JPH01303447A - Toner for developing electrostatic charge image - Google Patents

Abstract

PURPOSE:To improve fixability, offset resistance and durability by incorporating a styrene resin having the specific peak of a mol.wt. distribution, storage modulus and loss modulus as a main resin component into the toner. CONSTITUTION:This toner contains the styrene resin in which at least the peak of the mol.wt. distribution exists in a range of <=1X10<4> and >=5X10<5> and which has >=1X10<3>dyn/cm<2> storage modulus and <=5X10<3>dyn/cm<2> loss modulus as the essential resin component. This polymer is a copolymer of >=1 kinds of styrene monomers and other unsatd. monomers. The styrene monomer is exemplified by styrene, alpha-methyl styrene, etc. The other unsatd. monomers are exemplified by methyl acrylate, ethyl acrylate, etc. The polymer are so synthesized that the mol.wt. peak on the low mol.wt. side attains <=10,000, more particularly <=5,000 and the mol.wt. peak of the high mol.wt. side attains >=500,000, more particularly >=2,000,000. The toner having the excellent fixability and offset resistance and excellent mechanical strength and flowability as well is obtd. in this way.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a toner for developing electrostatic images used in electrophotography, electrostatic printing, electrostatic recording printing, etc. The present invention relates to a toner that has excellent properties and durability.

(Prior art) Conventionally, in a single copying machine using electrophotography, fixing is used to visualize an electrostatic latent image formed on a photoreceptor containing selenium and an organic photoconductor using a dry development method. A toner in which additives such as colorants are dispersed in a resin is used.

The above-described developing method involves developing an electrostatic latent image formed on the photoreceptor by charging and exposure with the toner, transferring the developed toner image to a support such as transfer paper, and using a heating roller and/or The toner image is fixed on the support by pressing, and the electrostatic latent image is visualized. After the toner image is transferred to the support, the remaining toner on the photoreceptor is scraped off by a cleaning member in order to clean the toner remaining on the photoreceptor in preparation for the next image forming process. .

The above-mentioned toner has a coloring agent, a charge control agent, and, if necessary, a toner characteristic imparting agent such as magnetic particles dispersed in a fixing resin.
These toners are resin particles with a particle size of 0 μm, and these toners are used for developing electrostatic latent images as two-component developers that are mixed with a carrier to form a developer, or as one-component developers that are made only of toner.

In the developing process, in order to faithfully reproduce the original image, these toners must exhibit excellent fluidity in the developing device, equalize the amount of charge on each toner particle, and reduce the amount of uncharged and weakly charged particles. It is necessary to prevent the occurrence of fog due to toner migration to areas other than the latent image, the accumulation of toner in the developing device due to excessively charged particles, and the reduction in image density due to a decrease in the amount of adhesion to the latent image. In addition, in order to obtain a clear image, the toner is quickly fixed on the transfer material in the fixing process, and the toner is transferred to the surface of the fixing roller, and the transfer material passing through the subsequent fixing process is smeared by the toner on the roller. It is necessary that so-called offset development does not occur.

Therefore, the fixing resin, which is the main component of the toner, is required to have delicate hardness and heat melting properties, and the toner obtained by crushing and classifying the fixing resin in which colorants etc. are dispersed is It is necessary for the toner to exhibit good fluidity without generating fine powder or agglomerating when subjected to mechanical impact due to is required to exhibit cohesive properties.

Therefore, many proposals have been made regarding the molecular weight and molecular weight distribution of polymers used as fixing resins. For example, in JP-A-56-16144, the molecular weights are 103-8 XIO' and 105-8 XIO'.
It has been proposed to use a fixing resin having at least one extreme value in each region of the image.

(Problems to be Solved by the Invention) However, although the toner according to the above-mentioned publication is certainly effective to some extent in terms of impact resistance and fluidity in the developing device, the transfer of the molten toner during fixing is Satisfactory results have not yet been obtained regarding the adhesion to materials and the cohesiveness between molten toner, and considerations from such viewpoints have not been mentioned.

