Toner for developing electrostatic images and method for forming image

Abstract

To provide a toner for developing electrostatic images which is environmentally friendly by increasing the ratio of materials derived from biomass and can attain fixability and heat-resistive storage property at the same time.SOLUTION: A toner for developing electrostatic images is a toner for developing electrostatic images including toner base particles containing a binder resin and a coloring agent. The binder resin includes a polymer having a structural unit expressed by the following general formula (1), and the concentration of a radioactive carbon isotope 14C is at least 21.5 pMC. [Chemical Formula 1] [In general formula (1), R1 represents a hydrogen atom or a methyl group, and R2 represents a C6 to C12 alicyclic hydrocarbon group.]SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a toner for developing electrostatic images, and more particularly to a toner for developing electrostatic images that is capable of achieving both fixability and heat-resistant storage stability while increasing the proportion of biomass-derived raw materials. [Background technology]

[0002] Patent Document 1 discloses a technology that uses biomass-derived resin and recycled resin as resin particles for toner that are excellent in fixing property and storage stability and are environmentally friendly. However, when the ratio of biomass-derived raw materials is high, the fixing property and heat-resistant storage property cannot be sufficiently ensured. Therefore, in order to produce an environmentally friendly toner, it is necessary to achieve both a further increase in the ratio of biomass-derived raw materials and an improvement in the fixing property and heat-resistant storage property. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2023-67691 A Summary of the Invention [Problem to be solved by the invention]

[0004] The present invention has been made in consideration of the above problems and circumstances. The problem to be solved by the present invention is to provide a toner for developing electrostatic images and an image forming method which is environmentally friendly by increasing the ratio of biomass-derived raw materials and which is capable of achieving both fixing properties and heat-resistant storage stability. [Means for solving the problem]

[0005] In order to solve the above problems, the present inventors have investigated the causes of the above problems, and have found that by using a biomass-derived raw material and an alicyclic alkyl monomer, it is possible to use a higher proportion of the biomass-derived raw material while maintaining fixability and heat-resistant storage stability. That is, the above-mentioned problems of the present invention are solved by the following means.

[0006] 1. A toner for developing electrostatic images, comprising toner base particles containing a binder resin and a colorant, The binder resin contains a polymer having at least a structural unit represented by the following general formula (1): Radioactive carbon isotopes 14 C concentration is 21.5 pMC or more 2. A toner for developing electrostatic images. [ka] [In general formula (1), R 1 R represents a hydrogen atom or a methyl group. 2 represents an alicyclic hydrocarbon group having 6 to 12 carbon atoms.]

[0007] 2. The weight average molecular weight of the polymer having the structural unit represented by the general formula (1) is within the range of 5,000 to 100,000 as measured by gel permeation chromatography. 2. The toner for developing electrostatic images according to claim 1,

[0008] 3. Radioactive carbon isotopes 14 C concentration is 32.3 pMC or more 2. The toner for developing electrostatic images according to claim 1,

[0009] 4. R in the general formula (1) 2 is an isobornyl group 2. The toner for developing electrostatic images according to claim 1,

[0010] 5. R in the general formula (1) 1 is a methyl group 2. The toner for developing electrostatic images according to claim 1,

[0011] 6. The toner base particles contain crystalline polyester in the range of 5 to 20% by mass. 2. The toner for developing electrostatic images according to claim 1,

[0012] 7. An image forming method using a toner for developing an electrostatic image, comprising the steps of: The toner for developing an electrostatic image is the toner for developing an electrostatic image according to any one of items 1 to 6. 1. An image forming method comprising: Effect of the Invention

[0013] According to the above-mentioned means of the present invention, by increasing the ratio of biomass-derived raw materials, it is possible to provide a toner for developing electrostatic images and an image forming method which are environmentally friendly and capable of achieving both fixing properties and heat-resistant storage stability. Although the mechanism by which the effects of the present invention are manifested or the mechanism by which the effects of the present invention are acted upon has not been clearly understood, it is speculated as follows. The toner for developing electrostatic images of the present invention contains a radioactive carbon isotope. 14 Since the concentration of C is 21.5 pMC or more, the environmental compatibility ratio is high. Here, 21.5 pMC is converted into a biomass degree of 20%, which is often specified as the minimum biomass degree required to obtain various biomass-related certifications. However, when the degree of biomass conversion is high and the proportion of biomass raw material derived is large, fixability and heat-resistant storage stability cannot be sufficiently ensured. Therefore, in the present invention, it has been discovered that by using an alicyclic alkyl monomer among biomass-derived raw materials, it is possible to use a higher proportion of biomass-derived raw materials while maintaining fixability and heat-resistant storage stability. By using alicyclic alkyl monomers, the structure of the polymer side chain becomes bulky and the main chain becomes rigid. By increasing this rigid structure locally, the local intermolecular interaction (van der Waals force) between the polymer chains becomes stronger, and as a result, the heat-resistant storage property is improved. In addition, the factor for making the main chain rigid is R 1It is also possible to make the structure of the compound rigid by changing the hydrogen atom to a methyl group. That is, methacrylate is more preferable than acrylate. In addition, from the viewpoint of ensuring fixability and heat resistance, radioactive carbon isotopes 14 The C concentration is preferably 85.6 pMC (equivalent to a degree of biomass conversion of 80%) or less. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] The toner for developing electrostatic images of the present invention is a toner for developing electrostatic images, which comprises toner base particles containing a binder resin and a colorant, and the binder resin contains at least a polymer having a structural unit represented by the following general formula (1), and a radioactive carbon isotope is added to the toner. 14 The concentration of C is 21.5 pMC or more. [ka] [In general formula (1), R 1 R represents a hydrogen atom or a methyl group. 2 represents an alicyclic hydrocarbon group having 6 to 12 carbon atoms.] This feature is a technical feature common to or corresponding to each of the following embodiments.

[0015] As an embodiment of the present invention, the weight average molecular weight, measured by gel permeation chromatography, of the polymer having the structural unit represented by the general formula (1) is preferably within the range of 5000 to 100000. By having the average molecular weight within the range of 5000 to 100000, the heat-resistant storage stability and fixability are excellent.

[0016] The radioactive carbon isotopes 14 It is preferable that the concentration of C is 32.3 pMC or more in order to obtain a toner that is more environmentally friendly.

[0017] R in the general formula (1) 2 However, an isobornyl group is preferred in that the heat-resistant storage stability of the binder resin is improved.

[0018] R in the general formula (1) 1 However, a methyl group is preferred in that the main chain becomes rigid and the heat resistance and storage stability are excellent.

[0019] It is preferable that the toner base particles contain crystalline polyester in the range of 5 to 20% by mass in terms of improving fixability and heat-resistant storage stability.

[0020] The toner for developing electrostatic images of the present invention is suitably used in an image forming method.

[0021] The present invention, its components, and embodiments and aspects for carrying out the present invention will be described below. In this application, the symbol "to" is used to mean that the numerical values ​​before and after the symbol "to" are included as lower and upper limits.

[0022] [Toner for developing electrostatic images of the present invention] The toner for developing electrostatic images of the present invention is a toner for developing electrostatic images, which comprises toner base particles containing a binder resin and a colorant, and the binder resin contains at least a polymer having a structural unit represented by the following general formula (1), and a radioactive carbon isotope is added to the toner. 14 The concentration of C is 21.5 pMC or more. [ka] [In general formula (1), R 1 R represents a hydrogen atom or a methyl group. 2 represents an alicyclic hydrocarbon group having 6 to 12 carbon atoms.]

[0023] <Radioactive carbon isotopes 14 Concentration of C> The radioactive carbon isotopes 14 The concentration of C is 21.5 pMC or more, and preferably falls within the range of 32.3 to 85.6 pMC.

[0024] Radioactive carbon isotopes 14 The C concentration is the radioactive carbon isotope relative to the total carbon element in the toner. 14 C is the ratio of radioactive carbon isotopes14 The C concentration is known to be an indicator of biomass content. 14 The concentration of C indicates to what extent the organic components in the toner containing organic components are derived from biomass. 14 The unit of C concentration is pMC (percent Modern Carbon).

