Toner binder and toner

Abstract

An object of the present invention is to provide a toner binder and a toner that maintains offset resistance while having high gloss and that is excellent in low-temperature fixability, grindability, image strength, and heat-resistant storage stability. The toner binder of the present invention is a toner binder containing a non-linear polyester modified resin (A), wherein the non-linear polyester modified resin (A) is a modified resin having one or more carbon-carbon bonds crosslinking polyesters, and the toner binder has a loss tangent tan of 2 to 20 in the entire temperature range of 110 C. to 130 C.

Claims

1. A toner binder comprising: a non-linear polyester modified resin (A), wherein the non-linear polyester modified resin (A) is a modified resin having one or more carbon-carbon bonds crosslinking polyesters, wherein the toner binder has a loss tangent tan of 2 to 20 in the entire temperature range of 110 C. to 130 C., wherein the polyester comprises a polyester (A1) having carbon-carbon double bonds, and the polyester (A1) having carbon-carbon double bonds has a glass transition temperature Tg.sub.A1 of 35 C. to 43 C.

2. The toner binder according to claim 1, wherein the polyester (A1) having carbon-carbon double bonds contains an unsaturated carboxylic acid component (y) and/or an unsaturated alcohol component (z) as a raw material.

3. The toner binder according to claim 1, wherein the toner binder has a double bond equivalent of 0.50 mmol/g or less.

4. The toner binder according to claim 1, wherein the polyester (A1) having carbon-carbon double bonds has a double bond equivalent of 0.02 to 2.00 mmol/g.

5. The toner binder according to claim 1, wherein at least one of the carbon-carbon bonds is a carbon-carbon bond formed by mutually crosslinking carbon-carbon double bonds derived from the polyester (A1) having carbon-carbon double bonds.

6. The toner binder according to claim 1, wherein the polyester (A1) having carbon-carbon double bonds has a peak top molecular weight Mp of 2,000 to 30,000.

7. The toner binder according to claim 1, further comprising a polyester (B) containing a saturated carboxylic acid component and a saturated alcohol component as raw materials.

8. The toner binder according to claim 7, wherein the polyester (A1) having carbon-carbon double bonds and the polyester (B) are contained at a weight ratio (A1)/(B) of 5/95 to 50/50.

9. The toner binder according to claim 7, wherein the non-linear polyester modified resin (A) is a modified resin produced by mutually crosslinking carbon-carbon double bonds derived from the polyester (A1) having carbon-carbon double bonds in a state where the polyester (A1) having carbon-carbon double bonds and the polyester (B) are mixed together.

10. The toner binder according to claim 7, wherein the non-linear polyester modified resin (A) is a modified resin produced by mutually crosslinking carbon-carbon double bonds derived from the polyester (A1) having carbon-carbon double bonds using a radical reaction initiator (c) in a state where the polyester (A1) having carbon-carbon double bonds and the polyester (B) are mixed together.

11. The toner binder according to claim 1, wherein the toner binder has a storage modulus (G) at 120 C. of 30 to 35,000 Pa and a loss modulus (G) at 120 C. of 60 to 70,000 Pa.

12. The toner binder according to claim 1, further comprising tetrahydrofuran (THF) insolubles, wherein the amount of the tetrahydrofuran (THF) insolubles in the toner binder is 20% by weight or less.

13. The toner binder according to claim 1, further comprising a crystalline resin (C) other than the polyester (A1) having carbon-carbon double bonds and a polyester (B) containing a saturated carboxylic acid component and a saturated alcohol component as raw materials.

14. The toner binder according to claim 1, wherein the toner binder has at least one inflexion point indicating a glass transition temperature Tg.sub.T in a temperature range of 20 C. to 80 C. in a chart obtained by differential scanning calorimetry (DSC) using the toner binder.

15. A toner comprising: the toner binder according to claim 1; and a colorant.

Description

EXAMPLES

(1) The present invention is further described below with reference to examples and comparative examples, but the present invention is not limited thereto. Hereinafter, part(s) means part(s) by weight unless otherwise specified.

[Production of Polyester (A1-1)]

(2) A reaction vessel equipped with a condenser, a stirrer, and a nitrogen inlet was charged with 737 parts (100.0% by mole) of a bisphenol A-EO (2 mol) adduct, 153 parts (42.0% by mole) of terephthalic acid, 164 parts (51.2% by mole) of adipic acid, 17 parts (6.8% by mole) of fumaric acid, 2.5 parts of titanium diisopropoxy bistriethanolaminate as a condensation catalyst, and 5 parts of tert-butyl catechol as a polymerization inhibitor. The mixture was allowed to react at 180 C. for four hours under a nitrogen stream while generated water was removed. The reaction was continued for additional 10 hours under a reduced pressure of 0.5 to 2.5 kPa. Then, the reaction product was taken out. Thus, the polyester (A1-1) was obtained.

(3) The double bond equivalent of the polyester (A1-1) was 0.15 mmol/g, Tg.sub.A1 was 39 C., and the peak top molecular weight was 18,400.

[Production of Polyesters (A1-2) to (A1-18)]

(4) The polyesters (A1-2) to (A1-18) were obtained by a reaction in the same manner as in Production Example 1, except that in each production example, a reaction vessel equipped with a condenser, a stirrer, and a nitrogen inlet was charged with the alcohol components and the carboxylic acid components according to Table 1. Table 1 shows the double bond equivalent, Tg.sub.A1, and the peak top molecular weight of each of the polyesters (A1-2) to (A1-18) obtained.

(5) TABLE-US-00001 TABLE 1 Production Production Production Production Production Production Production Production Production Production Production Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6 Ex. 7 Ex. 8 Ex. 9 Ex. 10 Ex. 11 Polyester (A1) (A1-1) (A1-2) (A1-3) (A1-4) (A1-5) (A1-6) (A1-7) (A1-8) (A1-9) (A1-10) (A1-11) Composition Saturated alcohol Bisphenol A-EO (2.0 mol) adduct 737 748 753 721 761 (parts by weight) component (x) 3-Methyl-1 5-pentanediol 533 559 Trimethylolpropane 17 Bisphenol A-PO (2.0 mol) adduct 749 767 712 772 Unsaturated Fumaric acid 17 26 27 26 carboxylic acid Maleic anhydride 14 21 21 component (y) Acrylic acid 16 Methacrylic acid 19 Unsaturated Oleyl alcohol 54 alcohol component 2-Hydroxyethyl methacrylate 28 (z) Saturated Terephthalic acid 153 144 146 139 145 144 155 551 577 carboxylic acid Adipic acid 164 155 157 149 156 155 167 43 45 287 274 component (w) Trimellitic anhydride 24 Properties Double bond equivalent (mmol/g) 0.15 0.22 0.14 0.22 0.23 0.20 0.22 0.22 0.23 0.22 0.21 Glass transition temperature (TgA1) ( C.) 39 38 40 32 30 24 26 6 9 20 20 Peak top molecular weight 18,400 13,900 18,100 9,400 8,800 9,300 8,400 14,100 13,800 13,000 12,000 Comparative Comparative Production Production Production Production Production Production Production Production Production Ex. 12 Ex. 13 Ex. 14 Ex. 15 Ex. 16 Ex. 17 Ex. 18 Ex. 1 Ex. 2 Polyester (A1) (A1-12) (A1-13) (A1-14) (A1-15) (A1-16) (A1-17) (A1-18) (A1-1) (A1-2) Composition Saturated alcohol Bisphenol A-EO (2.0 mol) adduct 748 769 762 738 739 (parts by weight) component (x) 3-Methyl-1 5-pentanediol 61 Trimethylolpropane 13 13 13 20 Bisphenol A-PO (2.0 mol) adduct 770 771 604 679 Unsaturated Fumaric acid 26 26 40 36 16 carboxylic acid Maleic anhydride 21 20 component (y) Acrylic acid Methacrylic acid 19 Unsaturated Oleyl alcohol alcohol component 2-Hydroxyethyl methacrylate (z) Saturated Terephthalic acid 73 64 137 118 288 260 carboxylic acid Adipic acid 289 262 273 226 195 147 127 65 component (w) Trimellitic anhydride 16 17 15 15 34 99 Properties Double bond equivalent (mmol/g) 0.22 0.22 0.22 0.22 0.21 0.34 0.31 0 0.14 Glass transition temperature (TgA1) ( C.) 17 20 15 27 31 37 40 15 91 Peak top molecular weight 11,300 11,900 10,700 12,200 11,800 10,600 11,300 7,500 8,500

