JPS5845710B2 - Denshisha Shin Yotona - Google Patents

Description

[Detailed description of the invention] This invention relates to improved electrophotographic toners.

As the electrophotographic method, US Pat.
Various methods are described in Japanese Patent Publication No. 8, etc., but these methods basically apply a uniform electrostatic charge on a photoconductive insulating layer and irradiate the insulating layer with a light image to remove the electrostatic charge. A latent image is formed, and then the latent image is developed and visualized using a finely powdered electrosensitive substance called toner using the technology, and if necessary, the powder image is transferred to paper, etc., and then fixed by heating, pressure, solvent vapor, etc. It is something that forces you to do something.

Furthermore, in the color electrophotography method using multicolor superimposition, an original is exposed through a color separation filter, and the above process is repeated multiple times using color toners such as yellow, cyan, and cegenta to obtain a color image.

Toners used in the process of developing electrostatic latent images include:
Conventionally, particles obtained by dispersing a coloring agent such as carbon black in a binder resin such as polystyrene resin and pulverizing the particles to a size of about 1 to 30 μm have been used.

Such toners are usually mixed with carrier materials such as iron powder or glass beads and are used to develop electrostatic latent images.

Regarding the reproduction of the original, in conventional black and white electrophotography, the reproduction of line parts is more important than the solid parts, but it goes without saying that the reproduction of solid parts is also important, and even more important is the reproduction of solid parts in color electrophotography. is even more important.

Here, reproducing a solid portion means obtaining a uniform image with an appropriate image density relative to the original, but it is difficult to obtain a uniform image.

In order to obtain a uniform image, in addition to obtaining a uniform latent image,
Although uniform development and uniform transfer are necessary, the problem lies primarily in the lack of uniform development.

A magnetic brush method is a dry developing method capable of uniform development, but in this method, a phenomenon in which unevenness occurs in the image due to the magnetic brush, so-called unevenness, may appear.

Although this is primarily a problem related to the performance of the developing device, the developer is not unrelated.

For example, it is a fact that under the same development conditions, unevenness occurs when using a certain developer, but not when using another developer.

Therefore, an object of the present invention is to provide a toner and a developer that can be developed uniformly without causing unevenness.

Furthermore, in color electrophotography with multicolor superimposition,
The multicolor superposition increases the thickness of the imaging layer and can cause cracks in the image.

Increasing the thickness of the imaging layer is highly advantageous for obtaining uniform images in halftone solids.

This is because the image forming layer is thinner in the halftone area than in the area with maximum density, making uniform development more difficult, but if the image forming layer is made thicker, uniform development becomes easier. be.

However, the occurrence of cracks in the image due to this is extremely undesirable.

Therefore, another object of the present invention is to provide a toner that does not cause cracks in the image even when the thickness of the image forming layer increases.

Further, many toners having a low softening point tend to be easily crushed by collisions between toner and carrier, between toners, and between toner and a photosensitive plate due to rotation of a developing device.

This is undesirable as it leads to deterioration of the developer.

Therefore, another object of the present invention is to provide a toner that melts easily with low thermal energy and is impact resistant against mechanical forces.

In order to achieve the above object, as a result of intensive research, the present inventor found that a system in which a substance that is in a rubber state at room temperature is added to an epoxy resin is good, and in particular has a Tg (6 glass transition point) of 10°C or less.
and a system to which a substance selected from polyurethane resins, polyester resins, low molecular weight polyethylenes, ionomer resins and ethylene-ethyl acrylate copolymers having a Tm (melting point or softening point) of 70 to 150°C (by BAR method) is added. I found something nice.

That is, in the present invention, the epoxy equivalent synthesized from epichlorohydrin and bisphenol A is 900 to 350.
0 epoxy resin and Tg below 10℃ and 70-150
A toner for dry electrophotography containing at least one substance selected from a polyurethane resin, a polyester resin, a low molecular weight polyethylene, an ionomer resin, and an ethylene-ethyl acrylate copolymer having a Tm of ℃ (according to the BiR method). .

Examples of the epoxy resin used in the present invention include Epicoat 1004 (900-1000), Epicoat 100
7 (1750-2100), Epicote 1009 (24
00-3500) All manufactured by Shell.

Examples include Araldite 1-GY6084 (900 (1000)), Araldite GY6097 (1750-2100), and Araldite GY6099 (2400-3500) all manufactured by Ciba.

However, the number in parentheses indicates the epoxy equivalent.

In addition, the Tg used in the present invention is 10°C or less and 70 to 15
The polyurethane resin having a Tm of 0°C is preferably a polyester-based thermoplastic polyurethane elastomer, such as Pantex T-5205 Pandex T.
-5201 (all manufactured by Dainippon Ink Co., Ltd.).

Tg of 10℃ or less and 70 to 150℃ used in the present invention
As the polyester resin having a Tm of
, BJ7915 (Bosnic Japan Co., Ltd.), etc.

Tg of 10℃ or less used in the present invention is 70 to 150℃
Examples of low molecular weight polyethylene having Tm include Sunwax 171-P (1500) and Sunwax 151P.
(2000) and Sunwax 161-P (5000), both manufactured by Sanyo Chemical Co., Ltd., and the numbers in parentheses indicate average molecular weights.

Both AC polyethylene 615 and AC polyethylene 392 are available from Allied Chemical.

Tg of 10°C or less and 70 to 150° used in the present invention
Ionomer resins having a Tm of C include Surlyn $1555 (Na type) and Surlyn #1652 (Zn
Type) Both are manufactured by Mitsui Polychemical Co., Ltd.

As the ethylene-ethyl acrylate copolymer having a Tg of 10°C or less and a Tm of 70 to 150°C, DPD
J-6169°DPDJ-9169, both manufactured by Nippon Unicar Co., Ltd., etc.

These resins are used in amounts of 3 to 100 parts by weight of epoxy resin.
It is preferable to use a mixture of 35 parts by weight, preferably 5 to 25 parts by weight.

Among the above resins, polyurethane resins and polyester resins are particularly preferred because of their excellent compatibility with epoxy resins.

Its advantages are remarkable in color toners.

It is clear that all known dyes and pigments can be used as the colorant used in the present invention, such as carbon black, nigrosine, iron black, metal complex dyes, chrome yellow, Hansa yellow, benzidine yellow, Red Garla, Aniline Red Brilliant Carmine 6B, 2.9-
These include dimethyl quinacridone, xanthine magenta phosphotungsten molybdate lake pigment, navy blue, ultramarine blue, and phthalocyanine blue.

Further, as the carrier used in the present invention, iron powder, nickel powder, and those whose surfaces are treated with resin or the like are used.

The present invention will be described in detail below with reference to Examples.

Example 1 After melt-kneading 100 parts by weight of an epoxy resin (trade name: Araldite GY6084, manufactured by Ciba Corporation) and 20 parts by weight of a polyurethane resin (trade name: Punchx T-5205 (Tg<-72°C), manufactured by Inu Nihon Inc.), Coarsely crushed 10
0 parts by weight and 4.5 parts by weight of Phthalocyanine Blue (trade name Fastgen Blue-5007, manufactured by Dainippon Ink Co., Ltd.) were mixed and ground in a ball mill, then melted and kneaded in a roll mill, and after cooling, coarsely ground using a speed mill. Then, it is pulverized using an air jet type pulverizer.

The obtained fine powder is classified to select 3 to 20 microns, which is used as toner.

For 8 parts by weight of this toner, carrier iron powder (trade name EF
V200/300. 92 parts by weight (manufactured by Nippon Tetsuko Co., Ltd.) were mixed to prepare a developer.

When copying was performed using this developer with a dry plain paper electrophotographic copying machine (product name NP1100, manufactured by Canon),
A clear blue image with no fog was obtained.

Moreover, in the solid part, almost no unevenness due to the magnetic brush was observed.

Further, although the same sheet was repeatedly copied several times to make the thickness of the image forming layer approximately 40 μm, no cracks occurred in the image.

Example 2 Although the epoxy resin Araldite GY6097 was used in place of the epoxy resin Araldite GY6084 in Example 1, the same results as in Example 1 were obtained.

Example 3 Epoxy resin Epicoat 1009 was used in place of the epoxy resin Araldite GY6084 in Example 1, but almost the same results as in Example 1 were obtained.

Example 4 Instead of the polyurethane resin of Example 1, a polyester resin (trade name: Vylon 4P300Tg: 6°C) was used.

Tm: 123°C) manufactured by Toyobo Co., Ltd.) 15 parts by weight was used,
Similar results as in Example 1 were obtained.

Example 5 Instead of the polyurethane resin of Example 1, low molecular weight polyethylene (trade name Sunwax 151P ('I'g<-1
00°C, Tm: 107'C) manufactured by Sanyo Chemical Co., Ltd.) was used, but the same results as in Example 1 were obtained.

Example 6 Ethylene-ethyl acrylate copolymer DPDJ-6169 (Tg Kuichi 7) was used instead of the polyurethane resin of Example 1.
The same results as in Example 1 were obtained using 25 parts by weight (5°C).

Example 7 In place of the polyurethane resin in Example 1, 5 parts by weight of an ionomer resin, $1652 (Tg<-106°C), was used, but the same results as in Example 1 were obtained.

Example 8 Instead of phthalocyanine blue in Example 1, benzidine yellow (trade name, Simku Fast Yellow GTF) was used.
219. A developer was prepared in the same manner as in Example 1 using 7 parts by weight of C, 1, 21090).

When copied using an NP1100 machine, a clear yellow image with no fog was obtained.

In addition, almost no unevenness due to the magnetic brush was observed in the solid area, and even though copying was repeated multiple times on the same sheet and the thickness of the image forming layer was about 40 μm, no cracks were observed in the image.

Example 9 A developer was prepared in the same manner as in Example 1, using 4 parts by weight of 2゜9-dimethylquinacridone (trade name: First Gen Super Magenta R8, manufactured by Dainippon Ink Co., Ltd.) in place of the phthalocyanine blue used in Example 1. Ta.

When the image was copied using an NP1100 machine, a clear red image with no fog was obtained.

In addition, almost no unevenness was observed in the solid portion, and no cracks were observed in the image even when the thickness of the image forming layer was approximately 40 μm.

Example i.

In place of the phthalocyanine blue in Example 1, carbon black (trade name Luftex-8 manufactured by Cabot) 4
A toner was obtained in the same manner as in Example 1 using parts by weight.

8 parts by weight of this toner and carrier iron powder (product name: EF20)
0/300 manufactured by Nippon Tetsuko Co., Ltd.) were mixed to obtain a developer.

When copying was performed using this developer on an NP1100 machine,
A clear black image was obtained.

In addition, almost no unevenness was observed in the solid portion, and no cracks were generated in the image even when the thickness of the image forming layer was about 40 μm.

Comparative Example The polyurethane resin of Example 1 was not used, but the rest was Example 1.
When a developer was prepared in the same manner as above and copied using an NPI 100 machine, there was severe fog and a clear image could not be obtained.

In the solid portion, an undesirable unevenness phenomenon occurred, and although an image with an image forming layer thickness of about 30 μm was obtained, cracks were generated.

Claims (1)

[Claims] 1 Bisphenol type epoxy resin with an epoxy equivalent of 900 to 3500 and a Tg of 10°C or less and 70 to 150°C
(according to the B&R method) a polyurethane resin having a Tm of
An electrophotographic toner comprising at least one substance selected from polyester resin, low molecular weight polyethylene, ionomer resin, and ethylene-ethyl acrylate copolymer.