JP7723596B2 - Binder resin composition for toner - Google Patents

Description

The present invention relates to a binder resin composition for toners used in developing latent images formed in, for example, electrophotography, electrostatic recording, or electrostatic printing, a method for producing the same, and a toner for developing electrostatic images containing the binder resin composition.

Patent Document 1 discloses a binder resin composition for toner containing one or more amorphous polyesters and a crystalline polyester, in which at least one amorphous polyester is obtained by reacting an alcohol component, a carboxylic acid component, and polyethylene terephthalate, and the crystalline polyester is contained in an amount 0.3 to 2.5 times by mass of the polyethylene terephthalate-derived component in the amorphous polyester.

Patent Document 2 discloses a binder resin composition for toner that contains one or more composite resins having a polyester resin portion and a vinyl resin portion, and a crystalline polyester, in which the polyester resin portion of at least one composite resin is obtained by polycondensation of an alcohol component containing ethylene glycol and an aromatic diol, and a carboxylic acid component.

Patent Document 3 discloses a binder resin composition for toner containing an amorphous polyester resin, which is a polycondensation product of a carboxylic acid component, an alcohol component, and polyethylene terephthalate, and a crystalline polyester resin, wherein the polyethylene terephthalate has an IV value of 0.40 or more and 0.75 or less, and the mass ratio of the polyethylene terephthalate to the crystalline polyester resin (polyethylene terephthalate/crystalline polyester resin) is 0.1 or more and 15 or less.

JP 2015-14778 A JP 2014-232169 A Japanese Patent Application Laid-Open No. 2018-13519

As described in Patent Documents 1 to 3, polyethylene terephthalate is used as a raw material for polyester resins for toner, and the use of polyethylene terephthalate is also useful from the perspective of recycling. However, when a certain type of carboxylic acid component is used as a raw material monomer, it has been found that when an amorphous polyester resin containing polyethylene terephthalate is used as a binder resin for toner, it is prone to giving off an unpleasant odor during fixing, and further improvements in storage stability are also required.

The present invention relates to a binder resin composition for toner that has reduced odor during fixing and excellent storage stability, a method for producing the same, and a toner for developing electrostatic images that contains the binder resin composition.

The present invention provides
[1] A binder resin composition for toner, comprising a polycondensate of an alcohol component, a carboxylic acid component, and polyethylene terephthalate, wherein the carboxylic acid component contains an aliphatic dicarboxylic acid compound having 4 to 12 carbon atoms, and the content of low-molecular-weight cyclic volatile components having a molecular weight of 50 to 200 among the volatile components in the binder resin composition is 25 mass % or less.
[2] Step 1: polycondensing an alcohol component, a carboxylic acid component containing an aliphatic dicarboxylic acid compound having 4 to 12 carbon atoms, and polyethylene terephthalate;
[0016] The present invention relates to a method for producing a binder resin composition for toner, which comprises: step 2: a step of steam distilling the reaction mixture obtained in step 1; and step 3: a step of reducing the pressure inside the reaction system to remove water after step 2, wherein the content of low-molecular-weight cyclic volatile components having a molecular weight of 50 or more and 200 or less among the volatile components in the binder resin composition is 25 mass % or less; and [3] a toner for developing electrostatic images, which contains the binder resin composition for toner according to [1] above and a colorant.

The toner binder resin composition of the present invention is highly effective in reducing odor during fixing and improving the storage stability of toner.

The binder resin composition for toner of the present invention contains a polycondensate using polyethylene terephthalate (PET) (hereinafter also referred to as amorphous polyester resin A), and has significant features in that the carboxylic acid component contains an aliphatic dicarboxylic acid compound having from 4 to 12 carbon atoms, and the content of low-molecular-weight cyclic volatile components among the volatile components in the binder resin composition is 25 mass % or less. Although the details are unknown, it is presumed that the effects of the present invention are achieved by the following mechanism.
When an aliphatic dicarboxylic acid compound is reacted in the presence of PET, it is likely to produce a low-molecular-weight cyclic compound through intramolecular cyclization of the aliphatic dicarboxylic acid compound having 4 to 12 carbon atoms, which is relatively prone to forming a cyclic structure, possibly due to the influence of catalyst residues contained in the PET during PET production.
The binder resin composition contains, as volatile components (VOCs), volatile components derived from low-molecular-weight cyclic compounds in addition to volatile components derived from polyethylene terephthalate. It is believed that the low-molecular-weight cyclic compounds among these volatile components volatilize during heating (fixing) and generate an unpleasant odor.
Therefore, by reducing the content of this low molecular weight cyclic compound, the odor can be reduced, and further, the decrease in the glass transition temperature of the toner due to the low molecular weight component is suppressed, thereby improving the storage stability.

Amorphous polyester resin A is a polycondensation product of an alcohol component, a carboxylic acid component, and polyethylene terephthalate.

From the viewpoint of low-temperature fixability, the alcohol component is selected from the group consisting of the formula (I):

(wherein OR and RO are oxyalkylene groups, R is an ethylene group and/or a propylene group, x and y are positive numbers each representing the average number of moles of alkylene oxide added, and 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 6 or less, and even more preferably 4 or less.)
Preferred are compounds represented by the formula (I). Examples of alkylene oxide adducts of bisphenol A represented by the formula (I) include polyoxypropylene adducts of 2,2-bis(4-hydroxyphenyl)propane and polyoxyethylene adducts of 2,2-bis(4-hydroxyphenyl)propane. It is preferred to use one or more of these.