[0025] The carbon atoms that make up carbon dioxide in the atmosphere have stable isotopes 12 In addition to C, there are other radioactive carbon isotopes 14 C is contained in the atmosphere. 14 The concentration of C is kept roughly constant (107.5 pMC). Plants continue to take in carbon dioxide from the atmosphere while they are alive, so the amount of C in their cells is 14 The concentration of C in the atmosphere 14 The concentration is roughly the same as that of C (107.5 pMC). On the other hand, when a plant stops living activities, 14 The concentration of C decreases at a constant rate (half-life 5730 years). Since animals continue to consume plants directly or indirectly while maintaining their vital functions, the concentration of C in animal cells 14 The concentration of C in plant cells 14 The concentration of C shows a similar trend. Biomass is utilized relatively soon after the plant ceases its life activity. 14 The concentration of C in the atmosphere 14 The concentration is roughly the same as that of C (107.5 pMC). In contrast, fossil resources such as petroleum are used tens of thousands to hundreds of millions of years after the plants and animals from which they were derived ceased to have any life activity. 14 C is hardly detected. From the above, it is considered that chemical products using only fossil resources such as petroleum as raw materials 14 The concentration of C is approximately 0 pMC. On the other hand, chemical products that use biomass as a raw material are in proportion to the amount of biomass used. 14 The concentration of C increases.

[0026] Chemical products that use a large amount of biomass are carbon neutral, so even if they are burned, they do not significantly increase the concentration of carbon dioxide in the atmosphere. Therefore, chemical products that use a large amount of biomass are effective in reducing the burden on the environment.

[0027] The ratio of the mass of carbon atoms derived from biomass to the total mass of carbon atoms in the toner particles (also referred to as the biomass degree or bio-based carbon content) is calculated by the following formula: In the following formula, X is the radioactive carbon isotope content in the entire toner. 14 Represents the concentration of C. Biomass ratio [mass%] = (X / 107.5) x 100

[0028] Radioactive carbon isotopes 14 The C concentration can be measured, for example, using an accelerator mass spectrometer (AMS). 14 The concentration of C can be measured according to ASTM-D6866.

[0029] In addition, in the present invention, 14 The concentration of C can also be calculated by the following method. For example, a case will be taken where a radioactive carbon isotope is used in a monomer constituting an acrylic resin that is a binder resin for toner base particles. (i) For each monomer, calculate the value of A1 using the following formula. A1 = number of moles of monomer constituting acrylic resin × number of carbon atoms of the monomer (In the case of isobornyl acrylate (IBXMA) of the acrylic resin (1) in the examples described below, A1 = 0.1889 (see Table IV).)

[0030] (ii) Calculate the total value A2 of each of the calculated A1 values. (In the case of the acrylic resin (1), A2=1.9853 (see Table IV).)

[0031] (iii) For each monomer, calculate the value of B1 using the following formula: B1 = number of moles of monomer constituting acrylic resin × number of carbon atoms derived from biomass of the monomer (In the case of isobornyl acrylate, which is the acrylic resin (1), B1=0.1889 (see Table IV).)

[0032] (iv) Calculate the sum B2 of the calculated B1 values. (In the case of the acrylic resin (1), B2=0.7871 (see Table IV).)

[0033] (v) Calculate the degree of biomass conversion Y1 in the acrylic resin using the following formula. Degree of biomass in acrylic resin Y1 = (B2 / A2) x 100 (In the case of the acrylic resin (1), Y1 = (0.7871 / 1.9853) × 100 = 39.6% (see Table IV))

[0034] (vi) The degree of biomass conversion Y2 in the entire toner is calculated using the following formula. Biomass content in the entire toner Y2 = Y1 x Ratio of acrylic resin in the entire toner (In the case of toner 1 using the acrylic resin (1), Y2=39.6×74%=29.1% (see Table V))

[0035] (vii) From the following formula: 14 Calculate the concentration X of C. 14 C concentration X = (biomass conversion degree Y2 / 100) × 107.5 (In the case of Toner 1, X=(29.1 / 100)×107.5=31.3 (see Table V))

[0036] In the toner of the present invention, the toner particles 14 The C concentration is 21.5 pMC or more. Therefore, the degree of biomass conversion is approximately 20.0 mass% or more. Such toner with a biomass content of 20.0% by mass or more is an environmentally friendly product because it uses a relatively large amount of biomass as a raw material.

[0037] The above 14 As a means for making the C concentration 21.5 pMC or more, for example, it is preferable to make the biomass content of the acrylic resin, which is the binder resin of the toner base particles, 25 to 40 mass %, and to make the ratio of the acrylic resin in the toner base particles 50 to 80 mass %. In the present invention, it is preferable that various monomers used as the biomass-derived raw material in the acrylic resin, which is the binder resin described below, have carbon atoms derived from biomass. In particular, it is preferable that isobornyl acrylate, methacrylic acid, n-butyl acrylate, etc., described below, have carbon atoms derived from biomass.

[0038] [Composition of toner for developing electrostatic images] Hereinafter, the toner for developing electrostatic images of the present invention will also be simply referred to as "toner". The toner of the present invention includes toner particles having toner base particles and an external additive disposed on the surface of the toner base particles. In this specification, "toner base particles" are those that constitute the base of "toner particles." The "toner base particles" according to the present invention contain at least a binder resin. If necessary, the toner base particles may contain other components such as a colorant, a release agent (wax), and a charge control agent. The "toner base particles" are called "toner particles" when an external additive is added. And, "toner" refers to an aggregate of toner particles.

[0039] <Toner base particles> The toner base particles according to the present invention contain a binder resin and a colorant. The toner base particles contain, as the binder resin, a polymer having at least a structural unit represented by the following general formula (1).

[0040] [ka]

[0041] In the general formula (1), R 1represents a hydrogen atom or a methyl group, and preferably represents a methyl group. R 2 R represents an alicyclic hydrocarbon group having 6 to 12 carbon atoms. 2 R preferably represents an isobornyl group, a cyclohexyl group, an adamantyl group, or the like. 2 is particularly preferably an isobornyl group in terms of improving the heat-resistant storage stability of the binder resin.

[0042] Examples of the monomer having a structural unit represented by the general formula (1) include isobornyl methacrylate, isobornyl acrylate, cyclohexyl acrylate, cyclohexyl methacrylate, adamantyl acrylate, and adamantyl methacrylate.

[0043] The weight average molecular weight of the polymer having the structural unit represented by the general formula (1) is preferably within the range of 5,000 to 100,000 as measured by gel permeation chromatography, in terms of excellent heat-resistant storage stability and fixability.

[0044] The weight average molecular weight of the polymer can be measured in terms of polystyrene by gel permeation chromatography (GPC). Specifically, a GPC device HLC-8120GPC (manufactured by Tosoh Corporation) and a column TSKguardcolumn+TSKgelSuperHZ-m triple column (manufactured by Tosoh Corporation) are used. Then, tetrahydrofuran is passed as a carrier solvent at a flow rate of 0.2 mL / min while maintaining the column temperature at 40°C. Then, the measurement sample is dissolved in tetrahydrofuran to a concentration of 1 mg / ml under dissolution conditions of treatment for 5 minutes using an ultrasonic disperser at room temperature. Then, the sample is treated with a membrane filter with a pore size of 0.2 μm to obtain a sample solution. 10 μL of this prepared sample solution is injected into the GPC device. The sample is detected using a refractive index detector (RI detector), and the molecular weight distribution of the sample is calculated using a calibration curve measured using monodisperse polystyrene standard particles.

[0045] The binder resin according to the present invention may be a polymer having at least the structural unit represented by the general formula (1), and examples thereof include styrene-acrylic copolymer resins, acrylic resins, etc. Among these, styrene-acrylic copolymer resins, which have excellent heat resistance, are preferred.

[0046] The toner base particles according to the present invention may contain a styrene resin or a polyester in addition to the polymer having the structural unit represented by the general formula (1). Furthermore, the toner base particles according to the present invention may contain a styrene-acrylic copolymer resin or an acrylic resin other than the polymer having the structural unit represented by the general formula (1). The toner base particles may contain a resin other than polyester. The resin is not particularly limited, and any known resin may be used. One type or multiple types of resin may be used.

[0047] As an example of a polymer having a structural unit represented by the general formula (1), a styrene-acrylic copolymer resin will be described below.

