JPS5857104B2 - Manufacturing method of pressure fixing toner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrostatic photographic toner, and more particularly to a pressure-fixable toner that can be fixed by pressure.

As conventional electrostatic photographic toners, heat-fixable toners are mainly used.

This type of toner is mainly made of thermoplastic resin, and after softening the resin by heating and kneading it with a coloring agent,
Made by crushing.

However, the fixing method using heat-fixable toner has the following drawbacks.

(1) It takes a long time to raise the temperature of the fixing device above the softening point of the toner.

(2) A large amount of electric power is required to maintain the temperature of the fixing device above the softening point of the toner.

(3) If the temperature of the fixing device is set too high in order to increase the speed, there is a risk of burning the copy paper or, in the worst case, a fire.

On the other hand, there have also been proposals to lower the temperature of the fixing device by using toner with a low softening point or toner that can be fixed only by pressure, thereby increasing the speed.

For example, Japanese Patent Publication No. 44-9880 discloses a pressure-fixable toner comprising an aliphatic component of 06 to C25;
No. 32, JP-A-48-75033, JP-A No. 48-7893
No. 1, No. 48-78936, etc. each contain descriptions of electrostatic photographic developers made of soft polymers, but in order to make these developers using the conventional pulverization method, (1) from the viewpoint of pulverizability; It must be frozen to a temperature below the embrittlement point and then crushed.

(2) Toners made using this method have a particle size distribution force, which increases manufacturing costs due to the need to make particle sizes uniform through classification, and also causes problems in these toners. (4) adhesion with carrier particles; and (5) formation of a film-like stain on the electrostatic latent image holding surface, which may cause problems when used repeatedly.

The present invention eliminates the above-mentioned drawbacks and provides a method for producing a pressure fixable toner at low production cost.

Further, the present invention provides a method for producing a pressure fixable toner that does not cause problems such as curdling or caking, and therefore does not cause any contamination on the surface of an electrostatic latent image.

Furthermore, the present invention provides a practical method for producing a pressure-fixable toner that can be fixed even with a low pressure.

The method for producing the toner of the present invention is to emulsify a hydrophobic polymerizable monomer capable of forming a soft polymer in an aqueous solution containing a polymerization initiator, polymerize it (hereinafter referred to as first polymerization), and then add film-forming properties to the resulting toner. A polymerizable monomer capable of forming a polymer substance and a water-soluble polymerization initiator are added if necessary, polymerization is performed again (hereinafter referred to as "second polymerization") to prepare a composite polymer latex, and then the polymer latex is spray-dried. At this time, a coloring agent is mixed into at least one of the first polymerization reaction system, the second polymerization reaction system, and the composite polymer latex.

By this method, a capsule toner can be obtained in which a soft polymer is used as a core material, a film-forming polymer material is used as an outer wall, and a colorant is contained in at least one of the core material and the outer wall.

As the polymerization initiator, a redox initiator consisting of an oxidizing agent and a reducing agent is used.

Naoko＼What is composite polymer latex?21st (19th)
1972) and the 24th Polymer Symposium (1975), it refers to a polymer latex containing two or more polymer components in a layered manner.

The soft polymer constitutes the core material of such composite polymer particles, is obtained by emulsion polymerization of the polymerizable monomer for the first polymerization as described above, and has pressure adhesive properties at room temperature.

Examples of such soft polymers include acrylic ester oligomers such as oligoethyl acrylate and oligobutyl acrylate, methacrylic ester oligomers, copolymerized oligomers of acrylic acid and long-chain alkyl acrylate,
Copolymerized oligomer of acrylic acid and long-chain alkyl acrylate, copolymerized oligomer of acrylic acid and long-chain alkyl methacrylate, copolymerized oligomer of methacrylic acid and long-chain alkyl acrylate, copolymerized oligomer of methacrylic acid and long-chain alkyl methacrylate , a copolymerized oligomer of styrene and long-chain alkyl acrylate, a copolymerized oligomer of styrene and long-chain alkyl methacrylate, a copolymerized oligomer of styrene and butadiene, and the like.

In addition, the film-forming polymeric substance constitutes the outer wall of the composite polymer particles, and as mentioned above, it is obtained by polymerizing the polymerizable monomer for the second polymerization, and unlike soft polymers, it has adhesive properties under pressure at room temperature. I don't.

Examples of such polymeric substances include polystyrene, styrene acrylate copolymer, styrene rubinyl ether copolymer, styrene-acrylonitrile copolymer, styrene-halo-coelectrovinylidene copolymer, polyvinyl acetate, or their binary or Vinyl polymers or copolymers such as terpolymers can be used.

Pigments and dyes such as carbon black are used as colorants.

The content of the core material is suitably 20 to 80% by weight, preferably 45 to 55% by weight, based on the toner.

If it is less than 20% by weight, pressure fixing properties will be poor, and if it is more than 80% by weight, granulation properties will be poor.

Note that the content of the colorant is not particularly limited.

