JPH0762765B2 - Polymerization toner - Google Patents

Description

The present invention relates to a polymerized toner produced by a suspension polymerization method. In particular, the present invention relates to a polymerized toner containing a large amount of two or more low-softening point compounds having different softening points and acid values.

[Prior Art] Conventionally, a toner used in a dry image forming method such as an electrophotographic method, an electrostatic printing method, and an electrostatic recording method is generally prepared by melt-mixing a colorant and other additives in a thermoplastic resin, After being uniformly dispersed, it is pulverized by a fine pulverizer and classified by a classifier so as to have a desired particle size. The resulting toner is quite good, but has potential problems due to the grinding process. That is, the toner obtained using the crushing method must have brittleness so that the material is crushed to some extent. However, if the toner is too brittle, it will be too finely pulverized, and the fine powder will have to be cut later in order to obtain a toner having an appropriate particle size distribution, which results in an increase in cost. Further, in the developing device of the copying machine, it is sometimes further pulverized. Further, when a material having a low melting point or a material having a pressure fixing property is used in order to improve the heat fixing property, a fusion phenomenon may occur in the crushing device or the classifying device, and continuous production may not be possible.

Therefore, as one means for overcoming the problems of the pulverization method, a polymerized toner produced from a polymerizable monomer by a suspension polymerization method has been proposed.

In a conventional general suspension polymerization method, a monomer composition having at least a colorant and a polymerizable monomer is granulated into a toner particle size in an aqueous medium, and a polymerization initiator or a new polymerization agent added in advance is granulated. The polymerizable monomer is polymerized by radicals generated when the polymerization initiator added to is decomposed by heat to form a polymer, thereby producing a polymerized toner. That is, since this method does not include a crushing step, the polymerized toner does not need to be brittle and has a spherical shape, so that it has excellent fluidity and uniform triboelectricity.

In recent years, for the purpose of lowering the fixing temperature of polymerized toner and / or lowering the fixing pressure in the contact roller fixing method, solid paraffin or a low molecular weight polyolefin having a shape-retaining property at room temperature in a monomer composition has been used. Although a polymerized toner containing a large amount of such a low softening point compound has been obtained, although a low fixing temperature and a low fixing pressure have been realized because of containing a large amount of the low softening point compound, on the other hand, The development durability may be deteriorated due to the softening of the toner. In order to improve this point, it has been attempted to improve the development durability by appropriately selecting the hardness of the low softening point compound, but the degree of low temperature and low pressure of fixing is reduced, and the energy saving fixing The current situation is that the effect is not very good.

[Problems to be Solved by the Invention] The present invention aims to improve the above-mentioned problems of the prior art. That is, the present invention achieves low-temperature fixing and / or low-pressure fixing, retains the function as a toner without causing fusion even if a force is applied to the toner in the developing device, and is capable of forming an image for a long time. An object of the present invention is to provide a polymerized toner that does not cause a decrease in density.

[Means and Actions for Solving Problems] The present invention provides a suspension polymerization method from a monomer composition containing at least a polymerizable monomer, a colorant, and a low softening point compound having a softening point of 40 to 130 ° C. A polymerized toner containing polymerized toner particles produced by the method, wherein the monomer composition further contains a polar polymer having a polar group, a polar copolymer having a polar group or a cyclized rubber. , Two or more of the above low softening point compounds are contained, their softening points (° C.) are T ₁ , T ₂ , ..., Tn, and their acid values (mgKOH / g) are β ₁ , β ₂ ,
, Βn, 40 ≤ T ₁ <T ₂ <... <Tn ≤ 130 and 0 ≤ β ₁ <β ₂ <... <βn ≤ 80, and the low softening point compound with the higher softening point is softened. Having a higher acid value than the low softening point compound having a lower point, the total content of the low softening point compound is a polymerizable monomer 10
50 to 3,000 parts by weight relative to 0 parts by weight, the polymerized toner particles have a pseudo capsule structure in which a low softening point compound is encapsulated by a polar polymer, a polar copolymer or a cyclized rubber, and softened. The present invention relates to a polymerized toner characterized in that a low softening point compound having a higher point encapsulates a low softening point compound having a lower softening point.