[Production of Polyester (A1-1)]

(6) The polyester (A1-1) was obtained by a reaction in the same manner as in Production Example 1, except that a reaction vessel equipped with a condenser, a stirrer, and a nitrogen inlet was charged with the alcohol component and the carboxylic acid component according to Table 1.

(7) The polyester (A1-1) does not contain carbon-carbon double bonds.

[Production of Polyester (A1-2)]

(8) The polyester (A1-2) was obtained by a reaction in the same manner as in Production Example 1, except that a reaction vessel equipped with a condenser, a stirrer, and a nitrogen inlet was charged with the alcohol component and the carboxylic acid component according to Table 1. Table 1 shows Tg.sub.A1 and the peak top molecular weight.

[Production of Polyester (B-1)]

(9) A reaction vessel equipped with a condenser, a stirrer, and a nitrogen inlet was charged with 746 parts (100.0% by mole) of a bisphenol A-PO (2 mol) adduct, 262 parts (84.1% by mole) of terephthalic acid, 19 parts (6.9% by mole) of adipic acid, and 0.6 parts of titanium diisopropoxy bistriethanolaminate as a condensation catalyst. The mixture was allowed to react at 220 C. for four hours under a nitrogen stream while generated water was removed. The reaction was continued for additional 10 hours under reduced pressure of 0.5 to 2.5 kPa. Then, the temperature was cooled to 180 C., and 32 parts (9.0% by mole) of trimellitic anhydride was added. After the reaction in a sealed vessel for one hour under normal pressure, the reaction product was taken out. Thus, the polyester (B-1) was obtained. The polyester (B-1) does not contain carbon-carbon double bonds.

[Production of Polyesters (B-2) to (B-8)]

(10) The polyesters (B-2) to (B-8) were obtained by a reaction in the same manner as in Production Example 19, except that in each production example, a reaction vessel equipped with a condenser, a stirrer, and a nitrogen inlet was charged with the alcohol components and the carboxylic acid components according to Table 2.

(11) The polyesters (B-2) to (B-8) do not contain carbon-carbon double bonds.

(12) TABLE-US-00002 TABLE 2 Production Production Production Production Production Production Production Production Ex. 19 Ex. 20 Ex. 21 Ex. 22 Ex. 23 Ex. 24 Ex. 25 Ex. 26 Polyester (B) (B-1) (B-2) (B-3) (B-4) (B-5) (B-6) (B-7) (B-8) Composition Alcohol Bisphenol A-PO 746 747 583 221 397 386 388 391 (parts by component (2.0 mol) adduct weight) Bisphenol A-PO 182 555 (3.0 mol) adduct Bisphenol A-EO 373 363 365 367 (2.0 mol) adduct Carboxylic Terephthalic acid 262 249 283 268 198 273 269 190 acid Trimellitic anhydride 32 32 11 12 29 34 29 34 component Adipic acid 19 31 57 75

[Production of Crystalline Resin (C-1)]

