JP2874167B2 - Electrostatic toner - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toner for electrostatography, and more particularly to a dry toner for electrostatography excellent in long-term printing durability.

2. Description of the Related Art Generally, there are a one-component system and a two-component system as an electrostatic latent image developer in electrophotography, but the latter is generally used at present. The two-component developer is also disclosed in
-66134, JP-A-59-162563, Japanese Patent Application No. 61-1
As seen in JP-A-6314, by dispersing and binding fine ferromagnetic particles in a binder resin, a so-called binder-type carrier, which is again adjusted to a certain size equal to or larger than the toner particle size, is used in a conventional method. It has become possible to obtain a printing durability of at least 500 prints per gram of a carrier, which has never been reached with a two-component developer. This means that the conventional iron powder carrier and some coated carriers have a long life which is incomparable to the printing durability of 20 to 30 sheets per gram of the carrier.

Problems to be Solved by the Invention On the other hand, when various studies were conducted on toner, depending on the type of toner, the toner adhered to the photoreceptor in a film form (this development is called "filming"). This causes a decrease in the sensitivity of the photoconductor, an increase in the residual potential, and fog. In addition, the toner is fused on the photoreceptor into a black spot, and the black spot toner (hereinafter referred to as “black spot”)
Spot), which is abbreviated as “BS”), becomes small black spots and is developed on copy paper as an undesired image.

Further, since the toner adheres to the carrier (the attached toner is referred to as “spent toner”), the rising of the charge is deteriorated, which may cause fogging and scattering of the toner.

The toner generally has a configuration in which an additive such as a colorant is dispersed in a binder resin. Various binder resins are commercially available, and toners are manufactured using these resins.

However, when a toner is prepared using a resin that is usually put on the market, even if the printing durability of 40,000 to 60,000 sheets is
It was found that when printing more than 10,000 sheets, filming gradually became noticeable, the carrier was spent, and fogging occurred.

Means for Solving the Problems Filming of the toner on the photoreceptor, fusing of the toner as a black spot on the photoreceptor, adhesion of the toner to the carrier, and fogging are caused by the toner binder. When synthesizing the resin, low molecular weight oligomers and raw material monomers that have not yet jumped yet, reaction catalyst residues,
It has been found that trace amounts of organic solvents and the like used remain depending on the means of polymerization, and these are caused by local plasticization of the binder resin.

Further, in order to solve the above problem, it is necessary to sufficiently remove the solvent, wash with water and dry after the synthesis of the resin to remove the plasticizing substance. Thermogravimetric analyzer (TG) for thermoplastic resin (Thermo Gra
It was found that the heating weight reduction starting temperature in the vimeter) should be 100 ° C. or more and the weight reduced by heating by 170 ° C. should be 0.3% by weight or less of the total weight.

That is, the present invention relates to an electrophotographic toner comprising at least a thermoplastic resin and a colorant, wherein the thermoplastic resin is a styrene-acrylic copolymer resin obtained by solution polymerization, and the heat weight of the thermoplastic resin is Decrease start temperature is 10
The present invention relates to a toner for electrophotography, wherein the weight loss by heating at 0 ° C. or more and up to 170 ° C. is 0.3% by weight or less of the total weight.

The thermoplastic resin used in the present invention generally has a softening point sufficient for fixing and a glass transition point sufficient for storage stability, and is synthesized by solution polymerization.

For example, a copolymer resin of styrene and an acrylic ester or a methacrylic ester may be used.

The heating weight loss start temperature is a temperature at which the weight of the resin starts to decrease when the resin is gradually heated in an atmosphere, and can be measured by, for example, a thermobalance.

In the present invention, the heating weight loss start temperature, SSC-5000 manufactured by Seiko Denshi Co., using TG / DTA200, in a nitrogen stream,
When the sample resin is heated at a heating rate of 10 ° C./min, the temperature (° C.) at which the weight of the sample resin starts to decrease is shown.

The resin used in the present invention must have a heating weight loss onset temperature of 100 ° C. or more, preferably 105 ° C. or more, in order to minimize substances that volatilize at low temperatures and to eliminate filming or BS on the photoreceptor.

