JPH07319202A - Electrophotographic developer - Google Patents

Abstract

(57) [Summary] [Structure] Developer for electrophotography (hereinafter referred to as toner)
The fixing resin contained in is a styrene-based polymer having a maximum value in the molecular weight range of 1 × 10 ^{3 to} 5 × 10 ³ , and a molecular weight of 3
Styrene having a maximum value in the range of × 10 ⁵ to 1 × 10 ^6.
It is composed of an acrylic copolymer. The weight ratio of the above styrene-based polymer and styrene-acrylic copolymer is 1/1
~ 9/1. The weight ratio of the above acrylic monomer is 0.
It is from 05 to 0.3. Weight ratio a of the above acrylic monomer
And the weight ratio b of the styrene-acrylic copolymer in the fixing resin satisfy the relationship of 0.26 ≦ a + 0.6b ≦ 0.46. [Effect] Since the toner maintains good storage stability, fixability, anti-offset property, chargeability, etc., it is possible to satisfy the above-mentioned various characteristics. It is suitable for a high-speed heat roller fixing method.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic developer used in an electrophotographic apparatus such as an electrostatic transfer copying machine or a laser printer.

[0002]

2. Description of the Related Art Generally, an electrophotographic developer (hereinafter referred to as a toner) is used in an image forming method known as an electrophotographic method, an electrostatic printing method, an electrostatic recording method or the like, and an electrostatic image is used. To visualize. In other words, the toner is the electrostatic transfer type copying machine,
Alternatively, it is used in electrophotographic devices such as laser printers. Then, these electrophotographic devices form an electrostatic latent image on the surface of the photoconductor made of a photoconductive material by using the above various methods, and then, after developing the electrostatic latent image with toner,
The toner image is transferred to a transfer material such as transfer paper as necessary. The transfer material on which the toner image has been transferred is heated and pressed by the heat roller fixing method, whereby the toner image is fixed on the transfer material.

In the above heat roller fixing method, the surface of the heated roller and the toner on the transfer material come into direct contact with each other under pressure. Therefore, the heat roller fixing method has extremely good thermal efficiency when the toner is fused to the transfer material, and the fixing operation can be performed quickly. Therefore, the fixing method is very effective particularly in a high-speed electrophotographic apparatus. Is.

However, in the above heat roller fixing method, since the surface of the heated roller and the heat-melted toner are in direct contact with each other under pressure, a so-called hot offset phenomenon occurs to contaminate the transfer material. That is, a part of the toner on the transfer material is transferred to and adheres to the roller surface, and the adhered toner is retransferred to the transfer material that next passes the roller surface. Therefore, in order to eliminate the above-mentioned inconvenience, the toner needs to have good offset resistance.

Further, when the adhesive force of the heat-melted toner to the transfer material is poor, the toner image fixed on the transfer material is peeled off from the transfer material when rubbed with a finger or the like. Therefore, in order to eliminate the above-mentioned inconvenience, the toner needs to have a good fixing property.

Further, the toner is required to have various properties such as storage stability, charging property, blocking resistance, developing property, transfer property and cleaning property in addition to the offset resistance and fixing property. .

However, the conventional toner has one or more problems in these characteristics. That is, since the above-mentioned conventional toner is easily melted by heating, for example, aggregation or blocking phenomenon is likely to occur during storage or in the electrophotographic apparatus.
That is, the above conventional toner has a poor storability.

Further, since the triboelectric property and the fluidity of the above-mentioned conventional toner become poor due to environmental changes such as humidity changes, the image density (ID) of the toner image is deteriorated.
Is easy to change. If the amount of toner adhering to the surface of the photoreceptor on which the electrostatic latent image is formed is increased in order to increase the image density, the background density (BG) also increases, so that the so-called fog phenomenon easily occurs.

Further, the conventional toner has a large charge amount due to repeated development by continuous use of the electrophotographic apparatus. That is, collision between toner particles and carrier particles,
Further, due to the contact between these particles and the surface of the photoreceptor, the toner particles, the carrier particles and the photoreceptor cause mutual deterioration. Therefore, with the conventional toner, the image density of the toner image is changed and the background density is increased due to repeated development, so that the image quality of the toner image is easily deteriorated. That is, the above conventional toner has a poor charging property.

In recent years, so-called high-speed fixing has been aimed at in order to improve the efficiency of copying work. That is, in the above heat roller fixing method, in order to increase the fixing speed of the toner image, an attempt has been made to lower the softening point of the fixing resin contained in the toner to facilitate the fixing operation. However, when the softening point of the fixing resin is lowered, the aggregation and blocking phenomenon of toner particles easily occur.

Therefore, it is strongly desired to develop a toner which is excellent in the above-mentioned various characteristics and which is suitable for a heat roller fixing method, particularly a so-called high speed heat roller fixing method.

For example, as disclosed in Japanese Patent Application Laid-Open No. 4-264559, "Claim 1", the molecular weight is 1 × 10 ^3.
Within the range of 1 × 10 ⁵ and the molecular weight of 1 × 10 ⁵ to 2 × 10 ⁵ , each has a maximum value, and the range of molecular weight distribution is 2.1 × 10 ⁵ or less, and the resin as a whole. A toner containing a styrene-acrylic copolymer having a styrene content of 80% by weight or more as a fixing resin has been proposed. The toner is prevented from causing a blocking phenomenon and has improved storage stability.

Further, for example, as disclosed in Japanese Patent Application Laid-Open No. 4-293055, "Claim 1", a styrene-based copolymer having a molecular weight of 1 × 10 ³ to 2 × 10 ⁴ is used. To
The styrene-based copolymer contains 10 to 50 parts by weight and a styrene-based copolymer having a molecular weight of 1 × 10 ⁵ to 2 × 10 ⁶ in a ratio of 50 to 90 parts by weight. The copolymerization ratio W _{a of the} monomer is 70 wt% to 98 wt%, the copolymerization ratio W _b of the styrene monomer in the styrene copolymer is 50 wt% to 90 wt%, and W _a ≧ W A toner containing a fixing resin satisfying the relationship of _b has been proposed. The toner has improved chargeability and avoids inconveniences such as occurrence of a so-called fog phenomenon or scattering of the toner.

[0014]

However, in the toner proposed in Japanese Patent Laid-Open No. 4-264559 mentioned above, the maximum value of the molecular weight of the styrene-acrylic copolymer is as small as 2 × 10 ⁵ at maximum. . For this reason, the elasticity of the heat-melted toner, that is, the heat-melted fixing resin is extremely small. Therefore, the toner proposed in Japanese Patent Application Laid-Open No. 4-264559 has a problem that the offset resistance becomes poor because the so-called hot offset phenomenon easily occurs when the surface temperature of the roller exceeds 190 ° C., for example. Have

Further, the toner proposed in the above-mentioned Japanese Patent Application Laid-Open No. 4-293055 is a copolymer which is copolymerized with a styrene-based monomer as described in "Means for Solving the Problems". As the polymerization component, alkyl acid alkyl ester (alkyl group having 1 to 17 carbon atoms) and methacrylic acid alkyl ester (alkyl group having 2 to 17 carbon atoms) are preferably used.

However, when the above ester is used as the copolymerization component, the styrene copolymer, that is, the toner containing the above fixing resin, has a glass transition temperature (T
g) is reduced. Then, when the glass transition temperature (Tg) of the low molecular weight styrene-based copolymer is lowered, the toner is likely to be adversely affected by heat. That is, the toner is apt to cause aggregation or blocking phenomenon during storage or in the electrophotographic apparatus, for example. Therefore, the toner proposed in JP-A-4-293055 is
It has a problem of poor storage stability.

Therefore, it is possible to satisfy the above-mentioned various characteristics such as storability, fixing property, anti-offset property and charging property, and it is suitable for a heat roller fixing method, especially a so-called high speed heat roller fixing method. Toner is sought.

That is, the present invention has been made in view of the above conventional problems, and an object thereof is to be able to satisfy various characteristics such as storability, fixing property, anti-offset property and charging property. Another object of the present invention is to provide an electrophotographic developer suitable for a heat roller fixing method, particularly a so-called high-speed heat roller fixing method.

[0019]

Means for Solving the Problems The inventors of the present application have made extensive studies on electrophotographic developers, and as a result, have found that styrene-based polymers and styrene-acrylic copolymers in fixing resins contained in electrophotographic developers. Or the weight ratio of the styrene polymer and the styrene-acrylic copolymer (styrene polymer / styrene-acrylic copolymer), or the acrylic monomer used for the fixing resin. By adjusting the weight ratio of (acrylic monomer / (acrylic monomer + styrene monomer)) and the like, storability,
It has been found that an electrophotographic developer can be obtained which can satisfy various properties such as fixability, offset resistance, and chargeability, and which is suitable for a heat roller fixing method, particularly a so-called high-speed heat roller fixing method. As a result, the present invention has been completed.

That is, in order to solve the above-mentioned problems, the electrophotographic developer according to the first aspect of the present invention has a molecular weight distribution of 1 × 10 ³ to 1 in the molecular weight distribution of the gel carrier liquid chromatogram.
It has a maximum value derived from a styrene-based polymer in the range of 5 × 10 ³ and a maximum value derived from a styrene-acrylic copolymer in the range of a molecular weight of 3 × 10 ⁵ to 1 × 10 ^6. And the weight ratio of the styrene polymer to the styrene-acrylic copolymer (styrene polymer / styrene-
The acrylic copolymer) contains a fixing resin of 1/1 to 9/1.

In order to solve the above-mentioned problems, the electrophotographic developer according to the second aspect of the present invention is the acrylic single-use developer used for the fixing resin in the electrophotographic developer according to the first aspect. The weight ratio of the monomers (acrylic monomer / (acrylic monomer + styrene monomer)) is 0.05 to 0.3.

Further, in order to solve the above-mentioned problems, the electrophotographic developer according to the third aspect of the present invention is the acrylic single-use developer used for the fixing resin in the electrophotographic developer according to the first aspect. Weight ratio a of the monomer (acrylic monomer / (acrylic monomer + styrene monomer)) and weight ratio b of the styrene-acrylic copolymer in the fixing resin (styrene-acrylic monomer). The copolymer / (styrene polymer + styrene-acrylic copolymer)) is characterized by satisfying the relationship of 0.26 ≦ a + 0.6b ≦ 0.46.

The present invention will be described in detail below. In the present invention, the styrene-based monomer used for the fixing resin contained in the electrophotographic developer (hereinafter, referred to as toner) is not particularly limited, and examples thereof include styrene and vinyltoluene. Examples include α-methylstyrene and the like. The acrylic monomer used for the fixing resin in the present invention is not particularly limited,
For example, the compound represented by the following general formula (1) may be mentioned.

CH ₂ ═CR ¹ —COOR ² (1) (In the formula, R ¹ represents a hydrogen atom or a lower alkyl group, R ² represents a hydrogen atom, a hydrocarbon group having up to 12 carbon atoms,
A hydroxyalkyl group, a vinyl ester group, or an aminoalkyl group is represented.) Examples of the acrylic monomer represented by the above general formula (1) include acrylic acid, methacrylic acid, methyl acrylate, ethyl acrylate, and acrylic acid. Butyl acid, 2-ethylhexyl acrylate, cyclohexyl acrylate,
Phenyl acrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, ethyl β-hydroxyacrylate, γ-hydroxypropyl acrylate, δ-hydroxybutyl acrylate, β-hydroxyethyl methacrylate, γ-aminopropyl acrylate, γ-N, N-
Examples include propyl diethylaminoacrylate, ethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, and the like.

The fixing resin composed of the styrene type monomer and the acrylic type monomer is a gel carrier liquid chromatogram (Gel Permeat chromatogram).
ionChromatogram), hereinafter referred to as GPC), has a maximum value derived from the styrene polymer in the molecular weight range of 1 × 10 ^{3 to} 5 × 10 ³ . When this maximum value is larger than the above range, the molecular weight of the styrene-based polymer becomes too large, and the heat-melted toner becomes difficult to enter into the fibers of the transfer paper (transfer material) and heat-melted. The adhesive force between the toners is reduced. Therefore, the fixing property of the toner becomes poor, which is not preferable. Further, when the maximum value is smaller than the above range, the fixing property of the toner is improved, but the molecular weight of the styrene-based polymer becomes too small, and the toner is likely to be adversely affected by heat. Therefore, the storage stability of the toner becomes poor, which is not preferable.

Further, together with the above-mentioned styrene polymer,
When a styrene-acrylic copolymer having a molecular weight of 1 × 10 ^{3 to} 5 × 10 ³ is used, or a molecular weight of 1
When an acrylic polymer in the range of × 10 ^{3 to} 5 × 10 ³ is used, the glass transition temperature (Tg) on the low molecular weight side of the toner is lowered. For this reason, the toner is likely to be adversely affected by the heat. That is, the toner is, for example,
During storage or in an electrophotographic device such as a copying machine,
Agglomeration and blocking phenomenon easily occur. Therefore, the storage stability of the toner becomes poor, which is not preferable. In the following description, for convenience of explanation, the molecular weight is 1 × 10 ^{3 to} 5
The styrene-acrylic copolymer within the range of × 10 ³ and the acrylic monomer provided for the acrylic polymer are referred to as the low molecular weight side acrylic monomer.

Further, the above fixing resin has a maximum value derived from the styrene-acrylic copolymer within the molecular weight range of 3 × 10 ⁵ to 1 × 10 ^{6 in} the GPC molecular weight distribution. If this maximum value is smaller than the above range, the molecular weight of the styrene-acrylic copolymer becomes too small, and the fixing offset phenomenon is likely to occur. Therefore, the offset resistance of the toner becomes poor, which is not preferable. Further, when the maximum value is larger than the above range, the elasticity of the toner, that is, the fixing resin becomes large. Therefore, in the kneading step (described later) at the time of producing the toner, the mechanical load on the kneading device becomes excessive, which is not preferable. In addition, it is difficult to synthesize a styrene-acrylic copolymer having a molecular weight larger than the above range, resulting in an increase in the cost of the fixing resin.

Further, the fixing resin is a weight ratio of the styrene-based polymer and the styrene-acrylic copolymer (styrene-based polymer / styrene-acrylic-based copolymer).
Is 1/1 to 9/1. When the above weight ratio is less than 1/1, the content of the styrene-based polymer in the fixing resin becomes too small, the adhesive force of the heat-melted toner to the transfer paper, and the heat-melted toner. The adhesive force between them becomes small. Therefore, the fixing property of the toner becomes poor, which is not preferable. Also, the weight ratio is 9 /
When it is larger than 1, the content of the styrene-acrylic copolymer in the fixing resin becomes too small, and the elasticity of the heat-melted toner, that is, the heat-melted fixing resin becomes small. Therefore, when the toner is fixed on the transfer paper, a hot offset phenomenon in which the toner adheres to the heat roller of the fixing device easily occurs, which is not preferable.

The above fixing resin has a weight ratio of acrylic monomers (acrylic monomer / (acrylic monomer + styrene monomer)) of 0.05 to 0.05. 0.3
Has become. There is a correlation between the weight ratio of the acrylic monomer and the chargeability of the fixing resin, that is, the toner. As the above weight ratio increases, the amount of charge on the toner increases,
The image density (ID) of the toner image formed by the electrophotographic apparatus is lowered. In addition, when the weight ratio is small, the amount of charge of the toner is small, so that a so-called fog phenomenon occurs in the toner image formed by the electrophotographic apparatus, or the toner is scattered. That is, when the above weight ratio is larger than 0.3, the image density is lowered, which is not preferable. Also, the weight ratio is
If it is less than 0.05, the image density is good, but it is not preferable because a fog phenomenon occurs or toner is scattered.

Further, the above fixing resin has a weight ratio a (acrylic monomer / acrylic monomer / acrylic monomer) to be used for the fixing resin.
(Acrylic monomer + styrene monomer)) and the weight ratio of the styrene-acrylic copolymer in the fixing resin b (styrene-acrylic copolymer / (styrene-based polymer + styrene-acrylic) System copolymer)) satisfies the relationship of 0.26 ≦ a + 0.6b ≦ 0.46. In the following description, for convenience of description, (a + 0.6b) in the above inequality is represented by the weight ratio B
Shall be called.

The weight ratio B and the chargeability of the toner are as follows.
There is a correlation. If the weight ratio a of the acrylic monomer or the weight ratio b of the styrene-acrylic copolymer is large, that is, if the weight ratio B is large, the charge amount of the toner is large and the toner formed by the electrophotographic apparatus is large. The image density of the image is reduced. Further, when the weight ratio B becomes small, the amount of charge of the toner becomes small, which causes problems such as a fog phenomenon in the toner image formed by the electrophotographic apparatus, or the toner scattering. That is, when the weight ratio B is larger than 0.46, the image density is lowered, which is not preferable. If the weight ratio B is less than 0.26, the image density is good, but fog phenomenon occurs, or the toner is scattered, which is not preferable. Therefore, in the fixing resin of the present invention, the weight ratio B is set to 0.26 or more and 0.46 or less so that the chargeability is kept in a good state and the charge amount is adjusted to the optimum value.

The above-mentioned fixing resin can be synthesized by a known method. That is, the fixing resin can be synthesized by various polymerization methods such as suspension polymerization method, emulsion polymerization method, solution polymerization method, and bulk polymerization method. Further, the polymerization conditions are, for example, depending on the type and combination of the styrene-based monomer and the acrylic-based monomer, the weight ratio of the two, and the like, so that the properties of the fixing resin become the optimum properties for the toner,
Just set it. Furthermore, the molecular weight and the molecular weight distribution may be adjusted by selecting the type and amount of the polymerization initiator, the type of solvent related to chain transfer, the type of dispersant or the emulsifier, and the like.

In the toner of the present invention, for example, a colorant, a charge control agent, a release agent (offset preventing agent) and the like are added to the fixing resin composed of the styrene polymer and the styrene-acrylic copolymer. It is prepared by blending the agent and granulating into particles having an appropriate particle size, for example, a diameter of several tens of μm.

Examples of the colorant include various color pigments, extender pigments, conductive pigments, magnetic pigments, photoconductive pigments and the like. The colorant is 1 to 30 parts by weight, preferably 2 to 20 parts by weight, based on 100 parts by weight of the fixing resin.
Used in parts by weight. The above colorants, that is, the above pigments may be used alone or in combination of two or more, depending on the application.

The following are preferably used as the color pigment. [Black] Furnace Black, Channel Black,
Thermal, carbon black such as gas black, oil black, acetylene black, lamp black, aniline black [white] zinc white, titanium oxide, antimony white, zinc sulfide [red] red iron oxide, cadmium red, red lead, mercury sulfide, permanent red 4R, Resole Red, Pyrazolone Red, Watching Red Calcium Salt, Lake Red D, Brilliant Carmine 6B, Eosin Lake, Rhodamine Lake B, Alizarin Lake, Brilliant Carmine 3B [Orange] Red Mouth Lead, Molybdenum Orange, Permanent Orange GTR, Pyrazolo Orange, Vulcan orange, Indanthrene brilliant orange RK, Benzidine orange G, Indanthrene brilliant orange GK [yellow] Yellow lead, zinc white, cadmium Rho, yellow iron oxide, mineral fast yellow, nickel titanium yellow, navels yellow, naphthol yellow S, Hansa yellow G, Hansa yellow 10G, benzidine yellow G, benzidine yellow GR, quinoline yellow rake, permanent yellow NCG, tartrazine Lake [Green] Chrome Green, Chrome Oxide, Pigment Green B, Malachite Green Lake, Fanal Yellow Green G [Blue] Dark Blue, Cobalt Blue, Alkali Blue Lake, Victoria Blue Lake, Phthalocyanine Blue Partial Chloride, Fast Sky Blue, Inn Dunslen Blue BC [Purple] Manganese Purple, First Violet B, Methyl Violet Lake The color pigments are not limited to those exemplified above. .

Examples of extender pigments include barite powder,
Examples thereof include barium carbonate, clay, silica, white carbon, talc, and alumina white. Examples of the conductive pigment include conductive carbon black and aluminum powder. As the photoconductive pigment, for example,
Examples thereof include zinc oxide, selenium, cadmium sulfide, and cadmium selenide.

As the magnetic pigment, various ferrites such as iron trioxide (Fe ₃ O ₄ ), iron sesquioxide (γ-Fe ₂ O ₃ ), zinc iron oxide (ZnFe ₂ O ₄ ), yttrium iron oxide ( Y ₃ Fe ₅ O ₁₂ ),
Iron cadmium oxide (CdFe ₂ O ₄ ), iron gadolinium oxide (Gd
₃ Fe ₅ O ₁₂ ), iron oxide copper (CuFe ₂ O ₄ ), lead iron oxide (PbFe
₁₂ O ₁₉ ), iron neodymium oxide (NdFeO ₃ ), iron oxide barium (Ba
Fe ₁₂ O ₁₉ ), magnesium iron oxide (MgFe ₂ O ₄ ), iron manganese oxide (MnFe ₂ O ₄ ), lanthanum iron oxide (LaFeO ₃ ), iron powder, cobalt powder, nickel powder and the like.

As the charge control agent, positive charge control and negative charge control can be selectively used according to the polarity of the toner body. As the charge control agent for controlling the positive charge, an organic compound having a basic nitrogen atom, for example, a basic dye, an aminopyridine, a pyrimidine compound, a polynuclear polyamino compound, an aminosilane, or the like, is surface-treated with each of the above compounds. Examples include fillers and various quaternary ammonium salt compounds. As the charge control agent for controlling the negative charge,
Examples thereof include organic compounds having a carboxy group such as metal chelates of alkylsalicylic acid, metal complex salt dyes, fatty acid soaps, metal salts of naphthenic acid, and the like. The charge control agent is
0.1 to 10 parts by weight to 100 parts by weight of fixing resin,
It is preferably used in a proportion of 0.5 to 8 parts by weight.

Examples of the releasing agent include aliphatic hydrocarbons, aliphatic metal salts, higher fatty acids, aliphatic esters or partially saponified products thereof, silicone oil, and various waxes. Among other things, the weight average molecular weight (M
Aliphatic hydrocarbons having w) of about 1000 to 10000 are preferable. Specifically, for example, low molecular weight polypropylene (polypropylene wax), low molecular weight polyethylene (polyethylene wax), paraffin wax, carbon number 4
One or a combination of two or more low molecular weight olefin polymers composed of the above olefin units is suitable.
The release agent is 0.1 parts by weight to 100 parts by weight of the fixing resin.
It is used in a proportion of 10 parts by weight, preferably 0.5 to 8 parts by weight.

For the toner, a mixture obtained by homogeneously pre-kneading the above-mentioned respective components by, for example, a dry blender, a Henschel mixer, a ball mill, etc. It is prepared by uniformly melt-kneading using a kneading device, cooling the obtained kneaded product, pulverizing it, and classifying it if necessary. The toner can also be produced by a suspension polymerization method or the like.

Further, the above toner (in this case, the toner main body) can be used by adding carrier particles such as iron powder, glass beads, nickel powder and ferrite powder, if necessary. Further, in order to improve the fluidity of the toner main body, for example, hydrophobic colloidal silica fine powder or abrasive fine particles such as cerium oxide may be added and used.

[0042]

According to the constitution of claim 1, the fixing resin is
A styrene-based polymer having a maximum value in the range of molecular weight of 1 × 10 ^{3 to} 5 × 10 ³ , and a styrene-acrylic copolymer having a maximum value in the range of molecular weight of 3 × 10 ⁵ to 1 × 10 ^6. And the weight ratio of the styrene polymer to the styrene-acrylic copolymer is 1/1 to 9/1. Therefore, the toner containing the above-mentioned fixing resin maintains good storage stability, fixability, offset resistance, and the like. That is, the above-mentioned toner is capable of satisfying the above-mentioned various characteristics and is suitable for a heat roller fixing method, particularly a so-called high-speed heat roller fixing method.

According to the second aspect of the present invention, in the fixing resin, the weight ratio of the acrylic monomer used for the fixing resin is 0.05 to 0.3. For this reason, the toner containing the above-mentioned fixing resin can maintain the storage property, the fixing property, the anti-offset property, and the like, as well as the charging property and the like.

According to the third aspect of the present invention, the fixing resin is such that the weight ratio a of the acrylic monomer used for the fixing resin is a.
And the weight ratio b of the styrene-acrylic copolymer in the fixing resin satisfy the relationship of 0.26≤a + 0.6b≤0.46. For this reason, the toner containing the above-mentioned fixing resin maintains the chargeability and the like as well as the storage stability, the fixability and the offset resistance.

Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples and Comparative Examples.

[0046]

【Example】

[Example 1] In the molecular weight distribution of GPC, the molecular weight was 4 ×
Styrenic polymer having a maximum value of 10 ³ and a molecular weight of 7 ×
A styrene-acrylic copolymer having a maximum value of 10 ⁵ is used, and the weight ratio (styrene-based polymer / styrene-acrylic-based copolymer) of the styrene-based polymer and the styrene-acrylic-based copolymer is 63/37, acrylic monomer weight ratio (acrylic monomer / (acrylic monomer + styrene monomer)) 0.15, weight ratio B 0.37, low molecular weight acrylic monomer Weight ratio of (low molecular weight side acrylic monomer /
(Low molecular weight acrylic monomer + styrene monomer))
A fixing resin having a value of 0 was prepared.

Next, 100 parts by weight of this fixing resin, 6 parts by weight of carbon black as a colorant, 2 parts by weight of a quaternary ammonium salt compound as a charge control agent, and polypropylene wax 2 as a release agent. A mixture was obtained by pre-kneading 1 part by weight of polyethylene wax and 1 part by weight of polyethylene wax. The resulting mixture was uniformly melt-kneaded using a twin-screw extrusion kneader, then cooled and pulverized to prepare a toner main body having an average particle diameter of 10 μm. Further, 0.2% by weight of hydrophobic colloidal silica fine powder was added to the toner body to improve fluidity, and silicone-coated ferrite powder was added as carrier particles. In this way, the toner was created.

Then, a storage stability test, a fixing property test, a hot offset test (offset resistance test), and a charging property test were conducted on the above toner. The conditions of each of the above tests are shown below.

Storability test: 300 g of toner was placed in a container, placed in an oven set to a temperature of 50 ° C. and left for 2 days. Then, the toner was taken out and filled in a toner hopper of an electrophotographic copying machine (SF-2022) manufactured by Sharp Corporation. Then, the electrophotographic copying machine
By operating for a minute, the toner supply state to the photosensitive drum during this period was examined, and the following sizing was performed to evaluate the storability of the toner.

◯: Good supply condition, that is, good storability, Δ: Practical problem with slight uneven supply, ×: Poor supply condition such as blocking phenomenon, that is, poor storability.

Fixability test: An electrophotographic copying machine (SF-2022) manufactured by Sharp Co., Ltd. was filled with toner, and a copy was made at a set temperature of 170 ° C. using a gray scale as an original. Then the resulting toner image (ie transfer paper)
The toner was rubbed a predetermined number of times with a sand-containing eraser while a predetermined pressure was applied, the residual ratio of the toner image, that is, the fixing state of the toner was examined, and the fixing performance of the toner was evaluated by performing the following ranking.

◯: Fixing condition is good, that is, fixing property is good, Δ: There is some fixing unevenness, but there is no problem in practical use, ×: Poor fixing condition, that is, fixing property is poor.

Hot offset test: A modified machine (model adopting a heating and pressure roller fixing system) of an electrophotographic copying machine (SF-2022) manufactured by Sharp Corporation was filled with toner, and a so-called black solid paper was copied as an original. Then, the obtained transfer paper was passed through the above-mentioned modified machine to determine the temperature at which the offset phenomenon occurred. The temperature of the heating pressure roller was initially set to 140 ° C. and increased from 140 ° C. by 5 ° C. to a predetermined temperature until the offset phenomenon occurred. And by performing the ranking shown below,
The offset resistance of the toner was evaluated.

◯: The offset phenomenon did not occur, that is, the offset resistance was good, Δ: The offset phenomenon occurred slightly, but there was no practical problem. ×: The offset phenomenon occurred, that is, the offset resistance was poor.

Charging Test: The toner charge amount was measured using a blow-off charge amount measuring device manufactured by Toshiba Corporation. In addition, an electrophotographic copying machine (SF
-2022) was filled with toner, and a predetermined paper was copied as an original. Then, the image density (ID) of the obtained toner image and the background density (BG) were compared, and the charging property of the toner was evaluated by performing the following ranking.

◯: good chargeability, Δ: slightly poor chargeability but no practical problem, x: poor chargeability.

The results of each of the above tests are summarized in Table 1. As is clear from the results shown in Table 1, the toner according to this example is excellent in various characteristics such as storage stability, fixability, anti-offset property, and charging property. That is,
It can be seen that the toner according to this example satisfies these characteristics.

Example 2 In place of the fixing resin used in Example 1, the weight ratio of the styrene polymer and the styrene-acrylic copolymer was 55/45, and the weight ratio of the acrylic monomer was 0.10. A toner was prepared in the same manner as in Example 1 except that the weight ratio B was 0.37, the other weight ratios and the two fixing values were the same as those of the fixing resin of Example 1 above. Then, each test was performed on the above toner.

The results of each test thus obtained are summarized in Table 1. As is clear from the results shown in Table 1, the toner according to this example has various characteristics such as storage stability, fixability, offset resistance, and chargeability, similar to the toner of Example 1. I understand. That is, it is understood that the toner according to this embodiment satisfies these characteristics.

Comparative Example 1 A styrene-based polymer having a maximum value in the molecular weight of 0.8 × 10 ³ (that is, 8 × 10 ² ) was used instead of the styrene-based polymer in the fixing resin of Example 1. A toner was prepared in the same manner as in Example 1.
Then, each test was performed on the above toner.

The results of each test thus obtained are summarized in Table 1. As is clear from the results shown in Table 1, the toner according to this comparative example is inferior to the toner of Example 1 in storage stability, offset resistance, and chargeability.

Comparative Example 2 A styrene-based polymer having a maximum value in the molecular weight of 20 × 10 ³ (that is, 2 × 10 ⁴ ) was used in place of the styrene-based polymer in the fixing resin of Example 1. A toner was prepared in the same manner as in Example 1.
Then, each test was performed on the above toner.

The results of each test thus obtained are summarized in Table 1. As is clear from the results shown in Table 1, the toner according to this comparative example is inferior in fixability to the toner of Example 1.

Comparative Example 3 A molecular weight of 2.5 was used in place of the styrene-acrylic copolymer in the fixing resin of Example 1.
A toner was prepared in the same manner as in Example 1 except that a styrene-acrylic copolymer having a maximum value of × 10 ⁵ was used. Then, each test was performed on the above toner.

The results of each of the tests thus obtained are summarized in Table 1. As is clear from the results shown in Table 1, the toner according to this comparative example is inferior in offset resistance and chargeability to the toner of Example 1.

[Comparative Example 4] Instead of the styrene-acrylic copolymer in the fixing resin of Example 1, a molecular weight of 12 × was used.
A toner was prepared in the same manner as in Example 1 except that a styrene-acrylic copolymer having a maximum value of 10 ⁵ (that is, 1.2 × 10 ⁶ ) was used. Then, each test was performed on the above toner.

The results of each test thus obtained are summarized in Table 1. As is clear from the results shown in Table 1, the toner according to this comparative example is inferior in fixability and chargeability to the toner of Example 1.

Comparative Example 5 Instead of the fixing resin in Example 2, the weight ratio of the styrene polymer to the styrene-acrylic copolymer was 45/55, the weight ratio B was 0.43, and A toner was prepared in the same manner as in Example 2 except that the fixing resin having the same weight ratio and two maximum values as the fixing resin of Example 2 was used. Then, each test was performed on the above toner.

The results of each of the tests thus obtained are summarized in Table 1. As is clear from the results shown in Table 1, the toner according to this comparative example is inferior in fixability and chargeability to the toner of Example 2.

Comparative Example 6 Instead of the fixing resin in Example 2, the weight ratio of the styrene polymer and the styrene-acrylic copolymer was 95/5 and the weight ratio B was 0.13. A toner was prepared in the same manner as in Example 2 except that the fixing resin having the same weight ratio and two maximum values as the fixing resin of Example 2 was used. Then, each test was performed on the above toner.

The results of each of the tests thus obtained are summarized in Table 1. As is clear from the results shown in Table 1, the toner according to this comparative example is inferior to the toner of Example 2 in storage stability, offset resistance, and chargeability.

Comparative Example 7 In place of the fixing resin used in Example 2, the weight ratio of the low molecular weight side acrylic monomer was 0.20.
A toner was prepared in the same manner as in Example 2 except that the fixing resin having the other weight ratio and the two maximum values equal to those of the fixing resin of Example 2 was used. Then, each test was performed on the above toner.

The results of each test thus obtained are summarized in Table 1. As is clear from the results shown in Table 1, the toner according to this comparative example is inferior in storage stability and chargeability to the toner of Example 2.

[Comparative Example 8] Instead of the fixing resin in Example 2, the acrylic monomer had a weight ratio of 0.03 and a weight ratio of B.
Was 0.30, and a toner was prepared in the same manner as in Example 2 except that a fixing resin having the other weight ratio and two maximum values equal to those of the fixing resin of Example 2 was used. Then, each test was performed on the above toner.

The results of each test thus obtained are summarized in Table 1. As is clear from the results shown in Table 1, the toner according to this comparative example is inferior in charging property to the toner of Example 2.

[Comparative Example 9] Instead of the fixing resin used in Example 2, the acrylic monomer had a weight ratio of 0.37 and a weight ratio B.
Was 0.64, a toner was prepared in the same manner as in Example 2 except that a fixing resin having the other weight ratio and two maximum values equal to those of the fixing resin of Example 2 was used. Then, each test was performed on the above toner.

The results of each test thus obtained are summarized in Table 1. As is clear from the results shown in Table 1, the toner according to this comparative example is inferior in storage stability and chargeability to the toner of Example 2.

Comparative Example 10 Instead of the fixing resin used in Example 2, the weight ratio of the styrene polymer and the styrene-acrylic copolymer was 90/10, and the weight ratio of the acrylic monomer was 0.20. A toner was prepared in the same manner as in Example 2 except that the weight ratio B was 0.26, the other weight ratios and the two maximum values were the same as those of the fixing resin of Example 2 above. Then, each test was performed on the above toner.

The results of each test thus obtained are summarized in Table 1. As is clear from the results shown in Table 1, the toner according to this comparative example is inferior to the toner of Example 2 in storage stability, offset resistance, and chargeability.

Comparative Example 11 Instead of the fixing resin in Example 2, the weight ratio of the styrene polymer and the styrene-acrylic copolymer was 50/50, and the weight ratio of the acrylic monomer was 0.20. A toner was prepared in the same manner as in Example 2 except that the weight ratio B was 0.50, the other weight ratios and the two fixing values were the same as those of the fixing resin of Example 2 above. Then, each test was performed on the above toner.

The results of each test thus obtained are summarized in Table 1. As is clear from the results shown in Table 1, the toner according to this comparative example is inferior in fixability and chargeability to the toner of Example 2.

As described above, the toners of Comparative Examples 1 to 11 cannot satisfy some of the various characteristics such as storage stability, fixability, offset resistance, and chargeability. I understand.

[0083]

[Table 1]

[0084]

According to the above constitution, the fixing resin comprises a styrene polymer having a maximum value in the range of 1 × 10 ^{3 to} 5 × 10 ³ , and a molecular weight of 3 × 10 ⁵ to 1 × 10 3. ^It is composed of a styrene-acrylic copolymer having a maximum value in the range of ⁶ , and the weight ratio of the styrene polymer and the styrene-acrylic copolymer is 1/1 to 9/1. . In the fixing resin, the weight ratio of the acrylic monomer used for the fixing resin is 0.05 to 0.3. Furthermore, the fixing resin is
The weight ratio a of the acrylic monomer used for this and the weight ratio b of the styrene-acrylic copolymer in the fixing resin.
And satisfy the relationship of 0.26 ≦ a + 0.6b ≦ 0.46.

Therefore, the electrophotographic developer containing the above-mentioned fixing resin is liable to have storability, fixability, offset resistance, and
Good chargeability and the like are maintained. As a result, the above-mentioned electrophotographic developer can satisfy the above-mentioned various characteristics and is suitable for a heat roller fixing method, particularly a so-called high-speed heat roller fixing method.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasuharu Morinishi 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka

Claims (3)

[Claims] 1. A gel carrier liquid chromatogram having a molecular weight distribution of 1 × 10 ^{3 to} 5 × 10 ³ having a maximum value derived from a styrene-based polymer and having a molecular weight of 3 in the molecular weight distribution.
It has a maximum value derived from a styrene-acrylic copolymer within the range of 10 ⁵ to 1 × 10 ⁶ , and the weight ratio of the styrene polymer and the styrene-acrylic copolymer (styrene-based copolymer). Polymer / styrene-acrylic copolymer) is 1
An electrophotographic developer comprising a fixing resin having a ratio of / 1 to 9/1. 2. The weight ratio (acrylic monomer / (acrylic monomer + styrene monomer)) of the acrylic monomer used for the fixing resin is 0.05 to 0.3. The electrophotographic developer according to claim 1, which is characterized in that. 3. A weight ratio a of an acrylic monomer used for a fixing resin (acrylic monomer / (acrylic monomer + styrene monomer)) and styrene in the fixing resin. -The weight ratio b of the acrylic copolymer (styrene-acrylic copolymer / (styrene-based polymer + styrene-acrylic-based copolymer)) satisfies the relationship of 0.26≤a + 0.6b≤0.46. The electrophotographic developer according to claim 1, which is characterized in that.