Pigment dispersion, coating film-forming composition, and cured film

Abstract

To provide a pigment dispersion and a coating film-forming composition which are excellent in dispersibility, and to provide a cured film which is excellent in near-infrared shielding properties and has better heat resistance than conventional ones.SOLUTION: There are provided: a pigment dispersion which contains a tin naphthalocyanine pigment, a dispersant, and a solvent, the dispersant being a resin type dispersant having a phosphate group and having an acid value of 1-128 mg KOH / g and an amine value of 0 mg KOH / g; a coating film-forming composition containing the pigment dispersion and a coating film-forming component; and a cured film of the coating film-forming composition.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a pigment dispersion, a composition for forming a coating film, and a cured film, and particularly to a pigment dispersion, a composition for forming a coating film, and a cured film containing a tin naphthalocyanine pigment.

Background Art

[0002] Conventionally, metal naphthalocyanine compounds, particularly tin (Sn) naphthalocyanine dichloride compounds (hereinafter referred to as tin naphthalocyanine pigments), have a large absorption in the near-infrared region and are thus widely used as near-infrared absorbers (for example, Patent Documents 1, 2, etc.).

[0003] Patent Document 1 discloses a tin naphthalocyanine dichloride compound having a flat light absorption waveform in the wavelength region of near-infrared rays of 750 to 950 nm, and a near-infrared absorber using the same.

[0004] Patent Document 2 describes a metal naphthalocyanine pigment (tin naphthalocyanine pigment) containing a tin naphthalocyanine chloride compound having a specific crystal form, a near-infrared absorber containing the pigment, and the like. Such a specific tin naphthalocyanine pigment is described as having high dispersibility.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] By the way, metal naphthalocyanine pigments such as tin naphthalocyanine pigments are generally considered to be difficult to disperse stably.

[0007] Furthermore, coatings containing suzunaphthalocyanine pigments must withstand heating (thermal history) during film formation, and when used as infrared absorbers in sensors, etc., they may be exposed to sunlight, causing their temperature to rise. In other words, high heat resistance as a coating is also required. There is room for improvement here.

[0008] The object of the present invention is to provide a pigment dispersion and a coating film formation composition with excellent dispersibility. Furthermore, it is to provide a cured film with excellent near-infrared shielding properties and better heat resistance than conventional materials. [Means for solving the problem]

[0009] The inventors of the present invention conducted diligent research to solve the aforementioned problems. As a result, they found that the aforementioned problems can be solved by constructing a pigment dispersion using a suzunaphthalocyanine pigment and a specific resin-type dispersant. The gist of the present invention is as follows.

[0010] (1) Contains suzunaphthalocyanine pigment, dispersant and solvent, A pigment dispersion wherein the dispersant is a resin-type dispersant having a phosphate group, an acid value of 1 to 128 mgKOH / g, and an amine value of 0 mgKOH / g. (2) The pigment dispersion according to item (1) above, wherein the dispersant is an acrylic resin-type dispersant whose main skeleton is an acrylic skeleton. (3) A coating film-forming composition comprising the pigment dispersion and coating film-forming component described in item (1) or (2) above. (4) A cured film of the coating film-forming composition described in item (3) above, which is capable of absorbing near-infrared light with a wavelength of 780 to 950 nm. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a pigment dispersion and a coating film formation composition with excellent dispersibility. Furthermore, it is possible to provide a cured film with excellent near-infrared shielding properties and better heat resistance than conventional films.

Brief Description of the Drawings

[0012] [Figure 1] It is a diagram showing the X-ray diffraction spectrum of the tin naphthalocyanine pigment used in Example 1. [Figure 2] It is a diagram showing the transmission spectrum after pre-baking of the coating film produced using the pigment dispersions of Examples 1 to 3. [Figure 3] It is a diagram showing the transmission spectrum after post-baking of the cured films of Examples 1 to 3. [Figure 4] It is a diagram showing the transmission spectrum after ad-baking of the cured films of Examples 1 to 3.

Modes for Carrying Out the Invention

[0013] The pigment dispersion according to an embodiment of the present invention contains a tin naphthalocyanine pigment, a dispersant, and a solvent. And the dispersant is a resin-type dispersant having a phosphate group. The acid value of this resin-type dispersant is 1 to 128 mgKOH / g, and the amine value of this resin-type dispersant is 0 mgKOH / g.

[0014] As the tin naphthalocyanine pigment, those represented by the following formula (1) can be used.

