JP2636304B2 - Image forming method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention develops an electrostatic latent image formed on the surface of a latent image carrier in, for example, electrophotography, electrostatic recording, electrostatic printing, and the like. The present invention relates to an image forming method having a step of performing the following.

[Technological background]

At present, as a method of forming a visible image from certain image information, a method via an electrostatic latent image such as an electrophotographic method, an electrostatic recording method, an electrostatic printing method, and the like is widely used.

For example, in electrophotography, after a uniform electrostatic charge is applied to a latent image carrier having a photosensitive layer made of a photoconductive material, the surface of the latent image carrier is exposed to an image by image exposure. A formed electrostatic latent image is formed, and this electrostatic latent image is developed by a developer to form a toner image. This toner image is transferred to a recording material such as paper, and then fixed by heating or pressing to form a copied image. On the other hand, the latent image carrier after the transfer step is neutralized, and then the toner remaining on the latent image carrier without being transferred is cleaned and used for the formation of the next copy image.

Therefore, in order to stably form a high-quality copy image without fogging many times, it is required that the frictional charging property of the toner is stably maintained.

[Conventional technology]

 From such a request, the following technology has been conventionally proposed.

An electrostatic image developer composed of toner particles containing a polyester having a chloroform insoluble content of 5 to 25% by weight as a binder resin, inorganic fine particles of negatively chargeable silica fine particles, and a fluororesin-coated carrier. (Japanese Patent Laid-Open No. 60-17
No. 6052).

Toner particles containing a polyester having a chloroform-insoluble content of 5 to 25% by weight as a binder resin, positively chargeable inorganic fine particles such as alumina fine particles, titanium oxide fine particles, nitrogen-containing silica fine particles, and a fluororesin coating An electrostatic image developer comprising a carrier (Japanese Patent Laid-Open No. 62-229158)
Reference).

[Problems to be solved by the invention]

However, the above technique has the following problems.

In the above technology, since the negatively chargeable silica fine particles are used, even if a strongly negatively chargeable fluororesin-coated carrier is used, the rise of the triboelectric chargeability of the toner particles is poor, and when an image is formed many times, There is a problem in that toner is scattered in the developing section, which contaminates the charging electrode, the transfer electrode, the separation electrode, and the like, resulting in an image defect. When the amount of toner scattering increases, the back surface of the front end of the transfer material, in which the back surface of the front end of the transfer material is stained with toner, occurs.

In addition, since the polyester used as the binder resin is very brittle, when subjected to a mechanical external force such as stirring in a developing device, the toner particles are broken and fine powder is easily generated, and the fine powder adheres to the surface of the carrier particles. As a result, there is a problem that the frictional charging property between the toner and the carrier becomes unstable.

In the above technology, since positively chargeable inorganic fine particles are used, the rise of the triboelectric chargeability of the toner particles is improved, and thus the toner scattering is reduced. As a result, the toner particles are destroyed by mechanical external force such as agitation and fine powder is easily generated, and the fine powder adheres to the surface of the carrier particles, and the triboelectric charging property between the toner and the carrier becomes unstable. There is a problem that image defects such as toner scattering and fog occur due to a decrease in the triboelectric charge amount of the particles and deterioration of the rise of the triboelectric charge.

The present invention has been made in view of the above circumstances, and an object of the present invention is to use an electrostatic image developer in which toner particles are hardly broken and a stable positive triboelectric charging property is exhibited over a long period of time. An object of the present invention is to provide an image forming method.

[Means for solving the problem]

In order to achieve the above object, the present invention provides a method for forming a negative electrostatic latent image formed on an organic photoreceptor by using an electrostatic image developer including a toner and inorganic fine particles treated with a nitrogen-containing substance. An image forming method including a developing step, wherein the toner has a ratio OHV / AV of a hydroxyl value (OHV) to an acid value (AV) obtained by subjecting a monomer composition containing the following components to condensation polymerization reaction. It is characterized by containing a polyester having a value of 1.0 to 5.0 and a glass transition point of 50 to 70 ° C as a binder resin.

Ingredient: 1 to 30 mol% of the total of the monomer composition, a polyvalent monomer having a valence of 3 or more Component: an aromatic dicarboxylic acid component; an aliphatic dialcohol In particular, as a polyvalent monomer having a valence of 3 or more in the component Is preferably a benzenetricarboxylic acid.

[Action]

Polyester used as a binder resin of the toner is a specific ratio of trivalent or more polyvalent monomer, aromatic dicarboxylic acid,
A polyester having a specific OHV / AV and glass transition point obtained by subjecting a monomer composition containing an aliphatic dialcohol to a polycondensation reaction, particularly an aliphatic dihydric alcohol instead of a conventionally used bisphenol alcohol. Since the alcohol is used, the flexibility of the molecular chain in the polyester is improved. Therefore, the mechanical energy due to the stirring of the developer and the like is converted into the kinetic energy of the molecular chains of the polyester, so that the mechanical stress applied to the toner particles is considerably reduced and the destruction of the toner particles is effectively prevented. Is done.

Therefore, even when an image is formed many times, the triboelectric charging property of the toner is stable, and the rise of the triboelectric charging property of the toner is remarkably improved due to the presence of the inorganic fine particles treated with the nitrogen-containing substance. Stable for a long time.

In particular, when the polyester, which is the binder resin of the toner, has a specific OHV / AV value, the above-described effect is reliably obtained, and the storability of the toner as a powder is improved.

[Specific configuration of the invention]

 Hereinafter, the configuration of the present invention will be specifically described.