[0048] <Styrene-acrylic copolymer resin> The styrene-acrylic copolymer resin is formed by addition polymerization of at least a styrene monomer and a (meth)acrylic acid ester monomer. The styrene monomer is CH 2 =CH-C 6 H 5 In addition to styrene represented by the structural formula above, styrene derivatives having known side chains or functional groups in the styrene structure are also included. In the following, styrene-acrylic copolymer resin will be simply referred to as "styrene-acrylic resin."

[0049] ((Meth)acrylic acid ester monomer) The (meth)acrylic acid ester monomer includes acrylic acid esters and methacrylic acid esters represented by CH(Ra)=CHCOORb (Ra represents a hydrogen atom or a methyl group, and Rb represents an alkyl group having 1 to 24 carbon atoms), as well as acrylic acid ester derivatives and methacrylic acid ester derivatives having known side chains or functional groups in the structure of these esters. Examples of the (meth)acrylic acid ester monomer include, in addition to the monomer containing a structural unit represented by the general formula (1) described above, acrylic acid ester monomers such as methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, t-butyl acrylate, isobutyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, lauryl acrylate, and phenyl acrylate; and methacrylic acid ester monomers such as methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, lauryl methacrylate, phenyl methacrylate, diethylaminoethyl methacrylate, and dimethylaminoethyl methacrylate.

[0050] In this specification, the term "(meth)acrylic acid ester monomer" is a general term for "acrylic acid ester monomer" and "methacrylic acid ester monomer" and means one or both of them. For example, "methyl (meth)acrylate" means one or both of "methyl acrylate" and "methyl methacrylate".

[0051] The (meth)acrylic acid ester monomer may be one or more kinds, as long as it includes a monomer containing a structural unit represented by the general formula (1) described above. For example, it is possible to form a copolymer using a styrene monomer and two or more kinds of acrylic acid ester monomers, to form a copolymer using a styrene monomer and two or more kinds of methacrylic acid ester monomers, or to form a copolymer using a styrene monomer in combination with an acrylic acid ester monomer and a methacrylic acid ester monomer.

[0052] (styrene monomer) Examples of styrene monomers include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-phenylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, p-tert-butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, pn-decylstyrene, and pn-dodecylstyrene.

[0053] (Preferred composition of styrene-acrylic resin) From the viewpoint of controlling the plasticity of the styrene-acrylic resin, the content of structural units derived from styrene monomer in the styrene-acrylic resin is preferably within a range of 40 to 90% by mass, more preferably within a range of 50 to 85% by mass, even more preferably within a range of 60 to 80% by mass, and even more preferably within a range of 65 to 75% by mass. The content of structural units derived from the (meth)acrylic acid ester monomer in the styrene-acrylic resin is preferably within a range of 10 to 60% by mass, more preferably within a range of 15 to 50% by mass, even more preferably within a range of 20 to 40% by mass, and even more preferably within a range of 15 to 35% by mass.

[0054] (Other monomers) The styrene-acrylic resin may further contain structural units derived from other monomers than the styrene monomer and the (meth)acrylic acid ester monomer. The other monomer is preferably a compound that forms an ester bond with a hydroxy group (-OH) derived from a polyhydric alcohol or a carboxy group (-COOH) derived from a polycarboxylic acid. In other words, the styrene-acrylic resin is preferably a polymer that can be addition polymerized with the styrene monomer and the (meth)acrylic acid ester monomer, and is further polymerized with a compound (amphoteric compound) having a carboxy group or a hydroxy group.

[0055] (Amphoteric Compound) Examples of the amphoteric compound include compounds having a carboxy group, such as acrylic acid, methacrylic acid, maleic acid, itaconic acid, cinnamic acid, fumaric acid, maleic acid monoalkyl esters, and itaconic acid monoalkyl esters, and compounds having a hydroxy group, such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and polyethylene glycol mono(meth)acrylate.

[0056] (Preferable content of structural units derived from amphoteric compounds) The content of the constitutional unit derived from the amphoteric compound in the styrene-acrylic resin is preferably within a range of 0.5 to 20% by mass, and more preferably within a range of 5 to 10% by mass. In an embodiment of the present invention, in the styrene-acrylic resin, the total of the content of the structural units derived from the styrene monomer, the content of the structural units derived from the (meth)acrylic acid ester monomer, and the content of the structural units derived from the amphoteric compound is 100 mass%.

[0057] (Method of synthesis of styrene-acrylic resin) The styrene-acrylic resin can be synthesized by polymerizing monomers using a known oil-soluble or water-soluble polymerization initiator. Examples of the oil-soluble polymerization initiator include azo- or diazo-based polymerization initiators and peroxide-based polymerization initiators.

[0058] (Azo or diazo polymerization initiator) Examples of the azo or diazo polymerization initiator include 2,2'-azobis-(2,4-dimethylvaleronitrile), 2,2'-azobisisobutyronitrile, 1,1'-azobis(cyclohexane-1-carbonitrile), 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile and azobisisobutyronitrile.

[0059] (Peroxide-based polymerization initiator) Examples of the peroxide polymerization initiator include benzoyl peroxide, methyl ethyl ketone peroxide, diisopropyl peroxycarbonate, cumene hydroperoxide, t-butyl hydroperoxide, di-t-butyl peroxide, dicumyl peroxide, 2,4-dichlorobenzoyl peroxide, lauroyl peroxide, 2,2-bis-(4,4-t-butylperoxycyclohexyl)propane, and tris-(t-butylperoxy)triazine.

[0060] (Water-soluble radical polymerization initiator) When synthesizing styrene-acrylic resin particles by emulsion polymerization, a water-soluble radical polymerization initiator can be used as the polymerization initiator. Examples of water-soluble radical polymerization initiators include persulfates such as potassium persulfate and ammonium persulfate, azobisaminodipropane acetate, azobiscyanovaleric acid and its salts, and hydrogen peroxide.

[0061] (Preferable weight average molecular weight of styrene-acrylic resin) From the viewpoint of easy control of the plasticity, the styrene-acrylic resin preferably has a weight average molecular weight (Mw) in the range of 5,000 to 100,000. The weight average molecular weight is more preferably in the range of 10,000 to 70,000, and even more preferably in the range of 15,000 to 60,000. The weight average molecular weight is even more preferably in the range of 20,000 to 40,000, and even more preferably in the range of 25,000 to 35,000. The weight average molecular weight of the styrene-acrylic resin can be measured in terms of polystyrene by gel permeation chromatography (GPC) in the same manner as the weight average molecular weight of the polymer mentioned above.

[0062] The toner base particles according to the present invention preferably contain styrene-acrylic resin in the range of 65 to 90% by mass.

[0063] <Polyester> The polyester used for the binder resin may be either a crystalline polyester or an amorphous polyester, but is preferably an amorphous polyester from the viewpoint of electrostatic chargeability.

[0064] In the present invention, the term "crystalline resin" refers to a resin having a melting point, i.e., a clear endothermic peak during heating, in an endothermic curve obtained by differential scanning calorimetry (DSC). The term "clear endothermic peak" refers to a peak having a half-width of 15°C or less in an endothermic curve obtained when the temperature is increased at a heating rate of 10°C / min. On the other hand, the term "amorphous resin" refers to a resin in which a baseline curve indicating the occurrence of glass transition is observed in an endothermic curve obtained by performing the same differential scanning calorimetry as above, but no clear endothermic peak is observed.

[0065] (Crystalline polyester) The crystalline polyester is a resin exhibiting crystallinity among known polyesters obtained by polycondensation reaction of a divalent or higher carboxylic acid (polycarboxylic acid) or its derivative with a divalent or higher alcohol (polyalcohol) or its derivative.

[0066] The polycarboxylic acid component for forming the crystalline polyester is a compound containing two or more carboxy groups in one molecule.Specific examples include saturated aliphatic dicarboxylic acids such as succinic acid, sebacic acid, and dodecanedioic acid; alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid; aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, and terephthalic acid; trivalent or higher polycarboxylic acids such as trimellitic acid and pyromellitic acid; and anhydrides or alkyl esters having 1 to 3 carbon atoms of these carboxylic acid compounds.As the polycarboxylic acid component for forming the crystalline polyester, it is preferable to use saturated aliphatic dicarboxylic acids.These may be used alone or in combination of two or more.

