JPS6188274A - Capsule toner - Google Patents

Abstract

PURPOSE:To improve rigidity and heat resistance by constituting a microcapsule of a core material and a shell material which is packed with pulverous wear- resistant inorg. powder and coasts said material. CONSTITUTION:General resins are usable for the resin constituting the shell material. The powder which is resistant to water and org. solvent and is thermally stable to temp. up to, for example, 300 deg.C is preferable as the pulverous wear- resistant inorg. powder to be packed into the shell material. Both of an inorg. material which itself is extremely hard and hardly wearable as compared to the shell material resin and a material which is self-lubricative and is strong to friction are used for the pulverous inorg. wear-resistant powder. Silicate, etc. are used as the former example and molybenum dioxide, etc. are used as the latter example, A spray dry method and phase sepn. method are adopted to coat the core material with the shell material. The core material has rigidity and wear resistance although said material is thin and therefore the capsule toner is less deteriorated even afer long-term friction and the fixing with small energy is made possible.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a toner used to develop an electrical latent image in electrophotography, electrostatic printing, magnetic recording, etc. Regarding possible microcapsule toner.

Previously, methods such as electrophotography, electrostatic printing, and magnetic recording have been widely used as methods for recording or copying information on large JA.

For example, in electrophotography, a pneumatic latent image is generally formed on a photoreceptor made of a photoconductive material by utilizing its photoconductivity, and then the latent image is developed using toner. If necessary, the toner image is transferred to a transfer material such as paper, and then fixed to obtain a copy.

The electronic printing method, as proposed in Japanese Patent Publication No. 42-14342, is a method of guiding and fixing a charged powder toner onto a recording material using an electric field for printing. The electrostatic recording method is a method in which a charge is applied to a dielectric layer in the form of an image, and a charged powder toner is attached and fixed thereon. The magnetic printing method is a method in which a magnetic latent image is formed on a Wi image JQ carrier, this is developed with toner powder containing a magnetic material, and the resulting toner image is transferred to recording material #1 and fixed. It is.

In the above-mentioned method, in order to make it possible to store the obtained toner image in a wet state, an operation of 'IH' is performed on a recording medium such as paper. Generally, engineering energy such as heat or pressure is used to fix toner images.
The smaller the energy required for fixing, the simpler the fixing device, the smaller the control system, the less consideration given to safety, etc., and the advantage that maintenance intervals can be extended. However, on the other hand, toner is exposed to mechanical pressure during transportation to the latent image surface, or heat from heat generating parts such as the fixing system and drive system in the developing system.
It is necessary to maintain its f'l ability even during storage without changing its development characteristics.

Lowering the melting point of toner to make it easier to fix,
In this respect, there is a natural limit to the use of soft materials. To overcome these limitations, there has been proposed a so-called microcapsule toner in which a soft core material is coated with another hard resin, as disclosed in US Pat. No. 3,788,994. However, although this microcapsule toner exhibits high resistance to static pressure and performs well during storage, it is unexpectedly brittle when subjected to dynamic pressure. They tend to be destroyed gradually and with a short lifetime, especially if the thermal environment is unfavorable. Increasing the thickness of the outer shell to provide sufficient strength against friction deteriorates the fixing properties.

In addition, it is difficult to encapsulate such thick-film microcapsules using conventionally known microencapsulation methods, and for extremely small toners ranging in size from several to several tens of liters, it is difficult to encapsulate toner particles. Agglomerates and M-shaped ;t
There are many inconveniences such as particles of only 9 materials being generated and the performance as a toner is likely to deteriorate. Development is desired.

An object of the present invention is to provide a capsule toner that solves the above-mentioned drawbacks.

A more specific object of the present invention is to provide a capsule toner that hardly deteriorates even when rubbed for a long time.

A further object of the present invention is to provide a capsule toner that can be easily manufactured.

Furthermore, it is an object of the present invention to provide a capsule toner that can be fixed with a small amount of energy.

A further object of the present invention is to provide a capsule toner that does not cause caking during storage and has good fluidity.

The microcapsule toner of the present invention was developed to achieve the above-mentioned object, and consists of a core material and a shell material covering the core material filled with abrasion-resistant inorganic fine powder. According to a preferred embodiment of the present invention, which is characterized by:
This microcapsule toner is produced by a method in which a dry mixture of a core material and a wear-resistant inorganic fine powder is covered with a shell material.

That is, the microcapsule toner of the present invention subjected to t1# as described above has improved rigidity and heat resistance by filling the shell material with abrasion-resistant inorganic fine powder, so that it has an extremely thin shell material. However, the toner can maintain its original form and function by withstanding friction during storage, agitation for development, or the transportation process, as well as frictional heat and heat generated from the device. In addition, since the thickness of the shell material is kept small, it is less likely to become an obstacle when applying pressure uniformly, and the core material of the present invention has high fluidity when pressurized, and the core material of the present invention has high fluidity when pressurized, so that it does not cause cracks in the shell material. The energy for constant Z+ is kept low because it is easy to penetrate and spread.

9-f. Binders constituting the core material of the microcapsule toner of the present invention include 1, for example, low molecular weight polyethylene wax, paraffin wax, fatty acids, esters thereof, metal soaps, fatty alcohols, polyhydric alcohols, and metal salts thereof. and its chlorides, fluorides, 7mides, bisamides, etc., as well as microcrystallins? Commercially available products include tux and amide wax, as well as natural products such as castor wax, hollow wax, beeswax, carnauba wax, rice wax, and montan wax.

In addition to so-called waxes, soft resins such as ethylene-vinyl acetate copolymers, ethylene-acrylic copolymers, low molecular weight polybutenes, cyclized rubbers,
etc. can be melted and fixed at extremely low temperatures even in heat fixing, but they can be particularly preferably used in pressure fixing. If necessary, an oily substance such as a non-drying oil such as soybean oil or human oil can be mixed. Also, by lowering the molecular weight of resins commonly used in heat fixing, such as epoxy resin, polyester resin, polyester resin, and polyacrylic type 11M.

Low melting point types can be used for heat fixing.

The core material of the capsule toner of the present invention generally includes:

Coloring agents include various dyes and pigments. Examples of such dyes and pigments include various carbon blacks, 7
Nilin black, Nafuthol yellow, molybdenum orange, a-damin lake, alizarin lake, methyl violet lake, phthalocyanine blue, nigrosine methylene blue, rose bengal, quinoline yellow, etc. are used. These coloring agents can be added to the core material binder in any M ratio, but usually 10%.
below,! Used in one go.

In addition, H
Magnetic powder may be included in the core material in order to
As such magnetic powder, powders of ferromagnetic elements such as iron, cobalt, and nickel, or alloys and compounds such as bugnetite, hematite, and ferrite are used. This magnetic powder may also be used as a colorant, and the amount of the Gi magnetic powder-containing powder may be in the range of 15 to 200 parts by weight based on 100 parts by weight of the total resin content of the core material 113.

As for the method of granulating the core material of the capsule toner of the present invention, the core material binder is soft or has a low melting point in the normal pulverization method, which tends to cause fusion, and it is necessary to pulverize while cooling. After mixing the binder, colorant, etc. in a molten state, the mixture is spray cooled or dispersed and suspended in warm water.

A method of cooling and solidifying after particle formation is suitable. In addition, the core material particles obtained by this method have a shape similar to that of a pearl, and this is reflected in the shape of the capsule toner finally obtained, making it possible to create a capsule toner with better durability against Ff, abrasion, etc. Can be built. Core particles are thus preferably formed having a particle size in the range from 5 to 20 lm.

The capsule toner of the present invention includes core particles as described above,
Obtained by covering with a shell material filled with wear-resistant inorganic fine powder.

Generally known resins can be used as the resin constituting the shell material, such as polystyrene, poly-P-chlorostyrene, polyvinyltoluene, styrene-butadiene copolymer, styrene-acrylic acid copolymer, styrene-maleic anhydride. Polymers or copolymers of styrene or its substituted products such as acid copolymers; epoxy resins, polyester resins, acrylic resins, acrylonitrile resins, xylene resins, polyurethanes, polyureas, melamine resins, polyamide resins, ionomer resins, furan Resin, ketone resin, terpene resin, phenol-modified terpene resin, rosin, rosin-modified pentaerythritol ester, natural resin-modified phenol resin lff-1, natural resin-modified leic acid resin, coumaron indene resin, malemono-modified pheonol resin, fat Cyclic hydrocarbon resin, petroleum resin, cellulose acetate phthalate, methyl vinyl ether-maleic anhydride copolymer, starch graft polymer, polyvinyl butyral, polyvinyl alcohol, polyvinyl toluene, polyvinyl pyridine, polyvinylidene chloride, polyvinylidene fluoride, Polyvinyl alcohol, polypyrrole, chlorinated paraffin, wax, adipose fin, etc. can be used alone or in combination. In addition, styrene-maleic anhydride copolymer, natural wood ++1i modified maleic acid resin, maleic acid modified phenol resin, etc. can be used alone or in combination. The higher the molecular weight of these shell material resins, the higher the toughness of the shell material, which tends to make encapsulation more difficult.

As the abrasion resistant e1 inorganic fine powder, one that exhibits high resistance to water and organic solvents and is thermally stable at temperatures up to 300° C. can be preferably used. In addition, wear-resistant IL used in the present invention
As an inorganic fine powder, is it itself? &Extremely hard compared to the shell material resin mentioned above, *Inorganic material that is difficult to destroy, or self-lubricating I! ]! ! Any material that is resistant to abrasion may be used. As an example of the former.

Silicate, crystal, silica sand, etc., flandum, alumina, titania, zirconia, aluminum silicate, etc., porcelain, silicon nitride, titanium nitride, silicon carbide, toughgestin carbide, titanium carbide, boron carbide, diamond, etc. new ceramics, titanium barium,
Amorphous metals such as magnesium titanate, calcium titanate, strontium titanate, calcium carbonate, magne 7A, antimony tritoxide, cerium oxide, Centast hard ferrites, amorphous silicon, hard metal powders such as chromium, nickel, stainless steel 1, etc. Examples include. Examples of the latter include molybdenum disulfide,
Examples include graphite and boron nitride. These can also be used in combination.

Also, the above #Availability 4I! The fine powder can be subjected to surface treatments such as organicization, hydrophobization, lipophilization, etc. in order to improve dispersion in the shell material.

These wear-resistant inorganic fine powders have an average particle size of 1 pm or less,
&f It is preferably 0.54 m or less, and in terms of BET specific surface area by nitrogen adsorption method, it is 0.5 to 400 m 2 /
A material of about 100 g can be used.

As mentioned above, if the ratio of the inorganic fine particles to the shell material exceeds 200% of the shell material resin, it is not desirable because encapsulation may be poor or the strength of the shell material may decrease. , less than 1%, the effect is poor, especially lO%~lO
A range of 0% is preferred.

The optimum 1Y range of scorched a fine powder is determined by the particle size of the particles.
Finer grains have more grains, coarser grains have less grains, and the optimum value is appropriately selected within the above range depending on the particle size.

Known methods can be used to coat and encapsulate the core material with a shell material filled with wear-resistant inorganic fine powder, but in the present invention, spray drying method,
A phase separation method can be preferably employed. In particular, it is preferable to use a method in which the shell material is coated with a shell material resin to which wear-resistant inorganic fine powder has been adhered to the surface in advance.

More specifically, the core material particles and the wear-resistant state A fine powder were mixed using a high-speed mixer such as a Henschel mixer to adhere the wear-resistant inorganic fine powder to the surface of the core material particles. rear,
Encapsulation is preferable; in this way, secondary agglomerates of inorganic fine particles are loosened and dispersed into secondary particles or a state close to it, and the abundance ratio of % fine particles in the shell material is made uniform. In addition, the agglomeration of the core particles itself is loosened, making it easier to flow and the operation becomes 8 spins. Compared to other methods, the present invention has advantages such as the effect of strengthening the adhesion between the core particles and the shell material polymer by embedding the inorganic fine particles into the surface of the core particles during coalescence. You can achieve your goals more effectively.

To coat with shell resin, the shell resin is dissolved in a solvent that is a good solvent for the shell resin but a poor solvent for the core particles, and then dissolved in this solution. A spray drying method in which the core material particles/inorganic fine particle mixture described in L is dispersed and the solvent is removed by heat or the like, or a phase separation method in which the shell material is precipitated by changing the solubility characteristics of the solvent may be applied. In both the spray drying method and the phase separation method, it is preferable to use a relatively dilute solution, for example 2 to 3% by weight, and unless the capsule wall is too thick, the capsule can be formed in a short time using a simple device. It is a single function. When using a concentrated solution or when attempting to form a relatively thick capsule wall, fine particles of only the shell material or agglomeration are likely to occur; however, as in the present invention, P inorganic fine particles are mixed with the core material particles. Also, the effect of suppressing the occurrence of fine particles and agglomeration of such shell material alone can be seen. The thickness of the shell material is 0
．． A range of 0.05 to 1 pm, particularly 0.1 to 0.6 pm is preferable because it provides a good balance between fixing properties and strength.

According to the present invention, the presence of wear-resistant inorganic particles in the outer shell improves rigidity and heat resistance even though the shell material is extremely thin. A microcapsule toner with improved properties is provided. Therefore, (1) the capsule toner of the present invention can be used as a toner due to friction during storage or during agitation or transportation process for development, as well as frictional heat and heat generated from the device. It has an extremely useful property of being able to maintain the form and function of the powder while requiring low energy for fixing.

Hereinafter, the present invention will be explained in more detail with reference to Examples and Comparative Examples.

Real "Lga".

[Manufacture of core material particles Low molecular weight polyethylene wax 30 with molecular H43000
i-lffi, 1550F paraffin wax 70
Preliminary dispersion of 470 parts by weight of Fe30,470 parts by weight,
Dispersion and mixing with 7 triters at 140°C.

The kneaded mixture was then sprayed into air at 50°C using air at 180°C from a two-fluid nozzle and collected by a cyclone to obtain spherical magnetic core particles of 1 to 20 ILm. .

[Microencapsulation] Core material particles 1000 heavy duty parts obtained above and titanium oxide 7 (
BET specific surface area 39.7 m'/g, particle size 0.04 μm)
The mixture was stirred and mixed for 2 minutes with a Henschel mixer model 10B (manufactured by Mikata Miike Seisakusho) at a rotation scale of 1 O.

Next, a portion of 100 parts of this mixture was mixed with dimethylaminoethyl meccrylate-styrene copolymer (copolymerization ratio l).
〇290, molecular weight 25,000) 10 parts by weight of DMF4
The dimethylaminoethyl methacrylate-styrene copolymer is dispersed in an encapsulation solution containing 0.00 parts by weight, and water is added dropwise while stirring to phase separate the dimethylaminoethyl methacrylate-styrene copolymer and surround the core material particles. The capsule toner was cured by heating to obtain capsule toner single particles having a shell material layer having a thickness of about 0.4 Bm and containing about 20% by weight of titanium oxide.

[Evaluation] The toner subjected to tJl showed positive chargeability, and the electronic copying machine PC
-12 (manufactured by Canon) was filled in a developing machine and when both were taken out, the image was clear and there was no fog.

A transferred image with high image density was obtained.

When testing the fixability of this unfixed image, it was found that the linear pressure was 12
The pressure level was arable at K g/cm, and sufficient heat fixing was possible at 280° C. when left in a constant temperature bath. Here, the fixing property is determined by fixing a fixed image on high-quality paper by using a 50 g weight with a base area of 1 cm" through Silpon paper C (Haga Yoshiten) with a tsubo of 120 g/m2.
The toner image was rubbed back and forth, and the point at which the difference in density of the toner image before and after the rubbing was 5% or less was determined as the fixing point.

The structure of the developing section of the developing machine used is shown in Fig. 1, and the distance between the drum 1 and the sleeve 2 is 30 mm.
0#Lm, distance between sleeve 2 and blade 4 is 1100
p, the fixed magnetic pole 3 has a maximum of 650 at the part facing the blade 4
The one showing Gaussian was used. Sleeve 2 rotated in the forward direction of drum I at a speed of 66 mm/sec.

Between drum 1 and sleeve 2), the frequency is 1°6K)
Iz, Vp-p (peak-to-peak voltage) 1.3K
An alternating current bias of V and a direct current bias of -400 V were applied, and an electrostatic image of -700 V was formed on the photoreceptor on the drum 1 in the dark area.

As a durability test, copying operations were repeated using a blank original with almost no toner consumption, toner was collected every 6 hours, and the copying process was carried out using a coulter counter MODEL.
When the particle size was inspected using a T A-■ model (manufactured by Coulter Counter), as shown as curve A in Figure 1,
24Il′? Even after the period, there was almost no change in particle size compared to the initial stage.
The copied images also maintained the same sharpness and clarity as the initial image. No damage was observed on the seal in the developing machine or on the developing sleeve.

Also, put this toner in a cylinder with a diameter of 50 mm.

Fill it to a thickness of 500mm and til it at a temperature of 50℃! Intermittent; δ, but no caking was observed. When copying was performed in the same manner as above, a good image was obtained ()
It was done.

A capsule toner was prepared in the same manner as in Example 1 except that titanium oxide was not used. Images were produced using this capsule toner in the same manner as in Example 1, and the images were initially clear and had high image density without fogging. The fixing property is also linear pressure t2Kg
/cm, and showed sufficient heat fixability at 80° C., and no difference from the toner of Example 1 was observed.

Using this toner, we conducted a durability test in the same manner as in Example 1. After about 6 hours, we found that toner fusion was visible at the part of the developer seal that came into contact with the rotating sleeve 2. After 24 hours, the sleeve no longer rotates smoothly, and furthermore, due to toner fusion at the end of the sleeve, it came into contact with the latent image support drum, making it impossible to maintain a regular gap. In addition, the developability of the toner had deteriorated, and the image density had decreased, resulting in a rough image.At this time, there was toner fused material in the toner in the hopper that did not pass through a 100-mesh sieve, and the toner fused material was observed on the developing sleeve. There was a streaky area where the toner was not coated.

Figure 2 shows the change in particle size of the hopper inner sleeve and toner using a coulter counter.To measure the zero particle size, put the collected toner into saline solution containing a surfactant and wait for 5 seconds +
1JI, a was carried out using a sonic dispersion.

The initial volume average diameter of 11.5 Bm increased to 18.7 Bm after 24 hours, or if the B1"rt dispersion time was increased to 5 minutes or more, the initial particle size decreased. Returned. When a fluidizing agent such as I/L aqueous colloidal silica is added to the toner in the hopper and mixed with a Henschel mixer, in terms of particle size, except for some fused pieces,
Although the grain size returned to its original size, the deteriorated developability was no longer restored.

"See 1 Tachieni" Instead of titanium oxide, alumina, zirconia, silicon carbide,
A capsule toner was obtained in the same manner as in Example 1 except that titanium nitride and boron nitride were used.

The results are shown in Table 1 below along with those of Example 1 and Comparative Example 1.
As shown in , the same results as in Example 1 were obtained.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of the main parts of a developing machine used to evaluate the durability of magnetic toners according to Examples and Comparative Examples of the present invention, and FIG. 2 shows changes in toner granulation during the durability test. It is a graph. 1.-Latent image support drum, 2.--Toner carrying sleeve. 3...Hard) C magnetic pole, ・[...Magnetic doctor blade, V5-φ・h5 main 1'' [toner. 6j・-Popper A...Microcapsule toner of Example 1 B...Comparative example Capsule toner LL of 1 is: Fig. 2 Fig. 1 Fig. 2 Rotary ring

Claims (1)

[Scope of Claims] 1. A microcapsule toner comprising a core material and a shell material covering the core material filled with wear-resistant inorganic fine powder. 2. The microcapsule toner according to claim 1, which is obtained by covering a dry mixture of a core material and a wear-resistant inorganic fine powder with a shell material.