The content of the alkylene oxide adduct of bisphenol A represented by formula (I) in the alcohol component is preferably 30 mol% or more, more preferably 50 mol% or more, even more preferably 70 mol% or more, and preferably 95 mol% or less, more preferably 85 mol% or less. The alcohol component also includes ethylene glycol units contained in PET.

Other alcohol components include aliphatic diols such as ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,4-butenediol, 1,3-butanediol, and neopentyl glycol, and trihydric or higher alcohols such as glycerin.

The carboxylic acid component contains an aliphatic dicarboxylic acid compound with 4 to 12 carbon atoms.

Aliphatic dicarboxylic acid compounds having 4 to 12 carbon atoms include succinic acid (4 carbon atoms), fumaric acid (4 carbon atoms), adipic acid (6 carbon atoms), suberic acid (8 carbon atoms), azelaic acid (9 carbon atoms), sebacic acid (10 carbon atoms), dodecanedioic acid (12 carbon atoms), succinic acids having alkyl or alkenyl groups on the side chain, anhydrides of these acids, and alkyl esters of these acids having 1 to 3 carbon atoms.

The number of carbon atoms in the aliphatic dicarboxylic acid compound is 4 or more and 12 or less, preferably 10 or less, and more preferably 8 or less. Note that the number of carbon atoms in the alkyl group of the alkyl ester moiety is not included in the number of carbon atoms in the aliphatic dicarboxylic acid compound.

The content of aliphatic dicarboxylic acid compounds having 4 to 12 carbon atoms in the carboxylic acid component is preferably 3 mol% or more, more preferably 5 mol% or more, and preferably 90 mol% or less, more preferably 50 mol% or less, and even more preferably 25 mol% or less. The carboxylic acid component also includes the terephthalic acid units contained in PET.

Carboxylic acid components other than aliphatic dicarboxylic acid compounds having 4 to 12 carbon atoms include aromatic dicarboxylic acid compounds and trivalent or higher carboxylic acid compounds.

Aromatic dicarboxylic acid compounds include phthalic acid, isophthalic acid, terephthalic acid, anhydrides of these acids, and alkyl esters in which the alkyl group has 1 to 3 carbon atoms. Of these, terephthalic acid or isophthalic acid is preferred from the viewpoint of low-temperature fixability, with terephthalic acid being more preferred.

From the viewpoint of low-temperature fixability, the content of aromatic dicarboxylic acid compounds in the carboxylic acid component is preferably 5 mol% or more, more preferably 10 mol% or more, even more preferably 15 mol% or more, and preferably 80 mol% or less, more preferably 60 mol% or less, even more preferably 50 mol% or less. The carboxylic acid component also includes the terephthalic acid units contained in PET.

Examples of trivalent or higher carboxylic acid compounds include 1,2,4-benzenetricarboxylic acid (trimellitic acid), 2,5,7-naphthalenetricarboxylic acid, pyromellitic acid, anhydrides of these acids, and alkyl esters in which the alkyl group has 1 to 3 carbon atoms. Of these, trimellitic acid compounds are preferred.

From the viewpoint of hot offset resistance, the content of trivalent or higher carboxylic acid compounds in the carboxylic acid component is preferably 3 mol% or more, more preferably 10 mol% or more, and even more preferably 20 mol% or more, and is preferably 40 mol% or less, more preferably 30 mol% or less. The carboxylic acid component also includes the terephthalic acid units contained in PET.

The alcohol component may contain a monohydric alcohol, and the carboxylic acid component may contain a monocarboxylic acid compound, as appropriate.

In the polycondensation reaction, PET undergoes transesterification and depolymerization with an alcohol component and a carboxylic acid component and is incorporated into the resin structure. Therefore, the resulting polyester resin is a polyester resin in which ethylene glycol and terephthalic acid, which are components of PET, are subjected to the polycondensation reaction as raw material monomers.
Therefore, in the present invention, it is preferable that the PET has a relatively low IV value, i.e., a low molecular weight, compared to conventionally used PET. In the present invention, by introducing a PET with a low IV value (low molecular weight) into the polyester resin, depolymerization of the PET proceeds more uniformly.

From the above perspectives, the IV value of PET is preferably 0.40 or higher, more preferably 0.45 or higher, even more preferably 0.50 or higher, and even more preferably 0.55 or higher. From the perspectives of low-temperature fixability and uniform depolymerization, it is preferably 0.85 or lower, more preferably 0.80 or lower, even more preferably 0.75 or lower, even more preferably 0.70 or lower, and even more preferably 0.65 or lower. The IV value is intrinsic viscosity and is an index of molecular weight. The IV value of PET can be adjusted by the polycondensation time, etc.

Commercially available PET products with an IV value of 0.40 or greater and 0.85 or less include RAMAPET L1 (manufactured by Indorama Ventures, IV value: 0.60), RAMAPET BF3067 (manufactured by Indorama Ventures, IV value: 0.65), RAMAPET N2G (manufactured by Indorama Ventures, IV value: 0.75), TRN-NTJ (manufactured by Teijin Limited, IV value: 0.53), TRN-RTJC (manufactured by Teijin Limited, IV value: 0.64), and RAMAPET S1 (manufactured by Indorama Ventures, IV value: 0.84).

The content of low IV PET is preferably 90% by mass or more, more preferably 95% by mass or more, even more preferably 98% by mass or more, and even more preferably 100% by mass of the total amount of PET used in polycondensation.