The toner constituting the electrostatic image developer used in the image forming method of the present invention comprises a polyester (hereinafter, also referred to as “specific polyester”) obtained by subjecting a monomer composition containing the above components to to a polycondensation reaction. It is contained as a resin.

Examples of the trivalent or higher polyvalent monomer of the component include a trivalent or higher polycarboxylic acid and / or a trivalent or higher polyhydric alcohol.

Examples of the trivalent or higher polyvalent carboxylic acid as the component include 1,2,4-benzenetricarboxylic acid, 1,3,5-benzenetricarboxylic acid, 1,2,4-cyclohexanetricarboxylic acid, 2,5, 7-naphthalenetricarboxylic acid, 1,2,4-
Naphthalenetricarboxylic acid, 1,2,4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-methylenecarboxypropane, tetra (methylenecarboxy) methane, 2,7,8−
Examples include octanetetracarboxylic acid, empoletrimer acid, anhydrides and esters of these acids, and the like.

Examples of the trihydric or higher polyhydric alcohol as the component include sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, sucrose, , 2,4-butanetriol, 1,2,5-pentanetriol, glycerol, 2-methylpropanetriol,
Examples thereof include 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane, and 1,3,5-trihydroxymethylbenzene.

Among these trivalent or higher polyvalent monomers, benzenetricarboxylic acids such as benzenetricarboxylic acid and anhydrides or esters of these acids are particularly preferred. That is, by using benzenetricarboxylic acids, stable triboelectricity can be imparted to the toner, and the fixability, hot offset resistance, and durability of the toner are improved.

The compounding ratio of the trivalent or higher polyvalent monomer is 1 to 30 mol% of the whole monomer composition. When the compounding ratio is too small, the hot offset resistance of the toner deteriorates, and the durability also deteriorates. On the other hand, when the mixing ratio is excessive, the fixability of the toner is deteriorated.

Examples of the aromatic dicarboxylic acid as the component include phthalic acid, isophthalic acid, terephthalic acid, and anhydrides or esters of these acids.

Other dicarboxylic acids may be used in combination with the above aromatic dicarboxylic acids. Examples of such other dicarboxylic acids include, for example, maleic acid, fumaric acid, mesaconic acid, citraconic acid, itaconic acid, glutaconic acid, cyclohexanedicarboxylic acid, succinic acid, adipic acid, sebacic acid,
Malonic acid or anhydrides or esters of these acids, dimers of linoleic acid, n-dodecenyl succinic acid,
Examples thereof include alkenyl succinic acid or alkyl succinic acid such as n-dodecyl succinic acid, anhydrides or esters of these acids, and other bifunctional organic acid monomers. The mixing ratio of such other dicarboxylic acids is preferably 30 mol% or less of the whole dicarboxylic acids. When the mixing ratio of the other dicarboxylic acid is excessive, the glass transition point Tg of the specific polyester is lowered and the storage stability of the toner is deteriorated.

As the aliphatic dialcohol of the component, for example, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol such as pentaethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, dipropylene glycol, Tripropylene glycol, 1,
Examples thereof include diols such as 4-butanediol, neopentyl glycol, 1,4-butenediol, 1,5-pentanediol, and 1,6-hexanediol. Among the aliphatic dialcohols, aliphatic dialcohols having 2 to 10 carbon atoms are particularly preferred. When the carbon number is too small, the moisture resistance is poor, while when the carbon number is too large, the glass transition point is lowered, the fluidity under high temperature and high humidity is reduced, and the developability is deteriorated.

Other dialcohols may be used in combination with the above aliphatic dialcohols. Examples of such other dialcohols include etherified bisphenols such as 1,4-bis (hydroxymethyl) cyclohexane, bisphenol A, hydrogenated bisphenol A, polyoxyethylenated bisphenol A, polyoxypropylene bisphenol A, and the like. And a bifunctional alcohol monomer of The mixing ratio of such other dialcohols is preferably not more than 30 mol% of the whole dialcohols. When the mixing ratio of the other dialcohol is excessive,
The brittleness of the obtained polyester increases, and fine powder of the toner is easily generated, and the durability of the developer deteriorates.

As the specific polyester, a polyester having a ratio of hydroxyl value (OHV) to acid value (AV) of OHV / AV of 1.0 to 5.0 is used, and particularly preferably 1.2 to 3.0. When the value of the ratio OHV / AV is too small, the fluidity of the toner deteriorates, the triboelectrification property decreases, and the developability decreases. On the other hand, when the value of the ratio OHV / AV is too large, the storage stability as a powder deteriorates.

Here, the acid value (AV) refers to the number of milligrams of potassium hydroxide required to neutralize the acid contained in 1 g of a sample. The hydroxyl value (OHV) is the number of milligrams of potassium hydroxide required to neutralize acetic acid bound to a hydroxyl group when acetylating 1 g of a sample in accordance with the Standard Fatty Acid Analysis Test Method (edited by the Japan Association of Fatty Chemicals). Say.

Further, the softening point Tsp of the specific polyester is 90
To 170 ° C, more preferably 100 to 160 ° C. When the softening point Tsp is too small, the storage stability of the toner as a powder deteriorates, and the hot offset resistance deteriorates. On the other hand, when the softening point Tsp is excessively large, the fixability deteriorates.

Here, the softening point Tsp refers to the Koka type flow tester “CFT
Using a “-500 type” (manufactured by Shimadzu Corporation), the measurement conditions were a load of 20 kg / cm ² , a nozzle diameter of 1 mm, a nozzle length of 1 mm, preheating at 80 ° C for 10 minutes, and a heating rate of 6 ° C / min. , Sample amount
When measured and recorded as 1 cm ³ (intrinsic specific gravity × weight expressed by 1 cm ³ ), when the height of the S-shaped curve in the plunger descent-temperature curve (softening flow curve) of the flow tester is h, h / The temperature at d.

Further, the glass transition point Tg of the specific polyester,
It needs to be 50-70 ° C. Such a glass transition point
If the Tg is too small, the storage stability of the toner as powder deteriorates, and the hot offset resistance deteriorates. On the other hand, when the glass transition point Tg is excessively large, the fixability deteriorates.

Here, the glass transition point Tg refers to a differential scanning calorimeter
Using a DSC (manufactured by Rigaku Denki) at a heating rate of 10 ° C / min, an extension of the baseline below the glass transition point of the DSC thermogram in the glass transition region and the peak from the rising part of the peak Is the value when the temperature at the point of intersection with the tangent line indicating the maximum slope up to the top is defined as the glass transition point.

The toner constituting the electrostatic image developer used in the image forming method of the present invention basically includes, for example, a coloring agent, a charge control agent, an offset preventing agent, and the like in a binder resin made of the above specific polyester. It is composed of a particle powder in which an additive is dispersed and contained, and its average particle size is preferably about 5.0 to 15.0 μm.

Examples of the coloring agent include carbon black, nigrosine dye (CINo. 50415B), and aniline blue (CINo. 50).
405), Calco Oil Blue (CINo.azoic Blue3),
Chrome Yellow (CINo.14090), Ultramarine Blue (CINo.77103), Dupont Oil Red (CINo.2)
6105), quinoline yellow (CINo. 47005), methylene blue chloride (CINo. 52015), phthalocyanine blue (CINo. 74160), malachite green oxalate (CINo. 42000), lamp black (CINo. 7726)
6), Rose Bengal (CINo.45435), mixtures thereof, and others can be used. The mixing ratio of the colorant is preferably about 1 to 20 parts by weight based on 100 parts by weight of the binder resin.

As the charge control agent, those having a positive charge property are used. For example, quaternary ammonium compounds disclosed in JP-A-49-51951 and JP-A-52-10141;
No. 11461, No. 54-158932, U.S. Pat.
Alkylpyridinium compounds and alkylpicolinium compounds disclosed in, for example, Japanese Patent No. 05;
Nigrosine dyes such as SO and Nigrosine EX;
Addition condensates disclosed in JP-A-49-80320 can be used.

Examples of the anti-offset agent include olefin polymers or copolymers having a low softening point such as polyethylene and polypropylene; paraffin wax having a high melting point such as microwax and Fischer-Tropsch wax; and liquid paraffin which is a liquid at room temperature and is a saturated or unsaturated paraffin. For example, silicone varnishes such as methyl silicon varnish and phenyl silicon varnish, aliphatic fluorocarbon compounds such as low-polymerized compounds of ethylene tetrafluoride and propylene hexafluoride, lower alcohol esters of fatty acids, polyhydric alcohol esters of fatty acids, and fatty acids Higher alcohol esters, partial esters of fatty acids and polyhydric alcohols, fatty acid esters such as mixed esters and their partially saponified products, alkylenebisfatty acid amides, higher fatty acids, fats Acid metal salt, higher alcohols,
For example, fluorine-containing surfactants described in JP-A-55-124428 can be exemplified. Such an anti-offset agent can be used alone or in combination of two or more, and its use ratio is, for example, preferably 1 to 20% by weight, particularly preferably 1 to 10% by weight, based on the binder resin. .

In the case of constituting a magnetic toner, magnetic particles are dispersed and contained in the toner particles. As such a magnetic material,
Ferromagnetic metals or alloys such as iron, ferrite, magnetite, cobalt, nickel, etc. or compounds containing these elements, or do not contain ferromagnetic elements but exhibit ferromagnetism by appropriate heat treatment Alloys, such as manganese-copper-aluminum, manganese-copper-tin, and other alloys of the type called Heusler alloys containing manganese and copper, or chromium dioxide, and the like. These magnetic materials have an average particle size of 0.1
Used in the form of fine powder of about 1 μm,
It is preferably 20 to 70 parts by weight, particularly preferably 30 to 60 parts by weight, per 100 parts by weight.

The inorganic fine particles constituting the electrostatic image developer used in the present invention together with the toner are those treated with a nitrogen-containing substance.

As such a nitrogen-containing substance, for example, an amino-modified silicone compound is preferable. According to the inorganic fine particles treated with the amino-modified silicone compound, the presence of the amino group makes the inorganic fine particles excellent in positive chargeability, and furthermore, the functional groups of the silicone compound and the hydroxyl groups present on the surface of the free fine particles. As a result, the inorganic fine particles are excellent in moisture resistance and durability, and have stable positive triboelectric charge that is not affected by environmental conditions.

Examples of the amino-modified silicone compound include an amino-modified silane coupling agent, an amino-modified silicone oil, an amino-modified silicone varnish, an amino-modified silicone rubber, and an amino-modified silicone resin. In terms of obtaining the nature,
Amino-modified silicone varnish, amino-modified silicone rubber, and amino-modified silicone resin are preferred.

As the amino-modified silane coupling agent, for example, the following compounds can be preferably used.

