TWI858649B - Pigment dispersion, coating film forming composition and cured film - Google Patents

Abstract

The present invention relates to a pigment dispersion, a coating film forming composition and a cured film. The present invention provides a pigment dispersion and a coating film forming composition with excellent dispersibility, and provides a cured film with excellent near-infrared shielding and better heat resistance than before. A pigment dispersion, 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, wherein the pigment dispersion contains a naphthalocyanine tin pigment, a dispersant and a solvent, and the dispersant is a resin-type dispersant having a phosphoric acid group, an acid value of 1 to 128 mgKOH/g, and an amine value of 0 mgKOH/g.

Description

Pigment dispersion, coating film forming composition and cured film

The present invention relates to a pigment dispersion, a coating film forming composition and a cured film, and in particular to a pigment dispersion containing a naphthalocyanine tin pigment, a coating film forming composition and a cured film.

In the past, metal naphthalocyanine compounds, especially dichlorotin (Tin, Sn) naphthalocyanine compounds (hereinafter referred to as tin naphthalocyanine pigments) have been widely used as near-infrared absorption materials because of their large absorption in the near-infrared region (e.g., Patent Documents 1, 2, etc.).

Patent document 1 discloses a dichloronaphthalocyanine tin compound having a flat light absorption waveform in the near-infrared wavelength region of 750 to 950 nm, and a near-infrared absorption material using the compound.

Patent document 2 describes a metal naphthalocyanine pigment (naphthalocyanine tin pigment) containing a chlorinated naphthalocyanine tin compound having a specific crystal form, a near-infrared absorbing material containing the pigment, etc. It also describes that this specific naphthalocyanine tin pigment has high dispersibility.

[Prior art literature]

[Patent Literature]

[Patent Document 1] Japanese Patent Publication No. 11-35583

[Patent Document 2] Japanese Patent Publication No. 2008-202000

However, it is generally considered difficult to stably disperse metal naphthalocyanine pigments such as naphthalocyanine tin pigments.

In addition, coatings containing naphthalocyanine tin pigments need to be able to withstand the heating (heat history) during film formation. At the same time, when used as infrared absorbing materials such as sensors, the temperature may also rise due to exposure to sunlight, etc. In other words, high heat resistance is also required as a coating. There is still room for improvement in this regard.

The purpose of the present invention is to provide a pigment dispersion and a coating film forming composition with excellent dispersibility. In addition, the purpose of the present invention is to provide a cured film with excellent near-infrared shielding properties and better heat resistance than before.

The inventors of the present invention have conducted in-depth research to solve the above-mentioned problems. As a result, it was found that the above-mentioned problems can be solved by using naphthalocyanine tin pigment and a specific resin-type dispersant to form a pigment dispersion. The gist of the present invention is as follows.

(1) A pigment dispersion comprising naphthalocyanine tin pigment, a dispersant and a solvent,

The above dispersant is a resin-type dispersant having a phosphoric acid group, an acid value of 1~128mgKOH/g, and an amine value of 0mgKOH/g.

(2) The pigment dispersion according to the above item (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 described in the preceding item (1) or (2) and a coating film forming component.

(4) The cured film of the coating film-forming composition described in the preceding item (3) can absorb near-infrared light with a wavelength of 780 to 950 nm.

According to the present invention, a pigment dispersion and a coating film forming composition with excellent dispersibility can be provided. In addition, a cured film with excellent near-infrared shielding properties and better heat resistance than before can be provided.

FIG1 is a diagram showing the X-ray diffraction spectrum of the naphthalocyanine tin pigment used in Example 1.

Figure 2 is a graph showing the transmission spectrum of the coating film made using the pigment dispersion of Examples 1 to 3 after pre-baking.

Figure 3 is a graph showing the transmission spectra of the cured films of Examples 1 to 3 after post-baking.

Figure 4 is a graph showing the transmission spectrum of the cured films of Examples 1 to 3 after additional baking.

The pigment dispersion of the embodiment of the present invention contains naphthalocyanine tin pigment, dispersant and solvent. Moreover, the above-mentioned dispersant is a resin-type dispersant having a phosphate group. The acid value of the resin-type dispersant is 1~128mgKOH/g, and the amine value of the resin-type dispersant is 0mgKOH/g.

The above-mentioned naphthalocyanine tin pigment can use the substance represented by the following formula (1).

