Particle, and toner

Abstract

To provide a particle having a hole in the inside thereof and having good storage stability.SOLUTION: A particle has a particle A including resin, and a particle B including resin. The particle B coats at least a part of the surface of the particle A, the volume average particle diameter of the particle is 1 μm to 10 μm, and true density ρt and apparent density ρp of the particles satisfy the following relational expression (1). Expression (1): 0.3≤ρp / ρt≤0.6.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to particles and toners. [Background technology]

[0002] Particles with internal voids have low density and are characterized by light scattering, heat insulation, and soundproofing properties, so there is potential demand for them in fields such as paints, electrophotography, and specific gravity adjusters.

[0003] Patent Document 1 discloses a method for producing toner particles, which includes a polymerization step of polymerizing a monomer composition capable of forming a polymer having a glass transition temperature of 70°C or less in an aqueous medium in the presence of a dispersant containing a metal hydroxide colloid and a colorant, wherein the colorant is a pigment composite hollow particle in which pigment particles are dispersed in a polymer phase and at least one void is formed inside the colorant.

[0004] Furthermore, particles having internal voids can also be used as heat insulating materials or sound insulating materials. Summary of the Invention [Problem to be solved by the invention]

[0005] However, particles having internal voids tend to have poor thermal stability, and therefore storage stability is likely to become a problem. An object of one embodiment of the present invention is to provide particles having internal voids that have good storage stability. [Means for solving the problem]

[0006] In order to solve the above problems, one embodiment of the present invention is Particles having a particle A containing a resin and a particle B containing a resin, the particle B covers at least a part of the surface of the particle A, The particles have a volume average particle size of 1 μm to 10 μm, The particles are provided such that the true density ρt and apparent density ρp of the particles satisfy the following relational expression (1): 0.3≦ρp / ρt≦0.6 (1) [Effects of the Invention]

[0007] According to one embodiment of the present invention, it is possible to provide particles having internal voids and having good storage stability. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a cross-sectional SEM image of an example of a particle according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of the present invention will be described in detail.

[0010] (particle) The particles of the present invention are Particles having a particle A containing a resin and a particle B containing a resin, the particle B covers at least a part of the surface of the particle A, The particles have a volume average particle size of 1 μm to 10 μm, The particles have a true density ρt and an apparent density ρp that satisfy the following relational expression (1): 0.3≦ρp / ρt≦0.6 (1)

[0011] The particles of the present invention may contain one type of resin, but preferably two or more types. The types or compositions of the resin contained in particle A and the resin contained in particle B may be the same or different.

[0012] The particles of the present invention may contain a colorant and may also contain other ingredients.

[0013] The particles of the present invention may also be toner.

[0014] According to the particles of the present invention, it is possible to provide particles having voids inside and having good storage stability.

[0015] <Particle density> The particles of the present invention are particles whose true density ρt and apparent density ρp satisfy the following relational expression (1): 0.3≦ρp / ρt≦0.6 (1)

[0016] If the value of ρp / ρt, where ρt is the true density of the particle and ρp is the apparent density, then it is less than 0.3, the number of voids in the particle will increase, and the particle will have insufficient mechanical strength, making it prone to collapse. If it is more than 0.6, then the particle density will be too high, and the particle will not be sufficiently effective as a specific gravity adjusting material.

[0017] The apparent density ρp of the particles can be obtained, for example, by measuring the particles with a dry automatic density meter, Accupyc II1340 (Shimadzu Corporation).

[0018] The true density ρt of the particles can be determined, for example, by mixing the particles with 100 parts of ethyl acetate to obtain a particle solution, which is then dried under reduced pressure at 100°C to obtain resin pellets. The resin pellets are then pulverized using an Oster Blender, and the pulverized particles are measured using an Accupyc II1340 dry automatic density meter (Shimadzu Corporation).

[0019] <Volume average particle size of particles> The volume average particle diameter of the particles of the present invention is 1 μm to 10 μm, and preferably 4 μm to 8 μm. If the volume average particle diameter of the particles is smaller than 1 μm, transfer and cleaning become difficult when the particles are used as a toner, and if it is larger than 10 μm, sufficient output image quality cannot be obtained when the particles are used as a toner.

[0020] The volume-average particle diameter (Dv) of the particles of the present invention can be measured using a particle size analyzer (Multisizer III, manufactured by Beckman Coulter) with an aperture diameter of 100 μm, and analyzed using analysis software (Beckman Coulter Multisizer 3 Version 3.51). Specifically, for example, 0.5 ml of 10% by weight surfactant (alkylbenzene sulfonate Neogen SC-A; manufactured by Dai-ichi Kogyo Seiyaku) is added to a 100 ml glass beaker, 0.5 g of particles are added, and the mixture is stirred with a microspatula. 80 ml of ion-exchanged water is then added. The resulting dispersion is dispersed for 10 minutes using an ultrasonic disperser (W-113MK-II, manufactured by Honda Electronics Co., Ltd.). This dispersion is then measured using the Multisizer III and an Isoton III (manufactured by Beckman Coulter) as the measurement solution. Measurement is performed by adding a particle sample dispersion of the present invention dropwise so that the concentration indicated by the apparatus is within the range of 8±2%. Within this concentration range, errors in particle size are unlikely to occur, and the particle size measurement reproducibility can be easily obtained in this measurement method.

[0021] <Average circularity of particles> The average circularity of the particles of the present invention is preferably 0.960 to 1.00. When the average circularity of the particles is within the above range, when the particles are toner, the uniformity of the image upon development is less likely to deteriorate, and the efficiency of toner transfer from the photosensitive member to the intermediate transfer member or from the intermediate transfer member to the recording material is less likely to decrease, making it easier to transfer uniformly.

[0022] The average particle circularity is defined as SR = (perimeter of a circle with the same area as the particle projected area / perimeter of the particle projected image) × 100 (%). It can be measured, for example, using a flow particle image analyzer ("FPIA-2100"; Sysmex Corporation) and analyzed using analysis software (FPIA-2100 Data Processing Program for FPIA version 00-10). Specifically, for example, 0.1-0.5 ml of 10% by weight surfactant (alkylbenzene sulfonate NEOGEN SC-A; Daiichi Kogyo Seiyaku Co., Ltd.) is added to a 100 ml glass beaker, 0.1-0.5 g of particles are added, and the mixture is stirred with a microspatula. Then, 80 ml of ion-exchanged water is added. The resulting dispersion is dispersed for 3 minutes using an ultrasonic disperser (Honda Electronics Co., Ltd.). The particle shape and distribution of this dispersion are measured using the FPIA-2100 until a particle concentration of 5,000-15,000 particles / μl is obtained. Within this concentration range, it is easy to obtain reproducible measurements of the average circularity in this measurement method.

[0023] <Observation of particles> The cross section of the particles of the present invention can be observed by a scanning electron microscope (SEM). Specifically, for example, the particles of the present invention are embedded in an epoxy resin, and the cross section of the particles is observed by a scanning electron microscope (SU8230, manufactured by Hitachi, Ltd.) under the following conditions, whereby the cross section of the particles can be observed.

[0024] [Observation conditions] Acceleration voltage: 5kv Emission current: 10μA Probe current: Norm Condenser lens 1:5.0 WD:8.0mm Observation mode: SE Magnification: ×2,000 or ×5,000

[0025] Fig. 1 is a cross-sectional SEM image of an example of a particle according to one embodiment of the present invention. In Fig. 1, particle 10 contains voids 30. Furthermore, since particle B is a fine particle with a particle size much smaller than that of particle A, at least a portion of the surface of particle A 20 in particle 10 is covered with particle B, although this cannot be confirmed in Fig. 1.

[0026] <Particle A> At least a portion of the surface of particle A is covered with particle B, and particle A contains a resin, and the resin contained in particle A may be one type or two or more types. Furthermore, particle A preferably has a volume average particle diameter of 1.1 μm to 9.9 μm, more preferably 3.9 μm to 7.9 μm. Furthermore, particle A preferably has a particle diameter of 0.1 μm to 20 μm, more preferably 0.5 μm to 15 μm, and even more preferably 1 μm to 10 μm.

[0027] Examples of the resin contained in particle A include polyester resin, styrene-acrylic resin, polyol resin, vinyl resin, polyurethane resin, epoxy resin, polyamide resin, polyimide resin, silicon resin, phenol resin, melamine resin, urea resin, aniline resin, ionomer resin, polycarbonate resin, etc., with polyester resin being particularly preferred. When a polyester resin is used, it may be combined with another resin, or several types of polyester resins may be mixed and used.

[0028] When the particles of the present invention are used as a toner, if the particles A contain a polyester resin, the particles have sufficient flexibility even when the molecular weight is reduced, and can be sharply melted during fixing, making it possible to smooth the image surface.

[0029] -Polyester resin- The polyester resin used in the particles of the present invention is preferably a polyester obtained by polyesterifying one or more polyols represented by the following general formula (2) and one or more polycarboxylic acids represented by the following general formula (3).

[0030] X-(OH)m (2) [In the formula, X represents an alkyl group, an alkylene group, an aromatic group or a heterocyclic aromatic group having 1 to 20 carbon atoms, which may have a substituent; and m represents an integer of 2 to 4.]

[0031] Y-(COOH)n (3) [In the formula, Y represents an alkyl group, an alkylene group, an aromatic group or a heterocyclic aromatic group having 1 to 20 carbon atoms, which may have a substituent, and n represents an integer of 2 to 4.]

[0032] Specific examples of polyols represented by general formula (2) include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, neopentyl glycol, 1,4-butenediol, 1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, dipropylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, and pentaerythritol. Examples of suitable esters include erythritol, dipentaerythritol, tripentaerythritol, 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane, 1,3,5-trihydroxymethylbenzene, bisphenol A, bisphenol A ethylene oxide adduct, bisphenol A propylene oxide adduct, hydrogenated bisphenol A, hydrogenated bisphenol A ethylene oxide adduct, and hydrogenated bisphenol A propylene oxide adduct.

[0033] Specific examples of polycarboxylic acids represented by general formula (3) include maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, malonic acid, n-dodecenylsuccinic acid, isooctylsuccinic acid, isododecenylsuccinic acid, n-dodecylsuccinic acid, isododecylsuccinic acid, n-octenylsuccinic acid, n-octylsuccinic acid, isooctylsuccinic acid, isooctylsuccinic acid, 1,2,4-benzenetricarboxylic acid, 2,5,7-naphthalenetricarboxylic acid, 1,2 ,4-naphthalenetricarboxylic acid, 1,2,4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-methylenecarboxypropane, 1,2,4-cyclohexanetricarboxylic acid, tetra(methylenecarboxyl)methane, 1,2,7,8-octanetetracarboxylic acid, pyromellitic acid, empol trimer acid, cyclohexanedicarboxylic acid, cyclohexenedicarboxylic acid, butanetetracarboxylic acid, diphenylsulfonetetracarboxylic acid, ethylene glycol bis(trimellitic acid), etc.

[0034] <Particle B> Particle B covers at least a part of the surface of particle A. By having particle B cover at least a part of the surface of particle A, when the particles are used as toner, the non-electrostatic adhesive force of the toner is reduced, and even when the transfer time is shortened, sufficient transfer efficiency can be obtained without impairing fixability.

[0035] Furthermore, in the particles of the present invention, the average primary particle diameter of particles B is preferably much smaller than the volume average particle diameter of particles A. When the average primary particle diameter of particles B is much smaller than the volume average particle diameter of particles A, particles B can sufficiently cover the surface of particles A even with a small amount of particles B. The average primary particle diameter of particles B is preferably 1 / 100 to 1 / 1000, more preferably 1 / 100 to 1 / 500, and even more preferably 1 / 100 to 1 / 200 of the volume average particle diameter of particles A. The average primary particle diameter of particles B is preferably 10 nm to 100 nm, and more preferably 30 nm to 90 nm. The average primary particle diameter of particles B is preferably 1 / 100 to 1 / 1000, more preferably 1 / 100 to 1 / 500, and even more preferably 1 / 100 to 1 / 200 of the volume average particle diameter of the particles of the present invention.

[0036] Particle B contains a resin, and examples of the resin that can be contained in particle B include the resin that can be contained in particle A described above.

[0037] The resin contained in particle B may also be a resin obtained by copolymerizing a polymerizable monomer. Examples of the polymerizable monomer include acids such as styrene, acrylic acid, butyl acrylate, methacrylic acid, ethylene oxide methacrylate, α-cyanoacrylic acid, α-cyanomethacrylic acid, itaconic acid, crotonic acid, fumaric acid, maleic acid, and maleic anhydride; acrylamide, methacrylamide, diacetone acrylamide, and methylol compounds thereof; acrylates and methacrylates having an amino group, such as vinylpyridine, vinylpyrrolidone, vinylimidazole, ethyleneimine, and dimethylaminoethyl methacrylate; and sulfate adducts thereof.

[0038] The type of resin contained in the particles B may be the same as or different from the type of resin contained in the particles A.

[0039] <Coloring agent> The particles of the present invention may contain a colorant.The colorant that can be used in the particles of the present invention is not particularly limited and can be appropriately selected from known dyes and pigments depending on the purpose, for example, carbon black, nigrosine dye, iron black, naphthol yellow S, Hansa yellow (10G, 5G, G), cadmium yellow, yellow iron oxide, ochre, yellow lead, titanium yellow, polyazo yellow, oil yellow, Hansa yellow (GR, A, RN, R), pigment yellow L, benzidine yellow (G, GR), permanent yellow (NCG), Vulcan fast yellow (5G, R), tartrazine Lake, Quinoline Yellow Lake, Anthrazan Yellow BGL, Isoindolinone Yellow, Bengala, Red Lead, Cinnabar, Cadmium Red, Cadmium Mercury Red, Antimony Vermilion, Permanent Red 4R, Para Red, Faise Red, Parachlor Orthonitroaniline Red, Lithol Fast Scarlet G, Brilliant Fast Scarlet, Brilliant Carnmin BS, Permanent Red (F2R, F4R, FRL, FRLL, F4RH), Fast Scarlet VD, Belkan Fast Rubin B, Brilliant Scarlet G, Lithol Rubin GX, Permanent Red F5R, Brilliant Carmine 6B, Pogment Scarlet 3B, Bordeaux 5B, Toluidine Maroon, Permanent Bordeaux F2K, Helio Bordeaux BL, Bordeaux 10B, Bon Maroon Light, Bon Maroon Medium, Eosin Lake, Rhodamine Lake B, Rhodamine Lake Y, Alizarin Lake, Thioindigo Red B, Thioindigo Maroon, Oil Red, Quinacridone Red, Pyrazolone Red, Polyazo Red, Chrome Vermilion, Benzidine Orange, Peri Non-orange, oil orange, cobalt blue, cerulean blue, alkali blue lake, peacock blue lake, Victoria blue lake, metal-free phthalocyanine blue, phthalocyanine blue, fast sky blue, indanthrene blue (RS, BC), indigo, ultramarine, Prussian blue, anthraquinone blue, fast violet B, methyl violet lake, cobalt purple, manganese purple, dioxane violet, anthraquinone violet, chrome green, zinc green, chromium oxide, pyridian, emerald green,Pigment Green B, Naphthol Green B, Green Gold, Acid Green Lake, Malachite Green Lake, Phthalocyanine Green, Anthraquinone Green, titanium oxide, zinc oxide, lithopone, etc. These may be used alone or in combination of two or more.

[0040] The content of the colorant in the particles of the present invention is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 1 to 15% by mass, more preferably 3 to 10% by mass. When the content of the colorant is 1% by mass or more, the coloring power of the particles does not decrease, and when the content is 15% by mass or less, poor dispersion of the pigment in the particles is unlikely to occur, the decrease in coloring power can be suppressed, and the electrical properties when used as a toner are unlikely to decrease. When the particles are toner, selectively incorporating a colorant into the resin present in the internal phase of the particles can improve the charging performance of the toner, such as environmental stability, charge retention ability, and charge amount.

[0041] The colorant may be used as a masterbatch composited with a resin. Resins that can be used as the masterbatch are not particularly limited and can be appropriately selected from known resins depending on the purpose. Examples include polyesters, polymers of styrene or its substitution products, styrene copolymers, polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, epoxy resins, epoxy polyol resins, polyurethanes, polyamides, polyvinyl butyral, polyacrylic acid resins, rosin, modified rosin, terpene resins, aliphatic hydrocarbon resins, alicyclic hydrocarbon resins, aromatic petroleum resins, chlorinated paraffin, and paraffin wax. These may be used alone or in combination of two or more.

[0042] Examples of polymers of styrene or its substitution products that can be used in the masterbatch include polyester resin, polystyrene, poly(p-chlorostyrene), poly(vinyltoluene), etc. Examples of styrene copolymers that can be used in the masterbatch include styrene-p-chlorostyrene copolymer, styrene-propylene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer, styrene-maleic acid copolymer, and styrene-maleic acid ester copolymer.

[0043] <Other ingredients> The particles of the present invention may contain other components in addition to those described above. The other components are not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include surfactants.

[0044] (toner) When the particles of the present invention are toner, they may contain, in addition to the above-mentioned components, for example, a release agent, a charge control agent, inorganic fine particles, a flowability improver, a cleaning improver, a magnetic material, a metal soap, and the like.

[0045] <Release agent> The release agent is not particularly limited and can be appropriately selected depending on the purpose, but a low-melting release agent having a melting point of 50 to 120° C. is preferred. A low-melting release agent effectively acts as a release agent between the fixing roller and the toner interface, thereby improving hot offset resistance even in an oil-less state where the fixing roller is not coated with a release agent such as oil.

[0046] Suitable examples of release agents include waxes. Examples of waxes include natural waxes such as plant-based waxes (e.g., carnauba wax, cotton wax, Japan wax, and rice wax); animal-based waxes (e.g., beeswax and lanolin); mineral waxes (e.g., ozokerite and cerusine); and petroleum waxes (e.g., paraffin, microcrystalline wax, and petrolatum). In addition to these natural waxes, synthetic hydrocarbon waxes (e.g., Fischer-Tropsch wax and polyethylene wax); synthetic waxes (e.g., esters, ketones, and ethers); and other synthetic waxes. Other examples include fatty acid amides (e.g., 12-hydroxystearic acid amide, stearic acid amide, phthalimide anhydride, and chlorinated hydrocarbons); low-molecular-weight crystalline polymer resins (e.g., polyacrylate homopolymers or copolymers such as poly-n-stearyl methacrylate and poly-n-lauryl methacrylate) (e.g., n-stearyl acrylate-ethyl methacrylate copolymers); and crystalline polymers having long alkyl groups in their side chains. These may be used alone or in combination of two or more.

[0047] The melting point of the release agent is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 50 to 120°C, more preferably 60 to 90°C. A melting point of 50°C or higher does not adversely affect heat-resistant storage stability, and a melting point of 120°C or lower makes it less likely for cold offset to occur during low-temperature fixing. The melt viscosity of the release agent, measured at a temperature 20°C higher than the melting point of the release agent, is preferably 5 to 1,000 cps, more preferably 10 to 100 cps. A melt viscosity of 5 cps or higher does not reduce release properties, and a melt viscosity of 1,000 cps or lower improves hot offset resistance and low-temperature fixability.

[0048] The content of the release agent in the toner of the present invention is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 0 to 40% by mass, more preferably 3 to 30% by mass. When the content of the release agent in the toner is 0 to 40% by mass or less, the fluidity of the toner is less likely to deteriorate.

[0049] <Charge control agent> The charge control agent is not particularly limited and can be appropriately selected from known agents depending on the purpose, and examples thereof include nigrosine dyes, triphenylmethane dyes, chromium-containing metal complex dyes, molybdate chelate pigments, rhodamine dyes, alkoxyamines, quaternary ammonium salts (including fluorine-modified quaternary ammonium salts), alkylamides, phosphorus or its compounds, tungsten or its compounds, fluorine-based activators, metal salts of salicylic acid, metal salts of salicylic acid derivatives, etc. These may be used alone or in combination of two or more.

[0050] The charge control agent may be a commercially available product, and examples of such commercially available products include Bontron 03, a nigrosine dye, Bontron P-51, a quaternary ammonium salt, Bontron S-34, a metal-containing azo dye, E-82, an oxynaphthoic acid metal complex, E-84, a salicylic acid metal complex, and E-89, a phenolic condensate (all manufactured by Orient Chemical Industry Co., Ltd.), TP-302 and TP-415, which are quaternary ammonium salt molybdenum complexes (all manufactured by Hodogaya Chemical Co., Ltd.), Copy Charge PSY VP2038, a quaternary ammonium salt, Copy Blue PR, a triphenylmethane derivative, and Copy Charge NEG VP2036 and Copy Charge NX, which are quaternary ammonium salts. Examples include VP434 (all manufactured by Hoechst), LRA-901, the boron complex LR-147 (manufactured by Nippon Carlit), copper phthalocyanine, perylene, quinacridone, azo pigments, and other polymeric compounds having functional groups such as sulfonic acid groups, carboxyl groups, and quaternary ammonium salts.

[0051] The content of the charge control agent in the toner is, for example, preferably 0.1 to 10 parts by mass, more preferably 0.2 to 5 parts by mass, per 100 parts by mass of the resin. When the content of the charge control agent is 0.1 part by mass or more per 100 parts by mass of the resin, charge controllability is obtained, and when it is 10 parts by mass or less, the chargeability of the toner does not become too high, the electrostatic attraction force with the developing roller becomes appropriate, and a decrease in the fluidity of the developer and a decrease in image density are unlikely to occur.

[0052] <Inorganic fine particles> The inorganic fine particles can be used as an external additive for imparting or assisting fluidity, developability, chargeability, etc. to the toner particles.

[0053] The inorganic fine particles are not particularly limited and can be appropriately selected from known fine particles depending on the purpose, and examples thereof include silica, alumina, titanium oxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, tin oxide, silica sand, clay, mica, wollastonite, diatomaceous earth, chromium oxide, cerium oxide, red iron oxide, antimony trioxide, magnesium oxide, zirconium oxide, barium sulfate, barium carbonate, calcium carbonate, silicon carbide, silicon nitride, and hydrophobized versions of these can be used, with hydrophobic silica and / or hydrophobic titanium oxide being particularly preferred. These may be used alone or in combination of two or more.

[0054] The size of the inorganic fine particles may be large, with an average primary particle size of 80 to 500 nm, or small, but small particle sizes are preferred. The small inorganic particles preferably have an average primary particle size of 5 to 50 nm, more preferably 10 to 30 nm. The specific surface area measured by the BET method is 20 to 500 m 2 / g is preferred.

[0055] The content of the inorganic fine particles in the toner is preferably 0.01 to 5.0% by mass, and more preferably 0.01 to 2.0% by mass.

[0056] <Flow improver> The flowability improver is an agent that increases hydrophobicity by surface-treating inorganic fine particles or the like, and prevents deterioration of flow properties and charging properties even under high humidity, and examples thereof include silane coupling agents, silylating agents, silane coupling agents having a fluorinated alkyl group, organic titanate coupling agents, aluminum coupling agents, silicone oil, modified silicone oil, etc. It is particularly preferable to treat the surface of silica and titanium oxide with such a flowability improver and use them as hydrophobic silica and hydrophobic titanium oxide.

[0057] <Cleaning improver> The cleaning improver is an agent added to the toner to remove the developer remaining on the photoreceptor or primary transfer medium after transfer, and examples thereof include fatty acid metal salts such as zinc stearate, calcium stearate, and stearic acid, and polymer fine particles produced by soap-free emulsion polymerization such as polymethyl methacrylate fine particles and polystyrene fine particles. The polymer fine particles preferably have a relatively narrow particle size distribution, and preferably have a volume average particle diameter of 0.01 to 1 μm.

[0058] <Magnetic materials> The magnetic material is not particularly limited and can be appropriately selected from known materials depending on the purpose, and examples thereof include iron powder, magnetite, ferrite, etc. Among these, white materials are preferred in terms of color tone.

[0059] (developer) The developer according to one embodiment of the present invention may be either a one-component developer or a two-component developer containing the toner of the present invention. The two-component developer contains the toner of the present invention and a carrier. The carrier is not particularly limited and can be appropriately selected depending on the purpose, but a carrier having a core material and a resin layer covering the core material is preferred.

[0060] The core material is not particularly limited and can be selected appropriately depending on the purpose. For example, manganese-strontium (Mn-Sr)-based materials and manganese-magnesium (Mn-Mg)-based materials with a density of 50 emu / g to 90 emu / g are preferred. From the viewpoint of ensuring image density, highly magnetic materials such as iron powder (100 emu / g or more) and magnetite (75 emu / g to 120 emu / g) are preferred. Furthermore, weakly magnetic materials such as copper-zinc (Cu-Zn)-based materials (30 emu / g to 80 emu / g) are preferred because they can weaken the contact of the toner with the photoreceptor in a spiked state, which is advantageous for achieving high image quality. These materials may be used alone or in combination.

[0061] The volume average particle size of the core material is preferably 25 μm or more and 200 μm or less.

[0062] The material for the resin layer that coats the core material is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include amino resins, polyvinyl resins, polystyrene resins, halogenated olefin resins, polyester resins, polycarbonate resins, polyethylene resins, polyvinyl fluoride resins, polyvinylidene fluoride resins, polytrifluoroethylene resins, polyhexafluoropropylene resins, copolymers of vinylidene fluoride and an acrylic monomer, copolymers of vinylidene fluoride and vinyl fluoride, fluoroterpolymers such as terpolymers of tetrafluoroethylene, vinylidene fluoride and a non-fluorinated monomer, silicone resins, etc. These may be used alone or in combination of two or more.

[0063] The mixing ratio of the toner and carrier in the two-component developer is preferably 2.0% by mass to 12.0% by mass, more preferably 2.5% by mass to 10.0% by mass.

[0064] (Particle manufacturing method) The method for producing the particles of the present invention is not particularly limited, but they can be produced, for example, by a dissolution suspension method.

[0065] Generally, in the dissolution suspension method, a particulate material mainly composed of a resin or a resin raw material is dissolved or dispersed in an organic solvent to form a solution or dispersion, which is then added to an aqueous medium containing a dispersant, and emulsified or dispersed using a conventional stirrer, homomixer, homogenizer, etc. to prepare an emulsion or dispersion. The organic solvent is then removed to obtain an aqueous slurry, which is then washed, dried, and classified as necessary using a known method, thereby producing particles of a desired particle size.

[0066] The resin or resin raw material that can be used in producing the particles of the present invention is not particularly limited as long as it is a resin that can be dissolved in a solvent, and examples thereof include polyester resin, styrene-acrylic resin, polyol resin, vinyl resin, polyurethane resin, epoxy resin, polyamide resin, polyimide resin, silicon resin, phenol resin, melamine resin, urea resin, aniline resin, ionomer resin, polycarbonate resin, etc. Other examples include resins or resin raw materials that can be used for the above-mentioned particles A and particles B.

[0067] <Oil phase preparation process> The oil phase, in which a particulate material mainly composed of a resin or a resin raw material is dissolved or dispersed in an organic solvent, can be prepared by gradually adding the particulate material while stirring the organic solvent and dissolving or dispersing it. If necessary, the particulate material may contain the above-mentioned colorant or masterbatch. Furthermore, the particulate material dissolved or dispersed in the oil phase is preferably the material contained in Particle A.

[0068] - Organic solvents - The organic solvent is preferably a volatile organic solvent having a boiling point of less than 100°C, as this facilitates subsequent removal of the organic solvent. Examples of such organic solvents include toluene, xylene, benzene, carbon tetrachloride, methylene chloride, 1,2-dichloroethane, 1,1,2-trichloroethane, trichloroethylene, chloroform, monochlorobenzene, dichloroethylidene, methyl acetate, ethyl acetate, methyl ethyl ketone, and methyl isobutyl ketone. These may be used alone or in combination of two or more, but it is particularly preferred to use ester-based organic solvents such as methyl acetate and ethyl acetate.

[0069] The resin concentration when dissolving or dispersing the particulate material in an organic solvent is preferably 40 to 80% by mass. If it is 40% by mass or more, the production amount will not be too small and the amount of organic solvent to be removed will not be too large, and if it is 80% by mass or less, the particulate material is easy to dissolve or disperse and the viscosity will not increase, making it easy to handle.

[0070] -Dispersion of particle materials- The method for dispersing the particulate material is not particularly limited, but known methods can be applied, and for example, dispersing equipment such as low-speed shear, high-speed shear, friction, high-pressure jet, and ultrasonic can be used. When a high-speed shear dispersing machine is used, the rotation speed is not particularly limited, but is usually 1,000 to 30,000 rpm, and preferably 5,000 to 20,000 rpm. The temperature when dispersing the particulate material under pressure is usually 0°C to 150°C, and preferably 20°C to 80°C.

[0071] <Aqueous phase preparation process> The aqueous phase in which the oil phase is dispersed can be prepared by adding a dispersant such as a resin or a resin raw material to an aqueous medium and stirring the mixture. The dispersant stabilizes the dispersion in the dispersion step. In order to effectively emulsify the oil phase components and the aqueous phase components in the dispersion step, it is preferable that the aqueous phase contains a surfactant.

[0072] -Dispersant- Examples of dispersants added to aqueous media include organic resin microparticles. The resin contained in the dispersant may be a resin obtained by copolymerizing a polymerizable monomer. Examples of the polymerizable monomer include acids such as styrene, acrylic acid, butyl acrylate, methacrylic acid, ethylene oxide methacrylate, α-cyanoacrylic acid, α-cyanomethacrylic acid, itaconic acid, crotonic acid, fumaric acid, maleic acid, and maleic anhydride; acrylamide, methacrylamide, diacetone acrylamide, and methylol compounds thereof; acrylates and methacrylates having amino groups, such as vinylpyridine, vinylpyrrolidone, vinylimidazole, ethyleneimine, and dimethylaminoethyl methacrylate, and sulfate adducts thereof. The resin contained in the aqueous phase may be the resin contained in particle B; the dispersant added to the aqueous medium may be particle B; and the organic resin microparticles added to the aqueous medium may be particle B.

[0073] -Aqueous medium- The aqueous medium is not particularly limited and can be appropriately selected from known ones, for example, water, a water-miscible solvent, a mixture thereof, etc. can be used, among which water is particularly preferred. Examples of the miscible solvent include alcohols such as methanol, isopropanol, ethylene glycol, etc., cellosolves such as dimethylformamide, tetrahydrofuran, methyl cellosolve, etc., lower ketones such as acetone, methyl ethyl ketone, etc. Furthermore, fine particles can be used as a suspension or dispersion stabilizer, and these fine particles may be particles B.

[0074] -Surfactants- Examples of surfactants include anionic surfactants such as alkylbenzenesulfonates, α-olefinsulfonates, and phosphate esters; amine salt-type surfactants such as alkylamine salts, aminoalcohol fatty acid derivatives, polyamine fatty acid derivatives, and imidazolines; quaternary ammonium salt-type cationic surfactants such as alkyltrimethylammonium salts, dialkyldimethylammonium salts, alkyldimethylbenzylammonium salts, pyridinium salts, alkylisoquinolinium salts, and benzethonium chloride; nonionic surfactants such as fatty acid amide derivatives and polyhydric alcohol derivatives; and amphoteric surfactants such as alanine, dodecyldi(aminoethyl)glycine, di(octylaminoethyl)glycine, and N-alkyl-N,N-dimethylammonium betaine.

[0075] <Dispersion process> An oil phase is dispersed in an aqueous phase to prepare a resin dispersion in which particle precursors formed by the coalescence of the resin contained in the oil phase and the resin contained in the aqueous phase are dispersed. Specifically, a resin dispersion is prepared in which particle precursors are dispersed, with particles of a "resin-containing dispersant" contained in an aqueous phase attached to the surface of particles containing a "resin contained in an oil phase." It is preferable that the particles of the "resin-containing dispersant" contained in the aqueous phase are much smaller than the particles containing a "resin contained in an oil phase." It is also preferable that the particles containing a "resin contained in an oil phase" are precursors of particle A, and that the particles of the "resin-containing dispersant" contained in the aqueous phase are precursors of particle B. The method for preparing the dispersion is not particularly limited, and known dispersing equipment such as low-speed shear, high-speed shear, friction, high-pressure jet, and ultrasonic dispersing equipment can be used. However, a high-speed shear dispersing equipment is preferred from the viewpoint of the ease of obtaining particles of the desired particle size. This dispersion process can also be an emulsification process.

[0076] When a high-speed shear disperser is used, the rotation speed is not particularly limited, but is usually 1,000 to 30,000 rpm, and preferably 5,000 to 20,000 rpm. The temperature during dispersion is usually 0 to 150°C, and preferably 20 to 80°C, under pressure.

[0077] <Organic solvent removal process> As a method for removing the organic solvent from the resin dispersion, a known method can be used. For example, a method can be used in which the temperature of the entire system is gradually increased under normal pressure or reduced pressure to evaporate and remove the organic solvent in the droplets.

[0078] <Cleaning process> When the organic solvent is removed from the resin dispersion, an aqueous slurry is formed. The resulting aqueous slurry can be washed using a known method. For example, the aqueous slurry can be filtered to obtain a filter cake, and water, hydrochloric acid, etc. are added to the filter cake, followed by mixing and filtering.

[0079] <Heating process> Examples of the heating step include a method of heating the slurry in a water bath or the like. The heating temperature may be selected depending on the type of resin. In the case of polyester, for example, heating can be performed at 40 to 80°C, preferably at 50 to 65°C, and more preferably at 55 to 65°C. By performing the heating treatment, the viscosity of the resin decreases and the aqueous medium incorporated inside the particle precursor is vaporized, thereby generating pores inside the particle precursor. Therefore, it is presumed that the particles obtained after drying can be particles having pores.

[0080] <Drying process> After the aggregates of the particle precursors are subjected to a heat treatment, the aggregates are dried using a known technique such as a circulating air dryer.

[0081] <Classification process> The dried aggregates can be classified using a known technique such as an elbow jet classifier to obtain particles of a desired particle size. The particles thus obtained contain voids. [Example]

[0082] The present invention will be described in detail below with reference to examples, but the present invention is not limited to the following examples. Unless otherwise specified, "parts" means "parts by mass" and "%" means "% by mass".

[0083] Example 1 <Particle production> A reaction vessel equipped with a condenser, a stirrer, and a nitrogen inlet tube was charged with polyols, namely 235 parts of an ethylene oxide 2-mol adduct of bisphenol A and 525 parts of a propylene oxide 3-mol adduct of bisphenol A, and polycarboxylic acids, namely 205 parts of terephthalic acid, 47 parts of adipic acid, and 2 parts of dibutyltin oxide, and reacted at 230°C under normal pressure for 8 hours, and then at a reduced pressure of 10 to 15 mmHg for 5 hours. Thereafter, 46 parts of trimellitic anhydride was added to the reaction vessel, and the reaction was continued for 2 hours at 180°C and normal pressure, yielding [Polyester Resin 1].

[0084] <Oil phase preparation process> In a vessel equipped with a stirring rod and a thermometer, 500 parts of [polyester resin 1] and 574 parts of ethyl acetate were charged and mixed for 1 hour to obtain [oil phase 1].

[0085] <Aqueous phase preparation process> 970 parts of ion-exchanged water, 40 parts of a 25 wt% aqueous dispersion of organic resin particles for dispersion stabilization (a copolymer of styrene-methacrylic acid-butyl acrylate-methacrylic acid ethylene oxide adduct sulfate sodium salt), and 140 parts of a 48.5% aqueous solution of sodium dodecyl diphenyl ether disulfonate (Eleminol MON-7, manufactured by Sanyo Chemical Industries) were mixed and stirred to obtain a milky white liquid. This was designated [Aqueous Phase 1].

[0086] <Dispersion process (emulsification process)> 120 parts of [Aqueous Phase 1] was added to 100 parts of [Oil Phase 1] and mixed for 20 minutes with a TK Homomixer while adjusting the rotation speed to 8,000 rpm, to obtain [Resin Dispersion 1], in which particle precursors were dispersed, with organic resin fine particles for dispersion stabilization contained in the aqueous phase attached to the surfaces of particles containing [Polyester Resin 1] contained in the oil phase. Note that the particles containing [Polyester Resin 1] contained in the oil phase and the organic resin fine particles for dispersion stabilization contained in the aqueous phase become Particles A and Particles B in the particles obtained after the classification step described below.

[0087] <Organic solvent removal process> [Resin dispersion 1] was placed in a container equipped with a stirrer and a thermometer, and the organic solvent was removed at 30° C. for 8 hours to obtain [Water-based slurry 1].

[0088] 100 parts of [Water-based Slurry 1] was filtered under reduced pressure, and the obtained filter cake was subjected to the following operations (1) to (5).

[0089] <Cleaning process> (1) 100 parts of ion-exchanged water was added to the filter cake, and the mixture was mixed with a TK homomixer (at 12,000 rpm for 10 minutes), followed by filtration to obtain [filter cake 1]. (2): 100 parts of 10% hydrochloric acid was added to [filter cake 1] of (1), and the mixture was mixed with a TK homomixer (at 12,000 rpm for 10 minutes) and then filtered. (3): 300 parts of ion-exchanged water was added to the filter cake from (2), and the mixture was mixed with a TK homomixer (at 12,000 rpm for 10 minutes), followed by filtration. 300 parts of ion-exchanged water was again added to the filter cake, and the mixture was mixed with a TK homomixer (at 12,000 rpm for 10 minutes), followed by filtration.

[0090] <Heating process> (4): 300 parts of ion-exchanged water was added to the filter cake of (3), and the mixture was mixed with a TK homomixer (at a rotation speed of 12,000 rpm for 10 minutes), and then heated in a water bath set at 55°C for 30 minutes, cooled to 25°C, and then filtered to obtain [filter cake 2].

[0091] <Drying process> (5): [Filter cake 2] was dried in a circulating air dryer at 45°C for 48 hours and sieved through a mesh with 75 µm openings to obtain [coarse particles 1].

[0092] <Classification process> [Coarse particles 1] were classified using an elbow jet classifier, and the volume average particle diameter (Dv) was measured by the following method to obtain [particles 1] with a volume average particle diameter (Dv) of 4.0 μm.

[0093] <Measurement of volume average particle diameter (Dv)> The volume-average particle diameter (Dv) of Particle 1 was measured using a particle size analyzer (Multisizer III, Beckman Coulter) with an aperture diameter of 100 μm, and analyzed using analysis software (Beckman Coulter Multisizer 3 Version 3.51). Specifically, 0.5 ml of 10% by weight surfactant (alkylbenzene sulfonate Neogen SC-A; Dai-ichi Kogyo Seiyaku Co., Ltd.) was added to a 100 ml glass beaker, 0.5 g of particles were added, and the mixture was stirred with a microspatula. 80 ml of ion-exchanged water was then added. The resulting dispersion was dispersed for 10 minutes using an ultrasonic disperser (W-113MK-II, Honda Electronics Co., Ltd.). This dispersion was then measured using the Multisizer III and an Isoton III (Beckman Coulter) as the measurement solution. Measurements were performed by adding a sample dispersion of Particle 1 dropwise so that the concentration indicated by the instrument was within the range of 8±2%.

[0094] <Measurement of apparent density and true density> The true density ρt and apparent density ρp of [particle 1] were evaluated by the following method. The apparent density ρp of [Particle 1] was measured using a dry automatic density meter Accupyc II1340 (Shimadzu Corporation). The results are shown in Table 1.

[0095] [Particle 1] was mixed with 100 parts of ethyl acetate to obtain a solution of [Particle 1]. The solution of [Particle 1] was then dried under reduced pressure at 100°C to obtain resin pellets, which were then pulverized using an Oster Blender. The pulverized [Particle 1] was measured using an Accupyc II1340 dry automatic density meter (Shimadzu Corporation) to obtain the true density ρt of [Particle 1]. The results are shown in Table 1. The value of ρp / ρt was rounded to one decimal place.

[0096] <Observation of particles> [Particle 1] was embedded in epoxy resin, and the cross section of [Particle 1] was observed under the following conditions using a scanning electron microscope (SU8230, manufactured by Hitachi, Ltd.).

[0097] [Observation conditions] Acceleration voltage: 5kv Emission current: 10μA Probe current: Norm Condenser lens 1:5.0 WD:8.0mm Observation mode: SE Magnification: ×2,000 or ×5,000

[0098] The cross-sectional SEM image of an average particle of [Particle 1] is shown in Figure 1. In Figure 1, particle 10 contained voids 30. Since the particle size of particle B is much smaller than that of particle A, at least a portion of the surface of particle A 20 in particle 10 is covered with particle B, although this cannot be confirmed in Figure 1.

[0099] Example 2 [Particles 2] were obtained in the same manner as in Example 1, except that in the heating step, the temperature of the water bath was set to 60°C so that the volume average particle diameter (Dv) would be 6.0 μm. The apparent density ρp and true density ρt of [Particles 2] were measured in the same manner as in Example 1. The results are shown in Table 1. The value of ρp / ρt was rounded to one decimal place.

[0100] Example 3 [Particles 3] were obtained in the same manner as in Example 1, except that in the heating step, the temperature of the water bath was set to 65°C so that the volume average particle diameter (Dv) would be 8.0 μm. The apparent density ρp and true density ρt of [Particles 3] were measured in the same manner as in Example 1. The results are shown in Table 1. The value of ρp / ρt was rounded to one decimal place.

[0101] (Comparative Example 1) [Particles 4] were obtained in the same manner as in Example 1, except that in the heating step, the temperature of the water bath was set to 70°C so that the volume average particle diameter (Dv) would be 6.0 μm. The apparent density ρp and true density ρt of [Particles 4] were measured in the same manner as in Example 1. The results are shown in Table 1. The value of ρp / ρt was rounded to one decimal place.

[0102] (Comparative Example 2) In Example 1, after obtaining [Filter Cake 1], in order to dissolve the organic resin fine particles contained in the aqueous phase (particles B), instead of adding 100 parts of 10% hydrochloric acid in the <Washing Step> (2), 100 parts of a 10% aqueous sodium hydroxide solution was added, and the mixture was mixed using a TK Homomixer (at a rotation speed of 12,000 rpm for 30 minutes), followed by vacuum filtration. In addition, in the <Heating Step>, the temperature of the water bath was adjusted to 23°C so that the volume average particle diameter (Dv) became 6.0 μm. [Particles 5] were obtained in the same manner as in Example 1. The apparent density ρp and true density ρt of [Particles 5] were measured in the same manner as in Example 1. The results are shown in Table 1. The value of ρp / ρt was rounded to one decimal place.

[0103] <Storage evaluation> -Heat-resistant storage stability- 10 g of each of [Particles 1] to [Particles 5] was weighed and placed in a 20 ml glass container. The glass container was tapped 150 times and then left in a thermostatic chamber set at a temperature of 50°C and a humidity of 80% for 24 hours. The penetration was then measured using a penetrometer according to the following evaluation criteria. Penetrations with a penetration value of A were deemed to have good storage stability, and those with a penetration value of B were deemed to have poor storage stability. The results are shown in Table 1. [Evaluation criteria] A (good shelf life): 10 or more B (poor preservation): Less than 10

[0104] [Table 1]

[0105] The particles of Examples 1 to 3 were evaluated as A in terms of penetration, and were therefore particles that could be used as the present invention.

[0106] The particles of Comparative Example 1 had a ρp / ρt value of 0.2, many voids in the particles, and insufficient mechanical strength, making the particles prone to collapse.

[0107] In the particles of Comparative Example 2, particle B was dissolved in the washing step, so particle A was not covered with particle B, the value of ρp / ρt was 1, and the evaluation of the penetration was B.

[0108] From the above, it was shown that particles satisfying the constitution of the present invention can provide particles having voids inside and having good storage stability.

[0109] The present invention is not limited to the above-described embodiments, but may be modified, added, modified, deleted, or otherwise altered within the scope of what a person skilled in the art can conceive, and any aspect of the present invention is within the scope of the present invention as long as it exhibits the functions and effects of the present invention.

[0110] The present invention includes, for example, the following aspects. <1> Particles having a particle A containing a resin and a particle B containing a resin, the particle B covers at least a part of the surface of the particle A, The particles have a volume average particle size of 1 μm to 10 μm, Particles, wherein the true density ρt and apparent density ρp of the particles satisfy the following relational expression (1): 0.3≦ρp / ρt≦0.6 (1) <2> The particles contain two or more types of resins. <1> The particle according to claim 1. <3> The type of resin contained in the particles A and the type of resin contained in the particles B are different. <1> or <2> The particle according to claim 1. <4> The particles contain a colorant. <1> , <2> or <3> The particle according to claim 1. <5> the above <1> , <2> , <3> or <4> A toner comprising the particles described in

[0111] the above <1> from <4> Any of the particles above <5> The toner described above can solve the various problems encountered in the prior art and achieve the object of the present invention. [Explanation of symbols]

[0112] 10 particles 20 Particle A 30 vacancies [Prior art documents] [Patent documents]

[0113] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-152166

Claims

1. A particle having a particle A containing a resin and a particle B containing a resin, the particle B covers at least a part of the surface of the particle A, The particles have a volume average particle size of 1 μm to 10 μm, The particles have a true density ρt and an apparent density ρp that satisfy the following relational expression (1): 0.3≦ρp / ρt≦0.6 (1)

2. The particle of claim 1 , wherein the particle comprises two or more resins.

3. The particles according to claim 1 , wherein the type of resin contained in said particles A is different from the type of resin contained in said particles B.

4. The particle of claim 1 , wherein the particle comprises a colorant.

5. A toner comprising particles according to any one of claims 1 to 4.

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