JP2013199555A - Polyester resin for toner, toner, developer, toner cartridge, process cartridge, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyester resin for a toner, which can prevent the toner from being crushed due to stirring in a developer and is suitable for the toner.SOLUTION: A polyester resin for a toner is a crosslinked product of: a polycondensate of dialcohol that contains dicarboxylic acid and a rosin skeleton; and a compound that contains a crosslinkable group having three or more organic functions.

Description

  The present invention relates to a polyester resin for toner, a toner, a developer, a toner cartridge, a process cartridge, and an image forming apparatus.

  A method of visualizing image information through a process of forming an electrostatic latent image and developing it, such as electrophotography, is currently used in various fields. In this method, the entire surface of the photosensitive member (latent image holding member) is charged, and then the surface of the photosensitive member is exposed to laser light according to image information to form an electrostatic latent image. Next, the electrostatic latent image is developed with a developer containing toner to form a toner image, and finally the toner image is transferred and fixed on the surface of the recording medium.

The following are known as binder resins contained in toner applied to the electrophotographic method as described above.
For example, Patent Document 1 discloses a resin using rosin glycidyl ester, dicarboxylic acid or dicarboxylic anhydride, and a polyfunctional epoxy compound.
Patent Document 2 discloses a resin using a disproportionated rosin, a tertiary fatty acid glycidyl ester, terephthalic acid or isophthalic acid, an aliphatic diol, and a trivalent or higher carboxylic acid or alcohol as a crosslinking component. .
Further, Patent Document 3 discloses a resin comprising a disproportionated rosin, a tertiary fatty acid glycidyl ester, terephthalic acid or isophthalic acid, an aliphatic diol, and a polyvalent isocyanate compound as a crosslinking component.
In addition, Patent Document 4 discloses a resin comprising a reaction product of a polyvalent epoxy compound and rosin, a polyhydric alcohol, a polybasic acid, and a lower alkyl ester.

JP 2001-142260 A JP 2004-205822 A JP 2006-3680 A JP 2007-248704 A

  An object of the present invention is to provide a polyester resin for a toner suitable for a toner capable of suppressing crushing caused by stirring in a developing device.

That is, the invention according to claim 1
It is a polyester resin for toner which is a cross-linked product of a polycondensate of a dialcohol containing a dicarboxylic acid and a rosin skeleton and a compound containing a trifunctional or higher functional crosslinkable group.

The invention according to claim 2
The polyester resin for toner according to claim 1, wherein the compound containing a trifunctional or higher functional crosslinkable group is a polyvalent carboxylic acid or a polyhydric alcohol.

  The toner according to claim 1, wherein the molecular weight distribution (Mw / Mn) obtained from the weight average molecular weight Mw and the number average molecular weight Mn is from 10.0 to 15.0. Polyester resin.

The invention according to claim 4
A toner comprising the polyester resin for toner according to any one of claims 1 to 3.

The invention according to claim 5
A developer comprising the toner according to claim 4.

The invention according to claim 6
Storing the toner according to claim 4;
The toner cartridge is detachable from the image forming apparatus.

The invention according to claim 7 provides:
A developer that stores the developer according to claim 5 and that develops an electrostatic latent image formed on the surface of the latent image holding member with the developer to form a toner image,
It is a process cartridge that can be attached to and detached from the image forming apparatus.

The invention according to claim 8 provides:
A latent image carrier,
Charging means for charging the surface of the latent image carrier;
An electrostatic latent image forming means for forming an electrostatic latent image on the surface of the latent image holding member;
Development means for containing the developer according to claim 5 and developing the electrostatic latent image with the developer to form a toner image;
Transfer means for transferring the toner image to a recording medium;
Fixing means for fixing the toner image on the recording medium;
An image forming apparatus.

  According to the invention of claim 1, compared to the case where the polycondensate of a dialcohol containing a dicarboxylic acid and a rosin skeleton and a compound containing a trifunctional or higher functional crosslinkable group is not a cross-linked product, A toner polyester resin suitable for a toner capable of suppressing crushing due to stirring in the toner is provided.

  According to the second aspect of the present invention, compared to the case where the compound containing a trifunctional or higher functional crosslinkable group is a compound other than a polyvalent carboxylic acid and a polyhydric alcohol, crushing by stirring in the developing device is performed. Provided is a polyester resin for toner that is suitable for a suppressable toner.

  According to the invention of claim 3, the toner capable of suppressing crushing due to stirring in the developing device as compared with the case where the molecular weight distribution (Mw / Mn) does not satisfy the range of 10.0 to 15.0. A polyester resin suitable for toner is provided.

  According to the fourth aspect of the present invention, a toner in which crushing due to stirring in the developing device is suppressed can be obtained as compared with the case where the present configuration is not provided.

  According to the fifth aspect of the present invention, there can be obtained a developer containing toner in which crushing due to stirring in the developing device is suppressed as compared with the case where the present configuration is not provided.

  According to the sixth aspect of the present invention, there can be obtained a toner cartridge that stores toner in which crushing due to agitation in the developing device is suppressed as compared with the case without this configuration.

  According to the seventh aspect of the present invention, compared with the case where the present configuration is not provided, the developer containing toner in which crushing due to stirring in the developing device is suppressed can be easily handled, and image formation with various configurations can be performed. Adaptability to the device can be improved.

  According to the eighth aspect of the present invention, there is provided an image forming apparatus using a developer containing toner in which crushing due to agitation in the developing device is suppressed as compared with the case where this configuration is not provided.

It is a figure explaining the state of a screw about an example of a screw extruder used for manufacture of toner concerning this embodiment. 1 is a schematic configuration diagram illustrating an example of an image forming apparatus according to an exemplary embodiment. It is a schematic block diagram which shows an example of the process cartridge which concerns on this embodiment.

  Hereinafter, embodiments of the polyester resin for toner, toner, developer, toner cartridge, process cartridge, and image forming apparatus of the present invention will be described in detail.

<Polyester resin for toner>
The polyester resin for toner according to this embodiment (hereinafter sometimes referred to as “specific polyester”) includes a polycondensate of a dialcohol containing a dicarboxylic acid and a rosin skeleton, and a compound containing a trifunctional or higher functional crosslinkable group. A polyester resin for toner, which is a cross-linked product of

The specific polyester having the structure as described above can suppress crushing of the toner due to stirring in the developing device when applied to the toner.
In general, a polyester resin used as a binder resin for a toner often uses bisphenol A or a derivative thereof as an alcohol component.
On the other hand, as shown in Patent Documents 1 to 4, those in which a rosin skeleton is introduced into a polyester resin are known, and those containing this rosin skeleton as a repeating unit derived from an alcohol component are also known.
The alcohol component containing a rosin skeleton is often obtained by reacting rosin with a glycidyl ester. In this case, the site adjacent to the hydroxyl group used in the polycondensation reaction contains an aliphatic structure. As a result, there is a problem that the hardness of the resin itself is lower than that of a polyester resin using an alcohol component in which an aromatic group is present adjacent to a hydroxyl group, such as bisphenol A described above.
The toner using such a polyester resin lacks the strength of the toner itself, and is crushed by stirring over a long period in the developing machine, causing image smearing in the non-image area (white area), In some cases, image stability over a long period of time could not be obtained.

Therefore, in the polyester resin for toner according to this embodiment, even if the polyester resin uses a dialcohol containing a rosin skeleton, the resin itself can be obtained by forming a crosslinked product with a compound having a trifunctional or higher functional crosslinkable group. It compensates for the brittleness.
Moreover, there exists an advantage that the viscoelasticity of resin can be adjusted by setting it as a crosslinked material.
In particular, when a polyvalent carboxylic acid or a polyhydric alcohol is used as the compound having a trifunctional or higher functional crosslinkable group, the acid value can be easily adjusted in addition to the viscoelasticity of the resin.

[Polycondensate constituting specific polyester]
Hereinafter, the polycondensate constituting the specific polyester will be described first.
Such a polycondensate is a polycondensate of a dicarboxylic acid and a dialcohol containing a rosin skeleton (hereinafter sometimes referred to as “rosin diol”).

(Dicarboxylic acid)
In this embodiment, as dicarboxylic acid, at least 1 sort (s) chosen from the group which consists of aromatic dicarboxylic acid and aliphatic dicarboxylic acid can be used. Specifically, for example, aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, 1,4-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid; oxalic acid, malonic acid, maleic acid, fumaric acid, Citraconic acid, Itaconic acid, Glutaconic acid, Succinic acid, Adipic acid, Sebacic acid, Azelaic acid, Dimer acid, Alkyl succinic acid having 1 to 20 carbon atoms having a branched chain, 1 to 20 carbon atoms having a branched chain And aliphatic dicarboxylic acids such as alkenyl succinic acid having an alkenyl group; anhydrides of these acids; and alkyl (1 to 3 carbon atoms) esters of these acids; and the like. Among these, aromatic carboxylic acids are preferable from the viewpoints of toner durability, fixability, and colorant dispersibility.

