JPH03168648A - Releasing agent for electrophotographic toner - Google Patents

Abstract

PURPOSE:To enhance hot offset resistance and electric chargeability stability without deteriorating the fluidity of a toner by incorporating a specified polyolefin type resin as a releasing agent. CONSTITUTION:The polyolefin resin having a volume average particles diameter of <= 10mum and a melt viscosity of <=1,000cp at 160 deg.C and a durometer hardness of >=30 is dispersed into the toner. Resins to be used as this resin are enumerated as follows: A; polyethylene, polypropylene, and an ethylene-alpha-olefin copolymer each low in melt viscosity, B; the adducts of the following monomers to A; ethylenically unsaturated monomers, acrylic esters, maleic acid derivatives, and those substituted by F or substituted by silane C; D as the oxides of A; ethylenically unsaturated carboxylic acids or their esters.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a release agent for electrophotographic toner.

More specifically, the present invention relates to a release agent for electrophotographic toner that is suitable for use in heat-fixing type copying machines or printers and has excellent hot offset resistance and charging stability.

[Conventional Technology Co-thermal fixing toner is fixed on a support by a heat roll. In this case, it is desired that the lower limit temperature of fixing is low. On the other hand, when the roll temperature increases, a phenomenon occurs in which toner sticks to the roll. It is desirable that the temperature at which this hot offset occurs is high. Generally, as the molecular weight of the binder increases, the hot offset temperature increases, but at the same time, the minimum fixing temperature also increases. Conversely, when the molecular weight decreases, both the hot offset temperature and the lower limit fixing temperature decrease.

In order to satisfy these contradictory performance requirements, electrophotographic toners (e.g. Japanese Patent Publication No. 3304/1983) in which a release agent such as low molecular weight polypropylene is added during toner production to increase the hot offset temperature, and release agents used during binder production are used. A method of polymerizing in the presence of a molding agent (for example, JP-A-60-8
3039) is known.

[Problems to be Solved by the Invention] However, since the particle size of the release agent in the prior art is larger (for example, about 50μ) than the toner particle size (for example, about 10μ), the release agent is not used during toner or binder production. If you try to add it, not only will excessive mixing power be required for melt mixing, but the release agent will not be sufficiently dispersed in the toner, resulting in a decrease in toner fluidity and toner agglomeration, resulting in insufficient toner supply within the copying machine. Furthermore, release agent particles may be released in the developer, resulting in deterioration of charging stability.

[Means for Solving the Problems] The present inventor has developed a release mold for electrophotographic toner that can be easily dispersed in toner, has a high hot offset temperature, and has excellent charging stability without reducing the fluidity of the toner. As a result of extensive research into agents, the present invention was arrived at. That is, in the present invention, the volume average particle diameter is 10μ or less, and 160μ
This release agent for electrophotographic toner is characterized by being made of a polyolefin resin having a melt viscosity of 1000 cps or less at °C and a durometer hardness of 30 or more.

The polyolefin resin according to the present invention is a polyolefin resin with a low melt viscosity, such as 1): low melt viscosity polyethylene, polypropylene, ethylene-α-olefin (3 to 8 carbon atoms) copolymer (for example, ethylene-propylene copolymer). 2): Ethylenically unsaturated monomers of 1) (styrene, (meth)acrylic esters, maleic acid derivatives (maleic anhydride, maleic dimethyl ester, maleic diethyl ester, maleic acid) di-2-ethylhexyl ester, etc.)) and their fluorine-substituted derivatives (
For example, perfluorohexaethyl methacrylate, etc.)
, adducts such as silane-substituted derivatives (e.g. triethoxyvinylsilane, etc.), 3): oxides of 1), 4): ethylenically unsaturated carboxylic acids ((meth)acrylic acid, itaconic acid, etc.) and/or esters thereof (Copolymers of alkyl (C1-C18) esters, etc. and ethylenically unsaturated hydrocarbons (ethylene, propylene, butene, etc.), and mixtures thereof are mentioned.

The method for producing the polyolefin resin according to the present invention is 1) by heat reduction of a high melt viscosity polyolefin resin at a temperature of 300 to 450°C for a reaction time of 0.5 to 10 hours, or by single or copolymerization of an olefin by a known polymerization method. obtained by letting 2) can be obtained by subjecting the low melt viscosity polyolefin of 1) to an addition reaction with an ethylenically unsaturated polymer in the presence of a peroxide catalyst or in the absence of a catalyst. 3) can be obtained by oxidizing the low melt viscosity polyolefin of 1) with oxygen or oxygen-containing gas (air), or by oxidizing with ozone-containing oxygen or ozone-containing gas (air). The acid value of the oxide is usually 100 or less, preferably 50 or less. 4) is obtained by copolymerization of an ethylenically unsaturated carboxylic acid and/or alkyl ester (having 1 to 18 carbon atoms) and an ethylenically unsaturated hydrocarbon. The amount of ethylenically unsaturated carboxylic acid and/or its alkyl ester is usually 30% or less, preferably 20% or less, based on weight.

In particular, the manufacturing method is not limited to these, but in order to simplify the manufacturing process, the method 1) by heat sterilization is preferred among the above manufacturing methods.

The volume average particle diameter of the mold release agent of the present invention is 10μ or less, preferably 0.5μ or more and 8μ or less. If it exceeds 10μ, dispersion in the toner will be insufficient, and if it is less than 0.5μ, agglomeration between particles will occur and handling will become difficult. The volume average particle diameter can be measured with a Coulter counter.

The method for producing the polyolefin resin of the present invention having a volume average particle diameter of 10 μm or less is not particularly limited, but may be carried out by 1) mechanically pulverizing with a pulverizer or 2) adding a solvent to polyolefin resin powder and heating it. Examples include a method of melting or dissolving with high-speed stirring, rapidly cooling to room temperature, separating and removing the solvent, and drying. For the mechanical pulverization in 1), a jet mill pulverizer, a wet pulverizer, or the like can be used. 2) Method using solvents include ketone solvents such as methyl ethyl ketone and acetone, ether solvents such as dioxane, alcohol solvents such as methanol and ethanol, aromatic solvents such as toluene and xylene, pentane, hebutane, etc. Aliphatic solvents, chlorinated solvents such as chloroform and carbon tetrachloride, distilled water, and mixtures thereof can be used. The weight ratio of the solvent to the polyolefin resin is usually 0.5:1.0 to 20.0:1.0. Heating time is usually 1 to 5 hours. Heating temperature is 50
°C to 250 °C. Depending on the solvent, if necessary, the mixed system may be pressurized to melt or dissolve it.

The melt viscosity of the mold release agent of the present invention at 160°C is 1000
cps or less, preferably 500 cps or less.

If the melt viscosity at 160° C. exceeds 1000 cps, the hot offset temperature will be insufficient when used as an electrophotographic toner. The melt viscosity of the mold release agent at 160° C. can be measured using a Pruckfield rotational viscometer. Conditions other than measurement temperature are JIS-K1557-
It can be carried out according to 1970. An oil bath with a temperature regulator can be used to adjust the temperature of the measurement sample.

The durometer hardness of the mold release agent of the present invention is 30 or more, preferably 40 or more. If the durometer hardness is less than 30, the toner will have insufficient fluidity when used as an electrophotographic toner. Durometer hardness is determined according to ASTM D-2240.

The release agent for electrophotographic toner of the present invention is made of a polyolefin resin, but if necessary, it can contain a binder, a colorant, and various additives to form an electrophotographic toner.

The binder is not particularly limited, but may include thermoplastic resins such as styrene resin, styrene-(meth)acrylic resin, styrene-butadiene resin, polyester resin, and epoxy resin.

Coloring agents include carbon, iron black, and benzidine yellow.
Examples include quinacridine, rhodamine B, and phthalocyanine. As the magnetic powder, powder of a ferromagnetic metal such as iron, cobalt, or nickel, or magnetite, hematite, ferrite, or the like may be used.

Furthermore, various additives include charge control agents (nigrosine,
quaternary ammonium salts, etc.).

As a precept for electrophotographic toner, the release agent of the present invention is usually 0.
．． 5 to 30% by weight, preferably 1 to 5% by weight, binder usually 45 to 95% by weight, preferably 70 to 90% by weight, colorant usually 3 to 50% by weight, etc.

The release agent of the present invention may be added during toner production or may be mixed in advance with the binder. Further, during binder polymerization, it may be added to the system together with other components.

The production of toner for electrophotography is as follows: 1) After dry blending the toner components, the toner components are melt-kneaded, then coarsely pulverized, and finally pulverized using a jet pulverizer, and further classified to produce a fine powder with a particle size of usually 2 to 20 μm. 2) It can also be obtained by suspension polymerizing the monomer of the binder component in the presence of other toner components to obtain a fine powder with a particle size of usually 2 to 20 μm. It is not limited to these.

The toner for electrophotography is mixed with carrier particles such as iron powder, glass beads, nickel powder, ferrite, etc., as required, and used as a developer for an electrical latent image. Furthermore, a hydrophobic colloidal silicate fine powder can also be used to improve the fluidity of the powder.

The toner for electrophotography is heated in a heat fixing heat roll section of a copying machine, such as a heat fixing type copying machine or a printer, and thereby fixed on a support (paper, polyester film, etc.) to form a recording material.

[Examples] The present invention will be further illustrated by the following examples, but the present invention is not limited thereto.

In the examples, all parts represent parts by weight.

Example 1 Low melt viscosity polypropylene 10 with a melt viscosity of 80 cps
00 parts were added to 3,000 parts of toluene, and the mixture was heated under reflux for 1 hour while stirring at 1,000 rpm to dissolve. This was rapidly cooled to room temperature, the precipitated fine particles were filtered, washed with methanol, and the solvent was removed under reduced pressure at 40°C for 10 hours to obtain a volume average particle diameter of 2 μ, a melt viscosity at 160°C of 80 cps, and a durometer hardness of 55. A mold release agent of the present invention was obtained.

Example 2 Low melt viscosity polypropylene 10 with a melt viscosity of 60 cps
00 parts were heated and melted at 150°C, and 10 parts of triethoxyvinylsilane and 10 parts of di-t-butyl peroxide were added dropwise over 4 hours. After keeping at 150℃ for 1 hour,
00 parts and heated for 1 hour while stirring at 1000 rpm. Rapidly cool to room temperature, filter, wash with methanol, and remove solvent at 40°C under reduced pressure for 10 hours to obtain a volume average particle size of 3.5μ.
A mold release agent of the present invention having a melt viscosity at 160° C. of 85 cps and a durometer hardness of 58 was obtained.

Comparative Example 1 Low melt viscosity polypropylene used in Example 1 (volume average particle diameter 50μ, melt viscosity at 160°C 60cp)
s, durometer hardness 53) as a comparative mold release agent.

Reference example 1 660 parts of styrene, 340 parts of butylacrylate solvent,
A binder was obtained by performing thermal polymerization at 130 to 180°C without using a polymerization initiator. The binder had a Tg of 53° C., a number average molecular weight of 11,000, and a weight average molecular weight of 70,000. The molecular weight was measured by GPC method. GPC
The molecular weight measurement of the binder by the method was carried out under the following conditions.

Equipment HLC802A column manufactured by Toyo Soda
TSK gel GMH6 2 bottles Measurement temperature 40'C Sample solution o. swt% THF solution solution injection amount
200 μl Detection device Refractive index detector Reference example 2 Using the mold release agent of Example 1 and the binder of Reference example 1]
An electrophotographic toner was prepared using the following method. Furthermore, an electrophotographic developer was produced.

Toner Preparation Method Binder: 87 parts Release agent of Example 1: 4 parts Carbon black
8 parts (Mitsubishi Kakogyo Co., Ltd. MA-100) Charge control agent 1 part (Hodogaya Chemical Co., Ltd.)
(Spiron Black TRH, manufactured by Co., Ltd.) The above-mentioned mixture was powder-blended, then kneaded in a Labo Plastomill at 130°C and 20 rpm for 20 minutes, and the mixed mixture was pulverized in a jet mill PJMIOO (manufactured by Nippon Pneumatic Co., Ltd.). Fine powder of 2 μm or less was cut from the finely ground material using a powder air classifier MSD (manufactured by Nippon Pneumatic Co., Ltd.).

3 parts of Aerosil R972 (Nippon Aerosil) were uniformly mixed with 1000 parts of the obtained powder to obtain a toner.

Method for Preparing Developer 25 parts of the above toner was mixed with 1000 parts of carrier iron powder for electrophotography (F-100 manufactured by Nippon Tetsuko Co., Ltd.) to obtain a developer for electrophotography.

Reference Example 3 An electrophotographic developer was obtained in the same manner except that the mold release agent of Example 1 was replaced with the mold release agent of Example 2.

Comparative Reference Example 1 An electrophotographic developer was obtained in the same manner except that the mold release agent of Example 1 was replaced with the mold release agent of Comparative Example 1.

The evaluation results of the developer are shown in Table 1.

Table-1 Evaluation of developer Note) ? The fluidity index was measured and evaluated using a dynamic Hosokawa Micron powder tester.

E Fluidity index: 80 or more G Fluidity index: 70 or more and less than 80 P Fluidity index: less than 70 Hot offset resistance Hot offset occurs when the heat roll temperature is 230°C using a commercially available heat-fixing copier. It was visually evaluated whether the

Charging Stability Toner charge amount Q1 when 500 copies were made; toner charge amount Q2 when 110,000 copies were made was measured using a blow-off charge amount meter.

E 11-, Q■/Q21≦0.1 The electrophotographic toner containing the release agent of the present invention not only has excellent toner fluidity and hot offset resistance, but also has excellent charging stability. This was confirmed.

[Effects of the Invention] ゛When the mold release agent of the present invention is used in an electrophotographic toner containing the same, it not only does not reduce the fluidity of the toner, but also has excellent hot offset resistance and further has excellent charging stability. Given its usefulness

Claims (1)

[Claims] 1. A release agent for an electrophotographic toner, which is made of a polyolefin resin having a volume average particle diameter of 10 μm or less, a melt viscosity at 160° C. of 1000 cps or less, and a durometer hardness of 30 or more.