[0067] The polyhydric alcohol component for forming the crystalline polyester is a compound containing two or more hydroxyl groups in one molecule. Specifically, for example, aliphatic diols such as ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, neopentyl glycol, and 1,4-butenediol; trihydric or higher polyhydric alcohols such as glycerin, pentaerythritol, trimethylolpropane, and sorbitol; and the like. As the polyhydric alcohol component for forming the crystalline polyester, it is preferable to use an aliphatic diol. These may be used alone or in combination of two or more.

[0068] The method for producing the crystalline polyester is not particularly limited, and the crystalline polyester can be produced by a general polyester polymerization method in which the above-mentioned polyvalent carboxylic acid and polyhydric alcohol are reacted in the presence of a catalyst. As the production method, for example, it is preferable to use a direct polycondensation method or an ester exchange method depending on the type of monomer.

[0069] Also, a linear aliphatic hydroxycarboxylic acid can be used in combination with the polyvalent carboxylic acid and / or polyhydric alcohol. Examples of linear aliphatic hydroxycarboxylic acids for forming crystalline polyesters include 5-hydroxypentanoic acid, 6-hydroxyhexanoic acid, 7-hydroxypentanoic acid, 8-hydroxyoctanoic acid, 9-hydroxynonanoic acid, 10-hydroxydecanoic acid, 12-hydroxydodecanoic acid, 14-hydroxytetradecanoic acid, 16-hydroxyhexadecanoic acid, 18-hydroxyoctadecanoic acid, and lactone compounds cyclized from these hydroxycarboxylic acids, or alkyl esters with alcohols having 1 to 3 carbon atoms. These may be used alone or in combination of two or more.

[0070] Furthermore, when forming the crystalline polyester, it is preferable to use a polyvalent carboxylic acid and a polyhydric alcohol component, since this makes it easy to control the reaction and allows a resin having a desired molecular weight to be obtained.

[0071] Examples of catalysts that can be used in the production of crystalline polyesters include titanium catalysts such as titanium tetraethoxide, titanium tetrapropoxide, titanium tetraisopropoxide, titanium tetrabutoxide, etc. Furthermore, examples of the catalyst include tin catalysts such as dibutyltin dichloride, dibutyltin oxide, diphenyltin oxide, etc.

[0072] The ratio of the polyvalent carboxylic acid component to the polyhydric alcohol component is preferably 1.5 / 1 to 1 / 1.5 in terms of the equivalent ratio [OH] / [COOH] between the hydroxyl group [OH] of the polyhydric alcohol component and the carboxyl group [COOH] of the polyvalent carboxylic acid component. Furthermore, the equivalent ratio [OH] / [COOH] is preferably within the range of 1.2 / 1 to 1 / 1.2.

[0073] The acid value of the crystalline polyester is preferably within the range of 5 to 30 mgKOH / g, more preferably 10 to 25 mgKOH / g, and even more preferably 15 to 25 mgKOH / g. This acid value is the mass of potassium hydroxide (KOH) required to neutralize the acid contained in 1 g of a sample, expressed in mg units. The acid value of the resin is measured according to the following procedure in accordance with JIS K0070-1992.

[0074] (Preparation of reagents) Dissolve 1.0 g of phenolphthalein in 90 mL of ethyl alcohol (95% by volume), add ion-exchanged water to make 100 mL, and prepare a phenolphthalein solution. Dissolve 7 g of JIS special grade potassium hydroxide in 5 mL of ion-exchanged water, and add ethyl alcohol (95% by volume) to make 1 liter. Place in an alkali-resistant container to avoid contact with carbon dioxide, leave for 3 days, then filter to prepare a potassium hydroxide solution. Standardization follows the description of JIS K0070-1992.

[0075] (Actual test) Weigh out 2.0 g of the crushed sample into a 200 mL Erlenmeyer flask, add 100 mL of a toluene / ethanol (toluene:ethanol volume ratio 2:1) mixture, and dissolve for 5 hours. Next, add a few drops of the prepared phenolphthalein solution as an indicator, and titrate with the prepared potassium hydroxide solution. The end point of the titration is when the indicator remains a pale red color for about 30 seconds.

[0076] (Blank test) The same procedure as in the main test described above is carried out, except that no sample is used (i.e., only a mixed solution of toluene / ethanol (toluene:ethanol in a volume ratio of 2:1) is used).

[0077] The titration results of the main test and the blank test are substituted into the following formula (a) to calculate the acid value.

[0078] Equation (a) A = [(CB) × f × 5.6] / S A: Acid value (mgKOH / g) B: Amount of potassium hydroxide solution added during blank test (mL) C: Amount of potassium hydroxide solution added during this test (mL) f: Factor of 0.1 mol / L potassium hydroxide ethanol solution S: mass of sample (g)

[0079] The weight average molecular weight (Mw) of the crystalline polyester is preferably 3000 to 100000 from the viewpoint of reliably achieving both sufficient low-temperature fixability and excellent long-term heat-resistant storage stability. The weight average molecular weight is more preferably 4000 to 50000, and particularly preferably 5000 to 20000. The ratio of the diol component and the dicarboxylic acid component used is preferably 1.5 / 1 to 1 / 1.5, more preferably 1.2 / 1 to 1 / 1.2, in terms of the ratio [OH] / [COOH] of the hydroxy group equivalent of the diol component to the carboxy group equivalent of the dicarboxylic acid component. The weight average molecular weight of the crystalline polyester can be measured in terms of polystyrene by gel permeation chromatography (GPC) in the same manner as the weight average molecular weight of the above-mentioned polymer.

[0080] The toner base particles according to the present invention preferably contain crystalline polyester in the range of 5 to 20% by mass in terms of improving fixability and heat-resistant storage stability. When the content of the crystalline polyester is 5% by mass or more, fixability is good. When the content of the crystalline polyester is 20% by mass or less, the crystalline polyester is not exposed on the toner surface, and heat-resistant storage stability is improved.

[0081] (amorphous polyester) Amorphous polyesters are obtained by a polycondensation reaction between a divalent or higher carboxylic acid (polycarboxylic acid) and a divalent or higher alcohol (polyalcohol). There are no particular limitations on the specific amorphous polyester, and any amorphous polyester conventionally known in the art can be used.

[0082] The specific method for producing the amorphous polyester is not particularly limited, and the resin can be produced by polycondensing (esterifying) a polyvalent carboxylic acid and a polyhydric alcohol using a known esterification catalyst.

[0083] The weight average molecular weight (Mw) of the amorphous polyester is not particularly limited, but is, for example, preferably in the range of 5,000 to 100,000, and more preferably in the range of 5,000 to 50,000. When the weight average molecular weight (Mw) is 5,000 or more, the heat-resistant storage stability of the toner can be improved, and when it is 100,000 or less, the low-temperature fixability can be further improved.

[0084] Examples of the polyvalent carboxylic acid and polyhydric alcohol used in the preparation of the amorphous polyester are not particularly limited, but include the following.

[0085] <Polycarboxylic acids> Examples of the carboxylic acids include aromatic carboxylic acids such as terephthalic acid, isophthalic acid, phthalic anhydride, trimellitic anhydride, pyromellitic acid, and naphthalenedicarboxylic acid; aliphatic carboxylic acids such as maleic anhydride, fumaric acid, succinic acid, alkenyl succinic anhydride, and adipic acid; and alicyclic carboxylic acids such as cyclohexanedicarboxylic acid. These polyvalent carboxylic acids may be used alone or in combination of two or more.

[0086] Among these polyvalent carboxylic acids, it is preferable to use aromatic carboxylic acids. In order to obtain a crosslinked or branched structure and to ensure better fixability, it is preferable to use a trivalent or higher carboxylic acid (such as trimellitic acid or its acid anhydride) in combination with a dicarboxylic acid. Examples of trivalent or higher carboxylic acids include 1,2,3-benzenetricarboxylic acid, 1,2,4-benzenetricarboxylic acid, 1,3,5-benzenetricarboxylic acid, 11,2,4-naphthalenetricarboxylic acid, and the like, as well as their anhydrides and lower alkyl esters. These may be used alone or in combination of two or more. Good too.