(Dialcohol containing rosin skeleton (rosin diol))
The rosin in the “dialcohol containing rosin skeleton (rosin diol)” in the present embodiment is a general term for resin acids obtained from trees, and the main component is abietic acid which is one of tricyclic diterpenes and its It is a substance derived from natural products including isomers. Specific components include, for example, parastrinic acid, neoabietic acid, pimaric acid, dehydroabietic acid, isopimaric acid, sandaracopimalic acid in addition to abietic acid, and the rosin used in this embodiment is a mixture thereof. is there.
Rosin is roughly classified into three types according to the collection method: tall rosin with pulp as raw material, gum rosin with raw pine oil as raw material, and wood rosin with raw material as pine stump. Gum rosin and / or tall rosin is preferred because rosin used in this embodiment is easily available.
These rosins are preferably purified. A purified rosin can be obtained by removing a high-molecular-weight product considered to have arisen from a peroxide of a resin acid from unpurified rosins and an unsaponified product contained in the unpurified rosins. The purification method is not particularly limited, and various known purification methods can be selected. Specifically, methods such as distillation, recrystallization, extraction and the like can be mentioned. Industrially, purification by distillation is preferably performed. The distillation is usually selected in consideration of the distillation time at a pressure of 200 ° C. or more and 300 ° C. or less and 6.67 kPa or less. The recrystallization is performed, for example, by dissolving unpurified rosin in a good solvent and then distilling off the solvent to obtain a concentrated solution, and adding a poor solvent to the solution. Good solvents include aromatic hydrocarbons such as benzene, toluene and xylene, chlorinated hydrocarbons such as chloroform, alcohols such as lower alcohols, ketones such as acetone, and acetates such as ethyl acetate. Examples of the poor solvent include hydrocarbon solvents such as n-hexane, n-heptane, cyclohexane, and isooctane. Extraction can be performed by, for example, converting an unpurified rosin into an alkaline aqueous solution using alkaline water, extracting an insoluble unsaponified product contained therein with an organic solvent, and then neutralizing the aqueous layer to purify the purified rosin. Is the way to get.

The rosin used in this embodiment may be a disproportionated rosin. Disproportionated rosin is a rosin containing abietic acid as a main component heated at high temperature in the presence of a disproportionation catalyst to eliminate unstable conjugated double bonds in the molecule. A mixture of dehydroabietic acid and dihydroabietic acid.
Examples of the disproportionation catalyst include various known catalysts such as supported catalysts such as palladium carbon, rhodium carbon, and platinum carbon, metal powders such as nickel and platinum, and iodides such as iodine and iron iodide.

  The rosin used in this embodiment may be a hydrogenated rosin for the purpose of eliminating unstable conjugated double bonds in the molecule. About hydrogenation reaction, well-known hydrogenation reaction conditions can be selected suitably. That is, it is carried out by heating rosin under hydrogen pressure in the presence of a hydrogenation catalyst. Examples of the hydrogenation catalyst include various known catalysts such as supported catalysts such as palladium carbon, rhodium carbon and platinum carbon, metal powders such as nickel and platinum, and iodides such as iodine and iron iodide.

  These disproportionated rosin and hydrogenated rosin may be provided with the purification step before and after the disproportionation treatment or the hydrogenation treatment.

As the dialcohol (rosin diol) containing the rosin skeleton as described above, for example, a compound synthesized by a known method from rosin and an epoxy compound may be used.
Specific examples of the rosin diol include compounds represented by the following general formula (1).

In the general formula (1), R ¹ and R ² each independently represent hydrogen or a methyl group. L ¹ , L ² , and L ³ are each independently a carbonyl group, an ester group, an ether group, a sulfonyl group, a chain alkylene group that may have a substituent, or a cyclic alkylene that may have a substituent. Represents a divalent linking group selected from the group consisting of a group, an arylene group which may have a substituent, and combinations thereof, and L ¹ and L ² or L ¹ and L ³ form a ring; Also good. A ¹ and A ² represent a rosin ester group.
Here, the rosin ester group refers to a residue obtained by removing a hydrogen atom from a carboxyl group contained in rosin.

Examples of the chain alkylene group represented by L ¹ , L ² , and L ³ include alkylene groups having 1 to 10 carbon atoms.
Examples of the cyclic alkylene group represented by L ¹ , L ² , and L ³ include cyclic alkylene groups having 3 to 7 carbon atoms.
Examples of the arylene group represented by L ¹ , L ² , and L ³ include a phenylene group, a naphthylene group, and an anthracene group.

  Examples of the substituent introduced into the chain alkylene group, cyclic alkylene group, and arylene group include an alkyl group having 1 to 8 carbon atoms, an aryl group, and the like, and a linear, branched, or cyclic alkyl group is preferable. Specifically, methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, isopropyl group, isobutyl group, s-butyl group, t-butyl group, isopentyl group, neopentyl group 1-methylbutyl group, isohexyl group, 2-ethylhexyl group, 2-methylhexyl group, cyclopentyl group, cyclohexyl group, phenyl group and the like.

The compound represented by the general formula (1) is a dialcohol compound containing two rosin ester groups in one molecule (hereinafter, referred to as “specific rosin diol”).
Since the rosin that is the base of the rosin ester group contained in the specific rosin diol has a bulky structure and high hydrophobicity, the polyester resin containing the rosin ester group (specific polyester) is difficult to contain water. In addition, because of the structure of the polyester resin, a hydroxyl group or a carboxyl group exists only at the end of the resin molecule, so that the rosin in the resin does not increase the amount of the hydroxyl group or carboxyl group that may adversely affect the chargeability of the toner. The amount of ester groups can be increased. Furthermore, when the specific rosin diol is obtained by reacting rosin with a bifunctional epoxy compound, the ring opening reaction of the epoxy group occurring between the epoxy group in the bifunctional epoxy compound and the carboxyl group in the rosin is an alcohol component. Since the reactivity is higher than the esterification reaction that occurs between rosin and rosin, unreacted rosin hardly remains in the polyester resin (specific polyester).

  Below, an example of the synthetic scheme of the polycondensate which comprises specific polyester which concerns on this embodiment is shown. In the following synthesis scheme, a specific rosin diol is synthesized by reacting a bifunctional epoxy compound with rosin, and the specific rosin diol and dicarboxylic acid are subjected to dehydration polycondensation to constitute the specific polyester according to the present embodiment. A polycondensate is synthesized. In the structural formula representing the polycondensate, a portion surrounded by a dotted line corresponds to a rosin ester group.

When the polycondensate is hydrolyzed, it is decomposed into the following monomers. Since this polycondensate is a 1: 1 condensate of dicarboxylic acid and diol, the constituent components of the resin can be estimated from the decomposition product.
Similarly, for a cross-linked product of such a polycondensate and a trifunctional compound containing a crosslinkable group, the constituent component can be estimated by applying the resin component of the decomposed product to a chemical analyzer such as a mass spectrum. .

Next, a method for synthesizing the specific rosin diol represented by the general formula (1) will be specifically described.
The specific rosin diol represented by the general formula (1) can be synthesized by a known method, for example, by a reaction between an epoxy compound and rosin.
The epoxy compound that may be used in the present embodiment is a bifunctional epoxy compound containing two epoxy groups in one molecule, and is an aromatic diol diglycidyl ether, an aromatic dicarboxylic acid diglycidyl ether, or aliphatic. Examples include diglycidyl ethers of diols, diglycidyl ethers of alicyclic diols, and alicyclic epoxides.

  Representative examples of diglycidyl ethers of aromatic diols include bisphenol A derivatives such as bisphenol A and polyalkylene oxide adducts of bisphenol A as aromatic diol components, polyalkylene oxide adducts of bisphenol F and bisphenol F, etc. Bisphenol F derivatives, bisphenol S, bisphenol S derivatives such as polyalkylene oxide adducts of bisphenol S, resorcinol, t-butylcatechol, biphenol and the like.

  Representative examples of diglycidyl ethers of aromatic dicarboxylic acids include terephthalic acid, isophthalic acid, phthalic acid and the like as the aromatic dicarboxylic acid component.

  Representative examples of diglycidyl ethers of aliphatic diols include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol as the aliphatic diol component, Examples include 1,6-hexanediol, neopentyl glycol, 1,9-nonanediol, diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol, and polytetramethylene glycol.

  Representative examples of diglycidyl ethers of alicyclic diols include hydrogenated bisphenol A as a cycloaliphatic diol component, hydrogenated bisphenol A derivatives such as polyalkylene oxide adducts of hydrogenated bisphenol A, cyclohexanedimethanol, and the like. Can be mentioned.

  A representative example of the alicyclic epoxide is limonene dioxide.

