Polysiloxane particle

Abstract

Provided is a polysiloxane particle which contains therein a pigment and has high insulation properties even during particle compression.　This polysiloxane particle comprises a polysiloxane and a pigment, wherein the pigment is coated with a surface treatment agent.

Description

Polysiloxane Particles

[0001] The present invention relates to polysiloxane particles.

[0002] Liquid crystal technology has made great advances and is now used not only in conventional display devices but also in light-control materials such as light-control films for the purpose of blocking light. Generally, light-control materials are sandwiched between two glass plates or films, with spacer particles arranged to maintain a constant thickness of the light-control layer.

[0003] Typical properties required for spacer particles include particle size uniformity, electrical insulation, appropriate particle strength, and light-blocking properties. Particle size uniformity is a factor affecting device precision, insulation is a factor affecting device reliability, particle strength is a factor affecting defects due to particle breakage or intrusion into other components, and light-blocking properties are a factor affecting display quality. Various classification techniques have been developed to achieve particle size uniformity after synthesis. On the other hand, insulation, particle strength, and light-blocking properties are properties that are significantly affected by the materials and synthesis method. For example, insulation is known to be due to the polymerized monomer structure and the conductivity and loading of the pigments and dyes, and can be adjusted by selecting the polymerized monomer structure and pigments and dyes. Particle strength can be adjusted by changing the polymerized monomer structure. Light-blocking properties can be adjusted by carbonizing the particles or by encapsulating or surface-adsorbing pigments and dyes.

[0004] One of the challenges facing spacer particles is achieving both insulating and light-blocking properties. Carbon black is a typical pigment that contributes to the light-blocking properties of spacer particles. Carbon black is frequently used because it can produce a natural black color and is easily available. However, because carbon black itself is conductive, it may impair the reliability of liquid crystal devices. However, reducing the loading amount of carbon black to improve insulating properties results in insufficient light-blocking properties. Furthermore, from the perspective of insulating reliability, it is necessary for the insulating properties to be maintained even when the particles are compressed. For example, Patent Documents 1 and 2 propose polysiloxane particles with high electrical resistance that can be used as spacer particles.

[0005] JP-A No. 11-49953 JP-A No. 8-081561

[0006] However, conventional polysiloxane particles tend to become conductive when compressed, and have problems with conductivity reliability when used in environments where a load is applied. Therefore, an object of the present invention is to provide polysiloxane particles that contain a pigment and have high insulating properties even when compressed.

[0007] The present invention has been made to solve the above-mentioned problems, and the gist of the present invention is as follows: [1] Polysiloxane particles containing a polysiloxane and a pigment, the pigment being coated with a surface treatment agent. [2] A polysiloxane particle having a 20% K value of 100 N / mm ２ [3] The polysiloxane particles according to [1], wherein the compressibility at the start of voltage drop measured by electrical conductivity measurement when a single particle is compressed is 50% or more and 90% or less. [4] The polysiloxane particles according to any one of [1] to [3], wherein the pigment is carbon black and the content of the carbon black is 4% by mass or more and 10% by mass or less. [5] The polysiloxane particles according to any one of [1] to [4], wherein the surface treatment agent is a silicone-based surface treatment agent. [6] The polysiloxane particles according to any one of [1] to [5], wherein the polysiloxane is a polymer of a silicone macromonomer. [7] The background lightness L ０ The polysiloxane particles according to any one of [1] to [6], wherein when an image observed under an optical microscope having a blackness parameter value B of 75 to 80 is analyzed by the following procedures (A) to (D), the blackness parameter value B calculated by the following mathematical formula (2) is 0.04 or more. (A) Polysiloxane particles are dispersed on a slide glass, and a cover glass is placed thereon to prepare a sample for analysis. (B) The sample for analysis is observed under the optical microscope, and images of the individual polysiloxane particles are taken. (C) ImageJ is used, and the image type is set to Lab Stack, and the particle lightness L, background lightness L0, and particle diameter a (μm) of the polysiloxane particles are analyzed. (D) The blackness parameter value B is calculated using the following mathematical formula (1): B=[log(L ０ / L)] / a Formula (2) [8] The polysiloxane particles according to [7], wherein the blackness parameter value B is 0.1 or less.

[0008] According to the present invention, it is possible to provide polysiloxane particles that contain a pigment within the particles and have high insulating properties even when the particles are compressed.

[0009] The present invention will be described in more detail below using embodiments.

[0010] [Polysiloxane Particles] The polysiloxane particles of the present invention contain a polysiloxane and a pigment, and the pigment is coated with a surface treatment agent.

[0011] <Compression ratio at the start of voltage drop> The polysiloxane particles of the present invention preferably have a compression ratio of 50% or more and 90% or less at the start of voltage drop when measured by conductivity measurement during single particle compression. When the compression ratio of the polysiloxane particles at the start of voltage drop when measured by conductivity measurement during single particle compression is 50% or more, they can maintain insulating properties during particle compression. Furthermore, when the compression ratio of the polysiloxane particles at the start of voltage drop when measured by conductivity measurement during single particle compression is more than 90%, they can maintain insulating properties during particle compression, but the amount of pigment that contributes to light-blocking properties will be too small, resulting in insufficient light-blocking properties. For these reasons, the compression ratio of the polysiloxane particles at the start of voltage drop when measured by conductivity measurement during single particle compression is preferably 53% or more, more preferably 56% or more, and even more preferably 59% or more, and preferably 87% or less, more preferably 84% or less, and even more preferably 81% or less. Methods for adjusting the compressibility at which the voltage drop begins, as measured by electrical conductivity measurement during single particle compression of polysiloxane particles, to fall within the above range include a method of surface treating the pigment with a specific surface treatment agent to adjust its dispersibility in polysiloxane, a method of adjusting the pigment loading amount, and a method of selecting the type of resin used to polymerize polysiloxane.

