JPH0497364A - Electrostatic charge image developing toner - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for producing a toner for developing electrostatic images in the field of electrophotography.

<Prior art> As conventional electrophotographic methods, US Pat.
Various methods are described in Japanese Patent Application No. 48, etc., but in general, a photoconductive substance is used to form an electrical latent image on a photoreceptor by various means, and then the latent image is developed with toner. After a powder image is transferred to paper or the like according to the requirements, it is fixed by heating, pressure, or solvent vapor.

In addition, in recent years, the electrostatic latent image of the original is formed by exposing it to spectral light, and this is developed with color toner of each color to obtain a colored copy image, or the copy images of each color are superimposed to form a full-color copy image. Color copying methods for obtaining images have also been put into practical use.

Toners are made by dispersing various colorants (dyes and pigments such as carbon black) and charge control agents in a binder resin such as styrene resin, and then finely pulverizing the particles to about 1 to 30 μm. , such toners are used in admixture with carrier materials such as glass peas, iron powder or fur.

<Problems to be Solved by the Invention> The toners conventionally used have the following problems.

1) Since it cannot be fixed at low temperatures, it consumes a lot of energy and is not suitable for high-speed fixing.

2) A high-temperature offset phenomenon is likely to occur during hot roll fixing, placing a heavy burden on the fixing device.

3) Adhesion or migration to the soft vinyl chloride sheet is observed, which tends to cause image stains and defects.

4) It has poor transparency and gloss after fixing and cannot be used for full color toner applications.

5. Due to low mechanical durability, it cannot be used for a long period of time.

In order to solve these problems, many studies have been made in terms of toner materials and formulations. Polyester resins are generally considered to be more advantageous than styrene resins in terms of vinyl chloride adhesion and low-temperature fixability. It is also used as a resin for full-color toners because it has excellent transparency. However, some problems remain,
The reality is that nothing that is comprehensively satisfactory has yet been submitted. Therefore, prompt improvements have been desired.

<Means for Solving the Problems> The present invention was made based on the above-mentioned circumstances, and its purpose is to provide a high-performance electrostatic developing toner in which the above-mentioned problems are solved. be.

Therefore, as a result of intensive studies to achieve the above objective, the present inventors have found that the above objective can be achieved by using a resin composition in which phenoxy resin is uniformly dissolved in polyester resin using a specific method. We have discovered this and arrived at the present invention.

That is, the gist of the present invention is to provide a toner for developing electrostatic images containing a colorant and a resin, in which the main component of the resin is a polyester resin and a phenoxy resin mixed and melted at a temperature equal to or higher than the softening point of the phenoxy resin. The present invention relates to a toner for developing an electrostatic image, characterized by being a resin composition comprising:

<For production> The present invention will be explained in detail below.

In the present invention, a binder is prepared by uniformly melting and mixing a phenoxy resin with a polyester resin, and a coloring agent and other necessary components are added to the binder to form a toner.

Among these, the polyester resin is not limited in any way, and all known polyester resins can be used, but among them, particularly preferred for the present invention are Mw, which is a measure of the spread of the molecular weight distribution of the resin.
Polyester resins having a value of /Mn of 3.0 or more may be mentioned.

In order to make the value of M w / M n of polyester resin 3.0 or more, it is necessary to use a method of melting or mixing several resins with different molecular weights in a molten state, or when forming a polymer from monomer components. Various methods can be employed, such as a method of applying crosslinking to a certain degree. Among these manufacturing methods, the degree of crosslinking is suppressed within a low range and M w / M n
The method of adjusting is the most suitable method for the present invention,
This is accomplished by adding a crosslinking heptamer to the polymerization reaction system.

By setting Mw/Mn to 3.0 or more, it is possible to maintain low-temperature fixing properties and to significantly improve offset resistance at high temperatures during hot roll fixing.

The polyester resin according to the present invention has a monomer composition consisting of a polyhydric alcohol and a polybasic acid, and if necessary, at least one of the polyhydric alcohol and the polybasic acid contains a polyfunctional component having a valence of 3 or more. Obtained by polymerizing substances.

In the above, 2 used for synthesis of polyester resin
Examples of alcohols include ethylene glycol,
diethylene glycol, triethylene glycol, 1,
Diols such as 2-propylene glycol, 3-propylene glycol, 1,4-butanediol, neopentyl glycol, 1,4-butynediol, 1.5-bentanediol, 1°6-hexanediol, bisphenol A , hydrogenated bisphenol A, bisphenol A alkylene oxide adducts such as polyoxyethylenated bisphenol A and polyoxypropylenated bisphenol A, and others. Among these monomers, it is particularly preferable to use a disphenol A alkylene oxide adduct as the main monomer, and especially an adduct having an average number of alkylene oxides added of 2 to 7 per molecule is more preferable.

Examples of trihydric or higher polyhydric alcohols involved in crosslinking polyester include sorbitol, 12.3.6-hexanetetrol, 4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, sucrose, 12. .4-butanetriol, l,2
．． 5-pentanetriol, glycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane, 1,3.5-trihydroxymethylbenzene,
Others can be mentioned.

On the other hand, examples of polybasic acids include maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, succinic acid, adipic acid, cehatic acid, azelaic acid, and malonic acid. Examples include acids, anhydrides of these acids, lower alkyl esters, and other divalent organic acids.

Examples of trivalent or higher polybasic acids involved in crosslinking polyester include 1,2,4-benzenetricarboxylic acid,
1,2.5-benzenetricarboxylic acid, ■, 2.4-cyclohexanetricarboxylic acid, 2,5.7-naphthalenetricarboxylic acid, 1°2.4-naphthalenetricarboxylic acid, 1,2.5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-methylenecarboxypropane, tetra(methylenecarboxy)methane, 12.
7.8-Octane tetracarboxylic acid, anhydrides thereof, and others.

In order to make M w / M n 3.0 or more, the component of trihydric or higher polyhydric alcohol and/or polybasic acid that participates in the crosslinking of polyester is the alcohol component or acid component as a structural unit in the polymer. It is preferably contained in a proportion of 3 to 80 mo1% in each component. If it is less than 3m01%, the degree of crosslinking is insufficient and M
It is difficult to obtain polyester with w/Mn of 3.0 or more, and therefore it is difficult to prevent high temperature offset during fixing. Further, if the amount used is 80mo1% or more, the gel content, which is a solvent-insoluble matter, increases extremely, which is undesirable because the fixing performance deteriorates.

These polyester resins have a softening point of 9
If the temperature is lower than 0°C, blocking may easily occur, resulting in poor storage stability or problems in mechanical durability. Furthermore, if the softening point exceeds 150°C, the fixing performance may deteriorate and problems may occur in transparency and gloss. The temperature is preferably within the range of 100 to 130°C, and more preferably within the range of 100 to 130°C.

Furthermore, in general, when a polyester resin has a high acid value, charging stability at high temperatures tends to deteriorate.
0KOHmg/g or less, more preferably 5KOHmg/g
It is best to adjust it so that it becomes g.

Methods for adjusting the acid value to a low level include, for example, synthesis using a lower alkyl esterified acid monomer component by transesterification, or adding a basic component such as an amino group-containing glycol to the composition. Examples include a method of neutralizing the remaining acid groups by doing so, but the present invention is not limited to these methods, and any known method can be employed.

Note that the polyester resin in the present invention can be synthesized by a commonly known method. Specifically, the reaction temperature (
Conditions such as 170°C to 250°C) and reaction pressure (5mmHg to normal pressure) are determined depending on the reactivity of the monomer, etc.
The reaction may be terminated when predetermined physical properties are obtained.

Phenoxy resin is a high molecular weight polyhydroxy polyether synthesized from bisphenol A and epichlorohydrin, and has the following chemical structural formula (1). In order to improve mechanical durability such as toughness, the temperature is preferably 150°C or higher, more preferably 180°C or higher.

Specific examples of such phenoxy resins include Bakelite PKHJ, PKHH, and PKHC (trade names, manufactured by Union Carbide).