(13) A reaction vessel equipped with a condenser, a stirrer, and a nitrogen inlet was charged with 716 parts of dodecanedioic acid, 394 parts of 1,6-hexane diol, and 0.5 parts of tetrabutoxy titanate as a condensation catalyst. The mixture was allowed to react at 170 C. for eight hours under a nitrogen stream while generated water was removed. Then, the reaction was continued for additional four hours under a nitrogen stream while generated water was removed as the temperature was gradually increased up to 220 C. Further, the reaction was continued under reduced pressure of 0.5 to 2.5 kPa, and the reaction product was taken out when the acid value reached 0.5 or lower. Thus, the crystalline resin (C-1) was obtained. The softening temperature of the crystalline resin (C-1) was 78 C. and the melting point thereof was 72 C. The softening temperature/melting point ratio was 1.08. A resin with such properties is sharply softened by heat, and is thus a crystalline resin.

[Production of Toner Binder (D-1)]

(14) A mixture of 30 parts of the polyester (A1-1) and 70 parts of the polyester (B-1) was fed into a twin screw kneader (S5KRC kneader available from Kurimoto, Ltd.) at 10 kg/hour, and at the same time, 1.0 part of t-butyl peroxybenzoate (c-1) as the radical reaction initiator (c) was fed thereinto at 0.10 kg/hour to carry out a crosslinking reaction by kneading and extrusion at 160 C. for 15 minutes. The resultant product was cooled. Thus, the toner binder (D-1) of the present invention was obtained.

[Production of Toner Binders (D-2) to (D-21)]

(15) In each example, a mixture of the polyester (A1), the polyester (B), and the crystalline resin (C) in parts by weight according to Table 3 was fed into a twin screw kneader in the same manner as is the case with Example 1, and at the same time, the radical reaction initiator (c) was fed thereinto to carry out a crosslinking reaction in the same manner as in Example 1. Thus, the toner binders (D-2) to (D-21) of the present invention were obtained.

(16) The radical reaction initiators (c) in Table 3 are as follows.

(17) (c-1): t-Butyl peroxybenzoate

(18) (c-2): di-t-Butyl peroxide

(19) (c-3): t-Butylperoxy isopropyl monocarbonate

(20) TABLE-US-00003 TABLE 3 Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6 Ex. 7 Ex. 8 Ex. 9 Ex. 10 Ex. 11 Ex. 12 Ex. 13 Toner binder (D) (D-1) (D-2) (D-3) (D-4) (D-5) (D-6) (D-7) (D-8) (D-9) (D-10) (D-11) (D-12) (D-13) Com- Non- Polyester (A1-1) 30 30 ponents linear (A1) (A1-2) 20 (parts poly- (A1-3) 30 by ester (A1-4) 20 weight) resin (A1-5) 20 (A) (A1-6) 20 (A1-7) 20 (A1-8) 20 (A1-9) 20 (A1-10) 20 (A1-11) 20 (A1-12) 23 (A1-13) (A1-14) (A1-15) (A1-16) (A1-17) (A1-18) (A1-1) (A1-2) Radical (c-1) 1.0 1.0 1.0 1.0 1.0 2.0 2.0 reaction (c-2) 1.0 1.0 1.0 1.0 1.0 initiator (c-3) 2.0 (c) Polyester (B) (B-1) 70 70 70 (B-2) 80 80 80 80 80 (B-3) 80 80 (B-4) 80 80 (B-5) 77 (B-6) (B-7) (B-8) Crystalline (C-1) 10 resin (C) Weight ratio (A1)/(B) 30/70 30/70 20/80 30/70 20/80 20/80 20/80 20/80 20/80 20/80 20/80 20/80 23/77 Prop- Glass transition 57 54 55 58 56 54 52 53 45 41 40 40 40 erties temperature (TgT) tan at 110 C. 2.3 2.5 5.1 2.3 5.0 3.9 4.8 4.2 3.3 3.4 8.8 10.1 5.5 tan at 120 C. 2.5 2.7 6.2 2.4 5.9 4.6 5.2 4.7 3.4 3.5 12.5 11.1 7.5 tan at 130 C. 2.7 3.0 7.2 2.6 6.4 4.8 5.8 5.1 3.5 3.5 10.8 12.4 9.5 Double bond 0.0 0.0 0.0 0.0 0.0 0.0 0.1 0.0 0.1 0.0 0.0 0.0 0.0 equivalent (mM/g) (G) at 120 C. (Pa) 1,560 710 140 1,620 150 200 170 185 300 270 30 35 46 (G) at 120 C. (Pa) 3,850 1,920 870 3,900 890 920 880 870 1,010 950 375 390 345 THF insolubles (%) 4 3 3 4 6 12 3 10 4 4 3 3 2 Com. Com. Com. Ex. 14 Ex. 15 Ex. 16 Ex. 17 Ex. 18 Ex. 19 Ex. 20 Ex. 21 Ex. 1 Ex. 20 Ex. 3 Toner binder (D) (D-14) (D-15) (D-16) (D-17) (D-18) (D-19) (D-20) (D-21) (D-1) (D-2) (D-3) Com- Non- Polyester (A1-1) ponents linear (A1) (A1-2) (parts by polyester (A1-3) weight) resin (A) (A1-4) (A1-5) (A1-6) (A1-7) (A1-8) (A1-9) (A1-10) (A1-11) (A1-12) (A1-13) 23 (A1-14) 23 (A1-15) 23 23 23 (A1-16) 23 23 (A1-17) 15 (A1-18) 15 (A1-1) 30 (A1-2) 30 Radical (c-1) 1.0 1.0 1.0 reaction (c-2) 1.0 1.0 1.0 1.0 initiator (c-3) 2.0 2.0 1.0 2.0 (c) Polyester (B) (B-1) 70 70 (B-2) (B-3) (B-4) (B-5) 77 77 (B-6) 77 77 77 77 (B-7) 85 85 (B-8) 77 Crystalline resin (C) (C-1) 5 5 5 Weight ratio (A1)/(B) 23/77 23/77 23/77 23/77 23/77 23/77 15/85 15/85 30/70 30/70 23/77 Properties Glass transition 41 39 49 38 52 40 54 55 50 82 30 temperature (TgT) tan at 110 C. 6.0 5.6 5.9 7.7 6.0 8.0 7.9 7.8 9.8 1.4 11.4 tan at 120 C. 7.4 7.5 8.1 11.5 8.1 11.3 10.9 10.6 15.0 1.9 15.7 tan at 130 C. 9.3 9.3 10.8 15.4 10.7 15.8 14.6 13.4 17.9 1.9 21.6 Double bond 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.1 0.0 0.0 0.0 equivalent (mM/g) (G) at 120 C. (Pa) 47 40 100 40 111 40 63 65 190 46,440 14 (G) at 120 C. (Pa) 350 300 810 460 900 450 685 690 2,850 87,390 220 THF insolubles (%) 3 3 5 4 4 3 3 3 0 21 4

[Production of Toner Binders (D-1) to (D-3)]

(21) In each example, a mixture of the polyester (A1) or (A1), the polyester (B), and the crystalline resin (C) in parts by weight according to Table 3 was fed into a twin screw kneader in the same manner as is the case with Example 1, and at the same time, the radical reaction initiator (c) was fed thereinto to carry out a crosslinking reaction in the same manner as in Example 1. Thus, the toner binders (D-1) to (D-3) were obtained.

(22) The glass transition temperature (Tg.sub.T) and the amount of the THF insolubles were measured for each of the toner binders according to the examples and the comparative examples. Table 3 shows the results.

(23) The storage modulus (G) and the loss modulus (G) at 110 C., 120 C., and 130 C. were also measured to calculate the loss tangent tan at each temperature. Table 3 shows the results.

(24) Table 3 also shows the storage modulus (G) and loss modulus (G) at 120 C.