  The epoxy group-containing compound can be obtained by, for example, a reaction of a diol component and epihalohydrin, but can be polycondensed and can have a high molecular weight depending on the amount ratio.

  In this embodiment, the reaction between rosin and the bifunctional epoxy compound proceeds mainly by a ring-opening reaction between the carboxyl group of rosin and the epoxy group of the bifunctional epoxy compound. At that time, the reaction temperature is preferably higher than the melting temperature of both components and / or at a temperature at which uniform mixing is possible, and specifically, a range of 60 ° C. or higher and 200 ° C. or lower is common. In the reaction, a catalyst for promoting the ring-opening reaction of the epoxy group may be added.

  Examples of the catalyst that can be used include amines such as ethylenediamine, trimethylamine, and 2-methylimidazole, quaternary ammonium salts such as triethylammonium bromide, triethylammonium chloride, and butyltrimethylammonium chloride, and triphenylphosphine.

  The reaction can be carried out by various methods. In general, in the case of a batch system, rosin and 2 are added to a heatable flask equipped with a condenser, a stirrer, an inert gas inlet, a thermometer and the like at a predetermined ratio. The progress of the reaction can be traced by charging a functional epoxy compound, heating and melting it, and sampling the reactant appropriately. The degree of progress of the reaction can be confirmed mainly by a decrease in the acid value, and the reaction can be appropriately completed when the reaction reaches the stoichiometric end point or the vicinity thereof.

  The reaction ratio of rosin and bifunctional epoxy compound is not particularly limited, but the molar ratio of rosin and bifunctional epoxy compound is 1.5 mol or more and 2.5 mol or less of rosin with respect to 1 mol of bifunctional epoxy compound. It is preferable to make it react in the range.

  Examples of specific rosin diols that can be suitably used in the present embodiment are shown below, but the present embodiment is not limited thereto.

  In the exemplary compound of the specific rosin diol, n represents an integer of 1 or more.

  In synthesizing the polycondensate constituting the specific polyester according to this embodiment, other dialcohol components other than the specific rosin diol may be used in combination as the dialcohol. The content of the specific rosin diol in the present embodiment is preferably 10 mol% or more and 100 mol% or less, more preferably 20 mol% or more and 90 mol% or less in the dialcohol component from the viewpoint of chargeability.

As the alcohol component other than the specific rosin diol, at least one selected from the group consisting of an aliphatic diol and an etherified diphenol can be used within a range that does not deteriorate the performance when applied to the toner.
Examples of the aliphatic diol include, for example, ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3 -Butanediol, 1,4-butenediol, 2-methyl-1,3-propanediol, 1,5-pentanediol, neopentyl glycol, 2-ethyl-2-methylpropane-1,3-diol, 2- Butyl-2-ethylpropane-1,3-diol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 2-ethyl-1,3-hexanediol, 2,4-dimethyl-1, 5-pentanediol, 2,2,4-trimethyl-1,3-pentanediol, 1,7-heptanediol, 1,8-octanediol, 1, -Nonanediol, 1,10-decanediol, 3-hydroxy-2,2-dimethylpropyl-3-hydroxy-2,2-dimethylpropanoate, diethylene glycol, triethylene glycol, polyethylene glycol, dipropylene glycol, polypropylene glycol Etc. These aliphatic diols may be used alone or in combination of two or more.
Moreover, in this embodiment, you may further use etherified diphenol with aliphatic diol. Etherified diphenol is a diol obtained by addition reaction of bisphenol A and alkylene oxide. The alkylene oxide is ethylene oxide or propylene oxide, and the average added mole number of alkylene oxide is 1 mol of bisphenol A. It is preferably 2 mol or more and 16 mol or less.

The polycondensate constituting the specific polyester according to the present embodiment is obtained by known and conventional polycondensation using the above-described dicarboxylic acid and a dialcohol containing the specific rosin diol as raw materials.
As the reaction method, either a transesterification reaction or a direct esterification reaction can be applied. Further, polycondensation can be promoted by a method of increasing the reaction temperature by pressurization, a pressure reduction method, or a method of flowing an inert gas under normal pressure. Depending on the above reaction, a known and commonly used reaction catalyst such as at least one metal compound selected from antimony, titanium, tin, zinc, aluminum and manganese may be used to accelerate the reaction. The addition amount of these reaction catalysts is preferably 0.01 parts by mass or more and 1.5 parts by mass or less, and more preferably 0.05 parts by mass or more and 1.0 parts by mass or less with respect to 100 parts by mass of the total amount of the acid component and the alcohol component. preferable. The reaction temperature can be 180 ° C to 300 ° C.

[Compound containing trifunctional crosslinkable group constituting specific polyester]
Then, the compound (henceforth a crosslinking agent) which contains the crosslinkable group which comprises specific polyester which concerns on this embodiment by trifunctional is demonstrated.
As such a crosslinking agent, at least one selected from the group consisting of polyvalent carboxylic acids, polyhydric alcohols, polyvalent isocyanates, and ionomers is desirable from the viewpoint of polycondensation with the polyester terminal. Among these, from the viewpoints of reaction controllability and molecular weight controllability, polyvalent carboxylic acids and polyhydric alcohols are preferable, and polyvalent carboxylic acids are particularly preferable.
That is, the crosslinkable group in the crosslinker is “carboxyl group”, “alcoholic hydroxyl group”, “isocyanate group”, “ionic crosslinkable group”, and a compound having these crosslinkable groups having three or more valences is used in the present embodiment. It becomes a crosslinking agent.

(Polyvalent carboxylic acid: trivalent or higher carboxylic acid)
As the polyvalent carboxylic acid as the crosslinking agent, that is, a trivalent or higher carboxylic acid, trimellitic acid is preferable from the viewpoint of reactivity and the like.

(Polyhydric alcohol: Trihydric or higher alcohol)
Examples of the polyhydric alcohol that is a crosslinking agent, that is, a trihydric or higher alcohol, include glycerol, diglycerol, sulfitol, sorbitan, butanetriol, trimethylolethane, trimethylolpropane, and pentathritol. From the viewpoint of controllability, glycerol is preferred. These may be used alone or in combination of two or more.

(Polyisocyanate: Trivalent or higher isocyanate)
The polyvalent isocyanate compound as a cross-linking agent, that is, a trivalent or higher isocyanate, is based on the hydroxyl group of a polyol such as triphenylmethane-4,4 ′, 4 ″ -triisocyanate, trimethylolpropane, hexanetriol or the like. Examples include adducts obtained by reacting an excess amount of a polyisocyanate compound with an excess amount of isocyanate groups.

(Ionomer)
As an ionomer used as a crosslinking agent, an unsaturated carboxylic acid (for example, acrylic acid or methacrylic acid) is used, and ionic crosslinking is performed by a carboxyl group derived from the unsaturated carboxylic acid and a polyvalent metal ion. An ionomer having a structure is used.
In order to introduce the ionic cross-linking structure as described above, a polyvalent metal compound may be reacted with a carboxyl group derived from an unsaturated carboxylic acid in the polymer. Coordination bonds (ionic bonds) are formed, and an ionic cross-linked structure is formed. Examples of suitable polyvalent metal compounds include alkaline earth metals, zinc group metal acetates and oxides.
Specific polyester containing ionomer is a polyester resin containing ionomer, in which about 20% to 80% of carboxyl groups are neutralized with a polyvalent metal such as zinc, cobalt, nickel, aluminum, or copper (II). Is mentioned.
As described above, the specific polyester into which the ionic cross-linked structure is introduced is less brittle and exhibits toughness at room temperature. As a result, such a toner containing the specific polyester is advantageous in that it is not crushed by stress caused by agitation in the developing unit and does not cause the external additive to be buried.

(Crosslinking method)
The specific polyester according to this embodiment may be obtained by, for example, subjecting a specific rosin diol and a carboxylic acid to polycondensation, and adding an amount for a cross-linking reaction at the end of the polycondensation to crosslink.
That is, since the structure between the specific rosin diol and the carboxylic acid is bulky, the crosslinking agent is preferably added afterwards in order to efficiently promote the crosslinking reaction.

(Crosslinking conditions)
The content of the various crosslinking agents described above is desirably 0.05 parts by mass or more and 5 parts by mass or less (more preferably 0.1 parts by mass or more and 3 parts by mass or less).
When the content of the cross-linking agent is 0.05 parts by mass or more, when the specific polyester is applied to the toner, it contributes to an improvement in the brittleness of the toner itself, and the crushing of the toner can be suppressed.
In addition, when the toner is produced using the specific polyester when the amount is 5 parts by mass or less, it is difficult to pulverize when pulverizing, and the insoluble content in the solvent does not increase during emulsification. When the toner is fixed, it does not become difficult to melt and cause a fixing failure.

