JP3584154B2 - Image recording device - Google Patents

Description

註） Ａ：良好 Ｂ：普通 Ｃ：不良
【００３０】
実施例２
図２に示したような、定着前露光に用いる露光光源の周りに感光体ドラムへの遮光と、トナー像への光照射のための集光効果をもつミラー１２を使用した電子写真画像記録装置を用いた以外は、実施例１と同様にして画像の定着及び評価を行った。このように定着前露光光を集光することにより、光照射効率を高めることが可能となった。
【００３１】
実施例１と同様のトナーを用い、同様の条件下で定着プロセスを観察したところ、実施例１に比べて１０℃低い温度、即ち１４０℃の定着温度で良好な定着画像を得ることができた。
このように、定着前露光に用いる光源に、全面発光する光源を使用するときに、転写紙上のトナーに直接照射されない光をトナーに集光することにより、効率良く定着プロセスが行えるものである。
【００３２】
実施例３
図３に示したような、定着前露光に用いる露光光源に有機ＥＬ素子を使用した。ＥＬ素子は可視光領域に発光波長を有し、なかでも、ブルー発光のＥＬ素子が安定して高輝度発光を実現している。このような可視領域短波長から近紫外領域までの、比較的短波長領域に発光波長を有しているＥＬ素子を定着前露光器の光源として用いることによって、本発明におけるトナー中の光分解性樹脂の分解作用を効率良く行うことができる。
このＥＬ素子を組み込んだキヤノン製プリンターＬＢＰ４５０により定着温度を変えて画像出力を行った。定着方式は、サーフ定着と呼ばれる板状の発熱体と紙搬送フイルムで構成された定着方法である。
【００３３】
使用したトナーは実施例１と同様のもので、これを実施例１と同様にＣＬＣ７００用キャリアと混合させて２成分系現像剤として、改造済みのＬＢＰ４５０用２成分系現像装置を用い現像処理を行った。このとき、ＣＬＣ７００の現流現像剤を比較として出力した。
【００３４】
その結果、実施例１と同様にＬＢＰ４５０においても、本例のトナーを用いることにより、従来例のトナーを用いるよりも約３０℃低い定着温度で定着画像を得ることができた。このとき、温度モニターは板状加熱材１４の裏側に取り付けた。
以上のように、有機ＥＬ素子を使用することにより、省スペース及び省消費電力で上記の効果を得ることができ、プリンター等のスペースのない電子写真画像記録装置においても適用可能となる。
【００３５】
【発明の効果】
電子写真プロセスにおいて、現像剤であるトナー粒子に光分解性の樹脂を混合させ、且つ転写プロセス後、定着プロセス前に、転写紙上のトナーに光照射を行うことによって、トナー結着樹脂の分子量の低下を起こし、ガラス転移温度を下げることで低い定着温度で定着プロセスを可能とするとともに、現像、転写及びクリーニングプロセスにおいては高い分子量を維持し、ガラス転移温度を高く維持することにより、フィルミング、ブロッキング及びブレード融着等の弊害なく良好な定着画像が得ることができる。
【図の簡単な説明】
【図１】本発明における画像記録装置の一例を示す概略図。
【図２】本発明における画像記録装置の他の一例を示す概略図。
【図３】本発明における画像記録装置の他の一例を示す概略図。
【図４】従来の画像記録装置の一例を示す概略図。
【図５】実施例１のトナーに定着前露光をしたときの分子量の変化を示す図。
【符号の説明】
１：像担持体
２：一次帯電器
３：現像剤担持体
４：転写帯電器
５：定着器
６：クリーナー
７：像露光器
８：定着前露光器
９：現像器
１０：転写紙
１１：遮光板
１２：反射ミラー
１３：有機ＥＬ素子露光器
１４：板状加熱装置
１５：サーフ定着器[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image recording device such as a copying machine or a printer.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, image recording apparatuses such as copiers and printers that employ an electrophotographic recording method have been widely used. This is done by developing a latent image formed on the photoreceptor drum into a visible image, transferring this visible image (toner image) onto transfer paper using electrostatic force, and then fixing the transferred image by heat. , For recording and forming an image. Further, a double-sided image recording apparatus capable of recording and forming an image on the other side (back side) on which an image is recorded and formed on one side by the same operation as described above, and further includes a yellow, magenta, cyan, black, etc. A color image recording apparatus capable of recording and forming a full-color image by using toner in combination has also been proposed and implemented.
[0003]
FIG. 4 shows a conventional example of an image recording apparatus using the electrophotographic method as described above. In this image recording apparatus, after the toner image formed on the photosensitive drum 1 is transferred to the transfer paper by the transfer device 4, the toner image on the transfer paper is fixed by applying heat and pressure in the fixing device 5. .
[0004]
In order to visualize an electric or magnetic latent image on a photoreceptor, there is an image forming method in which electroconductive or magnetically sensitive fine particles such as toner are attracted to the latent image to form a visible image. A representative example thereof is electrophotography, and many methods are known, for example, as described in US Pat. No. 2,297,691. In this electrophotography, a photoconductive substance is generally used to form an electric latent image on a photoreceptor by various means, and then the latent image is developed using toner to form a toner image. After transferring the toner image to a transfer material such as paper as necessary, a copy is obtained by fixing the toner image to the transfer material using heat, pressure or solvent vapor.
[0005]
In recent years, the above-mentioned technology has come to be used for output means such as a computer and a word processor, that is, a so-called printer, because of its high printing quality and quietness. When used in the above-mentioned environment, not only high printing quality and quietness, but also characteristics such as printing speed, energy consumption, long-term stability of images, environmental stability and running cost are required. It has become.
[0006]
The toner used in the above-described printers and copiers is fine particles composed of a binder resin and a magnetic material as main components, a colorant such as carbon black, a dye and a pigment, and waxes. ３０30 μm. The toner is generally mixed with a coloring agent composed of a dye or pigment or a magnetic material in a thermoplastic resin, melted, uniformly dispersed, and then pulverized and classified to obtain a toner having a desired particle diameter. It is manufactured as.
[0007]
The electrophotographic characteristics required for the toner obtained in this manner include various characteristics such as color developing properties, charging properties, fixing properties, and durability. Among them, low-temperature fixability for fixing at a relatively low temperature during fixing and durability during electrophotographic processes such as development, transfer, and cleaning are generally required to have mutually contradictory characteristics. Overcoming is a major challenge.
Achieving low-temperature fixing not only provides good fixed images, but also has many advantages such as reduced power consumption, reduced warm-up time required to raise the temperature of the fixing unit, and reduced curl of discharged paper. Yes, reducing the load of the fixing process leads to a reduction in manufacturing costs and running costs.
[0008]
[Problems to be solved by the invention]
Generally, in order to solve the problem of low-temperature fixing of toner, it is necessary to lower the fixing temperature of toner. The most effective way to lower the fixing temperature is to lower the glass transition point of the binder resin used for the toner. However, lowering the glass transition point of the toner and lowering the fixing temperature of the toner are characteristics required for other electrophotographic processes, specifically, that the toner does not agglomerate (has excellent blocking resistance), The fact that the toner does not fuse to the surface of the photoreceptor (excellent filming resistance). In the case where a one-component developer is used, the properties such as the fact that the toner does not fuse to the blade are reduced. .
[0009]
As described above, the low-temperature fixability of the toner is improved as the thermal properties such as the glass transition temperature of the binder resin are lowered, in other words, as the molecular weight of the binder resin is lowered, The characteristics are improved as the thermal properties such as the glass transition temperature of the binder resin are increased, in other words, as the molecular weight of the binder resin is increased.
[0010]
In order to achieve both of the above contradictory characteristics, measures have been taken such as using a so-called double peak binder resin containing a high molecular weight component and a low molecular weight component as the binder resin. However, the toner using the double peak binder resin, on the contrary, contains a high molecular weight component that deteriorates low-temperature fixability and a low molecular weight component that deteriorates other characteristics. The effect of improvement is not sufficient, and further improvement of each property is demanded.
