JPS62280784A - Image fixing method - Google Patents

Abstract

PURPOSE:To improve fixing energy efficiency, prompt fixability, resistance to environmental change, reliability in repetitive use and safety by using a developer contg. a thermoplastic polyamide resin and combining such developer with a fixing method in which the exertion of pressure and the radiation of light are used in conjunction. CONSTITUTION:The developer contg. a coloring agent and the thermoplastic polyamide resin as a binder resin component is used. The pressure is exerted to the developed or transferred toner image on a material to be recorded to embed the toner into, for example, the spaces among paper fibers or to improve the contact of the fibers and the other materials. The light is then applied to the image to put the thermoplastic polyamide resin in the toner into the molten state by the heat generated in the toner so that the resin is made to flow easily on the paper fibers and the other materials. Since the time when the light is applied is about 10<-3>sec order, the thermoplastic polyamide resin solidifies before the resin flows to disturb the toner image. The toner is thus securely fixed onto the material to be recorded.

Description

[Detailed Description of the Invention] 3. Detailed Description of the Invention Field of Industrial Application The present invention visualizes electrical latent images, magnetic latent images, etc.
Directly responds to electrical signals, etc. without forming a latent image,
The present invention relates to a method of fixing a toner image formed by image formation or transfer onto a recording material such as paper, cloth, or film.

Conventional technology Magnetic recording methods, such as electrophotography, electrostatic recording, or magnetography, usually form electrical or magnetic latent images, such as electrostatic latent images. The latent image is visualized using a developer called toner. A method is also known in which an image is formed by depositing a developer called toner, solid ink, or the like directly onto a base material such as paper in response to an input electrical signal or the like. Compared to chemical recording methods and color recording methods such as diazo recording and heat-sensitive pressure-sensitive color recording, the method of forming colored images using such a developer has no restrictions on recording materials such as paper; The storage stability of records is also good, and in recent years it has become the mainstream of hard copy records.

The developed image is then fixed with or without a transfer step. For example, to fix the image,
Currently, in the case of electrophotographic recording, which is the mainstream of plain paper copiers and high-quality high-speed printers, toner is softened or deformed by heat, light, pressure, solvents, ultraviolet rays, electron beams, radiation, etc. ing.

Problems to be Solved by the Invention However, in the case of colored recording using toner, etc., conventional fixing methods have several drawbacks, as shown in Table 1, and it is difficult to obtain a method that is satisfactory in all respects. It has not been done.

The evaluation in Table 1 is Good←O〉△〉X→Poor.As can be seen from Table 1, the heat roll fixing method (hard roll, soft roll) currently used in many electrophotographic copying machines is Although thermal efficiency is the highest for thermal fixing, approximately 50% or more of the power consumption of a copying machine is still used in this heat roll fixing process. Furthermore, since it takes several tens of seconds or more for the initial heating of the thermo roll, the copying machine cannot be used immediately after being turned on.

Furthermore, since the toner is heated and fixed by bringing the toner into contact with the hot roll, the toner may offset to the hot roll and contaminate the final image, or the toner may flow excessively on the recording material such as paper. This has disadvantages such as making the image thicker and making it shine more brightly than necessary.

On the other hand, in the case of radiant fixing, which heats the image without contacting the toner, excessive thickening of the image and unnecessarily glossy images are less likely to occur, but thermal efficiency is poor and high-speed processing is not possible. Furthermore, paper burning problems are likely to occur.

Conventionally, when heat fixing is used, vinyl resins such as epoxy resins, styrene resins, and acrylic resins are generally used as binder resins for developers. In particular, in the case of hot roll fixing, it is necessary to make the weight average molecular weight of the binder resin sufficiently larger than the critical molecular weight, or to have a partially crosslinked structure to prevent image deterioration due to hot roll contamination. It is being done. However, these methods have a problem in that the softening point of the toner is increased and the temperature of the heat fixing device must be set high. Therefore, as described above, it takes time to warm up the thermal fixing device, and the fixing device also consumes a large amount of power.

On the other hand, optical fixing methods using xenon flash lamps, etc. can be started immediately, and the toner image area absorbs energy at the time of selection, so there is less energy loss and risk of paper burning than with radiant fixing, but Since the energy absorption properties are different between the black image area and the line image area, it is difficult to maintain a constant fixing level for both areas, and it is usually necessary to instantaneously apply high energy of about 1.5 to 3 J/c11i. Therefore, a high-power dedicated power source is required, resulting in high power consumption and a high price of the fixing device.

Optical fixing is a method of fixing toner by selectively absorbing the energy of flash light, mainly in the infrared region, with carbon black, magnetite, and other infrared-absorbing substances in the toner, which absorbs excessive energy. Then, the energy absorbing portion instantly becomes high temperature of around 400°C. Therefore, if the applied or absorbed energy is too high, the toner will decompose, emit a bad odor, pollute the environment, and cause the image area to become bubbly or scattered.

In some cases, the viscosity of toner that has absorbed energy becomes extremely low, and the surface tension of the donor acts more strongly than it penetrates into paper, etc., resulting in thin lines in the fixed image or a decrease in image density. It has disadvantages such as Of course, if the applied or absorbed energy is too low, poor fixing will occur.

The light fixing method certainly has many advantages compared to radiant fixing, but heat roll fixing is still not as efficient.
For example, it is difficult to fix toner with low energy of 1 to 1.5 J/cm or less. In addition, even with the same toner, energy absorption is different between the solid black image area and the line image area, as mentioned repeatedly, and furthermore, because the fine powder part of the toner is more easily fixed than the coarse powder part, the energy absorption is different over the entire image area. It is extremely difficult to guarantee uniform and good fixing performance.

Further, in the case of optical fixing, it is difficult to select a toner binder resin that is stable at high temperatures of 300° C. to 500″C, and that is easy to flow and has an affinity with the recording material.

For example, polyamide resin is known as a resin for optical fixing, but when it is included in a binder resin to form a magnetic toner, sufficient fixing strength cannot be obtained by optical fixing.

The reason for this is thought to be that only the magnetic powder absorbs the optical energy, so the resin does not melt sufficiently. Another reason is that containing magnetic powder increases the viscosity of the toner, and even if the toner is melted by light energy, sufficient fluidity is not imparted to the toner, resulting in poor adhesion to paper. Conceivable. Furthermore, if enough light energy is applied to provide sufficient fluidity, the resin will decompose and produce a strange odor, making it unusable.

On the other hand, in the case of resins other than polyamide, if the resin has a molecular weight that can be used for toner, the resin will have a high viscosity if light energy is below the decomposition level of the resin, and if light energy is applied to give the fluidity necessary for fixing the toner, the resin will become viscous. decomposes,
Image disturbances occur due to bubbling, etc.

Pressure fixing, which has been attracting attention in recent years because it can be started immediately and consumes less power, cannot achieve a sufficient fixing level of 1q.

For example, the fiber gap of paper is around 10μ, which is almost the same as the toner particle size, so the toner that has entered the paper fiber gap is applied with a pressure of a fixing roll, for example, about 150 kg/cm. Even if pressure is applied, the stress is not transmitted and the toner is not fixed. In order to achieve sufficient fixation, high pressure is required, usually two or three metal rolls are used, and the pressure is approximately 150 to 200 kg/cm for the toner.
Since the high pressure of the waste is applied and the toner is crushed, the strength of the fixing roll becomes a problem, and the weight of the fixing device becomes 9 or more, usually about 10 kg, which is very heavy.

Furthermore, fixed images tend to become thick and glossy due to excessive deformation of the toner, and slight fluctuations in fixing conditions can cause wrinkles or tearing of the paper. .

In addition, it is well known that polyamide resin is used as a binder resin in developers used when pressure fixing is used, but since strong hydrogen bonds work between molecules in the solid state, even those with relatively low molecular weight can be used. It exhibits high polymer strength and has the disadvantage that sufficient fixing performance cannot be obtained by pressure alone unless the fixing pressure is set quite high.

In addition, in order to enable plastic deformation and viscoelastic deformation at room temperature, the binder resin may contain, for example, aliphatic components, other wax-like materials, weakly cross-linked polymers such as ionomers, other rubber-like resins, adhesives, etc. Addition of imparting agents, liquid additives, etc. is also practiced. However, toners containing these pressure-sensitive deformable materials have problems in manufacturing, such as offset to the pressure roller, deterioration of the toner due to repeated use, adhesion to the carrier when using a coarse carrier, and metal It has many disadvantages, such as sticking to the sleeve or the surface of the photoreceptor, clumping during storage, and not being transported to the sleeve.

Considering the safety issues and processing speed, solvent fixing is
The problem is that it can only be applied for special purposes.

In addition to these, fixing methods that employ high-frequency dielectric heating or electromagnetic induction heating as heating means have also been proposed, but even if the heating means is changed, all of the basic shortcomings of the heat fixing methods described above are improved. Do not mean.

It is also conceivable to fix a special toner using ultraviolet rays, electron beams, radiation, etc., or to promote fixation, but this has little overall advantage in terms of image forming characteristics and cost.

Accordingly, an object of the present invention is to provide an image fixing method that ensures good fixing performance while consuming less energy.

Another object of the present invention is to provide an image fixing method that can be started immediately and ensures good fixing performance.

Still another object of the present invention is to provide an image fixing method that ensures good fixing performance at high speed.

Still another object of the present invention is to provide an image fixing method that guarantees excellent image quality that is faithful to the developed image.

Still another object of the present invention is to provide an image fixing method that is highly reliable and safe in the face of environmental changes and repeated use.

Means for Solving the Problems As a result of intensive studies, the present inventors used a developer containing a thermoplastic polyamide resin based on dimer acid (hereinafter referred to as thermoplastic polyamide resin) as a binder resin. It has been discovered that by combining a pressure fixing method and a light fixing method, it is possible to stably and safely obtain a fixed image of extremely good quality with low energy consumption and immediate start-up.

That is, in the present invention, an image obtained by developing or transferring onto a recording material such as paper using a developer containing a thermoplastic polyamide resin as a binder resin component is applied with pressure and then irradiated with light. This method is characterized by applying pressure after irradiation with light or by applying pressure after irradiation with light, whereby extremely excellent fixing properties can be obtained.

The present invention will be explained in more detail below.

The toner image fixed in the present invention is formed on a recording material such as paper, cloth, film, etc.
Images formed by developing an electrical or magnetic latent image with a developer, those formed by applying a developer directly in response to an electrical signal, and those formed by electrostatic transfer. It may be either.

The developer used to form the fixed toner image in the present invention is composed mainly of a colorant and a binder resin, and at least a portion of the binder resin must be a thermoplastic polyamide resin. It is.

Among the above thermoplastic polyamide resins, preferred ones are:
It has a softening point of about 40°C to 200°C, more preferably about 45 to 150°C, and has a relatively low molecular weight. A thermoplastic polyamide resin having these characteristics exhibits a certain degree of pressure-sensitive deformability and melt viscosity when fixed by pressure and light according to the present invention, and is firmly fixed on a recording material.

Thermoplastic polyamide resins have a viscosity that rapidly decreases to 1 to 20 poise at temperatures above their softening point, excellent thermal stability during melting, and a fast assimilation rate during cooling. This characteristic indicates good wettability to adherends such as paper and fast fixing speed. Therefore, there is no increase in line thickness due to the flow of toner, and there is no reduction in resolution due to contact between lines.

It also shows that it is less likely to peel off, making it advantageous as a binding substance for toner. Furthermore, since it has excellent thermal stability, the resin is less likely to decompose due to light irradiation and does not generate any strange odor.

In the present invention, a polar functional group may be introduced into the polyamide resin in order to improve its affinity with paper, or the polyamide resin may be used in combination with other resins.

In order to promote the absorption of light energy, particularly energy in the infrared region, the developer of the present invention needs to contain carbon black, magnetite or other infrared absorbing agent, or it needs to be attached to the surface of the toner particles.

For example, when carbon black is used both as a colorant and as an infrared absorbing agent, it is desirable that the toner contains about 3 to 15% by weight of carbon black.

When externally attached to the surface of toner particles, 0.1% by weight to 3. It may be within the range of 0% by weight. Further, when magnetite is used, sufficient effects can be achieved by adding it to the toner in an amount of about 30 to 70% by weight. When using other infrared absorbers or when using two or more kinds in combination, the amount to be added can be determined experimentally as described above.

In addition to these, toner also contains various colorants, charge control agents,
Foaming agent, antioxidant, reinforcing agent, plasticizer, magnetic material, frame 1/
Non-crosslinked resinous materials and the like can be added.

In order to further improve the electrical properties, powder fluidity, storage stability, etc. of the developer, or to prevent the toner from filming on the photoreceptor, or to improve the cleaning properties of the toner. Other external additives may be added and attached to the surface of the toner particles for the purpose of improving the toner particles.

These external additives include long chain fatty acids such as stearic acid and their esters, amides, metal salts, molybdenum disulfide, carbon black, graphite, graphite fluoride, silicon carbide, boron nitride, silica, aluminum oxide, Examples include fine powders of titanium dioxide, zinc oxide, etc., fine powders of fluororesins, polycyclic aromatic compounds, waxy substances, crosslinked or non-crosslinked resin fine powders, etc., and are usually not limited to critical surface tension. 30 d 'J n /
It has a low surface energy of less than cm or a direct-to-farm coefficient of 0.
．． They are solid fine particles with a smooth surface of 1 or less, or fine particles that are non-adhesive and have some abrasive properties. Further, if necessary, a treatment for fixing these external additives to the surface of the toner particles using hot air or the like may be performed.

The developed toner image or transferred toner image on a recording material such as paper, cloth, or film obtained using the thermoplastic polyamide resin-containing developer is fixed by a combination of pressure application and light irradiation. , pressure application and light irradiation may be performed in any order. That is, first, pressure may be applied and then light irradiation may be performed, or pressure may be applied after light irradiation has been performed.

In order to eliminate the deterioration of the fixed image due to toner crushing, which is a drawback of the conventional method of applying pressure, and to alleviate problems such as the weight of the fixing device and paper wrinkles and paper breaks during fixing, the pressure application in the present invention is as follows: Applied pressure during fixing is approximately 30
to 150 KFl/ctri, preferably 60 to 12
0 K! j/ctA, more preferably 120-100
Set below Kg/Cm.

The pressure is applied by a fixing roll, but in the present invention, since the applied pressure is relatively low as mentioned above, it can be applied not only to iron alloy metal rolls but also to lightweight metal rolls such as aluminum, alloys, and plastic rolls. can be used.

Further, in the present invention, the light irradiation is carried out by a conventional method, and the irradiation amount is 0.3 to 15.5 J/cti, preferably 0.5 to 1.5 J/cti. What is necessary is to apply optical energy (capacitor storage energy) of O.J/cri.

Function In the fixing method of the present invention, when pressure is first applied and then light irradiation is performed, first, by applying pressure to the developed or transferred toner image on the recording material, the toner is transferred, for example, into the gaps between the paper fibers. Embed or improve contact between fibers and other materials. Next, by applying light, heat generated inside the toner melts the thermoplastic polyamide resin in the toner, making it easier to flow on paper fibers or other materials. Since the time of irradiation with light is on the order of 10-3 seconds, the thermoplastic polyamide resin is solidified before the toner flows to the extent that it disturbs the toner image, and the toner is firmly fixed on the recording material.

In addition, in the case of pressure fixing after light irradiation, the light irradiation melts the thermoplastic boonamide resin in the toner on the recording material, partially preventing the toners from adhering to each other and penetrating into paper fibers. The toner image is allowed to solidify to some extent by cooling, and then pressure is applied to firmly fix the toner image on the recording material.

EXAMPLES Examples of the present invention are shown below, but the present invention is of course not limited to these examples.

Example 1 Polyamide resin having an average molecular weight of 1800 to 2500, a softening point of 105°C, and a phenol terminal group (Emerase 1536 manufactured by Emery Industries Co., Ltd. > 5
0 parts, polyethylene wax 5 parts, carbon black 5 parts
．． 5 parts, and 1.5 parts of metal complex dye were melt-kneaded and crushed.
It was classified to obtain particles with an average particle size of 12.3 μm.

0.7% by weight of hydrophobized colloidal silica was added to the particles and mixed to obtain a toner.

This toner was added in an amount of 3 parts by weight to 100 parts by weight of the carrier and mixed to prepare a developer. Using the obtained developer,
Development and transfer were performed using a copying machine (FX-2830, manufactured by Fuji Xerox), and an unfixed copy image was created on transfer paper (Fuji Pirox I1.1L paper). This unfixed copy image is passed between two metal rolls at 80 K'j/ct.
Immediately after applying pressure A, light from a xenon flash lamp (manufactured by Ushio Electric) was irradiated. The irradiation energy at this time is 1. It was OJ/d. The results are shown in Table 2.

As is clear from Table 2, satisfactory image quality and fixation were obtained in terms of adhesion to fingers, paper staining, image loss, and set-off.

Comparative Example 1 Number average molecular weight, approximately 18,000, glass transition temperature, approximately 6
Styrene/n-butyl methacrylate copolymer 4 at 0°C
0 parts by weight, 2Q parts by weight of a styrene/allyl alcohol copolymer with a number average molecular weight of about 1.000 and a glass transition temperature of about 50°C, and 30 parts by weight of an ethylene/vinyl acetate copolymer with an MI value of about 400 at 190°C. 10 parts by weight of carbon black having a pH of about 3 were melt-kneaded, cooled, pulverized, and further classified to obtain particles with an average particle size of 12.8 μm. A toner was prepared by adding and mixing 0.8% by weight of colloidal silica fine powder to the particles.

The obtained toner was mixed with a carrier in the same formulation as in Example 1, an unfixed copy image was prepared in the same manner as in Example 1, and fixation was carried out under the same conditions.

As shown in Table 2, a sufficient degree of fixation was not obtained.

Table 2 1) Rub the fixed image strongly with your finger and judge the amount of toner adhering to the finger and the degree of contamination by the toner on the paper 2) Bend the part where the toner is fixed and check whether the toner image is missing or not. Judgment 3) Place a piece of paper on top of the fixed image, rub it with a ballpoint pen, etc., and judge how much toner transfers to the paper on top.Example 2: Softening point is about 110°C, melt viscosity at 200°C is 5~5 10 poise polyamide resin (Tomide #394
, manufactured by Fuji Kasei Kogyo Co., Ltd.>40 parts, number average molecule ff18.0
00 polyester resin 60 parts and average particle size 0.1μ
After melt-kneading, 100 parts of triiron tetroxide was pulverized and further classified to obtain particles with an average particle size of 12.6 μm.

To these particles, 0.4% by weight of carphone black having a pH of 3 and an average particle size of 24 mμ and 0.21% of hydrophobically treated colloidal silica were added and mixed to prepare a magnetic toner. Copy machine (Fuji Xerox (...) FX-2830■
) was modified, a -component developing device was installed, and an unfixed image was created using the obtained toner.

Thereafter, in the same manner as in Example 1, 11ON3/crA
When a pressure of 0.8 J/cm was applied and a light irradiation of 0.8 J/cm was further performed, as in Example 1, good image quality and degree of fixation were confirmed.

Example 3 Using the developer obtained in Example 1, an unfixed copy image was collected in the same manner as in Example 1, and then 1.OJ/cm
After the light irradiation, a pressure of 80'j/crit was immediately applied, and as in Example 1, good image quality and fixation were confirmed.

Example 4 Using the developer obtained in Example 2, an unfixed copy image was taken in the same manner as in Example 2, and then 1, OJ/cf.
When a pressure of 110 KI/ctit was applied immediately after irradiation with light of fl, good image quality and degree of fixation were confirmed as in Example 2.

Example 5 Thermoplastic polyamide resin (Persamide 950: manufactured by Henkel Japan Co., Ltd. > 60 parts, polyester 40 parts, triiron tetroxide 1
10 parts were melt-kneaded, pulverized, and roughly classified to obtain particles with an average particle size of 13.0 μι.

1) 0.35% by weight of carbon black with H=3, average particle diameter of 24Tn, and μ was added and mixed to the particles to prepare a magnetic toner. Copy machine (manufactured by Nshi Xerox ■ FX-28
30) was modified, a -component developing device was installed, and an unfixed image was created using this toner.

Thereafter, 90 KFi/cr was applied in the same manner as in Example 1.
After applying pressure i, 1. When light irradiation was performed at OJ/rm, good image quality and degree of fixation were confirmed.

Comparative Example 2 An unfixed copy image was obtained using the magnetic toner obtained in Example 5 in the same manner as in Example 5. 1. Although fixing was carried out only by light irradiation at OJ/cm, a sufficient degree of fixing was not obtained to be satisfactory for actual use.

Effects of the Invention In the present invention, a developer containing a thermoplastic polyamide resin is used, and this is combined with a fixing method that uses both pressure application and light irradiation. The above-mentioned drawbacks of optical fixing methods, pressure fixing methods, solvent fixing methods, etc. are improved. That is, the present invention is excellent in fixing energy efficiency, instant fixing performance, high-speed fixing performance, reliability and safety against environmental changes and repeated use,
The image quality after fixing is also good. In general, it has the advantage that desired fixing strength can be obtained even for magnetic toners for which sufficient fixing strength cannot be obtained by optical fixing alone.

Claims (7)

[Claims] (1) A developed toner image or a transferred toner image formed on a recording material using a developer containing a thermoplastic polyamide resin as a coloring agent and a binder resin component by applying pressure and irradiating light. An image fixing method characterized by fixing. (2) The image fixing method according to claim 1, wherein the developed toner image or the transferred toner image on the recording material is fixed by applying pressure and then irradiating light. (3) Image fixing according to claim 1, characterized in that the developed toner image or the transferred toner image on the recording material is fixed by applying pressure after irradiating with light. Method. (4) 3 on the developed toner image or transferred toner image on the recording material.
The image fixing method according to claim 2 or 3, characterized in that a pressure of 0 to 150 kg/cm^2 is applied. (5) 0 on the developed toner image or transferred toner image on the recording material
．． The image fixing method according to claim 2 or 3, wherein light of 3 to 1.5 J/cm^2 is irradiated. (6) The thermoplastic polyamide resin has a softening point of 40°C or higher2
Claim 1 characterized in that the temperature is 00°C or less
Image fixing method described in section. (7) The image fixing method according to claim 1, wherein the developer contains magnetic fine particles.