JPH0354347B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a toner for developing electrostatic images formed in electrophotography, electrostatic printing, electrostatic recording, and the like. [Prior Art] The process of developing an electrostatic image is a process in which charged fine particles are attracted by electrostatic attraction and adhered to the surface of an electrostatic image support, thereby visualizing the electrostatic image. Specific methods for carrying out such a development process include a wet development method using a liquid developer in which a pigment or dye is finely dispersed in an insulating organic liquid;
cascade method, which uses a powder developer consisting of a toner containing a colorant such as carbon black dispersed in a binder made of natural or synthetic resin;
There are dry developing methods such as the bristle brush method, magnetic brush method, impression method, and powder cloud method. The image visualized in the developing step may be fixed on the support as it is, but usually it is transferred to another support such as transfer paper and then fixed. In this way, the toner is not only subjected to the development process, but also to the subsequent processes, that is, the transfer process and the fixing process, so the toner has not only good developability but also the following processes: It is required to have good transfer and fixing properties. Among these, the conditions related to fixing properties are the most severe, and many studies and results have been published in the past on improving the fixing properties of this toner. It is generally advantageous to fix the toner image formed in the developing process or the image transferred thereto by a heat fixing method, and this heat fixing method includes a non-contact heat fixing method such as oven fixing, and a heat roller fixing method. There is a contact heat fixing method. The contact heating fixing method is excellent in that it has high thermal efficiency, and is particularly capable of high-speed fixing and is suitable for fixing in high-speed copying machines. Furthermore, since a relatively low-temperature heat source can be used, this method requires less power consumption, making it possible to downsize the copying machine and save energy. Further, even if paper accumulates in the fixing device, there is no risk of fire, which is also preferable. Although the contact heating fixing method is preferable in various respects as described above, this method has a serious problem of occurrence of an offset phenomenon. This is a phenomenon in which a portion of the toner constituting the image is transferred to the surface of the heat roller during fixing, and this is transferred again to the transfer paper or the like that is fed next, staining the image.
In order to prevent this offset phenomenon, various proposals have been made and some have been put into practical use. One is to perform fixing while applying a release oil such as silicone oil to the surface of a heated roller, and the other is to provide the toner itself with offset prevention performance. The latter method is superior in that the structure of the fixing device is simple because a silicone oil application mechanism and the like are not required, and maintenance such as replenishment of silicone oil is not required. Therefore, the offset phenomenon occurs when the temperature of the heat roller increases, and therefore, the higher the minimum temperature at which the offset phenomenon occurs (hereinafter referred to as "offset occurrence temperature"), the better the non-offset property is. It can be called toner, but in order for toner to be fixed, it must be heated to a temperature above its softening point. Therefore, in an actual heat roller fixing device, the temperature of the heat roller is lower than that of the toner. The temperature is set at a specific temperature within the fixable temperature range, which is above the softening point and below the offset generation temperature. However, in reality, it is not possible to maintain the temperature of the heat roller completely uniformly at the set temperature, and there are other temperature-related considerations that must be taken into consideration. It is desirable to use a toner that does not impair the advantages of the heat fixing method. Generally, in order to raise the temperature at which offset occurs in toner, it is effective to use a binder resin containing a high molecular weight component. Then, since the resin has a high softening point, the minimum temperature required for fixing the toner (hereinafter referred to as "minimum fixing temperature") becomes high.
The advantages of the contact heat fixing method are lost.
Naturally, it is desirable that this minimum fixing temperature be low, and in order to achieve the formation of visible images on both sides of a single sheet of transfer paper, which has recently become a high demand, the toner used for development must be It is necessary that the material can be fixed at a low temperature. In view of the above-mentioned background, a means has been developed for lowering the minimum fixing temperature by incorporating a low softening point wax made of a release agent such as polypropylene wax or polyethylene wax into toner particles. However, in this method, since the fluidity of the powdered toner is reduced, the developability and transferability are reduced, a good visible image cannot be formed, and there is a tendency for the toner to become cohesive.
Moreover, in order to obtain the effect of adding wax, the content ratio of the wax must be increased considerably, and as a result, wax components may adhere to the developing sleeve or electrostatic image support and form a film. , and there are drawbacks that impede its function. In order to improve the fluidity of toner, it is effective to add a fluidity improver made of fine hydrophobic silica powder to toner powder. In order to obtain this, it is necessary to add a large amount of hydrophobic silica fine powder, and as a result, the surface of the electrostatic image support is damaged by the highly hard hydrophobic silica fine powder, and the support is This becomes a serious problem when the electrostatic image support is a photoconductive photoreceptor, and when the surface of the electrostatic image support is cleaned with a rubber blade, the blade is subject to severe wear. In an image forming apparatus that has a recycling system in which toner that has not participated in the formation of a toner image is returned to the developing device for reuse, fine particles of hydrophobic silica are embedded in the surface of the toner particles, which improves the flow of the toner. The resulting visible image is of low quality. [Object of the Invention] The present invention has been made based on the above-mentioned circumstances, and its objects are to have sufficient non-offset properties, have a low minimum fixing temperature, and therefore have a wide fixable temperature range; Moreover, it is an object of the present invention to provide a toner for developing an electrostatic image that has high fluidity and non-cohesiveness and can consistently form good visible images stably. [Structure of the Invention] The present invention is characterized by a first wax made of polyolefin and an α-methylene aliphatic monocarboxylic acid ester monomer being block copolymerized as a modifying component. 0.1~50% by weight, softening point 90~160
C. and a second wax made of a modified polyolefin in a proportion such that the total of the first wax and the second wax is 1 to 20% by weight. The present invention will be specifically explained below. In the present invention, a first wax (hereinafter referred to as "unmodified wax") made of polyolefin (hereinafter referred to as "unmodified wax") and α
- A polymer obtained by block copolymerizing a methylene aliphatic monocarboxylic acid ester monomer (hereinafter referred to as "acrylate monomer") and polyolefin, i.e., a polyolefin modified with acrylate monomer as a modifying component (hereinafter referred to as "modified polyolefin"). ) (hereinafter referred to as "modified wax").
to form a toner for developing electrostatic images. In the above, the amount of unmodified wax and modified wax used is such that the total content of both waxes is within the range of 1 to 20% by weight based on the binder resin. If this proportion is less than 1% by weight, the wax will not be effective as a release agent and the non-offset properties of the toner will not be improved, while if this proportion is too large, the fluidity of the toner will decrease. It became like this,
As a result, developability and transferability deteriorate, and a good visible image cannot be formed, and the wax adheres to the developing sleeve or electrostatic image support to form a film, which impairs its function. In addition, the ratio of unmodified wax to modified wax is 1 part of the former and 0.5 to 10 parts of the latter by weight.
Preferably the proportion is 0.5 to 5 parts. If the latter ratio is too small, the fluidity of the toner will be insufficient, while if the former ratio is too small, the offset generation temperature will be low. As the binder resin, those normally used for this type of application can be used, but in practice, styrene resin, acrylic resin, styrene-acrylic copolymer resin, other vinyl resin, polyester resin, Others are preferred. One particularly preferable binder resin is a polymer or copolymer of styrenic monomers, that is, a polymer or copolymer of one or more styrenic monomers, or a polymer or copolymer of styrenic monomers and styrenic monomers. It is a styrene resin that is a copolymer with other vinyl monomers and has a ratio Mw/Mn of weight average molecular weight (Mw) to number average molecular weight (Mn) of 3.5 or more. Specific examples of the styrene monomer include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, a-methylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, p-n -butylstyrene, p-tert-butylstyrene, p-n-hexylstyrene, p-n
-octylstyrene, p-n-nonylstyrene,
Examples include p-n-decylstyrene, p-n-dodecylstyrene, p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, and 3,4-dichlorostyrene. As the copolymer of a styrene monomer and a vinyl monomer, a styrene-butadiene copolymer or a styrene-acrylic copolymer is particularly preferred. Examples of the acrylic monomer for the acrylic component include methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, propyl acrylate, n-octyl acrylate, dodecyl acrylate, and lauryl acrylate. , 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, phenyl acrylate, methyl α-chloroacrylate,
Methyl methacrylate, ethyl methacrylate,
Propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, lauryl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate , α-methylene aliphatic monocarboxylic acid esters such as dimethylaminoethyl methacrylate and diethylaminoethyl methacrylate; acrylonitrile, methacrylonitrile,
Examples include acrylamide, acrylic acid or methacrylic acid derivatives, and others. These monomers can be used alone or in combination. The above styrene resin has Mw/Mn of 3.5
or more, but Mw/Mn is 5
or more is desirable, and its molecular weight is about Mn
Particularly preferred are values between 2000 and 30000.
