JPH0410068B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a developer composition for developing electrostatic images in electrophotography, electrostatic recording, electrostatic printing, and the like. As a conventional electrophotographic method, U.S. Patent No. 2297691
As stated in the specification of No. 2357809, etc.
A photoconductive insulating layer is uniformly charged, the layer is then exposed to light, and the charge on the exposed portions is dissipated to form an electrical latent image, and the latent image is injected with toner. The image is visualized by attaching colored, electrically charged fine powder (called a "development process"), and the resulting visible image is transferred to a transfer material such as transfer paper (transfer process), followed by heating, pressure, or It also includes a step of permanently fixing (fixing step) using an appropriate fixing method. As described above, the toner must have the functions required not only in the development process but also in each process, such as the transfer process and the fixing process. In general, toner is subjected to mechanical frictional force due to shearing force and impact force during mechanical operation in a developing device, and deteriorates during copying of several thousand or several copies.
To prevent such toner deterioration, it is best to use a strong resin with a large molecular weight that can withstand mechanical friction, but these resins generally have a high softening point.
Open fixing, which is a non-contact fixing method, and radiant fixing using infrared rays have poor thermal efficiency, so fixing cannot be performed sufficiently, and contact fixing has good thermal efficiency, so even the widely used heat roller fixing method is sufficient. It is necessary to raise the temperature of the heat roller to fix the toner, which not only causes problems such as deterioration of the fixing device, curling of the paper, and increased energy consumption, but also causes the toner to become pulverized when used. During manufacturing, manufacturing efficiency is significantly reduced. Therefore, it is not possible to use a binder resin whose polymerization degree and even softening point are too high. On the other hand, in the heat roller fixing method, the heating roller surface and the toner image surface of the sheet to be fixed are in pressure contact, so the thermal efficiency is extremely high and it is widely used from low speeds to high speeds. When the heated roller comes into contact with the heated roller, so-called offset development is likely to occur, in which the toner adheres to the surface of the heated roller and is transferred to the subsequent transfer paper or the like. In order to prevent this development, the surface of the heating roller is treated with a material with excellent mold release properties such as fluorine-based resin, but a mold release agent such as silicone oil is also applied to the surface of the heating roller to completely prevent the offset phenomenon. are doing. However, the method of applying silicone oil or the like is not preferable because it not only increases the size of the fixing device and increases the cost, but also makes it complicated and can easily cause trouble. Furthermore, as described in Japanese Patent Publication No. 55-6895 and Japanese Patent Application Laid-Open No. 56-98202, there is a method of improving the offset phenomenon by widening the molecular weight distribution width of the binder resin, but the degree of polymerization of the resin increases, It is also necessary to increase the fixing temperature. Furthermore, as an improved method,
There is a method of improving the offset phenomenon by making the resin asymmetrical and crosslinking, as described in Japanese Patent Application Laid-open No. 50-44836 and Japanese Patent Application Laid-open No. 57-37353, but the fixation point is not improved. Not yet. Generally, the minimum fusing temperature is between the cold offset and the hot offset, so the usable temperature range is between the minimum fusing temperature and the hot offset. By increasing the temperature as much as possible, the fixing temperature used can be lowered and the usable temperature range can be expanded, resulting in energy savings, high-speed fixing, and prevention of paper curl. In addition, since double-sided copying can be performed without trouble, copying machines have become more intelligent, and the temperature control of the fixing device has become more accurate.
There are many advantages such as relaxing the tolerance range. Therefore, resins and toners with good fixing properties and offset resistance are always desired. In addition, in order to achieve such requirements, when using a styrene-based binder resin, Japanese Patent Application Laid-Open No. 49-65232,
As described in JP-A-50-28840 and JP-A-50-18342, methods of adding paraffin wax, low molecular weight polyolefin, etc. as offset preventive agents are known, but they are not effective if the amount added is small. It has been confirmed that if the amount is too large, the developer deteriorates quickly, and in the case of polyester resin, even if the offset preventive agent mentioned above is applied, it has little effect, and if the amount used is too large, the developer deteriorates quickly. Polyester resins have inherently good fusing properties and are
As described in the specification of No. 3,590,000, sufficient fixing is achieved even in a non-contact fixing system, but offset phenomenon tends to occur, making it difficult to use in a heat roller fixing system. Also, JP-A-50-44836, JP-A-Sho
As described in No. 57-37353 and JP-A No. 57-109875, polyester resins with improved offset resistance using polycarboxylic acids do not have sufficient offset resistance to be used, or Not only do they sacrifice the low-temperature fixing properties inherent to polyester resins, but they also have extremely poor pulverization properties in the toner production process, causing problems in developer production. The present invention was made to meet these demands, and its purpose is to provide a developer that can prevent offset without applying an anti-offset liquid in a heat roller fixing system and that can fix at a lower fixing temperature. It is about providing. Another object of the present invention is to provide a developer which can prevent offset without adding an offset preventive agent in a heat roller fixing system and which can be fixed at a lower fixing temperature. Other objects of the present invention are to have good fluidity, no blocking, and long life (hard to deteriorate).
The purpose is to provide developer. Another object of the present invention is to improve kneading properties during developer production.
The objective is to provide a developer with good pulverizability. In order to achieve the above object, the present inventors have made extensive studies and have arrived at the present invention. That is, the present invention
In an electrophotographic developer composition comprising a binder resin and a colorant, the main component of the binder resin is (a) represented by the following formula: (In the formula, R is an ethylene or propylene group, x and y are each an integer of 1 or more, and the average value of x + y is 2 to 7.) and (b) (a) Divalent carboxylic acid or its acid anhydride or its lower alkyl ester, (b) trimellitic acid or its acid anhydride or its lower alkyl ester, and (c) the following formula (R ₁ is an alkyl group or alkenyl group having 20 to 60 carbon atoms, n+m is 10 to 30, and n: m
is 1:4~4:1, and the number average molecular weight is 8000~
20000. ) is a polyester resin co-polymerized with a carboxylic acid component consisting of a polycarboxylic acid or its acid anhydride having a softening point of 60 to 120°C, the polyester resin having a softening point of 100 to 180°C. The present invention relates to an electrophotographic developer composition characterized in that: Examples of the diol component (a) in the present invention include polyoxypropylene 2,2-2,2-bis(4-hydroxyphenyl)propane, polyoxypropylene (3,3)-2,2-bis( 4-hydroxyphenyl)propane, polyoxyethylene (2,0)-2,2-bis(4-hydroxyphenyl)propane, polyoxypropylene (2,0)-2,2-bis(4-hydroxyphenyl)propane,
0)-polyoxyethylene(2,0)-2,2-bis(4-hydroxyphenyl)propane, polyoxypropylene(6)-2,2-bis(4-hydroxyphenyl)propane, etc. I can do it. Furthermore, among the carboxylic acid components (b) in the present invention, the divalent carboxylic acids (a) include fumaric acid,
Alkyl or alkenyl succinic acids such as maleic acid, phthalic acid, n-dodecenyl succinic acid, isododecenyl succinic acid, n-dodecyl succinic acid, isododecyl succinic acid, n-octylsuccinic acid, n-octenylsuccinic acid, n-butylsuccinic acid, etc. etc. By using alkyl or alkenyl succinic acid, it is possible to lower the minimum fixing temperature without lowering the offset generation temperature, but if it is too little, the effect will be weak, and if it is too much, the Tg will decrease and toner caking will easily occur. Not only that, but it becomes difficult to control the reaction. Therefore, its content is preferably 5 to 30 mol% in the carboxylic acid component. In addition, (b) trimellitic acid is a preferable acid component that improves the offset phenomenon, but if it is small, the effect is weak, and if it is large, it is difficult to control the reaction and it is not only difficult to obtain a polyester resin with stable performance, but also the resin deteriorates. It becomes hard and difficult to crush, resulting in undesirable phenomena such as a marked decrease in toner conversion efficiency and an increase in the minimum fixing temperature. Therefore, the amount of trimellitic acid in the carboxylic acid component is preferably 5 to 30 mol%. Furthermore, the polycarboxylic acid (c) has 22 to 62 carbon atoms.
- It is a relatively low molecular weight copolymer with an average molecular weight of 8,000 to 20,000 obtained by a copolymerization reaction of olefin and maleic anhydride, and its copolymerization ratio is 1/1 in terms of α-olefin/maleic anhydride ratio. 4~
4/1, and its softening point (ASTM-E28-51T
The ring and ball softening point (according to
Examples of α-olefins used include n-dococene-(1), n-pentacocene-(1), n-dotriacontene-(1), n-tetracontene-(1), n-
Examples thereof include pentatetracontene-(1), n-pentacontene-(1), n-hexacontene-(1), 3-butyldocosene-(1), and 3-ethylhexacosene-(1). Inner olefins other than α-olefins, such as triacotene-(4) and hexacocene-(8), can also be contained, but since the toner tends to cause caking, it is recommended that the olefins contain up to 10% by weight of the olefins. can. By using such a polycarboxylic acid, it is possible to improve offset resistance without raising the minimum fixing temperature in the fixing process, but if a large amount is used, toner caking is likely to occur and it is difficult to control the reaction. It becomes difficult. Therefore, its content is 0.1 to 20% by weight in the carboxylic acid component, and more preferably 1% by weight.
~10% by weight. When producing the polyester resin of the present invention, the ratio of the number of hydroxyl groups in the diol component to the number of carboxyl groups in the carboxylic acid component is determined.
It is good to set it to 1.2 to 0.8, preferably 1.1 to 0.9.
If it exceeds 1.2 or less than 0.8, the reaction will not proceed sufficiently, and if there are too many carboxyl groups,
Tg and softening point become high, making it impossible to obtain sufficient offset resistance. On the other hand, when the number of hydroxyl groups increases, the Tg decreases, toner caking tends to occur, and image quality due to environmental changes is lost. In addition, the softening point (ring and ball softening point according to ASTME28-51T) of the polyester resin of the present invention is 100.
The temperature is preferably 180 DEG C. If it is too low, the offset resistance will be insufficient, and if it is too high, the fixing performance will be insufficient. The polyester resin used in the present invention can be produced by condensation polymerization of a polyhydric carboxylic acid component and a polyol component at a temperature of 180 to 250°C in an inert gas atmosphere. At this time, in order to accelerate the reaction, commonly used esterification catalysts such as zinc oxide, stannous oxide, dibutyltin oxide, dibutyltin dilaurate, etc. can be used. It can also be produced under reduced pressure for the same purpose. Coloring agents used in the present invention include carbon black, acetylene black, phthalocyanine blue, permanent brown FG, brilliant fast color, pigment green B, rhodamine-B base, and solvent red.
49, Solvent Red 146, Solvent Blue 35
etc. and mixtures thereof, and usually,
About 1 to 15 parts by weight is used per 100 parts by weight of the binder resin. Examples of the magnetic material used in the present invention include alloys or compounds containing elements exhibiting ferromagnetism, such as ferrite and magnetite. 40～
It can be used by dispersing it in an amount of 70% by weight. In addition, low molecular weight polypropylene, fatty acid ester wax, etc., which are generally used as offset prevention agents, can be used in some cases, but they are not effective if added in small amounts, and developer deterioration is likely to occur if added in large amounts, so they should not be added. Care must be taken regarding the amount. Examples of manufacturing the resin used in the present invention and examples of the present invention will be described below, but the present invention is not limited to these examples. Production example 1 Polyoxypropylene (2.2)-2,2-bis(4-hydroxyphenyl)propane 525g, polyoxyethylene(2)-2,2-bis(4-hydroxyphenyl)propane 487.5g, fumaric acid 172.5
Put 138 g of isooctyl succinic acid and 0.1 g of hydroquinone into a 4-neck glass flask, attach a thermometer, a stainless steel stirring bar, a flowing condenser, and a nitrogen inlet tube, and heat in a nitrogen stream in an electric heating mantle for 200 g. The reaction was carried out at ℃ while stirring. When water stopped flowing out, the acid value was measured and found to be 1.0 mgKOH/g. Furthermore, 115.2 g of trimellitic anhydride, 50% by weight of α-olefin having an average carbon number of 32, and maleic anhydride.
50% by weight of copolymer A (average molecular weight 8000, softening point
60℃) was added and reacted for about 8 hours until the acid value reached
The reaction was terminated when 25 mgKOH/g was reached. The resulting resin is a pale yellow solid with a softening point at the end of the process.
It was 122℃. Production example 2 Polyoxypropylene (2.2)-2,2-bis(4-hydroxyphenyl)propane 1000g, terephthalic acid 237.1g, n-dodecylsuccinic acid 286g
g, 0.5 g of stannous oxide, and 0.1 g of hydroquinone were placed in the same apparatus as in Production Example-1, and heated in a nitrogen stream.
The reaction was carried out at 230°C. When water stopped flowing out, the acid value was measured and found to be 1.5 mg/KOH/g. Furthermore, 54.9g of trimellitic anhydride and average carbon number
45 α-olefin 30% by weight and maleleic anhydride
70% by weight copolymer B (average molecular weight 10000, softening point
Add 29g (75℃) and react for about 8 hours until the softening point reaches 125.
The reaction was terminated when the temperature reached ℃. The resulting resin was a pale yellow solid with an acid value of 16 mgKOH/g. Example 1 93 parts of the resin obtained in Production Example-1 and 7 parts of carbon black were mixed in a ball mill, kneaded for 30 minutes in a pressure kneader, cooled, coarsely pulverized, and finely pulverized in a jet pulverizer. A toner with a particle size of 12μ was obtained. A developer was prepared by adding 95 parts by weight of iron powder carrier to 5 parts by weight of this toner, and the image was printed on a copying machine to evaluate the fixing properties and offset properties. Well established. When the surface temperature of the heat roller was further increased by 10°C, no offset occurred even at 240°C. The copying machine used was a commercially available copying machine (Xerox 2830 manufactured by Fuji Xerox Co., Ltd.) so that the surface temperature of the heat roller could be changed freely, and the accompanying offset prevention sleeve was removed, and a silicone rubber copying machine was used. This system uses only a fixing roller and a Teflon-coated heat roller. In addition, the image density is 1.0 optical density as measured by Macbeth reflection densitometer.
A cellophane tape was applied to the solid black area of ~1.1 with a constant pressure, and it was peeled off at a constant speed to determine whether or not toner adhered to the cellophane tape. Examples 2 to 5, Comparative Examples 1 to 5 Next, Table 1 shows several examples and comparative examples using polyester resins synthesized by a method similar to Production Example 1. As can be seen from this table, the developer composition using the resin of the present invention can be fixed at a lower temperature, and no offset occurs even at higher temperatures. White missing,
No deterioration phenomena such as edge development, background stains, or line blurring were observed.

【table】

【table】

Claims (1)

[Scope of Claims] 1. An electrophotographic developer composition comprising a binder resin and a colorant, wherein the main component of the binder resin is (a) represented by the following formula: (In the formula, R is an ethylene or propylene group, x and y are each an integer of 1 or more, and the average value of x + y is 2 to 7.) Carboxylic acid or its acid anhydride or its lower alkyl ester, (b) trimellitic acid or its acid anhydride or its lower alkyl ester, and (c) the following formula (R ₁ is an alkyl group or alkenyl group having 20 to 60 carbon atoms, n+m is 10 to 30, and n: m
is 1:4~4:1, and the number average molecular weight is 8000~
20000. ) is a polyester resin co-polymerized with a carboxylic acid component consisting of a polycarboxylic acid or its acid anhydride having a softening point of 60 to 120°C, the polyester resin having a softening point of 100 to 180°C. An electrophotographic developer composition characterized in that: