JPS58205161A - Developer for electrostatic charge image - Google Patents

Abstract

PURPOSE:To obtain a titled developer of a dry type suitable for use in a thermal fixation method by using a special shapeless polyester resin as a core material and coating the same with a thermoplastic resin into capsule structure. CONSTITUTION:A shapeless polyester resin having <=60 deg.C glass transition temp., 60-130 deg.C softening point, and about 2,000-20,000 number average mol.wt. is used as a binder resin. More specifically, a core material consisting of (A) said binder resin and a coloring agent is coated with (B) a vinyl base polymer having >=55 deg.C glass transition temp., 100-150 deg.C softening temp., >=150,000Mw and >=5Mw/Mn (Mw is weight average mol.wt., Mn is number average mol.wt.) by using a spray drying method or the like, whereby a developer for electrostatic charge image is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a developer used in electrophotography, electrostatic printing, etc., and particularly to a dry developer suitable for heat fixing.

Conventionally, as an electrophotographic method, U.S. Patent No. 2.297,69
A number of methods are known, as described in Japanese Patent Publication No. 1, Japanese Patent Publication No. 42-25910, and Japanese Patent Publication No. 45-24748, but generally they utilize a photoconductive substance,
An electrical latent image is formed on the photoreceptor by various means, and then the latent image is developed using toner, and if necessary, after the toner image is transferred to a transfer material such as paper, heat or pressure is applied. etc.) is fixed and copies are obtained.

Furthermore, various developing methods are known in which an electrical latent image is visualized using toner.

For example, the magnetic brush method described in U.S. Pat. No. 2,874,065, the cascade development method described in U.S. Pat.
...A number of development methods are known, such as the powder cloud method and fur brush development method described in No. 76, and liquid development. Toners used in these developing methods include:
Conventionally, fine powders in which dyes and pigments are dispersed in natural or synthetic resins have been used. Furthermore, it is also known to use a developing fine powder to which a fifth substance is added for various purposes.The developed toner image is transferred and fixed to a transfer material such as paper as necessary. The fixing methods include heating and melting the toner using a heater or hot roller to fuse and solidify it on the support, softening or dissolving the binder resin of the toner with an organic solvent and fixing it on the support, and applying pressure. A method of fixing toner on a support is known.

Toner materials are selected to suit each fixing method,
Toners used in a particular fusing method generally cannot be used in other fusing methods.

In particular, the toner used in the conventionally widely used heat fusion fixing method using a heater is fixed by a hot roller constant fixing method, a solvent fixing method, and a solvent fixing method.
It is almost impossible to apply it to the pressure fixation method. Therefore, toners suitable for each fixing method are researched and developed.

In addition, the image recording method of forming a magnetic latent film and developing it with magnetic toner is well known.

Various methods and devices have been developed for the process of fixing toner images on paper, etc., but the most common methods currently are:
This is a so-called hot roll fixing method in which heat and pressure are applied simultaneously, and this is a method in which an image-receiving sheet carrying a toner image is brought into contact with a heated roller to fix the toner image on the image-receiving sheet. However, when such a fixing method is used, problems such as so-called offset occur with conventional toner. Offset tends to occur when part of the toner carried on the image-receiving sheet uses molecular weight resin.
Therefore, it is thought that the problem can be prevented to the same extent, but of course, simply using a crosslinked resin increases the fixing temperature and causes the problem of low-temperature offset in the unfixed area.

The cola that comes into contact with the toner image usually has at least a surface layer formed of silicone rubber or fluororesin, which has good releasability, and is coated on the surface to prevent offset and to prevent fatigue on the roller surface. Another method is to apply a release oil such as silicone oil. However, the method of applying oil has problems such as that the fixing device becomes complicated due to the provision of the oil application system and that the evaporation of the oil causes discomfort to the user. Therefore,
It is not desirable to try to prevent offset by coating with oil; rather, the current situation is that it is desired to develop a toner with good offset resistance and a wide stationary temperature range.

In addition to fixing properties, toner also has anti-blocking and developing properties.

Although it is necessary to have excellent transfer properties, cleaning properties, etc., conventional toners have had one or more of the following defects. That is, most of the toners that are easily melted by heating tend to become caked or collect during storage or in the copying machine. Many toners have poor triboelectric properties and flow properties due to environmental humidity changes. In addition, with many toners, the image density obtained changes due to mutual deterioration of the toner, carrier particles, and photosensitive plate due to collisions between toner particles and carrier particles and contact between them and the photosensitive plate surface due to repeated development due to continuous use. Increases background density and reduces the quality of copies. Therefore, there is a need for a toner that has a wide variety of toner properties and is suitable for the fixed hot roller fixing method 1.

Furthermore, recently, there has been a trend toward high-speed fixing in order to improve the efficiency of copying operations.In order to increase the fixing speed of conventional heat fixing methods, the softening point of the toner binder resin has been lowered to make it easier. Attempts have been made to use heat fixing, but lowering the softening point of the resin causes problems such as agglomeration of toner particles and blocking during use.

In this way, it is more suitable for high-speed heat roller constant deposition, and there is no camo roller offset and agglomeration.

There is a strong demand for toner with excellent blocking isotropic properties9. Conventionally, it has been considered to make toner into a capsule type for the purpose of simply increasing the heat fixing speed or keeping the heat constant and reducing the heat source energy. Microcapsule-type heat fixing toners aiming at high speed heat fixing or low heat energy consumption have been proposed. This type of capsule toner uses a low melting point component that is more easily melted by heat as a core material, and has a high melting point as a shell material.

In addition, it uses components that have characteristics such as chargeability and fluidity necessary for a toner.
No. 8 gives examples of polystyrene capsules with wax as the window material or polystyrene capsules with an aqueous solution as the core material. However, none of these methods takes into account the recent high-speed fixing by hot rolls, so the roller offset is severe, and therefore, they are of little use.

・”) In this way, conventional heat fixing capsule toners are a-ra+, 1
Unable to resolve the issue of N-offcent, we investigated materials with good hot roll high-speed fixing properties and excellent offset resistance, and found that polyester resin satisfies these requirements to a large extent. discovered. Furthermore, it has been found that among polyester resins, an amorphous one having a wire mesh of 1111 Mk is preferable for anti-offset properties. However, even with such polyester resins, when used in toner made by a simple crushing method as in the past, It is difficult to balance the conflicting elements of high-speed fixing performance, toner blot resistance, and caking resistance, so a certain compromise must be found. As a result of intensive research on this point, we developed a heat-fixing toner with a capsule structure made of polyester resin as a core material, which has high-speed hot roll fixing (low 1 degree fixing) and offset resistance.

It has been found that various toner properties such as freonking resistance, caking resistance, and developability can be satisfied, leading to the present invention.

The object of the present invention is to solve the above-mentioned problems.

The present invention provides a heat fixable toner. A further object of the present invention is to provide a toner for constant wear on a hot roller, which has particularly good fixing properties and good anti-offset properties.

Furthermore, it is an object of the present invention to provide a tll that has good chargeability and always shows stable chargeability during use, and that is clear and has no capri.
The present invention provides a toner that can be worn constantly on a hot roller, and which provides an iI image.

Furthermore, the object of the present invention is to have excellent fluidity and no agglomeration.
The present invention provides a heat roller constant cleaning toner that also has excellent impact resistance.

It is an object of the present invention to provide a toner that is constantly worn on a heated roller with less debris on the surface of a toner holding member or a photoreceptor.

A further object of the invention is to provide a magnetic toner which, when used as a magnetic developer, exhibits good and uniform magnetism and is capable of being used as a hot roller electrolayer.

The above object of the present invention is achieved by providing a toner with a capsule structure in which the core material is a material having high-speed heat fixing properties and anti-offset properties.

The cool thing about the present invention is that the surface of the core particles of the heat-fixable material whose main ingredients are nannan resin and kanshoku-ko is thermoplasticized! I-
In the transparent image developer coated with a saline resin, the binder resin preferably contains 50% of an amorphous polyester resin having a glass transition temperature of 60°C or less and a softening point of 60 to 150°C.
The thermoplastic resin has a glass transition temperature of 55°C or higher, a softening point of 100 to 150°C, and a M of 150,000 or higher.
It is a vinyl polymer having W and My/Mn of 5 or more.

In other words, the feature of the invention lies in the high heat fixability toner structure having a cuff-cell structure that achieves double-layer toner properties such as high speed thermal fixation.

In the heat-fixable toner with a capsule structure related to the present invention, the core material is a material with a low T7 that could not be used alone due to its blocking properties, cohesive properties, etc., and also has good anti-offset properties. The toner is used to share most of the functions of constant adhesion with the hot roller, and as a shell material, the toner properties such as developability and storage stability of the dry toner are maintained as before.

Alternatively, the objective of the present invention could be achieved by using a material having more than that amount and making it a so-called functionally separated type.

As the binder resin for the core particles used in the present invention, a specific polyester resin suitable for the purpose of the present invention is preferable. That is, it is desirable that the core particles contain 50% by weight or more (more preferably 60% by weight or more) of an amorphous polyester resin having a glass transition temperature of 60° C. or less and a softening point of 60 to 160° C. as a binder.

Aromatic polycarboxylic acids such as terephthalic acid, inophthalic acid, phthalic acid, naphthalenedicarboxylic acid, trimellitic acid and 4-pyromellitic acid, p-(2-hydroxyethoxy)benzoic acid, etc. as acid components of the polyester used in the core particles of the present invention. aromatic oxycarboxylic acids; maleic acid, fumaric acid.

Aliphatic polycarboxylic acids such as succinic acid, adipic acid, azelaic acid, heptanosic acid, etc.: 1,5-cyclohexanedicarboxylic acid, hex-7hydrophthalic acid.

There are alicyclic polycarboxylic acids such as tetrahydrophthalic acid, and alcohol components include ethylene glycol, propylene glycol + 1,4-butanediol, 1
, 6-butanediol, 1,5-bentanediol, 1
, 6-hexanediol, neopentyl glycol, glycerin, trimethylolethane, trimethylolpropane, aliphatic polyols such as pentaerythritol;
Alicyclic polyols such as 1,4-cyclohexanediol and 1,4-cyclohexane dimetatool; etherified diphenols such as ethylene oxide adducts of bisphenol A and propylene adducts of bisphenol A;

The acid component and alcohol component of the polyester used in the present invention can be arbitrarily selected as long as the combination satisfies the conditions of amorphousness and glass transition temperature. In order to have this, it is necessary to include an asymmetric component. In addition, for the purpose of resistant to fusetting, it is preferable to include a polycarboxylic acid of trivalent or higher valence and/or a polyol as a component to give the polyester a suitable network structure.

The polyester used in the present invention has a glass transition temperature of 60°C or less and a softening point of 60 to 160°C.

If the glass transition temperature exceeds 60°C or the softening point exceeds 100°C, excessive thermal energy will be required during heat fixing.
High-speed heat fixing performance deteriorates. and.

If the softening point is less than 60° C., offset resistance during fixing will be poor. Further, the number average molecular weight is preferably 20t30 to 20,000, preferably 6000 to 10,000. Molecular weight is 200
If it is less than 0, the releasability to the heat fixing roller becomes poor and an offset phenomenon tends to occur.On the other hand, if it exceeds 20,000, the softening point increases and the heat fixing power decreases.

As the binder resin for the core particles, other known binder resins such as polyester resins and epoxy resins outside the present invention may be used within a range that does not impair the performance of the present invention.

Styrene - acrylic resin, butyral resin, ethylene,
Ethyl acrylate resin, styrene/butadiene resin, etc. can be mixed and used.

As the thermoplastic fat material used in the present invention, those conventionally used as binders for toners can basically be used; determined. Within this range, for example, those that can be used as aqueous suspensions, those that can be used as alkali-soluble aqueous solutions, those that can form a coating layer on core particles by known microencapsulation methods, or those that can be formed by reaction during encapsulation. There are many things that can be done.

For water-based suspension resins, the minimum film forming temperature of the suspension should be around the softening point temperature of the core particles or preferably at least 60°C lower than that, and the resin should have good wettability and adhesion to the core particles. , It is necessary to maintain the durability of the toner when forming the outer wall, it is necessary to have a uniform coating that is not brittle, it is not sticky, and it is necessary to maintain the image forming ability, so it is necessary to have appropriate electrical resistance (insulation), frictional electrification, etc. characteristics are required. Such resin components include acrylic esters, methacrylic esters, styrene or derivatives thereof,
The above monomers arbitrarily selected from each monomer such as vinyl acetate, maleate ester, etc. and 0
．． Acrylic acid or methacrylic acid in an amount of about 2 to 10 mol%.

Products that are mainly composed of copolymer resins obtained by emulsion polymerization with organic acid monomers such as maleic acid, itaconic acid, and crotonic acid, that is, contain 60 mol% or more of this copolymer component in the resin content. can give.

In addition, as a type of resin that can be used as an alkali-soluble aqueous solution, two or more monomers arbitrarily selected from monomers such as styrene or its derivatives, acrylic esters, methacrylic esters, maleic esters, etc. On the other hand, there are products in which organic acid monomers such as acrylic acid, maleic acid, itaconic acid, and crotonic acid are copolymerized in an amount that gives an acid value of about 40 to 200 after one polymerization.

These thermoplastic resins have a glass transition temperature of 55°C or higher and a softening point of 100-15. , (11). When the glass transition temperature is less than 55°C, the obtained toner will undergo pronking during storage.

If the softening point is lower than 1'JO°C, offset is likely to occur during heat fixing. Furthermore, if the softening point exceeds 150°C, the heat fixing properties of the window material will be significantly impaired.

The coulometric average molecular weight My is required to be 150,000 or more from the viewpoint of preventing hot roller offset, and from the same viewpoint, it is desirable that MW/Mn be 5 or more. My l less than 50,000 and M'iF,
/Mn5, the hot-melted vinyl polymer will have poor offset resistance.

In the capsule toner of the present invention, a charge control agent, a coloring agent, and a fluidity modifier may be added to one or both of the core material and the outer shell, as necessary. The agent may be used by being mixed with the toner (externally added). Examples of the charge control agent include metal-containing dyes and nigrosine, and conventionally known dyes and pigments can be used as the colorant, and colloidal silica, fatty acid metal salts, etc. can be used as the fluidity modifier. There is.

Furthermore, if it is desired to obtain the magnetic toner 1, magnetic fine particles may be added to the toner. Magnetic substances include materials that exhibit magnetism or can be magnetized, such as iron, manganese, nickel, and cobalt.

Conventionally known magnetic materials can be used, such as fine metal powders such as chromium, various ferrites, alloys and compounds such as manganese, and other ferromagnetic alloys. These magnetic fine particles may be added to either the core material or the shell material, but in the case of obtaining an insulating toner, it is preferable to add them to the core material.

Furthermore, polyolefins such as low molecular weight polyethylene, low molecular weight polypropylene, etc. may be added to the core material and/or the shell material in order to improve the releasability from the heat fixing roll.

In the present invention, a known dry toner production method can be applied as is to obtain the core particles.

For example, the most common method is to mix Bolier, Stell resin, and other compounds into fine particles in advance, mix them uniformly by heat @ melt kneading, and then obtain core particles of a constant particle size using air jet pulverization, wind classifier, etc. It is. Moreover, core particles of a constant particle size can also be obtained by uniformly dispersing the preparation 1-compound in an organic solvent solution of a polyester resin and then spray-drying and granulating it using a spray dryer.

In the present invention, the spray drying method is preferred as the encapsulation method, but depending on the material used as the wall material,
Phase separation method, air suspension seed method, etc. can be used.

Hereinafter, the present invention will be explained in more detail with reference to Examples.
These do not limit the invention. Further, all parts in the examples are parts by weight. In addition, each physical property of the resin was measured by the following method.

Glass transition temperature - Dependency point measured with a differential scanning calorimeter (Model DSC-IB, manufactured by PerkinElmer) at a heating rate of 16° C. 7/min - According to JIS K2551, ring and ball softening point test.

[Production Example 1] Polypropylene oxide adduct of bisphenol A 56
Put 0 part into a Yotsuro flask, add a stirrer, a condenser,
Set the thermometer and gas inlet tube and place it inside the mantle heater. After replacing the inside of the reaction vessel with nitrogen gas, the contents are 50~
When the temperature reached 60°C, 190 parts of fumaric acid and 0.4 parts of hydroquinone were added, and the mixture was heated to 210°C with stirring.

After about 5 hours have elapsed while continuously removing the reaction water, the reaction is monitored by acid value measurement every hour to check the end point of one reaction. When the acid number reaches about 50, 0.5 part of sorbitol is added to each reaction mixture, and the reaction is continued until the acid number reaches about 25, after which the resin is cooled to room temperature. The resin thus obtained had a TN of 55°C and a Europeanization point of 95°C.

[Production Example 2] □' Following the same method as in Production Example 1, 650 parts of a polyethylene oxide adduct of bisphenol A and 7 parts of glycerin were placed in a flask, and the flask was heated at 50°C and replaced with nitrogen. 240 parts of 7-maric acid and 0.4 parts of hydroquinone are added thereto, and the mixture is heated and stirred at 210° C. to react. After the reaction is completed, the resin is cooled to room temperature. This resin had a Tll of 52°C and a softening point of 120°C.

[Production Example 6] 200 parts of fumaric acid, 600 parts of polyethylene oxide adduct of bisphenol A, and 0.5 parts of diphenolic acid are placed in a flask, and the reaction mixture is heated and stirred to about 80°C.

Approximately 0.4 part of hydroquinone is then added and the mixture is gradually heated to approximately 200° C. over approximately 6 hours. After distilling off the recovered alcohol and remaining raw materials, the reaction is allowed to proceed for about 8 hours under reduced pressure, and after the reaction is completed, it is allowed to cool. The obtained resin has a Tg of 59℃
, the softening point was 100'C.

[Production Example 4] 580 parts of dimethyl isophthalate, 300 parts of 1,4-butylene diol, 1 part of trimethylol, and 12 parts of lopane are placed in a flask, and heated and stirred to about 80'C. Approximately 1 g of tetrabutyl titanate is then added, and after approximately 6 hours (Kt), the mixture is gradually heated at approximately 210'CKt for reaction. After the reaction is complete, allow to cool. The resulting resin had a TV temperature of 57°C and a softening point of 70°C.

[Production Example 5] 500 parts of terephthalic acid, 100 parts of ethylene glycol,
420 parts of neopentyl glycol, 50 parts of trimethylolpropane, and 270 parts of isophthalic acid are charged into a flask and heated and stirred at 50"cK. Next, 0 parts of dibutyltin oxide is added.
．． Add 6 parts, heat to 220'C and react for about 6 hours. The obtained polyester had a Tf of 50'C and an electrification point of 86°C.

[Manufacturing example 61 650 parts of terephthalic acid, 200 parts of sebacic acid.

140 parts of isophthalic acid, 650 parts of ethylene glycol,
Pour 550 parts of neopentyl glycol into a flask 1
The reaction was carried out at 800-220'C for 4 hours, and then the system was reduced in pressure and the reaction was carried out for an additional 250'CI hours. The obtained resin had a Tf 5 t) 'C1 softening point of 100° C. [Production Example 7] According to the same method as Production Example 1, 400 parts of terephthalic acid,
100 parts of isophthalic acid, 280 parts of ethylene glycol,
Add 120 parts of neopentyl glycol to the flask and add 6
Heat and stir to 0°C.

Next, the mixture is heated to about 220°C and the reaction is carried out for about 6 hours. The TfI of the polyester obtained by cooling after completion of the reaction is 65°C.
, the softening point was 165°C.

[Production Example 8] 58 parts of dimethyl terephthalate, 600 parts of 1,2-brohanshiol, and 4 parts of trimethylolpropane are placed in a flask. The mixture is heated to about 80°C and 1.5 parts of tetrabutyl titanate are added, followed by gradual heating to about 200°C over a period of about 6 hours. After reducing the pressure of the system and removing the distillate, the system was further heated under reduced pressure for 6 hours to complete the reaction. The resulting polyester had a TjF of about 80''C1 and a softening point of about 95°C.

[Example 1] 100 parts of polyester (Production Example 1), 70 parts of magnetic powder (Magnetite gpT-iooo manufactured by Toda Kogyo), Ia molecule! Polypropylene (Viscol 660 manufactured by Sanyo Chemical Industries)
F) A mixture consisting of 5 parts was heated and kneaded with a roll. After allowing this to cool, it was pulverized one or two times, and further pulverized using a jet mill and classified using an air classifier to obtain core material particles with an average size of about 12 μm.

Separately, a styrene/butyl methacrylate/butyl acrylate/acrylic acid copolymer emulsion (acrylic acid 6 mol%, solid content 40%) was prepared. The glass transition temperature of the constituent resin of this emulsion is 70°C, the softening point is 140°C, and the M
W230,000 MW/Mn6.5.

To 20 parts of this emulsion, 58 parts of the core substance, metal complex dye (Orient Chemical Layer, Bondron E-81),
) Add 0.4 parts and 240 parts of water.