[0015]

Chemical formula

[0016] In formula (1), R1 to R 24 are each independently a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 20 carbon atoms, a substituted or unsubstituted heterocyclic group having 4 to 20 carbon atoms, -O-R 25 or -S-R 26 represents, R 25 and R 26Each of the following independently represents a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 20 carbon atoms, and M represents dichloro or tin dichloride (SnCl2).

[0017] R1 to R in equation (1) 24 It is preferable that R1~R 24 The suzunaphthalocyanine pigment, in which the atoms are hydrogen atoms, is not particularly limited, but examples include those having the crystalline form described in Japanese Patent Application Publication No. 2008-202000, and those having the crystalline form used in Example 1 described later. The suzunaphthalocyanine pigment of the present invention used in Example 1 shows the X-ray diffraction spectrum (XRD chart) shown in Figure 1, and in the X-ray diffraction spectrum, the maximum diffraction peak is shown at a Bragg angle of 2θ (±0.3°) of 6.0°, and further diffraction peaks are found at 11.9°, 13.8°, 14.7°, 16.4°, 17.2°, 26.7°, and 27.2°.

[0018] The average primary particle size of the suzunaphthalocyanine pigment particles is preferably 10 to 40 nm. The primary particle size of the suzunaphthalocyanine pigment can be measured, for example, from an image of the pigment taken with a transmission electron microscope at a magnification of 100,000x. Alternatively, the average primary particle size can be determined by measuring the primary particle size of 100 particles and taking the average value.

[0019] The suzunaphthalocyanine pigment can be micronized. The micronization process may be either wet or dry. For example, the method described in Japanese Patent Publication No. 2008-202000 can be used.

[0020] The content of suzunaphthalocyanine pigment in the pigment dispersion can be 1 to 12% by weight, based on solid content.

[0021] The dispersant may be any resin-type dispersant having a phosphate group, an acid value of 1 to 128 mg KOH / g, and an amine value of 0 mg KOH / g. From the viewpoint of dispersibility, the structure of the resin of the resin-type dispersant is at least one selected from those with an acrylic skeleton, a polyester skeleton, and a polyether skeleton as the main skeleton. Having an acrylic skeleton is preferred.

[0022] The acid value of the dispersant may be 1 to 128 mg KOH / g, but from the viewpoint of dispersibility, 20 to 100 mg KOH / g is preferred, and 30 to 75 mg KOH / g is more preferred. The acid value of the dispersant (acid value when calculated on a solid content basis) can be determined, for example, by a method in accordance with DIN EN ISO 2114. The amine value of the dispersant (amine value when calculated on a solid content basis) can be determined, for example, by a method in accordance with DIN 16945.

[0023] The molecular weight of the resin-type dispersant is not particularly limited; for example, the weight-average molecular weight (M W ) can be adopted if the value is between 3000 and 40000.

[0024] In the pigment dispersion, the dispersant content is preferably 50 to 200 parts by weight, based on solid content, per 100 parts by weight of suzunaphthalocyanine pigment, from the viewpoint of dispersibility.

[0025] Examples of solvents include aromatic, ketone, ester, glycol ether, alcohol, and aliphatic solvents. From the viewpoint of film-forming properties, at least one selected from aromatic, ketone, ester, and glycol ether solvents is preferred, with ester solvents being particularly preferred. Examples of ester solvents include propylene glycol monomethyl ether acetate (PMA or PGMEA). One of these solvents may be used, or two or more may be used in combination.

[0026] In a pigment dispersion, the solvent content is not particularly limited. For example, it can be 70 to 99% by weight in the pigment dispersion.

[0027] The pigment dispersion may contain other additives in addition to the components mentioned above, as needed. Examples of other additives include pigment derivatives, dispersion resins, dyes, pigments other than suzunaphthalocyanine pigments, antioxidants, anti-flocculation agents, and surface modifiers (leveling agents).

[0028] The pigment dispersion can be prepared, for example, by adding the aforementioned components to a known disperser such as a bead mill, sand mill, disperser, or paint conditioner and dispersing them. If necessary, filtration may be performed, or a solvent may be added and the mixture stirred to adjust the pigment concentration.

[0029] The pigment dispersion exhibits good dispersibility. This dispersibility can be evaluated, for example, by checking the viscosity of the pigment dispersion immediately after dispersion treatment and the particle size of the particles contained in the pigment dispersion. Alternatively, dispersion stability can be assessed by checking the degree of change in the viscosity and particle size after storage for a predetermined period under predetermined conditions after dispersion treatment.