[Production of Toner (T-1)]

(25) To 85 parts of the toner binder (D-1) were added 6 parts of carbon black MA-100 [available from Mitsubishi Chemical Corporation] as a pigment, 4 parts of carnauba wax as a release agent, and 4 parts of charge controlling agent T-77 [available from Hodogaya Chemical Co., Ltd.] to produce a toner by the following method.

(26) First, the components were pre-mixed using a Henschel mixer [FM10B available from Nippon Coke and Engineering Co., Ltd.], and then kneaded by a twin screw kneader [PCM-30 available from Ikegai Corporation]. Subsequently, after the kneaded mixture was finely ground using a supersonic jet grinder Labo Jet [available from Nippon Pneumatic Mfg. Co., Ltd.], the resultant particles were classified by an airflow classifier [MDS-I available from Nippon Pneumatic Mfg. Co., Ltd.]. Thus, toner particles having a volume average particle diameter D50 of 8 m were obtained.

(27) Subsequently, 1 part of colloidal silica (Aerosil R972 available from Nippon Aerosil Co., Ltd.) as a fluidizer was added to 100 parts of the toner particles and mixed in a sample mill. Thus, the toner (T-1) of the present invention was obtained.

[Production of Toners (T-2) to (T-21)]

(28) In each example, the raw materials in parts by weight according to Table 4 were used to produce a toner in the same manner as in Example 22. Thus, the toners (T-2) to (T-21) of the present invention were obtained.

(29) TABLE-US-00004 TABLE 4 Ex. 22 Ex. 23 Ex. 24 Ex. 25 Ex. 26 Ex. 27 Ex. 28 Ex. 29 Ex. 30 Ex. 31 Ex. 32 Ex. 33 Ex. 34 Toner (T-1) (T-2) (T-3) (T-4) (T-5) (T-6) (T-7) (T-8) (T-9) (T-10) (T-11) (T-12) (T-13) Toner binder (D) (D-1) (D-2) (D-3) (D-4) (D-5) (D-6) (D-7) (D-8) (D-9) (D-10) (D-11) (D-12) (D-13) Toner (T) Composition (parts by weight) Toner binder (D-1) 85 (D-2) 85 (D-3) 85 (D-4) 85 (D-5) 85 (D-6) 85 (D-7) 85 (D-8) 85 (D-9) 85 (D-10) 85 (D-11) 85 (D-12) 85 (D-13) 85 (D-14) (D-15) (D-16) (D-17) (D-18) (D-19) (D-20) (D-21) (D-1) (D-2) (D-3) Pigment Carbon black 6 6 6 6 6 6 6 6 6 6 6 6 6 Charge T-77 4 4 4 4 4 4 4 4 4 4 4 4 4 controlling agent Release agent Carnauba wax 4 4 4 4 4 4 4 4 4 4 4 4 4 Fluidizer Aerosil R972 1 1 1 1 1 1 1 1 1 1 1 1 1 Resulting properties Gloss degree (%) 20 25 30 22 28 26 28 26 23 24 40 35 34 Hot offset occurrence temperature ( C.) 200 200 180 200 190 190 180 190 180 180 180 180 200 Cold offset occurrence temperature ( C.) 125 115 120 125 125 125 125 125 110 105 100 110 100 Heat-resistant storage stability A A A A A A A A A A A A A Electrostatic charge stability A A A A A A A A A A A A A Grindability A A A A A A A A A A A A A Image strength A A A A A A A A A A A A A Ex. 35 Ex. 36 Ex. 37 Ex. 38 Ex. 39 Ex. 40 Ex. 41 Ex. 42 Com. Ex. 4 Com. Ex. 5 Com. Ex. 6 Toner (T-14) (T-15) (T-16) (T-17) (T-18) (T-19) (T-20) (T-21) (T-1) (T-2) (T-3) Toner binder (D) (D-14) (D-15) (D-16) (D-17) (D-18) (D-19) (D-20) (D-21) (D-1) (D-2) (D-3) Toner (T) Composition (parts by weight) Toner binder (D-1) (D-2) (D-3) (D-4) (D-5) (D-6) (D-7) (D-8) (D-9) (D-10) (D-11) (D-12) (D-13) (D-14) 85 (D-15) 85 (D-16) 85 (D-17) 85 (D-18) 85 (D-19) 85 (D-20) 85 (D-21) 85 (D-1) 85 (D-2) 85 (D-3) 85 Pigment Carbon black 6 6 6 6 6 6 6 6 6 6 6 Charge T-77 4 4 4 4 4 4 4 4 4 4 4 controlling agent Release agent Carnauba wax 4 4 4 4 4 4 4 4 4 4 4 Fluidizer Aerosil R972 1 1 1 1 1 1 1 1 1 1 1 Resulting properties Gloss degree (%) 32 31 37 45 36 41 43 40 20 2 20 Hot offset occurrence temperature ( C.) 200 200 210 180 200 180 180 180 130 230 120 Cold offset occurrence temperature ( C.) 105 105 110 105 110 110 105 110 120 170 115 Heat-resistant storage stability A A A A A A A A C A C Electrostatic charge stability A A A A A A A A A A A Grindability A A A A A A A A A B B Image strength A A A A A A A A C A C