After the heating weight loss starts, the heating weight loss starts, the heating condition is maintained, and heating is continued to 170 ° C. The weight ratio of the weight of the sample reduced to that temperature to the initial sample weight (%) Ask for.

The resin used in the present invention has a heating weight loss of 0.3% by weight (wt.
%) Or less, preferably 0.2 wt%, more preferably 0.1 wt%
It is desirable that: The resin loses weight by heating because volatile substances such as low-molecular-weight oligomers, unreacted monomers, reaction catalyst residues, and organic solvents used as needed are not sufficiently removed during resin synthesis. It is to get out. Such components include filming on the toner photoreceptor, fusion of black spots of the toner on the photoreceptor, adhesion of the toner to the carrier,
Since it causes fog, etc., keep it to 0.3 wt% or less.

The toner of the present invention is composed of a thermoplastic resin having a thermal weight loss onset temperature of 100 ° C. or higher and a heat weight loss of up to 170 ° C. of 0.3% by weight, and contains at least one colorant.

Such a thermoplastic resin was prepared by a solution polymerization method.
It can be prepared by heat treatment under reduced pressure of 01 to 10 mmHg at 80 to 200 ° C. for 0.1 to 3 hours.

Specific examples of the colorant that can be used in the present invention include black pigments such as carbon black, acetylene black, lamp black, and aniline black; and yellow pigments such as graphite, zinc yellow, cadmium yellow, and yellow iron oxide. Mineral Fast Yellow, Nickel Titanium Yellow, Navel's Yellow, Naphthol Yellow S, Hanser Yellow G, Hanser Yellow 10G, Benzidine Yellow G, Benzidine Yellow GR, Quinoline Yellow Lake, Permanent Yellow, NCG, Tartrazine Lake and the like.

For orange pigments, red-mouthed lead, molybdenum orange, permanent orange GTR, pyrazolone orange, Vulcan orange, induslen brilliant orange RK, benzidine orange G, induslen brilliant orange GK, etc. , Mercury sulphide, permanent red 4R, lithol red, pyrazolone red, watching red, calcium salt, lake red D, brilliant carmine 6B, eosin lake, rhodamine lake B, alizarin lake, brilliant carmine 3B, etc. Purple, fast violet B, methyl violet lake, etc .: For blue pigments, navy blue, cobalt blue, alkali blue lake, Victoria blue lake, phthalocyanine blue, Metal phthalocyanine blue, phthalocyanine blue, partially chlorinated, Fast Sky Blue, there is Indanthrene blue BC.

Green pigments include chrome green, chromium oxide, pigment green B, malachite green lake, and fanal yellow green G. White pigments include zinc white, titanium oxide, antimony white, and zinc sulfide.

The extender pigments include pearlite powder, barium carbonate, clay, silica, white carbon, talc, alumina white, and the like, and may be used alone or in combination of two or more.
All of them are not limited to these, regardless of whether they are organic or inorganic, as long as they have no pollution and high coloring power.

Other examples of yellow colorants include benzidine yellow, banza yellow, and chromophtal yellow.

When the toner of the present invention is used as a black toner, carbon black such as channel black or furnace black may be used as the pigment. The colorant used in the toner of the present invention is not limited to these, regardless of whether it is organic or inorganic, as long as it has no pollution and high coloring power.

If necessary, other additives such as a charge controlling agent and waxes may be added to the toner of the present invention, and various thermoplastic resins may be added to the toner of the present invention to improve fixability. May be used within a range that does not reduce the effect of the above. Alternatively, the surface treatment of the toner may be performed with an ultrafine metal oxide powder.

 Examples of the charge control agent include the following.

 Hydroxy-substituted naphtho is good for negative charging.
Eic acid and its alkyl derivatives, hydroxy-substituted tetra
Alkyl derivatives of hydronaphthoic acid and salicylic acid
Or a metal complex compound such as(Wherein X is a hydrogen atom, a lower alkyl group, a lower alkoxy group,
Represents a nitro group, a nitro group or a halogen atom, and n is 1 or more.
Or 2, m represents an integer of 1 to 3, X is the same,
May also be different, where M is a chromium or cobalt atom
And A Is hydrogen, sodium, potassium or
Represents ammonium ion. Metal complex chloride represented by)
Compound; Formula:And a metal complex salt compound represented by the formula:(Where X₁And X_TwoIs hydrogen atom, lower alkyl group, lower
Represents an alkoxy group, a nitro group or a halogen atom,
X₁And X_TwoMay be the same or different and m₁and
m_TwoRepresents an integer of 1 to 3, and R₁And R_ThreeIs a halogen atom
And R₁And R_TwoMay be the same or different and n₁
And n_TwoRepresents an integer of 1 to 3, and R_TwoAnd R_FourIs hydrogen field
M or chromium or cobalt
Represents an atom, K Is hydrogen, sodium, potassium or
Represents an ammonium ion. Metal complex represented by)
Salt compounds can be used as charge control agents. But
It is not limited to the gold-containing oil-soluble dyes listed here.
Also, 2-acrylamide-2-methylpropane-sulfo
Copolymerization of sulfonic acid salts such as
The charge control resin obtained by
When used together with an agent, the charge rise is improved and
Gnar scattering can be reduced.

In general, electron-donating dyes such as nigrosine dyes are generally used to impart positive chargeability. In addition, alkoxylated amines, quaternary ammonium salts, alkylamides, phosphorus and tungsten simple substances and compounds,
Molybdate chelate pigments, dibutyltin oxide and nitrogen-containing compounds are used alone or in combination.

Further, by using a copolymer of a vinyl monomer having an amino group, for example, dimethylaminoethyl methacrylate or diethylaminoethyl methacrylate with styrene and the like in combination with the above-mentioned charge control agent, the rise of charge is reduced and toner scattering is reduced. Can be done.

Examples of the method for producing the toner include a so-called pulverization method which is generally performed so as to be composed of the above-described resin, colorant and other additives, but is not particularly limited. The average particle size of the toner can be arbitrarily selected from 3 to 20 μm.

The toner of the present invention can be used as a two-component developer by, for example, blending with a suitable carrier. As the carrier, when performing the cascade development method, resin-coated glass beads, steel balls, etc., when performing the magnetic brush development method, ferrite, fine iron powder, or
A so-called binder type carrier or the like is used. Further, the toner of the present invention may be manufactured as an insulating magnetic toner, and the magnetic brush developing method may be performed by using the toner as a one-component developer.

Further, the toner may be used as a toner when an impression development method or a touchdown development method is performed.

Resin Synthesis Example 1 ・ Styrene 80 parts by weight ・ N-butyl methacrylate 20 parts by weight ・ Benzoyl peroxide 30 parts by weight ・ Toluene 500 parts by weight Put the above materials into a reaction vessel equipped with a stirrer, cooling pipe and thermometer, After melting, oxygen was expelled through a stream of nitrogen. Next, the temperature was gradually raised to 80 ° C., and kept at 80 ° C. for 3 hours. The temperature was further raised to 110 ° C. and kept for 3 hours. Then, it cooled to room temperature and maintained that temperature. Only a small amount of the product was desolvated and the physical properties were measured to obtain the following results.

(Number average molecular weight (Mn): 2,200, weight average molecular weight (Mw):
4.300, glass transition point (1 g): 42 ° C.) The resin obtained here is referred to as polymer A.

Resin Synthesis Example 2 70 parts by weight of styrene 30 parts by weight of n-butyl methacrylate 8 parts by weight of 3,3,5-trimethylcyclohexanone ditertiary butyl peroxyketal 100 parts by weight of toluene First at 80 ° C for 3 hours,
Next, it was kept at 110 ° C. for 10 hours and then at room temperature. Mn: 94.90 when physical properties were measured by desolvating only a small amount of the product.
0, Mw: 325,700, Tg: 75 ° C.

 The resin obtained here is referred to as polymer B.

Next, the polymer A and the polymer B were converted to a solid-form ratio. A: B = x:
The mixture was placed in a container equipped with a stirrer so as to obtain y (the ratio between x and y is shown in Table 1), heated to 80 ° C., sufficiently stirred, and uniformly mixed. Next, put in a heating vacuum oven, and gradually raise the temperature from 10 mmHg at 40 ° C first, and at 110 ° C to 160 ° C, the degree of vacuum is also 10 mmHg.
The resin obtained was changed to about 0.1 mmHg and the solvent removal time was arbitrarily changed, and the resulting resin was coarsely pulverized in advance with a 3 mm pass feather mill to obtain polymers 1 to 10 as shown in Table 1.

A toner having the following composition was obtained using these polymers 1-10.

Polymer 1 to 10.100 parts by weight Carbon black (MA # 8 parts by weight 100; manufactured by Mitsubishi Kasei Kogyo Co.) Charge control agent (Bontron N-4 parts by weight 01; manufactured by Orient Chemical Industries) Wax (Biscol 550P; 3 parts by weight) The above materials were stirred with a 10 Henschel mixer at 2000 rpm for 4 minutes. Next, after sufficiently kneading with a PCM30 (extrusion kneading machine), the mixture was cooled and roughly pulverized with a 3 mm pass feather mill. Next, the mixture was finely pulverized using a laboratory jet, and coarse powder and fine powder were classified using a zigzag classifier. Finally, colloidal silica (manufactured by Nippon Aerosil Co., Ltd .; R-97)
2) was subjected to a surface treatment of 0.2% by weight to obtain toners 1 to 10.

Toner 11 (using polymer 2) 12 (using polymer 7) having the following composition using polymers 2 and 7
I got

(Composition) • 100 parts by weight of polymer 2 or 7 • 8 parts by weight of carbon (MA # 100) • Charge control agent (Bontron S-3 parts by weight 34: manufactured by Orient Chemical Industries) • 3 parts by weight of wax (Biscol 550P) Was carried out according to the method for producing toner 10. The particle diameters of the obtained toners 1 to 12 were measured by a Coulter counter, and the ratio of particles having a particle diameter of smaller than 10 μm, the ratio of particles having a particle diameter of larger than 20 μm, and the weight average diameter D ₅₀ were measured.
Are collectively shown in Table 2.

[Manufacture of carrier I]

Parts by weight ・ Styrene-acrylic resin 100 (Priolite ACL: Goodyear) ・ Triiron tetroxide 200 (Mapico Black BL-500; Titanium) ・ Carbon black 5 (MA # 8; Mitsubishi Kasei) The above materials were melted and kneaded with three rolls, solidified and pulverized, and classified to obtain a magnetic carrier I having an average particle diameter of 35 μm.

[Manufacture II of Carrier II] parts by weight ・ Polyester resin 100 (Tm: 128 ° C, AV: 7, Tg: 64 ° C) ・ Zn-based ferrite 500 (σm: 68Oe, Hc: 135emu / g) (average particle diameter 0.6μm ) ・ Carbon black MA # 84 After kneading the above materials with 10 Henschel mixer,
The mixture was melt-kneaded with a PCM30 (extrusion kneader, / d 32.5). After cooling and solidifying, pulverize and classify, magnetic carrier with an average particle size of 55 μm
I got II.

Measurement of Charge Amount A total of 12 samples of toners 1 to 12 prepared in the examples were applied to the microcarriers I and II to a toner concentration of 10 wt%,
Put 60g in a 100cc plastic bottle and put it on a stand at 120rpm per minute,
The charge amount (Qf) after 10 minutes was determined.

 The results are shown in Table 2.

Image Test Carrier II and toners 1 to 12 are each placed in a single poly bottle so that the toner concentration becomes 7 wt%, and placed on a ball mill base to prepare a developer at 120 rpm for 10 hours. Of this developer, negatively charged toner is put into a copying machine EP870 (Minolta Camera Co., Ltd.) as it is, and a 100K sheet printing test is performed. On the other hand, for a positively charged toner, the photoconductor is replaced with an organic laminated photoconductor and 100K sheets are printed. A printing test was performed.

 Rank 5 No fog.

 4 Fog is slightly observed.

 3 Fog is slightly observed, but there is no practical problem.

 2 Lots of fog.

 1 Very much fog.

Was evaluated.

 Further, the toner charge amount after the printing durability test was examined.

 Table 3 shows the above results.

Scattering amount measurement The scattering amount of the developer after the 100K sheet printing test was determined using the following apparatus.

On a magnet roller and a magnet roller with a sleeve around it, 10 g of developer with a toner concentration of 20 wt% is set, and when the McNet is rotated at 1000 rpm, the toner that scatters is measured using a Shibata Chemical Digital Dust Meter. The value measured for 1 minute was recorded.

In the case of 500 cpm or less, even if it is a practically usable amount of scattering even in a practical machine, there is almost no trouble due to scattering, but if it exceeds 500 cpm, especially if it exceeds 1000 cpm, the scattering is severe and the surroundings of the developing device are soiled. Or cause fogging trouble.

 The results are shown in Table 3.

Filming When a part of the toner composition becomes a thin film on the photoconductor, the photosensitivity of the photoconductor decreases, the residual potential increases, and fogging occurs.

 Fog was ranked as follows.

◎ There is no filming ○ The gloss of the area where the developer touched and the area where it is not is different but there is no problem in practical use Understandable filming (halftones produce shading in the filming area and the other areas) XX There is no proper position on the exposure dial.

Fixing property test (fixing strength, high / low temperature offset) A fixing device was pressed at a speed of 45 cm / s by pressing a 60 mm fixing roller with Teflon resin coated on the upper roller and an LTV rubber roller under a pressure of 100 kg under pressure. The fixing temperature of ID1.2 and ID0.6 at the time of fixing at 175 ° C. was determined. Fixing strength is to erase the toner image by rubbing the copied image with a special device that places a load of 1 kg on sand poppy rubber. At this time, the ratio of the reflection temperature before and after rubbing with the sand poppy rubber was expressed as a percentage.

80% or more with ID 1.2 and 70 with ID 0.6 for practical use
% Or more, and the non-offset width needs to be 100 ° C. or more.

 The results are shown in Table 3.

Amount of charge decay after moisture resistance aging Charge amount (Charge amount when mixed and stirred for 30 minutes; Qf (30
) Of the developer measured at 35 ° C. and 85% environment, the lid of the bottle is opened, and the charge amount (Qf (35 ° C.-85%
−3 days)), and the amount of attenuation was determined by the following equation.

The results are shown in Table 3.

Heat resistance test Put 5g of toner in a glass sample bottle (50cc),
After leaving it in an oven at a temperature of ± 95 ° C for 24 hours, it was taken out gently, allowed to cool to room temperature, and then tilted upside down to check whether the toner dropped.

 Rank A: Falling between 0 and 5 seconds, no aggregation; Rank B: Falling between 5 and 15 seconds, no aggregation; Rank C: Falling between 15 and 30 seconds and lightly agglomerated Rank D 30 seconds to 1 minute No problem in practical use, which returned to the original toner when shaken well; Rank D 30 seconds to 1 minute. Solidified at the bottom; the results are shown in Table 3.

From the above results, regardless of the amount of volatiles in the resin,
In the early stage of the image test, fixing test, etc., there is no difference in the evaluation, but when a toner composed of resin with a high volatile content in the resin is subjected to a printing durability test with a copying machine,
Fog, carrier fog, toner filming on the photoreceptor, and reduction in sensitivity are observed.

As is clear from Table 3, at the end of the printing of 10K sheets, the toner of Comparative Example can be used practically without much difference from the product of the present invention with the toners 6, 7, 9, 12 and the like. When the above printing life is carried out, filming on the photoreceptor and spent on the carrier are promoted, and toner fog and carrier fog are deteriorated, so that they cannot be practically used and only the product of the present invention can be used. Was.

Effects of the Invention The toner according to the present invention is capable of filming on a photoreceptor,
Black spot fusion, adhesion to a carrier, etc. do not occur, excellent long-term durability, and a good image free of fog and the like can be formed.

Continuation of the front page (56) References JP-A-62-191859 (JP, A) JP-A-61-176604 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G03G 9 / 087

Claims (2)

(57) [Claims] 1. An electrophotographic toner comprising at least a thermoplastic resin and a colorant, wherein the thermoplastic resin is a styrene-acrylic copolymer resin obtained by solution polymerization, and A toner for electrostatic photography, characterized in that the reduction start temperature is 100 ° C. or higher and the weight loss on heating up to 170 ° C. is 0.3% by weight or less of the total weight. 2. The temperature at which the thermoplastic resin starts to lose weight by heating.
2. The toner for electrostatography according to claim 1, wherein the weight loss on heating up to 105 [deg.] C. and 170 [deg.] C. is 0.1% by weight or less of the total weight.