JPH05107808A - Toner for electrostatic image development - Google Patents

Abstract

(57) [Summary] [Structure] Small particles of styrene resin and / or acrylic resin obtained by soap-free emulsion polymerization are immobilized on the surface of mother particles of at least polyester resin and colorant. Preferably, the small particles treated with a fluorosurfactant are immobilized. [Effect] In addition to being excellent in low-temperature fixability, a change in the amount of charge due to a change in humidity of the use environment is small, and a stable high-quality image can be obtained with the present toner.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to electrophotography, electrostatic recording,
The present invention relates to a toner for developing an electrostatic charge image (electrostatic latent image) in electrostatic printing or the like, and more particularly to a highly reliable toner having excellent fixability and having a small change in charge amount due to a change in environmental humidity.

[0002]

2. Description of the Related Art As means for developing an electrostatic latent image formed on an electrophotographic photosensitive member or an electrostatic recording member, a method using a liquid developer (wet developing method) and a method using a binder resin dye,
A method in which a colorant such as a pigment and, if necessary, a toner in which a charge control agent or the like is dispersed, or a one-component or two-component dry developer in which the toner is mixed with a solid carrier is used (dry development method). Is generally adopted. And
Each of these methods has advantages and disadvantages, but at present, the dry development method is widely used.

In the dry developing system, a toner is used to develop an electrostatic charge image, which is transferred onto a transfer sheet and then fused and fixed on the transfer sheet to obtain a copy. At that time, the fusion of the toner image is performed by contact with the solution vapor, pressurization or heating. As a heating method, a non-contact heating method using an electric furnace and a pressure heating method using a heating roller are generally adopted.

That is, the electrophotographic method comprises a latent image forming step, a developing step, a transferring step and a fixing step. Therefore, the toner has not only the developing step but also the functions required in the transferring step and the fixing step. Must be prepared.

As the toner, a binder resin is a vinyl resin typified by styrene / acryl copolymer, and a colorant, a charge control agent and the like are added to the toner particles,
It has been used for reasons such as ease of manufacture. However, from the toner using such a vinyl-based resin as a binder resin, due to the properties of the resin used, low-temperature fixability, offset resistance, blocking resistance, etc. Nothing has been obtained that satisfies all of them. That is, in the case of a vinyl resin represented by a styrene / acrylic copolymer, if low-temperature fixability is pursued, offset resistance and blocking resistance will be impaired. On the contrary, if the offset resistance is to be improved, the softening point and the crosslink density of the resin must be increased, and the low temperature fixability is sacrificed.

On the other hand, a polyester resin has been attracting attention as a binder resin having a wide molecular weight distribution and satisfying required characteristics such as low-temperature fixability, offset resistance and blocking resistance in a well-balanced manner. That is, since the polyester resin has a hydrophilic polar group such as a carboxyl group and a hydroxyl group,
It is known that it is advantageous in terms of adhesiveness to paper and that it is particularly excellent in fixability when used as a toner. However, on the other hand, since polyester resin has these hydrophilic groups,
When the resin is used as a toner, there is a drawback in that the charge amount of the toner changes greatly due to changes in the humidity of the use environment, and the image becomes unstable.

Therefore, in order to solve such a drawback, a toner in which a polyester resin containing a colorant is coated with a vinyl resin has been proposed (Japanese Patent Laid-Open No. 1-18).
5659, JP-A-58-205161 and 58-2.
05162, 58-205163 and 58-2.
No. 05164).

[0008]

However, the toner in which the surface of the core particles mainly composed of the polyester resin is coated with the vinyl resin is excellent in the fixing property, but the change in the environmental humidity changes. Regarding the stability of the charge amount against the above, although it is improved as compared with the case of using the polyester resin alone, it cannot be said that the stability is sufficiently improved in actual use.

Therefore, an object of the present invention is to solve such a problem, that is, it is excellent in low-temperature fixing property, and the change of the charge amount with respect to the humidity change of the use environment is small, and a stable high quality image is obtained. It is to provide a toner that can.

[0010]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that a vinyl resin obtained by a specific polymerization method is immobilized on the surface of mother particles containing a polyester resin having a specific particle size as a main component. The present inventors have found that the toner thus prepared meets the above-mentioned object, and completed the present invention.

That is, according to the present invention, the volume average particle size of at least the polyester resin and the colorant is 1 to 20 μm.
An electrostatic charge, characterized in that small particles of styrene-based resin or / and acrylic resin having a particle size of 0.01 to 3 μm obtained by soap-free emulsion polymerization are immobilized on the surface of mother particles of m. An image developing toner is provided.

The toner of the present invention has a particle size of 0.0 obtained by soap-free emulsion polymerization on the surface of mother particles having a volume average particle size of 1 to 20 μm, which are composed of a polyester resin and a colorant.
By fixing small particles of 1 to 3 μm of styrene resin and / or acrylic resin, it has excellent low-temperature fixability, and the change of the charge amount with respect to the humidity change of the use environment is extremely small, resulting in stable and high stability. A quality image can be obtained.

As described above, since the polyester resin has a hydrophilic polar group, it has excellent low-temperature fixability when used as a toner, but on the other hand, due to changes in humidity in the use environment,
There is a drawback that the chargeability of the toner changes greatly. On the other hand, since the styrene resin and the acrylic resin have few hydrophilic groups, the fixability is inferior to that of the polyester resin, but the chargeability is stable against changes in humidity.

Therefore, it has been proposed to coat the vinyl-based resin on the mother particles mainly composed of the polyester resin as described above. In this case, a polyester resin having a particle size of 1 to 20 μm is used as a mother body. Small particles having a particle size of about 0.01 to 3 μm are required for uniform coating.
However, the pulverization method cannot obtain such fine particles. According to the emulsion polymerization method, it is possible to obtain such fine particles, but in the emulsion polymerization method, since a hydrophilic emulsifier is used to stabilize the dispersion of the generated particles, a polyester resin is used as a main component. Even if the surfaces of the mother particles are coated with small particles of styrene resin and / or acrylic resin obtained by emulsion polymerization, the toner chargeability of the toner obtained changes greatly due to changes in humidity.

Therefore, in the present invention, small particles made of a styrene resin and / or an acrylic resin obtained by a soap-free emulsion polymerization method in which an emulsifier is not used at the time of polymerization or only a very small amount of an emulsifier is used. , And coat and immobilize it on mother particles containing polyester resin as a main component. Small particles made of styrene resin and / or acrylic resin obtained by this soap-free emulsion polymerization method,
By coating and fixing the base particles containing a polyester resin as a main component, a toner having a small change in charge amount due to a change in humidity can be obtained.

In the present invention, when the small particles of the styrene resin and / or the acrylic resin treated with a fluorosurfactant are used, the negative chargeability of the toner is enhanced and the toner is charged with respect to changes in humidity. The change in quantity is even smaller. Further, in this case, when the resin small particles are treated with a fluorine-containing quaternary ammonium salt having a quaternary ammonium salt structure as the fluorine-based surfactant, the toner charge amount changes remarkably with respect to the humidity change. It will be small. The treatment of the resin small particles with a fluorine-containing surfactant is carried out, for example, by adding a fluorine-containing surfactant to the dispersion after the polymerization of the small particles is completed, and heating the mixture for 1 hour if necessary. It is carried out by stirring for a while.

The toner of the present invention can be obtained by coating and fixing small particles made of a styrene resin and / or an acrylic resin on mother particles made of at least a polyester resin and a colorant. The treatment is to attach the small particles to the base particles so that the small particles are uniformly sprinkled, and then apply mechanical energy to fix the small particles to the base particles to such an extent that they are not detached under actual use conditions. ..

Means for uniformly adhering the small particles to the mother particles include, for example, a method of mixing the mother particles and the small particles as a dry powder by a mixer or a method of mixing the mother particles and the small particles with a liquid which does not dissolve. After that, there is a method of removing the liquid, but both of them can achieve uniform adhesion by strengthening the electric attraction between the mother particles and the small particles.

After adhering the small particles to the mother particles, the small particles are immobilized on the surface of the mother particles by mechanical energy. The mechanical energy for immobilization is given by a grinding force. There are a method of adding, a method of applying an impact force to the mixture by a blade rotating at a high speed, a method of colliding particles with each other or a particle with an impact plate in a high-speed air stream. Mechanofusion [Hosokawa Micron Co., Ltd.], Type I mill [Japan Pneumatic Industrial Co., Ltd.]
With a device with a lower crushing air pressure than in the case of normal crushing,
Examples include Turbo Mill [Turbo Industry Co., Ltd.], Hybridizer [Nara Machinery Co., Ltd.], Cosmomizer [Nara Machinery Co., Ltd.], automatic mortar, and the like.

In the present invention, particles having a volume average particle size of 1 to 20 μm, which are composed of at least a polyester resin and a colorant, are used as mother particles. Any known method can be used to obtain the mother particles. Can be adopted.
For example, a method in which a polyester resin and a colorant are melt-kneaded and then pulverized and dispersed into particles having a particle size of 1 to 20 μm, a method in which a polyester resin is pulverized and then dyed, and the like can be mentioned.

In the present invention, the polyester resin used for the mother particles comprises a dihydric alcohol as shown in group A and a dibasic acid as shown in group B, and further C It may be one in which a trivalent or higher alcohol or carboxylic acid as shown in the group is added as a third component.

Group A: ethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-
Propylene glycol, 1,4-butanediol, neopentyl glycol, 1,4 butenediol, 1,4-
Bis (hydroxymethyl) cyclohexane, bisphenol A, hydrogenated bisphenol A, polyoxyethylenated bisphenol A, polyoxypropylene (2,
2) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene (3,3) -2,2-bis (4-hydroxyphenyl) propane, polyoxyethylene (2,0) -2,2 -Bis (4-hydroxyphenyl) propane, polyoxypropylene (2,0) -polyoxyethylene (2,0) -2,2-bis (4-hydroxyphenyl) propane and the like.

Group B: 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, linolein Acids, their acid anhydrides or esters with lower alcohols.

Group C: trihydric or higher alcohols such as glycerin, trimethylolpropane and pentaerythritol; trivalent and higher carboxylic acids such as trimellitic acid and pyromellitic acid.

In the present invention, as the binder resin for the mother particles, a known binder other than the polyester resin may be used as long as it does not impair the performance of the toner, for example, 20% by weight or less of the total binder resin. Resin such as epoxy resin, polyamide resin, urethane resin, phenol resin, butyral resin, styrene / butadiene resin, styrene / methacrylic resin, or styrene / acrylic acid alkyl ester resin having an alkyl group of 2 or more carbon atoms is mixed and used. be able to. By setting the Tg of the binder resin used for the mother particles to be lower than the Tg of the resin of the small particles to be coated, a toner having excellent storage stability and excellent fixability can be obtained.

As the colorant used in the mother particles of the present invention, the following arbitrary pigments and dyes can be selected.

Black pigments Carbon black, acetylene black, lamp black, aniline black, etc.

Yellow pigments Yellow lead, zinc yellow, cadmium yellow, yellow iron oxide, mineral fast yellow, nickel titanium yellow, navels yellow, naphthol yellow S, hange yellow G, hanzer yellow 10G, benzidine yellow G, benzidine yellow GR , Quinoline yellow rake, permanent yellow CG, tartrazine rake, etc.

Orange pigment Red lead yellow lead, molybdenum orange, permanent orange GTR, pyrazolone orange, vulcan orange, indanthrene brilliant orange RK, benzidine orange G, indanthrene brilliant orange GK and the like.

Red pigment Bengal, cadmium red, red lead, mercury cadmium sulfide, permanent red 4R, resole red, pyrazolone red, watching red calcium salt, lake red D, brilliant carmine 6B, eosin lake, rhodamine lake B, alizarin lake, Brilliant Carmine 3B etc.

Purple pigment Manganese purple, fast violet B, methyl violet lake, etc.

Blue Pigment Dark Blue, Cobalt Blue, Alkali Blue Lake, Victoria Blue Lake, Phthalocyanine Blue, Metal-Free Phthalocyanine Blue, Phthalocyanine Blue Partial Chloride, Fast Sky Blue, Indanthrene Blue B
C etc.

Green pigments chrome green, chrome oxide, pigment green B,
Malachite green rake, fanal yellow green, etc.

White pigment Zinc white, titanium oxide, antimony white, zinc sulfide, etc.

Body pigments Barite powder, barium carbonate, clay, silica, white carbon, talc, alumina white and the like.

Various dyes (basic, acidic dispersion, direct dyes, etc.) Nigrone, methylene blue, rose bengal, quinoline yellow, ultraman blue, etc.

Further, as agents for adjusting the polarity and charge amount of toner, nigrosine, monoazo dye, zinc hexadecyl succinate, alkyl ester or alkylamide of naphthoic acid, nitrohumic acid, N, N'-tetramethyldiaminebenzophenone, N , N'-tetramethylbenzidine, triazine, salicylic acid metal complex and the like can be used as the charge control agent.
These charge control agents may be blended in the mother particles, or may be coated and immobilized on the surface of the mother particles similarly to the small particles.

In the case of using a magnetic toner, it is preferable to disperse and use the magnetic material powder in the mother particles. In this case, as the magnetic material, magnetite, hematite, iron oxide such as ferrite, metals such as iron, cobalt, nickel, or these metals and aluminum, cobalt,
Copper, lead, magnesium, tin, zinc, antimony, beryllium, bismuth, cadmium, calcium, manganese,
Examples thereof include alloys with metals such as selenium, titanium, tungsten, and vanadium, and mixtures thereof.

Further, in the toner of the present invention, in order to further enhance the offset prevention property in heat roll fixing,
Known release agents such as low molecular weight olefin resins and various waxes may be added. These release agents may be blended in the mother particles or may be coated and immobilized on the surfaces of the mother particles.

In the present invention, the small particles composed of the styrene resin and / or the acrylic resin, which are coated and immobilized on the mother particles, include a styrene resin and / or an acrylic monomer, which is chained with a polymerization initiator if necessary. Soap-free emulsion polymerization is performed using a transfer agent to obtain particles having a particle size of about 0.01 to 3 μm. Examples of the monomer used in this case include the following. In the present invention, a styrene / α-methyl resin acid monocarboxylic acid ester copolymer is preferably used as the resin small particles.

Styrene type monomers: styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-ethylstyrene, 2,4
-Dimethylstyrene, pn-butylstyrene, pt
ert-butyl styrene, pn-hexyl styrene,
pn-octylstyrene, pn-nonylstyrene,
pn-decylstyrene, pn-dodecylstyrene,
p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, 3,4-dichlorostyrene and the like.

Acrylic monomer: methyl acrylate,
Ethyl acrylate, n-butyl acrylate, isobutyl acrylate, propyl acrylate, n-octyl acrylate, dodecyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, acrylic acid Phenyl, α-
Methyl chloroacrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, methacrylate n
-Butyl, isobutyl methacrylate, n-methacrylic acid
Α-Methyl fatty acid monocarboxylic acid esters such as octyl, dodecyl methacrylate, lauryl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate and diethylaminoethyl methacrylate.

In the toner of the present invention, when small particles of styrene resin and / or acrylic acid resin coated and fixed on the mother particles are treated with a fluorosurfactant, the negative chargeability of the toner is enhanced. In addition, there is an effect that the change in the charge amount with respect to the change in humidity becomes even smaller. Known anionic, cationic, amphoteric and nonionic fluorosurfactants may be used in this case, and specific examples thereof include the following.

Anionic surfactant

[Chemical 1]

[Chemical 2]

[Chemical 3]

[Chemical 4] (In the above formula, M and n are as follows. M: K, Na, NH ₄ , Li, 1 / 2Mg, 1 / 2C
a, 1 / 2Ba, 1 / 2Zn, 1 / 2Fe, 1 / 2C
o, 1 / 2Cr, etc. n: Positive integer. )

Cationic surfactant

[Chemical 5]

[Chemical 6] (In the above formula, X, Y, R ^{1 to} R ⁴ , n, and m each represent the following: X: I, Br, Cl, etc. Y: —SO ₂ — or —CO—, R ^{1 to} R. ⁴ : H, lower alkyl group or aryl group having 1 to 10 carbon atoms, n and m: positive integers.)

Amphoteric surfactant

[Chemical 7] (In the above formula, n represents a positive integer.)

Nonionic surfactant

[Chemical 8] (In the above formula, n represents a positive integer.)

Among these, when the small particles treated with the quaternary ammonium salt structure-containing chaotic surfactant were used, it was recognized that the change in the charge amount of the toner with respect to the change in humidity was the smallest.

When the toner of the present invention is used as a two-component developer, it is used as a mixture with carrier particles. As the carrier in this case, any carrier known in the art can be used regardless of the presence or absence of the coating layer, as long as it imparts the desired polarity and charge to the toner.

[0050]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto. The parts shown below are based on weight.

(Production Example of Mother Particles) A polyester resin comprising polyoxyethylenated bisphenol A and terephthalic acid, having a weight average molecular weight of 11,000 and a glass transition point (Tg) of 60 ° C. was prepared. This polyester resin 1
5 parts of low molecular weight polypropylene [550p manufactured by Sanyo Kasei Co., Ltd.], 10 parts of carbon black and 2 parts of Cr-containing monoazo dye [TRH manufactured by Hodogaya Chemical Co., Ltd.] were melt-kneaded with 00 parts for 60 minutes by a two-roll mill. Were mixed, cooled and pulverized by a jet mill, and fine powder was removed by an air classifier to obtain mother particles A having a volume average particle diameter of 8 μm.

(Small particle production example 1) 95 parts of ion-exchanged water was charged into a flask equipped with a stirrer, a dropping funnel, a nitrogen introductory officer, a cooler, and a thermometer, and the temperature was raised and replaced with nitrogen. The mixture was kept at 65 ° C. and stirred at a rotation speed of 200 rpm, and a mixture of 40 parts of styrene and 11 parts of n-butyl acrylate was added dropwise over 4 hours. Also, ion-exchanged water 5
0.14 parts of potassium persulfate dissolved in 1 part was added over 6 hours. Then, after heating for 11 hours, the mixture was heated at 80 ° C. for 3 hours to complete the polymerization, and small particles B were obtained.

At this time, the polymerization rate was 97% and the particle size was 0.3.
It was 5 μm. The glass transition point of the dry particles is 65.
It was ℃. For the drying, the polymerization solution was frozen and dried under reduced pressure.

(Small particle production example 2) The following fluorosurfactant 1. was added to the polymerization liquid of the small particles B obtained in the small particle production example 1.
After adding 5 parts and maintaining the temperature at 50 ° C. and stirring for 1 hour, the mixture was cooled, frozen and dried under reduced pressure to obtain small particles C.

(Production Example 3 of Small Particles) In the polymerization liquid of the small particles B obtained in Production Example 1 of small particles, the following fluorosurfactant 1.
After adding 5 parts and maintaining the temperature at 50 ° C. for 1 hour, cooling, freezing and drying under reduced pressure, small particles D were obtained.

(Small Particle Production Example 4) 1.5 parts of a fluorine-containing surfactant having a quaternary ammonium salt structure was added to the polymerization solution of the small particles B obtained in Small Particle Production Example 1 and kept at 50 ° C. After stirring for 1 hour, it was cooled, frozen and dried under reduced pressure to obtain small particles E.

[Chemical 9]

(Small Particle Production Example 5) Small particles were produced in the same manner as in Small Particle Production Example 1 except that 2.5 parts of sodium lauryl sulfate was added as an emulsifier in the polymerization step in Small Particle Production Example 1. A small particle F having a particle size of 0.21 μm and a glass transition point of 65 ° C. was obtained.

Example 1 95 parts of mother particles and 5 parts of small particles B were mixed in a mixer for 1 minute, and mixed to such an extent that small particles B could not be discriminated. Then, 15 parts of this mixed powder was treated by a hybridization system [Nara Machinery Co., Ltd. NHS-O] at 12000 rpm for 2 minutes to immobilize the mixture to prepare a toner.

Carrier 3 consisting of 3 parts of this toner and spherical ferrite powder of 100 μm coated with silicon resin
Parts were mixed in an environment of 20 ° C., 20% RH and 20 ° C., 90% RH, the charge amount of this developer was measured, and the rate of change of charge with humidity was determined. The results are shown in Table 1. In addition,
The rate of change of charging due to humidity in this case is defined by the following equation.

Table 1 also shows the results of obtaining the roller temperature required for sufficient fixing by using this developer and modifying the copying machine IMAGIO 420 manufactured by Ricoh Co., Ltd. so as to change the fixing roller temperature. It was shown to. In addition, sufficient fixing means that the image density is 60% or more of the original image density even if the fixed image is rubbed 5 times with a sand eraser.

Example 2 Example 1 except that the small particles C were used instead of the small particles B.
A toner was prepared in the same manner as in 1. and the obtained toner was tested in the same manner as in Example 1. The results are shown in Table 1.

Example 3 Example 1 was repeated except that the small particles D were used in place of the small particles B.
A toner was prepared in the same manner as in 1. and the obtained toner was tested in the same manner as in Example 1. The results are shown in Table 1.

Example 4 Example 1 except that small particle E was used in place of small particle B
A toner was prepared in the same manner as in 1. and the obtained toner was tested in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 1 In Example 1, small particles B were not immobilized on the mother particles A,
The mother particles A themselves were used as a toner, and the same test as in Example 1 was conducted on this toner. The results are shown in Table 1.

Comparative Example 2 Example 1 except that the small particles F were used in place of the small particles B.
A toner was prepared in the same manner as in 1. and the obtained toner was tested in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 3 Small particle B which is a styrene / n-butyl acrylate copolymer instead of the polyester resin in the mother particle production example.
In the same manner as in the mother particle production example, except that
Was prepared. The same test as in Example 1 was conducted using the obtained mother particles G as they were (without fixing the small particles). The results are shown in Table 1.

[0067]

[Table 1]

[0068]

The toner for developing an electrostatic image according to claim 1 has a styrene resin and / or an acrylic resin obtained by soap-free emulsion polymerization on the surface of mother particles containing a polyester resin and a colorant as main components. Since it is configured to fix small particles made of resin, the toner has excellent low-temperature fixability, and the change in the amount of charge due to changes in the humidity of the operating environment is small. With this toner, stable high-quality images can be obtained. ..

Further, the electrostatic image developing toner according to claim 2 is configured such that the small particles made of the styrene resin and / or the acrylic resin are treated with a fluorine-containing surfactant. Therefore, the effect that the change in the charge amount with respect to the change in humidity becomes smaller is added.

Furthermore, since the toner for developing an electrostatic charge image according to claim 3 is configured such that a fluorinated quaternary ammonium salt is selectively used as the fluorine-based surfactant, a change in the amount of charge with respect to a change in humidity is conspicuous. The effect of becoming smaller is added.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Ian Harper 1-3-6 Nakamagome, Ota-ku, Tokyo Within Ricoh Co., Ltd. (72) Inventor Akihiro Koban 1-3-6 Nakamagome, Ota-ku, Tokyo Stock company Ricoh

Claims (3)

[Claims] 1. A surface of a mother particle having a volume average particle diameter of 1 to 20 μm, which comprises at least a polyester resin and a colorant,
A toner for developing an electrostatic charge image, comprising at least small particles of styrene resin and / or acrylic resin having a particle diameter of 0.01 to 3 μm obtained by soap-free emulsion polymerization, which are fixed. 2. The toner for developing an electrostatic charge image according to claim 1, wherein the small particles made of the styrene resin and / or the acrylic resin are treated with a fluorosurfactant. 3. The toner for developing an electrostatic charge image according to claim 2, wherein the fluorine-based surfactant is a fluorinated quaternary ammonium salt.