JPH0736210A - Electrophotographic toner - Google Patents

Abstract

PURPOSE:To obtain an electrophotographic toner fixable even at a low fixing temp. and excellent in anti-offsetting property and fixing strength to transfer paper by incorporating at least long chain prim. alcohol having a specified structure. CONSTITUTION:This electrophotographic toner contains at least long chain prim. alcohol having a structure represented by the formula [where R is H or CH3 and (n) is about 20-100]. In the case where R is CH3, the prim. alcohol has reduced crystallinity and a lower m.p. The prim. alcohol is preferably contained in this toner by 0.5-20wt.% of the total amt. of the prim. alcohol and a bonding resin as a base as resin components constituting this toner. Since such long chain prim. alcohol has a lower m.p. than polyolefin wax used so far and has releasability to a fixing roll, when the prim. alcohol is incorporated into an electrophotographic toner, it lowers the softening point of the toner, melts well even under a heat fixing roll at a low temp. and ensures excellent anti-offsetting property and fixing strength.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic toner, and more particularly to an electrophotographic toner for a copying machine or printer which employs heat roll fixing.

[0002]

2. Description of the Related Art In recent years, electrophotographic copying machines and printers have been widely used in general households and the like. (Reduction of power consumption), high speed for the purpose of spreading to so-called gray area located at the boundary between printing machine and copying machine, or low roll pressure for simplification of fixing roll to reduce machine cost. Is desired. In addition, copiers equipped with a double-sided copy function and an automatic document feeder have become widespread along with the sophistication of copiers, so electrophotographic toner used in copiers and printers has a low fixing temperature and offset resistance. Is excellent
In addition, in order to prevent stains during double-sided copying and stains in the automatic document feeder, those having excellent fixing strength on transfer paper are required.

In order to meet the above requirements, the prior art has proposed proposals for improving the molecular weight and molecular weight distribution of the binder resin. Specifically, attempts have been made to lower the fixing temperature by lowering the molecular weight of the binder resin. However, when the molecular weight is lowered, the melting point is lowered, but at the same time, the viscosity is also lowered, which causes a problem that an offset phenomenon occurs on the fixing roll. In order to prevent this offset phenomenon, a method of widening the low molecular weight region and the high molecular weight region of the molecular weight distribution of the binder resin, or cross-linking of the polymer portion has been performed. However, in this method, the glass transition temperature of the resin is unavoidably lowered in order to have sufficient fixing property, and it is unavoidable that the storability of the toner is impaired. Further, if the low molecular weight portion of the binder resin is increased, the toner itself becomes brittle, and stains are generated during double-sided copying and stains on the automatic document feeder. Furthermore, there is also a method of incorporating a low molecular weight polyolefin-based release agent in order to prevent the offset phenomenon. However, the commercially available low molecular weight polypropylene has a melting point of 130 to 140 ° C., and when fixing at low temperature, the effect on the offset property of the toner was not sufficient. Furthermore, when such a polypropylene is contained in a low melting point toner, the melting point of the toner becomes high,
When fixing is performed at a low fixing temperature, there is a problem that sufficient fixing strength on the transfer paper cannot be obtained.

[0004]

SUMMARY OF THE INVENTION The object of the present invention is for electrophotography, which can fix at a low fixing temperature, does not cause any practical problems even in non-offset properties, and has excellent fixing strength on transfer paper. To provide toner.

[0005]

SUMMARY OF THE INVENTION The present invention is an electrophotographic toner containing at least a long-chain primary alcohol having the following structure.

[0006]

[Chemical 2]

The present invention will be described in detail below. The long-chain primary alcohol (the following structural formula) applied to the electrophotographic toner of the present invention has a low melting point and lowers the melting start temperature of the electrophotographic toner when mixed with a binder resin as a main component. The low temperature fixability is improved.

[0008]

[Chemical 3]

In the long-chain primary alcohol of the above structural formula, R is H.
CH ₃ has a lower crystallinity and a lower melting point than CH ₃ .
Further, in the present invention, those having n = 20 to 100 are used. Specific examples of the long-chain primary alcohol as described above include a trade name: UNILIN 350 manufactured by Petrolite Co., Ltd.
Alcohol, UNILIN 425 Alcoh
ol, UNILIN 550 Alcohol, UNI
LIN 700 Alcohol, X-1049 (n =
33), X-1071 (n = 69), X-1026 (n
= 22), X-1038 (n = 30) and the like.
The content of the long-chain primary alcohol in the electrophotographic toner is 0. 0, based on the total amount of the resin components consisting of the long-chain primary alcohol and the binder resin as the main component constituting the electrophotographic toner. It is preferable to contain 5 to 20% by weight.
If the amount is less than 0.5% by weight, the effect of lowering the melting point of the electrophotographic toner is small. Therefore, when fixing at a low fixing temperature, it is difficult to obtain sufficient fixing strength on the transfer paper. If the amount is more than 20% by weight, the binder resin is used. It is not preferable since the long-chain primary alcohol is poorly dispersed and the toner blocking property and the charging stability are poor due to poor compatibility with. Long-chain primary alcohols have lower melting points than conventionally used polyolefin waxes and also have releasability for fixing rollers, so when incorporated in electrophotographic toners, the softening point of the toners is lowered. Even if it is a heat fixing roll at a low temperature, it is sufficiently melted, and it has excellent effects on non-offset property and fixing strength.

Next, materials other than the long-chain primary alcohol constituting the electrophotographic toner of the present invention, that is, the binder resin, the colorant and the like will be described. Binder resin as a main component used in the present invention, polystyrene resin, polyacrylic acid ester resin, styrene-acrylic acid ester copolymer resin, styrene-methacrylic acid ester copolymer resin,
Examples thereof include polyvinyl chloride, polyvinyl acetate, polyvinylidene chloride resin, phenol resin, epoxy resin and polyester resin. When the long-chain primary alcohol of the present invention is used by mixing it with the above-mentioned binder resin, it is preferable to perform not only simple melt mixing but also graft copolymerization on the binder resin.
When the long-chain primary alcohol is grafted with the binder resin, the dispersibility of the alcohol is improved, and it is possible to prevent the kneaded product from being desorbed or reaggregated during kneading. As a method of grafting the long-chain primary alcohol used in the present invention to the binder resin, a hydroxyl group is introduced into the binder resin, and diisocyanate or polyisocyanate is used as a cross-linking agent. It can be achieved by hot-melt kneading with a long-chain primary alcohol. The reaction rate between the hydroxyl group of alcohol and the isocyanate becomes slower in the order of primary>secondary>tertiary>. Therefore, the long-chain primary alcohol of the present invention has the fastest reaction rate and is the preferred form. As a method of introducing a hydroxyl group into the binder resin, as a hydroxyl group-containing monomer, para-hydroxystyrene, hydroxyethylhexyl acrylate, hydroxyethyl methacrylate or the like is copolymerized with another styrene or a monomer such as acryl, or the terminal hydroxyl group of the polyester resin is used. There are ways to use it. Examples of diisocyanates or polyisocyanates as the crosslinking agent include 2,4 tolylene diisocyanate, 2,6 tolylene diisocyanate, diphenylmethane-4,4'-diisocyanate, polymethylene polyphenyl polyisocyanate and the like. In addition, these isocyanates may be blocked with a blocking agent such as phenol or alcohol. The reaction when the hydroxyl group in the binder resin and the long-chain primary alcohol of the present invention are crosslinked with diisocyanate or polyisocyanate to form a graft copolymer is considered as follows.

[0011]

[Chemical 4]

As shown in the above reaction formula, the long-chain primary alcohol is added to the reaction product of the hydroxyl group-introduced acrylic resin and diisocyanate to obtain the graft copolymer in the bottom column.

As the colorant used in the toner of the present invention, carbon black, nigrosine dye, aniline blue, calco oil blue, chrome yellow, ultramarine blue, DuPont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, malachite green. Examples include oxalate and a mixture thereof. It is necessary that these colorants are contained in a sufficient ratio so that a visible image having a sufficient density is formed, and the amount is usually 1 per 100 parts by weight of the binder resin.
The ratio is about 20 parts by weight.

Regarding the melting characteristics of the toner, the melting start temperature of the toner is 6 in order to improve the fixing property at a lower temperature.
It is preferably 0 ° C or higher and 100 ° C or lower. If it is higher than 100 ° C., the fixing property is not sufficient, and if it is lower than 60 ° C., the blocking property is deteriorated and the storage stability may be deteriorated. The melting start temperature refers to the falling start temperature of the plunger and was measured by the following measuring method. Measuring machine: Shimadzu's advanced flow tester CF-50
0 The measurement conditions are as follows. Plunger: 1 cm ² , Die diameter: 1 mm, Die length: 1 mm, Load: 20 KgF, Preheating temperature: 50
~ 80 ° C, Preheating time: 300sec, Temperature rising rate: 6 ° C /
min.

In the electrophotographic toner of the present invention, the above-mentioned long-chain primary alcohol, binder resin and colorant are appropriately mixed with other toner components such as a charge control agent, a release agent and a magnetic material. The average particle size is 5 to
It is in the range of 20 μm. A toner for electrophotography may be formed by adding and mixing a fluidity improver made of fine silica powder or the like to the particles thus obtained.

The electrophotographic toner of the present invention is mixed with a carrier composed of iron powder, ferrite, granulated magnetite or the like to be a two-component developer, or a magnetic one-component developer or a non-magnetic one without mixing with a carrier. It may be used as a component developer.

[0017]

EXAMPLES The present invention will be described below based on examples. In the examples, “part” means “part by weight”. Example 1 58 parts of styrene, 22 parts of butyl acrylate and 20 parts of hydroxyethyl methacrylate were copolymerized by a suspension polymerization method to obtain a weight average molecular weight of 14 × 10 ⁴ and a number average molecular weight of 0.4.
A styrene-acrylic acid ester copolymer resin containing hydroxyl groups of 10 ⁴ was obtained. -Styrene-acrylic acid ester copolymer resin 90 parts-Chromium-containing metal dye 1.5 parts (Orient Chemical Co., Ltd. product name: Bontron S-34) -Carbon black 6.5 parts (Mitsubishi Chemical Industries product Name: MA-100) -Blocked isocyanate (polyisocyanate) 10 parts (Bayer Co., Ltd. product name: Cleran UI) -Polypropylene 3 parts (Sanyo Kasei Co., Ltd. product name: Viscol 660P) -Long chain primary alcohol 10 parts ( Product name: UNILIN 350, melting point 78 ° C manufactured by Petrolite Co., Ltd.) The raw materials having the above mixing ratios are mixed in a super mixer, melt-kneaded by a twin-screw kneader, crushed by a jet mill, and then by a dry airflow classifier. After classification, the average particle size is 10
Particles of μm were obtained. Then, 100 parts of the particles and hydrophobic silica (trade name: Cabosil TS-53 manufactured by Cabot Corporation)
0.4 parts of 0) was stirred for 1 minute in a Henschel mixer, and hydrophobic silica was adhered to the surface of the particles to obtain the electrophotographic toner of the present invention.

Example 2 90 parts of the above styrene-acrylic acid ester copolymer resin 1.5 parts of chromium-containing metal dye (trade name: Bontron S-34 manufactured by Orient Chemical Industry Co., Ltd.) Carbon black 6.5 parts ( Mitsubishi Kasei Kogyo Co., Ltd. product name: MA-100) ・ Blocked isocyanate (polyisocyanate) 10 parts (Bayer Co. product name: Cleran UI) ・ Polypropylene 3 parts (Sanyo Chemical Co., Ltd. product name: VISCOL 660P) ・ Long chain Primary alcohol 10 parts (trade name: UNILIN 425, manufactured by Petrolite Co., melting point 91 ° C.) The raw materials having the above blending ratios are mixed with a super mixer, hot-melt kneaded with a twin-screw kneader, and then ground with a jet mill, After that, it was classified by a dry airflow classifier to obtain an average particle size of 10
Particles of μm were obtained. Then, 100 parts of the particles and hydrophobic silica (trade name: Cabosil TS-53 manufactured by Cabot Corporation)
0.4 parts of 0) was stirred for 1 minute in a Henschel mixer, and hydrophobic silica was adhered to the surface of the particles to obtain the electrophotographic toner of the present invention.

Example 3 90 parts of the above styrene-acrylic acid ester copolymer resin-1.5 parts of chromium-containing metal dye (trade name: Bontron S-34 manufactured by Orient Chemical Industry Co., Ltd.)-Carbon black 6.5 parts ( Mitsubishi Kasei Kogyo Co., Ltd. product name: MA-100) ・ Blocked isocyanate (polyisocyanate) 10 parts (Bayer Co. product name: Cleran UI) ・ Polypropylene 3 parts (Sanyo Chemical Co., Ltd. product name: VISCOL 660P) ・ Long chain Primary alcohol 10 parts (Petrolite product name: UNILIN 550, melting point 99 ° C.) The raw materials having the above blending ratios are mixed with a super mixer, hot melt kneaded with a twin-screw kneader, and then ground with a jet mill, After that, it was classified by a dry airflow classifier to obtain an average particle size of 10
Particles of μm were obtained. Then, 100 parts of the particles and hydrophobic silica (trade name: Cabosil TS-53 manufactured by Cabot Corporation)
0.4 parts of 0) was stirred for 1 minute in a Henschel mixer, and hydrophobic silica was adhered to the surface of the particles to obtain the electrophotographic toner of the present invention.

Example 4 90 parts of the above styrene-acrylic copolymer resin 1.5 parts of chromium-containing metal dye (trade name: Bontron S-34 manufactured by Orient Chemical Industry Co., Ltd.) Carbon black 6.5 parts (Mitsubishi Kasei) Kogyo Co., Ltd. product name: MA-100) ・ Blocked isocyanate (polyisocyanate) 10 parts (Bayer Co. product name: Cleran UI) ・ Polypropylene 3 parts (Sanyo Kasei Co., Ltd. product name: Viscol 660P) ・ Long chain first grade Alcohol 10 parts (trade name: UNILIN 700, melting point 105 ° C., manufactured by Petrolite Co., Ltd.) The raw materials having the above mixing ratios are mixed with a super mixer, melt-kneaded with a twin-screw kneader, ground with a jet mill, and then dry The average particle size is 10 after classification with an airflow classifier.
Particles of μm were obtained. Then, 100 parts of the particles and hydrophobic silica (trade name: Cabosil TS-53 manufactured by Cabot Corporation)
0.4 parts of 0) was stirred for 1 minute in a Henschel mixer, and hydrophobic silica was adhered to the surface of the particles to obtain the electrophotographic toner of the present invention.

Example 5 78 parts of styrene and 22 parts of butyl acrylate were copolymerized by a suspension polymerization method to obtain a styrene acrylate copolymer having a weight average molecular weight of 13 × 10 ⁴ and a number average molecular weight of 0.5 × 10 ^4. Obtained. An electrophotographic toner of the present invention was obtained in the same manner except that the blocked isocyanate of Example 1 was not used.

Comparative Example 1 A comparative electrophotographic toner was obtained in the same manner as in Example 1 except that long-chain primary alcohol and blocked isocyanate were not used.

Comparative Example 2 A comparative electrophotographic toner was obtained in the same manner as in Example 1 except that the long chain primary alcohol was changed to polyethylene (trade name: PE-130 manufactured by Hoechst Co., Ltd.).

Next, the following items were tested for the above-mentioned Examples and Comparative Examples. (1) Non-Offset Temperature Region First, 4 parts of each electrophotographic toner obtained in the above-mentioned Examples and Comparative Examples and 96 parts of a ferrite carrier (Powder Tech Co., Ltd. product name: FL-1020) not coated with a resin were prepared. A two-component developer was prepared by mixing. Next, a commercially available copying machine (trade name: SF-9, manufactured by Sharp Corporation) is used using the developer.
800), a plurality of belt-shaped unfixed images having a length of 2 cm and a width of 5 cm were formed on an A4 transfer paper. Then, a heat fixing roll having a surface layer made of a fluororesin and a pressure fixing roll having a surface layer made of silicone rubber are paired and rotated, and a fixing device is rotated at a roll pressure of 1 Kg / cm ² and a roll speed of 50.
The surface temperature of the heat fixing roll was changed stepwise, and the toner image on the transfer paper having the above-mentioned unfixed image was fixed at each surface temperature. At this time, it was observed whether or not toner stains were generated in the margins, and the temperature region where stains did not occur was taken as the non-offset temperature region. Further, the difference between the maximum value and the minimum value in the non-offset temperature region was defined as the non-offset temperature width.

(2) Fixing Strength The surface temperature of the heat fixing roll of the fixing device was set to 130 ° C., and the toner image on the transfer paper on which the unfixed image was formed was fixed. Then, the formed fixed image was rubbed with a cotton pad, and the fixing strength was calculated by the following formula to be used as an index of low energy fixing property. As the image density, a reflection densitometer RD-914 manufactured by Macbeth was used. Fixing strength (%) = image density of fixed image after rubbing / image density of fixed image before rubbing × 100 The test results of the above items are shown in Table 1. (3) Melting start temperature Measuring instrument and measuring conditions are as described above.

[0026]

[Table 1]

As is clear from the test results of Table 1, in the electrophotographic toners of Examples 1 to 5 of the present invention, the offset does not occur in the non-offset temperature region from the low temperature to the high temperature, and the temperature range thereof is also wide. It was confirmed that a practically sufficient range of 80 to 90 ° C. was maintained. In addition, the fixing temperature 13
The fixing strength at 0 ° C. was 80% or more, and it was confirmed that the fixing strength was practically sufficient. On the other hand, in Comparative Examples 1 and 2, the fixing strength at the fixing temperature of 130 ° C. is 75.
It was confirmed to be as low as% or less. Also,
Commercially available copying machines using each developer (Toshiba brand name:
The result of continuous copying test up to 10,000 sheets with BD-3801) shows that in all of Examples 1 to 5, the triboelectrification amount was −2 from the initial stage to 10000 sheets.
The value changes from 0 μc / g to −25 μc / g, and the image density is 1.45 to 1.4 from the initial to 10,000 sheets.
It was confirmed that there was no problem in practical use because the value changed to 0. The copied original is A4 with 6% black.
belongs to. The triboelectric charge amount was measured using a blow-off triboelectric charge amount measuring device manufactured by Toshiba Chemical Co., and the image density was measured using a reflection densitometer RD-914 manufactured by Macbeth.

[0028]

The electrophotographic toner of the present invention is capable of fixing at a low temperature while maintaining a sufficient non-offset temperature region, is excellent in fixing strength, and is capable of obtaining a sufficient number of image densities. It has the effect of being able to.

Claims (4)

[Claims] 1. An electrophotographic toner comprising at least a long-chain primary alcohol having the following structure. [Chemical 1] 2. The toner for electrophotography according to claim 1, wherein the content of the long-chain primary alcohol in the resin component is 0.5 to 20% by weight. 3. The electrophotographic toner according to claim 1, which contains a binder resin containing a hydroxyl group and a diisocyanate or a polyisocyanate. 4. The melting start temperature of the toner is 60 ° C. or higher and 10
The toner for electrophotography according to claim 1, which has a temperature of 0 ° C. or lower.