JPH02118669A - Electrophotographic toner and electrophotographic developing agent - Google Patents

Abstract

PURPOSE:To improve fixing characteristics and offsetting resistance selectively and to improve also blocking resistance of a toner as well by regulating a weight average mol.wt. and an MI value of a styrene/acrylic copolymer to be used as a material for the toner. CONSTITUTION:At least two kinds of uncrosslinked styrene/acrylic copolymer having each specified weight average mol.wt. and specified MI value are blended. Concretely, an uncrosslinked styrene/acrylic copolymer(A) having 80000-200000 weight average mol.wt. and 1-9g/10min MI value is mixed with an uncrosslinked styrene/acrylic copolymer (B) having the same weight average mol.wt. and 10-20g/10min MI value in 10/90-60/40 weight ratio of B/A. Thus, an electrophotographic toner having sufficiently high fixing characteristics, offsetting resistance and high blocking resistance is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an electrophotographic toner and an electrophotographic developer for developing a latent image in electrophotography.

<Prior Art> As a developing toner for electrostatic image development in an electrophotographic apparatus, a one-component type toner that does not use a carrier or a two-component type toner that uses a carrier is used.

These one-component and two-component toners are usually manufactured as follows.

First, resin, wax, pigment, charge control agent, etc. are mixed,
After melting, mixing, and cooling, it is crushed and classified to obtain charged toner particles. Then, a fluidizing agent, a resistance control agent, etc. are usually externally added to the charged toner particles.

The resin used here is required to have high various thermal properties such as fixing properties, anti-offset properties, and anti-blocking properties.

Therefore, as resins or resin compositions with good thermal properties, styrene-acrylic copolymers cross-linked with a cross-linking agent or styrene-acrylic cross-linked resins are mixed with ordinary styrene-acrylic non-cross-linked resins. is used.

Electrophotographic toners using these resins are disclosed, for example, in JP-A-55-147639, JP-A-59-88748, JP-A-60-4946, JP-A-60-46565, and JP-A-6159345. has been done.

However, when these crosslinked resins are used, a non-crosslinking agent is used, which increases the number of steps for producing an electrophotographic toner, and also complicates the management and control of the production.

Therefore, an example of a resin composition for toner based on styrene-acrylic type in which no crosslinked resin is used is disclosed in Japanese Patent Application Laid-Open No. 61-184.
Publication No. 553, Publication No. 62-115170, Special Publication No. 6
It is disclosed in JP 3-32180, JP 63-32183, and the like.

The resin composition described in JP-A-61-184553 is
For example, by blending two types of styrene-acrylic non-crosslinked resins with weight average molecular weights MMW 113,000 and Mw 48,000, the melt viscosity characteristic is 5X10'voice or less at 100°C.
At 120°C, 1 x 10 r' voids or more and 7g or more at 65°C.

Further, the resin composition described in JP-A-62-115170 has a Mw of 10,000 to 30,000, a Tg of 60 to 70°C, and an M of
w 200,000 to 400,000, Tg 55 to 65°C two types of styrene-acrylic copolymers were mixed at a predetermined weight ratio, and 140
The melt viscosity at °C is 10,000 voids or less.

Also, Japanese Patent Publication No. 63-32180, No. 63-321
In Publication No. 83, in the GPC chromatogram, ],
Blends of styrene-acrylic copolymers having maximum values of 0,000 to 2,000,000 and 1,000 to 800,000 are disclosed.

Since these methods use non-crosslinked resins, electrophotographic toners can be manufactured easily.

<Problems to be Solved by the Invention> However, the current situation is that these methods do not provide various properties such as sufficient fixing properties, anti-offset properties, and anti-blocking properties.

More specifically, the fixing performance at low temperatures, for example, about 130° C. or lower, is insufficient. Further, the temperature range in which offset resistance is exhibited is narrow, and offset occurs at temperatures below 210°C.
A resin composition that exhibits good fixing properties and anti-offset properties has not yet been realized.

An object of the present invention is to provide a good electrophotographic toner and an electrophotographic developer that have excellent fixing properties and anti-offset properties using a non-crosslinked resin that is easy to manufacture.

<Means for Solving the Problems> Such objects are achieved by the following inventions (1) and (2).

(1) Each weight average molecular weight is 80,000 to 200
,000 non-crosslinked styrene-acrylic copolymer with an MI value of 1 to 9 g710 m1n, and a resin A with an MI value of 1
Electrophotographic toner (2) containing 0 to 20 g/l 0 m1n of resin B at a B/A weight ratio of 10/90 to 60/40. An electrophotographic developer, characterized in that it contains a toner and carrier particles.

Effect> In the present invention, as the resin for the electrophotographic toner, a resin having a predetermined weight average molecular weight and a predetermined MI value is used.
In both cases, two types of non-crosslinked styrene-acrylic copolymer resins are used and blended.

This selectively improves fixing properties and anti-offset properties.
- to do.

In addition, the combination of two types of non-crosslinked styrene-acrylic copolymers having a weight average molecular weight and an MI value in the present invention has not been previously known.

<Specific Structure of the Invention> As the resin used in the electrophotographic toner, a styrene-acrylic copolymer is particularly used.

A styrene-acrylic copolymer is obtained by a copolymerization reaction between a styrene monomer and a copolymerizable acrylic monomer.

In this case, the copolymerizable styrenic monomers include styrene and its derivatives.

In addition, examples of acrylic monomers include methyl acrylate,
Ethyl acrylate, isopropyl acrylate, n-butyl acrylate, α-ethylhexyl acrylate, α-hydroxyethyl acrylate, hydroxypropyl acrylate, medyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, Isobutyl methacrylate, n-hexyl methacrylate, lauryl methacrylate, α-hydroxyedyl methacrylate,
Examples include acrylic esters or methacrylic esters such as hydroxypropyl methacrylate; acrylamides such as acrylamide, diacetone acrylamide, and N-methylol acrylamide;

In this case, (meth)acrylic acid esters are suitable as the acrylic monomer.

The molar ratio of the styrene monomer to the acrylic monomer in the styrene-acrylic copolymer may range from 1:1 to 10:1.

In addition, the styrene-acrylic copolymer may contain 5 mol% or less of vinyl monomers such as vinyl esters, ethylene olefins, and ethylenically unsaturated carboxylic acids.

In the present invention, two or more types of such styrene-acrylic copolymers are used. Moreover, such a styrene-acrylic copolymer does not contain a crosslinking agent and is non-crosslinked.

The two or more types of non-crosslinked styrene-acrylic copolymers each have a weight average molecular weight of 80.000 to 200,00.
0, preferably ioo, ooo to 200,000.

If the weight average molecular weight is less than the above range, the offset resistance will be poor, and if it exceeds the above range, the fixing property will be poor.

The weight average molecular weight can be measured, for example, by gel permeation chromatography (manufactured by Shimadzu Corporation).

Furthermore, resin A and resin B, which are non-crosslinked styrene-acrylic copolymers, have such weight average molecular weights.
has a predetermined MI value (melt index).

The MI value is defined in JISK-7210, and the MI value of resin A is 1 to 9 g/l 0 m1n.

The MI value of resin B is 10 to 20 g/l 0 m1n.

Combinations of resins with MI values outside the above range result in insufficient fixing properties and offset resistance.

In this case, the MI value is an index of how much molten resin flows out at a constant pressure and a constant temperature, and is a value indicating the amount of flow out per 10 minutes. At this time, JISK-72
Measurement is carried out by incorporating the manual cutting method of the thermoplastic plus deck flow test method as described in No. 10. Two or more types of each of resin A and resin B may be used.

The weight ratio B/A of resin A and resin B is 10/90.
~60/40, preferably 20/80~50150.

If the weight ratio B/A is outside the above range, fixing properties and anti-offset properties will deteriorate.

The electrophotographic toner of the present invention contains the resins A and B described above as binders.

In the binder, other styrene-acrylic copolymers, polyesters, epoxy resins, silicone resins, fluororesins, polyamide resins, acrylic resins, polyurethane resins, polyether resins, polyvinyl alcohol resins,
One or more of polyethylene, ethylene vinyl acetate copolymer, and polypropylene may be contained in an amount of 10% by weight or less.

The average particle diameter of the toner particles is preferably 5 to 25 μs, more preferably 6 to 25 μs, particularly preferably 8 to 20 μs.

When the average particle size is less than 5, the fluidity of the developer deteriorates and developer caking and adhesion to the sleeve tend to occur, and when it exceeds 25, resolution tends to deteriorate and poor fixing properties tend to occur. becomes.

To measure the average particle size of toner particles, the volume particle size of the measured value is calculated by the Coulter counting method, and the 50% average particle size is taken as the average particle size.

In the Coulter counting method, Isoton II (manufactured by Coulter Electronics) is used as the electrolyte.
For example, a Coulter counter TA-II (manufactured by Coulter Electronics) with an aperture diameter of 100) 1711
Perform volume-based measurements using

In addition, the particle size distribution is generally calculated as 2 when the average particle size is J.
1 or more is 10% by volume or less, especially about O to 6% by volume, H/
2 or less is preferably 10% by volume or less, particularly about 0 to 6% by volume.

By using particles with such a particle size distribution, sufficient fluidity and good image quality can be obtained, and in addition, the toner yield and
Yield is improved and manufacturing becomes easier.

Toner particles having such a particle size may be one-component or two-component, and contain magnetic powder and/or colorant, and a binder containing the resins A and B described above. .

Magnetic powders include iron, manganese, cobalt, nickel,
Metals such as chromium or their alloys, chromium oxide,
Metal oxides such as iron sesquioxide and triiron tetroxide,
O-Fe20x (M is Fe, Mn, Go, Ni, Mg,
Any conventionally known magnetic material can be used, such as ferrite represented by one or more metals selected from the group of monovalent or divalent metals such as Zn, Cd, Ba, and Li. It is.

The amount of magnetic powder in the magnetic toner particles containing these magnetic powders and the resins A and B is preferably 10 to 70% by weight, more preferably 20 to 60% by weight.

When it is less than 10% by weight, the magnetic force from the magnet inside the developing machine is not sufficiently transmitted, and fogging, toner scattering, etc. tend to worsen. Moreover, if it exceeds 70% by weight, the fixing properties of the toner tend to deteriorate.

The non-magnetic toner may also contain the resin and colorant described above.

There are no particular restrictions on the colorant used, but suitable colorants include, for example, black pigments such as carbon black, acetylene black, channel black, and aniline black; Dialite Yellow GR, Variotol Yellow 1090
red pigments such as Permanent Red E5B and Rhodamine 2B; blue pigments such as copper phthalocyanine and cobalt blue; green pigments such as Pigment Green B; and orange pigments such as pyrazolone orange.

The content of such a colorant is based on 100% resin of toner particles.
It is preferably about 1 to io parts by weight.

Note that colorants such as these may be used in combination with magnetic powder.

Various internal additives may be further added to such toner particles.

Waxes are an example of internal additives.

The wax is used to prevent the so-called offset phenomenon that occurs during fixing with a fixing roll, and uses, for example, low molecular weight polyethylene, polypropylene, metal salts of fatty acids, silicone oil, and the like.

Such products include polyethylene such as Hiwax 100P and Hiwax 110P [Mitsui Petrochemical Industries, Ltd.], Viscoel 550P, and Viscole 330P.
[Polypropylene, zinc stearate 601, zinc stearate CP from Sanyo Kasei Kogyo Co., Ltd. [Fatty acid metal salts, silicone oil KF, etc. from Nitto Kasei Kogyo Co., Ltd.]
96, silicone oil K F 69 H [Shin-Etsu Silicone Co., Ltd.], and the like.

Fluororesins are also effective as mold release agents having such functions.

These substances having a release effect are 0.1 to 10 parts by weight, more preferably 1 to 10 parts by weight, per part by weight of toner particles].
It is preferable to contain 5 parts by weight.

Inorganic or organic pigments can also be used as resistance control agents.

In addition, internal additives include fluidity improvers, resistance adjusters, etc., which will be described later.

Further, a charge control agent may be added internally.

Examples of the charge control agent include metal complexes such as azo dye metal complexes, dyes such as nigrosine dyes, and quaternary ammonium salt type dyes.

To such toner particles, inorganic or organic fine particles such as a resistance adjuster, a colorant, a fluidity improver, etc. can be externally added as additive particles.

Examples of these include colloidal silica, metal oxides such as titanium oxide, zinc oxide, and alumina, inorganic fine particles such as silicon carbide, calcium carbonate, barium carbonate, and calcium silicate, magnetic particles, PMMA, polyethylene, nylon, silicone resin, and phenol. resin, benzoguanamine resin, polymer beads such as polyester, polytetrafluoroethylene, polytetrafluoroethylene,
Fluorine-containing organic fine particles such as polyvinylidene fluoride, fatty acid metal salts such as zinc stearate and magnesium stearate, black pigments such as carbon black, acetylene black, channel black, and aniline black, Dialite Yellow GR, Variol Yellow 1090
Yellow pigments such as Permanent 1/Tsudo E5B, red pigments such as Rhodamine 2B, blue pigments such as copper phthalocyanine and cobalt blue, green pigments such as Pigment Green B, orange pigments such as pyrazolone orange, and the charge control agents described above. Can be mentioned.

In addition, although only one type of these additive particles may be used, two or more types can also be used in combination as required.

Further, the above-mentioned mold release agent can also be externally added as additive particles.

These additive particles are dry mixed with the toner particles.

At this time, each additive particle may be subjected to a coupling agent such as ditanate, aluminum, or silane, silicone oil, or other organic or inorganic treatment for surface hydrophobization treatment and surface dispersion improvement treatment. .

These additive particles have an average particle size of about 0.005 to 5-. Further, the amount of external addition is approximately 0.1 to 8% by weight.

In addition, in the case of a particle size of 1 or less, it is measured using an electron microscope.

Such additive particles are dry-mixed with toner particles using a Henschel mixer, grind mixer, blender, Nauta mixer, etc., and then adsorbed or fixed on the surface of the toner particles, and are further removed by mechanical strain, heat, etc. , which are fixedly integrated and embedded in the surface of the toner particles.

In order to produce the electrophotographic toner of the present invention, as one example, resins A and B and other raw material compositions are sufficiently mixed in a Henschel mixer, and then kneaded in a hot melt mixer. After that, it was cooled and coarsely ground in a hammer mill.

Finely pulverize using a jet impact mill.

Next, the additive particles to be externally added are dry mixed using, for example, a Henschel mixer.

The electrophotographic toner thus obtained, in the case of a magnetic toner or a non-magnetic one-component toner, can be directly used as a one-component developer.

In addition, the electrophotographic toner of the present invention is preferably mixed with carrier particles and used as a two-component developer.

The carrier particles to be used are not particularly limited, and known carrier particles made of Fe, various types of ferrite, etc. may be used, but it is preferable to use ferrite because charging can be easily controlled.

In the present invention, the volume average particle diameter of the carrier particles is preferably 20 to 120, more preferably 50 to 100.
It is a door.

In the electrophotographic developer of the present invention comprising such carrier particles and the above electrophotographic toner, the content of the electrophotographic toner is preferably 2 to 12% by weight.
, more preferably 3 to 10% by weight.

Such an electrophotographic developer of the present invention can be developed by a magnetic brush development method, or if necessary, a cascade method, a bristle brush method, or a magnetic brush development method.
It is used in dry developing methods such as the powder cloud method to achieve certain effects.

<Example> Hereinafter, the present invention will be explained in further detail by giving specific examples of the present invention.

Example 1 Styrene-acrylic copolymer resin A1 Styrene-butyl acrylate MI value 5.7 g 710 m1n Weight average molecular weight Mw 160,000 43 parts by weight (measured by GPC) Styrene-acrylic copolymer resin B1 Styrene-acrylic Butyl acid MI value 10.3 g/l 0 min Mw 125,000 43 parts by weight Polypropylene wax (Viscol 550P, manufactured by Mitsubishi Chemical Industries, Ltd.) 4.5 parts by weight Charge control agent (Subiron Black TRH, manufactured by Hodogaya Chemical Co., Ltd.) 2.0 Parts by weight of carbon black (MA-100 manufactured by Mitsubishi Chemical Industries, Ltd.) 7.5 parts by weight or more of raw materials were blended, melted, mixed, cooled, and coarsely ground using a hammer mill. The powder was then finely pulverized with a jet mill and classified to produce a toner having a volume average particle diameter of 11111, which was used as a base toner.

Next, silica (R-972 manufactured by Nippon Aerosil Co., Ltd. with an average particle size of 0
．． 01un+) was added in an amount of 0.3% by weight based on the base toner and mixed in a blender to obtain a chargeable toner. This is referred to as toner 1.

Comparative Example 1 In Example 1, resins A1 and B1 were replaced with resin A1.8.
A chargeable toner was obtained in the same manner as in Example 1, except that the amount was changed to 6 parts by weight.

This is referred to as toner 2.

Comparative Example 2 In Example 1, resins A1 and B1 were replaced with resin B1.8.
A chargeable toner was obtained in the same manner as in Example 1, except that the amount was changed to 6 parts by weight. This is referred to as toner 3.

Example 2 Styrene-acrylic copolymer resin A2 Styrene-butyl acrylate-methyl methacrylate MI value 8.5 g/l 0 min Mw 140,000 69 parts by weight Styrene-acrylic copolymer resin B2 Styrene-butyl acrylate MI value 19.9g/l 0min Mw 162,000 17 parts by weight Polypropylene wax (Viscol 550P, manufactured by Mitsubishi Chemical Industries, Ltd.) 4.5 parts by weight Charge control agent (Subiron Black T RH, manufactured by Hodogaya Chemical Industries, Ltd.) 2.0 A chargeable toner was obtained according to Example 1 using 7.5 parts by weight or more of carbon black (MA-100 manufactured by Mitsubishi Chemical Industries, Ltd.) as a raw material.

This is referred to as toner 4.

Comparative Example 3 In Example 2, resins A2 and B2 were replaced with resin A2.8.
A chargeable toner was obtained in the same manner as in Example 1 except that the amount was changed to 6 parts by weight.

This is referred to as toner 5.

Comparative Example 4 In Example 2, resins A2 and B2 were replaced with resin B2.8.
A chargeable toner was obtained in the same manner as in Example 1 except that the amount was changed to 6 parts by weight. This is referred to as toner 6.

Various toners and carriers from 1 to 6 above (TDK TF-
3044 average particle size 100ha, HC18 at 50000e
0e, a, n40emu/g) was mixed and used as a developer with a toner concentration of 4%, and its fixing properties, anti-offset properties, and anti-blocking properties were measured. The results are shown in Table 1.

The fixing properties were determined at a paper speed of 250 mm/s and a fixing pressure of 4.
0 kgf, set to a predetermined temperature, and determined from the rate of change in image source intensity.

The judgment criteria are as follows.

Rate of change: 90% or more: 0 80-90%: 0 70-80%: Δ 70% or less: X From Table 1, all toners show good results in terms of blocking resistance.

Furthermore, regarding the fixing properties, it can be seen that Toner 1 is improved compared to Toner 2, and Toner 4 is improved compared to Toner 5.

In particular, regarding offset resistance, the temperature range in which offset resistance is exhibited is expanding.

Example 3 and Comparative Examples 5 to 14 Toners 7 to 17 were prepared in Example 1 except that the styrene-acrylic copolymer used was changed to those shown in Table 2 below, and similar experiments were conducted. All resin compositions are
Styrene-butyl acrylate. The results are shown in Table 2.

The offset resistance was tested at 140° C. and 210° C., and the evaluation criteria were as follows.

Almost no offset 20 Some offset: △ Significant offset: X From the results shown in Table 2, the effects of the present invention are clear.

<Effects of the Invention> As described above, in the electrophotographic toner of the present invention, the weight average molecular weight and MI of the styrene-acrylic copolymer used are
By regulating the value, fixing properties and anti-offset properties can be selectively improved. Furthermore, the blocking resistance is also good.

Claims (2)

[Claims] (1) Each weight average molecular weight is 80,000 to 200
,000 non-crosslinked styrene-acrylic copolymer with an MI value of 1 to 9 g/10 min, and a resin A with an MI value of 1.
An electrophotographic toner comprising 0 to 20 g/10 min of resin B at a B/A weight ratio of 10/90 to 60/40. (2) An electrophotographic developer comprising the electrophotographic toner according to claim 1 and carrier particles.