White composition containing porous resin particles and method for producing the white composition containing porous resin particles

Abstract

To provide a porous resin particle-containing white composition that has improved whiteness.SOLUTION: A porous resin particle-containing white composition contains porous resin particles with an average particle size of 15 μm or less and a specific surface area of 5 m2 / g or more, and a dispersion medium. The porous resin particles have a pore size of 200 nm or less and a pore capacity of 0.03 cm3 / g or more.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a white composition containing porous resin particles and a method for producing the white composition containing porous resin particles. [Background technology]

[0002] Generally, white materials are formed from a particle-like dispersoid that does not absorb visible light and a dispersion medium present around the dispersoid. Because the degree of whiteness is due to reflection and scattering between different substances, a large difference in refractive index between the dispersoid and the dispersion medium is generally preferred. For this reason, inorganic pigments with high refractive index, such as titanium oxide, are often used as the dispersoid. However, inorganic pigments often have a high specific gravity and tend to settle easily. Furthermore, once settled, they are difficult to redisperse, which can lead to nozzle clogging when discharging ink, etc.

[0003] For this reason, in recent years, studies have been conducted on the use of organic materials, which have a lower specific gravity than inorganic pigments. For example, hollow resin particles made of styrene-based resin or acrylic resin (Patent Documents 1 and 2) and porous particles made of acrylic resin or starch (Patent Documents 3 and 4) have been proposed. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-122310 [Patent Document 2] Japanese Patent Application Laid-Open No. 2015-134890 [Patent Document 3] Japanese Patent Application Laid-Open No. 2014-111728 [Patent Document 4] Special Publication No. 2007-507572 Summary of the Invention [Problem to be solved by the invention]

[0005] However, when hollow resin particles such as those shown in Patent Documents 1 and 2 are used, although reflection can be obtained at the interface between the hollow center portion and the resin, the dispersion medium is generally resin, so there is a problem that sufficient reflection cannot be obtained at the interface between the hollow resin particles and the dispersion medium.Furthermore, since the hollow center portion of hollow resin particles is hollow, they are prone to deformation when dispersed using beads or when heated, and there is also a problem that deformation changes the whiteness.

[0006] Furthermore, the method of swelling resin particles to make them porous, as shown in Patent Document 3, has the problem that the pore size tends to become large, making it unsuitable for particle sizes that maximize the whiteness of the resin particles. Furthermore, because the pore size of the porous resin particles is large, the dispersion medium penetrates the porous resin particles, resulting in insufficient reflection at the interface between the porous resin particles and the dispersion medium. The starch shown in Patent Document 4 certainly has whiteness in the porous particles themselves, but because its refractive index is nearly the same as that of the general resins used in dispersion media, when the starch is used in ink or paint, the reflections of the porous particles and the dispersion medium cancel each other out, resulting in a significant reduction in whiteness.

[0007] An object of the present invention is to provide a porous resin particle-containing white composition that can improve whiteness, and a method for producing the porous resin particle-containing white composition. [Means for solving the problem]

[0008]

[0006] To achieve the above object, the inventors conducted extensive research and found that porous resin particles having a predetermined average particle size and a predetermined specific surface area can be produced by producing porous resin particles using a method selected from high-density crystallization, nanoparticle precipitation, and polymerization-induced phase separation. Mixing the resulting porous resin particles with a dispersion medium to form a porous resin particle-containing composition produces sufficient reflection at the interface between the porous resin particles and the dispersion medium, resulting in stable, excellent whiteness. Furthermore, the inventors found that adding inorganic oxide fine particles to the mixture of porous resin particles and a dispersion medium increases the number of reflections due to light scattering by the inorganic oxide fine particles, and also generates reflection at the interface between the inorganic oxide fine particles and the porous resin particles, resulting in further improved whiteness.

[0009] That is, the present invention provides the following configurations. [1] Average particle diameter 15μm or less, specific surface area 5m 2 / g or more, and a dispersion medium.

[0010] [2] The pore diameter of the porous resin particles is 200 nm or less, and the pore volume is 0.03 cm 3 / g or more of the porous resin particle-containing white composition according to [1] above.

[0011] [3] The porous resin particle-containing white composition according to [1] or [2] above, wherein the difference Δn between the refractive index of the porous resin particles and the refractive index of the dispersion medium is 0.10 or more and 1.0 or less.

[0012] [4] The porous resin particle-containing white composition according to any one of the above [1] to [3], wherein the porous resin particles are made of a crystalline resin.

[0013] [5] The porous resin particle-containing white composition according to any one of the above [1] to [4], wherein the porous resin particles have a spherical shape.

[0014] [6] The porous resin particle-containing white composition according to [1] above, further containing inorganic oxide fine particles.

[0015] [7] The porous resin particle-containing white composition according to [6] above, wherein the inorganic oxide microparticles are composed of one or more inorganic oxide microparticles selected from the group consisting of titanium oxide, cerium oxide, zirconium oxide, zinc oxide, tin oxide, indium tin oxide, tungsten oxide, tantalum oxide, niobium oxide, and germanium oxide.

[0016] [8] The porous resin particle-containing white composition according to [6] or [7] above, wherein one or more of the inorganic oxide fine particles are supported on the porous resin particles.

[0017] [9] The dispersion medium is water, The porous resin particle-containing white composition according to any one of the above [1] to [8], wherein the porous resin particle-containing white composition is a white aqueous dispersion.

[0018]

[10] The brightness L of the white water dispersion * The porous resin particle-containing white composition according to [9] above, wherein is 20 or more.

[0019]

[11] The dispersion medium is a resin, The porous resin particle-containing white composition according to any one of the above [1] to [8], which is a white ink or a white paint.

[0020]

[12] Lightness L of the white ink * The porous resin particle-containing white composition according to

[11] above, wherein the value of the whiteness index is 30 or more.

[0021]

[13] Lightness L of the white paint * The porous resin particle-containing white composition according to

[11] above, wherein the value of the whiteness index is 50 or more.

[0022]

[14] A method selected from the group consisting of high-density crystallization, nanoparticle precipitation, and polymerization-induced phase separation, which produces nanoparticles with an average particle size of 15 μm or less and a specific surface area of ​​5 m 2 / g or more of porous resin particles, A method for producing a white composition containing porous resin particles, comprising mixing the porous resin particles with a dispersion medium to obtain a white composition containing porous resin particles.

[0023]

[15] The high-density crystallization method includes: a heating and dissolving step of heating and dissolving a polymer compound having an aromatic ring in its main chain, which may have a substituent, in an organic solvent to obtain a solution containing the polymer compound; a gelling step of cooling the solution to obtain a gel; a crushing step of crushing the gel to obtain porous resin particles containing a co-crystal of the polymer compound and the organic solvent; and The boiling point of the organic solvent is 100°C or higher, and The hydrogen bond term of the Hansen solubility parameter of the organic solvent is 7.4 MPa 0.5 or less, or the hydrogen bond term is 7.4 MPa 0.5 and the polarization term of the Hansen solubility parameter is 11.4 MPa. 0.5

[14] The method for producing a porous resin particle-containing white composition according to

[14] above, wherein the white composition contains less than 100% by weight of porous resin particles.

[0024]

[16] Producing porous resin particles by either the high-density crystallization method or the nanoparticle precipitation method; The method for producing a white composition containing porous resin particles according to

[14] or

[15] above, wherein the porous resin particles as a dispersoid and a resin as a dispersion medium are mixed to obtain a white ink.

[0025]

[17] The method for producing a white composition containing porous resin particles according to the above

[16] , further comprising mixing inorganic oxide fine particles in addition to the porous resin particles and the resin.

[0026]

[18] Producing porous resin particles by the nanoparticle precipitation method; The method for producing a white composition containing porous resin particles according to

[14] or

[15] above, wherein the porous resin particles as a dispersoid are mixed with water as a dispersion medium to obtain a white aqueous dispersion.

[0027]

[19] Producing porous resin particles by any method selected from a high-density crystallization method, a nanoparticle precipitation method, and a polymerization-induced phase separation method; The method for producing a white composition containing porous resin particles according to

[14] or

[15] above, wherein the porous resin particles as a dispersoid and a resin as a dispersion medium are mixed to obtain a white paint.

[0028]

[20] A method for producing a white composition containing porous resin particles according to claim 19, further comprising mixing inorganic oxide fine particles in addition to the porous resin particles and the resin. [Effects of the Invention]

[0029] According to the present invention, it is possible to provide a porous resin particle-containing white composition capable of improving whiteness, and a method for producing a porous resin particle-containing white composition. [Brief explanation of the drawings]

[0030] [Figure 1] FIG. 1 is a schematic diagram showing an example of a porous resin particle-containing white composition according to this embodiment. [Figure 2] FIG. 2 is an electron microscope image showing the appearance of the porous resin particles contained in the porous resin particle-containing white composition. [Figure 3] 3(a) and 3(b) are schematic diagrams showing modified examples of the porous resin particle-containing white composition of FIG. [Figure 4] FIG. 4 is a schematic diagram illustrating a method for measuring the lightness L* of a porous resin particle-containing white ink or a porous resin particle-containing white water dispersion in the examples. [Figure 5] FIG. 5(a) is an electron microscope image showing the appearance of the porous resin particles produced by the high-density crystallization method of Production Example 2, and FIG. 5(b) is a schematic diagram of the porous resin particles. [Figure 6] FIG. 6(a) is an electron microscope image showing the appearance of the porous resin particles produced by the nanoparticle precipitation method of Production Example 4, and FIG. 6(b) is a schematic diagram of the porous resin particles. [Figure 7]7(a) and 7(b) are schematic diagrams for explaining a method for measuring the lightness L* of a white paint containing porous resin particles in the examples. [Figure 8] FIG. 8(a) is an electron microscope image showing the appearance of the porous resin particles produced by the polymerization-induced phase separation method of Production Example 5, and FIG. 8(b) is a schematic diagram of the porous resin particles. [Figure 9] FIG. 9 is an electron microscope image showing the appearance of the porous resin particles after mixing and dispersion in Example 15. [Figure 10] FIG. 10 is an electron microscope image showing the appearance of the porous resin particles after mixing and dispersion in Example 16. [Figure 11] FIG. 11 is an electron microscope image showing the appearance of the porous resin particles after mixing and dispersion in Example 17. DETAILED DESCRIPTION OF THE INVENTION

[0031] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings, but the present invention is not limited to the following embodiments.