[Physical properties of specific polyester]
The specific polyester according to this embodiment preferably has a molecular weight distribution (Mw / Mn) determined from the weight average molecular weight Mw and the number average molecular weight Mn of 1.5 to 15.0, preferably 3 to 12. More preferably, it is 5 or more and 10 or less.
In particular, the molecular weight distribution (Mw / Mn) is preferably 10.0 or more and 15.0 or less from the viewpoint of suppressing the crushing of toner due to stirring in the developing device.
This molecular weight distribution can be adjusted by the amount of the crosslinking agent and the polymerization temperature.

In addition, the weight average molecular weight (Mw) of the specific polyester according to this embodiment is 4,000 or more and 1,000,000 or less from the viewpoint of durability and hot offset resistance when used as a binder resin for toner. Is preferable, and 7,000 to 300,000 is more preferable.
In addition, the weight average molecular weight Mw, the number average molecular weight Mn of specific polyester, and the molecular weight distribution (Mw / Mn) calculated | required from these are calculated | required by the method described in the Example.

*
The softening temperature of the specific polyester according to this embodiment is preferably 80 ° C. or higher and 160 ° C. or lower, and 90 ° C. or higher and 150 ° C., from the viewpoint of toner fixing property, storage stability, and durability when used as a toner binder resin. More preferably, it is not higher than ° C.
The glass transition temperature of the specific polyester according to this embodiment is preferably 35 ° C. or more and 80 ° C. or less, and preferably 40 ° C. or more from the viewpoint of toner fixing property, storage stability, and durability when used as a binder resin for the toner. 70 degrees C or less is more preferable.
The softening temperature and glass transition temperature can be easily adjusted by adjusting the raw material monomer composition, the polymerization initiator, the molecular weight, the catalyst amount, etc., or by selecting the reaction conditions.

*
The acid value of the specific polyester according to the exemplary embodiment is preferably 1 mgKOH / g or more and 50 mgKOH / g or less, and preferably 3 mgKOH / g or more and 30 mgKOH / g or less, from the viewpoint of toner chargeability when used as a toner binder resin. Is more preferable.
In addition, about the softening temperature of specific polyester, a glass transition temperature, and an acid value, it calculates | requires by the method described in the Example.

  The specific polyester according to this embodiment may be a modified polyester. Examples of the modified polyester include grafting and blocking with phenol, urethane, epoxy and the like by the methods described in JP-A-11-133668, JP-A-10-239903, JP-A-8-20636, and the like. Polyester.

The specific polyester according to this embodiment has a feature that it is difficult to contain water by containing a rosin skeleton having a bulky structure and a high hydrophobic property, and in addition to this, the resin itself is a crosslinked product. It is also excellent in strength.
For this reason, the specific polyester according to the present embodiment is a toner that has excellent chargeability when used as a binder resin for the toner and that can also prevent crushing due to stirring in the developing device. it can. From this point, it can be said that the specific polyester according to this embodiment is useful for toner.

<Toner>
The toner according to the exemplary embodiment contains the specific polyester according to the exemplary embodiment as a binder resin, and a colorant, a release agent, a charge control agent, an external additive, and the like as necessary. Other components may be included.
In addition to the specific polyester according to the exemplary embodiment, the toner according to the exemplary embodiment includes a known binder resin, for example, a vinyl-based resin such as a styrene-acrylic resin, in a range that does not impair the effect due to the specific polyester. Other resins such as resin, epoxy resin, polycarbonate, and polyurethane may be used in combination.
The content of the specific polyester according to the exemplary embodiment is preferably 70% by mass or more, more preferably 90% by mass or more, and still more preferably 100% by mass in the binder resin constituting the toner.

(Coloring agent)
The colorant used in this embodiment may be a dye or a pigment, but a pigment is desirable from the viewpoint of light resistance and water resistance.
Desirable colorants include carbon black, aniline black, aniline blue, calcoil blue, chrome yellow, ultramarine blue, dupont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, malachite green oxalate, lamp black, rose bengal, Quinacridone, benzicine yellow, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 57: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 185, C.I. I. Pigment red 238, C.I. I. Pigment yellow 12, C.I. I. Pigment yellow 17, C.I. I. Pigment yellow 180, C.I. I. Pigment yellow 97, C.I. I. Pigment yellow 74, C.I. I. Pigment blue 15: 1, C.I. I. A known pigment such as CI Pigment Blue 15: 3 may be used.

The content of the colorant in the toner according to the exemplary embodiment is desirably in the range of 1 part by mass to 30 parts by mass with respect to 100 parts by mass of the binder resin. It is also effective to use a surface-treated colorant or a pigment dispersant as necessary.
By selecting the type of colorant, yellow toner, magenta toner, cyan toner, black toner and the like can be obtained.

(Release agent)
Examples of the release agent used in the present embodiment include paraffin wax such as low molecular weight polypropylene and low molecular weight polyethylene; silicone resin; rosins; rice wax; carnauba wax; The melting temperature of these release agents is preferably 50 ° C. or higher and 100 ° C. or lower, and more preferably 60 ° C. or higher and 95 ° C. or lower. The content of the release agent in the toner is desirably 0.5% by mass or more and 15% by mass or less, and more desirably 1.0% by mass or more and 12% by mass or less. When the content of the release agent is 0.5% by mass or more, the occurrence of defective peeling is prevented particularly in oilless fixing. When the content of the release agent is 15% by mass or less, the fluidity of the toner is not deteriorated, and the image quality and the reliability of image formation are improved.

(Charge control agent)
As the charge control agent used in the present embodiment, a known one may be used, but an azo metal complex compound, a metal complex compound of salicylic acid, or a resin type charge control agent containing a polar group may be used. Good.

(External additive)
The toner according to the exemplary embodiment may contain an inorganic powder as an external additive for toner particles for the purpose of improving fluidity.
Suitable inorganic powders include, for example, silica powder, alumina, titanium oxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, silica sand, clay, mica, wollastonite, diatomaceous earth, Examples thereof include chromium oxide, cerium oxide, bengara, antimony trioxide, magnesium oxide, zirconium oxide, barium sulfate, barium carbonate, calcium carbonate, silicon carbide, and silicon nitride. Silica powder is particularly desirable. The proportion of the inorganic powder mixed with the toner is usually in the range of 0.01 to 5 parts by weight, preferably 0.01 to 2.0 parts by weight with respect to 100 parts by weight of the toner. Range. Moreover, you may use together well-known materials, such as a silica, titanium, a resin particle (resin particles, such as a polystyrene, PMMA, a melamine resin), and alumina, in this inorganic powder. Further, as a cleaning activator, a metal salt of a higher fatty acid typified by zinc stearate and particle powder of a fluorine-based high molecular weight substance may be added.

-Toner characteristics-
The toner shape factor SF1 according to the exemplary embodiment is desirably in the range of 110 to 150, and more desirably in the range of 120 to 140.

Here, the shape factor SF1 is obtained by the following equation (1).
SF1 = (ML ² / A) × (π / 4) × 100 (1)
In the above formula (1), ML represents the absolute maximum length of the toner, and A represents the projected area of the toner.

  SF1 is quantified mainly by analyzing a microscope image or a scanning electron microscope (SEM) image using an image analyzer, and is calculated as follows, for example. That is, an optical microscope image of particles scattered on the surface of the slide glass is taken into a Luzex image analyzer through a video camera, and the maximum length and projected area of 100 particles are obtained, calculated by the above equation (1), and the average value is calculated. It is obtained by seeking.

  The volume average particle diameter of the toner according to the exemplary embodiment is preferably in the range of 8 μm to 15 μm, more preferably in the range of 9 μm to 14 μm, and still more preferably in the range of 10 μm to 12 μm.

  The volume average particle size is measured using a Coulter Multisizer (manufactured by Coulter Inc.) with an aperture diameter of 50 μm. At this time, the measurement was performed after the toner was dispersed in an electrolyte aqueous solution (Isoton aqueous solution) and dispersed by ultrasonic waves for 30 seconds or more.

  The toner production method according to the exemplary embodiment is not particularly limited, and toner particles are produced by a known dry method such as a kneading and pulverizing method, a wet method such as an emulsion aggregation method or a suspension polymerization method, and the like. Thus, an external additive is externally added to the toner particles to obtain a toner.

The kneading and pulverizing method is a method for producing toner particles by kneading a kneaded product after kneading a toner forming material containing a binder resin to obtain a kneaded product.
More specifically, the kneading and pulverizing method is divided into a kneading step for kneading the toner forming material containing the binder resin and a pulverizing step for pulverizing the kneaded product. You may have other processes, such as a cooling process which cools the kneaded material formed by the kneading process as needed.
Each step will be described in detail.

-Kneading process-
In the kneading step, the toner forming material including the binder resin is kneaded.
In the kneading process, 0.5 to 5 parts by mass of an aqueous medium (for example, water such as distilled water or ion-exchanged water, alcohols, or the like) may be added to 100 parts by mass of the toner forming material. desirable.

  Examples of the kneader used in the kneading process include a single screw extruder, a twin screw extruder, and the like. Hereinafter, as an example of a kneading machine, a kneading machine having a feed screw part and two kneading parts will be described with reference to the drawings, but the invention is not limited thereto.

FIG. 1 is a diagram illustrating a screw state of an example of a screw extruder used in a kneading process in the toner manufacturing method according to the present embodiment.
The screw extruder 11 includes a barrel 12 having a screw (not shown), an inlet 14 for injecting a toner forming material as a raw material of the toner into the barrel 12, and an aqueous medium added to the toner forming material in the barrel 12. A liquid addition port 16 for discharging the toner, and a discharge port 18 for discharging the kneaded material formed by kneading the toner forming material in the barrel 12.

  The barrel 12 has a feed screw portion SA for transporting the toner forming material injected from the injection port 14 to the kneading portion NA in order from the side closer to the injection port 14, and the toner forming material is melt-kneaded by the first kneading process. A kneading part NA, a feed screw part SB for transporting the toner forming material melted and kneaded in the kneading part NA to the kneading part NB, and the toner forming material is melted and kneaded in a second kneading process. It is divided into a kneading part NB that forms the smelted product and a feed screw part SC that transports the formed kneaded product to the discharge port 18.

  The barrel 12 is provided with temperature control means (not shown) that is different for each block. That is, the temperature may be controlled at different temperatures from the block 12A to the block 12J. FIG. 1 shows a state in which the temperatures of the block 12A and the block 12B are controlled to t0 ° C., the temperatures of the blocks 12C to 12E are controlled to t1 ° C., and the temperatures of the blocks 12F to 12J are controlled to t2 ° C. Yes. Therefore, the toner forming material of the kneading part NA is heated to t1 ° C., and the toner forming material of the kneading part NB is heated to t2 ° C.

  When the toner forming material containing the binder resin is supplied from the injection port 14 to the barrel 12, the toner forming material is sent to the kneading portion NA by the feed screw portion SA. At this time, since the temperature of the block 12C is set to t1 ° C., the toner forming material is fed into the kneading portion NA in a state of being heated and changed into a molten state. Since the temperatures of the block 12D and the block 12E are also set to t1 ° C., the toner forming material is melted and kneaded at the temperature of t1 ° C. in the kneading portion NA. The binder resin is in a molten state at the kneading portion NA and is subjected to shearing by the screw.

Next, the toner forming material that has been kneaded in the kneading part NA is sent to the kneading part NB by the feed screw part SB.
Next, the aqueous medium is added to the toner forming material by injecting the aqueous medium into the barrel 12 from the liquid addition port 16 in the feed screw portion SB. Moreover, although the form which inject | pours an aqueous medium in the feed screw part SB is shown in FIG. 1, it is not restricted to this, An aqueous medium may be inject | poured in the kneading part NB, The feed screw part SB and the kneading part NB In both cases, an aqueous medium may be injected. That is, the position and the injection location for injecting the aqueous medium are selected as necessary.

As described above, when the aqueous medium is injected into the barrel 12 from the liquid addition port 16, the toner forming material and the aqueous medium in the barrel 12 are mixed, and the toner forming material is cooled by the latent heat of vaporization of the aqueous medium. The temperature of the toner forming material is maintained appropriately.
Finally, the kneaded material formed by being melted and kneaded by the kneading part NB is transported to the discharge port 18 by the feed screw part SC and discharged from the discharge port 18.
As described above, the kneading process using the screw extruder 11 shown in FIG. 1 is performed.

-Cooling process-
The cooling step is a step of cooling the kneaded product formed in the kneading step. In the cooling step, the cooling temperature is 40 ° C. at an average temperature decrease rate of 4 ° C./sec or more from the temperature of the kneaded product at the end of the kneading step. It is preferable to cool to below. Rapid cooling at the above average cooling rate is preferable because the dispersion state immediately after the kneading process is maintained. In addition, the said average temperature-fall rate means the average value of the speed | rate to temperature-fall from the temperature of the kneaded material at the time of the completion | finish of a kneading process (for example, when using the screw extruder 11 of FIG. 1 to 40 degreeC). .
Specific examples of the cooling method in the cooling step include a method using a rolling roll in which cold water or brine is circulated, a sandwiching cooling belt, and the like. When cooling is performed by the above method, the cooling rate is determined by the speed of the rolling roll, the flow rate of brine, the supply amount of the kneaded material, the slab thickness at the time of rolling the kneaded material, and the like. The slab thickness is preferably 1 to 3 mm.

-Crushing process-
The kneaded material cooled by the cooling process is pulverized by the pulverization process, and particles are formed. In the pulverization step, for example, a mechanical pulverizer or a jet pulverizer is used.

-Classification process-
The particles obtained by the pulverization step may be classified by a classification step in order to obtain toner particles having a volume average particle diameter in a target range, if necessary. In the classification process, conventionally used centrifugal classifiers, inertia classifiers, etc. are used, and fine powder (particles smaller than the target particle size) and coarse powder (target particle size). Larger particles) are removed.

-External addition process-
The obtained toner particles may be adhering to the inorganic powder represented by the specific silica, titania and aluminum oxide described above for the purpose of charge adjustment, fluidity provision, charge exchangeability and the like. These are performed by, for example, a V-type blender, a Henschel mixer, a Redige mixer, or the like, and are attached in stages.

-Sieving process-
You may provide a sieving process after the said external addition process as needed. Specific examples of the sieving method include a gyro shifter, a vibration sieving machine, and a wind sieving machine. By sieving, coarse particles of the external additive and the like are removed, and generation of streaks on the photosensitive member and scumming in the apparatus are suppressed.

As a method for producing the toner according to the present embodiment, the following emulsion aggregation method may be used.
As such an emulsion aggregation method, an emulsification step of emulsifying a raw material constituting the toner to form resin particles (emulsion particles), an aggregation step of forming an aggregate containing the resin particles, and a fusion step of fusing the aggregates You may have.
Specific steps are shown below.

-Emulsification process-
For example, the resin particle dispersion may be produced by applying a shearing force to a solution obtained by mixing an aqueous medium and a binder resin with a disperser. At that time, particles may be formed by heating to lower the viscosity of the resin component. A dispersant may be used for stabilizing the dispersed resin particles.
Furthermore, if the resin is oily and dissolves in a solvent having a relatively low solubility in water, the resin is dissolved in these solvents and dispersed in water together with a dispersant and a polymer electrolyte, and then heated or decompressed. By evaporating the solvent, a resin particle dispersion is produced.

Examples of the aqueous medium include water such as distilled water and ion-exchanged water; alcohols; and the like. Water is preferable.
Examples of the dispersant used in the emulsification step include water-soluble polymers such as polyvinyl alcohol, methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, sodium polyacrylate, and sodium polymethacrylate; sodium dodecylbenzenesulfonate, Anionic surfactants such as sodium octadecyl sulfate, sodium oleate, sodium laurate, potassium stearate, cationic surfactants such as laurylamine acetate, stearylamine acetate, lauryltrimethylammonium chloride, amphoteric such as lauryldimethylamine oxide Ionic surfactant, polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene Surfactants such as nonionic surfactants such as alkyl amines; and the like are; tricalcium phosphate, aluminum hydroxide, calcium sulfate, calcium carbonate, inorganic salts such as barium carbonate.

  Examples of the disperser used for preparing the emulsion include a homogenizer, a homomixer, a pressure kneader, an extruder, and a media disperser. As the size of the resin particles, the average particle diameter (volume average particle diameter) is preferably 1.0 μm or less, more preferably in the range of 60 nm to 300 nm, and further preferably in the range of 150 nm to 250 nm. . If it is less than 60 nm, the resin particles become stable particles in the dispersion, and thus aggregation of the resin particles may be difficult. On the other hand, if it exceeds 1.0 μm, the cohesiveness of the resin particles is improved and it becomes easy to prepare toner particles, but the particle size distribution of the toner may be widened.

  In preparing the release agent dispersion, the release agent is dispersed in water together with an ionic surfactant, a polymer electrolyte such as a polymer acid or a polymer base, and then heated to a temperature equal to or higher than the melting temperature of the release agent. Dispersion treatment is performed using a homogenizer or a pressure discharge type disperser to which a strong shearing force is applied while heating. Through the above treatment, a release agent dispersion is obtained. An inorganic compound such as polyaluminum chloride may be added to the dispersion during the dispersion treatment. Examples of desirable inorganic compounds include polyaluminum chloride, aluminum sulfate, highly basic polyaluminum chloride (BAC), polyaluminum hydroxide, and aluminum chloride. Among these, polyaluminum chloride and aluminum sulfate are desirable. The release agent dispersion is used in the emulsion aggregation method, but the release agent dispersion may also be used when the toner is produced by suspension polymerization.