[0011]
[Means for Solving the Problems]
The above object is achieved by the present invention described below. That is, the present invention provides a photoconductive image carrier, a charging unit for uniformly charging the image carrier, and an image exposure apparatus for exposing the charged image carrier surface to form an electrostatic latent image. Exposing means, developing means for developing the electrostatic latent image with toner to form a toner image, transfer means for transferring the obtained toner image onto a final support member, and on the obtained final support member An electrophotographic image recording apparatus having a fixing unit for fixing the toner, wherein the binder resin of the toner contains a photodegradable resin, and the binder resin of the toner is provided between the transfer unit and the fixing unit. And a light source for reducing the molecular weight of the binder resin is provided , and the light source is mainly composed of a component from 254 nm or a short wavelength to a near ultraviolet region in a visible region. An image recording device is provided.
[0012]
In the present invention, in the development, transfer and cleaning processes, the molecular weight of the binder resin of the toner is maintained in a high molecular weight state, the thermal characteristics such as the glass transition temperature are increased, and a stable image forming process is realized. . Also, after development and transfer, before the fixing process, lower the molecular weight of the binder resin of the toner, lower the thermal characteristics such as the glass transition temperature, and easily fix the toner on the transfer paper in the low temperature range. It is possible. Specifically, by including a photodegradable polymer in the binder resin of the toner particles, the molecular weight is maintained at a high molecular weight during the development, transfer, and cleaning processes, and after the transfer process, the fixing process is performed. By previously irradiating the toner on the transfer paper with light, the molecular weight of the toner is reduced, and the thermal properties such as the glass transition point are lowered, thereby realizing a toner fixing process at a low temperature. Preferably, the weight average molecular weight of the binder resin of the toner is reduced by 10% or more by light irradiation.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in more detail with reference to preferred embodiments.
FIG. 1 is a schematic diagram illustrating an image recording apparatus according to a preferred embodiment. This apparatus includes a photosensitive drum (image carrier) 1, a charger (charging unit) 2, an image exposing unit (exposure unit) 7, a developing unit (developing unit) 9, and a transfer charger (transfer unit) disposed therearound. Means), a fixing device (fixing means) 5, and a cleaning member 6.
[0014]
As the image carrier 1, a function-separated type having a two-layer structure such as a charge generation layer and a charge transport layer, or a single layer type, with a conductive support base as the lowermost layer, is used. Examples of the charging unit 2 used for the primary charging include a non-contact type using a corona charger, and a contact type using a roller charger. The optical system 7 as an exposure means includes a scanner type using a semiconductor laser, an LED that performs image exposure via a selfoc lens as a light condensing device, an EL element, a plasma light emitting element, and the like. Other optical systems can also be used.
[0015]
In the present invention, the toner used in the development processing has a photodegradable resin.
In the present invention, the photodegradable resin means a resin in which the main chain or the side chain molecular chain of the polymer forming the resin is cut by light irradiation and the molecular weight is reduced. Changes in the skeleton forming such a resin change the mechanical strength and thermal characteristics of the resin. Specifically, when a measurement sample is irradiated with a light amount of 10 mJ / cm ² for 1 second by a low-pressure mercury lamp having an emission wavelength of 254 nm as a main component, a sample whose weight average molecular weight decreases by 10% or more is photolyzed. In the present invention, the conductive resin is defined.
First, as a binder resin as a main component of the toner, for example, polyester, polystyrene, epoxy resin, styrene-alkyl acrylate copolymer, styrene-alkyl methacrylate copolymer, styrene-acrylonitrile copolymer, Examples thereof include a styrene-butadiene copolymer, a styrene-maleic anhydride copolymer, polyethylene, and polypropylene, and these can be used alone or in a mixture.
[0016]
As the colorant for the toner, specifically, in addition to carbon black, an organic colorant, specifically, for example, C.I. I. Direct Red 1, C.I. I. Basic Red 1, C.I. I. Modant Red 30, C.I. I. Direct Blue 1, C.I. I. Direct Blue 2, C.I. I. Acid Blue 15, C.I. I. Basic Blue 3, C.I. I. Basic Blue 5, C.I. I. Modant Blue 7, C.I. I. Direct Green 6, C.I. I. Basic Green 4, C.I. I. Dyes such as Basic Green 6; cadmium yellow, mineral first yellow, navel yellow, naphthol yellow S, Hansa yellow G, permanent yellow NCG, tartrazine lake, molybdenum orange GTR, benzidine orange G, cadmium red 4R, watching red calcium salt, Pigments such as Brilliant Carmine 3B, Fast Violet B, Methyl Violet Lake, Cobalt Blue, Alkaline Blue Lake, Victoria Blue Lake, Quinacridone, Rhodamine Lake, Phthalocyanine Blue, Fast Sky Blue, Pigment Green B, Macalite Green Lake, Final Yellow Green G, etc. And the like.
[0017]
Further, a charge control agent can be added to the toner for the purpose of controlling chargeability. As the charge control agent, any of a positive charge control agent or a negative charge control agent can be used. Specifically, for example, a nigrosine dye, a triphenylmethane dye, a quaternary ammonium salt, an amine or Examples include imine-based compounds, and polymers thereof, metal compounds of salicylic acid or alkyl salicylic acid, metal-containing monoazo dyes, polymers having a carboxylic acid or sulfonic acid functional group, humic acids and salts such as nitrohumin, and the like. .
[0018]
Further, after transferring the toner image on the transfer paper, by performing light irradiation before fixing, the molecular chain of the binder resin of the toner is cut, and a photodegradable resin that reduces the molecular weight of the binder resin includes, for example, , Polymethyl vinyl ketone, polyethyl vinyl ketone, poly-t-butyl vinyl ketone, polyphenyl vinyl ketone, polydivinyl ketone, polymethyl isopropenyl ketone, polyacetoxymethyl vinyl ketone, polychlorovinyl methyl ketone, polychloromethyl vinyl Examples thereof include polyvinyl ketones such as ketones, organic polysilanes such as polyphenylmethylsilane, copolymers of methyl methacrylate and indanone, and polyolefin sulfone resins. Particularly, polyvinyl ketones are preferable. These photodegradable resins may be used alone or in combination of two or more. Further, a copolymer of a monomer for the binder resin of the toner and the monomer for the photodegradable resin, or a photodegradable resin obtained by grafting a fixing resin of the toner may be used. Further, by incorporating a sensitizer having absorption in the visible light region into the binder resin, a more excellent photodecomposition effect can be obtained.
[0019]
The content of the photodegradable resin in the toner is preferably in the range of 10 to 90% by weight based on the total amount of the toner. If the content of the photodegradable resin is less than 10% by weight, the molecular chain of the toner binder resin cannot be sufficiently cut during light irradiation, and the molecular weight of the toner binder resin must be sufficiently reduced. When the content exceeds 90% by weight, the storage stability is lowered, which is not preferable.
[0020]
The developing means is either a two-component developing means using a two-component developer obtained by mixing a toner and a magnetic carrier, or a one-component developing means using a one-component developer using the toner alone. May be.
Specific examples of the carrier powder used when the toner according to the present invention is used as a two-component developer include, for example, ferromagnetic metals such as iron powder, cobalt powder, and nickel powder; ferrite, magnetite, Examples of the compound include an iron such as hematite; and a compound containing an element exhibiting ferromagnetism such as cobalt and nickel. Further, there may be mentioned a magnetic substance-dispersed carrier in which the above-mentioned magnetic substance is dispersed in a binder. In the present invention, when the toner and the carrier particles are mixed and used as a two-component developer, the mixing ratio of the toner and the carrier particles in the developer also depends on the particle size of the carrier particles. , 0.5 to 10% by weight.
[0021]
With the above configuration, light irradiation is performed on the toner image on the transfer paper obtained through the latent image forming, developing, and transferring processes before fixing the toner image. As a light source used at this time, a laser system such as a low-pressure mercury lamp, a high-pressure mercury lamp, a fluorescent lamp, a halogen lamp, an organic EL element, or various semiconductor lasers or various gas lasers can be used. This light irradiation is performed on the toner image on the transfer paper after the toner is transferred and before the toner is fixed. In addition, it is preferable that the light shielding plate 11 is installed on the upstream side in the paper feeding direction of the flash lamp 8 as shown in FIG. 1 so that the photosensitive member serving as the image carrier is not exposed during light irradiation.
[0022]
FIG. 2 shows an example in which, instead of the light-shielding plate 11 in FIG. 1, a mirror 12 having a light-condensing effect for light-shielding on a photoconductor and light irradiation on a toner image is used around a light source used for exposure before fixing. It is. By using the mirror in this manner, the light irradiation efficiency can be increased, and the molecular weight of the binder resin can be reduced more efficiently.
[0023]
FIG. 3 shows an example in which an exposure device composed of an organic EL element is used as a light source used for exposure before fixing. An EL element has an emission wavelength in a visible light region, and has recently been applied to a display or the like. Among them, a blue light emitting EL element stably realizes high luminance light emission. Recently, it has been reported that an emission spectrum in the ultraviolet region can be obtained by using polymethylphenylsilane. As described above, the EL element has an emission wavelength in a relatively short wavelength range from a short wavelength in the visible region to a near ultraviolet region, and it can efficiently contribute to the photodecomposition action of the binder resin of the toner in the present invention. it can.
[0024]
From the viewpoint of the emission wavelength and the size of the light source, by using the EL element as the exposure light source before fixing, it is possible to efficiently perform the photolysis of the binder resin of the toner in a space-saving and power-saving manner. The present invention can be efficiently applied to an electrophotographic image recording apparatus in which space from transfer to fixing is limited.
[0025]
【Example】
Hereinafter, the present invention will be described more specifically with reference to Examples, but the present invention is not limited to these Examples.
Example 1
A low-pressure mercury lamp was installed as a light source 8 of a pre-fixing exposure unit as shown in FIG. 1 in a Canon CLC700 copying machine, and an image was output by changing the fixing temperature using this device. As a developing method, a two-component developing method using a current carrier of CLC700 and a toner having the following composition was used. The fixing method was roller fixing, in which a heating unit of 600 W was included in both the upper roller and the lower roller, and a fixing unit controlled at 180 ° C. was used.
12 parts by weight of polyester resin 2 parts by weight of cyan pigment (CI pigment blue) 4 parts by weight of photodegradable resin (polymethylisopropenyl ketone) 0.7 parts by weight of charge control agent
The fixing property was evaluated when the fixing temperature was set to 180 ° C, 150 ° C, and 120 ° C. In addition, a durability test of 1,000 sheets was performed. The results are shown in Table 1 below. Here, the developer used in the conventional example in Table 1 is a two-component developer using the current toner of CLC700.
[0027]
From Table 1, when the toner according to the present invention is used, a good fixed image can be obtained at the same fixing temperature as the conventional product toner when the pre-fixing exposure is not performed, but by performing the pre-fixing exposure, The molecular weight distribution of the toner resin as measured by gel permeation chromatography was reduced as shown in FIG. 5, and a good output image could be obtained at a fixing temperature of 150 ° C., which is 30 ° C. lower than the conventional example. At this time, the weight average molecular weight calculated in terms of styrene changed from 80,000 to 50,000.
The fixing temperature at this time varies depending on the process speed of the copying machine, the fixing pressure, the nip width between the rollers, and the like. In this embodiment, the fixing temperature could be lowered under the same conditions. This shows that the fixability of the toner was improved.
In the durability test, no adverse effect such as filming or blocking was observed as in the case of the current product.
[0028]
As described above, according to the configuration of the present invention, the toner containing the photodegradable resin is used, and after the transfer process and before the fixing process, light irradiation is performed by the above-described exposure unit, thereby forming the toner particles. Photo-cleavage occurs in the molecular chain of the resin to reduce the molecular weight, and accordingly, the glass transition temperature decreases, and a good fixed image can be obtained by fixing at a lower temperature than the conventional toner.
[0029]
Table 1

Note) A: good B: normal C: bad
Example 2
An electrophotographic image recording apparatus using a mirror 12 having a light-shielding effect on a photosensitive drum and a light-collecting effect for irradiating a toner image with light around an exposure light source used for pre-fixing exposure as shown in FIG. The fixing and evaluation of the image were performed in the same manner as in Example 1 except for using. By condensing the pre-fixing exposure light in this manner, the light irradiation efficiency can be increased.
[0031]
When the fixing process was observed under the same conditions using the same toner as in Example 1, a good fixed image could be obtained at a temperature lower by 10 ° C. than that in Example 1, that is, at a fixing temperature of 140 ° C. .
As described above, when a light source that emits light over the entire surface is used as the light source used for pre-fixing exposure, light that is not directly applied to the toner on the transfer paper is focused on the toner, so that the fixing process can be performed efficiently.
[0032]
Example 3
An organic EL element was used as an exposure light source used for pre-fixing exposure as shown in FIG. The EL element has an emission wavelength in a visible light region, and among them, a blue emission EL element stably realizes high-luminance emission. By using such an EL element having an emission wavelength in a relatively short wavelength region from a short wavelength region in the visible region to a near ultraviolet region as a light source of a pre-fixing exposure device, the photodegradability of the toner in the present invention is improved. The resin can be efficiently decomposed.
An image was output by changing the fixing temperature using a Canon printer LBP450 incorporating the EL element. The fixing method is a fixing method including a plate-like heating element called surf fixing and a paper transport film.
[0033]
The toner used was the same as that in Example 1. This was mixed with the carrier for CLC700 as in Example 1, and used as a two-component developer, using a remodeled LBP450 two-component developing device to perform development processing. went. At this time, the current developer of CLC700 was output for comparison.
[0034]
As a result, a fixed image could be obtained at a fixing temperature of about 30 ° C. lower than that of the conventional toner by using the toner of this example also in the LBP450 as in Example 1. At this time, the temperature monitor was attached to the back side of the plate-shaped heating material 14.
As described above, by using the organic EL element, the above-described effects can be obtained with less space and power consumption, and the present invention can be applied to an electrophotographic image recording apparatus such as a printer which has no space.
[0035]
【The invention's effect】
In the electrophotographic process, by mixing a photodegradable resin with toner particles as a developer, and by performing light irradiation on the toner on the transfer paper after the transfer process and before the fixing process, the molecular weight of the toner binder resin is reduced. By lowering the glass transition temperature, the fixing process can be performed at a low fixing temperature, and in the development, transfer, and cleaning processes, a high molecular weight is maintained, and by maintaining a high glass transition temperature, filming, A good fixed image can be obtained without adverse effects such as blocking and blade fusion.
[Brief explanation of the figure]
FIG. 1 is a schematic diagram illustrating an example of an image recording apparatus according to the present invention.
FIG. 2 is a schematic diagram showing another example of the image recording apparatus according to the present invention.
FIG. 3 is a schematic view showing another example of the image recording apparatus according to the present invention.
FIG. 4 is a schematic diagram showing an example of a conventional image recording apparatus.
FIG. 5 is a diagram illustrating a change in molecular weight when the toner of Example 1 is exposed to light before fixing.
[Explanation of symbols]
1: Image carrier 2: Primary charger 3: Developer carrier 4: Transfer charger 5: Fixer 6: Cleaner 7: Image exposing device 8: Pre-fixing exposing device 9: Developing device 10: Transfer paper 11: Light shielding Plate 12: Reflection mirror 13: Organic EL element exposure unit 14: Plate heating device 15: Surf fixing unit

Claims (7)

A photoconductive image carrier, a charging unit for uniformly charging the image carrier, an exposure unit for imagewise exposing the charged image carrier surface to form an electrostatic latent image, and Developing means for developing the latent image with toner to form a toner image, transfer means for transferring the obtained toner image onto a final support member, and fixing for fixing the toner on the obtained final support member And an electrophotographic image recording apparatus comprising:
The binder resin of the toner contains a photodegradable resin,
Between the transfer means and the fixing means, a light source for photo-decomposing the binder resin of the toner and reducing the molecular weight of the binder resin is provided ,
An image recording apparatus , wherein the light source has a main component of a component from 254 nm or a short wavelength in a visible region to a near ultraviolet region . The light source is a low pressure mercury lamp, high pressure mercury lamp, a fluorescent lamp, a halogen lamp, an organic EL device, an image recording apparatus according to claim 1 which is selected from a semiconductor laser and a gas laser. 3. The image recording apparatus according to claim 1, wherein the toner has a sensitizer having absorption in a visible light region. The image recording apparatus according to any one of claims 1 to 3, the light shielding member is provided between the light source and the image bearing member. Light source, an image recording apparatus according to any one of claims 1 to 4 as a light source to reduce the weight average molecular weight of the binder resin of the toner more than 10%. The photodegradable resin contains at least one resin selected from the group consisting of polyvinyl ketones, organic polysilanes, copolymers of methyl methacrylate and indanone, and polyolefin sulfone resins . Item 2. The image recording device according to item 1 . The image recording apparatus according to claim 1 , wherein the photodegradable resin contains a polyvinyl ketone.

Images