From the viewpoint of fixability, the content of PET is preferably 10 mol% or more of the total amount of the alcohol component, the carboxylic acid component, and the PET, and is preferably 50 mol% or less, more preferably 40 mol% or less, and even more preferably 30 mol% or less.
Since PET is a polycondensation of ethylene glycol with terephthalic acid, dimethyl terephthalate, etc., the terephthalic acid-ethylene glycol unit (Mw: 192) is counted as 1 mole. Therefore, the number of moles of PET = the number of moles of ethylene glycol units = the number of moles of terephthalic acid units.

The equivalent ratio (COOH groups/OH groups) of the carboxylic acid component (including the terephthalic acid units in the PET) to the alcohol component (including the ethylene glycol units in the PET) is preferably 0.6 or more, more preferably 0.7 or more, even more preferably 0.75 or more, and is preferably 1.2 or less, more preferably 1.15 or less.

The binder resin composition of the present invention has a content of low-molecular-weight cyclic volatile components controlled within a predetermined range. The low-molecular-weight cyclic volatile components are low-molecular-weight cyclic volatile components having a molecular weight of 50 or more and 200 or less, which are produced by intramolecular cyclization of an aliphatic dicarboxylic acid compound.

The content of low-molecular-weight cyclic volatile components is 25% by mass or less, preferably 15% by mass or less, more preferably 5% by mass or less, and even more preferably 2% by mass or less of the volatile components (total amount of volatile components) in the binder resin composition.

On the other hand, the content of low-molecular-weight cyclic volatile components in the binder resin composition is preferably 1.0 ppm or less, more preferably 0.5 ppm or less, and even more preferably 0.3 ppm or less.

Furthermore, the total amount of volatile components in the binder resin composition is preferably 10 ppm or less, more preferably 7 ppm or less, and even more preferably 4 ppm or less.

The binder resin composition of the present invention, in which the content of low-molecular-weight cyclic volatile components is controlled, can be obtained by, for example, a method of removing the low-molecular-weight cyclic volatile components by steam distillation.
Step 1: a step of polycondensing an alcohol component, a carboxylic acid component including an aliphatic dicarboxylic acid compound having 4 to 12 carbon atoms, and polyethylene terephthalate;
A method including step 2: steam distilling the reaction mixture obtained in step 1, and step 3: reducing the pressure in the reaction system after step 2 to remove water is preferred.

In step 1, the polycondensation reaction between the alcohol component, carboxylic acid component, and PET can be carried out, for example, in an inert gas atmosphere, preferably in the presence of an esterification catalyst, and, if necessary, in the presence of an esterification promoter, polymerization inhibitor, etc., at a temperature preferably between approximately 180°C and 250°C.

Examples of esterification catalysts include tin compounds such as dibutyltin oxide and tin(II) 2-ethylhexanoate, and titanium compounds such as titanium diisopropylate bistriethanolamine. Among these, tin compounds such as tin(II) 2-ethylhexanoate are preferred. The amount of the esterification catalyst used is preferably 0.01 parts by mass or more, more preferably 0.1 parts by mass or more, and preferably 1.5 parts by mass or less, more preferably 1.0 part by mass or less, per 100 parts by mass of raw material monomers (alcohol component, carboxylic acid component, and PET). Examples of esterification promoters include gallic acid. The amount of the 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, more preferably 0.1 parts by mass or less, per 100 parts by mass of raw material monomers. Examples of polymerization inhibitors include tert-butylcatechol. The amount of polymerization inhibitor used is preferably 0.001 part by mass or more, more preferably 0.01 part by mass or more, and preferably 0.5 part by mass or less, more preferably 0.1 part by mass or less, per 100 parts by mass of raw material monomer.

In step 2, steam distillation is a method in which water is supplied to the heated reaction system and mixed with the reaction mixture obtained in step 1, causing the low-molecular-weight cyclic volatile components to undergo azeotropic distillation with water vapor.

The temperature of the reaction mixture to which water is supplied is 100°C or higher, preferably 220°C or lower, and more preferably 210°C or lower. By mixing water into a reaction mixture within this temperature range, water vapor remains in the polyester resin, and together with distillation, low-molecular-weight cyclic volatile components can be removed from the reaction mixture obtained in step 1.

The amount of water vapor supplied is preferably 2 parts by mass or more, more preferably 3 parts by mass or more, and even more preferably 4 parts by mass or more, per 100 parts by mass of the raw material monomers (alcohol component, carboxylic acid component, and PET) of amorphous polyester resin A, and from the standpoint of productivity, is preferably 10 parts by mass or less, more preferably 8 parts by mass or less, and even more preferably 6 parts by mass or less.

The water supply rate is preferably 0.03 parts by mass/min or more, more preferably 0.05 parts by mass/min or more, even more preferably 0.07 parts by mass/min or more, and preferably 0.16 parts by mass/min or less, more preferably 0.13 parts by mass/min or less, even more preferably 0.10 parts by mass/min or less, per 100 parts by mass of the raw material monomers (alcohol component, carboxylic acid component, and PET) for amorphous polyester resin A.

In step 3, moisture can be removed by maintaining the reaction system at a temperature of, for example, 200°C or higher and 250°C or lower, under reduced pressure, for example, 30 kPa or lower.

When a trivalent or higher carboxylic acid compound is used as the carboxylic acid component, it is preferable to remove the water and then carry out a further polycondensation reaction until the desired softening point is reached.

From the viewpoint of hot offset resistance, the softening point of amorphous polyester resin A is preferably 120°C or higher, more preferably 125°C or higher, and even more preferably 130°C or higher. From the viewpoint of low-temperature fixability, it is preferably 160°C or lower, more preferably 150°C or lower, and even more preferably 145°C or lower.