By the dispersion treatment, a release agent dispersion liquid containing release agent particles having a volume average particle diameter of 1 μm or less is obtained. In addition, the more preferable volume average particle diameter of the release agent particles is 100 nm or more and 500 nm or less.
When the volume average particle diameter is less than 100 nm, the properties of the binder resin used are affected, but generally the release agent component is hardly taken into the toner. On the other hand, if it exceeds 500 nm, the dispersion state of the release agent in the toner may be insufficient.

  For the preparation of the colorant dispersion, a known dispersion method can be used. For example, a general dispersion means such as a rotary shear type homogenizer, a ball mill having a medium, a sand mill, a dyno mill, or an optimizer can be employed. Is not to be done. The colorant is dispersed in water together with a polymer electrolyte such as an ionic surfactant, a polymer acid, or a polymer base. The volume average particle diameter of the dispersed colorant particles may be 1 μm or less, but if it is in the range of 80 nm or more and 500 nm or less, the dispersion of the colorant in the toner is preferable without impairing the cohesiveness.

-Aggregation process-
In the agglomeration step, a resin particle dispersion, a colorant dispersion, a release agent dispersion, etc. are mixed to form a mixed liquid, which is heated to agglomerate at a temperature lower than the glass transition temperature of the resin particles to form aggregated particles. To do. Aggregated particles are often formed by making the pH of the mixed solution acidic under stirring. The pH is preferably in the range of 2 to 7, and in this case, it is also effective to use a flocculant.
In the aggregation step, the release agent dispersion may be added and mixed at once with various dispersions such as a resin particle dispersion, or may be added in multiple portions.

  As the aggregating agent, a surfactant having a polarity opposite to that of the surfactant used for the dispersant, an inorganic metal salt, and a divalent or higher-valent metal complex are preferably used. In particular, the use of a metal complex is particularly desirable because the amount of the surfactant used can be reduced and the charging characteristics are improved.

  As the inorganic metal salt, an aluminum salt and a polymer thereof are particularly suitable. In order to obtain a narrower particle size distribution, the valence of the inorganic metal salt is bivalent than monovalent, trivalent than bivalent, trivalent than trivalent, and tetravalent than trivalent. Inorganic metal salt polymers are more suitable.

  Alternatively, a toner having a structure in which the surface of the core aggregated particles is coated with a resin may be prepared by additionally adding a resin particle dispersion when the aggregated particles have reached a desired particle size (coating step). In this case, the release agent and the colorant are not easily exposed on the toner surface, which is desirable from the viewpoint of chargeability and developability. In the case of additional addition, a flocculant may be added or pH adjustment may be performed before additional addition.

-Fusion process-
In the fusing step, the agglomeration is stopped by raising the pH of the suspension of the agglomerated particles to a range of 3 to 9 under stirring conditions according to the agglomeration step, and at a temperature equal to or higher than the glass transition temperature of the resin. The aggregated particles are fused by heating. Moreover, when it coat | covers with resin, this resin is also united and a core aggregated particle is coat | covered. The heating time may be as long as fusion is performed, and may be performed for about 0.5 hours to 10 hours.

Cool after fusion to obtain fused particles. Further, in the cooling step, crystallization may be promoted by reducing the cooling rate in the vicinity of the glass transition temperature (range of glass transition temperature ± 10 ° C.) of the resin, so-called slow cooling.
The fused particles obtained by fusing are made into toner particles through a solid-liquid separation process such as filtration and, if necessary, a washing process and a drying process. When no external additive is added to the toner particles, the obtained toner particles may be used as the toner.

-External addition process-
The inorganic particles described above may be externally added to the obtained toner particles in the same manner as in the kneading and pulverization method. The external addition method of the inorganic powder is the same as in the kneading and pulverization method.

<Developer>
The developer according to this embodiment includes at least the toner according to this embodiment.
The toner according to this exemplary embodiment is used as it is as a one-component developer or as a two-component developer. When used as a two-component developer, it is used by mixing with a carrier.

  The carrier that can be used for the two-component developer is not particularly limited, and a known carrier may be used. Examples thereof include magnetic metals such as iron oxide, nickel and cobalt, magnetic oxides such as ferrite and magnetite, resin-coated carriers having a resin coating layer on the surface of the core material, and magnetic dispersion carriers. Further, a resin dispersion type carrier in which a conductive material or the like is dispersed in a matrix resin may be used.

  In the two-component developer, the mixing ratio (mass ratio) of the toner and the carrier is preferably in the range of toner: carrier = 1: 100 to 30: 100, and more preferably in the range of 3: 100 to 20: 100. .

<Image Forming Apparatus and Image Forming Method>
Next, an image forming apparatus according to this embodiment using the developer according to this embodiment will be described.
The image forming apparatus according to the present embodiment includes a latent image holding member, a charging unit that charges the surface of the latent image holding member, and an electrostatic latent image forming unit that forms an electrostatic latent image on the surface of the latent image holding member. The electrostatic latent image contains a developer according to the present embodiment, and developing means for developing the electrostatic latent image with the developer to form a toner image, and transfer for transferring the toner image to a recording medium And fixing means for fixing the toner image on the recording medium.
By the image forming apparatus according to the present embodiment, a charging step of charging the surface of the latent image holding member, an electrostatic latent image forming step of forming an electrostatic latent image on the surface of the latent image holding member, and the electrostatic latent image A book comprising: a developing step of developing with a developer according to the present embodiment to form a toner image; a transfer step of transferring the toner image to a recording medium; and a fixing step of fixing the toner image on the recording medium. The image forming method according to the embodiment is performed.

  In this image forming apparatus, for example, the part including the developing unit may have a cartridge structure (process cartridge) that can be attached to and detached from the main body of the image forming apparatus. The process cartridge includes a developing unit that stores the developer according to the present embodiment and develops the electrostatic latent image formed on the surface of the latent image holding body with the developer to form a toner image. A process cartridge according to this embodiment that is detachably attached to the apparatus is preferably used.

Hereinafter, an example of the image forming apparatus according to the present embodiment will be described, but the present embodiment is not limited to this. In addition, the main part shown to a figure is demonstrated and the description is abbreviate | omitted about others.
FIG. 2 is a schematic configuration diagram showing a four-tandem color image forming apparatus. The image forming apparatus shown in FIG. 2 is a first to first electrophotographic method that outputs yellow (Y), magenta (M), cyan (C), and black (K) images based on color-separated image data. Fourth image forming units 10Y, 10M, 10C, and 10K (image forming means) are provided. These image forming units (hereinafter sometimes simply referred to as “units”) 10Y, 10M, 10C, and 10K are arranged in parallel in the horizontal direction at a predetermined distance from each other. The units 10Y, 10M, 10C, and 10K may be process cartridges that can be attached to and detached from the image forming apparatus main body.

Above each unit 10Y, 10M, 10C, 10K in the figure, an intermediate transfer belt 20 as an intermediate transfer member is extended through each unit. The intermediate transfer belt 20 is wound around a drive roller 22 and a support roller 24 that are in contact with the inner surface of the intermediate transfer belt 20, and travels in a direction from the first unit 10Y to the fourth unit 10K. The support roller 24 is urged away from the drive roller 22 by a spring or the like (not shown), and a predetermined tension is applied to the intermediate transfer belt 20 wound around the support roller 24. An intermediate transfer member cleaning device 30 is provided on the side surface of the latent image holding member of the intermediate transfer belt 20 so as to face the drive roller 22.
Further, each of the developing devices (developing means) 4Y, 4M, 4C, and 4K of the units 10Y, 10M, 10C, and 10K includes yellow, magenta, cyan, and black contained in the toner cartridges 8Y, 8M, 8C, and 8K. The four color toners can be supplied.

  Since the first to fourth units 10Y, 10M, 10C, and 10K described above have the same configuration, here, the first unit that forms a yellow image disposed on the upstream side in the intermediate transfer belt traveling direction. 10Y will be described as a representative. It should be noted that the second to fourth units are denoted by adding reference numerals with magenta (M), cyan (C), and black (K) instead of yellow (Y) to the same parts as the first unit 10Y. Description of 10M, 10C, 10K is omitted.

The first unit 10Y has a photoreceptor 1Y that functions as a latent image holding member. Around the photoreceptor 1Y, an electrostatic latent image is obtained by exposing the surface of the photoreceptor 1Y to a predetermined potential with a charging roller 2Y, and exposing the charged surface with a laser beam 3Y based on the color-separated image signal. An exposure device 3 for forming the electrostatic latent image, a developing device (developing means) 4Y for supplying the charged toner to the electrostatic latent image to develop the electrostatic latent image, and a primary transfer for transferring the developed toner image onto the intermediate transfer belt 20 A roller (primary transfer unit) 5Y and a photoconductor cleaning device (cleaning unit) 6Y for removing toner remaining on the surface of the photoconductor 1Y after the primary transfer are sequentially arranged.
The primary transfer roller 5Y is disposed inside the intermediate transfer belt 20 and is provided at a position facing the photoreceptor 1Y. Further, a bias power source (not shown) for applying a primary transfer bias is connected to each of the primary transfer rollers 5Y, 5M, 5C, and 5K. Each bias power source varies the transfer bias applied to each primary transfer roller under the control of a control unit (not shown).

