Binder resin for toners, toner, and method for producing same

Abstract

A binder resin for toner of the present invention comprising: a polyester resin (A) which contains a constitutional unit derived from isosorbide and has a softening temperature of higher than 120 C.; and a polyester resin (B) different from the polyester resin (A), wherein the binder resin for toner has a pulverizability index of 25 or more.

Claims

1. A binder resin, comprising: a polyester resin (A) comprising a constitutional unit derived from isosorbide and has a softening temperature of higher than 120 C.; and a polyester resin (B) different from the polyester resin (A), wherein the binder resin has a pulverizability index of 25 or more, a weight average molecular weight (Mw) of the polyester resin (B) is from 500 to 1,000,000, and a glass transition temperature of the polyester resin (B) is from 35 C. to 82 C.

2. The binder resin according to claim 1, wherein a ratio of the number of carbon atoms contained in a constitutional unit derived from isosorbide to the number of entire carbon atoms contained in the polyester resin (A) is from 0.1% to 30%.

3. The binder resin according to claim 1, wherein the polyester resin (A) is a polycondensate of a monomer mixture comprising either or both of a tri- or higher polycarboxylic acid and a trihydric or higher polyhydric alcohol in a range of from 0.1% to 80% by mole with respect to the total number of moles of entire acid components.

4. The binder resin according to claim 1, wherein a softening temperature of the polyester resin (B) is higher than 120 C.

5. The binder resin according to claim 4, wherein the softening temperature of the polyester resin (B) is from >120 C. to 165 C.

6. The binder resin according to claim 1, wherein a softening temperature of the polyester resin (B) is 120 C. or lower.

7. The binder resin according to claim 6, wherein the softening temperature of the polyester resin (B) is from 75 C. to 120 C.

8. The binder resin according to claim 1, wherein a ratio of the number of carbon atoms contained in a constitutional unit derived from isosorbide to the number of entire carbon atoms contained in the polyester resin (B) is less than 1%.

9. The binder resin according to claim 1, wherein a mass ratio of the polyester resin (A) to the polyester resin (B) is from 5:95 to 95:5.

10. A toner comprising the binder resin according to claim 1.

11. A method for producing the toner according to claim 10, the method comprising: melting and kneading a mixture comprising the polyester resin (A) and the polyester resin (B); and pulverizing a kneaded product thus obtained.

12. The binder resin according to claim 1, wherein the softening temperature of the polyester resin (A) is from 122 C. to 160 C.

13. The binder resin according to claim 1, wherein a glass transition temperature of the polyester resin (A) is from 40 C. to 82 C.

14. The binder resin according to claim 1, wherein an acid value of the polyester resin (A) is from 0.1 to 50 mg KOH/g.

15. The binder resin according to claim 1, wherein an acid value of the polyester resin (B) is from 0.1 to 50 mg KOH/g.

16. The binder resin according to claim 1, wherein a mass ratio of the polyester resin (A) to the polyester resin (B) is from 25:75 to 75:25.

17. The binder resin according to claim 1, wherein a mass ratio of the polyester resin (A) to the polyester resin (B) is from 40:60 to 60:40.

18. The binder resin according to claim 1, further comprising an additional binder resin other than the polyester resin (A) and the polyester resin (B), wherein a content of the additional binder resin is 25 parts by mass or less with respect to 100 parts by mass of the sum of the polyester resin (A) and the polyester resin (B).

19. The binder resin according to claim 1, further comprising an additional binder resin other than the polyester resin (A) and the polyester resin (B), wherein a content of the additional binder resin is 20 parts by mass or less with respect to 100 parts by mass of the sum of the polyester resin (A) and the polyester resin (B).

Description

EXAMPLES

(1) Hereinafter, the invention will be described in more detail with reference to Examples, but the invention is not limited by the following Examples.

(2) The evaluation methods used in each example to be described later are as follows.

(3) <Method of Evaluating Physical Properties of Polyester Resin>

(4) (Glass Transition Temperature (Tg))

(5) The temperature at the intersection point between the baseline on the low temperature side of the chart when a polyester resin was filled in an aluminum cell by 100.5 mg and heated on a hot plate at 100 C. for 10 minutes, the cell was brought into close contact with dry ice and rapidly cooled to 0 C. or lower, and the measurement was then conducted at a rate of temperature increase of 5 C./min by using a differential scanning calorimeter DSC-60 manufactured by Shimadzu Corporation and the tangent of the endothermic curve in the vicinity of the glass transition temperature was determined and the temperature was taken as Tg.

