JP3166014B2 - Hydrophobic titanium oxide and developer for electrophotography - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a hydrophobic titanium oxide powder and an electrophotographic developer containing the same. More specifically, the present invention relates to a hydrophobic titanium oxide powder, which has a low triboelectric charging property with respect to iron and can be provided at low cost, and an electrophotographic developer containing the same.

[0002]

2. Description of the Related Art Toners for electrophotographic developers
The use of additives (fluidity improvers) for the purpose of increasing the fluidity and preventing aggregation is widely performed. Heretofore, as a fluidity improver, a metal oxide fine powder having a hydrophobic surface, particularly a silica fine powder, has been generally used. However, from the viewpoint of triboelectric charging with iron generally used as a carrier, these additives themselves have high charging properties. Therefore, when these are used in excess, the effect on the chargeability of the toner itself becomes remarkable, and phenomena such as an increase in the dependence of the charge amount on humidity and a decrease in stability over time occur. Therefore, the amount of these additives used is generally 1 part by weight or less, and the effect of improving the fluidity obtained is not always sufficient.

It is expected that such a problem can be solved by using an additive having a small triboelectric charge amount with iron as a fluidity improver. Since the titanium oxide powder has a triboelectric charge amount with respect to iron in a range of about −50 μC / g to about +50 μC / g, and its value is stable, electrophotography,
In electrostatic recording and the like, when it is used as an agent for improving the fluidity of a toner, it satisfies the condition that the static charge of the toner is not largely changed.

[0004] On the other hand, untreated titanium oxide has high hydrophilicity, so that if it is used as it is as an additive in a toner, problems arise in dispersibility and durability. Therefore, in order to use titanium oxide as an additive for a toner, it is necessary to make the surface hydrophobic by some method.

In general, as a method for making a hydrophilic surface of a metal oxide or the like hydrophobic, a method of chemically or physically inactivating a hydroxyl group on the surface with a silane coupling agent or polysiloxane is known. . But,
Some problems arise when the titanium oxide powder is hydrophobized by these conventional methods.

For example, when a titanium oxide powder is treated with a silane compound such as an alkylalkoxysilane, an alkylhalogenated silane, or an alkyldisilazane, the triboelectrification after the treatment hardly changes from that before the treatment, but the surface becomes hydrophobic. The degree of hydrophobization is small, and the degree of hydrophobicity achieved by increasing the throughput is limited to around 40. Further, it is difficult to obtain a constant degree of hydrophobicity. Therefore, when titanium oxide treated with such a silane compound is added to a hydrophobic substance, a problem arises in terms of its dispersibility.

Further, polysiloxane such as dimethylpolysiloxane itself has negative chargeability, and when it is subjected to a hydrophobic treatment until the titanium oxide to be treated has a degree of hydrophobicity of 50 or more by using the same, iron Also exhibits a large negative charge (in absolute value), and the inherent characteristics of titanium oxide are not used.

On the other hand, a fluorine-substituted silane compound is known as a surface treating agent which imparts high hydrophobicity, and a surface treatment of a metal oxide by using the same has already been reported (Japanese Patent Application Laid-Open No. Sho.
0-93455). When titanium oxide is actually treated with a fluorine-substituted silane compound, it is possible to simultaneously achieve a high degree of hydrophobicity and a low triboelectric charge. But,
When using a large amount of titanium oxide powder having a large specific surface area, it is necessary to use a large amount of an expensive fluorine-substituted silane compound in order to impart sufficient hydrophobicity to such titanium oxide powder. Not practical from above.

For this reason, conventional titanium oxide powders are used without simultaneously satisfying the two conditions of the degree of hydrophobicity and the triboelectric charge amount against iron, and these powders are actually used in electrophotographic developers. When used for the purpose of improving the fluidity, there arises a problem that the chargeability is easily affected by the environment and the change with time is large.

[0010]

SUMMARY OF THE INVENTION An object of the present invention is to provide a titanium oxide powder having a sufficient degree of hydrophobicity and a low triboelectric charge at a practical price in consideration of the problems of the prior art. Another object of the present invention is to provide a developer for electrophotography, which contains the titanium oxide powder, has stable charging properties, and is excellent in fluidity.

[0011]

[Knowledge leading to solution of the problem] The inventors of the present invention have conducted intensive studies to achieve the above object. As a result, titanium oxide surface-treated with a combination of a fluorine-substituted silane compound and an organopolysiloxane is a fluorine-substituted silane compound or an organopolysiloxane. It has been found that the same degree of hydrophobicity can be obtained with a smaller amount of treatment as compared to the case where siloxane is treated alone. As a result, the amount of the fluorine-substituted silane compound used can be suppressed to a practically acceptable range, and the triboelectric charge amount and the degree of hydrophobicity with respect to iron can be set to practically preferable values. When this surface-treated powder is actually added to the toner, the change in the charge amount of the toner itself is extremely small, so that it can be used in a relatively large amount, and it has been confirmed that sufficient fluidity can be obtained as a result. Thus, the object of the present invention has been achieved.

[0012]

According to the present invention, the triboelectric charge of iron treated with a fluorine-substituted silane compound and an organopolysiloxane is in the range of -50 .mu.C / g to +50 .mu.C / g and measured by a methanol titration test. An electrophotographic developer is provided, wherein titanium oxide (TiO ₂ ) powder having a degree of hydrophobicity of 50 or more is added to a toner.

[0013] The fluorine-substituted silane compound used in the present _{^{invention, R 1 - (X) p}} - (CH 2 CH 2 O) q (CH 2) m SiR 2 3-n R 3 n [ respectively wherein, R ¹ is a fluorine-substituted alkyl group having 1 to 10 carbon atoms; X is SO ₂ NR ⁴ (where R ⁴ is hydrogen or an alkyl group having 1 to 5 carbon atoms); divalent selected from CONR ⁴ , CO ₂ or CH ₂ O R ² is an alkyl group having 1 to 5 carbon atoms; R ³ is Cl, Br or an alkoxy group having 1 to 5 carbon atoms; p is an integer of 0 or 1;
M is an integer of 1 to 5 (where p and q are simultaneously 0, m is an integer of 2 to 5); n is an integer of 1 to 3. ], Specifically, the following compounds are exemplified.

C ₆ F ₁₃ CH ₂ CH ₂ Si (OCH ₃ ) ₃ CF ₃ CH ₂ CH ₂ OCH ₂ CH ₂ CH ₂ Si (OCH ₃ ) ₃ C ₄ F ₉ CH ₂ CH ₂ OCH ₂ CH ₂ SiCH ₃ ( _{OC 2 H 5) 2 C 6} F 13 CH 2 CH 2 O (CH 2 CH 2 O) 2 (CH 2) 3 Si (O
_{CH 3) 3 C 7 F 15} CH 2 O (CH 2) 3 Si (OC 2 H 5) 3 C 7 F 15 CONEt (CH 2) 3 Si (OCH 3) 3 C 8 F 17 SO 2 NEt (CH 2 ) ₃ Si (OCH ₃ ) ₃ C ₈ F ₁₇ SO ₂ NPr (CH ₂ ) ₃ Si (OCH ₃ ) ₃ C ₈ F ₁₇ SO ₂ NEt (CH ₂ ) ₃ SiMeCl ₂

The organopolysiloxane used in the present invention is not particularly limited as long as it is sufficient to make the titanium oxide powder to be treated hydrophobic, but from the viewpoint of product price and hydrophobicity, the following general formula (2) Are preferred. Formula (2):-(SiMe ₂ O) _a (SiR ⁵ R ⁶ O) _b-wherein R ⁵ and R ⁶ are an alkyl group, a phenyl group, a phenyl-substituted alkyl group, an alkoxy group, and a hydrogen group. represent identical or different substituents more selected (where, R ^5, R ⁶ are, a is 0 applies not be a hydrogen group simultaneously). A represents 0 or a positive integer, and b represents a positive integer. The substituents R ⁵ and R ⁶ in the general formula (2) may be any as long as they are sufficient to make the powder to be treated hydrophobic. Examples of the combination of the organic substitution machine include a methyl group and a hydrogen group, a phenyl group and a phenyl group, a methyl group and a methylstyryl group, a methyl group and a long-chain alkyl group, and a methyl group and a long-chain alkoxy group.

The degree of polymerization of these organopolysiloxanes is not particularly limited, except that they have fluidity such that they adhere uniformly to the surface of the titanium oxide powder, but from the viewpoint of the processing operation, those having a viscosity of about 10 cs to 1000 cs. It is preferable to use The particle diameter of the titanium oxide powder is particularly preferably from 40 m ² / g to 200 m ² / g.

The amount of triboelectric charging of the titanium oxide treated in the present invention with respect to iron is in the range of −50 μC / g to +50 μC / g. If the triboelectric charge (absolute value) exceeds 50 μC / g, the chargeability of the toner will be greatly affected, and its temperature dependence and aging will be particularly large. The method of measuring the triboelectric charge amount is specified in literatures such as (Coloring Material, 55 [9] 630-636.1982).

The degree of hydrophobicity of the titanium oxide powder used in the present invention must be 50 or more as measured by a methanol titration test. When the degree of hydrophobicity is less than 50, the compatibility with the toner is insufficient, and the dispersibility is deteriorated. The methanol titration test is a method for experimentally determining the degree of hydrophobicity of a treated titanium oxide powder, and is defined as follows in this specification. Add 0.2 g of the treated titanium oxide powder to 50 ml of water in a beaker. While stirring this mixture with a magnetic stirrer, methanol is added dropwise.
The end point is when the entire titanium oxide fine powder is wet in the solution, and the degree of hydrophobicity is the volume of methanol used (Qml)
Is defined by the following equation: Hydrophobicity = Q / (50 + Q) × 100

As a method for treating the titanium oxide powder used in the present invention, a conventionally known method is applied. That is, while mechanically sufficiently stirring the titanium oxide powder to be treated, the fluorine-substituted silane compound and then or simultaneously with the organopolysiloxane are added dropwise or sprayed thereto. At this time, it is desirable to add diethylamine or the like as a catalyst for increasing the reactivity of the fluorine-substituted silane compound, or to blow ammonia gas. Further, depending on the viscosity of the fluorine-substituted silane compound and the organopolysiloxane to be used, it is also possible to use a solvent such as ethanol, acetone or hexane as a diluent. After adding the treatment agent,
The reaction is completed by heating at a temperature in the range of 100 ° C. to 300 ° C. in a nitrogen atmosphere, and the solvent is removed.

The triboelectric charge of the hydrophobic titanium oxide, ie, iron, which is the object of the present invention, is from -50 μC / g to +50.
a fluorine-substituted silane compound suitable for giving a fine powder of titanium oxide (TiO ₂ ) having a hydrophobicity of at least 50 μC / g and measured by a methanol titration test; and The total amount of the organopolysiloxane used is determined according to the specific surface area of the titanium oxide powder to be treated. For example, in the case of a titanium oxide powder having a specific surface area of 50 m ² / g, the total usage of the fluorine-substituted silane compound and the organopolysiloxane is from 2.5% by weight to 12.0% by weight based on the weight of the titanium oxide to be treated. Preferably 2.5
The above-mentioned degree of hydrophobicity is achieved by being in the range of from 6.0% by weight to 6.0% by weight. In other cases, the object is achieved by increasing or decreasing the total amount of the fluorine-substituted silane compound and the organopolysiloxane in proportion to the specific surface area according to the above relationship. With respect to the individual use amount, the use amount of the fluorine-substituted silane compound ranges from 1.0% by weight to 10.0% by weight, preferably from 1.0% by weight to 5.0% by weight based on the titanium oxide to be treated. And the amount of organopolysiloxane used should be 1.0% to 5.0% by weight, preferably 1.0% to 2.5% by weight. In this case, the quantitative ratio of the fluorine-substituted silane compound to the organopolysiloxane is 0.2
To 10

The developer of the present invention is obtained by adding the titanium oxide fine particles treated with the above-mentioned fluorine-substituted silane compound and the above-mentioned organopolysiloxane to a toner by an ordinary method.

In the present invention, it is essentially important to use a fluorine-substituted silane compound in combination with an organopolysiloxane (see Comparative Examples described later). Even if these are used individually to treat titanium oxide particles, the desired degree of hydrophobicity cannot be achieved. The cause of the synergistic effect of the fluorine-substituted silane compound and the organopolysiloxane on the degree of hydrophobicity is explained by the presence of the organopolysiloxane near the titanium oxide surface to which the fluorine-substituted silane compound is bonded. It is supposed that the orientation of the compound increases, but it is not always clear.

[0023]

DETAILED DESCRIPTION OF THE INVENTION Hereinafter, the present invention will be specifically described with reference to examples. These are for explanation, and the present invention is not limited by these.

[0024]

Example 1 Heat-dried titanium oxide (specific surface area 50
20 g of m ² / g) was charged into a stainless steel container, and a treating agent 1 having the following composition was sprayed at room temperature while stirring under a nitrogen atmosphere. Treatment agent 1: Fluorine-substituted silane compound C ₈ F ₁₇ SO ₂ NPr (CH ₂ ) ₃ Si (OMe) ₃ 0.50 g Methyl hydrogen polysiloxane 0.25 g (KF-99 (20 cs) manufactured by Shin-Etsu Chemical Co., Ltd.) diethylamine 5.0 ml of a few drops n-hexane After spraying, the mixture was further stirred at room temperature for 30 minutes, and then heated to 250 ° C. over a period of 40 minutes under a nitrogen stream, and kept at this temperature for 30 minutes. Allowed to cool to room temperature. The degree of hydrophobicity and the triboelectric charge on iron of the obtained powder in a methanol titration test were 70 and −18 μC / g, respectively.

[0025]

Example 2 In this example, the treatment of titanium oxide was carried out by sequentially using a fluorine-substituted silane compound and polysiloxane. Heat dried titanium oxide (specific surface area 50
20 g of m ² / g) were charged in a stainless steel container, and while stirring under a nitrogen atmosphere, a treating agent 2a having the following composition was sprayed at room temperature, and then a treating agent 2b was sprayed at the same room temperature. Treatment agent 2a: Fluorine-substituted silane compound C ₈ F ₁₇ SO ₂ NPr (CH ₂ ) ₃ Si (OMe) ₃ 0.50 g Diethylamine several drops n-hexane 3.0 ml Treatment agent 2b: methyl hydrogen polysiloxane 0.25 g ( Shin-Etsu Chemical Co., Ltd. KF-99 (20 cs)) 2.0 ml n-hexane After spraying was completed, the mixture was further stirred at room temperature for 30 minutes, and then externally heated under a nitrogen stream. The temperature was raised to 250 ° C. over 40 minutes, maintained at this temperature for 30 minutes, and then allowed to cool to room temperature. The characteristics of the obtained powder were measured. The degree of hydrophobicity and the triboelectric charge amount with respect to iron in the methanol titration test were 65 and −2 μC / g, respectively.

[0026]

Example 3 Heat-dried titanium oxide (specific surface area 50
m ² / g) was charged into a stainless steel container, and a treating agent 3 having the following composition was sprayed at room temperature while stirring under a nitrogen atmosphere. Treatment agent 3: a fluorine-substituted silane compound _{C 6 F 13 CH 2 CH 2} Si (OCH 3) 3 0.50g diphenyl polysiloxane 0.50 g (Shin-Etsu Chemical Co., Ltd. KF-50 (100cs)) diethylamine few drops n- 5.0 ml of hexane After the completion of the spraying, the mixture was further stirred at room temperature for 30 minutes, heated from the outside under a nitrogen stream, heated to 230 ° C. over 40 minutes, kept at this temperature for 30 minutes, and allowed to cool to room temperature did.
The degree of hydrophobicity and the triboelectric charge against iron of the obtained powder by a methanol titration test were 71 and −24 μC / g, respectively.
Met.

[0027]

Example 4 Heat-dried titanium oxide (specific surface area: 10
(0 m ² / g) was charged into a stainless steel container, and a treating agent 4 having the following composition was sprayed at room temperature while stirring under a nitrogen atmosphere. Treatment agent 4: fluorine-substituted silane compound _{C 7 F 15 CH 2 O (} CH 2) 3 Si (OEt) 3 1.00g of methyl alkyl polysiloxane ^* 0.25 g (Shin-Etsu Chemical Co., Ltd. KF-413 (100cs)) diethylamine a few drops of acetone 5.0 ml * R ⁵ is a methyl group, after R ⁶ is a long chain alkyl group completion of spraying, after further stirring for 30 minutes at room temperature, was subjected to external heating in a nitrogen stream. The temperature was raised to 200 ° C. over 40 minutes, maintained at this temperature for 30 minutes, and allowed to cool to room temperature. The characteristics of the obtained powder were measured. The degree of hydrophobicity and the triboelectric charge against iron in the methanol titration test were 78 and −21 μC / g, respectively.

[0028]

Example 5 Heat-dried titanium oxide (specific surface area 50
20 g of m ² / g) were charged into a stainless steel container, and a treating agent 5 having the following composition was sprayed at room temperature while stirring under a nitrogen atmosphere. Treatment agent 5: fluorine-substituted silane compound _{2.00g C 4 F 9 CH 2 CH} 2 OCH 2 CH 2 CH 2 SiMe (OEt) 2 -methyl-alkoxy polysiloxane 0.25 g (manufactured by Shin KF-851 (80cs)) A few drops of diethylamine 5.0 ml of n-hexane After the completion of spraying, the mixture was further stirred at room temperature for 30 minutes, and then externally heated under a nitrogen stream. The temperature was raised to 250 ° C. over 40 minutes, maintained at this temperature for 30 minutes, and then allowed to cool to room temperature. The characteristics of the obtained powder were measured. The degree of hydrophobicity and the triboelectric charge against iron in the methanol titration test were 61 and −22 μC / g, respectively. In this example, it can be seen that even if 1 part by weight or more of the titanium oxide-treated powder developer of the present invention is used, the chargeability of the toner is not significantly affected.

[0029]

Example 6 Heat-dried titanium oxide (specific surface area 50
20 g of m ² / g) was charged into a stainless steel container, and a treating agent 6 having the following composition was sprayed at room temperature while stirring under a nitrogen atmosphere. Treatment agent 6: fluorine-substituted silane compound _{C 8 F 17 SO 2 NEt (} CH 2) 3 SiMeCl 2 0.50g of methylhydrogenpolysiloxane 0.25 g (manufactured by Shin KF-99 (20cs)) few drops of diethylamine n After the spraying was completed, the mixture was further stirred at room temperature for 30 minutes, and then ammonia gas was blown in for 30 minutes. Thereafter, external heating was performed under a nitrogen stream. Raise the temperature to 250 ° C over 40 minutes,
After maintaining at this temperature for 30 minutes, it was allowed to cool to room temperature. The characteristics of the obtained powder were measured. The degree of hydrophobicity and the triboelectric charge amount against iron by the methanol titration test were 65, respectively.
+2 μC / g.

[0030]

Example 7 Heat-dried titanium oxide (specific surface area 50
20 g of m ² / g) was charged into a stainless steel container, and a treating agent 7 having the following composition was sprayed at room temperature while stirring under a nitrogen atmosphere. Treating agent 7: fluorine-substituted silane compound _{C 8 F 17 SO 2 NPr (} CH 2) 3 Si (OMe) 3 1.00g methyl styryl polysiloxane 0.25 g (manufactured by Shin KF-410 (100cs)) Number of diethylamine 5.0 ml of acetone After the spraying was completed, the mixture was further stirred at room temperature for 30 minutes, and then externally heated under a nitrogen stream. The temperature was raised to 250 ° C. over 40 minutes, maintained at this temperature for 30 minutes, and then allowed to cool to room temperature. The characteristics of the obtained powder were measured. The degree of hydrophobicity and the triboelectric charge against iron in the methanol titration test were 62 and -25 μC / g, respectively.

[0031]

Comparative Example 1 In this example, a titanium oxide powder was treated with only a fluorine-substituted silane compound without using an organopolysiloxane. 20 g of heat-dried titanium oxide (specific surface area: 50 m ² / g) was charged into a stainless steel container, and a treatment agent having the following composition was sprayed at room temperature while stirring under a nitrogen atmosphere. Treatment agent: Fluorine-substituted silane compound C ₈ F ₁₇ SO ₂ NPr (CH ₂ ) ₃ Si (OMe) ₃ 0.50 g A few drops of diethylamine 5.0 ml of n-hexane After spraying is completed, the mixture is further stirred at room temperature for 30 minutes and then nitrogen. External heating was performed under air flow. The temperature was raised to 250 ° C. over 40 minutes, maintained at this temperature for 30 minutes, and then allowed to cool to room temperature. The characteristics of the obtained powder were measured. The degree of hydrophobicity and the amount of triboelectricity against iron in the methanol titration test were 24 and -4 μC / g, respectively.

[0032]

Comparative Example 2 In this example, a titanium oxide powder was treated with only an organopolysiloxane without using a fluorine-substituted silane compound. 20 g of heat-dried titanium oxide (specific surface area: 50 m ² / g) was charged into a stainless steel container, and a treatment agent having the following composition was sprayed at room temperature while stirring under a nitrogen atmosphere. Treatment agent: 0.50 g of methyl hydrogen polysiloxane (KF-99 (200 cs) manufactured by Shin-Etsu Chemical Co., Ltd.) 5.0 ml of n-hexane After completion of spraying, the mixture was further stirred at room temperature for 30 minutes, and then externally heated under a nitrogen stream. Done. The temperature was raised to 250 ° C. over 40 minutes, maintained at this temperature for 30 minutes, and then allowed to cool to room temperature. The characteristics of the obtained powder were measured. The degree of hydrophobicity and the amount of triboelectricity with respect to iron in the methanol titration test were 10, and −42 μC / g, respectively. The hydrophobicity of the titanium oxide powder obtained by the same operation except that the amount of polysiloxane in the treating agent was changed to 1.0 g and 3.0 g by a methanol titration method, and the triboelectric charge amount to iron were as follows:
41, −75 μC / g and 68, −208 μC / g, respectively
Met.

[0033]

Comparative Example In this example, in order to more clearly show the effect of the combined use of the fluorine-substituted silane compound and the organopolysiloxane, the amount (total amount) of the treating agent was set to 5.0% by weight. B: only organopolysiloxane (5.0% by weight); and C: fluorine-substituted silane compound (2.5% by weight) + organopolysiloxane (2.5% by weight). The titanium oxide powder was treated in the same manner as in the above examples (Examples and Comparative Examples). The results are as shown in the table below. This example shows that the effect of the present invention is not an average or total effect of the fluorine-substituted silane compound and the organopolysiloxane, but a synergistic effect of the combination of the two.

[0034]

Example 8 Carbon 18 in styrene-acrylic resin
% Was dispersed and pulverized, and 1 g of the titanium oxide particles prepared in Examples 1 to 7 was mixed with 100 g of a resin powder (resin powder-1) obtained by classifying the powder to 10 μ to 20 μ to prepare a toner. . Further, 30 g of this toner is added to iron oxide powder 1
000 g and a developer. The developer prepared without adding the titanium oxide fine particles has a triboelectric charge of −15.
μC / g, but the triboelectric charge of this developer was-
It was 15 μC / g. Put this developer in a commercial copier,
As a result of the life test, no fog occurred on the image even with about 26,000 or more copies. Furthermore, a good image was displayed even in an environment of high temperature and high humidity (28 ° C., 85% RH), and no change in the charge amount was observed.

[0035]

Comparative Example 3 In the same manner as in Example 8, except that the titanium oxide powder added in Example 8 was changed to the titanium oxide powder prepared in Comparative Example 2 (having a hydrophobicity of 10, and a triboelectric charge of -42 μC / g). A developer was prepared. The charge amount of this developer is -1.
It was 5 μC / g. When this developer was put into a commercially available copying machine and a life test was performed, fogging occurred on the image on about 13,000 sheets, and the charge amount was -13 μC in an environment of high temperature and high humidity (28 ° C., 85% RH). / g.

[0036]

Example 9 Carbon 18 in styrene-acrylic resin
%, Nigrosine 5% dispersed, pulverized, and then mixed with 100 g of a resin powder (resin powder-2) obtained by classifying into 10 μ to 20 μ, by mixing 1 g of the titanium oxide fine particles prepared in Examples 1 to 7 above. A toner was prepared. Further, 30 g of this toner was added to 1000 g of iron oxide powder to prepare a developer. While the triboelectric charge of the developer prepared without adding the titanium oxide fine particles was +18 μC / g, the triboelectric charge of this developer was also +18 μC / g. The developer was put into a commercial copying machine and subjected to a life test.
No fog occurred in the image even with more than 000 copies. Furthermore, good performance was exhibited even in an environment of high temperature and high humidity (28 ° C., 85% RH), and no change in the charge amount was observed.

[0037]

Comparative Example 4 The procedure of Example 9 was repeated, except that the titanium oxide powder added in Example 9 was changed to the titanium oxide powder prepared in Comparative Example 2 (having a hydrophobicity of 10, and a triboelectric charge of -42 μC / g). A developer was prepared. The charge amount of this developer is +1
It was 7 μC / g. When this developer was put into a commercially available copying machine and a life test was carried out, fogging occurred on the image on about 9,000 sheets, and the charge amount was +13 μC / C under an environment of high temperature and high humidity (28 ° C., 85% RH). g.

[0038]

As is apparent from the above description, the treatment of titanium oxide with the combined use of the fluorine-substituted silane compound and the organopolysiloxane requires a significantly smaller amount of treatment than the treatment of the fluorine-substituted silane compound alone, and is practically possible. The required hydrophobic titanium oxide powder can be obtained. That is, since the titanium oxide powder of the present invention has a hydrophobicity of 50 or more, it is excellent in dispersibility in a toner, and has a triboelectric charge amount to iron of −50 μC / g to +50 μC.
/ g, the effect on the chargeability of the toner itself is small, and the toner has a sufficient fluidity improving effect. Further, the developer of the present invention using the additive provided at this practical price has not only improved fluidity but also excellent temporal stability with respect to the charge amount and the environment.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) C01G 23/04 C07F 7/18 G03G 9/08 368

Claims (4)

(57) [Claims] 1. A general formula ^{(1): R 1 - (} X) p - (CH 2 CH 2 O) q (CH 2) m SiR 2 3-n R 3 n [ respectively wherein, R ¹ is the number of carbon atoms X is SO ₂ NR ⁴ (where R ⁴ is hydrogen or an alkyl group having 1 to 5 carbon atoms); a divalent substituent selected from CONR ⁴ , CO ₂ or CH ₂ O; R ² is an alkyl group having 1 to 5 carbon atoms; R ³ is Cl, Br or an alkoxy group having 1 to 5 carbon atoms; p is an integer of 0 or 1;
M is an integer of 1 to 5 (where p and q are simultaneously 0, m is an integer of 2 to 5); n is an integer of 1 to 3. And the organopolysiloxane having a triboelectric charge on iron in the range of −50 μC / g to +50 μC / g, and a degree of hydrophobicity of 5 measured by a methanol titration test.
0 or more titanium oxide (TiO 2)
₂ ) Powder. 2. An organopolysiloxane represented by the general formula (2):-(SiMe ₂ O) _a (SiR ⁵ R ⁶ O) _b-wherein R ⁵ and R ⁶ are an alkyl group, a phenyl group or a phenyl substituent. Represents the same or different substituents selected from an alkyl group, an alkoxy group and a hydrogen group (provided that R ⁵ and R ⁶ must not be hydrogen groups at the same time when a is 0). A represents 0 or a positive integer, and b represents a positive integer.] The titanium oxide (TiO ₂ ) powder according to claim 1, wherein 3. A compound of the general formula (1): R ^1- (X) _p- (CH ₂ CH ₂ O) _q (CH ₂ ) _m SiR ² _3-n R ³ _{n wherein} R ¹ is carbon number X is SO ₂ NR ⁴ (where R ⁴ is hydrogen or an alkyl group having 1 to 5 carbon atoms); a divalent substituent selected from CONR ⁴ , CO ₂ or CH ₂ O; R ² is an alkyl group having 1 to 5 carbon atoms; R ³ is Cl, Br or an alkoxy group having 1 to 5 carbon atoms; p is an integer of 0 or 1;
M is an integer of 1 to 5 (where p and q are simultaneously 0, m is an integer of 2 to 5); n is an integer of 1 to 3. And a triboelectric charge against iron in the range of −50 μC / g to +50 μC / g, and a degree of hydrophobicity of 5 measured by a methanol titration test.
An electrophotographic developer, wherein titanium oxide (TiO ₂ ) powder having a value of 0 or more is added to a toner. 4. An organopolysiloxane represented by the general formula (2):-(SiMe ₂ O) _a (SiR ⁵ R ⁶ O) _b-wherein R ⁵ and R ⁶ are an alkyl group, a phenyl group or a phenyl substituent. Represents the same or different substituents selected from an alkyl group, an alkoxy group and a hydrogen group (provided that R ⁵ and R ⁶ must not be hydrogen groups at the same time when a is 0). A represents 0 or a positive integer, and b represents a positive integer].