JPH024896B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a toner for developing electrostatic images, and more particularly to a microcapsule type toner that can be suitably used as a pressure fixing type toner. [Prior Art] In recent years, an electrostatic charge image is formed based on image information using electrophotography, electrostatic printing, electrostatic recording, etc., and this is developed with a developer toner to form a toner image. It is widely practiced to form a visible image by transferring this toner image onto a transfer paper or the like and then fixing it. Conventionally, as an electrostatic image developer toner, a powdered toner obtained by finely pulverizing a thermoplastic resin as a binder and a coloring agent such as carbon black dispersed therein has been widely used. If it is a two-component toner, it can be mixed and stirred with a carrier such as iron powder or glass beads.
If the toner is a one-component toner containing fine magnetic powder, it can be triboelectrified by stirring itself, and the electrostatic force can be used to develop an electrostatically charged image, resulting in a toner image. For example, after being transferred, the image is heated and fixed using a heating roller or the like. However, in such toners, the toner particles are crushed during agitation for triboelectric charging, producing fine powder toner, resulting in poor visible image quality or the need to replace the toner with a new one prematurely. In addition, since fusing is achieved by a heat fusing method, a long waiting time is required for the temperature of the fuser to rise to the required set temperature, and This requires a large amount of energy and can even cause a fire if a paper jam occurs.
Moreover, in order to achieve reliable fixing, it is necessary to satisfy fairly strict conditions regarding temperature conditions and the like. Under these circumstances, a method of fixing using pressure has been proposed. That is, a pressure fixing method has been proposed in which toner particles are fixed to an image forming support by applying pressure to the toner, and for example, the method described in US Pat. No. 3,269,626 is known. Since this method does not require the use of heat or solvent, it has the advantage that it does not cause various problems, does not require warm-up time, and requires less energy for fixing. However, the above-mentioned pressure fixing method has poor fixing properties compared to fixing methods using heat, etc., and is easily peeled off when rubbed, and requires high pressure, which may destroy the fibers of the image forming support, such as copy paper. There were disadvantages such as the paper becoming weak and the surface of the copy paper becoming excessively glossy. In order to solve these drawbacks, research has recently begun on the use of so-called microcapsules as toners for developing electrostatic images. This microcapsule type toner is a powder type toner in which a liquid substance or soft solid exhibiting pressure fixability and a colorant are enclosed as core materials in fine particle resin capsules. This microcapsule type toner can encapsulate sticky soft solids in the core material.
Compared to conventional pressure fixing toners made of a single resin, this toner is expected to have advantages such as good powder characteristics, fixing at low pressure, and no agglomeration or blocking during toner production or storage. However, conventional microcapsule toners have various drawbacks. For example, JP-A-54-76233 discloses that the outer wall of a microcapsule toner is formed from a polyamide resin, but because the outer wall has low strength, it is difficult to isolate the toner particles during production. The drying process required to form a powder must be carried out by spray drying, and vigorous stirring must be avoided, making it impossible to obtain a sufficient amount of charge, and therefore the visible image formed is The image density tends to be low. Furthermore, the polymerization reaction of the polymer that forms the capsules of this toner must be carried out at high temperatures, and when magnetic fine powder is contained in the magnetic toner, the polymerization reaction of the polyacid chloride contained together in the particles must be carried out. The hydrochloric acid produced will attack the magnetic material, and the desired properties will be sacrificed. Further, the same publication describes a microcapsule type toner having an outer wall made of epoxy resin, but it has the drawback that the reaction time is long because the reaction rate of the epoxy resin is slow. moreover,
JP-A-57-179860 describes a microcapsule type toner having an outer wall made of polyurethane resin or polyurea resin. This technique has the advantage that the outer wall can be formed quickly, but has the disadvantage that the strength of the wall material increases and the pressure required for fixing increases. Furthermore, since the outer wall is hard, it has no effect on fixing properties.
The disadvantage is that it merely protects the inside, and it actually degrades the fixing performance. Furthermore, there is a drawback that it is difficult to control the amount of charge. As described above, conventional microcapsule type toners have various problems in terms of their physical properties and manufacturing, and at present, they have not been practically desirable. [Object of the Invention] The present invention has been made based on the above-mentioned circumstances, and its first purpose is to provide flexibility to the outer wall and not only protect the core material but also provide fixation ability to the outer wall itself. An object of the present invention is to provide a microcapsule type toner that is imparted with the following properties. A second object of the present invention is to provide a microcapsule type toner that has high capsule strength, is less prone to agglomeration, and is easy to manufacture. A third object of the present invention is to provide a microcapsule type toner whose charge can be easily controlled. [Configuration of the Invention] The microcapsule type toner of the present invention is characterized in that it has an outer wall made of at least an epoxyurea resin or a substance containing an epoxyurea resin. The present invention will be explained in detail below. The microcapsule type toner of the present invention is composed of an outer wall and a core material. The outer wall has the above structure, and the core material contains a pressure fixing substance and a coloring agent. Note that the coloring agent may be contained in the outer wall instead of the core material, or may be contained in both the core material and the outer wall. The material constituting the outer wall in the present invention contains at least epoxyurea resin or epoxyurethane resin. The above resin may be a 100% polymer in this material, or may be a partial polymer rather than a 100% polymer, or it may be present in a mixed form in this material. good. The above substance can be obtained as follows.
That is, it is obtained by reacting a mixture of a polyvalent isocyanate compound, which is a raw material for urea and urethane resins, and an epoxy resin prepolymer or a compound having an epoxy group, which is a raw material for epoxy resins, with a polyvalent amine compound. That is, a urea bond is generated by a reaction between an isocyanate and an amine, and an epoxy ring is opened by a reaction between an epoxy resin prepolymer or a compound having an epoxy group and an amine. Therefore, it is thought that a substance with the following structure is produced in the outer wall. (R, R', and R'' each represent a divalent bonding group.) Additionally, it may exist in the form of a mixture of urethane or urea resin and epoxy ring-opening polymer. The outer wall is made of the material obtained by the process, and it is made into a capsule shape.As the polyvalent isocyanate for obtaining the resin contained in the material that forms the outer wall, for example, the following are preferred. (1) Hexamethylene diisocyanate OCN (CH ₂ ) ₆ OCN Commercial product: “Sumidyur H” manufactured by Sumitomo Bayer Urethane Co., Ltd. (2) Commercially available product: "Sumiyur N" manufactured by Sumitomo Bayer Urethane (3) Metaphenylene diisocyanate

[Formula] Commercial product: "Naphconate" manufactured by National Aniline (4) Toluylene diisocyanate

[Formula] and

〔Effect of the invention〕

When developing an electrostatic charge image, stirring causes frictional charging, but since the outer wall of the toner is made of epoxyurea or epoxyurethane resin, which has great resistance to friction, the stirring is not necessary. Even if it is vigorously applied, it will not be crushed, and therefore a sufficient amount of charge can be retained, and as a result, a visible image with sufficiently high image density can be formed. In addition, the outer wall is made of epoxyurea resin or epoxyurethane resin, and the resin is not affected by moisture, and therefore maintains its fluidity as a powder for a long period of time and does not aggregate. When used as an electrostatic image developer toner, visible images of good quality can be stably formed. Further, the toner of the present invention is easily torn by a pressure roller with a linear pressure of, for example, 10 to 30 kg/cm, although it varies depending on the thickness of its outer wall, particle size, etc. By using a pressing roller, it is possible to easily fix the toner image formed by the toner onto a supporting paper, for example, a transfer paper. That is, when the capsule is ruptured, the core material sealed inside is released, but since this core material is a pressure-fixable material containing a colorant, it has sufficient visibility and Because pressure is applied to areas that have fluidity or plasticity, the pressure-fixing substance enters or is pushed between the fibers of paper such as transfer paper and is trapped, resulting in the toner Adequate fusing is achieved without image disturbance, ie without sacrificing resolution. In addition, since the outer wall is not a rigid polymer but an epoxyurea or epoxyurethane resin that has a certain degree of elasticity,
There is no deterioration in fixing performance due to the outer wall, no fixing failure occurs, and for example, after fixing, an image can be obtained that does not come off easily even if rubbed with a finger, paper, eraser, etc. The advantages of the microcapsule type toner of the present invention have been described above, but in addition to the above, the following effects can be obtained. That is, since the outer wall of the microcapsule type toner according to the present invention is made of a strong epoxyurea resin or epoxyurethane resin, it can be isolated from a state dispersed in a liquid and made into a powder. If necessary, drying methods other than the usual drying methods can be used without any particular adverse effects. In addition, the production of the microcapsule type toner of the present invention may be carried out using the interfacial polymerization method, which is a type of suspension dispersion polymerization method as described above (the components in the particles and the components in the dispersion medium are separated at the interface of the suspension dispersion particles). This can be carried out very advantageously, that is, easily and at low cost, by using a method in which a resin film is formed by a polymerization reaction. In this method, inexpensive water can be used as a dispersion medium without any danger, and the particles obtained are essentially spherical, with high fluidity, which is one of the important physical properties for electrophotography. Toner can be manufactured reliably. [Examples] Examples of the present invention will be described below, but the present invention is not limited to these. Example 1 50 g of liquid polybutene (HV-35, manufactured by Nippon Petrochemical Co., Ltd.) as a substance contained in the core material Exemplary compound (6) of polyvalent isocyanate (reaction product of toluylene isocyanate and trimethylolpropane), (Sumidyur) L-75, manufactured by Sumitomo Bayer Urethane Co., Ltd.) 25g Bisphenol A type epoxy resin (Epicoat
819, manufactured by Yuka Ciel Epoxy Co., Ltd.) 25 g Magnetic powder (BL-520, manufactured by Titan Kogyo Co., Ltd.) 100 g or more of the substances were mixed and stirred for about 1 hour using a sand grinder to mix and disperse, to obtain a magnetic ink. Separately, colloidal tricalcium phosphate 14 prepared from trisodium phosphate and calcium chloride
g, sodium dodecylbenzenesulfonate 0.06
Prepare a dispersion liquid by uniformly dispersing g in 800 ml of water.
Next, the above-mentioned magnetic ink was added to this dispersion liquid using a TK homogeator (manufactured by Tokushu Koki Kogyo Co., Ltd.) at a rotation speed of 8000 to 9000 rpm under optical microscope observation.
The oil was dispersed for about 10 minutes to form oil droplets of ~20μ. Next, transfer to a 4-necked flask in Step 2, and add 10 g of xylylenediamine and 10 g of Epicure T (manufactured by Yuka Ciel Epoxy Co., Ltd.) under low-speed stirring (approximately 200 rpm).
150 ml of an aqueous solution in which was dissolved was added over about 30 minutes at room temperature. The mixture was stirred at room temperature for 1 hour, and then the temperature was gradually raised to 80° C. for 7 hours to react, yielding microcapsules consisting of an epoxy polymer and a urea polymer. The mixture was then cooled, 40 ml of concentrated hydrochloric acid was added to decompose and remove the dispersion stabilizer tricalcium phosphate, filtered, washed with water and dried to obtain the microcapsule type toner of the present invention. This toner will be referred to as "Toner 1". Examples 2 to 18 The microcapsule type of the present invention was prepared in the same manner as in Example 1 using the substances listed in Table 1 as isocyanate, epoxy group-containing compound, core material-containing substance, magnetic powder, and amine compound. Got toner. The respective toners are designated as "toner 2" to "toner 18".

【table】

[Table] Comparative Example 1 A microcapsule toner having an outer wall composed solely of polyurea resin was synthesized in the same manner as in Example 1 described in JP-A-57-179860. This toner is referred to as "comparison toner 1." Comparative Example 2 A microcapsule toner having an outer wall composed solely of an epoxy polymer was synthesized in the same manner as in Example 17 described in JP-A-54-76233. This toner is referred to as "comparison toner 2." Comparative Example 3 100 parts of ethylene/vinyl acetate copolymer and magnetic powder
A toner was obtained by melting, kneading, and pulverizing 100 parts of BL-100. This toner will be referred to as "Comparison Toner 3." Example 19 Regarding “Toner 1” to “Toner 18” and “Comparative Toner 1” to “Comparative Toner 3” obtained above,
Frictional charge amount with conductive amorphous iron powder, environmental test (50
℃, humidity 80%, left for 10 hours), volume resistivity, and surface condition were examined. The results are shown in Table-2. In addition, in the environmental test evaluation, ○ indicates that no blocking etc. are observed and the same graininess as at the time of manufacture is maintained, and △ indicates that there is some blocking etc. but the graininess is almost the same as at the time of manufacture. If you have sex,
An x mark indicates a case where blocking etc. are significant and graininess during production is not observed, and a mark with two marks indicates an intermediate evaluation of each evaluation.

【table】

[Table] Example 20 Using the above "Toner 1" to "Toner 18" and "Comparison Toner 1" to "Comparison Toner 3", U-Bix10
(manufactured by Konishiroku Photo Industry Co., Ltd.) was modified into a pressure fixing device for image evaluation. Three types of pressure devices of 10Kg/cm, 15Kg/cm, and 20Kg/cm were used as pressure fixing devices. establish each one,
Offset and fixing properties were tested. The fixability test was carried out using an eraser (manufactured by Tombo Co., Ltd., Monoplastic Eraser) and dyed material abrasion fastness tester A-
3010 (manufactured by Daiei Kagaku Seimitsu Seisakusho) was partially modified, an eraser was fixed as shown in Figure 1, and the fixing surface was rubbed three times under a load of 1.5 kg to examine the degree of decrease in image density. The image density was evaluated by measuring the reflection density using PDA-65 (manufactured by Konishiroku Photo Industry Co., Ltd.). In FIG. 1, 1 is a test machine support stand, 2 is a fixing surface, 3 is an eraser, and 4 is a weight (1.5 kg). The results are shown in Table-3. As described above, it can be seen that the toner of the present invention has excellent fixing properties and offset properties. Furthermore, since the amount of charge of "Comparative Toner 1" was low, there was a lot of fog, and the image had low sharpness and poor image quality. In contrast, with the toner of the present invention, all images had good sharpness.

【table】

[Table] Example 21 Polyethyl acrylate (MW=7×10 ⁴
MW/Mn=4.0) 90g Carbon black (#30, manufactured by Mitsubishi Carbon)
10g Exemplified compound (11) (Sumidyur 44V-10) 50g Bisphenol A type epoxy resin (Epicoat
819) 50 g or more were mixed and dispersed in the same manner as in Example 1 to obtain the toner of the present invention. This toner is referred to as "Toner 21." Example 22 A toner of the present invention was obtained in the same manner as in Example 21 except that poly-2-ethylhexyl acrylate was used instead of polyethyl acrylate. This toner is referred to as "Toner 22". Example 23 A two-component developer was obtained by using the above "Toner 21" to "Toner 22" and adding conductive iron powder as a carrier. The charge amounts of the above toners are +8μc/g and +
It was 7.8μc/g. Image evaluation was performed using U-Bix V3R (manufactured by Konishiroku Photo Industry Co., Ltd.) in which the photoconductor was replaced with an organic photoconductor photoconductor and the fixing device was replaced with a pressure fixing device. As a result, good images with good sharpness were obtained in all cases, and there was no deterioration in image quality in a long run (10,000 copies) test, and no damage to the capsule toner was observed. Further, after fixing, a fixability test using an eraser was performed, and it was found that the image density only decreased from Dmax 1.5 to Dmax 1.45, with almost no decrease.

[Brief explanation of drawings]

FIG. 1 is a front view showing the main parts of the fixability testing device. 1: Testing machine support stand, 2: Fixing surface, 3: Eraser, 4: Weight (1.5Kg).

Claims (1)

[Claims] 1. A microcapsule type toner having an outer wall made of a substance containing at least an epoxyurea resin or an epoxyurethane resin.