JP2938567B2 - Electrophotographic toner - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an electrophotographic toner which is fixed with a low calorific value and has excellent image quality.

BACKGROUND ART In the electrophotographic technology field, as the amount of information increases,
The required copying speed tends to increase. In a high-speed camera, the amount of heat transmitted from the calorimeter roll is smaller than that in a medium-speed camera, and the heat loss captured by the paper cannot be fully recovered, so that the surface temperature of the calorimeter roll decreases remarkably. Therefore, it has been desired to provide a toner composition that can be fixed with a lower calorific value and does not cause an offset phenomenon at the fixing temperature.

On the other hand, as the size of a camera has been reduced, development and improvement of a developer having a low calorific value and excellent fixability and anti-offset property have been similarly performed in association with a decrease in the temperature and pressure of a fixing roll.

For example, as described in JP-B-55-6895, a resin for developer has a weight average molecular weight / number average molecular weight of 3.4.
To provide a toner having good offset resistance by using a resin having a number average molecular weight of 2,000 to 30,000.
A method of obtaining a toner which does not cause an offset phenomenon even at a relatively high fixing temperature by using a crosslinked resin as described in JP-A-10-1031 to widen a fixing temperature range is known.

However, although these techniques have a great effect in a conventional copying machine in which the offset phenomenon becomes a problem,
It has been found that a low calorie fixing copier cannot provide a sufficient effect. This is presumably because in the prior art, improvements were made in the direction of increasing the weight-average molecular weight of the polymer in order to improve the strength and offset resistance of the toner.

Therefore, these resins have very high viscosities and are not suitable for a low heat fixing copying machine as they are. However, if the weight average molecular weight is reduced to lower the viscosity, the offset resistance or the strength of the toner is insufficient, and the toner tends to be broken or broken during long-term running, thereby deteriorating the image quality.

DISCLOSURE OF THE INVENTION The object of the present invention is to solve all the problems of the prior art, and to provide a toner that can be fixed with a low heat quantity suitable for recent high-speed copying machines and low-calorie copying machines and has excellent strength. Is to do.

The present inventors have found that the problem is that the strength of the low-molecular resin having high fluidity in the toner is low and the strength of the toner is insufficient as a whole.
The present invention has been found that the problem can be solved by producing a toner using an ethylene polymer having a w) of 200,000 or more and an ethylene polymer having high resin strength and fluidity.

That is, the present invention has a weight average molecular weight (Mw) of 200,000
The above ethylene polymer X (hereinafter, ethylene polymer X)
20 to 80 parts by weight, and 80 to 20 parts by weight of an ethylene polymer Y having a Z average molecular weight / number average molecular weight (Mz / Mn) of 6 or more and Mw of 50,000 or less (hereinafter abbreviated as ethylene polymer Y). Is a toner composition for electrophotography, the mixture being a main component.

According to the above-described method of the present invention, a stable and high-quality image can be always obtained by fixing with a low calorific value, which cannot be solved by the prior art. That is, the toner of the present invention has a low fixing minimum temperature, a wide non-offset region, and extremely good image characteristics, and has excellent performance as an electrophotographic toner.

BEST MODE FOR CARRYING OUT THE INVENTION The molecular weight of the ethylene polymer X in the present invention is 20 in Mw.
It is more than 0,000, preferably 200,000 to 1,000,000. The Mw of the ethylene polymer X is greatly related to the offset resistance of the toner, the abrasion resistance in a fixing property test, the image stability, and the like. If the Mw is less than 200,000, the above-mentioned properties are significantly deteriorated.

In the present invention, the ratio of the ethylene polymer X is 20
It is necessary that the amount be up to 80 parts by weight, especially 30 to 70 parts by weight. When the ratio of the ethylene polymer X is 20
If the amount is less than the weight part, the strength and viscosity of the resin decrease, and the offset resistance, the abrasion resistance of the fixing property, and the image stability deteriorate. On the other hand, when the amount is more than 80 parts by weight, the viscosity of the resin is increased, and the fixing at a low calorific value becomes insufficient.

Z average molecular weight of ethylene polymer Y in the present invention /
The number average molecular weight (Mz / Mn) is preferably 6 or more and Mw is 50,000 or less. If Mz / Mn is less than 6, the resin strength of the ethylene polymer Y is not guaranteed and the copy image is not stable. On the other hand, if the Mw is larger than 50,000, the resin strength is guaranteed, but the fluidity deteriorates, and fixing with a low calorific value becomes impossible. Preferably Mz / Mn is 6-100, Mw is 1,000-50,
000.

Z average molecular weight of ethylene polymer Y in the present invention /
When the number average molecular weight (Mz / Mn) is 6 or more and Mw is 50,000 or less, for example, a method of obtaining a polymer having a wide distribution by continuously or intermittently changing the polymerization temperature, etc., Mw not exceeding 50,000 And a method of broadening the molecular weight distribution using a crosslinking agent.

The ethylenic polymers X and Y in the present invention are those obtained by polymerizing an ethylenically unsaturated monomer by a polymerization method such as solution polymerization, suspension polymerization and emulsion polymerization.

The ethylenically unsaturated monomer is, for example, methyl acrylate, ethyl acrylate, propyl acrylate,
Butyl acrylate, octyl acrylate, cyclohexyl acrylate, lauryl acrylate, stearyl acrylate, benzyl acrylate, furfuryl acrylate, tetrahydrofurfuryl acrylate, hydroxyethyl acrylate, hydroxybutyl acrylate, dimethylaminomethyl acrylate Acrylates such as dimethylaminoethyl acrylate; methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, octyl methacrylate, lauryl methacrylate, stearyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate; Furfuryl methacrylate, tetrahydrofurfuryl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, Methacrylic esters such as hydroxybutyl acrylate, dimethylaminomethyl methacrylate, and dimethylaminoethyl methacrylate; aromatic vinyl monomers such as vinyltoluene, α-methylstyrene, chlorostyrene and styrene; dibutyl maleate; Unsaturated dibasic acid dialkyl esters such as dioctyl maleate, dibutyl fumarate, dioctyl fumarate; vinyl esters such as vinyl acetate and vinyl propionate; nitrogen-containing vinyl monomers such as acrylonitrile and methacrylonitrile; acrylic acid; Unsaturated carboxylic acids such as methacrylic acid and citric acid; unsaturated dicarboxylic acids such as maleic acid, maleic anhydride, fumaric acid and itaconic acid; monomethyl maleate, monoethyl maleate, monobutyl maleate, maleic acid Unsaturated dicarboxylic acid monoesters such as monooctyl, monoethyl fumarate, monobutyl fumarate, monooctyl fumarate; styrenesulfonic acid, acrylamide, methacrylamide, N-substituted acrylamide, N-substituted methacrylamide, methacrylamidepropanesulfonic acid, etc. Yes, at least one of these monomers is used. Among them, acrylates, methacrylates, styrene, dialkyl fumarate, acrylonitrile, cinnamate methacrylate, monoester fumarate, acrylic acid, acrylamide,
Methacrylamide and the like are preferred.

The amount of the above polymer mixture in the toner is usually 50 to 95% by weight.
It is. If necessary, the polymer mixture may be, for example, polyvinyl chloride, polyolefin, polyester, polyvinyl butyral, polyurethane, polyamide, rosin, terpene resin, phenol resin, or epoxy resin as long as the effects of the present invention are not impaired. , Paraffin wax, polyolefin wax and the like may be added.

Generally, a colorant is used in the electrophotographic toner of the present invention. As a coloring agent to be used, for example, carbon black,
Black pigments such as acetylene black, lamp black and magnetite, graphite, yellow iron oxide, Hansa Yellow G, quinoline yellow lake, permanent yellow, NCG molybdenum orange, Vulcan orange, indanthrene, brilliant orange GK, bengala, brilliant carmine 6B And known pigments such as frisalin lake, methyl violet lake, fast violet B, cobalt blue, alkali blue lake, phthalocyanine blue, fast sky blue, pigment green B, malachite green lake, titanium oxide and zinc white. The amount is usually 50 to 300 parts by weight based on 100 parts by weight of the polymer.

The toner composition of the present invention is prepared by appropriately selecting and adding known charge adjusting agents such as nigrosine, a quaternary ammonium salt, a metal-containing azo pigment, a metal salt of a fatty acid, a pigment dispersant, an offset inhibitor and the like. Can be used as a toner.

That is, the polymer mixture to which the above-mentioned various additives were added was premixed with a Henschel mixer, kneaded in a heated and melted state with a kneader such as a kneader, finely crushed using a jet crusher after cooling, and then classified. The particles are usually collected in the range of 8 to 20 μ to obtain a toner.

Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited to these Examples. still,
“Parts” indicates parts by weight.

Production Example 15 The four-necked flask of 5 was equipped with a cooling tube, a thermometer, a nitrogen introduction tube, and a stirrer, charged with 70 parts of styrene and 30 parts of n-butyl acrylate, and heated to 100 ° C. while introducing nitrogen. , 100 parts of xylol, 0.2 parts of azoisobutyronitrile
It was dropped continuously over 10 hours. Thereafter, the temperature was raised to 130 ° C., and the residual monomer was polymerized for 5 hours. The solvent was removed from the resin solution to obtain a resin A. In the following Production Examples 2 to 5, the amount of azoisobutyronitrile was varied in order to change the weight average molecular weight (Mw) of the obtained ethylenic polymer Y.

Production Example 2 Resin B was obtained in the same manner as in Production Example 1 except that 0.4 parts of azoisobutyronitrile were used.

Production Example 3 Resin C was obtained in the same manner as in Production Example 1, except that 0.6 parts of azoisobutyronitrile was used.

Production Example 4 Resin D was obtained in the same manner as in Production Example 1, except that 1.0 part of azoisobutyronitrile was used.

Production Example 5 A cooling tube, a thermometer, a nitrogen introducing tube, and a stirrer were attached to the four-necked flask of Example 5, 100 parts of xylol was charged, and the temperature was raised to reflux while introducing nitrogen.
Butyl acrylate 15 parts, azoisobutyronitrile 5
And 0.1 part of divinylbenzene were continuously dropped over 5 hours. Thereafter, the remaining monomer was polymerized for 10 hours. The resin solution was desolvated to obtain a resin E. The following Production Examples 6 to 12
The amount of divinylbenzene was varied to change (Mz / Mn) of the ethylenic polymer Y obtained in the above.

Production Example 6 Production Example 5 except that divinylbenzene was changed to 0.5 part.
Resin F was obtained in the same manner as in the above.

Production Example 7 Production Example 5 except that divinylbenzene was changed to 1.0 part.
Resin G was obtained in the same manner as described above.

Production Example 8 Production Example 5 except that divinylbenzene was changed to 1.5 parts.
Resin H was obtained in the same manner as described above.

Production Example 9 Production Example 5 except that divinylbenzene was changed to 3.0 parts.
Resin I was obtained in the same manner as described above.

Production Example 10 Production Example 5 except that divinylbenzene was changed to 3.3 parts.
Resin J was obtained in the same manner as described above.

Production Example 11 Production Example 5 except that divinylbenzene was changed to 3.8 parts.
Resin K was obtained in the same manner as described above.

Production Example 12 Production Example 5 except that divinylbenzene was changed to 4.0 parts.
Resin L was obtained in the same manner as described above.

Table 1 shows the molecular weights of the resins produced in Production Examples 1 to 12 described above.

The molecular weight was determined by GPC using commercially available monodispersed standard polystyrene as a standard, tetrahydrofuran as a solvent, and a refractometer as a detector.

Resins were produced in Production Examples 13 to 19 in order to examine the effect of Mz / Mn of the resin (Y) produced by another production method.

Production Example 13 100 parts of xylol were charged into the same apparatus as in Production Example 5, and
The temperature was raised to 80 ° C while introducing nitrogen, and 85 parts of styrene and n-butyl acrylate were heated at a rate of 10 ° C / hr.
15 parts and 5 parts of azoisobutyronitrile were continuously dropped over 5 hours. Thereafter, the remaining monomer was polymerized for 10 hours, and the solvent was removed to obtain a resin M.

Production Example 14 Resin N was obtained in the same manner as in Production Example 13, except that the temperature was changed to 90 ° C.

Production Example 15 Resin P was obtained in the same manner as in Production Example 13 except that the temperature was changed to 100 ° C. and the temperature was raised at a rate of 8 ° C./hr.

Production Example 16 Resin Q was obtained in the same manner as in Production Example 13, except that the temperature was changed to 110 ° C. and the temperature was raised at a rate of 5 ° C./hr.

Production Example 17 Resins E and F were mixed at a ratio of 1: 1 to obtain a resin R.

Production Example 18 Resins E and H were mixed at a ratio of 1: 1 to obtain a resin S.

Production Example 19 Resins E and H were mixed at a ratio of 8: 2 to obtain a resin T.

Table 2 shows the molecular weights of the resins produced in Production Examples 13 to 19 above.

Examples 1 to 4 and Comparative Examples 1 to 4 In order to see the effect of Mz / Mn of the ethylene polymer Y, the above resins were combined according to Table 3 and a toner was produced by the following method.

100 parts of a resin mixture, 10 parts of carbon black (AM-100, manufactured by Mitsubishi Chemical Corporation), 5 parts of polypropylene wax,
After preliminarily mixing 1 part of a nigrosine dye as a charge control agent with a Henschel mixer, kneading the mixture at 170 ° C. using a twin-screw kneader, cooling, coarsely pulverizing, finely pulverizing, and further classifying with a classifier. ~ 20μ toner was obtained.

The use ratio of the resin in the table is a weight ratio.

Using the above toner, the fixing property, the offset property, the image quality and the like were evaluated. The fixing property and the offset property were modified so that the roll temperature of a commercially available copying machine could be arbitrarily changed.

 Table 3 shows the results.

In the table, the 70% fixing temperature, the toner layer on the image of solid black portions of 2 cm × 2 cm, with a load of 125 g / cm ² at Gakushin type friction fastness tester (Daiei Kagaku Seiki Seisakusho) The minimum heat roll temperature required for the toner layer to have a residual weight of more than 70% after rubbing 50 times with a sand eraser.

The low-temperature offset refers to a temperature at which the temperature of the fixing roll is lowered and offset starts to occur.

The high-temperature offset refers to a temperature at which the temperature of the fixing roll is increased and offset starts to occur.

The evaluation of the image quality was made by visually checking the 50,000th copy and based on the following criteria.

 ◎ Very clear and free of fogging.

○ It is slightly blurred or slightly fogged, but there is no practical problem.

 △ It is a little ugly or fuzzy.

 × Unusable because of severe blurring and offset.

Example 5 and Comparative Examples 5 to 6 In order to examine the effect of Mw of the ethylene polymer X used, the above resins were combined according to Table 4 to produce a toner according to Example 1.

 The evaluation results are shown in Table 4 together with Example 2.

Examples 6 to 9 and Comparative Examples 7 to 10 In order to see the effect of changing the ratio between the ethylene polymers X and Y, the above resins were combined according to Table 5 and a toner was produced according to Example 1.

 The evaluation results are shown in Table 5 together with Example 2.

Examples 10 to 14 and Comparative Examples 11 to 12 Resins MT in Table 6 and Resin A were combined to produce a toner by the above-described method, and the same evaluation was performed.

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-62-115170 (JP, A) JP-B-55-6895 (JP, B2)

Claims (12)

(57) [Claims] 1. An ethylene polymer having a weight-average molecular weight (Mw) of 20 to 80 parts by weight and an ethylene polymer having a Z-average molecular weight / number-average molecular weight (Mz / Mn) of 6 or more and Mw of 50,000 or less. An electrophotographic toner composition containing a mixture of 80 to 20 parts by weight of a polymer Y as a main component. 2. The ethylene polymer X having a Mw of 200,000 to 1,000.
2. The electrophotographic toner composition according to claim 1, wherein the content is in the range of 0.000. 3. The toner composition according to claim 1, wherein the amount of the ethylene polymer X is 30 to 70 parts by weight and the amount of the ethylene polymer Y is 70 to 30 parts by weight. 4. The method according to claim 1, wherein Mz / Mn is in the range of 6 to 100.
Item. 5. The ethylene polymer Y having a Mw of 1,000 to 50,000.
The toner composition according to claim 1, wherein 6. The method according to claim 1, wherein the ethylenic polymer is obtained by a polymerization method selected from the group consisting of solution polymerization, suspension polymerization and emulsion polymerization of ethylenically unsaturated monomers.
Item. 7. The ethylenically unsaturated monomer is an acrylate, a methacrylate, a styrene, a dialkyl fumarate, an acrylonitrile, a methacrylic acid, a cinnamic acid, a fumaric monoester, an acrylic acid, an acrylamide or a methacryl. The toner composition according to claim 6, which is at least one monomer selected from the group consisting of amides. 8. The toner composition according to claim 1, wherein the amount of the polymer mixture in the toner ranges from 50 to 95% by weight. 9. A polymer material selected from the group consisting of polyvinyl chloride, polyolefin, polyester, polyvinyl butyral, polyurethane, polyamide, rosin, terpene resin, phenol resin, epoxy resin, paraffin wax and polyolefin wax in the toner. The toner composition according to claim 1, comprising: 10. The toner composition according to claim 1, wherein the colorant is contained in an amount of 5 to 300 parts by weight based on 100 parts by weight of the polymer. 11. The toner composition according to claim 14, further comprising a charge adjusting agent, a pigment dispersant, and an anti-offset agent. 12. A polymer mixture to which various additives are added as required is premixed, kneaded in a heated and molten state, cooled, finely pulverized and classified to a particle diameter in the range of 8 to 20 μm. The toner composition according to claim 1.