Hereinafter, an operation of forming a yellow image in the first unit 10Y will be described. First, prior to the operation, the surface of the photoreceptor 1Y is charged to a potential of about −600V to −800V by the charging roller 2Y.
The photoreceptor 1Y is formed by laminating a photosensitive layer on a conductive substrate (volume resistivity at 20 ° C .: 1 × 10 ⁻⁶ Ωcm or less). This photosensitive layer usually has a high resistance (a resistance equivalent to that of a general resin), but has a property that the specific resistance of the portion irradiated with the laser beam changes when irradiated with the laser beam 3Y. Therefore, a laser beam 3Y is output to the surface of the charged photoreceptor 1Y via the exposure device 3 in accordance with yellow image data sent from a control unit (not shown). The laser beam 3Y is applied to the photosensitive layer on the surface of the photoreceptor 1Y, whereby an electrostatic latent image of a yellow print pattern is formed on the surface of the photoreceptor 1Y.

The electrostatic latent image is an image formed on the surface of the photoreceptor 1Y by charging. The specific resistance of the irradiated portion of the photosensitive layer is lowered by the laser beam 3Y, and the charged charge on the surface of the photoreceptor 1Y flows. On the other hand, this is a so-called negative latent image formed by the charge remaining in the portion not irradiated with the laser beam 3Y.
The electrostatic latent image formed on the photoreceptor 1Y in this way is rotated to a predetermined development position as the photoreceptor 1Y travels. Then, at this development position, the electrostatic latent image on the photoreceptor 1Y is converted into a visible image (developed image) by the developing device 4Y.

  The yellow developer stored in the developing device 4Y is triboelectrically charged by being stirred inside the developing device 4Y, and has the same polarity (negative polarity) as the charged electric charge on the photoreceptor 1Y. Is held on a developer roll (developer holder). As the surface of the photoreceptor 1Y passes through the developing device 4Y, the yellow toner is electrostatically attached to the latent image portion on the surface of the photoreceptor 1Y, and the latent image is developed with the yellow toner. . The photoreceptor 1Y on which the yellow toner image is formed continues to run at a predetermined speed, and the toner image developed on the photoreceptor 1Y is conveyed to a predetermined primary transfer position.

When the yellow toner image on the photoreceptor 1Y is conveyed to the primary transfer position, a predetermined primary transfer bias is applied to the primary transfer roller 5Y, and electrostatic force directed from the photoreceptor 1Y to the primary transfer roller 5Y. Acts on the toner image, and the toner image on the photoreceptor 1 </ b> Y is transferred onto the intermediate transfer belt 20. The transfer bias applied at this time has a polarity (+) opposite to the polarity (−) of the toner. For example, in the first unit 10Y, it is controlled to about +10 μA by a control unit (not shown).
On the other hand, the toner remaining on the photoreceptor 1Y is removed and collected by the cleaning device 6Y.

Further, the primary transfer bias applied to the primary transfer rollers 5M, 5C, and 5K after the second unit 10M is also controlled according to the first unit.
Thus, the intermediate transfer belt 20 to which the yellow toner image is transferred by the first unit 10Y is sequentially conveyed through the second to fourth units 10M, 10C, and 10K, and the toner images of the respective colors are superimposed to form a superimposed toner image. It is formed.

  The intermediate transfer belt 20 on which the four color toner images are superimposed through the first to fourth units is disposed on the image transfer surface side of the intermediate transfer belt 20, the support roller 24 in contact with the inner surface of the intermediate transfer belt 20, and the intermediate transfer belt 20. The secondary transfer roller (secondary transfer means) 26 is connected to a secondary transfer portion. On the other hand, a recording sheet (recording medium) P is fed at a predetermined timing to a gap where the secondary transfer roller 26 and the intermediate transfer belt 20 are pressed against each other via a supply mechanism, and a predetermined secondary transfer is performed. A bias is applied to the support roller 24. The transfer bias applied at this time has the same polarity (−) as the polarity (−) of the toner, and an electrostatic force from the intermediate transfer belt 20 toward the recording paper P is applied to the superimposed toner image, and the intermediate transfer belt. The superimposed toner image 20 is transferred onto the recording paper P. The secondary transfer bias at this time is determined according to the resistance detected by a resistance detection means (not shown) for detecting the resistance of the secondary transfer portion, and is voltage-controlled.

Thereafter, the recording paper P is sent to a fixing device (fixing means) 28, where the superimposed toner image is heated, and the color-superposed toner image is melted and fixed on the recording paper P. The recording paper P on which the fixing of the color image has been completed is conveyed by a conveyance roll (discharge roll) 32 toward the discharge unit, and a series of color image forming operations is completed.
The image forming apparatus exemplified above is configured to transfer the superimposed toner image onto the recording paper P via the intermediate transfer belt 20, but is not limited to this configuration, and is not limited to this configuration. A structure in which an image is transferred to a recording sheet may be used.

<Process cartridge, toner cartridge>
FIG. 3 is a schematic configuration diagram illustrating a preferred example of a process cartridge that stores the developer according to the present embodiment. The process cartridge 200 includes, together with the photoconductor 107, a charging device 108, a developing device 111, a photoconductor cleaning device (cleaning means) 113, an opening 118 for exposure, and an opening 117 for static elimination exposure. Are combined and integrated with each other.
The process cartridge 200 is detachable from an image forming apparatus main body including a transfer device 112, a fixing device 115, and other components not shown. It constitutes. Reference numeral 300 denotes a recording sheet.

  The process cartridge 200 shown in FIG. 3 includes a photoconductor 107, a charging device 108, a developing device 111, a photoconductor cleaning device 113, an opening 118 for exposure, and an opening 117 for static elimination exposure. These devices may be selectively combined. In the process cartridge according to the present embodiment, in addition to the developing device 111, the photoconductor 107, the charging device 108, the photoconductor cleaning device (cleaning means) 113, the opening 118 for exposure, and the charge removal exposure. You may provide at least 1 sort (s) selected from the group comprised from the opening part 117. FIG.

Next, the toner cartridge will be described.
The toner cartridge is detachably attached to the image forming apparatus, and at least in the toner cartridge that stores toner to be supplied to the developing means provided in the image forming apparatus, the toner is in the above-described embodiment. Such toner is used. The toner cartridge only needs to contain at least toner, and may contain developer, for example, depending on the mechanism of the image forming apparatus.

  2 is an image forming apparatus having a configuration in which the toner cartridges 8Y, 8M, 8C, and 8K can be attached and detached, and the developing devices 4Y, 4M, 4C, and 4K are respectively the developing devices ( Are connected to a toner cartridge corresponding to (color) by a developer supply pipe (not shown). Further, when the amount of developer stored in the toner cartridge is reduced, the toner cartridge can be replaced.

  Hereinafter, although an example is given and this embodiment is explained concretely, this embodiment is not limited only to an example shown below. In the examples, “parts” and “%” mean “parts by mass” and “% by mass” unless otherwise specified.

[Measurement methods for various physical properties]
<Measurement of weight average molecular weight Mw and number average molecular weight Mn>
Two “HLC-8120GPC, SC-8020 (6.0 mm ID × 15 cm) manufactured by Tosoh Corporation” were used, and THF (tetrahydrofuran) was used as an eluent. As experimental conditions, the experiment was conducted using a sample concentration of 0.5%, a flow rate of 0.6 ml / min, a sample injection amount of 10 μl, a measurement temperature of 40 ° C., and an RI detector. The calibration curve is “Polystyrene standard sample TSK standard” manufactured by Tosoh Corporation: “A-500”, “F-1”, “F-10”, “F-80”, “F-380”, “A” -2500 "," F-4 "," F-40 "," F-128 ", and" F-700 ".

-Synthesis of specific rosin diol (1)-
Bisphenol A diglycidyl ether (trade name jER828, manufactured by Mitsubishi Chemical Co., Ltd.) 113 parts by mass as a bifunctional epoxy compound, and gum rosin 200 masses subjected to purification treatment by distillation (distillation conditions: 6.6 kPa, 220 ° C.) as a rosin component And 0.4 parts by mass of tetraethylammonium bromide (Tokyo Chemical Industry Co., Ltd.) as a reaction catalyst were charged into a stainless steel reaction vessel equipped with a stirrer, heating device, cooling tube and thermometer, and the temperature was raised to 130 ° C. The ring-opening reaction between the acid group of rosin and the epoxy group of the epoxy compound was continued for 4 hours at the same temperature, and the reaction was stopped when the acid value reached 0.5 mgKOH / g. The specific rosin diol (1) mentioned as a compound was obtained.