[0012] In this specification, the compressibility at the onset of voltage drop in electrical conductivity measurements during single particle compression of polysiloxane particles can be measured as follows. Using a microcompression tester, polysiloxane particles (single particles) are compressed with a smooth cylindrical indenter end face (diameter 50 μm, gold (Au) plated) under conditions of 25°C, a compression rate of 0.3 mN / sec, and a maximum test load of 100 mN. The load value (N) and compression displacement (mm) at this time are measured. At this time, a constant current device is set to a current value of 0.01 A and a maximum voltage value of 0.33 V, and electrical properties are also measured simultaneously. The resistance value of the polysiloxane particles decreases with compression, and a sudden voltage drop is observed at a certain compression rate. The compression rate at this time is defined as the compression rate at which the voltage drop begins. As the microcompression tester, for example, an "ENT-NEXUS" manufactured by Elionix can be used. The compression ratio at the start of voltage drop measured by conductivity measurement when a single particle of polysiloxane is compressed may be determined by arithmetically averaging the compression ratios at the start of voltage drop for 50 arbitrarily selected polysiloxane particles.

[0013] <20% K value> The polysiloxane particles have a compressive elastic modulus (20% K value) of 100 N / mm when compressed by 20%. ２ Preferably, it is 85 N / mm or less. ２ More preferably, it is 70 N / mm or less. ２ When the 20% K value of the polysiloxane particles is equal to or less than the upper limit, the polysiloxane particles tend to exhibit particle strength appropriate for use as spacer particles. The 20% K value of the polysiloxane particles is not particularly limited, but from the viewpoint of easily exhibiting particle strength appropriate for use as spacer particles, it is, for example, 3 N / mm ２ More than 5N / mm ２ The 20% K value of the polysiloxane particles is an index that universally and quantitatively represents the hardness of the polysiloxane particles.

[0014] In this specification, the 20% K value of polysiloxane particles can be measured as follows. Using a microcompression tester, polysiloxane particles (single particles) are compressed with a cylindrical (diameter 50 μm, gold (Au)-plated) smooth indenter end face under conditions of 25°C, a compression rate of 0.3 mN / sec, and a maximum test load of 100 mN. The load value (N) and compression displacement (mm) at this time are measured. From the obtained measured values, the 20% K value (20% compressive elastic modulus) of the polysiloxane particles can be calculated using the following mathematical formula (1). Examples of microcompression testers that can be used include the "ENT-NEXUS" manufactured by Elionix, the "Microcompression Tester MCT-W200" manufactured by Shimadzu Corporation, and the "Fisherscope H-100" manufactured by Fischer. The 20% K value of the polysiloxane particles may be calculated by arithmetically averaging the 20% K values ​​of 50 randomly selected polysiloxane particles. ２ ) = (3 / 2 １／２ ) F.S. －３／２ ・R －１／２ Formula (1) F: Load value (N) when the polysiloxane particle is compressed and deformed by 20% S: Compression displacement (mm) when the polysiloxane particle is compressed and deformed by 20% R: Radius of the polysiloxane particle (mm)

[0015] <Blackness parameter value B> The polysiloxane particles of the present invention have a background lightness L ０ When an image observed under an optical microscope having a blackness parameter value of 75 to 80 is analyzed by the following procedures (A) to (D), it is preferable that the blackness parameter value B calculated by the following formula (2) is 0.04 or more: (A) Polysiloxane particles are dispersed on a slide glass, and a cover glass is placed thereon to prepare a sample for analysis; (B) The sample for analysis is observed under the optical microscope, and images of individual polysiloxane particles are taken; (C) ImageJ is used, the image type is set to Lab Stack, and the particle lightness L of the polysiloxane particles and the background lightness L are taken; ０ and particle diameter a (μm). (D) Calculate the blackness parameter value B using the following formula (1): B = [log(L ０ / L)] / a Formula (2) When calculating the blackness parameter value B, it is desirable that the polysiloxane particles to be observed are in the range of 10 to 50 μm. ０ If the blackness parameter B is outside the range of 75 to 80, it can be corrected using multiple analysis results with different background lightnesses. The blackness parameter value B can be calculated by analyzing 20 arbitrarily selected polysiloxane particles and using the average value. Polysiloxane particles with a blackness parameter value B of less than 0.04 indicate that the blackness of the polysiloxane particles is less than a certain level, resulting in poor light-blocking properties. For this reason, the blackness parameter value B of the polysiloxane particles is preferably 0.042 or more, more preferably 0.044 or more, even more preferably 0.046 or more, and even more preferably 0.050 or more. The blackness parameter value B of the polysiloxane particles is preferably 0.1 or less, more preferably 0.08 or less, and even more preferably 0.06 or less. Having the blackness parameter value B of the polysiloxane particles below the upper limit makes it easier to maintain insulation properties. Methods for adjusting the blackness parameter value B of polysiloxane particles to fall within the above range include a method of surface treating the pigment with a specific surface treatment agent to adjust the dispersibility in polysiloxane, a method of adjusting the pigment loading amount, and a method of selecting the type of resin used to polymerize the polysiloxane.

[0016] <Resistivity at 50% Compression> The polysiloxane particles preferably have a resistivity of 200 Ω·μm or more, more preferably 350 Ω·μm or more, and even more preferably 500 Ω·μm or more, at 50% compression. When the polysiloxane particles have a resistivity at 50% compression of at least the above-mentioned lower limit, the conductivity reliability can be improved when used in an environment where a load is applied.

[0017] In this specification, the resistivity of polysiloxane particles when compressed to 50% can be measured as follows: Using a microcompression tester, polysiloxane particles (single particles) are compressed with the end face of a cylindrical (diameter 50 μm, gold (Au) plated) smooth indenter under conditions of 25° C., a compression speed of 0.3 mN / sec, and a maximum test load of 100 mN, and the resistance value R when compressed to 50% is measured by a four-terminal method. ２ ) and the distance between electrodes (μm) (particle radius (μm)) at 50% compression are measured. From the measured values ​​obtained, the resistivity ρ of the polysiloxane particles at 50% compression can be calculated using the following formula (3). For example, an "ENT-NEXUS" manufactured by Elionix can be used as the microcompression tester. Resistivity ρ (Ω μm) = R (Ω) × S (μm ２ ) / L (μm) = R (Ω) x πr ２ (μm ２ ) / r (μm) = πrR Formula (3) ρ: resistivity R: resistance value S: particle cross-sectional area L: distance between electrodes when compressed 50% (r: particle radius)

[0018] <Transmittance at a wavelength of 550 nm> The polysiloxane particles preferably have a transmittance at a wavelength of 550 nm of 50% or less, more preferably 40% or less, and even more preferably 30% or less. When the polysiloxane particles have a transmittance at a wavelength of 550 nm of the above upper limit or less, the desired light-blocking properties are achieved.

[0019] In this specification, the transmittance of polysiloxane particles at a wavelength of 550 nm can be measured as follows. Polysiloxane particles with a median particle size of 15 μm and a CV value of 10% are mixed with a curable silicone resin and dispersed using ultrasonic waves to obtain a dispersion. The obtained dispersion is applied to a slide glass ("Preclean Slide Glass S7213" manufactured by Matsunaga Glass Co., Ltd.) to a film thickness of 180 to 200 μm to form a coating film. The coating film is cured at 100°C for 4 hours, and then the transmittance is measured using an integrating sphere attachment ("U-4100" manufactured by Hitachi, Ltd.).

[0020] <Particle size> The particle size of the polysiloxane particles is preferably 1 μm or more, more preferably 3 μm or more, and even more preferably 10 μm or more. Furthermore, the particle size of the polysiloxane particles is preferably 150 μm or less, more preferably 100 μm or less, and even more preferably 50 μm or less. When the particle size of the polysiloxane particles is above the above-mentioned lower limit and below the above-mentioned upper limit, they can be used as spacer particles to maintain the distance between two substrates such as glass plates and films in liquid crystal display devices and light-adjusting materials, thereby maintaining the thickness of the liquid crystal layer at a certain distance or more. As a result, the light-adjusting performance of liquid crystal display devices and light-adjusting materials, which adjusts the amount of incident light, haze, etc., can be more effectively improved. Furthermore, when the particle size of the polysiloxane particles is above the above-mentioned lower limit and below the above-mentioned upper limit, the occurrence of color unevenness in liquid crystal display devices and light-adjusting materials can be more effectively suppressed. The particle size of the polysiloxane particles can be appropriately set depending on the application.

[0021] [Pigment] The pigment contributes to the light-shielding properties of the polysiloxane particles. It is preferable to use a pigment that causes a voltage drop at a compression rate of 90% or less when measuring the electrical conductivity of polysiloxane particles containing the pigment during single particle compression. From this perspective, examples of pigments include carbon black, carbon nanotubes, graphene, graphite, titanium nitride, titanium black, iron oxide, zinc oxide, boron carbide, copper-chromium composite oxide, copper-chromium-zinc composite oxide, zirconium carbide, zirconium boride, tungsten carbide, tungsten disulfide, silver, aluminum, calcium carbonate, alumina, potassium clay, calcium silicate, magnesium oxide, aluminum hydroxide, magnesium carbonate, talc, mica, baryte, barium carbonate, titanium oxide, and silica. Carbon black and graphene are preferred, and carbon black is particularly preferred. Furthermore, the pigment may be a pigment that is not electrically conductive and does not cause the voltage drop, or an organic black pigment may be used. From the viewpoint of increasing the blackness parameter value B, the pigment is preferably a black pigment such as titanium black, carbon black, or an organic black pigment, and among these, carbon black is more preferable. The above pigments may be used alone or in combination of two or more kinds.

[0022] The carbon black is not particularly limited, but examples thereof include channel black, roll black, furnace black, thermal black, ketjen black, acetylene black, etc. The carbon black may be used alone or in combination of two or more types.

[0023] The average particle size of the pigment is preferably 10 nm or more, more preferably 50 nm or more, and even more preferably 100 nm or more, and is preferably 500 nm or less, more preferably 300 nm or less, and even more preferably 100 nm or less. When the average particle size of the pigment is equal to or greater than the above-mentioned lower limit and equal to or less than the above-mentioned upper limit, the dispersibility of the pigment is further improved, and the pigment can be mixed more uniformly with the polysiloxane particles.

[0024] The pigment is coated with a surface treatment agent. When the pigment is surface-treated with the surface treatment agent, the surface treatment agent bonds or adheres to the surface of the pigment, thereby coating the pigment, and the dispersibility of the pigment in the polysiloxane particles is improved, allowing the pigment to have high insulating properties when compressed. The light-blocking properties of the resulting polysiloxane particles are also improved. Furthermore, the pigment loading amount in the polysiloxane particles can be increased, making it easier to increase, for example, the blackness parameter value B. Among the above pigments, carbon black is preferably used because it can express a natural black color and is easily available, and the carbon black is preferably coated with a surface treatment agent. Details of the surface treatment agent will be described later.

[0025] The content of the pigment (for example, carbon black when the pigment is carbon black) in the polysiloxane particles is, for example, 0.5% by mass or more and 12% by mass or less, preferably 4% by mass or more and 10% by mass or less, more preferably 4.5% by mass or more and 9% by mass or less, and even more preferably 5% by mass or more and 8% by mass or less. By making the content of the pigment (carbon black) equal to or greater than the lower limit, it is possible to impart appropriate light-blocking properties to the polysiloxane particles. Furthermore, by making the content equal to or less than the upper limit, it becomes easier to ensure insulation properties and also to increase the compressibility at the start of the voltage drop.

[0026] [Polysiloxane] The polysiloxane particles contain polyorganosiloxane. In the polysiloxane particles, polyorganosiloxane may be the main component, and its content is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more. When the content of polyorganosiloxane is equal to or more than the above lower limit, the polysiloxane particles can be imparted with appropriate particle strength and insulating properties. In addition, the content of polyorganosiloxane in the polysiloxane particles is, for example, 99.5% by mass or less, preferably 99% by mass or less, more preferably 98% by mass or less, and even more preferably 96% by mass or less, from the viewpoint of containing a certain amount or more of other components such as pigments.

[0027] The polyorganosiloxane in the polysiloxane particles is preferably composed of a material obtained by polymerizing the monomer components described below. Therefore, the polyorganosiloxane is preferably composed of a polymer of a silicone macromonomer. Furthermore, when the surface treatment agent is polyorganosiloxane, it is preferable that the surface treatment agent also contains polyorganosiloxane in addition to the polymerized monomer components.

[0028] [Method for Producing Polysiloxane Particles] Polysiloxane particles can be obtained by, without particular limitation, uniformly mixing and dispersing the pigment in the monomer component and polymerizing the resulting mixture. Here, it is preferable to further add a surface treatment agent to the monomer component. The polymerization method is not particularly limited, and polymerization can be carried out by known methods such as radical polymerization, ionic polymerization, polycondensation (condensation polymerization, polycondensation), addition condensation, living polymerization, and living radical polymerization. Examples of such methods include suspension polymerization in the presence of a radical polymerization initiator, as well as seed polymerization and dispersion polymerization, which involve swelling and polymerizing monomers using non-crosslinked seed particles together with a radical polymerization initiator. Among these, suspension polymerization is preferred. In suspension polymerization, the monomer component, pigment, and optionally a surface treatment agent are dispersed in an aqueous solvent such as water, and the polymerization reaction is carried out in the presence of a radical polymerization initiator. It is also preferable to add a dispersing aid such as gelatin, starch, polyvinyl alcohol, or carboxymethyl cellulose to the aqueous solvent. The use of a dispersing aid stabilizes the monomer droplets, allowing polysiloxane particles of an appropriate particle size to be obtained. The dispersing aid is preferably polyvinyl alcohol.

[0029] The monomer component used is a component that becomes a polyorganosiloxane upon polymerization, specifically a silane compound. Examples of the silane compound include silane compounds having an alkenyl group such as a vinyl group, or an ethylenically unsaturated group such as a (meth)acryloyl group. The monomer component is preferably a silicone macromonomer. Examples of the silicone macromonomer include organopolysiloxanes having an ethylenically unsaturated group, preferably an organopolysiloxane having a (meth)acryloyl group. The ethylenically unsaturated group may be located in a side chain or at a terminal. The number of ethylenically unsaturated groups in one molecule is preferably two or more, about 2 to 6, more preferably 2 to 4, and even more preferably 2. It is even more preferable to have ethylenically unsaturated groups at both terminals.

[0030] The silicone macromonomer may be a linear or branched organopolysiloxane, or a mixture of linear and branched organopolysiloxanes, but is preferably a linear organopolysiloxane. In the silicone macromonomer, examples of the residual groups bonded to the silicon atom other than the ethylenically unsaturated group include hydrocarbon groups such as alkyl groups such as methyl, ethyl, propyl, butyl, hexyl, and dodecyl, aryl groups such as phenyl, and aralkyl groups such as 2-phenylethyl and 2-phenylpropyl. Further examples include halogen-substituted hydrocarbon groups such as chloromethyl and 3,3,3-trifluoropropyl. Of these, hydrocarbon groups are preferred, and methyl groups are more preferred, from the standpoint of ease of synthesis. Furthermore, of the residual groups bonded to the silicon atom, preferably 80 mol % or more are methyl groups, more preferably 90 mol % or more are methyl groups, and even more preferably 100 mol % are methyl groups. Specifically, the silicone macromonomer is preferably an organopolysiloxane containing vinyl groups at both ends or an organopolysiloxane containing (meth)acryloyl groups at both ends, with organopolysiloxanes containing (meth)acryloyl groups at both ends being more preferred. The number-average molecular weight of the silicone macromonomer is preferably 200 to 5,000, more preferably 300 to 4,500, and even more preferably 400 to 4,000. In this specification, the number-average molecular weight is a value determined by gel permeation chromatography (GPC) measurement and converted into polystyrene equivalent.

[0031] [Surface Treatment Agent] As the surface treatment agent used in the polysiloxane particles, a silicone-based surface treatment agent is preferably used. Examples of silicone-based surface treatment agents include polyglycerin-modified silicone, polysiloxanes having a conjugated ring structure, amine-modified silicone, carboxyl-modified silicone, carbinol-modified silicone, and carboxylic anhydride-modified silicone. Among these, polysiloxanes having a conjugated ring structure are preferred from the viewpoint of improving the dispersibility of the pigment and improving the light-blocking properties. As the polyglycerin-modified silicone, for example, a branched polyglycerin-modified silicone in which the silicone chain is branched can be used. The polysiloxane having a conjugated ring structure may be any polysiloxane having three or more conjugated ring structures that form a common conjugated system, and preferably includes a polysiloxane having three to six conjugated aromatic six-membered rings.

[0032] The amount of the surface treatment agent added is, for example, 10% by mass or more and 200% by mass or less, preferably 50% by mass or more and 95% by mass or less, and more preferably 60% by mass or more and 90% by mass or less, relative to 100% by mass of the pigment. By making the content of the surface treatment agent equal to or greater than the above-mentioned lower limit, it becomes easier to properly disperse the pigment. On the other hand, by making the content equal to or less than the above-mentioned upper limit, it becomes easier to exert an effect commensurate with the content.

[0033] The polysiloxane having a conjugated ring structure specifically has a structure represented by the following formula (1). (In formula (1), each R is independently a group represented by A-B or a monovalent hydrocarbon group having 1 to 4 carbon atoms, at least one R among the multiple Rs is a group represented by A-B, A is a divalent organic group bonded to a silicon atom, B is three or more conjugated ring structures that form a common conjugated system, and n is an integer of 1 or greater.)

