JPH0335659B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field] 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 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, toner for developing electrostatic images has been widely used in powder form, which is obtained by finely pulverizing thermoplastic resin as a binder and colorant such as carbon black dispersed therein. If it is a two-component toner, by mixing and stirring it 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, it 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 It requires a lot of energy and can even cause a fire if paper jams occur.
Moreover, in order to achieve reliable fixing, it is necessary to satisfy fairly strict conditions regarding temperature conditions and the like. Under such 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 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 etc. 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 aggregation or blocking during toner formulation or storage. However, the reality is that conventional microcapsule type toners have not yet been satisfactory. For example, JP-A-54-76233 discloses a technique for obtaining a polyamide film by polycondensation of acid chloride and a trifunctional amine such as diethyltriamine, but microcapsule type toner is manufactured using acid chloride. However, there is a problem that hydrolysis of acid chloride occurs when it is made into small particles, and the film formation reaction cannot be carried out stably.In addition, the rate of hydrolysis increases especially when the pH is 7 or higher during emulsion production, and microcapsule toner This becomes a big problem when small particles of 8 to 25 μm are required. Furthermore, Japanese Patent Application Laid-open No. 56-64349 discloses a technique using a cross-linked resin for the outer wall, and Japanese Patent Application Laid-Open No. 57-179860
The publication discloses a technique in which polyurethane resin or polyurea resin is obtained by polyaddition or condensation of isocyanate and diamine, etc., and this is used as an outer wall. According to this technique, crosslinking certainly increases the film strength and rigidity of the outer wall resin, but on the other hand, when used as a toner, the impact strength decreases and the brittleness becomes strong, making it difficult to form toner particles in a developing device. When mechanical force such as stirring or classification is applied, part of the outer wall tends to be easily destroyed, resulting in a decrease in fluidity. Furthermore, Japanese Patent Application Laid-Open No. 58-66948 discloses a technique in which the outer wall is made of a mixed resin of polyurea resin, polyurethane resin, and polyamide resin. However, as is clear from the fact that a fluidizing agent is used to fluidize the toner, this technique also has the drawback of causing a decrease in fluidity when used as a toner, similar to the above. The inventors of the present invention have made intensive studies to solve the drawbacks of the conventional technology, and have found that although the outer wall of the conventional microcapsule toner uses a crosslinking resin, the degree of crosslinking is not controlled. Therefore, it was found that the mechanical strength was weak, which caused a decrease in fluidity in particular. That is, it has been discovered that there is a certain correlation between the degree of crosslinking of the outer wall and the mechanical strength of the resin, which led to the activation of the present invention. [Object of the Invention] An object of the present invention is to provide a microcapsule type toner in which the degree of crosslinking of the outer wall resin can be controlled and, as a result, the mechanical strength of the resin can be adjusted to appropriate physical properties. [Structure of the Invention] The above-mentioned object of the present invention is to provide a microcapsule type toner having a core material having pressure fixing properties and an outer wall for covering the core material, wherein the outer wall has the following properties [A] and [B]. This was achieved using a microcapsule type toner which is characterized by containing ] as a main component. [A] A polyamide resin obtained using an acid chloride and an amine, at least one of which is a mixture of difunctionality and trifunctionality. [B] A polyurea resin obtained using an isocyanate and an amine, at least one of which is a mixture of difunctionality and trifunctionality. 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. One of the features of the present invention is that it provides a novel technical idea of controlling the degree of crosslinking of the outer wall, and as a control means, at least one of the compounds used to obtain the outer wall resin is added to two or more kinds. As a result, a microcapsule type toner having appropriate physical properties such as mechanical strength is formed, and fluidity, which is extremely important as a toner physical property, is improved. The resin of the present invention basically consists of a polyamide resin (hereinafter referred to as A resin) and a polyurea resin (hereinafter referred to as B resin). A resin and B resin are both 100%
It may be a copolymer, a partial copolymer, or even a blend. Further, if necessary, a third resin component may be contained in addition to the A resin and the B resin as a copolymer or a blend. Here, the third resin component is styrene resin,
Examples include acrylic resin, styrene acrylic resin, and the like. The above resin A can be obtained by a polycondensation reaction between an acid chloride and an amine. In the present invention, it is sufficient that at least one of acid chloride and amine is a mixture of two or more kinds, and both are
It may be a mixture of more than one species. On the other hand, resin B can be obtained by polyaddition reaction of isocyanate and amine. In the present invention, at least one or both of the isocyanate and the amine may be a mixture of two or more thereof. The mixing ratio of A resin and B resin is A resin: B resin =
The ratio is 1:9 to 9:1, preferably 5:5 to 1:9. Acid chlorides used in the present invention include adipoyl chloride, sebacoyl chloride, phthaloyl chloride, isophthaloyl chloride, terephthaloyl chloride, fumaroyl chloride, 1,4-cyclohexane dicarbonyl chloride, 4,4' -Diacid halides such as biphenyldicarbonyl chloride and 4,4'-sulfonyldibenzoyl chloride, trifunctional acid halides such as trimesoyl chloride, etc., and may be used as a mixture of two or more types. .
Mixtures with difunctional and trifunctional acid chlorides are also preferably used. The mixing ratio at this time is bifunctional
Trisensory = 99:15~60:40, good or 99:1~
It is 80:20. When the amine used in the present invention is used as a mixture of two or more types of amines, a mixture of a difunctional amine and a trifunctional or higher functional amine is used. As the difunctional amine, ethylenediamine,
hexamethylene diamine, phenylene diamine,
xylylenediamine, diaminocyclohexane,
piperazine, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl ether, 4,
Examples include 4'-diaminostilbene-2,2'-sulfonic acid and its sodium salt. Examples of trifunctional or higher functional amines include diethylenetriamine, triethylenetetramine, tetraethylenepentamine, iminobispropylamine, and triaminobenzene. One or more of the above amines may be arbitrarily selected and used, and other polyamines having different molecular chain lengths may be mixed in order to impart elasticity. The mixing ratio of two or more types of amines is 3% in total amines.
It is preferable to contain 1 to 50 mol% of a polyfunctional amine having higher functionality, and more preferably 2 to 30 mol%. The mixing ratio of acid chloride and amine to obtain resin A is 1:1 to 50 equivalents, preferably 1:1.1 to 40.
It is equivalent. When the isocyanate used in the present invention is used as a mixture of two or more, one of the isocyanates is
It is a functional isocyanate, and the others are trifunctional or higher functional isocyanates. Examples of the difunctional isocyanate include the following. (1) Hexamethylene diisocyanate OCN- (CH ₂ -) ₆ NCO Commercial product name "Sumidyur H" (manufactured by Sumitomo Bayer Urethane) (2) Metaphenylene diisocyanate Commercial product name “Naphconate” (manufactured by National Aniline) (3) Toluylene diisocyanate

[Formula] and

〔Effect of the invention〕

According to the present invention, since one of the monomers used to obtain the resins [A] and [B] is a mixture of two or more types, the degree of crosslinking can be freely controlled, resulting in mechanical strength. It was possible to obtain a microcapsule type toner having suitable physical properties. In particular, it has been found that when the degree of crosslinking is controlled so that the content of the crosslinking organism is 2 to 30 mol %, the fluidity of the toner becomes extremely good. [Examples] Examples of the present invention will be described below, but the embodiments of the present invention are not limited to these. Note that "parts" represent parts by weight unless otherwise specified. Substances contained in the manufacturing core material of toner No. 1 of the present invention (A) Acid chloride (B ₁ ) ″ Isocyanate (B ₂ ) ″ Magnetic powder (BL-520, manufactured by Titan Kogyo Co., Ltd.) 50 Partial Polymerization Initiator The above substances were mixed and stirred for about 1 hour using a sand grinder to uniformly mix and disperse the mixture to obtain a magnetic ink. 14 g of colloidal tricalcium phosphate prepared separately from trisodium phosphate and calcium oxide;
A dispersion liquid is prepared by uniformly dispersing 0.06 g of sodium dodecylbenzenesulfonate in 800 ml of water. Next, the magnetic ink was added to this dispersion.
Using a homogeator (manufactured by Tokushu Kika Kogyo Co., Ltd.) at a rotation speed of 8,000 to 9,000 rpm, under optical microscope observation,
The mixture was dispersed for about 10 minutes to form fine oil droplets with a diameter of 20 μm. Next, the dispersion was transferred to a No. 2 four-necked flask, and 70 ml of an aqueous solution in which (C ₁ ) and (C ₂ ) were dissolved was added at room temperature while stirring at low speed. Next, the temperature was gradually raised and the reaction was carried out at 80°C for 7 hours to obtain microcapsules having the polymer (A) as the core material and the polymer as the outer wall. Next, this was 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. In the above, (A), (B), (C ₁ ), and (C ₂ ) are respectively shown in the table −
Toner No. 1 of the present invention was obtained using the substance shown in No. 1. Production of toners No. 2 to No. 5 of the present invention In the production of toner No. 1 of the present invention, two types of amine components (C ₁ ) and (C ₂ ) are separately added, that is, after adding (C ₁ ), , (C ₂ ) and (C ₁ ) were added in the same manner as inventive toner No. 2.
~No.5 was obtained. Manufacture of Comparative Toner No. 1 and No. 2 In the manufacture of Invention Toner No. 1, Comparative Toner No. 1 and No. 2 were manufactured in the same manner as Invention Toner No. 1 using the substances shown in Table-1. I got it. [Example] Fluidity evaluation Toners of the present invention No. 1 to 1 obtained as above
The fluidity of each of Comparative Toner No. 5 and Comparative Toner Nos. 1 and 2 was measured. The evaluation method was based on the quietness density described below. This method is a method for evaluating fluidity, and is a simple method for evaluating fluidity in systems where there is no large difference in density, such as this system, and the larger the value, the better the fluidity. . (Measurement method) A simple laboratory method: place a cone-shaped funnel on top of a 20ml graduated cylinder, gently drop the microcapsule toner from above through a 100-mesh sieve, and measure the weight of the 20ml toner. , the quietness density was calculated. (Measurement Results) The results are shown in Table 1, and it can be seen that the toner of the present invention has good fluidity. Cohesiveness of toner Inventive toners No. 1 to 5 and comparative toners No. 1 and 2
The presence or absence of cohesion was visually examined. The results are shown in Table-1. In the table, “○” means no aggregation.
"Δ" indicates slight aggregation, and "x" indicates considerable aggregation.

【table】

Claims (1)

[Scope of Claims] 1. A microcapsule-type toner having a core material containing a pressure-fixing substance and an outer wall for covering the core material, wherein the outer wall mainly contains the following [A] and [B]. A microcapsule type toner characterized by: [A] A polyamide resin obtained using an acid chloride and an amine, at least one of which is a mixture of difunctionality and trifunctionality. [B] A polyurea resin obtained using an isocyanate and an amine, at least one of which is a mixture of difunctionality and trifunctionality.