[Production of Toners (T-1) to (T-3)]

(30) In each example, the raw materials in parts by weight according to Table 4 were used to produce a toner in the same manner as in Example 22. Thus, the toners (T-1) to (T-3) were obtained.

(31) [Evaluation Methods]

(32) The following describes measurement methods, evaluation methods, and criteria for testing of the each obtained toner for low-temperature fixability, glossiness, hot offset resistance, heat-resistant storage stability, electrostatic charge stability, grindability, and image strength.

(33) <Low-Temperature Fixability (Cold Offset Occurrence Temperature)>

(34) The toner was uniformly placed on paper to a ratio of 1.00 mg/cm.sup.2. At this point, the powder was placed on the paper using a printer with its thermal fixing device removed. Any method may be used as long as the powder can be uniformly placed in the above ratio.

(35) This paper was passed between a soft roller and a heating roller at a fixing rate (peripheral speed of the heating roller) of 213 mm/sec with the heating roller temperature in increments of 5 C. in the range of 100 C. to 230 C.

(36) Then, the toner-fixed image was visually observed for occurrence of cold offset, and the cold offset occurrence temperature (MFT) was measured.

(37) A lower cold offset occurrence temperature indicates better low-temperature fixability.

(38) Under the above evaluation conditions, usually, a lower cold offset occurrence temperature of 125 C. or lower is preferred.

(39) <Glossiness>

(40) The toner was placed on paper and fixed to the paper by the same method as described above for the low-temperature fixability.

(41) Then, thick white paper was placed under the toner-fixed paper, and the gloss degree (%) of the printed image was measured at an incident angle of 60 degrees using a glossmeter (IG-330 available from Horiba, Ltd.) for each increment of 5 C. in the range of the cold offset occurrence temperature (MFT) to a hot offset occurrence temperature. The highest gloss degree (%) in the range is used as an index of the glossiness of the toner.

(42) For example, when the gloss degree is 10% at 120 C., 15% at 125 C., 20% at 130 C., and 18% at 135 C., the highest gloss degree is 20% at 130 C. Thus, the gloss degree of 20% is used as an index.

(43) A higher gloss degree indicates better glossiness. Under the above evaluation conditions, usually, a gloss degree of 20% or higher is preferred.

(44) <Hot Offset Resistance (Hot Offset Occurrence Temperature)>

(45) By the same method as described above for the low-temperature fixability, the toner was placed on paper passed between a soft roller and a heating roller at a fixing rate (peripheral speed of the heating roller) of 213 mm/sec with the heating roller temperature in increments of 5 C. in the range of 100 C. to 230 C.

(46) Then, the toner-fixed image was visually observed for occurrence of hot offset, and the hot offset occurrence temperature was measured.

(47) A higher hot offset occurrence temperature indicates better hot offset resistance. Under the above evaluation conditions, usually, a hot offset occurrence temperature of 180 C. or higher is preferred.

(48) <Heat-Resistant Storage Stability>

(49) The toner (1 g) was placed in an airtight container and left to stand in an atmosphere of 50 C. and a humidity of 50% for 24 hours. The degree of blocking was visually observed, and the heat-resistant storage stability was evaluated according to the following criteria.

(50) [Criteria]

(51) A: No blocking occurred.

(52) B: Blocking occurred partially.

(53) C: Blocking occurred entirely.

(54) <Electrostatic Charge Stability>

(55) (1) A 50-ml glass jar was charged with 0.5 g of the toner and 20 g of a ferrite carrier (F-150 available from Powdertech Co., Ltd.). The temperature and the relative humidity inside the glass jar were controlled at 23 C. and 50% for at least eight hours.

(56) (2) The glass jar was friction-stirred at 50 rpm for 10 minutes and for 60 minutes by a Turbula shaker-mixer. The electrostatic charge level was measured for each time period.

(57) A blow-off electrostatic charge level measurement device [available from Kyocera Chemical Corporation] was used for the measurement.

(58) A value of electrostatic charge level after a friction time of 60 minutes/electrostatic charge level after a friction time of 10 minutes was calculated to obtain an index of the electrostatic charge stability.

(59) [Criteria]

(60) A: 0.7 or more

(61) B: 0.6 or more and less than 0.7

(62) C: Less than 0.6

(63) <Grindability>

(64) After kneading by a twin screw kneader, cooling, and coarsely grounding, the resultant coarse particles of the toner (8.6 mesh pass to 30 mesh on) were finely ground by a supersonic jet mill (Labojet available from Nippon Pneumatic Mfg. Co., Ltd.) under the following conditions.

(65) Grinding pressure: 0.5 MPa

(66) Grinding time: 10 min

(67) Adjuster ring: 15 mm

(68) Louver size: medium

(69) Without classification, these particles were measured for the volume average particle size (m) by a Coulter counter TAII (U.S. Coulter Electronics Ltd.). The grindability was evaluated according to the following criteria.

(70) [Criteria]

(71) A: Less than 10 m

(72) B: 10 m or more and less than 12 m

(73) C: 12 m or more

(74) <Image Strength>

(75) An image fixed for evaluation of the low-temperature fixability was subjected to a scratch test under a load of 10 g that was applied to a pencil fixed at an inclination of 45 degrees from directly above the pencil according to JIS K 5600. The image strength was evaluated based on the hardness of the pencil that did not scratch the image. A higher pencil hardness indicates better image strength. Generally, a hardness of HB or higher is preferred.

(76) [Criteria]

(77) A: HB or higher

(78) B: B

(79) C: 2B or lower

(80) As is clear from the evaluation results shown in Table 4, the toners (T-1) to (T-21) in Examples 22 to 42 of the present invention exhibited excellent results in all the properties.

(81) In contrast, the toners in Comparative Example 4, Comparative Example 5, and Comparative Example 6 exhibited poor results in some properties. The toner binder used in Comparative Example 5 had a tan of less than 2 at 110 C., 120 C., and 130 C. In contrast, the toner binder used in Comparative Example 6 had a tan of more than 20 at 130 C.

INDUSTRIAL APPLICABILITY

(82) The toner binder and the toner of the present invention exhibit offset resistance and can provide high gloss for a toner image, which are excellent in low-temperature fixability, grindability, image strength, and heat-resistant storage stability. The toner binder and the toner are suitably applicable as a toner binder and a toner for developing electrostatic images in processes such as electrographic printing, electrostatic recording, and electrostatic printing.

(83) The toner binder and the toner are also suitably applicable as additives for coating materials, additives for adhesives, and particles for electronic paper.