After mixing and dispersing well while avoiding foaming, spray drying is performed using a spray 1 dryer at an inlet temperature If of -160°C and an outlet temperature of 90°C, so that the emulsion-constituting copolymer is mainly formed around the core material particles. Colloidal silica (Aerosil R-972) was added to the thus obtained capsule toner provided with a crosslinked resin coating layer, and a -component development type electrophotographic copying machine (Canon N
P-400RE) and a copying test was conducted, and sufficient image density and development durability were obtained. In addition, in order to examine the heat fixability in detail, only the fixing unit of the copying machine was prepared separately, and the fixation properties were also excellent even on a separately prepared transfer paper. Further, this capsule toner was left in an atmosphere at 50° C. for a long time, but no freonking or caking was observed.

[*Stream side 2 to 6] Capsule toners were obtained in the same manner as in Example 1 except that the polyester of Example 1 was replaced with another example (Production Examples 2 to 6) (Examples 2 to 6). Their performance is the first
It was as shown in the table.

[Example 7] 100 parts of polyester (Production Example 1), 70 parts of magnetic powder (Magnetite KPT-1000 manufactured by Toda Kogyo).

is molecular weight polypropylene (Viscol 6 manufactured by Sanyo Chemical Industries)
A mixture consisting of 5 parts of 60F) was classified using a roll and an air classifier to obtain core material particles with an average size of around 12μ. A polymer emulsion (2 mol% itaconic acid, 42% solids) was prepared. The glass transition of the constituent resin of this emulsion is 65℃, the softening point is 165℃, 1MW 280,000, MW/! vl
It's 8.5.

Also, acrylic copolymer resin (Seiko Kagaku, Hyros X-
516, oxidation 6I]) was dissolved in ammonia alkaline water to make a 25% aqueous solution.

8 parts of the above resin aqueous solution was mixed with 20 parts of the above emulsion, 50 parts of the core material particles and 200 parts of water were added thereto, the mixture was well mixed and dispersed, and then sprayed with a spray dryer at an inlet temperature of 160°C and an outlet temperature of 80°C. Spray drying was carried out at 0.degree. C. to provide a resin coating layer mainly composed of the emulsion-constituting copolymer and an alkali-soluble resin around the core material particles.

Colloidal silica (Aerosil R-972) was added to the capsule toner thus obtained, and a copying test was conducted in the same manner as in Example 1.

The results were as shown in Table 1.

[Example 8] A capsule toner was obtained in the same manner as in Example 7 using the emulsion/alkaline aqueous solution mixture except that the polyester in Example 7 was replaced with Production Example 6, and the results shown in Table 1 were obtained. .

[Comparative Example 1] A capsule toner was obtained in the same manner as in Example 7 except that the polyester of Example 7 was replaced with Production Example 7. [Comparative Example 2] The polyester of Example 1 was replaced with Production Example 8. A bag cell toner was obtained in the same manner as in Example 1 except for the above.

[Comparative Example 6J 100 parts of the polyester of Production Example 6, magnetic powder (Titan Industry Contract Magnetai BL-120) 80 parts, low molecular weight polyethylene (Mitsui Petrochemical High Wax 220.1'
) A mixture consisting of 4 parts was heated and kneaded with a roll. After cooling, this was made into a coarse powder, which was then finely pulverized using a jet mill and classified using an air classifier to obtain toner particles of 5 to 25 μm. When this toner was subjected to a copy fixing test in the same manner as in Method 1, sufficient images and fixing properties were obtained. However, when this toner was left in an atmosphere at 45° C. for 24 hours, blocking occurred at the tip, resulting in a lump.

Table 1 1 person: Canon Co., Ltd. Agent: Gi Marushima

Claims (1)

[Scope of Claims] An electrostatic image developer in which the surface of a core particle of a heat-fixing material whose main component is a binder resin 1 and a colorant is coated with a thermoplastic resin. The binder resin has a glass transition temperature of 60°C or less, 60°~
It contains an amorphous polyester resin having a softening point of 150°C, and the thermoplastic resin has a glass transition temperature of about 55°C, a softening point of 100'' to 150°C, and a My of 150,000 or more.
An electrostatic image developer characterized by being a vinyl-based poly°7- having an M''/Mn of 5 or more.