organic solvent.

2. The liquid dispersion of fluoride particles according to claim 1, wherein a counter ion of a hydrophilic group in the anionic surfactant is a proton or an onium ion.

3. The liquid dispersion of fluoride particles according to claim 1 wherein the anionic surfactant is at least one of an anionic hydrocarbon surfactant and an anionic fluorocarbon surfactant represented by a following Chemical Formula (1): ##STR00004## wherein R represents an alkyl group having 2 to 18 carbon atoms, an aryl group having 2 to 18 carbon atoms, a polyoxyalkylene alkyl ether group having 2 to 18 carbon atoms, an alkyl group having 2 to 18 carbon atoms in which at least one hydrogen atom is substituted with a fluorine atom, an aryl group having 2 to 18 carbon atoms in which at least one hydrogen atom is substituted with a fluorine atom, or a polyoxyalkylene alkyl ether group having 2 to 18 carbon atoms in which at least one hydrogen atom is substituted with a fluorine atom, X represents COO.sup.?, PO.sub.4.sup.?, SO.sub.3.sup.?, or SO.sub.4.sup.?, and M represents a proton or an onium ion.

4. The liquid dispersion of fluoride particles according to claim 1, wherein a content of the anionic surfactant is in a range of 0.2 mass % to 8 mass % with respect to 100 mass % of the fluoride particles.

5. The liquid dispersion of fluoride particles according to claim 1, wherein the fluoride particles are particles of at least one fluoride selected from a group consisting of Na.sub.3AlF.sub.6, Na.sub.5Al.sub.3F.sub.14, Na.sub.3Li.sub.3Al.sub.2F.sub.12, Na.sub.2MgAlF.sub.7, K.sub.2NaAlF.sub.6, LiCaAlF.sub.6, and LiSrAlF.sub.6.

6. The liquid dispersion of fluoride particles according to claim 1, wherein a moisture concentration in the liquid dispersion of fluoride particles is 1.5 mass % or less with respect to 100 mass % of the liquid dispersion of fluoride particles.

7. The liquid dispersion of fluoride particles according to claim 1, wherein the organic solvent is at least one of an alcohol solvent, a ketone solvent, and an ether solvent.

8. The liquid dispersion of fluoride particles according to claim 1, wherein an average dispersed particle size of the fluoride particles is in a range of 1 nm to 100 nm.

9. The liquid dispersion of fluoride particles according to claim 1, wherein a content of the fluoride particles is in a range of 1 mass % to 30 mass % with respect to 100 mass % of the liquid dispersion of fluoride particles.

10. The liquid dispersion of fluoride particles according to claim 1, wherein an Rsp value of the liquid dispersion of fluoride particles as measured by pulse NMR is 5 or more.

11. A composition for forming an optical film, comprising the liquid dispersion of fluoride particles according to claim 1.

12. An optical film comprising a cured film of the composition for forming an optical film according to claim 11.

Description

EXAMPLES

[0101] Suitable Examples of the present invention will be described in detail below. However, materials or mixing amounts mentioned in these Examples do not purport to limit the scope of the present invention only to these unless there is a definitive description.

(Measurement Method of Average Particle Size)

[0102] Using a particle size distribution measuring instrument (Microtrac, Nanotrac UPA, UPA-UZ152, manufactured by MicrotracBEL Corp.), the average particle size of fluoride particles in the liquid dispersion was measured. It is noted that the average particle size (d50) is a particle size defined by the fact that particles having an average dispersion particle size or less accounts for 50% by volume of the entire sample particles. [0103] Measurement principle: dynamic light scattering frequency analysis (FFT-heterodyne method). [0104] Light source: 3 mW, two semiconductor lasers of 780 nm [0105] Set temperature range: 10? C. to 80? C. [0106] Particle size distribution measuring range: 0.8 nm to 6.5406 ?m [0107] Measurement target: colloidal particles

[0108] Unless otherwise specified, each average particle size in Examples and Comparative Examples means a volume-equivalent average particle size measured by the above dynamic light scattering method.