The present invention has good mechanical strength and toner fluidity,
The object of the present invention is to obtain a toner that has excellent adhesive strength and offset resistance of a molten toner onto a transfer material, has a wide fixing temperature range, and has excellent fixing properties.

(Means for Solving the Problems) According to the present invention, at least the peak of the molecular weight distribution is I
XIO' or less and 5 The objectives of the invention are achieved.

(Function) As the present inventors investigated the binder resin of toner, they discovered that not only the molecular weight distribution of the binder resin but also the elastic modulus of the resin itself, specifically the storage modulus and loss modulus It has been found that it greatly contributes to the adhesive force to the transfer material during toner fixation and the cohesive force between molten toners, and affects fixing performance and offset resistance.

The storage modulus and loss modulus here are one of the viscoelastic characteristic functions defined in general vibration experiments of objects with viscoelasticity, and the real part of the complex modulus is the storage modulus,
The imaginary part is called the loss elasticity.

The present invention will be explained in detail below.

The polymer used in the present invention is a styrenic polymer with excellent chargeability and crushability, and is a copolymer of one or more of the styrene monomers listed below and other unsaturated monomers. can be,
Examples of styrenic monomers include styrene, α-methylstyrene, 0-methylstyrene, P-methylstyrene, p-
Ethyl styrene, p-methoxystyrene, 0, m, p-
Examples of other unsaturated monomers include methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, phenyl acrylate,
Methyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, ethyl β-hydroxyacrylate, propyl T-hydroxyacrylate, butyl σ-hydroxyacrylate, ethyl β-hydroxymethacrylate, ethylene glycol dimethacrylate ,
Acrylic monomers such as tetraethylene glycol dimethacrylate, vinyl formate, vinyl acetate, etc.
Vinyl esters such as vinyl propionate, vinyl ethers such as vinyl n-butyl ether, vinyl phenyl ether, vinyl cyclohexacyl ether, diolefins such as butadiene, isoprene, chloroprene, and ethylene, propylene, isobutylene, butene. -1, pentene-1,4-methylpentene-
Examples include monoolefins such as No. 1 and the like. Divinylhenzene is also particularly useful as a crosslinking agent.

The polymer used in the present invention has a molecular weight peak on the low molecular weight side of 10.000 or less, particularly 5.000 or less, and a molecular weight peak on the high molecular weight side of 500.000 or more by a known polymerization method. In particular, the 2,000° meltability is improved, and the ease of flow when melted and the reduction in mechanical strength of the toner are compensated for by the high molecular weight polymer component.

The inventors of the present invention focused on the adhesion of the molten toner to paper and the cohesive force between the toners when fused, based on the above-mentioned considerations regarding the molecular weight of the polymer, and further investigated the storage elastic modulus of the polymer. By setting it to X 103 dyn/cm2 or more, the cohesive force of the toner during melting can be increased, and adhesion of the molten toner to the fixing roller (high temperature offset) can be extremely well prevented, and the loss modulus can be reduced to 5 X 103 dyn/cm2.
It has been found that by setting the amount to be less than m'', the molten toner quickly penetrates and adheres to the transfer material, improving fixing performance.

The above-mentioned elastic modulus varies depending on the copolymer structure and structural unit of the polymer even if the polymers have the same molecular weight and molecular weight distribution, and is a value unique to the polymer itself.

If the storage elastic modulus is lower than I x 103 dyn/cm2, the cohesiveness between the molten toner will be poor, especially at high speeds.
Offcent tends to occur during high temperature fixing.

Furthermore, if the loss modulus is higher than 5 x 103 dyn/cm2, the adhesion to the transfer material becomes poor, the fixing performance deteriorates, and the lower limit temperature increases.

In order to improve toner fixing properties and triboelectric charging properties, other polymers may be added to the above polymers to serve as binder resins. For example, olefin polymers such as polyethylene, chlorinated polyethylene, polypropylene, and ionomers Coalescence, polyvinyl chloride, polyester, polyamide, polyurethane, epoxy resin, diallyl phthalate resin, silicone resin, ketone resin, polyvinyl butyral resin, phenolic resin, rosin modified phenolic resin, xylene resin, rosin modified maleic acid resin, rosin ester, petroleum Various polymers such as resins can be used.

As the coloring agent added to the binder resin whose main component is the styrene polymer, the following various pigments and dyes (hereinafter simply referred to as coloring pigments) may be added to the monomer. Can be used.

Black pigment carbon blank, acetylene black, lamp black, aniline black.

Yellow pigments yellow lead, zinc yellow, cadmium yellow, yellow iron oxide, mineral first yellow, nickel titanium yellow, fuichi bulls yellow, naphthol yellow S1 Hansa yellow 10G, benzidine yellow G1 quinoline yellow lake, permanent yellow NCG, tartrazine lake.

Orange pigment red yellow lead, molybdenum orange, permanent orange GTR, pyrazolone orange, halcan orange, indanthrene brilliant orange RK, benzidine orange G1 indanthrene brilliant orange GK.

Red pigment red pigment, cadmium red, red lead, cadmium sulfide, permanent orange 4R, resol red,
Pyrazolone Red, Watching Red Calcium Salt,
Lake Red D, Brilliant Carmine 6B, Eosin Lake, Rhodamine Lake B, Alizarin Lake, Brilliant Carmine 3B.

Purple pigment Manganese Purple, First Violet B1 Methyl Violet Lake.

Blue pigments navy blue, cobalt blue, alkali blue lake, Victoria blue lake, phthalocyanine blue, metal-free phthalocyanine blue, phthalocyanine blue partially chlorinated product, first sky blue, indanthremble-BC
.

Green pigment chrome green, chromium oxide, pigment green B1
Malachite Green Lake, Fanal Yellow Green G.

white pigment Zinc white, titanium oxide, antimony white, zinc sulfide.

Extender pigments Palite powder, barium carbonate, clay, silica, white carbon, Kuruk, aluminum white.

As the magnetic material pigment, for example, triiron tetroxide (Fe: +0
4>, iron sesquioxide (7-Fe203), zinc iron oxide (ZnFezOa), iron indolium oxide (Y3Fe
, 0+z), cadmium oxide (Gd:1FesO+z)
, iron oxide (CuFez04), iron oxide complex (PbFe
+z paste), cadmium oxide (NdFeO, ), barium iron oxide (IllaFe+zO+J), magnesium iron oxide (MgFezO□), manganese iron oxide (MnF
ezOn), lanthanum iron oxide (LaFeO:+), iron powder (Fe), cobalt powder (Co), nickel powder (Ni
), but in the present invention, any of these known fine powders of the (n feed material f4) can be used.

The ratio of binder resin to colorant can vary considerably, but generally speaking, 1 to 30 parts by weight, especially 2 to 20 parts by weight per 100 parts by weight of binder resin are preferably used. Ru.

Further, a charge control agent may be added to control the charging characteristics of the toner. For example, nigrosine, monoazo dyes, zinc hexadecyl succinate, alkyl esters or alkylamides of naphthoic acid, nitrofumic acid, N,N'-tetramethyldiaminehensiphenone, N,N'-tetramethylhenzidine, triazine, salicylic acid. Strongly polar substances called charge control agents are used in this field, such as metal complexes. These charge control j17
One agent contains 0.00 parts per 100 parts by weight of binder resin. Ol to 10 parts by weight, especially 0.1 to 5 parts by weight are preferably used.

Furthermore, a polymer having a polar group may be added for the purpose of charge control.

For example, it may be a homopolymer of polar monomers described below, or a copolymer of the above-mentioned polymerizable monomer and polar monomer.

Anion - The anionic monomer used in the present invention includes unsaturated carboxylic acids such as acrylic acid and methacrylic acid, unsaturated dibasic acids such as maleic acid and fumaric acid, maleic anhydride, itaconic anhydride, etc. Anhydrides of unsaturated dibasic acids, styrene sulfonic acid, 2-acrylamido-2-2methylpropanesulfonic acid, mono-(2-methacryloyloxyethyl)
Acid phosphate, 2-methacryloyloxyethylsuccinic acid, etc. can be mentioned.

Left lJz 111 Raw dimethylamino (meth)acrylate, diethylaminoethyl (meth)acrylate, diethylaminopropyl (meth)acrylate, N-aminoethylaminopropyl (meth)acrylate, vinylpyridine, 2-vinylimidazole, 2-hydroxy-3 -Nitrogen-containing monomers such as acryloxypropylmethylammonium chloride and the like can be mentioned.

The polar group-containing polymer made of the above-mentioned polar monomer etc. is appropriately determined by taking into account the solubility with the polymerizable monomer that can form the fixing resin mentioned above and the charging characteristics of the produced toner. , generally used in an amount of 0.1 to 10 parts by weight per 100 parts by weight of the polymerizable monomer.

Various additives including the above-mentioned coloring agent are melt-mixed with the binder resin in a known melt-kneading machine, and the resulting kneaded composition is cooled, then dissolved in a solvent in a known pulverizer, and spray-dried. After granulation by the method, it is classified and the particle size is 5.
It is used as a toner of 8 to 20 μm, particularly 8 to 20 μm.

Further, an abrasive substance may be added to the toner of the present invention, if necessary, in order to clean the photoreceptor.

For example, talc, kaolin, barium sulfate, etc. may be used, but aluminum silicate, surface-treated aluminum silicate, titanium dioxide, calcium carbonate, antimony trioxide, barium titanate, calcium titanate, strontium titanate, oxidized Magnesium, calcium silicate, zinc oxide, etc. are preferred, and colloidal silica and surface-treated hydrophobic silica are particularly preferred. Addition of the above-mentioned abrasive substance, especially hydrophobic silica, also improves the fluidity of the toner and developer. The abrasive material has an average particle size of 1 to 100 μm.
In particular, those having a diameter of 10 to 30 μm are preferred. These abrasive substances contain 0.01 parts by weight per 100 parts by weight of the toner.
It is preferable to add 1 to 1 part by weight. If the amount of the abrasive substance added is less than 0.01 part by weight, the fluidity of the toner will be poor, and if it exceeds 1 part by weight, the photoreceptor will tend to be easily damaged.

Further, in order to adjust the electrical resistance of the toner, a carbon blank, aluminum oxide, etc. may be sprinkled on the toner.

These electrical resistance adjusters are 0.00% per 100 parts by weight of toner.
It is preferable to add 1 to 1 part by weight.

Hereinafter, the present invention will be explained in more detail with reference to Examples and Comparative Examples. In addition, the elastic modulus in Examples and Comparative Examples is diameter 3
．． Temperature 175”C~177 with 0cm parallel disk
Under the conditions of °C1 frequency 1.0Hz, total angle 1, Odeg, Rheobexie Analyzer RPX-7 manufactured by Iwamoto Manufacturing Co., Ltd.
This is the value measured with 05 (product name).

(Example 1) Styrene-acrylic copolymer 100 with molecular weight peaks near 8,000 and 900,000, storage modulus of 3.0X103, and loss modulus of 2.0XIO3 in the molecular weight distribution measured by GPC. Parts by weight, carbon plastic as colorant.

7 parts by weight, 1 part by weight of a negative polar dye as a charge control agent,
Low molecular weight polypropylene as anti-offset agent0.
5 parts by weight were melt-mixed using a heated roll mill, then coarsely pulverized and classified to produce a toner having an average particle size of 18 μm.

The toner obtained above has an average particle size of 50 to 80 μm.
When combined with the ferrite carrier of m, the toner concentration is 4.
The developer was 5%.

DC-5585 high-speed copying machine (55 A4 horizontal sheets per minute) equipped with a heat-pressing type fixing device using the above developer
(manufactured by Sanda Kogyo Co., Ltd., product name) and a low-speed copying machine (20 A4 sheets per minute) DC-2055 (manufactured by Sanda Kogyo Co., Ltd., product name)
Image copying was carried out at Each item of liquidity was evaluated.

High temperature off-cent occurrence temperature: Increase the set temperature of the heating roller of each copying machine from 100°C in 2.5°C increments, pass the transfer paper with the toner image transferred, and check the image at the leading edge on the transfer paper. The temperature at which offset occurs was determined by determining whether or not the surface portion of the fixed heat roller caused toner stains on the non-image area of the transfer paper due to the rotation of the roller.

Fixing strength dependent temperature: Increase the set temperature of the heating roller of each copying machine from 100°C in 2.5°C increments, pass the transfer paper on which the toner image has been transferred and fix it, and the formed fixing Press the adhesive tape onto the image, then peel it off, and measure the image density of the fixed image before and after peeling off using a reflection densitometer (
(manufactured by Tokyo Juishiki Co., Ltd.), and the temperature at which the temperature was 90% or higher was determined by the following.

The characteristics of the toner in the developing device were determined by visual observation and the obtained copied image.

○: Good, △: Fair, ×: Poor.

There was little generation of fine powder toner, and the fluidity remained good.

Table 1 shows the results for each item.

(Example 2) In the molecular weight distribution measured by GPC, the molecular weight peak has maximum points near 4,900 and 2,100,000, the storage modulus is 2.5X103, and the loss modulus is 4.0XIO.
', 100 parts by weight of styrene-acrylic copolymer, 8 parts by weight of carbon black as a coloring agent, 1 part by weight of a negative polar dye as a charge control agent, and 0.5 parts by weight of low molecular weight polypropylene as an anti-offset agent are heated. After melting and mixing with a roll mill, it is roughly pulverized and classified until the average particle size is 1.
A 7 μm toner was prepared.

Then, in the same manner as in Example 1, the developer was adjusted to have a toner concentration of 4.5%, image copying was performed, and each item was evaluated. In the printing durability test, even when 50,000 sheets were continuously copied, there was almost no differentiation in the developing device.
Furthermore, the toner had good fluidity and clear images were continuously obtained.

The results are shown in Table-1.

(Example 3) In the molecular weight distribution measured by GPC, the molecular weight peak has maximum points near 6000 and 600000, the storage modulus is 1.5X10'', and the loss modulus is 3.5X103
100 parts by weight of styrene-acrylic copolymer, 7 parts by weight of carbon black as a coloring agent, 1 part by weight of a negative polar dye as a charge control agent, and 0.5 parts by weight of low molecular weight polypropylene as an anti-offset agent were mixed using a heated roll mill. After melting and mixing, coarsely pulverize and classify to obtain an average particle size of 18 μm.
created toner.

Then, in the same manner as in Example 1, the developer was adjusted to have a toner concentration of 4.5%, an image was copied, and each item was evaluated. In addition, in continuous copying of 50,000 sheets,
Although a small amount of fine powder was generated in the developing device, the toner fluidity did not change significantly and the image was satisfactory.

The results are shown in Table-1.

(Comparative Example 1) In the molecular weight distribution measured by GPC, the molecular weight peak has maximum points near 8000 and 900000, the storage elastic modulus is 5.0xlO2, and the left elastic modulus is 3.0xIO'
100 parts by weight of styrene-acrylic copolymer, 7 parts by weight of carbon black as a coloring agent, 1 part by weight of a negative polar dye as a charge control agent, and 0.5 parts by weight of low molecular weight polypropylene as an anti-offset agent were mixed using a heated roll mill. After melting and mixing, coarsely pulverize and classify to obtain an average particle size of 19 μm.
created toner.

Then, in the same manner as in Example 1, the developer was adjusted to have a toner concentration of 4.5%, an image was copied, and each item was evaluated. In the 50,000-sheet printing durability test, a small amount of fine powder was generated in the developing device, and the fluidity also varied, but it did not significantly affect the copied images.

The results are shown in Table-1.

(Comparative Example 2) In the molecular weight distribution measured by GPC, the molecular weight peak has maximum points near 8000 and 1,000,000, the storage modulus is 2.5XIO', and the loss modulus is 6.0XIO3
100 parts by weight of styrene-acrylic copolymer, 7 parts by weight of carbon black as a coloring agent, 1 part by weight of a negative polar dye as a charge control agent, and 0.5 parts by weight of low molecular weight polypropylene as an anti-offset agent were mixed using a heated roll mill. After melting and mixing, coarsely pulverize and classify to obtain an average particle size of 18 μm.
created toner.

Then, in the same manner as in Example 1, the developer was adjusted to have a toner concentration of 4.5%, an image was copied, and each item was evaluated. In the 50,000-sheet printing durability test, a small amount of fine powder was generated in the developing device, and the fluidity also varied, but it did not significantly affect the copied images.

The results are shown in Table-1.

(Comparative Example 3) A styrene-acrylic copolymer with molecular weight peaks near 8000 and 900000 in the molecular weight distribution measured by GPC, a storage modulus of 5.3X103, and a loss modulus of 6.2XIO'. 100 parts by weight of carbon black as a coloring agent, 1 part by weight of a negative polar dye as a charge control agent, and 0.5 parts by weight of low molecular weight polypropylene as an anti-offset agent were melt-mixed in a heated roll mill, and then coarsely ground. , to prepare a toner having an average particle size of 17 μm.

Then, in the same manner as in Example 1, the developer was adjusted to have a toner concentration of 4.5%, an image was copied, and each item was evaluated. In the 50,000-sheet printing durability test, a small amount of fine powder was generated in the developing device, and the fluidity varied, but it did not affect the copied image much.

The results are shown in Table-2.

(Comparative Example 4) In the molecular weight distribution measured by GPC, the molecular weight peak has maximum points near 11,000 and 450,000, the storage modulus is 3.2X103, and the loss modulus is 2.5X103.
100 parts by weight of a styrene-acrylic copolymer, 7 parts by weight of carbon black as a coloring agent, 1 part by weight of a negative polar dye as a charge control agent, and 0.5 parts by weight of low molecular weight polypropylene as an offset prevention agent were mixed using a heated roll mill. After melt-mixing, coarsely pulverize and classify to obtain an average particle size of 18 μm.
created toner.

Then, in the same manner as in Example 1, the developer was adjusted to have a toner concentration of 4.5%, an image was copied, and each item was evaluated. In the 50,000-sheet printing test, 300
When the number of sheets exceeded 00, the image density began to decrease and furthermore, image fogging occurred. Further, the fluidity of the developer was also unstable.

The results are shown in Table-2.

(Comparative Example 5) In the molecular weight distribution measured by GPC, the molecular weight peak is 1, the maximum point is around 420,000, and the storage modulus is 4.
．． 2x1x103, 100 parts by weight of a styrene-acrylic copolymer with a loss modulus of 4.0x103, 7 parts by weight of carbon black as a coloring agent, 1 part by weight of a negative polar dye as a charge control agent, as an anti-offset agent. After melt-mixing 0.5 parts by weight of low molecular weight polypropylene using a heated roll mill, the mixture was coarsely pulverized and classified to produce a toner having an average particle size of 18 μm.

Then, in the same manner as in Example 1, the developer was adjusted to have a toner concentration of 4.5%, an image was copied, and each item was evaluated. In the 50,000-sheet printing test, 300
Image fogging occurred after the number of sheets exceeded 00. Also,
Fine powder toner was generated in the developing device, and the fluidity of the developer was also significantly reduced.

The results are shown in Table-2.

As is clear from the table, there are at least two molecular weight peaks of the fixing resin, and each peak exists in a limited molecular weight range. It can be seen that by using the following fixing resins, it is possible to obtain toners that have excellent fixing properties and anti-offset properties, greatly expand the fixing temperature range, and also have excellent mechanical strength and fluidity.

(Hereinafter, blank space) (Effects of the Invention) As is clear from the table, according to the present invention, fixing is possible at low temperatures, the adhesion of the molten toner to the transfer material during fixing is strengthened, and furthermore, The cohesive force of the molten toner is also increased, the fixable temperature range is expanded, and the fixing rate is also significantly improved.

Furthermore, since the toner has good mechanical strength and fluidity, clear images can be stably obtained, especially in long-term continuous copying or high-speed copying.

Claims (1)

[Claims] At least the peak of the molecular weight distribution is 1×10^4 or less,
It is in the region of 5×10^5 or more, and the storage modulus is 1×10
＾3dyn/cm＾2 or more, loss modulus is 5×10＾3
A toner for developing electrostatic images characterized by containing a styrene resin having a dyn/cm^2 or less as a main resin component.