According to the method of the present invention, since a polymerizable monomer is polymerized on the surface of a soft polymer obtained by emulsion polymerization, a capsule toner with a uniform particle size can be obtained. In addition to being inexpensive, the soft material can be completely encapsulated and isolated, which prevents agglomeration, bridging, caking, adhesion with carrier particles, and contamination of the electrostatic latent image holding surface during storage and use. In addition, a capsule toner that can be destructively fixed with low pressure can be obtained.

Furthermore, since the process of the present invention is carried out entirely in an aqueous system from the emulsification process to the spray drying process, there are no problems associated with solvent treatment, such as explosion-proof equipment, solvent recovery, etc., compared to methods using organic solvents, and production costs are reduced. It's advantageous.

Examples are shown below.

Example 1 Potassium persulfate 1.08? , sodium thiosulfate hydrate i
, ooy, aqueous solution containing 0.0031' of sulfuric acid steel 80
0R1 was heated to 70 to 75°C, and emulsion polymerization was performed by adding butyl acrylate 51' while stirring.

After the polymerization was completed, styrene 50S' was added and emulsion polymerization was performed again to prepare a composite polymer latex.

Next, an emulsifier and water-dispersible carbon black (Colloidex A5, manufactured by Columbia Carbon Co., USA) 10 Y were added to this composite polymer latex, and after uniformly dispersing it to form a slurry, it was heated to an inlet temperature of 135°C and an outlet temperature of 85°C using a Niro atomizer. The slurry was spray-dried at a spray pressure of 5.6 kg/crA (as compressor pressure) to obtain a pressure-fixable toner containing carbon black on the outer wall.

Example 2 A pressure fixable toner was obtained in the same manner as in Example 1 except that a mixture of styrene/butyl methacrylate (mole ratio)=7/3 was used instead of styrene.

Example 4 An aqueous solution containing 1.01' potassium persulfate, 1 sodium thiosulfate, OOg, and 0.0036 f copper sulfate at 80 omA'
was stirred, and 50 g of lauryl acrylate was added thereto to perform emulsion polymerization.

After polymerization, potassium persulfate 0.216P and styrene 50P
Then, emulsion polymerization was carried out again to obtain a composite polymer latex, which was then treated in the same manner as in Example 1 to obtain a pressure fixable toner.

Example 5 A pressure fixable toner was obtained in the same manner as in Example 4 except that a mixture of styrene/butyl methacrylate (mole ratio) = 7/3 was used instead of styrene.

An electrostatic latent image formed on a commercially available electrophotographic material using the toner of each example obtained as described above was developed and transferred, and then fixed using a variable pressure steel fixing roller. A clear fixed image was obtained at a pressure of 3.3 to 3.8 kg/mu.

Note that all of these toners had low cohesiveness and excellent fluidity.

On the other hand, for comparison, a toner was prepared according to the method described in Examples of JP-A-48-75032.

That is, chloroform-cyclohexane mixed solvent 45CH in a volume ratio of 4:3; polystyrene (PS-2 manufactured by Dow Chemical Company, USA) 24r and phenol-formaldehyde resin (ERLB-044 manufactured by Union Carbide Company, USA).
9) 24 P was dissolved to prepare a resin mixed solution.

2.5 P of carbon black (Peerless 155, manufactured by Columbia Carbon Co., USA) was added to this solution and uniformly dispersed with a homomixer.

Next, this dispersion was heated using a Niro atomizer at an inlet temperature of 6.
8℃, outlet temperature 53℃, compressor pressure 6kg/c
A comparative pressure fixing toner was obtained by spray drying under wt conditions.

Below, fixing was carried out in the same manner as in Example 1.
Only a vague fixed image could be formed at a pressure of kg/mm.

Note that the toner particles showed a tendency to aggregate.

Claims (1)

[Claims] 1. A hydrophobic polymerizable monomer capable of forming a soft polymer is emulsified in an aqueous solution in which a polymerization initiator is dissolved, and after a first polymerization reaction is carried out, a film-forming polymeric substance is added to this. When adding a polymerizable monomer capable of forming a polymer and performing a second polymerization reaction to prepare a composite polymer latex, and then spray drying this polymer latex, the first polymerization reaction system, the second polymerization reaction system, and the composite polymer latex at least 1 of
A method for producing a pressure-fixable toner, which comprises mixing a colorant into a toner. 2 The soft polymer is an acrylic ester oligomer, a methacrylic ester oligomer, a copolymerized oligomer of acrylic acid and a long-chain alkyl acrylate, a copolymerized oligomer of acrylic acid and a long-chain alkyl methacrylate, a copolymerized oligomer of methacrylic acid and a long-chain alkyl acrylate A group consisting of oligomers, copolymerized oligomers of methacrylic acid and long-chain alkyl methacrylate, copolymerized oligomers of styrene and long-chain alkyl acrylate, copolymerized oligomers of styrene and long-chain alkyl methacrylate, and copolymerized oligomers of styrene and butadiene. The method according to claim 1, which is one selected from. 3. The method according to claim 1 or 2, wherein the film-forming polymeric substance is a vinyl polymer.