JPH0232623B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a toner for developing electrostatic images formed in electrophotography, electrostatic printing, electrostatic recording, and the like. [Background of the Invention] For example, in electrophotography, an electrostatic latent image is usually formed by charging and exposing an electrostatic image support made of a photoconductive photoreceptor, and then this electrostatic latent image is coated with a binder resin. Developed with a toner formed by containing a coloring agent etc. in fine particles,
The resulting toner image is transferred to a support such as transfer paper and then fixed by heating, pressure, etc. to form a visible image. It is of course preferable to form a visible image via such an electrostatic charge image at high speed, and from this point of view, conventionally, the heat roller fixing method has high thermal efficiency in the fixing process and is advantageous compared to other methods. has been widely adopted. However, recently there has been a strong demand for even higher speeds, and in order to achieve this,
It is an essential condition to speed up the fixing of toner images. Therefore, in order to fix toner images at high speed in the hot roller fixing method, the toner used for development is required to have good low-temperature fixability, and for this purpose, the binder resin that makes up the toner needs to be softened. Need to lower the score. However, if the softening point of the binder resin of the toner is lowered, part of the toner forming the image will be transferred to the surface of the heat roller during fixing, and this will be transferred again to the next transferred transfer paper, etc., and the image will be transferred. There is a tendency for smudging, or so-called offset development, to occur. In addition to the above-mentioned offset phenomenon, the hot roller fixing system has a problem in that a so-called wrapping phenomenon occurs in which the transfer paper or the like is adhered to and wrapped around the surface of the hot roller. This wrapping phenomenon occurs particularly when the temperature of the heat roller is too low. In order to successfully achieve such high-speed fixing, the toner needs to be capable of low-temperature fixing and have excellent non-offset and non-wrapping properties. [Prior Art] Vinyl polymers have been widely used as binders in toners, and in order to obtain non-offset properties in toners using vinyl polymers as binders, high molecular weight polymers are used. However, since high molecular weight vinyl polymers have a high softening point, it is difficult to obtain a wide fixable temperature range even if the offset generation temperature is high, and it is difficult to obtain a suitable toner. I can't. On the other hand, polyester resin can be relatively easily obtained in the form of a low molecular weight material, so it is possible to use it as a binder to obtain a toner with a low softening point. Compared to toners made of vinyl polymers, they have better "wetting" to a support such as transfer paper when melted, and can achieve sufficient fixation at a lower temperature than toners made of vinyl polymers, which have approximately the same softening point. This is preferable because it can be done. However, toners using polyester resin as a binder usually have a drawback of low offset generation temperature. On the other hand, in order to raise the offset generation temperature of the toner, it is effective to include a high molecular weight component in the binder resin of the toner.
If sufficient non-offset properties are to be obtained in the toner by this means, the minimum temperature required for fixing the toner (hereinafter referred to as "minimum fixing temperature") will be high because the resin has a high softening point. As a result, the advantages of the heat roller fixing method are lost. Naturally, it is desirable that this minimum fixing temperature be low, and in order to achieve the formation of visible images on both sides of a single sheet of transfer paper, which has recently become a high demand, the toner used for development must be It is necessary that the material can be fixed at a low temperature. From the above background, by incorporating a release agent made of polyolefin wax such as polypropylene wax or polyethylene wax into toner particles, it is possible to lower the minimum fixing temperature and improve non-offset and non-wrapping properties. Measures have been developed to improve sexual performance. Such a method allows the toner itself to have low-temperature fixing properties and a release agent, and compared to a method in which fixing is performed while applying a release oil such as silicone oil to the surface of a heated roller, it is easier to apply silicone oil. Since no mechanism is required, the structure of the fixing device is simple, and it is superior in that maintenance such as replenishment of silicone oil is not required. However, in such a method, in order to fully obtain the effect of adding wax, the content ratio of the wax must be increased considerably, and as a result, the fluidity of the powdered toner decreases. However, as a result, developability and transferability deteriorate, resulting in a failure to form a good visible image, and there is a tendency for the toner to become cohesive.Furthermore, the carrier and developing sleeve that are mixed with the toner to form a two-component developer Alternatively, the wax component may adhere to the electrostatic image support, forming a film and contaminating it, which may impede its function. In addition, in a recycling system for efficient use of toner, that is, a system in which toner that has been subjected to development but did not participate in the formation of a visible image is returned to the developing device and used again for development, the fluidity of toner is The disadvantage is that the resistance is significantly reduced and the durability is low. In this way, with the technical means of incorporating a release agent into toner, it is difficult to obtain sufficient low-temperature fixing and release properties as well as sufficient fluidity in the toner with one type of release agent. It is extremely difficult to perform the formation at even higher speeds. [Object of the Invention] The present invention has been made based on the above-mentioned circumstances, and its object is to have a low minimum fixing temperature, sufficient mold releasability, good fluidity, and durability. The object of the present invention is to provide a toner for developing electrostatic images that has high properties and can form excellent visible images at high speed over many times. [Structure of the Invention] The above object is to combine a binder resin made of a polyester resin containing 5% by weight or more of chloroform-insoluble matter, carnauba wax and/or candelilla wax, and an alkylene bis represented by the following general formula. This is achieved by an electrostatic image developing toner characterized by containing a release agent made of a fatty acid amide compound. general formula [In the formula, R ₁ and R ₂ are each the same or different saturated or unsaturated aliphatic hydrocarbon groups having 10 or more carbon atoms, and R ₃ and R ₄ are each the same or different hydrogen atoms or -OCR ₅ groups (However, R ₅ represents a saturated or unsaturated aliphatic hydrocarbon group.)
, and n represents a positive integer. ] The present invention will be specifically explained below. In the present invention, a polyester resin having a chloroform-insoluble content of 5% by weight or more is used as a binder resin, and carnauba wax and/or candelilla wax (hereinafter simply " ) and a mold release agent made of an alkylene bis fatty acid amide compound represented by the above general formula (hereinafter also simply referred to as "second mold release agent"). Used as toner for developing charge images. The polyester resin used as the binder resin in the present invention is obtained by polycondensation of alcohol and carboxylic acid, and the alcohols used include, for example, ethylene glycol, diethylene glycol, triethylene glycol, 1,
Diols such as 2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, neopentyl glycol, 1,4-butenediol, 1,4-bis(hydroxymethyl)cyclohexane, and bisphenol A, Examples include etherified bisphenols such as hydrogenated bisphenol A, polyoxyethylenated bisphenol A, and polyoxypropylenated bisphenol A, and other dihydric alcohol monomers. Examples of carboxylic acids include maleic acid, fumaric acid, mesaconic acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, succinic acid, adipic acid, sebacic acid, malonic acid, Examples include anhydrides of these acids, dimers of lower alkyl esters and linoleic acid, and other divalent organic acid monomers. As the polyester resin used in the present invention, it is preferable to use not only a polymer composed only of the above-mentioned bifunctional monomers but also a polymer containing a component composed of trifunctional or higher polyfunctional monomers. Examples of such polyfunctional monomers, such as trivalent or higher polyhydric alcohol monomers, include sorbitol, 1,2,
3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, sucrose, 1,
2,4-butanetriol, 1,2,5-pentanetriol, glycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane, 1,3,5 -trihydroxymethylbenzene, and others. In addition, as trivalent or higher polyvalent carboxylic acid monomers,
For example, 1,2,4-benzenetricarboxylic acid,
1,2,5-benzenetricarboxylic acid, 1,2,
4-cyclohexanetricarboxylic acid, 2,5,7
-Naphthalenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, 1,2,4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-
Mention may be made of methylenecarboxypropane, tetra(methylenecarboxyl)methane, 1,2,7,8-octanetetracarboxylic acid, Empol trimer acid, acid anhydrides thereof, and others. It is desirable that the above trifunctional or higher polyfunctional monomer component be contained in a proportion of 30 to 80 mol % in each of the alcohol component or acid component as a structural unit in the polymer. The polyester resin used in the present invention has a chloroform-insoluble content of 5% by weight or more.
The chloroform-insoluble content herein refers to the paper-insoluble content when a sample is dissolved in chloroform, and is determined as follows. Finely crush the resin sample, collect 5.00g of sample powder that passed through a 40-mesh sieve, and place it in a 150ml container with 5.00g of super-aiding agent Radiolite (#700), and inject 100g of chloroform into this container. death,
The sample was placed on a ball mill stand and rotated for 5 hours or more to sufficiently dissolve the sample in chloroform. On the other hand, place a piece of paper (No. 2) with a diameter of 7 cm in the pressurizer, pre-coat 5.00g of Radiolite uniformly on it, and add a small amount of chloroform to make the paper adhere to the pressurizer. , the contents of the container are poured into a strainer. Furthermore, thoroughly wash the container with 100 ml of chloroform and pour it into a filter to prevent any deposits from remaining on the walls of the container. Then, close the top lid of the strainer and carry out straining.
The filtration is carried out under a pressure of 4 kg/ ^cm2 or less, and after the chloroform has stopped flowing out, fresh chloroform is added.
Add 100 ml to wash the residue on the paper and perform pressure filtration again. After the above operations are completed, the paper, the residue on it, and the radiolite are all placed on aluminum foil and placed in a vacuum dryer at a temperature of 80 to 100℃.
Dry for 10 hours under a pressure of 100 mmHg, measure the total weight a (g) of the dried product thus obtained,
The chloroform insoluble content x (wt%) is determined by the following formula. x (weight%) = a (g) - paper weight (g) - radiolite weight (10.00g) / sampling weight (5.00g)
) × 100 The chloroform-insoluble content determined in this way is a high molecular weight polymer component or a crosslinked polymer component in the polyester resin,
Its molecular weight is believed to be approximately 200,000 or more. The proportion of the above-mentioned chloroform-insoluble components can be controlled to a considerable extent by appropriately selecting the reaction conditions or by making an appropriate crosslinking agent exist in the reaction system in the polymerization reaction between alcohol and carboxylic acid mentioned above. can be formed with. In the present invention, the polyester resin having a chloroform-insoluble content of 5% by weight or more is used as a binder, but if a polyester resin having a chloroform-insoluble content of less than 5% by weight is used, the resulting toner will have a low offset generation temperature. I end up. The first mold release agent contained in the toner of the present invention is carnauba wax and/or candelilla wax, and its penetration is 4 or less and the melting point is 60 to 60.
The temperature is 110℃. In the above, the wax penetration is JISK2235
- The value obtained in accordance with the test method specified in 1980. That is, the sample wax is heated and melted, placed in a sample container, left to cool, and then heated to a temperature of 25°C in a constant temperature water bath.
A needle with a total mass of 100g is maintained at a constant temperature of degree. Further, the melting point is determined by differential scanning calorimetry (DSC). That is, the melting point is defined as the melting peak value when several mg of a sample is heated at a constant temperature increase rate (10° C./min). Specific examples of the first mold release agent include those listed in Table 1.

[Table] The second release agent contained in the toner of the present invention is composed of an alkylene bis fatty acid amide compound represented by the above general formula, and representative examples include those represented by the following structural formula. can be mentioned.

〔Effect of the invention〕

As described above, in the toner of the present invention, the binder resin is composed of a polyester resin containing a high molecular weight component that is insoluble in chloroform above a certain level, and furthermore, the toner as described above is composed of the first mold release agent and the second mold release agent. Because it contains a mold release agent, as is clear from the description of the examples below, it has a low minimum fixing temperature, has sufficient mold release properties, and has excellent non-offset and non-rolling properties. It has excellent adhesion properties, good fluidity, and high durability.As a result, it is possible to produce excellent visible images with high image density at low fixing temperatures without the occurrence of offset or curling phenomena. Moreover, it can be stably formed many times at an even higher speed. Even when subjected to the development process in a recycling system, it has excellent durability and can stably obtain the above characteristics, and contamination of the carrier, electrostatic image support, and developer sleeve with toner is greatly reduced. . Although the reason why the toner of the present invention has such excellent properties as described above has not been strictly elucidated, it is believed that the following is a part of the reason. The binder resin itself has non-offset properties and can be fixed at low temperatures. The toner contains not only one type of release agent, but also both the first release agent and the second release agent, which have different characteristics.
If the release agent required for the toner is obtained only by the second release agent, the fluidity will be greatly reduced, and the low-temperature fixing property required for the toner will be obtained only by the second release agent. In this case, the disadvantage that each mold release agent exhibits a large decrease in mold release properties does not appear in this case, and the favorable effects of each of the first mold release agent and the second mold release agent are sufficient. As a result, excellent low-temperature fixing properties, high mold releasability, and high fluidity can all be stably obtained for a long period of time in the toner. Furthermore, the first mold release agent is carnauba wax and/or candelilla wax with a penetration level of 4 or less, which is itself hard and highly durable, making it especially suitable for recycling systems. In some cases, there is no deterioration of properties such as a decrease in fluidity, and since the first release agent is hard, the surface of the toner has high slipperiness and the fixing properties are improved. Furthermore, since the toner of the present invention has good fluidity even though it contains a release agent, it is not necessary to add a fluidity improver such as hydrophobic silica fine powder, or when it is necessary to add it. Even if it is added, only a small amount is sufficient, and therefore, adding a large amount of hydrophobic silica fine powder may cause harmful effects, such as damage to the surface of the electrostatic image support due to the high hardness of hydrophobic silica fine powder. This will not cause any problems such as being exposed. [Examples of the Invention] Examples of the present invention will be described below, but the present invention is not limited thereto. Note that "parts" represent parts by weight. The binder resin and mold release agent used in the following examples are as follows. [Binder resin] 1 Binder resin A 299 g of terephthalic acid, 211 g of polyoxypropylene (2,2)-2,2-bis(4-hydroxyphenyl)propane, and 82 g of pentaerythritol
g, thermometer, stainless steel stirrer,
Place it in a round bottom flask equipped with a glass nitrogen gas inlet tube and a flow-down condenser, set this flask on a mantle heater, and maintain an inert atmosphere inside the flask by introducing nitrogen gas through the nitrogen gas inlet tube. Polyester resin with a chloroform-insoluble content of 17% by weight and a softening point of 131°C [mold release] was obtained by raising the temperature at 17% by weight and a softening point of 131°C by adding 0.05 g of dibutyltin oxide and reacting at a temperature of 200°C while monitoring the reaction at the softening point. Agent] 1 Mold release agent a1 (first mold release agent) "Carnauba Wax No. 1" (manufactured by Noda Wax Co., Ltd.) 2 Mold release agent a2 (first mold release agent) "Cyandelilla Wax No. 1" (manufactured by Noda Wax Co., Ltd.) 2” (manufactured by Noda Wax Co., Ltd.) 3 Mold release agent b1 (second mold release agent) “Hexato Wax C” (manufactured by Hoechst Japan Co., Ltd.) 4 Mold release agent b2 (second mold release agent) “Bisamide” ( (manufactured by Nitto Kagaku Co., Ltd.) 5 Mold release agent C (for comparison) "Viscol 660P" (manufactured by Sanyo Chemical Co., Ltd., low molecular weight polypropylene wax) 6 Mold release agent d (for comparison) "Hoechst Wax OP" (manufactured by Hoechst Japan Co., Ltd.) , partially saponified product of butylene glycol ester of montanic acid) 7. Mold release agent e (for comparison) "Aramide HT" (manufactured by Lion Akzo, stearic acid amide) In each example and comparative example, materials of the indicated formulation were used. was kneaded in an extruder set at a temperature 10°C lower than the softening point of the binder resin, cooled (water-cooled), pulverized, and classified to obtain toner powder consisting of particles with an average particle size of 11 μm. A toner was produced by adding 0.8% by weight of hydrophobic silica fine powder to the toner. Example 1 Binder resin A 100 parts Mold release agent a1 2 parts Mold release agent b1 2 parts Carbon black "Mogal L" (manufactured by Cabot Corporation) 10 parts Example 2 Binder resin A 100 parts Mold release agent a1 2 parts Mold release agent b1 6 parts Carbon black "Mogul L" 10 parts Example 3 Binder resin A 100 parts Mold release agent a2 2 parts Mold release agent b2 2 parts Carbon black "Mogul L" 10 parts Comparative example 1 Binder resin A 100 parts Mold release agent a1 2 parts Carbon black "Mogal L" 10 parts Comparative example 2 Binder resin A 100 parts Mold release agent a1 4 parts Carbon black "Mogul L" 10 parts Comparative example 3 Binder resin A 100 parts Mold release agent b1 2 parts Carbon black " Comparative example of 10 parts of "Mogal L" 4 Binder resin A 100 parts Release agent b1 4 parts Comparative example of 10 parts of carbon black "Mogal L" 5 Comparative example of 10 parts of binder resin A 100 parts Release agent C 4 parts Carbon black "Mogal L" 10 parts Example 6 Binder resin A 100 parts Carbon black "Mogul L" 10 parts Comparative example 7 Binder resin A 100 parts Mold release agent a1 2 parts Mold release agent e 2 parts Carbon black "Mogul L" 10 parts Comparative example 8 Binder resin A 100 Part Mold release agent a2 2 parts Mold release agent e 2 parts Carbon black "Mogul" 10 parts Comparative example 9 Binder resin A 100 parts Mold release agent d 2 parts Mold release agent b1 2 parts Carbon black "Mogul L" 10 parts Comparative example 10 Binder resin A 100 parts Release agent c 2 parts Release agent b1 2 parts Carbon black "Mogal L" 10 parts The toners obtained in Examples 1 to 3 above were used as "Toner 1" to "Toner 3", respectively. ”, and the toners obtained in Comparative Examples 1 to 10 were designated as “Comparative Toner 1” to “Comparative Toner 10”, respectively, and as an index of fluidity for each of these toners, the powder particles with higher fluidity had higher Taking advantage of the small degree of compression, the sample was loosely packed into a container with a diameter of 28 mm and a volume of 100 ml from above through a 100 mesh sieve, and the weight was measured to determine the static bulk density. Further, each of the above toners and a carrier made of resin-coated iron powder are mixed to prepare a developer having a toner concentration of 2% by weight, and each of the toners is used to create an electrophotographic copying machine having a toner recycling system. Using "U-Bix4500" (manufactured by Konishiroku Photo Industry Co., Ltd.) under the environmental conditions of a temperature of 33°C and relative humidity of 80%, an electrostatic charge image is developed, a toner image is transferred to a transfer paper, and a heated roller fixes the toner image. A photocopying test using a fixing process using a device was conducted 60,000 times, and the initial image density of the resulting copied image and the image density after 60,000 copies were measured. In addition, the static bulk density of each toner after 60,000 copies was determined. After 60,000 copies, the degree of toner contamination on the surface of the carrier, the surface of the photosensitive drum, and the surface of the developing sleeve was examined. Furthermore, for each toner, the minimum fixing temperature offset occurrence temperature and curling occurrence temperature were determined. Regarding the minimum fixing temperature, we used a heated roller whose surface layer was made of Teflon (polytetrafluoroethylene manufactured by Dupont) and a heated roller whose surface layer was made of silicone rubber "KE-".
1300RTV" (manufactured by Shin-Etsu Chemical Co., Ltd.), the toner image of the sample toner was transferred onto a 64 g/ ^m2 transfer paper and was fixed at a high linear speed of 200 mm/sec. , the set temperature of the heat roller was raised stepwise by 5 degrees Celsius from 100 degrees Celsius, and Kimwibe rubbing was applied to the formed fixed image. The set temperature was taken as the minimum fixing temperature. Note that the fixing device used here does not have a silicone oil supply mechanism. In addition, to measure the offset occurrence temperature, the toner image is transferred and fixed by the above-mentioned fixing device, and then a blank transfer paper is sent to the fixing device under the same conditions. The operation of observing whether or not toner stains occur was repeated while the set temperature of the heat roller of the fixing device was successively increased, and the temperature at which offset occurred was determined. In addition, using a so-called solid black original, the set temperature of the heat roller of the fixing device was successively lowered in accordance with the measurement of the offset generation temperature described above, in order to fix the toner on almost the entire surface of the transfer paper. The temperature at which winding occurs was determined by repeating this condition. The results are shown in Table 2.

[Table] As is clear from the results in Table 2, the toner of the present invention has a high offset generation temperature and excellent non-offset properties, and a low curl generation temperature and excellent non-coiling properties. Furthermore, the minimum fixing temperature is low and excellent low-temperature fixing properties are obtained.
Moreover, it has good fluidity and high durability.
Even after 10,000 copies, excellent properties are maintained, contamination by toner is small, and excellent visible images can be stably formed many times at high speed. On the other hand, Comparative Toners 1 and 2 contained only the first releasing agent, and therefore had poor fluidity and image density. Comparative toners 3 and 4 contain only the second release agent, so the minimum fixing temperature is high and the non-wrapping property is poor. According to Comparative Toner 5, since the releasing agent contained is a low molecular weight polypropylene wax, the minimum fixing temperature and the wrapping temperature are high, and furthermore, contamination by toner is observed and durability is low. Furthermore, since Comparative Toner 6 does not contain any release agent, the minimum fixing temperature is considerably high, the temperature at which curling occurs is high, and the non-rolling property is poor.

Claims (1)

[Scope of Claims] 1. A binder resin made of a polyester resin containing chloroform-insoluble content of 15% by weight or more;
A toner for developing an electrostatic image, comprising carnauba wax and/or candelilla wax and a release agent made of an alkylene bis fatty acid amide compound represented by the following general formula. general formula [In the formula, R ₁ and R ₂ are each the same or different saturated or unsaturated aliphatic hydrocarbon groups having 10 or more carbon atoms, and R ₃ and R ₄ are each the same or different hydrogen atoms or -OCR ₅ groups (However, R ₅ represents a saturated or unsaturated aliphatic hydrocarbon group.)
, and n represents a positive integer. ]