JPH0668640B2 - Electrophotographic toner and image forming method - Google Patents

Description

The present invention relates to an electrophotographic toner used in an image forming method for fixing a toner image formed by an electrophotographic method, an electrostatic printing method or the like onto a transfer material, and an electrophotographic toner. The present invention relates to an image forming method using the toner.

[Prior Art] Conventionally, a number of methods are known as electrophotographic methods as described in US Pat. No. 2,297,691, Japanese Patent Publication No. 42-23910 and Japanese Patent Publication No. 43-24748. Generally, a photoconductive substance is used to form an electric latent image on a photoconductor by various means, and then the latent image is developed with a toner, and a toner is transferred to a transfer material such as paper as necessary. After transferring an image, it is fixed by heating or pressure to obtain a copy.

Various developing methods for visualizing an electric latent image using toner are known.

For example, the magnetic brush method described in U.S. Pat.No. 2874063, the cascade development method described in US Pat. A number of developing methods such as the method are known. Toners used in these developing methods are conventionally dyes in natural or synthetic resins,
A fine powder in which the pigment is dispersed is used. Furthermore, the third
It is also known to use developing fine powders to which substances have been added for various purposes.

The developed toner image is transferred and fixed on a transfer material such as paper, if necessary.

As a method for fixing the toner image, a method of heating and melting the toner by a heater or a heat roller to fuse and solidify it on the support, a method of softening or dissolving the binder resin of the toner with an organic solvent and fixing it on the support, pressurization There is known a method of fixing the toner to the support by the method.

Toners are selected with materials suitable for each fixing method,
Generally, the toner used for a particular fixing method cannot be used for another fixing method. In particular, it is almost impossible to transfer the toner used in the heat fusion fixing method using a heater, which has been widely used in the past, to the heat roller fixing method, the solvent fixing method, the pressure fixing method and the like. Therefore, toner suitable for each fixing method has been researched and developed.

Various magnetic recording methods are known in which a magnetic latent image is formed and developed with a magnetic toner.

Although various methods and devices have been developed for the process of fixing the toner image on paper, the most general method at present is
This is a so-called thermal roll fixing method in which heat and pressure are applied simultaneously, and this is a method of fixing the toner image on the image receiving sheet by bringing the image receiving sheet carrying the toner image into contact with a heated roller. However, when such a fixing method is used, problems such as so-called offset are likely to occur in the conventional toner. Offset is an undesirable phenomenon in which a part of the toner carried on the image receiving sheet is transferred to the roller surface.

That is, in recent years, a heat roll type fixing system having a good thermal efficiency has come to dominate the commercial copying machines as the efficiency of copying operations, the energy saving, and the miniaturization and high performance of copying machines have increased. Most of these copiers try to fix the toner on the paper by thermocompression bonding with a heating roller.The non-contact heating method using heat rays allows the heating element to obtain a satisfactory fixed image at a lower temperature. Although there are many advantages such as higher speed and the like, this method also has various drawbacks. As one of the big things, when the roller is kept at a temperature at which the toner should be sufficiently fixed to the holding member such as paper, the toner is fused not only on the paper but also on the heat roll,
Due to that, the heat roll becomes dirty as the copying is repeated, and the blade or cleaning web that should keep the roll clean cannot be removed sufficiently, and eventually the paper is also soiled, which is the so-called offset contact method. It has serious problems.

Various measures have been attempted for fixing devices and toners in order to solve or alleviate this problem, but it cannot be said that they have been sufficiently solved.

As the fixing device, a material such as Teflon or silicon having excellent surface peeling property is used. Alternatively, a device such as applying oil such as silicone oil to the roller has been made, and most of the hot roller fixing devices of currently commercialized copying machines apply oil in some form. However, the oil application causes problems such as oil stains on the sheet and troubles due to complication of the fixing device and an increase in cost.

As a toner, a method of adding a small amount of wax such as low-molecular weight polyethylene or polypropylene that is sufficiently melted when heated to increase the peeling property is used, but it is effective in preventing offset, but aggregation of the toner However, it is difficult to say that this is sufficient, because adverse effects such as an increase in the property, instability in the charging characteristics, and a decrease in the durability have been observed. As other methods, various attempts have been made to improve the binder resin. Japanese Patent Publication No. 51-23354 discloses a toner using a crosslinked polymer as a binder resin. According to that method, there is a remarkable improvement in offset resistance and scuffing resistance, but on the other hand, if the degree of cross-linking is increased, the fixing point will rise, and the fixing temperature will be low enough that offset resistance and scuffing resistance will be low. Good satisfactory fixing properties have not been obtained. And, the cross-linked polymer is difficult to disperse the pigment and is difficult to be compatible with other polymers, so that the toner using the cross-linked polymer as a binder resin is difficult to obtain good developing characteristics. There is.

In addition, low molecular weight amorphous polyester resins and epoxy resins are attracting attention as binders suitable for low-temperature fixing. Attempts to use a polyester resin as a binder for toner have been made, for example, in Japanese Patent Publication No. Sho 46-12680 (USP.
3590000), Japanese Patent Publication No. 52-25420 (USP.36811)
No. 06) and the like. However, according to the experiments and studies conducted by the inventors of the present invention with respect to these descriptions, the toner having the polyester resin as a main binder can surely have a lower fixing temperature than other materials, but the offset to the heat roller does not occur. The phenomenon cannot be sufficiently prevented.

In general, in order to measure high-speed fixing, it is necessary to lower the molecular weight of the resin and lower the softening point, which is contrary to the measures for improving the offset resistance. Further, this inevitably lowers the glass transition point of the resin, which causes an undesirable phenomenon that the toner is blocked during storage. However, low temperature fixing is not so required. In the conventional low-speed medium-speed machine, process measures such as the above-mentioned fixing device improvement and toner improvement, for example, crosslinking,
Due to measures such as the use of releasable additives, there was no problem at a practical level. However, basically, the above contradiction has not been solved, and under the present circumstances, a toner capable of fixing at an extremely low temperature and having a wide fixing temperature range and good offset resistance and blocking resistance has not been obtained.

[Problems to be Solved by the Invention] The present invention has been made to provide an electrophotographic toner and an image forming method using the toner, in which the above drawbacks are remarkably improved.

The objects of the present invention are listed below.

(1) An object of the present invention is to provide a dry toner suitable for a heat roll fixing method in which oil is not applied, and an image forming method using the toner.

(2) The object of the present invention is to fix a toner sufficiently at a lower temperature and reduce the energy, particularly suitable for high-speed fixing, sufficiently prevent offset, and a toner having a wide fixable temperature range. It is to provide an image forming method using the same.

(3) An object of the present invention is to provide a toner having an acceptable agglomeration temperature and free from blocking during storage and use, and an image forming method using the toner.

(4) An object of the present invention is to provide a toner having stable electric characteristics under various humidity conditions and excellent moisture resistance, and an image forming method using the toner.

(5) It is an object of the present invention to provide a toner having an excellent developing property, which has a sufficient image density and is clear, and which has an image quality without resolution such as background fog, and an image forming method using the toner. .

(6) It is an object of the present invention to provide a toner having excellent durability against repeated use and capable of stably maintaining a good image as described in the preceding paragraph, and an image forming method using the toner. It is in.

(7) An object of the present invention is to provide a toner having excellent powder properties such as fluidity and cohesiveness, good replenishment and storage properties, and an image forming method using the toner.

(8) It is an object of the present invention to provide a toner having a high degree of abrasion resistance against a mechanical load during a developing process and having excellent impact resistance, and an image forming method using the toner. is there.

(9) An object of the present invention is a toner having a good transfer rate that enables easy transfer from an electrostatic image forming surface to an image receiving surface, and having excellent transferability without image irregularity and nonuniformity during transfer, and the toner. An object of the present invention is to provide an image forming method using.

(10) It is an object of the present invention to provide a toner that does not adhere to the toner holding member or the electrostatic latent image surface and is not contaminated, and an image forming method using the toner.

(11) An object of the present invention is to provide a toner having almost no carrier contamination caused by adhesion to a carrier, fusion, etc. in a two-component developer, and an image forming method using the toner. is there.

(12) An object of the present invention is to provide a toner having good dispersibility of magnetic powder in a one-component magnetic toner and an image forming method using the toner.

(13) An object of the present invention is to provide a toner having a good photosensitive surface cleaning property by reducing mechanical abrasion of an electrostatic image forming surface, and an image forming method using the toner.

(14) It is an object of the present invention to provide a toner which is easy to manufacture, enables stable production, and is low in cost, and an image forming method using the toner.

(15) An object of the present invention is to provide a toner of high commercial value which is excellent in overall conditions in which various performances required for the toner are well balanced and an image forming method using the toner. .

[Means and Actions for Solving Problems] Specifically, the present invention forms an electrical latent image on a photoreceptor,
The latent image is developed with toner to form a toner image, the toner image is transferred to a transfer material, and the toner image on the transfer material is fixed at a fixing temperature 10 ° C. or more higher than the softening lower limit temperature of the toner. An electrophotographic toner used in an image forming method of fixing by a thermocompression bonding method, wherein the toner contains a binder resin and a colorant as main components, and the binder resin contains an etherified bisphenol and a dicarboxylic acid. And a toner having an acid value of 10 to 100. The toner has the following conditions: 10 ≦ T ₂ −T ₁ ≦ 60 110 ≦ T ₁ <170 (unit: ° C.) [In the formula, T ₁ represents the softening lower limit temperature of the toner, and T ₂ represents the softening upper limit temperature. ] It is related with the toner for electrophotography characterized by satisfying.

Furthermore, the present invention forms an electric latent image on a photoreceptor, develops the latent image with toner to form a toner image, transfers the toner image to a transfer material, and transfers the toner image on the transfer material. In the image forming method of fixing the toner by thermocompression bonding, the toner contains a binder resin and a colorant as main components, and the binder resin is a polyester resin produced from a raw material containing etherified bisphenol and dicarboxylic acid. The polyester resin has an acid value of 10 to 100, and the toner has the following conditions: 10 ≦ T ₂ −T ₁ ≦ 60 110 ≦ T ₁ <170 (unit: ° C.) [wherein T ₁ is a toner Shows the softening lower limit temperature, and T ₂ shows the softening upper limit temperature. ], The toner image on the transfer material is fixed by heat and pressure under a fixing temperature condition higher than the softening lower limit temperature T ₁ by 10 ° C. or more.

In the present invention, the softening lower limit temperature, the softening upper limit T ₁ ,
T ₂ can be obtained by the following measuring method.

Using flow tester CFT-500 type (manufactured by Shimadzu Corporation),
Toner drawn when the die (nozzle) has a diameter of 0.5 mm and a thickness of 1.0 mm, an extrusion load of 50 kg is applied, and an initial set temperature of 80 ° C. and a preheating time of 300 seconds followed by a constant temperature increase of 5 ° C./minute. Then, a plunger drop amount-temperature curve (hereinafter referred to as a softened S-shaped curve) is calculated. Use 2.5 g of fine powder as the sample toner, and make the plunger cross-sectional area 1.0 cm ² . Softening S
The curve is usually the one shown in Fig. 1. As the temperature rises at a constant rate, the toner is gradually heated and starts to flow out. (Plunger descending A → B) When the temperature is further raised, the toner in the molten state largely flows out (B → C → D), and the plunger descending is stopped and completed. (D → E) The height H of the softening S curve indicates the total outflow amount, and the temperature T ₀ corresponding to the point C of H / 2 indicates the softening point of the toner.

The softening upper limit temperature T ₂ and the softening lower limit temperature T ₁ can be obtained from the softening S-shaped curve by drawing the intersection method.

That is, the temperatures T ₁ and T ₂ indicated by the tangents of the S-shaped curve at point C, which is the softening point, and the intersections F and G on the extension lines of the outflow start line (AB) and outflow stop line (DE) Softening lower limit temperature,
This is the softening upper limit temperature.

Correlation between physical properties of toner and flow tester value
As disclosed in JP-A-211160, a toner whose softening point and melt viscosity in flow tester measurement are specified,
There is already a description of toner that specifies the difference between the softening point and the softening start temperature such as 05161. The major difference between the present invention and these is that the above-mentioned inventors explain the thermal phenomenon over the entire toner with only one representative value (for example, the softening point) indicating the overall thermal characteristics of the toner. Try to solve the drawbacks of. For example, in FIG. 2, the toner characteristics are completely different although they have the same softening point. However, the present invention can satisfy low temperature fixing property, cold offset resistance, hot offset resistance, and storage stability for the first time by partially decomposing the physical properties and thermal properties of the toner and defining them. It exists in that toner can be obtained. In FIG. 1, T ₁ is considered to be an index showing the thermal characteristics of the soft component in the toner. T ₁ is 110
If the temperature is lower than 0 ° C, a large amount of the soft component is likely to undergo thermal deformation at a low temperature, which increases the cohesiveness during storage (hardens in the worst case) and impairs the toner fluidity. Further, the hot offset caused by heat fusion of the soft component onto the heat roll, which occurs at the upper limit fixing temperature, becomes worse. When T ₁ is 170 ° C. or higher, the fixing point is increased, which is not practically preferable as a toner for high-speed copying machines.

Further, T ₂ is a quantitative index of the hard component in the toner. The higher T ₂ is, the more the hard component is, the more energy is required to completely fix the toner,
Actually, a fixing device having a high set temperature and a wide nip width is required. And since there are many hard components, cold offset at low temperature inevitably increases.

However, the present invention can be achieved only by the toner that defines the thermal characteristics of the soft component and the hard component, and at the same time and necessarily in the temperature range in which the fixing temperature of the actual machine can be unitarily determined.

The preferable temperature range of the toner is 10 <T ₂ −T ₁ <50,
110 ≦ T ₁ <150 (unit: ° C.), more preferably 10 <T ₂ −T ₁
<40, 110 <T ₂ <145 (unit: ° C).

As a binder resin for achieving the present invention, the inventors of the present invention, after intensive studies on various resins, find a polyester resin, particularly a polyester resin obtained by reacting a polycarboxylic acid and an etherified diphenol. It was completed by.

In the process of reaching the polyester resin, the present inventors have focused on the vinyl-based polymer, its copolymer, and the epoxy-based polymer, and invented a toner within the above temperature range. I couldn't. As a characteristic of the vinyl-based polymer from its original constituents, an attempt to lower T ₁ will increase T ₂ at the same time, and even if the softening point is the same, the softening curve becomes an S-shaped curve that is broad in terms of temperature. (Fig. 3).

Examples of the divalent aromatic carboxylic acid as the carboxylic acid used in the polyester of the present invention include phthalic acid, isophthalic acid,
There are derivatives of phthalic anhydride, derephthalic acid, and their esters, and examples of trivalent or higher aromatic polycarboxylic acids include 1,2,4 benzenetricarboxylic acid, 1,2,5-benzenetricarboxylic acid, 1,2,4 naphthalene tricarboxylic acid,
There are 2,5,7 naphthalene tricarboxylic acid, 1,2,4,5 benzene tetracarboxylic acid, and their anhydrides and esterified products. The amount of trivalent or higher aromatic polycarboxylic acid preferably does not exceed 40 mol% of the acid component.

Examples of the divalent aliphatic carboxylic acid include maleic acid, fumaric acid, succinic acid, adipic acid, sebacic acid and itaconic acid. In addition, an acid component can be used within a range that does not impair the object of the present invention.

The etherified diphenol used in the present invention is mainly an etherified bisphenol obtained by etherifying bisphenol, and particularly a propoxylated one and / or an ethoxylated one. These have 2-3 moles of oxypropylene or oxyethylene per mole of bisphenol. Specifically, polyoxypropylene 2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene 2,2-bis (4-hydroxy, 2,6-dichlorophenyl) propane, polyoxyethylene (1.0) -polyoxy Propylene (1.5) -bis (4 hydroxyphenyl) propane and the like.

Particularly useful in the present invention are propoxylated bisphenols, which do not contain ethoxylated bisphenols, but are preferred to have a composition in which the molar amount does not exceed the amount of propoxylated bisphenols, and both propoxylated and ethoxylated alkoxys are used. In the case of modified bisphenol, it is preferable that the ethoxylation amount does not exceed the propoxylation amount. That is, in the case of the toner composition using the polyester using the etherified diphenol in which the ethoxylated bisphenol accounts for the majority, the characteristics at high humidity are obviously inferior as compared with the toner composition using the propoxylated bisphenol. It is presumed that this reflects the difference in hydrophilicity and hygroscopicity of the obtained toner composition. That is, the toner using the etherified bisphenol in excess of ethoxylated bisphenol has a high hygroscopic property under high humidity, and therefore the triboelectric charging property is lowered, resulting in poor developing performance and consequently a low image density.

The etherified diphenol is obtained by directly adding ethylene oxide or propylene oxide to diphenol or by reacting an olefin halohydrin with diphenol.

Other alcohol components, if necessary, within the range of 20 mol% of the total polyol, for example, ethylene glycol, propylene glycol, 1,4-butanediol, 1,5-
Pentanediol, 1,6-hexanediol, glycerin, trimethylolethane, trimethylolpropane,
Aliphatic polyols such as pentaerythritol and aliphatic polyols such as 1,4-cyclohexanediol and 1,4-cyclohexanedilutanol can be used.

The polyester used in the present invention has a glass transition temperature of 50 to 80 ° C.
Is desirable. If the glass transition temperature exceeds 80 ° C, excessive heat energy is required during heat fixing, and the high-speed heat fixing property deteriorates. The number average molecular weight is preferably 2000
~ 20,000, more preferably 3000 ~ 10,000 with a molecular weight of 20
If it is less than 00, the releasability to the heat fixing roller is deteriorated and an offset phenomenon is likely to occur. On the contrary, if it exceeds 20,000, the heat fixing force is lowered together with the increase in the softening point. The acid value of the polyester used is preferably 10 to 100, more preferably 10 to 60. When the acid value is less than 10, the toner obtained is insufficient in offset at the time of heat fixing, and the releasability from the fixing roller becomes poor. On the other hand, when it exceeds 100, the toner obtained has poor fixability or is easily affected by humidity, resulting in poor images under high humidity.

As the binder of the toner of the present invention, other known binder resins may be mixed and used as long as the performance of the present invention is not impaired. For example, there are polyester resins, epoxy resins, styrene-acrylic resins, butyral resins, styrene-butadiene resins and the like which are not included in the present invention.

The alkyl-substituted dicarboxylic acid has 6 to 18 carbon atoms.
Alkyl-substituted succinic acid, maleic acid, fumaric acid, and acid anhydrides thereof can be mentioned. The higher the carbon number of the alkyl, the more effectively the fixing point can be lowered by adding a small amount, but the action is strong. If too much, blocking of the toner occurs in a low temperature range, so that the amount must be strictly within the above range.

As the alkyl-substituted diol, glycols substituted with an alkyl group having 6 to 18 carbon atoms can be equally used.
Especially ethylene glycol is preferable. It has the same effects as those of the alkyl-substituted dicarboxylic acid.

Examples of the charge control agent used in the toner of the present invention include organic metal compounds which are organic salts or complexes containing divalent or higher valent metals. A, Ba, C as effective metal species
Examples include polyvalent compounds such as a, Cd, Co, Dr, Du, Fe, Hg, Mg, Mn, Ni, Pb, Sn, Sr and Zn. As the organometallic compound, carboxylate salts of the above metals, alkoxylates, organometallic complexes, and chelate compounds are effective, and examples thereof include zinc acetate, magnesium acetate, calcium acetate, aluminum acetate,
Magnesium stearate, calcium stearate,
There are aluminum stearate, aluminum isopropoxide, aluminum acetylacetonate, iron (III) acetylacetonate, 3,5 ditertiary butyl chromium stearate and the like, and particularly acetylacetone metal complex and salicylic acid metal salt are preferable. The amount added should not exceed 10% by weight, based on the binder resin. or
Below 0.2%, the substantial effect disappears. The content of the above-mentioned additive is appropriately 0.01 to 40% by weight based on the binder resin.

If necessary, a colorant and a fluidity modifier may be added to the toner of the present invention, and the charge control agent and the fluidity modifier may be mixed (externally added) with the toner and used. Conventionally known dyes and pigments can be used as the colorant, and colloidal silica, fatty acid metal salts and the like can be used as the fluidity modifier.

Further, when it is desired to obtain a magnetic toner, magnetic fine particles may be added to the toner. Does the magnetic substance show magnetism,
Any material that can be magnetized, such as iron, manganese, nickel, cobalt, chromium, and other fine metal powders, various ferrites, alloys and compounds such as manganese, and other ferromagnetic alloys such as magnetite, are conventionally known as magnetic materials. You can use what you have. The content thereof is appropriately 20 to 150% by weight, preferably 30 to 90% by weight, more preferably 40 to 85% by weight, based on the binder resin.

Further, polyolefins such as low molecular weight polyethylene and low molecular weight polypropylene may be added to the toner in order to make the releasing property to the heat fixing roll more complete.

Hereinafter, the present invention will be specifically described with reference to resin production examples, examples, and comparative examples, but these do not limit the present invention in any way. All used parts are parts by weight.

[Polyester Production Example 1] 545 parts of polyoxypropylene (2,5) -2,2-bis (4-hydroxyphenyl) propane were placed in a four-necked flask, and a stirrer, condenser, thermometer, and gas introduction tube were set. And place it in the mantle heater. After purging the inside of the reaction vessel with nitrogen gas, when the content was adjusted to 50 to 60 ° C., 135 parts of terephthalic acid and 77 parts of succinic acid (C ₁₆ H ₃₀ O ₄ ) substituted with an alkyl group of C ₁₂ Then, 38 parts of trimellitic acid is added to make 0.9 equivalent of carboxyl group to 1 equivalent of hydroxyl group. The mixture system is heated to 210 ° C. with stirring. After removing the water of reaction, after about 5 hours, the reaction is followed by measuring the acid value every hour in order to see the end point of the reaction. The reaction is cooled to room temperature when the oxidation is about 30.

[Production Example-2 of Polyester] Polyoxypropylene (2,
5) Put 545 parts of 2,2,2-bis (4-hydroxyphenyl) propane in a flask, replace with nitrogen, and heat at 50 ° C. To this are added 135 parts of isophthalic acid, 77 parts of succinic acid substituted with a C ₁₂ alkyl group, and 38 parts of trimellitic acid, and the mixture is heated and stirred at 210 ° C. to react, and after completion of the reaction, it is cooled to room temperature.

[Production Example-3 of Polyester] Polyoxypropylene was produced in the same manner as in Production Example 1.
545 parts of (2,5) -2,2-bis (4-hydroxyphenyl) propane are put into a flask and the atmosphere is replaced with nitrogen and heated at 50 ° C. To this, 108 parts of terephthalic acid, 24 parts of adipic acid, 77 parts of succinic acid substituted with a C ₁₂ alkyl group, and 38 parts of trimellitic acid are added, and the mixture is heated and stirred at 210 ° C. to react.
After completion of the reaction, it is cooled to room temperature.

[Production Example-4 of Polyester] Polyoxypropylene was produced in the same manner as in Production Example 1.
(2,5) -2,2-bis (4-hydroxyphenyl) propane 436
Parts and 18 parts of glycerin are put into a flask and replaced with nitrogen and heated to 50 ° C. To this, 179 parts of terephthalic acid and 77 parts of succinic acid substituted with a C ₁₂ alkyl group were added, and the mixture was added to
Heat and stir to react at 0 ° C. After completion of the reaction, it is cooled to room temperature.

(Production Example-1 of Comparative Polyester) The acid component of Production Example 1 of polyester was replaced with 185 parts of fumaric acid, and this mixture system was heated and mixed at 210 ° C to remove reaction water. When the acid value reaches 20, the reaction ends and the resin is cooled to room temperature.

(Production Example-2 of Comparative Polyester) In the same manner as in Production Example 1 of polyester, the acid component was replaced with 60 parts of trimellitic acid and 100 parts of maleic anhydride, dehydration condensation was performed, and the reaction was stopped at an acid value of 25, I got polyester.

Example 1 A mixture of 100 parts of polyester of Production Example 1 magnetite (Fe ₃ O ₄ ) 65 parts low molecular weight polypropylene 5 parts acetylacetone iron 2 parts (unit is parts by weight) was heated and kneaded with a roll. After allowing this to cool, it was made into a coarsely pulverized product, finely pulverized by an ultrasonic jet mill, and classified by an air classifier to obtain toner particles having an average diameter of about 13 μm. Colloidal silica (Aerosil R-972) was added to this toner to give a one-component toner. When 2.5 g of this toner was precisely weighed and the softening S-shaped curve was measured by the above flow tester, T ₂ = 165 ° C., T ₁ = 142 ° C., T ₂ −T ₁ =
23, T ₀ = 154 ° C. (softening point), and the toner was in the temperature range of the present invention.

The electrophotographic copying machine (Canon NP-400RE) which has the electrostatic latent image forming step of the one-component developing method, the developing step, the transferring step, and the fixing step by the hot-pressure roller fixing device is further used to check the electrophotographic characteristics. When supplied and subjected to a copy test, sufficient image density and development durability of 50,000 or more sheets were obtained, and no problem in fixing property occurred.
In addition, for the purpose of closely examining the heat fixing property, only the fixing unit of the copying machine was separately prepared, and an unfixed image on a separately prepared transfer paper was subjected to a fixing test by changing the roller set temperature with this separate fixing device. Practical fixing temperature is 10 ° C higher than T _1.
The temperature was high at 152 ° C, the offset phenomenon did not occur in a wide temperature range, and the fixability was excellent. 50 more of this toner
After leaving it in an atmosphere of ℃ for a long time, no blocking or caking was observed. Further, there was no problem with the developability in a high humidity atmosphere and the developability in a low humidity atmosphere.

However, the minimum practical fixing temperature refers to the minimum temperature at which a fixed image that can be practically sufficiently endured can be obtained without cold offset to the heat roller.

Example 2 A toner was obtained in the same manner as in Example 1 except that the linear polyester in Example 1 was replaced with that in Production Example 2.

T ₁ and T ₂ in the flow tester measurement are 118 ° C and 1 respectively.
It was 39 ° C.

The toner obtained was tested in the same manner as in Example 1, and as a result, sufficient image properties, anti-offset properties and storability were exhibited.

By the way, the minimum practical fixing temperature was 136 ° C., and the toner had a fairly good fixing property.

Example 3 Polyester of Production Example 3 100 parts Magnetite (Fe ₃ O ₄ ) 60 parts Polyethylene wax 3 parts Acetylacetone iron 5 parts A mixture was heated and kneaded with a roll. This was coarsely pulverized, finely pulverized, and classified to obtain toner particles of 5 to 20 μm, and colloidal silica was further added. T ₁ at this time,
T ₂ was 165 ° C and 198 ° C. When a copy test was conducted in the same manner as in Example 1, sufficient performance could be confirmed. There was no problem in the fixing test using an external fixing device and the 50 ° C high temperature storage test.

Example 4 In Example 1, except that magnetite which is magnetic powder was removed from the toner compounding method and 8.0 parts of carbon black was added, the same procedure as in Example 1 was followed except that the average particle size was 9.2 after the steps of crushing, crushing and classifying. μ toner was obtained. 20 parts of this toner was mixed with 80 parts of carrier iron powder (Nippon Iron Powder, EFV200 / 300) and supplied to a Canon copier NP-6000 for development test. As a result, the initial image and the 20,000-sheet durability image were sufficient, and the fixability was better than in Example 1. The T ₁ and T ₂ of the toner in the flow tester measurement were 121 ° C. and 143 ° C., which were sufficiently included in the temperature range of the present invention.
Further, the minimum practical fixing temperature by the separate fixing device shown in Example 1 is 139 ° C., which is 18 ° C. higher than T ₁ , and the storage test also showed sufficient performance.

Example 5 A toner was prepared in the same manner as in Example 1 except that 3 parts of chromium 3,5 di-t-butylsalicylate was used instead of 2 parts of iron acetylacetone, and flow tester measurement and electrophotographic property evaluation were conducted. was _{2 -T 1 = 48, T 1} = 134 ℃. Further, the initial image and the durable image were extremely good and had no problem. Further, the same results as in Example 1 were obtained with the fixing test using another fixing device, the storage test and the high humidity test.

Example 6 A toner was obtained in the same manner as in Example 4 except that the polyester of Production Example 4 was used instead of the polyester of Production Example 1. A _{T 2 -T 1 = 14, T} 1 = 121 ℃, actual characteristic goes result of substantially the same satisfaction as in Example 4 were obtained.

Comparative Example 1 A toner was obtained in the same manner as in Example 1 except that only the polyester of Comparative Production Example 2 was used as the polyester. When colloidal silica was added to this toner and a test was conducted in the same manner as in Example 1, sufficient performance was exhibited in initial developability, durability and storability. However, the fixing point in fixing tends to be too high, and it cannot be put to practical use.

The measured values of T ₁ and T ₂ by the flow tester were 183 ° C. and 215 ° C., which were considerably high values.

The minimum practical fixing temperature also exceeds 200 ° C, and it is clear that it is not suitable for high-speed fixing toner.

Comparative Example 2 A toner was produced in the same manner as in Example 5, except that the polyester of Comparative Production Example 1 was used, and colloidal silica was added to obtain a one-component toner. The T ₁ of this toner was as low as 98 ° C., which caused concern about hot offset properties and storage stability.

When the electrophotographic characteristics were tested in the same manner as in Example 1, the hot offset increased with the durability, and the toner deposited and deposited on the heat roller frequently contaminates the transfer paper.

Further, the toner showed a tendency to aggregate during storage, and many granular lumps were generated, so that the toner was not broken by simple vibration.

From these results, it was found that the softening lower limit temperature and the electrophotographic characteristics are clearly correlated.

At this time, T ₂ was 117 ° C.

[Advantages of the Invention] In the electrophotographic toner of the present invention, as described above,
Since the softening lower limit temperature and the softening upper limit temperature are within a specific range, they are excellent in low-temperature fixability, can be fixed by low energy, are particularly suitable for high-speed fixing, prevent offset, and have a wide fixable temperature range. Blocking is hard to occur,
Has excellent durability against repeated use,
A good image is kept stable, and various powder properties such as fluidity are excellent, replenishment and storage properties are good, and there is no adhesion or contamination on the toner holding member or the electrostatic latent image surface. In the two-component developer, there is almost no carrier contamination due to adhesion to the carrier, fusion, etc., and in the one-component magnetic toner, the dispersibility of the magnetic powder is good and the mechanical property of the electrostatic image forming surface is good. It has a good cleaning property of the photosensitive surface by reducing wear. The toner of the present invention is an excellent toner in which various performances required as a toner are balanced as described above, and the industrial significance of the present invention is great.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between the temperature and the plunger drop amount by a flow tester, and clarifies the definitions of the softening lower limit temperature T ₁ , the softening upper limit temperature T ₂ , and the softening point T ₀ . FIG. 2 is a graph showing a comparison of temperature-plunger drop amount curves by a flow tester of different kinds of toner having the same softening point but completely different toner characteristics. FIG. 3 shows the temperature of a toner using a conventional vinyl polymer-
7 is a graph showing a comparison between a plunger drop amount curve (solid line) and a toner temperature-plunger drop amount curve of the present invention (broken line).

Claims (8)

[Claims] 1. An electrical latent image is formed on a photoconductor, the latent image is developed with toner to form a toner image, the toner image is transferred to a transfer material, and the toner image on the transfer material is transferred. A toner for electrophotography used in an image forming method of fixing by thermocompression bonding at a fixing temperature higher than the softening lower limit temperature of the toner by 10 ° C. or more. The toner contains a binder resin and a colorant as main components. The binder resin comprises a polyester resin produced from a raw material having an etherified bisphenol and a dicarboxylic acid, the polyester resin has an acid value of 10 to 100, and the toner has the following condition 10 ≦ T: _2- T ₁ ≦ 60 110 ≦ T ₁ <170 (unit: ° C.) [In the formula, T ₁ represents the softening lower limit temperature of the toner, and T ₂ represents the softening upper limit temperature. ] A toner for electrophotography, characterized by satisfying: 2. The binder resin according to claim 1, wherein the binder resin comprises a polyester resin produced from a raw material having an etherified bisphenol, an aromatic polycarboxylic acid having a valence of 3 or more, and a dicarboxylic acid. Toner for electrophotography. 3. The amount of polycarboxylic acid having a valence of 3 or more in all acid components
The electrophotographic toner according to claim 1 or 2, wherein the content is within 40 mo%. 4. The toner for electrophotography according to claim 1, wherein the toner contains an organometallic compound. 5. An electric latent image is formed on a photoconductor, the latent image is developed with toner to form a toner image, the toner image is transferred to a transfer material, and the toner image on the transfer material is transferred. In the image forming method of fixing by thermocompression bonding, the toner contains a binder resin and a colorant as main components, and the binder resin is a polyester resin produced from a raw material containing etherified bisphenol and dicarboxylic acid. The polyester resin has an acid value of 10 to 100, and the toner has the following conditions: 10 ≦ T ₂ −T ₁ ≦ 60 110 ≦ T ₁ <170 (unit: ° C.) [wherein T ₁ is the toner The softening lower limit temperature is shown, and T ₂ is the softening upper limit temperature. ], The toner image on the transfer material is fixed by heat and pressure under a fixing temperature condition higher than the softening lower limit temperature T ₁ by 10 ° C. or more. 6. The binder resin according to claim 5, wherein the binder resin comprises a polyester resin produced from a raw material having an etherified bisphenol, an aromatic polycarboxylic acid having a valence of 3 or more, and a dicarboxylic acid. Image forming method. 7. The amount of polycarboxylic acid having a valency of 3 or more in all acid components
The image forming method according to claim 5 or 6, which is within 40 mo%. 8. The image forming method according to any one of claims 5 to 7, wherein the toner contains an organometallic compound.