[0032] <White composition containing porous resin particles> 1 is a schematic diagram showing an example of a porous resin particle-containing white composition according to this embodiment. As shown in FIG. 1, a porous resin particle-containing white composition 1A has an average particle diameter of 15 μm or less and a specific surface area of ​​5 m 2 / g or more, and a dispersion medium 3. The porous fine particles are added to the porous resin particle-containing white composition mainly as a pigment, and exhibit a white color when dispersed in the dispersion medium.

[0033] [Porous resin particles] FIG. 2 is an electron microscope image showing the appearance of porous resin particles contained in a porous resin particle-containing white composition. As shown in FIG. 2, the porous resin particles have a plurality of pores (also called pores) with the same or different pore diameters and shapes, and in particular, the pores are formed on the particle surface. The pores may be independent pores (independent pores) or continuous pores (continuous pores). Examples of resin particles include hollow resin particles, which have a hollow wall, such as a substantially spherical wall, and a hollow portion (pore) inside, and basically have one pore. The porous resin particles used in this embodiment do not include hollow resin particles with different pore forms, such as pore shape and number of pores. The average particle size of the porous resin particles used in this embodiment is 15 μm or less, and can be 10 μm or less, 5 μm or less, or 2 μm or less. The average particle size of the porous resin particles can be 0.05 μm or more, 0.1 μm or more, or 1 μm or more. By setting the average particle size of the porous resin particles to 15 μm or less, the porous resin particles are less likely to precipitate in the porous resin particle-containing white composition, thereby achieving excellent whiteness. The average particle size of the porous resin particles can be measured by laser diffraction.

[0034] When the refractive index of the porous resin particles is n1 and the refractive index of the dispersion medium is n0, if the refractive index difference Δn (= n1 - n0) between the porous resin particles and the dispersion medium is relatively large, the whiteness of the porous resin particle-containing white composition tends to be improved by using a smaller average particle size of the porous resin particles, and if the refractive index difference Δn is relatively small, the whiteness of the porous resin particle-containing white composition tends to be improved by using a larger average particle size of the porous resin particles. Therefore, it is preferable to appropriately adjust the average particle size of the porous resin particles depending on the refractive index difference Δn between the porous resin particles and the dispersion medium.

[0035] The difference Δn between the refractive index of the porous resin particles and the refractive index of the dispersion medium can be, for example, 0.10 or more and 1.0 or less, 0.15 or more and 0.90 or less, or 0.20 or more and 0.70 or less.

[0036] The specific surface area of ​​the porous resin particles is 5m 2 / g or more, and 2 / g or more, 15m 2 / g or more, 50m 2 / g or more, or 60m 2 / g or more. 2 When the specific surface area is set to 1 / g or more, the area of ​​the interface between the porous resin particles having a refractive index difference and the dispersion medium increases due to the white coloring principle, and the reflectivity and scattering properties increase, thereby improving the whiteness. The specific surface area of ​​the porous resin particles can be measured, for example, by a gas adsorption method.

[0037] The refractive index n1 of the porous resin particles is not particularly limited, but from the viewpoint of improving reflectivity by increasing the refractive index difference Δn, it can be 1.6 or more, 1.8 or more, or 2.0 or more.

[0038] The pore diameter of the porous resin particles is not particularly limited, but is preferably 200 nm or less from the viewpoint of increasing the interface area between the porous resin particles and the dispersion medium. The pore diameter of the porous resin particles can be 100 nm or less, 50 nm or less, or 20 nm or less. Furthermore, the pore diameter of the porous resin particles can be 0.5 nm or more, or 1.0 nm or more.

[0039] The pore volume of the porous resin particles is not particularly limited, but from the viewpoint of further increasing the interface area between the porous resin particles and the dispersion medium, it is preferably 0.03 cm 3 / g or more. The pore volume of the porous resin particles is 0.1 cm 3 / g or more, 0.2cm 3 / g or more, or 0.25cm 3 / g or more.

[0040] The porous resin particles used in this embodiment include, for example, a co-crystal of a polymer compound having an aromatic ring, which may have a substituent, in the main chain and an organic solvent, and the organic solvent has a boiling point of 100°C or higher and a hydrogen bond term of the Hansen solubility parameter of the organic solvent of 7.4 MPa. 0.5or less, or the hydrogen bond term is 7.4 MPa 0.5 and the polarity term of the Hansen solubility parameter is 11.4 MPa. 0.5 is less than.

[0041] The polymer compound (hereinafter also referred to as the specific polymer compound) preferably has at least a repeating unit represented by the following formula 1A, from the viewpoint of making it easier to form a co-crystal with an organic solvent (hereinafter also referred to as the specific organic solvent) having the above-mentioned properties and making it easier to stabilize the structure of the resulting porous resin particles. [ka]

[0042] In formula 1A, L 1 , L 2 , and L 3 each independently represents a single bond or a divalent group, R 1 , R 2 , and R 3 each independently represents a monovalent substituent, or x, y, and z each independently represent an integer of 0 to 4, m represents an integer of 0 or more, n represents an integer of 0 to 10, and when n is 0, m is an integer of 1 or more, and when n≠0, p represents an integer of 1 to 3; L 1 , L 2 , and L 3 may be the same or different, and R 1 , R 2 , and R 3 may be the same or different, and R 1 , and R 2 may be bonded to each other to form a ring.

[0043] In formula 1A, L 2 , and L 3The divalent group is not particularly limited, but is preferably at least one group selected from the group consisting of an alkylene group (preferably having 1 to 10 carbon atoms) which may have a substituent, a carbonyl group, a sulfonyl group, -O-, -NR- (R represents a monovalent group), -S-, and combinations thereof; more preferably at least one group selected from the group consisting of -O-, a carbonyl group, a sulfonyl group, -C(CH3)2-, -OC(=O)-, -C(=O)O(CH2)2O-, and -S-; and even more preferably at least one group selected from the group consisting of -O-, -S-, a carbonyl group, and a sulfonyl group.

[0044] R 1 , R 2 , and R 3 The monovalent group is not particularly limited, but may include at least one group selected from the group consisting of a halogen atom, a carboxy group, a hydroxy group, an amino group, a hydrocarbon group having 1 to 10 carbon atoms (one or more hydrogen atoms may be substituted with a halogen atom), and a sulfonic acid group.

[0045] R 1 , and R 2 When they are bonded to each other to form a ring, they may, together with the naphthylene group and L1, form a biphenylenediyl group, a fluorenediyl group, a phenanthrenediyl group, an anthracenediyl group, a triphenylenediyl group, a thianthenediyl group, a xanthenediyl group, a phenoxathiindiyl group, a carbazolediyl group, an acridinediyl group, a phenothiazinediyl group, a phenoxazinediyl group, or the like.

[0046] m represents an integer of 0 or greater and is not particularly limited, but in terms of obtaining porous resin particles more efficiently, m is preferably an integer of 1 or greater, more preferably an integer of 3 or less, even more preferably an integer of 2 or less, and particularly preferably 1. n represents an integer of 0 to 10, and when n is 0, m is an integer of 1 or more, and n is preferably an integer of 0 to 3, and more preferably an integer of 1 or 2. p is preferably an integer of 1 to 3, and more preferably 1 or 2.

[0047] The specific polymer compound preferably has at least a repeating unit represented by the following formula 1B, from the viewpoint of more easily forming a co-crystal with the specific organic solvent and more easily stabilizing the structure of the resulting porous resin particles. [ka]

[0048] In formula 1B, L 2 , and L 3 each independently represent a single bond or a divalent group; R1, R2, and R3 each independently represent a monovalent substituent; x, y, and z each independently represent an integer of 0 to 4; m represents an integer of 0 or more; n represents an integer of 0 to 10; when n is 0, m is an integer of 1 or more; when n≠0, p represents an integer of 1 to 3; and each repeating unit contains L 2 , and L 3 When there are multiple repeating units, they may be the same or different, and each repeating unit has R 1 , R 2 , and R 3 When there are a plurality of groups, they may be the same or different. The examples of the groups and numbers of each symbol in formula 1B have the same meanings as those explained as the groups and numbers of each symbol in formula 1A, and the preferred embodiments are also the same.

[0049] When the specific polymer compound has a repeating unit represented by the above formula 1B, the specific organic solvent is preferably at least one selected from the group consisting of nitrobenzene and 1,2-dimethoxybenzene.