(Moisture Measurement Method)

[0109] The moisture concentration in the liquid dispersion of fluoride particles was measured by the Karl Fischer method. A TQV-2200S (trade name) manufactured by Hiranuma Sangyo Co., Ltd. was used as the moisture measuring device. The measurement method was the volumetric titration method based on JIS K 0068 (2001).

(Viscosity Measuring Method)

[0110] The viscosity of the liquid dispersion of fluoride particles was measured using a B-type viscometer. As the B-type viscometer, a DV-I PRIME (trade name) manufactured by Brookfield, USA was used. The measurement was performed based on JIS K 5600-2-2 (2004).

(Method for Measuring Solvent Affinity)

[0111] An index (Rsp value) of the solvent affinity of the liquid dispersion of fluoride particles was calculated by pulse NMR. The Rsp value was measured using Spinsolve 60 ULTRA Phosphorus manufactured by Magritek as a measuring apparatus, by NMR (measurement nucleus: 1H) and the CPMG (Carr-Purcell-Meiboom-Gill sequence) method. The Rsp value was calculated by the following Formula (1).

[00001]$\begin{array}{cc}\mathrm{Rsp}=\left(\mathrm{Rav}-\mathrm{Rb}\right)/\left(\mathrm{Rb}\right)& \left(1\right)\end{array}$

[0112] wherein Rsp is an index indicating solvent affinity, Rav is a reciprocal of a relaxation time of a liquid dispersion of fluoride particles, and Rb is a reciprocal of a relaxation time of a blank solvent excluding fluoride particles in the liquid dispersion of fluoride particles.

Example 1

[0113] In a fluororesin container, 1,600 g of propylene glycol monomethyl ether (PGME, reagent) and 80 g of Na.sub.3AlF.sub.6 particles (manufactured by Stella Chemifa Corporation) were mixed to prepare a slurry containing aggregated Na.sub.3AlF.sub.6 particles. This slurry was charged into a bead mill (manufactured by Nippon Coke & Engineering Co., Ltd.) and subjected to dispersion treatment. After the slurry was charged, a portion where the slurry was exposed to the outside air was set to a nitrogen atmosphere. As the beads, zirconia beads (manufactured by Nikkato Corporation) were used. During the dispersion treatment, the liquid dispersion was sampled at regular time intervals and the particle size distribution of the sample was measured. The dispersion treatment was performed until the average particle size (volume-based average particle size, d 50) of Na.sub.3AlF.sub.6 particles decreased and the decrease was stopped, thereby obtaining 1,000 g of a mixed solution containing Na.sub.3AlF.sub.6 particles. Thereafter, 1 g of PLYSURF A212C (trade name, manufactured by DKS Co. Ltd.) as a dispersant was added to the mixed solution, and ultrasonic treatment was performed for 1 minute. As a result, a liquid dispersion of Na.sub.3AlF.sub.6 particles in which the content of Na.sub.3AlF.sub.6 particles was 5 mass % with respect to the total mass of the liquid dispersion, and the content of PLYSURF A212C as a dispersant was 2 mass % with respect to 100 mass % of Na.sub.3AlF.sub.6 particles was obtained. The physical property values of the obtained liquid dispersion are shown in Table 1.

Example 2

[0114] In the present example, the addition amount of PLYSURF A212C as a dispersant was changed to 2 g (4 mass % with respect to 100 mass % of Na.sub.3AlF.sub.6 particles). A liquid dispersion according to the present example was prepared in the same manner as in Example 1 except for the above-described difference. The physical property values of the obtained liquid dispersion are shown in Table 1.

Example 3

[0115] In the present example, NEOPELEX GS (trade name, manufactured by Kao Corporation) was used as a dispersant instead of PLYSURF A212C. A liquid dispersion according to the present example was prepared in the same manner as in Example 1 except for the above-described difference. The physical property values of the obtained liquid dispersion are shown in Table 1.

Example 4

[0116] In the present example, 7H-dodecafluoroheptanoic acid was used as a dispersant instead of PLYSURF A212C. In addition, the addition amount of 7H-dodecafluoroheptanoic acid was also changed to 0.1 g (0.2 mass % with respect to 100 mass % of Na.sub.3AlF.sub.6 particles) with respect to 1,000 g of the liquid dispersion. A liquid dispersion according to the present example was prepared in the same manner as in Example 1 except for the above-described differences. The physical property values of the obtained liquid dispersion are shown in Table 1.