The crystallinity of a resin is expressed by the crystallinity index, which is defined as the ratio of the softening point to the maximum endothermic peak temperature measured by a differential scanning calorimeter, i.e., the value of [softening point/maximum endothermic peak temperature]. A crystalline resin is a resin having a crystallinity index of 0.6 or more, preferably 0.7 or more, more preferably 0.9 or more, and 1.4 or less, preferably 1.2 or less, more preferably 1.1 or less.
On the other hand, an amorphous resin is a resin in which no endothermic peak is observed, or if an endothermic peak is observed, the resin has a crystallinity index of more than 1.4, preferably more than 1.5, more preferably 1.6 or more, or less than 0.6, preferably 0.5 or less.
The crystallinity of a resin can be adjusted by the type and ratio of raw material monomers, and production conditions (e.g., reaction temperature, reaction time, cooling rate), etc. The maximum endothermic peak temperature refers to the temperature of the peak with the largest peak area among the observed endothermic peaks. For crystalline resins, the maximum endothermic peak temperature is the melting point.

From the viewpoint of heat-resistant storage stability, the glass transition temperature of amorphous polyester resin A is preferably 45°C or higher, more preferably 50°C or higher, and even more preferably 52°C or higher. From the viewpoint of low-temperature fixability, it is preferably 70°C or lower, more preferably 65°C or lower, and even more preferably 60°C or lower.

From the viewpoint of charge stability, the acid value of amorphous polyester resin A is preferably 5 mgKOH/g or more, more preferably 10 mgKOH/g or more, and preferably 40 mgKOH/g or less, more preferably 30 mgKOH/g or less.

In the present invention, the polyester resin may be modified to the extent that its properties are not substantially impaired. Examples of modified polyester resins include polyester resins grafted or blocked with phenol, urethane, epoxy, or the like, using methods described in JP-A Nos. 11-133668, 10-239903, and 8-20636.

Furthermore, the present invention provides a toner containing the toner binder resin composition of the present invention as a binder resin, specifically a toner for developing electrostatic images containing the toner binder resin composition of the present invention and a colorant.

The toner of the present invention may contain a resin other than the binder resin composition of the present invention as a binder resin, and the content of amorphous polyester resin A in the binder resin is preferably 40% by mass or more, more preferably 50% by mass or more, and even more preferably 55% by mass or more.

From the viewpoint of low-temperature fixability, it is preferable that the toner of the present invention further contains an amorphous polyester resin (hereinafter also referred to as amorphous polyester resin AL) having a softening point lower than that of amorphous polyester resin A.

The difference in softening point between amorphous polyester resin A (hereinafter also referred to as amorphous polyester resin AH) and amorphous polyester resin AL is preferably 20°C or more, more preferably 30°C or more, even more preferably 38°C or more, and preferably 60°C or less, more preferably 55°C or less, even more preferably 45°C or less.

The amorphous polyester resin AL is preferably a polycondensate of an alcohol component containing an alkylene oxide adduct of bisphenol A represented by formula (I) above and a carboxylic acid component containing an aromatic dicarboxylic acid compound.

The content of the alkylene oxide adduct of bisphenol A represented by formula (I) in the alcohol component is preferably 70 mol% or more, more preferably 80 mol% or more, even more preferably 90 mol% or more, even more preferably 95 mol% or more, and even more preferably 100 mol%.

Aromatic dicarboxylic acid compounds include the same compounds as those mentioned above, with terephthalic acid being preferred.

The content of the aromatic dicarboxylic acid compound in the carboxylic acid component is preferably 70 mol% or more, more preferably 80 mol% or more, even more preferably 90 mol% or more, even more preferably 95 mol% or more, and even more preferably 100 mol%.

Carboxylic acid components other than aromatic dicarboxylic acid compounds include aliphatic dicarboxylic acid compounds and trivalent or higher carboxylic acid compounds.

The alcohol component may contain a monohydric alcohol, and the carboxylic acid component may contain a monocarboxylic acid compound, as appropriate.

The equivalent ratio of the carboxyl groups of the carboxylic acid component to the hydroxyl groups of the alcohol component (COOH groups/OH groups) is preferably 0.6 or more, more preferably 0.7 or more, even more preferably 0.75 or more, and preferably 1.2 or less, more preferably 1.15 or less.

Amorphous polyester resin AL can be produced by polycondensation of an alcohol component and a carboxylic acid component in the same manner as amorphous polyester resin AH.

From the viewpoint of heat-resistant storage stability, the softening point of the amorphous polyester resin AL is preferably 80°C or higher, more preferably 83°C or higher, and even more preferably 90°C or higher. From the viewpoint of low-temperature fixability, it is preferably 120°C or lower, more preferably 110°C or lower, and even more preferably 100°C or lower.

From the viewpoint of heat-resistant storage stability, the glass transition temperature of the amorphous polyester resin AL is preferably 45°C or higher, more preferably 50°C or higher, and even more preferably 53°C or higher. From the viewpoint of low-temperature fixability, it is preferably 70°C or lower, more preferably 65°C or lower, and even more preferably 60°C or lower.

From the viewpoint of charging stability, the acid value of the amorphous polyester resin AL is preferably 2 mgKOH/g or more, more preferably 4 mgKOH/g or more, and preferably 20 mgKOH/g or less, more preferably 15 mgKOH/g or less.

The mass ratio of amorphous polyester resin AL to amorphous polyester resin AH (amorphous polyester resin AL/amorphous polyester resin AH) is preferably 30/70 or more, more preferably 40/60 or more, and preferably 80/20 or less, more preferably 60/40 or less.

The total content of amorphous polyester resin in the binder resin is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and even more preferably 100% by mass.