[0050] The porous resin particles may be composed of either an amorphous resin or a crystalline resin, but from the viewpoint of further improving reflectivity, they are preferably composed of a crystalline resin. When the porous resin particles are made of a crystalline resin, it is presumed that birefringence occurs in the molecular region of the crystalline portion, which promotes an increase in the refractive index and further improves reflectivity.

[0051] Examples of the amorphous resin include one or more selected from polyethersulfone (PES), polystyrene (PS), polycarbonate (PC), polyphenylene ether (PPE), polyarylate (PAR), polysulfone (PSU), polyetherimide (PEI), and polyamideimide (PAI).

[0052] Examples of the crystalline resin include one or more selected from polyimide (PI), polyether ether ketone (PEEK), polyamide (PA), polyphenylene sulfide (PPS), liquid crystal polymer (LCP), polyethylene naphthalate (PEN), and polybutylene naphthalate (PBN).

[0053] The porous resin particles are produced by any method selected from the group consisting of the high-density crystallization method described below, the known nanoparticle precipitation method, and the known polymerized organic phase separation method. The shape of the porous resin particles is not particularly limited, and they may have a connected structure in which particles are adhered to each other, or may be spherical. Porous resin particles having a connected structure in which particles are adhered to each other can be produced, for example, by the high-density crystallization method described below or the known nanoparticle precipitation method, and spherical porous resin particles can be produced, for example, by the known polymerized organic phase separation method.

[0054] [Dispersion medium] The dispersion medium used in this embodiment is not particularly limited, and examples thereof include water and resin. When water is used as the dispersion medium, the porous resin particle-containing white composition may be a white aqueous dispersion. When a resin is used as the dispersion medium, the porous resin particle-containing white composition may be a white ink or a white paint. Details of the white aqueous dispersion, white ink, and white paint will be described later.

[0055] The refractive index n0 of the dispersion medium is not particularly limited, but from the viewpoint of improving reflectivity by increasing the refractive index difference Δn, it can be 1.60 or less, 1.50 or less, or 1.40 or less.

[0056] [Inorganic oxide fine particles] 3(a) and 3(b) are schematic diagrams showing modified examples of the porous resin particle-containing white composition 1A of FIG. 1. The porous resin particle-containing white composition 1B may further contain inorganic oxide fine particles 4 having an average particle diameter of 0.1 μm or more and 1.0 μm or less (FIG. 3(a)). When the porous resin particle-containing white composition 1B contains inorganic oxide fine particles 4 having an average particle diameter within the above range, reflection occurs at the inorganic oxide fine particles 4, and the number of reflections due to light scattering at the inorganic oxide fine particles 4 by the porous resin particles 2 increases. Furthermore, in addition to reflection at the interface between the porous resin particles 2 and the dispersion medium 3, reflection also occurs at the interface between the inorganic oxide fine particles 4 and the porous resin particles 2, further improving whiteness.

[0057] The form of the inorganic oxide fine particles 4 in the porous resin particle-containing white composition 1B is not particularly limited, but for example, one or more inorganic oxide fine particles 4 may be supported on a porous resin particle 2 (FIG. 3(b)). This increases the area of ​​the interface between the porous resin particle 1 and the inorganic oxide fine particles 4, thereby further improving the whiteness.

[0058] The average particle size of the inorganic oxide fine particles is not limited to the above range, but can be 0.05 μm or more and 5.0 μm or less, or 0.1 μm or more and 2.0 μm or less.

[0059] The inorganic oxide microparticles are not particularly limited, but are preferably composed of one or more selected from the group consisting of titanium oxide, cerium oxide, zirconium oxide, zinc oxide, tin oxide, indium tin oxide, tungsten oxide, tantalum oxide, niobium oxide, and germanium oxide.

[0060] <Specific Examples of Porous Resin Particle-Containing White Compositions> (white ink) The white ink contains porous resin particles as a dispersoid having an average particle size and specific surface area within the above ranges, and a resin as a dispersion medium.

[0061] When the total mass of the white ink is taken as 100 mass%, the content of the porous resin particles is preferably 1.0 mass% or more and 60 mass% or less, more preferably 2.0 mass% or more and 50 mass% or less, and even more preferably 5.0 mass% or more and 40 mass% or less.

[0062] The resin contained in the white ink is not particularly limited, but examples thereof include polyurethane resins, polyamide resins, NC resins, alkyd resins, phenolic resins, and acrylic resins used in gravure printing inks, flexographic printing inks, and lithographic printing inks, as well as polyester resins and alkali-soluble resins used in resist inks.

[0063] The white ink preferably further contains inorganic oxide fine particles. The white ink may also contain one or more known additives such as fats and oils, auxiliaries, and solvents.

[0064] (white water dispersion) A white water dispersion that can be suitably used mainly for aqueous inkjet inks contains porous resin particles as a dispersoid having an average particle size and specific surface area within the above ranges, and water as a dispersion medium.

[0065] When the total mass of the white water dispersion is taken as 100 mass%, the content of the porous resin particles can be preferably 2.5 mass% or more and 50 mass% or less, more preferably 5.0 mass% or more and 40 mass% or less, and even more preferably 10 mass% or more and 30 mass% or less.

[0066] As the water, pure water or ultrapure water such as ion-exchanged water, ultrafiltered water, reverse osmosis water, distilled water, etc. can be used.

[0067] The white water dispersion may contain one or more known additives such as a dispersant, a solvent, a surfactant, and the like.

[0068] (white paint) The white paint contains porous resin particles as a dispersoid having an average particle size and specific surface area within the above ranges, and a resin as a dispersion medium.

[0069] When the total mass of the white paint is taken as 100 mass%, the content of the porous resin particles can be preferably 1.0 mass% or more and 50 mass% or less, more preferably 3.0 mass% or more and 40 mass% or less, and even more preferably 5.0 mass% or more and 30 mass% or less.

[0070] The resin contained in the white paint is not particularly limited, but examples thereof include acrylic resin, melamine resin, epoxy resin, polyester resin, polyurethane resin, polyamide resin, and phenol resin.

[0071] The white paint preferably further contains inorganic oxide fine particles and may also contain one or more known additives such as a dispersant, a plasticizer, an anti-settling agent, an emulsifier, a thickener, an antifoaming agent, an anti-algae agent, an anti-mold agent, a preservative, an anti-skinning agent, a drying agent, an anti-sagging agent, and a matting agent.

[0072] <Method of manufacturing a white composition containing porous resin particles> The method for producing the porous resin particle-containing white composition according to this embodiment is to produce porous resin particles having an average particle size of 15 μm or less and a specific surface area of ​​5 m by any one of a high-density crystallization method, a nanoparticle precipitation method, and a polymerization-induced phase separation method. 2 / g or more, and the porous resin particles are mixed with a dispersion medium to obtain a white composition containing porous resin particles.

[0073] <Method of manufacturing porous resin particles> [High-density crystallization method] The high-density crystallization method includes, for example, a heat-dissolving step, a gelling step, and a pulverization step. The high-density crystallization method may include other steps before the heat-dissolving step, between the steps, or after the pulverization step, without departing from the spirit of the present invention.

[0074] (heating melting process) The heat dissolution step is a step of dissolving a specific polymer compound in a specific organic solvent by heating to obtain a solution containing the specific polymer compound. This step prepares a homogeneous solution containing the specific organic solvent and the specific polymer compound, and enables efficient production of porous resin particles in a subsequent step.

[0075] The specific organic solvent has a boiling point of 100°C or higher and a hydrogen bond term of the Hansen solubility parameter of 7.4 MPa. 0.5 The following organic solvents (hereinafter, such specific organic solvents are also referred to as "specific organic solvent A-1"), or a solvent having a hydrogen bond parameter of 7.4 MPa 0.5 The polarization term of the Hansen solubility parameter exceeds 11.4 MPa. 0.5 (Such a specific organic solvent is hereinafter also referred to as "specific organic solvent A-2"). Among them, the specific organic solvent is preferably specific organic solvent A-1, from the viewpoint of making it easier to stabilize the structure of the obtained porous resin particles.

[0076] The mechanism by which the effects of the present invention are obtained by using a specific organic solvent is not entirely clear, but the present inventors speculate as follows. First, because the boiling point of the specific organic solvent is 100°C or higher, it is assumed that the thermal stability of the resulting cocrystal is more likely to be enhanced, and as a result, gelation is induced at a lower temperature. Furthermore, the inventors have experimentally confirmed that factors other than the dispersion term of the Hansen solubility parameter (polarization term, hydrogen bond term) contribute significantly to gelation, with the hydrogen bond term contributing most significantly.

[0077] The specific polymer compound has an aromatic ring such as a phenylene group in its main chain and a rigid and curved molecular structure, making it difficult to form a dense, regular crystal by itself. In such cases, voids exist in the bulk of the specific polymer compound. In this case, it is presumed that a specific organic solvent capable of dissolving the specific polymer compound, in other words, having a molecular size capable of penetrating the specific polymer compound in a glassy state and having the dispersion term and hydrogen bonding term of its Hansen solubility parameter within a predetermined range, penetrates and remains in the voids, and as a result, the co-crystal structure is likely to be stabilized.

