JP4390643B2 - Polyester for toner - Google Patents

Description

  The present invention relates to a polyester for toner suitable as a binder resin for toner used for developing a latent image formed in an electrophotographic method, an electrostatic recording method, an electrostatic printing method, and the like, and a toner containing the polyester.

  2. Description of the Related Art Conventionally, a technique for adding wax to toner for improving hot offset is known. However, in the case of a toner containing polyester as a binder resin, since the compatibility between the polyester and the wax is low, the wax is difficult to disperse in the resin. Furthermore, when the difference in viscosity between the resin and the wax is large, additives such as carbon black tend to aggregate on the wax portion having a low melt viscosity, which may cause a decrease in charge amount. Thus, it is known to use a hydroxyl group-modified wax having a high affinity for polyester (see Patent Document 1), but the effect is insufficient.

On the other hand, a toner binder composition (see Patent Document 2) in which the difference in physical properties between the binder resin and the wax is adjusted, and polyester with wax added therein as the binder resin are used. A toner adjusted to a specific range (see Patent Document 3) has also been reported, but from the viewpoint of wax dispersibility, further improvement in performance is desired.
JP 10-10785 A (Claim 4) JP-A-7-301951 (Claim 1) JP 2002-148844 A (Claim 1)

  An object of the present invention is to provide a polyester for toner excellent in both hot offset resistance and chargeability and a toner containing the polyester.

  The present invention relates to a polyester for toner obtained by performing at least a part of the condensation polymerization reaction between an alcohol component and a carboxylic acid component in the presence of a wax having a polar group, and the wax is added in an amount of 0.5 to 20% by weight. The present invention relates to a polyester for toner and a toner containing the polyester for toner.

  Since the polyester for toner of the present invention is excellent in both hot offset resistance and chargeability, it can be suitably used as a binder resin for toner.

  The present inventors examined a means for improving the dispersibility of the wax in the polyester. As the wax, a wax having a polar group having a good compatibility with the polyester was used, and further, an alcohol component and a carboxylic acid component were used. It has been found that a polyester having excellent wax dispersibility can be obtained by performing at least a part of the condensation polymerization reaction in the presence of such a wax. Even when such a polyester is mixed with an additive such as carbon black at the time of toner production, the additive is uniformly dispersed in the resin without agglomerating in the wax part. Hot offset resistance can be improved.

In the present invention, the polar group possessed by the wax includes a hydroxyl group (—OH), a carboxyl group (—COOH), an ester bond (—COO—), a urethane group (—NHCOO—), a carbonyl group (> CO), and an ether bond. (—O—), amide group (—CONH ₂ ) and the like can be mentioned, and the wax used in the present invention preferably has at least a hydroxyl group from the viewpoint of compatibility with polyester.

  In the wax having a hydroxyl group, the total value of the hydroxyl value and the acid value is preferably 5 to 150 mgKOH / g, more preferably 10 to 100 mgKOH / g, and still more preferably 10 to 60 mgKOH / g, from the viewpoint of dispersibility of the wax. When a plurality of types of wax having a hydroxyl group are contained, it is preferable that the weighted average value thereof falls within the above range.

  As the wax having a hydroxyl group, a wax modified with alcohol based on paraffin wax “FT-100” (manufactured by Nippon Seiwa Co., Ltd.), for example, “PARACOHOL-5300” (hydroxyl value: 17 mgKOH / g, acid value: 1 mgKOH) / PAR), "PARACOHOL-6110" (hydroxyl value: 50 mgKOH / g, acid value: 4 mgKOH / g), "PARACOHOL-5003A" (hydroxyl value: 32 mgKOH / g, acid value: 5 mgKOH / g) Wax Co.).

  As the wax having a carboxyl group, a wax modified with an acid based on “FT-100”, for example, “OX-0420” (manufactured by Nippon Seiwa Co., Ltd., hydroxyl value: 6 mgKOH / g, acid value: 3 mgKOH / g) Etc.

  Examples of the wax having an ester bond include carnauba wax.

  Examples of the wax having a urethane group include “NPS-6010” and “HAD-5150” (manufactured by Nippon Seiwa Co., Ltd.).

  Examples of the wax having a carbonyl group include diheptadecyl ketone.

  Examples of the wax having an ether bond include n-hexadecyl ether.

