JPS6261142B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a toner used in electrophotography, electrostatic recording, magnetic recording, electrostatic printing, etc., and particularly relates to a capsule toner suitable for pressure fixing and a method for producing the capsule toner. Conventionally, as an electrophotographic method, U.S. Patent No. 2297691
No. 2825814, No. 3220324, No. 3220324, No.
3220831, Special Publication No. 42-23910 and Special Publication No. 43
Many methods are known, as described in Japanese Patent No. 24748, etc., but in general, a photoconductive substance is used to form an electrical latent image on a photoreceptor by various means, and then the A latent image is developed using toner, and after the toner image is transferred to a transfer material such as paper as necessary, it is fixed by heat, pressure, solvent vapor, etc. to obtain a copy. Various methods are also known for visualizing electrical latent images using toner. For example, the magnetic brush method described in US Pat. No. 2,874,063, the cascade development method described in US Pat. No. 2,618,552, and US Pat. No. 2,221,776
The powder cloud method described in the specification of the same No.
A large number of development methods are known, such as the touchdown development method described in No. 2895847, the furbrush development method, and the liquid development method. As toners used in these developing methods, fine powders in which dyes or pigments are dispersed in natural or synthetic resins have conventionally been used. Furthermore, it is also known to use fine developing powder to which a third substance is added for various purposes. The developed toner image is transferred and fixed onto a transfer material such as paper, if necessary. Methods for fixing toner images include a method in which the toner is heated and melted using a heater or a heated roller, and then fused and solidified on the support, a method in which the binder resin of the toner is softened or dissolved with an organic solvent and then fixed on the support, and a method in which the toner is fixed on the support by applying pressure. A method of fixing toner on a support by using a method is known. Toner materials are selected to be suitable for each fixing method, and toners used for a particular fixing method generally cannot be used for other fixing methods. especially,
It is almost impossible to transfer the toner used in the conventionally widely used heat fusion fixing method using a heater to a hot roller fixing method, a solvent fixing method, a pressure fixing method, or the like. Therefore, toners suitable for each fixing method are being researched and developed. The method of fixing toner by applying pressure is based on US Patent No.
It is described in specification No. 3269626, Japanese Patent Publication No. 46-15876, etc., and is energy saving, non-pollution, copying can be done without waiting time when the copier is turned on, there is no risk of burning copies, and high speed. It has many advantages such as being able to be fixed and having a simple fixing device. However, there are problems with toner fixability, off-cut phenomena on the pressure roller, paper wrapping around the pressure roller, etc., and various research and developments are being carried out to improve the pressure fixability. For example, Japanese Patent Publication No. 44-9880 describes a pressure fixing toner containing an aliphatic component and a thermoplastic resin;
No. 48-78931, No. 49-17739, No. 52-
No. 108134 describes a capsule-type pressure fixing toner containing a soft material in the core, and JP-A-48-75033 describes a pressure fixing toner using a block copolymer of a tenacious polymer and a soft polymer. The fixing toner is listed. However, the pressure fixing performance is sufficient and there is no offset phenomenon or paper wrapping around the pressure roller.
It has stable developing performance and fixing performance even after repeated use, does not cause adhesion to the carrier, metal sleeve, or photoreceptor surface, and has good storage stability that does not cause aggregation or caking during storage.Practical. A pressure fixing toner that is fully satisfactory in terms of surface area has not yet been obtained. For example, a pressure fixing toner made of a soft material has good pressure fixing properties, but it is difficult to finely pulverize into a toner, tends to cause offset phenomenon to the pressure roller, and also There are many problems such as easy adhesion to particles, agglomeration and cake formation during storage. In addition, in various conventional pressure fixing capsule toners, if a soft material with good pressure fixing properties is used as the core material, the soft material gradually adheres to the pressure roller as pressure fixing is repeated. In the end, offset and wrapping of the transfer paper occur, and the fixing performance varies widely, so that a capsule toner that is always stable and that is practically satisfactory has not yet been obtained. Furthermore, recently, a method has been used in which electrostatic latent images are developed using a one-component developer that contains magnetic fine particles in the toner and does not use carrier particles, but in this case, the toner binding resin contains magnetic fine particles. The toner is required to have good dispersibility and adhesion with the toner, as well as impact resistance and fluidity, and it is extremely difficult to achieve both this and the pressure fixing performance. The present invention provides a pressure fixable capsule toner with stable performance without the above-mentioned drawbacks by limiting the thickness of the shell material depending on the hardness of the core material, and a method for producing the pressure fixable capsule toner. It is something to do. The present invention provides a pressure-fixing capsule toner that has extremely good and stable fixing properties under pressure on plain paper, and further has stable developing performance and fixing performance even when copying a large number of sheets, and a method for producing the same. It provides: Furthermore, the present invention provides a pressure-fixable capsule toner that does not cause offset to a pressure roller and does not cause adhesion to a carrier, a developing sleeve, or a photoreceptor surface, and a method for producing the same. Furthermore, the present invention provides a pressure-fixable capsule toner with excellent storage stability that does not aggregate or form cakes during use or storage, and a method for producing the same. Furthermore, the present invention provides a pressure-fixable capsule toner that has good chargeability, always exhibits stable chargeability during use, and provides clear, fog-free images, and a method for producing the same. Furthermore, even when the present invention contains magnetic fine particles and is used as a magnetic toner for one-component developer or magnetic recording, it exhibits good pressure fixing properties, good magnetism, and electrostatic transferability. The present invention provides a pressure-fixable capsule toner and a method for producing the same. Further, the present invention provides a pressure-fixable capsule toner having excellent durability and fluidity, and a method for producing the same. That is, the present invention provides a pressure-fixable capsule toner in which pressure-fixable core material particles are coated with a film material, in which the main particle size of the capsule toner is a μm,
Assuming that the main particle size of the core material particles is bμm and the hardness of the core material is y (JIS-K2530, unit dmm), the capsule toner has the following formula: 0.01exp (23a-b/b)≦y≦5exp (60a-b/ An object of the present invention is to provide a pressure-fixable capsule toner that satisfies the following relational expression b) [wherein y is 0.5 to 75 and a-b/b is 0.04 to 0.35]. Furthermore, the present invention provides a method for manufacturing a pressure fixable capsule toner by coating pressure fixable core material particles with a film material, in which a core material having a hardness y (JIS-K2530, unit: dmm) is used. Generate material particles and classify the generated core material particles to obtain main particle size b
A core material particle having a diameter of μm is prepared, and the prepared core material particle is coated with a coating material to form the following relational expression:
0.01exp(23a-b/b)≦y≦5exp(60a-b/b) [where a is the main particle size of the capsule toner a μm
, y is 0.5 to 75, and a-b/b is 0.04 to 0.35. ] An object of the present invention is to provide a method for producing a pressure-fixable capsule toner, which is characterized by forming a capsule toner that satisfies the following. In pressure fixable capsule toner, the performance of the capsule toner is influenced by the selection of materials for the core material that exhibits pressure fixability and the shell material that improves chargeability, fluidity, etc., but the hardness of the core material, It has been found that the main particle size, wall thickness, etc. are closely related to each other, and that it is particularly important for pressure-fixable capsule toners to satisfy these favorable relationships. That is, when manufacturing capsule toner, a core material with good pressure fixability and a shell material with good chargeability, fluidity, etc. are used, and the ratio of core material particles to shell material is taken into consideration. However, it was not always possible to obtain a capsule toner with stable performance. The reason for this is the distribution of the particle size of the core material particles.
Since the finished capsule toner also has a particle size distribution, each particle of the capsule toner does not necessarily have a favorable ratio of core material to shell material. This is because the thickness is not obtained. Therefore, even if the finished capsule toner is simply classified to have a uniform particle size distribution, it is not necessarily possible to obtain a capsule toner with stable performance. In order to obtain a capsule toner with always stable pressure fixability, chargeability, fluidity, etc., the particle size distribution of the core material particles and the particle size distribution of the capsule toner must be carefully controlled, and then the hardness of the core material and the particle size distribution of the capsule toner must be carefully controlled. It was found that it is necessary to control the thickness of the shell material so that it has a certain relationship depending on the main particle size of the shell material. Although it is conceivable to simply control the thickness of the shell material according to the hardness of the core material, in that case, it is difficult to obtain an appropriate thickness of the shell material corresponding to the main particle size of the core material particles. In other words, when the main particle size is large, the thickness is slightly insufficient, and when it is small, the thickness is slightly excessive. In order to compensate for such differences in main particle size, it is preferable to control the ratio of core material particles to shell material particles. Depending on the hardness of the core material, performance can be stabilized by controlling the ratio between the core material particles and the shell material, or more practically, the ratio between the particle size of the core material particles and the thickness of the shell material. That is, after appropriately controlling the particle size distribution of the core material particles and capsule toner, as described above, the main particle size of the capsule toner is a μm, the main particle size of the core material particles is b μm, and the hardness of the core material is y.
(JIS-K2530, unit dmm) is 0.01exp
(23a-b/b)≦y≦5exp (60a-b/b) Particularly preferably, the relational expression 0.03exp (27a-b/b)≦y≦3exp (47a-b/b) [where y is 0.5 to 75, and ab/b is 0.04 to 0.35. ] It has been found that a pressure-fixing capsule toner with stable performance can be obtained by controlling it to satisfy. That is, when we conducted experiments using core materials with various hardnesses (y dmm) and varying the ratio of core material particles to shell materials (i.e., the thickness of the capsule toner shell), we found that the above equation A range of capsule toners have been found to exhibit stable performance. However, in order to form a shell, from a practical standpoint, a-b generally needs to be 0.01 μm or more, preferably 0.02 μm or more. Particle size distribution control of core material particles and capsule toner involves controlling the main particle size, which means the particle size that accounts for the largest number of particles within the particle size distribution, and the particle size distribution width of individual particles from the main particle size. It depends. The number of particles of a certain particle size is measured using a particle analyzer. That is, an optically magnified image of the particle group to be measured is converted into a video signal by a television camera, this image information is sent to a threshold circuit, converted into binary image information, and further sent to a counting circuit. The counting circuit measures the particle diameter and number of particles using the television scanning line and points obtained by subdividing the scanning line. Examples of particle analyzers include LUZEX 450 manufactured by Nippon Regulator Co., Ltd. When manufacturing capsule toner by manufacturing core material particles and then coating them with a shell material, the core material particles are classified in advance within the range of the main particle size ±3 μm, and then the shell material particles are coated. It is particularly preferable to classify the capsule toner after it is completed so that 70% (number) or more of the capsule toner has a main particle size of ±3 μm. However, if the particle size distribution can be set within a preferable range by appropriately determining the manufacturing conditions, there may be cases in which there is no need for classification by strictly defining the manufacturing conditions. JISK2530 is the standard for expressing the hardness of the core material.
Use the stated penetration. This is because the needle has a certain shape.
It is expressed in 0.1 mm increments as the depth of penetration under a constant load at a constant temperature in a constant time, and is measured using a penetrometer, which is a type of material testing machine. In the above relational expression, if the value of (a-b)/b deviates from the specified range with respect to the hardness of the core material, the chargeability and fluidity of the capsule toner will deteriorate; Aggregation causes decreased storage stability and durability. On the other hand, if it deviates to a larger extent, the pressure fixing properties will be extremely poor even if the chargeability and fluidity can be maintained. Next, in the present invention, as the pressure fixing component used for the core material, the material conventionally used for the core material of pressure fixing capsule toner is appropriately used. or those that exhibit tackiness at room temperature and pressure, such as soft material tackifiers, may be used alone or in combination. In short, any material that exhibits pressure fixing properties can be used; for example, Japanese Patent Publication No. 44-9880, Japanese Patent Application Laid-open No. 48-7503
No. 48-78931, No. 49-17739, No. 52-
Many of those described in No. 108134 and No. 48-75033 can be used. Particularly preferred are higher fatty acids (stearic acid, palmitic acid, lauric acid, etc.), polyolefins (low molecular weight polyethylene, low molecular weight polypropylene, oxidized polyethylene, polytetrafluoroethylene, etc.), low molecular weight polystyrene, epoxy resins, polyester resins ( (acid value 10 or less), polyamide resin, styrene-butadiene copolymer (monomer ratio 5-30:95-70), ethylene-acrylic acid copolymer, ethylene-methacrylic acid copolymer, ethylene-vinyl acetate copolymer , polyvinylpyrrolidone, methyl vinyl ether-maleic anhydride copolymer, maleic acid-modified phenolic resin, phenol-modified terpene resin, and the like. In addition, various resins can be used as the outer shell material, including those that are insulating and have good film-forming ability, those that have good positive or negative chargeability, and those that have good fluidity and non-agglomeration. Particularly preferred are those that do not inhibit the pressure fixing properties of the core material. for example,
Polystyrene, poly-p-chlorostyrene, polyvinyltoluene, styrene-butadiene copolymer, styrene-acrylic acid copolymer, styrene-
Polymers or copolymers of styrene or its substituted products such as anhydrous maleic copolymers, polyester resins,
Acrylic resin, xylene resin, polyamide resin, ionomer resin, furan resin, ketone resin, terpene resin, rosin, rosin-modified pentaerythritol ester, natural resin-modified phenolic resin, natural resin-modified maleic acid resin, coumaron indene resin, alicyclic resin Group hydrocarbon resins, petroleum resins, cellulose acetate phthalate, starch graft polymers, polyvinyl butyral, polyvinyl alcohol, and the like can be used alone or in combination. In particular, styrene resins, polyester resins, ionomer resins, cellulose acetate phthalate, starch graft polymers, polyvinyl butyral, and the like having an average molecular weight of 1500 or more are preferred. If the affinity and adhesion between the core material particles and the shell material are poor, an intermediate adhesive layer may be provided. Further, an appropriate amount of a charge control agent such as a metal-containing dye or nigrosine conventionally used in toners may be added to the insulating material for the outer shell. Furthermore, charge control agent fine particles are mixed with the toner (external addition).
It can also be used as In the capsule toner of the present invention, dyes, pigments, etc. conventionally used as colorants for toners can be used, if necessary, and may be added to one or both of the core particle and the outer shell. Furthermore, if it is desired to obtain a magnetic toner, magnetic fine particles may be added to the toner. The magnetic substance may be any material that exhibits magnetism or can be magnetized, such as iron,
Conventionally known magnetic materials can be used, such as fine metal powders such as manganese, nickel, cobalt, and chromium, various ferrites, alloys and compounds of manganese, and other ferromagnetic alloys. These magnetic fine particles may be added to either the core material particles or the shell material, but in the case of obtaining an insulating toner, it is preferable to add them to the core material particles. The image obtained with the capsule toner of the present invention is fixed by passing between a pair of pressure-loaded rollers, but auxiliary heating may be performed. The applied pressure is generally about 10-30 kg/cm.
Regarding the pressure fixing device, Japanese Patent Publication No. 44-12797,
U.S. Patent No. 3269626, U.S. Patent No. 3612682, U.S. Patent No.
It is described in No. 3655282, No. 3731358, etc. The present invention will be specifically explained below using examples.
Parts in the examples are parts by weight. Examples 1 to 3 Polyethylene oxide (density 0.99,
100 parts of carbon black (penetration: 0.5) and 10 parts of carbon black were thoroughly kneaded at about 150°C for 30 minutes using a roll mill. This material was made into a fine powder using a pulverizer such as a cutter mill or a jet mill. The main particle size of the fine powder core material particles was 14.5 μm. This powder was classified so that 90% or more of the particles had a diameter of 14.5±3 μm. Next, the particles were sufficiently dispersed in a 10% cyclohexane solution of the styrene-butadiene copolymer and dried using a spray dryer to obtain a capsule toner containing the styrene-butadiene copolymer as grain. The main particle size of this capsule toner is 15.2μ
It was hot. 10 parts of this capsule toner was mixed with 90 parts of iron powder carrier (manufactured by Nippon Steel Powder Co., Ltd., trade name: EFV200/300) to prepare a developer. This developer was put into the developing device of a dry type electronic copying machine (manufactured by Canon, product name NP-5000), and the fixing device was connected to the fixing roller (upper and lower rollers with a total pressure of 460 kg).
Continuous copying was performed by replacing the book's chrome-plated rigid roller. As a result, a clear image with good fixability and no fog was obtained. Furthermore, continuous copying was continued and 30,000 copies were made, and copies were obtained that were comparable in image quality and fixability to the initial images. The fixability test result was 5th to 6th grade. The fixability was evaluated according to the dye fastness test method against friction (JIS-L0849-1971). That is, using a friction tester, the toner fixing surface and a white cotton cloth for friction were rubbed against each other according to a prescribed method (drying test), and the degree of coloring of the white cotton cloth for friction was compared with the gray scale for contamination. The fixability was evaluated using grades. In the above example, fixability and durability were tested by varying the thickness of the grain. The results were as shown in Examples 2 and 3 and Comparative Examples 1 and 2 in Table 1. Examples 4 to 6 The same procedure as in Example 1 was repeated except that the core material was low molecular weight polyethylene (penetration 3.5) (trade name: AC-6, manufactured by Allied Chemical). The main particle size of the core material particles was 16.0 μm, and the pressure fixability and durability were tested with various grain thicknesses. The results were as shown in Examples 4 to 6 and Comparative Example 3 in Table 1. Examples 7 to 9 The same procedure as in Example 1 was repeated except that the core material was polyethylene (penetration 7.5) (trade name: AC-617, manufactured by Allied Chemical). The main particle size of the core material particles is 18.0μm, and the results of testing the pressure fixability and durability with various grain thicknesses are shown in Table-
The results were as in Examples 7 to 9 and Comparative Example 4 in No. 1. However, some cooling operation was required during pulverization of the core material. Examples 10 and 11 A urea formaldehyde initial condensate was prepared in the following manner. Mix 20 parts of urea and 55 parts of 37% formalin to 10%
Add ethanolamine to adjust pH to 8.0 and heat to 70°C.
Stirring was carried out at a temperature of 25 hours to obtain a transparent urea-formaldehyde initial condensate with a slightly increased viscosity. 24 parts of this initial condensate was dissolved in 180 parts of water, and while stirring, ethylene-vinyl acetate copolymer (manufactured by Allied Chemical Co., Ltd., AC-430, penetration
A warm 60% toluene solution of 75) was emulsified and dispersed. Next, add citric acid to this system in 2 to 3 parts, and
The pH was adjusted to around 3.5, stirring was continued for about 6 hours while maintaining the temperature at 45 to 50°C, and the mixture was left to stand overnight. The obtained precipitate was thoroughly washed with water and dried to obtain core material particles.
Most of the toluene contained in the core had already been lost during the long-term encapsulation process, and the core had essentially become a solid core. Penetration degree 75, main grain size
It was 13μ. Next, a grain material layer of styrene-butadiene copolymer was provided on the capsule particles in the same manner as in Example 1, and the same fixability and durability tests were conducted. The results are shown in Table-1.

【table】

[Table] Examples 12 to 33, Comparative Examples 7 to 18 In Examples 1 to 11 and Comparative Examples 1 to 6, cellulose acetate phthalate (reagent manufactured by Wako Pure Chemical Industries, Ltd.) was used as the grain material.
(Used as an acetone solution) and styrene-maleic anhydride-butyl acrylate copolymer (monomer ratio 50/15/35wt%) (Daido Kogyo, Stylite The results were almost the same as those for styrene-butadiene copolymer. Example 34, Comparative Examples 19 and 20 Ethylene-vinyl acetate copolymer (manufactured by Allied Chemical Co., Ltd., AC401, penetration 4.0) was used as the core material, and styrene-butadiene copolymer (monomer ratio 15/15) was used as the grain material. 85 wt%) (used as a methyl ethyl ketone solution), a capsule toner was prepared by changing the thickness of the grain in the same manner as in Example 1, and used as a developer. As shown in Table 2, the results were clearly superior in quality to the comparative example.

【table】

Claims (1)

[Scope of Claims] 1. In a pressure fixable capsule toner in which pressure fixable core material particles are covered with a film material, the main particle size of the capsule toner is a μm, the main particle size of the core material particles is b μm, and the core material The hardness of y (JIS-
K2530, unit dmm), the capsule toner is 0.01exp (23a-b/b)≦y≦5exp (60a-b/
b) A pressure-fixable capsule toner, characterized in that it satisfies the following relational expression: where y is 0.5 to 75, and a-b/b is 0.04 to 0.35. 2. In a method for producing a pressure fixable capsule toner by coating pressure fixable core material particles with a coating material, the core material particles are produced from a core material having a hardness y (JIS-K2530, unit dmm). , the generated core material particles are classified to prepare core material particles having a main particle size b μm, and the prepared core material particles are coated with a coating material to form the following relational expression, 0.01exp (23a-b/b) ≦y≦5exp(60a-b/b) [where a is the main particle size of the capsule toner aμm
, y is 0.5 to 75, and a-b/b is 0.04 to 0.35. ] A method for producing a pressure-fixable capsule toner, characterized by forming a capsule toner that satisfies the following.