JP2012073303A - Electrophotographic toner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic toner giving good image density, suppressing surface fogging or melt sticking on a blade, and having a wide non-offset range and excellent low temperature fixability.SOLUTION: The electrophotographic toner contains at least a binder resin, poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (denoted by PHBH hereinafter) and a colorant. The proportion of PHBH in the total of the binder resin and the PHBH is from 5 to 50 mass%.

Description

  The present invention relates to an electrophotographic toner.

  Electrophotographic toners used in electrophotography include two-component toners and one-component toners. The two-component toner is a toner composed of an insulating toner containing a binder resin, a colorant and the like and a magnetic carrier. The one-component toner includes a magnetic toner containing a magnetic material and a non-magnetic toner not containing a magnetic material. Generally, the magnetic toner is used for black toner, and the non-magnetic toner is used for black toner and color toner.

  Such toner is required to have excellent low-temperature fixability, no offset at low temperatures, and a wide non-offset width. Further, it is also required to reduce the adhesion to ground fog and the developing blade. Therefore, various studies have been made on toners excellent in these characteristics (for example, see Patent Document 1).

JP 2001-222135 A

        The present invention has been made in view of the above circumstances, and is an electrophotographic toner that has good image density, suppresses fogging to ground fog and blades, wide non-offset width, and excellent low-temperature fixability. Offering is an issue.

As a result of intensive studies, the present inventor has found that the above problem can be solved by blending a specific amount of poly (3-hydroxybutyrate-co-3-hydroxyhexanoate) (hereinafter referred to as PHBH) into the toner. The present invention has been completed.
The toner for electrophotography of the present invention contains at least a binder resin, PHBH, and a colorant, and a ratio of the PHBH in the total of the binder resin and the PHBH is 5 to 50% by mass. It is characterized by.
The electrophotographic toner of the present invention is preferably produced using an open roll type kneader.

  According to the present invention, it is possible to provide an electrophotographic toner that has a good image density, suppresses fusing to ground fog and blades, has a wide non-offset width, and is excellent in low-temperature fixability.

Hereinafter, the present invention will be described in detail.
<Toner for electrophotography>
The electrophotographic toner (hereinafter referred to as toner) of the present invention contains at least a binder resin, PHBH, and a colorant.
Examples of the binder resin include polyester resins, styrene resins, (meth) acrylic resins, styrene- (meth) acrylic copolymer resins, olefin resins (for example, α-olefin resins such as polyethylene and polypropylene) ), Vinyl resins (eg, polyvinyl chloride, polyvinylidene chloride, etc.), polyamide resins, polyether resins, urethane resins, epoxy resins, polyphenylene oxide resins, terpene phenol resins, polylactic acid resins, hydrogenated Rosin, cyclized rubber, thermoplastic polyimide, etc. can be used. Of these, polyester resins are preferred because they are the same type of resin as PHBH and have good dispersibility.

  PHBH is an aliphatic polyester having a repeating structure composed of a 3-hydroxyalkanoate represented by the following formula (1). PHBH is a polymer synthesized by microorganisms using vegetable oil as a main raw material, has biodegradability, and is excellent in environmental compatibility.

[—CHR—CH ₂ —CO—O—] (1)

Here, R is an alkyl group represented by C _n H _{2n + 1} . N is 1 and 3. That is, PHBH is a combination of 3-hydroxybutyrate (also referred to as 3HB) in which n is 1 in formula (1) and 3-hydroxyhexanoate (also referred to as 3HH) in which n is 3. It is a polymer.
The composition ratio of 3-hydroxybutyrate and 3-hydroxyhexanoate in PHBH, that is, 3-hydroxybutyrate / 3-hydroxyhexanoate is 99/1 to 80/20 (mol / mol) Is preferred.

  In the toner of the present invention, the proportion of PHBH is 5 to 50% by mass in a total of 100% by mass of the binder resin and PHBH. By blending PHBH in such a range and using it together with the binder resin, the elasticity of the toner becomes moderate and PHBH is well dispersed in the toner, so that the fusion of the toner to the blade is suppressed. The As a result, it is possible to prevent streak-like color loss of the image and a decrease in image density due to such fusion. In addition, by blending PHBH in such a range, the low-temperature fixability is improved, the non-offset width is widened, and the fixing strength of the image is also improved. When the ratio of PHBH is less than 5% by mass, the elasticity of the toner is insufficient, and when it exceeds 50% by mass, the dispersibility of PHBH decreases.

  The content of the binder resin in the toner is preferably 40 to 95% by mass and particularly preferably 45 to 90% by mass in 100% by mass of the toner. Further, the content of PHBH in the toner is preferably 3 to 50% by mass and particularly preferably 4 to 40% by mass in 100% by mass of the toner.

As the colorant, a black pigment can be used for a black toner, and a magenta pigment, a cyan pigment, a yellow pigment, and the like can be used for a color toner.
Carbon black can be used as the black pigment. Carbon black can be used without being limited by the number average particle diameter, oil absorption, PH, etc., and the following are commercially available products. For example, trade names: REGAL 400, 660, 330, 300, SRF-S, STERING SO, V, NS, and R manufactured by Cabot Corporation of the United States can be given. Moreover, the brand name made from Columbian Carbon Japan: RAVEN H20, MT-P, 410, 420, 430, 450, 500, 760, 780, 1000, 1035, 1060, 1080. In addition, trade names manufactured by Mitsubishi Chemical Corporation: # 5B, # 10B, # 40, # 2400B, MA-100, and the like can be given. These carbon blacks can be used alone or in combination of two or more.

    Examples of the magenta pigment include C.I. I. Pigment Red 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 21, 22, 23, 30, 31, 32, 37, 38, 39, 40, 41, 48, 49, 50, 51, 52, 53, 54, 55, 57, 58, 60, 63, 64, 68, 81, 83, 87, 88, 89, 90, 112, 114, 122, 123, 163, 202, 206, 207, 209; I. Pigment violet 19; C.I. I. Butlet 1, 2, 10, 13, 15, 23, 29, 35, etc. can be used. These magenta pigments can be used alone or in combination of two or more.

    Examples of cyan pigments include C.I. I. Pigment Bull-2, 3, 15, 16, 17; I. Bat Bull-6; I. Acid Bull-45 etc. can be used. These cyan pigments can be used alone or in combination of two or more.

    Examples of yellow pigments include C.I. I. Pigment Yellow-1, 2, 3, 4, 5, 6, 7, 10, 11, 12, 13, 14, 15, 16, 17, 23, 65, 73, 74, 83, 93, 94, 97, 155 180, etc. can be used. These yellow pigments can be used alone or in combination of two or more.

Among these pigments for color toners, magenta pigments are C.I. from the viewpoint of color mixing and color reproducibility. I. Pigment Red 57 and 122 are cyan pigments. I. Pigment Blue 15 is yellow pigment is C.I. I. Pigment Yellow 17, 93, 155, and 180 can be preferably used.
As the pigment for the color toner, a so-called master batch which is dispersed in a high concentration in a resin that can be a binder resin in advance may be used.

The carbon black content in the black toner is preferably in the range of 0.1 to 20% by mass, more preferably 1 to 10% by mass, and still more preferably 1 to 5% in 100% by mass of the black toner. % By mass. When the carbon black content is less than the above range, the image density is lowered, and when it exceeds the above range, the image quality is liable to be lowered, and the toner moldability is also lowered.
In addition to carbon black, black magnetic powder such as iron oxide and ferrite can be used as the black pigment.

    The content of the color toner pigment in the color toner is preferably in the range of 1 to 20% by mass, particularly preferably 4.5 to 8% by mass in 100% by mass of the color toner. When the content of the color toner pigment is less than the above range, the image density is lowered, and when it exceeds the above range, the charging stability is deteriorated and the image quality is liable to be lowered. It is also disadvantageous in terms of cost.

In addition to the binder resin, PHBH, and colorant, a release agent, a charge control agent, magnetic powder, an additive, and the like can be added to the toner as optional components. Hereinafter, each component will be described.
Examples of the release agent include polyolefin waxes such as polyethylene wax, polypropylene wax, polybutene wax and modified polyethylene wax, synthetic waxes such as Fischer-Tropsch wax, paraffin waxes such as natural paraffin, micro wax and synthetic paraffin, and microcrystalline wax. Petroleum wax, carnauba wax, candelilla wax, rice wax, hydrogenated castor oil, acidic olefin wax, maleic acid ethyl ester, maleic acid butyl ester, stearic acid methyl ester, stearic acid butyl ester, palmitic acid cetyl ester, ethylene montanate Ester wax, stearamide, oleic acid made of fatty acid ester such as glycol ester or partially saponified product thereof Bromide, palmitic acid amide, lauric acid amide, behenic acid amide, methylene bis stearamide, amide waxes such as ethylene bis stearamide and the like.

Among these waxes, Fischer-Tropsch wax, acidic olefin wax, ester wax and carnauba wax are suitable, and Fischer-Tropsch wax is particularly suitable. Moreover, these mold release agents can be used individually or in combination of 2 or more types. You may mix the mold release agent from which a softening point (melting | fusing point) differs.
Further, from the softening point, a compound having a relatively low softening point or a low melting point, specifically, a release agent having a softening point (melting point) of 50 to 170 ° C., more preferably 60 to 160 ° C. is preferable. When the softening point is less than 50 ° C., the toner has insufficient blocking resistance and storage stability, and when it exceeds 170 ° C., the fixing start temperature is undesirably increased.

    The content of the release agent is preferably in the range of 0.1 to 10% by mass, preferably 0.5 to 7% by mass, more preferably 1 to 5% by mass in 100% by mass of the toner. It is. If the content of the release agent is less than the above range, the toner release function is insufficient and the toner tends to adhere to the heat fixing roller. As a result, image offset or paper wrapping may occur, resin May become difficult to melt, and the fixing strength of the image may decrease. On the other hand, if the above range is exceeded, the release agent may be detached from the toner, causing blade fusion, or adhering to various members in an image forming apparatus such as a copier or printer. There is a possibility that the quality may deteriorate and the image forming apparatus itself may malfunction.

Examples of the charge control agent include a positive charge control agent and a negative charge control agent.
Examples of positively chargeable charge control agents include modified products of nigrosine and fatty acid metal salts, quaternary ammonium salts such as tributylbenzylammonium-1-hydroxy-4-naphthosulfonate, tetrabutylammonium tetrafluoroborate, Diorganotin oxide such as dibutyltin oxide, dioctyltin oxide, dicyclohexyltin oxide, diorganotin borate such as dibutyltin borate, dioctyltin borate, dicyclohexyltin borate, pyridium salt, azine, triphenylmethane compounds and cationic functional groups And low molecular weight polymers. These positively chargeable charge control agents may be used alone or in combination of two or more. As these positively chargeable charge control agents, nigrosine compounds and quaternary ammonium salts are preferably used.

  Examples of negatively chargeable charge control agents include acetylacetone metal complexes, monoazo metal complexes, organometallic compounds such as naphthoic acid or salicylic acid metal complexes or salts, chelate compounds, and low molecular weight polymers having an anionic functional group. It is done. These negatively chargeable charge control agents can be used alone or in combination of two or more. As these negatively chargeable charge control agents, salicylic acid metal complexes and monoazo metal complexes are preferably used.

    The content of the charge control agent can usually be selected in the range of 0.1 to 5% by mass in 100% by mass of the toner, preferably 0.5 to 4% by mass, and more preferably 1 to 4% by mass. The charge control agent is preferably colorless or light color for color toners.

    When the magnetic toner is used, examples of the magnetic powder include metals such as cobalt, iron, nickel, aluminum, copper, iron, nickel, magnesium, tin, zinc, gold, silver, selenium, titanium, tungsten, zirconium, and others. Metal alloys, metal oxides such as aluminum oxide, iron oxide and nickel oxide, ferrite, magnetite and the like can be used. The addition amount of the magnetic powder is usually 1 to 70% by mass, preferably 5 to 50% by mass, and more preferably 10 to 40% by mass in 100% by mass of the toner. The average particle size of the magnetic powder is preferably 0.01 to 3 μm.

    Examples of additives include stabilizers (for example, UV absorbers, antioxidants, heat stabilizers, etc.), flame retardants, antifogging agents, dispersants, nucleating agents, and plasticizers (phthalate esters, fatty acid plastics). Agents, phosphoric acid plasticizers, etc.), polymer antistatic agents, low molecular antistatic agents, compatibilizers, conductive agents, fillers, fluidity improvers, and one of these as required The above may be added.

An external additive may be attached to the surface of the toner from the viewpoint of imparting fluidity.
As the external additive, inorganic fine particles such as silica, alumina, talc, clay, calcium carbonate, magnesium carbonate, titanium oxide, carbon black powder, and magnetic powder are preferable, and they may be used alone or in combination of two or more. Of inorganic fine particles, silica can be particularly preferably used. Silica is not particularly limited to its average particle diameter, BET specific surface area, surface treatment and the like, and can be appropriately selected according to the use. However, the BET specific surface area is preferably in the range of 50 to 400 m ² / g, and the surface-treated hydrophobic Silica is preferred.

In addition to the inorganic fine particles, a fine resin powder such as polytetrafluoroethylene resin powder or polyvinylidene fluoride resin powder may be used in combination with the toner as an external additive.
When inorganic fine particles or resin fine powder is used as an external additive, the amount thereof can be appropriately selected from the range of 0.01 to 8 parts by mass, preferably 0.1 to 5 parts by mass with respect to 100 parts by mass of the toner. More preferably, it is 0.1-4 mass parts, Most preferably, it is 0.3-3 mass parts. By attaching the external additive within such a range, the fluidity and charging stability of the toner are improved, and a uniform image can be formed.

    The toner of the present invention is not limited to the development method, and can be used for a non-magnetic one-component development method, a magnetic one-component development method, a two-component development method, and other development methods. When the toner for magnetic one-component development is used, the above-described magnetic powder is mixed with the binder resin. When the toner for a two-component development system is used, the toner of the present invention is used by mixing with a carrier. Among these, from the viewpoint of simplicity of the image forming apparatus and cost, it is preferably used as a toner for a non-magnetic one-component development system.

    In the case of the toner for the two-component development system, for example, nickel, cobalt, iron oxide, ferrite, iron, glass beads, etc. can be used as the carrier. These carriers may be used alone or in combination of two or more. The average particle size of the carrier is preferably 20 to 150 μm. Further, the surface of the carrier may be coated with a coating agent such as a fluorine resin, an acrylic resin, or a silicone resin.

    Further, the toner of the present invention may be a monochrome toner (black toner) or a full color toner. The above-mentioned carbon black can be used as a colorant for a non-magnetic toner for monochrome, and the black color of the above-described magnetic powder can be used as a colorant for a magnetic toner for monochrome. Things can be used. In the full-color toner, the above-described color pigment can be used as a colorant.

<Manufacturing method>
The toner of the present invention includes a binder resin, PHBH, and a colorant, a mixing step in which optional components are mixed as necessary, a kneading step in which the mixture obtained in the mixing step is melted and kneaded, and heat melting. And a pulverization and classification step of pulverizing the kneaded product obtained in the kneading step. An optional step of adding an external additive to the pulverized toner may be provided after the pulverization and classification step.

(Mixing process)
In the mixing step, a mixture can be prepared using a mixing device such as a double cone mixer, a V-type mixer, a drum-type mixer, a super mixer, a Henschel mixer, or a Nauter mixer.

(Kneading process)
In the kneading step, the mixture is hot-melt kneaded to uniformly disperse the colorant, PHBH, and optional components in the binder resin to obtain a kneaded product. In the kneading step, a batch type (for example, a pressure kneader, a Banbury mixer, etc.) or a continuous type hot melt kneader may be used. An extruder is preferred. For example, open roll type continuous kneader, KTK type twin screw extruder manufactured by Kobe Steel Co., Ltd., TEM type twin screw extruder manufactured by Toshiba Machine Co., Ltd., twin screw extruder manufactured by Kay Sea Kay Co., Ltd., PCM type manufactured by Ikekai Tekko Co., Ltd. A twin screw extruder, a twin screw extruder manufactured by Kuriyama Seisakusho, a co-kneader manufactured by Buss, etc. are preferred.
Among these, when an open roll type continuous kneader is used, even if PHBH is lower in dispersibility than other polyester resins, it can be uniformly dispersed in the toner.

In the open roll type continuous kneader, two rolls, a front roll and a back roll, are arranged in parallel, and the raw material passes through the gap between the two rolls, and kneading is performed by mechanical shearing force at that time. It is. In addition, this roll has a spiral groove and a lateral groove, and these grooves are provided in the vicinity of the other end of the roll from the action of causing the raw material to bite into the gap between the rolls and the raw material supply unit provided in the vicinity of one end of the roll. There exists an effect | action which accelerates | stimulates conveying a kneaded material to the provided kneaded material discharge | emission part. The raw material can be appropriately supplied not only from the roll end but also from the first half, middle and second half of the roll according to the characteristics of the raw material.
The open roll type continuous kneader can exhibit heating and cooling functions by passing a heating medium such as oil or hot water through the front roll and a cooling medium such as water through the back roll. Thereby, kneading can be performed at an appropriate temperature, and by performing cooling together with kneading, it is not necessary to employ a cooling process as a separate process, and the process can proceed directly to the pulverization process. As an open roll type continuous kneader, Nippon Koke Kogyo "Nedex (trade name)") and the like can be used.

(Crushing classification process)
In the pulverizing and classifying step, the kneaded material in a hot-melt state obtained from the kneader is cooled and solidified, and then pulverized and classified to obtain a classified toner.
The pulverization is performed by coarsely pulverizing with a crusher, hammer mill, feather mill or the like, then finely pulverizing with a jet mill, high-speed rotor rotary mill or the like, and pulverizing to a predetermined toner particle size step by step.
Then, the toner is classified by an inertia class elbow jet, a centrifugal class microplex, a DS separator, a dry air classifier or the like to obtain a classified toner having a volume average particle diameter of 3 to 15 μm.
The coarse powder obtained at the time of classification may be returned to pulverization, and the obtained fine powder may be returned to the kneading step and reused.

(External addition process)
When attaching an external additive to the surface of the toner, a predetermined amount of the classified toner obtained in the pulverization and classification step and the external additive are blended to give a shearing force to powder such as a Henschel mixer or a super mixer. An external addition step of stirring and mixing with a high-speed stirrer (external additive machine) is performed. At this time, heat is generated inside the external additive machine, and aggregates are easily generated. Therefore, it is preferable to adjust the temperature by cooling the periphery of the container part of the external additive machine with water. Furthermore, it is preferable to control the material temperature inside the container of the external additive machine to a management temperature that is about 10 ° C. lower than the glass transition temperature of the binder resin.

  As described above, a toner containing at least a binder resin, PHBH, and a colorant and having a PHBH ratio in the total of the binder resin and PHBH of 5 to 50% by mass specifies PHBH. Since the amount is blended, the image density is good, the adhesion to the ground fog and the blade is suppressed, the non-offset width is wide, and the low-temperature fixability is excellent.

Examples of the present invention will be described below, but the present invention is not limited to these examples.
[Example 1]
(Manufacture of toner)
Using a Henschel mixer (trade name: “Henschel Mixer 20L” manufactured by Mitsui Mining Co., Ltd.), the following components were uniformly mixed for 5 minutes under the condition of 2000 rpm (mixing step). Then, the obtained mixture was melt-kneaded with an open roll type kneader (manufactured by Nippon Coke Kogyo Co., Ltd., trade name: “NIDEX”) (kneading step).
・ Binder resin: 95 parts by mass of polyester resin (Mw 30000, Mn 2500, Tg (shoulder) 60 ° C.)
・ PHBH 5 parts by mass (Mw 400000, Mn 5000, Tg (shoulder) 50 ° C.)
Colorant: 5 parts by mass of carbon black (trade name: “Sunblack200” manufactured by Asahi Carbon Co., Ltd.)
・ Charge control agent: 1 part by mass of iron complex (monoazo metal complex) (trade name: “T-77” manufactured by Hodogaya Chemical Co., Ltd.)
-Mold release agent: 2 parts by mass of Fischer-Tropsch wax (trade name: “FT-100” manufactured by Nippon Seiki Co., Ltd.)
-Mold release agent: 1 part by weight of carnauba wax (trade name: “Carnauba wax No. 2 powder” manufactured by Nippon Wax Co., Ltd.)

Next, the kneaded product was cooled and solidified, and pulverized and classified to obtain a classified toner having a volume average particle diameter of 8 μm (pulverizing and classifying step).
The following external additive consisting of silica was added to 100 parts by mass of the obtained classified toner, and mixed for 5 minutes at a rotation speed of 2500 rpm with a 10 L Henschel mixer to obtain an evaluation toner of Example 1 (outside Attachment process).
-0.7 parts by mass of silica (manufactured by CABOT, average primary particle size 10.5 nm, specific surface area 200 m ² / g)

[Example 2]
An evaluation toner of Example 2 was obtained in the same manner as in Example 1 except that the binder resin was changed from 95 parts by mass to 75 parts by mass and PHBH was changed from 5 parts by mass to 25 parts by mass.

[Example 3]
An evaluation toner of Example 3 was obtained in the same manner as in Example 1 except that the binder resin was changed from 95 parts by mass to 50 parts by mass and PHBH was changed from 5 parts by mass to 50 parts by mass.

[Comparative Example 1]
A toner for evaluation of Comparative Example 1 was obtained in the same manner as in Example 1 except that the binder resin was changed from 95 parts by mass to 100 parts by mass and that PHBH was not added.

[Comparative Example 2]
A toner for evaluation of Comparative Example 2 was obtained in the same manner as in Example 1 except that the binder resin was changed from 95 parts by mass to 45 parts by mass and PHBH was changed from 5 parts by mass to 55 parts by mass.

[Comparative Example 3]
A toner for evaluation of Comparative Example 3 was obtained in the same manner as in Example 1 except that 5 parts by mass of a polyester resin having an Mw peak top of 5000 was used instead of PHBH.

Table 1 shows the blending amounts of the binder resin and PHBH in Examples and Comparative Examples.

<Evaluation 1>
Each toner for evaluation in Examples and Comparative Examples is filled in a cartridge, and a printing test up to 3000 sheets is performed with a commercially available non-magnetic one-component developing type printer at a printing rate of 5% and a printing speed of 30 pages / min. Carried out.
At this time, the temperature of the fixing roll of the printer was set to 170 ° C.
Then, the image density and fogging at the initial stage when the printing durability test was performed and at the time of printing 3000 sheets were evaluated as follows. In addition, the presence or absence of toner fusion to the developing blade after printing durability was confirmed visually.
The results are shown in Table 2.
(Image density)
The density of a solid image of 25 mm × 25 mm was measured with a reflection densitometer (manufactured by Macbeth, trade name: RD914).
(Ground fog)
Using a whiteness meter (manufactured by Nippon Denshoku Industries Co., Ltd., trade name: ColorMeter2000), the difference between the whiteness of the non-image area at the time of the printing test and the whiteness before the printing test is calculated as the value of the background fog. did.

As shown in Table 2, in each example, a decrease in image density due to the printing durability test, toner fusion to the developing blade after the printing durability test was not observed, and the background fogging value was good, and the long There was no problem with the actual machine characteristics.
On the other hand, in Comparative Example 2, blade fusion occurred at the time of printing 1000 sheets, and streak-like white spots in the image and a decrease in image density were recognized. Since the toner for evaluation of Comparative Example 2 has an excessive PHBH content, the dispersion of each component in the toner is insufficient, and as a result, it is presumed that the occurrence of blade fusion was promoted.
In Comparative Example 3, blade fusion occurred at the time of printing 2500 sheets, and streaky white spots in the image and a decrease in image density were observed. The toner for evaluation of Comparative Example 3 is presumed to have blade fusion due to insufficient elasticity.

<Evaluation 2>
(Fixing test)
Uses an external fixing machine. 200 mm / sec. Paper basis weight: 65 g / m ² .
Mn—Mg—Sr ferrite with an average particle size of 35 μm coated with acrylic resin (PMMA) was used as a carrier (composition was Fe ₂ O ₃ : MnO: MgO: SrO = 73: 23: 3.5: 0.5, resin The developer was prepared with a coating ratio of 1.5% by mass) and a mixing ratio with the toner: carrier = toner = 93% by mass: 7% by mass.
Using this developer, a strip-shaped unfixed image having a length of 3 cm and a width of 6 cm was produced on A4 transfer paper by a commercially available copying machine (SF-9800, manufactured by Sharp Corporation). The toner adhesion amount on the transfer paper was adjusted to about 1.6 mg / cm ² depending on the toner density, the surface potential of the photoreceptor, the development potential, the exposure amount, the transfer conditions, and the like.
Next, a fixing machine in which a heat fixing roll whose surface layer is made of polytetrafluoroethylene and a pressure fixing roll whose surface layer is made of silicone rubber rotates in a pair, a roll pressure is 1 kgf / cm ² , The roll speed was adjusted to 100 mm / sec, and the surface temperature of the heat fixing roll was increased stepwise from 100 to 220 ° C. at intervals of 5 ° C., and the above-mentioned unfixed image was held at each surface temperature. The toner image on the transfer paper was fixed.
At the time of fixing, observation was made as to whether or not the transfer paper having an unfixed image was wound around the surface of the heat fixing roll, and the low temperature side winding generation temperature and the high temperature side winding generation temperature were confirmed.
At the same time, it was observed whether or not toner contamination occurred in the blank portion, and a temperature region where the contamination did not occur was defined as a non-offset temperature region.
Further, the fixing strength, that is, the fixing strength when fixing at 150 ° C., 170 ° C., and 190 ° C. was derived as follows.
The surface temperature of the heat fixing roll of the fixing machine was set to 150 ° C., 170 ° C., and 190 ° C., respectively, and the toner image patches with different amounts of adhesion on paper were fixed. Then, after measuring the image density of the formed fixed image using a spectral color difference meter (product name: 939, manufactured by X-rite), the fixed image is applied with a sand eraser while applying a weight of 1 kg. Then, the image density was measured in the same manner. The fixing strength was calculated from the obtained measurement value according to the following formula, and the portion where the image density was most drastically decreased was defined as the minimum remaining rate.
Minimum remaining rate (%) = (image density of fixed image after rubbing / image density of fixed image before rubbing) × 100
The results are shown in Table 3.

As shown in Table 3, in Example 1, a sufficient non-offset width and fixing strength were obtained. In Example 2 and Example 3, although not as high as Example 1, practically inferior fixing characteristics were obtained.
On the other hand, in Comparative Example 1 and Comparative Example 3, both the low temperature side and the high temperature side of the non-offset width were narrowed, and the minimum remaining rate was also poor compared to Examples 1-3.
In Comparative Example 2, there was no non-offset width.

  According to the present invention, it is possible to provide a toner having a good image density, suppressed fogging to ground fog and blades, a wide non-offset width, and low-temperature fixability. This toner has excellent compatibility with the environment.

Claims (2)

Containing at least a binder resin, poly (3-hydroxybutyrate-co-3-hydroxyhexanoate) (hereinafter referred to as PHBH), and a colorant;
The toner for electrophotography, wherein a ratio of the PHBH in the total of the binder resin and the PHBH is 5 to 50% by mass.   2. The toner for electrophotography according to claim 1, wherein the toner is produced using an open roll type kneader.