Surface-modified inorganic oxide powder modified with nonionic surfactants

Abstract

To provide an inorganic oxide powder having smaller charging amount difference between that under a high-temperature high-humidity condition and that under a low-temperature low-humidity condition.SOLUTION: A surface-modified inorganic oxide powder is a powder comprising composite particles involving inorganic oxide particles and a coating formed on the particle surfaces, in which (1) the coating involves a hydrophobicity imparting agent and a nonionic surfactant and (2) the powder has a hydrophobicity rate of 40% or over.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This invention relates to a novel surface-modified inorganic oxide powder. In particular, it relates to a surface-modified inorganic oxide powder whose surface is modified with a nonionic surfactant. [Background technology]

[0002] Generally, in electrophotographic printing, which is used in laser printers and photocopiers, the printing process involves the following steps: a) charging the photoreceptor, b) irradiating the charged photoreceptor with laser light to form an electrostatic latent image, c) attaching charged toner to the electrostatically latent imaged photoreceptor to develop a mirror image of the image on the photoreceptor, d) transferring the toner attached to the photoreceptor to a printing medium such as paper, and e) fixing the toner on the printing medium by heating and applying pressure using a heat roller or the like.

[0003] Toner is agitated within devices such as photocopiers and becomes electrically charged (i.e., electrostatically charged) through friction with carriers and other components. This highly controlled electrostatic charge allows it to perform its developing function. Since image formation is carried out by electrostatic attraction, the process of electrostatically charging the toner is extremely important.

[0004] However, since different printing presses require different levels of toner charge, it is necessary to adjust the charge level to the optimal value. Furthermore, because printing presses are used in countries and regions with various environments, it is necessary that the fluctuation in charge level be as small as possible under any temperature and humidity conditions. In particular, a key property of toner is that the difference in charge level is small even under the two extreme conditions of high temperature and high humidity (HH) and low temperature and low humidity (LL).

[0005] To achieve the performance described above, surface-modified inorganic oxides are used, which are obtained by treating the surface of fine inorganic oxide powders such as silica, titania, and alumina with organic substances. By treating the inorganic oxide surface with various organic groups, the electrostatic properties and hydrophobicity of the powder surface can be modified. Such surface-modified inorganic oxide powders used in toner applications are known as external additives.

[0006] Known surface treatment agents for inorganic oxide powders used in toner applications include organosilicon compounds such as dimethyldichlorosilane, hexamethyldisilazane, and silicone oil. Surface treatment with these organosilicon compounds can, for example, hydrophobize the surface of silica nanoparticles by replacing the silanol groups with organic groups.

[0007] In practice, hydrophobized small-particle silica is widely used to control fluidity and electrostatic properties. However, while the fluidity of toner is improved when using small-particle silica, there is a problem in that the difference in charge between HH conditions and LL conditions becomes large.

[0008] Conventional technologies relating to such inorganic oxide particles include, for example, a non-magnetic one-component color developer made by mixing inorganic fine powder hydrophobically treated with silicone oil with specific colored fine particles (Patent Document 1). However, with the inorganic fine powder described in Patent Document 1, the amount of charge increases not only under HH conditions but also under LL conditions, and therefore, no improvement effect on the above problem can be expected.

[0009] Furthermore, to mitigate excessive negative charge under LL conditions, a method has been proposed in which surface-treated silica treated with aminosilane or amino-modified silicone oil is added (Patent Documents 2 and 3). However, the methods described in Patent Documents 2 and 3 have the problem of reducing negative charge under HH conditions where the amount of charge tends to be insufficient.

[0010] In order to solve this problem, in recent years, it has also been proposed to use a hydrophobically treated material such as titania as an external additive (Patent Documents 4 and 5). However, although the use of titania can reduce the difference in charge amount due to environmental changes, in addition to the contamination of the members of the printing machine by titania, in recent years, safety issues have arisen due to concerns about the carcinogenicity of titania.

Prior Art Documents

Patent Documents

[0011]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Summary of the Invention

Problems to be Solved by the Invention

[0012] For the reasons described above, there is a strong desire to develop an inorganic oxide powder with a smaller difference in charge amount between the HH condition and the LL condition and suitable for toner applications, etc., but such a material has not yet been developed.

[0013] Therefore, the main object of the present invention is to provide an inorganic oxide powder with a smaller difference in charge amount between high temperature and high humidity conditions and low temperature and low humidity conditions.

Means for Solving the Problems

[0014] As a result of intensive research in view of the problems of the prior art, the present inventors have found that specific inorganic oxide particles surface-modified with a nonionic surfactant and a suitable hydrophobizing agent can achieve the above object, and have completed the present invention.

[0015] In other words, the present invention relates to the following surface-modified inorganic oxide powder. 1. A powder comprising composite particles including inorganic oxide particles and a film formed on the surface of those particles, (1) The coating comprises a hydrophobic agent and a nonionic surfactant, (2) The hydrophobicity of the powder is 40% or more. A surface-modified inorganic oxide powder characterized by the following features. 2. The amount of nonionic surfactant (g) is expressed as the BET specific surface area (m²) of the inorganic oxide particles. 2 The surface-modified inorganic oxide powder according to claim 1, wherein the value obtained by dividing by ( / g) is 0.015 to 0.150. 3. Nonionic surfactants are defined by the following general formula (1): [ka] [In the formula, R represents a linear or branched hydrocarbon group having 8 to 18 carbon atoms, which may have unsaturated bonds; x represents an integer of 1 or more; n represents an integer of 2 or more; and x and n satisfy n > x.] The surface-modified inorganic oxide powder according to item 1 or 2, which is an ethoxylated aliphatic amine having a basic skeleton derived from a tertiary amino group represented by . 4. Hydrophobic agents, (a) General formula (2) below: [ka] (In the formula, R 1 R represents a hydrocarbon group with 1 to 18 carbon atoms. 2 , R 3 and R 4 These represent, either identical or different from each other, a chlorine atom, a hydroxyl group, or an alkoxy group having 1 to 3 carbon atoms.) Alkylsilanes represented by (b) Silicone oil and (c) Hexamethyldisilazane A surface-modified inorganic oxide powder according to any one of the above items 1 to 3, which is at least one selected from the group consisting of the above. 5. The inorganic oxide particles are at least one selected from the group consisting of gas-phase silica particles, gas-phase alumina particles, and gas-phase titania particles, and the BET specific surface area thereof is 30 to 400 m 2 / g, and the surface-modified inorganic oxide powder according to any one of the above items 1 to 4. 6. In the toner obtained by externally adding the surface-modified inorganic oxide particles to negatively charged polyester-based binder resin particles, the charge amount C LL (μC / g) after 40 hours under the conditions of a temperature of 10 °C and a relative humidity of 10% is divided by the charge amount C HH (μC / g) after 40 hours under the conditions of a temperature of 35 °C and a relative humidity of 80% to obtain a value [C LL / C HH of 1.55 or less, and the surface-modified inorganic oxide powder according to any one of the above items 1 to 5. 7. An external additive for toner or powder coating containing the surface-modified inorganic oxide powder according to any one of the above items 1 to 6. 8. An electrophotographic toner composition or powder coating composition containing the external additive according to item 7 and binder resin particles.

Effect of the Invention

[0016] According to the present invention, it is possible to provide an inorganic oxide powder having a smaller difference in charge amount between the HH condition and the LL condition. In particular, since the surface of the inorganic oxide particles constituting the inorganic oxide powder is hydrophobized by a hydrophobizing agent and further surface-treated with a nonionic surfactant, the difference between the charge amount under the HH condition and the charge amount under the LL condition is controlled to be low. More specifically, as shown in the following examples and the like, the ratio [C LL (μC / g) of the charge amount C HH (μC / g) under the LL condition to the charge amount C LL / C HH under the HH condition can obtain a value closer to 1. In other words, the variation in the charge amount due to the difference in the use environment is relatively small, and excellent charge stability can be exhibited.

[0017] Thus, the powder of the present invention, which exhibits excellent electrostatic stability, can be suitably used as an external additive, particularly for toners or powder coatings. Therefore, an electrophotographic toner composition or powder coating composition containing the surface-modified inorganic oxide powder of the present invention can reduce the difference in charge levels between HH conditions and LL conditions, resulting in improved long-term storage stability and control of developer degradation behavior. [Modes for carrying out the invention]

[0018] 1. Surface-modified inorganic oxide powder The surface-modified inorganic oxide powder (the powder of the present invention) modified with the nonionic surfactant of the present invention is a powder composed of composite particles including inorganic oxide particles and a film formed on the surface of those particles, (1) The coating comprises a hydrophobic agent and a nonionic surfactant, (2) The hydrophobicity of the powder is 40% or more. It is characterized by the following:

[0019] <Composition of the powder of this invention> The particles constituting the powder of the present invention are composed of composite particles including inorganic oxide particles and a coating formed on the surface of those particles. The coating contains a hydrophobic agent and a nonionic surfactant.

[0020] In other words, the composite particles described above have a basic structure in which inorganic oxide particles are used as core particles (original materials), and part or all of their surface is coated with a film containing organosilicon compounds and nonionic surfactants.

[0021] The type of inorganic oxide particles that form the core is not limited, but at least one of silica, titania, alumina, etc., can be preferably used. Alternatively, particles of a mixed oxide (complex oxide) containing these oxides may also be used. These particles themselves can be known or commercially available.

[0022] The particle size of inorganic oxide particles is not limited, but typically a primary particle diameter of around 5-150 nm is acceptable. The BET specific surface area of ​​inorganic oxide particles is typically 30-400 m². 2 A value of approximately / g would suffice, but it is not limited to this.

[0023] Furthermore, in this invention, it is preferable to use powder produced by the gas phase method (fumed method) as inorganic oxide particles. The gas phase method itself is a known manufacturing method (synthesis method), and for example, silica particles can be synthesized by a method that includes a step of introducing a silicon compound (such as silicon tetrachloride) or metallic silicon into an oxygen-hydrogen flame and causing a hydrolysis reaction. Since such powders have a particle shape that is less spherical than silica produced by the sol-gel method, advantages such as effectively suppressing liberation from the toner surface can be obtained. In addition, since no solvent is used, the advantage of not generating aggregated particles during drying can also be obtained.

[0024] Therefore, in the present invention, it is preferable to use inorganic oxide particles produced by the vapor phase method (fumed particles) as the inorganic oxide particles. For example, at least one of vapor phase silica particles, vapor phase alumina particles, and vapor phase titania particles can be preferably used. Such vapor phase inorganic oxide particles themselves can be known or commercially available. For example, commercially available products shown in the examples below can also be suitably used.

[0025] Furthermore, in the present invention, a step-by-step treatment can be used in which pre-hydrophobized inorganic oxide particles are used as core particles, and these are treated with a nonionic surfactant. In this case, known or commercially available hydrophobized inorganic oxides can be used as core particles. For example, commercially available hydrophobized inorganic oxide powders shown in the examples below can also be suitably used.

[0026] The hydrophobic agent included in the above-mentioned film is not particularly limited, and known or commercially available hydrophobic agents can also be used.

[0027] More specifically, examples of usable materials include alkylsilazane compounds (organosilazanes) such as tetramethyldisilazane, hexamethyldisilazane (HMDS), and pentamethyldisilazane; alkylalkoxysilane compounds such as dimethyldimethoxysilane, dityldiethoxysilane, trimethylmethoxysilane, methyltrimethoxysilane, and butyltrimethoxysilane; chlorosilane compounds such as dimethyldichlorosilane and trimethylchlorosilane; and silicone oils such as polydimethylsiloxane (PDMS). These may be used individually or in combination of two or more.

[0028] Among these, it is preferable to use at least one of alkylsilazane compounds, alkylalkoxysilane compounds, silicone oils, etc., in order to more reliably obtain the effects of the present invention. In particular, at least one of hexamethyldisilazane, polydimethylsiloxane, alkylalkoxysilane, etc. is more preferable.

[0029] Furthermore, among these, in particular, the following general formula (2): [ka] (In the formula, R 1 This indicates a hydrocarbon group with 1 to 18 carbon atoms. 2 , R 3 and R 4 These represent, either identical or different from each other, a chlorine atom, a hydroxyl group, or an alkoxy group having 1 to 3 carbon atoms.) Alkylsilanes represented by (b) Silicone oil and (c) Hexamethyldisilazane At least one selected from the group consisting of the above can also be suitably used.

[0030] Among these, at least one of (a) alkylalkoxysilanes included in the alkylsilanes mentioned above, (b) silicone oil, and (c) hexamethyldisilazane is particularly preferred.

[0031] The alkylalkoxysilane mentioned above is not particularly limited as long as it is an alkoxysilane having an alkyl group, and examples include trimethoxyalkoxysilane and triethoxyalkoxysilane. In the alkylalkoxysilane, the number of carbon atoms (C) of the alkyl group is not particularly limited, but it is particularly preferably C2 to C18. If it is less than C2, the alkoxysilane may volatilize during surface treatment. If it is more than C18, strong aggregation may occur due to the effect of its high viscosity, and the dispersibility of the obtained powder may be impaired.

[0032] As the silicone oil mentioned above, in addition to polydimethylsiloxane, modified silicone oils to which alkyl groups, -OH groups, etc., have been introduced can also be used.

[0033] The viscosity range of the hydrophobicity imparting agent (measured at a temperature of 25°C) is not particularly limited, but is generally preferably 20 to 300 cs. If the viscosity is less than 20 cs, volatilization of low molecular weight polysiloxanes, etc., occurs during surface treatment, which is undesirable from the viewpoint of energy efficiency and environmental impact. On the other hand, if the viscosity exceeds 300 cs, higher aggregation may occur, potentially impairing the dispersibility of the resulting powder.

[0034] The content of the hydrophobic agent in the powder of the present invention is not particularly limited as long as the desired hydrophobicity is obtained, but it is generally preferably about 1 to 40 parts by weight, and particularly preferably 2 to 30 parts by weight, per 100 parts by weight of inorganic oxide particles.

[0035] The powder of the present invention contains a nonionic surfactant along with a hydrophobic agent in its coating. According to the present invention, by further surface-treating the particle surface treated with the hydrophobic agent with a nonionic surfactant, an appropriate amount of moisture can be adsorbed, thereby contributing to improved electrostatic stability. In other words, the difference in the amount of charge between HH conditions and LL conditions is thought to be due to the amount of moisture adsorbed, and by controlling such adsorption, electrostatic stability can be ensured. In this regard, a structure having a layer containing a hydrophobic agent on the surface of inorganic oxide particles, and a layer of nonionic surfactant on that layer, is a preferred example, but is not limited to this. The reason for imparting hydrophobicity with a hydrophobic agent is that if treatment is performed with a nonionic surfactant alone, excessive moisture will be adsorbed, resulting in almost no charge under HH conditions.

[0036] On the other hand, when treated with anionic surfactants, although the reason is unclear, the electrostatic charge under HH conditions decreases compared to nonionic surfactants due to their high water adsorption capacity.

[0037] From this perspective, the present invention uses a combination of a hydrophobic treatment agent and a nonionic surfactant, and as described below, a nonionic surfactant containing a tertiary amino group is more preferred. The reason why this results in superior electrostatic stability is not entirely clear, but for example, when the inorganic oxide particles are silica, it is thought that the strong interaction between its silanol group and amino group allows for efficient surface modification. It is also presumed that the positive charge imparting effect of the amino group suppresses the strong negative charge imparted to the powder after surface treatment, which is another contributing factor.

[0038] The nonionic surfactant contained in the aforementioned film is not particularly limited, and known or commercially available nonionic surfactants can be used, for example. The hydrophilic group of the nonionic surfactant is not limited, but polyoxyethylene chains, polyoxypropylene chains, etc. are preferred, and polyoxyethylene chains are particularly preferred.

[0039] More specifically, various nonionic surfactants such as esters, ethers, ester ethers, alkyl glycosides, and ethoxylated amines can be used. These can be used individually or in combination of two or more.

[0040] Examples of esters that can be used include glyceryl laurate, glyceryl monostearate, sorbitan fatty acid esters, and sucrose fatty acid esters.

[0041] Examples of ethers that can be used include pentaethylene glycol monododecyl ether, octaethylene glycol monododecyl ether, octylphenol ethoxylate, and nonylphenol ethoxylate.

[0042] Examples of ester ethers that can be used include polyoxyethylene glycerol fatty acid esters, polyoxyethylene castor oil, and polyoxyethylene sorbitan fatty acid esters.

[0043] Examples of alkyl glycosides that can be used include octyl glucoside, decyl glucoside, and lauryl glucoside.

[0044] Ethoxylated amines include those with the following general formula (1): [ka] [In the formula, R represents a linear or branched hydrocarbon group having 8 to 18 carbon atoms, which may have unsaturated bonds; x represents an integer of 1 or more; n represents an integer of 2 or more; and x and n satisfy n > x.] Examples of ethoxylated aliphatic amines having a basic skeleton derived from a tertiary amino group can be given.

[0045] Among these, it is preferable to use at least one of the ethoxylated amines, in that it is more reliable to obtain the effects of the present invention (particularly the effect of reducing the charge difference between HH conditions and LL conditions), and the ethoxylated aliphatic amine represented by the above general formula (1) is more preferable. In the above general formula (1), by setting the number of carbon atoms of R to the range of 8 to 18 (preferably 10 to 16), it is possible to impart higher hydrophobicity and obtain higher dispersibility by effectively preventing aggregation of core particles.

[0046] In the above general formula (1), n ​​and x are not limited, but from the viewpoint of obtaining the effects of the amino group as described above, it is preferable that n and x are integers such that the number-average molecular weight of the ethoxylated aliphatic amine is 1200 or less. Therefore, for example, n and x can be set so that the number-average molecular weight is around 300 to 900, but this is not limited to this.

[0047] Specific examples of such ethoxylated aliphatic amines include bis-2-hydroxyethyl isotridecyloxypropylamine, poly-(5)-oxyethylene isodecyloxypropylamine, and polybis-(2-hydroxyethyl)oxyethylene cocoalkyloxypropylamine. Commercially available products of these can also be used. More specifically, products like those shown in the examples below can be suitably used.

[0048] The content of the nonionic surfactant in the powder of the present invention is not particularly limited, but is generally about 1 to 40 parts by weight per 100 parts by weight of inorganic oxide particles, and is particularly preferably 2 to 30 parts by weight.

[0049] In particular, in the present invention, it is more preferable that the content of the nonionic surfactant is in proportion to the BET specific surface area of ​​the inorganic oxide particles. That is, the content (g) of the nonionic surfactant is in proportion to the BET specific surface area (m²) of the inorganic oxide particles. 2The value obtained by dividing by ( / g) is preferably 0.012 to 0.180, and more preferably 0.015 to 0.150. As a result, by surface treatment with a nonionic surfactant, an appropriate amount of moisture can be adsorbed, which improves electrostatic stability.

[0050] <Characteristics of the powder of this invention> Hydrophobicity The hydrophobicity of the powder of the present invention (composite particle powder) is usually 40% or more, preferably 50% or more. In the present invention, the hydrophobicity is an indicator of the degree of hydrophobicity of the surface-modified inorganic oxide powder, and the higher the value, the higher the hydrophobicity. If the hydrophobicity is less than 40%, the residual silanol groups of the inorganic oxide powder will not be able to maintain strong chargeability, and it may not be possible to obtain an inorganic oxide powder with excellent chargeability. In the present invention, the upper limit of the hydrophobicity is theoretically 100%, but it is not limited to this. In the present invention, the method for measuring the hydrophobicity is the method of Test Example 1 described below.

[0051] Average particle size The average particle size (secondary particle diameter) of the powder of the present invention is usually around 0.1 to 10 μm, but is not limited to this.

[0052] Charge ratios under HH and LL conditions The powder of the present invention is characterized by a small difference between the amount of charge under HH conditions and the amount of charge under LL conditions. More specifically, the amount of charge C when left for 40 hours at a temperature of 35°C and a humidity of 80% under HH conditions. HH (μC / g) and the amount of charge C when left for 40 hours under LL conditions of 10°C and 10% humidity. LL (μC / g) ratio [C LL / C HHThe charge is usually 1.55 or less, and is particularly preferably 1.00 to 1.50, and more preferably 1.00 to 1.20. In the powder of the present invention, the charge under HH conditions can be, for example, about -40 to -5 μC / g, but is not limited to this as it can be appropriately changed depending on the application, usage conditions, etc. The charge under LL conditions can also be -40 to -5 μC / g, but is not limited to this as it can be appropriately changed depending on the application, usage conditions, etc. In the present invention, the method for measuring these charge amounts is the method shown in Test Example 1 below.

[0053] 2. Method for producing the powder of the present invention The method for producing the powder of the present invention is not particularly limited, as long as a powder having the above-described composition and characteristics can be obtained. In the present invention, the following methods can be suitably employed: A) a method including the step of applying a nonionic surfactant and a hydrophobic agent to inorganic oxide powder and then heat-treating it (hereinafter also referred to as "simultaneous treatment"), B) a method including the step of applying a hydrophobic agent to inorganic oxide particles and then heat-treating them to obtain hydrophobic inorganic oxide powder, and the step of applying a nonionic surfactant to the hydrophobic inorganic oxide powder and then heat-treating it (hereinafter also referred to as "step-by-step treatment"). The powder of the present invention can be obtained more reliably by these methods.

[0054] As an alternative method, C) a method including the step of applying a nonionic surfactant to a hydrophobic inorganic oxide powder whose surface has been pre-treated to be hydrophobic, and then heat-treating it, can also be suitably employed. According to method C) above, commercially available hydrophobic inorganic oxide powder can be used, thereby enabling the preparation of the powder of the present invention more efficiently in a single step.

[0055] <Simultaneous processing> The simultaneous processing method includes a step of applying a nonionic surfactant and a hydrophobic agent to an inorganic oxide powder, followed by a heat treatment. More specifically, it can be suitably produced by a method including (a) a step of preparing a mixture containing inorganic oxide powder, a hydrophobic agent, and a nonionic surfactant (mixture preparation step), and (b) a step of heat treating the mixture at a temperature of 100 to 200°C (heat treatment step).

[0056] Mixture preparation process The method is not limited to any method that can coat the surface of each particle constituting the inorganic oxide powder with a hydrophobic agent and a nonionic surfactant. For example, a method of mixing the inorganic oxide powder with a vaporized hydrophobic agent under stirring, or a method of mixing the inorganic oxide powder with a hydrophobic agent under stirring, to obtain hydrophobic inorganic oxide powder, to which a nonionic surfactant can be sprayed, or a method of spraying a mixture of the hydrophobic agent and the nonionic surfactant under stirring can be suitably employed.

[0057] In this case, the hydrophobic agent, nonionic surfactant, and mixture of the hydrophobic agent and nonionic surfactant can all be used dissolved or dispersed in a solvent (e.g., organic solvents such as hexane, toluene, or methanol) as needed. In this case, the concentration of each component can be appropriately set depending on the type of hydrophobic agent or nonionic surfactant used.

[0058] Furthermore, in this invention, water and catalysts (such as amines) can be appropriately added to the mixture as needed.

[0059] The temperature conditions in the mixture preparation process are not particularly limited and may be, for example, within the range of 10 to 40°C, but are not limited thereto. Furthermore, it is generally preferable to carry out the process in an inert gas atmosphere. For example, nitrogen gas, helium gas, argon gas, etc., can be suitably used.

[0060] The types and amounts of inorganic oxide particles, hydrophobicity-imparting agents, and nonionic surfactants used can be the same as those described in "1. Surface-Modified Inorganic Oxide Powder" above.

[0061] Heat treatment process In the heat treatment process, the mixture obtained in the above process is heat-treated at a temperature of 100 to 200°C.

[0062] While there are no strict limitations on the heat treatment temperature in the heat treatment process, it is generally preferable to set it between 100 and 200°C (particularly 150 to 200°C). If the heat treatment temperature exceeds 200°C, partial decomposition of the nonionic surfactant may occur. Conversely, if the temperature is below 100°C, sufficient surface modification by the hydrophobicity-imparting agent may not be achieved, potentially resulting in an undesirable hydrophobicity.

[0063] The heat treatment atmosphere, as in the previous step, is preferably carried out in an inert gas atmosphere. For example, nitrogen gas, helium gas, argon gas, etc., can be suitably used. In particular, the previous step can be carried out in a sealed reactor, and the heat treatment step can be suitably carried out while maintaining the same atmosphere.

[0064] The heat treatment time should be sufficient to allow the hydrophobicity-imparting agent to fix (adhere) to the surface of each particle constituting the inorganic oxide powder. For example, it can be 10 to 200 minutes, but is not limited to this.

[0065] <Step-by-step processing> The step-by-step process includes the steps of: obtaining hydrophobic inorganic oxide powder by applying a hydrophobic agent to inorganic oxide particles and then heat-treating them; and applying a nonionic surfactant to the hydrophobic inorganic oxide powder and then heat-treating it.

[0066] More specifically, it can be suitably manufactured by a method including, for example, (a) a step of preparing a first mixture containing inorganic oxide particles and a hydrophobic agent (first mixture preparation step), (b) a step of heat-treating the first mixture at a temperature of 100 to 360°C (first heat treatment step), (c) a step of preparing a second mixture containing the mixture obtained in the first heat treatment step and a nonionic surfactant (second mixture preparation step), and (d) a step of heat-treating the second mixture at a temperature of 100 to 200°C (second heat treatment step).

[0067] In this case, the hydrophobic agent and nonionic surfactant may be used dissolved or dispersed in a solvent (e.g., organic solvents such as hexane, toluene, or methanol) as needed. The concentration of the organosilicon compound in this case can be appropriately set depending on the type of organosilicon compound used.

[0068] Furthermore, in this invention, water and catalysts (such as amines) can be appropriately added to the mixture as needed.

[0069] First mixture preparation step In the first mixture preparation step, a first mixture containing inorganic oxide particles and a hydrophobicity-imparting agent is prepared.

[0070] The temperature conditions in this process are not particularly limited; for example, they may be within the range of 10 to 40°C, but are not limited to this range. Furthermore, it is generally preferable to carry out the process in an inert gas atmosphere. For example, nitrogen gas, helium gas, argon gas, etc., can be suitably used.

[0071] The types and amounts of inorganic oxide particles and hydrophobicity-imparting agents used can be the same as those described in "1. Surface-Modified Inorganic Oxide Powder" above.

[0072] First heat treatment process In the first heat treatment step, the first mixture obtained in the previous step is heat-treated at a temperature of 100 to 360°C.

[0073] The heat treatment temperature is not limited, but is usually between 100 and 360°C, and particularly preferably between 150 and 300°C. If the heat treatment temperature exceeds 360°C, partial decomposition of the hydrophobic agent may occur. If the temperature is below 100°C, sufficient surface modification by the hydrophobic agent may not be achieved, and the desired hydrophobicity may not be obtained.

[0074] The heat treatment atmosphere, as in the previous step, is preferably carried out in an inert gas atmosphere. For example, nitrogen gas, helium gas, argon gas, etc., can be suitably used. In particular, the previous step can be carried out in a sealed reactor, and the heat treatment step can be suitably carried out while maintaining the same atmosphere.

[0075] The heat treatment time should be sufficient to allow the hydrophobic agent to fix (adhere) to the surface of each particle constituting the inorganic oxide powder, and can be, for example, 10 to 200 minutes, but is not limited to this.

[0076] Second mixture preparation step In the second mixture preparation step, a second mixture is prepared containing the mixture obtained in the first heat treatment step and a nonionic surfactant.

[0077] The temperature conditions in this process are not particularly limited; for example, they may be within the range of 10 to 40°C, but are not limited to this range. Furthermore, it is generally preferable to carry out the process in an inert gas atmosphere. For example, nitrogen gas, helium gas, argon gas, etc., can be suitably used.

[0078] The type and amount of nonionic surfactant used can be the same as those described in "1. Surface-Modified Inorganic Oxide Powder" above.

[0079] Second heat treatment process In the second heat treatment step, the second mixture obtained in the second mixture preparation step is heat-treated at a temperature of 100 to 200°C.

[0080] The heat treatment temperature is not limited, but is usually 100-200°C, and particularly preferably 100-150°C. If the heat treatment temperature exceeds 200°C, partial decomposition of the nonionic surfactant may occur. If the temperature is below 100°C, sufficient surface modification by the nonionic surfactant may not occur, and the desired properties may not be obtained.

[0081] The heat treatment atmosphere, as in the previous step, is preferably carried out in an inert gas atmosphere. For example, nitrogen gas, helium gas, argon gas, etc., can be suitably used. In particular, the previous step can be carried out in a sealed reactor, and the heat treatment step can be suitably carried out while maintaining the same atmosphere.

[0082] The heat treatment time should be sufficient to allow the nonionic surfactant to be uniformly distributed and fixed to the surface of each particle constituting the inorganic oxide powder, and can be, for example, 10 to 200 minutes, but is not limited to this.

[0083] 3. Use of the powder of the present invention The powder of the present invention possesses the properties described in "1. Surface-Modified Inorganic Oxide Powder" above, and therefore exhibits excellent properties of inorganic oxide particles (especially inorganic oxide particles produced by the gas phase method), as well as excellent charge stability (environmental stability) in which the difference in charge amount between HH conditions and LL conditions is small and well controlled.

[0084] Therefore, the powder of the present invention can be suitably used as an additive (particularly an external additive for toners) to toners, powder coatings, etc. Accordingly, the present invention also encompasses electrophotographic toner compositions or powder coating compositions (hereinafter, both are collectively referred to as "the composition of the present invention") that contain the powder of the present invention and binder resin particles.

[0085] The composition of the present invention contains the surface-modified inorganic oxide powder of the present invention described above, and there are no particular restrictions on its composition, manufacturing method, etc., and known compositions and methods can also be used.

[0086] The content of the powder of the present invention in the composition of the present invention is not particularly limited as long as the desired property improvement effect is obtained, but it is usually preferable that it is contained in an amount of about 0.1 to 5.0% by weight. If the content of the powder of the present invention in the composition of the present invention is less than 0.1% by weight, the effect of improving fluidity or stabilizing the electrostatic environment due to the addition of the powder of the present invention may not be sufficiently obtained. Furthermore, if the content of the powder of the present invention exceeds 5.0% by weight, the amount of powder acting independently increases, which may cause problems such as image quality and cleaning properties.

[0087] In addition to binder resin particles, the composition of the present invention may optionally contain, for example, pigments, charge control agents (static control agents), waxes, etc. These components may be the same as those in known or commercially available toner compositions. Furthermore, while negatively charged toner is preferred, the toner type is not particularly limited in other respects. Therefore, for example, either a magnetic or non-magnetic one-component toner or a two-component toner may be used. Moreover, it may be either monochrome or color.

[0088] Furthermore, in the electrophotographic toner composition of the present invention, the powder of the present invention as an external additive is not limited to being used alone, but may be used in combination with other metal oxide fine powders depending on the purpose. For example, the hydrophobic inorganic oxide powder of the present invention can be used in combination with other surface-modified dry silica fine powders, surface-modified dry titanium oxide fine powders, surface-modified wet titanium oxide fine powders, etc., as needed. [Examples]

[0089] Examples and comparative examples are shown below to give a more detailed explanation of the features of the present invention. However, the scope of the present invention is not limited to the examples.

[0090] [Example 1] BET specific surface area is 200m 2Gas-phase silica (trade name AEROSIL® 200, manufactured by Nippon Aerosil) was placed in a reaction vessel, and under a nitrogen atmosphere, 15.0 g of hexamethyldisilazane (trade name Dynasylan® HMDS, manufactured by Evonik Industries AG) was sprayed onto 100 g of the powder as a hydrophobic agent while stirring. After heating and stirring at 150°C for 60 minutes, the mixture was cooled to obtain hydrophobic inorganic oxide powder 1 surface-treated with the hydrophobic agent. Subsequently, under a nitrogen atmosphere, a solution of 10.0 g of glycerin laurate dissolved in 10 g of hexane was sprayed onto hydrophobized inorganic oxide powder 1, heated to 100°C, and then cooled to obtain surface-modified inorganic oxide powder 1.

[0091] [Example 2] Surface-modified inorganic oxide powder 2 was obtained by performing the same treatment as in Example 1, except that 10.0 g of pentaethylene glycol monodecyl ether was used as a nonionic surfactant for hydrophobic inorganic oxide powder 1.

[0092] [Example 3] Surface-modified inorganic oxide powder 3 was obtained by performing the same procedure as in Example 1, except that 10.0 g of bis-2-hydroxyethyl isotridecyloxypropylamine (trade name Tomamine® E-17-2, manufactured by Evonik Industries AG) was used as a nonionic surfactant for hydrophobic inorganic oxide powder 1.

[0093] [Example 4] Surface-modified inorganic oxide powder 4 was obtained by performing the same procedure as in Example 1, except that 10.0 g of bis-2-hydroxyethyl isodecyloxypropylamine (trade name Tomamine® E-14-2, manufactured by Evonik Industries AG) was used as a nonionic surfactant for hydrophobized inorganic oxide powder 1.

[0094] [Example 5] Surface-modified inorganic oxide powder 5 was obtained by performing the same procedure as in Example 1, except that 10.0 g of poly-(5)-oxyethylene isodecyloxypropylamine (trade name Tomamine® E-14-5, manufactured by Evonik Industries AG) was used as a nonionic surfactant for hydrophobic inorganic oxide powder 1.

[0095] [Example 6] Surface-modified inorganic oxide powder 6 was obtained by performing the same procedure as in Example 1, except that 10.0 g of polybis-(2-hydroxyethyl)oxyethylene cocoalkyloxypropylamine (trade name Tomamine® EC-15, manufactured by Evonik Industries AG) was used as a nonionic surfactant for hydrophobic inorganic oxide powder 1.

[0096] [Example 7] AEROSIL® R974 (manufactured by Nippon Aerosil Co., Ltd.) was used as a commercially available hydrophobized inorganic oxide powder. 10.0 g of bis-2-hydroxyethyl isotridecyloxypropylamine (trade name Tomamine® E-17-2, manufactured by Evonik Industries AG) was sprayed onto it as a nonionic surfactant, and after heating to 100°C and cooling, surface-modified inorganic oxide powder 7 was obtained.

[0097] [Example 8] Except for using 15.0 g of isobutyltrimethoxysilane (trade name Dynasylan®, IBTMO, manufactured by Evonik Industries AG) as a hydrophobic agent, the same treatment as in Example 3 was carried out to obtain surface-modified inorganic oxide powder 8.

[0098] [Example 9] Except for using 20.0 g of dimethyl silicone oil (product name KF-96-100CS, manufactured by Shin-Etsu Chemical Co., Ltd.) as a hydrophobic agent and heating conditions of 300°C for 20 minutes, the same treatment as in Example 3 was carried out to obtain surface-modified inorganic oxide powder 9.

[0099] [Example 10] BET specific surface area 50m 2 Using vapor-phase silica (trade name AEROSIL® 50, manufactured by Nippon Aerosil) at a concentration of / g, and adding 3.8g of hexamethyldisilazane (trade name Dynasylan® HMDS, manufactured by Evonik Industries AG) and 2.5g of bis-2-hydroxyethylisotridecyloxypropylamine (trade name Tomamine® E-17-2, manufactured by Evonik Industries AG), the same treatment as in Example 3 was carried out to obtain surface-modified inorganic oxide powder 10.

[0100] [Example 11] BET specific surface area is 380m² 2 Using vapor-phase silica (trade name AEROSIL® 380, manufactured by Nippon Aerosil) at a concentration of / g, and adding 28.5g of hexamethyldisilazane (trade name Dynasylan® HMDS, manufactured by Evonik Industries AG) and 19.0g of bis-2-hydroxyethylisotridecyloxypropylamine (trade name Tomamine® E-17-2, manufactured by Evonik Industries AG), the same treatment as in Example 3 was carried out to obtain surface-modified inorganic oxide powder 11.

[0101] [Example 12] BET specific surface area is 100m 2 Using gas-phase alumina (trade name AEROXIDE® Alu C, manufactured by Evonik Industries AG) at a concentration of / g, and using isobutyltrimethoxysilane (trade name Dynasylan® IBTMO, manufactured by Evonik Industries AG) 7.5g and bis-2-hydroxyethylisotridecyloxypropylamine (trade name Tomamine® E-17-2, manufactured by Evonik Industries AG) 5.0g as hydrophobicity imparters, the same treatment as in Example 1 was carried out to obtain surface-modified inorganic oxide powder 12.

[0102] [Example 13] BET specific surface area: 90m 2Using a gas-phase titania (trade name AEROXIDE® TiO2P90, manufactured by Nippon Aerosil) at a concentration of / g, and using isobutyltrimethoxysilane (trade name Dynasylan® IBTMO, manufactured by Evonik Industries AG) 6.8g and bis-2-hydroxyethylisotridecyloxypropylamine (trade name Tomamine® E-17-2, manufactured by Evonik Industries AG) 4.5g as hydrophobicity imparters, the same treatment as in Example 1 was carried out to obtain surface-modified inorganic oxide powder 13.

[0103] [Example 14] BET specific surface area is 170m² 2 The same treatment as in Example 1 was performed to obtain surface-modified inorganic oxide powder 14, except that a gas-phase silica-alumina composite oxide (trade name AEROSIL® MOX 170, manufactured by Evonik Industries AG) was used at a concentration of / g, and 12.8g of isobutyltrimethoxysilane (trade name Dynasylan® IBTMO, manufactured by Evonik Industries AG) and 8.5g of bis-2-hydroxyethylisotridecyloxypropylamine (trade name Tomamine® E-17-2, manufactured by Evonik Industries AG) were used as hydrophobic agents.

[0104] [Example 15] A surface-modified inorganic oxide powder 15 was obtained by performing the same procedure as in Example 1, except that 3.0 g of bis-2-hydroxyethyl isotridecyloxypropylamine (trade name Tomamine® E-17-2, manufactured by Evonik Industries AG) was used as a nonionic surfactant for 1 hydrophobic inorganic oxide powder.

[0105] [Example 16] The same procedure as in Example 1 was followed to obtain surface-modified inorganic oxide powder 16, except that 5.0 g of bis-2-hydroxyethyl isotridecyloxypropylamine (trade name Tomamine® E-17-2, manufactured by Evonik Industries AG) was used as a nonionic surfactant for hydrophobic inorganic oxide powder 1.

[0106] [Example 17] A surface-modified inorganic oxide powder 17 was obtained by performing the same procedure as in Example 1, except that 20.0 g of bis-2-hydroxyethyl isotridecyloxypropylamine (trade name Tomamine® E-17-2, manufactured by Evonik Industries AG) was used as a nonionic surfactant with respect to hydrophobic inorganic oxide powder 1.

[0107] [Example 18] A surface-modified inorganic oxide powder 18 was obtained by performing the same procedure as in Example 1, except that 30.0 g of bis-2-hydroxyethyl isotridecyloxypropylamine (trade name Tomamine® E-17-2, manufactured by Evonik Industries AG) was used as a nonionic surfactant with respect to hydrophobic inorganic oxide powder 1.

[0108] [Comparative Example 1] A surface-modified inorganic oxide powder 19 was obtained by performing the same procedure as in Example 1, except that a solution was used in which 10.0 g of sodium stearate, an anionic surfactant, was dissolved in 10 g of ethanol instead of a nonionic surfactant, for the hydrophobic inorganic oxide powder 1.

[0109] [Comparative Example 2] Surface-modified inorganic oxide powder 20 was obtained by performing the same procedure as in Example 1, except that a solution was used in which 10.0 g of hexadecyltrimethylammonium bromide, a cationic surfactant, was dissolved in 30 g of ethanol instead of a nonionic surfactant, for hydrophobized inorganic oxide powder 1.

[0110] [Comparative Example 3] BET specific surface area is 200m 2Gas-phase silica (trade name AEROSIL® 200, manufactured by Nippon Aerosil) was placed in a reaction vessel, and 10.0 g of the nonionic surfactant bis-2-hydroxyethyl isotridecyloxypropylamine (trade name Tomamine® E-17-5, manufactured by Evonik Industries AG) was sprayed onto 100 g of the powder while stirring under a nitrogen atmosphere. After heating to 100°C and then cooling, surface-modified inorganic oxide powder 21 was obtained.

[0111] [Comparative Example 4] A surface-modified inorganic oxide powder 22 was obtained by performing the same procedure as in Example 1, except that 1.0 g of bis-2-hydroxyethyl isotridecyloxypropylamine (trade name Tomamine® E-17-2, manufactured by Evonik Industries AG) was used as a nonionic surfactant for 1 hydrophobic inorganic oxide powder.

[0112] [Comparative Example 5] A surface-modified inorganic oxide powder 23 was obtained by performing the same procedure as in Example 1, except that 40.0 g of bis-2-hydroxyethyl isotridecyloxypropylamine (trade name Tomamine® E-17-2, manufactured by Evonik Industries AG) was used as a nonionic surfactant for hydrophobic inorganic oxide powder 1.

[0113] [Comparative Example 6] The same procedure as in Example 1 was performed, except that 5.0 g of hexamethyldisilazane (trade name Dynasylan® HMDS, manufactured by Evonik Industries AG) was used as a hydrophobic agent. i, table A surface-modified inorganic oxide powder 24 was obtained.

[0114] [Test Example 1] The following physical properties were measured for each surface-modified inorganic oxide powder obtained in each example and comparative example. The results are shown in Table 1.

[0115] (1) Hydrophobicity Place a stirring bar and 50 mL of water in a 200 mL beaker, and add 0.2 g of the sample to be measured. Stir with a magnetic stirrer. Stir at a speed that does not cause the powder on the surface of the liquid to become turbulent. Pour methanol into a burette, and slowly mix the methanol into the liquid while stirring with the tip of the burette submerged in the liquid. The endpoint is the point at which the sample is no longer visible on the surface of the liquid, and the amount of methanol added at that point (mL) is used to calculate the hydrophobicity (%) using the following formula. Hydrophobicity (%) = [Amount of drop / (Amount of drop + 50)] × 100 Furthermore, in this test, when 150 mL of methanol is added dropwise, the beaker becomes full and no more can be added. In this case, the hydrophobicity is calculated as [150 / (150+50)] × 100 = 75%, and is therefore expressed as ">75%". In other words, although the upper limit of hydrophobicity is theoretically 100%, as mentioned above, due to the measurement method, values ​​exceeding 75% cannot be measured, so values ​​exceeding 75% are expressed as ">75%".

[0116] (2) Toner charge amount A toner composition was obtained by stirring and mixing 2.0 g of nonionic surfactant-treated inorganic oxide and 98.0 g of negatively charged toner (polyester resin, average particle size 7 μm) in a mixer. Then, 2.0 g of this toner composition and 48.0 g of iron powder carrier (silicone resin-coated ferrite, average particle size 35 μm) were placed in a glass container (75 mL capacity) to prepare a mixture. Two identical samples of the mixture were prepared to measure the amount of charge. One sample was left to stand for 40 hours under high temperature and high humidity conditions (HH conditions: temperature 35°C, relative humidity 80%). The other sample was left to stand for 40 hours under low temperature and low humidity conditions (LL conditions: temperature 10°C, relative humidity 10%). Each sample prepared under the above conditions was shaken in a turbler mixer at 24 rpm for 10 minutes. 0.05 g of the mixture was taken, and the charge was measured using a blow-off charge measurement device (MODEL230TO) manufactured by Trek Japan Co., Ltd.

[0117] [Table 1]

[0118] As is clear from the results in Table 1, the surface-modified inorganic oxide powders in the examples satisfy all the properties specified in the present invention and exhibit excellent electrostatic stability.

Claims

1. A powder comprising composite particles including inorganic oxide particles and a film formed on the surface of those particles, (1) The coating comprises a hydrophobic agent and a nonionic surfactant, (2) The hydrophobicity of the powder is 40% or more, (3) The nonionic surfactant is the following general formula (1): 【Transformation 5】 [In the formula, R represents a linear or branched hydrocarbon group having 8 to 18 carbon atoms, which may have unsaturated bonds; x represents an integer of 1 or more; n represents an integer of 2 or more; and x and n satisfy n > x.] It is an ethoxylated aliphatic amine having a basic skeleton derived from a tertiary amino group, represented by the following: A surface-modified inorganic oxide powder characterized by the following features.

2. The content (g) of nonionic surfactant is expressed as the BET specific surface area (m²) of the inorganic oxide particles. ２ The surface-modified inorganic oxide powder according to claim 1, wherein the value obtained by dividing by ( / g) is 0.015 to 0.

150.

3. Hydrophobicity-imparting agents, (a) General formula (2) below: 【Transformation 6】 (In the formula, R １ R represents a hydrocarbon group having 1 to 18 carbon atoms. ２ , R ３ and R ４ These represent, either identical or different from each other, a chlorine atom, a hydroxyl group, or an alkoxy group having 1 to 3 carbon atoms.) Alkylsilanes represented by (b) Silicone oil and (c) Hexamethyldisilazane The surface-modified inorganic oxide powder according to claim 1 or 2, which is at least one selected from the group consisting of the following.

4. The inorganic oxide particles are at least one selected from the group consisting of gas-phase silica particles, gas-phase alumina particles, and gas-phase titania particles, and their BET specific surface area is 30 to 400 m². ２ A surface-modified inorganic oxide powder according to any one of claims 1 to 3, wherein the amount is / g.

5. In the toner obtained by externally adding the surface-modified inorganic oxide powder to negatively charged polyester-based binder resin particles, the charge amount C ＬＬ (μC / g) after 40 hours under the conditions of a temperature of 10°C and a relative humidity of 10% is divided by the charge amount C ＨＨ (μC / g) after 40 hours under the conditions of a temperature of 35°C and a relative humidity of 80% to obtain a value [C ＬＬ / C ＨＨ ] of 1.55 or less. The surface-modified inorganic oxide powder according to any one of claims 1 to 4.

6. An external additive for toner or powder coating, comprising the surface-modifying inorganic oxide powder described in any one of claims 1 to 5.

7. An electrophotographic toner composition or powder coating composition comprising the external additive described in claim 6 and binding resin particles.

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