JPS62195678A - Developer composition for electrophotography - Google Patents

Abstract

PURPOSE:To obtain a developer which prevents offsetting without using an offset preventive liquid, permits fixing at a lower fixing temp. and has good fluidity and long life by using a specific polyester resin as an essential compo nent for a binder resin. CONSTITUTION:The polyester resin obtd. by the co-condensation polymn. of A) a diol component expressed by the formula, B) divalent carboxylic acid contg. 5-50mol% alkyl or alkenyl succinic acid in the total carboxylic acid component or the acid anhydride thereof or the lower alkyl ester thereof, and C) trivalent or higher polyvalent carboxylic acid or the acid anhydride thereof or the lower alkyl ester thereof or trihydric or higher polyhydric alcohol is used as the essential component of the binder resin of a developer compsn. contg. the binder resin and coloring agent. The alkyl of alkenyl succinic acid decreases the offset generating temp. or lowest fixing temp. but the glass transition is lowered if the content thereof of is too high. C improves the offsetting but the control of reaction is difficult if the content thereof is too high. The value of the hydroxyl value/acid value of the polyester resin is specified to >=1.2 to improve the fluidity.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a developer composition for developing electrostatic images in electrophotography, electrostatic recording, electrostatic printing, and the like.

8 [Prior Art and Problems] Conventional electrophotography involves uniformly charging a photoconductive insulating layer, and then charging the photoconductive insulating layer, as described in U.S. Pat. No. 2,297,691, U.S. Pat. An electrical latent image is formed by exposing a layer to light and dissipating the charge on the exposed areas, which is then visualized by depositing a colored, electrically charged fine powder called toner on the latent image. After transferring the resulting visible image to a transfer material such as transfer paper (transfer process), heating,
It consists of permanently fixing (fixing step) using pressure or other suitable fixing methods.

In this way, toner is used not only in the development process but also in the transfer process.
It must have the functions required in each step of the fixing process.

Generally, toner is subjected to mechanical frictional force due to shearing force and impact force during mechanical operation in a developing device, and deteriorates while copying several thousand to tens of thousands of sheets. To prevent such toner deterioration, it is best to use a strong resin with a large molecular weight that can withstand mechanical friction, but these resins generally have a high softening point and are suitable for non-contact fixing methods such as oven fixing and infrared fixing. With radiant fixing, the thermal efficiency is poor, so fixing is not sufficient.Also, since the contact fixing method has good thermal efficiency, even in the widely used heat roller constant fixing method, a heat roller is used to ensure sufficient fixing. It becomes necessary to raise the temperature of the toner, which not only causes problems such as deterioration of the fixing device, curling of paper, and increased energy consumption, but also has poor pulverization properties when using such resins, so when manufacturing toner, Manufacturing efficiency is significantly reduced.

Therefore, it is not possible to use a binder resin whose polymerization degree and even softening point are too high. On the other hand, in the heat roller constant fixing method, the heating roller surface and the toner image surface of the sheet to be fixed are in pressure contact, so the thermal efficiency is extremely high, and it is widely used from low to high speeds (although it is used, the heating roller surface and the toner image surface When the toner comes into contact with the heating roller, the toner adheres to the surface of the heating roller and is transferred to the subsequent transfer paper, which is a so-called offset phenomenon. In addition to this, we also apply a release agent such as silicone oil to the surface of the heated roller.

However, the method of applying silicone oil or the like not only increases the size of the fixing device and increases the cost, but also makes it complicated, which tends to cause trouble, and is therefore not preferable.

Also, Japanese Patent Publication No. 55-6895, Japanese Patent Publication No. 56-98202
As described in the above publication, there is a method of improving the offset phenomenon by widening the molecular weight distribution width of the binder resin, but generally the degree of polymerization of the resin increases and the fixing temperature used also needs to be set high.

As a further improved method, as described in Japanese Patent Publication No. 57-493, Japanese Patent Application Laid-open No. 50-44836, and Japanese Patent Application Publication No. 57-37353, there is a method of improving the offset phenomenon by making the resin asymmetrical and crosslinking it. However, the retention point has not improved.

Generally, the minimum fusing temperature is between the low temperature offset and the high temperature offset, so the usable temperature range is between the minimum fusing temperature and the high temperature offset.The minimum fusing temperature should be lowered as much as possible, and the temperature at which high temperature offset occurs should be raised as much as possible. This makes it possible to lower the usable fixing temperature and widen the usable temperature range, resulting in energy savings, high-speed fixing, and prevention of paper curl.

In addition, in order to be able to make double-sided copies without any trouble, the copiers have become more intelligent, the temperature control of the fixing device has become more accurate, and
There are many advantages such as relaxing the tolerance range.

Therefore, resins and toners with good fixing properties and offset resistance are always desired.

When using a styrene-based binder resin to meet such requirements, Japanese Patent Application Laid-Open Nos. 49-65232 and 1977-
No. 28840 and JP-A No. 50-81342, methods of adding paraffin wax, low molecular weight polyolefin, etc. as anti-offset agents are known, but if the amount added is small, there is no effect, and if the amount is too large, the development It has also been confirmed that the agent deteriorates quickly.

Polyester resin inherently has good fixing properties, and can be sufficiently fixed even in a non-contact fixing method, as described in U.S. Pat. It was difficult to use.

As described in JP-A-50-44836, JP-A-57-37353, and JP-A-57-109875, polyester resins with improved anti-offset properties using polyhydric carboxylic acids have sufficient properties for use. There is a problem in that either they do not have anti-offset properties, or those that do do so at the expense of the low-temperature fixing properties that polyester resins inherently have. On the other hand, toners using polyester resins may have poor fluidity compared to styrene-based toners, and may become agglomerated, resulting in poor toner transportability within the developing device.
Developability may deteriorate, resulting in formation of visible images with poor image quality, such as image unevenness and background smearing.

In order to improve the fluidity of toner, a large amount of fluidity improver such as hydrophobic silica fine powder is added, but as a result, the surface of the electrostatic image support is cleaned using a urethane rubber blade or the like. If the blade is used, toner particles may become trapped between the blade and the electrostatic image support, resulting in poor cleaning and smearing of the visible image.
In addition, when using an image forming apparatus that has a recycling system in which toner that has been developed but has not been transferred is returned to the developing device for reuse, fine particles of hydrophobic silica are embedded in the surface of the toner particles. The fluidity of the liquid was reduced and a visible image of poor quality could be formed.

The present invention has been made to meet these demands, and its purpose is to provide a developing method in which offset is prevented without applying an anti-offset liquid and which can be fixed at a lower fixing temperature in a heat roller constant fixing method. The goal is to provide medicine.

Another object of the present invention is to provide a developer that has good fluidity, does not cause blocking, and has a long life (hard to deteriorate).

[Failure to solve the problem]

That is, the present invention provides an electrophotographic developer composition containing a binder resin, a colorant, and other additives as desired, in which the main component of the binder resin is (a) represented by the following general formula: (In the formula, R is ethylene or propylene group, X.

Each y is an integer of 1 or more, and the average value of X+y is 2 to 7. ) a diol component represented by T; (b) a divalent carboxylic acid or its acid anhydride or its lower alkyl ester containing 5 to 50 mol% of alkyl or alkenyl succinic acid in the total carboxylic acid component; It is made of a polyester resin obtained by cocondensation polymerization with a polyhydric carboxylic acid or an acid anhydride or a lower alkyl ester thereof, or a polyhydric alcohol of trihydric or higher valence, and the acid value of the polyester resin is AV and the hydroxyl value is OH.
The present invention relates to an electrophotographic developer composition characterized in that the value of OHV/AV is 1.2 or more when V is expressed as OHV/AV.

When producing polyester resin, unless a transesterification reaction or a monovalent carboxylic acid or alcohol reaction is performed, carboxyl groups or hydroxyl groups remain at the molecular ends of the polyester resin, but depending on the amount of these terminal groups, the polyester resin itself It has been confirmed that the amount of triboelectric charge changes. If the amount of terminal groups, especially the acid value, is reduced too much,
If the amount of charge of the polyester resin decreases and the amount of terminal groups, especially the acid value, is increased too much, the amount of charge of the polyester resin will increase to a certain level, but on the other hand, the environmental dependence after tonerization becomes significant, and the developer It is difficult to use it as a composition for use. Polyester resins with an acid value of 5 to 60 (KOI (+ag/g)) are often used for toners. Now, when the acid value of the polyester resin is AV and the hydroxylization is OHV, OHV/AV is Toners made of polyester resins with a value of 1.2 or more have better fluidity, although the reason is not strictly clear, and using such toners makes it possible to lower the minimum fixing temperature. Ta.

The polyester resin used as the main component of the binder resin in the present invention is obtained by condensation polymerization of alcohol and carboxylic acid, carboxylic acid ester, or carboxylic acid anhydride. is polyoxypropylene (2,2)-2,2-
Bis(4-hydroxyphenyl)propane, polyoxypropylene(3,3)-2,2-bis(4-hydroxyphenyl)propane, polyoxyethylene(2,0)-
2,2-bis(4-hydroxyphenyl)propane, polyoxypropylene (2,0)-polyoxyethylene (
2,0)-2,2-bis(4-hydroxyphenyl)propane, boriooxypropylene(6)-2,2-bis(
Examples include 4-hydroxyphenyl)propane.

In addition, other diols such as ethylene glycol, diethylene glycol, triethylene glycol,
■, 2-propylene glycol, 1.3-propylene glycol, 1.4-7'tanediol, neopentyl glycol, 1.4-butynediol, 1.5-bentanediol, ■.

Diols such as 6-hexanediol, bisphenol A1, hydrogenated bisphenol A1, and other dihydric alcohols can be added in an amount of about 10 mol % or less in the alcohol component.

In addition, among the divalent carboxylic acid components in the present invention, examples of the alkyl or alkenyl succinic acid include n-butylsuccinic acid, n-butenylsuccinic acid, isobutylsuccinic acid, isobutenylsuccinic acid, and n-octylsuccinic acid. , n-
Examples include octenylsuccinic acid, n-dodecylsuccinic acid, n-dodecenylsuccinic acid, isododecylsuccinic acid, isododecenylsuccinic acid, anhydrides and lower alkyl esters of these acids. By using alkyl or alkenyl succinic acid, the temperature at which offset occurs is not lowered,
The minimum fixing temperature can be lowered, but if it is too little, the effect is weak, and if it is too much, the glass transition temperature will be lowered and the storage stability of the toner will deteriorate. Therefore, its content is preferably 5 to 50 mol% in the total carboxylic acid components.

Further, in the present invention, examples of the (b) divalent carboxylic acid component other than alkyl or alkenylsuccinic acid include maleic acid, fumaric acid, citraconic acid, itaconic acid,
Glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, succinic acid, adipic acid, sepacic acid, azelaic acid, malonic acid, or anhydrides, lower alkyl esters, and other divalent carboxylic acids of these acids. can be mentioned.

In addition, the trivalent or higher polyfunctional monomer (c) in the present invention is a preferable component for improving the offset phenomenon, but
If it is too little, the effect will be weak, and if it is too much, it will be difficult to control the reaction, and not only will it be difficult to obtain a polyester resin with stable performance, but the resin will also become hard and difficult to crush, resulting in a marked drop in toner production efficiency, and the minimum fixing temperature will be high. Undesirable phenomena such as Therefore, the amount of the trivalent or higher polyfunctional monomer (c) to be used is preferably 5 to 60 mol % in the carboxylic acid component. Specifically, among the trivalent or higher polyfunctional monomers in (c), alcohol components include sorbitol, 1
, 2.3.6-hexanetetrol, 1,4-sorbitan, pentaerythritol, dipentaerys IJ l-
-ol, tripentaerythritol, 1,2.4-butanetriol, 1,2.5-pentanetriol, glycerol, 2-methylpropanetriol, 2-methyl-
Examples include 1,2,4-butanetriol, trimethylolethane, trimethylolpropane, 1゜3.5-trihydroxybenzene, and other trihydric or higher polyhydric alcohols, and trivalent or higher carboxylic acid components. is 1
．． 2.4-benzenetricarboxylic acid, 1,2.5-benzenetricarboxylic 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(methylenecarboxyl)methane, 1,2,7゜8- Examples include octane tetracarboxylic acid, embol trimer acid, anhydrides thereof, lower alkyl esters, and other trivalent or higher carboxylic acids.