-Synthesis of specific rosin diol (2)-
Instead of 113 parts by mass of bisphenol A diglycidyl ether (trade name jER828, manufactured by Mitsubishi Chemical Corp.) as a bifunctional epoxy compound, 113 parts by mass of bisphenol F diglycidyl ether (trade name jER806, manufactured by Mitsubishi Chemical Corp.) The specific rosin diol (2) was synthesized by the same method as the synthesis of the specific rosin diol (1) except that it was used.

-Synthesis of polyester resin (1)-
313 parts by mass of specific rosin diol (1) as an alcohol component, 115 parts by mass of bisphenol A propylene oxide, 87 parts by mass of terephthalic acid (manufactured by Wako Pure Chemical Industries, Ltd.), 30 parts by mass of dodecenyl succinic acid, and glycerol as a crosslinking agent 0.6 parts by mass (manufactured by Wako Pure Chemical Industries), and tetra-n-butyl titanate (manufactured by Tokyo Chemical Industry Co., Ltd.) as a reaction catalyst 1.1 parts by mass of a stirrer, heating device, thermometer, fractionator, A polyester resin (1) was synthesized by charging into a stainless steel reaction vessel equipped with a nitrogen gas introduction tube and subjecting it to a polycondensation reaction at 230 ° C. for 8 hours with stirring in a nitrogen atmosphere to confirm that the target molecular weight had been reached. . 2 g of the synthesized specific polyester resin 1 was taken and hydrolyzed by heating at 150 ° C. for 3 hours in 10 ml of heavy dimethyl sulfoxide and 2 ml of a heavy methanol solution of sodium hydroxide (7N). Thereafter, heavy water was added, 1H-NMR measurement was performed, and it was confirmed that the resin was composed of the specific rosin diol (1) and terephthalic acid according to the charged values.

-Synthesis of polyester resins (2)-(11)-
According to Table 1 and Table 2, the synthesis | combination of polyester resin (2)-(11) is carried out by the method similar to the synthesis | combination of polyester resin (1) except having changed the kind and addition amount of an acid component, an alcohol component, and a crosslinking agent. went.

[Example 1]
-Production of toner particles 1-
The following mixture was kneaded with an extruder and pulverized with a surface pulverizer. Thereafter, the process of classifying fine particles and coarse particles with a wind classifier (turbo classifier (TC-15N), manufactured by Nisshin Engineering Co., Ltd.) and obtaining intermediate size particles is repeated three times, and the volume average particle diameter = 8 μm of magenta toner particles 1 were obtained.

(Mixture composition)
・ Polyester resin (1) 100 parts ・ Magenta pigment (CI Pigment Red 57) 3 parts

-Manufacture of toner 1 (addition of external additives)-
Hydrophobic titania 0.8% treated with decylsilane with an average particle size of 15 nm, hydrophobic silica with a mean particle size of 30 nm (NY50, manufactured by Nippon Aerosil Co., Ltd.) 1.1%, and hydrophobic with an average particle size of 100 nm with respect to toner particles 1 After blending for 10 minutes at a peripheral speed of 32 m / s using a Henschel mixer so that the active silica (X24, manufactured by Shin-Etsu Chemical Co., Ltd.) is 1.0%, coarse particles are removed using a sieve of 45 μm mesh, Toner 1 was obtained.

-Production of carrier-
Ferrite (trade name EFC-35B, manufactured by Powdertech, weight average particle size: 35 μm): 100 parts Toluene: 13.5 parts Methyl methacrylate / perfluorooctyl methacrylate copolymer (polymerization ratio 90:10, Weight average molecular weight 49,000): 2.3 parts, carbon black (trade name: VXC72, manufactured by Cabot Corporation): 0.3 part, Eposter S (melamine resin particles, manufactured by Nippon Shokubai Co., Ltd.): 0.3 part Ferrite The above components except for the above were dispersed in a sand mill for 1 hour to prepare a resin coating layer forming solution. Next, this resin coating layer forming solution and ferrite were put in a vacuum degassing kneader and stirred for 20 minutes while reducing the pressure at a temperature of 60 ° C. to form a resin coating layer on the ferrite to obtain a carrier. The volume resistance value of the obtained carrier was 2 × 10 ¹¹ Ωcm.

-Production of Developer 1-
100 parts of the carrier obtained as described above was added to 1: 7 parts of the external toner, and mixed for 5 minutes by a ball mill to obtain a color developer.

[Evaluation]
<Image evaluation>
The obtained developer was housed in a Docu Center Color 500CP remodeling machine manufactured by Fuji Xerox Co., Ltd., and image formation was performed by such an apparatus. The image quality (melting unevenness) of the initial image and the image quality (melting unevenness) of the 50,000th image obtained were observed with a magnifying glass, and the white background of the printed material obtained for the 50,000th image. (Non-image part) Dirt was evaluated by reading the value of X-lite.
The evaluation criteria for image quality evaluation and background contamination are as follows.
-Evaluation criteria-
・ ○: No problem in the image quality of the initial and 50,000th image, dirt X-lite of the non-image portion is 1.2 or less ・ △ :: The image quality of the initial and 50,000th image is no problem, Some stains (X-lite is more than 1.2 and less than 1.5) are observed in the non-image area, but there is no practical problem. ×: Image quality of the initial and 50,000th images is deficient , Large dirt (X-lite is 1.5 or more) is observed in the non-image area, which is not practically usable.

<Empty evaluation>
The obtained developer was accommodated in a toner cartridge attached to and detached from a Docu Center Color 500CP modified machine manufactured by Fuji Xerox Co., Ltd., and stirred for about 10 minutes. The developer was taken out before and after stirring, and then the toner and the carrier were separated using a jet sieve, and the particle size of the toner was measured.
The evaluation criteria for idle rotation are as follows.
-Evaluation criteria-
・ ○: Particle size variation is 10% or less ・ △: Particle size variation is more than 10% and less than 20%, no practical problem ・ ×: Particle size variation is 20% or more, actual use is impossible

[Examples 2 to 10, Comparative Example 1]
According to Table 3, toner particles 2 to 11, toner 2 to 11, and developers 2 to 11 were obtained in the same manner as in Example 1 except that the polyester resin type was changed.
Next, evaluation was performed in the same manner as in Example 1. The evaluation results are also shown in Table 3 below.

  From the above results, it can be seen that in this example, better results were obtained for both the idle evaluation and the image evaluation than in the comparative example.

1Y, 1M, 1C, 1K, photoconductor (image carrier)
2Y, 2M, 2C, 2K, charging roller 3Y, 3M, 3C, 3K laser beam 3 exposure device 4Y, 4M, 4C, 4K, developing device (developing means)
5Y, 5M, 5C, 5K Primary transfer rollers 6Y, 6M, 6C, 6K, 113 Photoconductor cleaning device (cleaning means)
8Y, 8M, 8C, 8K Toner cartridges 10Y, 10M, 10C, 10K Unit 20 Intermediate transfer belt 22 Drive roller 24 Support roller 26 Secondary transfer roller (transfer means)
28 Fixing device (fixing means)
30 Intermediate transfer member cleaning device 32 Transport roll (discharge roll)
107 photoconductor (image carrier)
108 Charging device (charging means)
111 Developing device (developing means)
112 Transfer device (transfer means)
113 Photoconductor cleaning device (cleaning means)
115 Fixing device (fixing means)
116 Mounting rail 117 Opening 118 for static elimination exposure Opening 200 for exposure Process cartridge,
P, 300 recording paper (recording medium)

Claims (8)

  A polyester resin for toner which is a cross-linked product of a polycondensate of a dialcohol containing a dicarboxylic acid and a rosin skeleton and a compound containing a trifunctional or higher functional crosslinkable group.   The polyester resin for toner according to claim 1, wherein the compound containing a trifunctional or higher functional crosslinkable group is a polyvalent carboxylic acid or a polyhydric alcohol.   The polyester resin for toner according to claim 1 or 2, wherein a molecular weight distribution (Mw / Mn) obtained from the weight average molecular weight Mw and the number average molecular weight Mn is 10.0 or more and 15.0 or less.   A toner comprising the polyester resin for toner according to any one of claims 1 to 3.   A developer comprising the toner according to claim 4. Storing the toner according to claim 4;
A toner cartridge to be attached to and detached from the image forming apparatus. A developer that stores the developer according to claim 5 and that develops an electrostatic latent image formed on the surface of the latent image holding member with the developer to form a toner image,
A process cartridge attached to and detached from the image forming apparatus. A latent image carrier,
Charging means for charging the surface of the latent image carrier;
An electrostatic latent image forming means for forming an electrostatic latent image on the surface of the latent image holding member;
Development means for containing the developer according to claim 5 and developing the electrostatic latent image with the developer to form a toner image;
Transfer means for transferring the toner image to a recording medium;
Fixing means for fixing the toner image on the recording medium;
An image forming apparatus comprising: