JPH06301232A - Electrostatic photographic toner - Google Patents

Abstract

PURPOSE:To provide an electrostatic photographic toner capable of improving image quality owing to reduced white surface fog, etc., and improving copying performance such as fixability-peelability or scattering resistance by improving the dispersibility of a resin component used in a toner. CONSTITUTION:A toner based on a bonding resin, a colorant, an electrostaticcharge controlling agent and a releasing material is blended with an ethylene-propylene rubber/ethylene hexene/ethylene vinyl acetate mixture as a chemical agent for making the releasing material compatible with the bonding resin to obtain the objective electrostatic photographic toner. The chemical agent is added to at least part of the bonding resin and the releasing material and the resulting master batch is used. The amt. of the chemical agent used is regulated to 2-10wt.% of the total amt. of the agent and the resin.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toner for electrostatic photography, and more specifically, it improves the dispersibility of a release material in a binder resin and the fixing and image quality of the toner. The present invention relates to an electrophotographic toner used in general machines, laser printers, plain paper facsimiles and the like.

[0002]

2. Description of the Related Art Conventionally, as a two-component developer, a toner which is a powder for visualizing an electrostatic latent image on a photoconductor and an electric charge to the toner by frictional charging, and the toner is conveyed to a developing area. There are known two-component developers for carriers. Of these developers, the toner is generally 80 to 95% of a binder resin, 5 to 1
About 5% of a colorant, about 1 to 5% of a charge control agent, and if necessary, about 5% or less of a release agent and an external additive are mixed. In this case, the binder resin is generally polystyrene, styrene-acrylic copolymer,
Polyester, epoxy, polyamide, polymethylmethacrylate, polyvinyl butyral, etc. are used. Among these, styrene-acrylic copolymer resin, polyester resin, polystyrene resin, etc. are typical.

As the colorant, carbon black such as furnace black and channel black is used for black toner. The charge control agent differs depending on whether it is for a positively charged toner or a negatively charged toner, and the former is an electron donating substance such as a nigrosine dye, a fatty acid metal salt or a quaternary ammonium salt, and the latter. As azo metal-containing dyes, chlorinated paraffin,
An electron accepting substance such as chlorinated polyester is used. Further, as the release material (release agent), low molecular weight polypropylene (polypropylene wax), low molecular weight polyethylene (polyethylene wax), etc. are used for offset prevention.

In the production of a dry toner, the above raw materials are weighed in appropriate amounts and mixed in a dry manner by a known mixing means such as a Henschel mixer, and then a known melt-kneading means such as a screw type extruder or a kneader. Thus, the raw materials are uniformly dispersed, followed by cooling, pulverizing and classifying to obtain a toner having a particle size of about 5 to 20 μm. If necessary, fine powder such as colloidal silica, titanium oxide, alumina, or fatty acid metal salt is added to the toner surface as an external additive for the purpose of improving toner fluidity, adjusting triboelectric charging property, or improving cleaning property. It may be deposited, which results in the final toner product.

The above is an example of a very general manufacturing method introduced in texts and the like. In addition to the above, in addition to the above-mentioned raw materials for the purpose of improving the offset resistance at the time of fixing,
A technique for adding at least one thermoplastic rubber-like substance consisting of an alkylene-vinyl acetate copolymer, a partial hydrolyzate thereof, and a copolymer of alkylene and α-olefin is disclosed in JP-A-54-140538. It is proposed by the publication. By the way, when it comes to copying performance,
In order to obtain good copy image quality, fixability, etc., it is essential to disperse the toner raw material uniformly, especially the dispersibility of a releasing material of a resin different from the binder resin in the binder resin.

