JP3702578B2 - Crush classification method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pulverized and classified manufacturing method for pulverizing a raw material crushed material and fractionating a powder having a desired particle diameter or weight. For example, the raw material crushed material is pulverized, and only a desired particle size distribution is extracted and used in a method for producing an electrophotographic toner.
[0002]
[Prior art]
As an apparatus for pulverizing raw material crushed material and separating powder having a desired particle size or weight, there are a counter jet mill AFG manufactured by Hosokawa Micron Co., Ltd. and an IDS pulverizing classifier manufactured by Nippon Pneumatic Co., Ltd. The counter jet mill is provided with a plurality of compressed air nozzles 2 below the container, and the powder accumulated in the container is entrapped in the gas ejected from the nozzle to collide with the raw material crushed material, and pulverized. The powder that has been pulverized to a desired size by being sucked in passes through the rotating rotor 3. Large sized particles are returned by the rotating rotor, fall down, and further crushed. The IDS pulverization classifier supplies the raw material crushed material to the centrifugal force classifier, and after taking out particles having a desired particle size or less, disperses the raw material crushed material in the gas flow blown from the nozzle, and collides with the collision plate for pulverization. . The pulverized material joins the raw material crushed material and is supplied again to the classifier. These devices are used for pulverizing and classifying powder in general, and are used as a pulverizing and classifying step in the production of electrophotographic toner.
[0003]
[Problems to be solved by the invention]
The electrophotographic toner uses a material having a relatively low softening point and glass transition point in order to thermally fix an image. In recent years, there is a tendency toward a lower softening point and a lower glass transition point due to demands for higher speed and lower temperature fixing.
When classifying toner (especially those having a low softening point and a low glass transition point) with the above pulverization classifier, problems such as sticking of raw materials to the apparatus and mixing of coarse particles occur.
[0004]
This phenomenon is thought to occur because the energy of the pulverized material colliding with the machine such as the rotor and the collision plate becomes heat and the powder softens instantaneously. In addition, the same phenomenon is assumed when the powder that does not soften has strong adhesion and cohesion.
Further, recent toners are required to control the rounding of the particle shape due to the demand for higher performance of powder characteristics and charging characteristics. If the above pulverizer is used, it is possible to make the particle surface shape smooth due to collision when passing through the rotor, high-speed airflow energy, etc., and it is beneficial to use these devices also from that viewpoint, A similar problem occurs.
[0005]
[Means for Solving the Problems]
As a result of studying the present inventors to solve this problem and perform stable production, a gas flow in which a raw material containing at least one kind of thermoplastic resin is kneaded and crushed raw material crushed material is ejected from a plurality of nozzles. Pulverized by colliding raw material crushed material and pulverized material in a confluence region of a plurality of gas flows, passing the gas in which the pulverized material is dispersed to the opening of a rotating member having an opening, In the pulverization classification method in which the pulverized material that does not pass is sorted into the pulverized material that does not pass through, is combined with the raw material crushed material, and is pulverized by collision, this problem is caused by including the compound represented by the general formula (1) in the raw material. Solved.
[0006]
[Chemical formula 2]
[0007]
(In the formula, R ¹ represents an alkyl group or alkoxyl group having 10 or more carbon atoms, and R ² represents —X—COOR ³ (X represents an alkylene group, and R ³ represents an alkyl group having 10 or more carbon atoms.) Or an alkyl group having 10 or more carbon atoms).
Furthermore, sticking can be further suppressed by utilizing collision of particles in the pulverization step.
[0008]
It is considered that the adhesion to the apparatus is reduced by the releasing effect of the compound. Even if the adhesion occurs little by little, it is considered that the adhered material is peeled off due to the centrifugal force of the rotating body and the releasing effect of the lubricant. According to the present invention, the interval of regular cleaning in the machine is extended, and a great industrial advantage is realized.
In addition, the powder surface can be made smoother, and rounding control has been realized.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
In the pulverization classification method used in the present invention, the raw material crushed material and the pulverized material are dispersed and collided with a gas flow. As a method for dispersing the raw material crushed product and pulverized product in the gas stream, a method of dispersing allowed to rise up to the balloon material crushed product and pulverized product compressed air from a nozzle to the material crushed product and pulverized product deposited on the container or the like Ya Pipes and nozzles are provided at the bottom of the hopper on the raw material crushed material and pulverized material, such as hopper, and compressed gas is blown out from the nozzle.
Examples of such a method include a method of flowing and a method of depositing powder on a table feeder or the like and feeding and dispersing the powder into a gas flow path.
[0010]
As a method of collision, a method of causing a member such as a collision plate to face and collide with a gas flow direction in which raw material crushed material and pulverized material are dispersed (such as I-type jet mill manufactured by Nippon Pneumatic Co., Ltd.), or unevenness on at least one surface The surfaces of the members that are formed are made to face each other at an interval of 10 mm or less, and the member surfaces are moved relative to each other to generate a vortex in the recess, and the gas flow is passed through the opposed gap to cause particles in the vortex. Examples include a method of causing particles to collide with each other, a method of causing particles to collide with an uneven surface, a method of arranging a plurality of compressed air blowing nozzles, and a method of causing particles to collide with each other in a confluence region of gas flow. Although the sticking to the apparatus is suppressed by the addition of the lubricant of the present invention, the method of making it collide with the collision plate or the like sometimes sticks at the time of the collision, so the collision between particles in the vortex or the collision between particles in the gas flow merging area Is more preferable.
[0011]
The rotating member provided with the opening is rotated, and the gas in which the pulverized material is dispersed is flowed through the opening from the outside to the inside of the rotating member. When the gas passes through the rotating body, the particles having a large particle size and the heavy particles are returned to the outside, and only the particles having a small particle size and the light weight pass through the gas flow. The rotation of the rotating member also causes the gas flow to rotate, and the centrifugal force causes particles having a large particle size or heavy particles to be ejected to the outside, so that only particles having a small particle size or light weight pass through.
[0012]
As the rotating member, a cylindrical or conical rotor is generally used, and a slit-shaped opening is provided. The particles ejected to the outside join the raw material crushed material and are pulverized again. Examples of these apparatuses include a counter jet mill AFG and an inomizer manufactured by Hosokawa Micron. In the counter jet mill, the particles collide with each other in a gas flow confluence area, and the inomizer collides the particles with each other by a vortex in the gap between the rotating crushing rotor and the liner.
[0013]
The method of collecting the powder pulverized and classified by the above steps is not particularly limited, but as a general method, the powder that has passed through the rotating member can be collected by a filter or a cyclone. The powder returned to the outside of the rotating member may be collected by dropping and depositing below the rotating member only by gravity. Further, it may be deposited like a cyclone by rotating air current.
[0014]
In the case of Hosokawa Micron's pulverizing and classifying machine counter jet mill AFG type (Fig. 1), a plurality of compressed air nozzles 2 are provided below the container, and the particles accumulated in the container are brought into the gas ejected from the nozzle and the particles collide with each other. The pulverized powder is pulverized to a desired size by sucking with a blower through the rotating rotor 3 above the container, and passes through the rotating rotor 3. Large sized particles are returned by the rotating rotor, fall down, and further crushed.
[0015]
If the powder has strong adhesion or cohesion, or is easily melted or softened by the heat of collision energy, it will collide with the rotating member when passing through the opening of the rotating member, and may adhere gradually. There is.
This problem was solved by including the compound represented by the general formula (1) in the powder used in the present invention.
[0016]
[Chemical 3]
[0017]
(In the formula, R ¹ represents an alkyl group or alkoxyl group having 10 or more carbon atoms, and R ² represents —X—COOR ³ (X represents an alkylene group, and R ³ represents an alkyl group having 10 or more carbon atoms.) Or an alkyl group having 10 or more carbon atoms.)