[0087] <Polyhydric alcohol> Examples of the polyhydric alcohol include aliphatic diols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, butanediol, hexanediol, neopentyl glycol, and glycerin. Examples of the polyhydric alcohol include alicyclic diols such as cyclohexanediol, cyclohexanedimethanol, and hydrogenated bisphenol A. Examples of the polyhydric alcohol include aromatic diols such as an ethylene oxide adduct of bisphenol A and a propylene oxide adduct of bisphenol A. These polyhydric alcohols may be used alone or in combination of two or more.

[0088] Among these polyhydric alcohols, aromatic diols and alicyclic diols are preferred, and aromatic diols are more preferred. In order to ensure better fixation, trihydric or higher polyhydric alcohols (glycerin, trimethylolpropane, pentaerythritol) may be used in combination with the diol to form a crosslinked or branched structure.

[0089] In addition, a monocarboxylic acid and / or a monoalcohol may be further added to the polyester obtained by polycondensation of a polyvalent carboxylic acid and a polyhydric alcohol to esterify the hydroxyl group and / or the carboxyl group at the polymerization terminal, thereby adjusting the acid value of the polyester.

[0090] Examples of the monocarboxylic acid include acetic acid, acetic anhydride, benzoic acid, trichloroacetic acid, trifluoroacetic acid, propionic anhydride, etc. Examples of the monoalcohol include methanol, ethanol, propanol, octanol, 2-ethylhexanol, trifluoroethanol, trichloroethanol, hexafluoroisopropanol, phenol, etc.

[0091] The amorphous polyester used in the present invention may be a hybrid amorphous polyester in which a vinyl-based polymer segment composed of a styrene-acrylic polymer or the like and a polyester-based polymer segment composed of an amorphous polyester are bonded via a bireactive monomer.

[0092] The content ratio of the vinyl-based polymerization segment is preferably within a range of 5 to 30% by mass, and more preferably within a range of 10 to 20% by mass, based on the total mass of the hybrid amorphous polyester.

[0093] When the hybrid amorphous polyester contains a vinyl-based polymerization segment in the range of 5 to 30% by mass, the balance between charge retention and charge leakage can be controlled.

[0094] <Release agent> The toner base particles according to the present invention contain a releasing agent. The releasing agent is a component that seeps out from the toner particles during fixing and enhances the fixing and releasing properties of the toner. As the release agent, various known waxes can be used. Examples of the wax include polyolefin waxes such as polyethylene wax and polypropylene wax, branched chain hydrocarbon waxes such as microcrystalline wax, long chain hydrocarbon waxes such as paraffin wax and sazol wax, dialkyl ketone waxes such as distearyl ketone, carnauba wax, montan wax, behenic acid behenate, trimethylolpropane tribehenate, pentaerythritol tetrabehenate, pentaerythritol diacetate dibehenate, glycerin tribehenate, 1,18-octadecanediol distearate, trimellitic acid tristearyl, distearyl maleate, and other ester waxes, and amide waxes such as ethylenediamine behenylamide and trimellitic acid tristearylamide. These release agents may be used alone or in combination of two or more.

[0095] The content of the release agent is preferably in the range of 0.1 to 20% by mass, more preferably in the range of 1 to 10% by mass, based on the toner base particles. If the content of the release agent is within the above range, the release agent is not too much and can be prevented from being exposed on the toner surface. As a result, aggregation of the toner base particles due to the exposed release agent can be prevented, and deterioration of heat-resistant storage stability can also be prevented. The melting point of the release agent is preferably within a range of 50 to 95° C. from the viewpoint of low-temperature fixability and releasability of the toner.

[0096] <Coloring agent> The toner base particles according to the present invention may contain a colorant. As the colorant, a known inorganic or organic colorant can be used. As the colorant, carbon black, magnetic powder, various organic or inorganic pigments, dyes, etc. can be used. In particular, it is preferable to use a chromatic pigment. As the inorganic pigment, it is preferable to use a phthalocyanine pigment. The amount of the colorant added is preferably within the range of 1 to 10% by mass relative to the toner base particles. When the amount added is 10% by mass or less, the colorant is not exposed on the toner surface, and aggregation of toner particles due to the exposed colorant is unlikely to occur. 14 The effects of C are also more likely to be realized.

[0097] <Charge control agent> The toner base particles according to the present invention may contain a charge control agent. The charge control agent may be a known compound such as a nigrosine dye, a metal salt of naphthenic acid or a higher fatty acid, an alkoxylated amine, a quaternary ammonium salt, an azo metal complex, or a metal salt of salicylic acid. The charge control agent makes it possible to obtain a toner with excellent charging properties. The content of the charge control agent is preferably within a range of usually 0.1 to 5.0% by mass based on the toner base particles.

[0098] <External additives> The toner base particles according to the present invention may have their surfaces treated with an external additive, which can improve the fluidity, chargeability, cleaning properties, etc. Examples of the external additive include inorganic oxide fine particles such as silica fine particles, alumina fine particles, and titanium oxide fine particles. Examples of the external additive include inorganic stearic acid compound fine particles such as aluminum stearate fine particles and zinc stearate fine particles, and inorganic titanic acid compound fine particles such as strontium titanate and zinc titanate. These may be used alone or in combination of two or more.

[0099] From the viewpoint of improving heat-resistant storage stability and environmental stability, it is preferable that these inorganic particles are subjected to a gloss treatment, which is preferably carried out using a silane coupling agent, a titanium coupling agent, a higher fatty acid, a silicone oil, or the like. The amount of the external additive added is preferably within a range of 0.05 to 5 parts by mass, and more preferably within a range of 0.1 to 3 parts by mass, based on 100 parts by mass of the toner base particles. When a plurality of external additives are used, the total amount of the additives is preferably within the above range.

[0100] <Toner particle size> The average particle size of the toner particles according to the present invention is preferably, for example, 3 to 10 μm, more preferably 5 to 8 μm, in terms of the volume-based median diameter. This average particle size can be controlled by the concentration of the coagulant used during production, the amount of organic solvent added, the fusion time, the composition of the binder resin, etc. By having the volume-based median diameter fall within the above range, extremely fine dot images at a 1200 dpi level can be faithfully reproduced.

[0101] The volume-based median diameter of the toner particles is measured and calculated using a measuring device consisting of a "Multisizer 3" (manufactured by Beckman Coulter) connected to a computer system equipped with the data processing software "Software V3.51." Specifically, first, 0.02 g of the measurement sample (toner) is added to 20 mL of surfactant solution (a surfactant solution prepared by diluting, for example, a neutral detergent containing a surfactant component 10 times with pure water in order to disperse the toner particles) and allowed to mix. Then, ultrasonic dispersion is performed for 1 minute to prepare a toner dispersion. This toner dispersion is poured with a pipette into a beaker containing an "ISOTON II" (manufactured by Beckman Coulter) in the sample stand until the concentration indicated on the measuring device reaches 8%. By keeping the concentration within the above range, reproducible measurement values ​​can be obtained. In the measurement device, the number of measured particles is set to 25,000, the aperture diameter is set to 100 μm, and the measurement range of 2 to 60 μm is divided into 256 parts to calculate the frequency value. The particle diameter of the largest 50% of the volume cumulative fraction is determined to be the volume-based median diameter.

[0102] <Average circularity of toner particles> The average circularity of the toner particles according to the present invention is preferably within a range of 0.930 to 1.000, and more preferably within a range of 0.950 to 0.995, from the viewpoints of the stability of the charging characteristics and the low-temperature fixing ability. When the average circularity is within the above range, individual toner particles are less likely to be crushed, contamination of the frictional charging member is suppressed, and the chargeability of the toner is stabilized. Also, the image formed has high image quality.