[0034] The silicone surface treatment agent having the structure represented by formula (1) preferably has a number average molecular weight of from 1,000 to 40,000, more preferably from 2,000 to 30,000, even more preferably from 3,000 to 25,000, still more preferably from 5,000 to 20,000, and particularly preferably from 7,000 to 18,000. Having a number average molecular weight within the above range makes it easier to properly disperse the pigment.

[0035] <Silicone surface treatment agent represented by formula (1)> In formula (1), each R is independently a group represented by A-B or a monovalent hydrocarbon group having 1 to 4 carbon atoms. At least one R among the multiple Rs is a group represented by A-B. A is a divalent organic group and is bonded to the silicon atom of formula (1).

[0036] A is a divalent organic group bonded to the silicon atom of formula (1), preferably a divalent organic group having 11 or less carbon atoms, more preferably a divalent organic group having 10 or less carbon atoms. Thus, polyorganosiloxanes in which A has a certain number of carbon atoms or less are preferred because they tend to improve the dispersibility of the pigment. In addition, although there is no particular limit on the lower limit of the number of carbon atoms in A, it is preferable that A be a divalent organic group having 4 or more carbon atoms.

[0037] A may be a hydrocarbon group, but may also have a heteroatom. When A has a heteroatom, it is preferable that any of the α-, β-, and γ-position atoms among the atoms constituting A is a heteroatom. It is believed that the presence of a heteroatom near the aromatic ring in the structure of the silicone surface treatment agent increases the degree of freedom of rotation, allowing the vicinity of the aromatic ring to adopt various conformations, thereby reducing self-aggregation force. This increases the affinity of the silicone surface treatment agent to the pigment while reducing the self-aggregation force of the silicone surface treatment agent itself, thereby improving the flexibility of the polysiloxane particles. From the viewpoint of improving flexibility, it is more preferable that the α- or β-position atom is a heteroatom, and even more preferable that the α-position atom is a heteroatom. Here, the α-position atom is an atom constituting A that is bonded to a conjugated ring possessed by B (i.e., one conjugated ring among the three or more conjugated rings possessed by B, preferably one aromatic six-membered ring among the three to six conjugated aromatic six-membered rings). The β-position atom is an atom constituting A that is bonded to the α-position atom. The γ-atom is an atom bonded to the β-atom but is not an α-atom. A may also have heteroatoms in portions other than the α-, β-, and γ-atoms.

[0038] The heteroatom is not particularly limited and examples thereof include an oxygen atom, a nitrogen atom, a sulfur atom, and a boron atom. Among these, an oxygen atom is preferred from the viewpoint of effectively improving compatibility with resins.

[0039] When A has a heteroatom, A has a structural unit having a heteroatom. Examples of the structural unit include ether, ester, amide, urethane, thioether, and thioester. Among them, from the viewpoint of improving the adsorption to the pigment and improving the compatibility with the resin, ether or ester is preferred, ether is more preferred, and cyclic ether is particularly preferred. Note that the cyclic ether is an ether having a structure in which carbon of a cyclic hydrocarbon is substituted with oxygen.

[0040] Furthermore, from the viewpoint of improving the adsorption to the pigment and the compatibility with the resin, A preferably has a skeleton represented by the following formula (5-1) or formula (5-2). In formula (5-1), *1 and *2 are bonds, and R ４ is a hydrogen atom or a hydrocarbon group having 1 to 4 carbon atoms, preferably a hydrogen atom. ４ may be the same or different. ３ is a hydrogen atom or a hydrocarbon group having 1 to 4 carbon atoms, preferably a hydrocarbon group having 1 to 4 carbon atoms, more preferably a hydrocarbon group having 1 to 3 carbon atoms, and even more preferably an ethyl group. ５ is a hydrogen atom or a hydrocarbon group having 1 to 4 carbon atoms, preferably a hydrogen atom. The oxygen atom in formula (5-1) is the above-mentioned β-position atom or γ-position atom, preferably a β-position atom. In formula (5-2), *3 and *4 are bonds. The oxygen atom having the bond *3 is the above-mentioned α-position atom, β-position atom or γ-position atom. Among the above, it is preferable that A has a skeleton represented by formula (5-1).

[0041] Furthermore, from the viewpoint of improving the adsorption to the pigment and compatibility with the resin, A preferably has any of the structures represented by the following formulas (6) to (11). In formulas (6) to (11), *5 represents a bond bonded to the conjugated ring possessed by B, and *6 represents a bond bonded to the silicon atom of formula (1). Furthermore, A may be a group other than those in which any of the α-, β-, and γ-position atoms is a heteroatom. Specifically, A may be a hydrocarbon group such as an alkylene group such as a methylene group or an ethylene group, or an arylene group such as a phenylene group. Furthermore, A may be a group in which any atom other than the α-, β-, and γ-position atoms is a heteroatom, or may be an oxygen-containing hydrocarbon group composed of an alkylene group and an ester group.

[0042] In formula (1), B is a conjugated ring structure of three or more that constitute a common conjugated system. Conjugation refers to the alternating connection of unsaturated bonds and single bonds in a molecular structure, resulting in stabilization due to the interaction of p orbitals and delocalization of electrons (presence spread throughout the conjugated system). B preferably has three or more aromatic ring structures, and more preferably has three to six conjugated aromatic six-membered rings. When the number of aromatic six-membered rings is three or more, the adsorption to the pigment is improved, making it easier to disperse the pigment in the resin. Furthermore, when the number of aromatic six-membered rings is six or less, the compatibility of the polyorganosiloxane with the resin is likely to be improved. From the viewpoint of improving the adsorption to the pigment and compatibility with the resin, the number of aromatic six-membered rings is preferably four to five.

[0043] The conjugated ring may be a fused ring compound or a non-fused ring compound, but is preferably a fused ring compound. Thus, when B contains a fused ring compound or when B is a fused ring compound, the adsorption to the pigment is improved, and the pigment is easily dispersed in the resin. Furthermore, the fused ring is preferably an aromatic ring, and the fused ring compound is preferably a fused aromatic ring compound.

[0044] Examples of fused ring compounds include anthracene-substituted compounds, phenanthrene-substituted compounds, triphenylene-substituted compounds, pyrene-substituted compounds, tetracene-substituted compounds, picene-substituted compounds, perylene-substituted compounds, pentaphene-substituted compounds, pentacene-substituted compounds, and hexaphene-substituted compounds. Among these, anthracene-substituted compounds, pyrene-substituted compounds, and perylene-substituted compounds are preferred, and pyrene-substituted compounds and perylene-substituted compounds are more preferred. Here, "substituted compounds" means that they may have a substituent. For example, anthracene-substituted compounds include both anthracene and anthracene having a substituent, and the same applies to other substituents. When a fused ring compound has a substituent, at least one of the hydrogen atoms constituting the fused ring compound is substituted with a substituent. Examples of the substituent include organic groups having 1 to 10 carbon atoms. From the viewpoint of easily improving the compatibility of the polyorganosiloxane of the present invention with resins, it is preferable that the fused ring compound does not have a substituent. Therefore, B is more preferably anthracene, pyrene, or perylene, and particularly preferably pyrene or perylene. In addition, the fused ring compound may be any compound as long as any carbon atom constituting the fused ring is bonded to the above-mentioned A. In addition, the non-fused ring compound is preferably a non-fused aromatic ring compound, for example, a compound having a structure in which multiple aromatic rings are linked by single bonds, such as a substituted terphenyl. In addition, the non-fused ring compound may be any compound as long as any carbon atom constituting the aromatic ring is bonded to the above-mentioned A.

[0045] In the present invention, B can be any of the above-mentioned compounds without any particular limitation, but the preferred structure of B is shown below. In the above formulas (12) to (15), * represents a bond to A.

[0046] Among the above formulas (12) to (15), the compounds of any of formulas (12) to (14), which are fused ring compounds, are preferred, and among these, pyrene of formula (12) or perylene of formula (13) is more preferred, and perylene of formula (13) is even more preferred.

[0047] In formula (1), at least one R is a group represented by A-B, and the remaining R are hydrocarbon groups having 1 to 4 carbon atoms. In formula (1), the number of groups represented by A-B among the multiple R is, for example, 1 to 8, preferably 1 to 5, more preferably 1 to 4, and even more preferably 1 or 2, and the remaining are monovalent hydrocarbon groups having 1 to 4 carbon atoms. When there are multiple groups represented by A-B, the multiple groups represented by A-B may be the same or different. Examples of monovalent hydrocarbon groups having 1 to 4 carbon atoms include methyl, ethyl, propyl, and butyl, with methyl being preferred. When there are multiple monovalent hydrocarbon groups having 1 to 4 carbon atoms, the multiple monovalent hydrocarbon groups having 1 to 4 carbon atoms may be the same or different.

[0048] In formula (1), n ​​means the number of repetitions, and n is an integer of 1 or more. Although n is not particularly limited as long as it is an integer of 1 or more, from the viewpoint of keeping the number average molecular weight of the polyorganosiloxane within a certain range, it is, for example, 530 or less, preferably 500 or less, more preferably 300 or less, and even more preferably 250 or less, and for example, 20 or more, preferably 50 or more, more preferably 100 or more, and even more preferably 200 or more.

[0049] The polyorganosiloxane having the structure represented by formula (1) may have the group represented by A-B at one end, at both ends, on a side chain, at one end and a side chain, or at both ends and a side chain.

[0050] <Silicone surface treatment agent represented by formula (2)> A silicone surface treatment agent according to one embodiment of the present invention has a structure represented by the following formula (2): The silicone surface treatment agent has a group represented by A-B at one end. (In formula (2), each R is independently a monovalent hydrocarbon group having 1 to 4 carbon atoms, and A, B, and n are defined as in formula (1).) Examples of the monovalent hydrocarbon group having 1 to 4 carbon atoms include alkyl groups such as methyl, ethyl, propyl, and butyl, with methyl being preferred. The alkyl group is preferably linear, but may be branched. Multiple R groups may be the same or different. In formula (2), A, B, and n are defined as in formula (1), as described above. The silicone surface treatment agent represented by formula (2) has a group represented by A-B at one end, which is preferred because it easily improves adsorption to pigments.

[0051] <Silicone surface treatment agent represented by formula (3)> A silicone surface treatment agent according to one embodiment of the present invention has a structure represented by the following formula (3): The silicone surface treatment agent has groups represented by A-B at both ends. (In formula (3), each R is independently a monovalent hydrocarbon group having 1 to 4 carbon atoms, and A, B, and n are defined as those in formula (1).) R in formula (3) is defined as R in formula (2), and A, B, and n are defined as those in formula (1).

[0052] <Silicone surface treatment agent represented by formula (4)> A silicone surface treatment agent according to one embodiment of the present invention has a structure represented by the following formula (4): The silicone surface treatment agent has a group represented by A-B in its side chain. (In formula (4), R is a monovalent hydrocarbon group having 1 to 4 carbon atoms or a hydrogen atom, m is an integer of 1 to 10, and A, B, and n are the same as those in formula (1).) R in formula (4) is the same as R in formula (2), and A, B, and n are the same as those in formula (1). In formula (4), m is an integer of 1 to 8, preferably an integer of 1 to 6, more preferably an integer of 1 to 5, and even more preferably 1 or 2. When m is in this range, adsorption to the pigment is improved and self-aggregation of polyorganosiloxanes is suppressed, which is preferable. The polyorganosiloxane represented by formula (4) may be a random polymer or a block polymer. More specifically, the unit shown in parentheses of m and the unit shown in parentheses of n may be present in the molecule in a block manner or randomly.

[0053] Of the silicone surface treatment agents described above, those having a structure represented by formula (2) or (3) above are preferred, and those having a structure represented by formula (2) above are more preferred.

[0054] <Method for Producing Silicone Surface Treatment Agent> The method for producing the silicone surface treatment agent of the present invention is not particularly limited, and can be obtained by reacting a commonly available polyorganosiloxane having functional groups with a compound having three or more conjugated rings that form a common conjugated system and that is capable of reacting with the functional groups of the polyorganosiloxane. For example, the silicone surface treatment agent of the present invention can be produced by utilizing an acetalization reaction between an aldehyde and a diol, or a hydrosilylation reaction between a hydrosilyl group and a carbon-carbon unsaturated bond. For example, the silicone surface treatment agent of the present invention can be produced by reacting a polyorganosiloxane having a diol structure with a compound having an aldehyde group and three or more conjugated rings that form a common conjugated system. Alternatively, the silicone surface treatment agent of the present invention can be produced by reacting a polyorganosiloxane having hydrosilyl groups at the terminal and / or side chain with a compound having a group having a carbon-carbon unsaturated bond, such as an acrylate group or a methacrylate group, and three or more conjugated rings that form a common conjugated system. The silicone surface treatment agent of the present invention may also be one obtained by further chain-extending a compound having a structure shown in formulas (1) to (4) with a chain extender. Chain extension makes it easier to increase the number average molecular weight of the silicone surface treatment agent of the present invention. The chain extender may be a linear polyorganosiloxane or a cyclic polyorganosiloxane such as octamethylcyclotetrasiloxane or decamethylcyclopentasiloxane.

[0055] [Additives] The polysiloxane particles of the present invention may contain additives other than the above-mentioned polysiloxane, pigment, and surface treatment agent, as needed, as long as the effects of the present invention are not impaired. For example, additives such as curing catalysts, alkoxysilane compounds, antioxidants, heat stabilizers, colorants, flame retardants, and antistatic agents may be blended. The other components may be used alone or in combination of two or more.

[0056] [Uses] The uses of the polysiloxane particles of the present invention are not particularly limited, but they are suitably used in applications requiring light-blocking properties, such as spacer particles in display devices using liquid crystal or light-adjusting materials.

[0057] The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to these examples in any way.

[0058] [Number Average Molecular Weight] The number average molecular weight of polyorganosiloxane was measured under the following conditions: A Waters "APC System" was used as the measuring device, an HSPgel HR MB-M 6.0 x 150 mm column was used, and THF was used as the solvent, at a flow rate of 0.5 mL / min and a temperature of 40°C.

[0059] [Compression Ratio at the Start of Voltage Drop] The compression ratio at the start of voltage drop was measured by measuring the conductivity when a single particle of polysiloxane particles was compressed according to the measurement method described in the specification.

[0060] [20% K Value] The 20% K value of the polysiloxane particles was measured according to the measurement method described in the specification.

[0061] [Blackness parameter value] The blackness parameter value of the polysiloxane particles was measured by the method described in the specification. ０ The image for image analysis was taken under the condition that the background brightness L ０ If the value was outside the range of 75 to 80, correction was performed using the following method: (1) Prepare five or more images with different background brightnesses in the same observation field (for example, take images with background brightnesses of 40, 50, 60, 70, and 90). (2) Calculate the blackness parameter for all images using the method described in the specification. (3) Plot the blackness parameter on the vertical axis and the background brightness on the horizontal axis, and perform linear approximation. (4) Use the obtained approximation formula to calculate the blackness parameter when the background brightness is 77.5.

[0062] [Resistivity at 50% Compression] The resistivity of the polysiloxane particles at 50% compression was measured according to the measurement method described in the specification. Furthermore, based on the measured resistivity at 50% compression, the conductivity reliability when used in an environment where a load is applied was evaluated. The evaluation criteria are as follows: A: 500 Ω·μm or more B: 200 Ω·μm or more but less than 500 Ω·μm C: 50 Ω·μm or more but less than 200 Ω·μm D: Less than 50 Ω·μm

[0063] [Transmittance at a wavelength of 550 nm] The transmittance of the polysiloxane particles at a wavelength of 550 nm was measured according to the measurement method described in the specification. Furthermore, the light-blocking ability was evaluated based on the measured transmittance at a wavelength of 550 nm. The evaluation criteria are as follows: A: 20% or less B: 40% or more but less than 20% C: 50% or more but less than 40% D: More than 50%

[0064] [Raw Materials Used] The raw materials used in the Examples and Comparative Examples are as follows.

[0065] (Pigments) Carbon black: "MA600" manufactured by Mitsubishi Chemical Corporation Graphene: "Graphene powder" manufactured by Nishina Materials Co., Ltd.

[0066] (Polysiloxane) Monomer 1: "X-22-2445" manufactured by Shin-Etsu Chemical Co., Ltd., number average molecular weight 3200 Monomer 2: "X-22-164" manufactured by Shin-Etsu Chemical Co., Ltd., number average molecular weight 380 Monomer 3: "X-22-164A" manufactured by Shin-Etsu Chemical Co., Ltd., number average molecular weight 1720 Monomer 4: "Methyltrimethoxysilane" manufactured by Shin-Etsu Chemical Co., Ltd., number average molecular weight 136

[0067] (Surface Treatment Agents) Surface Treatment Agent 1: The agent synthesized in Synthesis Example 1 below was used. Synthesis Example 1 98.6 g of an organosiloxane compound (Mn=15,000) having a 1,3-diol group represented by formula (16), 1.7 g of 3-perylenecarboxaldehyde as a monomer, 50 g of toluene as a solvent, and 0.6 g of a catalyst ("Amberlyst 15 dry" manufactured by Organo Corporation) were reacted in a nitrogen atmosphere at 100°C for 24 hours. After the reaction, the catalyst was removed by filtration through a 5.0 μm PTFE filter, and the filtrate was concentrated using a rotary evaporator and a vacuum dryer to obtain Surface Treatment Agent 1. The reaction formula is as follows. 1H NMR measurement confirmed that the following reaction had proceeded: The NMR measurement apparatus used was a JEOL "ECX-400," and measurements were carried out using deuterated chloroform as the solvent under the conditions of a sample concentration of 1 wt %, 25° C., a measurement frequency of 400 MHz, and 8 accumulations.

[0068] Surface treatment agent 2: The one synthesized in the following Synthesis Example 2 was used. <Synthesis Example 2> Surface treatment agent 2 of Synthesis Example 2 was obtained in the same manner as in Synthesis Example 1, except that the monomer was changed to 1.4 g of 1-pyrenecarboxaldehyde. The reaction formula is as follows:

[0069] Surface Treatment Agent 3: The product synthesized in Synthesis Example 3 below was used. Synthesis Example 3 20 g of an organosiloxane compound (Mn = 10,000) having one terminal hydroxyl group, 0.72 g of 1-pyrenecarboxylic acid as a monomer, 200 g of THF as a solvent, and 0.86 g of 2-methyl-6-nitrobenzoic anhydride and 0.61 g of 4-dimethylaminopyridine as reactants were reacted in a nitrogen atmosphere at room temperature for 24 hours. After the reaction, the reaction solution was washed with a heavy water solution and an ammonium chloride solution and concentrated using a rotary evaporator to obtain Surface Treatment Agent 3. The reaction formula is as follows. 1H NMR measurement confirmed that the following reaction had progressed. A JEOL "ECX-400" NMR measurement device was used, and measurements were performed using deuterated chloroform as the solvent under the following conditions: sample concentration 1 wt %, 25°C, measurement frequency 400 MHz, and 8 accumulations.

[0070] Surface treatment agent 4: Polyglycerin-modified silicone surfactant "KF-6106" manufactured by Shin-Etsu Chemical Co., Ltd.

[0071] [Examples 1 to 9, Comparative Examples 1 and 3] A surface treatment agent and carbon black were added to 3 g of acrylic-modified silicone according to the formulation shown in Table 1, followed by ultrasonic treatment to obtain a monomer dispersion. 0.15 g of initiator (NOF Corporation's "Perocta O") was added to this dispersion and stirred uniformly. Polyvinyl alcohol (PVA) was dissolved in pure water to obtain a 5.5% by mass aqueous solution. 2 g of the monomer dispersion was added to 20 g of the PVA aqueous solution and stirred to adjust the monomer droplets to a predetermined particle size. The mixture was then heated at 90°C for 12 hours to carry out a polymerization reaction, and the resulting particles were washed several times with pure water and then ethanol. Polysiloxane particles (particle diameter 10-50 μm) were recovered by classification. The evaluation results are shown in Table 1. However, in Comparative Examples 1 and 3, no surface treatment agent was added.

[0072] Example 10: To 3 g of acrylic-modified silicone, a surface treatment agent and graphene were added according to the formulation shown in Table 1, followed by ultrasonic treatment to obtain a monomer dispersion. 0.15 g of initiator (NOF Corporation's "Perocta O") was added to this dispersion and stirred uniformly. Polyvinyl alcohol (PVA) was dissolved in pure water to obtain a 5.5% by mass aqueous solution. 2 g of the monomer dispersion was added to 20 g of the PVA aqueous solution, and the mixture was stirred to adjust the monomer droplets to a predetermined particle size. The mixture was then heated at 90°C for 12 hours to carry out a polymerization reaction, and the resulting particles were washed several times with pure water and then with ethanol. Polysiloxane particles (particle diameter 10-50 μm) were recovered by classification. The evaluation results are shown in Table 1.

[0073] Comparative Example 2 Polysiloxane particles were obtained according to the procedure of Example 1 of JP-A-11-049953. However, the methyltrimethoxysilane and carbon black used were as described above. In Comparative Example 2, no surface treatment agent was added.

[0074]

[0075] As is clear from the above, the polysiloxane particles prepared in each Example had high insulating properties even when compressed because the pigment was coated with a surface treatment agent. In contrast, the polysiloxane particles prepared in Comparative Examples 1 to 3 did not have high insulating properties when compressed because the pigment was not coated with a surface treatment agent.

Claims

1. comprising a polysiloxane and a pigment, the pigment is coated with a surface treatment agent, Polysiloxane particles having a 20% K value of 100 N / mm 2 or less.

2. A composition comprising a polysiloxane and a pigment, the pigment is coated with a surface treatment agent, Polysiloxane particles having a compressibility of 50% or more and 90% or less at the start of voltage drop when measuring electrical conductivity when a single particle is compressed.

3. A composition comprising a polysiloxane and a pigment, the pigment is coated with a surface treatment agent, Polysiloxane particles having a blackness parameter value B of 0.04 or more calculated by the following formula (2) when an image observed with an optical microscope having a background lightness L 0 of 75 to 80 is analyzed by the following procedures (A) to (D): (A) Polysiloxane particles are dispersed on a glass slide, and a cover glass is placed on top of the particles to prepare a sample for analysis. (B) The sample for analysis is observed under the optical microscope, and images of the individual polysiloxane particles are taken. (C) Using ImageJ, the image type is set to Lab Stack, and the particle lightness L, background lightness L 0 and particle diameter a (μm) of the polysiloxane particles are analyzed. (D) Calculate the blackness parameter value B using the following formula (2): B = [log(L 0 / L)] / a Formula (2)

4. the pigment is carbon black, The polysiloxane particles according to any one of claims 1 to 3, wherein the content of the carbon black is 4% by mass or more and 10% by mass or less.

5. The polysiloxane particles according to any one of claims 1 to 3, wherein the surface treatment agent is a silicone-based surface treatment agent.

6. The polysiloxane particles according to any one of claims 1 to 3, wherein the polysiloxane is a polymer of a silicone macromonomer.

7. 4. The polysiloxane particles according to claim 3, wherein the blackness parameter value B is 0.1 or less.