JPH0363659A - Electrophotographic releasing agent - Google Patents

Abstract

PURPOSE:To enhance hot offset resistance of a toner and to reduce tendency to print separating claw marks and attachment of the toner to a carrier by adding a specified polypropylene type resin as a releasing agent. CONSTITUTION:The polypropylene type resin to be used for the releasing agent is a low melt-viscosity type polypropylene having a melt viscosity of <= 60 cps at 160 deg.C, an isotactic content of 75 - 90 %, and a propylene content of >=75 %. This resin can be obtained by heat degrading a high molecular weight polypropylene type resin (A) having the said range of isotactic content, and the maleic acid derivative adduct to the heat-degradation product or the oxide of the heat degradation product can also be used, and a copolymer of propylene and other olefin can be used for the resin (A).

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a mold release agent for electrophotography. More specifically, the present invention relates to an electrophotographic release agent suitable for use in heat-fixing type copying machines or printers, which has excellent hot offset resistance and release properties.

[Prior Art] A heat 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, a method of adding low molecular weight polypropylene to an electrophotographic toner has been proposed (Japanese Patent Publication No. 3304/1983).

[Problems to be Solved by the Invention] However, with this method, not only is it not possible to obtain a sufficient hot offset temperature, but also the mold releasability from the heat roll is reduced, scratch marks are generated by the separating claws, and furthermore, there are problems such as filming on the carrier. A problem arises.

[Means for Solving the Problems] The present inventor has made efforts to develop a mold release agent for electrophotography that can obtain a sufficient hot offset temperature, has excellent mold releasability from a heat roll, and does not cause filming on the carrier. As a result of study, we have arrived at the present invention. That is, the present invention
It is characterized by being made of a low melt viscosity polypropylene resin having a melt viscosity at 160°C of 80 cps or less, an isotactic content of 75% to 90% (75% or more and less than 90%), and a propylene content of 75% or more. This is a mold release agent for electrophotography.

The low melt viscosity polypropylene resin according to the present invention can be obtained by thermally degrading a high molecular weight polypropylene resin having an isotactic content of 75% or more and less than 90%, although the manufacturing method is not particularly limited. be able to. The present invention also includes adducts of maleic acid derivatives (maleic anhydride, maleic acid dimethyl ester, maleic acid diethyl ester, maleic acid di-2-ethylhexyl ester, etc.) of thermal degradation products of high molecular weight polypropylene resins, and high molecular weight polypropylene resins. Oxides of thermally degraded products of resins can also be used.

When producing a high molecular weight polypropylene resin by thermal degradation, the high molecular weight polypropylene resin used as a raw material has a melt index of usually 0.1 to 100, preferably 1 to 50. Furthermore, as the composition of the high molecular weight polypropylene resin used as a raw material, a copolymer of propylene and other olefins can also be used.

Other olefins include ethylene, butene, octene, and the like. The content of propylene is usually 75% by weight or more, preferably 90% by weight or more. If the amount is less than 75% by weight, the releasability will be insufficient when used as an electrophotographic toner, and claw marks will be likely to occur. For thermal degradation, high molecular weight polypropylene resin is heated to 0.5 to 1.
This can be done by passing it through for 0 hours. The melt viscosity of the thermally degraded product can be adjusted by the thermally degraded temperature and thermally degraded time. If it is less than 300°C, it takes time to lower the melt viscosity, and if it exceeds 450'C, the melt viscosity lowers in a short time and becomes difficult to control.

The isotactic content of the low melt viscosity polypropylene resin according to the present invention is 75% or more and less than 90%, preferably 80 to 87%. Isotactic content is 75
If the amount is less than %, the fluidity of the toner decreases when used as an electrophotographic toner, and the toner may not be able to be supplied to a developing machine.

The isotactic content of the low melt viscosity polypropylene resin according to the present invention is 998 cm'' measured by an infrared spectrophotometer.
” absorbance (Dssa) and 974 cm-
Absorbance CD at ", □4) From the following formula % formula % Isotactic content (%) "Dss, / D974 X100 160 of the low melt viscosity polypropylene resin according to the present invention
Melt viscosity at °C is 60 cps or less, preferably 45
cps or less. Melt viscosity at 160℃ is 60c
If the temperature exceeds ps, a sufficient hot offset temperature may not be obtained when used in an electrophotographic toner. The melt viscosity of the low melt viscosity polypropylene resin at 160° C. is measured using a Brookfield rotational viscometer.

Conditions other than the measurement temperature are in accordance with JIS-1557-1970. An oil bath with a temperature regulator is used to adjust the temperature of the measurement sample.

The electrophotographic mold release agent of the present invention is made of a low melt viscosity polypropylene resin, and if necessary, a binder,
A toner for electrophotography can be prepared by containing a colorant and various additives.

Examples of the binder include styrene resins, such as copolymers of styrene monomers, (meth)acrylic acid ester monomers, and other monomers. Examples of styrenic monomers include styrene,
Examples include alkylstyrenes (eg, α-methylstyrene, P-methylstyrene), and the like. Among these, styrene is preferred. Examples of (meth)acrylic acid ester monomers include alkyl (meth)acrylates (acrylic having 1 to 18 carbon atoms, methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, etc.), hydroxyl group-containing (meth)acrylate (hydroxylethyl (meth)acrylate, etc.), amino group-containing (meth)acrylate (dimethylaminoethyl (meth)acrylate, etc.) Acryte, diethylaminoethyl (meth)
acrylate, etc.), and mixtures of two or more thereof. Among these, preferred are alkyl (meth)acrylates.

Other monomers (vinyl esters (vinyl acetate, etc.), vinyl ethers, (vinylethyl ether, etc.), aliphatic hydrocarbon vinyls (α-olefin, butadiene, etc.), nitrile group-containing vinyl compounds ((meth)acrylonitrile, etc.)
, N-vinyl compounds (N-vinylpyrrolidone, etc.), unsaturated carboxylic acids or their anhydrides ((meth)acrylic acid, maleic anhydride, itaconic anhydride, etc.) can also be used with styrene monomers or styrene monomers. It may also be a copolymer with a mixture of (meth)acrylic acid ester monomers. The amount of other monomers is usually 2
It is 0% by weight or less, preferably 10% by weight or less.

Copolymers can usually be produced by solution polymerization, suspension polymerization, or bulk polymerization. A polymerization initiator may be used during polymerization. Polymerization initiators include azo-based initiators (azobisisobutyronitrile, azobisisovaleronitrile, etc.), polyamide-based initiators (benzoyl peroxide, lauroyl peroxide, di-t-butyl peroxide, t-
Butylcumyl peroxide, dicumyl peroxide, t-butylperoxybenzoate 1,1-bis(t
-butylperoxy) 3,3.5-trimethylcyclohexane, etc.). The polymerization reaction is usually carried out in an atmosphere of an inert gas such as nitrogen. Polymerization temperature is usually 50
-220°C, preferably 70-200°C.

The reaction time depends on other conditions, but is usually 1 to 50 hours, preferably 2 to 10 hours. When the reaction time is shorter than 1 hour, it is difficult to control the reaction, and when it exceeds 50 hours, it is economically disadvantageous. If a solvent is used during polymerization, remove the solvent from the reaction.

Colorants include carbon, iron black, benzidine yellow,
Examples include quinacudrine, 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 such as glosine and quaternary ammonium salts.

As a component of the electrophotographic toner, a low melt viscosity polypropylene resin is usually used in an amount of 0.5 to 30% by weight, preferably 1 to 30% by weight.
5% by weight, binder usually 45-95% by weight, preferably 70-90% by weight, coloring material usually 3-50% by weight
etc. on a monthly basis.

The low melt viscosity polypropylene resin may be added at the time of 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 obtain particles with a particle size of usually 2 to 20μ. It can also be obtained by obtaining a fine powder or 2) 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.

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

The electrophotographic toner is heated in a heat fixing heat roll section of a copying machine, such as a heat fixing type copying machine or a printer, so that it can be applied to a support (paper, polyester film, etc.).
and is used as a recording material.

[Examples] The present invention will be further explained below with reference to Examples, but the present invention is not limited thereto.

In the examples, all parts represent parts by weight.

Example 1 A high molecular weight polypropylene resin with an isotactic content of 85% and a propylene content of 97% by weight was continuously passed through a tube equipped with a static mixer while
Contains isotactic material that does not undergo heat degradation for 10,000 minutes at 65℃! A mold release agent made of a low melt viscosity polypropylene resin having a melt viscosity of 88% and a melt viscosity of 35 cps at 160° C. was obtained.

Comparative Example 1 While continuously passing a high molecular weight polypropylene resin with an isotactic content of 88% and a propylene content of 97% by weight through a tube incorporating a static mixer,
Heat degraded at 55°C for 60 minutes to an isotactic content of 85
% and a melt viscosity at 160° C. of 280 cps was obtained.

Comparative Example 2 A high molecular weight polypropylene with an isotactic content of 70% and a propylene content of 70% by weight was reduced under the heat reduction conditions of Example 1 to produce a polypropylene with an isotactic content of 61% and a melt viscosity of 30 cps at 160°C. A mold release agent made of a resin based resin was obtained.

Reference Example 1 A binder was obtained by thermally polymerizing 660 parts of styrene and 340 parts of butyl acrylate at 130 to 180°C without using a solvent or 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. Molecular weight was determined by GPC method. Molecular weight measurement of styrenic resin by GPC method was performed under the following conditions.

Equipment: Toyo Soda HLC802A column:
TSK gel GMH62 pieces Measurement temperature: 25°C Sample solution: 0.5 wt% THF solution Injection amount: 200 μm 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 produced by 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 (mMA-100, manufactured by Mitsubishi Chemical Industries, Ltd.) Charge control agent: 1 part (Spiron Black TRH, manufactured by Hodogaya Chemical Industries, Ltd.) The above-mentioned mixture was powder-blended and then kneaded for 10 minutes at 140° C. and 30 rpm using a Labo Plastomill, and the mixed material was pulverized using a jet mill PJM100 (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.).

A toner was obtained by uniformly mixing 3 parts of Aerosil R972 (Nippon Aerosil) with 1000 parts of the obtained powder.

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

Reference Examples 3 and 4 Developers were obtained in the same manner except that the release agents of Example 1 were replaced with the release agents of Comparative Examples 1 and 2.

Table 1 shows the evaluation results for each developer.

Table-1 Developer evaluation results Hot offset resistant Using a commercially available heat-fixing copier, Heat that causes hot offset Evaluation was made based on the temperature of the roll.

8220°C or more 0 200°C or more and less than 220°C P
Claw marks below 200° C. Using a commercially available heat-fixing type copying machine, the presence or absence of claw marks from separation claws at a heat roll temperature of 160° C. was visually evaluated.

Filming onto the carrier After mixing the developer at 1100 rpm for 3 hours using a Turbulence shaker mixer, the amount of toner adhering to the surface of the carrier was observed using a microscope.

The electrophotographic toner containing the low melt viscosity polypropylene resin of the present invention as a release agent not only has excellent hot offset resistance, but also is resistant to the generation of fingernail marks, and also has excellent toner adhesion to the carrier (filming to the carrier). It was confirmed that there were few

[Effect of the invention]

Claims (1)

[Claims] 1. A mold release agent for electrophotography characterized by being made of a low melt viscosity polypropylene resin having a melt viscosity at 160° C. of 60 cps or less, an isotactic content of 75% to 90%, and a propylene content of 75% or more. .