Note that the values of Mw, Mn, and Mw/Mn can be measured by various methods, and there are slight variations depending on the measurement method. Therefore, in the present invention, the values of Mw, Mn and Mw/Mn are defined as those measured by the following measuring method. That is, all of these values are values measured by gel permeation chromatography under the conditions described below. A solvent (tetrahydrofuran) is flowed at a flow rate of 1 ml per minute at a temperature of 25° C., and a sample weight of 8 mg of a tetrahydrofuran sample solution with a concentration of 0.4 g/dl is injected, and measurements are performed. When measuring the molecular weight of a sample, the molecular weight distribution of the sample is included in a range where the logarithm of the molecular weight and the count number of a calibration curve prepared using several types of monodisperse polystyrene standard samples are linear. Select measurement conditions. In addition, the reliability of this measurement was determined using the NBS706 polystyrene standard sample (Mw=28.8×10 ⁴ , Mn=13.7×10 ⁴ ,
Confirm that Mw/Mn of Mw/Mn=2.11) becomes 2.11±0.10. Furthermore, although styrenic resins as mentioned above differ depending on the type of monomers contained as constituent components, they generally have a softening point of about 100 to 100 by the ring and ball method.
Those with a glass transition temperature of 170°C are particularly effective, and those with a glass transition point of 40°C or higher are particularly effective. That is, if the softening point is 100° C. or lower, excessive pulverization is likely to occur, and the photoconductive plate is likely to be contaminated by toner filming. Furthermore, if the softening point exceeds 170°C, it will be hard and difficult to crush, and furthermore, a large amount of heat will be required during fixing, resulting in poor fixing efficiency. On the other hand, when the glass transition point is 40° C. or lower, agglomeration is likely to occur due to the cold flow phenomenon since the storage condition for toner is usually 40° C. or lower. In addition, the glass transition point of styrene resin is generally
As the value of Mw/Mn increases, it tends to have a wider range and is difficult to indicate a specific value, so Mw/Mn
It may be difficult to measure the glass transition point of resins with large values. The styrenic resin can be synthesized by the following method. Using common polymerization methods
A resin having Mw/Mn of 1.5 to 3.0 is obtained. However, the following method is used to obtain a resin with Mw/Mn of 3.5 or more used in the present invention. That is, one method is to carry out polymerization by continuously or continuously changing the polymerization temperature. Another method is to polymerize a divinyl compound and a trivinyl compound in combination. Still another method is a method in which several types of monomers having different initiator concentrations and chain transfer agent concentrations are sequentially added and polymerized. In particular, by mixing relatively low molecular weight resin with high molecular weight resin, it is possible to easily
A resin with a large Mw/Mn can be obtained. These methods can be carried out by bulk polymerization, solution polymerization, suspension polymerization, emulsion polymerization, etc. but,
The suspension polymerization method is most preferred because of the ease of handling the resulting resin and the reduction in manufacturing costs. In addition, one method for increasing Mw/Mn is to dissolve several types of resins with different molecular weights in a solvent and remove the solvent by drying under reduced pressure or spray drying, or to dissolve them by heating and blend them. There is a way. Another example of the binder resin preferred in the present invention is polyester resin, which is obtained by polycondensation of alcohol and carboxylic acid. Examples of the alcohol used here include ethylene glycol, diethylene glycol,
triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,
4-butanediol, neopentyl glycol,
Diols such as 1,4-butenediol, 1,4
-Bis(hydroxymethyl)cyclohexane, etherified bisphenols such as bisphenol A, hydrogenated bisphenol A, polyoxyethylenated bisphenol A, polyoxypropylenated bisphenol A, and other dihydric alcohol monomers I can raise my body. Examples of carboxylic acids include maleic acid, fumaric acid, mesaonic acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, cyclohexanecarboxylic acid, succinic acid, adipic acid, sebacic acid, malonic acid, Examples include anhydrides of these acids, dimers of lower alkyl esters and linoleic acid, and other divalent organic acid monomers. In the present invention, as the polyester resin, it is preferable to use not only a polymer made only of the above difunctional monomers but also a polymer containing a component made of trifunctional or higher polyfunctional monomers. . Examples of such polyfunctional monomers, such as trivalent or higher polyhydric alcohol monomers, include sorbitol, 1,
2,3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, sugar,
1,2,4-butanetriol, 1,2,5-pentanetriol, glycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane, 1,3 , 5-trihydroxymethylbenzene, and others. In addition, as trivalent or higher polyvalent carboxylic acid monomers,
For example, 1,2,4-benzenetricarboxylic acid,
1,2,5-benzenetricarboxylic acid, 1,2,
4-cyclohexanetricarboxylic acid, 2,5,7
-Naphthalenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, 1,2,4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-
Mention may be made of methylenecarboxypropane, tetra(methylenecarboxyl)methane, 1,2,7,8-octanetetracarboxylic acid, Empol trimer acid, acid anhydrides thereof, and others. It is desirable that the above trifunctional or higher polyfunctional monomer component be contained in a proportion of 30 to 80 mol % in each of the alcohol component or acid component as a structural unit in the polymer. The polyester resin used in the present invention preferably has a chloroform-insoluble content of 5% by weight or more. Here, the chloroform-insoluble content refers to the paper-insoluble content when the sample is dissolved in chloroform.
It can be found as follows. Finely crush the resin sample, collect 5.00g of sample powder that has passed through a 40-mesh sieve, place it in a 150ml container with 5.00g of the super-aiding agent Radiolite (*700), and inject 100g of chloroform into the container. death,
The sample was placed on a ball mill stand and rotated for 5 hours or more to sufficiently dissolve the sample in chloroform. On the other hand, place a piece of paper (No. 2) with a diameter of 7 cm in the pressurizer, pre-coat 5.00g of Radiolite uniformly on it, and add a small amount of chloroform to make the paper adhere to the pressurizer. , the contents of the container are poured into a strainer. Furthermore, thoroughly wash the container with 100 ml of chloroform and pour it into a filter to prevent any deposits from remaining on the walls of the container. After that, close the top lid of the filtration vessel and carry out filtration.
The filtration is carried out under a pressure of 4 kg/ ^cm2 or less, and after the chloroform has stopped flowing out, fresh chloroform is added.
Add 100 ml to wash the residue on the paper and perform pressure filtration again. After the above operations are completed, the paper, the residue on it, and the radiolite are all placed on aluminum foil and placed in a vacuum dryer at a temperature of 80 to 100℃.
Dry for 10 hours under a pressure of 100 mmHg, measure the total weight a (g) of the dried product thus obtained,
The chloroform insoluble content x (wt%) is determined by the following formula. x (weight%) = a (g) - weight of paper (g)
-Weight of radiolite (10.00g) / Sampling weight (5.00g) x 100 The chloroform-insoluble content determined in this way is a high molecular weight polymer component or a crosslinked polymer component in the polyester resin,
Its molecular weight is believed to be approximately 200,000 or more. The proportion of the above-mentioned chloroform-insoluble components can be controlled to a considerable extent by appropriately selecting the reaction conditions or by making an appropriate crosslinking agent exist in the reaction system in the polymerization reaction between alcohol and carboxylic acid mentioned above. can be formed with. In the present invention, a polyester resin having a chloroform-insoluble content of 5% by weight or more is used as a binder, but if a polyester resin having a chloroform-insoluble content of less than 5% by weight is used, the resulting toner will have a low offset temperature. Still another example of what is preferably used as the binder resin in the present invention is a styrene-butadiene copolymer (hereinafter referred to as "S-B copolymer"). S-B copolymer is obtained by copolymerizing styrene monomer and butadiene,
Here, the styrene monomer includes styrene, o-
Methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, p-n-butylstyrene, p-dodecylstyrene, p-methoxystyrene, p-methylstyrene enylstyrene, p-chlorostyrene, and others. Further, the S-B copolymer must contain a high molecular weight component having a molecular weight of 100,000 or more, and the content thereof must be 10% by weight or more. The content ratio of this high molecular weight component is 10
When the amount is less than % by weight, the non-offset property of the binder resin itself disappears, so that the temperature at which offset occurs becomes low. In particular, high molecular weight components with a molecular weight of 100,000 or more are 10
A range of 70% by weight is preferable because the offset generation temperature is high and the softening point is low. Molecular weights in this specification are determined by gel vermi- ation chromatography (Gel vermi- cation chromatography) under the following conditions.
This is required by the Permeation Chromatography (Permeation Chromatography) method. In other words, “Waters 200 type
Using a GPC (Water's 200 Type GPC) measuring device (manufactured by Waters), a sample solution of tetrahydrofuran with a concentration of 0.2 g/dl was poured at a temperature of 25°C while flowing the solvent (tetrahydrofuran) at a flow rate of 1 ml per minute. A sample weight of 4 mg is injected into the column and measured. As the columns used here, a combination of 10 ⁶ -10 ⁶ -10 ⁵ -10 ⁴ is used. The monodisperse polystyrene standard samples for setting the calibration curve are polystyrene manufactured by Plessyer Chemical Co., Ltd., and have molecular weights of 1800000, 860000, 411000,
160000, 98200, 51000, 19800, 10000, and 4000 are used. Note that the tetrahydrofuran-insoluble content at the time of measurement has a molecular weight of 500,000 or more, and is a high molecular weight component with a molecular weight of 100,000 or more in the present invention. The S-B copolymer used in the present invention has a styrene component (hereinafter referred to as "styrene component").
A content of 70 to 98% by weight, particularly preferably 85 to 98% by weight. When an S-B copolymer with a styrene component content of less than 70% by weight is used, the glass transition point of the binder resin becomes low,
The resulting toner becomes cohesive and forms clumps during storage or in a developing device. On the other hand, when an S-B copolymer containing more than 98% by weight of styrene is used, the softening point of the binder resin becomes high and the fixable temperature range becomes narrow. The polyolefin constituting the unmodified wax contained in the toner of the present invention is a homopolymer type obtained from a single olefin monomer, or a copolymer type obtained by copolymerizing the olefin monomer with another monomer copolymerizable with it. It may be of any type. The olefin monomers include, for example, ethylene, propylene, butene-1, pentene-1, hexene-1, heptene-1, octene-1, nonene-1, decene-1, and those having different positions of unsaturated bonds. isomers of, as well as e.g. 3-methyl-1-butene, 3-methyl-2-pentene, 3-
Included are those having a branched chain consisting of an alkyl group, such as propyl-5-methyl-2-hexene, and all other olefin monomers. Other monomers copolymerizable with the olefin monomer include other olefin monomers, such as vinyl methyl ether, vinyl-n-
Vinyl ethers such as butyl ether and vinyl phenyl ether; vinyl esters such as vinyl acetate and vinyl butyrate; haloolefins such as vinyl fluoride, vinylidene fluoride, tetrafluoroethylene, vinyl chloride, vinylidene chloride, and tetrachloroethylene; For example, methyl acrylate, ethyl acrylate, n-butyl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate,
Acrylic acid esters or methacrylic acid esters such as stearyl methacrylate, N,N-dimethylaminoethyl methacrylate, t-butylaminoethyl methacrylate, acrylic acid derivatives such as acrylonitrile, N,N-dimethylacrylamide, etc. acrylic acid,
Organic acids such as methacrylic acid, maleic acid, fumaric acid, itaconic acid, diethyl fumarate, β-
Various substances such as pinene can be mentioned. Therefore, when the polyolefin component is a copolymer type, an olefin copolymer type obtained by copolymerizing at least two or more of the above-mentioned olefin monomers, such as an ethylene-propylene copolymer, an ethylene-propylene copolymer, etc.
Butene copolymer, ethylene-pentene copolymer,
Copolymer type such as propylene-butene copolymer, propylene-pentene copolymer, ethylene-3-methyl-1-butene copolymer, ethylene-propylene-butene copolymer, or at least one of the above-mentioned olefin monomers. Olefin copolymer type obtained by copolymerizing one type with at least one monomer other than the above-mentioned olefin monomers, such as ethylene-vinyl acetate copolymer, ethylene-vinyl methyl ether copolymer, ethylene-chloride Vinyl copolymer, ethylene-methyl acrylate copolymer, ethylene-
Methyl methacrylate copolymer, ethylene-acrylic acid copolymer, propylene-vinyl acetate copolymer, propylene-vinylethyl ether copolymer, propylene-ethyl acrylate copolymer, propylene-methacrylic acid copolymer, butene -Vinyl methyl ether copolymer, butene-
Copolymer types such as methyl methacrylate copolymer, pentene-vinyl acetate copolymer, hexane-vinyl butyrate copolymer, ethylene-propylene-vinyl acetate copolymer, ethylene-vinyl acetate-vinyl methyl ether copolymer, etc. can be taken as a thing. When a copolymer type is used using a monomer other than the olefin monomer, it is preferable to use a copolymer type in which the proportion of the olefin moiety by the olefin monomer in the polyolefin component is, for example, 50 mol% or more. This is because if the proportion of the olefin portion becomes small, the effect of improving toner fixing performance will not be sufficiently exhibited. The modified polyolefin constituting the modified wax is obtained by blocking a polyolefin component with a modifying component, and the polyolefin described above is used as the polyolefin component. In addition, acrylate monomers are used as modifying components, and specific examples thereof include methyl acrylate, ethyl acrylate, n-butyl acrylate,
Isobutyl acrylate, propyl acrylate, n-octyl acrylate, dodecyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, phenyl acrylate, methyl α-chloroacrylate, meth Methyl acrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, lauryl methacrylate, 2-ethylhexyl methacrylate, Examples include stearyl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, and others. By carrying out block copolymerization using the above-mentioned acrylate monomer and the polyolefin described above according to conventional methods and conditions, a modified wax made of the modified polyolefin can be obtained. For example, for block copolymerization, a method using a living polymer or a method in which radicals generated by mechanochemically dividing a wax are reacted with an acrylate monomer to obtain a block copolymer can be used. Specific examples of preferred acrylate monomers as modifying components include methyl acrylate, methyl methacrylate, and n-butyl methacrylate. The proportion of the modifying component in the modified polyolefin is 0.1 to 50% by weight, particularly preferably 1 to 40% by weight. If this ratio is too small, the fluidity of the toner will be significantly reduced, and if it is too large, the minimum fixing temperature of the toner will become high. In addition, such modified polyolefin is JIS K2531-
It has a softening point of 90 to 160°C when measured by the ring and ball method specified in 1960. The toner of the present invention combines the above-mentioned unmodified wax and modified wax with a colorant, a magnetic material, a property improver,
It is a granular material that is dispersed in the above-mentioned binder resin together with other necessary additives, and its average particle size is usually in the range of 5 to 30 microns. Coloring agents include carbon black, nigrosine dye (CI No. 50415B), and aniline blue (CI No.
50405), Calco Oil Blue (CINo.azoec Blue)
3), Chrome Yellow (CINo.14090), Ultramarine Blue (CINo.77103), Dupont Oil Red (CINo.26105), Quinoline Yellow (CINo.
47005), methylene blue chloride (CINo.
52015), Phthalocyanine Blue (CINo.74160),
Malachite Green Oxalate (CINo.
42000), lampblack (CI No. 77266), rose bengal (CI No. 45435), mixtures thereof, and others. These colorants need to be contained in a sufficient proportion to form a visible image of sufficient concentration, and are usually used in binder resins.
The proportion is about 1 to 20 parts by weight per 100 parts by weight. The magnetic material may be a ferromagnetic metal or alloy such as iron, cobalt, or nickel, including ferrite and magnetite, or a compound containing these elements, or a material that does not contain a ferromagnetic element but is subjected to appropriate heat treatment. Alloys that become ferromagnetic, such as manganese-copper-aluminum,
Mention may be made of a type of alloy called Heusler alloy containing manganese and copper, such as manganese-copper-tin, or chromium dioxide, among others. These magnetic substances are uniformly dispersed in the binder in the form of fine powder with an average particle size of 0.1 to 1 micron. The content is 20 to 70 parts by weight per 100 parts by weight of toner.
Preferably it is 40 to 70 parts by weight. The property improving agents include charge control agents, anti-offset agents, lubricants for improving fluidity, and others. The toner of the present invention is mixed with a carrier made of iron powder, glass beads, etc. to make a two-component developer, but when it contains a magnetic material, it can be directly used as a one-component developer for developing electrostatic images. . [Effects of the Invention] Since the toner according to the present invention contains both an unmodified wax and a modified wax, it has a high offset generation temperature, and also has a high offset generation temperature, as will be clear from the description of the examples below. However, the minimum fixing temperature is low and it is suitable for high-speed fixing using a heat roller fixing device. In addition, there are cases where the degree of decrease in fluidity due to the addition of wax is so small that it becomes unnecessary or necessary to add a fluidity improver such as hydrophobic silica fine powder to obtain the necessary fluidity. However, a very small amount of addition is sufficient.
Therefore, damage caused by adding a large amount of hydrophobic silica fine powder can be avoided. Furthermore, it has high non-aggregation properties and excellent storage stability. Therefore, according to the toner of the present invention, it is possible to achieve good development due to its high fluidity and non-cohesiveness, and it is also possible to fix at low temperature and high speed, resulting in high image density and excellent image density. A visible image can always be stably formed. In addition, since the toner of the present invention has a low minimum fixing temperature, it is possible to avoid exposing the paper, which is the toner image support, to high temperatures during fixing. It becomes practically possible to form a visible image using toner. The reason why such excellent results as described above can be obtained is that: (1) both the unmodified wax and the modified wax contained in the toner are mainly composed of polyolefin, so the minimum fixing temperature of the toner is low; Modified wax has an excellent effect of imparting non-offset properties, and since modified wax is also effective in imparting non-offset properties, as a result, the temperature at which offset occurs in the toner is high. Not only does the degree of decrease in toner fluidity due to the addition of wax itself be smaller than that in the case of unmodified wax, but also when unmodified wax is further added, the toner fluidity due to its addition is lower. Part of the reason is thought to be that it has the effect of suppressing the rate of decrease in It is presumed that the reason for ○C above is that the modified wax has the effect of increasing and stabilizing the compatibility of the unmodified wax with the binder resin, and as a result, the adhesion of the unmodified wax is hidden. be done. In addition, if the binder resin is a styrene resin and its Mw/Mn value is 3.5 or more, if it is a polyester resin and the chloroform insoluble content is 5% by weight or more, it is an S-B resin. When the binder resin itself contains 10% by weight or more of a high molecular weight component having a molecular weight of 100,000 or more, the binder resin itself has low-temperature fixing properties and non-offset properties, and therefore the effects of the present invention are ensured and It is fully exhibited and it is possible to reduce the proportion of added wax. [Examples] Examples of the present invention will be described below, but the invention is not limited to these. Note that "parts" represent parts by weight. The binder resin and wax used in the following examples are as follows. [Binder resin] (1) Binder resin A1 Obtained by copolymerizing styrene, methyl methacrylate, and n-butyl methacrylate at a weight ratio of 50:20:30, containing high molecular weight components and low molecular weight components. The ratio by weight is 40:100,
Mw=130000, Mn=8000, Mw/Mn=16.25,
Copolymer (2) with a softening point of 135°C Binder resin A2 299 g of terephthalic acid, 221 g of polyoxypropylene (2,2)-2,2-bis(4-hydroxyphenyl)propane, and 82 g of pentaerythritol. , placed in a round-bottom flask equipped with a thermometer, a stainless steel stirrer, a glass nitrogen gas inlet tube, and a flow-down condenser, and the flask was placed on a heating mantle, and nitrogen gas was introduced through the nitrogen gas inlet tube. Raise the temperature while maintaining an inert atmosphere inside the flask.
Furthermore, 0.05 g of dibutyltin oxide is added and the reaction is carried out at a temperature of 200°C while monitoring the reaction at the softening point. Chloroform-insoluble matter 17
Weight%, polyester resin with a softening point of 131°C (3) Binder resin A3 (dispersion medium) Water 180 parts (monomer) Butadiene 10 parts Styrene 90 parts Divinylbenzene 0.16 parts (emulsifier) Fatty acid potassium salt 2.2 parts Disproportionated rosin Acid potassium salt 2.2 parts Potassium phosphate 0.4 parts (polymerization initiator system) Ferrous sulfate 0.005 parts Paramenthane hydroperoxide 0.02 parts t-dodecyl mercaptan 0.5 parts The resulting latex was placed in an autoclave to carry out a polymerization reaction at a temperature of 5°C, and when the conversion rate reached 70%, 0.2 parts of a polymerization terminator N,N'-diethylhydroxyamine was added to stop the reaction. After adding 1 part of stabilizer to the coagulant, calcium chloride is added to coagulate the polymer, dehydrated and dried, the content of high molecular weight components with a molecular weight of 100,000 or more is 41% by weight, and the softening point is 41% by weight. 141℃ S-B copolymer [wax] (1) Modified wax a Polyethylene wax block copolymerized with methyl methacrylate (methyl methacrylate content 5% by weight, softening point 110℃) (2) Unmodified wax b Polypropylene wax “Viscoll 660P”
(Manufactured by Sanyo Kasei Co., Ltd.) In each of the Examples and Comparative Examples, toner consisting of particles with an average particle size of 10 μm was prepared by using the materials of the indicated formulation in a conventional manner by melting, kneading, cooling, pulverizing, and classifying the materials. Manufactured. Example 1 Binder resin A1 100 parts modified wax a 2 parts unmodified wax b 2 parts Carbon black "Mogal L" 10 parts Example 2 Binder resin A2 100 parts modified wax a 2 parts unmodified wax b 2 parts Carbon black "Mogal"L'' 10 parts Example 3 Binder resin A3 100 parts Modified wax a 2 parts Unmodified wax b 2 parts Carbon black "Mogal L" 10 parts Comparative example 1 Binder resin A1 100 parts Unmodified wax b 3 parts Carbon black "Mogal L" ” 10 parts Comparative example 2 Binder resin A2 100 parts Unmodified wax b 3 parts Carbon black "Mogal L" 10 parts Comparative example 3 Binder resin A3 100 parts Unmodified wax b 3 parts Carbon black "Mogal L" 10 parts Implementation of the above The toners obtained in Examples 1 to 3 are referred to as "Toner 1" to "Toner 3," and the toners obtained in Comparative Examples 1 to 3 are referred to as "Comparative Toner 1" to "Comparative Toner 3," respectively. The fluidity of each of these toners was investigated. That is, the degree of compaction was measured using a powder compressibility tester "Tapdencer" (manufactured by Seishin Enterprise Co., Ltd.), taking advantage of the fact that powders with higher fluidity have a smaller degree of compaction. Specifically, a sample is loosely packed into a container with a diameter of 28 mm and a volume of 100 ml from above through a 100 mesh sieve, the weight is measured to determine the static bulk density A, and the container is then placed in a top tapping device with a lid of the same diameter. Determine the volume of the sample when tapped 600 times at a drop height of 5 mm, divide the previously determined weight by this volume value to determine the solidified bulk density P, and calculate the degree of compression C using the following formula: Calculated. C=P-A/P×100 (%) Also, by mixing each toner with a carrier made of iron powder coated with resin, the toner concentration is 2% by weight and the toner charge amount is 20±1 microcoulomb. /
Using each developer, an electrophotographic copying machine "U-Bix3000" (manufactured by Konishiroku Photo Industry Co., Ltd.) is used to develop an electrostatic charge image, transfer a toner image to transfer paper, and develop a toner image. Fixing was carried out using a hot roller fixing device, and the amount of toner primarily adhered to the surface of the photosensitive drum, the transfer rate to transfer paper, and the image density of the obtained copied image were measured. Here, the primary adhesion amount of toner is the amount of toner adhesion per unit area at a location where the so-called solid black potential is 800V. Furthermore, the minimum fixing temperature and offset generation temperature were determined for each of the toners, and the storage stability was also evaluated. Regarding the minimum fixing temperature, a heat roller whose surface layer is made of Teflon (polytetrafluoroethylene manufactured by Dupont) and a pressure roller whose surface layer is made of silicone rubber "KE-1300RTV" (manufactured by Shin-Etsu Kagaku Kogyo Co., Ltd.) The fixing device is used to fix the toner image of the sample toner transferred onto the transfer paper of 64 g/m ² at a linear speed of 120 mm/sec.
Kimwipe rubbing is applied to the formed fixed image repeatedly at each temperature raised in steps of 5°C above ℃, and the lowest set temperature for a fixed image that exhibits sufficient resistance to rubbing is applied to the lowest fixing temperature. Temperature. Note that the fixing device used here does not have a silicone oil supply mechanism. In addition, to measure the offset generation temperature, the toner image is transferred and fixed using the above-mentioned fixing device, and then a blank transfer paper is sent to the fixing device under the same conditions. The operation of observing whether or not toner stains occur was repeated while the set temperature of the heat roller of the fixing device was successively increased, and the temperature at which offset occurred was determined. Regarding toner 7, an electrophotographic copying machine "U-Bix T" (manufactured by Konishiroku Photo Industry Co., Ltd.) was used.
The electrostatic charge image was developed, the toner image was transferred to transfer paper, and a fixing test was conducted. Regarding storage stability, each sample was left for 48 hours at a temperature of 55°C and a relative humidity of 40%, and the presence or absence of aggregation and its degree were evaluated. The above results are shown in Table 1. Note that the offset occurrence humidity marked with an asterisk (*) indicates that the offset phenomenon did not occur at that temperature.

【table】

[Table] In addition, when we conducted a continuous copying test for 20,000 times using each of Toner 1 to Toner 3 using an electrophotographic copying machine "U-Bix3000," the results were clear and good until the end, regardless of which toner was used. A copy image was formed. As is clear from the above results, the toner according to the present invention has excellent non-offset properties and has a very low minimum fixing temperature, compared to the conventional toner containing only unmodified polyolefin wax. It has a wide range, has high fluidity and can be put to practical use even without the addition of fluidity improvers, has excellent developability and transferability, and always produces stable and good visible images. can be formed.

Claims (1)

[Claims] 1. A first wax made of polyolefin;
A second polyolefin made of a modified polyolefin having a softening point of 90 to 160° C., which is block copolymerized with an α-methylene aliphatic monocarboxylic acid ester monomer as a modifying component, in which the proportion of the modifying component is 0.1 to 50% by weight, and the softening point is 90 to 160°C. 1. A toner for developing an electrostatic image, characterized in that it contains wax in a proportion such that the total of the first wax and the second wax is 1 to 20% by weight.