JPH11133660A - Production of toner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a toner excellent in the dispersibility of the colorant through simple processes. SOLUTION: When a toner is produced through a process 1 for stirring and mixing starting materials including a bonding resin and a colorant, a process 2 for melting and kneading a mixture obtd. in the process 1 and a process 3 for pulverizing and classifying a melted and kneaded body obtd. in a process 2, the bonding resin and the colorant are stirred and mixed in the temp. range from (the glass transition temp. of the bonding resin) -5 deg.C to the softening point of the bonding resin in the process 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing toner used in electrophotography, electrostatic printing, magnetic recording, and the like, and more particularly, to a method for producing toner by a dry method.

[0002]

2. Description of the Related Art At present, a pulverizing method is mainly used as a method for producing a dry toner. Examples of a general method for producing a color toner by a pulverization method include, for example, 1) dry-mixing a raw material comprising a binder resin and a colorant, and further, if necessary, additives such as a charge control agent; 2) There is a method of melting and kneading the raw material mixture while applying a temperature with a general-purpose kneading apparatus, and 3) pulverizing the kneaded material solidified by cooling to obtain a color toner.

As an element relating to the performance of a color toner,
Has coloring power and transparency. Although the coloring power and the transparency are influenced by the amount of the colorant, it is also greatly influenced by the degree of dispersion of the colorant in the color toner particles. The dispersion state of the various raw materials in the color toner particles is substantially determined by the step of mixing the raw materials and the step of kneading in the production method of the color toner by the pulverization method. However, the kneaded product obtained by the method for producing a color toner by a pulverization method tends to have poor coloring power and transparency as a color toner because the raw material components in the binder resin, particularly the colorant, are insufficiently dispersed. There is.

To solve such a problem, Japanese Patent Laid-Open Publication No.
Japanese Patent No. 1154 discloses a technique of dispersing a water-insoluble dye and / or pigment in a binder resin by a flushing method. JP-A-6-11895 discloses that the step of melt-kneading is divided into two steps, a raw material mixture is granulated in a first kneading step, and an additive such as a binder resin is added and diluted in a second kneading step. A mixing technique is disclosed.
However, these attempts not only require a plurality of special steps, but also have the problem that the steps are very many and complicated.

[0005]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a method for producing a toner excellent in dispersibility of a colorant by a simple process.

[0006]

That is, the gist of the present invention is as follows: [1] 1) a step of stirring and mixing raw materials containing a binder resin and a colorant; 2) a step of melt-kneading the mixture obtained in step 1). And 3) a step of pulverizing and classifying the melt-kneaded product obtained in step 2), and
[5 ° C from the glass transition point (Tg) of the binder resin used]
A method for producing a toner, wherein a binder resin and a colorant are stirred and mixed in a temperature range of [low temperature] to [softening point (Tm) of the binder resin], [2] amount of the colorant Is from 0.1 to 50 parts by weight based on 100 parts by weight of the binder resin, [3] the method of [1] or [2], wherein the stirring and mixing time is from 5 to 120 minutes. ] And the mixing method [4] using a mixing device having a stirring blade, wherein the peripheral speed of the stirring blade is 5 to 200 m /
The method according to any one of the above [1] to [3], wherein
About.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION

1) Stirring and mixing step of raw materials In the stirring and mixing step of raw materials, the binder resin and the colorant are stirred and mixed. The temperature of the stirring and mixing is in the temperature range of [temperature lower by 5 ° C. than the glass transition point (Tg) of the binder resin used] to [softening point (Tm) of the binder resin]. Preferably [T
g to 5 ° C.) to [Temperature (Tms) at which the binder resin begins to soften], and more preferably Tg.
To Tms, particularly preferably [the temperature 5 ° C. higher than Tg] to Tms.