R ¹ is an alkyl group or an alkoxyl group, each having 10 or more carbon atoms, preferably 16 or more, and more preferably 20 or more. R ² is —X—COOR ³ preferably X is
[Formula 4]
− (CH ₂ ) _n −
[0019]
Wherein n is a straight-chain alkylene group having 6 or more and R ³ is an alkyl group having 20 or more carbon atoms. Alternatively, it is an alkyl group having 10 or more carbon atoms, preferably 16 or more carbon atoms. Particularly preferred is an alkyl group having 20 or more carbon atoms. When R ² is —X—COOR ³ , R ¹ is preferably an alkoxyl group (ie, a diester). Specific examples include aliphatics such as di-n-decyl ketone, di-n-dodecyl ketone, di-n-stearyl ketone, di-n-icosyl ketone, di-n-behenyl ketone, and di-n-tetracosyl ketone. Ketones; Fatty acid diesters such as dodecyl sebacate, distearyl sebacate, dibehenyl sebacate; fatty acid monoesters such as stearyl laurate, behenyl laurate, stearyl stearate, behenyl stearate, stearyl behenate, behenyl behenate, etc. Is mentioned. Mixtures of these are also suitable.
[0020]
Furthermore, the melting point is particularly preferably 50 ° C. or higher and 100 ° C. or lower.
The addition amount of the compound used in the present invention varies depending on the composition, particle size and addition method of the powder, and is not particularly limited in the range having an appropriate release effect, but is preferably in the range of 1 to 20% by weight, more preferably It is in the range of 3 to 10% by weight.
In order to add the compound to the powder and exhibit the effect, the compound must be dispersed or dissolved in at least the thermoplastic resin contained in the powder. In this case, other additives in addition to the compound may be simultaneously dispersed or dissolved in the thermoplastic resin. The addition method is not particularly limited as long as the conditions are satisfied. For example, in the case of an electrophotographic toner which is a kneaded pulverized product of various additives and a binder resin, it may be added at the stage of polymerization production of the binder resin, or after the binder resin and the compound are dissolved and mixed in the solvent, the solvent is added. It may be distilled off. Further, it may be added at the toner kneading stage.
[0021]
The manifestation of the effect of the present invention is considered to be because adhesion to the classification zone requiring the accuracy of the classification device is reduced by the mold release effect of the compound represented by the general formula (1). Even if it adheres very slightly by using a rotating member, it is considered that the deposit is peeled off by centrifugal force and returned to the outside. It is thought that the ease of peeling of the deposits is improved by adding the compound. Even if the compound is not present, if the rotational force of the rotating member is increased to increase the centrifugal force, the force to peel off the deposit will increase, but the classification point (passes through the opening of the rotating member or is returned to the outside by changing the rotational frequency. Since the particle size of the boundary also changes, it is practically difficult.
[0022]
For the purpose of suppressing the wear of the rotating member, the rotating member may be subjected to wear resistance treatment. As the anti-abrasion treatment, there is a method of forming an oxide film on the surface or coating with ceramic, but these treatments make small irregularities on the surface and are easy to adhere. In such a case, the present invention is more effective.
The crushed powder used in the present invention is effective for those having strong adhesion and cohesion and those that are easily melted or softened by energy such as collision.
[0023]
Taking the electrophotographic toner as an example of the powder used in the present invention, a thermoplastic resin is used as the binder resin which is the main component of the toner.
Since the toner is melt-fixed on paper by heat, it is desirable that the binder resin has a lower glass transition point or flow tester softening point because it can be fixed at a lower temperature. However, when the glass transition point and the flow tester softening point are low, as described above, it is easy to melt and soften due to energy such as collision, and the performance desired for toner and the ease of classification production are contradictory. . That is, the present invention is particularly effective for a toner having a low glass transition point or flow tester softening point of the binder resin.
[0024]
As the binder resin, various known resins suitable for toner can be used. For example, styrene resin, vinyl chloride resin, rosin modified maleic resin, phenol resin, epoxy resin, saturated polyester resin, unsaturated polyester resin, low molecular weight polyethylene, low molecular weight polypropylene, ionomer resin, polyurethane resin, silicone resin, ketone resin , Ethylene-ethyl acrylate copolymer, xylene resin, polyvinyl butyral resin, and the like. Preferred resins for use in the present invention include styrene resins, saturated or unsaturated polyester resins, and epoxy resins. . Particularly preferred are styrene resins and polyester resins.
[0025]
Styrene resins include polystyrene, polychlorostyrene, poly-α-methylstyrene, styrene-chlorostyrene copolymer, styrene-propylene copolymer, styrene-butadiene copolymer, styrene-vinyl chloride copolymer, styrene. -Vinyl acetate copolymer, styrene-maleic acid copolymer, styrene-acrylic acid ester copolymer (styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer) Styrene-octyl acrylate copolymer and styrene-phenyl acrylate copolymer), styrene-methacrylic acid ester copolymer (styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene- Butyl methacrylate copolymer, styrene-metac Octyl copolymer Le acid and styrene - phenyl methacrylate copolymer), methyl methacrylate copolymer styrene -α- chloromethyl acrylate and styrene - acrylonitrile - acrylic acid ester copolymers and the like.
[0026]
Examples of the polyester resin include a crosslinkable polyester resin and a non-crosslinkable polyester resin.
The crosslinkable polyester resin is obtained by polycondensation of a divalent carboxylic acid monomer, a divalent alcohol monomer, a trivalent or higher polyvalent carboxylic acid monomer or a polyhydric alcohol monomer. Divalent alcohol monomers include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, neopentyl glycol, 1,4-butenediol. Diols such as bisphenol A, etherified bisphenols such as bisphenol A, polyoxyethylenated bisphenol A and polyoxypropylenated bisphenol A, and other divalent alcohol monomers. The divalent carboxylic acid monomer is mainly composed of isophthalic acid, terephthalic acid, adipic acid, sebacic acid, diphenic acid, naphthalenedicarboxylic acid, cyclohexanedicarboxylic acid, anhydrides or lower alkyl esters of these acids. Is mentioned. Examples of the trivalent or higher polyvalent carboxylic acid include trimellitic acid, cyclohexanetricarboxylic acid, naphthalenetricarboxylic acid, butanetricarboxylic acid, hexanetricarboxylic acid, octanetetracarboxylic acid, anhydrides of these acids, and the like. Examples of the trihydric or higher polyhydric alcohol monomer include trimethylolethane, trimethylolpropane, glycerin, and pentaerythritol.
[0027]
The non-crosslinkable polyester resin is obtained by polycondensation containing a divalent carboxylic acid monomer and a divalent alcohol monomer as main components. Examples of the divalent alcohol monomer and the divalent carboxylic acid monomer include those similar to the crosslinkable polyester resin.
Moreover, not only one type but also two or more types of binder resins can be used in combination.
[0028]
In addition, as a binder resin used for full color where glossiness and transparency are required, among styrene resins and polyester resins, those which are non-crosslinkable and have a narrow molecular weight distribution are preferable. More preferred. The weight average molecular weight is preferably 5 times or less of the number average molecular weight, more preferably 3 times or less.
[0029]
About a trivalent or higher polyvalent carboxylic acid monomer or polyhydric alcohol monomer within a range that does not substantially lose the properties of the non-crosslinkable resin, that is, a level that gives a highly branched structure to the linear polymer. About 2 mol% or less may be added.
Moreover, not only one type but also two or more types of binder resins can be used in combination.
[0030]
The softening point of the binder resin, which is a thermoplastic resin used in the present invention, preferably has a value measured by a flow tester method of 160 ° C. or lower, more preferably 135 ° C. or lower. A temperature exceeding 160 ° C. is not preferable because sufficient low-temperature fixability cannot be obtained and the fixing strength tends to deteriorate. As the binder resin used for full color where glossiness and transparency are required, those having a temperature of 120 ° C. or lower are preferable, and those having a temperature of 110 ° C. or lower are more preferable. The lower the softening point is, the better the fixing property is. However, since the glass transition point described later is lowered as the softening point is lowered, the resin is designed in combination with the adverse effect of lowering the glass transition point.
[0031]
The glass transition temperature of the binder resin is preferably such that the transition start (inflection point) is 50 ° C. or higher and 75 ° C. or lower when measured with a differential thermal analyzer. When the glass transition temperature is less than 50 ° C., the thermal stability during long-term storage is poor, causing toner aggregation and solidification, which causes problems in use. Further, when the temperature is 75 ° C. or higher, although there is a margin in toner fusion and fine powder crushing, the softening point increases as the glass transition point increases, and the fixability tends to deteriorate. The average particle size of the toner is preferably 5 to 20 μm.
[0032]
The present invention can be used for the production of two-component developer toner, magnetic one-component toner, non-magnetic one-component toner, black toner, mono-color toner, and full-color toner. In general, a method using a Coulter counter is widely used for the particle size of the toner. The average particle size of the toner used in the present invention is 100 μm aperture for the Coulter Counter TA-II type, the toner particles are dispersed in isotone, and the 3rd to 16th channels are used to determine the toner particle size distribution. Measured and determined by volume average.
[0033]
The softening point of the binder resin, which is a thermoplastic resin, was measured using a flow tester method. In a flow tester (CFT500 manufactured by Shimadzu Corporation), a heating body is set at 80 ° C. using a nozzle having a diameter of 1 mm and a length of 10 mm, and 1 g of binder resin is charged. The plunger is lightly pressed and preheated for 300 seconds, then a pressure of 30 kg / square cm is applied and the temperature is raised at a rate of 6 ° C./minute. As the temperature rises, the binder resin softens, the binder resin is pushed out from the nozzle, and the plunger descends. The temperature corresponding to the midpoint of the descending distance of the plunger from the start to the end of the descent is defined as the softening point.
[0034]
The glass transition point of the binder resin, which is a thermoplastic resin, is measured using a differential thermal analyzer (DT-30 model, manufactured by Shimadzu Corporation). About 20 mg of the binder resin is placed in the sample cell and set in the measuring unit, and once at 10 ° C./min. After heating to 100 ° C. at the rate of temperature increase and cooling to room temperature, the temperature is increased again at 10 ° C./min, and tangent lines are drawn from each of the smooth curve portions before and after the inflection temperature portion of the DTA curve. Let the intersection of each other be the glass transition point.
[0035]
【Example】
EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to a following example, unless the summary is exceeded.
Example 1
100 parts by weight of styrene-butyl acrylate copolymer resin (flow tester softening point 130 ° C. glass transition point 60 ° C.)
2 parts by weight of polypropylene, 2 parts by weight of charge control agent (quaternary ammonium salt), 5 parts by weight of behenyl behenate (melting point: 76.0 ° C.), kneaded with a twin-screw kneader, roughly crushed, Obtained.
[0036]
The raw crushed material was subjected to pulverization and classification using a counter jet mill 400AFG manufactured by Hosokawa Micron. This device has a structure in which the pulverized powder is classified by a rotating rotor portion having a slit-shaped opening, and particles larger than a desired particle diameter do not pass through the rotating rotor but fall into the pulverizing zone and are pulverized again. Yes.
It was possible to continuously obtain about 300 kg of pulverized classifieds (average particle size of about 8.3 μm and containing 25 to 35% by volume of fine powder of 5 μm or less) at a feed rate of about 30 kg / hour for about 10 hours.
[0037]
Example 2
Branched polyester resin 100 parts by weight (constituent monomer: polyoxypropylenated bisphenol A, polyoxyethylenated bisphenol A, terephthalic acid, trimellitic acid flow tester softening point 113 ° C glass transition point 67 ° C)
Pigment Pigment Blue 15 5 parts by weight of charge control agent (LR147 manufactured by Nippon Carlit Co., Ltd.) 4 parts by weight of distearyl ketone (melting point: 87.5 ° C.) A toner raw material crushed material was obtained.
[0038]
The toner raw material coarsely pulverized product was pulverized and classified using a counter jet mill 400AFG manufactured by Hosokawa Micron Corporation. This device has a structure in which the pulverized powder is classified by a rotating rotor portion having a slit-shaped opening, and particles larger than a desired particle diameter do not pass through the rotating rotor but fall into the pulverizing zone and are pulverized again. Yes.
About 300 kg of pulverized classifieds (with an average particle diameter of about 8.5 μm and containing 25 to 35% by volume of fine powder of 5 μm or less) was obtained continuously at a feed rate of about 30 kg / hour for about 10 hours.
[0039]
Example 3
100 parts by weight of styrene-butyl acrylate copolymer resin (flow tester softening point 130 ° C. glass transition point 60 ° C.)
2 parts by weight of polypropylene Charge control agent (quaternary ammonium salt) 2 parts by weight Distearyl ketone (melting point: 87.5 ° C.) 5 parts by weight are kneaded with a twin-screw kneader, coarsely crushed, and crude toner raw material Got.
[0040]
The toner raw material coarsely pulverized product was pulverized and classified using a counter jet mill 400AFG manufactured by Hosokawa Micron Corporation. This device has a structure in which the pulverized powder is classified by a rotating rotor portion having a slit-shaped opening, and particles larger than a desired particle diameter do not pass through the rotating rotor but fall into the pulverizing zone and are pulverized again. Yes.
About 300 kg of pulverized classifieds (with an average particle size of about 8.4 μm and containing 25 to 35% by volume of fine powder of 5 μm or less) in about 10 hours at a feed rate of about 30 kg / hour could be obtained continuously.
[0041]
[Brief description of the drawings]
FIG. 1 is a diagram showing an example of a pulverization classification method that can be used in the present invention.
[Explanation of symbols]
1 Raw material feed 2 Compressed air nozzle for crushing 3 Classification rotor 4 Crushing classification

Claims (6)

A raw material containing at least one kind of thermoplastic resin is kneaded, and the coarsely crushed raw material crushed material is dispersed in a gas flow ejected from a plurality of nozzles. pulverized by collision, a gas containing dispersed pulverized product into the opening of the rotary member having an opening passed through, sorted into the pulverized material does not pass through the ground material to pass, pulverized material does not pass through is joined with the material crushed product Further, in the pulverization classification method for pulverization by collision, the pulverization classification method is characterized in that the raw material contains a compound represented by the general formula (1).
(In the formula, R ¹ represents an alkyl group or alkoxyl group having 10 or more carbon atoms, and R ² represents —X—COOR ³ (X represents an alkylene group, and R ³ represents an alkyl group having 10 or more carbon atoms.) Or an alkyl group having 10 or more carbon atoms.)   The pulverization classification method according to claim 1, wherein the rotating member has a cylindrical or conical shape and has a slit-shaped opening. The pulverization classification method according to claim 1 or 2 , wherein the glass transition point of the thermoplastic resin is 50 ° C or higher and 75 ° C or lower. The pulverization classification method according to any one of claims 1 to 3 , wherein a softening point of the thermoplastic resin is 160 ° C or lower. The pulverization classification method according to any one of claims 1 to 4 , wherein the pulverized product obtained by this method is a dry electrophotographic toner or a raw material of a dry electrophotographic toner. 6. The pulverization classification method according to claim 5 , wherein the classified product obtained by this method is a color toner.