JPS5993455A - Electrostatic charge image developing toner - Google Patents

Abstract

PURPOSE:To enable satisfactory fixation through contact heating fixation by using a toner consisting of the first toner powder using a resin essentially composed of a polymer obtained from a multifunctional monomer as a binder, and the second toner powder. CONSTITUTION:A toner consists of the first toner powder using for a binder a resin composed essentially of a polymer obtained from a multifunctional monomer, such as a polyester resin obtained by condensation of polycarboxylic acid with polyol, or a polyamide resin obtained by condensation of polycarboxylic acid with polyamine; and the second toner powder using for a binder, a resin composed essentially of a polymer other than said polymer. Both toner powders are mixed and used.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a toner for developing electrostatic images formed in electrophotography, electrostatic printing, electrostatic recording, and the like.

In the process of developing an electrostatic charge image, the charged imitation particles are attracted by electrostatic attraction and attached to the surface of the electrostatic charge mound support.
This facilitates the process of visualizing the electrostatic charge image.

The specific method for carrying out such a developing process is as follows:
Wet development method uses a liquid developer in which pigments or dyes are finely dispersed (2) in an insulating concentrated liquid, and a coloring agent such as carbon black is dispersed in a binder made of natural or synthetic resin. There are dry developing methods, such as the cascade method, bristle brush method, magnetic brush method, impression method, and powder cloud method, which use a powder developer made of toner.

The image visualized in the developing step may be fixed on the support as it is, but usually it is transferred to another support such as transfer paper and then fixed. In this way, the toner is not only subjected to the development process, but also to the subsequent processes, that is, the transfer process and the fixing process, so the toner has not only good developability but also the following processes: It is required to have good transfer and fixing properties. Among these, the conditions related to fixing properties are the most severe, and many studies and results have been published in the past on improving the fixing properties of toners.

It is generally advantageous to fix the toner image formed in the developing process or the image to which it is transferred by a heat fixing method, and this heat fixing method includes (3) a non-contact heat fixing method such as oven fixing; , and contact heating fixing methods such as heat roller fixing. The contact heat fixing method is
It is excellent in terms of high thermal efficiency, and is particularly suitable for high-speed fixing in high-speed copying machines. Furthermore, since a relatively low-temperature heat source can be used, this method requires less power consumption, making it possible to downsize the copying machine and save energy. Further, even if paper accumulates in the fixing device, there is no risk of fire, which is also preferable.

Although the contact heat fixing method is preferable in various respects as described above, this method has a problem in that an offset phenomenon occurs. This is a phenomenon in which a portion of the toner constituting the image is transferred to the surface of the heat roller during fixing, and this is transferred again to the transfer paper or the like that is fed next, staining the image. In order to prevent this offset phenomenon, it is effective to provide a cleaning member such as a cleaning roller in contact with the heat roller, and use this cleaning member to clean the toner adhering to the heat roller.

However, when such a leaning member is provided, so-called back side stain development occurs. This back side stain development occurs when the toner material accumulated on the printing member receives excessive heat, and the toner material is transferred to the heated roller, which supports the image on the transfer paper etc. that is subsequently fed. It stains the surface of the body, and also transfers to the pressure roller that is pressed by the heat roller and transfers to this pressure roller 1
- This is a phenomenon in which the back side of the image support is smudged by toner substances.

As a result of investigating the cause of such back-side staining phenomenon, it was found that this back-side staining phenomenon has an important relationship with the elasticity of the toner when it is melted. That is, conventionally, a thermoplastic resin containing a styrene-acrylic copolymer as a main component has been used as a binder resin for toner.
These resins have low elasticity when melted, so they easily transfer, so even if they once adhere to the cleaning member, for example, when the heater of the heat roller is turned on, the toner substance adhering to the cleaning member will be heated. (5) If it is, it will be transferred to the heat roller, resulting in the back surface staining phenomenon.

However, toners that have high elasticity when melted and do not cause backside staining have very poor fixing properties.This is because toners have high elasticity even when softened and melted by a heat roller, causing wetting on image supports such as transfer paper, or This is because the permeability between paper fibers is low.

In order to solve the problem of the back side staining phenomenon as described above, it has been proposed that the binder of the toner contains a thermally crosslinkable resin such as unsaturated polyester.

According to the toner made of such a binder, the thermally crosslinkable resin is crosslinked by the heat from the heated roller on the cleaning member and becomes high in molecular weight over time, and its elasticity increases when melted, so that the toner substance is transferred to the heated roller. As a result, the back surface stain phenomenon is prevented from occurring.

However, toners using only a thermally crosslinkable resin as a binder as described above have a drawback that cleaning properties are low and the surface of an electrostatic image support cannot be sufficiently cleaned by a cleaning member (6).

In addition, in order to obtain good cleaning properties, for example, when using a styrene-acrylic copolymer as a toner binder, we are also considering incorporating a thermally crosslinkable resin as a component of the binder to suppress the phenomenon of backside staining. However, in this case, the compatibility of the thermally crosslinkable resin with the styrene-acrylic copolymer, which can be called the main component resin of the binder, is low, making it impossible to produce a uniformly mixed resin. However, if such a resin is used as a binder, the desired properties will not be exhibited.

The present invention has been made based on the above-mentioned circumstances, and its object is to enable suitable fixing by a contact heating fixing method, without causing backside staining, and to prevent electrostatic charge image formation. It is an object of the present invention to provide a toner for developing electrostatic images that has good cleaning properties on a support and is easy to produce.

The object of the present invention is to provide a first toner powder (7) in which the binder is a resin mainly composed of a polymer obtained from a polyfunctional monomer, and a toner powder as described above, in which the first toner powder is mixed. This is achieved by a toner for developing an electrostatic image, which is characterized in that it is composed of a second toner powder whose binder is a resin whose main component is a polymer other than the polymer.

The present invention will be specifically explained below.

In the present invention, a toner for developing an electrostatic image is composed of a first toner powder and a second toner powder, and the binder of the first toner powder is made by polymerizing a polyfunctional monomer. (hereinafter referred to as "crosslinkable polymer") or a resin obtained by blending this crosslinkable polymer with an appropriate resin, and the second toner powder is A blast of a polymer other than a crosslinkable polymer, such as a styrene-acrylic copolymer resin, satisfies the general properties required for toners, including the cleanability of electrostatic image supports. .

In the above, it is preferable that the first toner powder and the second toner powder have the same triboelectric charging characteristics. Differences in triboelectric properties due to differences in binder components are
For example, the type or amount of the additive resin or copolymer component in the binder resin of each toner powder, the type or amount of other toner components, especially the charge control agent, contained in the toner powder, the average particle size, etc., and the frictional electrification of the toner. By appropriately selecting factors that influence the characteristics, it is possible to make them small.

The mixing ratio of the first toner powder and the second toner powder is not particularly limited, but is preferably 10:90 by weight.
~90: 10. Preferably 30 near 0 to 70:30
It is.

Since the toner of the present invention is as described above, the uniformly mixed toner of the first toner powder composed of a binder mainly composed of a crosslinkable polymer and the second toner powder has an electrostatic charge. The electrostatic charge image is developed by being supplied to the image support, and the thus formed toner image is transferred to the image support such as transfer paper and sent to a hot roller fixing device. The toner remaining on the toner is cleaned (9), but since the second toner powder with excellent cleaning properties is present in this toner, the poor cleaning properties of the first toner powder are compensated for and the overall cleaning performance is improved. As a result, good leaning can be achieved. In addition, in the heat roller fixing device, the toner forming the toner image melts when it comes into contact with the heat roller, but the elasticity of the molten toner at this time is small, so the wetting to the image support is good and there is sufficient space between the fibers. penetration and as a result good fixation is achieved.

Then, some of the toner sticks to the roller and is further cleaned and deposited on the cleaning roller.The toner substance becomes more elastic over time on the cleaning roller, so it is heated to a temperature higher than the fusing temperature by the heat roller. Even if the heat roller is heated, there is no transfer to the pressure roller via the heat roller, and the occurrence of back surface staining can therefore be prevented.

This is because the toner contains a first toner powder,
This is because the binder contains a crosslinkable resin as a main component, and the functional moiety of the polyfunctional monomer still remains in a considerable proportion in the crosslinkable resin (10). This is because the remaining functional parts of the crosslinkable resin are bonded over time by the heat from the heat roller, and the whole becomes a three-dimensional crosslinked structure.

Note that the elasticity of the toner immediately after melting is 1000 to 20.
000 dyne/m2 or more will ensure good fixing, and if the elasticity of the molten toner material on the cleaning roller is 24,000 dyne/m2 or more, the backside staining phenomenon can be reliably prevented.

Further, since the first toner powder and the second toner powder constituting the toner of the present invention can be manufactured by applying the usual toner manufacturing method as is, there is no particular problem in manufacturing them, and both toner powders Since mere mechanical mixing is sufficient, differences in the properties of these binders do not pose a problem, and after all, they can be manufactured easily and at low cost.

The crosslinkable resin which is the main component of the binder of the first toner powder is a polyfunctional monomer (11), such as a polymer obtained by condensation of a polyhydric carboxylic acid and a polyhydric alcohol. Polyester resins, polyamide resins obtained by condensation of polyvalent carboxylic acids and polyvalent amines, etc. can be preferably used, and in particular, trifunctional or higher polyfunctional monomer components are used as the entire monomer components involved in the condensation. It is desirable that the content is at least 15 to 40 mol. When a polyester resin is used as a binder, it is preferably a polyester having an acid value of 27 or more, preferably 30 or more, and most preferably 37 or more.

Specific examples of dicarboxylic acids that can be suitably used to obtain polyester resins or polyamide resins include maleic acid, hexamaric acid, mesaconic acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, and terephthalic acid. acid, cyclohexanedicarboxylic acid,
Examples include succinic acid, adipic acid, sepatic acid, malonic acid, anhydrides of these acids, dimers of lower alkyl esters and luic acid, and others.

Specific examples of trivalent or higher polycarboxylic acids that can be suitably used include 1,2.4-benzenetricarboxylic acid, 1,2.4-cyclohexanetricarboxylic acid, and 2,5.7-naphthalenetricarboxylic acid. Acid, 1,2.
4-naphthalene tricarboxylic acid, 1,2,4-butanetricarbo/acid, 1,2,5-hexane) IJ carboxylic acid, 1,3-dicarboxyl-2-methyl-2-methylenecarboxylpropane, tetra( (methylenecarboxyl)methane, 1.2,7.8-octanetetracarboxylic acid, embol trimer acid, acid anhydrides thereof, and others.

Specific examples of polyhydric alcohols that yield polyester resins through condensation 1 with the above polyhydric carboxylic acids include evapoethylene glycol, diethylene glycol, triethylene glycol, 1.2-7'ropylene glycol, 1.3-7
Diols such as robylene glycol, 1゜4-butanediol, neopentyl glycol, 1,4-butynediol, 1,4(13) monobis(hydroxymethyl)cyclohexane, and bisphenol A1 hydrogenated bisphenol A1 poly Etherified bisphenols such as oxyethylenated bisphenol A1, polyoxypropylenated bisphenol A, and others can be mentioned.

Further, specific examples of polyhydric alcohols having a valence of 3 or more which can be suitably used include sorbyl, 1,2,
3.6-hexanetetrol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, sucrose, 1,2.4-butanetriol, 1,2.5-pentanetriol, glycerol, 2-methyl Propanetriol, 2-methyl-1,2
, 4-butanetriol, trimethylolethane, trimethylolpropane, 1,3.5-trihydroxymethylbenzene, and others.

Further, specific examples of polyvalent amines that are condensed with the above polyvalent carboxylic acid to give polyamide resin include ethylenediamine,
Examples include hexamethylenediamine, imino(14)bispropylamine, phenylenediamine, xylylenediamine, 4,4-diaminophenyl ether, diethylenetriamine, triethylenetetramine, and others.

As the binder for the second toner powder, one should be selected from resins such as polymers and copolymers, or mixtures thereof, which are usually used for this purpose, so that the toner produced by the binder has good cleaning properties. However, styrene resins or styrene-acrylic copolymers are particularly preferred in various respects.

Styrenes for obtaining styrene resins or styrene-acrylic copolymers include, for example, styrene, O-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-ethylstyrene, 2,4
-dimethylstyrene, p-n-butylstyrene, p-
tert-butylstyrene, p"-hexylstyrene, p-n-octylstyrene, p"-nonylstyrene, p-H-7"silstyrene, p-n-dodecylstyrene, (15) p-methoxystyrene, p- Examples include phenylstyrene, p-chlorostyrene, and 3,4-dichlorostyrene.

Examples of acrylic monomers for obtaining the styrene/acrylic copolymer include methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, propyl acrylate, acrylic flln-octyl,
Dodecyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, phenyl acrylate, methyl α-chloroacrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, lauryl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate, dimethyl methacrylate α-methylene aliphatic monocarboxylic acid esters such as amine ethyl and diethylaminoethyl methacrylate; acrylic acid or methacrylic acid derivatives such as acrylonitrile, methacrylonitrile, acrylamide, and others. These monomers can be used alone or in combination. In particular, a terpolymer consisting of the three components styrene-methyl methacrylate-butyl methacrylate is preferred.

When the first toner powder and the second toner powder contain a colorant in the binder particles described above, and further contain a property improver added as necessary, to form a magnetic toner. A magnetic substance is contained together with the colorant or in place of the colorant.

As a coloring agent, carbon black, nigrosine dye (
C,1, 50415B), Aniline Blue (C,1
, A30405), Calco Oil Blue (C, I.

A azoec Blue 3), Chrome Yeo-(C
, 1, A14090), ultramarine blue (C,
1, A77103), DuPont Oil Red (C, 1
,A26105), quinoline yellow (C,1,A(
17) 47005), methylene blue chloride (C,I.

A32015), phthalocyanine blue (C, 1, 7
4160), malachite green offsalate (C,
1, A42000), lamp black (C, I.

A77266), Rose Bengal (C, 1, A4543
5), mixtures thereof, and others. These colorants need to be contained in a sufficient proportion to form a visible image with sufficient concentration, and usually range from 1 to 20 parts by weight per 100 parts by weight of the binder. be done.

The magnetic material may be a metal or alloy that exhibits ferromagnetism such as ferrite, magnetite, iron, cobalt, or nickel, or a compound containing these elements, or a material that does not contain a ferromagnetic element but can be made by subjecting it to appropriate heat treatment. Mention may be made of alloys which become ferromagnetic, such as alloys of the type called Heusler alloys containing manganese and copper, such as manganese-copper-aluminum, manganese-copper-tin, or chromium dioxide, among others. These magnetic materials are uniformly dispersed in the binder in the form of fine powder (18) with an average particle size of 0.1 to 1 micron. And its content is 100% toner! The amount is 920 to 70 parts by weight, preferably 40 to 70 parts by weight.

Further, as the characteristic improving agent, nigrosine dye, amines, ammonium salts, pyridinium salts, and other charge control agents can be mainly mentioned.

The toner of the present invention may be mixed with a carrier made of iron, ferrite, magnetite, glass beads, etc. to form a developer, or when each toner powder contains a magnetic substance, it may be used as a developer as it is. When mixed with a carrier, the carrier is preferably one made of iron powder coated with a resin from various points of view.

Examples of the present invention will be described below, but the present invention is not limited to these.

"Part" indicates the heavy part.

Example 1 Terephthalic acid, trimellitic acid, and polyoxypropylene (2,2)-2,2-bis(4-hy(19) droxyphenyl)propane! : were polycondensed in a molar ratio of 2:3:6 to obtain a crosslinkable unsaturated polyester resin. 100 parts of this crosslinkable unsaturated polyester, 10 parts of carbon black, and 1 part of "Oil Black rsO" (manufactured by Orient Chemical Co., Ltd.) were mixed, kneaded using two rolls at a temperature of 110 to 120°C for 25 minutes, and then mixed using a conventional method. Cooling, pulverization, and classification were performed according to the procedure to obtain a positively chargeable first toner powder having an average particle size of 10P. this"
``Toner powder person''.

On the other hand, copolymer 100 obtained by copolymerizing styrene and butyl acrylate at a ratio of 8:2 by weight
part, 10 parts of carbon black, and oil black rs
Mix parts o, o and s and roll them into two rolls at a temperature of 110.
Knead at ~120°C for 25 minutes, cool and crush according to conventional methods.
Classification was performed to obtain a positively chargeable second toner powder having an average particle size of 10 μm, and this was designated as “toner powder B”.

The toner powder A and the toner powder B are mixed in various ratios to obtain a total of 8 types of toner, and each of the toners is mixed with a carrier made of iron powder having an average particle size of 120P coated with a Teflon resin at different toner concentrations. A total of 8 kinds of developers were prepared by mixing them so that the amount of the developer was 2.0% by weight. The electrophotographic copying machine "U-Bix
Using a modified machine of 5J (manufactured by Konishiroku Photo Industry Co., Ltd.), a copy test was carried out for 5,000 times with each of the above-mentioned developers, and the number of copies a until the back side stain phenomenon occurred and the image quality of the obtained copied images were evaluated. We conducted an evaluation. The results are shown in Table 1. Regarding the number of copies a, "none" indicates that no back surface staining phenomenon occurred during the 5000 copy tests.

(21) Table 1 According to the results shown in Table 1, a developer using a toner mixed with toner powder A and toner powder B can clean the photoreceptor well and produce copied images of excellent image quality, and it is also possible to avoid stains on the back surface. It is clear that the occurrence of the phenomenon is prevented.

Example 2 45 parts of the crosslinkable unsaturated polyester resin used in Example 1, 55 parts of magnetite, and 1 part of Oy (22) Rubrac "80 J" were thoroughly mixed and heated to 140 to 150°C using two rolls. Mixed for 20 minutes at
A first toner powder was obtained. This is referred to as "toner powder C".

On the other hand, 45 parts of the same styrene-butyl acrylate copolymer as in Example 1, 55 parts of magnetite, and 1 part of oil black "SO" were thoroughly mixed, and the mixture was rolled using two rolls at a temperature of 140 to 150°C. The mixture was kneaded for 20 minutes, cooled, pulverized, and classified according to a conventional method to obtain a second toner powder having an average particle size of 11 tones.

This is referred to as "toner powder D".

A total of eight types of one-component developers were prepared by mixing toner powder C and toner powder in various proportions. and an electrophotographic copying machine rU, which is equipped with a fixing roller consisting of a steel drum provided with a rubber coating layer, an organic photoreceptor as a photoreceptor, and a developing device for one-component developer.
Using a modified machine of Bixvz J (manufactured by Konishiroku Photo Industry Co., Ltd.), tests similar to those in Example 1 were carried out (23) on each of the above-mentioned developers. The results are shown in Table 2.

The results shown in Table 2 and above also show that the toner prepared by mixing a toner powder containing a polyfunctional monomer and a polymer obtained as the main binder has sufficient cleaning of the photoreceptor and excellent image quality. It is clear that a copy image of 100% can be obtained and that the occurrence of the back side stain phenomenon is prevented.

397-

Claims (1)

[Claims] 1) A first toner powder whose binder is a resin mainly composed of polymer gold obtained from a polyfunctional monomer;
A toner for static image development, characterized in that the toner powder is mixed with a second toner powder whose binder is a tree JJf whose main component is a polymer other than the above-mentioned polymer.