The polymerized toner of the present invention usually has a volume average particle size of about 0.1 to about 30.
It contains 50 to 3,000 parts by weight of a low softening point compound having a softening point of 40 to 130 ° C. with respect to 100 parts by weight of a polymer having a particle diameter of μm and formed from a polymerizable monomer by suspension polymerization. As described above, the polymerized toner of the present invention is excellent in blocking resistance as compared with the conventional polymerized toner, although it contains a large amount of the low softening point compound. This is because the low softening point compound is well encapsulated in the polymer obtained by polymerizing the polymerizable monomer, and the low softening point compound is not exposed on the surface of the polymerized toner particles. In the present invention, to confirm whether or not the low softening point compound is substantially encapsulated in the polymer, the obtained polymerized toner is melt-kneaded, cooled and solidified and then pulverized, and then classified and polymerized. This is done by preparing a pulverized powder having an average particle diameter similar to that of the toner, and comparing the blocking resistance of the prepared pulverized powder with the blocking resistance of the polymerized toner used as the raw material. Blocking resistance is the length remaining on a 20-mesh sieve (Taylor mesh) after 1-5 g of a sample is placed in a 100 ml container with a diameter of about 5 cm and left for one day in an environment of a temperature of 50 ° C and a relative humidity of about 60 ± 5%. It can be measured by the presence or absence of aggregates with a particle size of about 1 mm or more.

The effect of the low softening point compound used in the toner of the present invention is
It can be considered as follows. That is, the size of the softening point depends on the fixing temperature, and the acid value can be used as a measure of the hydrophilicity of the low softening point compound. The low softening point compound in the toner produced by the suspension polymerization method in an aqueous medium has a larger acid value (probably the low softening point compound A) is more likely to migrate to the surface and has a lower softening value with a smaller acid value. Point compound (probably B
And) is included. Therefore, a material having a higher softening point than B containing A, which easily migrates to the surface, can greatly contribute to the hardness and blocking resistance of the toner surface.
(In the polymerizable monomer and the low softening point compound, the former is preferably more hydrophilic.) In addition, B contained is:
It can contribute to low temperature and low pressure fixing of toner.

The above can be considered in the same manner even if the number of types of low softening point compounds increases.

Further, when the penetration of n kinds of low softening point compounds (see JIS K 2207 etc.) is α ₁ , α ₂ ... αn, it is preferable that α ₁ ≧ α ₂ ≧ ... ≧ αn.

Softening point T ₁ of the low softening point compound used in the toner of the present invention
When T ₁ <40, the blocking resistance of the toner becomes poor, and when Tn> 130, low temperature fixing of the toner becomes difficult.

On the other hand, the acid value (see JIS K 2501-80 etc.) is preferably 80 or less, and when βn> 80, the difference in hydrophilicity with the polymerizable monomer becomes small, and the weight of the polymer generated from the polymerizable monomer decreases. It tends to migrate to the surface of the toner rather than coalesced, resulting in poor blocking resistance, or the property of inhibiting polymerization when polymerizing a polymerizable monomer.

Further, when Tk <Tl and βk> βl (k <l), the hardness of the toner decreases, so the development durability decreases, and the image density decreases when images are printed for a long time. Easier to do.

The polymerized toner of the present invention can be manufactured by the following manufacturing method.

That is, at least a polymerizable monomer, low softening point 40-130
A monomer composition containing a low softening point compound having a temperature of ℃ and a colorant is dispersed and granulated in an aqueous medium heated to a high temperature, and after the granulation step is substantially completed, In this method, a polymerization initiator is added to an aqueous medium containing the monomer composition particles and adjusted to a polymerization temperature to carry out suspension polymerization.
In this case, the liquid temperature during the granulation step of the aqueous medium is preferably higher than the softening point of the low softening point compound in terms of ease of granulation and sharp particle size distribution.

In the above production method, a polymerization initiator for polymerizing the polymerizable monomer is added to the aqueous medium after granulating the monomer composition. Therefore, the temperature of the aqueous medium, which is the dispersion medium of the monomer composition, can be set to a higher temperature than in the conventional case, and granulation can be performed. Further, a classification step is provided after granulation to classify the monomer composition particles having a predetermined particle size and the monomer composition particles having a non-specified particle size, and then a polymerization initiator is added to carry out polymerization. It is also possible to mix the separated monomer composition particles having a non-specified particle size with another monomer composition before the polymerization step, and re-disperse and granulate them for reuse. Is. In addition, since it is possible to raise the temperature of the aqueous medium during the granulation step without considering the decomposition temperature of the polymerization initiator, the monomer composition may contain a substance such as paraffin or a low molecular weight polyolefin. Even a low softening point compound that is insoluble in a polymerizable monomer can be added in a large amount for granulation, and even if a large amount is added, granulation can be performed at a high temperature, resulting in a sharp An energy-saving polymerized toner capable of constant temperature fixing and / or low pressure fixing having a particle size distribution can be produced.

According to the knowledge of the present inventors, when a water-soluble polymerization initiator is used, the produced polymerized toner has a reduced moisture resistance, and thus the development characteristics and blocking resistance at high temperature and high humidity deteriorate. In order to produce a polymerized toner having excellent environmental characteristics, it is preferable to use a substantially water-insoluble polymerization initiator. When a substantially water-insoluble polymerization initiator is used, in a system in which the monomer composition is previously dissolved and mixed in the conventional manner, the polymerization initiator is evenly distributed to each monomer composition particle. However, even in a system in which a monomer composition is granulated in an aqueous medium as in the above-mentioned production method, and then a substantially water-insoluble polymerization initiator is added, each particle is satisfactorily treated. It is surprising that the polymerization reaction takes place.