  As described above, among the waxes having polar groups specifically exemplified, waxes modified with alcohols such as “PARACOHOL-5300”, “PARACOHOL-6110”, “PARACOHOL-5003A” and the like are preferable.

  The melting point of the wax having a polar group is preferably from 70 to 150 ° C., more preferably from 70 to 100 ° C., from the viewpoints of toner fixing property, hot offset resistance and chargeability.

  The content of the wax having a polar group is 0.5 to 20% by weight, preferably 1 to 15% by weight, more preferably 3 to 15%, from the viewpoint of toner fixing property and hot offset resistance in the polyester. % By weight.

  The polyester for toner of the present invention is obtained by performing at least a part of the condensation polymerization reaction of an alcohol component and a carboxylic acid component used as raw material monomers in the presence of the wax having the polar group.

  Examples of the divalent alcohol component include polyoxyethylene (2.0) -2,2-bis (4-hydroxyphenyl) propane, polyoxyethylene (2.2) -2,2-bis (4-hydroxyphenyl) Formula (I) such as propane, polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, etc .:

(Wherein R is an alkylene group having 2 or 3 carbon atoms, x and y are positive numbers, and the sum of x and y is 1 to 16, preferably 1.5 to 5.0)
And an alkylene oxide adduct of bisphenol A, ethylene glycol, 1,2-propylene glycol, 1,4-butanediol, neopentyl glycol, polyethylene glycol, polypropylene glycol, hydrogenated bisphenol A, and the like.

  Among these, from the viewpoint of toner durability and chargeability, an alkylene oxide adduct of bisphenol A represented by the formula (I) is preferable. 70 mol% or more is preferable in an alcohol component, and, as for content of the alkylene oxide adduct of bisphenol A, 80 mol% or more is more preferable.

  Examples of the trihydric or higher polyhydric alcohol component include sorbitol, pentaerythritol, glycerin, trimethylolpropane and the like.

  Divalent carboxylic acid components include aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, and terephthalic acid; oxalic acid, malonic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, succinic acid, Aliphatic dicarboxylic acids such as succinic acid substituted with alkyl groups having 1 to 20 carbon atoms or alkenyl groups having 2 to 20 carbon atoms such as adipic acid, dodecenyl succinic acid, octyl succinic acid; anhydrides of these acids and their Alkyl (C1-C3) ester of an acid etc. are mentioned.

  Examples of the trivalent or higher polyvalent carboxylic acid component include 1,2,4-benzenetricarboxylic acid (trimellitic acid), 2,5,7-naphthalenetricarboxylic acid, pyromellitic acid and acid anhydrides thereof, lower alkyl ( Examples thereof include esters having 1 to 3 carbon atoms.

  In the polyester of the present invention, a trivalent or higher monomer is preferably used as one kind of raw material monomer. From the viewpoint of durability, the content of the trivalent or higher monomer, that is, the trivalent or higher polyhydric alcohol and the polyvalent carboxylic acid compound, preferably the trivalent or higher polyvalent carboxylic acid compound is 10 -40 mol% is preferable and 10-30 mol% is more preferable.

  Furthermore, from the viewpoint of molecular weight adjustment and the like, a monovalent alcohol or a monovalent carboxylic acid compound may be appropriately contained in each component as long as the effects of the present invention are not impaired.

  The polycondensation reaction between the alcohol component and the carboxylic acid component can be carried out in the same manner as in the case of producing a normal polyester except that at least a part thereof is carried out in the presence of wax. It is obtained by subjecting a raw material monomer comprising a component and a carboxylic acid component to condensation polymerization at 150 to 280 ° C. in the presence of a wax and in an inert gas atmosphere, if necessary, in the presence of an esterification catalyst, a polymerization inhibitor and the like. The addition timing of the wax is not particularly limited, and the wax may be added from the beginning of the condensation polymerization reaction or may be added during the reaction, but it is preferably added during the reaction from the viewpoint of toner productivity.

  The softening point of the polyester of the present invention is preferably from 90 to 160 ° C., more preferably from 100 to 150 ° C., from the viewpoint of toner fixability, durability and hot offset resistance. The glass transition point is preferably from 50 to 80 ° C., more preferably from 55 to 75 ° C., from the viewpoint of toner fixability and storage stability.

  The acid value of the polyester of the present invention is preferably from 3 to 40 mgKOH / g, more preferably from 5 to 30 mgKOH / g, from the viewpoint of chargeability of the toner.