In formula (1), R ₁ to R ₂₄ each independently represent 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, -OR ₂₅ or -SR ₂₆ , R ₂₅ and R ₂₆ each independently represent a hydrogen 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, and M represents tin dichloride (SnCl ₂ ).

R ₁ to R ₂₄ in formula (1) are preferably hydrogen atoms. In addition, there is no particular limitation on the naphthalocyanine tin pigment in which R ₁ to R ₂₄ are hydrogen atoms, and for example, a pigment having a crystal form described in Japanese Patent Publication No. 2008-202000, a pigment having a crystal form used in Example 1 described later, etc. can be cited. The naphthalocyanine tin pigment of the present invention used in Example 1 shows an X-ray diffraction spectrum (XRD pattern) as shown in FIG. 1, and the Bragg angle 2 θ (±0.3°) in the X-ray diffraction spectrum shows a maximum diffraction peak at 6.0°, and has diffraction peaks at 11.9°, 13.8°, 14.7°, 16.4°, 17.2°, 26.7°, and 27.2°.

The average primary particle size of the naphthalocyanine tin pigment particles is preferably 10 to 40 nm. The primary particle size of the naphthalocyanine tin pigment can be measured, for example, based on an image of the pigment photographed at a magnification of 100,000 times under a transmission electron microscope. In addition, for the average primary particle size, for example, the primary particle sizes of 100 particles can be measured, and the average value thereof can be used as the average primary particle size.

Naphthalocyanine tin pigments can be micronized pigments. Micronization can be done by either wet or dry methods. For example, the method described in Japanese Patent Publication No. 2008-202000 can be used.

Based on the solid content, the content of naphthalocyanine tin pigment in the pigment dispersion can be 1~12% by weight.

The dispersant can be any resin-type dispersant having a phosphate group, an acid value of 1 to 128 mgKOH/g, and an amine value of 0 mgKOH/g. From the perspective of dispersibility, the main skeleton of the resin structure of the resin-type dispersant is at least one selected from an acrylic skeleton, a polyester skeleton, and a polyether skeleton. Preferably, it has an acrylic skeleton.

The acid value of the dispersant can be 1~128mgKOH/g. From the perspective of dispersibility, it is preferably 20~100mgKOH/g, and more preferably 30~75mgKOH/g. The acid value of the dispersant (the acid value when converted to solid content) can be obtained, for example, according to the method of DIN EN ISO 2114. The amine value of the dispersant (the amine value when converted to solid content) can be obtained, for example, according to the method of DIN 16945.

The molecular weight of the resin type dispersant is not particularly limited. For example, a dispersant having a weight average molecular weight (M _W ) of 3,000 to 40,000 can be used.

From the perspective of dispersibility, the content of the dispersant in the pigment dispersion is preferably 50 to 200 parts by weight based on solid content relative to 100 parts by weight of naphthalocyanine tin pigment.

Examples of solvents include aromatic, ketone, ester, glycol ether, alcohol, and aliphatic solvents. From the perspective of film formation, it is preferred to select at least one of aromatic, ketone, ester, and glycol ether solvents, and ester solvents are particularly preferred. Examples of ester solvents include propylene glycol monomethyl ether acetate (PMA or PGMEA). Solvents may be used alone or in combination of two or more.

The content of the solvent in the pigment dispersion is not particularly limited. For example, it can be 70 to 99% by weight in the pigment dispersion.

The pigment dispersion may also contain other additives in addition to the above-mentioned components as needed. As other additives, there can be cited pigment derivatives, dispersing resins, dyes, pigments other than naphthalocyanine tin pigments, antioxidants, anti-agglomeration agents, surface conditioners (leveling agents), etc.

The pigment dispersion can be prepared, for example, by adding the above-mentioned components to a known disperser such as a bead mill, a sand mill, a disperser, a paint conditioner, etc. and dispersing them. In addition, filtering treatment can be performed as needed, and a solvent can be added and stirred to adjust the pigment concentration.

The pigment dispersion has good dispersibility. Such dispersibility can be evaluated, for example, by confirming the viscosity of the pigment dispersion just after the dispersion treatment and the particle size of the particles contained in the pigment dispersion. In addition, the dispersion stability can also be observed by confirming the degree of change in viscosity and particle size after storage under specified conditions for a specified period of time after the dispersion treatment.

More specifically, the viscosity (initial viscosity A) and particle size (initial particle size X) immediately after the dispersion process can be measured and evaluated. In addition, the viscosity (initial viscosity A) and particle size (initial particle size X) immediately after the dispersion process, as well as the viscosity (viscosity after storage B) and particle size (particle size after storage Y) after one week of storage at 40°C after the dispersion process can also be measured, and the evaluation can be performed based on the ratio of the viscosity B after storage to the initial viscosity A (B/A×100), and the ratio of the particle size Y after storage to the initial particle size X (Y/X×100).

If these ratios: the change rate of the viscosity of the pigment dispersion is 60-120%, and the change rate of the particle size of the particles contained in the pigment dispersion is 70-140%, the dispersion stability can be evaluated to be good. The viscosity and particle size can be measured using, for example, a measuring device described in the embodiments described below.

The coating film forming composition of the embodiment of the present invention contains the above-mentioned pigment dispersion and coating film forming components. That is, it can also be said that the coating film forming composition contains the components constituting the above-mentioned pigment dispersion and coating film forming components.

Examples of coating film-forming components include polymerizable components, polymers, and mixtures thereof.

樹脂)等。 Examples of the polymer include thermoplastic urethane resins, (meth) acrylic resins, polyamide resins, polyimide resins, styrene-maleic acid resins, polyester resins, organic silicon resins, and cardo resins (

Resin) etc.

The content of the polymer in the film-forming composition is preferably 10 to 90% by weight, more preferably 30 to 70% by weight, in the total solid content of the film-forming composition. When the pigment dispersion contains a dispersing resin, the content of the polymer in the film-forming composition is the total content including the dispersing resin. The molecular weight of the polymer can be appropriately determined. In addition, the concentration of the pigment in the total solid content of the film-forming composition is preferably 3 to 30% by weight.

Among the polymers used as coating film forming components, alkali-soluble resins that show solubility in alkaline solutions are preferred. Examples of such alkali-soluble resins include (meth)acrylic polymers described in Japanese Patent Publication No. 2021-191846 or Japanese Patent Publication No. 2009-179789. From the perspective of developing properties, the weight average molecular weight of the alkali-soluble resin is preferably 5,000 to 50,000.

As a polymerizable component, it is easy to implement patterning by photolithography or development (negative development), so a photosensitive polymerizable component (photopolymerizable component) is preferred. As usable photopolymerizable components, photopolymerizable compounds and photopolymerization initiators are included. Such photopolymerizable compounds and photopolymerization initiators can be, for example, substances described in Japanese Patent Gazette No. 2009-179789. Relative to the total solid content in the film-forming composition, the photopolymerizable compound preferably contains 5 to 70 weight%. In addition, these can be used alone or in combination of two or more. The content of the photopolymerization initiator in the film-forming composition is preferably 0.1 to 10 weight% relative to the total solid content in the film-forming composition.

The coating film forming composition may also contain various additives such as sensitizers (sensitizing pigments), chain transfer agents, fluorine-based organic compounds, thermal polymerization initiators, thermal polymerization components, fillers, surfactants, adhesion promoters, antioxidants, anti-agglomeration agents, and surface conditioners (leveling agents) as needed.

The coating film forming composition can be obtained by stirring the above-mentioned components using, for example, a disperser, a vibrator, etc. When a pigment dispersion is used, a solvent can be added to adjust the concentration of the solid component in the coating film forming composition. In addition, the concentration of the solid component in the coating film forming composition during stirring can be, for example, 5 to 30% by weight. The obtained mixed solution can be filtered as needed.

The cured film of the coating film forming composition can be formed as follows: the coating film is formed by applying the coating film forming composition to the desired thickness on the desired substrate surface using a known device such as a spin coater, and the coating film forming component is cured by heating or the like. The cured film can absorb near-infrared light with a wavelength of 780 to 950 nm. In particular, the heat resistance is good. For example, even after heating (post-baking) under the conditions described in the first column of the embodiment described later, the absorption of near-infrared light with a wavelength of 780 to 950 nm can be within the range of practical use. Such a cured film is suitable as a near-infrared absorption filter used in filters, solid-state imaging elements, image display devices, infrared sensors, etc.

[Implementation example]

Below, the implementation of the present invention is described in more detail based on the embodiments.

(Implementation Example 1)

Pigment used: Naphthalocyanine tin pigment (manufactured by Sanyo Pigment Co., Ltd., NC502)

In formula (1), R1 to R24 are hydrogen atoms, and M is SnCl ₂ . The X-ray diffraction spectrum is shown in Fig. 1 . It has diffraction peaks at the predetermined positions as described above.

Composition: 6 parts by weight of naphthalocyanine tin pigment (NC502),

Resin type dispersant A (main skeleton: acrylic skeleton, group adsorbed to the pigment: phosphate group, solid content: 56.4% by weight, acid value: 48 mgKOH/g, amine value: 0 mgKOH/g) 10.6 parts by weight,

Solvent (propylene glycol monomethyl ether acetate: PMA or PGMEA) 83.4 parts by weight,

The above composition is mixed to obtain a mill base. Then, 400 parts by weight of zirconia beads with a diameter of 0.1 mm are mixed with 100 parts by weight of the mill base, and a dispersion treatment is performed for 60 minutes using a coating conditioner. Then, the zirconia beads are removed and PMA is added and stirred to make the concentration of naphthalocyanine tin pigment 5% by weight, thereby obtaining the pigment dispersion of Example 1.

(Example 2)

Composition: 6 parts by weight of naphthalocyanine tin pigment (NC502),

Resin type dispersant B (main skeleton: polyester skeleton, group adsorbed to pigment: phosphate group, solid content: 100 weight%, acid value: 50 mgKOH/g, amine value: 0 mgKOH/g) 6 parts by weight,

Solvent (PMA) 88 parts by weight,

The above components are mixed to obtain a mill base. Then, the pigment dispersion of Example 2 is obtained by the same operation as Example 1.

(Implementation Example 3)

Composition: 6 parts by weight of naphthalocyanine tin pigment (NC502),

Resin type dispersant C (main skeleton: polyether skeleton, group adsorbed to pigment: phosphate group, solid content: 50% by weight, acid value: 48 mgKOH/g, amine value: 0 mgKOH/g) 12 parts by weight,

Solvent (PMA) 82 parts by weight,

The above components are mixed to obtain a mill base. Then, the pigment dispersion of Example 3 is obtained by the same operation as Example 1.

(Comparison Example 1)

Composition: 6 parts by weight of naphthalocyanine tin pigment (NC502),

Resin type dispersant D (main skeleton: polyester skeleton, group adsorbed to pigment: phosphate group, solid content: 100% by weight, acid value: 129 mgKOH/g, amine value: 0 mgKOH/g) 6 parts by weight,

Solvent (PMA) 88 parts by weight,

The above composition was mixed to obtain a mill base. Then, a dispersion treatment was performed by the same operation as in Example 1, but gelation occurred and a pigment dispersion could not be obtained. That is, the composition of Comparative Example 1 caused poor dispersion.

(Comparison Example 2)

Composition: 6 parts by weight of naphthalocyanine tin pigment (NC502),

Resin type dispersant E (main skeleton: acrylic skeleton, group adsorbed to the pigment: amine group, solid content: 45.1% by weight, acid value: 19 mgKOH/g, amine value: 29 mgKOH/g) 13.3 parts by weight,

Solvent (PMA) 80.7 parts by weight,

The above composition was mixed to obtain a mill base. Then, a dispersion treatment was performed by the same operation as in Example 1, but gelation occurred and a pigment dispersion could not be obtained. That is, the composition of Comparative Example 2 caused poor dispersion.

(Comparison Example 3)

Composition: 6 parts by weight of naphthalocyanine tin pigment (NC502),

Resin type dispersant F (main skeleton: acrylic skeleton, group adsorbed to pigment: carboxyl, solid content: 100% by weight, acid value: 106 mgKOH/g, amine value: 0 mgKOH/g) 6 parts by weight,

Solvent (PMA) 88 parts by weight,

The above composition was mixed to obtain a mill base. Then, a dispersion treatment was performed by the same operation as in Example 1, but gelation occurred and a pigment dispersion could not be obtained. That is, the composition of Comparative Example 3 caused poor dispersion.

(Rating 1)

<Viscosity>

For the pigment dispersions obtained in Examples 1 to 3, as shown in "Table 1", the dispersibility of the pigment dispersions was evaluated based on the initial viscosity (A) just prepared. It should be noted that the initial viscosity (A) of 30 mPa‧s or less was judged as "good". In addition, the viscosity (B) after storage at 40°C for 1 week was measured, and the change rate (dispersion stability) of the viscosity (B) after storage relative to the initial viscosity (A) was calculated using the following formula. It should be noted that the viscosity was measured using a TV-22 viscometer manufactured by Toki Sangyo Co., Ltd.

Viscosity change rate [%] = (viscosity B after storage/initial viscosity A) × 100

<Particle size>

For the pigment dispersions obtained in Examples 1 to 3, the initial particle size (X) immediately after preparation was judged to be "good" if it was less than 180 nm. In addition, the particle size (Y) after storage at 40°C for one week was measured, and the change rate (dispersion stability) of the particle size (Y) after storage relative to the initial particle size (X) was calculated using the following formula. It should be noted that the particle size was measured using FPAR-1000 manufactured by Otsuka Electronics Co., Ltd.

Particle size change rate [%] = (particle size after storage Y/initial particle size X) × 100

The results of evaluation 1 are shown in Table 1.

(Rating 2)

<Heat resistance of coating>

The pigment dispersion obtained in Examples 1 to 3, the coating film forming component (acrylic resin, weight average molecular weight: 7700, acid value: 115mgKOH/g, amine value: none, solid content: 37.2% by weight) and the solvent (PMA) were mixed and stirred to prepare a coating liquid (the coating film forming composition of the present invention). At this time, the solid content of the coating liquid was 12% by weight, and the concentration of the pigment in the coating liquid based on the solid content was 25% by weight. Using each coating liquid of the obtained Examples 1, 2, and 3, each coating film with a film thickness of 1 μm was formed by spin coating on the surface of a substrate (material: glass). The substrate (coated plate) with each coating film formed on the surface was dried at room temperature (23°C) for 3 minutes, heated at 90°C for 2.5 minutes (pre-baking: state in Figure 2), and then heated at 230°C for 30 minutes (post-baking: state in Figure 3), thereby forming a cured film on the substrate.

Next, after post-baking, additional heating was performed at 230°C for 3 hours (additional baking: state of Figure 4). For the coated board after pre-baking, post-baking and additional baking, the light transmission spectrum was measured using a spectrophotometer (V-670 manufactured by JASCO Corporation). The measurement results are shown in Figures 2 to 4. In addition, the representative values of the light transmittance (%) after pre-baking, post-baking and additional baking at a wavelength of 900 to 950nm (infrared region) of each embodiment are shown in "Table 2". It should be noted that regarding the evaluation criteria, if the transmittance at a wavelength of 780 to 950nm after post-baking is less than 30%, it can be actually used. It can be said that the closer the transmittance is to 0%, the better the near-infrared absorption characteristics are.

(Evaluation results) As shown in Table 1, Table 2, and Figures 2 to 4, the pigment dispersion of the present invention containing naphthalocyanine tin pigment and a specific resin-type dispersant having a phosphate group can be well dispersed even for naphthalocyanine tin pigment which is generally considered difficult to disperse stably. Therefore, the coating film forming composition can also have good dispersibility. In addition, it can be seen that the cured film formed by heating and curing the coating film forming composition containing the above-mentioned pigment dispersion has good heat resistance and can maintain good near-infrared light shielding. Among them, the cured film composed of the composition using the acrylic resin-type dispersant A whose main skeleton is an acrylic skeleton has heat resistance that can withstand heating during film forming processing and can withstand temperature rise caused by exposure to sunlight during use.

Claims (4)

A pigment dispersion contains naphthalocyanine tin pigment, a dispersant and a solvent, wherein the dispersant is a resin-type dispersant having a phosphate group, an acid value of 30-75 mgKOH/g and an amine value of 0 mgKOH/g; the main skeleton of the resin structure of the resin-type dispersant is at least one selected from an acrylic skeleton and a polyester skeleton. The pigment dispersion as described in claim 1, wherein the dispersant is an acrylic resin type dispersant whose main skeleton is an acrylic skeleton. A coating film forming composition comprising the pigment dispersion described in claim 1 or 2 and a coating film forming component. The cured film of the coating film-forming composition described in claim 3 can absorb near-infrared rays with a wavelength of 780 to 950 nm.

Images