Example 5

[0117] In the present example, heptanoic acid was used as a dispersant instead of PLYSURF A212C. In addition, the addition amount of heptanoic acid was also changed to 0.1 g (0.2 mass % with respect to 100 mass % of Na.sub.3AlF.sub.6 particles) with respect to 1,000 g of the liquid dispersion. A liquid dispersion according to the present example was prepared in the same manner as in Example 1 except for the above-described differences. The physical property values of the obtained liquid dispersion are shown in Table 1.

Example 6

[0118] In the present example, the preparation conditions of the slurry were changed so that the content of Na.sub.3AlF.sub.6 particles was 1 mass % with respect to the total mass of the liquid dispersion. A liquid dispersion according to the present example was prepared in the same manner as in Example 1 except for the above-described difference. The physical property values of the obtained liquid dispersion are shown in Table 1.

Example 7

[0119] In the present example, the preparation conditions of the slurry were changed so that the content of Na.sub.3AlF.sub.6 particles was 30 mass % with respect to the total mass of the liquid dispersion. A liquid dispersion according to the present example was prepared in the same manner as in Example 1 except for the above-described difference. The physical property values of the obtained liquid dispersion are shown in Table 1.

Example 8

[0120] In the present example, Na.sub.5Al.sub.3F.sub.14 was used instead of Na.sub.3AlF.sub.6 particles. A liquid dispersion according to the present example was prepared in the same manner as in Example 1 except for the above-described difference. The physical property values of the obtained liquid dispersion are shown in Table 1.

Example 9

[0121] In the present example, LiCaAlF.sub.6 was used instead of Na.sub.3AlF.sub.6 particles. A liquid dispersion according to the present example was prepared in the same manner as in Example 1 except for the above-described difference. The physical property values of the obtained liquid dispersion are shown in Table 1.

Example 10

[0122] In the present example, 2-propanol (IPA, reagent) was used as a dispersion solvent instead of PGME. A liquid dispersion according to the present example was prepared in the same manner as in Example 1 except for the above-described difference. The physical property values of the obtained liquid dispersion are shown in Table 1.

Example 11

[0123] In the present example, methyl ethyl ketone (MEK, reagent) was used as a dispersion solvent instead of PGME. In addition, 7H-dodecafluoroheptanoic acid was used as a dispersant instead of PLYSURF A212C. A liquid dispersion according to the present example was prepared in the same manner as in Example 1 except for the above-described differences. The physical property values of the obtained liquid dispersion are shown in Table 1.

Comparative Example 1

[0124] In the present comparative example, Noigen (registered trademark, manufactured by DKS Co. Ltd.) as a nonionic surfactant was used as a dispersant. A liquid dispersion according to the present comparative example was prepared in the same manner as in Example 1 except for the above-described difference. The physical property values of the obtained liquid dispersion are shown in Table 1.

Comparative Example 2

[0125] In the present comparative example, Ftergent (registered trademark) 310 (manufactured by NEOS Co. Ltd.) as a nonionic surfactant was used as a dispersant. A liquid dispersion according to the present comparative example was prepared in the same manner as in Example 1 except for the above-described difference. The physical property values of the obtained liquid dispersion are shown in Table 1.

Comparative Example 3

[0126] In the present comparative example, a liquid dispersion according to the present comparative example was prepared in the same manner as in Example 1 except that no dispersant was used. The physical property values of the obtained liquid dispersion are shown in Table 1.

Comparative Example 4

[0127] In the present comparative example, magnesium fluoride particles (manufactured by Stella Chemifa Corporation) were used as fluoride particles instead of Na.sub.3AlF.sub.6 particles. In addition, no dispersant was used. A liquid dispersion according to the present comparative example was prepared in the same manner as in Example 1 except for the above-described differences. The physical property values of the obtained liquid dispersion are shown in Table 1.

TABLE-US-00001 TABLE 1 Content of Average fluoride Content of Moisture dispersed Fluoride Organic particles dispersant concentration particle Rsp Viscosity particles solvent Dispersant (mass %) (mass %) (mass %) size (nm) value (mPa .Math. s) Example 1 Na.sub.3AlF.sub.6 PGME PLYSURF A212C 5 2 0.5 12 11.9 3.4 Example 2 Na.sub.3AlF.sub.6 PGME PLYSURF A212C 5 4 0.4 9.4 12.5 3.2 Example 3 Na.sub.3AlF.sub.6 PGME NEOPELEX GS 5 2 0.8 9.3 8.5 3.6 Example 4 Na.sub.3AlF.sub.6 PGME 7H- 5 0.2 0.5 52 5.4 4.8 Dodecafluoroheptanoic acid Example 5 Na.sub.3AlF.sub.6 PGME Heptanoic acid 5 0.2 0.5 15 5.8 4.0 Example 6 Na.sub.3AlF.sub.6 PGME PLYSURF A212C 1 2 0.3 10 11.5 2.3 Example 7 Na.sub.3AlF.sub.6 PGME PLYSURF A212C 30 2 0.8 14 12.3 15.5 Example 8 Na.sub.5Al.sub.3F.sub.14 PGME PLYSURF A212C 5 2 0.5 20 10.8 3.8 Example 9 LiCaAlF.sub.6 PGME PLYSURF A212C 5 2 0.4 25 11.2 3.5 Example 10 Na.sub.3AlF.sub.6 IPA PLYSURF A212C 5 2 0.5 21 14.5 4.0 Example 11 Na.sub.3AlF.sub.6 MEK 7H- 5 2 0.4 81 6.3 2.2 Dodecafluoroheptanoic acid Comparative Na.sub.3AlF.sub.6 PGME Noigen XL-40 5 2 0.6 120 3.2 4.6 Example 1 Comparative Na.sub.3AlF.sub.6 PGME Ftergent 310 5 2 0.6 325 2.8 4.0 Example 2 Comparative Na.sub.3AlF.sub.6 PGME None 5 0.4 360 3.8 5.0 Example 3 Comparative MgF.sub.2 PGME None 10 0.8 13 22.1 10.8 Example 4

Example 12

[0128] First, 27.5 g of the liquid dispersion prepared in Example 1 and 1.2 g of a commercially available acrylate coating material (acrylic resin) were mixed. Further, 0.6 g of 1-hydroxycyclohexyl phenyl ketone (photopolymerization initiator) was dissolved in the mixed solution to obtain a composition for forming an optical film. Next, 10 g of the composition for forming an optical film was diluted with 10.9 g of propylene glycol monomethyl ether to prepare a low refractive index coating material.

[0129] One surface of a PET film (Lumirror (registered trademark) U34 manufactured by Toray Industries, Inc., thickness: 100 ?m) was coated with 300 ?l of the diluted low refractive index coating material by spin coating. The coating film was dried at 130? C., and then irradiated with ultraviolet rays at 400 mJ/cm.sup.2 to be photocured, and thus an antireflection film (low refractive index layer, optical film) was layered on the PET film.

Example 13

[0130] In the present example, the liquid dispersion prepared in Example 2 was used instead of the liquid dispersion prepared in Example 1. An antireflection film according to the present example was layered in the same manner as in Example 12 except for the above-described difference.

Example 14

[0131] In the present example, the liquid dispersion prepared in Example 3 was used instead of the liquid dispersion prepared in Example 1. An antireflection film according to the present example was layered in the same manner as in Example 12 except for the above-described difference.

Example 15

[0132] In the present example, the liquid dispersion prepared in Example 4 was used instead of the liquid dispersion prepared in Example 1. An antireflection film according to the present example was layered in the same manner as in Example 12 except for the above-described difference.

Example 16

[0133] In the present example, the liquid dispersion prepared in Example 5 was used instead of the liquid dispersion prepared in Example 1. An antireflection film according to the present example was layered in the same manner as in Example 12 except for the above-described difference.

Example 17

[0134] In the present example, the liquid dispersion prepared in Example 6 was used instead of the liquid dispersion prepared in Example 1. An antireflection film according to the present example was layered in the same manner as in Example 12 except for the above-described difference.

Example 18

[0135] In the present example, the liquid dispersion prepared in Example 7 was used instead of the liquid dispersion prepared in Example 1. An antireflection film according to the present example was layered in the same manner as in Example 12 except for the above-described difference.