The binder resin mainly composed of polyester resin as described above used in the present invention has a softening point of 106 to 10.
160°C and a glass transition temperature of 50 to 80°C are preferable, but if the softening point is less than 106°C, it is not effective in obtaining a sufficient non-offset region, and if it exceeds 160°C, the minimum fixing temperature becomes high, etc. , undesirable phenomena occur. On the other hand, if the glass transition temperature is less than 50°C, the storage stability after forming a toner will be poor, and if it exceeds 80°C, it will adversely affect the fixing performance, which is not preferable.

In addition, the acid value and hydroxyl value of polyester resin are JIS K
When the ethyl acetate insoluble content is 3% by weight or more, dioxane is preferably used as the acid value measurement solvent.

In the present invention, when the acid value is AV and the hydroxyl value is OHV, a polyester resin with an OHV/AV value of 1.2 or more is used as the main component of the binder resin.
．． Toner obtained using a polyester resin with a polyester resin of less than 1.2 has a higher minimum fixing temperature than a toner obtained using a polyester resin with a polyester resin of 1.2 or more, and has poor fluidity. It is necessary to add a large amount of a fluidity improver such as hydrophobic silica fine powder, and in this case, as described above, a visible image with poor image quality is often formed.

The above-mentioned polyester resin having an OHV/AV value of 1.2 or more can be easily obtained by using a larger number of functional groups in the alcohol component than in the carboxylic acid component in the polycondensation reaction described above.

The polyester resin used in the present invention can be produced by condensation polymerization of a polyhydric carboxylic acid component and a polyol component, for example, at a temperature of 180 to 250° C. in an inert gas atmosphere. At this time, commonly used esterification catalysts such as zinc oxide, stannous oxide, dibutyltin oxide, dibutyltin dilaurate, etc. can be used to accelerate the reaction. It can also be produced under reduced pressure for the same purpose.

A toner is obtained using the polyester resin according to the present invention as a main component of a binder resin. For example, in order to improve the crushability in forming a toner, styrene or styrene-acrylic resin having a number average molecular weight of 11,000 or less is used. , other resins may be used up to 30% by weight in the binder resin. At the time of toner preparation, in addition to colorants, charge control agents and magnetic substances as required, property improvers such as wax as an anti-offset agent and hydrophobic silica as a fluidity improver are added. When such a polyester resin is used as a binder resin, it is not necessary to add the property improver, and even if it is added, the amount added can be small.

Coloring agents used in the present invention include carbon blank, acetylene black, phthalocyanine blue, permanent brown FC, brilliant first scarlet, pigment green B10-damine-B base,
Examples include Tsurben Trend 49, Tsurben Tread 146, Solvent Blue 35, and mixtures thereof, and are usually used in an amount of about 1 to 15 parts by weight per 100 parts by weight of the binder resin.

When making a magnetic toner using the binder resin according to the present invention,
Examples of the magnetic material include powders of ferromagnetic metals such as iron, cobalt, and nickel, and alloys or compounds containing ferromagnetic elements such as ferrite, hematite, and magnetite, and the magnetic material has an average particle size of 0.1 It can be used in the form of a fine powder of ~1 μm, dispersed in an amount of about 40 to 70 parts by weight per 100 parts by weight of the binder resin.

〔Example〕

Examples of manufacturing the binder resin and examples of the present invention will be described below, but the present invention is not limited to these examples.

It should be noted that all composition ratios shown in Examples are expressed in parts by weight.

Production Example 1 Polyoxypropylene (2,2)-2,2-bis(4-
840 g of hydroxyphenyl)propane, 195 g of polyoxyethylene(2)-2,2-bis(4-hydroxyphenyl)propane, and 317 g of isophthalic acid.

47 g of n-butylsuccinic acid and 94 g of 1,2.5-benzenetricarboxylic acid were placed in a 21 glass four-bottle flask, equipped with a thermometer, a stainless steel stirring bar, a flowing condenser, and a nitrogen inlet tube, and placed in a mantle heater. The mixture was reacted under a nitrogen stream at 200°C with stirring. The degree of polymerization was determined from the softening point according to ASTHE 2B-517, and the reaction was terminated when the softening point reached 122°C. The resulting resin was a pale yellow solid, and the DSC
The glass transition temperature measured by a differential calorimeter was 65°C. Further, the acid value of the resin was 15 KOHmg/g, and the hydroxyl value was 30 KOHmg/g. The resin is bound to a binder resin (
1).

Production Example 2 Polyoxypropylene (2,2)-2,2-bis(4-
Hydroxyphenyl)propane 1050g 1isooctenylsuccinic acid 170g, azelaic acid 141g.

Using the same apparatus and procedure as in Production Example 1 using 189 g of 1,2,4-benzenetricarboxylic acid, the softening point was 122.
℃, glass transition temperature 60℃, acid value 18KOHmg/g,
A polyester resin having a hydroxyl value of 37 KOf1 mg/g was obtained.

This resin is referred to as a binder resin (2).

Production Example 3 Polyoxypropylene (2,2)-2,2-bis(4-
hydroxyphenyl)propane 578g, polyoxyethylene(2)-2,2-bis(4-hydroxyphenyl)propane 176g, )rimethylolpropane 72g
g, terephthalic acid 374g, n-dodecylsuccinic acid 1
Production Example 1 using 71g and 2g of dibutyltin oxide
A polyester resin having a softening point of 122° C., a glass transition temperature of 61° C., an acid value of 14 KOII tag/g, and a hydroxyl value of 29 KOH mg/g was obtained using the same equipment and procedure. This resin is referred to as a binder resin (3).

Production Example 4 Polyoxypropylene (2,2)-2,2-bis(4-
716 g of (hydroxyphenyl)propane, 12 g of L4-butanediol, 72 g of trimethylolpropane, 278 g of fumaric acid, 127 g of isododecenyl succinic acid,
Using the same equipment and procedure as in Production Example 1 using 1.5 g of hydroquinone, the softening point was 122°C and the glass transition temperature was 6.
2℃, acid value 26KO1mg/g, hydroxyl value 37KOf
(mg/g polyester resin was obtained. This resin is referred to as binder resin (4).

Production Example 5 In the same manner as in Production Example 1, except that the amount of isophthalic acid was changed to 345 g, a softening point of 122°C, a glass transition temperature of 67°C, an acid value of 28 KOHmg/g, and a hydroxyl value of 26 KO were obtained.
A polyester resin of Hmg/g was obtained. This resin is referred to as a binder resin (5).

Production Example 6 In the same manner as Production Example 3, except that the amount of terephthalic acid was changed to 410 g, the softening point was 122°C, the glass transition temperature was 65°C, the acid value was 30 KOI 1 mg/g, and the hydroxyl value was 20 K.
A polyester resin with an OI of 1 mg/g was obtained. This resin is referred to as a binder resin (6).

Production Example 7 In Production Example 1, the reaction was terminated when the softening point reached 105°C, and the glass transition temperature was 62°C and the acid value was 22KOI1m.
g/g and a hydroxyl value of 37 KOIImg/g was obtained. This resin is referred to as a binder resin (7).

Examples 1 to 4, Comparative Examples 1 to 2, and Reference Examples 1 to 2 Materials with the following compositions were mixed in a ball mill, then melted and kneaded in a pressurized Neegoo, cooled, and then subjected to normal crushing and classification processes to determine the average particle size. 1
A 1 μm toner was prepared.

Composition> Example 1 Binder resin (1) 93 parts Example 2 Binder resin (2193 parts Carbon black "Googal 400R 47 parts Example 3 Binder resin + 3)" 93 parts Carbon blank "Googal 400R 47 parts Example 4 Binder Resin (4) 93 parts Carbon blank "Googal 400R 47 parts Comparative example 1 Binder resin (5) 93 parts Carbon blank "Googal 400R 47 parts Comparative example 2 Binder resin (6193 parts Carbon black [Googal 400RJ 7 parts Reference example 1] Binder Resin + 71 93 parts Carbon black "Googal 400RJ 7 parts Reference example 2 Binder resin (7193 parts Carbon blank" Gougal 400R 47 parts Polypropylene wax 4 parts [Viscol 550PJ
(Manufactured by Sanyo Chemical Co., Ltd.) The toners obtained in Examples 1 to 4 above were Toner 1 to Toner 4, and the toners obtained in Comparative Examples 1 to 2 were Comparative Toner 1 to Comparative Toner 2, respectively.
The toners obtained in Reference Examples 1 and 2 were designated as Reference Toner 1, respectively.
~Reference toner 2.

39g each of the above toners and 1261g of resin-coated iron powder
A commercially available electrophotographic copying machine (the photoreceptor is amorphous selenium, the rotation speed of the fixing roller is 255 mm/sec, the temperature of the heat roller in the fixing device is variable, and the oil coating device is Images were taken using the following image.

Control the fixing temperature between 120°C and 220°C,
Table 1 shows the results of evaluating the image fixing properties and offset properties.

The minimum fixing temperature here is 15 mm x 7.5 mm on the bottom.
A load of 500 g was placed on a 500 g sand eraser, and the image fixed through the fixing machine was rubbed back and forth 5 times. The optical reflection density was measured using a Macbeth reflection densitometer before and after rubbing, and the fixing rate was determined as defined below. This refers to the temperature of the fixing roller when the temperature exceeds 70%.

Regarding storage stability, each toner was left for 24 hours at 50° C. and 40% relative humidity, and the degree of aggregation was evaluated. The results are also shown in Table 1.

However, Comparative Toner 1, Comparative Toner 2, and Reference Toner 2 had poor toner fluidity and poor toner conveyance within the developing device, and as a result, image unevenness and background smear occurred from the initial image. For Toners 1 to 4, the minimum fixing temperature was low, the toner conveyance was good, and the image quality of visible images was good from the initial stage up to 50,000 sheets.

Table 1 Applicant's agent Kaoru Furutani Procedures (Hoshosho (voluntary) April 16, 1986

Claims (1)

[Scope of Claims] 1. In an electrophotographic developer composition containing a binder resin, a colorant, and other additives as desired, the main component of the binder resin is (a) represented by the following formula: ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, R is an ethylene or propylene group, x and y are each an integer of 1 or more, and the average value of x + y is 2 to 7.) Diol component represented by and (b) a divalent carboxylic acid or its acid anhydride or its lower alkyl ester containing 5 to 50 mol% of alkyl or alkenylsuccinic acid in the total carboxylic acid component; and (c) a trivalent or higher polyvalent carboxylic acid. A polyester resin obtained by cocondensation polymerization with an acid, its acid anhydride, its lower alkyl ester, or a trivalent or higher polyhydric alcohol, wherein the acid value of the polyester resin is AV, and the hydroxyl value is OH.
An electrophotographic developer composition having an OHV/AV value of 1.2 or more when V is expressed as OHV/AV. 2. The softening point of the binder resin is 106 to 160°C,
The electrophotographic developer composition according to claim 1, having a glass transition temperature of 50 to 80°C.