H ₂ NCH ₂ CH ₂ CH ₂ Si (OCH ₃ ) ₃ H ₂ NCH ₂ CH ₂ CH ₂ Si (OC ₂ H ₅ ) ₃ H ₂ NCONHCH ₂ CH ₂ CH ₂ Si (OC ₂ H ₅ ) ₃ H ₂ NCH ₂ CH ₂ NHCH ₂ CH ₂ CH ₂ Si (OCH ₃ ) ₃ H ₂ NCH ₂ CH ₂ NHCH ₂ CH ₂ NHCH ₂ − −CH _{2 CH 2 Si (OCH 3) 3} H 5 C 2 OCOCH 2 CH 2 NHCH 2 CH 2 CH 2 - -Si (OCH 3) 3 H 5 C 2 OCOCH 2 CH 2 NHCH 2 CH 2 NH- -CH 2 CH 2 CH _{2 Si (OCH 3) 3 H} 5 C 2 OCOCH 2 CH 2 NHCH 2 CH 2 NH- -CH 2 CH 2 NHCH 2 CH 2 NHCH 2 - -CH 2 CH 2 Si (OCH 3) 3 H 3 COCOCH 2 CH 2 NHCH ₂ CH ₂ NH− −CH ₂ CH ₂ CH ₂ Si (OCH ₃ ) _{3 H 3 CNHCH 2 CH 2 CH 2} Si (OC 2 H 5) 3 H 2 N (CH 2 CH 2 NH) 2 CH 2 CH 2 CH 2 - -Si (OCH 3) 3 Further, in the above compound, a form in which an alkoxy group is substituted by a chlorine atom may be used. These compounds may be used alone or in combination of two or more.

As the amino-modified silicone oil, for example, those represented by the following general formula (1) can be preferably used.

General formula (1) (R ¹¹ represents an alkylene group, an aryl group, an aminoalkylene group, etc., R ¹² and R ¹³ each represent a hydrogen atom, a hydroxyl group, an alkyl group, an aryl group, etc., x, y
Represents an integer of 1 or more. As the amino-modified silicone oil, those having an amino equivalent value in the range of 200 to 22500 are preferable.
Those in the range of 300 to 10,000 are preferred. When the value of the amino equivalent is too small, the effect of imparting positive chargeability by the inorganic fine particles is small, and as a result, an unclear image with fog may be obtained.On the other hand, when the value of the amino equivalent is excessive, the inorganic fine particles are Transfer tends to occur, which may result in a decrease in the durability of the developer.

As the amino-modified silicone oil, one having a viscosity at 25 ° C. in the range of 10 to 100 cps is preferable, and one having a viscosity in the range of 20 to 3500 cps is particularly preferable. When the viscosity is too low, the adhesiveness of the inorganic fine particles increases, and as a result, the durability of the developer may decrease.On the other hand, when the viscosity is too high, proper surface treatment becomes difficult,
As a result, the positive chargeability of the toner becomes unstable, and the durability of the developer may decrease.

Commercially available amino-modified silicone oils that can be preferably used include, for example, those listed in Table 1 below.

Examples of the silicone varnish used to obtain the amino-modified silicone varnish include methyl silicone varnish and phenylmethyl silicone varnish, and methyl silicone varnish is particularly preferable.

Methyl silicone varnish has a T represented by the following structural formula.
It is a polymer consisting of ²¹ units, D ²¹ units and M ²¹ units, and a three-dimensional polymer containing a large amount of T ²¹ units.

Further, methyl silicone varnish or phenyl methyl silicone varnish is specifically a substance having a chemical structure represented by, for example, the following structural formula (1).

(R ²¹ represents a methyl group or a phenyl group.) In the above silicone varnish, the T ²¹ unit is particularly a unit effective for imparting good thermosetting properties and for forming a three-dimensional network structure. inorganic fine particles whose surface has been treated with a silicone varnish containing hunt T ²¹ unit is made to have a tough film is hard on the surface, therefore the impact strength, moisture resistance, and is excellent in releasability. T ²¹ above
The unit is 10 to 90 mol% in the silicone varnish, especially 30 to 90 mol%.
It is preferably contained at a ratio of 80 mol%. When the proportion of the T ²¹ unit is too small, increased adhesiveness to soften might moisture resistance, durability, stability of triboelectric chargeability decreases, especially reduced cleaning property of the toner, also Toner scattering may occur, resulting in image unevenness, fogging, and the like, and further, the durability of the fixing device may be reduced.
On the other hand, when the proportion of the T ²¹ unit is too large, the coating layer formed on the surface of the inorganic fine particles is not uniform, the frictional chargeability of stability, durability may decrease.

In addition, such a silicone varnish has a hydroxyl group at a terminal or a side chain of a molecular chain, and is cured by dehydration condensation of the hydroxyl group. As a curing accelerator that can be used to accelerate this curing reaction,
Examples thereof include fatty acid salts such as zinc, lead, cobalt, and tin; and amines such as triethanolamine and butylamine. Of these, amines can be particularly preferably used.

The silicone rubber used for obtaining the amino-modified silicone rubber is, for example, a long-chain polymer composed of only ^D31 units represented by the following structural formula, and having a viscosity at a temperature of 25 ° C. of, for example, 10 ⁵ to 10 ⁹ Those having an average molecular weight of, for example, 10 ⁴ to 10 ⁸ in cps can be preferably used. In particular, the viscosity is 10 ⁶ to 10 ⁸ cps and the average molecular weight is 1
Those which are from 0 ⁵ to 10 ⁷ are preferred. When the viscosity is too low or the average molecular weight is too low, durability and moisture resistance may decrease.On the other hand, when the viscosity is too high or the average molecular weight is too high, uniform surface treatment becomes difficult, resulting in friction. The chargeability becomes unstable and an unclear image with fog tends to be formed, and the durability and moisture resistance may be reduced.

(R ³¹ and R ³² each represent an alkyl group such as a methyl group or an ethyl group, an aromatic group such as a phenyl group, a polyether, and the like.) R ³¹ and R ³² of the D unit each represent a methyl group or a phenyl group. And particularly preferably a methyl group. Further, in order to make the silicone rubber have a crosslinked structure, it is preferable to use a small amount of ^D33 unit represented by the following structural formula together with ^D32 unit represented by the following structural formula to copolymerize.

By thus forming the silicone rubber into a crosslinked structure, the inorganic fine particles whose surface has been treated with the silicone rubber have a hard and tough film on the surface, and therefore have impact strength, moisture resistance, and separation resistance. It has excellent moldability.

Further, such a silicone rubber preferably has a hydroxyl group at a terminal or a side chain of a molecular chain, and curing is promoted by dehydration condensation of the hydroxyl group, and the hydroxyl group and the functional group on the surface of the inorganic fine particles are promoted. The reaction allows the formation of a film by a strong chemical bond. Known vulcanizing agents can be used to accelerate this curing reaction. Specifically, for example, benzoyl peroxide, bis-2,
Organic peroxides such as 4-dichlorobenzoyl peroxide, di-t-butyl peroxide and dicumyl peroxide can be preferably used.

Silicone resin used to obtain the amino-modified silicone resin, T ⁴¹ units represented by the following structural formula, D
It is a polymer composed of ⁴¹ units, D ⁴² units and M ⁴¹ units, and is a polymer containing a large amount of T ⁴¹ units unlike silicone oil.

(R ⁴¹ , R ⁴² , R ⁴³ , R ⁴⁴ , R ⁴⁵ , and R ⁴⁶ each represent an organic group such as an alkyl group such as a methyl group or an ethyl group and an aromatic group such as a phenyl group.) The resin has a hard property because there are many branches and a large number of fine networks formed by crosslinking, and the ^T41 unit is an effective unit for forming a crosslinked structure and has a cyclic structure in the molecule. Is also an effective unit for forming the above structure, so that the silicone resin has tough properties and also has flexible properties. Further, since a considerable amount of silanol groups having OH groups that are freely present without forming a siloxane bond remain in the silicone resin, the silanol groups react with functional groups present on the surface of the inorganic fine particles, or Siloxane bonds are formed during the curing stage,
As a result, the silicone resin has more tough properties.

Therefore, the inorganic fine particles whose surface is treated with such a silicone resin have a tough and flexible film on the surface, and therefore have excellent impact strength, moisture resistance, and release properties. .

To the above-mentioned silicone varnish and amino-modified silicone varnish, the T ²¹ unit, D ²¹ unit, if substituted group having an amino group and a part of the methyl group or a phenyl group present in the M ²¹ units Good. Further, in order to make the silicone rubber an amino-modified silicone rubber,
A part of R ³¹ and R ^{32 in} the D ³¹ unit may be substituted with a group having an amino group. Further, in order to make the silicone resin an amino-modified silicone resin, the ^T41 unit, ^D41 unit,
Organic groups present in D ⁴² units and M ⁴¹ units (R ⁴¹ , R ⁴² , R ⁴³ , R
⁴⁴ , R ⁴⁵ , R ⁴⁶ ) may be partially substituted with a group having an amino group.

Examples of such a group having an amino group include those represented by the following structural formula.

_{-CH 2 CH 2 -NH 2 -CH 2} (CH 2) 2 -NH 2 -CH 2 (CH 2) 2 -NHM (CH 2) 3 -NH 2 As the inorganic fine particles before being treated with the nitrogen-containing substance as described above, for example, silica, alumina, titanium oxide,
Examples include fine particles of barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, chromium oxide, cerium oxide, antimony trioxide, zirconium oxide, silicon carbide, and the like.

In particular, silica fine particles can be preferably used as the inorganic fine particles. Silica fine particles are fine particles having a Si-O-Si bond, and may be any of those manufactured by a dry method and a wet method, but those manufactured by a dry method are preferable, and in particular, a silicon halide compound. It is preferable that the particles are silica fine particles generated by vapor phase oxidation. In addition, as silica fine particles, in addition to silicon dioxide (silica), aluminum silicate, sodium silicate, calcium silicate, potassium silicate, zinc silicate,
Fine particles made of a silicate such as magnesium silicate may be used, but those containing 85% by weight or more of SiO ₂ are preferable.

As a method of treating the surface of the inorganic fine particles with the nitrogen-containing substance as described above, a known technique can be used,
Specifically, for example, a method in which inorganic fine particles are dispersed in a solution in which a nitrogen-containing substance is dissolved in a solvent as described above, and then the solvent is removed by filtration or spray drying, and then cured by heating, or fluidized. By using a bed apparatus, a method in which a solution in which a nitrogen-containing substance is dissolved in a solvent as described above is spray-coated on inorganic fine particles, and then heated and dried to remove the solvent and cure the film, or the like can be used.

The average particle diameter of the primary particles (particles separated into individual unit particles) of the positively-chargeable inorganic fine particles whose surfaces are treated with the nitrogen-containing substance as described above is as follows. It is preferably in the range of 3 μm to 2 μm, especially 5 μm to 500 μm. The BET specific surface area is 20
Preferably it is 500 m ² / g. When the average particle diameter is too small or the BET specific surface area is too large, for example, when cleaning is performed using a blade-type cleaning device, inorganic fine particles may easily pass through, and cleaning failure may occur. On the other hand, when the average particle size is too large or the BET specific surface area is too small, the fluidity of the developer is reduced and the developability is deteriorated, and as a result, the image density may be reduced or image unevenness may occur. .

It is preferable that the inorganic fine particles treated with the nitrogen-containing substance are contained in a state of being attached to the surface of the toner particles by being externally added to and mixed with the toner.

The content ratio of the inorganic fine particles treated with the nitrogen-containing substance is preferably from 0.1 to 5% by weight, particularly preferably from 0.1 to 2% by weight of the toner. When the content ratio is too small, the fluidity of the developer may decrease, and as a result, the triboelectricity of the toner becomes poor, and it becomes difficult to impart a proper amount of positive charge to the toner, Fog and image unevenness may occur. On the other hand, when the content ratio is excessive, a part of the inorganic fine particles may be present in a state of being separated from the toner particles, and as a result, the released inorganic fine particles may adhere to and transfer to the carrier particles, or the inner wall of the developing device. The toner adheres and accumulates on a developing sleeve, a regulating blade, and the like, and eventually, the triboelectricity of the toner becomes poor at an early stage, and it becomes difficult to apply a proper amount of positive charge to the toner, thereby reducing fog and image density. May occur.

In the present invention, when a two-component developer is used,
A carrier is further used together with the toner and the inorganic fine particles treated with the nitrogen-containing substance.

Such a carrier is not particularly limited, but an uncoated carrier made of magnetic particles, a resin-coated carrier obtained by coating the surface of magnetic particles with a resin, and a magnetic material obtained by dispersing and containing magnetic particles in a binder resin. A body dispersion type carrier or the like can be used.

The magnetic particles constituting the carrier include substances strongly magnetized in the direction by a magnetic field, for example, iron, ferrite, iron, including magnetite, nickel, cobalt, and other ferromagnetic metals or alloys or these elements. Alloys that do not contain compounds or ferromagnetic elements but become ferromagnetic when appropriately heat-treated, such as alloys of the type called Heusler alloys such as manganese-copper-aluminum or manganese-copper-tin or chromium dioxide Can be used.

Here, ferrite is a general term for magnetic oxides containing iron, and is not limited to spinel-type ferrite represented by the chemical formula of MO.Fe ₂ O ₃ (M is a divalent metal). Such ferrite can be suitably used in the present invention because various magnetic properties can be obtained by changing the composition of the contained metal component. Among them, manganese-zinc-based ferrite and nickel-zinc-based ferrite have higher electric resistance and exhibit excellent triboelectric charging ability, so copper-
Zinc ferrite is particularly preferred. Also, since ferrite is an oxide, its specific gravity is smaller and lighter than metals such as iron and nickel. Therefore, it is easy to mix and stir with toner, uniform toner concentration and uniform triboelectric charge. It is suitable in achieving.

As the resin for coating the resin-coated carrier or the binder resin for the magnetic material-dispersed carrier, for example, a styrene-acrylic copolymer, a silicone compound, a fluorine resin, or the like can be suitably used.

The average particle size of the carrier is preferably from 20 to 200 μm, particularly preferably from 40 to 150 μm. When the average particle size is too small, a carrier adheres to the electrostatic latent image to form a fixed image, a so-called carrier adhesion phenomenon occurs, and as a result, the image may be unclear, while when the average particle size is excessive, Image alignment may occur. Here, the average particle size (weight) of the carrier refers to a value measured using “Microtrack” (manufactured by Nikkiso Co., Ltd.).

The developing method is not particularly limited, and various known developing methods can be employed. Specifically, (1) a magnetic brush of the developer is carried on a developer carrying carrier in a state where the layer thickness is larger than, for example, a gap in the developing area, and the magnetic brush is carried into the developing area and is immersed by the magnetic brush. A contact type magnetic brush method in which toner particles or particles in a magnetic brush are attached to a latent image while rubbing an image to perform development, and (2) a magnetic brush of a developer has a layer thickness smaller than, for example, a gap in a development area. In this state, the magnetic brush is carried on a developer carrier, the magnetic brush is carried into the developing area, and an oscillating electric field or the like is applied to the developing area, thereby causing the toner particles or particles in the magnetic brush to fly while flying. The development can be performed by employing a development method such as a non-contact magnetic brush method in which particles or particles are adhered to a latent image for development, and (3) a cascade method.

〔Example〕

Hereinafter, examples of the present invention will be specifically described, but the present invention is not limited to these examples.

<Production of Polyester> A dicarboxylate and a dialcohol shown in Table 1 below were converted to a capacity 1 equipped with a thermometer, a stainless steel stirrer, a glass nitrogen gas inlet tube, and a falling condenser.
, The flask was set in a mantle heater, nitrogen gas was introduced from a nitrogen gas inlet tube, and the temperature was raised while keeping the inside of the flask in an inert atmosphere. After dibutyltin oxide was added and reacted at a temperature of 200 ° C., trivalent or higher polyvalent monomers shown in Table 1 below were added and further reacted to obtain each polyester.

Acid value (AV), hydroxyl value (OHV), ratio O of each polyester
The values of HV / AV, softening point Tsp and glass transition point Tg are as shown in Table 2 below.

<Production of Toner> The toner materials shown in Table 3 below were mixed, kneaded, and cooled, then roughly pulverized by a hammer mill, further finely pulverized by a jet mill, and then classified to have an average particle diameter of 11.0 μm.
Were produced.

<Manufacture of Inorganic Fine Particles> (1) Inorganic Fine Particles 1 (for the Present Invention) 100 parts by weight of silica fine particles “Aerosil 200” (manufactured by Nippon Aerosil Co., Ltd.) having an average particle diameter of 12 μm and a BET specific surface area of 200 m ² / g are rotated at high speed. Into a mixer and then N-β (aminoethyl) γ-aminopropyltrimethoxysilane “KBM60
3 "(manufactured by Shin-Etsu Chemical Co., Ltd.) and 8 parts by weight of hexamethyldisilazane" SZ6079 "(manufactured by Toray Silicone Co., Ltd.) dissolved in 100 parts by weight of hexane are dropped into the high-speed mixer. After adding and surface treatment,
The contents of the mixer were transferred to a flask and heated for 5 hours with stirring at a temperature of 100 to 150 ° C. in an inert gas atmosphere to remove hexane as a solvent and proceed with the reaction, and treated with a nitrogen-containing substance. Inorganic fine particles 1 were produced. The inorganic fine particles 1 had an average primary particle diameter of 12 mμ and a BET specific surface area of 190 m ² / g.

(2) Inorganic fine particles 2 (for the present invention) In the production of the inorganic fine particles 1, the amino equivalent was 350
In addition to 10 parts by weight of amino-modified silicone oil "SF8417" (manufactured by Toray Silicone Co., Ltd.) having a viscosity of 1200 cps at 0 and 25 ° C., and 8 parts by weight of hexamethyldisilazane "SZ6079" (manufactured by Toray Silicone Co., Ltd.) Was treated in the same manner to produce inorganic fine particles 2 treated with a nitrogen-containing substance. The inorganic fine particles 2 have an average primary particle diameter of 13 m.
μ, BET specific surface area was 180 m ² / g.

(3) Inorganic fine particles 3 (for the present invention) In the production of the above inorganic fine particles 1, the average particle diameter was 16 m.
μ, silica fine particles with a BET specific surface area of 130 m ² / g
130 "(manufactured by Nippon Aerosil Co., Ltd.) and 100 parts by weight of an amino-modified silicone varnish having the structural unit represented by the following structural formula dissolved in 100 parts by weight of xylene. By the treatment, inorganic fine particles 3 treated with a nitrogen-containing substance were produced. This inorganic fine particle 3
Has an average primary particle size of 16 mμ and a BET specific surface area of 92 m ² / g
Met.

(X, y, and z are each an integer of 1 or more, and x: y: z = 1: 4:
5 (4) Inorganic fine particles 4 (for the present invention) In the production of the above inorganic fine particles 1, the average particle diameter is 7 mμ,
AEROSIL 30 silica fine particles with a BET specific surface area of 300 m ² / g
0 "(manufactured by Nippon Aerosil Co., Ltd.) and 100 parts by weight of amino-modified silicone rubber 25 having a structural unit represented by the following structural formula
Inorganic fine particles 4 treated with a nitrogen-containing substance were produced in the same manner except that a treating solution prepared by dissolving parts by weight and 0.2 parts by weight of benzoyl peroxide in 125 parts by weight of xylene was used. The inorganic fine particles 4 have an average primary particle diameter of 7 m.
μ, BET specific surface area was 166 m ² / g.

(X, y, and z are each an integer of 1 or more, and x: y: z = 7: 1:
2 (5) Inorganic fine particles 5 (for the present invention) As structural units, the following D ¹ unit, the following D ² unit, and the following AD ¹
Units, having the following T ¹ units, and their molar ratio is 4.5: 0.5: 1:
The amino-modified silicone resin of No. 4 and benzoyl peroxide of 0.5% by weight based on the amino-modified silicone resin were dissolved in xylene to prepare a treatment liquid.

Next, silica fine particles “Aerosil 300” (manufactured by Nippon Aerosil Co., Ltd.) were placed in a mixer, and a treatment liquid was sprayed on the silica fine particles at a ratio such that the amino-modified silicone resin was 20% by weight. Was placed in a flask, and while stirring, the solvent xylene was removed at a temperature of 120 ° C. for 5 hours, and at the same time, the amino-modified silicone resin was cured to produce inorganic fine particles 5 treated with a nitrogen-containing substance. The inorganic fine particles 5 had an average primary particle diameter of 7 mμ and a BET specific surface area of 135 m ² / g.

(6) Comparative inorganic fine particles 1 Negatively charged silica fine particles "Aerosil R-972" (manufactured by Nippon Aerosil Co., Ltd.) are used as comparative inorganic fine particles 1.

<Manufacture of carrier> (1) Carrier 1 Vinylidene fluoride-ethylene tetrafluoride copolymer "VT-
6 g of “100” (copolymer molar ratio = 80: 20, intrinsic viscosity = 0.95 dl / g, manufactured by Daikin Industries, Ltd.) and 6 g of methyl methacrylate copolymer “Acripet MF” (manufactured by Mitsubishi Rayon Co., Ltd.) And mixed solvent of methyl ethyl ketone (mixing volume ratio =
1: 1) The coating solution was prepared by dissolving in 500 ml. Using a fluidized bed apparatus, apply the coating solution to 1 kg of magnetic particles made of spherical copper-zinc-based ferrite (manufactured by Nippon Tekko Kogyo Co., Ltd.), further heat-treat at 200 ° C. for 5 hours, and then aggregate. The material was sieved to produce a carrier 1 having a resin coating layer having a thickness of about 2 μm. The average particle size of the carrier 1 was 82 μm.

(2) Carrier 2 Using a fluidized bed apparatus, silicone varnish “SR-
8101 parts (manufactured by Toray Silicone Co., Ltd.) is applied to 100 parts by weight of magnetic particles made of spherical copper-zinc ferrite (manufactured by Nippon Iron Powder Co., Ltd.), and further heat-treated at 200 ° C. for 5 hours. Then, the aggregate was sieved to produce a carrier 2 having a resin coating layer. This carrier 2
Was 82 μm.