  The volume average dispersion diameter of the wax having a polar group in the polyester is preferably 1 to 20 μm, and more preferably 1 to 15 μm, from the viewpoints of toner fixability, durability, and hot offset resistance. The dispersion diameter of the wax can be adjusted by the addition timing of the wax, the kind of raw material monomer, the stirring strength when polymerizing the raw material monomer, the cooling rate after polymerization, and the like. For example, as the wax is added at an earlier stage of polymerization, the dispersion diameter of the wax tends to be smaller.

  The toner of the present invention containing, as a binder resin, the polyester of the present invention in which a wax is dispersed with an appropriate particle size has excellent chargeability and hot offset resistance. Therefore, the toner of the present invention can be suitably used as a non-magnetic one-component developing toner and a non-magnetic two-component developing toner that require high durability.

  The toner of the present invention further includes a colorant, a charge control agent, a conductivity regulator, an extender pigment, a reinforcing filler such as a fibrous substance, an antioxidant, an anti-aging agent, a fluidity improver, and a cleaning property improver. Such additives may be appropriately contained.

  As the colorant, all of dyes and pigments used as toner colorants can be used, such as carbon black, phthalocyanine blue, permanent brown FG, brilliant first scarlet, pigment green B, rhodamine-B base, Solvent Red 49, Solvent Red 146, Solvent Blue 35, Quinacridone, Carmine 6B, Disazo Yellow and the like can be used alone or in combination of two or more. The toner of the present invention is a black toner, color Either toner or full color toner may be used. The content of the colorant is preferably 1 to 40 parts by weight and more preferably 3 to 10 parts by weight with respect to 100 parts by weight of the binder resin.

  Charge control agents include nigrosine dyes, triphenylmethane dyes containing tertiary amines as side chains, quaternary ammonium salt compounds, polyamine resins, imidazole derivatives and other positively chargeable charge control agents and metal-containing azo dyes, copper Examples include negatively chargeable charge control agents such as phthalocyanine dyes, metal complexes of alkyl derivatives of salicylic acid, and boron complexes of benzylic acid.

The toner production method may be any conventionally known method such as a kneading and pulverizing method, a phase inversion emulsification method, and a polymerization method. For example, in the case of a pulverized toner by a kneading and pulverizing method, the polyester of the present invention is included. Binder resin, colorant, charge control agent, etc. are uniformly mixed with a mixer such as a Henschel mixer, then melt-kneaded with a closed kneader, a single or twin screw extruder, an open roll kneader, etc., and cooled. , Pulverized and classified. Further, inorganic fine particles such as hydrophobic silica or resin fine particles may be externally added to the obtained toner surface. The weight average particle diameter (D ₄ ) of the toner is preferably 3 to 15 μm, and more preferably _{4 to 8} μm.

[Softening point of resin]
Using a Koka type flow tester (manufactured by Shimadzu Corporation, CFT-500), a 1 g sample was heated at a heating rate of 6 ° C./min, a load of 1.96 MPa was applied by a plunger, a diameter of 1 mm, A nozzle with a length of 1 mm is pushed out, and this draws a plunger drop amount (flow value) -temperature curve of the flow tester. When the height of the S-shaped curve is h, the temperature corresponding to h / 2 (sample) The temperature at which half of the effluent flowed out) is taken as the softening point.

[Glass transition point of resin and melting point of wax]
Using a differential scanning calorimeter (Seiko Denshi Kogyo Co., Ltd., DSC210), the sample was heated to 200 ° C., and the sample cooled to 0 ° C. at a temperature decrease rate of 10 ° C./min was measured at a temperature increase rate of 10 ° C./min. When wax is used as a sample, the maximum peak temperature is taken as the melting point. Further, when a resin is used as a sample, the glass transition point is defined as the temperature at the intersection of the base line extension below the maximum peak temperature and the tangential line showing the maximum slope from the peak rising portion to the peak apex.

[Acid value and hydroxyl value of resin and wax]
Measured according to the method of JIS K0070.

[Volume average dispersion diameter of wax]
A sample solution is prepared by weighing 0.5 g of resin into a 50 ml sample tube, adding 20 ml of tetrahydrofuran, placing it on a ball mill bed and stirring for 1 hour to sufficiently dissolve the resin. The obtained sample solution was diluted with tetrahydrofuran until the wax had a measured concentration, and the volume average dispersed particle size of the wax was measured with a Shimadzu laser diffraction particle size distribution analyzer “SALD-2000J” (manufactured by Shimadzu Corporation). .
In addition, when resin-insoluble matter is confirmed in the solution, the dropping of 1N potassium hydroxide (KOH) aqueous solution and ultrasonic irradiation are repeated until the insoluble matter disappears, and it is confirmed that there is no insoluble matter in the sample solution. Then, the above measurement is performed.

Examples 1 and 7 and Comparative Examples 2 and 3
The alcohol component shown in Table 1, carboxylic acid components other than fumaric acid and trimellitic anhydride, esterification catalyst, and wax were placed in a 5-liter four-necked flask equipped with a nitrogen introduction tube, a dehydration tube, a stirrer, and a thermocouple. The reaction was continued in a nitrogen atmosphere at 230 ° C. until the reaction rate reached 90%, and then reacted at 8.3 kPa for 1 hour. Thereafter, the mixture was cooled to 185 ° C., fumaric acid and a polymerization inhibitor were added, reacted to 210 ° C. by stepwise temperature increase, trimellitic anhydride was added, and after 1 hour of atmospheric pressure reaction, 26.7 kPa The reaction was carried out until the desired softening point was reached, to obtain a polyester. In the present invention, the reaction rate means a value of reaction water amount (mol) / theoretical water generation amount (mol) × 100.

Example 2
A polyester was obtained in the same manner as in Example 1 except that the wax was added together with trimellitic anhydride instead of at the start of polymerization.

Example 3
The alcohol component shown in Table 1, a carboxylic acid component other than trimellitic anhydride, and an esterification catalyst were placed in a 5-liter four-necked flask equipped with a nitrogen introduction tube, a dehydration tube, a stirrer, and a thermocouple, and under a nitrogen atmosphere The reaction was allowed to proceed at 230 ° C. until the reaction rate reached 90%, and then reacted at 8.3 kPa for 1 hour. Thereafter, it is cooled to 210 ° C., wax and trimellitic anhydride are added, reacted at normal pressure for 1 hour, reacted at 8.3 kPa for 1 hour, and then reaches a desired softening point at 200 kPa. The reaction was performed until polyester was obtained.

Example 4
The alcohol component, carboxylic acid component, esterification catalyst and wax shown in Table 1 were placed in a 5-liter four-necked flask equipped with a nitrogen introduction tube, a dehydration tube, a stirrer and a thermocouple, and at 230 ° C. under a nitrogen atmosphere. After reacting until the reaction rate reached 90%, the reaction was performed at 8.3 kPa until a desired softening point was reached, thereby obtaining a polyester.

Examples 5 and 6
Four 5-liter capacity equipped with alcohol components, carboxylic acid components other than trimellitic anhydride, esterification catalyst and wax shown in Table 1, equipped with nitrogen introduction tube, dehydration tube with rectifying column, stirrer and thermocouple Put in a neck flask, raise the temperature to 180 ° C., raise the temperature to 230 ° C. over 8 hours, react for 2 hours, cool to 200 ° C., add trimellitic anhydride, and reach the desired softening point The reaction was performed until polyester was obtained.

Comparative Example 1
A polyester was obtained in the same manner as in Example except that no wax was used.

  Table 1 shows the softening point, glass transition point, acid value, and volume average dispersion diameter of the waxes obtained in the examples and comparative examples.

The following commercially available products were used for waxes A to C in Table 1.
Wax A: “PARACOHOL-5300” (manufactured by Nippon Seiwa Co., Ltd.)
Hydroxyl value: 17 mg KOH / g, acid value: 1 mg KOH / g, melting point: 87.0 ° C
Wax B: “PARACOHOL-6110” (manufactured by Nippon Seiwa Co., Ltd.)
Hydroxyl value: 50 mgKOH / g, acid value: 4 mgKOH / g, melting point: 85.8 ° C
Wax C: “PARACOHOL-5003A” (manufactured by Nippon Seiwa Co., Ltd.)
Hydroxyl value: 32 mgKOH / g, acid value: 5 mgKOH / g, melting point: 74.6 ° C
Polyethylene wax: “FT-100” (manufactured by Nippon Seiwa Co., Ltd.)
Melting point: 98.0 ℃

Toner Production Example (1) Examples 1 to 7 and Comparative Examples 2 and 3
A raw material consisting of 100 parts by weight of polyester, 4 parts by weight of carbon black “MOGUL-L” (Cabot) and 1 part by weight of negatively chargeable charge control agent “Bontron S-34” (Orient Chemical Co., Ltd.) After thorough mixing, melt kneading is performed using a co-rotating twin-screw extruder with a heating temperature in the roll of 100 ° C., and the resulting mixture is cooled, coarsely pulverized, pulverized with a jet mill, classified, and volume A powder having an average particle size of 8.0 μm was obtained.
To 100 parts by weight of the obtained powder, 0.1 part by weight of hydrophobic silica “TS-530” (manufactured by Cabot, average particle size: 8 nm) is added as an external additive, and mixed with a Henschel mixer to prepare a toner. Obtained.

(2) Comparative Example 1
A toner was obtained in the same manner as in Example 1 except that 5 parts by weight of the same wax A as in Example 1 was used as a raw material.

Test Example (1) Hot-offset resistance In a commercially available full-color electrophotographic recording apparatus of a non-magnetic one-component development system, the fixing speed was set to 100 mm / sec, and the toner was mounted on the apparatus from which the oil coating apparatus was removed. The temperature of the heat roller in the fixing device is made variable, and the temperature is raised from 100 ° C. to 240 ° C., an image is printed every time the temperature is raised by 10 ° C., and the toner adheres to the surface of the heat roller at each temperature. Was observed with the naked eye. The temperature at which the toner adhered to the surface of the heat roller was defined as the hot offset occurrence temperature, and the hot offset resistance was evaluated according to the following evaluation criteria. The results are shown in Table 2.

〔Evaluation criteria〕
Hot offset generation temperature is ◎: 210 ° C or higher ○: 180 ° C or higher and lower than 210 ° C ×: Less than 180 ° C

(2) Chargeability 0.6 g of toner and 19.4 g of a silicone ferrite carrier (manufactured by Kanto Denka Kogyo Co., Ltd., average particle size: 90 μm) were mixed at a rotational speed of 250 r / min using a ball mill. The toner charge amount was measured using a “q / m meter” (manufactured by EPPING) after 60 seconds, 300 seconds, 600 seconds, 1200 seconds, and 3000 seconds from the start of mixing, and the following evaluation criteria The chargeability was evaluated according to The results are shown in Table 2.

〔Evaluation criteria〕
Maximum charge amount: ◎: 20 μC / g or more ○: 10 μC / g or more, less than 20 μC / g ×: Less than 10 μC / g

From the above results, it is clear that the toner containing the polyester of the example is excellent in both hot offset resistance and chargeability.
On the other hand, the following can be seen from the results of the comparative example.
(1) Comparative Example 1
Even when a wax having a polar group is used, although it is mixed with the wax after the production of the polyester, the hot offset resistance is good, but the chargeability is lowered. This is presumably due to poor wax dispersion.
(2) Comparative Example 2
Since the wax having a polar group is not used, the chargeability is lowered. This is presumably because additives such as carbon black are aggregated in the wax part when the toner is produced because the compatibility between the polyethylene wax and the polyester is low.
(3) Comparative Example 3
Since the content of the wax in the polyester is too large, the chargeability is lowered. This is presumably due to poor wax dispersion.

  The polyester for toner of the present invention is used as a binder resin for a toner used for developing a latent image formed in an electrophotographic method, an electrostatic recording method, an electrostatic printing method or the like.

Claims (5)

Formula (I):

(In the formula, R is an alkylene group having 2 or 3 carbon atoms, x and y are positive numbers, and the sum of x and y is 1 to 16)
An alcohol component an alkylene oxide adduct of bisphenol A comprising more than 70 mole% represented in at least a portion of the polycondensation reaction of a carboxylic acid component, carried out in the presence of a paraffin wax having a hydroxyl group A polyester for toner obtained by containing 0.5 to 20% by weight of the wax. Toner for polyester according to claim 1, wherein the sum of hydroxyl value and acid value of the paraffin wax having a water group is 5~150mgKOH / g. Claim 1 or 2 for toner polyester according volume average dispersion diameter of the wax is 1 to 20 [mu] m. The polyester for toner according to any one of claims 1 to 3 , wherein the softening point of the polyester is 90 to 160 ° C. Claim 1-4 toner containing the toner for polyester according to any one.