[0006]

Therefore, in order to impart the resin dispersibility for satisfying the above-mentioned objects, the manufacturing conditions for melt-kneading are studied from the viewpoints of the types of raw materials and the adoption of a continuous kneader. However, sufficient results have not been obtained. Further, with respect to the additives as disclosed in the above-mentioned JP-A-54-140538, the effect on the toner was examined by using these additives alone or in combination, but a slight improvement in fixing property or the like was observed. However, it is not sufficient, and problems such as white background fog and toner scattering remain. Therefore, the object of the present invention is to improve the dispersibility of the resin component used in the toner, thereby improving the image quality such as reducing the fog on a white background, improving the fixing and peeling property, or improving the toner scattering resistance. An object of the present invention is to provide an electrophotographic toner that can be improved.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and the gist thereof is to include a binder resin, a colorant, a charge control agent, and a releasing material as main components. The toner for electrostatic photography contains a mixture of ethylene / propylene rubber / ethylene hexene / ethylene vinyl acetate as a compatibilizing agent for a releasing material with respect to a binder resin. In this case, at least one of the binder resins is used. Part, and a resin component composed of a releasing material, and these compatibilizers, those that are pre-formulated as a masterbatch, the amount of the compatibilizer, the total amount with the resin component A medium content of 2 to 10% by weight is effective in both cases.

[0008]

In the present invention, a mixture of ethylene / propylene rubber / ethylene hexene / ethylene vinyl acetate is used as a compatibilizing agent for the releasing material with respect to the binder resin together with each toner raw material or in advance as a master batch with a resin component. As a result, the dispersion of the releasing material in the resin component in the obtained toner becomes extremely good, and the result of the actual copying test shows that the white background fog, toner scattering, etc. are reduced, or the peeling property of the paper from the fixing roller, that is, The improvement in fixing peelability becomes remarkable. In particular, when the compatibilizer is added together with the resin component by the masterbatch method, the dispersibility is further improved, and even if a small amount of the releasing material and the compatibilizer are used, a good evaluation similar to the use of a large amount can be obtained. It becomes possible to obtain.

[0009]

EXAMPLES The present invention will be described in detail below based on examples. First of all, the main essence of the present invention is that the resin component mainly composed of the binder resin and the releasing material in the toner is ethylene / propylene rubber / ethylene hexene as a compatibilizing agent for the both. / Ethylene vinyl acetate ternary mixture is used. The reason why the mixture of these three components exerts the effect is not clear, but according to the experiments by the present inventors, the above-mentioned combination is the best, and the reason is probably ethylene propylene rubber and ethylene hexene, respectively. ,
It is expected that this is due to the fact that it has an unsaturated bond and that ethylene vinyl acetate has a strong polarity.

As a means for blending the above-mentioned three components into the toner raw material as a compatibilizing agent, it is possible to dry-blend these three components in advance with a Henschel mixer or the like and then blend these into the toner raw material as a compatibilizing agent. By omitting such a preliminary dry mixing step and directly blending the three components of the compatibilizer into the toner raw materials and simultaneously adding the binder resin, the colorant, and the like at the same time, the effect is not obtained. There is no change. The mixing ratio of these three components, ethylene / propylene rubber / ethylene hexene / ethylene vinyl acetate, may be appropriately selected depending on the purpose and application, that is, the combination of the binder resin and the releasing material. A ratio can be adopted.

Next, the means for producing the toner of the present invention will be described.
For example, according to the conventional means as described above, the compatibilizing agent is added to a toner raw material having a predetermined composition, and the compatibilizing agent is mixed by a mixing means such as a Henschel mixer, and then a series of known methods such as melt kneading / cooling / grinding / classification It is also possible to prepare a toner by the step of, or at least a part of the binder resin, the releasing agent and the compatibilizer are preliminarily subjected to the steps of mixing / melt kneading / cooling / milling to make each resin highly concentrated. After preparing a uniformly dispersed masterbatch, the masterbatch is blended with the remainder of the binder resin, as well as other toner raw materials such as colorants, charge control agents, etc., to give a predetermined toner formulation. It is also possible to carry out classification as described above in the step (1) to adjust the particle size to obtain a toner. In any case, the surface treatment can be performed by adding an external additive, if necessary.

In this case, the compatibilizer may be used in a relatively small amount, and it is suitable that it is in the range of 2 to 10% by weight in the total amount of the binder resin and the releasing material. Is. However, if it is less than 2% by weight, the original effect of the compatibilizing agent, that is, the uniform dispersion of the resin, cannot be sufficiently exhibited. On the other hand, when the amount of the compatibilizer added is more than 10% by weight, the characteristics peculiar to these substances are strongly exhibited, and the performance of the toner as a whole may be adversely affected. It should be noted that as the binder resin or the release material (release agent) used as the toner raw material, the above-mentioned conventionally used materials may be appropriately selected and used.
As the binder resin, styrene-acrylic copolymer resin,
Polyester resin, polystyrene resin, etc. are suitable, and polypropylene wax, polyethylene wax, etc. are suitable as the release agent.

The effects of the present invention will be described in more detail below based on the experimental results. Table 1 shows the toner composition used in the experiment, and Table 2 shows the evaluation after continuous copying of 10,000 sheets. In Tables 1 and 2, Examples 1 to 5 satisfy the range of the present invention, and Comparative Examples 1 to 6 show those outside the above range for confirming the effect of the present invention. Further, Examples 1 to 3 in Table 1 are examples in which the weight mixing ratio A or B of the two levels of the compatibilizing agent shown in Table 3 is directly blended with the toner raw material, and Examples 4 to 5 are Table 3 2 shows an example in which the masterbatch having the two levels of the weight composition ratios a and b shown in Table 4 is blended with the toner raw materials by using the compatibilizing agent A of 1.

On the other hand, Comparative Examples 1 to 3 in Table 1 are examples in which the compatibilizing agent is not used, and Comparative Examples 4 to 6 use the compatibilizing agent, but the three components as found in the present invention. Examples are shown respectively in which the use of mixed compatibilizers is not carried out. In Table 2, the evaluation method after continuous copying of 10,000 sheets is as follows. (A) Toner scattering: The state of toner scattering in the copying machine after continuous copying of 10,000 sheets was visually confirmed. (B) White background fog: Color difference meter (Σ9 from Nippon Denshoku Industries Co., Ltd.)
0) was used as the difference between the values of the white background before and after copying on the copy paper. The smaller the value, the smaller the fog and the better. (C) Fixing / releasing property: The degree of dirt of the fixing roller after continuous copying of 10,000 sheets is visually confirmed. However, ◯: good, Δ: roller is dirty, ×: roller is heavily soiled.

Examples and comparative examples shown in Tables 1 and 2 will be described below. Example 1 100 parts by weight of styrene-acrylic resin, 7 parts by weight of carbon black, 3 parts by weight of quaternary ammonium salt, 3 parts by weight of polypropylene wax, 5 parts by weight of a mixture of ethylene / propylene rubber / ethylene hexene / ethylene vinyl acetate (Sample A). After mixing the parts with a Henschel mixer, melt kneading, cooling, pulverization and classification were carried out to prepare a toner having an average particle size of 10 μm. 100 parts by weight of this toner and 0.
3 parts by weight were mixed to obtain the final toner. Further, 4 parts by weight of the final toner and 100 parts by weight of the ferrite carrier were mixed to prepare a developer. When continuous copying was performed on 10,000 sheets using the above-mentioned developer and final toner, toner scattering, white background fog, peelability from the fixing roller and the like were improved.

Example 2 100 parts by weight of styrene-acrylic resin, 7 parts by weight of carbon black, 3 parts by weight of quaternary ammonium salt, 2 parts by weight of polyethylene wax, a mixture of ethylene / propylene rubber / ethylene hexene / ethylene vinyl acetate (Sample A) ) After mixing 5 parts by weight with a Henschel mixer, melt kneading, cooling, pulverization and classification were carried out to prepare a toner having an average particle size of 10 μm. 100 parts by weight of this toner and 0.
3 parts by weight were mixed to obtain the final toner. Further, 4 parts by weight of the final toner and 100 parts by weight of the ferrite carrier were mixed to prepare a developer. When continuous copying was performed on 10,000 sheets using the above-mentioned developer and final toner, toner scattering, white background fog, peelability from the fixing roller and the like were improved.

Example 3 100 parts by weight of polyester resin, 7 parts by weight of carbon black, 3 parts by weight of quaternary ammonium salt, 3 parts by weight of polypropylene wax, a mixture of ethylene / propylene rubber / ethylene hexene / ethylene vinyl acetate (Sample B).
After mixing 4 parts by weight with a Henschel mixer, melt kneading, cooling, pulverization and classification were carried out to prepare a toner having an average particle size of 10 μm. 100 parts by weight of this toner and 0.3 parts by weight of hydrophobic silica were mixed to obtain a final toner. Further, 4 parts by weight of the final toner and 100 parts by weight of the ferrite carrier are mixed,
Used as a developer. 1 using the above developer and final toner
After continuous copying of 20,000 sheets, toner scattering,
Fog on white background, peelability from the fixing roller, etc. were improved.

Example 4 Styrene-acrylic resin 70 for masterbatch
Parts by weight, 10 parts by weight of polypropylene wax, and 20 parts by weight of the mixture A of the compatibilizer are mixed, melt-kneaded, cooled, and ground. Next, as a toner, the above master batch (a) 20 is used.
By weight, 86 parts by weight of styrene-acrylic resin, 7 parts by weight of carbon black and 3 parts by weight of quaternary ammonium salt were blended to obtain a final toner and a developer in the same manner as in Example 1. As a result of continuous copying, good evaluation was obtained when the master batch was used despite the reduction of wax and compatibilizer.

Example 5 For a masterbatch, 50 parts by weight of a polyester resin, 30 parts by weight of polypropylene wax, and 20 parts by weight of a mixture A of a compatibilizer are mixed, melt-kneaded, cooled and ground.
Next, as a toner, 10 parts by weight of the above masterbatch (b), 95 parts by weight of polyester resin, and carbon black 7
3 parts by weight of a quaternary ammonium salt were mixed to prepare a final toner and a developer in the same manner as in Example 1. As a result of continuous copying, good evaluation was obtained when the master batch was used despite the reduction of wax and compatibilizer.

Comparative Examples 1 to 3 are comparative examples in which no compatibilizer is used, and as shown in the evaluation after continuous copying of 10,000 sheets, a large amount of toner scatters,
White background fogging is also large, and moreover, there are many roller stains with respect to fixing peeling property. Comparative Examples 4 to 6 These are examples using a compatibilizing agent, and therefore, the evaluations after continuous copying of 10,000 sheets are as shown in Table 2, as shown in Comparative Examples 1 to 3.
Although it is slightly improved from 3, it is clear that satisfactory results have not been obtained because the type of compatibilizer is not appropriate.

[0021]

[Table 1]

[Table 2]

[Table 3]

[Table 4]

[0022]

As can be seen from the above examples, according to the present invention, it is possible to improve the dispersibility of the resin component, thereby improving the image quality such as reducing fog on a white background, and fixing and peeling. It is possible to provide a toner for electrostatic photography which has improved copying properties such as improved properties and improved toner scattering resistance, and the effect is extremely remarkable.

Claims (3)

[Claims] 1. A toner containing a binder resin, a colorant, a charge control agent, and a releasing material as main components, and ethylene / propylene rubber / ethylenehexene / as a compatibilizing agent of the releasing material to the binder resin. An electrophotographic toner comprising a mixture of ethylene vinyl acetate. 2. The toner for electrostatic photography according to claim 1, wherein at least a part of the binder resin, the releasing agent and the compatibilizing agent are blended in advance as a master batch. 3. The electrostatic charge according to claim 1 or 2, wherein the amount of the compatibilizer used is in the range of 2 to 10% by weight based on the total amount of the binder resin and the releasing material. Photographic toner.