[0030] More specifically, the viscosity (initial viscosity A) and particle size (initial particle size X) immediately after dispersion treatment can be measured and evaluated. Alternatively, the viscosity (initial viscosity A) and particle size (initial particle size X) immediately after dispersion treatment, and the viscosity (viscosity after storage B) and particle size (particle size after storage Y) after storage at 40°C for one week after dispersion treatment can be measured and evaluated from the ratio of viscosity B after storage to initial viscosity A (B / A × 100) and the ratio of particle size Y after storage to initial particle size X (Y / X × 100).

[0031] Regarding dispersion stability, a good stability can be evaluated if the change rate of these ratios is 60-120% for the viscosity of the pigment dispersion and 70-140% for the particle size of the particles contained in the pigment dispersion. Viscosity and particle size can be measured, for example, using the measuring apparatus described in the examples below.

[0032] A coating film-forming composition according to an embodiment of the present invention includes the aforementioned pigment dispersion and coating film-forming components. In other words, the coating film-forming composition can also be said to include each component constituting the aforementioned pigment dispersion and the coating film-forming components.

[0033] Examples of film-forming components include polymerizable components, polymers, and mixtures thereof.

[0034] Examples of polymers include thermoplastic urethane resins, (meth)acrylic resins, polyamide resins, polyimide resins, styrene-maleic acid resins, polyester resins, silicone resins, and cardo resins.

[0035] The polymer content in the film-forming composition is preferably 10 to 90% by weight, and more preferably 30 to 70% by weight, of the total solid content of the film-forming composition. If the pigment dispersion contains a dispersion resin, the polymer content in the film-forming composition is the total amount including the dispersion resin. The molecular weight of the polymer can be determined as appropriate. Furthermore, it is preferable that the pigment concentration in the total solid content of the film-forming composition be 3 to 30% by weight.

[0036] Among polymers used as film-forming components, alkali-soluble resins that are soluble in alkaline solutions are preferred. Examples of such alkali-soluble resins include (meth)acrylic polymers described in Japanese Patent Publication No. 2021-191846 and Japanese Patent Publication No. 2009-179789. From the viewpoint of developability, the weight-average molecular weight of the alkali-soluble resin is preferably 5000 to 50000.

[0037] As polymerizable components, photosensitive polymerizable components (photopolymerizable components) are preferred because they can be easily patterned by photolithography or development (negative development). Usable photopolymerizable components include photopolymerizable compounds and photopolymerization initiators. Such photopolymerizable compounds and photopolymerization initiators can be those described in Japanese Patent Application Publication No. 2009-179789. The photopolymerizable compound is preferably contained in an amount of 5 to 70% by weight relative to the total solid content of the coating film-forming composition. These may be used alone or in combination of two or more. The content of the photopolymerization initiator in the coating film-forming composition is preferably 0.1 to 10% by weight relative to the total solid content of the coating film-forming composition.

[0038] Various additives such as sensitizers (sensitizing dyes), chain transfer agents, fluorine-based organic compounds, thermal polymerization initiators, thermal polymerization components, fillers, surfactants, adhesion promoters, antioxidants, anti-coagulation agents, and surface modifiers (leveling agents) may be added to the coating film-forming composition as needed.

[0039] The coating film-forming composition can be obtained by stirring the aforementioned components, for example, using a disperser, shaker, or the like. When using a pigment dispersion, a solvent may be added to adjust the solid content concentration in the coating film-forming composition. The solid content concentration in the coating film-forming composition during stirring can be, for example, 5 to 30% by weight. The resulting mixture may be filtered as needed.

[0040] A cured film of a coating-forming composition can be formed by applying the coating-forming composition to the surface of a desired substrate to a desired thickness using a known apparatus such as spin coating, and then curing the coating-forming component by heating or other means. This cured film is capable of absorbing near-infrared light with a wavelength of 780 to 950 nm. In particular, it has good heat resistance, and for example, even after heating (post-baking) under the conditions described in the examples section below, the absorption of near-infrared light with a wavelength of 780 to 950 nm can remain within the range of practical use. Such a cured film is suitable as a near-infrared absorption filter used in optical filters, solid-state image sensors, image display devices, infrared sensors, etc. [Examples]

[0041] Embodiments of the present invention will be described in more detail below based on examples.

[0042] (Example 1) Pigment used: Suzunaphthalocyanine pigment (manufactured by Sanyo Pigment Co., Ltd., NC502) In equation (1), R1 to R24 are hydrogen atoms, and M is SnCl2. The X-ray diffraction spectrum is shown in Figure 1. As mentioned above, diffraction peaks are present at the specified positions. Composition: 6 parts by weight of tin phthalocyanine pigment (NC502), Resin-type dispersant A (main skeleton: acrylic skeleton, adsorption group to pigment: phosphate group) Solids content: 56.4% by weight; Acid value: 48 mg KOH / g; Amine value: 0 mg KOH / g) 10.6 parts by weight, Solvent (propylene glycol monomethyl ether acetate: PMA or PGMEA) 83.4 parts by weight, A mill base was obtained by blending the following. Next, 400 parts by weight of zirconia beads with a diameter of 0.1 mm were added to 100 parts by weight of the mill base and dispersed with paint conditioner for 60 minutes. After that, the zirconia beads were removed, and PMA was added and stirred so that the concentration of tin phthalocyanine pigment was 5% by weight to obtain the pigment dispersion of Example 1.

[0043] (Example 2) Composition: 6 parts by weight of tin phthalocyanine pigment (NC502), Resin-type dispersant B (main skeleton: polyester skeleton, adsorption group to pigment: phosphate group) Solids content: 100% by weight; Acid value: 50 mg KOH / g; Amine value: 0 mg KOH / g) 6 parts by weight, Solvent (PMA) 88 parts by weight, A mill base was obtained by blending the ingredients. Next, the pigment dispersion of Example 2 was obtained by the same procedure as in Example 1.

[0044] (Example 3) Composition: 6 parts by weight of tin phthalocyanine pigment (NC502), Resin-type dispersant C (main skeleton: polyether skeleton, adsorption group to pigment: phosphate group) Solids content: 50% by weight; Acid value: 48 mg KOH / g; Amine value: 0 mg KOH / g) 12 parts by weight, Solvent (PMA) 82 parts by weight, The mixture was then combined to obtain the mill base. Next, the pigment dispersion of Example 3 was obtained by the same procedure as in Example 1.

[0045] (Comparative Example 1) Composition: 6 parts by weight of tin phthalocyanine pigment (NC502), Resin-type dispersant D (main skeleton: polyester skeleton, adsorption group to pigment: phosphate group) Solids content: 100% by weight; Acid value: 129 mgKOH / g; Amine value: 0 mgKOH / g) 6 parts by weight, Solvent (PMA) 88 parts by weight, A mill base was obtained by blending the following. Next, a dispersion treatment was performed using the same procedure as in Example 1, but gelation occurred and a pigment dispersion could not be obtained. In other words, the composition of Comparative Example 1 resulted in poor dispersion.

[0046] (Comparative Example 2) Composition: 6 parts by weight of tin phthalocyanine pigment (NC502), Resin-type dispersant E (main skeleton: acrylic skeleton, adsorption group to pigment: amino group) Solids content: 45.1% by weight; Acid value: 19 mg KOH / g; Amine value: 29 mg KOH / g) 13.3 parts by weight Solvent (PMA) 80.7 parts by weight, A mill base was obtained by blending the ingredients. Next, a dispersion treatment was performed using the same procedure as in Example 1, but gelation occurred and a pigment dispersion could not be obtained. In other words, the composition of Comparative Example 2 resulted in poor dispersion.

[0047] (Comparative Example 3) Composition: 6 parts by weight of tin phthalocyanine pigment (NC502), Resin-type dispersant F (main skeleton: acrylic skeleton, adsorption group to pigment: carboxyl group) Solids content: 100% by weight; Acid value: 106 mgKOH / g; Amine value: 0 mgKOH / g) 6 parts by weight, Solvent (PMA) 88 parts by weight, A mill base was obtained by blending the ingredients. Next, a dispersion treatment was performed using the same procedure as in Example 1, but gelation occurred and a pigment dispersion could not be obtained. In other words, the composition of Comparative Example 3 resulted in poor dispersion.

[0048] (Rating 1) <Viscosity> The dispersibility of the pigment dispersions obtained in Examples 1-3 was evaluated based on their initial viscosity (A) immediately after preparation, as shown in Table 1. A viscosity (A) of 30 mPa·s or less was considered "good." Furthermore, the viscosity (B) after storage at 40°C for one week was measured, and the rate of change of the viscosity (B) after storage relative to the initial viscosity (A) (dispersion stability) was calculated using the following formula. Viscosity was measured using a TV-22 viscometer manufactured by Toki Sangyo Co., Ltd. Viscosity change rate [%] = (Viscosity after storage B / Initial viscosity A) × 100

[0049] <Particle size> For the pigment dispersions obtained in Examples 1-3, those with an initial particle size (X) of 180 nm or less immediately after preparation were classified as "good." Furthermore, the particle size (Y) was measured after storage at 40°C for one week, and the rate of change in particle size (Y) after storage relative to the initial particle size (X) (dispersion stability) was calculated using the following formula. Particle size measurements were performed using an FPAR-1000 manufactured by Otsuka Electronics Co., Ltd. Percentage change in particle size [%] = (Particle size after storage Y / Initial particle size X) × 100

[0050] The results for evaluation 1 are shown in Table 1.

[0051] [Table 1]

[0052] (Rating 2) <Heat resistance of the coating film> The pigment dispersions obtained in Examples 1-3, the film-forming component (acrylic resin, weight-average molecular weight: 7700, acid value: 115 mg KOH / g, amine value: none, solids content: 37.2% by weight), and the solvent (PMA) were mixed and stirred to prepare a coating solution (the film-forming composition of the present invention). At this time, each component was blended so that the solids content of the coating solution was 12% by weight and the pigment concentration in the coating solution was 25% by weight based on the solids content. Using the coating solutions obtained in Examples 1, 2, and 3, each coating film with a thickness of 1 μm was formed on the surface of a substrate (material: glass) by spin coating. The substrate (coated plate) on which each coating film was formed was dried at room temperature (23°C) for 3 minutes, then heated at 90°C for 2.5 minutes (pre-bake: state shown in Figure 2), and then heated at 230°C for 30 minutes (post-bake: state shown in Figure 3) to produce a cured film on the substrate.

[0053] Next, after post-baking, an additional heating period of 3 hours was performed at 230°C (ad-baking: the state shown in Figure 4). The light transmission spectra of the coated plates after pre-baking, post-baking, and ad-baking were measured using a spectrophotometer (JASCO Corporation, V-670). The measurement results are shown in Figures 2 to 4. In addition, representative values ​​of the light transmittance (%) after pre-baking, post-baking, and ad-baking in the wavelength range of 900 to 950 nm (infrared region) for each example are shown in Table 2. The evaluation criteria are that if the transmittance at wavelengths of 780 to 950 nm after post-baking is 30% or less, it is practically usable, and the closer the transmittance is to 0%, the better the near-infrared absorption characteristics are considered to be.

[0054] [Table 2]

[0055] (Evaluation Results) As shown in Tables 1 and 2, and Figures 2-4, the pigment dispersion of the present invention, which contains a suzunaphthalocyanine pigment and a specific resin-type dispersant having a phosphate group, can disperse even suzunaphthalocyanine pigments, which are generally said to be difficult to disperse stably, well. Therefore, the coating film-forming composition can also have good dispersibility. Furthermore, it can be seen that the cured film obtained by heat-curing the coating film-forming composition containing the pigment dispersion has good heat resistance and can maintain good shielding of near-infrared light. In particular, the cured film made from a composition using an acrylic resin-type dispersant A, whose main skeleton is an acrylic skeleton, has heat resistance that can withstand heating during film formation processing as well as temperature rise due to exposure to sunlight when used.

Claims

1. It contains suzunaphthalocyanine pigment, a dispersant and a solvent, The dispersant is a resin-type dispersant having a phosphate group, an acid value of 1 to 128 mg KOH / g, and an amine value of 0 mg KOH / g. A pigment dispersion wherein the suzunaphthalocyanine pigment is represented by the following formula (1). 【Chemistry 1】 (In formula (1), R1 to R24 each independently represent a hydrogen atom, a halogen atom, a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C6-C20 aryl group, a substituted or unsubstituted C4-C20 heterocyclic group, -O-R25, or -S-R26; R25 and R26 each independently represent a hydrogen atom, a substituted or unsubstituted C1-C20 alkyl group, or a substituted or unsubstituted C6-C20 aryl group; and M represents dichloro or tin dichloride (SnCl2).)

2. The pigment dispersion according to claim 1, wherein the dispersant is an acrylic resin-type dispersant whose main skeleton is an acrylic skeleton.

3. A coating film-forming composition comprising the pigment dispersion and coating film-forming component according to claim 1 or 2.

4. A cured film of the coating film-forming composition according to claim 3, which is capable of absorbing near-infrared light with a wavelength of 780 to 950 nm.

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