JP2017142431A - Method for manufacturing electrophotographic toner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing an electrophotographic toner that, when a polylactic acid is introduced therein, is excellent in fogging suppression property in a high-temperature and high-humidity environment, and has satisfactory low-temperature fixability and durability.SOLUTION: There is provided a method for manufacturing an electrophotographic toner including the following step 1 to step 4. Step 1: fusing and kneading an amorphous composite resin L1 including a polyester resin segment and a styrene resin segment, and having a hydroxyl value of 10 mgKOH/g or more and 80 mgKOH/g or less and a softening point of 80°C or more and 120°C or less, and a crystalline polylactic acid, at 140°C or more and 230°C or less. Step 2: mixing the fused and kneaded material obtained in step 1, an amorphous resin H having a softening point of 122°C or more and 150°C or less, an amorphous composite resin L2 including a polyester resin segment and a styrene resin segment and having a softening point of 80°C or more and 120°C or less, a colorant, and a mold release agent. Step 3: fusing and kneading a mixture obtained in step 2. Step 4: pulverizing and classifying the fused and kneaded material obtained in step 3.SELECTED DRAWING: None

Description

  The present invention relates to a method for producing an electrophotographic toner.

  In recent years, with the promotion of miniaturization, high speed, and high image quality of electrophotographic apparatuses, and from the viewpoint of high reliability that does not impair the toner performance even in various environments, the toner used for electrophotographic printing is There is a strong demand for improved low-temperature fixability and durability.

On the other hand, the use of polylactic acid, which is a plant-derived raw material, is being studied for the purpose of reducing environmental burdens in toners that are electrophotographic developers.
In Patent Document 1, as a method for producing an electrostatic charge image developing toner excellent in durability, heat-resistant storage stability and high temperature offset resistance, production of an electrostatic charge image developing toner containing at least amorphous polyester and crystalline polylactic acid. A method in which amorphous polyester and crystalline polylactic acid are mixed at 140 to 250 ° C., step 2 in which the mixture obtained in step 1 is melt-kneaded, and the melt-kneaded product obtained in step 2 A method for producing a toner for developing an electrostatic charge image, which includes a step 3 of pulverizing and classifying, is described.

JP 2014-112207 A

However, polylactic acid does not always have satisfactory toner chargeability. In particular, in a high temperature and high humidity environment, problems such as fogging due to poor chargeability are likely to occur. In a high temperature and high humidity environment, the electrostatic adhesion force of the toner to the developing roller is weakened, and the toner carried on the surface of the developing roller adheres to the part that should be originally white on the carrier, and the printed image The toner is transferred to the white background.
Therefore, the present invention provides a method for producing an electrophotographic toner that has excellent anti-fogging properties in a high temperature and high humidity environment and has good low temperature fixability and durability when polylactic acid is introduced into the toner. To do.

That is, the present invention relates to a method for producing an electrophotographic toner including the following steps 1 to 4.
Step 1: Amorphous composite resin L1 having a polyester resin segment and a styrene resin segment, having a hydroxyl value of 10 mgKOH / g to 80 mgKOH / g and a softening point of 80 ° C to 120 ° C, and crystalline polylactic acid And melt kneading at 140 ° C. to 230 ° C. Step 2: The melt-kneaded product obtained in Step 1, amorphous resin H having a softening point of 122 ° C. to 150 ° C., and a polyester resin segment A step of mixing an amorphous composite resin L2 having a styrene-based resin segment and a softening point of 80 ° C. or higher and 120 ° C. or lower, a colorant, and a release agent Step 3: Mixing the mixture obtained in Step 2 Step of melt-kneading Step 4: Step of pulverizing and classifying the melt-kneaded product obtained in Step 3 The present invention also relates to an electrophotographic toner obtained in the step including Steps 1 to 4 above.

  According to the present invention, when polylactic acid is introduced into a toner, there is provided a method for producing an electrophotographic toner that is excellent in fog suppression under a high temperature and high humidity environment, and has good low temperature fixability and durability. can do.

The method for producing an electrophotographic toner of the present invention includes the following steps 1 to 4.
Step 1: Amorphous composite resin L1 having a polyester resin segment and a styrene resin segment, having a hydroxyl value of 10 mgKOH / g to 80 mgKOH / g and a softening point of 80 ° C to 120 ° C, and crystalline polylactic acid And melt kneading at 140 ° C. to 230 ° C. Step 2: The melt-kneaded product obtained in Step 1, amorphous resin H having a softening point of 122 ° C. to 150 ° C., and a polyester resin segment A step of mixing an amorphous composite resin L2 having a styrene-based resin segment and a softening point of 80 ° C. or higher and 120 ° C. or lower, a colorant, and a release agent Step 3: Mixing the mixture obtained in Step 2 Step of melt-kneading Step 4: Step of pulverizing and classifying the melt-kneaded product obtained in Step 3 According to the present invention, when polylactic acid is introduced into a toner, fog suppression in a high-temperature, high-humidity environment is performed. Excellent low temperature fixability and durability A preferred method for producing an electrophotographic toner can be provided.

The reason why the present invention has such an effect is not clear, but is considered as follows. Since crystalline polylactic acid is composed of aliphatic monomers, it does not have an aromatic ring in the molecular structure. Therefore, when crystalline polylactic acid is used for the electrophotographic toner, the aromatic ring concentration in the toner tends to be low. Therefore, by introducing an amorphous composite resin having a polyester-based resin segment and a styrene-based resin segment, the aromatic ring concentration in the electrophotographic toner is increased, the chargeability is improved, and the effect of suppressing fogging is achieved. It is thought that it was obtained.
In addition, in Step 1, by using a composite resin having a polyester resin segment having a predetermined hydroxyl value and a styrene resin segment, the composite resin and polylactic acid undergo an ester exchange reaction, and the composite of these resins It is considered that the compatibility with other binder resins is increased, and both the low-temperature fixability and durability are improved.

In the present invention, the meaning of each term is as follows.
`` Binder resin '' is a general term for amorphous composite resin L1, crystalline polylactic acid, and their reaction products, amorphous resin H, and amorphous composite resin L2. “To resin” means a numerical value relative to the total amount of the aforementioned resin.
With respect to binder resins other than crystalline polylactic acid, “crystalline” means the ratio of the softening point (° C.) to the maximum peak temperature (° C.) of the endotherm measured by a differential scanning calorimeter (DSC), that is, [(softening point) / It means that the value of the crystallinity index defined by (maximum endothermic peak temperature) is 0.6 or more, preferably 0.8 or more, and less than 1.4, preferably 1.2 or less.
With respect to binder resins other than crystalline polylactic acid, “amorphous” means that the value of the crystallinity index is 1.4 or more or less than 0.6. The maximum peak temperature of endotherm refers to the temperature of the peak on the highest temperature side among the endothermic peaks observed under the conditions of the measurement methods described in the examples. If the maximum peak temperature is within 20 ° C. from the softening point, the melting point of the crystalline resin is taken, and the peak exceeding 20 ° C. from the softening point is taken as the peak due to the glass transition of the amorphous resin.

With respect to polylactic acid, “crystalline” means that the crystallinity is 20% or more.
In addition, the said crystallinity degree can be calculated | required by the method as described in an Example.
Hereinafter, “electrophotographic toner” is also simply referred to as “toner”.

[Step 1]
In step 1, an amorphous composite resin L1 having a polyester resin segment and a styrene resin segment, having a hydroxyl value of 10 mgKOH / g to 80 mgKOH / g and a softening point of 80 ° C to 120 ° C, Lactic acid is melt kneaded at 140 ° C. or higher and 230 ° C. or lower.

<Amorphous composite resin L1>
The amorphous composite resin L1 has a polyester resin segment and a styrene resin segment from the viewpoint of obtaining a toner excellent in fog suppression, low temperature fixability, and durability under a high temperature and high humidity environment.
Amorphous composite resin L1 forms a complex with crystalline polylactic acid, and has a hydroxyl value from the viewpoint of obtaining a toner excellent in fog suppression, low-temperature fixability, and durability in a high temperature and high humidity environment. It is 10 mgKOH / g or more and 80 mgKOH / g or less, preferably 15 mgKOH / g or more, more preferably 20 mgKOH / g or more, further preferably 25 mgKOH / g or more, further preferably 30 mgKOH / g or more. The hydroxyl value is preferably 70 mgKOH / g or less, more preferably 60 mgKOH / g or less, and still more preferably 50 mgKOH / g or less.

From the viewpoint of obtaining a toner having excellent low-temperature fixability and durability, the amorphous composite resin L1 has a softening point of 80 ° C or higher and 120 ° C or lower, preferably 90 ° C or higher, more preferably 95 ° C or higher, Preferably it is 100 degreeC or more, More preferably, it is 105 degreeC or more, Preferably it is 115 degreeC or less, More preferably, it is 113 degreeC or less, More preferably, it is 110 degreeC or less.
In the present invention, the softening point is measured by the method described in the examples.

[Polyester resin segment]
In the amorphous composite resin L1, the polyester resin segment is made of a polyester resin obtained by polycondensation of an alcohol component and a carboxylic acid component.

(Alcohol component)
The alcohol component may be an aromatic polyol compound or an aliphatic polyol compound.
The aromatic polyol compound is preferably an aromatic diol, more preferably an alkylene oxide adduct of bisphenol A, and more preferably a formula (I): from the viewpoints of low-temperature fixability and durability.

[Wherein, RO and OR are oxyalkylene groups, R is at least one selected from an ethylene group and a propylene group, and x and y represent the average number of moles of alkylene oxide added, each being a positive number. The value of the sum of x and y is 1 or more, preferably 1.5 or more, and 16 or less, preferably 8 or less, more preferably 4 or less. An alkylene oxide adduct of bisphenol A represented by the formula:

Examples of the alkylene oxide adduct of bisphenol A represented by the formula (I) include 2,2-bis (4-hydroxyphenyl) propane propylene oxide adduct, 2,2-bis (4-hydroxyphenyl) propane ethylene. And oxide adducts. These can be used alone or in combination of two or more.
Among these, a combination of a propylene oxide adduct of 2,2-bis (4-hydroxyphenyl) propane and an ethylene oxide adduct of 2,2-bis (4-hydroxyphenyl) propane is preferable.

  Molar ratio of 2,2-bis (4-hydroxyphenyl) propane propylene oxide adduct to 2,2-bis (4-hydroxyphenyl) propane ethylene oxide adduct [2,2-bis (4-hydroxyphenyl) Propylene oxide adduct of propane / ethylene oxide adduct of 2,2-bis (4-hydroxyphenyl) propane] is preferably 40/60 or more, more preferably 50/50 or more, and further preferably 60/40 or more. And preferably 90/10 or less, more preferably 80/20 or less, and still more preferably 75/25 or less.

  The content of the alkylene oxide adduct of bisphenol A is preferably 70 mol% or more, more preferably 90 mol% or more, still more preferably 95 mol% or more, still more preferably 100 mol% in the alcohol component.

Examples of the aliphatic polyol compound include aliphatic diols having 2 to 20 carbon atoms, and trihydric or higher aliphatic alcohols such as glycerin. Among these, the above aliphatic diols are preferable.
Aliphatic diols include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,4-butenediol 1,3-butanediol, neopentyl glycol, 1,10-decanediol, 1,12-dodecanediol and the like. These can be used alone or in combination of two or more.

  The content of the aliphatic polyol compound in the alcohol component is preferably 50 mol% or less, more preferably 30 mol% or less, still more preferably 15 mol% or less, and 0 mol% or more.

(Carboxylic acid component)
The carboxylic acid component is preferably an aromatic dicarboxylic acid compound from the viewpoint of durability, and an aliphatic dicarboxylic acid compound is preferable from the viewpoint of low-temperature fixability.

  Examples of the aromatic dicarboxylic acid compound include phthalic acid, isophthalic acid, terephthalic acid; anhydrides of these acids or alkyl (C1-3) esters of these acids. These can be used alone or in combination of two or more. In these, a terephthalic acid or isophthalic acid is more preferable, and a terephthalic acid is still more preferable.

  The content of the aromatic dicarboxylic acid compound is preferably 10 mol% or more, more preferably 30 mol% or more, still more preferably 50 mol% or more, and 100 mol% or less in the carboxylic acid component.

  Examples of the aliphatic dicarboxylic acid compound include alkyls having 1 to 20 carbon atoms such as oxalic acid, malonic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, succinic acid, adipic acid, dodecenyl succinic acid, octyl succinic acid, etc. And aliphatic dicarboxylic acids such as succinic acid substituted with a group or an alkenyl group having 2 to 20 carbon atoms; anhydrides of these acids or alkyl (C1 to C3) esters of these acids. These can be used alone or in combination of two or more.

  The content of the aliphatic dicarboxylic acid compound in the carboxylic acid component is preferably 50 mol% or less, more preferably 30 mol% or less, still more preferably 20 mol% or less, and preferably 0 mol% or more. .

  Further, from the viewpoint of productivity, the carboxylic acid component preferably contains a trivalent or higher carboxylic acid compound, and more preferably contains a trivalent carboxylic acid compound.

  Examples of trivalent or higher carboxylic acid compounds include 1,2,4-benzenetricarboxylic acid (trimellitic acid), 2,5,7-naphthalenetricarboxylic acid, pyromellitic acid or acid anhydrides thereof, alkyl (carbon number: 1 -3) Esters, and the like. Among these, trimellitic acid and its anhydride (hereinafter, trimellitic acid and its anhydride are collectively referred to simply as “trimellitic acid and the like”) are preferable.

  The content of the trivalent or higher carboxylic acid compound, preferably the content of trimellitic acid, etc. is preferably 1 mol% or more, more preferably 3 mol% or more, and even more preferably 10 mol% or more in the carboxylic acid component. From the viewpoint of low-temperature fixability, it is preferably 50 mol% or less, more preferably 40 mol% or less, still more preferably 20 mol% or less, still more preferably 15 mol% or less.

  In addition, a monovalent alcohol may be appropriately contained in the alcohol component, and a monovalent carboxylic acid may be appropriately contained in the carboxylic acid component from the viewpoint of molecular weight adjustment.

  The equivalent ratio of the carboxylic acid component and the alcohol component (COOH group / OH group) is preferably 0.7 or more, more preferably 0.8 or more, and preferably 1.3 or less, more preferably from the viewpoint of adjusting the terminal group. 1.2 or less.

  The polycondensation of the alcohol component and the carboxylic acid component should be performed, for example, in an inert gas atmosphere at a temperature of about 180 ° C. to 250 ° C. in the presence of an esterification catalyst, a polymerization inhibitor, etc. Can do. Examples of the esterification catalyst include tin compounds such as dibutyltin oxide and tin (II) 2-ethylhexanoate, and titanium compounds such as titanium diisopropylate bistriethanolamate. Examples of the esterification cocatalyst that can be used together with the esterification catalyst include gallic acid and the like. The amount of esterification catalyst used is preferably 0.01 parts by mass or more, more preferably 0.1 parts by mass or more, and preferably 1 part by mass or less, more preferably 100 parts by mass of the total amount of alcohol component and carboxylic acid component. Preferably it is 0.6 mass part or less. The amount of esterification promoter used is preferably 0.001 parts by mass or more, more preferably 0.01 parts by mass or more, and preferably 0.5 parts by mass or less, with respect to 100 parts by mass of the total amount of the alcohol component and the carboxylic acid component. More preferably, it is 0.1 parts by mass or less.

[Styrene resin segment]
As the styrene resin segment, those obtained by addition polymerization of a raw material monomer containing a styrene compound are preferable.
As the styrene compound, at least styrene or a styrene derivative such as α-methylstyrene or vinyltoluene is used.

  The content of the styrene compound is preferably 60% by mass or more, more preferably 70% by mass or more, still more preferably 80% by mass or more, and still more preferably, from the viewpoint of fog suppression and durability in the raw material monomer of the styrene resin segment. From the viewpoint of low-temperature fixability, it is preferably 100% by mass or less, more preferably 99% by mass or less, and still more preferably 98% by mass or less.

  The raw material monomer for the styrene resin segment used in addition to the styrene compound includes: (meth) acrylic acid alkyl ester; ethylenically unsaturated monoolefins such as ethylene and propylene; diolefins such as butadiene; halovinyls such as vinyl chloride Vinyl esters such as vinyl acetate and vinyl propionate; ethylenic monocarboxylic esters such as dimethylaminoethyl (meth) acrylate; vinyl ethers such as vinyl methyl ether; vinylidene halides such as vinylidene chloride; N-vinyl pyrrolidone N-vinyl compounds such as

  The raw material monomer of the styrene resin segment used in addition to the styrene compound may be used alone or in combination of two or more. In the present specification, “(meth) acrylic acid” means at least one selected from acrylic acid and methacrylic acid.

  Among the raw material monomers of the styrene resin segment used in addition to the styrene compound, (meth) acrylic acid alkyl ester is preferable from the viewpoint of improving the low-temperature fixability of the toner. In view of the above, the carbon number of the alkyl group in the (meth) acrylic acid alkyl ester is preferably 1 or more, more preferably 2 or more, still more preferably 3 or more, and preferably 22 or less, more preferably 18 Hereinafter, it is more preferably 12 or less, and further preferably 8 or less. In addition, carbon number of this alkyl ester means carbon number derived from the alcohol component which comprises ester.

  Examples of (meth) acrylic acid alkyl esters include methyl (meth) acrylate, ethyl (meth) acrylate, (iso) propyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, (iso or tertiary) butyl (meth) Examples include acrylate, 2-ethylhexyl (meth) acrylate, (iso) octyl (meth) acrylate, (iso) decyl (meth) acrylate, and (iso) stearyl (meth) acrylate. Here, `` (iso or tertiary) '', `` (iso) '' means to include both the presence and absence of these prefixes, and the presence of these prefixes. If not, it indicates normal. Further, “(meth) acrylate” indicates that both acrylate and methacrylate are included.

  The content of the (meth) acrylic acid alkyl ester is preferably 1% by mass or more, more preferably 2% by mass or more from the viewpoint of low-temperature fixability in the raw material monomer of the styrene resin segment, and the same viewpoint Therefore, it is preferably 30% by mass or less, more preferably 20% by mass or less, and still more preferably 10% by mass or less.

  A resin obtained by addition polymerization of a raw material monomer containing a styrene compound and a (meth) acrylic acid alkyl ester is also referred to as a styrene- (meth) acrylic resin.

  The addition polymerization reaction of the raw material monomer of the styrene-based resin segment can be performed by a conventional method, for example, in the presence of a polymerization initiator such as dicumyl peroxide, a crosslinking agent, or the like, in the presence of an organic solvent or in the absence of a solvent. The temperature condition is preferably 110 ° C. or higher, more preferably 120 ° C. or higher, further preferably 130 ° C. or higher, and preferably 250 ° C. or lower, more preferably 235 ° C. or lower, still more preferably 220 ° C. or lower. is there.

  When an organic solvent is used in the addition polymerization reaction, xylene, toluene, methyl ethyl ketone, acetone or the like can be used. The amount of the organic solvent used is preferably about 10 parts by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the raw material monomer of the styrene resin segment.

(Amotropic monomer)
From the viewpoint of low temperature fixability and durability, the amorphous composite resin L1
(A) In addition to the raw material monomer of the polyester-based resin segment and the raw material monomer of the styrene-based resin segment, both reactive monomers capable of reacting with both the raw material monomer of the polyester-based resin segment and the raw material monomer of the styrene-based resin segment It is preferably a composite resin obtained by using
(B) A polyester monomer segment raw material monomer, a styrene resin segment raw material monomer, and an amphoteric monomer capable of reacting with any of the raw material monomers of both segments, comprising an alcohol component containing an aromatic diol and a carboxylic acid component More preferably, it is a composite resin obtained by using.

  When a raw material monomer for the polyester resin segment and a raw material monomer for the styrene resin segment are polymerized to obtain a composite resin, the polycondensation reaction and / or the addition polymerization reaction are preferably performed in the presence of both reactive monomers. Thereby, the composite resin becomes a composite resin in which the polyester resin segment and the styrene resin segment are bonded via the structural unit derived from the both reactive monomers, and the polyester resin segment and the styrene resin segment become finer, And uniformly dispersed.

That is, from the viewpoint of improving the durability and low-temperature fixability of the toner, the amorphous composite resin L1
(I) a raw material monomer for a polyester-based resin segment, comprising an alcohol component containing an alkylene oxide adduct of bisphenol A represented by formula (I) and a carboxylic acid component containing an aromatic dicarboxylic acid compound; It is a resin obtained by polymerizing a bifunctional monomer capable of reacting with either a raw material monomer of a styrene resin segment and (iii) a raw material monomer of a polyester resin segment or a raw material monomer of a styrene resin segment. preferable.

  As the both reactive monomers, at least one functional group selected from a hydroxyl group, a carboxy group, an epoxy group, a primary amino group and a secondary amino group in the molecule, preferably at least selected from a hydroxyl group and a carboxy group. A compound having one kind of functional group, more preferably a carboxy group and an ethylenically unsaturated bond is preferred, and by using such a bireactive monomer, the dispersibility of the resin as the dispersed phase can be further improved. it can. The both reactive monomers are preferably at least one selected from acrylic acid, methacrylic acid, fumaric acid, maleic acid and maleic anhydride. From the viewpoint of the reactivity of polycondensation reaction and addition polymerization reaction, acrylic acid is preferred. More preferred is methacrylic acid or fumaric acid. However, when used together with a polymerization inhibitor, a polyvalent carboxylic acid having an ethylenically unsaturated bond such as fumaric acid functions as a raw material monomer for the polyester resin segment. In this case, fumaric acid or the like is not a bireactive monomer but a raw material monomer for the polyester resin segment.

  From the viewpoint of low-temperature fixability, the amount of both reactive monomers used is preferably at least 1 mol, more preferably at least 2 mol, even more preferably at least 3 mol with respect to a total of 100 mol of the alcohol component of the polyester resin segment. From the viewpoint of durability, it is preferably 20 mol or less, more preferably 10 mol or less, and still more preferably 7 mol or less.

  In the amorphous composite resin L1, the mass ratio of the polyester resin segment to the styrene resin segment (polyester resin segment / styrene resin segment) is preferably 70/30 or more, more preferably from the viewpoint of low-temperature fixability. Is 75/25 or more, more preferably 80/20 or more, and from the viewpoint of durability, it is preferably 95/5 or less, more preferably 90/10 or less, and still more preferably 85/15 or less. In the above calculation, the mass of the polyester-based resin segment is an amount obtained by subtracting the amount (calculated value) of reaction water dehydrated by the polycondensation reaction from the mass of the raw material monomer of the polyester-based resin segment used. The amount of both reactive monomers is included in the raw material monomer amount of the polyester resin segment. The amount of the styrene resin segment is the amount of the raw material monomer of the styrene resin segment, but the amount of the polymerization initiator is included in the amount of the raw material monomer of the styrene resin segment.

[Physical properties of amorphous composite resin L1]
From the viewpoint of improving durability, the glass transition temperature of the amorphous composite resin L1 is preferably 45 ° C or higher, more preferably 50 ° C or higher, and further preferably 55 ° C or higher, and improves low-temperature fixability. From the viewpoint, it is preferably 80 ° C. or lower, more preferably 75 ° C. or lower, further preferably 70 ° C. or lower, and further preferably 65 ° C. or lower.

From the viewpoint of improving the low-temperature fixability, the acid value of the amorphous composite resin L1 is preferably 40 mgKOH / g or less, more preferably 30 mgKOH / g or less, still more preferably 20 mgKOH / g or less, and preferably 1 mgKOH. / g or more, more preferably 2 mgKOH / g or more.
In this invention, a glass transition temperature and an acid value are measured by the method as described in an Example.

[Amount of amorphous composite resin L1]
In step 1, the compounding amount of the amorphous composite resin L1 is preferably 10% by mass or more, more preferably 20% by mass or more, still more preferably 30% by mass or more, with respect to the total amount of the melt-kneaded product. The amount is preferably 80% by mass or less, more preferably 70% by mass or less, and still more preferably 60% by mass or less.

<Crystalline polylactic acid>
The degree of crystallinity of the crystalline polylactic acid is preferably 30% or more, more preferably 50% or more, still more preferably 70% or more, more preferably 80% or more, from the viewpoint of improving low-temperature fixability and durability. More preferably, it is 90% or more and 100% or less.

The crystalline polylactic acid may be a homopolymer of lactic acid or a copolymer of lactic acid and another hydroxycarboxylic acid.
Lactic acid that is a monomer of crystalline polylactic acid may be either L-lactic acid or D-lactic acid.

  Examples of other hydroxycarboxylic acids include hydroxycarboxylic acids having 3 to 8 carbon atoms, specifically, glycolic acid, hydroxybutyric acid, hydroxyvaleric acid, hydroxypentanoic acid, hydroxycaproic acid, hydroxyheptanoic acid, and the like. Can be mentioned.

  The content of lactic acid in the monomer constituting the crystalline polylactic acid is preferably 80 mol% or more, more preferably 90 mol% or more, and still more preferably substantially 100 mol%, from the viewpoint of improving the durability of the toner. It is. Therefore, polylactic acid is preferably a homopolymer of lactic acid rather than a copolymer of lactic acid and other hydroxycarboxylic acids.

  Crystalline polylactic acid can be produced according to a conventional method by polycondensation of lactic acid or polycondensation of lactic acid with another hydroxycarboxylic acid. In the present invention, crystalline polylactic acid such as “ “N-3000” (glass transition temperature: 63 ° C.), “N-4000” (glass transition temperature: 61 ° C.) (above, homopolymer of lactic acid, manufactured by Nature Works) can also be used.

  From the viewpoint of improving the durability of the toner, the number average molecular weight of the crystalline polylactic acid is preferably 60,000 or more, more preferably 100,000 or more, further preferably 150,000 or more, more preferably 180,000 or more, and the low temperature of the toner. From the viewpoint of improving the fixing property, it is preferably 300,000 or less, more preferably 250,000 or less, and still more preferably 200,000 or less.

  From the viewpoint of improving the durability of the toner, the weight average molecular weight of the crystalline polylactic acid is preferably 60,000 or more, more preferably 100,000 or more, further preferably 250,000 or more, further preferably 400,000 or more, and further preferably 450,000 or more. From the viewpoint of improving the low-temperature fixability of the toner, it is preferably 700,000 or less, more preferably 550,000 or less, and still more preferably 500,000 or less.

  The melting point of the crystalline polylactic acid is preferably 155 ° C. or higher, more preferably 160 ° C. or higher from the viewpoint of improving the durability of the toner, and preferably 180 ° C. from the viewpoint of improving the low-temperature fixability of the toner. Below, more preferably 175 ° C. or less.

  The mass ratio of amorphous composite resin L1 and crystalline polylactic acid (amorphous composite resin L1 / crystalline polylactic acid) blended in step 1 is preferably 30 from the viewpoint of improving the low-temperature fixability of the toner. / 70 or more, more preferably 35/65 or more, still more preferably 40/60 or more, still more preferably 45/55 or more, and from the viewpoint of improving durability, preferably 90/10 or less, more preferably 80/20 or less, more preferably 70/30 or less, and still more preferably 60/40 or less.

  As described above, the binder resin is a polystyrene-polyester-polylactic acid block copolymer in which a part of polylactic acid is substituted by transesterification between the polyester resin segment of the amorphous composite resin L1 and polylactic acid. Including polymers.

<Conditions for Step 1>
In step 1, melt kneading is preferably performed using a continuous multi-axis kneader from the viewpoint of low-temperature fixability and durability. Examples of the continuous multi-axis kneader include a horizontal polymerization tank using an extrusion flow and a forced extrusion reaction apparatus.
The continuous multiaxial kneader is preferably a continuous biaxial kneader.
The continuous multi-axis kneader includes, for example, a trough having an internal temperature control mechanism and two or more long-axis screws having paddles. The long-axis screws are arranged in parallel to each other along the long-axis direction in the trough. The ratio of the trough length to the paddle diameter (hereinafter also simply referred to as “L / D ratio”) is preferably 5 or more, more preferably 7 or more, and still more preferably 8 or more, from the viewpoint of easy adjustment of the melt-kneading conditions. And preferably 20 or less, more preferably 15 or less, and still more preferably 13 or less.
An example of a continuous multi-axis kneader is KRC kneader (manufactured by Kurimoto Steel Works, trade name “S1KRC kneader”).

  The residence time in step 1 is preferably 2 minutes or more, more preferably 3 minutes or more, still more preferably 4 minutes or more, still more preferably 5 minutes or more, from the viewpoint of improving low-temperature fixability and durability. From the viewpoint of improving the durability of the toner, it is preferably 90 minutes or less, more preferably 70 minutes or less, further preferably 60 minutes or less, more preferably 50 minutes or less, still more preferably 40 minutes or less, and even more preferably 30 minutes or less. More preferably, it is 20 minutes or less. The residence time refers to the time from when the resin is supplied to the continuous multi-axis kneader until it is discharged.

  In the transesterification reaction in Step 1, the transesterification rate based on polylactic acid is preferably 1% or more from the viewpoint of improving low-temperature fixability and durability of the toner during all ester bonds in polylactic acid. Preferably it is 3% or more, more preferably 5% or more, more preferably 6% or more, more preferably 8% or more, more preferably 10% or more, and preferably from the viewpoint of improving the durability of the toner. It is 30% or less, more preferably 25% or less, still more preferably 20% or less, further preferably 18% or less, further preferably 16% or less, and further preferably 15% or less.

The transesterification rate based on polylactic acid can be estimated from the amount of change in integrated intensity between the carbonyl carbon-derived peak of the polylactic acid ester bond and the carbonyl carbon-derived peak that appears after transesterification by the ¹³ C-NMR method. It can be determined by the method described in the examples.
The transesterification reaction in the present invention refers to a transesterification reaction that occurs between a component derived from polylactic acid and a component derived from polyester, and the transesterification reaction between components derived from polylactic acid and between components derived from polyester is Not included.

  In step 1, the melt kneading temperature is preferably 170 ° C. or higher, more preferably 180 ° C. or higher, and still more preferably 190 from the viewpoint of increasing the transesterification rate between polyester and polylactic acid and being excellent in low-temperature fixability and durability. From the viewpoint of excellent durability, it is preferably 230 ° C. or less, more preferably 220 ° C. or less, still more preferably 210 ° C. or less, and further preferably 200 ° C. or less.

  The present invention includes step 1 in the preparation of the toner raw material mixture. The resin composition obtained in step 1 is cooled and ground to a particle size of about 0.01 to 3 mm, and then continues as a toner raw material. It is preferable to use for a process.

[Step 2]
In Step 2, the melt-kneaded product obtained in Step 1, the amorphous resin H having a softening point of 122 ° C. or higher and 150 ° C. or lower, a polyester resin segment and a styrene resin segment, and a softening point of 80 ° C. The amorphous composite resin L2 having a temperature of 120 ° C. or lower, a colorant, and a release agent are mixed.

  In step 2, the blended amount of the melt-kneaded product obtained in step 1 is preferably 1% by mass or more, more preferably 5% by mass or more, still more preferably 10% by mass or more, based on the total amount of the binder resin. More preferably, it is 15% by mass or more, and preferably 50% by mass or less, more preferably 40% by mass or less, and further preferably 30% by mass or less.

<Amorphous resin H>
From the viewpoint of obtaining durability, the amorphous resin H has a softening point of 122 ° C or higher and 150 ° C or lower, preferably 125 ° C or higher, more preferably 130 ° C or higher, still more preferably 132 ° C or higher, and The temperature is preferably 145 ° C. or lower, more preferably 140 ° C. or lower, and still more preferably 138 ° C. or lower.

  Amorphous resin H is preferably a resin (hereinafter simply referred to as a polyester resin) at least partly from the viewpoint of obtaining a toner excellent in fog suppression, low-temperature fixability, and durability in a high temperature and high humidity environment. Also referred to as “polyester resin”, and more preferably a composite resin having a polyester resin segment and a styrene resin segment.

The polyester resin segment of the polyester resin and the composite resin is made of a polyester resin obtained by polycondensation of an alcohol component and a carboxylic acid component.
As the alcohol component, the carboxylic acid component, and the blending amounts thereof, the same examples as those of the amorphous composite resin L1 described above can be cited as preferred examples.
As the polyester-based resin segment of the composite resin, the same examples as those of the amorphous composite resin L1 described above can be cited as a preferred example.
Also in the composite resin, it is preferable to use a bireactive monomer, and the same examples as the above-described examples of the amorphous composite resin L1 can be given as preferred examples.
In the composite resin as the amorphous resin H, the mass ratio of the polyester resin segment to the styrene resin segment (polyester resin segment / styrene resin segment) is also in the same range as the above amorphous composite resin L1. It is mentioned as a suitable example.

[Physical properties of amorphous resin H]
The glass transition temperature of the amorphous resin H is preferably 45 ° C. or higher, more preferably 50 ° C. or higher, further preferably 55 ° C. or higher, from the viewpoint of improving durability, and the viewpoint of improving low-temperature fixability. Therefore, it is preferably 80 ° C. or lower, more preferably 75 ° C. or lower, further preferably 70 ° C. or lower, and further preferably 65 ° C. or lower.

The acid value of the amorphous resin H is preferably 40 mgKOH / g or less, more preferably 30 mgKOH / g or less, still more preferably 20 mgKOH / g or less, and preferably 1 mgKOH / g from the viewpoint of improving low-temperature fixability. g or more, more preferably 2 mgKOH / g or more.
The hydroxyl value of the amorphous resin H is preferably 5 mgKOH / g or more, more preferably 10 mgKOH / g, from the viewpoint of obtaining a toner excellent in fog prevention, low-temperature fixability, and durability in a high temperature and high humidity environment. More preferably, it is 15 mgKOH / g or more, preferably 50 mgKOH / g or less, more preferably 40 mgKOH / g or less, and further preferably 30 mgKOH / g or less.

[Amount of amorphous resin H]
In step 2, the blending amount of the amorphous resin H is preferably 10% by mass or more, more preferably 20% by mass or more, still more preferably 30% by mass or more based on the total amount of the binder resin. Preferably it is 80 mass% or less, More preferably, it is 70 mass% or less, More preferably, it is 60 mass% or less.

<Amorphous composite resin L2>
The amorphous composite resin L2 has a polyester resin segment and a styrene resin segment from the viewpoint of obtaining a toner excellent in fog prevention, low temperature fixability, and durability in a high temperature and high humidity environment.
The amorphous composite resin L2 has a softening point of 80 ° C. or higher and 120 ° C. or lower, preferably 90 ° C. or higher, more preferably 95 ° C. or higher, from the viewpoint of obtaining a toner having excellent low-temperature fixability and durability. Preferably it is 100 degreeC or more, More preferably, it is 105 degreeC or more, Preferably it is 115 degreeC or less, More preferably, it is 113 degreeC or less, More preferably, it is 110 degreeC or less.

The polyester resin segment of the amorphous composite resin L2 is made of a polyester resin obtained by polycondensation of an alcohol component and a carboxylic acid component.
As the alcohol component, the carboxylic acid component, and the blending amounts thereof, the same examples as those of the amorphous composite resin L1 described above can be cited as preferred examples.
As the polyester-based resin segment of the amorphous composite resin L2, those similar to the examples of the amorphous composite resin L1 described above can be cited as preferred examples.
Also in the amorphous composite resin L2, it is preferable to use both reactive monomers, and examples similar to the above-described examples of the amorphous composite resin L1 are given as preferred examples.
As a suitable example, the mass ratio of the polyester resin segment to the styrene resin segment (polyester resin segment / styrene resin segment) in the amorphous composite resin L2 is also in the same range as the amorphous composite resin L1. Can be mentioned.
The amorphous composite resin L2 used in step 2 is preferably the same resin as the amorphous composite resin L1 used in step 1 from the viewpoint of improving low-temperature fixability and durability.

[Physical properties of amorphous composite resin L2]
From the viewpoint of improving durability, the glass transition temperature of the amorphous composite resin L2 is preferably 45 ° C. or higher, more preferably 50 ° C. or higher, and further preferably 55 ° C. or higher, and improves low-temperature fixability. From the viewpoint, it is preferably 80 ° C. or lower, more preferably 75 ° C. or lower, further preferably 70 ° C. or lower, and further preferably 65 ° C. or lower.

From the viewpoint of improving low-temperature fixability, the acid value of the amorphous composite resin L2 is preferably 40 mgKOH / g or less, more preferably 30 mgKOH / g or less, still more preferably 20 mgKOH / g or less, and preferably 1 mgKOH. / g or more, more preferably 2 mgKOH / g or more.
The hydroxyl value of the amorphous composite resin L2 is preferably 10 mg KOH / g or more, more preferably 15 mg KOH / g, from the viewpoint of obtaining a toner excellent in fog suppression, low-temperature fixability, and durability in a high temperature and high humidity environment. g or more, more preferably 20 mgKOH / g or more, more preferably 25 mgKOH / g or more, more preferably 30 mgKOH / g or more, and preferably 80 mgKOH / g or less, more preferably 70 mgKOH / g or less, more preferably 60 mgKOH. / g or less, more preferably 50 mgKOH / g or less.

[Amount of amorphous composite resin L2]
In step 2, the compounding amount of the amorphous composite resin L2 is preferably 5% by mass or more, more preferably 10% by mass or more, still more preferably 20% by mass or more, based on the total amount of the binder resin. The amount is preferably 60% by mass or less, more preferably 50% by mass or less, and still more preferably 40% by mass or less.

<Colorant>
As the colorant, all of dyes and pigments used as toner colorants can be used, such as carbon black, phthalocyanine blue, permanent brown FG, brilliant first scarlet, pigment green B, rhodamine-B base, Solvent Red 49, Solvent Red 146, Solvent Blue 35, Quinacridone, Pigment Red 57; 1, Disazo Yellow and the like can be used, and the toner obtained may be either black toner or color toner.

  The blending amount of the colorant is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and preferably 40 parts by mass with respect to 100 parts by mass of the binder resin from the viewpoint of low-temperature fixability and durability. Part or less, more preferably 20 parts by weight or less, still more preferably 10 parts by weight or less.

<Release agent>
Examples of the mold release agent include wax, and more specifically, polypropylene wax, polyethylene wax, polypropylene polyethylene copolymer wax; hydrocarbon wax such as microcrystalline wax, paraffin wax, Fischer-Tropsch wax, and sazol wax. Or their oxides; carnauba wax, montan wax or ester waxes thereof such as deoxidized wax, fatty acid ester wax; fatty acid amides, fatty acids, higher alcohols, fatty acid metal salts, etc. Or two or more can be used. Among these, ester waxes are preferable from the viewpoint of obtaining a toner having excellent fog suppression, low temperature fixability, and durability under a high temperature and high humidity environment.

  The melting point of the release agent is preferably 60 ° C. or higher, more preferably 70 ° C. or higher from the viewpoint of durability, and preferably 160 ° C. or lower, more preferably 100 ° C. or lower, from the viewpoint of low-temperature fixability. More preferably, it is 80 degrees C or less.

  The compounding amount of the release agent is preferably 0.5 parts by mass or more from the viewpoint of low temperature fixability and offset resistance of the toner and dispersibility in the binder resin with respect to 100 parts by mass of the binder resin. Preferably, it is 1.0 part by mass or more, more preferably 1.5 part by mass or more, and from the same viewpoint, it is preferably 10 parts by mass or less, more preferably 8 parts by mass or less, and further preferably 7 parts by mass or less.

<Charge control agent>
In step 2, a charge control agent may be further mixed.
The charge control agent is not particularly limited, and either a positively chargeable charge control agent or a negatively chargeable charge control agent may be used.
Examples of positively chargeable charge control agents include nigrosine dyes such as “Nigrosine Base EX”, “Oil Black BS”, “Oil Black SO”, “Bontron N-01”, “Bontron N-04”, “Bontron N-07 ”,“ Bontron N-09 ”,“ Bontron N-11 ”(manufactured by Orient Chemical Co., Ltd.) and the like; triphenylmethane dyes containing tertiary amines as side chains, quaternary ammonium salt compounds such as“ Bontron P-51 "(manufactured by Orient Chemical Industry Co., Ltd.), cetyltrimethylammonium bromide," COPY CHARGE PX VP435 "(manufactured by Clariant), etc .; polyamine resin such as" AFP-B "(manufactured by Orient Chemical Industry Co., Ltd.) Imidazole derivatives such as “PLZ-2001” and “PLZ-8001” (manufactured by Shikoku Kasei Kogyo Co., Ltd.); styrene-acrylic resins such as “FCA-701PT” (Fujikura Chemical) Etc., Ltd.) Co., Ltd., and the like.

In addition, as the negatively chargeable charge control agent, metal-containing azo dyes such as “Varifast Black 3804”, “Bontron S-31”, “Bontron S-32”, “Bontron S-34”, “Bontron S-36” (Above, made by Orient Chemical Co., Ltd.), “Eisenspiron Black TRH”, “T-77” (made by Hodogaya Chemical Co., Ltd.), etc .; metal compounds of benzylic acid compounds, such as “LR-147” , “LR-297” (manufactured by Nippon Carlit Co., Ltd.), etc .; metal compounds of salicylic acid compounds such as “Bontron E-81”, “Bontron E-84”, “Bontron E-88”, “Bontron E-” "304" (made by Orient Chemical Co., Ltd.), "TN-105" (made by Hodogaya Chemical Co., Ltd.), etc .; copper phthalocyanine dyes; quaternary ammonium salts such as "COPY CHARGE NX VP434" (made by Clariant) Nitroimidazole derivatives ; Organometallic compounds, and the like.
Among charge control agents, negatively chargeable charge control agents are preferable, and metal compounds of salicylic acid compounds are more preferable.

  The blending amount of the charge control agent is preferably 0.01 parts by mass or more, more preferably 0.05 parts by mass or more, still more preferably 0.1 parts by mass or more, with respect to 100 parts by mass of the binder resin, from the viewpoint of low-temperature fixability and durability. From the same viewpoint, it is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, and still more preferably 3 parts by mass or less.

  In step 2, additives such as magnetic powder, fluidity improver, conductivity modifier, reinforcing filler such as fibrous substance, antioxidant, anti-aging agent, and cleaning improver may be mixed. .

<Conditions for step 2>
The mixing in step 2 is performed using a mixer such as a Henschel mixer or a ball mill, for example. Among these, it is preferable to use a Henschel mixer.

[Step 3]
In step 3, the mixture obtained in step 2 is melt-kneaded.
The melt kneading can be performed using a known kneader such as a hermetic kneader, a single or twin screw extruder, and an open roll kneader. It is possible to use an open roll type kneader from the viewpoint of efficiently and highly dispersing additives such as a colorant, a charge control agent, and a release agent in the toner without repeating kneading and using a dispersion aid. Preferably, the open roll kneader is provided with a supply port and a kneaded product discharge port along the axial direction of the roll.

  The open roll type kneader refers to a kneading section that is not sealed and released, and can easily dissipate the kneading heat generated during kneading. The continuous open roll type kneader is preferably a kneader equipped with at least two rolls, and the continuous open roll type kneader used in the present invention comprises two rolls having different peripheral speeds, That is, it is a kneader equipped with two rolls, a high rotation side roll with a high peripheral speed and a low rotation side roll with a low peripheral speed. From the viewpoint of improving the dispersibility of additives such as release agents, colorants and charge control agents in the toner, reducing the mechanical force during melt kneading, suppressing heat generation, and reducing the temperature during melt kneading. From the point of view, it is preferable that the high rotation side roll is a heating roll and the low rotation side roll is a cooling roll.

The temperature of the roll can be adjusted by, for example, the temperature of the heat medium passed through the roll.
The heating temperature in the roll is preferably 20 ° C. or higher, more preferably 30 ° C. or higher, and preferably 200 ° C. or lower, more preferably 150 ° C. or lower, from the viewpoint of the dispersibility of the additive.

The roll rotation peripheral speed of the high rotation side roll is the viewpoint of improving the dispersibility in the toner of additives such as wax, colorant, charge control agent, etc., the viewpoint of reducing the mechanical force during melt kneading and suppressing heat generation Therefore, it is preferably 20 m / min or more, more preferably 25 m / min or more, still more preferably 30 m / min or more, and preferably 50 m / min or less, more preferably 45 m / min or less, still more preferably 40 m / min. It is as follows.
From the same viewpoint, the roll rotation peripheral speed of the low-rotation side roll is preferably 10 m / min or more, more preferably 15 m / min or more, still more preferably 20 m / min or more, and preferably 40 m / min or less. More preferably, it is 36 m / min or less, More preferably, it is 33 m / min or less.

  The structure, size, material, etc. of the roll are not particularly limited, and the roll surface may be any of smooth, corrugated, uneven, etc., but the kneading share is increased, and the colorant, charge control agent, mold release From the viewpoint of improving the dispersibility of additives such as additives in the toner, reducing the mechanical force during melt-kneading, and suppressing heat generation, each roll surface may have a plurality of spiral grooves. preferable.

[Step 4]
In step 4, the melt-kneaded product obtained in step 3 is pulverized and classified.
Prior to pulverization, the melt-kneaded product obtained in step 3 is preferably cooled to such an extent that pulverization is possible. The cooling may be performed using a cooling device, but may be natural cooling.

  The pulverization may be performed in multiple stages. For example, the resin kneaded material obtained by curing the melt-kneaded material may be coarsely pulverized to about 1 to 5 mm and further pulverized to a desired particle size.

As a pulverizer suitably used for coarse pulverization, a hammer mill, an atomizer, a rotoplex, and the like can be given.
Examples of the pulverizer preferably used for fine pulverization include a fluidized bed jet mill, a collision plate jet mill, and a rotary mechanical mill. Among these, from the viewpoint of pulverization efficiency, it is preferable to use a fluidized bed jet mill and a collision plate jet mill, and it is more preferable to use a fluidized bed jet mill.

  Examples of classifiers used for classification include rotor classifiers, airflow classifiers, inertia classifiers, and sieve classifiers. At the time of classification, the pulverized product removed by insufficient pulverization may be subjected to pulverization again, and pulverization and classification may be repeated as necessary.

[Step 5]
The production method of the present invention may further include the following step 5.
Step 5: Step of mixing the toner particles obtained in the classification in Step 4 and an external additive Examples of external additives include hydrophobic silica, titanium oxide fine particles, alumina fine particles, cerium oxide fine particles, inorganic fine particles such as carbon black, and polycarbonate. And polymer fine particles such as polymethyl methacrylate and silicone resin. Among these, hydrophobic silica is preferable.
When the toner particles are subjected to surface treatment using an external additive, the amount of the external additive added is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and still more preferably 100 parts by mass of the toner particles. 1 part by mass or more, and preferably 5 parts by mass or less, more preferably 4 parts by mass or less, and further preferably 3 parts by mass or less.

The volume median particle size (D ₅₀ ) of the electrophotographic toner obtained by the production method of the present invention is preferably 2 μm or more, more preferably 3 μm or more, and still more preferably, from the viewpoint of low-temperature fixability and durability of the toner. It is 4 μm or more, and preferably 20 μm or less, more preferably 15 μm or less, and further preferably 10 μm or less.
The volume median particle size (D ₅₀ ) is measured by the method described in the examples.

  About each physical-property value of resin etc., it measured and evaluated by the following method.

[Measuring method]
[Softening point of resin]
Using a flow tester (Shimadzu Corporation, CFT-500D), a 1 g sample was heated at a heating rate of 6 ° C / min, and a load of 1.96 MPa was applied by a plunger, from a nozzle with a diameter of 1 mm and a length of 1 mm. Extrude. The amount of plunger drop of the flow tester is plotted against the temperature, and the temperature at which half of the sample flows out is taken as the softening point.

[Maximum peak temperature of resin endotherm]
Using a differential scanning calorimeter “Q-100” (manufactured by TA Instruments Japan Co., Ltd.), 0.01 to 0.02 g of sample is weighed in an aluminum pan and cooled from room temperature to 0 ° C. at a temperature drop rate of 10 ° C./min. Hold at 0 ° C. for 1 minute. Thereafter, the measurement is performed at a heating rate of 10 ° C./min. Among the observed endothermic peaks, the temperature of the peak on the highest temperature side is defined as the highest endothermic peak temperature.

[Glass transition temperature of resin and polylactic acid]
Using a differential scanning calorimeter “Q-100” (manufactured by TA Instruments Japan Co., Ltd.), 0.01 to 0.02 g of sample was weighed into an aluminum pan, heated to 200 ° C., and the temperature decreasing rate was 10 ° C. Cooled to 0 ° C./min. Next, the sample is heated at a heating rate of 10 ° C./min and measured. The glass transition temperature is defined as the temperature at the intersection of the base line extension below the maximum peak temperature of endotherm and the tangent line indicating the maximum slope from the peak rising portion to the peak apex.

[Acid value and hydroxyl value of resin]
Measured by the method of JIS K0070. However, only the measurement solvent is changed from the mixed solvent of ethanol and ether specified in JIS K0070 to the mixed solvent of acetone and toluene (acetone: toluene = 1: 1 (volume ratio)).

[Polylactic acid crystallinity]
X-ray source: Cu / Kα-radiation, tube voltage: 40 kV, tube current: 120 mA, measurement range using powder X-ray diffraction (XRD) measuring device “Rigaku RINT 2500VC X-RAY diffractometer” (manufactured by Rigaku Corporation) : The diffraction intensity (2θ) is 5 to 40 °, the scanning speed is 5.0 ° / min, and the peak intensity is measured by the continuous scanning method. The sample is crushed and then used for measurement. From the obtained X-ray diffraction, the value calculated from the following formula is defined as the crystallinity of polylactic acid.

[Melting point of polylactic acid]
Using a differential scanning calorimeter “DSC Q20” (manufactured by TA Instruments Japan Co., Ltd.), 0.01 to 0.02 g of sample is weighed into an aluminum pan, and the temperature is increased from 20 ° C. to 200 ° C. at a heating rate of 10 ° C./min. Warm up. The highest endothermic peak temperature observed from the obtained melting endothermic curve is defined as the melting point of polylactic acid.

[Average molecular weight of polylactic acid]
The molecular weight distribution is measured by the gel permeation chromatography (GPC) method according to the following method, and the number average molecular weight and the weight average molecular weight are obtained.
(1) Preparation of sample solution The sample is dissolved in chloroform at 25 ° C so that the concentration is 0.5 g / 100 ml. Next, this solution is filtered using a fluororesin filter “DISMIC-25JP” (manufactured by ADVANTEC) having a pore size of 0.2 μm to remove insoluble components to obtain a sample solution.
(2) Molecular weight measurement Using the following measuring device and analytical column, flow chloroform at 1 mL / min as the eluent, and stabilize the column in a constant temperature bath at 40 ° C. Inject 100 μL of the sample solution into the sample and perform measurement. The molecular weight of the sample is calculated based on a calibration curve prepared in advance. There are several types of monodisperse polystyrene (A-500 (5.0 × 10 ² ), A-1000 (1.01 × 10 ³ ), A-2500 (2.63 × 10 ³ ), A -5000 (5.97 × 10 ³ ), F-1 (1.02 × 10 ⁴ ), F-2 (1.81 × 10 ⁴ ), F-4 (3.97 × 10 ⁴ ), F-10 (9.64 × 10 ⁴ ), F -20 (1.90 × 10 ⁵ ), F-40 (4.27 × 10 ⁵ ), F-80 (7.06 × 10 ⁵ ), F-128 (1.09 × 10 ⁶ )) are used as standard samples. The molecular weight is in parentheses.
Measuring device: HLC-8220GPC (manufactured by Tosoh Corporation)
Analytical column: GMHXL + G3000HXL (Tosoh Corporation)

[Volume Median Particle Size D _{50 of} Toner]
Measuring machine: Coulter Multisizer II (Beckman Coulter, Inc.)
Aperture diameter: 100μm
Analysis software: Coulter Multisizer AccuComp version 1.19 (Beckman Coulter, Inc.)
Electrolyte: Isoton II (Beckman Coulter, Inc.)
Dispersion: Emulgen 109P (manufactured by Kao Corporation, polyoxyethylene lauryl ether, HLB: 13.6) is dissolved in the electrolyte so as to have a concentration of 5% by mass.
Dispersion condition: 10 mg of a measurement sample was added to 5 mL of the dispersion, and dispersed for 1 minute with an ultrasonic disperser, then 25 mL of the electrolyte was added, and further dispersed for 1 minute with an ultrasonic disperser. Prepare sample dispersion.
Measurement conditions: The sample dispersion was added to 100 mL of the electrolyte so that the particle size of 30,000 particles could be measured in 20 seconds, and 30,000 particles were measured. Determine the median particle size (D ₅₀ ).

[Evaluation method]
(Low temperature fixability)
The printer “OKI MICROLINE 5400” (made by Oki Data Co., Ltd.), modified to take unfixed images, was filled with toner, and an unfixed image of 3 × 4 cm square was printed. Using an external fixing device modified from OKI MICROLINE 3010 (manufactured by Oki Data Co., Ltd.), increasing the fixing roll temperature in increments of 5 ° C from 100 ° C to 200 ° C at a fixing roll rotation speed of 120mm / sec. However, this unfixed image was fixed at each temperature to obtain a fixed image. Attach "Scotch (registered trademark) Mending Tape 810" (Sumitomo 3M Limited, width: 18mm) to the image obtained at each fixing temperature, rub it 3 times from the top with a 500g weight, and then apply the tape. I peeled it off. The image density before and after the tape was peeled off was measured using an image density measuring instrument “GREGSPM50” (Gretag), and the image density ratio before and after rubbing ([image density after rubbing / image density before rubbing] The temperature at which x100) first exceeded 90% was defined as the minimum fixing temperature, and was used as an index for low-temperature fixability. A smaller value indicates better low-temperature fixability, but is preferably 150 ° C. or lower.

〔durability〕
Toner is mounted on ID cartridge “ML-5400, Image Drum” manufactured by Oki Data Co., Ltd., modified so that the developing roller can be seen visually. 70r / min under conditions of 30 ° C and 50% humidity An idling operation was performed at (equivalent to 36 ppm), and developing roller filming was visually observed. The time until filming occurred was used as an index of durability. The durability indicates that the longer the time until the developing roller filming occurs, the better the durability is, but it is preferably 9 hours or more, more preferably 10 hours or more.

[Fog suppression]
Mount the toner on the non-magnetic one-component developing device "MicroLine 5400" (Oki Data Co., Ltd.) and leave it for 12 hours in an environment with a temperature of 40 ° C and a relative humidity of 80%. It was. Thereafter, the toner remaining on the organic photoreceptor (OPC) drum was collected by attaching “Scotch Mending Tape” (Sumitomo 3M Co., Ltd., width: 18 mm). Using the image density measuring device “GREGSPM50” (Gretag) to measure the image density with the mending tape itself, ΔE (ΔE = √ (L ^{* 2} + a ^{* 2} + b ^{* 2} )) was measured to evaluate fog suppression. .

[Examples of resin production]
Production Examples H1, L1-5: Resins H-1, L-1-5
Put the polyester resin segment raw material monomer and esterification catalyst other than trimellitic anhydride shown in the table in a 10-liter four-necked flask equipped with a nitrogen inlet tube, dehydrator tube, stirrer and thermocouple, and maintain at 230 ° C. The reaction was performed for 12 hours, and then the reaction was performed at 8.3 kPa for 1 hour. The temperature was lowered to 160 ° C., and the raw material monomer of the styrene resin segment, the bireactive monomer, and dicumyl peroxide were added dropwise over 1 hour using a dropping funnel. After aging the addition polymerization reaction for 1 hour while maintaining the temperature at 160 ° C., the temperature was raised to 210 ° C., and the raw material monomer of the styrene resin segment was removed at 8.3 kPa for 1 hour. Further, trimellitic anhydride was added at 210 ° C. and reacted until the desired softening point was reached to obtain an amorphous composite resin.

Production Example L6: Resin L-6
Raw material monomer of polyester-based resin segment other than fumaric acid and trimellitic anhydride shown in the table, 40 g of tin (II) 2-ethylhexanoate and 1 g of gallic acid were equipped with a nitrogen introduction tube, dehydration tube, stirrer and thermocouple The reaction was carried out at 230 ° C. for 8 hours in a 10-liter four-necked flask. After the reaction, the mixture was reacted at 8.3 kPa for 1 hour. Furthermore, the temperature was lowered to 210 ° C., and 5 g of trimellitic anhydride, fumaric acid and tertiary butyl catechol were added to obtain an amorphous polyester resin.

[Manufacture of toner for electrophotography]
Examples 1-4, Comparative Examples 1-3
[Step 1]
50 parts by mass of amorphous resin L1 and polylactic acid (manufactured by Nature Works, trade name: N-3000, number average molecular weight Mn: 188,000, weight average molecular weight Mw: 472,000, melting point: 170 ° C., crystallinity 92%) The mass parts were melt-kneaded using a continuous biaxial kneader “S1KRC kneader” (manufactured by Kurimoto Steel Corporation, shaft diameter 25 mm, shaft length 255 mm, L / D ratio 10.2). The operating conditions of the biaxial continuous kneader were a roll peripheral speed of 15 m / min and a kneaded product discharge temperature of 200 ° C. The feed rate of the raw material mixture was 5 kg / hr, and the average residence time was about 5 minutes. After cooling the kneaded product obtained in step 1, the mixture is coarsely pulverized with a Rotoplex (manufactured by Hosokawa Micron Corporation), and melt kneaded product A is obtained as a coarsely pulverized product having a volume particle size of 2 mm or less using a sieve having an opening of 2 mm. Got.
In Comparative Example 3, step 1 is not performed.

[Step 2]
20 parts by mass of melt-kneaded product A obtained in step 1, 50 parts by mass of amorphous resin H, 30 parts by mass of amorphous composite resin L2, colorant “ECB-301” (manufactured by Dainichi Seika Kogyo Co., Ltd., 3 parts by weight of phthalocyanine blue (PB15: 3), 3 parts by weight of release agent “WEP-9” (manufactured by NOF Corporation, synthetic ester wax, melting point 72 ° C.), and negative charge control agent “Bontron E- 84 parts (manufactured by Orient Chemical Co., Ltd.) was mixed for 1 minute using a Henschel mixer (manufactured by Nippon Coke Industries Co., Ltd.).

[Step 3]
Melting by mixing and kneading the mixture obtained in step 2 using a continuous two-open roll type kneader “NEDEX” (manufactured by Nippon Coke Industries, Ltd., roll outer diameter: 14 cm, effective roll length: 80 cm) A kneaded product B was obtained. The operating conditions of the continuous two-open roll type kneader were high rotation side roll (front roll) peripheral speed 32.4m / min, low rotation side roll (back roll) peripheral speed 21.7m / min, and roll gap 0.1mm. It was. The heating medium temperature and cooling medium temperature in the roll are 145 ° C. on the raw material input side of the high rotation side roll and 100 ° C. on the kneaded material discharge side, 75 ° C. on the raw material input side of the low rotation side roll and 35 ° C. on the kneaded material discharge side. there were. The feed rate of the raw material mixture was 10 kg / hr, and the average residence time was about 3 minutes.

[Step 4]
After the melt-kneaded product B obtained in step 3 is cooled, it is coarsely pulverized by a pulverizer “Rotoplex” (manufactured by Hosokawa Micron Co., Ltd.), and coarsely pulverized with a sieve having an opening of 2 mm and a volume particle size of 2 mm or less. I got a thing. The resulting coarsely pulverized product was finely pulverized using a DS2 airflow classifier (impact plate type, manufactured by Nippon Pneumatic Industry Co., Ltd.), adjusting the pulverization pressure so that the volume median particle size became 8.0 μm. . The resulting finely pulverized product is classified by adjusting the static pressure (internal pressure) so that the volume median particle size is 8.5 μm using a DSX2 type airflow classifier (manufactured by Nippon Pneumatic Industry Co., Ltd.) Toner mother particles were obtained.
[Step 5]
100 parts by weight of the toner base particles obtained and hydrophobic silica “R972” (manufactured by Nippon Aerosil Co., Ltd., average particle size: 16 nm) as an external additive, 1 part by weight, hydrophobic silica “NAX50” (manufactured by Nippon Aerosil Co., Ltd.) The average particle size was 30 nm. 1 part by mass was mixed for 3 minutes at 2100 r / min (circumferential speed 29 m / sec) with a Henschel mixer (manufactured by Nihon Coke Kogyo Co., Ltd.) to obtain a toner.

  By comparing the toners of Examples 1 to 4 with the toners of Comparative Examples 1 and 2, according to the production method of the present invention, when polylactic acid is introduced into the toner, It can be understood that an electrophotographic toner having excellent fog suppression at low temperature and good low temperature fixability and durability can be obtained.

Claims (9)

A method for producing an electrophotographic toner comprising the following steps 1 to 4.
Step 1: Amorphous composite resin L1 having a polyester resin segment and a styrene resin segment, having a hydroxyl value of 10 mgKOH / g to 80 mgKOH / g and a softening point of 80 ° C to 120 ° C, and crystalline polylactic acid And melt kneading at 140 ° C. to 230 ° C. Step 2: The melt-kneaded product obtained in Step 1, amorphous resin H having a softening point of 122 ° C. to 150 ° C., and a polyester resin segment A step of mixing an amorphous composite resin L2 having a styrene-based resin segment and a softening point of 80 ° C. or higher and 120 ° C. or lower, a colorant, and a release agent Step 3: Mixing the mixture obtained in Step 2 Step of melt-kneading Step 4: Step of pulverizing and classifying the melt-kneaded product obtained in Step 3   The amorphous composite resin L1 reacts with any of the raw material monomer of the polyester resin segment, the raw material monomer of the styrene resin segment, and the raw material monomer of both segments, which includes an alcohol component containing an aromatic diol and a carboxylic acid component. The method for producing an electrophotographic toner according to claim 1, which is a composite resin obtained by using the obtained both reactive monomers.   The mass ratio between the polyester resin segment and the styrene resin segment of the amorphous composite resin L1 [polyester resin segment / styrene resin segment] is 70/30 or more and 95/5 or less. A method for producing the electrophotographic toner according to claim.   The method for producing an electrophotographic toner according to claim 1, wherein the softening point of the amorphous composite resin L1 is 100 ° C. or higher and 115 ° C. or lower.   The method for producing an electrophotographic toner according to claim 1, wherein the amorphous resin H has a softening point of 125 ° C. or more and 140 ° C. or less.   The method for producing an electrophotographic toner according to claim 1, wherein the amorphous resin H is a composite resin having a polyester resin segment and a styrene resin segment.   The method for producing an electrophotographic toner according to claim 1, wherein the crystallinity of the crystalline polylactic acid is 30% or more.   The method for producing an electrophotographic toner according to claim 1, wherein the melt kneading temperature in Step 1 is 180 ° C. or higher and 200 ° C. or lower.   An electrophotographic toner obtained by the steps including the steps 1 to 4.