JP2999574B2 - Flash fixing toner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flash fixing toner used for developing an electrostatic latent image in electrophotography and the like. Conventionally, as an electrophotographic method, a method described in U.S. Pat. No. 2,297,691 is well known, which generally uses a photoconductive insulator (such as a photo-condrum) and uses a photoconductive insulator such as a corona discharge. An electrostatic latent image is formed by applying a uniform electrostatic charge to a conductive insulator and irradiating a photo image on the photoconductive insulator by various means, and then forming the latent image into a fine image called toner. Visualize the development using powder, transfer the toner image to paper etc. as necessary, and fix the toner image on a recording medium such as paper by means of pressure, heating, irradiation of solvent, vapor, light, etc. To obtain a copy.

[0002]

2. Description of the Related Art As a toner for developing these electrostatic latent images, a coloring agent such as carbon black is conventionally dispersed in a binder resin made of a natural or synthetic polymer. 5
Particles finely pulverized to about 20 μm are used. Such a toner is usually used alone or in combination with a carrier material (carrier) such as iron powder or glass beads for developing an electrostatic latent image.

When the toner is used alone for development (one-component developing method), the toner usually contains magnetic powder,
The toner is frictionally charged by being rubbed against a wall of a developing device or a member of a developing roll in the developing device, and further, is held on the developing roll by a magnetic force of a magnet included in the developing roll, and the developing is performed. As the roll rotates, the toner is carried to the latent image portion on the photoconductive insulator, and only the charged toner adheres to the latent image by electric attraction, thereby performing development.

When a carrier and a toner are mixed and used (two-component developing method), a developer composed of the toner and the carrier is frictionally charged by mixing and stirring in a developing device, and the toner is carried on the carrier. In this state, the toner is transferred to the latent image portion on the photoconductive insulator, and only the charged toner is selectively adhered to the latent image by an electric attraction, thereby performing development. Also in this case, the toner image is formed only with toner.

In the case of the two-component developing method, iron powder or other ferromagnetic particles are usually used as the carrier in many cases. In this case, the magnetic particles are held by a developing roll in a developing device and a magnetic brush is used. When the developing roller rotates, the magnetic brush is carried to the latent image portion on the photoconductive insulator, whereby the toner is transported to the latent image portion.

On the other hand, as a binder resin used for the toner, a low polymer is generally used in many cases.
Further, the fixing is to fuse the toner powder image and fix it on the recording paper, and there are various methods as described above. Among these methods, flash fixing, which is a typical example of light fixing, is a method of fixing by flash of a discharge tube such as a xenon flash lamp. (1) Non-contact fixing, and Does not degrade image resolution, (2) no waiting time after power-on, quick start is possible, (3) fire does not occur even if recording paper jams in fixing unit due to system down
(4) It has a great feature that it can be fixed irrespective of the material and thickness of the recording paper, such as glued paper, preprinted paper, and paper of different thickness.

The process in which the toner is fixed to the recording paper by flash fixing is as follows. First, as described above, when the toner image is transferred to the recording paper, the toner is adhered as it is to the powder to form an image. When a flash of a discharge tube such as a xenon flash lamp is irradiated there, the toner becomes
The temperature rises by absorbing the energy of the flash, softens and melts, and adheres closely to the recording paper.

After the end of the flash, the temperature decreases and solidifies to form a fixed image, and the fixing is completed, and the fixed image fixed on the recording paper does not collapse even when rubbed with a finger, for example.
What is important here is that the toner melts and adheres firmly to the recording paper. For this purpose, the toner absorbs light energy from the flash, including heat energy that does not dissipate to the outside world and contribute to temperature rise. Must be sufficiently melted.

Therefore, if the applied light energy is insufficient, the toner cannot be sufficiently melted, and satisfactory fixability cannot be obtained. Generally, in flash fixing, the upper layer of the toner, which receives irradiation energy at the time of flash light irradiation, instantaneously becomes a high temperature state of 200 ° C. or more. However, unlike the fixing method such as heat roll fixing, the supply of irradiation energy is not continuous. Therefore, when a substance having a high heat of fusion is used as a toner constituent substance, the melting point of the substance is 20%.
Even if the temperature is 0 ° C. or less, the compound does not sufficiently dissolve, and causes poor fixing.

For this reason, in flash fixing, the heat of the upper layer of the toner, which has become high temperature due to the irradiation energy, penetrates to the lower layer of the toner by heat conduction, and the toner in the lower layer of the toner melts and penetrates into the recording medium. As a result, the toner is fixed. For this reason, in the flash fixing method, it is necessary to apply energy for heating the upper layer portion of the toner to a temperature far exceeding the melting point of the toner component by flash light irradiation.

This is problematic in that it is uneconomical in terms of energy, and the toner constituents in the upper layer of the toner undergo heat / photolysis upon receiving strong irradiation energy, and produce an unpleasant odor depending on the material of the toner constituents. There is. Also, as the toner component material, the toner for flash fixing must be softened more than the binder resin used for the hot roll fixing toner because the toner must be melted by the amount of heat reaching the lower layer of the toner by heat conduction and penetrate into the recording medium. Low-polymer low-temperature polymers are commonly used.

As a further problem caused by this, a toner composed of a low-polymer polymer having a low softening temperature, which is commonly used as a flash fixing binder, has a problem that when exposed to a high temperature environment, the toner surface becomes soft and the toner becomes soft. There is a problem that so-called blocking in which particles are associated with each other easily occurs. When such blocking occurs, the fluidity of the toner is extremely reduced, so that not only the toner is not supplied smoothly to the developing device, but also the toner characteristics such as the particle diameter change, so that the charging characteristics of the toner also change. And appropriate development cannot be performed.

The present invention has been made in view of the above-mentioned conventional problems, and provides a flash fixing toner which exhibits good fixability with a small irradiation energy and has excellent blocking resistance. The purpose is to:

[0014]

According to the present invention, an essential component of the toner is a heat of fusion of 20 cal / g or less and a melting point of 200 ° C.
Using a polyolefin compound having the following physical properties, the energy of flash light irradiation causes the polyolefin compound to melt instantly and penetrate into the recording paper, thereby increasing the penetration of the entire toner into the recording paper. As a result, Good fixability to recording paper was imparted to the entire toner.

Considering the toner fixing step in the flash fixing step in a time series, (1) flash light irradiation step;
When flash light is applied to the toner, the toner absorbs the energy of the flash light and generates heat. The surface of the toner becomes extremely hot instantaneously. (2) Heat conduction / penetration process; Conduction, the entire toner softens and melts and penetrates the recording medium; (3) cooling / fixing process; the toner temperature decreases and solidifies to form a fixed image. By adding a polyolefin compound having a heat of fusion of 20 cal / g or less and a melting point of 200 ° C. or less according to the present invention, the following effects are obtained.

(1) In the flash light irradiation process,
By adding a polyolefin compound having a heat of fusion of 20 cal / g or less and a melting point of 200 ° C. or less to the toner of the present invention, the heat of fusion required for melting the toner is reduced, and the toner is sufficiently dissolved even with weaker flash light irradiation than before. As a result, the fixability of the toner is improved. (2) In the flash light irradiation process, the polyolefin compound according to the present invention melts more quickly than other toner constituent materials, and exhibits a low melt viscosity when dissolved. It penetrates the recording medium beforehand and increases the wettability between the toner and the recording medium.

For this reason, the permeability of the toner that subsequently melts and penetrates into the recording medium is increased. Therefore, the fixing property of the toner is improved. The heat of fusion shown in the present invention is 20 cal / g.
Hereinafter, the addition amount of the polyolefin compound having a melting point of 200 ° C. or less is 1 to 20% by weight based on the toner.
In particular, the content is preferably 3 to 10% by weight.

This is because if the amount is less than this, the effect of the present invention cannot be obtained. If the amount exceeds this, the cohesive force between the toner binders is weakened, and the mechanical strength of the toner image after fixing is reduced. It is. The melt viscosity of the polyolefin compound at 200 ° C. is desirably 1000 cP or less. This is because if the melt viscosity exceeds this value, the permeability to the recording medium is reduced, and the effect of the present invention is reduced.

By using a polyolefin compound having a melting point of 150 ° C. or higher, the blocking resistance of the toner is significantly improved. This is because, as described above, the material generally used for the flash fixing toner binder is a low-polymerized polymer having a low softening temperature and a glass transition temperature of 65 ° C. or lower.
The polyolefin has excellent thermal stability.

The toner used in the present invention can be produced by a conventionally known method. That is, the polyolefin compound, the binder resin, the colorant, the inorganic filler and the charge control agent, if necessary, are kneaded and melted by a pressure kneader, a roll mill, an extruder, etc., uniformly dispersed, and then pulverized by a pulverizer such as a jet mill. And classifying it with a classifier, for example, an air classifier, to obtain a desired toner.

After the conventional flash fixing toner is manufactured, a predetermined amount of the fine powder of the polyolefin compound according to the present invention is charged together with the toner into a mixer such as a super mixer or a Henschel mixer, and the mixer is rotated for a short period of time to rotate the toner surface. The effect of the present invention can also be achieved by a so-called external addition method in which the polyolefin compound is adhered to the surface. The specifications of the device, such as the printing speed of a printing device such as a printer,
If the composition is different, the fixing properties and blocking resistance required for the toner are slightly different.However, when the polyolefin compound of the present invention is added by an external addition method, fixing is performed by controlling the material and the amount of the external addition of the polyolefin compound. It is possible to control the toner characteristics such as durability and blocking resistance, so that it is not necessary to design a new toner material for each printer, and one type of reference toner is used for each printing device having different required characteristics. Is possible, and the economic merit is great.

[0022]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the present invention is limited thereto. Example 1 An epoxy resin (Epiclon EXA) was used as a binder resin.
85 parts by weight of -1191; Dainippon Ink and Chemicals, 8 parts by weight of a polyolefin wax (DX-018; manufactured by Mitsui Petrochemical Industries) exhibiting physical properties of a melting point of 187 ° C., a heat of fusion of 5 cal / g, and a melt viscosity of 100 cP at 200 ° C. , Nigrosine dye (Bontron N-04; manufactured by Orient Chemical)
3 parts by weight and 4 parts by weight of carbon (Vulcan XC-72; manufactured by Cabot) were added, and the mixture was heated at 130 ° C. and 30 ° C.
Then, the mixture was melted and kneaded to obtain a toner mass. The cooled toner mass was made into a coarse toner of about 2 mm by a rotoplex grinder. Next, the coarse toner is jet-milled (PJM pulverizer;
Fine pulverization was performed using Nippon Pneumatic Industrial Co., Ltd.), and the pulverized product was classified using an air classifier (manufactured by Alpine) to obtain a positive toner A having a particle size of 5 to 20 μm.

Next, a developer comprising 5 parts by weight of these toners and 95 parts by weight of amorphous iron powder TSV100 / 200 (manufactured by Nippon Iron Powder) as a carrier is prepared, and a FACOM-Flush-fixing system is used. A printing test and a fixing test were performed using a 6715D laser printer. At this time, the thickness of the toner on the recording paper was set to 10 to 15 μm. For the fixing device, a capacitor having a capacity of 160 μF is used, and the capacitor charging voltage is set to 100 V from 1500 to 2500 V.
By changing the step, the energy applied to the flash lamp was changed, and the relationship between the intensity of the flash light irradiation and the fixability of the toner was evaluated.

Regarding the fixing strength, an adhesive tape (Scotch Mending Tape, manufactured by Sumitomo 3M) was lightly applied on the fixed image, and an iron cylindrical block having a diameter of 100 mm and a thickness of 20 mm was fixed on the tape at a constant speed in the circumferential direction. Is adhered to the recording paper, and then the tape is peeled off. The ratio of the optical density after peeling to the optical density of the image before tape peeling is expressed as a percentage, and a value of 80% or more is evaluated as good fixability. did. The optical density was measured using a PCM meter manufactured by Macbeth.

Further, regarding the evaluation of the blocking property, φ5
A 0 mm container was filled with 50 g of the toner, and after being exposed to the evaluation environment for 12 hours, the state of aggregation of the toner was visually evaluated to evaluate. In these evaluations, it was confirmed that Toner A exhibited good fixability at a capacitor charging voltage of 1800 V and did not cause blocking even in a 55 ° C. environment. Example 2 As a binder resin, 88 parts by weight of an epoxy resin (R-304; manufactured by Mitsui Petrochemical Industries), 3 parts by weight of a nigrosine dye (Bontron N-04; manufactured by Orient Chemical), carbon (Vulcan XC-72; manufactured by Cabot) 4 parts by weight were added, and the mixture was melted and kneaded at 130 ° C. for 30 minutes using a pressure kneader to obtain a toner mass. The cooled toner mass was made into a coarse toner of about 2 mm by a rotoplex grinder. Next, the coarse toner is finely pulverized using a jet mill (PJM pulverizer; manufactured by Nippon Nippon Machima Kogyo Co., Ltd.), and the pulverized material is classified by an air classifier (manufactured by Alpine) to obtain a positive toner having a particle size of 5 to 20 μm. Obtained.

To this toner, 3 parts by weight of a polyolefin wax (DX-018; manufactured by Mitsui Petrochemical Industries) showing physical properties of a melting point of 187 ° C., a heat of fusion of 5 cal / g, and a melt viscosity at 200 ° C. of 100 cP was added, and a Henschel mixer was added. Was mixed and stirred to obtain a flash fixing toner B to which the polyolefin wax was externally added. When the same evaluation as that of Example 1 was performed on the toner B,
It shows good fixability at a capacitor charging voltage of 1900V,
In addition, it was confirmed that no blocking occurred even in a 65 ° C. environment. Comparative Example 1 The same evaluation as in Example 1 was performed on the toner (toner C) before externally adding the polyolefin wax.
In order to exhibit good fixing properties, a capacitor charging voltage of 2300 V was required, and the blocking temperature was 45 ° C. Comparative Example 2 A toner D was obtained in the same manner as in Example 1 except that the content of the polyolefin wax was changed to 1% by weight.

The same evaluation as in Example 1 was performed on this toner.
A capacitor charging voltage of 2200 V was required and the blocking temperature was 45 ° C. Comparative Example 3 Toner E was obtained in the same manner as in Example 1, except that the content of the polyolefin wax was changed to 25% by weight. Since the toner E has a low charging ability, background stain on the printing background portion was conspicuous. When the same evaluation as in Example 1 was performed on this toner, the blocking temperature was 65 ° C. Regarding the fixability, peeling occurred due to the low strength of the fixed toner binder, and no region showing good fixability was observed in the evaluation capacitor charging voltage range. Comparative Example 4 Polyolefin wax having a melting point of 87 ° C. and a heat of fusion of 1
Toner F was obtained in the same manner as in Example 1, except that a polyolefin wax (DT-017; manufactured by Mitsui Petrochemical Industries) having physical properties of 5 cal / g and a melt viscosity at 200 ° C of 100 cP or less was used. When the same evaluation as in Example 1 was performed on this toner, a capacitor charging voltage of 1900 V was required to exhibit good fixing performance. Is 45
° C, and no effect of improving blocking resistance was observed.

[0028]

As described above, according to the present invention, good fixability can be obtained with a slight irradiation energy, and blocking resistance is excellent.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-1-234857 (JP, A) JP-A-58-215660 (JP, A) JP-A-4-282640 (JP, A) JP-A-4-234 186250 (JP, A) JP-A-4-277752 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 9/08

Claims (2)

(57) [Claims] 1. A flash fixing toner using a binder resin, wherein the binder resin has a heat of fusion of 20 cal / g.
Hereinafter, melting point contains a polyolefin compound having the following physical properties 200 ° C. 0.99 ° C. or higher, the polyolefin compound
Said polyolefin having a content of
The compound has a melt viscosity at 200 ° C of 1000 cP or less.
A toner for flash fixing, characterized in that: 2. The method of claim 1, wherein the polyolefin compound according to claim 1 is externally added.
Characterized in that the toner adheres to the toner surface by
Brush fixing toner.