Claims
- 1. A negatively chargeable magnetic toner for developing an electrostatic image comprising: toner particles, which are comprised of a magnetic material, 100 parts by weight of a binder resin, 0.5 to 20 parts by weight of a long-chain compound, and 0.1-10 parts by weight of a negative charge control agent and from 0.1 to 4 wt. parts per 100 wt. parts of the magnetic toner of a flowability improving agent carried on the surface of the toner particles,wherein the binder resin consists essentially of a polyester resin having an acid value of 10-50 mg KOH/g, obtained from a mixture of (i) diol represented by the following formula (A): wherein R denotes an ethylene or propylene group, x and y are independently 0 or a positive integer with the proviso that the average of x+y is in the range of 0-10,(ii) dibasic acid selected from the group consisting of terephthalic acid, isophthalic acid, succinic acid, n-dodecenylsuccinic acid and fumaric acid, and (iii) trimellitic anhydride, said polyester resin has an OH value of at most 60 mg KOH/g and a number-average molecular weight (Mn) of 2,500 to 10,000, the long-chain compound comprises a long-chain alkyl alcohol having an OH value of 22-90 mg KOH/g and a weight-average molecular weight (Mw) of 800-3900, an Mw/Mn ratio of at most 2.9, and a melting point of at least 91° C., and the long-chain alkyl alcohol is represented by the following formula (3): formula (3)CH3(CH2)xCH2OH wherein X is 38-170 on average, and is contained so as to satisfy a condition of the following formulae (1) and (5): formula (1)acid value of binder resin+OH value of long-chain alkyl alcohol>(¼)×OH value of binder resin, formula (5)fr x (acid value of binder resin)+fa x (OH value of long-chain alkyl alcohol)—(¼) x fr x (OH value of binder resin) >10 wherein fr and fa denote content factors of the binder resin and long-chain alkyl alcohol, respectively, wherein fr=(R/(a+α+R) and fa=(a/(a+α+R) and R is the content of the binder resin, a is the content of the long-chain alkyl alcohol, and α is the content of THF-insoluble resinous matter other than the long-chain alkyl alcohol.
- 2. The toner according to claim 1, wherein the long-chain alkyl alcohol contains at least 50wt. % of a long-chain alkyl alcohol component having at least 37 carbon atoms based on the total weight of the long-chain alkyl alcohol.
- 3. The toner according to claim 1, wherein the polyester resin and the long-chain alkyl alcohol satisfy a condition of the following formula:acid value of polyester resin+OH value of long-chain alkyl alcohol−(¼)×OH value of polyester resin >5.
- 4. The toner according to claim 3, wherein the polyester resin and the long-chain alkyl alcohol satisfy a condition of the following formula:acid value of polyester resin+OH value of long-chain alkyl alcohol−(¼)×OH value of polyester resin >10.
- 5. The toner according to claim 1, wherein the polyester resin has a glass transition point of 40-90° C.
- 6. The toner according to claim 5, wherein the polyester resin has a glass transition point of 45-85° C.
- 7. The toner according to claim 1, wherein the polyester resin has a weight average molecular weight (Mw) of 3×103 -3×106.
- 8. The toner according to claim 7, wherein the polyester resin has an Mw of 1×104-2.5×106.
- 9. The toner according to claim 8, wherein the polyester resin has an Mw of 4×104-2×106.
- 10. A toner according to claim 1, wherein the value of (fr x (acid value of binder resin)+fa x (OH value of long-chain alkyl alcohol)) in the formula 5 is in the range of 21 to 90.
Priority Claims (3)
Number |
Date |
Country |
Kind |
5-354164 |
Dec 1993 |
JP |
|
6-123295 |
May 1994 |
JP |
|
6-203024 |
Aug 1994 |
JP |
|
Parent Case Info
This application is a continuation of prior application Ser. No. 08/361,526 filed Dec. 22, 1994, now abandoned.
US Referenced Citations (25)
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EP |
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EP |
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JP |
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JP |
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Non-Patent Literature Citations (2)
Entry |
Patent Abstracts of Japan, vol. 12, No. 48 (P-666) [2895], Feb. 1988 of JP 62-195276. |
Derwent Abstract No. AN 91-257358 of JP 3-168651 dated 1991. |
Continuations (1)
|
Number |
Date |
Country |
Parent |
08/361526 |
Dec 1994 |
US |
Child |
08/992427 |
|
US |