JP2023067180A - Surface-modified inorganic oxide powder modified with nonionic surfactant - Google Patents

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

The present invention relates to novel surface-modified inorganic oxide powders. In particular, it relates to a surface-modified inorganic oxide powder whose surface is modified with a nonionic surfactant.

Generally, in the electrophotographic method used in laser printer copiers and the like, a) a step of charging a photoreceptor, and b) a step of forming an electrostatic latent image by irradiating the charged photoreceptor with a laser beam. c) depositing charged toner onto the electrostatic latent imaged photoreceptor to develop a mirror image of the image on the photoreceptor; d) transferring the toner deposited on the photoreceptor to a print medium such as paper; e) Printing is performed by a process of fixing the toner on the printing medium by heating and pressure using a hot roller or the like.

Toner is agitated in an apparatus such as a copier and is charged (that is, electrified) by friction with a carrier or the like. Further, the developing function can be expressed by the highly controlled chargeability. The process of triboelectrically charging the toner is very important because electrostatic attraction is responsible for image formation.

However, since the target toner charge amount differs depending on the printing machine, it is required to adjust the charge amount to an optimum value. Furthermore, since printing presses are used in various environments in countries and regions, it is necessary that the amount of charge varies as little as possible under any temperature and humidity environment. In particular, it is an important property of the toner that the charge amount difference is small even under extreme conditions of high temperature and high humidity (HH) and low temperature and low humidity (LL) conditions.

In order to obtain the above performance, a surface-modified inorganic oxide is used in which the surface of inorganic oxide powder such as fine silica, titania, and alumina is treated with an organic substance. By treating the inorganic oxide surface with various organic groups, it is possible to modify the chargeability, hydrophobicity, etc. of the powder surface. Surface-modified inorganic oxide powders used for such toner applications are known as so-called external additives.

Organic silicon compounds such as dimethyldichlorosilane, hexamethyldisilazane, and silicone oil are known as surface treatment agents for inorganic oxide powders used in toner applications. By surface treatment with these organosilicon compounds, for example, silanol groups on the surface of silica fine particles can be substituted with organic groups for hydrophobization.

In practice, hydrophobized small particle size silica is widely used to control fluidity and chargeability. However, when silica having a small particle size is used, although the fluidity of the toner is improved, there is a problem that the charge amount difference between the HH condition and the LL condition becomes large.

As a conventional technology related to such inorganic oxide particles, for example, a non-magnetic one-component color developer is known in which inorganic fine powder hydrophobized with silicone oil is mixed with specific colored fine particles (Patent Document 1). However, with the inorganic fine powder of Patent Document 1, not only the charge amount under the HH condition but also the charge amount under the LL condition increases.

In addition, a method of adding surface-treated silica treated with aminosilane or amino-modified silicone oil has also been proposed in order to alleviate excessive negative chargeability under LL conditions (Patent Documents 2 and 3). However, the methods of Patent Documents 2 and 3 have a problem that the negative chargeability is lowered under HH conditions where the charge amount tends to be insufficient.

In order to solve this problem, in recent years, it has been proposed to use a hydrophobized titania or the like as an external additive (Patent Documents 4 and 5). However, although the use of titania can reduce the difference in charge amount due to changes in the environment, in addition to the contamination of parts of printing presses with titania, there have been concerns about the carcinogenicity of titania in recent years, which has led to safety issues. ing.

JP-A-5-165257 JP-A-1-73354 JP-A-1-237561 JP-A-10-268550 JP 2009-42447 A

For the above reasons, the development of an inorganic oxide powder that has a smaller charge amount difference between the toner under the HH condition and the LL condition and is suitable for toner applications is desired. not yet developed.

Accordingly, a main object of the present invention is to provide an inorganic oxide powder having a smaller difference in charge quantity between high temperature and high humidity conditions and low temperature and low humidity conditions.

As a result of intensive research in view of the problems of the prior art, the inventors of the present invention have found that specific inorganic oxide particles surface-modified with a nonionic surfactant and an appropriate hydrophobizing agent achieve the above object. I found that it can be done, and came to complete the present invention.

［式中Ｒは、直鎖型又は分岐型であって、不飽和結合を有していても良い炭素数８～１８の炭化水素基を示し、ｘは１以上の整数、ｎは２以上の整数をそれぞれ示し、ｘ及びｎはｎ＞ｘを満たす。］
で表される３級アミノ基由来の基本骨格を有するエトキシ化脂肪族アミンである、前記項１又は２に記載の表面改質無機酸化物粉末。
４． 疎水性付与剤が、
（ａ）下記一般式（２）：

（式中、Ｒ^１は、炭素数１以上１８以下の炭化水素基を表し、Ｒ^２、Ｒ^３及びＲ^４は、互いに同一又は異なって、塩素原子、ヒドロキシ基又は炭素数１～３のアルコキシ基を示す。）で示されるアルキルシラン類、
（ｂ）シリコーンオイル及び
（ｃ）ヘキサメチルジシラザン
からなる群から選択された少なくとも１種である、前記項１～３のいずれかに記載の表面改質無機酸化物粉末。
５． 無機酸化物粒子が、気相法シリカ粒子、気相法アルミナ粒子及び気相法チタニア粒子からなる群から選択された少なくとも１種であり、かつ、そのＢＥＴ比表面積が３０～４００ｍ^２／ｇである、前記項１～４のいずれかに記載の表面改質無機酸化物粉末。
６． 当該表面改質無機酸化物粒子を負帯電性ポリエステル系結着性樹脂粒子に外添したトナーにおいて、温度１０℃・相対湿度１０％の条件下で４０時間経過した時の帯電量Ｃ_ＬＬ（μＣ／ｇ）を、温度３５℃・相対湿度８０％の条件下で４０時間経過した時の帯電量Ｃ_ＨＨ（μＣ／ｇ）で除した値［Ｃ_ＬＬ／Ｃ_ＨＨ］が１．５５以下である、前記項１～５のいずれかに記載の表面改質無機酸化物粉末。
７． 前記項１～６のいずれかに記載の表面改質無機酸化物粉末を含むトナー用又は粉体塗料用の外添剤。
８． 前記項７に記載の外添剤と結着性樹脂粒子とを含む電子写真用トナー組成物又は粉体塗料組成物。 That is, the present invention relates to the following surface-modified inorganic oxide powder.
1. A powder composed of composite particles containing inorganic oxide particles and a coating formed on the particle surface,
(1) the film contains a hydrophobicity imparting agent and a nonionic surfactant,
(2) the powder has a hydrophobicity of 40% or more,
A surface-modified inorganic oxide powder characterized by:
2. The surface modification according to claim 1, wherein the value obtained by dividing the content (g) of the nonionic surfactant by the BET specific surface area (m ² /g) of the inorganic oxide particles is 0.015 to 0.150. Inorganic oxide powder.
3. The nonionic surfactant has the following general formula (1):

[In the formula, R represents a straight-chain or branched hydrocarbon group having 8 to 18 carbon atoms which may have an unsaturated bond, x is an integer of 1 or more, and n is 2 or more. Each denote an integer, and x and n satisfy n>x. ]
3. 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. Hydrophobicity-imparting agent
(a) the following general formula (2):

(In the formula, R ¹ represents a hydrocarbon group having 1 to 18 carbon atoms; R ² , R ³ and R ⁴ are the same or different from each other and are a chlorine atom, a hydroxy group, or an alkoxy group having 1 to 3 carbon atoms; group.) Alkylsilanes represented by
4. The surface-modified inorganic oxide powder according to any one of Items 1 to 3, which is at least one selected from the group consisting of (b) silicone oil and (c) hexamethyldisilazane.
5. The inorganic oxide particles are at least one selected from the group consisting of fumed silica particles, fumed alumina particles and fumed titania particles, and have a BET specific surface area of 30 to 400 m ² /g. 5. The surface-modified inorganic oxide powder according to any one of Items 1 to 4.
6. The charge amount C _LL (μC /g) divided by the charge amount C _HH (μC/g) after 40 hours at a temperature of 35° C. and a relative humidity of 80% [C _LL /C _HH ] is 1.55 or less. 6. The surface-modified inorganic oxide powder according to any one of 1 to 5 above.
7. 7. An external additive for toner or powder coating containing the surface-modified inorganic oxide powder according to any one of 1 to 6 above.
8. 8. An electrophotographic toner composition or powder coating composition comprising the external additive according to item 7 and binder resin particles.

According to the present invention, it is possible to provide an inorganic oxide powder with a smaller charge amount difference between HH conditions and LL conditions. 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 charge amount under HH conditions and , LL conditions are controlled to be low. More specifically, as shown in _Examples and the like below, the _ratio [C _LL /C _HH ] closer to 1 can be obtained. In other words, the fluctuation of the charge amount due to the difference in use environment is relatively small, and excellent charge stability can be exhibited.

Thus, the powder of the present invention, which is excellent in charge stability, can be suitably used as an external additive for toners or powder coatings. Therefore, the electrophotographic toner composition or powder coating composition containing the surface-modified inorganic oxide powder of the present invention can reduce the difference in charge amount between HH and LL conditions. As a result, effects such as long-term storage stability and control of developer deterioration behavior can be obtained.

1. Surface-Modified Inorganic Oxide Powder The surface-modified inorganic oxide powder modified with a nonionic surfactant of the present invention (powder of the present invention) contains inorganic oxide particles and a film formed on the particle surface. A powder composed of composite particles,
(1) the film contains a hydrophobicity imparting agent and a nonionic surfactant,
(2) the powder has a hydrophobicity of 40% or more,
It is characterized by

<Configuration (composition) of the powder of the present invention>
The particles constituting the powder of the present invention are composed of composite particles containing inorganic oxide particles and coatings formed on the particle surfaces. The film contains a hydrophobicity-imparting agent and a nonionic surfactant.

That is, the above-described composite particles have a basic structure in which inorganic oxide particles are used as core particles (original material), and a part or all of the surface is coated with a film containing an organosilicon compound and a nonionic surfactant. do.

The type of inorganic oxide particles that serve as core particles is not limited, but at least one of silica, titania, alumina, and the like can be preferably used. Moreover, particles of a mixed oxide (double oxide) containing these oxides may be used. Known or commercially available particles can be used for these particles themselves.

The particle size of the inorganic oxide particles is not limited, but usually the primary particle size should be about 5 to 150 nm. The BET specific surface area of the inorganic oxide particles is generally about 30 to 400 m ² /g, but is not limited to this.

In addition, in the present invention, it is preferable to use powder obtained by a vapor phase method (fumed method) as the inorganic oxide particles. The gas phase method itself is a known manufacturing method (synthetic method). For example, in the case of manufacturing silica particles, a step of introducing a silicon compound (silicon tetrachloride, etc.) or metallic silicon into an oxygen-hydrogen flame to cause a hydrolysis reaction. can be synthesized by a method including Since such a powder has a particle shape that is more non-spherical than silica produced by the sol-gel method, it has the advantage of being able to effectively suppress separation from the toner surface. In addition, since no solvent is used, there is the advantage that no agglomerated particles are formed during drying.

Therefore, in the present invention, it is preferable to use inorganic oxide particles (fumed particles) produced by the gas phase method 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. Known or commercially available inorganic oxide particles can be used as the inorganic oxide particles produced by the vapor phase method. For example, commercially available products shown in Examples below can also be suitably used.

In addition, in the present invention, a stepwise treatment can be used in which inorganic oxide particles which have been hydrophobized in advance are used as core particles, and the core particles are treated with a nonionic surfactant. In this case, known or commercially available hydrophobized inorganic oxides can be used as the core particles. For example, commercially available hydrophobized inorganic oxide powders shown in Examples below can also be suitably used.

The hydrophobicity imparting agent contained in the film is not particularly limited, and for example, known or commercially available hydrophobicity imparting agents can be used.

More specifically, alkylsilazane compounds (organosilazanes) such as tetramethyldisilazane, hexamethyldisilazane (HMDS), pentamethyldisilazane; Alkylalkoxysilane compounds such as methoxysilane and butyltrimethoxysilane; chlorosilane compounds such as dimethyldichlorosilane and trimethylchlorosilane; silicone oils such as polydimethylsiloxane (PDMS); These may be used individually by 1 type, and may be used in mixture of 2 or more types.

Among these, it is preferable to use at least one of alkylsilazane-based compounds, alkylalkoxysilane-based compounds, silicone oil, and the like, since the effects of the present invention can be obtained more reliably. In particular, at least one of hexamethyldisilazane, polydimethylsiloxane, alkylalkoxysilane and the like is more preferable.

（式中、Ｒ^１は、炭素数１～１８の炭化水素基を示す。Ｒ^２、Ｒ^３及びＲ^４は、互いに同一又は異なって、塩素原子、ヒドロキシ基又は炭素数１～３のアルコキシ基を示す。）で示されるアルキルシラン類、
（ｂ）シリコーンオイル及び
（ｃ）ヘキサメチルジシラザン
からなる群から選択された少なくとも１種も好適に用いることができる。 Also among these, in particular, the following general formula (2):

(wherein R ¹ represents a hydrocarbon group having 1 to 18 carbon atoms; R ² , R ³ and R ⁴ are the same or different from each other and are chlorine atoms, hydroxy groups or alkoxy groups having 1 to 3 carbon atoms; shows.) Alkylsilanes represented by
At least one selected from the group consisting of (b) silicone oil and (c) hexamethyldisilazane can also be preferably used.

Among these, at least one of (a) alkylalkoxysilanes included in the above alkylsilanes, (b) silicone oil, and (c) hexamethyldisilazane is more preferable.

The alkylalkoxysilane is not particularly limited as long as it is an alkoxysilane having an alkyl group, and examples thereof include trimethoxyalkoxysilane and triethoxyalkoxysilane. In the alkylalkoxysilane, the number of carbon atoms (C) in the alkyl group is not particularly limited, but preferably C2 to C18. If it is less than C2, the alkoxysilane may volatilize during surface treatment. On the other hand, if it exceeds C18, strong aggregation may occur due to the influence of the high viscosity, and the dispersibility of the obtained powder may be impaired.

As the above silicone oil, in addition to polydimethylsiloxane as described above, modified silicone oil into which an alkyl group, —OH group, or the like is introduced can also be used.

The viscosity range of the hydrophobicity-imparting agent (measurement temperature 25° C.) is not particularly limited, but it is usually preferably 20 to 300 cs. If the viscosity is less than 20 cs, volatilization of low-molecular-weight polysiloxane occurs during surface treatment, which is undesirable from the viewpoint of energy efficiency, environment, and the like. On the other hand, if the viscosity exceeds 300 cs, higher aggregation may occur and the dispersibility of the resulting powder may be impaired.

The content of the hydrophobicity-imparting agent in the powder of the present invention is not particularly limited as long as the desired hydrophobicity can be obtained. It is desirable to use 2 to 30 parts by weight.

The powder of the present invention contains a nonionic surfactant together with a hydrophobicity-imparting agent in its film. According to the present invention, the surface of particles treated with a hydrophobicity-imparting agent is further surface-treated with a nonionic surfactant. As a result, an appropriate amount of water can be adsorbed, which contributes to the improvement of charging stability. can do. In other words, the charge amount difference between the HH condition and the LL condition is considered to be caused by the moisture adsorption amount, and it can be said that the charging stability is ensured by controlling such an adsorption amount. In this respect, a structure having a layer containing a hydrophobicity-imparting agent on the surface of the inorganic oxide particles and a layer containing a nonionic surfactant on the layer is a preferred example, but is not limited to this. Here, the reason why hydrophobicity is imparted by a hydrophobicity-imparting agent is that, when treated with only a nonionic surfactant, water is adsorbed excessively, resulting in almost no charge under HH conditions.

On the other hand, when anionic surfactants are used for the treatment, although the reason for this is not clear, their high water adsorption capacity reduces the chargeability under HH conditions compared to nonionic surfactants.

From this point of view, in the present invention, a combination of a hydrophobic treatment agent and a nonionic surfactant is used, and among them, a nonionic surfactant containing a tertiary amino group is more preferable, as will be described later. Although the reason why this results in better charging stability is not clear, for example, when the inorganic oxide particles are silica, the strong interaction between the silanol group and the amino group makes the surface modification efficient. This is thought to be a factor. In addition, it is speculated that the effect of suppressing the impartation of strong negative chargeability to the powder after surface treatment due to the effect of imparting positive chargeability due to the amino group is also one of the factors.

The nonionic surfactant contained in the film is not particularly limited, and for example, known or commercially available nonionic surfactants can be used. Although the hydrophilic group of the nonionic surfactant is not limited, polyoxyethylene chains, polyoxypropylene chains and the like are preferable, and polyoxyethylene chains are particularly preferable.

More specifically, various nonionic surfactants such as esters, ethers, ester ethers, alkylglycooxides and ethoxylated amines can be used. These can be used singly or in combination of two or more.

Examples of esters that can be used include glyceryl laurate, glyceryl monostearate, sorbitan fatty acid ester, sucrose fatty acid ester, and the like.

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

Examples of ester ethers that can be used include polyoxyethylene glycerin fatty acid ester, polyoxyethylene castor oil, polyoxyethylene sorbitan fatty acid ester, and the like.

Examples of alkyl glycosides that can be used include octyl glucoside, decyl glucoside, lauryl glucoside, and the like.

［式中Ｒは、直鎖型又は分岐型であって、不飽和結合を有していても良い炭素数８～１８の炭化水素基を示し、ｘは１以上の整数、ｎは２以上の整数をそれぞれ示し、ｘ及びｎはｎ＞ｘを満たす。］
で表される３級アミノ基由来の基本骨格を有するエトキシ化脂肪族アミンを挙げることができる。 As ethoxylated amines, the following general formula (1):

[In the formula, R represents a straight-chain or branched hydrocarbon group having 8 to 18 carbon atoms which may have an unsaturated bond, x is an integer of 1 or more, and n is 2 or more. Each denote an integer, and x and n satisfy n>x. ]
An ethoxylated aliphatic amine having a basic skeleton derived from a tertiary amino group represented by can be mentioned.

Among these, at least one kind of ethoxylated amines is used in that the effect of the present invention (especially the effect of reducing the charge amount difference between the HH condition and the LL condition) can be obtained more reliably. is preferred, and ethoxylated aliphatic amines represented by the above general formula (1) are particularly preferred. In the above general formula (1), particularly by setting the number of carbon atoms of R in the range of 8 to 18 (preferably 10 to 16), it is possible to impart higher hydrophobicity and effectively aggregate the core particles. By preventing this, it becomes possible to obtain higher dispersibility.

Although n and x in the general formula (1) are not limited, from the viewpoint of obtaining the effects of the amino group as described above, the number average molecular weight of the ethoxylated aliphatic amine is an integer of 1200 or less. is preferred. Therefore, n and x can be set so that the number average molecular weight is about 300 to 900, but not limited to this.

Specific examples of such ethoxylated aliphatic amines include bis-2-hydroxyethylisotridecyloxypropylamine, bis-2-hydroxyethylisotridecyloxypropylamine, poly-(5)-oxyethyleneisodecyloxypropyl amine, polybis-(2-hydroxyethyl)oxyethylene cocoalkyloxypropylamine, and the like. Commercially available products can also be used for these. More specifically, products such as those shown in Examples below can be preferably used.

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, particularly 2 to 30 parts by weight, relative to 100 parts by weight of the inorganic oxide particles. is desirable.

In particular, in the present invention, the content of the nonionic surfactant is more preferably set according to the BET specific surface area of the inorganic oxide particles. That is, the value obtained by dividing the content (g) of the nonionic surfactant by the BET specific surface area (m ² /g) of the inorganic oxide particles is preferably 0.012 to 0.180, particularly 0.015. It is more preferable to set it to ~0.150. As a result, an appropriate amount of water can be adsorbed by surface treatment with a nonionic surfactant, and as a result, an effect of improving charging stability can be obtained.

<Characteristics of the powder of the present invention>
Hydrophobicity The hydrophobicity of the powder of the present invention (powder of composite particles) is usually 40% or more, preferably 50% or more. The hydrophobicity in the present invention is an index indicating the degree of hydrophobicity of the surface-modified inorganic oxide powder, and the larger the numerical value, the higher the hydrophobicity. If the hydrophobicity is less than 40%, the residual silanol groups in the inorganic oxide powder may make it impossible to maintain strong chargeability, and an inorganic oxide powder with excellent chargeability may not be obtained. In the present invention, the upper limit of the hydrophobicity is theoretically 100%, but is not limited to this. In addition, in the present invention, the method of measuring the hydrophobicity is according to the method of Test Example 1 described later.

Average Particle Size The average particle size (secondary particle size) of the powder of the present invention is usually about 0.1 to 10 μm, but is not limited to this.

Charge Amount Ratio under HH Condition and LL Condition The powder of the present invention is characterized in that the difference between the charge amount under HH condition and the charge amount under LL condition is small. More specifically, the charge amount C HH (μC/g) when left for 40 hours at 35° C. and 80% humidity as HH conditions, and the charge amount C _HH (μC/g) when left for 40 hours at 10° C. and 10% humidity as LL conditions. and the charge amount C _LL (μC/g) [C _LL /C _HH ] is usually 1.55 or less, preferably 1.00 to 1.50, especially 1.00 to 1 .20 is more preferred. In the powder of the present invention, the charge amount under HH conditions can be, for example, about −40 to −5 μC/g, but it is not limited to this because it can be changed as appropriate depending on the application, use conditions, etc. . The charge amount under the LL condition can also be -40 to -5 μC/g, but it is not limited to this because it can be changed as appropriate according to the application, use conditions, and the like. Incidentally, in the present invention, the method for measuring these charge amounts is according to the method shown in Test Example 1 below.

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 the powder having the constitution and properties as described above can be obtained. In the present invention, in particular, A) a method including a step of applying a nonionic surfactant and a hydrophobicity-imparting agent to an inorganic oxide powder followed by heat treatment (hereinafter also referred to as "simultaneous treatment"), and B) inorganic oxide particles. A method comprising a step of obtaining a hydrophobized inorganic oxide powder by applying a hydrophobicity-imparting agent to the powder and then heat-treating it, and a step of heat-treating after applying a nonionic surfactant to the hydrophobized inorganic oxide powder (hereinafter "step Also referred to as "processing".), etc. can be suitably adopted. By these methods, the powder of the present invention can be obtained more reliably.

As another method, C) a method including a step of applying a nonionic surfactant to a hydrophobized inorganic oxide powder whose surface has been hydrophobized in advance and then heat-treating the powder can be preferably adopted. According to method C) above, it is possible to use a commercially available hydrophobized inorganic oxide powder, thereby more efficiently preparing the powder of the present invention in one step.

<Simultaneous processing>
The simultaneous treatment is a method including a step of applying a nonionic surfactant and a hydrophobicity-imparting agent to the inorganic oxide powder, followed by heat treatment. More specifically, (a) a step of preparing a mixture containing an inorganic oxide powder, a hydrophobicity imparting agent and a nonionic surfactant (mixture preparation step), (b) the mixture at a temperature of 100 to 200 ° C. It can be suitably produced by a method including a heat treatment step (heat treatment step).

Mixture preparation step The method is not limited as long as the surface of each particle constituting the inorganic oxide powder can be coated with a hydrophobicity imparting agent and a nonionic surfactant, for example, the inorganic oxide powder and the vaporized hydrophobic A method of spraying a nonionic surfactant on a hydrophobized inorganic oxide powder obtained by either a method of mixing with an imparting agent or a method of mixing a hydrophobicity imparting agent with an inorganic oxide powder under stirring, A method of spraying a mixture of a hydrophobicity-imparting agent and a nonionic surfactant under stirring, or the like can be suitably employed.

In this case, the hydrophobicity-imparting agent, the nonionic surfactant, and the mixture of the hydrophobicity-imparting agent and the nonionic surfactant are all dissolved in a solvent (e.g., an organic solvent such as hexane, toluene, and methanol) as necessary. Or it can also be used in a dispersed state. In that case, the concentration of each component can be appropriately set according to the type of hydrophobicity-imparting agent or nonionic surfactant to be used.

In addition, in the present invention, water and a catalyst (amine, etc.) can be appropriately added to the mixture, if necessary.

The temperature conditions in the mixture preparation step are not particularly limited, and may be, for example, within the range of 10 to 40° C., but are not limited thereto. Moreover, the atmosphere is preferably an inert gas atmosphere. For example, nitrogen gas, helium gas, argon gas, etc. can be preferably used.

The types and amounts of the inorganic oxide particles, the hydrophobicity-imparting agent, and the nonionic surfactant may be the same as those described in "1. Surface-modified inorganic oxide powder" above. .

Heat Treatment Step In the heat treatment step, the mixture obtained in the above step is heat treated at a temperature of 100 to 200.degree.

Although the heat treatment temperature in the heat treatment step is not limited, it is usually preferably 100 to 200° C. (especially 150 to 200° C.). If the heat treatment temperature exceeds 200°C, partial decomposition of the nonionic surfactant may occur. On the other hand, if the temperature is less than 100° C., the surface is not sufficiently modified by the hydrophobicity-imparting agent, and the desired hydrophobicity may not be obtained.

As for the heat treatment atmosphere, it is usually preferable to carry out the heat treatment in an inert gas atmosphere, as in the above process. For example, nitrogen gas, helium gas, argon gas, etc. can be preferably used. In particular, it is possible to carry out the above process in a closed reactor, and continue the heat treatment process while maintaining the atmosphere.

The heat treatment time may be a time sufficient for the hydrophobicity-imparting agent or the like to be fixed (adhered) to the surface of each particle constituting the inorganic oxide powder, and can be, for example, about 10 to 200 minutes. , but not limited to.

<Step processing>
The stepwise treatment includes a step of obtaining a hydrophobized inorganic oxide powder by applying a hydrophobicity-imparting agent to the inorganic oxide particles and then heat-treating, and a step of applying a nonionic surfactant to the hydrophobized inorganic oxide powder and then heat-treating. It is a method comprising steps.

More specifically, for example, (a) a step of preparing a first mixture containing inorganic oxide particles and a hydrophobicity imparting agent (first mixture preparation step), (b) the first mixture is heated to a temperature of 100 to 360 ° C. (first heat treatment step), (c) preparing a second mixture containing the mixture obtained by the first heat treatment step and a nonionic surfactant (second mixture preparation step) (d) It can be suitably produced by a method including a step of heat-treating the second mixture at a temperature of 100 to 200° C. (second heat-treating step).

In this case, the hydrophobicity-imparting agent and the nonionic surfactant can be used after being dissolved or dispersed in a solvent (for example, an organic solvent such as hexane, toluene, and methanol) as necessary. The concentration of the organosilicon compound in that case can be appropriately set according to the type of the organosilicon compound used.

In addition, in the present invention, water and a catalyst (amine, etc.) can be appropriately blended in the mixture, if necessary.

First Mixture Preparing Step In the first mixture preparing step, a first mixture containing inorganic oxide particles and a hydrophobicity-imparting agent is prepared.

The temperature conditions in this step are not particularly limited, and may be, for example, within the range of 10 to 40° C., but are not limited thereto. Moreover, the atmosphere is preferably an inert gas atmosphere. For example, nitrogen gas, helium gas, argon gas, etc. can be preferably used.

Regarding the types and amounts of the inorganic oxide particles and the hydrophobicity-imparting agent, the same ones as described in the above "1. Surface-modified inorganic oxide powder" can be employed.

First Heat Treatment Step In the first heat treatment step, the first mixture obtained in the above step is heat treated at a temperature of 100 to 360.degree.

Although the heat treatment temperature is not limited, it is usually 100 to 360°C, preferably 150 to 300°C. If the heat treatment temperature exceeds 360°C, the hydrophobicity-imparting agent may be partially decomposed. On the other hand, if the temperature is less than 100° C., the surface is not sufficiently modified by the hydrophobicity-imparting agent, and the desired hydrophobicity may not be obtained.

As for the heat treatment atmosphere, it is usually preferable to carry out the heat treatment in an inert gas atmosphere, as in the above process. For example, nitrogen gas, helium gas, argon gas, etc. can be preferably used. In particular, it is possible to carry out the above process in a closed reactor, and continue the heat treatment process while maintaining the atmosphere.

The heat treatment time may be a time sufficient for the hydrophobicity-imparting agent to be immobilized (adhered) to the surface of each particle constituting the inorganic oxide powder, and can be, for example, about 10 to 200 minutes. It is not limited to this.

Second Mixture Preparation Step In the second mixture preparation step, a second mixture containing the mixture obtained by the first heat treatment step and a nonionic surfactant is prepared.

The temperature conditions in this step are not particularly limited, and may be, for example, within the range of 10 to 40° C., but are not limited thereto. Moreover, the atmosphere is preferably an inert gas atmosphere. For example, nitrogen gas, helium gas, argon gas, etc. can be preferably used.

As for the type and amount of the nonionic surfactant, the same ones as those explained in the above "1. Surface-modified inorganic oxide powder" can be adopted.

Second Heat Treatment Step 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.degree.

Although the heat treatment temperature is not limited, it is usually 100 to 200°C, preferably 100 to 150°C. If the heat treatment temperature exceeds 200°C, partial decomposition of the nonionic surfactant may occur. On the other hand, if the temperature is less than 100° C., sufficient surface modification by the nonionic surfactant may not be performed, and desired properties may not be obtained.

As for the heat treatment atmosphere, it is usually preferable to carry out the heat treatment in an inert gas atmosphere, as in the above process. For example, nitrogen gas, helium gas, argon gas, etc. can be preferably used. In particular, it is possible to carry out the above process in a closed reactor, and continue the heat treatment process while maintaining the atmosphere.

The heat treatment time may be a time sufficient for the nonionic surfactant to be uniformly arranged and fixed on the surface of each particle constituting the inorganic oxide powder, for example, it can be about 10 to 200 minutes. but not limited to this.

3. Use of the powder of the present invention Since the powder of the present invention has the characteristics shown in the above "1. Surface-modified inorganic oxide powder", it is an excellent inorganic oxide particle (especially inorganic oxide particles obtained by a vapor phase method). In addition to the characteristics, it is possible to exhibit excellent charging stability (environmental stability) in which the charge amount difference between the HH condition and the LL condition is controlled to be small.

Therefore, the powder of the present invention can be suitably used as an additive (especially an external additive for toner) for toners, powder coatings, and the like. Therefore, the present invention also includes an electrophotographic toner composition or a powder coating composition containing the powder of the present invention and the binder resin particles (hereinafter both are collectively referred to as the "composition of the present invention"). .

The composition of the present invention contains the surface-modified inorganic oxide powder of the present invention described above, and its composition, its production method, etc. are not particularly limited, and known compositions and methods can be employed.

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 effect of improving properties can be obtained, but it is usually preferably 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 addition of the powder of the present invention may not sufficiently improve the fluidity or stabilize the environmental stability of electrification. be. On the other hand, if the content of the powder of the present invention exceeds 5.0% by weight, many of the powders of the present invention act alone, and there is a possibility that problems may occur, for example, in image quality and cleanability.

The composition of the present invention may contain pigments, charge control agents (charge control agents), waxes, etc., if necessary, in addition to the binding resin particles. These ingredients can also be similar to known or commercially available toner compositions. Further, the type of toner is preferably negatively charged toner, but is not particularly limited in other respects. Therefore, for example, either magnetic or non-magnetic one-component toner or two-component toner may be used. Furthermore, either monochrome or color may be used.

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, and may be used in combination with other metal oxide fine powder depending on the purpose. . For example, the hydrophobic inorganic oxide powder of the present invention, other surface-modified dry-type silica fine powder, surface-modified dry-type titanium oxide fine powder, surface-modified wet-type titanium oxide fine powder, etc. are required. They can be used in combination depending on the situation.

EXAMPLES Examples and comparative examples are shown below to describe the features of the present invention more specifically. However, the scope of the present invention is not limited to the examples.

[Example 1]
Vapor-phase silica (trade name: AEROSIL® 200, manufactured by Nippon Aerosil) having a BET specific surface area of 200 m ² /g is placed in a reaction tank, and a hydrophobicity-imparting agent is added to 100 g of powder while stirring in a nitrogen atmosphere. As, 15.0 g of hexamethyldisilazane (trade name Dynasylan (registered trademark) HMDS, manufactured by Evonik Industries AG) was sprayed, heated and stirred at 150 ° C. for 60 minutes, cooled, and a hydrophobized inorganic material surface-treated with a hydrophobicity imparting agent. An oxide powder 1 was obtained.
After that, in a nitrogen atmosphere, a solution obtained by dissolving 10.0 g of glycerol laurate in 10 g of hexane as a nonionic surfactant was sprayed on the hydrophobized inorganic oxide powder 1, heated to 100 ° C. and then cooled. A modified inorganic oxide powder 1 was obtained.

[Example 2]
Hydrophobized inorganic oxide powder 1 was treated in the same manner as in Example 1 except that 10.0 g of pentaethylene glycol monodecyl ether was used as a nonionic surfactant, and surface-modified inorganic oxide powder 2 was obtained. got

[Example 3]
10.0 g of bis-2-hydroxyethylisotridecyloxypropylamine (trade name Tomamine (registered trademark) E-17-2, manufactured by Evonik Industries AG) as a nonionic surfactant per 1 of the hydrophobized inorganic oxide powder A surface-modified inorganic oxide powder 3 was obtained by performing the same treatment as in Example 1 except that .

[Example 4]
10.0 g of bis-2-hydroxyethylisodecyloxypropylamine (trade name Tomamine (registered trademark) E-14-2, manufactured by Evonik Industries AG) as a nonionic surfactant per 1 of the hydrophobized inorganic oxide powder A surface-modified inorganic oxide powder 4 was obtained by performing the same treatment as in Example 1 except that .

[Example 5]
Poly-(5)-oxyethylene isodecyloxypropylamine (trade name Tomamine (registered trademark) E-14-5, manufactured by Evonik Industries AG) as a nonionic surfactant is added to 1 of the hydrophobized inorganic oxide powder 10. A surface-modified inorganic oxide powder 5 was obtained by performing the same treatment as in Example 1 except that 0.0 g was used.

[Example 6]
For hydrophobized inorganic oxide powder 1, polybis-(2-hydroxyethyl)oxyethylene cocoalkyloxypropylamine (trade name Tomamine (registered trademark) EC-15, manufactured by Evonik Industries AG) is added as a nonionic surfactant. ) A surface-modified inorganic oxide powder 6 was obtained by performing the same treatment as in Example 1, except that 10.0 g was used.

[Example 7]
AEROSIL (registered trademark) R974 (manufactured by Nippon Aerosil Co., Ltd.) is used as a commercially available hydrophobized inorganic oxide powder, and bis-2-hydroxyethylisotridecyloxypropylamine (trade name: Tomamine (registered trademark) E-17-2, manufactured by Evonik Industries AG) was sprayed, heated to 100° C. and then cooled to obtain surface-modified inorganic oxide powder 7 .

[Example 8]
Except for using 15.0 g of isobutyltrimethoxysilane (trade name: Dynasylan (registered trademark) IBTMO, manufactured by Evonik Industries AG) as a hydrophobicity imparting agent, the same treatment as in Example 3 was performed to obtain a surface-modified inorganic oxide powder. got 8.

[Example 9]
The same treatment as in Example 3 was performed except that 20.0 g of dimethyl silicone oil (trade name KF-96-100CS, manufactured by Shin-Etsu Chemical Co., Ltd.) was used as a hydrophobicity imparting agent, and the heating conditions were set to 300 ° C. for 20 minutes. , a surface-modified inorganic oxide powder 9 was obtained.

[Example 10]
Gas-phase silica (trade name: AEROSIL (registered trademark) 50, manufactured by Nippon Aerosil) having a BET specific surface area of 50 m ² /g was used, and hexamethyldisilazane (trade name: Dynasylan (registered trademark) HMDS, manufactured by Evonik Industries AG) was used. The same treatment as in Example 3 was performed except that 2.5 g of bis-2-hydroxyethylisotridecyloxypropylamine (trade name Tomamine (registered trademark) E-17-2, manufactured by Evonik Industries AG) was used. A surface-modified inorganic oxide powder 10 was obtained.

[Example 11]
Gas-phase silica (trade name: AEROSIL (registered trademark) 380, manufactured by Nippon Aerosil) having a BET specific surface area of 380 m ² /g was used, and hexamethyldisilazane (trade name: Dynasylan (registered trademark) HMDS, manufactured by Evonik Industries AG) 28 The same treatment as in Example 3 was performed except that 19.0 g of bis-2-hydroxyethylisotridecyloxypropylamine (trade name Tomamine (registered trademark) E-17-2, manufactured by Evonik Industries AG) was used. A surface-modified inorganic oxide powder 11 was obtained.

[Example 12]
Vapor-phase alumina (trade name: AEROXIDE (registered trademark) Alu C, manufactured by Evonik Industries AG) having a BET specific surface area of 100 m ² /g was used, and isobutyltrimethoxysilane (trade name: Dynasylan (registered trademark) IBTMO) was used as a hydrophobicity imparting agent. , manufactured by Evonik Industries AG) and bis-2-hydroxyethylisotridecyloxypropylamine (trade name Tomamine (registered trademark) E-17-2, manufactured by Evonik Industries AG) 5.0 g. A surface-modified inorganic oxide powder 12 was obtained by performing the same treatment as in Example 1.

[Example 13]
Vapor-phase titania (trade name: AEROXIDE (registered trademark) TiO ₂ P90, manufactured by Nippon Aerosil) having a BET specific surface area of 90 m ² /g was used, and isobutyltrimethoxysilane (trade name: Dynasylan (registered trademark) IBTMO) was used as a hydrophobicity imparting agent. , manufactured by Evonik Industries AG) and 4.5 g of bis-2-hydroxyethylisotridecyloxypropylamine (trade name Tomamine (registered trademark) E-17-2, manufactured by Evonik Industries AG). A surface-modified inorganic oxide powder 13 was obtained by performing the same treatment as in Example 1.

[Example 14]
A vapor-phase method silica-alumina composite oxide (trade name: AEROSIL (registered trademark) MOX 170, manufactured by Evonik Industries AG) having a BET specific surface area of 170 m ² /g was used, and isobutyltrimethoxysilane (trade name: Dynasylan (registered trademark)) was used as a hydrophobicity imparting agent. Trademark) IBTMO, manufactured by Evonik Industries AG) 12.8 g, and bis-2-hydroxyethylisotridecyloxypropylamine (trade name Tomamine (registered trademark) E-17-2, manufactured by Evonik Industries AG) 8.5 g. was treated in the same manner as in Example 1 to obtain a surface-modified inorganic oxide powder 14.

[Example 15]
3.0 g of bis-2-hydroxyethylisotridecyloxypropylamine (trade name Tomamine (registered trademark) E-17-2, manufactured by Evonik Industries AG) as a nonionic surfactant per 1 of the hydrophobized inorganic oxide powder A surface-modified inorganic oxide powder 15 was obtained by performing the same treatment as in Example 1 except that .

[Example 16]
5.0 g of bis-2-hydroxyethylisotridecyloxypropylamine (trade name Tomamine (registered trademark) E-17-2, manufactured by Evonik Industries AG) as a nonionic surfactant was added to 1 of the hydrophobized inorganic oxide powder. A surface-modified inorganic oxide powder 16 was obtained by performing the same treatment as in Example 1 except that the powder was used.

[Example 17]
20.0 g of bis-2-hydroxyethylisotridecyloxypropylamine (trade name Tomamine (registered trademark) E-17-2, manufactured by Evonik Industries AG) as a nonionic surfactant for 1 of the hydrophobized inorganic oxide powder A surface-modified inorganic oxide powder 17 was obtained by performing the same treatment as in Example 1 except that .

[Example 18]
30.0 g of bis-2-hydroxyethylisotridecyloxypropylamine (trade name Tomamine (registered trademark) E-17-2, manufactured by Evonik Industries AG) as a nonionic surfactant per hydrophobized inorganic oxide powder 1 A surface-modified inorganic oxide powder 18 was obtained by performing the same treatment as in Example 1 except that .

[Comparative Example 1]
Example 1 except that a solution obtained by dissolving 10.0 g of anionic surfactant sodium stearate in 10 g of ethanol was used instead of the nonionic surfactant for the hydrophobized inorganic oxide powder 1. A surface-modified inorganic oxide powder 19 was obtained by performing the same treatment.

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

[Comparative Example 3]
Vapor-phase silica (trade name: AEROSIL (registered trademark) 200, manufactured by Nippon Aerosil) having a BET specific surface area of 200 m ² /g is placed in a reaction tank, and while stirring under a nitrogen atmosphere, 100 g of this powder is subjected to nonionic interface Spray 10.0 g of activator bis-2-hydroxyethylisotridecyloxypropylamine (trade name Tomamine (registered trademark) E-17-5, manufactured by Evonik Industries AG), heat to 100 ° C. and then cool to modify the surface. An inorganic oxide powder 21 was obtained.

[Comparative Example 4]
1.0 g of bis-2-hydroxyethylisotridecyloxypropylamine (trade name Tomamine (registered trademark) E-17-2, manufactured by Evonik Industries AG) as a nonionic surfactant per 1 of the hydrophobized inorganic oxide powder A surface-modified inorganic oxide powder 22 was obtained by performing the same treatment as in Example 1 except that .

[Comparative Example 5]
40.0 g of bis-2-hydroxyethylisotridecyloxypropylamine (trade name Tomamine (registered trademark) E-17-2, manufactured by Evonik Industries AG) as a nonionic surfactant per hydrophobized inorganic oxide powder 1 A surface-modified inorganic oxide powder 23 was obtained by performing the same treatment as in Example 1 except that .

[Comparative Example 6]
The same treatment as in Example 1 was performed except that 5.0 g of hexamethyldisilazane (trade name Dynasylan (registered trademark) HMDS, manufactured by Evonik Industries AG) was used as a hydrophobicity-imparting agent. and surface-modified inorganic oxide powder 24 was obtained.

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

(1) Hydrophobicity A stirrer and 50 mL of water are placed in a 200 mL beaker, and 0.2 g of a measurement sample is added. Stir with a magnetic stirrer. The stirring speed should be set so that the powder on the surface of the liquid does not rise up. Methanol is put into a burette, the tip of the burette is put into the liquid, and the methanol is slowly mixed into the liquid while stirring. The end point is defined as the point at which no sample is observed on the liquid surface, and the amount of methanol dropped (mL) at that point is applied to the following formula to obtain the hydrophobicity (%).

Hydrophobicity (%) = [Dripping amount / (Dripping amount + 50)] x 100

In addition, in this test, when 150 mL of methanol is dropped, the beaker becomes full and no more drops can be made. The hydrophobicity in that case is expressed as “>75%” from [150/(150+50)]×100=75%. That is, the upper limit of the hydrophobicity is theoretically 100%, but since it cannot be measured when it exceeds 75% due to the method of measurement as described above, those exceeding 75% are indicated as ">75%". do.

(2) Charge amount of toner A toner composition was obtained by stirring and mixing 2.0 g of a nonionic surfactant-treated inorganic oxide and 98.0 g of a negatively chargeable toner (polyester resin, average particle size: 7 µm) in a mixer. . Then, 2.0 g of this toner composition and 48.0 g of an iron powder carrier (silicone resin-coated ferrite, average particle size of 35 μm) were placed in a glass container (75 mL volume) to prepare a mixture. Two samples of the same mixture were prepared as samples for measuring the charge amount, and one sample was allowed to stand at high temperature and high humidity (HH conditions: temperature 35° C., relative humidity 80%) for 40 hours. Another sample was allowed to stand in a low temperature and low humidity environment (LL conditions: temperature 10° C., relative humidity 10%) for 40 hours.
Each sample prepared under the above conditions was shaken with a Turbula mixer at 24 rpm for 10 minutes, 0.05 g of the mixture was sampled, and the charge amount was measured using a blow-off charge amount measuring device (MODEL 230TO) manufactured by Trek Japan Co., Ltd. I made a measurement.

As is clear from the results in Table 1, the surface-modified inorganic oxide powders of Examples satisfy all of the properties defined in the present invention and have excellent charging stability.

Claims (8)

A powder composed of composite particles containing inorganic oxide particles and a coating formed on the particle surface,
(1) the film contains a hydrophobicity imparting agent and a nonionic surfactant,
(2) the powder has a hydrophobicity of 40% or more,
A surface-modified inorganic oxide powder characterized by: The surface modification according to claim 1, wherein the value obtained by dividing the content (g) of the nonionic surfactant by the BET specific surface area (m ² /g) of the inorganic oxide particles is 0.015 to 0.150. Inorganic oxide powder. The nonionic surfactant has the following general formula (1):

[In the formula, R represents a straight-chain or branched hydrocarbon group having 8 to 18 carbon atoms which may have an unsaturated bond, x is an integer of 1 or more, and n is 2 or more. Each denote an integer, and x and n satisfy n>x. ]
3. The surface-modified inorganic oxide powder according to claim 1 or 2, which is an ethoxylated aliphatic amine having a basic skeleton derived from a tertiary amino group represented by: Hydrophobicity-imparting agent
(a) the following general formula (2):

(In the formula, R ¹ represents a hydrocarbon group having 1 to 18 carbon atoms; R ² , R ³ and R ⁴ are the same or different from each other and are a chlorine atom, a hydroxy group, or an alkoxy group having 1 to 3 carbon atoms; group.) Alkylsilanes represented by
The surface-modified inorganic oxide powder according to any one of claims 1 to 3, which is at least one selected from the group consisting of (b) silicone oil and (c) hexamethyldisilazane. The inorganic oxide particles are at least one selected from the group consisting of fumed silica particles, fumed alumina particles and fumed titania particles, and have a BET specific surface area of 30 to 400 m ² /g. The surface-modified inorganic oxide powder according to any one of claims 1 to 4. The charge amount C _LL (μC /g) divided by the charge amount C _HH (μC/g) after 40 hours at a temperature of 35° C. and a relative humidity of 80% [C _LL /C _HH ] is 1.55 or less. , The surface-modified inorganic oxide powder according to any one of claims 1 to 5. An external additive for toners or powder coatings containing the surface-modified inorganic oxide powder according to any one of claims 1 to 6. An electrophotographic toner composition or powder coating composition comprising the external additive according to claim 7 and binder resin particles.