As described above, the polymerization initiator used in the above production method is preferably substantially water-insoluble. The substantially water-insoluble polymerization initiator in the present invention means 100 g of water at room temperature.
It has a solubility of 1 g or less, preferably 0.5 g or less in 100 g of water, and particularly preferably 0.2 g or less in 100 g of water. When it has a solubility of more than 1 g in 100 g of water, the decomposition product of the polymerization initiator remaining on the surface of the polymerized toner particles after the completion of the polymerization undesirably lowers the moisture resistance of the polymerized toner. Further, the polymerization initiator used in the above-mentioned production method is soluble in the polymerizable monomer, and is usually used in an amount range (monomer 100
When the polymerization initiator is 2 to 5 parts by weight based on parts by weight), it has the property of being dissolved in the polymerizable monomer. As a polymerization initiator usable in the above production method, 2,2'-azobis- (2,4-
Dimethylvaleronitrile), 2,2'-azobisisobutyronitrile, 1,1'-azobis- (cyclohexane-1)
-Carbonitrile), 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile, and other azo or diazo polymerization initiators such as azobisisobutyronitrile (AIBN): benzoyl peroxide Examples thereof include peroxide polymerization initiators such as methyl ethyl ketone peroxide, isopropyl peroxycarbonate, cumene hydroperoxide, 2,4-dichlorolylbenzoyl peroxide, and lauroyl peroxide.
In the production method of the present invention, the polymerization initiator preferably has a melting point equal to or lower than the polymerization temperature (usually 50 ° C. or higher). Further, it is also preferable to use two or more kinds of polymerization initiators mixed for the purpose of controlling the molecular weight and the molecular weight distribution of the polymer, the reaction time or the like. In that case, it is preferable to use at least one having a melting point at a temperature corresponding to the liquid temperature in the aqueous medium at the time of polymerization or at a temperature lower than that. This is because the polymerization initiator is oiled at the liquid temperature during the polymerization reaction, so that the polymerization initiator or the radicals generated from the polymerization initiator is added to each of the monomer composition particles dispersed after being added to the aqueous medium. It is because it is imparted more favorably. By the way, 2,2'-azobis- (2,4-dimethylvaleronitrile) used in the below-mentioned examples is a meso form (mp 55-57 ° C) and dl
A mixture with the body (mp 74-77 ° C), the mixture being about 45
Melting starts at ℃ and finishes at about 70 ℃. The amount of the polymerization initiator used is 0.1 to 20 parts by weight, preferably 1 to 10 parts by weight, based on 100 parts by weight of the polymerizable monomer. If it is less than 0.1 parts by weight, it is difficult to uniformly apply the polymerization initiator to each of the monomer composition particles, and if it exceeds 20 parts by weight, the molecular weight of the polymerization product is too low and the polymerization reaction is too low. The tendency to occur unevenly increases.

The suspension polymerization reaction is usually carried out at a polymerization temperature of 50 ° C. or higher, and the upper limit temperature is set in consideration of the decomposition rate of the polymerization initiator.
If the set polymerization temperature is too high, the polymerization initiator will be rapidly decomposed, which is not preferable. In the above production method, since it is not necessary to allow the polymerization initiator to be present in the monomer composition during suspension granulation, the liquid temperature of the aqueous medium during granulation is, for example, 75 ° C. or higher and the monomer composition Granulation can be easily carried out by decreasing the melt viscosity of.

After confirming that the formed monomer composition particles have a predetermined particle size, the liquid temperature of the aqueous medium containing the particles is lowered to a polymerization temperature (for example, 55 to 70 ° C.), and then a polymerization initiator is added. Added. By lowering the liquid temperature of the aqueous medium, the shape retention of the monomer composition particles is improved and the coalescence of the particles is suppressed.
The polymerization reaction time varies depending on the type of polymerization initiator and the polymerization temperature, but is usually 2 to 30 hours.

In the above production method, since dispersion granulation at high temperature is possible, it is possible to produce a polymerization product usable as a toner even if a low softening point compound is added to the monomer composition in a large amount as an additive. Is possible. In the polymerized toner of the present invention, the low softening point compound can also serve as a binder resin. The low softening point compound in the present invention has a softening point of 40 measured by the ring and ball method (see JIS K 2531 etc.).
To 130 ° C, preferably 50 to 120 ° C. If the softening point is less than 40 ° C, the blocking resistance and shape retention of the toner are insufficient, and if it exceeds 130 ° C, the effect of lowering the fixing temperature and fixing pressure is small.