[0078] The following are specific examples of specific organic solvents. Note that the numbers in parentheses in this paragraph represent the dispersion term, polarization term, hydrogen bond term, and boiling point of the Hansen solubility parameters, respectively. Examples of specific organic solvents include nitrobenzene (20.0, 10.6, 3.1, 210.9), 1,2-dimethoxybenzene (19.2, 4.4, 9.4, 206.3), cyclopentanone (17.9, 11.9, 5.2, 130.8), cyclohexanone (17.8, 8.4, 5.1, 155.7), γ-butyrolactone (18.0, 16.6, 7.4, 203.9), morpholine (18.0, 4.9, 11.0, 129.0), aniline (20.1, 5.8, 11.2, 184.5), and the like. At least one selected from the group consisting of nitrobenzene, 1,2-dimethoxybenzene, cyclopentanone, cyclohexanone, and γ-butyrolactone is preferred, at least one selected from the group consisting of nitrobenzene, 1,2-dimethoxybenzene, and γ-butyrolactone is more preferred, and at least one selected from nitrobenzene and 1,2-dimethoxybenzene is even more preferred. From the viewpoint of more stabilizing the structure of the resulting porous resin particles, nitrobenzene is particularly preferred as the specific organic solvent.

[0079] The hydrogen bond term of the Hansen solubility parameter of specific organic solvent A-1 is 7.4 MPa 0.5 less than 6.0 MPa 0.5 Preferably less than 4.0 MPa 0.5 Less than 1.0 MPa is more preferable. 0.5 The above is preferable.

[0080] The polarization term of the Hansen solubility parameter for specific organic solvent A-2 is 11.4 MPa. 0.5Less than 10.0 MPa 0.5 Less than 5.8MPa is more preferable. 0.5 More preferably, 5.0 MPa or less 0.5 Particularly preferred is 1.0 MPa or less. 0.5 The above is preferable.

[0081] The boiling point of the specific organic solvent is 100° C. or higher, and from the viewpoint of providing the resulting porous resin particles with superior stability, the boiling point is more preferably 130° C. or higher, and even more preferably 200° C. or higher. There is no particular upper limit, but the boiling point is preferably 300° C. or lower, and more preferably 250° C. or lower. When two or more specific organic solvents are used, it is preferable that the boiling point of the mixture is within the above-mentioned range.

[0082] The melting point of the specific organic solvent is not particularly limited, but is generally preferably −60° C. or higher, more preferably −45° C. or higher, even more preferably −10° C. or higher, and preferably 30° C. or lower, more preferably 20° C. or lower, and even more preferably 10° C. or lower.

[0083] The specific polymer compound is a component that forms a co-crystal with the specific organic solvent and constitutes the base of the porous resin particles. As the specific polymer compound, any known polymer compound can be used without any particular limitation, as long as it has an aromatic ring that may have a substituent in the main chain. As already explained, a polymer compound having a rigid and curved molecular structure is more likely to create voids inside and to form a co-crystal with a specific organic solvent.

[0084] The specific polymer compound preferably has at least a repeating unit represented by the following formula 1A, from the viewpoint of more easily forming a cocrystal with the specific organic solvent and more easily stabilizing the structure of the resulting porous resin particles. [ka]

[0085] In formula 1A, L 1 , L 2 , and L3 each independently represents a single bond or a divalent group, R 1 , R 2 , and R 3 each independently represents a monovalent substituent; x, y, and z each independently represent an integer of 0 to 4; m represents an integer of 0 or more; n represents an integer of 0 to 10; when n is 0, m is an integer of 1 or more; and when n≠0, p represents an integer of 1 to 3; L 1 , L 2 , and L 3 may be the same or different, and R 1 , R 2 , and R 3 may be the same or different, and R 1 , and R 2 may be bonded to each other to form a ring.

[0086] In formula 1A, L 2 , and L 3 The divalent group is not particularly limited, but is preferably at least one group selected from the group consisting of an alkylene group (preferably having 1 to 10 carbon atoms) which may have a substituent, a carbonyl group, a sulfonyl group, -O-, -NR- (R represents a monovalent group), -S-, and combinations thereof; more preferably at least one group selected from the group consisting of -O-, a carbonyl group, a sulfonyl group, -C(CH3)2-, -OC(=O)-, -C(=O)O(CH2)2O-, and -S-; and even more preferably at least one group selected from the group consisting of -O-, -S-, a carbonyl group, and a sulfonyl group.

[0087] R 1 , R 2 , and R 3 The monovalent group is not particularly limited, but may include at least one group selected from the group consisting of a halogen atom, a carboxy group, a hydroxy group, an amino group, a hydrocarbon group having 1 to 10 carbon atoms (one or more hydrogen atoms may be substituted with a halogen atom), and a sulfonic acid group.

[0088] R 1 , and R 2When they are bonded to each other to form a ring, they may, together with the naphthylene group and L1, form a biphenylenediyl group, a fluorenediyl group, a phenanthrenediyl group, an anthracenediyl group, a triphenylenediyl group, a thianthenediyl group, a xanthenediyl group, a phenoxathiindiyl group, a carbazolediyl group, an acridinediyl group, a phenothiazinediyl group, a phenoxazinediyl group, or the like.

[0089] m represents an integer of 0 or greater and is not particularly limited, but in terms of obtaining porous resin particles more efficiently, m is preferably an integer of 1 or greater, more preferably an integer of 3 or less, even more preferably an integer of 2 or less, and particularly preferably 1. n represents an integer of 0 to 10, and when n is 0, m is an integer of 1 or more, and n is preferably an integer of 0 to 3, and more preferably an integer of 1 or 2. p is preferably an integer of 1 to 3, and more preferably 1 or 2.

[0090] The specific polymer compound preferably has at least a repeating unit represented by the following formula 1B, from the viewpoint of more easily forming a co-crystal with the specific organic solvent and more easily stabilizing the structure of the resulting porous resin particles. [ka]

[0091] In formula 1B, L 2 , and L 3 each independently represent a single bond or a divalent group; R1, R2, and R3 each independently represent a monovalent substituent; x, y, and z each independently represent an integer of 0 to 4; m represents an integer of 0 or more; n represents an integer of 0 to 10; when n is 0, m is an integer of 1 or more; when n≠0, p represents an integer of 1 to 3; and each repeating unit contains L 2 , and L 3 When there are multiple repeating units, they may be the same or different, and each repeating unit has R 1 , R 2 , and R 3 When there are a plurality of groups, they may be the same or different. The examples of the groups and numbers of each symbol in formula 1B have the same meanings as those explained as the groups and numbers of each symbol in formula 1A, and the preferred embodiments are also the same.

[0092] The following formula 1B-1 is a specific example of a repeating unit represented by formula 1B. However, the repeating unit represented by formula 1B is not limited to the following example. Furthermore, each symbol in formula 1B-1 has the same meaning as each symbol in formula 1B. [ka]

[0093] The specific polymer compound may have one type of repeating unit represented by formula 1B alone or two or more types in combination. The specific polymer compound may also have a unit other than the repeating unit represented by formula 1B. The specific polymer compound may be either an amorphous polymer compound or a crystalline polymer compound, but from the viewpoint of further improving reflectivity, a crystalline polymer compound is preferred.

[0094] The content of the repeating unit represented by formula 1B in the specific polymer compound is not particularly limited, but from the viewpoint of providing the resulting porous resin particles with superior stability, the molar content of the unit represented by formula 1B in all repeating units of the specific polymer compound (when the specific polymer compound has two or more types of repeating units represented by formula 1B, the total content) is preferably 50 mol % or more, more preferably 70 mol % or more, even more preferably 90 mol % or more, and preferably 100 mol % or less.

[0095] The method for mixing the specific polymer compound with the specific organic solvent is not particularly limited, and the polymer compound may be added to the specific organic solvent, or the specific organic solvent may be added to the specific polymer compound. In this case, the mixing ratio of the specific polymer compound to the specific organic solvent is not particularly limited, but the mass ratio of the content of the specific polymer compound to the total mass of the obtained solution is preferably 0.2 (20 mass%) or more, more preferably 0.3 (30 mass%) or more, and even more preferably 0.4 (40 mass%) or more, in order to facilitate the generation of crystal nuclei and to facilitate the uniformity of the particle size of the resulting porous resin particles. The upper limit is not particularly limited, but is preferably 0.6 (60 mass%) or less, more preferably 0.5 (50 mass%) or less, in order to facilitate the fluidity and uniformity of the solution. When two or more specific polymer compounds and / or specific organic solvents are used, the total content thereof is preferably within the above range.

[0096] The heating temperature when the mixture of the specific polymer compound and the specific organic solvent is heated and dissolved is not particularly limited, but is preferably equal to or higher than the melting point of the specific organic solvent and equal to or lower than the boiling point of the specific organic solvent. In particular, from the viewpoint of being able to increase the temperature of the solution when obtaining particles, the heating temperature is preferably higher than 5°C, more preferably 10°C or higher, even more preferably 25°C or higher, and particularly preferably 50°C or higher.

[0097] It is generally known that the affinity between a polymer compound and an organic solvent has a greater effect on the solubility of the polymer compound in an organic solvent than the dissolution temperature. This production method achieves excellent compatibility between a specific polymer compound and a specific organic solvent by selecting a specific combination of the two. From the viewpoint of further improving energy efficiency, the heating temperature is preferably 50 to 150°C.

[0098] The solution obtained in this step is a solution in which the specific polymer compound is dissolved in the specific organic solvent, and the obtained solution is colorless or colored and transparent.

[0099] (Gelling process) The gelling step is a step in which the solution obtained in the heating and high dissolution step is cooled to obtain a gel. The cooling method is not particularly limited, and known methods can be used. Specific examples include a method in which a solution obtained by heating and stirring is cooled while stirring and maintained at a predetermined temperature. This step produces a gel containing porous resin particles that contain a co-crystal of a specific polymer compound and a specific organic solvent.

[0100] The temperature at which the solution is cooled and maintained is not particularly limited, but is preferably higher than the melting point of the specific organic solvent used, in that the mobility of the molecules of the specific polymer compound and the specific organic solvent is more suitable for nucleation and growth of co-crystals, in other words, the rate of co-crystal formation is faster. Furthermore, this production method uses a combination of a specific polymer compound having a rigid and curved molecular structure and a specific organic solvent, which allows gelation without cooling to 5°C or below.

[0101] The temperature to be maintained is not particularly limited, but is preferably 0° C. or higher, more preferably above 5° C., even more preferably 10° C. or higher, and particularly preferably 15° C. or higher. The upper limit is preferably lower than the boiling point of the specific organic solvent and the glass transition temperature of the solution (estimated from the content ratio of the specific polymer compound to the specific organic solvent and their respective glass transition temperatures), and is, for example, preferably 60° C. or lower, more preferably 40° C. or lower, and even more preferably 30° C. or lower. The retention time is preferably, for example, 1 to 48 hours.

[0102] (Crushing process) The pulverization step is a step of pulverizing the gel obtained in the gelation step to obtain porous resin particles containing a co-crystal of a polymer compound and an organic solvent. The pulverization method is not particularly limited, and either a dry pulverization method or a wet pulverization method can be used. For dry grinding, for example, a mortar, a jet mill, a hammer mill, a pin mill, a rotary mill, a vibration mill, a planetary mill, a bead mill, or the like can be used. For wet grinding, a ball mill, a high-speed rotary grinder, a jet mill, a bead mill, an ultrasonic homogenizer, a high-pressure homogenizer, or the like can be used.

[0103] The crushing step may further include a step of drying the crushed gel. When the pulverized gel contains the specific organic solvent in a free state, the gel, whose surface area has been increased by pulverization, can be dried more efficiently, and as a result, the purity of the cocrystals in the porous resin particles can be further improved.

[0104] The method for drying the pulverized gel is not particularly limited, and known methods can be used. For example, a method of reducing pressure and / or a method of heating can be used. The drying temperature is not particularly limited, but is preferably 0 to 100°C, more preferably 0 to 50°C, even more preferably 10 to 30°C, and particularly preferably 20 to 30°C. The drying time is not particularly limited, but is preferably about one hour to one month.

[0105] The method for producing the porous resin particles of the present invention preferably further comprises a step of washing the pulverized gel with a solvent (hereinafter also referred to as "washing solvent") before drying the pulverized gel. The washing solvent is compatible with the specific organic solvent, is a poor solvent for the polymer compound, and has a lower boiling point than the specific organic solvent. Therefore, when the pulverized gel is washed with the washing solvent, the free specific organic solvent contained in the pulverized gel is diluted and replaced by the washing solvent. Furthermore, because the washing solvent is a poor solvent for the polymer compound, it is less likely to destroy the structure of the resulting porous resin particles. When the specific organic solvent contained in the gel is diluted and replaced with a washing solvent, the drying time of the porous resin particles can be further shortened.

[0106] Such a washing solvent may be appropriately selected depending on the relationship with the specific polymer compound and the specific organic solvent. Examples of the washing solvent include water and alcohol, and alcohols having 3 or less carbon atoms are particularly preferred, such as methanol, ethanol, 1-propanol, and 2-propanol.

[0107] The washing method is not particularly limited, and may be a method of directly contacting the pulverized gel with a washing solvent. On the other hand, the washing solvent is compatible with the specific organic solvent and is a poor solvent for the specific polymer compound. Therefore, it is preferable to first suspend the pulverized gel in the specific organic solvent and then contact the suspension with the washing solvent to wash the particles, since this allows for more efficient exchange of the free (excess) specific organic solvent with the washing solvent. Examples of washing methods include adding a washing solvent to a suspension containing the pulverized gel, stirring the mixture, and then centrifuging the mixture to recover the solid content. This method may be repeated two or more times.

[0108] The content of the gel in the suspension is not particularly limited, but is preferably 8 to 25% by mass. By going through the above process, the average particle size is 15 μm or less and the specific surface area is 5 m 2 / g or more of porous resin particles are obtained.

[0109] [Nanoparticle precipitation method or polymerization-induced phase separation method] The porous resin particles may be produced by a nanoparticle precipitation method or a polymerization-induced phase separation method, which may be any known method. In the nanoparticle precipitation method, for example, a specific polymer compound is dissolved in a good solvent to prepare a solution, and the solution is then dropped into a poor solvent to produce nanoparticles with an average particle size of 15 μm or less and a specific surface area of ​​5 m 2 / g or more of porous resin particles are obtained. In the polymerization-induced phase separation method, for example, polymerizable monomers that make up a specific polymer compound are mixed with a non-polymerizable liquid (pore-forming agent), and the polymerizable monomers are polymerized in the mixture to induce phase separation, resulting in the formation of particles with an average particle size of 15 μm or less and a specific surface area of ​​5 m 2 / g or more of porous resin particles are obtained.

[0110] Next, the porous resin particles obtained by any one of the methods selected from the high-density crystallization method, nanoparticle precipitation method, and polymerization-induced phase separation method are mixed with the dispersion medium described above to obtain a white composition containing porous resin particles.

[0111] When producing a white ink, it is preferable to produce porous resin particles by either the high-density crystallization method or the nanoparticle precipitation method, mix the porous resin particles as a dispersoid with a resin as a dispersion medium, and optionally mix one or more additives to obtain the white ink, which makes it easier to achieve the desired whiteness of the ink.

[0112] In order to further improve whiteness, it is preferable to further mix inorganic oxide particles in addition to the porous resin particles and resin when producing a white ink. The inorganic oxide particles are preferably composed of one or more particles selected from titanium oxide, cerium oxide, zirconium oxide, zinc oxide, tin oxide, indium tin oxide, tungsten oxide, tantalum oxide, niobium oxide, and germanium oxide.

[0113] When producing a white aqueous dispersion, it is preferable to produce porous resin particles by a nanoparticle precipitation method, mix the porous resin particles as a dispersoid with water as a dispersion medium, and optionally add one or more additives to obtain a white aqueous dispersion, which makes it easier to achieve the desired whiteness of the aqueous dispersion.

[0114] When producing a white aqueous dispersion, it is preferable to further mix the above inorganic oxide fine particles in addition to the porous resin particles and resin, from the viewpoint of further improving whiteness.

[0115] When producing a white paint, it is preferable to produce porous resin particles by any method selected from the group consisting of high-density crystallization, nanoparticle precipitation, and polymerization-induced phase separation, and then mix the porous resin particles (dispersoid) with a resin (dispersion medium), and optionally add one or more additives to obtain the white paint. This makes it easier to achieve the desired whiteness of the paint.

[0116] When producing a white paint, it is preferable to further mix the above inorganic oxide fine particles in addition to the porous resin particles and resin, from the viewpoint of further improving whiteness.

[0117] By going through the above steps, a white composition containing porous resin particles is obtained.

[0118] The brightness L of the porous resin particle-containing white composition produced by the above-mentioned production method * is preferably 20 or more.

[0119] For example, when the porous resin particle-containing white composition is a white ink, the lightness L * is preferably 30 or more, more preferably 40 or more, and even more preferably 60 or more. In addition, when the white ink contains inorganic oxide fine particles, the lightness L * is preferably 30 or more, more preferably 40 or more, and even more preferably 60 or more.

[0120] When the porous resin particle-containing white composition is a white water dispersion, the lightness L * is preferably 20 or more, more preferably 25 or more.

[0121] When the porous resin particle-containing white composition is a white paint, the lightness L of the white paint * is preferably 50 or more, more preferably 60 or more. When the white paint contains inorganic oxide fine particles, the lightness L * is preferably 60 or more, more preferably 80 or more. [Example]

[0122] Examples of the present invention will be described below. The present invention is not limited to the examples shown below. In the examples, unless otherwise specified, the units of values ​​in the tables are mass (g).

[0123] (Production of porous resin particles by high-density crystallization method) (Production Example 1) 10.0 g of polyethersulfone powder (manufactured by Sumitomo Chemical Co., Ltd., product name "Sumikaexcel 3600P") was added to 90.0 g of nitrobenzene (10% by mass) and dissolved under heating and stirring (100°C, 15 minutes) to obtain a solution. The Hansen solubility parameters for the dispersion term, polarization term, hydrogen bond term, and boiling point of the nitrobenzene were (20.0, 10.6, 3.1, 210.9). Next, the solution was allowed to cool naturally with stirring (room temperature: 25°C).

[0124] After leaving the solution at room temperature overnight, crystallization occurred, causing the solution to become cloudy. This cloudy solution was added dropwise to 1000 mL of methanol at room temperature. After stirring for another hour at room temperature, the slurry solution was mixed in a thin-film vortex high-speed mixer (Primix Corporation, equipment name "Filmix 56-L") at a speed of 10 m / s for 5 minutes and then at 30 m / s for 5 minutes, and the resulting precipitate was collected by vacuum filtration. Finally, the particles were vacuum dried overnight at room temperature, and the dried porous resin particles (PMP14) were collected.

[0125] (Production Example 2) 2.0 g of polyethersulfone powder (manufactured by Sumitomo Chemical Co., Ltd., product name "Sumikaexcel 3600P") was added to 18.0 g of nitrobenzene (10% by mass), and the mixture was stirred under heating (150°C, 15 minutes) to dissolve the powder, obtaining a solution. Next, this solution was allowed to cool naturally under stirring (room temperature: 25°C) to obtain a seed solution.

[0126] 18.0 g of polyethersulfone powder (manufactured by Sumitomo Chemical Co., Ltd., product name "Sumikaexcel 3600P") was added to 62.0 g of nitrobenzene and dissolved under heating and stirring (150 °C, 15 minutes) to obtain a solution. Next, this solution was kept at 90 °C and the seed solution was added dropwise under stirring to obtain a 20 mass % solution, which was then allowed to cool to room temperature (room temperature was 25 °C) while stirring. After standing overnight at room temperature, the solution solidified into a white gel. After crushing the gel, 40 g of nitrobenzene was added, and the resulting fluid slurry was added dropwise to 1000 mL of methanol at room temperature. The resulting slurry was mixed in a thin-film vortex-type high-speed mixer (Primix Corporation, Filmix 56-L) at a speed of 10 m / s for 5 minutes and then at 30 m / s for 5 minutes. The precipitate was then collected by centrifugation (3500 rpm, 5 min). This methanol washing and centrifugation recovery was repeated three times to remove excess nitrobenzene, and after further washing with ultrapure water, the particles were vacuum dried at room temperature overnight, and the dried porous resin particles (PMP28) were recovered.

[0127] (Production of porous resin particles by nanoparticle precipitation method) (Production Example 3) 10.0 g of polyethersulfone powder (manufactured by Sumitomo Chemical Co., Ltd., product name "Sumikaexcel 3600P") was added to 190.0 g of γ-butyrolactone (5% by mass) and dissolved under heating and stirring (100°C, 15 minutes) to obtain a solution. Next, the polyethersulfone solution was allowed to cool to room temperature and then added dropwise to an equal volume of methanol to produce a solution with a solid content of 2.5% by mass. After adding 320 g of methanol and 1280 g of water to the solution, the solid matter was separated by centrifugation (6000 rpm, 30 minutes), washed with pure water, and finally vacuum dried at room temperature overnight to recover the dried porous resin particles (NP16).

[0128] (Production Example 4) 10.0 g of polyethersulfone powder (manufactured by Sumitomo Chemical Co., Ltd., product name "Sumikaexcel 3600P") was added to 190.0 g of γ-butyrolactone (5% by mass) and dissolved under heating and stirring (100°C, 15 minutes) to obtain a solution. Next, this solution was added dropwise to an equal volume of water to prepare a solids-containing aqueous solution with a solids content of 2.5% by mass. The pH of this solid-containing aqueous solution was adjusted to 10 using an aqueous sodium hydroxide solution, and the solid was separated by centrifugation (3500 rpm, 5 min). This process of washing with ultrapure water was repeated until the pH of the aqueous solution reached 7. The resulting aqueous solution was centrifuged (6000 rpm, 30 min) to separate the solid. Finally, the solution was vacuum dried at room temperature overnight, and the dried porous resin particles (NP40) were collected.

[0129] (Production of porous resin particles by polymerization-induced phase separation method) (Production Example 5) 5.6 mL of styrene monomer liquid (Nacalai Tesque) was passed through a basic column to remove the polymerization inhibitor, then dispersed in 17 mL of water. The mixture was purged with dry nitrogen for at least 5 minutes and then stirred in an oil bath at 70 °C. A polymerization initiator solution consisting of 90 mg of the polymerization initiator 4,4'-azobis(4-cyanovaleric acid) (Fujifilm Wako Pure Chemical Industries, Ltd.), 50.0 mg of sodium hydroxide, and 5.0 g of water was added and reacted overnight at 70 °C. Cloudiness appeared within 2 hours of the start of the reaction, indicating the progress of the reaction. After reacting overnight at 70 °C, the mixture was allowed to cool to room temperature, 50 mL of methanol was added, and the solid was separated by suction filtration. The solid was washed with methanol and finally vacuum dried at room temperature overnight. The dried porous resin particles (PS-1) were recovered.

[0130] (Production of white ink containing porous resin particles) Example 1 10.0 g of rosin-modified phenolic resin and 6.0 g of polymerized linseed oil were mixed at 130° C. to obtain 16.0 g of varnish for ink evaluation. 0.4 g of porous resin particles 1 (PMP14) obtained in Production Example 1 and 1.6 g of varnish were placed on the glass plate of a Huber-Muller tester, mixed with a spatula, and then rotated 100 times at 100 rpm. The mixture that had spread across the entire glass plate was then collected with a spatula and rotated 100 times at 100 rpm. This process was repeated three times to obtain the porous resin particle-containing white ink of Example 1.

[0131] Example 2 A white ink containing porous resin particles was obtained in the same manner as in Example 1, except that the porous resin particles (PMP28) obtained in Production Example 2 were used.

[0132] Example 3 A white ink containing porous resin particles was obtained in the same manner as in Example 1, except that the porous resin particles (NP16) obtained in Production Example 3 were used.

[0133] Example 4 A white ink containing porous resin particles was obtained in the same manner as in Example 1, except that the porous resin particles (NP40) obtained in Production Example 4 were used.

[0134] Example 5 A white ink containing porous resin particles was obtained in the same manner as in Example 2, except that the mixing ratios of the porous resin particles (PMP28), rosin-modified phenolic resin, and polymerized linseed oil were changed to the values ​​in Table 1.

[0135] Example 6 A white ink containing porous resin particles was obtained in the same manner as in Example 4, except that the mixing ratios of the porous resin particles (NP40), rosin-modified phenolic resin, and polymerized linseed oil were changed to the values ​​in Table 1.

[0136] (Manufacturing ink containing hollow resin particles) (Comparative Example 1) An ink containing hollow resin particles was obtained in the same manner as in Example 1, except that hollow resin particles made of styrene-acrylic resin (manufactured by The Dow Chemical Company, trade name "Ropeake (registered trademark) OP-62") were used. The hollow resin particles used in Comparative Example 1 had an average particle diameter (average outer diameter) of 0.5 μm and a calculated average inner diameter of 0.4 μm.

[0137] (Production of ink containing porous resin particles) (Comparative Example 2) A porous resin particle-containing ink was obtained in the same manner as in Example 1, except that the porous resin particles obtained in Preparation Example 2 described in JP 2014-111728 A were used.

[0138] The inks obtained in Examples 1 to 6 and Comparative Examples 1 and 2 were measured and evaluated by the following methods.

[0139] [Evaluation method] (Average particle size) The average particle diameters of the porous resin particles and hollow resin particles were measured using a laser diffraction / scattering particle size distribution analyzer (manufactured by Microtrack Bell, device name "MT-3300EX II"). As for the measurement conditions, ethanol was used as the solvent, and the concentration was adjusted to within the appropriate range for the above-mentioned device.

[0140] (specific surface area) The specific surface area of ​​the porous resin particles was measured using a gas adsorption measurement device (Microtrack-Bell, device name "Belsorp-max"). For the hollow resin particles used in Comparative Example 1, the specific surface area was calculated using the measured average particle diameter. The measurement conditions were N2 gas adsorption method, and N2 was set at 77K.

[0141] (pore volume) The pore volume of the porous resin particles was measured using the gas adsorption measuring device under the same measuring conditions as for the specific surface area.

[0142] (Average pore diameter) The value at 50% pore volume in the pore volume measurement was taken as the average pore diameter of the porous resin particles.

[0143] (brightness) The obtained white ink containing porous resin particles, ink containing hollow resin particles, or ink containing porous resin particles was heated and poured between glass plates with a gap of 62 μm as shown in Figure 4 to obtain a glass cell for measuring white density. With commercially available black paper placed on the opposite side of the obtained cell, the lightness L was measured using a spectrophotometer (manufactured by Suncolor, device name "DataColor650") * In order to eliminate the influence of the glass cell, the lightness L was calculated by subtracting the reflectance of the glass cell before the ink was poured from the reflectance obtained by the spectrophotometer. *The lightness L * was calculated from the reflection component obtained by subtracting the reflection component of the glass cell / black paper. For the ink containing porous resin particles of Comparative Example 2, the brightness L * was estimated.

[0144] Lightness L * When the value was 40 or more, it was rated as extremely good (◎), when it was 30 or more but less than 40, it was rated as good (◯), when it was 20 or more but less than 30, it was rated as slightly poor (△), and when it was less than 20, it was rated as poor (×).

[0145] (Saturation) Using the above spectrophotometer, chromaticity a * , b * Measure C * =((a * ) 2 +(b * ) 2 ) 1 / 2 From the formula, chromaticity C * The results are shown in Table 1.

[0146] [Table 1]

[0147] Representative electron microscope images of the appearance of porous resin particles produced by the high-density crystallization method of Production Example 2 are shown in Figures 5(a) and 5(b), and representative electron microscope images of the appearance of porous resin particles produced by the nanoparticle precipitation method of Production Example 4 are shown in Figures 6(a) and 6(b). As shown in Figures 5(a) and 5(b), when porous resin particles are produced by the high-density crystallization method, it was found that the porous resin particles have an almost spherical shape and a connected structure in which the particles are adhered to each other. Furthermore, as shown in Figures 6(a) and 6(b), when porous resin particles were produced by the nanoparticle precipitation method, it was found that the porous resin particles had a spherical shape and had a connected structure in which the particles were adhered to each other.

[0148] Furthermore, from the results in Table 1, the porous resin particle-containing white inks of Examples 1 to 6 had an average particle diameter of 15 μm or less and a specific surface area of ​​5 m 2 / g or more, the lightness L * It was found that the value was 30 or more, and high whiteness was exhibited.

[0149] On the other hand, the ink containing hollow resin particles in Comparative Example 1 contained hollow resin particles instead of porous resin particles, and therefore exhibited poor whiteness. Furthermore, the ink containing porous resin particles of Comparative Example 2 had an average particle size of 20 μm and was inferior in whiteness.

[0150] In addition, two types of white inks containing porous resin particles were produced in the same manner as in Example 2, except that the concentrations of the porous resin particles (PMP28) obtained in Production Example 2 were set to 20% by mass and 36.4% by mass, respectively, when the total mass of the white ink containing porous resin particles was taken as 100% by mass. * was measured. Similarly, two types of white inks containing porous resin particles were produced in the same manner as in Example 4, except that the concentrations of the porous resin particles (NP40) obtained in Production Example 4 were 20% by mass and 45.5% by mass, respectively, when the total mass of the white ink containing porous resin particles was taken as 100% by mass. * was measured.

[0151] As a result, when the concentration of the porous resin particles (PMP28) obtained in Production Example 2 was 20 mass % or 36.4 mass %, the brightness L * were 39.3 and 62.8, respectively, and it was found that the whiteness was further improved by increasing the concentration of porous resin particles. Similarly, when the concentration of the porous resin particles (NP40) obtained in Production Example 4 was 20 mass % or 45.5 mass %, the lightness L * were 45.3 and 61.3, respectively, and it was found that the whiteness was further improved by increasing the concentration of porous resin particles.

[0152] (Production of Porous Resin Particle-Containing White Water Dispersion) Example 7 2.0 g of porous particles 1 (NP16) obtained in Production Example 3, 1.0 g of dispersant (BYK-190), 2.0 g of glycerin, 3.0 g of 1,3-butanediol, 12.0 g of ion-exchanged water, and 100 g of zirconia beads were placed in a plastic bottle and shaken in a paint conditioner for 90 minutes. The zirconia beads were then removed, yielding a white aqueous dispersion containing porous resin particles.

[0153] Example 8 A white aqueous dispersion containing porous resin particles was obtained in the same manner as in Example 7, except that the porous particles 1 (NP40) obtained in Production Example 4 were used.

[0154] (Production of aqueous dispersion containing hollow resin particles) (Comparative Example 3) An aqueous dispersion containing hollow resin particles was obtained in the same manner as in Example 7, except that hollow resin particles made of styrene-acrylic resin (manufactured by The Dow Chemical Company, trade name "Ropeake (registered trademark) OP-62") were used.

[0155] [Evaluation method] (brightness) The obtained porous resin particle-containing white water dispersion or hollow resin particle-containing water dispersion was heated and poured between glass plates with a gap of 10 μm as shown in FIG. 4 to obtain a glass cell for measuring white density. With commercially available black paper placed on the opposite side of the obtained cell, the brightness L was measured using the above spectrophotometer. * In order to eliminate the influence of the glass cell, the lightness L was calculated by subtracting the reflectance of the glass cell before the ink was poured from the reflectance obtained by the spectrophotometer. * The lightness L * was calculated using the reflection component minus the reflection component of the glass cell / black paper.

[0156] Lightness L * When the value was 40 or more, it was rated as extremely good (⊚), when it was 20 or more but less than 40, it was rated as good (◯), and when it was less than 20, it was rated as poor (x).

[0157] (Saturation) Using the above spectrophotometer, chromaticity a* , b * Measure C * =((a * ) 2 +(b * ) 2 ) 1 / 2 From the formula, saturation C * The results are shown in Table 2.

[0158] [Table 2]

[0159] From the results in Table 2, the porous resin particle-containing white water dispersions of Examples 7 and 8 had an average particle size of 15 μm or less and a specific surface area of ​​5 m 2 / g or more, the lightness L * is 20 or more, and saturation C * It was found that the thickness was small and high whiteness was exhibited.

[0160] On the other hand, the hollow resin particle-containing aqueous dispersion of Comparative Example 3 contained hollow resin particles instead of porous resin particles, and was inferior in whiteness.

[0161] (Production of white paint containing porous resin particles) Example 9 0.393 g of porous resin particles 1 (PMP14) obtained in Production Example 1, 15.0 g of acrylic water-based paint Pasta Clear W, and 40 g of glass beads were placed in a plastic bottle, shaken in a paint conditioner for 60 minutes, and the glass beads were removed to obtain the porous resin particle-containing white paint of Example 9.

[0162] Example 10 A white paint containing porous resin particles was obtained in the same manner as in Example 9, except that the porous resin particles (PMP28) obtained in Production Example 2 were used.

[0163] Example 11 A white paint containing porous resin particles was obtained in the same manner as in Example 9, except that the porous resin particles (NP16) obtained in Production Example 3 were used.

[0164] Example 12 A white paint containing porous resin particles was obtained in the same manner as in Example 9, except that the porous resin particles (NP40) obtained in Production Example 4 were used.

[0165] (Manufacturing paint containing hollow resin particles) Comparative Example 4 A paint containing hollow resin particles was obtained in the same manner as in Example 7, except that hollow resin particles made of styrene-acrylic resin (manufactured by The Dow Chemical Company, trade name "Ropeake (registered trademark) OP-62") were used.

[0166] (Production of paint containing porous resin particles) (Comparative Example 5) A coating material containing porous resin particles was obtained in the same manner as in Example 9, except that the porous resin particles obtained in Preparation Example 2 described in JP 2014-111728 A were used.

[0167] [Evaluation method] (brightness) As shown in Figure 7(a), the resulting white paint containing porous resin particles, hollow resin particle-containing paint, or porous resin particle-containing paint was applied to a PET film using an applicator and dried at room temperature for 1 hour and at 140°C for 30 minutes to obtain a coating film for measuring the white density. The coating film thickness was 38 μm. With commercially available black paper placed on the PET film side of the resulting coating film, the brightness L was measured using the above spectrophotometer. * In order to eliminate the influence of the PET film, the lightness L was calculated from the value obtained by subtracting the reflectance of the PET film from the reflectance obtained by the spectrophotometer. * was calculated.

[0168] Lightness L * When the value was 60 or more, it was rated as extremely good (◎), when it was 50 or more but less than 60, it was rated as good (◯), when it was 40 or more but less than 50, it was rated as slightly poor (△), and when it was less than 20, it was rated as poor (×).

[0169] (Saturation) Using the above spectrophotometer, chromaticity a* , b * Measure C * =((a * ) 2 +(b * ) 2 ) 1 / 2 From the formula, saturation C * The results are shown in Table 3.

[0170] [Table 3]

[0171] From the results in Table 3, the porous resin particle-containing white paints of Examples 9 to 12 had an average particle diameter of 15 μm or less and a specific surface area of ​​5 m 2 / g or more, the lightness L * is 50 or more, and saturation C * It was found that the thickness was small and high whiteness was exhibited.

[0172] On the other hand, the paint containing hollow resin particles in Comparative Example 4 contained hollow resin particles instead of porous resin particles, and was inferior in whiteness. Furthermore, the porous resin particle-containing paint of Comparative Example 5 had an average particle size of 20 μm and was inferior in whiteness.

[0173] (Production of white ink containing porous resin particles) Example 13 A white ink containing porous resin particles was obtained in the same manner as in Example 2, except that the mixing ratio of porous resin particles (PMP28) was changed to the value in Table 4 and titanium oxide (manufactured by Ishihara Sangyo Kaisha, Ltd., average particle diameter 0.21 μm) was further mixed in.

[0174] Example 14 A white ink containing porous resin particles was obtained in the same manner as in Example 4, except that the mixing ratio of porous resin particles (NP40) was changed to the value in Table 4 and titanium oxide (manufactured by Ishihara Sangyo Kaisha, Ltd., average particle diameter 0.21 μm) was further mixed in.

[0175] (Manufacturing of titanium oxide-containing ink) (Comparative Example 6) A titanium oxide-containing ink was produced in the same manner as in Example 13, except that no porous resin particles were mixed. The lightness L was measured in the same manner as in Examples 1 to 6. * and saturation C * The results of the measurements and calculations are shown in Table 4. The chroma C of titanium oxide * was 2.3.

[0176] [Table 4]

[0177] From the results in Table 4, the porous resin particle-containing white paints of Examples 13 and 14 had an average particle size of 15 μm or less and a specific surface area of ​​5 m 2 / g or more, the lightness L * is 40 or more, and saturation C * It was found that the thickness was small and high whiteness was exhibited.

[0178] On the other hand, the titanium oxide-containing ink of Comparative Example 6 did not contain porous resin particles and had poor whiteness.

[0179] (Production of white paint containing porous resin particles) Example 15 A white paint containing porous resin particles was obtained in the same manner as in Example 10, except that titanium oxide (manufactured by Ishihara Sangyo Kaisha, Ltd., average particle size 0.21 μm) was further mixed.

[0180] Example 16 A white paint containing porous resin particles was obtained in the same manner as in Example 12, except that titanium oxide (manufactured by Ishihara Sangyo Kaisha, Ltd., average particle size 0.21 μm) was further mixed.

[0181] Example 17 A white paint containing porous resin particles was obtained in the same manner as in Example 15, except that the porous resin particles (PS-1) of Production Example 5 were used and mixed according to the values ​​in Table 5.

[0182] (Manufacturing titanium dioxide-containing paints) (Comparative Example 7) A titanium oxide-containing paint was produced in the same manner as in Example 15, except that porous resin particles were not mixed. * was 7.8.

[0183] [Evaluation method] (brightness) As shown in Figure 7(b), the resulting white paint containing porous resin particles, the paint containing hollow resin particles, or the paint containing porous resin particles was directly applied to black paper using an applicator, and then dried at room temperature for 1 hour and at 140°C for 30 minutes to obtain a coating film for measuring the white density. The coating film thickness was 35 μm.

[0184] The lightness L* was measured using the above spectrophotometer. * When the value was 80 or more, it was rated as good (◯), when it was 60 or more but less than 80, it was rated as slightly poor (△), and when it was less than 60, it was rated as poor (×).

[0185] (Saturation) Using the above spectrophotometer, chromaticity a * , b * Measure C * =((a * ) 2 +(b * ) 2 ) 1 / 2 From the formula, saturation C * The results are shown in Table 5.

[0186] [Table 5]

[0187] As a representative example, electron microscope images of the appearance of the porous resin particles produced by the polymerization-induced phase separation method of Production Example 5 are shown in FIGS. 8(a) and 8(b). As shown in FIGS. 8(a) and 8(b), it was found that when the porous resin particles were produced by the polymerization induced phase separation method, the porous resin particles had a spherical shape.

[0188] The appearance of the porous resin particles after mixing and dispersion in Example 15 is shown in Figure 9, the appearance of the porous resin particles after mixing and dispersion in Example 16 is shown in Figure 10, and the appearance of the porous resin particles after mixing and dispersion in Example 17 is shown in Figure 11.

[0189] As shown in Figure 9, when titanium oxide was mixed with porous resin particles produced by the high-density crystallization method, the interconnected structure of the porous resin particles was largely maintained. It was also confirmed that multiple titanium oxide particles were attached to the porous resin particles, and that some of the titanium oxide particles had penetrated into the porous resin particles.

[0190] Furthermore, when titanium oxide was mixed with porous resin particles produced by the nanoparticle precipitation method, the interconnected structure of the porous resin particles was broken down, as shown in Figure 10. It was also confirmed that some of the titanium oxide particles were adsorbed onto the broken down porous resin particles.

[0191] Furthermore, as shown in Figure 11, when titanium oxide was mixed with porous resin particles produced by polymerization-induced phase separation, a simple mixture of porous resin particles and titanium oxide particles was confirmed to be formed.

[0192] Furthermore, from the results in Table 5, the porous resin particle-containing white paints of Examples 15 to 17 had an average particle diameter of 15 μm or less and a specific surface area of ​​5 m 2 / g or more, the lightness L * is 80 or more, and saturation C * It was found that the thickness was small and high whiteness was exhibited.

[0193] On the other hand, the titanium oxide-containing paint of Comparative Example 7 did not contain porous resin particles and was inferior in whiteness.

[0194] In particular, the titanium oxide-equivalent concentrations of the porous resin particle-containing white paints of Examples 16 and 17 were 4.1% and 4.4%, respectively, which were significantly higher than the titanium oxide-equivalent concentration of 2.5% of the titanium oxide-containing paint of Comparative Example 7. This indicates that by adding porous resin particles instead of increasing the titanium oxide content in the titanium oxide-containing paint, the brightness L of the paint can be increased while suppressing the content of titanium oxide, which has a large mass. * It was found that it can be improved sufficiently. [Explanation of symbols]

[0195] 1A White composition containing porous resin particles 1B White composition containing porous resin particles 2 Porous resin particles 3 Dispersion medium 4 Inorganic oxide fine particles

Claims

1. Average particle diameter 15μm or less, specific surface area 5m ２ / g or more porous resin particles and a dispersion medium, the porous resin particles contain a polymer compound, The polymer compound has at least a repeating unit represented by the following formula 1A: 【Chemistry 1】 In formula 1A, L 1 , L 2 , and L 3 each independently represent a single bond or a divalent group, R 1 , R 2 , and R 3 each independently represent a monovalent substituent, or x, y, and z each independently represent an integer of 0 to 4, m represents an integer of 0 or more, n represents an integer of 0 to 10, when n is 0, m is an integer of 1 or more, and when n≠0, p represents an integer of 1 to 3, L 1 , L 2 , and L 3 may be the same or different, R 1 , R 2 , and R 3 may be the same or different, and R 1 and R 2 may be bonded to each other to form a ring.

2. The pore diameter of the porous resin particles is 200 nm or less, and the pore volume is 0.03 cm ３ The porous resin particle-containing white composition according to claim 1, wherein the porous resin particle-containing white composition has a viscosity of 1000 MPa or more.

3. 3. The porous resin particle-containing white composition according to claim 1, wherein the difference Δn between the refractive index of the porous resin particles and the refractive index of the dispersion medium is 0.10 or more and 1.0 or less.

4. 4. The porous resin particle-containing white composition according to claim 1, wherein the porous resin particles are made of a crystalline resin.

5. 5. The porous resin particle-containing white composition according to claim 1, wherein the porous resin particles have a spherical shape.

6. The porous resin particle-containing white composition according to claim 1 , further comprising inorganic oxide fine particles.

7. 7. The porous resin particle-containing white composition according to claim 6, wherein the inorganic oxide fine particles are composed of one or more inorganic oxide fine particles selected from the group consisting of titanium oxide, cerium oxide, zirconium oxide, zinc oxide, tin oxide, indium tin oxide, tungsten oxide, tantalum oxide, niobium oxide, and germanium oxide.

8. 8. The porous resin particle-containing white composition according to claim 6, wherein one or more of the inorganic oxide fine particles are supported on the porous resin particles.

9. the dispersion medium is water, 9. The porous resin particle-containing white composition according to claim 1, wherein the porous resin particle-containing white composition is a white aqueous dispersion.

10. The lightness L of the white water dispersion ＊ The porous resin particle-containing white composition according to claim 9, wherein the σ is 20 or more.

11. the dispersion medium is a resin, The porous resin particle-containing white composition according to any one of claims 1 to 8, wherein the porous resin particle-containing white composition is a white ink or a white paint.

12. The lightness L of the white ink ＊ The porous resin particle-containing white composition according to claim 11, wherein the σ is 30 or more.

13. The lightness L of the white paint ＊ The porous resin particle-containing white composition according to claim 11, wherein the σ is 50 or more.

14. By any method selected from the high-density crystallization method, the nanoparticle precipitation method, and the polymerization-induced phase separation method, an average particle diameter of 15 μm or less and a specific surface area of ​​5 m ２ / g or more, mixing the porous resin particles with a dispersion medium to obtain a white composition containing porous resin particles; the porous resin particles contain a polymer compound, The method for producing a white composition containing porous resin particles, wherein the polymer compound has at least a repeating unit represented by the following formula 1A: 【Chemistry 2】 In formula 1A, L 1 , L 2 , and L 3 each independently represent a single bond or a divalent group, R 1 , R 2 , and R 3 each independently represent a monovalent substituent, or x, y, and z each independently represent an integer of 0 to 4, m represents an integer of 0 or more, n represents an integer of 0 to 10, when n is 0, m is an integer of 1 or more, and when n≠0, p represents an integer of 1 to 3, L 1 , L 2 , and L 3 may be the same or different, R 1 , R 2 , and R 3 may be the same or different, and R 1 and R 2 may be bonded to each other to form a ring.

15. The high-density crystallization method includes: a heating and dissolving step of heating and dissolving a polymer compound having an aromatic ring in its main chain, which may have a substituent, in an organic solvent to obtain a solution containing the polymer compound; a gelling step of cooling the solution to obtain a gel; a crushing step of crushing the gel to obtain porous resin particles containing a co-crystal of the polymer compound and the organic solvent; and The boiling point of the organic solvent is 100°C or higher, and The hydrogen bond term of the Hansen solubility parameter of the organic solvent is 7.4 MPa ０．５ or less, or the hydrogen bond term is 7.4 MPa or less ０．５ and the polarization term of the Hansen solubility parameter is 11.4 MPa. ０．５ The method for producing a porous resin particle-containing white composition according to claim 14, wherein the total mass of the porous resin particle-containing white composition is less than 10 ...

16. producing porous resin particles by either the high-density crystallization method or the nanoparticle precipitation method; 16. The method for producing a white composition containing porous resin particles according to claim 14, wherein the white ink is obtained by mixing the porous resin particles as a dispersoid with a resin as a dispersion medium.

17. The method for producing a porous resin particle-containing white composition according to claim 16, further comprising mixing inorganic oxide fine particles in addition to the porous resin particles and the resin.

18. producing porous resin particles by the nanoparticle precipitation method; 16. The method for producing a white composition containing porous resin particles according to claim 14, wherein the porous resin particles serving as a dispersoid and water serving as a dispersion medium are mixed to obtain a white aqueous dispersion.

19. producing porous resin particles by any method selected from a high-density crystallization method, a nanoparticle precipitation method, and a polymerization-induced phase separation method; 16. The method for producing a white composition containing porous resin particles according to claim 14, wherein the white paint is obtained by mixing the porous resin particles as a dispersoid with a resin as a dispersion medium.

20. 20. The method for producing a porous resin particle-containing white composition according to claim 19, further comprising mixing inorganic oxide fine particles in addition to the porous resin particles and the resin.

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