(3) Carrier 3 Spherical ferrite particles having no resin coating layer “F-15”
“0” (manufactured by Nippon Tekko Kogyo Co., Ltd.) is designated as carrier 3 The average particle size of the carrier 3 was 80 μm.

Examples and Comparative Examples In each of Examples and Comparative Examples, inorganic fine particles, toner and carrier in the combinations shown in Table 4 below were used, and first, inorganic fine particles were added to the toner, and these were mixed by a Henschel mixer. Then, inorganic fine particles were adhered and held on the surface of the toner particles, and a carrier was mixed with the inorganic fine particles by a V-type mixer to produce each developer.

<Actual photo test> An electrophotographic copying machine "U-Bix 1550M" equipped with an organic photoreceptor for forming a negative electrostatic latent image using each of the above developers.
R ”(manufactured by Konica Corp.)
Under the environmental conditions of 0 ° C and 60% relative humidity), a real-image test was performed to form a copy image continuously 50,000 times.
The following items were evaluated.

(1) Fog The relative density of a white background (a portion corresponding to a white background having an original density of 0.0) in a copied image was measured by using "Sakura Densitometer" (manufactured by Konica Corporation). In addition,
The white background reflection density was set to 0.0. The evaluation was “○” when the relative concentration was less than 0.01, “△” when it was 0.01 or more and less than 0.03, and “×” when it was 0.03 or more.

(2) Image Density For the copied image after 50,000 times, the maximum value of the relative density of the image portion in the copied image was measured using a “Sakura Densitometer” (manufactured by Konica Corporation) and judged. As for the practical level, the maximum value is 1.0 or more.

(3) Toner scattering The inside of the copying machine and the copied image were visually observed, and “○” indicates that toner scattering was hardly observed and was good, “△” indicates that toner scattering was slightly observed but was at a practical level, and “ト ナ ー” A case where there was a lot of scattering and there was a problem in practice was marked as "x".

(4) Back surface dirt on the leading edge of the transfer paper The leading edge region on the back surface of the transfer paper that passed through the fixing device was visually observed and evaluated. "○" indicates that the back surface dirt is hardly recognized and is good, "△" indicates that the back surface dirt is slightly recognized but is at a practical level, and "x" indicates that the back surface dirt is recognized and is practically problematic. "

 The above results are shown in Table 5 below.

As can be understood from the results of the above examples, according to the electrostatic image developer used in the image forming method of the present invention, fine powder due to destruction of toner particles was not generated, and stable for a long period of time. The triboelectricity is exhibited, and
An image with no fog and high image density can be stably formed many times without toner scattering and back surface dirt at the leading edge of the transfer paper.

On the other hand, according to the comparative developer 1, when an image is formed many times, toner particles are broken by mechanical external force such as agitation received in the developing device, and fine powder is generated. Adhesion lowers the triboelectrification of the toner and carrier, causing toner scattering and fogging. Also,
According to the comparative developer 2, since the negatively chargeable silica fine particles are used, even when a fluororesin-coated carrier having a strong negative chargeability is used, the rise of the triboelectric chargeability of the toner is poor, and an image is formed many times. Then, toner scattering occurs, and even if the surface state of the carrier is slightly changed, the triboelectric charging becomes unstable and fogging occurs.

〔The invention's effect〕

According to the image forming method of the present invention, a specific polyester is used as a binder resin for a toner in an electrostatic image developer to be used. Can be effectively prevented. Therefore, the characteristics of the inorganic fine particles treated with the nitrogen-containing substance are sufficiently exhibited, and stable triboelectricity is exhibited for a long period of time. A good image having a high density can be formed. Then, the value of OHV / AV of the polyester which is the binder resin of the toner is 0.1.
By setting the value to 5.0, the above-described effects are reliably obtained, and the storability of the toner as a powder is improved.

Further, as a trivalent or higher polyvalent monomer in the component,
In particular, by using benzenetricarboxylic acids, a more stable triboelectric charging property can be imparted to the toner, and the fixing property and the hot offset resistance are improved.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masafumi Uchida 2970, Ishikawacho, Hachioji-shi, Tokyo Konica Corporation (72) Inventor Toshiko Yajima 2970, Ishikawacho, Hachioji-shi, Tokyo Konica Corporation (56) References JP-A-60-176044 (JP, A) JP-A-58-14144 (JP, A) JP-A-58-11952 (JP, A) JP-A-58-7647 (JP, A) JP-A-59-128558 (JP, A) JP-A-62-129862 (JP, A) JP-A-62-8164 (JP, A) JP-A-61-284771 (JP, A) JP-A-62-195677 (JP, A)

Claims (2)

(57) [Claims] An image including a step of developing a negative electrostatic latent image formed on an organic photoreceptor with an electrostatic image developer having a toner and inorganic fine particles treated with a nitrogen-containing substance. In the forming method, the toner has a ratio OHV / AV of a hydroxyl value (OHV) to an acid value (AV) of 1.0 to 5.0, which is obtained by subjecting a monomer composition containing the following components to a condensation polymerization reaction. An image forming method comprising a polyester having a glass transition point of 50 to 70 ° C. as a binder resin. Ingredients: 1 to 30 mol% of the entire monomer composition, a polyvalent monomer having a valence of 3 or more Ingredients: Aromatic dicarboxylic acid ingredient; Aliphatic dialcohol 2. The image forming method according to claim 1, wherein the trivalent or higher polyvalent monomer in the component is a benzenetricarboxylic acid.