[0103] The average circularity of the toner particles is a value measured using "FPIA-3000" (manufactured by Sysmex Corporation). Specifically, the measurement sample (toner) is mixed with an aqueous solution containing a surfactant, and dispersed by ultrasonic dispersion treatment for 1 minute. After that, images are taken using an "FPIA-3000" (manufactured by Sysmex) under the measurement conditions of HPF (high magnification imaging) mode at an appropriate concentration of 3,000 to 10,000 HPF detections. The circularity of each toner particle is calculated according to the following formula (y), and the circularity of each toner particle is added and divided by the total number of toner particles. If the HPF detection number is within the above range, reproducibility is obtained. Formula (y): Circularity = (perimeter of a circle with the same projected area as the particle image) / (perimeter of the projected image of the particle)

[0104] [Toner manufacturing method] The toner for developing electrostatic images according to the present invention can be produced by known methods such as kneading and pulverization, suspension polymerization, emulsion aggregation, dissolution suspension, polyester elongation, and dispersion polymerization. Among these, it is preferable to use the emulsion aggregation method. The emulsion aggregation method can produce toner base particles with a sharp particle size distribution and highly controlled particle size and toner circularity.

[0105] The emulsion aggregation method is the following method. First, a dispersion of fine particles of binder resin (hereinafter also referred to as "binder resin fine particles") dispersed with a surfactant or a dispersion stabilizer is prepared. Next, this dispersion of binder resin fine particles is mixed with a dispersion of various fine particles to be contained in the toner base particles, for example, a dispersion of fine particles of a colorant and a dispersion of fine particles of various optional components. Next, an aggregating agent is added to aggregate the particles to the desired particle size of the toner base particles, and thereafter or simultaneously with the aggregation, the binder resin fine particles are fused together to control the shape. In this manner, the toner base particles are formed.

[0106] In the toner production method according to the present invention, an example of a production method for producing toner base particles containing a colorant by an emulsion aggregation method is shown below. The method for producing toner base particles by an emulsion aggregation method includes the following steps (1) to (5), and an external additive is added to the toner base particles by step (6).

[0107] (1) A step of preparing a dispersion liquid in which fine colorant particles are dispersed in an aqueous medium (2) A step of preparing a dispersion in which binder resin particles, optionally containing an internal additive, are dispersed in an aqueous medium. (3) A step of mixing a dispersion of colorant particles with a dispersion of binder resin particles, and aggregating, associating, and fusing the colorant particles and binder resin particles to form toner base particles. (4) A process of filtering the toner base particles from the dispersion system (aqueous medium) and removing surfactants, etc. (5) Drying the toner base particles (6) A process of adding external additives to the toner base particles

[0108] The dispersion liquid prepared in the above-mentioned production methods (1) and (2) may contain a surfactant and a dispersion stabilizer, if necessary. The preparation of the dispersion liquid can be carried out by utilizing mechanical energy. Examples of dispersing machines for carrying out dispersion include low-speed shear dispersing machines, high-speed shear dispersing machines, friction dispersing machines, high-pressure jet dispersing machines, ultrasonic dispersing machines such as ultrasonic homogenizers, and high-pressure impact dispersing machines such as ultimaizers.

[0109] In the present invention, a dispersion containing a compound having a structural unit represented by the general formula (1) is used as the dispersion of the binder resin particles. In the present invention, it is preferable to use a dispersion of a crystalline polyester in addition to the dispersion of a compound having a structural unit represented by the general formula (1).

[0110] The particle size of the binder resin particles used in the toner base particles, whether the resin particles are amorphous or crystalline, is preferably within a range of about 50 to 300 nm in terms of volume-based median size. The volume-based median diameter of the binder resin particles can be measured by an electrophoretic light scattering photometer, for example, "ELS-800 (manufactured by Otsuka Electronics Co., Ltd.)."

[0111] In the step (3) of the above manufacturing method, the particles are slowly aggregated while balancing the repulsive force of the particle surface by adjusting the pH and the aggregation force by adding an aggregating agent made of an electrolyte. Then, the particles are associated while controlling the average particle size and particle size distribution, and at the same time, the particles are fused together by heating and stirring to control the shape, thereby forming toner base particles.

[0112] The flocculant used in the present invention is not particularly limited, but is preferably selected from metal salts. Examples of the flocculant include monovalent metal salts such as salts of alkali metals such as sodium, potassium, and lithium, divalent metal salts such as calcium, magnesium, manganese, and copper, and trivalent metal salts such as iron and aluminum. Specific examples of salts include sodium chloride, potassium chloride, lithium chloride, calcium chloride, magnesium chloride, zinc chloride, copper sulfate, magnesium sulfate, and manganese sulfate. Among these, divalent metal salts are particularly preferred. When a divalent metal salt is used, aggregation can be promoted with a smaller amount. These salts may be used alone or in combination of two or more kinds.

[0113] In the step (4), the toner base particles are separated from the dispersion liquid of the toner base particles using a solvent such as water, and the cake-like aggregate containing the separated toner base particles is washed to remove any attached substances such as surfactants. Specific methods of solid-liquid separation and washing include, but are not limited to, centrifugation, reduced pressure filtration using an aspirator, a Nutsche, or the like, and filtration using a filter press, or the like. At this time, pH adjustment, pulverization, or the like may be appropriately performed. Such operations may be repeated.

[0114] (5) Dryers used in the drying step include ovens, spray dryers, vacuum freeze dryers, reduced pressure dryers, stationary shelf dryers, mobile shelf dryers, fluidized bed dryers, rotary dryers, and agitator dryers. The moisture content in the dried toner base particles, as measured by Karl Fischer coulometric titration, is preferably 5% by mass or less, and more preferably 2% by mass or less.

[0115] The toner base particle according to the present invention may be a multi-layered toner base particle having a core-shell structure in which the toner base particle serves as a core particle and a shell layer covers the surface of the core particle. The shell layer does not have to cover the entire surface of the core base particle, and the core particle may be partially exposed. The cross section of the core-shell structure can be observed by known observation means such as a transmission electron microscope (TEM) or a scanning probe microscope (SPM).

[0116] In the case of a core-shell structure, the core particle and the shell layer can have different properties such as glass transition point, melting point, and hardness, making it possible to design toner base particles according to the purpose. For example, a shell layer can be formed by aggregating and fusing a resin with a relatively high glass transition point (Tg) to the surface of a core particle that contains a binder resin and metal particles and has a relatively low glass transition point (Tg). The shell layer preferably contains an amorphous resin.

[0117] The toner base particles having a core-shell structure can be obtained, for example, by the above-mentioned emulsion aggregation method. Specifically, toner base particles having a core-shell structure are first prepared by aggregating, associating, and fusing binder resin particles for core particles and metal fine particles to prepare core particles. Next, binder resin particles for the shell layer are added to a dispersion of the core particles, and the binder resin particles for the shell layer are aggregated and fused to the surface of the core particles to form a shell layer that covers the surface of the core particles. It is preferable that the internal additives used arbitrarily are contained in the core particles.

[0118] The core particles may be prepared to have a multi-layer structure of two or more layers made of binder resins with different compositions. For example, when preparing binder resin particles having a three-layer structure, they can be prepared by carrying out a polymerization reaction to synthesize the binder resin in three stages: the first polymerization stage (formation of the inner layer), the second polymerization stage (formation of the middle layer), and the third polymerization stage (formation of the outer layer). In addition, by changing the composition of the polymerizable monomer in each of the polymerization reactions of the first to third polymerization stages, binder resin particles having a three-layer structure with different compositions can be prepared. In addition, for example, by carrying out a synthesis reaction of the binder resin in a state in which an appropriate internal additive such as a release agent is contained in any of the first to third polymerization stages, binder resin particles having a three-layer structure containing the appropriate internal additive can be formed.

[0119] The toner according to the present invention is obtained by adhering an external additive to the surface of the toner base particles obtained in the steps (1) to (5) in the step (6). Specifically, the following method is used for the step (6).

[0120] The external additives can be added to and mixed with the toner base particles using a mechanical mixer. Examples of the mechanical mixer that can be used include a Henschel mixer, a Nauta mixer, a Turbula mixer, etc. Among these, it is preferable to use a mixer that can impart shear force to the particles to be treated, such as a Henschel mixer, and to perform the mixing process by lengthening the mixing time or increasing the rotational peripheral speed of the stirring blades. When a plurality of types of external additives are used, all of the external additives may be mixed with the toner base particles at once, or the external additives may be mixed in separate batches depending on the type of external additive.

[0121] In addition, the method of mixing the external additives can be, for example, using the above-mentioned mechanical mixer, and the degree of disintegration and adhesion strength of the external additives can be controlled by controlling the mixing intensity, i.e., the peripheral speed of the stirring blade, the mixing time, or the mixing temperature.

[0122] Although the embodiment of the present invention has been specifically described above, the embodiment of the present invention is not limited to the above example, and various modifications can be made.

[0123] [Developer] The toner for developing electrostatic images of the present invention can be used as a magnetic or non-magnetic one-component developer, but may also be mixed with a carrier to be used as a two-component developer. When the toner is used as a two-component developer, the carrier may be magnetic particles made of a conventionally known material such as a metal such as iron, ferrite, magnetite, or an alloy of such a metal with a metal such as aluminum or lead. Ferrite particles are particularly preferred as the carrier.

[0124] As the carrier, a coated carrier in which the surface of magnetic particles is coated with a coating agent such as resin, or a dispersion type carrier in which fine magnetic powder is dispersed in a binder resin may be used. The volume-based median diameter (d50) of the carrier is preferably within the range of 20 to 100 μm, and more preferably within the range of 25 to 80 μm. The volume-based median diameter (d50) of the carrier can be measured, for example, by a laser diffraction particle size distribution measuring device HELOS (manufactured by SYMPATEC) equipped with a wet disperser.

[0125] [Image forming method] The image forming method of the present invention is characterized by using the above-mentioned toner for developing electrostatic images of the present invention. In the image forming method of the present invention, for example, an electrostatic image formed on a photoreceptor is developed to obtain a toner image, and the toner image is transferred to an image support. Thereafter, the toner image transferred to the image support is fixed to the image support by a fixing process using a heat and pressure fixing method, thereby obtaining a printed matter on which a visible image is formed.

[0126] The toner of the present invention can be used in a monochrome image forming method or a full-color image forming method. In the full-color image forming method, any image forming method can be applied, such as a four-cycle image forming method consisting of four types of color developing devices for yellow, magenta, cyan, and black, and one photosensitive member, or a tandem image forming method in which image forming units having color developing devices and photosensitive members for each color are installed for each color. EXAMPLES

[0127] The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto. In the following examples, unless otherwise specified, the operations were performed at room temperature (25°C). Furthermore, unless otherwise specified, "%" and "parts" mean "% by mass" and "parts by mass", respectively. In the following, for biomass-derived raw materials (biomass-derived monomers), the amounts charged are underlined in Table I. Monomers other than those derived from biomass may be commercially available products or petroleum-derived monomers.

[0128] <Preparation of acrylic binder resin particle dispersion (1)> A 5 L reaction vessel equipped with a stirrer, a temperature sensor, a cooling tube, and a nitrogen inlet was prepared. Sodium dodecyl sulfate (C 10 H 21 (OCH 2 CH 2 ) 2 SO 3 An aqueous surfactant solution was prepared by dissolving 0.6 parts by mass of an anionic surfactant consisting of potassium persulfate (Na) in 2,370 parts by mass of ion-exchanged water, and then a polymerization initiator solution was added by dissolving 7 parts by mass of potassium persulfate in 140 parts by mass of ion-exchanged water, and the liquid temperature was raised to 75°C. The isobornyl methacrylate (IBXMA), n-butyl acrylate, and methacrylic acid shown below were each derived from biomass-derived raw materials. Styrene (St) 225 parts by mass Isobornyl methacrylate (IBXMA) 41 parts by weight n-Butyl acrylate (nBA) 122 parts by weight Methacrylic acid (MAA) 43 parts by weight n-Octyl mercaptan (NOM) 4.5 parts by mass The polymerizable monomer mixture solution was added dropwise over 1 hour. After the addition, the mixture was heated and stirred at 85° C. for 2 hours to carry out polymerization, thereby preparing an acrylic binder resin particle dispersion (1).

[0129] <Preparation of acrylic binder resin particle dispersions (2) to (7)> Acrylic binder resin particle dispersions (2) to (7) were prepared by changing the amount of the acrylic binder resin particle dispersion (1) as shown in the following Table I. The monomer ratio of each acrylic binder resin particle dispersion is shown in the following Table II. The terms in Tables I and II below are as follows: IBXMA: Isobornyl methacrylate CHA: Cyclohexyl acrylate CHMA: Cyclohexyl methacrylate IBXA: Isobornyl acrylate nOA: normal octyl acrylate nOMA: normal octyl methacrylate Moreover, "acrylic resins (1) to (7)" in Tables I and II represent "acrylic binder resin particle dispersions (1) to (7)," respectively.

[0130] [Table 1]

[0131] [Table 2]

[0132] <Preparation of Crystalline Polyester Resin Particle Dispersion (1)> (Synthesis of crystalline polyester (1)) 281 parts by mass of dodecanedioic acid and 283 parts by mass of 1,6-hexanediol were placed in a reaction vessel equipped with a stirrer, a thermometer, a cooling tube, and a nitrogen gas inlet tube. After replacing the atmosphere in the reaction vessel with dry nitrogen gas, Ti(OBu) 4 0.1 parts by mass of was added, and the reaction was carried out under stirring at about 180°C for 8 hours under a nitrogen gas flow. 4 Then, 0.2 parts by mass of was added, the temperature was raised to about 220°C, and the reaction was carried out with stirring for 6 hours, after which the pressure inside the reaction vessel was reduced to 1333.2 Pa, and the reaction was carried out under reduced pressure to obtain crystalline polyester 1. The crystalline polyester 1 had a number average molecular weight (Mn) of 5500, a weight average molecular weight (Mw) of 18000, and a melting point (Tc) of 67°C.

[0133] (Preparation of Polyester Dispersion (1)) 30 parts by mass of the above crystalline polyester 1 was melted and transferred in the molten state to an emulsifying and dispersing machine "Cavitron CD1010" (manufactured by Eurotech Co., Ltd.) at a transfer rate of 100 parts by mass per minute. On the other hand, 70 parts by mass of reagent ammonia water was diluted with ion-exchanged water to prepare dilute ammonia water with a concentration of 0.37% by mass. Simultaneously with the transfer of the molten crystalline polyester 1, the dilute ammonia water in the aqueous solvent tank was transferred to the emulsifying and dispersing machine "Cavitron CD1010" at a transfer rate of 0.1 liters per minute while being heated to 100°C by a heat exchanger. Next, the emulsifying and dispersing machine "Cavitron CD1010" was operated at a rotor speed of 60Hz and a pressure of 5kg / cm 2 The operation was performed under the following conditions. Thus, a crystalline polyester resin particle dispersion (1) of crystalline polyester 1 having a solid content of 30 parts by mass was prepared. At this time, the volume-based median diameter of the particles contained in the crystalline polyester resin particle dispersion (1) was 200 nm.

[0134] <Preparation of release agent particle dispersion (W1)> Paraffin wax (HNP0190 made by Nippon Seiro, melting temperature 85℃) 270 parts by mass Anionic surfactant (Neogen RK, manufactured by Daiichi Kogyo Seiyaku) 13.5 parts by weight (60% active ingredient, 3% release agent) Ion-exchanged water: 21.6 parts by weight The above materials were mixed, and the release agent was dissolved in a pressure discharge homogenizer (Gaulin homogenizer manufactured by Gaulin Co., Ltd.) at an internal liquid temperature of 120°C. After that, the mixture was dispersed at a dispersion pressure of 5 MPa for 120 minutes, then at 40 MPa for 360 minutes, and cooled to obtain a dispersion. Ion-exchanged water was added to adjust the solid content to 20%, and this was used as release agent dispersion (W1). The volume average particle size of the particles in the release agent dispersion (W1) was 215 nm.

[0135] <Preparation of Cyan Pigment Dispersion 1> 90 parts by mass of sodium lauryl sulfate was dissolved in 1600 parts by mass of ion-exchanged water by stirring. While stirring this solution, 420 parts by mass of copper phthalocyanine (CI Pigment Blue 15:3) was gradually added. Next, a dispersion of colorant particles was prepared by dispersing using a stirring device Clearmix (manufactured by M Technique Co., Ltd.). The volume-based median diameter of the colorant particles in the cyan pigment dispersion 1 was measured and found to be 150 nm.

[0136] <Production of Toner 1> A reaction vessel equipped with a stirrer, a temperature sensor and a cooling tube was prepared. The following materials were added to the reaction vessel: Acrylic binder resin particle dispersion (1) 250 parts by weight (solid content) Release agent particle dispersion (W1) 30 parts by weight Dodecyl diphenyl ether disulfonic acid sodium salt is 1% by mass (solid content equivalent) in resin ratio. Ion-exchanged water 2000 parts by weight At room temperature (25°C), a 5 mol / L aqueous sodium hydroxide solution was added to adjust the pH to 10. Furthermore, 30 parts by mass (solid content equivalent) of Cyan Pigment Dispersion 1 and 30 parts by mass of Crystalline Polyester Resin Particle Dispersion (1) were added. Next, a solution in which 60 parts by mass of magnesium chloride was dissolved in 60 parts by mass of ion-exchanged water was added at 30°C over a period of 10 minutes with stirring. After leaving it for 3 minutes, the temperature was raised to 80°C over 60 minutes, and after the liquid temperature reached 80°C, the stirring speed was adjusted so that the particle size growth rate was 0.01 μm / min. Then, the particles were grown until the volume-based median diameter measured with a Coulter Multisizer 3 (manufactured by Coulter Beckman) was 6.8 μm. An aqueous solution in which 190 parts by mass of sodium chloride was dissolved in 760 parts by mass of ion-exchanged water was added to stop the growth of particle size. Furthermore, the particles were heated and stirred at 80° C. to promote fusion of the particles. When the average circularity of the toner reached 0.970 using an average circularity measuring device "FPIA-3000" (manufactured by Sysmex Corporation), the toner was cooled to 30° C. at a cooling rate of 2.5° C. / min. Next, the toner cake was subjected to solid-liquid separation, and the dehydrated toner cake was washed by repeating the operation of redispersing the toner cake in ion-exchanged water and separating the solid from the liquid three times, and then dried at 40° C. for 24 hours to obtain toner particles.

[0137] The following particles were added to 100 parts by mass of the obtained toner particles, and mixed in a Henschel mixer (manufactured by Mitsui Miike Kakoki Co., Ltd.) at a rotor peripheral speed of 35 m / sec and 32° C. for 20 minutes. Hydrophobic silica particles (number average primary particle size: 12 nm, hydrophobicity: 68) 1.0 parts by mass Alumina particles (number average primary particle diameter = 12 nm) 0.44 parts by mass After mixing, coarse particles were removed using a sieve with 45 μm openings, and the biomass-derived raw material of Example 1 was used ( 14 C) Toner 1 was obtained. The volume-based median diameter of toner 1 was 6.6 μm.

[0138] <Production of Toner 2 to Toner 9> In the production of the toner 1, the type of binder resin, the amount charged, and the like were changed as shown in the following Table III to produce toners 2 to 9.

[0139] [Table 3]

[0140] The degree of biomass conversion for each acrylic resin is shown in Table IV below. As described above, the degree of biomass content in the acrylic resin was calculated based on the total carbon number of the monomer (carbon number of the monomer derived from biomass + carbon number of the monomer not derived from biomass), the number of moles of the monomer, and the carbon number derived from biomass. Furthermore, the degree of biomass conversion in the toner particles was calculated based on the degree of biomass conversion in the acrylic resin. Furthermore, the radioactive carbon isotope concentration was calculated from the degree of biomass conversion in the toner particles, and is shown in Table V below.

[0141] [Table 4]

[0142] [Table 5]

[0143] <Preparation of developer> Each of the toners obtained above was mixed with a carrier coated with silicone resin (a ferrite carrier with a volume-based median diameter of 60 μm) so that the toner content (toner concentration) in the two-component developer was 6 mass %. In this way, developers 1 to 9 were prepared.

[0144] [Evaluation method] The evaluation methods used were the following two items: "fixation test" and "heat resistance storage test." <Fixation test> As an image forming apparatus, a commercially available full-color multifunction printer "AccurioPress C3080 (manufactured by Konica Minolta)" was used, which had been modified so that the surface temperatures of the upper fixing belt and the lower fixing roller could be changed, and the two-component developers of the above colors were loaded in sequence. A4 (Basic weight 90g / m 2 ) On plain paper, toner adhesion amount is 11.3 g / m 2 A test was conducted in which a solid image was output at a fixing temperature of 100 to 200°C, and the fixing temperature was changed in 5°C increments while the test was repeated. The lowest fixing temperature at which image staining due to fixing offset was not visually confirmed was taken as the lowest fixing temperature, and the low-temperature fixing property was evaluated according to the following evaluation criteria. In the following criteria, A to C were rated as acceptable. (standard) A: The minimum fixing temperature is less than 135°C (the toner has excellent low-temperature fixing properties) B: Minimum fixing temperature is 135°C or higher and less than 145°C (the toner has good low-temperature fixing properties) C: Minimum fixing temperature is 145°C or higher and less than 155°C (the toner has good low-temperature fixing properties) D: Minimum fixing temperature 155°C or higher (the toner has poor low-temperature fixing ability and cannot be used)

[0145] <Heat resistance storage test> 0.5 g of toner was placed in a 10 ml glass bottle with an inner diameter of 21 mm, the bottle was capped, and the bottle was shaken 600 times at room temperature using a Tap Denser KYT-2000 (manufactured by Seishin Enterprises). After that, the bottle was left for 2 hours in an environment of 55°C and 35% RH with the cap removed. Next, the toner was placed on a 48 mesh (350 μm mesh) sieve while being careful not to break up the toner aggregates, and then set in a powder tester (manufactured by Hosokawa Micron Corporation) and fixed with a presser bar and knob nut. After that, the vibration intensity was adjusted to a feed width of 1 mm, and vibration was applied for 10 seconds, after which the ratio (mass %) of the toner amount remaining on the sieve was measured. The toner cohesion rate is a value calculated by the following formula. (Toner cohesion rate (%)) = (mass of toner remaining on sieve (g)) / 0.5 (g) x 100 Similar measurements were performed at temperatures of 57.5°C and 60°C, and the X-axis was plotted as temperature and the Y-axis as toner cohesion rate. An approximate straight line was drawn between two temperatures between 55°C, 57.5°C, and 60°C that sandwiched the region where the toner cohesion rate was 50%, and the temperature where the toner cohesion rate was 50% was calculated by interpolation, and evaluation was performed based on the following evaluation criteria. In the following criteria, A to C were considered to be acceptable. (standard) A: 59℃ or higher B: 58℃ or higher but less than 59℃ C: 57℃ or higher and lower than 58℃ D: Less than 57℃

[0146] [Table 6]

[0147] As shown by the above results, it is recognized that the toner of the present invention is superior in fixing property and heat-resistant storage stability compared to the toner of the comparative example, even when a high proportion of biomass-derived raw materials is used.

Claims

1. A toner for developing an electrostatic image, comprising toner base particles containing a binder resin and a colorant, The binder resin contains a polymer having at least a structural unit represented by the following general formula (1): Radioactive carbon isotopes １４ The concentration of C is 21.5 pMC or more.

2. A toner for developing electrostatic images. 【Chemistry 1】 [In general formula (1), R １ represents a hydrogen atom or a methyl group. ２ represents an alicyclic hydrocarbon group having 6 to 12 carbon atoms.

2. The weight average molecular weight of the polymer having the structural unit represented by the general formula (1) is within the range of 5,000 to 100,000 as measured by gel permeation chromatography.

2. The toner for developing electrostatic images according to claim 1.

3. The radioactive carbon isotopes １４ The concentration of C is 32.3 pMC or more.

2. The toner for developing electrostatic images according to claim 1.

4. R in the general formula (1) ２ is an isobornyl group 2. The toner for developing electrostatic images according to claim 1.

5. R in the general formula (1) １ is a methyl group 2. The toner for developing electrostatic images according to claim 1.

6. The toner base particles contain crystalline polyester in the range of 5 to 20% by mass.

2. The toner for developing electrostatic images according to claim 1.

7. An image forming method using a toner for developing an electrostatic image, comprising the steps of: The toner for developing an electrostatic image is the toner for developing an electrostatic image according to any one of claims 1 to 6.

1. An image forming method comprising:

Images