JPS6361263A - Positively electrifiable toner - Google Patents

Abstract

PURPOSE:To obtain the toner stable in electrifiability and fluidity independently of environmental condition by incorporating a specific styrene resin and a fatty acid (derivative) which is slightly soluble in water to the titled toner. CONSTITUTION:The toner contains the styrene resin (A) and the resin (for example, polystyrene) which is substantially electrostatically neutral, and a coloring matter. The resin A is composed of a copolymer of styrene (derivative), alkyl(meth)acrylate contg. nitrogen atom, and 0.1-50wt% of a monomer shown by the formula. In the formula, R1 and R2 are each alkyl, phenyl or its derivative, R3 is alkylene, phenylene or its derivative, R4 is H or methyl group. And, the titled toner contains 0.01-20wt% of the fatty acid (derivative) which is slightly soluble in water, preferably, a fatty acid, a polyvalent metal salt of the fatty acid, or the fatty acid ester (such as beef tallow).

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a positively charged toner used in electrophotography and electrostatic recording.

Conventionally, as an electrophotographic method, U.S. Patent No. 2,297.69
Although a number of methods are known, such as those described in Japanese Patent Publication No. 42-23910 and Japanese Patent Publication No. 43-24748, generally a photoconductive substance is used and a photoreceptor is coated on a photoreceptor by various means. An electrical latent image is formed, then the latent image is developed using toner, and if necessary, the toner image is transferred to a transfer material such as paper, and then fixed by heat, pressure, solvent vapor, etc. to form a copy. It's something you get. Further, when a step of transferring a toner image is included, a step for removing residual toner is usually provided.

Development methods for visualizing electrical latent images using toner include, for example, the magnetic brush method described in U.S. Pat. No. 2,874,063, and the magnetic brush method described in U.S. Pat. Cascade development method and 2.22'l, 7
Powder method described in No. 76 specification, U.S. Patent No. 3
, 909.258, which uses conductive magnetic toner, is known.

As toners applied to these developing methods, fine powders in which dyes and pigments are dispersed in natural or synthetic resins have conventionally been used. For example, particles obtained by dispersing a colorant in a binder resin such as polystyrene and pulverizing the particles to about 1 to 30 μm are used as toner. As the magnetic toner, one containing magnetic particles such as magnetite is used. In the case of a system using a so-called two-component developer, the toner is usually mixed with carrier particles such as glass beads and iron powder.

Conventionally, nigrosine dyes have been used as a typical charge control agent for positively charging toner. When a toner using a nigrosine dye as a charge control agent is used, there is a large variation in the amount of charge applied to the toner, and when a nigrosine dye is used as a charge control agent, the resulting image has a fog in the background. growing. This variation in the amount of charge is amplified by the temperature and humidity of the environment in which it is used, and the density of the image obtained with continuous use changes greatly, resulting in a significant drop in the quality level of the image. Furthermore, when a nigrosine dye is used as a charge control agent, the toner has poor flow characteristics, and after the toner image is transferred to a transfer material such as paper, the remaining toner is removed during the cleaning process to remove the remaining toner on the photoreceptor. Removal is likely to be poor. In particular, when the photoreceptor has relatively low hardness, such as when it is made of an organic photoconductive material, damage to the photoreceptor is significant.

Furthermore, if the photoconductor cleaning process is performed using a method in which a cleaning member is brought into contact with the surface of the photoconductor, such as a blade cleaning method suitable for high-speed cleaning or a fur brush cleaning method, this cleaning defect may become noticeable. appear.

Furthermore, since nigrosine dyes have a dark black color,
The problem is that it is difficult to use with color toners other than black.

Therefore, the object of the present invention is to
The object of the present invention is to provide a positively charged toner that always has good and stable charging and fluidity characteristics, has high image density, is clear, and has little fog.

Still another object of the present invention is to provide a positively charged toner that is easily removed from the surface of a photoreceptor in a cleaning process regardless of environmental conditions.

Another further object of the present invention is to provide a positively charged toner in which colors other than black are possible.

An object of the present invention is to provide a positively charged toner comprising at least a positively charged styrenic resin, a substantially electrostatically neutral resin, and a colorant, in which the styrenic resin contains styrene or its replacement product and nitrogen. acrylic acid alkyl ester or methacrylic acid alkyl ester not containing the formula (1
), and the unit represented by formula (1) is 0.
It is a styrene resin containing 1 to 50 wt% of N.
R30C-C=CH2(1) / I R2R4 (wherein, R1 and R2 represent an alkyl group or a phenyl group or a substituted product thereof, R3 represents an alkylene group or a phenylene group or a substituted product thereof, and R4 represents H
Or represents a methyl group. ) This is achieved by a positively charged toner containing 0.01 to 20 wt % of a poorly water-soluble fatty acid or its conductor based on the total binder resin.

Here, the substantially electrostatically neutral resin refers to the positive -T
IF conductive styrene resin triboelectric charging is performed at T1 (μc/g
), the triboelectric charge amount T2 (μc
/g) refers to a resin that satisfies the formula IT21≦-ITl 1.

In a developing method using toner and carrier, the interaction between the toner and carrier is extremely important.

That is, in order for the toner to be charged uniformly, the frictional charging between the toner and the carrier must be fast and the amount must be large to some extent. However, if the amount is too large, it will be difficult to remove the carrier from the carrier during development, resulting in a decrease in image density. In addition, even if the top toner appears to be uniformly charged, microscopically there are variations in the amount of frictional charge and there are toners that are leaking, so slight changes in the environment can cause soil blurring. Increased toner scattering may occur.

That is, the present invention has been made as a result of intensive research to solve the above problems, and when a toner that satisfies the above conditions is used,
They found that it gave good results.

That is, by locally increasing the triboelectric charging ability of the standard positively charging resin by adding an organic acid such as a fatty acid or its derivative, the charging ability due to contact friction with the carrier is improved, and at the same time, it is substantially possible to It is considered that by diluting the entire material by adding a resin and preventing the retention of an excessive amount of charge, it is possible to maintain stabilization and balance of chargeability particularly against environmental fluctuations.

Further, with this configuration, it is possible to appropriately adjust the hardness and brittleness of the toner, so it is extremely easy to improve durability and prevent damage to the surface of the photoreceptor and staining.

The styrene resin, which is an essential component of the positively charged toner of the present invention, contains 0.1 to 50% of the monomer represented by formula (1).
It is preferable that the content is wt%, more preferably 1
It is preferable to contain ~20 wt%.

Examples of the monomer of formula (1) include acrylate derivatives such as dimethylamine ethyl acrylate, diethylaminoethyl acrylate, dibutylaminoethyl acrylate, 'N-ethyl-N-phenylaminoethyl acrylate, and dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, and dibutylaminoethyl acrylate. Methacrylate derivatives such as ethyl methacrylate and N-ethyl-N-phenylaminoethyl acrylate can be used.

Furthermore, as the polymerization initiator for the styrene resin, which is an essential component, an azo initiator represented by formula (2) is preferable.

CN CN In addition, R1-4 are CH3, CH2CH3.

-CH2CH2CH3, CH(CH3)2.

CH2CH2CH2CH3, CH(CH3)CH2CH
3, CH2CH(CH3) 2 .

-C(CH3) 3. CH2CH2CH2CH2
CH3, CH2CH2CH2CH2CH2CH3, -C
H2CH(CH2CH3)CH2CH2CH2CH3,
It is preferable to select one or more types from <→.

In particular, 50 wt styrene-acrylic comonomer
% or more is preferable. Examples of styrenic monomers include styrene, vinyltoluene, α-methylstyrene, etc., and examples of acrylic monomers include acrylic acid and esters of acrylic acid such as methyl ester, ethyl ester, propyl ester, butyl ester, and 2-ethylhexyl ester. , methacrylic acid, and esters such as methyl ester, ethyl ester, propyl ester, butyl ester, and 2-ethylhexyl ester of methacrylic acid.

The ratio of styrene monomer to acrylic monomer is 1 styrene monomer to 1 acrylic monomer.
It is preferable to use ~50 wt%.

Particularly preferred among these is a copolymer consisting of at least a styrene monomer, an acrylic acid or methacrylic acid ester whose Tg of the homopolymer is approximately 30° C. or less, and the aminoacrylic monomer.

The above-mentioned styrene resin may include styrene, acrylic monomers, and vinyl monomers other than the monomer represented by formula (1), and conventionally widely known monomers can be used.

The mechanical and thermal properties of styrene resin include crushability,
Considering durability, stability, storage stability, etc., the melt index is 0 (at a temperature of 125℃ and a load of 21608).
．． 1-1o (g/l.

), glass inversion point (rg) so ~ 80°C, Izots 7 value 10 (kg-cm/am) or less, more preferably 5 (kg-cm/am) or less. is preferred.

Since the positively chargeable resin serves as a reference for the positive f-electrification of the toner, it is preferable that the positively chargeable resin is contained in an amount of 15% by weight or more of the binder resin in the toner.

As described above, the resin used in the present invention, which can be considered to be substantially neutral, has a triboelectric charge amount T2 that satisfies the condition of the formula % formula % with respect to the triboelectric charge amount T1 of the positive g-electric styrene resin. things are used.

Generally, polystyrene, poly-p-chlorostyrene,
I of styrene and its substituted products such as polyvinyltoluene
L polymer; styrene-P-chlorostyrene copolymer, styrene-propylene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-methyl acrylate copolymer, styrene-acrylic acid Ethyl copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, Styrene-α-methyl chloromethacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinylethyl ether copolymer, styrene-vinylethyl ketone copolymer, styrene-butadiene copolymer Polymer, styrene
Styrenic copolymers such as isoprene copolymer, styrene-acrylonitrile-indene copolymer, styrene-maleic acid copolymer, and styrene-maleic acid ester copolymer; polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, polyester, polyurethane,
Polyamide, epoxy resin, polyvinyl butyral, polyacrylic acid resin, rosin, modified rosin, terpene resin, phenol resin, aliphatic or alicyclic hydrocarbon resin, aromatic petroleum resin, chlorinated paraffin, paraffin wax, etc. alone or Mix and use. Among these, polystyrene, styrene-acrylic copolymer, styrene-butadiene copolymer, epoxy resin, polyester resin, etc. are preferred. The content of the above neutral resin is positive 4+F7
The amount can be adjusted appropriately depending on the type and type of L-based styrene resin and fatty acid, but generally it is 5 to 85% of the total binder resin.
It is preferable that If it is less than this, the dilution effect as a neutral resin will be insufficient, and if it is more than this, the positive chargeability of the toner will be canceled out.

It is also possible to use other conventionally known resins and polymers as binder resins for toners.

Furthermore, the poorly water-soluble fatty acids or their derivatives used in the present invention include fatty acids having 12 to 30 carbon atoms, metal soaps, esters, sulfuric esters, sulfonates, etc. derived from fatty acids, preferably at room temperature. Fatty acids are solid fatty acids with 12 to 30 carbon atoms or their metal salts or ester compounds, such as saturated fatty acids such as lauric acid, palmitic acid, stearic acid, and naphthenic acid, or unsaturated fatty acids such as oleic acid and linoleic acid. It is used alone or in mixtures with salts or in ester compounds with alcohols. More preferably, balmitic acid, stearic acid, oleic acid, naphthenic acid and/or their polyvalent metal salts or esters with glycerin are used alone or in combination of two or more.

In addition, poorly water-soluble in the present invention refers to deionized water 1010
Refers to a substance having a solubility of 1 g or less per 00:L at room temperature.

Fatty acid or fatty acid layer conductor is styrenic positive: iii
：Means for uniformly dispersing in an electrically charged resin and a neutral resin; Means for uniformly dispersing in a styrene-based positively chargeable resin and then mixing with a neutral resin; Styrene after uniformly dispersing in a neutral resin Although it is possible to disperse it in the binder resin by mixing it with the positive charging resin, it is preferable to disperse it in the neutral resin in advance. The reason for this is thought to be that the best dispersion of the fatty acid or its conductor, which serves to strengthen the toner's chargeability, and the neutral resin, which serves to weaken the toner's chargeability, leads to good charge control of the toner. It will be done.

Methods for dispersing fatty acids or their 8 conductors into neutral resins include simultaneous kneading, mixing each fine particle into powder, and dispersing fatty acids or their visiting conductors in a solvent during polymerization of the neutral resin. When the neutral resin is produced by emulsion polymerization, a method of dispersing the resin also as an emulsifier is used.

The amount of the fatty acid layer conductor is 0.01 to 0.01 to the total binder resin.
It is preferable to contain 20 wt% (preferably 0.1 to 5 parts).

If the fatty acid or fatty acid layer conductor content is within the above range, the compatible dispersion of the toner components less than 0.01 wt % is insufficient, resulting in agglomeration of the toner.

Reduced fluidity, toner friction 1! : Phenomenon such as decrease in electric property and charge controllability occur. Also, if it is more than 20wt%,
Although the components of the toner are sufficiently compatible and dispersed, under high humidity conditions, toner agglomeration and a decrease in density during durability occur.

The positively charged toner of the present invention contains 1 to 20 parts by weight (preferably 2 to 15 parts by weight) of a colorant based on 100 parts by weight of resin.
Or, in the case of a magnetic toner, it is preferable to add 10 to 200 parts by weight (preferably 20 to 100 parts by weight) of magnetic powder.

The magnetic powder used in the present invention includes powders of ferromagnetic elements and alloys and compounds containing these elements, such as magnetite, iron such as γ-Fe2O3° ferrite, alloys and compounds of cobalt, nickel, manganese, etc. There are some conventionally known magnetic materials such as ferromagnetic alloys. Especially magnetite etc. are blue or green tea, γ-
Fe2O3 type is suitable for yellow or red magnetic toner.

As the colorant that can be used in the toner of the present invention, inorganic pigments and organic dyes and pigments can be used as desired.
Although water-soluble dyes are not preferred because they are susceptible to wetting even after image fixation, they can be used for the purpose of improving timekeeping performance within a range that does not significantly deteriorate the characteristics of the developer of the present invention. The colorant is used in an amount of 0.1 to 20 parts by weight based on 100 parts by weight of the total resin.

Examples of the pigments used in the present invention include benzidine yellow, high-quality yellow, phthalocyanine blue, phthalocyanine green, and navy blue.

Ultramarine, Cobalt Blue, Quinacridone Toluidine Toner, Permanent Yellow, Palcan First Yellow, Permanent Orange, Palcan First Orange, Indanthrene Brilliant Orange, Permanent Red, Palcan First Pink, Brilliant Cardin. There are indanslen blue, naphthol green, etc.

In addition, as a dye, CI 12700. CI 186
90, C118736A, Cl26020°CI 12
150. CI 12715. CI 60725, Cl7
4350. Cl61565. ClIO345, Cl48
000. CI 11080. C111100, Cl62
015. Examples include Cl64500 and Cl62500, but those with good compatibility and dispersibility with the binder used are preferred.

Moreover, additives may be further added to the toner of the present invention, if necessary. Examples of such additives include lubricants such as polyvinylidene fluoride and polytetrafluoroethylene, fixing aids such as low molecular weight polyethylene, fluidity imparting agents and anti-caking agents such as colloidal silica, and the like. Cerium oxide is an abrasive.

As an image forming method in which the positively charged toner of the present invention can be used, an electrostatic image formed on an electrostatic image support by an electrostatic image forming method such as an electrophotographic method, an electrostatic recording method, or an electrostatic printing method is used. , developed with the developer described above. For example, in electrophotography, as shown in FIG. 2, a charging mechanism 2 such as a corona charger applies an electrostatic charge to the surface of a drum 1 made of a photoconductive photoreceptor that is rotated in the direction of the arrow. An optical image of the document is projected by the exposure mechanism 3 to form an electrostatic charge image, and this electrostatic charge image is developed into a toner image by the developing device 4 filled with the above-mentioned developer.

The developing method used here is a method depending on the characteristics of the developer, such as magnetic brush developing method, cascade developing method,
Method using conductive magnetic toner described in U.S. Pat. No. 3,909,258, JP-A-53-31136
A method using a high-resistance magnetic toner described in JP-A No. 54-42141, a method described in JP-A No. 55-18656, and a fur brush developing method.

These include powder claradone and impressionon.

The toner image thus formed is transferred onto a transfer material such as transfer paper. In the example shown in FIG. 2, the toner image is electrostatically transferred to the transfer paper synchronously conveyed along the transfer paper path p shown by the chain line by the action of the transfer discharge device 5. As the transfer means, various means such as pressure transfer and thermal transfer can be used. The transfer material with the toner image transferred is then conveyed to a fixing device and undergoes a fixing process using, for example, a contact heat fixing method using a heated pressure roller.
This forms a visible image.

On the other hand, the electrostatic image support that has undergone the transfer process is subjected to a cleaning process after being neutralized if necessary, and then subjected to the next image forming process. In the example shown in FIG. 2, the static charge on the drum 1 is eliminated by the action of the static eliminating discharger 6, and the toner particles remaining on the drum 1 are removed by the cleaning mechanism 7 using a cleaning blade in the figure. It is removed and cleaned.

Although the cleaning method here is arbitrary, it is preferable to use a blade cleaning method or a fur brush cleaning method that can reliably achieve the required cleaning, and can sufficiently cope with high-speed image formation. .

The blade cleaning method is a method in which cleaning is performed by installing a scraping blade so that its tip edge comes into contact with the surface of the electrostatic image support that is moved, and has a simple structure and does not require energy. . A blade cleaning method is preferred in combination with the toner of the present invention.

Here, a method for measuring the amount of triboelectric charge of a positively chargeable resin, a positively chargeable resin containing an organic acid, and a neutral resin will be described in detail with reference to the drawings.

First, each resin powder was measured using a Coulter Counter manufactured by Coulter Co., Ltd. to determine the number average particle size of 9 to 11 μm, the volume average particle size of 13 to 15 μm, and 6.35 μm.
The following is 20 weight 2% or less, and 20.2 μm or more is 15
The particles are adjusted so that they can be considered to have substantially the same particle size, which is less than or equal to 2.

Next, the amount of triboelectric charge of each sample is measured using the apparatus shown in FIG. First, in a metal measuring container 12 with a conductive screen 13 of 400 mesh (the size can be changed as appropriate so that it does not exceed the size of the tin particles) at the bottom, resin powder whose frictional 1F electric charge is to be measured and particles with a particle size of 200 to 300 are placed. Approximately 4 g of a mixture (developer) of amorphous iron powder (the same type is used for the three types of resins) in a weight ratio of 1:9 is placed on the surface between the meshes to create a metallic surface. Lid 1
Do 4. Weigh the entire weight of the measurement container 2 at this time W+
(g). Next, in the suction device 11 (at least the part in contact with the measurement container 2 is an insulator), suction is performed from the suction port 17, and the landscape control valve 16 is adjusted to lower the pressure of the vacuum gauge 15 to 70.
0mmHg. In this state, suction is applied sufficiently (for about 1 minute) to remove the resin powder. The potential of the electrometer 19 at this time is assumed to be (volt). Here, 18 is a capacitor, and the container is C (μF). In addition, the weight of the entire measurement container after suction is weighed and is defined as Wz (g). The triboelectric charge iT (μC/g) of this resin powder is calculated as shown in the following formula.

However, the measurement conditions are 23° C. and 50% RH.

Next, the present invention will be explained in more detail based on examples.

Note that the number of parts is by weight.

〔Example〕

Table 1 lists the styrene-based positively chargeable resin and neutral resin used, along with their triboelectric charge amounts.

All copies are from M Engineering Department.

Example 1 During polymerization of neutral resin III, neutral resin III component 100
1 part to 4 parts beef tallow (palmitic acid).

Stearic acid, glycerin ester of oleic acid) were mixed. 25 parts of this neutral resin containing beef tallow, 75 parts of positively charged styrene resin I, and 5 parts of phthalocyanine pigment were melt-kneaded, crushed, and classified to obtain a blue powder with an average particle size of 12 μm. 100 parts of this blue powder and 0.5 part of regular colloidal silica were mixed to prepare a toner.

NP manufactured by Canon, which was modified to form a negative electrostatic image by mixing 8 parts of this toner and 100 parts of iron powder carrier.
When FLFI brush development was carried out using a -5000 copying machine, an extremely good image was obtained. This image was equally good under high temperature and high humidity conditions as well as under low temperature and low humidity conditions, and the charge amount of the toner was extremely stable as shown in the table below.

Further, residual toner on the photoreceptor after transfer was successfully removed by either blade cleaning or fur brush cleaning.

Example 2 100 parts of neutral resin II and 2 parts of valmitic acid were melt-kneaded and crushed. 50 parts of this fatty acid-containing neutral resin and 50 parts of positively chargeable styrene resin I.

A toner was prepared by mixing 100 parts of a red powder obtained by melt-kneading, crushing, and classifying 4 parts of a monoazo red pigment and 1 part of positively chargeable colloidal silica.

When 10 parts of this toner and 100 parts of ferrite carrier were mixed and the same test as in Example 1 was conducted, similar good results were obtained.

Example 3 The same results as in Example 1 were obtained except that aluminum stearate was used instead of beef tallow.

Example 4 Neutral resin III was pulverized in advance, and the pulverized neutral resin II! 1 part of zinc naphthenate per 100 parts was mixed into particles using a Henshinyl mixer. The same good results as in Example 1 were obtained except that this mixed particle was used instead of the neutral resin containing beef tallow.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing a device for determining the amount of frictional charge according to the present invention. FIG. 2 shows 14 schematic explanatory diagrams of the configuration of an electrophotographic copying machine that carries out an electrophotographic process. 11 is a suction device, 12 is a measurement container, 13 is a conductive screen, 15 is a vacuum gauge, 16 is a full air control valve, 17 is a suction port, and 18 is a condenser. 1 -----1 drum, 2 -----1 belt TL mechanism, 3 -----1 exposure mechanism, 4 -----1 developing device, 5 -----1 for transfer Discharge device, 6 ------- Main discharge device, 7 ------- Cleaning mechanism,

Claims (2)

[Claims] (1) In a positively charged toner comprising at least a styrene resin, a substantially electrostatically neutral resin, and a colorant, the styrenic resin comprises styrene or a substitute thereof;
Containing a unit composed of a nitrogen-free acrylic acid alkyl ester or methacrylic acid alkyl ester and a monomer represented by formula (1),
It is a styrene resin containing 0.1 to 50 wt% of the unit represented by formula (1), and has mathematical formulas, chemical formulas, tables, etc. (I) [In the formula, R_1 and R_2 are an alkyl group, a phenyl group, or represents a substituent thereof, R_3 represents an alkylene group or a phenylene group or a substituent thereof, R
_4 represents H or a methyl group. ) 0.01 to 20% of poorly water-soluble fatty acids or derivatives thereof to the total binder resin.
A positively charged toner characterized by containing wt%. (2) The positively charged toner according to claim (1), wherein the fatty acid or its derivative is a fatty acid, a fatty acid polyvalent metal salt, or a fatty acid ester.