Example 19

[0136] In the present example, the liquid dispersion prepared in Example 8 was used instead of the liquid dispersion prepared in Example 1. An antireflection film according to the present example was layered in the same manner as in Example 12 except for the above-described difference.

Example 20

[0137] In the present example, the liquid dispersion prepared in Example 9 was used instead of the liquid dispersion prepared in Example 1. An antireflection film according to the present example was layered in the same manner as in Example 12 except for the above-described difference.

Example 21

[0138] In the present example, the liquid dispersion prepared in Example 10 was used instead of the liquid dispersion prepared in Example 1. An antireflection film according to the present example was layered in the same manner as in Example 12 except for the above-described difference.

Example 22

[0139] In the present example, the liquid dispersion prepared in Example 11 was used instead of the liquid dispersion prepared in Example 1. An antireflection film according to the present example was layered in the same manner as in Example 12 except for the above-described difference.

Comparative Example 5

[0140] In the present example, the liquid dispersion prepared in Comparative Example 1 was used instead of the liquid dispersion prepared in Example 1. An antireflection film according to the present comparative example was layered in the same manner as in Example 12 except for the above-described difference.

Comparative Example 6

[0141] In the present example, the liquid dispersion prepared in Comparative Example 2 was used instead of the liquid dispersion prepared in Example 1. An antireflection film according to the present comparative example was layered in the same manner as in Example 12 except for the above-described difference.

Comparative Example 7

[0142] In the present example, the liquid dispersion prepared in Comparative Example 3 was used instead of the liquid dispersion prepared in Example 1. An antireflection film according to the present comparative example was layered in the same manner as in Example 12 except for the above-described difference.

Comparative Example 8

[0143] In the present example, the liquid dispersion prepared in Comparative Example 4 was used instead of the liquid dispersion prepared in Example 1. An antireflection film according to the present comparative example was layered in the same manner as in Example 12 except for the above-described difference.

(Haze Measurement and Minimum Light Reflectance Measurement)

[0144] Using an ultraviolet-visible near-infrared spectrophotometer (trade name: V670, manufactured by JASCO Corporation), the haze value of the antireflection film (low reflectance layer), and the minimum light reflectance of the antireflection film (low refractive index layer) were measured in accordance with JIS K 7136.

[0145] The physical properties of the antireflection films according to Examples 12 to 22 and Comparative Examples 5 to 8 are shown in Table 2. In the antireflection film of Comparative Example 8, the light transmittance of the antireflection film was high, and the haze value was equivalent to that of a single PET film. Therefore, each numerical value in Examples 12 to 22 and Comparative Examples 5 to 7 in Table 2 indicates a relative value with respect to a reference value with the optical characteristics of the antireflection film of Comparative Example 8 as 100 (reference value). Regarding the haze and the minimum light reflectance in Table 2, a smaller numerical value indicates better optical characteristics of the antireflection film.

TABLE-US-00002 TABLE 2 Concentration (vol %) of fluoride Minimum particles contained light Liquid dispersion in antireflection film Haze reflectance Example 12 Liquid dispersion 50 100 75 of Example 1 Example 13 Liquid dispersion 50 100 87 of Example 2 Example 14 Liquid dispersion 50 100 91 of Example 3 Example 15 Liquid dispersion 50 100 66 of Example 4 Example 16 Liquid dispersion 50 100 68 of Example 5 Example 17 Liquid dispersion 50 100 75 of Example 6 Example 18 Liquid dispersion 50 100 72 of Example of 7 Example 19 Liquid dispersion 50 100 80 of Example 8 Example 20 Liquid dispersion 50 100 92 of Example 9 Example 21 Liquid dispersion 50 100 72 of Example 10 Example 22 Liquid dispersion 50 100 78 of Example 11 Comparative Liquid dispersion 50 158 80 Example 5 of Comparative Example 1 Comparative Liquid dispersion 50 175 72 Example 6 of Comparative Example 2 Comparative Liquid dispersion 50 160 59 Example 7 of Comparative Example 3 Comparative Liquid dispersion 50 100 100 Example 8 of Comparative Example 4