As the low softening point compound, paraffin, wax, low molecular weight polyolefin, modified wax having an aromatic group,
Hydrocarbon compounds with alicyclic groups, natural wax, carbon number
12 or more long-chain hydrocarbon chains [CH ₃ CH _{2 11} or CH ₂
Examples thereof include long-chain carboxylic acids having ₁₂ or more aliphatic carbon chains] and esters thereof. Different low softening point compounds are mixed and used. Specifically, paraffin wax (manufactured by Nippon Oil Co., Ltd.), paraffin wax (manufactured by Nippon Seiro Co., Ltd.), microwax (manufactured by Nippon Oil Co., Ltd.), microcrystalline wax (manufactured by Nippon Seiro Wax Co., Ltd.), hard paraffin wax (manufactured by Nippon Seiro Wax Co., Ltd.), PE-130 (Hoechst), Mitsui High Wax 110P
(Mitsui Petrochemical), Mitsui High Wax 220P (Mitsui Petrochemical), Mitsui High Wax 660P (Mitsui Petrochemical),
Mitsui High Wax 210P (Mitsui Petrochemical), Mitsui High Wax 320P (Mitsui Petrochemical), Mitsui High Wax 410P
(Mitsui Petrochemical), Mitsui High Wax 420P (Mitsui Petrochemical), Hiletz T-100X (Mitsui Petrochemical), Hiletz T-200X (Mitsui Petrochemical), Hiletz T-300X
(Mitsui Petrochemical): Petrosin 80 (Mitsui Petrochemical), Petrosin 100 (Mitsui Petrochemical), Petrosin 1
20 (Mitsui Petrochemical), Tack Ace A-100 (Mitsui Petrochemical), Tack Ace F-100 (Mitsui Petrochemical), Tack Ace B-60 (Mitsui Petrochemical), Modified Wax JC-1
141 (Mitsui Petrochemical), modified wax JS-2130 (Mitsui Petrochemical), modified wax JC-4020 (Mitsui Petrochemical), modified wax JC-1142 (Mitsui Petrochemical), modified wax JC-5020 ( Mitsui Petrochemical): Beeswax, carnauba wax, montan wax and the like can be mentioned. When a low softening point compound having a softening point of 100 ° C. or higher is used, it may be preferable to carry out dispersion granulation at a liquid temperature of the aqueous medium of 100 ° C. or higher under pressure.

The above-mentioned low softening point compound is a fixing temperature of the polymerized toner and / or
Alternatively, in order to lower the fixing pressure, 50 to 3,000 parts by weight are mixed with 100 parts by weight of the polymerizable monomer. Especially 70-1,000
It is preferably mixed in parts by weight. If it is less than 50 parts by weight, it is insufficient to lower the fixing temperature or fixing pressure of the fixing roller, and if it exceeds 3,000 parts by weight, the blocking resistance and durability tend to deteriorate.

The polymerizable monomer applicable to form the polymerized toner of the present invention is a monomer having a CH ₂ ═C <group as a reactive group, and is styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene. , P-methoxystyrene,
p-phenylstyrene, p-chlorostyrene, 3,4-dichlorostyrene, p-ethylstyrene, 2,4-dimethylstyrene, pn-butylstyrene, p-tert-butylstyrene, pn-hexylstyrene , Pn-octyl styrene, pn-nonyl styrene, pn-decyl styrene, pn-dodecyl styrene and its derivatives; vinyl esters such as vinyl acetate, vinyl propionate and vinyl benzoate. Acrylic acid,
Methacrylic acid, maleic acid, maleic acid half ester; methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, 2-ethylhexyl methacrylate, Α-Methylene aliphatic monocarboxylic acid esters such as stearyl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate; methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, acrylic Propyl acrylate, n-octyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, phenyl acrylate and other acrylates Ters; vinyl ethers such as vinyl methyl ether, vinyl ethyl ether, vinyl isobutyl ether; vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone, methyl isopropenyl ketone; N-vinyl pyrrole, N-vinyl carbazole, N-vinyl indole , N-vinyl compounds such as N-vinylpyrrolidone; vinylnaphthalenes; monomers having a reactive double bond such as vinyl groups such as acrylic acid or methacrylic acid derivatives such as acrylonitrile, methacrylonitrile and acrylamide. There is. These may be used alone or in combination of two or more. You may use a crosslinking agent as needed. Examples of the crosslinking agent include divinylbenzene, divinylnaphthalene, diethylene glycol dimethacrylate, ethylene glycol dimethacrylate and the like. The amount of the crosslinking agent added is usually 0.1 to 5 parts by weight per 100 parts by weight of the polymerizable monomer.
Further, a polymer of these polymerizable monomers may be added in a small amount in the monomer composition. Among the above-mentioned monomers, styrene, styrene having a substituent such as an alkyl group, or a mixed monomer of styrene and another monomer is preferable in view of developability and durability.

Further, a preferable polymerized toner can be obtained by adding a polar polymer having a polar group, a polar copolymer or a cyclized rubber as an additive during the polymerization of the monomer to polymerize the polymerizable monomer. Polar polymer, polar copolymer or cyclized rubber,
0.5 to 50 parts by weight, preferably 1 to 40 parts by weight is added to 100 parts by weight of the polymerizable monomer. If it is less than 0.5% by weight, it is difficult to obtain a sufficient pseudocapsule structure.
If the amount is more than parts by weight, the amount of the polymerizable monomer becomes insufficient and the properties of the polymerized toner tend to deteriorate. Polymerization is carried out by suspending a polar monomer, a polar copolymer, or a polymerizable monomer composition containing a cyclized rubber in an aqueous phase of an aqueous medium in which a dispersant having an opposite charge to the polar polymer is dispersed. Preferably. That is, the cationic or anionic polymer, the cationic or anionic copolymer, or the anionic cyclized rubber contained in the polymerizable monomer composition is a reversely charged anion dispersed in an aqueous medium. Of electrostatic or cationic dispersant electrostatically attracts the particle surface of the toner, and the dispersant covers the particle surface to prevent unification of the particles and stabilize them, as well as added polar polymer and polar copolymer. Alternatively, since the cyclized rubber gathers on the surface layer of the particles serving as the toner, the cyclized rubber becomes a kind of shell-like form, and the obtained particles become pseudo capsules. The relatively high molecular weight polar polymer, polar copolymer or cyclized rubber gathered in the surface layer of the particle encloses a large amount of the low softening point compound inside the toner particle, so that the polymerized toner particle of the present invention is resistant to blocking. Imparts excellent properties such as developability, developability, and abrasion resistance. The polar polymers (including polar copolymers and cyclized rubbers) and reversely-charged dispersants that can be used in the present invention are exemplified below. The weight average molecular weight of the polar polymer measured by GPC is 5,000.
Those having a molecular weight of up to 500,000 dissolve well in the polymerizable monomer and have durability, and thus are preferably used.

(I) As the cationic polymer, a polymer of a nitrogen-containing monomer such as dimethylaminoethyl methacrylate or diethylaminoethyl acrylate, a copolymer of styrene and the nitrogen-containing monomer or styrene, an unsaturated carboxylic acid ester, etc. And the nitrogen-containing monomer.

(Ii) Examples of anionic polymers include nitrile monomers such as acrylonitrile, halogen-containing monomers such as vinyl chloride, unsaturated carboxylic acids such as acrylic acid, unsaturated dibasic acids, and unsaturated dibasic acids. There are anhydride polymers or copolymers of styrene and said monomers.

As the dispersant, an inorganic fine powder which has the ability to disperse and stabilize the monomer composition particles in an aqueous medium and is sparingly soluble in water is preferable. The amount of dispersant added to the aqueous medium is based on water.
It is preferable to add 0.1 to 50% by weight (preferably 1 to 20% by weight).

(Iii) Examples of anionic dispersants include Aerosil # 200,
There are colloidal silica such as # 300 (manufactured by Nippon Aerosil Co., Ltd.).

(Iv) Examples of the cationic dispersant include aluminum oxide, magnesium hydroxide, and fine powder of hydrophilic positively charged silica such as aminoalkyl-modified colloidal silica treated with a coupling agent.

Instead of the above polar polymer or copolymer, a cyclized rubber having anionic property may be used.

To produce a magnetically polymerized toner, magnetic particles are added to the monomer composition. In this case, the magnetic particles also serve as a coloring agent. The magnetic particles that can be used in the present invention include substances that are magnetized when placed in a magnetic field, such as iron,
Examples include powders of ferromagnetic metals such as cobalt and nickel, and powders of alloys and compounds such as magnetite, hematite and ferrite. Magnetic fine particles having a particle size of 0.05 to 5 μm, preferably 0.1 to 1 μm are used. The content of the magnetic particles is 10 to 60% by weight, preferably 20 to 50% by weight, based on the weight of the toner. Further, these magnetic fine particles may be treated with a treating agent such as a silane coupling agent or a titanium coupling agent, or an appropriate reactive resin. In this case, depending on the surface area of the magnetic fine particles and the density of the hydroxyl groups existing on the surface, it is 5% by weight or less (preferably 0.1% or less).
With a treatment amount of 1 to 3% by weight, sufficient dispersibility in the polymerizable monomer and the low softening point compound is obtained, and the physical properties of the toner are not adversely affected. The polymerized toner contains a colorant, and as the colorant, conventionally known dyes, carbon black, and pigments such as grafted carbon black obtained by coating the surface of carbon black with a resin can be used. . The colorant is contained in an amount of 0.5 to 30% by weight based on the polymer and the low softening point compound. A charge control agent and a fluidity modifier may be added (internally added) to the toner, if necessary. The charge control agent and the fluidity modifier may be used as a mixture (external addition) with toner particles. Examples of the charge control agent include metal complexes of organic compounds having a carboxyl group or a nitrogen-containing group, metal-containing dyes, nigrosine and the like. Examples of fluidity modifiers and auxiliary agents for cleaning the surface of the latent image bearing member (photoreceptor) include colloidal silica and fatty acid metal salts.
Further, for the purpose of increasing the amount, a filler such as calcium carbonate or fine powder silica may be blended in the toner in an amount of 0.5 to 20% by weight. Further, in order to prevent the toner particles from coagulating with each other and improve the fluidity, a fluidity improver such as Teflon (registered trademark) fine powder or zinc stearate powder may be added. When a low softening point compound such as a low molecular weight hydrocarbon compound (for example, a weight average molecular weight of 500 to 5,000) or a carnauba wax that improves releasability at the time of heat roll fixing is used as the low softening point compound, for example, the hydrocarbon compound is hydrophobic and low. Since it has a molecular weight, it is less likely to mix with the polymer produced by the polymerization, and is less likely to be exposed on the particle surface as compared with a polar polymer, a polar copolymer or a cyclized rubber, and will be pushed into the polymerized toner. As a result, even if it contains a large amount of the low softening point compound, it is excellent in durability and blocking resistance because it is encapsulated. Then, the toner comes out of the inside at the time of fixing, and the fixability and offset property are remarkably improved. In other words, it serves as an offset agent and a fixing agent.

When the polymerized toner of the present invention is applied to a two-component developer, it can be applied at a compounding ratio of a normal toner and a carrier, and for example, 1 to 500 parts by weight of the carrier is mixed with 1 part by weight of the toner. .

The suspension method is a colorant (including a magnetic material in the present invention), 50 to 3,000 parts by weight of the low-softening point compound and 100 parts by weight of the polymerizable monomer are uniformly dissolved, Alternatively, the dispersed monomer composition is used in an aqueous medium containing 0.1 to 50% by weight of a suspension stabilizer (for example, a sparingly soluble inorganic dispersant) (for example, 5 ° C or higher, preferably 10 ° C or higher than the polymerization temperature).
It is heated to a temperature higher by ~ 30 ° C) by a usual stirrer, homomixer, homogenizer or the like. Preferably the agitation speed, time and aqueous medium so that the particles of the melted or softened monomer composition have the desired toner particle size, generally less than 30 μm (eg volume average particle size 0.1-20 μm). Adjust the temperature. Then, the liquid temperature of the aqueous medium is lowered to the polymerization temperature while stirring is carried out to the extent that the sedimentation of the particles is prevented so that the state of the dispersion stabilizer is almost maintained by the action of the dispersion stabilizer. The polymerization temperature is
50 ° C or higher, preferably 55 to 80 ° C, particularly preferably 60 to 75
The temperature is set to ° C, and a substantially water-insoluble polymerization initiator is added with stirring to carry out polymerization. After the completion of the reaction, the produced toner particles are collected by an appropriate method such as washing, removal of the dispersion stabilizer, filtration, decantation, centrifugation and the like, and dried to obtain the polymerized toner of the present invention. In the suspension polymerization method, usually 200 to 3,000 parts by weight of water is used as an aqueous dispersion medium with respect to 100 parts by weight of the polymerizable monomer and the low softening point compound.

Also suitable stabilizers such as polyvinyl alcohol,
Sodium salts such as gelatin, methyl cellulose, methyl hydropropyl cellulose, ethyl cellulose, carboxymethyl cellulose, polyacrylic acid and salts thereof, starch, gum alginate, zein, casein, tricalcium phosphate, talc, barium sulfate, bentonite, hydroxylated It is also possible to use any one or a mixture of aluminum, ferric hydroxide, titanium hydroxide, thorium hydroxide and the like contained in an aqueous medium to such an extent that the production method of the present invention is not adversely affected.

In order to disperse the inorganic dispersion stabilizer uniformly, a surfactant may be used to the extent that it does not adversely affect the production method of the present invention. This is for promoting the intended action of the above dispersion stabilizer, and specific examples thereof include sodium dodecylbenzenesulfonate, sodium tetradecyl sulfate, sodium pentadecyl sulfate, sodium octyl sulfate, and allyl-alkyl-poly. Sodium ether sulfonate, sodium oleate, sodium laurate, sodium caprate, sodium caprylate, sodium caproate, potassium stearate, calcium oleate, 3,3-disulfone diphenylurea-4,4-diazo-bis-amino -8-Naphthol-6-
Sodium sulfonate, ortho-carboxybenzene-
Examples thereof include azo-dimethylaniline, 2,2,5,5-tetramethyl-triphenylmethane-4,4-diazo-bis-β-naphthol-sodium disulfonate, and the like. However, it should be noted that when a hydrophilic organic stabilizer or surfactant is used, the moisture resistance of the polymerized toner decreases.

Further, a water-soluble polymerizable monomer simultaneously undergoes emulsion polymerization in water, and since the resulting suspension polymer is contaminated with small emulsion-polymerized particles, a water-soluble polymerization inhibitor, such as a metal salt, is added. It is also possible to prevent emulsion polymerization in the aqueous phase. It is also possible to add glycerin, glycol or the like to water in order to reduce the viscosity of the aqueous medium and prevent the particles from coalescing during polymerization. Further, salts such as NaCl, KCl and Na ₂ SO ₄ may be added to the aqueous medium in order to reduce the solubility of the easily soluble polymerizable monomer in water. It is also possible to add a Bronsted acid such as hydrochloric acid to the aqueous medium in order to enhance the ionization of the polar groups of the polar polymer or cyclized rubber in the monomer composition. In particular, the addition of Bronsted acid such as hydrochloric acid to the aqueous medium is effective in further enhancing the effect of the anionic polymer, anionic copolymer or cyclized rubber.

The polymerized toner of the present invention can be applied to a known dry electrostatic image developing method. For example, two-component developing method such as cascade method, magnetic brush method, microtoning method; one-component developing method using magnetic toner such as conductive one-component developing method, insulating one-component developing method, jumping developing method; powder cloud Method and fur brush method; a non-magnetic one-component developing method in which the toner is carried on the toner carrier by electrostatic force and is transferred to the developing section for development; an electric field curtain is transferred to the developing section by the electric field curtain method and developed. It can be applied to the developing method. Although it is particularly preferably applicable to the dry developing method, it may optionally be used as a toner for the wet developing method.

[Examples] Hereinafter, the present invention will be described in detail based on Examples.

Example 1 The above components were mixed with an attritor at a temperature of 85 ° C. for 4 hours to prepare a monomer composition. Obtained monomer composition 254
20 parts by weight of amino-modified silica (100 parts by weight of Aerosil 200 treated with 5 parts by weight of aminopropyltriethoxysilane) and 25 parts by weight of 0.1N hydrochloric acid are contained.
The mixture was put into an aqueous medium of 1200 parts by weight of distilled water heated to 85 ° C. while stirring with a TK homomixer, and after the addition, the mixture was stirred at 10,000 rpm for 15 minutes to carry out dispersion granulation.

After granulation, the liquid temperature was lowered to 60 ° C, and 3 parts by weight of 2,2'-azobis- (2,4-dimethylvaleronitrile) and 1.5 parts by weight of 2,2'-azobisisobutyronitrile were used as a polymerization initiator. It was added to the aqueous medium and stirred for 30 minutes. Further, stirring was changed to paddle blade stirring, and stirring was carried out at 60 ° C. for 10 hours to complete the polymerization.

The obtained polymerized toner-containing aqueous medium is cooled and dehydrated,
Washing with sodium hydroxide solution to dissolve and remove amino-modified silica, washing with water, dehydration, and drying (if necessary, fine particles of unnecessary component particles are removed) to obtain a volume average particle diameter of 8 μm (100 μm (Measured with a Coulter counter using the aperture of No. 1) to obtain a polymerized toner. The polymerized toner obtained had about 1 part of wax based on 100 parts by weight of polystyrene.
It contained 00 parts by weight. Also, the toner obtained is 50 ° C.
No blocking occurred even if left in the environment for 1 day. From this, it was found that the paraffin wax was encapsulated in the carnauba wax, and the carnauba wax was encapsulated in the cyclized rubber and contained in the polymerized toner particles.

10 parts by weight of the obtained polymerized toner, zinc stearate powder 0.
1 part by weight, hydrophobic silica (Aerosil R972, manufactured by Nippon Aerosil Co., Ltd.) 0.1 part by weight, and insulating carrier particles having an average particle size of 40 μm (formed from 75 parts by weight of iron tetraoxide and 25 parts by weight of epoxy resin) 90 parts by weight Were mixed to prepare a developer, and development was performed under the following conditions.

The developing device shown in FIG. 1 was used. The image carrier has a selenium photoreceptor, the peripheral speed of the image carrier 1 is 100 mm / sec, the maximum potential of the electrostatic charge image formed on the image carrier is +750 V, the outer diameter of the sleeve (developer carrier) 2. 20mm, and the peripheral speed is
100 mm / sec, the magnetic flux density in the vertical direction on the sleeve surface of the N and S poles of the magnet roller 3 is 1000 gauss, and the thickness of the developer layer is 20.
The development was carried out at 1400 Vpp with 0 μm, the gap between the sleeve 2 and the image carrier 1 of 300 μm, the bias voltage applied to the sleeve was +200 V DC component and 3.0 kHz AC component. The electrostatic latent image is well developed, the developed toner image is electrostatically transferred to plain paper, and the toner image on the plain paper is fixed to a fixing roller and a pressure roller having a silicon rubber surface layer under a pressure of 15 kg / cm ^2. It was fixed through a heat and pressure roller fixing device (nip width 7 mm, paper traveling speed 150 mm / sec). The fixing temperature is shown in Table 1.

In the developing device of FIG. 1, the toner T having the external additive is quantitatively supplied to the lower chamber by the supply roller 8 and the elastic member 7 and mixed with the carrier to form the developer 4. A DC bias power supply 5 applies a DC bias, and an AC bias power supply 6 applies an AC bias to the sleeve 2 and the doctor blade 10 that incorporate the magnet roller 3. The developer 4 is conveyed as the sleeve 2 rotates in the A direction, and is used for developing the electrostatic latent image of the image carrier 1 including the aluminum cylinder 11 and the selenium photoconductor 12. The developer layer regulating member 9 also serves as an outer wall of the developing device.

In addition, Table 1 shows the image density retention rate after 1000 images were printed in this developing system.

Comparative Example 1 Paraffin wax 120 ° F. in Example 1 was replaced with 50 parts by weight of paraffin wax and 50 parts by weight of carnauba wax.
Example 1 was repeated except that the amount was 100 parts by weight. A blocking test, a fixing test and a development durability test were conducted using the obtained toner, and the results are shown in Table 1.

Comparative Example 2 The procedure of Example 1 was repeated, except that 50 parts by weight of 120 ° F. paraffin wax and 50 parts by weight of carnauba wax in Example 1 were replaced by 100 parts by weight of carnauba wax. A blocking test, a fixing test and a development durability test were conducted using the obtained toner, and the results are shown in Table 1.

Comparative Example 3 In place of 50 parts by weight of 120 ° F paraffin wax and 50 parts by weight of carnauba wax in Example 1, 50 parts by weight of PO wax S-20 (manufactured by Nippon Oil Co., Ltd., softening point 62-67 ° C, acid value 55-70) was used. And POPKO S-
5 (Noda Wax Co., Ltd., softening point 80 ° C, acid value 3.8) 50
The same procedure as in Example 1 was carried out except that the parts by weight were used. A blocking test, a fixing test and a development durability test were conducted using the obtained toner, and the results are shown in Table 1.

Comparative Example 4 The procedure of Example 1 was repeated, except that 50 parts by weight of 120 ° F paraffin wax and 50 parts by weight of carnauba wax in Example 1 were used instead of 1600 parts by weight. When a blocking test was conducted on the obtained toner, it was blocked, and the fixing test and the development durability test were not conducted.

Comparative Example 5 A blocking test, a fixing test and a development durability test were carried out in the same manner as in Example 1 except that 50 parts by weight of 120 ° F paraffin wax and 50 parts by weight of carnauba wax were used in Example 1 respectively. The results are shown in Table 1.

[Advantages of the Invention] As described above, by using n kinds of low softening point compounds having limited softening points and acid values, conventionally, they can be used alone in terms of toner blocking characteristics and development durability. A low softening point compound which could not be used can be used, a wide range of samples can be selected, and contradictory properties such as low temperature and / or low pressure fixing and development durability can be simultaneously satisfied.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing a developing device used in Examples and Comparative Examples of the present invention. 1 ... Photosensitive drum, 2 ... Sleeve, 3 ... Magnet roller, 4 ... Developer, 5,6 ... Development bias power supply, 7
...... Elastic member, 8 …… Supply roller, 9 …… Developer layer regulating member, 10 …… Doctor blade, 11 …… Aluminum cylinder, 12 …… Selenium photoreceptor

Claims (2)

[Claims] 1. Polymerization containing polymerized toner particles produced by a suspension polymerization method from a monomer composition containing at least a polymerizable monomer, a colorant and a low softening point compound having a softening point of 40 to 130 ° C. A toner, wherein the monomer composition further contains a polar polymer having a polar group, a polar copolymer having a polar group, or a cyclized rubber, and contains two or more kinds of the low softening point compounds. , Its softening point (℃) is T ₁ , T ₂ , ..., Tn, and its acid value (mgKOH / g) is β ₁ , β ₂ ,
, Βn, 40 ≤ T ₁ <T ₂ <... <Tn ≤ 130 and 0 ≤ β ₁ <β ₂ <... <βn ≤ 80, and the low softening point compound with the higher softening point is softened. Having a higher acid value than the low softening point compound having a lower point, the total content of the low softening point compound is a polymerizable monomer 10
50 to 3,000 parts by weight relative to 0 parts by weight, the polymerized toner particles have a pseudocapsule structure in which a low softening point compound is encapsulated by a polar polymer, a polar copolymer or a cyclized rubber, A polymerized toner characterized in that a low-softening point compound having a higher point encapsulates a low-softening point compound having a lower softening point. 2. The low softening point compound having a lower softening point has a penetration degree larger than that of the low softening point compound having a higher softening point. Polymerized toner.