JPS5856863B2 - Toner for heat fixing type development - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a toner for developing an electrostatic latent image obtained, for example, in electrophotography, and particularly to a toner for heat-fixing type development.

In general, this type of developer toner is classified into so-called two-component type toner, which is used together with a carrier, and so-called one-component type toner, which has magnetic fine powder dispersed therein.

This component-based toner is also called a magnetic toner, has various characteristics, and is practically preferable.

On the other hand, the toner residue obtained by developing with such toner needs to be fixed on a transfer paper or the like, and a heat fixing method is widely used as the fixing method.

Among these methods, the fixing method using a heating roller fixing device is a contact type fixing method, so it has high thermal efficiency and can reliably fix the toner image using a relatively low-temperature heat source. It is preferable because there is very little risk of ignition even in the case of a fire.

When a toner image is fixed by bringing a heating element into contact with the toner image, such as in a heating roller fixing device, there is a risk that a so-called offset phenomenon may occur in which a portion of the toner adheres to the heating element and is transferred to the subsequent image area. There is.

This offset phenomenon occurs when the viscoelasticity of the toner melted by heating is inappropriate and too large or too small. Therefore, the temperature range in which the offset phenomenon does not occur depends on the type and type of resin that is the main component of the toner. It depends on the type and content of the ingredients contained.

However, in conventional one-component toner, it is usually 40 to 7
Since fine magnetic material powder with a weight of 0% is dispersed in the toner, its softening point is higher than that of a two-component toner, and naturally the lowest temperature at which it can be fixed is also higher.

As a result, the practical temperature range in which the offset phenomenon does not occur and in which fixing can be performed is extremely narrow, or in many cases does not exist.

Under these circumstances, when fixing an image formed using a conventional component-based toner using a heating roller fixing device,
It is necessary to impregnate the roller surface with silicone oil or supply silicone oil to the roller surface, which causes various problems. Also, when conventional one-component toner is used, photoreceptor etc. The surface of the latent image support (hereinafter referred to as "master") is significantly contaminated.

This phenomenon occurs because the toner contains fine powder of magnetic material, so it is easily crushed during stirring, and the resulting fine particle toner enters the recesses on the master surface. It is presumed that this is caused by adhesion of the particles to the master surface.

As such master contamination progresses, it becomes impossible to apply the required charge to the master, and the image density gradually decreases, shortening the life of the master.

The master contamination is caused not only by the fine particle toner generated by crushing as described above, but also by the fine particle toner which could not be removed in the classification operation.

However, this fine particle toner can be removed by spraying the finely pulverized toner into a hot air stream through a device such as a spray dryer, thereby causing the fine particle toner to fuse to the surface of the large-diameter toner.

In view of the above points, the present invention is a -component magnetic toner which has a wide temperature range in which no offset phenomenon occurs even when an image formed using the toner is fixed with a normal power-rotating heat roller fixing device. Another purpose is to provide a master with extremely low degree of contamination.

In the present invention, a magnetic toner containing a thermoplastic resin and a magnetic material as main components further contains a thermoplastic rubbery substance and a releasing substance.

The thermoplastic resin is a styrene polymer or a copolymer of styrene and other α,β-unsaturated ethylenic monomers, with a softening point of 60 to 200°C and a glass transition temperature of 30°C.
~150°C is preferred.

As the magnetic material, fine magnetite powder of 1 μm or less is usually used, but metals such as cobalt, iron, and nickel, alloys thereof, ferrite, and mixtures thereof can also be used.

Here, the α,β-unsaturated ethylenic monomer is:
For example, α-methylstyrene, p-engineered styrene,
2,4-dimethylstyrene, pn-butylstyrene, p
-tert-j Tylstyrene, p-n-hexylstyrene, p-'-n-octylstyrene, p-n-nonylstyrene, p-n decylstyrene, p-n-dodecylstyrene, p-methoxystyrene, p- Styrenes such as phenylstyrene, p-chlorostyrene, 3,4-dichlorostyrene, vinylnaphthalenes, ethylenically unsaturated monoolefins such as ethylene, propylene, butylene, isobutylene, vinyl chloride, vinyl bromide, vinyl fluoride , vinyl esters such as vinyl acetate, vinyl propionate, vinyl benzoate, vinyl acetate, methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, propyl acrylate, n-acrylate
octyl, dodecyl acrylate, lauryl acrylate,
2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, phenyl acrylate,
α-methyl chloroacrylate, methyl methacrylate,
Ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, ethyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, α-methylene aliphatic monocarboxylic acid esters such as phenyl methacrylate, dimethylamine ethyl methacrylate, diethylamine ethyl methacrylate, acrylic acid or methacrylic acid derivatives such as acrylonitrile, methacrylonitrile, acrylamide, vinyl methyl ether, Vinyl ethers such as vinyl ethyl ether and vinyl isophthyl ether, vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone, and methyl isopropenyl ketone, N-vinylpyrrole, N-vinylcarbazole,
N such as N-vinylindole and N-vinylpyrrolene
-vinyl compounds, etc.

Examples of thermoplastic rubbery substances include alkylene-vinyl acetate copolymers, partial hydrolysates of alkylene-vinyl acetate copolymers, graft copolymers of alkylene-vinyl acetate copolymers and vinyl chloride, and alkylene-acetic acid. Examples include graft combinations of partial hydrolysates of vinyl copolymers and unsaturated organic acids, copolymers of alkylene and α-olefins, styrene-butadiene copolymers, and especially ethylene-vinyl acetate copolymers. Preferred are polymers or partial hydrolysates thereof, and copolymers of ethylene and α-olefin.

The content of this thermoplastic rubber-like substance in the toner is
If the thermoplastic rubber material is an alkylene-vinyl acetate copolymer, the content of the vinyl acetate component is 10 to 40 weight. Preferably, it is a combination.

The addition of the thermoplastic rubbery material prevents master contamination.

This is believed to be because the addition of this rubbery substance increases the elasticity and toughness of the toner particles.

If the content of the rubbery substance is too large, the fluidity of the toner when it is melted will be reduced, and the thermal stability and pulverizability will also be reduced.

Moreover, if the content is excessive, master contamination will become noticeable.

Furthermore, as mentioned above, alkylene-vinyl acetate copolymer is preferable as this rubbery substance, but if the content of the vinyl acetate component is too large, the softening point of the toner decreases and the thermal stability deteriorates. Furthermore, the electrical resistance of the toner decreases, and the charge retention of the toner deteriorates, so that image blurring occurs at high humidity, and the crushability also decreases.

On the other hand, if the content is too low, there is a greater tendency for master contamination and offset phenomena to occur.

The mold release substance is effective in preventing offset phenomenon,
Specifically, low molecular weight polyalkylene resins such as polyethylene and polypropylene, fatty acid metal salts, higher fatty acids, higher alcohols, higher fatty acid amides, natural or synthetic paraffins, mixtures thereof, and the like are used.

The content of this releasing substance in the toner is 0.1 to 10
The weight [phi] is preferably 1 to 3 more weights; if the content is too low, an offset phenomenon will occur, and if it is too low, the fluidity of the toner will deteriorate and the cleaning performance will deteriorate.

The magnetic material may be contained in the toner at a ratio of 40 to 70 weight φ.

If this content is excessive, the electrical resistance of the toner will decrease,
The charge retention of the toner deteriorates, causing image blurring.

Furthermore, the softening point of the toner becomes high, making it difficult to perform suitable fixing and increasing the possibility of master contamination.

On the other hand, if the amount is too low, the function as a magnetic toner will be lost, the required charging ability will not be obtained, and the toner will easily scatter.

Further, the toner of the present invention has an average particle size of 5 to 30 μm,
Substantially no toner of 1 μm or less is contained.

1μ? If the toner contains n or less, master contamination becomes noticeable.

Furthermore, if the average particle size is 5 μm or less, not only master contamination is likely to occur, but also the fluidity of the toner becomes significantly poor.

When the average particle size is 30 μm or more, image distortion becomes noticeable.
It ceases to be practical.

The toner of the present invention naturally contains a colorant component.

As this colorant component, one or more of pigments and dyes such as carbon black and nigrosine can be used.

The charge of the toner can also be controlled by adding dyes.

Furthermore, 0.1 to 1 weight line aqueous silica may be added to the magnetic toner of the present invention in order to obtain the required fluidity.

The toner of the present invention is a one-component magnetic toner and is substantially insulating, and preferably has a high minimum temperature at which it can be fixed, and has a temperature range of 140 to 240 degrees above which no offset occurs. To suitably fix an image formed by the toner without supplying silicone oil or the like, without causing an offset phenomenon, using a fixing device having a heating roller whose surface is treated with ordinary Teflon. Can be done.

At the same time, master contamination is significantly reduced, and as a result, the toner can be put to practical use, for example, as a one-component toner for a repeat transfer type electronic copying machine having a heating roller fixing device.

The magnetic toner of the present invention is also preferably electrically insulating, since the toner image formed thereby can be suitably electrostatically transferred.

However, even if it is conductive, the effects of the present invention are not impaired.

In this case, by using a high-resistance electrically insulating paper as the transfer paper, or by first transferring the toner image to a conductive transfer roller or a silicone transfer roller, and then retransferring this transferred image to the image receiving paper, It is possible to achieve a suitable transfer.

Examples of the present invention will be specifically described below, but these are not intended to limit the present invention.

Note that "parts" indicate parts by weight.

Example l Styrene-acrylic resin (polymer of styrene:butyl methacrylate = 65:35...40
Magnetic powder (Mapico Black BL-50 manufactured by Titan Kogyo Co., Ltd.)
0) ・・・・・・・・・・・・50 parts Ethylene-vinyl acetate copolymer (manufactured by Toyo Soda Kogyo Co., Ltd. Ultracene-630) ・・・・・・・・・・・・10 parts Polypropylene ( Sanyo Chemical Co., Ltd. Viscoel 660P)
・・・・・・・・・・・・・・・2 parts carbon black (Mitsubishi Kasei MA-100)...
・・・・・・・・・・・・ 2-part black stain dye (Orient Chemical Co., Ltd. Oil Black BS) ・・・・・・・・・・・・・・・
・1 part of the mixture based on the above recipe was milled in a magnetic ball mill for 20
After mixing for an hour, the mixture was kneaded for 1 hour using two heated rolls.

After the obtained lumps were cooled to room temperature, they were finely pulverized with a jet mill, and the resulting powder was heat-treated using a spray dryer, and then passed through a zigzag classifier (manufactured by Alpine).
A magnetic toner of the present invention having an average particle size of 17 μm was produced.

In addition, as a comparison sample, a magnetic toner was prepared in the same manner by removing the ethylene-vinyl acetate copolymer from the above-mentioned formulation. Each of these samples was loaded into a U Bix (manufactured by Konishiroku Photo Industries Co., Ltd.) copying machine equipped with a developing device for magnetic toner, and fixed in a heated roller fixing device using zinc oxide and a photoreceptor. When the temperature was set at 200'C and 1000 copies were run, no offset development occurred with any of the magnetic toners, indicating that hot roll fixing was possible.

According to the magnetic toner of the present invention, clear images with high density and little fogging were obtained, and the deterioration in image quality was also very small.

However, according to the comparative magnetic toner, after 1,000 copies, master contamination had a reflection density of 0.25, fogging occurred with running, and deterioration of image quality such as image distortion and density reduction occurred.

According to the magnetic toner of the present invention, the master contamination after 1000 copies was 0.03 in reflection density.

Example 2 Styrene-acrylic resin (copolymer of styrene: methyl methacrylate = 5:3:2)...35 parts Magnetic (EPT-1000 manufactured by Toda Kogyo Co., Ltd.)...60 parts Polyethylene (manufactured by Petrolite Co., Ltd.) Barec.

2000 poly wax) ・・・・・・・・・・・・
・14 parts carbon black (Columbia Carbon Co., Ltd. Peerless-155) ・・・・・・・・・・・
...2 parts nigrosine dye (manufactured by Orient Chemical Co., Ltd.)
Oil black SO) ・・・・・・・・・
・・・・・・1 part ethylene-α-olefin copolymer (
Mitsui Petrochemical Co., Ltd. Tafmar P-480)
...... 4 parts A magnetic toner of the present invention having an average particle size of 15 μm was prepared in the same manner as in Example 1 except that the mixture of the above formulation was mixed and dispersed in a magnetic ball mill for 20 hours and then kneaded in an extruder. Manufactured.

In addition, as a comparative magnetic toner, a magnetic toner was prepared in the same manner from the above formulation except that polyethylene was removed.

To these two types of toners, 0.4 weight of the hydrophobic silica used in Example 1 was added, and image evaluation was performed using U-Bix750 (manufactured by Konishiroku Photo Industry Co., Ltd.) equipped with a magnetic toner developer. As a result, clear images with high density and little fogging were obtained with all toners.

In addition, each of the above magnetic toners was tested using a hot roll fixing tester.
When the fixing temperature was varied from 140°C to 220°C and the fixing performance and offset phenomenon were investigated, it was found that the magnetic toner of the present invention containing polyethylene as a releasing substance did not cause the offset phenomenon within the above measurement temperature range. It was found that fixing was possible at a temperature of 160° C. or higher.

However, according to the comparative magnetic toner, an offset phenomenon already occurred at a temperature of 170'C, and a fixing temperature of 170'C or higher was required.

Example 3 Styrene resin (Picolastic, manufactured by Esso Petrochemical Co., Ltd.)
D-125) ・・・・・・・・・・・・40
8B magnetic powder (RB-BL manufactured by Titan Kogyo Co., Ltd.)...55
Polypropylene (Viscol 660P manufactured by Sanyo Chemical Co., Ltd.)
) ・・・・・・・・・・・・・・・3
Carbon black (Mitsubishi Kasei MA-8)...
・・・・・・・・・・・・2 parts nigrosine base (Orient Chemical Co., Ltd. Oil Black EX) ・・・・・・・・・・・・・・・
・Partial hydrolyzate of 1 part ethylene-vinyl acetate (Dumilan D-219 manufactured by Mitsui Polychemical Co., Ltd.)
5 parts A mixture of the above formulation was treated in the same manner as in Example 1 to produce a magnetic toner of the present invention.

This magnetic toner was mixed with U-Bix-200O described in Example 1.
R (manufactured by Konishiroku Photo Industry Co., Ltd.) and set the fixing roller temperature to 19.
When a running test of 10,000 copies was conducted at 0°C, no offset development was observed.

Further, roller contamination and master contamination were very small, and the master contamination had a reflection density of between 0.02 and 0.05 after 10,000 copies.

The image after fixing has very good gradation and no fogging or
The image density was also satisfactory.

Example 4 Formulation-1 Styrene-acrylic resin (copolymer of styrene:butyl methacrylate:methyl methacrylate = 5:3:2)
・・・・・・・・・・・・35 parts ethylene-vinyl acetate (Toyo Soda Co., Ltd. Ultrasen 630
Vinyl acetate content: 16%)...5 parts Magnetic powder (BL-8P manufactured by Titan Kogyo Co., Ltd.)...60 parts Nigrosine base (Oil Black EX manufactured by Orient Chemical Co., Ltd.)
・・・・・・・・・・・・・・・1 part polypropylene (Viscol 66P manufactured by Sanyo Kaisha)
・・・・・・・・・・・・・・・Pa 2 part carbon black (Columbia Carbon Co., Ltd. Peerless-155)
・・・・・・・・・・・・・・・2 parts prescription-
2 Styrene-acrylic resin (same as formulation-1)...
・・・・・・25 parts ethylene-vinyl acetate (Toyo Soda Co., Ltd. Ultrasen)
710 VA content 27 buns)・・・・・・・・・・・・
15 parts magnetic powder (BL-8P manufactured by Titan Kogyo Co., Ltd.)...6
0 parts Nigrosine base (Orient Chemical Co., Ltd. Oil Black EX) ・・・・・・・・・・・・
・・・1 part polypropylene (Viscol 660P manufactured by Sanyo Chemical Co., Ltd.) ・・・・・・・・・・・・
・・・2 parts carbon black (Columbia Carbon Peerless-155) ・・・・・・・・・・・・
...2-part prescription-3 Styrene-acrylic resin (same as prescription-1)...
・・・・・・・・・15 parts ethylene-vinyl acetate (Toyo Soda Co., Ltd. Ultrasen)
541 VA content 10%)・・・・・・・・・・・・
25 parts magnetic powder (BL-8P manufactured by Titan Kogyo Co., Ltd.)...6
0 parts Nigrosine base (Orient Chemical Co., Ltd. Oil Black EX) ・・・・・・・・・・・・
・・・1 part polypropylene (Viscol 660P manufactured by Sanyo Chemical Co., Ltd.) ・・・・・・・・・・・・
・・・2 parts carbon black (Columbia Carbon Peerless-155) ・・・・・・・・・・・・
...2 parts prescription-4 Styrene-acrylic resin (same as prescription-1)...
・・・・・・30 parts ethylene-vinyl acetate (Toyo Soda Co., Ltd. Ultrasen)
760 VA content 40φ)・・・・・・・・・・・・
10 parts Magnetic powder (BL-8P manufactured by Titan Kogyo Co., Ltd.)...6
0 parts Nigrosine base (Orient Chemical Co., Ltd. Oil Black EX) ・・・・・・・・・・・・
・・・1 part polypropylene (Viscol 660P manufactured by Sanyo Chemical Co., Ltd.) ・・・・・・・・・・・・
・・・2 parts carbon black (Columbia Carbon Peerless-155) ・・・・・・・・・・・・
...2 parts A mixture of each of the above formulations was melted and kneaded with a hot roll, cooled, and coarsely crushed.

The coarsely ground material was further kneaded using an extruder.

The subsequent granulation steps from fine pulverization were carried out in the same manner as in Example 1 to produce a magnetic toner having an average particle size of 15 μn.

0.2 weight of the hydrophobic silica used in Example 1 was added to these magnetic toners, and UBix 20 described in Example 1 was added.
00 R was run for 1000 copies, and the fixing properties and offset phenomenon were further examined using the hot roll tester described in Example 2. Each magnetic toner was stored in a constant temperature and humidity tank at a temperature of 50° C. and a relative humidity of 80 φ for 10 days. , heat resistance and humidity resistance were investigated.

These results are shown in the table below.

As can be seen from this table, the toner of the present invention has excellent properties, particularly in terms of preventing the offset phenomenon and preventing master contamination.

If the content of the rubbery substance increases, or if the rubbery substance is an ethylene-vinyl acetate copolymer and the vinyl acetate component content increases, the pulverization and granulation properties actually decrease. As a result, the amount of toner with the required particle size that can be obtained in the classification step after pulverization will be reduced, which is not a good idea.

Claims (1)

[Claims] 1 Thermoplastic resin, thermoplastic rubber-like substance, magnetic material having a weight φ of 40 to 70 with respect to the toner weight, and 0.1 to 10
The thermoplastic resin is at least one of a styrene polymer and a copolymer of styrene and another α,β-unsaturated ethylenic monomer. A characteristic heat-fixing type developing toner.