(6) (Softening Temperature)

(7) The measurement is conducted by using a polyester resin as a measurement sample at a load of 294 N (30 kgf) while constantly increasing the temperature at a rate of temperature increase of 3 C./min by using a nozzle of 1 mm 10 mm and a flow tester CFT-500 manufactured by Shimadzu Corporation. The measurement sample is prepared by 1.0 g. The temperature at which the measurement sample was discharged by 4 mm from the baseline was determined, and the temperature was taken as the softening temperature.

(8) (Acid Value)

(9) A polyester resin was precisely weighed (A (g)) by about 0.2 g and introduced into a side-arm Erlenmeyer flask, 20 mL of benzyl alcohol was added thereto, and the polyester resin was heated by using a heater at 230 C. for 15 minutes in a nitrogen atmosphere to be dissolved. The solution was cooled to room temperature, 20 mL of chloroform and a few drops of a phenolphthalein solution were then added thereto, and the titration was conducted with a 0.02 normal KOH benzyl alcohol solution (titre=B (mL), potency of KOH solution=p). The blank measurement was conducted in the same manner (titre=C (mL)), and the acid value of the polyester resin was calculated according to the following equation.
Acid value (mg KOH/g)=(BC)0.0256.11pA

(10) (Average Molecular Weight)

(11) An elution curve was obtained by gel permeation chromatography under the following conditions, and the average molecular weight (Mw, Mn, and Mp) and the molecular weight dispersity (Mw/Mn) were determined in terms of standard polystyrene from the retention time corresponding to the peak value on the elution curve thus obtained.

(12) Apparatus: HLC 8020 manufactured by TOSOH CORPORATION.

(13) Column: three columns of TSKgel (registered trademark) GMHXL (column size: 7.8 mm (inner diameter)30.0 cm (length)) manufactured by TOSOH CORPORATION connected in series.

(14) Oven temperature: 40 C.

(15) Eluent: tetrahydrofuran (THF).

(16) Sample concentration: 4 mg/10 mL.

(17) Filtration conditions: sample solution is filtered through 0.45 m Teflon (registered trademark) membrane filter.

(18) Flow velocity: 1 mL/min.

(19) Injection volume: 0.1 mL.

(20) Detector: differential refractive index (RI) detector.

(21) (Gel Fraction)

(22) A polyester resin was weighed (D (g)) by about 0.5 g and introduced into a 100 mL Erlenmeyer flask, 50 mL of THF was added thereto, the polyester resin was dissolved by immersing the flask in a water bath set at 70 C. for 3 hours, thereby preparing a THF solution. Meanwhile, Celite 545 was tightly filled in a glass filter 1GP100 up to 6 to 7 portions, dried in a dryer at 105 C. for 3 hours or longer, and weighed (E (g)).

(23) Subsequently, the THF solution in which the polyester resin was dissolved was transferred into this dried glass filter and subjected to suction filtration. All the contents remaining on the wall of the Erlenmeyer flask were transferred into the glass filter by using acetone, acetone was allowed to flow in the glass filter to drop the soluble matter into the suction bottle, suction was continuously conducted so that the solvent did not remain in the filter, and the residue was then dried in a vacuum dryer at 80 C. for 3 hours or longer and weighed (F (g)). The THF-insoluble matter (% by mass) was calculated by the following equation, and this value was taken as the gel fraction.
THF-insoluble matter (% by mass)=(FE)/D100

(24) <Pulverizability Index of Binder Resin for Toner>

(25) A kneaded product of a binder resin was obtained in the same manner as in the production of a toner in Examples and Comparative Examples to be described later except that components other than the polyester resin (binder resin) were not blended, the kneaded product thus obtained was pulverized and sieved, and the particles which passed through 16 mesh but did not pass through 22 mesh were obtained. This classified powder was precisely weighed by 10.00 g (G (g)), pulverized for 10 minutes by using a pulverizer Trio Blender (manufactured by Trio Science Co.), and then sieved through a sieve with 30 mesh. The mass (H (g)) of the particles which passed through a sieve with 30 mesh (mesh opening: 0.5 mm) was precisely weighed, and the passage rate (%) was calculated by the following equation. This operation was conducted three times, and the average value thereof was taken as the pulverizability index of the binder resin for toner in each example.
Passage rate (%)=(H/G)100