In order to bring the binder resin into a state in which only the surface is gradually softened, the temperature of the stirring and mixing is preferably at least [a temperature lower by 5 ° C. than the glass transition point (Tg) of the binder resin used]. When only the surface of the binder resin is gradually softened, the colorant can be easily dispersed in the subsequent melt-kneading step. This is because 1) secondary and tertiary aggregates of the colorant of about several tens of μm adhere to the softened binder resin surface and enter the inside of the binder resin surface, that is, the colorant aggregates are softened on the surface. 2) As a result, not only is the surrounding of the colorant aggregates covered with the binder resin, but also the voids between the colorant aggregates are impregnated with the molten resin, and the colorant aggregates. Primary particles themselves are also covered with the binder resin,
3) As a result, it is considered that the cohesive energy between the primary particles in the secondary and tertiary aggregates of the colorant is reduced, and the colorant is easily dispersed.

From the viewpoint of suppressing the fusion between the binder resins and suppressing the adhesion of the binder resin to the apparatus, the temperature of the stirring and mixing is T
m or less is preferable. As the fusion of the binder resins progresses, the particle size of the resin increases, and the load on the mixing device also increases due to the adhesion of the binder resin to the device. .

The method for setting the temperature of the stirring and mixing within a predetermined range is not particularly limited, and examples thereof include a method of heating a portion of the apparatus used for stirring and mixing where the raw material components are held to a constant temperature. Can be The temperature of the portion to be held is set in consideration of a desired stirring and mixing temperature and heat generated by operation of the apparatus.

The raw material components of the toner include known additives such as a charge control agent and wax, if necessary, in addition to the colorant and the binder resin.

The colorant is not particularly limited, and a known colorant for a color toner can be used. Specifically, black colorants such as carbon black, acetylene black, lamp black, graphite, iron black, aniline black, and cyanine black; I. Pigment Yellow 1, 3, 74, 97, 98, etc .; acetoacetic arylamide monoazo yellow pigments; C.I.
I. Pigment Yellow 12, 13, 13, 14
Acetoacetic acid arylamide-based disazo yellow pigments such as 7:
C. I. Pigment Red 48, 49: 1, 5
3: 1, 57, 57: 1, 81, 122, 5
Red or red pigments such as C.I. I. Blue pigments of copper phthalocyanine and its derivatives such as CI Pigment Blue 15: 3; I. Green pigments such as CI Pigment Green 7 and 36 (Phthalocyanine Green) can be used. These colorants may be used alone or as a mixture of two or more, and one or more pigments may be mixed.

The binder resin is not particularly limited, and a known binder resin for a color toner can be used. Examples of the polyester resin among the binder resins include a polyester resin using an alcohol component and an acid component such as carboxylic acid, carboxylic acid ester, and carboxylic anhydride as a raw material monomer.

Specific examples of the alcohol component are shown below. As the dihydric alcohol, 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, polyoxypropylene (6)
Alkylene oxide adducts of bisphenol A such as -2,2-bis (4-hydroxyphenyl) propane; ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3
-Propylene glycol, 1,4-butanediol, neopentyl glycol, 1,4-butynediol, 1,
5-pentanediol, 1,6-hexanediol,
Examples thereof include 1,4-cyclohexanedimethanol, dipropylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, bisphenol A, and hydrogenated bisphenol A.

Examples of trihydric or higher alcohols include sorbitol, 1,2,3,6-hexanetetrol, 1,4-
Sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butane Triol, trimethylolethane, trimethylolpropane, 1,3,5-trihydroxymethylbenzene and the like can be mentioned.

Specific examples of the acid component are shown below. As divalent carboxylic acids, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, succinic acid,
Adipic acid, sebacic acid, azelaic acid, malonic acid; n
Alkenyl succinic acid such as -dodecenyl succinic acid, n-dodecyl succinic acid or alkyl succinic acid. Furthermore, such carboxylic acid anhydrides and lower alkyl (C1 to C4) esters can also be mentioned as the acid component in the present invention.

As tri- or higher carboxylic acids, 1,2,4
-Benzenetricarboxylic acid, 2,5,7-naphthalenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, 1,2,4-butanetricarboxylic acid, 1,2,5-
Hexanetricarboxylic acid, 1,3-dicarboxyl-2
-Methyl-2-methylenecarboxypropane, 1,2,
4-cyclohexanetricarboxylic acid, tetra (methylenecarboxyl) methane, 1,2,7,8-octanetetracarboxylic acid, pyromellitic acid, and empol trimer acid. Further, anhydrides of such carboxylic acids,
Lower alkyl (C1-C4) esters can also be mentioned as the acid component in the present invention.

Other binder resins include styrenes such as styrene, chlorostyrene, α-methylstyrene, styrene-acrylate, and styrene-butadiene;
Monoolefins such as ethylene, propylene, butylene and isobutylene; vinyl esters such as vinyl acetate, vinyl propionate, vinyl benzoate and vinyl butyrate; methyl acrylate, ethyl acrylate, butyl acrylate;
Octyl acrylate, dodecyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate,
Esters of α-methylene aliphatic monocarboxylic acid such as butyl methacrylate and dodecyl methacrylate; vinyl ethers such as vinyl methyl ether, vinyl ethyl ether and vinyl butyl ether; vinyl methyl ketone, vinyl hexyl ketone, vinyl isopropenyl ketone and the like A homopolymer or a copolymer using vinyl ketone or the like as a monomer is exemplified.

The charge control agent that can be used in the present invention is not particularly limited, and a known charge control agent for a color toner can be used. Examples of charge control agents for negatively charged toner include chromium azo complex dyes; iron azo complex dyes; cobalt azo complex dyes; chromium zinc zinc aluminum boron complexes or salts of salicylic acid or its derivatives; naphtholic acid or its derivatives. Chromium-zinc-aluminum-boron complex or salt compound; Benzoic acid or its derivative chromium-zinc-aluminum boron complex or salt compound; Long-chain alkyl carboxylate, long-chain alkyl sulfonate, etc. Agents and the like. Examples of the charge control agent for the positively charged toner include derivatives such as nigrosine dyes and derivatives thereof, triphenylmethane derivatives, quaternary ammonium salts, quaternary phosphonium salts, quaternary viridinium salts, guanidine salts, and amidine salts. Can be

Further, as other additives, known additives for color toners can be used. Specific examples include natural and synthetic waxes, polyamides, epoxy resins, polycarbonates, polyurethanes, silicone resins, fluororesins, petroleum resins, offset inhibitors and the like. Examples of the offset preventing agent include a property improving agent such as a wax such as polyolefin. When a polyester resin is used as the binder resin, the offset preventing agent does not need to be added, and even when it is added, the amount of addition may be small.

In the present specification, the “glass transition point (Tg) of a binder resin” is defined as a physical property of a substance in a glassy state,
For example, it is a temperature at which the specific volume or the like suddenly changes and begins to show rubber-like elasticity. When the binder resin is composed of a mixture of a plurality of components, Tg is defined as the glass transition point of the mixture.

The "softening point (Tm) of the binder resin" and the "temperature (Tms) at which the binder resin begins to soften" are defined as follows. Koka type flow tester (CFT-50
0, manufactured by Shimadzu Corporation), and the diameter of the pores of the die is 1
A sample of 1 cm ³ is melted and discharged under the conditions of mm, length 1 mm, load 20 kg / cm ² G, and heating rate 6 ° C./min. Thereby, a plunger descent amount (flow value) -temperature curve of the flow tester is obtained. The height of the obtained S-shaped curve is h, and the temperature at the height corresponding to h / 2 is Tm.
And Also, the outflow start temperature is Tms.

In this step, the amount of the raw material components of the toner is not particularly limited. The amount of the colorant is preferably 0.1 to 50 parts by weight based on 100 parts by weight of the binder resin, and 0.1 to 30 parts by weight based on 100 parts by weight of the binder resin. More preferably, it is particularly preferably 1 to 10 parts by weight based on 100 parts by weight of the binder resin. From the viewpoint of image density, the amount of the colorant is preferably 0.1 part by weight or more based on 100 parts by weight of the binder resin. From the viewpoint of the limit of the amount of resin covering the colorant and the image transparency and saturation, It is preferably 50 parts by weight or less based on 100 parts by weight of the binder resin.

The time for stirring and mixing is not particularly limited.
Minutes or more, more preferably 5 to 120 minutes,
It is more preferably from 10 to 100 minutes, particularly preferably from 15 to 60 minutes. From the viewpoint of the blending amount of the colorant and the binder resin and the time during which the colorant is covered with the binder resin, the time of stirring and mixing is preferably 5 minutes or more, and from the viewpoint of operation stability and productivity, 120 minutes or less is preferable. .

The apparatus that can be used in this step is not particularly limited, and a general-purpose mixing apparatus or a general-purpose granulation apparatus can be used. For example, Henschel mixer (Mitsui Mining), super mixer (Kawata), high-speed mixer (Fukae Kogyo), Reidige mixer (Matsubo), Newgram machine (Seisin company), HYBRIDizer (Nara Machinery) ) And a high-speed stirring type mixing device or a granulating device.

As the above-mentioned mixing device, a device having a stirring blade is more preferable. In the mixing device having the stirring blade, the peripheral speed of the stirring blade is not particularly limited, but is preferably 5 to 200 m / s, and 10 to 1 m / s.
More preferably 50 m / s, 30 to 100 m
/ S is particularly preferable. Since the peripheral velocity of the stirring blade is the linear velocity of the powder, the peripheral velocity is preferably 5 m / s or more in order to bring the colorant into strong contact with the binder resin, and by controlling the temperature change caused by frictional heat. From the viewpoint of stable operation, the speed is preferably 200 m / s or less.

The pressure in this step is not particularly limited, but it is more preferable to carry out mixing under normal pressure to reduced pressure.

2) Melt-kneading step In this step, the mixture obtained in the stirring and mixing step of step 1) is melt-kneaded. There is no particular limitation on the melt kneader that can be used in this step, and a known melt kneader used in the melt kneading step in a dry method can be used. Specific examples include a single-screw kneader, a twin-screw kneader, a continuous kneader, a batch kneader, a roll mill, and a continuous open-roll kneader.

The operation conditions of the melt kneader may be appropriately set according to the kind of the melt kneader to be used, the desired degree of dispersion of the raw material components, and the like.

The melt-kneading temperature is not particularly limited, but it is desirable to melt-knead at a temperature at which the viscosity of the melt-kneaded product becomes highest, for example, at the melting point of the binder resin.

3) Pulverization and classification step In this step, the pulverization and classification of the melt-kneaded product obtained in step 2) is performed. Examples of an apparatus used for the pulverization include a known mill used in a pulverization step in a dry method. For example, a jet mill, a collision plate mill, a rotary mechanical mill and the like can be mentioned.

The apparatus used for classification is not particularly limited, and includes known classifiers such as an air classifier, an inertial classifier, and a sieve classifier.

Further, a step of adding an external additive to the classified toner may be provided. By providing such a step, effects such as securing the fluidity and chargeability of the toner can be achieved. Examples of usable external additives include inorganic fine particles such as silicon dioxide, titanium dioxide, aluminum oxide, zinc oxide, magnesium oxide, cerium oxide, iron oxide, copper oxide, and tin oxide.

As a method for adding the external additive, the classified toner and the externally added inorganic fine particles may be stirred and mixed with a high-speed stirrer such as a super mixer or a Henschel mixer. The mixing conditions such as the number of rotations of the stirring and the mixing time may be appropriately determined in accordance with the toner performance. It is more preferable that the external additive is subjected to a crushing process in advance.

The toner obtained by the production method of the present invention has a good HAZE value in the range of 10 to 23%, and has excellent dispersibility of the colorant in the toner.

[0036]

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

Raw material components of toner: Polyester resin (Tg = 60 ° C., Tm = 100 ° C.)
95 parts by weight (acid component: terephthalic acid 40 parts by weight, fumaric acid 60 parts by weight; alcohol component: polyoxyethylene (2.0)
-2,2-bis (4-hydroxyphenyl) propane 1
3 parts by weight of copper phthalocyanine pigment (CI Pigment Blue 15: 3) 3 parts by weight of charge control agent (boron benzylate complex)

Example 1 1.5 kg of a toner raw material component was supplied to a Henschel mixer, and then the raw material components were mixed at a rotation speed of a stirring blade of 3000 rpm while keeping the jacket temperature at 30 ° C. The Henschel mixer used had an effective volume of 10 liters. About 2 from the start of mixing
After a lapse of minutes, the temperature in the bath of the Henschel mixer reached 55 ° C. While maintaining the temperature, stirring and mixing were continued for another 15 minutes to obtain a mixture. The resulting mixture is
The mixture was quantitatively supplied to a continuous two-roll kneader using a table feeder and kneaded to obtain a melt-kneaded product.

The continuous two-roll type kneader used for kneading had a roll outer diameter of 0.12 [m] and an effective roll length of 0.8.
[M]. The operating condition of the continuous two-roll kneader is that the rotation speed of the high rotation side roll (front roll) is 7
5 rotations / minute, low rotation side roll (back roll) rotation speed 5
The rotation was 0 revolutions / minute and the roll gap was 0.0001 [m].
The temperature of the heating medium and the temperature of the cooling medium in the roll are 100 ° C. on the raw material input side and 100 k
° C, the raw material input side of the low rotation roll was 30 ° C, and the kneaded material discharge side was 30 ° C. The feed rate of the mixture was 4 kg / hour, and the average residence time was about 10 minutes.

The resulting melt-kneaded toner was cooled by a cooling belt, and then crushed by a mill having a φ2 [mm] screen. Next, the coarsely crushed product was pulverized by an I-type jet mill. Furthermore, coarse powder and fine powder were removed from the pulverized material using a cyclone type air classifier, and the average particle size (medium particle size) was 9 [μ].
m] was obtained. The average particle size of the toner was measured with a Coulter counter. Further, colloidal silica was added to the obtained cyan toner to obtain a developer. The amount of colloidal silica added was 2 parts by weight based on 100 parts by weight of the cyan toner.

Examples 2 to 9 and Comparative Examples 1 to 3 Under the conditions shown in Table 1, respective developers were obtained by the production method according to the production method of Example 1. Examples 1 to 5 show the effect of the mixture temperature, Examples 3, 6, and 7 show the effect of the stirring and mixing time, and Examples 3, 8, and 9 show the effect of the peripheral speed. Comparative Examples 1, 2, and 3 were performed at a mixture temperature of 20 ° C., 50 ° C., and 105 ° C., respectively.

An image forming test was performed using each of the developers obtained in Examples 1 to 5 and Comparative Examples 1 to 3, and the dispersibility of the colorant in each toner used in each developer was determined. Was confirmed.

The image formation test was performed using a Tektronix Phaser 550 manufactured by Kyushu Matsushita Electric Industrial Co., Ltd. First, a solid image was formed such that the toner amount on the OHP sheet was 0.5 mg / cm ^2, and fixing was performed at a temperature of 160 ° C. The transparency of the image was evaluated by adjusting the image density to about 1.3. This measurement was performed using an NDH-100 IDP-type HAZE meter manufactured by Nippon Denshoku Industries Co., Ltd. Table 1 shows the results.

[0044]

[Table 1]

The HAZE value is expressed by the following equation (1). The better the dispersibility of the colorant is, the smaller the diffuse transmittance becomes. Therefore, the smaller the HAZE value is, the better the dispersibility of the colorant is.

[0046]

(Equation 1)

As a result, as shown in Table 1, Examples 1 to 9
Have a HAZ value of 10 to 15%, and Comparative Examples 1 to 3 have a HAZ value of
The E value was 25-30%. From this, it was found that the toner obtained by the production method of the present invention had good dispersibility of the colorant.

[0048]

According to the present invention, a toner having good dispersibility of a colorant can be manufactured.

Claims (4)

[Claims] 1. A step of stirring and mixing raw materials containing a binder resin and a colorant; 2) a step of melt-kneading the mixture obtained in step 1); and 3) a pulverization of the melt-kneaded product obtained in step 2). In the method for producing a toner having each step of the classification step,
[5 ° C from the glass transition point (Tg) of the binder resin used]
A method for producing a toner, comprising stirring and mixing a binder resin and a colorant in a temperature range of [low temperature] to [softening point (Tm) of the binder resin]. 2. The method according to claim 1, wherein the amount of the coloring agent is 0.1 to 50 parts by weight based on 100 parts by weight of the binder resin. 3. The method according to claim 1, wherein the stirring and mixing time is 5 to 120 minutes. 4. The production method according to claim 1, wherein stirring and mixing are performed using a mixing device having stirring blades, and the peripheral speed of the stirring blades is 5 to 200 m / s.