Other binder resins include polyester resins other than the amorphous polyester resins mentioned above, vinyl resins such as styrene-acrylic resins, epoxy resins, polycarbonates, polyurethanes, and composite resins containing two or more of these resins.

The binder resin content in the toner is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, and even more preferably 80% by mass or more, and is preferably 99% by mass or less, more preferably 98% by mass or less, and even more preferably 95% by mass or less.

The colorant may be a dye, pigment, magnetic material, or the like that is used as a toner colorant. In the present invention, the toner may be either a black toner or a color toner.

Colorants that can be used include dyes, pigments, magnetic materials, and the like that are used as toner colorants. Examples include carbon black, phthalocyanine blue, permanent brown FG, brilliant fast scarlet, pigment red 122, pigment green B, rhodamine B base, solvent red 49, solvent red 146, solvent blue 35, quinacridone, carmine 6B, isoindoline, and disazo yellow. In the present invention, the toner may be either black or color toner.

From the viewpoint of improving the image density and low-temperature fixability of the toner, the content of the colorant is preferably 1 part by weight or more, more preferably 2 parts by weight or more, and preferably 40 parts by weight or less, more preferably 20 parts by weight or less, and even more preferably 10 parts by weight or less, per 100 parts by weight of the binder resin.

In addition to the binder resin and colorant, the toner for developing electrostatic images of the present invention may contain additives such as a release agent, a charge control agent, a magnetic powder, a flowability improver, a conductivity adjuster, a reinforcing filler such as a fibrous substance, an antioxidant, and a cleaning improver.

Examples of release agents include hydrocarbon waxes such as polypropylene wax, polyethylene wax, polypropylene-polyethylene copolymer wax, microcrystalline wax, paraffin wax, and Fischer-Tropsch wax, as well as their oxides; ester waxes such as carnauba wax, montan wax, and their deoxidized waxes, and fatty acid ester wax; fatty acid amides, fatty acids, higher alcohols, and fatty acid metal salts, which can be used alone or in combination of two or more.

The melting point of the release agent is preferably 60°C or higher, more preferably 70°C or higher, from the viewpoint of toner transferability, and preferably 160°C or lower, from the viewpoint of low-temperature fixability.

From the viewpoints of the toner's low-temperature fixability and offset resistance, and its dispersibility in the binder resin, the content of the release agent is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and even more preferably 1.5 parts by mass or more, per 100 parts by mass of binder resin, and is preferably 10 parts by mass or less, more preferably 8 parts by mass or less, and even more preferably 7 parts by mass or less.

The charge control agent is not particularly limited, and may contain either a positively chargeable charge control agent or a negatively chargeable charge control agent.

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," and "Bontron N-11" (all manufactured by Orient Chemical Industries Co., Ltd.); triphenylmethane dyes containing a tertiary amine as a side chain; quaternary ammonium salt compounds, such as "Bontron P-51" (manufactured by Orient Chemical Industries Co., Ltd.), cetyltrimethylammonium bromide, and "COPY CHARGE PX" (manufactured by Orient Chemical Industries Co., Ltd.). VP435 (manufactured by Clariant), etc.; polyamine resins, such as AFP-B (manufactured by Orient Chemical Industries, Ltd.); imidazole derivatives, such as PLZ-2001 and PLZ-8001 (both manufactured by Shikoku Chemical Industries, Ltd.); styrene-acrylic resins, such as FCA-701PT and FCA-201-PS (manufactured by Fujikura Chemical Industries, Ltd.), etc.

Negatively chargeable charge control agents include metal-containing azo dyes, such as "Balifast Black 3804," "Bontron S-31," "Bontron S-32," "Bontron S-34," and "Bontron S-36" (all manufactured by Orient Chemical Industries, Ltd.), "Eisenspiron Black TRH," and "T-77" (manufactured by Hodogaya Chemical Co., Ltd.); metal compounds of benzilic acid compounds, such as "LR-147" and "LR-297" (manufactured by Nippon Carlit Co., Ltd.); metal compounds of salicylic acid compounds, such as "Bontron E-81," "Bontron E-84," "Bontron E-88," and "Bontron E-304" (all manufactured by Orient Chemical Industries, Ltd.), and "TN-105" (manufactured by Hodogaya Chemical Co., Ltd.); copper phthalocyanine dyes; and quaternary ammonium salts, such as "COPY CHARGE NX" VP434 (Clariant), nitroimidazole derivatives, organometallic compounds, etc.

From the viewpoint of toner charge stability, the content of the charge control agent is preferably 0.01 parts by mass or more, more preferably 0.2 parts by mass or more, and preferably 10 parts by mass or less, more preferably 5 parts by mass or less, even more preferably 3 parts by mass or less, and even more preferably 2 parts by mass or less, per 100 parts by mass of binder resin.

The toner of the present invention may be obtained by any conventional method such as the melt-kneading method, emulsion phase inversion method, or polymerization method. However, from the viewpoints of productivity and colorant dispersibility, pulverized toner obtained by the melt-kneading method is preferred. In the case of pulverized toner obtained by the melt-kneading method, for example, raw materials such as a binder resin, a colorant, and, if necessary, a release agent and a charge control agent are uniformly mixed in a mixer such as a Henschel mixer, and then melt-kneaded in an internal kneader, a single-screw or twin-screw extruder, an open-roll kneader, or the like, followed by cooling, pulverization, and classification.

When producing toner, if the binder resin is made up of multiple resins, a binder resin in which multiple resins are mixed in advance may be used, but when producing toner, each resin may be directly used to mix the raw materials.

The toner of the present invention preferably uses an external additive to improve transferability. Examples of external additives include inorganic fine particles such as silica, alumina, titania, zirconia, tin oxide, and zinc oxide, and organic fine particles such as resin particles such as melamine-based resin fine particles and polytetrafluoroethylene resin fine particles. Two or more types may be used in combination. Of these, silica is preferred, and from the perspective of toner transferability, hydrophobic silica that has been hydrophobized is even more preferred.

Hydrophobic treatment agents used to hydrophobize the surface of silica particles include hexamethyldisilazane (HMDS), dimethyldichlorosilane (DMDS), silicone oil, octyltriethoxysilane (OTES), and methyltriethoxysilane.

From the viewpoint of the chargeability, fluidity, and transferability of the toner, the average particle diameter of the external additive is preferably 10 nm or more, more preferably 15 nm or more, and preferably 250 nm or less, more preferably 200 nm or less, and even more preferably 90 nm or less.

From the viewpoint of the toner's chargeability, fluidity, and transferability, the content of the external additive is preferably 0.05 parts by weight or more, more preferably 0.1 parts by weight or more, and even more preferably 0.3 parts by weight or more, per 100 parts by weight of toner particles before treatment with the external additive, and is preferably 5 parts by weight or less, and more preferably 3 parts by weight or less.

The volume median particle diameter ( _D50 ) of the toner of the present invention is preferably 3 μm or more, more preferably 4 μm or more, and preferably 15 μm or less, more preferably 10 μm or less. In this specification, the volume median particle diameter ( _D50 ) means the particle diameter at which the cumulative volume frequency calculated by volume fraction is 50% counted from the smallest particle diameter. In addition, when the toner is treated with an external additive, the volume median particle diameter of the toner particles before treatment with the external additive is taken as the volume median particle diameter of the toner.

The toner of the present invention can be used as a single-component developing toner as is, or as a two-component developing toner mixed with a carrier, in image forming devices using either a single-component or two-component developing system, respectively.

The present invention will be explained in detail below using examples, but the present invention is not limited to these examples. Physical properties of resins and the like can be measured by the following methods.

[PET IV value]
The viscosity can be determined by dissolving the material in a 60/40 phenol/tetrachloroethane (mass ratio) mixed solvent at a concentration of 4 g/L, measuring with an Ubbelohde viscometer, and calculating according to the following formula.
IV=(-1+√(1+4kη))/(2kC)
(where k = 0.33, C = 0.004 g/mL, and η = (t/t) (t: number of seconds it takes for the solvent alone to fall, and t: number of seconds it takes for the sample solution to fall).)

[Content of low molecular weight cyclic volatile components in resin]
(1) Measurement of standard toluene solution: Weigh 100 mg of toluene into a 100 mL volumetric flask and make up to 100% with methanol. This solution is further diluted 100 times to make the standard toluene solution. Add 10 μL of the standard toluene solution to a 20 mL headspace vial and quickly seal it with an aluminum cap. Measure the headspace gas under the conditions shown below.
(2) Sample measurement
30 to 40 g of the sample is ground in a coffee mill for 15 seconds, and 500 mg of the resulting finely ground material is weighed into a 20 mL headspace vial and sealed with an aluminum cap.
The vial containing the sample was placed in a headspace sampler "Agilent 7697" (Agilent Technologies) and heated at 70°C for 25 minutes. The headspace gas was then introduced into a gas chromatograph "Agilent 7890B" (Agilent Technologies) and measured under the conditions shown below.
From the peak area obtained by the measurement and the toluene peak area measured above, the total amount of volatile organic compounds (TVOC) and the amount of cyclic volatile organic compounds (CVOC) with a molecular weight of 50 or more and 200 or less in the sample resin are calculated in toluene equivalent, and the CVOC (mass%) in the TVOC is further calculated.
[Measurement conditions]
Headspace sampler conditions: Oven temperature: 70°C
Loop temperature: 170℃
Line temperature: 200℃
Vial equilibration time: 25 minutes GC measurement conditions Column: DB-624 (60 m x 320 μm x 1.8 μm: Agilent Technologies)
Detector: MSD
Oven temperature rise conditions: Initial temperature 40°C (hold for 2 minutes)
First stage temperature increase rate: 7°C/min Final temperature: 220°C (held for 8 minutes)
Inlet temperature: 200℃
Detector temperature: 300°C
Split ratio: 20:1
Column flow rate: 1.2 mL/min (He)

[Softening point of resin]
Using a flow tester "CFT-500D" (Shimadzu Corporation), 1g of sample is heated at a temperature increase rate of 6℃/min while applying a load of 1.96MPa with the plunger, and extruding it from a nozzle 1mm in diameter and 1mm in length. The plunger depression distance 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 endothermic peak temperature of resin]
Using a differential scanning calorimeter "Q-100" (TA Instruments Japan Co., Ltd.), 0.01 to 0.02 g of sample is weighed into an aluminum pan, cooled from room temperature (20°C) to 0°C at a rate of 10°C/min, and maintained at that temperature for 1 minute. The sample is then heated to 180°C at a rate of 10°C/min while measuring the endothermic peak. The temperature of the peak with the largest peak area among the observed endothermic peaks is taken as the maximum endothermic peak temperature.

[Glass transition temperature of resin]
Using a differential scanning calorimeter "Q-20" (TA Instruments Japan Co., Ltd.), 0.01 to 0.02 g of sample was weighed into an aluminum pan, heated to 200°C, and cooled from that temperature to 0°C at a rate of 10°C/min. The sample was then heated at a rate of 10°C/min, and the glass transition temperature was determined as the temperature at the intersection of an extension of the baseline below the maximum endothermic peak temperature and a tangent line showing the maximum slope from the rising part of the peak to the peak apex.