The mixing ratio of polyester resin and phenoxy resin in the present invention is preferably 97-60:3-40 by weight. If the amount of phenoxy resin is less than this range, the mechanical durability may be low and it may not be possible to use it stably for a long period of time. Furthermore, when the amount of phenoxy resin is large, the softening point increases, making it difficult to fix at low temperatures, and transparency and gloss tend to deteriorate.

In the present invention, when producing toner, these phenoxy resins may be heated and kneaded with other resins at a temperature higher than their softening point to melt them, but in that case, it is difficult to melt them completely uniformly, and it is difficult to melt them uniformly. Even if it were possible, the energy and effort required to do so would be extremely large.

In the present invention, when the polymerization reaction of the polyester resin is completed, the heating state is maintained without being left to cool to room temperature, and more preferably, the temperature is maintained at a temperature equal to or higher than the softening point of the phenoxy resin so that reheating is not necessary. It is preferable to use a resin composition in which the phenoxy resin is added while being maintained at all times, mixed and melted at a temperature equal to or higher than the softening point of the phenoxy resin, and then taken out.

In this case, the phenoxy resin can be easily and uniformly melted into the polyester resin by simply adding the phenoxy resin to the reaction system using the reaction temperature during polyester resin production.

Considering the softening point of the phenoxy resin, the melting temperature at this time is preferably 180'C or higher, more preferably 2.
It is preferable that the temperature is 00°C or higher.

Colorants that can be used in the present invention include carbon blank, lamp black, iron black, ultramarine blue, aniline blue, phthalocyanine blue, phthalocyanine green, Hansa Yellow G, rhodamine dyes and pigments, chrome yellow, quinacridone, benzidine yellow, rose bengal, Any conventionally known dyes and pigments such as triallylmethane dyes, monoazo and disazo dyes and pigments can be used alone or in combination. These colorants are preferably used in an amount of 0.5 to 20 parts by weight, more preferably 2 to IO parts by weight, based on 100 parts by weight of the resin.

In the present invention, various constituent components may be included in addition to the above resin components and colorants.

First, as the resin for toner, in addition to the resin composition according to the present invention described above, it may be considered to add other resins when producing the toner, if necessary.

Examples of this type of resin include various known resins such as epoxy resins, styrene/acrylic copolymer resins, styrene/aminoacrylic copolymer resins, and silicone resins.

Further, magnetic fine powder can be included in the toner for the purpose of improving the developing mechanism or the image quality. Examples of the magnetic powder include alloys or compounds containing elements exhibiting ferromagnetism, such as ferrite and magnetite. The following amounts can be dispersed and used.

All known charge control agents can be used. For example, for positively charging properties, there are nigrosine dyes, quaternary ammonium salts, styrene/aminoacrylate copolymers, polyamine resins, etc. For negatively charging properties, there are azo dyes containing metals such as chromium, cobalt, aluminum, etc., and metals such as alkyl salicylic acids. Salt, etc. are known. The amount used is preferably 0.1 to 10 parts by weight, more preferably 0.5 to 5 parts by weight, per 100 parts by weight of the resin. The charge control agent is
It may be used either by being mixed into the resin or by being attached to the surface of the toner particles.

In addition, it is also possible to add various auxiliary agents such as plasticizers and release agents to the toner for the purpose of adjusting thermal properties, physical properties, etc. Examples include low molecular weight polyolefin for improving offset properties and colloidal silica for improving fluidity.

The amount added is suitably 0.1 to 10 parts by weight per 100 parts by weight of the resin.

A general method for producing the toner of the present invention is as follows.

■Disperse resin, colorant, charge control agent, etc. uniformly using a Henschel mixer.

(2) Melt and knead the dispersion using a kneader, extruder, roll mill, etc.

■After coarsely pulverizing the kneaded material with a hammer mill, cutter mill, etc., finely pulverizing it with a jet mill or one-type mill.

■Classify the finely ground material using a dispersion classifier, zigzag classifier, etc.

■If necessary, disperse silica, etc. into the classified material using a Henschel mixer.

When the toner of the present invention is mixed with a carrier and used as a two-component developer, the carrier has a particle size of 30 to 200.
Conventionally known materials such as iron powder, ferrite powder, magnetite powder, etc. of about μm size can be used. Moreover, those whose surfaces are coated with silicone resin, acrylic resin, fluororesin, or a mixture of these resins can also be suitably used. The mixing weight ratio of carrier and toner is 1
00: 1 to 10 is good.

In addition, Mw/M of the polyester resin in the present invention
The value of n was calculated from the value measured by gel permeation chromatography (GPC). The measurement conditions are as follows: Tetrahydrofuran is flowed as a solvent at a flow rate of 1 d/min at a temperature of 25° C., and a sample solution of tetrahydrofuran with a sample concentration of 8 μ/d is injected for 0.5 d. As a column, in order to accurately measure the molecular weight range of approximately 5×10'' to 5×10'', it is preferable to combine a plurality of commercially available polystyrene gel columns. In measuring the molecular weight of the sample, the molecular weight distribution of the sample was calculated from the relationship between the logarithm value and the count number of a calibration curve prepared using several types of monodisperse polystyrene standard samples. Also, the detector has R
1 (refractive index) detector was used.

The softening point of the resin in the present invention is determined according to JIS K7210.
It was measured using a flow tester described in 6719 and 6719. Specifically, as shown in Figure 1, approximately 1
While heating sample 3 of
A load of 1 mL is applied to the sample, and the sample is extruded through a die 4 having a hole diameter of 1 ml and a length of 1 cm. As a result, a plunger stroke temperature curve as shown in FIG. 2 is drawn, and when the height of the S-shaped curve is h, the temperature corresponding to h/2 is defined as the softening temperature.

On the other hand, the acid value of the polyester resin in the present invention is JI
It is measured according to the method described in S KOO70.

<Examples> Examples of the present invention will be described below, but the present invention is not limited thereto. In the examples, "parts" indicate "parts by weight."

[Example] - (Manufacture of polyester resin for comparison) Put 40 g or more of fumaric acid into a 4-Low flask made of glass, and attach a thermometer, a stainless steel stirring bar, a falling condenser, and a nitrogen introduction tube. The reaction was carried out under a nitrogen stream in an electric mantle heater with stirring at 200° C. and normal pressure in the first half and 220° C. under reduced pressure in the second half.

The acid value of the obtained polyester resin is 2.0 K OHm
g/g, and the softening point was 111°C. Also, Mw/
Mn was 5.5.

Gold Layer [L (Synthesis of Resin Composition A) A polyester resin was polymerized under the same monomer composition and reaction conditions as in Synthesis Example 1, and a polyester resin having the same physical properties as in Synthesis Example 1 was obtained.

Next, while maintaining the final reaction temperature (220°C) even after the completion of the reaction, phenoxy resin Bakelite PKHC was added at a ratio of 20 parts to 80 parts of this polyester resin and melted and stirred to form a resin composition. was created.

Main Plan (Synthesis of Resin Composition B) A polyester resin was obtained by carrying out the reaction in the same manner as in Synthesis Example 1, except that 30 g or more of terephthalic acid was used.

The acid value of the obtained polyester resin was 3.3 K OHm
g/g, and the softening point was 123°C. Also, Mw/
Mn was 14.5.

In the same manner as in Synthesis Example 2, 10 parts of phenoxy resin Bakelite PKHH was added to 90 parts of the polyester resin and melted and stirred to prepare a resin composition.

A polyester resin was obtained by carrying out the reaction in the same manner as in Synthesis Example 1 except that 200 g of pentaerythritol and 230 g or more of fumaric acid were used.

The acid value of the obtained polyester resin is 0.8 K OHm
g/g, and the softening point was 127°C. Also, Mw/
Mn was 34.8.

Hereinafter, similarly to Synthesis Example 2, 10 parts of phenoxy resin Bakelite PKHJ was added to 90 parts of the above polyester resin.
A resin composition was prepared by melting and stirring the resin composition.

(Examples 1-7 and Comparative Examples 1-2) Table 1 lists toner compositions of Examples 1-7 and Comparative Examples 1-2.

The toner was produced as follows.

The materials for each toner were melt-kneaded using a kneader, cooled, and then coarsely ground using a hammer mill, and then finely ground using an air jet type pulverizer.

The obtained fine powder was classified to have a particle size of 5 to 20 μm to obtain a toner. The volume average particle diameters measured by Coulter counter were all within the range of 10±0.5 μm.

A developer is prepared by mixing these toners and a carrier. In the case of positively charged toners (Examples 1 to 4 and Comparative Example 1), the carrier is a fluororesin coated powder with an average particle diameter of about 70 μm. In the case of negatively chargeable toner (Examples 5 to 7 and Comparative Example 2), ferrite powder coated with silicone resin has an average particle size of about 70 μm.
ferrite powder was used. The toner concentration was 5 wt % in each case, and the toner was mixed for a predetermined time in a blender to obtain a developer.

In order to produce an image using the above developer, use a commercially available copying machine, and use an organic photoconductor as a photoreceptor for the positively chargeable developer and selenium as the photoreceptor for the negatively chargeable developer. there was.

The following tests were conducted using these toners and developers to evaluate the toners.

(Frictional charge amount) The amount of triboelectric charge of the developer was measured by the blow-off method.

(Minimum fixing temperature and offset temperature resistance) Using a fixing unit modified from a commercially available copying machine's thermal roll fixing device (upper roll: Teflon, lower roll: silicone) to variable temperature,
Pass through unfixed paper that has been developed with a certain amount of toner. Repeat the same process while changing the hot roll temperature, and set the lowest roll temperature at which the toner image does not peel off when rubbed with your finger as the lowest fixing temperature. Further, the highest roll temperature at which no high temperature offset phenomenon is visually observed is defined as the offset resistance temperature.

(Resistance to vinyl chloride) After inserting a white sheet of soft vinyl chloride into toner in a container, the condition of toner contamination on the vinyl chloride sheet was determined by holding it at a temperature of 50″C day and night. Visually observe. All (rated as ○ for non-contaminating items and × for contaminated items.

(OHP transparency) Reproducing clear color tones even when transmitted through an OHP (overhead projector) is an essential performance for full-color toners. OHP transparency fixed the toner image. HP receipts were actually transmitted through an OHP and visually judged. ○ indicates that the color reproduction of the transmitted image is good;
Those that are unclear are marked as ×.

(Continuous live copying test) Using the prepared developer, one copy of each was printed using the above-mentioned copying machine.
A continuous live-action test of 0,000 sheets was conducted. Evaluation is based on image density and
Durability was judged by comprehensively looking at changes in image quality, mainly changes in fog.

The evaluation results of the above tests are summarized in Table 2.

As is clear from this, the toner of the present invention has excellent performance.

〈Effect of invention〉 The results obtained by the present invention are as follows.

By using the heat fixing toner of the present invention, (1) it is possible to fix at a relatively low temperature, so sufficient fixing strength can be obtained with less energy consumption.

(2) Since the phenomenon of high-temperature offset during hot roll fixing is unlikely to occur, a clean and clear toner-fixed image can be obtained under all fixing conditions.

(3) Since there is no adhesion or migration of toner to the soft vinyl chloride sheet, no toner image loss or contamination occurs.

(4) Since it has good OHP transparency, it can be easily applied to full-color toners.

(5) Since it has high mechanical durability, it is possible to maintain the same initial image quality even after long-term use or continuous use.

As described above, according to the present invention, a toner having excellent effects can be obtained by a simple method, and therefore the present invention is extremely useful industrially.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view showing the central portion of the flow tester, and FIG. 2 is a plunger stroke (displacement)-temperature curve of the flow tester. 1... Plunger 2... Cylinder, 3...
Sample, 4...Die, 5...Die holder.

Claims (2)

[Claims] (1) In a toner for developing electrostatic images containing a colorant and a resin, the main component of the resin is a resin composition formed by mixing and melting a polyester resin and a phenoxy resin at a temperature equal to or higher than the softening point of the phenoxy resin. A toner for developing electrostatic images characterized by: (2) The resin composition is a resin composition obtained by mixing and melting a polyester resin with a phenoxy resin while maintaining the temperature at a temperature higher than the softening point of the phenoxy resin when the polymerization reaction for manufacturing the polyester resin is completed. The toner for developing an electrostatic image according to claim 1, characterized in that: