JPH0473661A - Fine particle toner for electrostatic charge image developing and production thereof - Google Patents

Abstract

PURPOSE:To improve fine line reproducibility, gradation characteristic, etc. by incorporating a polyester resin having a specific Izod impact value or below as the essential component of a binder component and forming the toner to a specific average grain size based on weight or below. CONSTITUTION:This toner contains the polyester resin having <=1.5kg.cm/cm<2> Izod impact value as the essential component of the binder component and the average grain size based on weight thereof is specified to <=5mum. There is the threshold of the average grain size by the kinds of the binder resins in the production of the toner by grinding. The resins having the Izod impact value larger than 1.5kg.cm/cm<2> are hardly ground and since the softening temp. of many of such resins is low, the resins are reflocculated by the generated heat and the toners of the larger grain sizes are eventually formed even if the grinding energy is increased. The fine particle toner of <=5mum average grain size is obtainable even from the ground matter of the large average grain size by subjecting such matter to a classification treatment, but the yield of the toner is extremely low and such is entirely unpracticable. The fine line reproducibility, gradation characteristic, etc., are improved in this way.

Description

[Detailed Description of the Invention] [Objective of the Invention] (Industrial Field of Application) The present invention is directed to improving fine line reproducibility, gradation, etc. for developing electrostatic images in electrophotography, electrostatic recording, etc. The present invention relates to a fine particle toner with excellent properties and a method for producing the same.

(Prior art) Currently, powder toner used in dry development methods is used as a toner for developing electrostatic images in electrophotography, electrostatic recording, etc., which are widely used in copying machines, printers, etc. It's mainstream. There are two types of powder toner: insulating toner and conductive toner, both of which work by selectively adhering to an electrostatic charge image using electrostatic force and making it visible, and by fixing the image onto the recording medium using heat, etc. It has a function. Therefore, toners are required to faithfully reproduce electrostatic latent images, but powder toners have the following problems, and the reality is that the quality of electrostatic latent images is considerably impaired.

A common method for obtaining powdered toner is a pulverization method in which dyes, pigments, magnetic powders, etc. are melted in a binder resin, dispersed by cross-crossing, mechanically pulverized after cooling, and then classified. However, the toner obtained by this pulverization method consumes a huge amount of electrical energy, and in terms of profitability, the weight-based average particle size is 9 μm (hereinafter referred to as the average particle size).
However, even if profitability is not taken into consideration, the thickness can only be reduced to about 7 μm. However, with particle diameters on this level, it is not possible to faithfully reproduce a high-definition electrostatic latent image, and there is a demand for finer toner particles.

For this reason, various methods for producing powder toner other than pulverized toner have been studied, and known methods include spray drying, emulsion polymerization, and suspension polymerization.

However, since the spray drying method produces spherical toner, it is difficult to obtain uniform charge, good fluidity, or fine toner particles. There are disadvantages such as the need for explosion-proof equipment and recovery of solvents, the consumption of enormous amounts of thermal energy during drying, and limitations on materials when imparting sufficient physical properties to the toner. However, it is difficult to obtain toner with sufficient characteristics using this method alone.

In addition, in the method of producing spherical toner particles in water by emulsion polymerization method or suspension polymerization method, is it easy to obtain fine toner particles? It has been pointed out that the stabilizer remains on the surface of the toner particles, and this adsorbs moisture in the air, lowering the electrical resistance of the toner, making it difficult to copy on plain paper, and making the charge on the toner surface uneven. However, this point is a problem and it has not yet been put into practical use.

(Problems to be Solved by the Invention) The present invention provides a fine particle toner with excellent fine line reproducibility, gradation, etc., and a manufacturing method that makes it possible to economically obtain the fine particle toner.

[Structure of the invention]

(Means for Solving the Problem) The present invention has an Izod impact value of 1.5 kg-an/a.
A fine particle toner for developing electrostatic charge images containing a polyester resin of 1 or less as the main binder component and having a weight-based average particle diameter of 5 μm or less and an Izot impact value of 1.
A binder component mainly composed of a polyester resin of 5 kg-cm/cd or less, a coloring agent component, and other additive components as needed are melt-kneaded, and a crusher that uses mechanical impact force is used to melt and knead the binder component, which is mainly composed of a polyester resin, and then melt and knead the binder component, which is mainly composed of a polyester resin of 5 kg-cm/cd or less. The present invention relates to a method for producing a fine particle toner for developing electrostatic images, which is characterized in that a toner having a particle size of 5 μm or less is obtained.

Izod impact value is a type of material test that uses impact load to determine the degree of toughness and brittleness of a material. Regarding the measurement principle and method of Izotsu impact value, please refer to J.
Compliant with IS K7110. In this test, a bending test piece of a certain shape is destroyed by a single impact, and the impact strength of the material is determined by the amount of energy absorbed by the test piece. Currently, two types of such tests are used: Charpy type and Izod type, but they are basically the same test, and either type may be used as long as the unit of impact value is converted. To express the test result, the quotient of the absorbed energy of the test piece divided by the cross-sectional area of the test piece is expressed as kg-cm/ad.
It is expressed in units of , and this is taken as the Izod impact value. In addition, the Izotsu impact value test piece in the present invention is JIS K
We will use the No. 2 test piece described in 7110 without a notch.

The polyester resin used in the present invention has an Izod impact value of 1.5 kg-cm/ci or less. Such a polyester resin is formed by condensation polymerization of a divalent or higher organic acid component and a divalent or higher alcohol component as main components. Examples of acid components include adipic acid, sebacic acid, azelaic acid,
Aromatics such as glutaric acid, terephthalic acid, isophthalic acid,
Trivalent carboxylic acids such as aliphatic dicarboxylic acids, trimellitic acid, and pyromellitic acid, and alcohol components such as divalent carboxylic acids such as ethylene glycol, propylene glycol, butylene gelicol, pentyl glycol, hexyl glycol, neopentyl glycol, and diethylene glycol. Examples include polyhydric alcohols such as alcohol, trimethylolpropane, glycerin, pentaerythritol, and sorbitol. In addition, a polyfunctional epoxy resin, a glycidyl ester, and a monovalent acid or alcohol can be used as necessary. A specific example of a preferred polyester resin that can be used in the present invention is rosin-modified polyester.

The rosin-modified polyester is one in which, for example, a rosin glycidyl ester obtained by reacting a disproportionated rosin and epichlorohydrin is used as a monomer component of the polyester resin. In general, polyester resins have flexibility, and it is easy to obtain Izot impact values greater than 1.5 kg-am/ci, but by using such modified monomers or modifying polyester resins, it is possible to A polyester resin with a low impact value can be obtained. The weight average molecular weight of the polyester resin is preferably 20,000 to 8,000.

Further, the polyester resin preferably accounts for 70% by weight or more of the total toner binder component, and more preferably 90% by weight or more. If it is less than this, sufficient pulverizing performance may not be obtained depending on the properties of other binder components.

As a method for producing the fine particle toner of the present invention, a binder component containing the polyester resin of the present invention as a main component, a colorant component, and other necessary components are mixed in a twin-screw extrusion kneader,
After hot melting and kneading using a mixer such as a roll mill or a pressure kneader, the mixture is pulverized using a pulverizer that uses mechanical impact force. The most preferable crusher that uses mechanical impact force to obtain the toner of the present invention is a jet mill that uses the pressure of compressed air, such as an air suction type, an air flow collision type, or a collision plate collision type. High-speed rotating mills that utilize impact, shearing, and grinding forces, such as swing hammer mills, bottle mills, turbo-type mills, and centrifugal classification mills, are also suitable.

The particle size distribution of the toner obtained by pulverization is rosin-lambda.
distribution or lognormal distribution. The particle size distribution of the toner obtained by the present invention is 1 μm or less on a weight basis or 40% of the total.
5 μm or more and 30% or less, preferably 1 μm or less is 20% or less of the total, and 5 μm or more is 5% or less. When the volume is 5 μm or more and 30% or more, fine line reproducibility decreases, and 1 μm or less is 40% or more.
% or more is not preferable because the fluidity of the toner decreases.

As a binder component, in addition to the polyester resin of the present invention, in order to impart fixing properties, anti-offset properties, etc. as necessary, a binder component having an Izot impact value of 5 kg-cm is used.
Various thermoplastic resins and waxes having a value larger than /Ci may also be used.

In addition, as colorants, dyes and pigments conventionally used in toner materials are used, and carphone black is a typical example, but zinc, yellow iron oxide, /'%ncyel, disazo yellow, and quinoline yellow are used as colorants. Permanent Yellow Permanent Red, Red Red, Resole Red, Watch Palm Red Ca Salt, Watch Palm Red Mn
Salt, Pyrazolone Red, Lakerad C, Lakerad D,
Brilliant Carmine 6B, Brilliant Carmine 3B
Pigments or oil-soluble dyes such as , navy blue, phthalocyanine blue, metal-free phthalocyanine, and titanium oxide can be used.

Other necessary components include, for example, a charge control agent and magnetic powder. As the charge control agent, oil-soluble dyes, metal-containing dyes, acid dyes, naphthenic acid metal salts, fatty acid metal soaps, etc. are used.

As the magnetic powder, alloys or compounds of iron such as various ferrites, magnetites, and hematites, zinc, cobalt, di-ykel, manganese, etc. can be used.

These magnetic powders are preferably spherical, cubic, octahedral, acicular, oblate, etc., and have an average particle size of 0.1 to 0.5 microns, and are suitable for good dispersion in the resin. Surface treatment, for example, hydrophobic treatment with fatty acids, etc.
It may also be subjected to silane coupling agent treatment, resin coating treatment, etc.

In addition, hydrophobic silica is used for the purpose of improving fluidity, carborundum, alumina, cerium oxide, etc. are used as abrasives, and metal soap powder, polyphenyl vinylidene nitride, etc. are used as lubricants.
Fine particles such as polytetrafluoroethylene can also be used.

(Operations and effects of the invention) The present invention has an Izot impact value of 1.5 kg・cm/cm.
2 or less polyester resin is produced by a pulverizer that utilizes mechanical impact force. In the production of toner by such pulverization, there is a limit to the average particle size depending on the type of binder resin. Resins with an Izot impact value greater than 1.5 kg-cm/cffl are difficult to crush, and the softening temperature of many resins is low, so even if the crushing energy is increased, the generated heat will cause reaggregation. This is because the particle size becomes large. Although it is possible to obtain a fine particle toner having an average particle size of 5 μm or less by subjecting a pulverized product having a large average particle size to a classification process, the yield of the toner decreases significantly and is not practical at all.

According to the present invention, it is possible to economically produce toner particles with an average particle diameter of 5 μm or less, and it is possible to obtain images with extremely excellent fine line reproducibility, gradation, etc. compared to conventional printed matter. Became.

(Example) Examples will be explained below. The middle part of the example shows parts by weight.

Example 1 Zero gin modified polyester resin (product name KR-445,
Manufactured by Arayo Kagaku Kogyo, Mw=17000, Izod impact value=1.4 kgan/cnf)
92 parts carbon black (trade name: #44, manufactured by Mitsubishi Chemical Industries) 5 parts charge control agent (trade name Nispiron Black TRH, manufactured by Hodogaya Chemical Industry ■) 3 parts After premixing the raw materials according to the above recipe, kneader - After melting and kneading and cooling, jet mill (product name: Nilaposit)
The powder was crushed using Nippon Pneumatic Kogyo (manufactured by Nippon Pneumatic Industries). The weight-based average particle diameter of the obtained pulverized product was measured using a Coulter Counter (trade name: TA-II, manufactured by Coulter Electric Co., Ltd.). In addition, the Izotsu impact value is calculated using the Izotsu Charpy impact tester (product name: CIT-4).
0I (C), manufactured by Toga Seimitsu Kogyo ■).

When the jet mill was set to conditions that gave the best pulverization efficiency within an economical range, a toner with a weight-based average particle diameter of 4.1 μm was obtained. The setting conditions of the jet mill are as follows.

Raw material foot amount: 6g/min Collision plate = 90° Louver: Small air pressure crab 5.5kg/ClIr Adjustment ring: 8+n+oX 3 Distance ring: 1 (lnmX 3) The obtained toner is cut into ultra-fine powder using a wind classifier to make particles of 1 μm or less account for about 8% of the total on a volume basis. 0.7 parts of colloidal silica was mixed with 100 parts of the obtained toner. Further, a developer was prepared with a toner concentration of 296,
When a printing test was conducted using a commercially available copying machine, images with extremely high gradation and high resolution were obtained.

Example 2 In order to improve the fixation of printed matter, a toner was manufactured in the same manner as in Example 1 using the following formulation with the addition of a wax component (
94.6% of the total inner component of the thermoplastic resin
).

Polyester resin (same as Example 1) 88 parts Polyethylene wax (trade name, PE-130, manufactured by Hoechst) 4 parts Carbon black (same as Example 1) 5 parts Charge control agent (same as Example 1) 3 The toner particles thus obtained had an average particle size of 4.5 μm.

Comparative Example 1 In the formulation of Example 1, the polyester resin was replaced with Polyester-HP301 (manufactured by Nippon Gosei Kagaku Kogyo ■, Mw = 43
0000, Izotsu impact value = 3.5 kgcm/c
o? ) was performed in the same manner as in Example 1 to obtain a toner. The weight-based average particle diameter of this toner was 7.5 μm.

Next, the average particle diameter was measured by changing the settings of the jet mill. The results are shown below.

Comparative Example 2 An example in which the polyester resin in the formulation of Example 1 was changed to Tuft:/NE-382 (manufactured by Kao ■, Mw=15000, Izod impact value=1.8 kgcm/cd)! A similar test was conducted. The obtained toner had a weight-based average particle diameter of 5.2 μm, and only a toner with a large average particle diameter was obtained.

Claims (1)

[Scope of Claims] 1. Electrostatic image development containing a polyester resin having an Izod impact value of 1.5 kg·cm/cm^2 or less as a main component of the binder component and having a weight-based average particle diameter of 5 μm or less. fine particle toner. 2. Melt and knead a binder component mainly composed of a polyester resin with an Izod impact value of 1.5 kg/cm/cm^2 or less, a colorant component, and other additive components as necessary, and apply mechanical impact force. 1. A method for producing a fine particle toner for developing electrostatic images, characterized in that a toner having a weight-based average particle diameter of 5 μm or less is obtained using a pulverizer using a pulverizer.