(26) (Particle Diameter and Particle Size Distribution of Particles)

(27) The particle diameter and particle size distribution of the particles were measured by using a laser diffraction type particle diameter measuring instrument (trade name: LA-920, manufactured by HORIBA, Ltd.). According to the operation manual of the measuring instrument, a flow cell for measurement was used, distilled water was added into the cell, the relative refractive index was selected and set to 1.20, and the adjustment of the optical axis, fine adjustment of the optical axis, and blank measurement were conducted by setting the particle diameter standard to a volume standard. Next, an aqueous dispersion of particles was added into the cell so as to have a concentration at which the transmittance was in a range of from 70% to 90%, an ultrasonic treatment was conducted for 1 minute at an intensity of 5, and the particle size distribution of the particles was measured. The particle diameter (median diameter) corresponding to a cumulative percentage of 50% on the volume distribution standard in the particle size distribution thus measured was taken as the average particle diameter.

(28) <Method of Evaluating Toner>

(29) (Storage Stability)

(30) A toner was weighed by about 5 g and introduced into a sample bottle, this was left to stand for about 24 hours in a dryer maintained at 45 C., and the degree of aggregation of the toner was evaluated and used as an index of storage stability (blocking resistance). The evaluation criteria were as follows.

(31) (Significantly favorable): toner is dispersed by only turning sample bottle upside down.

(32) (Favorable): toner is dispersed by turning sample bottle upside down and tapping it 2 or 3 times.

(33) (Usable): toner is dispersed by turning sample bottle upside down and tapping it 4 or 5 times.

(34) x (Inferior): toner is not dispersed by turning sample bottle upside down and tapping it 5 times.

(35) (Low Temperature Fixability)

(36) Printing was conducted by using a printer (SPEEDIA (registered trademark) N4-614 manufactured by CASIO COMPUTER CO., LTD.) which had a fixing roller not coated with silicone oil, was set to have a roller speed of 100 mm/sec, and was capable of changing the temperature, and the low temperature fixability was evaluated. Specifically, the final temperature at which the toner started to be fixed on the paper when the toner was fixed on paper was taken as the fixing temperature, and the low temperature fixability was judged according to the following criteria.

(37) (Significantly favorable): fixing temperature is lower than 140 C.

(38) (Favorable): fixing temperature is 140 C. or higher and lower than 150 C.

(39) (Usable): fixing temperature is 150 C. or higher and lower than 160 C.

(40) x (Inferior): fixing temperature is 160 C. or higher.

(41) (Hot Offset Resistance)

(42) By using a printer which had a fixing roller not coated with silicone oil, was set to have a roller speed of 30 mm/sec, and was capable of changing the roller temperature, a solid image of 4.5 cm in length15 cm in width was printed as a test pattern at a toner density of 0.5 mg/cm.sup.2 and a roller temperature of every 5 C. At this time, the lowest temperature at which the toner was transferred to the fixing roller by the hot offset phenomenon at the time of fixing was determined as the hot offset occurring temperature, and the hot offset resistance (non-offset property) was judged according to the following criteria.

(43) (Significantly favorable): hot offset occurring temperature is 200 C. or higher.

(44) (Favorable): hot offset occurring temperature is 180 C. or higher and lower than 200 C.

(45) (Usable): hot offset occurring temperature is 170 C. or higher and lower than 180 C.

(46) x (Inferior): hot offset occurring temperature is lower than 170 C.

(47) (Durability)

(48) After 30,000 sheets of test pattern were printed by the same method as in the evaluation of hot offset resistance, the durability was evaluated by adhesion to the blade and fogging of the printed surface according to the following criteria.

(49) (Significantly favorable): adhesion to blade and fogging are not observed.

(50) (Favorable): adhesion to blade and fogging are significantly slightly observed.

(51) (Usable): adhesion to blade and fogging are slightly observed but can be improved by additives and the like.

(52) x (Inferior): adhesion to blade and fogging are greatly observed.

Production Examples 1 to 9: Production of Polyester Resin

(53) The polycarboxylic acids and polyhydric alcohols presented in Table 1 and titanium alkoxide to be 500 ppm with respect to the entire acid components were introduced into a reaction vessel equipped with a distillation column.

(54) Subsequently, the number of revolutions of the stirring blade in the reaction vessel was maintained at 120 rpm, the temperature was started to increase, heating was conducted so that the temperature in the reaction system reached 265 C., and the esterification reaction was conducted while maintaining this temperature. After the esterification reaction was completed and discharge of water from the reaction system was not observed any longer, the temperature in the reaction system was lowered and maintained at 245 C., the pressure in the reaction vessel was lowered over about 40 minutes, the degree of vacuum was set to 133 Pa, and the condensation reaction was conducted while discharging the diol component from the reaction system.

(55) The viscosity of the reaction system increased as the reaction proceeded, the degree of vacuum was increased as the viscosity increased, and the condensation reaction was conducted until the torque of the stirring blade reached a value indicating the desired softening temperature. Thereafter, the stirring was stopped at the time point at which the predetermined torque was indicated, the reaction system was returned to normal pressure, and the reaction product was taken out from the reaction vessel by pressurizing with nitrogen, thereby obtaining polyester resins A to I. The physical properties of the polyester resins A to I thus obtained are presented in Table 1.

(56) Incidentally, the composition of the polycarboxylic acids and polyhydric alcohols introduced presented in Table 1 is parts by mole of each monomer component when the total number of moles of the entire acid components (all the polycarboxylic acids) is taken as 100 parts by mole.

(57) As the bisphenol A PO adduct, polyoxypropylene(2.3)-2,2-bis(4-hydroxyphenyl)propane was used.

(58) The isosorbide-derived carbon atom ratio is the ratio (%) of the number of carbon atoms contained in the constitutional unit derived from isosorbide to the number of entire carbon atoms contained in the polyester resin.

(59) The isosorbide-derived carbon atom ratio and the content of the trivalent or higher monomer component with respect to the total number of moles of the entire acid components were respectively calculated from the composition introduced.

(60) TABLE-US-00001 TABLE 1 Produc- Produc- Produc- Produc- Produc- Produc- Produc- Produc- Produc- tion tion tion tion tion tion tion tion tion Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- ple 1 ple 2 ple 3 ple 4 ple 5 ple 6 ple 7 ple 8 ple 9 Polyester resin A B C D E F G H I Composition Terephthalic acid Parts by mole 98 100 70 94 94 70 100 94 100 introduced Anhydrous trimellitic Parts by mole 2 0 30 6 6 30 0 6 0 acid Bisphenol A PO adduct Parts by mole 45 45 95 118 65 95 50 65 90 Ethylene glycol Parts by mole 20 18 40 0 55 60 63 55 28 Trimethylolpropane Parts by mole 0 10 0 0 0 0 10 0 0 Isosorbide Parts by mole 40 40 20 2 20 0 0 0 0 Isosorbide-derived carbon atom ratio % 11.6 11.3 3.9 0.4 4.9 0 0 0 0 Content of trivalent or higher monomer mol % 2 10 30 6 6 30 10 6 0 component with respect to total number of moles of entire acid components Physical Tg C. 89 80 64 65 66 58 63 72 50 properties Softening temperature C. 142 136 143 122 112 135 155 132 90 Acid value Mg KOH/g 14 7 3.4 2.5 12 2.5 7 2.7 7.5 Mn 3000 2500 1400 2700 1500 1400 3800 2300 1500 Mw 9700 16000 39000 19000 5100 44000 130000 25000 4300 Mp 6800 4400 2000 6700 3800 2000 6800 8000 3800 Gel fraction wt % 4 8 23 0 0 17 12 2 0

Example 1

(61) A mixture was obtained by mixing 89 parts by mass of a polyester resin, 7 parts by mass of a quinacridone pigment (HOSTAPARM PINK E, C.I. No. Pigment Red 122 manufactured by Clariant), 3 parts by mass of carnauba wax No. 1 (manufactured by TOYO ADL CORPORATION), and 1 part by mass of a negatively chargeable charge control agent (LR-147 manufactured by Japan Carlit Co., Ltd.) by using a Henschel mixer for 5 minutes. As the polyester resin, the polyester resin A and polyester resin F produced above were used in a mass ratio of A:F=50:50. In other words, the ratio of the polyester resin A to the total mass of the binder resin for toner was set to 50% by mass, and the ratio of the polyester resin F to 50% by mass.

(62) Subsequently, the mixture thus obtained was melted and kneaded by using a twin screw extruder (PCM-29, manufactured by Ikegai Corp.). The melting and kneading was conducted by setting the external temperature of the barrel 1 to 30 C., the barrel 2 to 60 C., the barrel 3 to 100 C., and the barrel 4 onwards to 120 C. After kneading, the resultant was cooled, thereby obtaining a toner lump. The toner lump thus obtained was finely pulverized to have a particle diameter of 10 m or less by using a jet mill of a fine pulverizer, thereby obtaining a pulverized product. The pulverized product thus obtained was arranged to have an average particle diameter of 4 m or more and 9 m or less by excluding fine particles having a particle diameter of 3 m or less by using a classifier. To 100 parts by mass of the fine powder thus obtained, 0.25 part by mass of silica (R-972 manufactured by EVONIK) was added and attached by mixing them together by using a Henschel mixer, thereby obtaining a toner.

(63) The toner thus obtained was evaluated by the evaluation methods described above. The results are presented in Table 2.

Examples 2 to 6 and Comparative Examples 1 to 4

(64) Toners were obtained by the same method as in Example 1 except that the composition (the kind of the polyester resin and the ratio (% by mass) thereof to the total mass) of the binder resin for toner was changed as presented in Tables 2 and 3.

(65) The toner thus obtained was evaluated by the evaluation methods described above. The results are presented in Tables 2 and 3. In Tables 2 and 3, TMA represents anhydrous trimellitic acid and TMP represents trimethylolpropane.

(66) TABLE-US-00002 TABLE 2 Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Binder resin Polyester resin (A) A 50 50 50 for toner (wt %) B 50 C 50 D 50 Polyester resin (B) E (wt %) F 50 50 50 G 50 H 50 I 50 Pulverizability index 57 43 38 71 40 88 Properties of Isosorbide-derived carbon atom ratio (%) 11.6 11.6 11.6 11.3 0.4 3.9 polyester Trivalent or higher Kind TMA TMA TMA TMP TMA TMA resin (A) monomer component Content (mol %) 2 2 2 10 6 30 Properties of Softening temperature 135 155 132 135 135 90 polyester ( C.) resin (B) Properties Storage stability of toner Low temperature fixability Hot offset resistance Durability

(67) TABLE-US-00003 TABLE 3 Comparative Comparative Comparative Comparative Comparative Comparative Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Binder resin Polyester resin (A) A 100 for toner (wt %) B C D Polyester resin (B) E 50 50 (wt %) F 50 50 50 100 G 50 H I 50 50 Pulverizability index 45 92 22 18 41 24 Properties of Isosorbide-derived carbon atom ratio (%) 11.6 polyester Trivalent or higher Kind TMA resin (A) monomer component Content (mol %) 2 Properties of Softening temperature 112, 135 112, 90 135, 155 135, 90 135 polyester ( C.) resin (B) Properties of Storage stability toner Low temperature fixabilit X Hot offset resistance X Durability X X X

(68) As presented in the results, the binder resins for toner used in the toners of Examples 1 to 6 had a pulverizability index of 25 or more and exhibited excellent pulverizability. In addition, the toners of Examples 1 to 6 exhibited excellent storage stability, low temperature fixability, hot offset resistance, and durability.

(69) On the contrary, the toners of Comparative Examples 1 and 2 exhibited poor durability since the polyester resin E which contained a constitutional unit derived from isosorbide and had a softening temperature of 120 C. or lower was used therein.

(70) The binder resins for toner used in the toners of Comparative Examples 3 and 4 exhibited poor pulverizability since polyester resins which both did not contain a constitutional unit derived from isosorbide were combined therein.

(71) The toner of Comparative Example 5 exhibited poor durability since a polyester resin A which contained contain a constitutional unit derived from isosorbide and had a softening temperature of higher than 120 C. was singly used therein.

(72) The binder resin for toner used in the toner of Comparative Example 6 exhibited poor pulverizability since the polyester resin F which did not contain a constitutional unit derived from isosorbide was singly used therein.

INDUSTRIAL APPLICABILITY

(73) The binder resin for toner of the invention is used in the production of a toner. According to the binder resin for toner of the invention, a toner exhibiting excellent storage stability, low temperature fixability, non-offset property, and durability can be obtained. In addition, it is possible to favorably pulverize the kneaded product and to enhance the productivity of toner in the case of producing a toner through a step of melting and kneading a material for toner such as a binder resin for toner and pulverizing the kneaded product thus obtained.

(74) The toner of the invention can be used in development of an electrostatic image or a magnetic latent image in an electrophotographic method, an electrostatic recording method, an electrostatic printing method, or the like.