[Acid value of resin]
Measurement is performed based on the method of JIS K 0070:1992, except that the measurement solvent is changed from the ethanol and ether mixture specified in JIS K 0070 to a mixture of acetone and toluene (acetone:toluene = 1:1 (volume ratio)).

[Melting point of release agent]
Using a differential scanning calorimeter "DSC 210" (manufactured by TA Instruments Japan Co., Ltd.), 0.01 to 0.02 g of sample is weighed into an aluminum pan, heated to 200°C at a heating rate of 10°C/min, and cooled from that temperature to -10°C at a cooling rate of 5°C/min. Next, the sample is heated to 180°C at a heating rate of 10°C/min and measured. The maximum endothermic peak temperature observed in the melting endothermic curve obtained is taken as the melting point of the release agent.

[Average particle size of external additives]
The average particle size refers to the number-average particle size, and is calculated by measuring the particle sizes (average values of major and minor axes) of 500 particles in a scanning electron microscope (SEM) photograph and averaging these values by number.

[Volume Median Particle Size of Toner]
Measuring device: Coulter Multisizer II (manufactured by Beckman Coulter, Inc.)
Aperture diameter: 50 μm
Analysis software: Coulter Multisizer AccuComp version 1.19 (Beckman Coulter, Inc.)
Electrolyte: Isoton II (Beckman Coulter, Inc.)
Dispersion liquid: Emulgen 109P (Kao Corporation, polyoxyethylene lauryl ether, HLB (Griffin): 13.6) was dissolved in the electrolyte to adjust the concentration to 5% by mass. Dispersion conditions: 10 mg of the measurement sample was added to 5 mL of the dispersion liquid, and the mixture was dispersed for 1 minute using an ultrasonic disperser (machine name: US-1, manufactured by SND Corporation, output: 80 W). Thereafter, 25 mL of the electrolyte liquid was added, and the mixture was further dispersed for 1 minute using the ultrasonic disperser to prepare a sample dispersion liquid.
Measurement conditions: The sample dispersion is added to 100 mL of the electrolyte to a concentration that allows the particle diameters of 30,000 particles to be measured in 20 seconds, and the volume median particle diameter (D ₅₀ ) is determined from the particle size distribution.

Resin Production Example 1
The alcohol components, terephthalic acid, PET, esterification catalyst, and esterification co-catalyst shown in Table 1 were placed in a 10-liter four-neck flask equipped with a thermometer, a stainless steel stirring rod, a downflow condenser, and a nitrogen inlet tube. The mixture was heated to 235°C in a nitrogen atmosphere in a mantle heater. After confirming that the reaction rate reached 95% or more at 235°C, the mixture was cooled to 190°C. The aliphatic dicarboxylic acid compound shown in Table 1 was then added, and the mixture was heated to 230°C over 2 hours and then reacted at 26.7 kPa for 1 hour. Next, 350 g of ion-exchanged water (5 parts by mass per 100 parts by mass of raw material monomers, feed rate 0.08 parts by mass/min) was added to the resin over 1 hour while stirring the reaction mixture at 200°C. The mixture was then heated to 230°C, reduced pressure at 26.7 kPa for 0.5 hours, and steam distillation was performed. After that, the mixture was cooled to 190°C, and then trimellitic anhydride was added. The mixture was maintained at 210°C for 30 minutes and reacted under a reduced pressure of 80 kPa until the softening point shown in Table 1 was reached, thereby obtaining amorphous polyester resins (resins AH1 to AH5). In the present invention, the reaction rate refers to the value of the amount of reaction water produced (mol)/theoretical amount of water produced (mol)×100.

Resin Production Example 2
The alcohol component, terephthalic acid, esterification catalyst, and esterification co-catalyst shown in Table 1 were placed in a 10-liter four-neck flask equipped with a thermometer, a stainless steel stirring rod, a downflow condenser, and a nitrogen inlet tube, and the flask was heated to 235°C in a nitrogen atmosphere using a mantle heater. After confirming that the reaction rate had reached 95% or more at 235°C, the flask was cooled to 190°C. The aliphatic dicarboxylic acid shown in Table 1 was then added, and the mixture was heated to 230°C over 2 hours and then reacted at 26.7 kPa for 1 hour. After cooling to 190°C, trimellitic anhydride was added, the mixture was maintained at 210°C for 30 minutes, and the reaction was continued under a reduced pressure of 80 kPa until the softening point shown in Table 1 was reached, yielding an amorphous polyester resin (Resin AH6).

Resin Production Example 3
The alcohol component, terephthalic acid, PET, esterification catalyst, and esterification co-catalyst shown in Table 1 were placed in a 10-liter four-neck flask equipped with a thermometer, a stainless steel stirring rod, a downflow condenser, and a nitrogen inlet tube, and the mixture was heated to 235°C in a nitrogen atmosphere in a mantle heater. After confirming that the reaction rate had reached 95% or more at 235°C, the mixture was cooled to 190°C. The aliphatic dicarboxylic acid shown in Table 1 was then added, and the mixture was heated to 230°C over 2 hours, followed by a reaction at 26.7 kPa for 1 hour. After cooling to 190°C, trimellitic anhydride was added, the mixture was held at 210°C for 30 minutes, and the reaction was continued under a reduced pressure of 80 kPa until the softening point shown in Table 1 was reached, yielding an amorphous polyester resin (Resin AH7).

