JPH0468361A - Electrophotographic toner - Google Patents

Abstract

PURPOSE:To attain the improvements in the fixing property and the resistance for the offset property by allowing the weight average molecular weight of a fixing resin of a toner to be in a constant range, specifying the gradient of the average viscosity of the toner particle and allowing milder region than the gradient of the average viscosity to be present thereon. CONSTITUTION:The toner incorporates the fixing resin and a coloring agent. The fixing resin is in a range of 50,000-5,000,000 at the weight average molecular weight and the gradient of the average viscosity of the toner at a range of 100-150 deg.C is in a range of 0.02-0.07/ deg.C and the region where the gradient of the viscosity is mild is formed at >=10%. One material which shows a different physical property to a fixing resin component of the toner is present thereon and in a rapid region temp. at the gradient of the viscosity of the toner the fixing resin component allowing the viscosity characteristic of the whole toner to be degraded with the raising temp. affects and in a mild region temp. at the gradient of the viscosity, the fixing resin component hardly changing the viscosity characteristic so much is affected. Thus even though the heating condition of the fixing roller is changed the toner is not influenced and the fixing property is enhanced and the resistance to the offset property is enhanced.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a toner used in electrophotography, and more specifically, toner used in an image forming apparatus etc. having a toner heat fixing mechanism. The present invention relates to an electrophotographic toner that exhibits excellent fixing properties and sufficient anti-offset properties.

(Prior art) Electrophotographic copying machines and the like used in electrophotography usually include a developing sleeve that appropriately conveys toner, a photoconductor on which an electrostatic latent image is formed, and a photoconductor that transfers toner from the electrostatic latent image on the photoconductor. A fixing mechanism is provided to fix the transferred toner to the transfer paper. Toners, which are popular in this field, are formed of particles consisting of a fixing resin, a colorant, and, if necessary, a charge control agent, a magnetic material, and a release agent.

The toner is usually electrically attracted to the electrostatic latent image portion of the photoreceptor, and then transferred to a transfer material (paper) and conveyed to a fixing mechanism. The toner on the transfer paper is heated in a short time by a fixing roller of a fixing mechanism, and the fixing resin in the toner is heated and melted. A portion of the molten fixing resin permeates the transfer paper, and when the fixing roller or the like is separated, it coagulates and is bound to the transfer paper.

Such toner is normally required to have fixing properties to transfer paper and anti-offset properties during transfer.

Good fixing of the toner is achieved when the fixing resin is melted to some extent by a fixing roller or the like and sufficiently adhered to the transfer paper. Also, the offset of the fixing roller is
This occurs when the resin hardens and sticks to the roller when it is not sufficiently melted by the fixing roller, or when the fixing resin loses its near-liquid viscosity and wets the roller. Therefore, offset resistance of the toner is achieved when the fixing resin has appropriate cohesiveness and cold offset and hot offset do not occur.

(Problems to be Solved by the Invention) Conventionally, in order to improve the fixing properties and anti-offset properties of toner, there is a fixing resin containing low molecular weight hydrogenated polybutadiene (Japanese Unexamined Patent Publication No. 103354/1982).
. The purpose of this is to improve the fixing performance by quickly melting the low molecular weight fixing resin component by the fixing roller. In addition, by incorporating a reactive prepolymer (Japanese Unexamined Patent Publication No. 110948/1982), or by using the ratio of styrene and 2-ethylmethahexyl methacrylate as a binder resin within a certain range (
(Japanese Unexamined Patent Publication No. 80-57855), one having anti-offset properties has already been proposed.

However, in conventional toners, a low molecular weight fixing resin is simply added (or present) to the particles, and there is still room for improvement.

For example, when the fixing roller is heated, the toner melts quickly and permeates into the transfer paper, but because the toner's cohesiveness and anchoring effect are insufficient, when the fixing roller separates, the toner is not fully coagulated. offset is likely to occur. Furthermore, problems tend to occur in fixing performance.

Furthermore, if the heating conditions of the fixing roller change slightly during fixing, the fixing resin in the toner changes its permeability and cohesiveness, which may reduce its fixing properties and anti-offset properties. During fixing, the fixing roller is kept at a certain constant temperature, heating the toner particles and melting them appropriately, but the fixing roller surface is heated from the time the toner starts fixing to the end of fixing a large amount of toner, especially during fixing. It is unavoidable that the temperature changes slightly between the start and end of fixing, and it is difficult for the toner to always be heated at a constant temperature and for a constant period of time from the fixing roller.

Therefore, in view of the above circumstances, an object of the present invention is to provide an electrophotographic toner having excellent fixing properties and anti-offset properties.

Another object of the present invention is to provide an electrophotographic toner that is highly compatible with fixing rollers and the like.

(Means for Solving the Problems) According to the present invention, there is provided a toner containing a fixing resin and a colorant, wherein the fixing resin has a weight average molecular weight (M
ooo to 5,000,000, and the viscosity gradient (absolute value) of the toner in the temperature range of 100 to 150°C satisfies the range of 0.02 to 0.07/°C, and in the temperature range Provided is an electrophotographic toner characterized by having a region where the viscosity gradient is slower than the average viscosity gradient of the toner by 10% or more.

The present invention also includes: The toner particles can be characterized by being spherical toner particles formed by suspension polymerization.

Incidentally, the viscosity gradient of the toner indicates the ratio of 1°g logarithm of viscosity to temperature. For this reason, the temperature difference (X+
The amount of change in viscosity with respect to Δ)-X°C is 1.

g(Y+Δ) pois −1ogY pois, and the viscosity gradient has a value expressed by the formula %) = (log(Y+Δ)/Y)/Δ°C. Note that K has a monotonous decreasing relationship as the temperature increases, and the viscosity is measured by a flow tester.

(Function) In the present invention, it is important that the weight average molecule j1 of the fixing resin in the toner satisfies the range of 50,000 to 5,000,000. The resin in the actual toner particles during fixing is heated to a temperature of approximately 100°C to 150°C.If the weight average molecular weight (Mw) of the fixing resin is within the above range, the toner particles is melted appropriately during fixing, and can maintain permeability and cohesiveness suitable for fixing properties.

In the present invention, in addition to satisfying the weight average molecular weight (Nw) range of the fixing resin, the average viscosity gradient (absolute (
It is important that 11) is in the range of 0.02 to 0.07/°C.

The viscosity of the toner monotonically decreases as the fixing resin gradually melts as the temperature rises, and the viscosity gradient takes a negative value. Therefore, it is understood that the variation in viscosity due to temperature is affected by the absolute value of the viscosity gradient, and if the absolute value is large, the viscosity change with respect to the temperature of the toner becomes large. In the present invention, j[1
As shown in the figure, the average viscosity gradient of the toner is 0.02 to 0.
．． 07/"C. As shown in FIG. 1, the toner in this range has less viscosity change with temperature than conventional toner particles, and this also shows that the toner of the present invention has a lower temperature during fixing. It is understood that the change does not cause a sudden change in viscosity.Furthermore, the fact that the viscosity gradient of the entire toner in the above temperature range is slow means that there may be tolerance in setting the heating conditions of the fixing roller, etc. Easy to understand.

Furthermore, in the present invention, it is important that the viscosity gradient region that is slower than the average viscosity gradient in the temperature range occupies 10%, particularly 15% or more.

During toner fixing, the toner is heated for a short period of time by a fixing roller at approximately 180°C. Due to this heating, the toner starts to melt at around 100"C, and when the toner is in a moderately molten state, the resin penetrates into the transfer paper, and when the fixing roller separates, it exerts a certain cohesive force and anchor effect, and the transfer paper It adheres well to the sides.

In this case, it is understood that some of the fixing resin components of the toner of the present invention exhibit different physical properties, and in a temperature range where the viscosity gradient of the toner is steep, the viscosity characteristics of the entire toner can be changed by increasing the temperature. It is understood that the fixing resin component that lowers the temperature is acting on the toner, and that the fixing resin component that does not change the viscosity characteristics of the toner as a whole changes much when the temperature rises in a region where the viscosity gradient is slow, although it changes the melting state.

It is believed that when the resin component whose viscosity changes drastically acts, toner permeability is quickly achieved. On the other hand, due to the existence of the above-mentioned slow region, even if the toner is heated by the high-temperature fixing roller and the temperature has already risen, the viscosity of the toner remains at a constant value compared to conventional products. The maintenance of this constant viscosity has an effect on permeability, cohesiveness, and anchoring effect during toner fixation, although the details are unknown, but transfer Since paper toner has fixing properties and does not cause hot or cold offset, it is important to keep the viscosity as unchanged as possible so that the toner's permeability, cohesiveness, and anchoring effect can be properly adjusted during fixing. What is achieved is understood. Further, if the region of slow viscosity gradient exists in 10% or more, especially 15% or more of the entire temperature range, the above-mentioned effect can be sufficiently achieved. Therefore, compared to conventional toner, even if the heating conditions of the fixing roller change, the toner is not affected in any way, and its fixing properties are improved and offset resistance is improved.

7 In the present invention, it is more desirable to obtain the toner by a suspension polymerization method. Suspension polymerization method.

Since the particle size of the toner can be made relatively uniform and the particles can be made to be nearly perfectly spherical, there is an advantage of improving fluidity. Moreover, as shown in FIG. 2, it is possible to form the fixing resin in a state in which a low molecular weight substance and a high molecular weight substance are present in the fixing resin. Such a fixing resin molecular weight distribution improves the relationship between the melting state and the viscosity state, and has a positive effect on fixing properties and anti-offset properties.

Suspension polymerization involves suspending vinyl monomers, colorants, or other ingredients that can become a fixing resin.

This is carried out by using initiators and crosslinking agents that have a defined half-life. By such polymerization method,
It is possible to satisfy the above-mentioned weight average molecular weight (Mw) range of the fixing resin and to obtain a viscosity change gradient within the range of the toner particles.

(Preferred Embodiments of the Invention) Preferred embodiments of the present invention will be described in detail below. The toner of the present invention comprises a fixing resin, a colorant, and, if necessary, a charge control agent, a magnetic material, and other materials.

In the fixing resin used in the present invention, those having an ethylenically unsaturated bond are used alone or in combination of two or more.

Suitable examples of such monomers include monovinyl aromatic monomers, acrylic monomers, vinyl ester monomers, vinyl ether monomers, diolefin monomers, and monoolefin monomers. body etc.

As a monovinyl aromatic monomer, in the formula, R1 is a hydrogen atom, a lower alkyl group, or a halogen atom, and R2 is a hydrogen atom, a lower alkyl group, a halogen atom, an alkoxy group, an amino group, a nitro group, a vinyl group, or It is a carboxyl group.

monovinyl aromatic hydrocarbons such as styrene, α-methylstyrene, vinyltoluene, α-chlorostyrene,
o-m-p-chlorostyrene, p-ethylstyrene, sodium styrene sulfonate, divinylbenzene alone or in combination of two or more, and other monomers mentioned above include the following: Each can be mentioned.

Formula % Formula % (2) In the formula, R3 is a hydrogen atom or a lower alkyl group, and R4 is a hydrogen atom, a hydrocarbon group having up to 12 carbon atoms, a hydroxyalkyl group, a vinyl ester group, or an aminoalkyl group. Monomers such as acrylic acid, methacrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, phenyl acrylate, methyl methacrylate, hexyl methacrylate, 2-methacrylate -Ethylhexyl, 3-ethyl hydroxyacrylate, γ-propyl hydroxyacrylate, δ-butyl hydroxyacrylate, β-hydroxyethyl methacrylate, γ-aminopropyl acrylate, γ-N,N-diethylaminopropyl acrylate , ethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, etc.

formula %formula% In the formula, R6 is a hydrogen atom or a lower alkyl group, vinyl propionate, etc.

Vinyl ethers of the formula, CH2=CH0-R5...(4) where R6 is a monovalent hydrocarbon group having up to 12 carbon atoms, such as vinyl methyl ether, vinyl ethyl ether, vinyl-n-butyl ether, Vinyl phenyl ether, vinyl cyclohexyl ether, etc.

Diolefins, particularly butadiene, isoprene, chloroprene, etc., of formula % formula % (5) in which each of R, , R, , R is a hydrogen atom, a lower alkyl group, or a halogen atom.

Vinyl esters, such as vinyl formate, vinyl acetate, R7゜CH2=C-R++...
(6) In the formula, each of R4° and R7 is a hydrogen atom or a lower alkyl group. Monoolefins, especially ethylene, propylene, imbutylene, butene-1, pentene-1,4-methylpentene-1 etc., etc.

The weight average molecular weight (Mw) of the fixing resin composed of such resin components is 50,000 to 5,000,000.
It is particularly important to satisfy the range of 100°000 to 2,000,000. The fixing roller, etc. of the device used in the present invention is generally heated to a temperature of about 180°C, and the temperature is 100°C relative to the resin in the actual toner particles during fixing.
It acts in the range of 150°C to 150°C. If the weight average molecular weight (Mw) of the fixing resin is smaller than the above range, the toner particles made of the fixing resin will quickly melt during fixing and will extremely lose viscosity, making hot offset apt to occur. On the other hand, if the weight average molecular weight (M) of the fixing resin is larger than the above range, the toner particles will have a large amount of insoluble portions and cold offset will easily occur.

Furthermore, the weight average molecular weight (Mw) distribution of the fixing resin is
It is more desirable to have two peaks as shown in the figure. That is, it is desirable that low molecular weight polymers and high molecular weight polymers coexist. Further, in the molecular weight peak of the polymer, the minimum peak molecular weight value is 50,000 or less,
Preferably 3000 to 50000, particularly preferably 5
000 to 40,000, and the maximum peak molecular weight is 200,000 or more, preferably 2oO00o to 7,000,000, particularly preferably 300,000 to 5
The range is 000000. A fixing resin having a molecular weight distribution within the above range further improves the fixing properties, offset resistance, bronking resistance, and abrasion resistance of the toner. Moreover, it has a great influence on obtaining a suitable viscosity change gradient in the temperature range described below. In addition, it is desirable that a high molecular weight component having a molecular weight higher than the maximum molecular weight peak exists in the range of 10 to 40% of the total, which can improve blocking resistance and durability and provide stable performance over a long period of time. can.

As the coloring agent used in the present invention, dyes and pigments known per se are used, and specific examples thereof can be shown below.

a. Black pigments carbon black, acetylene black, lamp black, aniline black.

b, yellow pigments yellow lead, zinc yellow, cadmium yellow, yellow iron oxide, mineral first yellow, nickel titanium yellow, navels yellow naphthol yellow S, Hansa yellow 10G, benzidine yellow G, quinoline yellow lake, permanent yellow NGO, tartrazine rake.

C9 orange pigment red yellow lead, molybdenum orange, permanent orange GTR, pyrazolone orange, palkan orange,
Indanthrene Brilliant Orange RK, Benzidine Orange G, Indanthrene Brilliant Orange GR
.

d, Red pigment red pigment, cadmium red, red lead, mercury cadmium sulfide, Palkan Orange 4R, Lysol Red, Pyrazolone Red, Watching Red Calcium Salt, Lake Red D, Brilliant Carmine 6B, Eosin Lake, Rhodamine Lake B, Alizarin Lake, Brilliant Carmine 3B.

e, purple pigment manganese violet, fast violet B, methyl violet lake.

f, blue pigment navy blue, cobalt blue alkali blue lake, Victoria blue lake, phthalocyanine blue metal-free phthalocyanine blue, phthalocyanine blue partially chlorinated product,
First Sky Blue Indance Tremble-BC.

g, green pigment chrome green, chromium oxide, pigment green B,
Malachite green lake, final yellow green G0 h, white pigment zinc white, titanium oxide, antimony white, zinc sulfide.

19 constitution raw materials Palite powder, barium carbonate, clay silica, white carbon, talc, aluminum white.

These colorants can be added in an amount of 1 to 20 parts by weight, particularly preferably 5 to 15 parts by weight, per 1 part by weight of O to the fixing resin component.

Components other than the colorant used in the present invention include a magnetic material, a charge control agent, and the like as appropriate.

As the magnetic material pigment, for example, triiron tetroxide (Fes04
), iron sesquioxide (y -Fe203), iron zinc oxide (Z
nFe204), iron yttrium oxide (YsF15sO
+2), iron cadmium oxide (Gd3FesO,2), iron copper oxide (CuFe204), iron oxide complex (PbPe+
20+, ), neodymium iron oxide (NbFe03), barium iron oxide (BaPe+20+o), magnesium iron oxide (MgPe20a), manganese iron oxide (MnFe20)
a), lanthanum iron oxide (LaFeOs), iron powder (Fe
), :2 Baltic powder (Co), Nickel powder (Ni
), but any of these known fine powders of magnetic materials can be used in the present invention.

In addition, in order to adjust the chargeability of the toner, a charge control agent known per se, such as metal-containing azo dye (alkyl)salicylic acid, metal compound naphthenic acid metal soap, fatty metal soap, resin acid soap, etc. is added. You can also do that. These charge control agents can be used in an amount of 0.1 to 10 parts by weight, particularly preferably 0.5 to 5 parts by weight, per 100 parts by weight of the polymerizable monomer. Further, in order to provide an offset prevention effect to the toner, a release agent such as low molecular weight polyethylene, low molecular weight polypropylene, various waxes, silicone oil, etc. can be included. These anti-offset agents are preferably used in an amount of 0.1 to 10 parts by weight, particularly preferably 0.5 to 8 parts by weight, per 100 parts by weight of the polymerizable monomer.

For toner particles composed of the above components, the viscosity was measured using a flow tester at a temperature of 100 to 1.
In the range of 50°C, the average viscosity gradient is 0.02 to 0.
．． 07/°C1, particularly 0.03 to 0.06/°C, is preferably used. A toner having a viscosity gradient within such a range has a small viscosity change with respect to temperature (this means that the viscosity does not change rapidly due to temperature changes during fixing.On the other hand, if the viscosity gradient is lower than the above range, It becomes impossible to obtain sufficient permeability to the toner.

In the present invention, it is also important that the toner has a slow region where the viscosity gradient (absolute (II)) is less than or equal to the average viscosity gradient in the above temperature range by 10%, particularly preferably 15% or more.Toner If the region where the viscosity gradient is slower than the average viscosity gradient does not exist within the above range, the fixing performance and offset resistance of the toner will not be sufficiently improved during fixing.

FIG. 1 is a characteristic diagram showing the relationship between temperature and viscosity of the toner according to the present invention. As shown in Figure 311, the viscosity change curve A of the toner of the present invention has an average viscosity gradient (absolute value) of 0.
The absolute value of the gradient is 0.030/°C or less in the temperature range of 120°C to 125°C and the temperature range of 135°C to 140°C, which is lower than the average viscosity gradient value. In contrast, the average viscosity gradient (absolute) of the conventional toner curve B is 0 in the temperature range of 110 to 150°C.
．． 07045/℃, which is a very high value.
Moreover, no slow region is observed in the average viscosity gradient. Therefore, when the toner particles of the present invention are heated by the fixing roller, there are some states in which the viscosity does not change much and the viscosity is maintained at a predetermined level, whereas the toner particles of the conventional toner, that is, the average viscosity gradient is less than 0.077°C. If it is higher than that, the viscosity changes drastically and affects permeability, cohesiveness, and anchoring effect, which are factors for fixing properties and anti-offset properties.

In the present invention, it is also preferable that two regions where the viscosity gradient is 0.03/°C or less exist as shown in WI211m. For example, a first region can exist in a temperature range of 115-125°C and another region can exist in a temperature range of 130-140°C. Toners have alternating regions of slow viscosity gradient.

It has good permeability into the transfer paper, has good cohesiveness when the fixing roller is removed, improves fixing properties, and the fixed toner does not easily separate from the transfer paper. Further, no dirt was observed on the fixing roller, and no offset was observed.

In manufacturing the toner of the present invention, a known method can be used, in which the weight average molecular weight (M) of the fixing resin is selected to be within the above range, and the fixing resin, colorant, and other materials are The toner particles can be obtained by melt-kneading and pulverizing the toner particles so that a viscosity change gradient within the above range can be obtained in advance in the above temperature range.In addition, in the present invention, in addition to the crosstalk method, It is further desirable to obtain toner particles directly by turbid polymerization.

The suspension polymerization method has the advantage that the particle size of the toner can be made relatively uniform, and the particles can be made into particles that are close to perfect spheres. Also a coloring agent in the polymer chain.

The product has excellent durability and fluidity because the mold release agent and the like are incorporated, and the compounding ingredients do not come off.

Furthermore, as described above, the fixing resin shown in FIG. 2 can be formed with a low molecular weight substance and a high molecular weight substance present.

Suspension polymerization is carried out by suspending vinyl monomers, colorants, or other ingredients that can become fixing resins, using initiators and crosslinking agents with a predetermined half-life.

(A) Polymerization initiator A polymerization initiator is important in the suspension polymerization of the present invention, and specific polymerization initiators include 2,2-azobis(2,4
-dimethylvaleronitrile), 2,2'-azobisisobutyronitrile, ■, 1'-azobis(cyclohexane-1-carbonitrile), 2,2'-azobis-4-methoxy-2,4-dimethylvalero Azo compounds such as nitrile, 2,2-azobis(2-cyclopropylpropionitrile), cumene hydroperoxide, t-butyl hydroperoxide, dicumyl peroxide, di-t-butyl peroxide, benzoyl peroxide, lauroyl peroxide Radical polymerizable initiators such as peroxides such as In addition, combinations with ionizing radiation such as γ-rays and accelerated electron beams, and various sensitizers are also used.

Further, the amount of the polymerization initiator such as an azo compound or peroxide may be a so-called appropriate amount of catalyst, and is generally 0.00% per monomer charged.
It is preferably used in an amount of 1 to 30% by weight, especially 2 to 20% by weight. Among the polymerization initiators used in the present invention, at least one initiator having a half-life of 30 minutes or less at a temperature of 80° C. is used in suspension polymerization.

The half-life of 30 minutes or less means the half-life under the influence of a polymerization accelerator when the polymerization accelerator is included.

(B) Crosslinking agent: A crosslinking agent is added during suspension polymerization to promote polymerization of vinyl monomers. The amount of the crosslinking agent used is desirably in the range of 0.01 to 50% by weight, particularly 0.1 to 10% by weight, based on the monomers charged.

Examples of crosslinking agents include divinyl compounds such as divinylbenzene, divinyl ether, and divinyl sulfone, diallyl compounds such as allyl phthalate and diallyl carbinol, diacrylic esters such as diacrylphenol, ethylene glycol dimethacrylate, and trimethylol. Any known per se such as propane triacrylate, glycidyl methacrylate, glycidyl acrylate, etc. can be used, but diacrylic esters are particularly preferred.

(C) Other compounding agents used in the polymerization step: In the present invention, polymerization accelerators, crosslinking agents, or chain transfer agents may be used as necessary, and these may be known per se, and are added in appropriate amounts. be able to.

Furthermore, in the polymerization step of the present invention, surfactants and dispersants known per se may be added in order to perform granulation and the like well.

In suspension polymerization, the dispersion medium is usually water-soluble,
Water, alcohol, etc. are used. The vinyl monomer is usually suspended in the dispersion medium in an amount of 50 g to 500 g per 1 liter of the dispersion medium, although it varies depending on the type thereof.

During suspension granulation, surfactants and dispersion stabilizers are used, and these are known per se, but especially fatty acid-based and sulfonic acid-based anionic surfactants are used as surfactants. It is desirable to use a sparingly soluble inorganic salt or the like as a dispersion stabilizer.

Granulation in a dispersion medium during suspension polymerization is performed using a homomixer.
This is carried out using a high-speed shear stirrer such as a homogenizer, and the granulation size is preferably in the range of 1 to 50 μm, particularly 3 to 20 μm. By setting the granulation diameter within the above range, toner particles of an appropriate size can be obtained.

During suspension polymerization, at least one type of initiator with a half-life of 30 minutes or less, a slow polymerization initiator, a crosslinking agent, etc. are also blended as described above. These blends are suitably carried out before or after granulation.

The reaction temperature is preferably 30 to 100°C, particularly 40 to 90°C. Further, in the present invention, the reaction temperature may be changed during the reaction. Examples are shown below.

(Example) Examples are shown below. Note that the scope of the present invention is not limited to the scope of the examples.

(Example 1) The toner components shown below were formulated so that the average viscosity gradient of the toner was 0.02 to 0.07/°C at a temperature of 100 to 150°C.

Styrene 82 parts by weight 2-ethylhexyl methacrylate 18 parts by weight Carbon black, MA-100 (manufactured by Mitsubishi Kasei Corporation, trade name) 5 parts by weight Charge control agent, Bontron S-40 (manufactured by Orient Corporation, trade name) 1 part by weight Divinylbenzene 0.89 parts by weight 2-ethylene glycol dimethacrylate 2.0 parts by weight Polymerization initiator, (2,2'-azobis(4-methoxy 2
8 parts by weight of 4-dimethylvaleronitrile) 6 parts by weight of tricalcium phosphate in 400 parts by weight of water.
Part by weight and sodium dodecylbenzenesulfonate 0.0
The mixture was added to a continuous phase containing 1 part by weight, granulated using a homomixer, and polymerized at 80°C for 8 hours. Then, the obtained polymer was treated with a dilute acid, washed with water, and dried to obtain toner particles.

As a result, when the particle size characteristics were measured using a Coulter counter, the median diameter on a volume basis was found to be:

had a sharp particle size distribution of 11.3 μm.

In addition, when the molecular weight distribution was measured by GPC, fJ
As shown in Figure 2, it has multiple peaks, and the overall weight average molecular weight (Mw) is 690,000, with the largest peak on the high molecular side at 2,300,000, and the lowest on the low molecular side. The peak was at the 31,000 position. The proportion of high molecular weight components having a molecular weight equal to or higher than the maximum molecular weight peak (shaded area in the figure) to the total was 18.9%.

As shown in FIG. 1, the curve of the viscosity change gradient of toner particles shows a slow monotonous decreasing curve, and the average viscosity change gradient is 0.
At 04987°C, the region where the viscosity gradient is slower than the average temperature is 1.
It existed at a temperature of 20° C. to 125° C. and a temperature of 135° C. to 140° C., and the total proportion of that region was 20%.

Next, 0.1 parts by weight of hydrophobic silica is mixed per 100 parts by weight of the obtained toner, and a carrier in which ferrite particles are coated with silicone resin is mixed with a toner concentration of 3%.
The mixture was mixed to obtain a developer.

And electronic photocopying 1! A printing durability test of 20,000 sheets was conducted using DC-1205 (manufactured by Sanda Kogyo Co., Ltd., trade name), and the fixing properties and anti-offset properties were evaluated.

Regarding fixing properties, a transfer paper with a toner image formed thereon is passed through and fixed, an adhesive tape is pressed against the formed fixed image, and then peeled off, and the fixed image is compared before and after peeling off. The density was determined by measurement using a reflection densitometer (manufactured by Tokyo Juishiki), and was evaluated by calculating. Further, fixing roller stains were determined by visually observing the fixing roller after printing and by checking the stains on the back of the paper during printing. In addition, offset resistance was evaluated based on whether an offset phenomenon occurred during continuous copying. At the same time, image characteristics were also evaluated. Also,
Regarding blocking resistance, put 20 g of toner in a glass cylinder with an inner diameter of 26.5 mm in an oven at 60°C, place a 100 g weight on the toner, leave it for 30 minutes, and then remove and scrape off the cylinder. Evaluation was made based on whether the toner crumbled. The results are shown in Table 1.

(Example 2) Styrene 82 parts by weight 2-Ethylhexyl methacrylate 18 parts by weight Divinylbenzene 0.89 parts by weight 2-
Ethylene glycol dimethacrylate 2, 0 parts by weight Polymerization initiator [2, Cuazobis (4-methoxy 2,4-
(dimethylvaleronitrile) 8 parts by weight A mixture of these was polymerized in the same manner as in Example 1 to synthesize suspension polymerized balanced fat particles.

100 parts by weight of the obtained suspension polymerized resin particles, 5 parts by weight of carbon black (MA-100 manufactured by Mitsubishi Kasei Corporation), and 1 part by weight of a charge control agent (Bontron 5-40 manufactured by Orient Corporation) were mixed and heated at around 150°C. The mixture was melt-kneaded on a roll mill.

After cooling this mixture, it was pulverized with an air jet mill and subjected to air classification to obtain a volume-based median diameter of 11.2 μm.
I got the toner. When the viscosity change of this toner particle was measured, it showed a curve similar to that shown in FIG.

Next, a developer was prepared and evaluated in the same manner as in Example 1. The results are shown in Table 1.

(Comparative example) 100 parts by weight of a styrene-acrylic copolymer having a molecular weight distribution as shown in Figure 2, carbon black (MA-
100 manufactured by Mitsubishi Chemical Corporation) and 1 part by weight of a charge control agent (Bontron 5-40 manufactured by Orient Corporation) were mixed,
The mixture was melt-kneaded on a roll mill at around 0'C. After cooling this mixture, it was pulverized with an air jet mill and subjected to air classification to obtain a toner of 10.5 yU-m.

The curve of the viscosity change gradient of toner particles is a monotonically decreasing curve as shown in FIG. 1, and the average viscosity gradient is 0.07045.
There was no region where the viscosity gradient was slow between 115°C and 145°C.

Next, a developer was prepared and evaluated in the same manner as in Example 1. The results are shown in Table 1.

Table-1 In this table, if fixability is maintained at 95% or more, ○, 90
% or more was rated as Δ, and when it fell below 90%, it was rated as ×.

In addition, the blocking resistance was evaluated as ○ if the cylinder crumbled as it was when the cylinder was removed, △ if it crumbled when pressed with a finger, and × if it did not crumble.

(Effects of the Invention) According to the present invention, the weight average molecular weight (
Mw) satisfies a certain range, and the temperature is 100 to 150℃
The average viscosity gradient of toner particles is set to 0 in the range of
．． 02 to 0.07/°C, and a region where the viscosity gradient is slower than the average viscosity gradient is 10% or more, so that during fixing, the toner has an appropriate melting and viscosity range, and the resin easily spreads onto the transfer paper. While penetrating into the paper, the toner has a certain degree of cohesiveness and anchoring effect, so the toner fixes well to the transfer paper and does not easily peel off from the transfer paper. Further, offset is less likely to occur. Furthermore, even if the heating conditions of the fixing roller differ slightly, the toner is less affected by the fixing device and has excellent device compatibility.

[Brief explanation of drawings]

FIG. 1 is a characteristic diagram showing temperature and viscosity changes of toner particles according to the present invention, and FIG. 2 is a characteristic diagram showing molecular weight distribution of toner particles according to the present invention.

Claims (2)

[Claims] (1) A toner containing a fixing resin and a colorant,
The fixing resin has a weight average molecular weight (Mw) in the range of 50,000 to 5,000,000 and a temperature of 100
A region where the average viscosity gradient (absolute value) of the toner in the range of 150° C. satisfies the range of 0.02 to 0.07/° C., and the viscosity gradient is slower than the average viscosity gradient of the toner in the temperature range. An electrophotographic toner comprising 10% or more of. (2) The toner according to claim 1, which is spherical toner particles formed by suspension polymerization.