Resin Production Example 4
The raw material monomers, esterification catalyst, and esterification co-catalyst shown in Table 1 were placed in a 10-liter four-neck flask equipped with a thermometer, a stainless steel stirring rod, a downflow condenser, and a nitrogen inlet tube, and the temperature was raised to 235°C in a mantle heater under a nitrogen atmosphere. After that, it was confirmed that the reaction rate had reached 95% or more at 235°C. Thereafter, the reaction was continued under a reduced pressure of 8 kPa until the softening point shown in Table 1 was reached, yielding an amorphous polyester resin (Resin AL1).

The physical properties of the resulting resins are shown in Table 1. We also attempted to measure the maximum endothermic peak temperature, but no endothermic peak was observed for any of the resins.

Examples 1 to 5, Comparative Example 1 and Reference Example 1
100 parts by mass of the binder resin shown in Table 2, 1 part by mass of a negatively chargeable charge control agent "Bontron E-81" (manufactured by Orient Chemical Industries, Ltd.), 5 parts by mass of a colorant "Regal 330R" (manufactured by Cabot Corporation, carbon black), and 3 parts by mass of a release agent "NP-055" (manufactured by Mitsui Chemicals, Inc., polypropylene wax, melting points: 136°C, 145°C) were thoroughly mixed in a Henschel mixer, and then melt-kneaded using a co-rotating twin-screw extruder with a kneading section total length of 1560 mm, a screw diameter of 42 mm, and a barrel inner diameter of 43 mm at a roll rotation speed of 200 r/min and a heating temperature inside the roll of ₁₀₀ °C. The resulting melt-kneaded product was cooled and coarsely pulverized, then finely pulverized using an I-2 type pulverizer (manufactured by Nippon Pneumatic Co., Ltd.), and classified to obtain toner particles with a volume median particle size (D50) of 6.5 μm.

To 100 parts by mass of the resulting toner particles, 2.0 parts by mass of the external additive "Aerosil R-972" (hydrophobic silica, manufactured by Nippon Aerosil Co., Ltd., hydrophobic treatment agent: DMDS, average particle size: 16 nm) were added, and the mixture was mixed for 5 minutes at 3600 rpm using a Henschel mixer to perform external addition treatment, yielding a toner.

Test Example 1 [Odor]
10 g of toner was weighed into an aluminum cup, the cup was covered with a lid, and the cup was left standing on a hot plate heated to 160° C. for 15 minutes, and the odor emitted from the toner was evaluated according to the following evaluation criteria. The results are shown in Table 2.
<Evaluation criteria>
A: No odor is detected at all.
B: Almost no odor is noticeable.
C: A slight odor is detected.
D: A strong odor is felt.

Test Example 2 [Storage]
4 g of toner was left for 72 hours in an environment of 50°C and 45% humidity. After leaving for 48 hours and 72 hours, the degree of toner aggregation was visually observed and the storage stability was evaluated according to the following evaluation criteria. The results are shown in Table 2.
<Evaluation criteria>
A: No aggregation was observed even after 48 and 72 hours.
B: No aggregation is observed after 48 hours, but slight aggregation is observed after 72 hours.
C: No aggregation is observed after 48 hours, but aggregation is clearly observed after 72 hours.

From the above results, it can be seen that in all of Examples 1 to 5, the odor was reduced and the storage stability was good.
In contrast, resin AH7, which was not subjected to steam distillation during production, contains a higher amount of low molecular weight cyclic volatile components than resin AH2, and it can be seen that comparison example 1, which used resin AH7, generates an odor and lacks shelf life.
Furthermore, in Reference Example 1, in which ethylene glycol and terephthalic acid, which are components of PET, were used instead of PET, no odor was generated and the storage stability was good. This shows that the issue of odor due to low-molecular-weight components is not due to the type of monomer, but is due to the use of PET.

Toners for developing electrostatic images containing the toner binder resin composition of the present invention are suitable for use in developing latent images formed in electrostatic image development methods, electrostatic recording methods, electrostatic printing methods, etc.

Claims (2)

Step 1: A step of polycondensing an alcohol component, a carboxylic acid component including an aliphatic dicarboxylic acid compound having from 4 to 12 carbon atoms (but not including a trivalent or higher carboxylic acid compound) , and polyethylene terephthalate;
Step 2: steam distilling the reaction mixture obtained in step 1 ;
Step 3: A step of reducing the pressure in the reaction system after Step 2 to remove water ; and
Step 4: After Step 3, a trivalent or higher carboxylic acid compound is added and a polycondensation reaction is carried out.
wherein the binder resin composition contains 10 ppm or less of volatile components, and the content of low-molecular-weight cyclic volatile components having a molecular weight of 50 or more and 200 or less among the volatile components is 25 mass % or less. Step 1: A step of polycondensing an alcohol component, a carboxylic acid component including an aliphatic dicarboxylic acid compound having from 4 to 12 carbon atoms (but not including a trivalent or higher carboxylic acid compound), and polyethylene terephthalate;
Step 2: steam distilling the reaction mixture obtained in step 1;
Step 3: A step of reducing the pressure in the reaction system after Step 2 to remove water; and
Step 4: After Step 3, a trivalent or higher carboxylic acid compound is added and a polycondensation reaction is carried out.
a step I for producing a binder resin composition for toner, the binder resin composition having a volatile component content of 10 ppm or less and a low-molecular-weight cyclic volatile component content of 50 to 200 of the volatile components of 25 mass % or less by a method comprising the steps of:
Step II: mixing the obtained raw materials including the binder resin composition for toner, melt-kneading the mixture, cooling, pulverizing, and classifying the mixture.
A method for producing a toner for developing electrostatic images, comprising: