JP4342229B2 - Fixing roller - Google Patents

Description

【００４７】
表１の結果より、参考例１及び比較例１において、ローラの発泡層の厚みが０．５ｍｍ、及び２５ｍｍでは定着性が悪くなることが判る。
実施例２及び比較例２において、ローラの発泡層の厚みが０．５ｍｍでは十分な製品硬度が得られないことが判る。
実施例３及び比較例３において、加硫温度が上昇するにしたがって、製品硬度値が上がることが判る。
参考例１、実施例２乃至４からセル径に関しては、加硫温度２５０℃乃至４００℃の間にセル径が最小となる加硫温度が存在することが判る。
【００４８】
（実施例５及び比較例５）
実施例１のシリコーン組成物の充填剤において、所望の可塑度になるように充填剤量を調整し、加硫温度を２５０℃、外径φ３０ｍｍ、ゴム厚み８ｍｍとしてた以外は実施例１同様にして加圧ローラを製造し、その評価を行った。その結果を表２に示した。
【００４９】
【表２】

【００５０】
実施例５及び比較例５において、可塑度１４０以下、及び４２０以上のシリコーン組成物による加圧ローラによる定着性が悪いことが判る。
【００５１】
（実施例６）及び（比較例６）
加硫温度をＩＲ炉の設定温度を変えて所望の温度とし、外径φ３０ｍｍ、ゴム厚み８ｍｍとしてた以外は実施例１同様にして加圧ローラを製造し、その評価を行った。その結果を表３に示した。
【００５２】
【表３】

【００５３】
実施例６及び比較例６において、加硫温度１５０℃では製品硬度値が小さ過ぎるので、加圧ローラとしての定着性を悪くしている。また、加硫温度４５０℃では製品硬度値が大きくなると共に、その測定に大きなバラツキが見られた。
【００５４】
（実施例７）及び（比較例７）
発泡剤を１,１’−アゾ−ビスイソブチルニトリルとし、その添加量を変化させ、製品硬度を変化させ、製品硬度、平均セル径を調整し、加硫温度を３００℃、外径φ２４ｍｍ、ゴム厚み５ｍｍとした以外は実施例１同様にして加圧ローラを製造し、その評価を行った。その結果を表４に示した。
【００５５】
【表４】

【００５６】
実施例７及び比較例７において、発泡層のセル径が２５０以上の場合は、加圧ローラとしたときに定着性を悪くしている。また、加硫温度、発泡剤の種類にもよるが、この場合の発泡剤の適量は５重量％を超えることはこのましくないことが判る。
【００５７】
（実施例８）及び（比較例８）
加硫温度２５０℃、外径φ３０ｍｍ、ゴム厚み８ｍｍとし、発泡層表面にＰＦＴチューブとした以外は実施例１同様にして加圧ローラを製造し、その評価を行った。その結果を表４に示した。
【００５８】
【表５】

【００５９】
実施例８及び比較例８において、接着剤層の厚みが７μｍでは接着剤不良となり、１２０μｍでは加圧ローラとしての定着性に悪影響を与える。
このようなことから本発明の加圧ローラは、前記構成を満たすことで、定着時における熱容量が少なく熱を伝え易いので温度差による外形変化が少ないため、低温時と高温時において同様の定着性が得られ、同時に高解像度の印字品質を保つことができ、産業上の利用価値が極めて高いローラを提供することができる。
【００６０】
【発明の効果】
以上説明したように本発明に係るロール成型体を用いた定着ローラによれば、未硬化の状態での可塑度（ＪＩＳ Ｋ６２４９可塑度試験法に準拠する。）が１５０乃至４００の範囲にある未加硫のシリコーンゴムを芯金の外表面に押し出して、発泡加硫して該ゴム厚み１乃至２０ｍｍの範囲で形成してなる筒状のロール成型体を具備したローラからなり、該成型体は温度２５０乃至４００℃の範囲で発泡加硫した後のアスカーＣ硬度が５°乃至４０°の範囲にあり、かつ平均セル径が３０乃至２００μｍの範囲にある発泡層を有してなるので、発泡層のアスカーＣ硬度を小さく抑えた成型体を得ることができ、及びそれを用いた低硬度なローラは耐久使用性やグリップ性が十分にあり、微細粒径化したトナーを使用しても定着部での高解像度の確保ができる。
【図面の簡単な説明】
【図１】図１は本実施形態に係る発泡層中に存在するセルの模式断面図である。
【符号の説明】
１ セル径
２ 不定形泡
３ 最大内接真球[0001]
BACKGROUND OF THE INVENTION
  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a roller used in an image forming apparatus such as an electrophotographic copying machine, a laser printer, a facsimile, and an OA device that combines these, and in particular, a developing roller, a charging roller, a toner conveying roller, and a transfer roller. Roll molding that can be used suitably for photoconductor drum cleaner roller, fixing roller, and pressure rollerBodyUsingFixingIt is about Roller.
[0002]
[Prior art]
In general, many image forming apparatuses such as electrophotographic copying machines, laser printers, facsimile machines, and other office automation equipment employ a contact heating type heat roller fixing method with good thermal efficiency and safety and an energy saving type film heating method as fixing means. is doing. A heat roller fixing type heat fixing device is basically composed of a heating roller (fixing roller) as a heating rotator and an elastic pressure roller as a pressure rotator pressed against, and rotates the pair of rollers. Then, a recording material (transfer material sheet, electrostatic recording paper, electrofax paper, printing, etc. as a heated material in which an unfixed image (toner image) is formed and supported on the pressure nip portion (fixing nip portion) of the roller pair Paper, etc.) is introduced and the pressure nip portion is nipped and conveyed to fix the unfixed image as a permanently fixed image on the surface of the recording material by heat from the heating roller and pressure applied at the pressure nip portion. It is something to be made.
[0003]
As the elastic pressure roller used here, a roller in which an elastic layer is formed on a cylindrical or cylindrical core and a fluororesin layer as a toner release layer is formed on the outer peripheral surface thereof is often used. In order to ensure a contact area between the transfer material and the heating member, the processing roller is required to have sufficient elasticity, and the elastic layer is set to be relatively thick. Silicone rubber is often used as the material of the heat insulating layer from the viewpoint of heat resistance. Various film heating type fixing devices have also been proposed (see, for example, Patent Documents 1, 2, 3, and 4). In such an apparatus, a heat-resistant film (fixing film), which is a heating rotator, is brought into close contact with a heating rotator (elastic roller) and conveyed to a heating element, and the heat-resistant fixing film is sandwiched between the heating element and the heating element. A recording material carrying an undetermined fixed image is introduced into a pressure nip formed by a pressure member and conveyed together with a heat resistant film, and heat and pressure applied from a heating body applied via the heat resistant film This is an apparatus for fixing an unfixed image as an image on a recording material by applying pressure at a nip portion.
[0004]
The film heating type heating device can use a linear heating element with a low heat capacity as the heating element, and a thin film with a low heat capacity as the film, thus saving power and shortening the wait time (improving quick start performance). Is possible. In this type of fixing system, a driving roller is provided on the inner peripheral surface of the film for driving the fixing film, and the film is driven while tension is applied. The film is loosely fitted to the film guide and rotated for pressurization. Although a system is known in which the film is driven to rotate with respect to the pressurizing rotator by driving the body, since the number of parts is reduced in recent years, the latter pressurizing rotator driving system is adopted. There are many.
[0005]
Recently, the pressure roller used in the heat fixing device of the electrophotographic image forming apparatus is given low durability of the roller in order to provide durable use and appropriate grip and always have good material transportability. Is needed. The solid type roller has a large heat capacity, so it is difficult to heat it, and the fixing roller takes away the heat applied to the paper, so there is a problem that the fixing property in the low temperature environment or in the initial state immediately after turning on the power deteriorates. At the same time, since the stress due to thermal expansion is large in the solid roller, there is a problem that a change in shape between the low temperature and the high temperature is large, and it is difficult to maintain stable fixability by changing the amount of pressure applied to the fixing roller.
[0006]
When a solid roller is used, an envelope (60 g / m2) having multiple overlaps as a transfer material.²In the following, the pressure may partially concentrate downward. In such a case, a minute bulge occurs in the rotation direction of the roller, and the bulge is fixed to the roller so as not to dissipate the stress applied to the paper. This paper wrinkle is generated in an oblique direction by applying a force in the rotational direction and a force perpendicular to the rotational direction due to the reverse crown shape of the roller.
In addition, since the solid roller generates little pressure divergence, a large reaction occurs in a small area. However, when this solid roller is used as a pressure roller, the reaction occurs on the unevenness formed on the surface, and the transfer material is thin paper. Even when using the above, there is a problem that paper wrinkles are likely to occur if there is a slight overlap of paper.
[0007]
On the other hand, since the foam roller has a small heat capacity and easily transfers heat, the external shape change due to the temperature difference is small. Therefore, similar fixability can be obtained at low temperatures and high temperatures. In addition, the foaming roller uses a porous layer to diverge the pressure over a wide range, so that paper wrinkles are less likely to occur than the solid roller. Therefore, it is necessary to reduce the hardness of the roller. As the elastic pressure roller used here, a silicone rubber elastic layer or a silicone rubber sponge layer is formed on a cylindrical or cylindrical metal core, and directly or on the outer peripheral surface thereof. In many cases, a fluororesin layer is formed as a toner release layer via a toner.
[0008]
A fluororesin layer formed by covering a fluororesin tube or a fluororesin layer formed through a process of applying and firing a fluororesin-based paint has been put to practical use. In order to secure a bonding area between the transfer material and the heating member, the pressure roller is required to have sufficient elasticity, and the elastic layer is set to be relatively thick. In recent years, there is a strong demand for high speed in the heat roller fixing device or the fixing film driving type heat fixing device as well as the pressure roller driving type heat fixing device. Has been. In order to save power, the number of heat fixing devices that do not perform standby temperature control by increasing the heating efficiency is increasing. In order to satisfy the above requirements in such an apparatus, it is necessary to use a fixing roller and a pressure roller having a relatively low pressure and a small diameter, and when the recording material conveyance speed of the image forming apparatus is high, In order to supply a sufficient amount of heat to the recording material, it is necessary to increase the pressure nip width between the fixing roller or the fixing film and the pressure roller at a low pressure. For this reason, the pressure hardness of the pressure roller is reduced. Attempts have been made to develop pressure rollers.
[0009]
For example, for the purpose of providing a low-density fixing pressure roller, a fixing pressure roller has been proposed in which a hollow hole continuous in the length direction is provided in a silicone rubber layer formed of liquid silicone ( For example, see Patent Document 5). Moreover, when it has a fluororesin surface layer on a silicone rubber layer, it has also proposed that the surface hardness measured with an Asker C-type hardness meter (1 kgf) is 60 degrees or less.
Further, the elastic layer of the pressure roller is formed by a sponge layer having a hardness of 35 to 50 ° (Asker C) formed of porous silicone rubber and a PFA tube coated on the sponge layer, and the roller hardness is 45 to 60 ° ( There has been proposed a pressure roller with good fixability that prevents the occurrence of paper wrinkles set to Asker C) (see, for example, Patent Document 6).
Furthermore, it has been proposed that the average cell diameter of the foam layer is 150 to 300 μm and the Asker C hardness is in the range of 20 to 60 ° (see, for example, Patent Documents 7 and 8).
[0010]
[Patent Document 1]
JP-A-63-313182.
[Patent Document 2]
Japanese Patent Laid-Open No. 2-157878.
[Patent Document 3]
JP-A-4-44075.
[Patent Document 4]
JP-A-4-204980.
[Patent Document 5]
JP-A-7-271233.
[Patent Document 6]
JP-A-5-107972.
[Patent Document 7]
JP-A-11-167246.
[Patent Document 8]
Japanese Patent Application Laid-Open No. 11-167301.
[0011]
[Problems to be solved by the invention]
However, although certain appropriate values such as the average cell diameter and Asker hardness of the foam layer are known, it is necessary to improve and secure the resolution at the fixing unit in response to the demand for higher print quality and higher resolution. In the recent situation, it is not possible to respond sufficiently and there is room for improvement. Also, with conventional rollers, if the heat treatment of silicone rubber is insufficient or the relationship with the thickness of the foam layer is not clear, durable use and grip properties are not sufficient, and toner with a fine particle size is used. However, there may be a case where high resolution cannot be ensured in the fixing unit, and printing unevenness may occur. In other words, with the recent progress in reducing the particle size of toner, it is effective to reduce the average cell diameter on the surface of the foam roller in order to maintain high-resolution and high-quality printing without uneven printing. As it turns out, it has also proved difficult to ensure low hardness at the same time.
[0012]
  Therefore, the subject of this invention is the above-mentioned, The roll molded object which suppressed the Asker C hardness of the foaming layer smallForIt has sufficient durability and grip, and has low hardness that can ensure high resolution at the fixing part even when using toner with a fine particle size.FixingTo provide a roller.
[0013]
[Means for Solving the Problems]
  As a result of intensive studies to achieve the above-mentioned problems, the present inventor has appropriately selected the amount of foaming agent, and the uncured silicone rubber has a plasticity (test value based on JIS K6249) in the range of 150 to 400 Select vulcanization temperature 25The roll molded body of silicone rubber vulcanized at 0 to 400 ° C. has a fine and uniform sponge cell, the Asker C hardness is kept small, and the roll molded body has a thickness of 1 to 20 mm. As a result, the present inventors have found that when used as a low-hardness roller in a fixing portion, the gripping property and durability usability are excellent, and that the image forming apparatus contributes sufficiently to ensure high resolution.
  That is, the roll molded body according to the present invention and a roller using the roll molded body have the following configurations or means, and solve the above-described problems.
[0014]
  The fixing roll according to the present invention extrudes unvulcanized silicone rubber having an uncured plasticity (based on JIS K6249 plasticity test method) in the range of 150 to 400 onto the outer surface of the cored bar. And a roller provided with a cylindrical roll molded body formed by foaming and vulcanizing and having a rubber thickness of 1 to 20 mm.5An Asker C hardness after foaming vulcanization in the range of 0 to 400 ° C. is in the range of 5 ° to 40 ° and the foamed layer has an average cell diameter in the range of 30 to 200 μm. To do.
[0015]
The roll molding according to the present invention is an organic foaming agent such as azobisisobutyronitrile (AIBN), azocarbonamide (ADCA), dinitrosopentamethylenetetramine (DPT), or the like, as a foaming agent in the foam vulcanization. Can be suitably used. Further, when the uniformity of the cell diameter is particularly required, it is desirable to use dimethyl-1,1'-azobis (1-cyclohexanecarboxylate) as the foaming agent.
[0016]
The roll molded body according to the present invention may be characterized in that a fluororesin is coated on the outer periphery of the foam layer, and in particular, an adhesive layer is provided between the foam layer and the fluororesin, The thickness of the adhesive layer is desirably in the range of 10 to 100 μm.
For example, when a roll molded body is used as a roller of a fixing device, it is desirable to provide a release layer for the developer on the outer peripheral surface of the molded body, and such a release layer is coated with a fluororesin. Is desirable. When providing such a fluororesin, it is provided through an adhesive layer or the like. When the thickness of the adhesive layer is in the range of 10 to 100 μm, it sufficiently contributes to the adhesion between them, and the smoothness can be sufficiently maintained even when pressure is applied to the fluororesin surface.
[0017]
The roll molded body according to the present invention may be characterized in that at least one of the foamed layer and the fluororesin has conductivity.
If such conductivity of the roll molded body is imparted, the roll molded body can be used for a semiconductive roller other than the fixing roller. The electroconductivity can be imparted by adding carbon black, a fine powder of metal, metal oxide, etc., a conductive polymer material, etc., which are known per se, to each layer.
[0018]
The roll molded body according to the present invention may be characterized in that a heat transfer layer is provided on the outer periphery of the foam layer, and the heat conductivity of the heat transfer layer is 1 W / k · m or more.
When such a heat transfer layer is formed, it is preferable to use it for a fixing roller or the like because the wait time of the fixing device is shortened. The heat transfer layer may be coated with a heat conductive material or may be coated with a heat conductive film.
[0019]
The low-hardness roller according to the present invention is obtained by providing the roll molded body on the outer peripheral surface of the core metal described above.
The low-hardness roller may be a developing roller, a charging roller, a toner conveying roller, a transfer roller, a photosensitive drum cleaner roller, a fixing roller, or a fixing roller of an image forming apparatus such as an electrophotographic copying machine, a laser printer, a facsimile machine, and an OA device. It can be suitably used as a pressure roller.
In particular, it is desirable to use as a nip roller of a fixing roller.
[0020]
The low-hardness roller according to the present invention preliminarily forms the roll molded body by applying an adhesive primer to the outer peripheral surface of the core metal in advance, and extruding the uncured silicone rubber to the outer peripheral surface of the core metal. The roll molded body is bonded to the outer peripheral surface of the core metal while being vulcanized and foamed.
Therefore, as described above, the roll molded body can be provided directly or indirectly on the outer peripheral surface of the core metal. As a preferable low-hardness roller, the roll molded body is directly molded on the core metal surface, It is desirable to use an adhesion primer or the like in advance.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of a roll molded body and a roller using the roll molded body according to the present invention will be described in detail. In addition, the roll molded object which concerns on this invention, and the roller using the same are not restricted to the following embodiment.
FIG. 1 is a schematic cross-sectional view of a cell bubble according to this embodiment.
[0022]
The roll molded body according to the present invention is obtained by foaming and vulcanizing a silicone rubber having an uncured plasticity (based on JIS K6249 plasticity test method) in the range of 150 to 400. It consists of a cylindrical molded body formed in a range of 20 mm.
[0023]
The silicone rubber is not particularly limited as long as it has the unvulcanized plasticity, but vinyl group-containing dimethyl silicone raw rubber, vinyl group-containing phenyl silicone raw rubber, vinyl group-containing fluorosilicone raw rubber, etc. or modified products thereof. It is preferable to use a material to which a reinforcing silica filler such as fumed silica or precipitated silica is added as required.
The plasticity of the unvulcanized silicone rubber is in the range of 150 to 400. In particular, the range is preferably 250 to 400. When the plasticity is less than 150, it is difficult to obtain a foamed layer having fine cells having a cell diameter of 200 μm or less. When the plasticity exceeds 400, it is difficult to obtain a low hardness foam layer of 40 ° or less with an Asker C-type hardness meter.
[0024]
The vulcanizing agent is an organohydropolyene polysiloxane having two or more hydrogen atoms bonded to silicon atoms in one molecule.
Moreover, if a peroxide is used in combination as a vulcanization auxiliary, it is effective for improving the characteristics. Examples of the peroxide include benzoyl peroxide, bis-2,4-dichlorobenzoyl peroxide, dicumyl peroxide, di-t-butyl peroxide, 2,5-dimethyl-2,5-bis (t-butyl peroxide). -Oxy) hexane etc. are illustrated.
In order to adjust the heat resistance improver and hardness, non-reinforcing silica may be added.
[0025]
Moreover, when providing electroconductivity to a roll molding, a electroconductivity imparting agent can be added. Examples of the conductivity imparting agent include conductive carbon black, metal powders such as nickel, aluminum and copper, metal oxides such as zinc oxide and tin oxide, or core materials such as barium sulfate, titanium oxide and potassium titanate, and tin oxide. Examples thereof include a conductivity-imparting agent or a conductive polymer agent.
[0026]
As a foaming agent for foaming and vulcanizing the silicone rubber, an organic azo foaming agent such as azobisisobutyronitrile (AIBN), azocarbonamide (ADCA), dinitrosopentamethylenetetramine (DPT) is used. preferable. In particular, dimethyl-1,1'-azo-bis (1-cyclohexanecarboxylate) is preferably used when the cell diameter uniformity is particularly required.
The content of the foaming agent varies depending on the type of the foaming agent, but is usually in the range of 0.1 to 10% by weight, particularly 0.5 to 10% by weight, based on the silicone rubber before vulcanization. This is because if the amount is less than 0.1% by weight, foaming does not occur sufficiently, while if the amount exceeds 10% by weight, the foamed elastic body cannot be maintained and mechanical strength is lowered.
When dimethyl-1,1'-azo-bis (1-cyclohexanecarboxylate) is used as a foaming agent, it is preferably 0.5 to 5% by weight.
[0027]
A reaction inhibitor can be added to the silicone rubber. As the reaction inhibitor, methyl vinylcyclotetrasiloxane, acetylene alcohols, siloxane-modified acetylene alcohol, hydroperoxide, or the like can be used.
Further, a curing accelerator for addition reaction can be added to the silicone rubber. Examples of the curing accelerator for addition reaction include platinum compound catalysts. Examples of the platinum catalyst include chloroplatinic acid, alcohol-modified chloroplatinic acid, platinum supported on a solid catalyst such as platinum black, alumina, silica or carbon, platinum and olefin, ethylene, alcohol or vinylsiloxane. A complex or each complex of chloroplatinic acid and an olefin, ethylene, alcohol, or vinyl siloxane can be used.
[0028]
The roll molded body after vulcanization has a foamed layer having an average cell diameter in the range of 30 to 200 μm. In particular, the average cell diameter is preferably in the range of 30 to 150 μm. Moreover, it is preferable that the foamed layer having such cells forms the entire molded body, particularly at least the surface layer of the roll molded body.
As shown in FIG. 1, the cell diameter 1 in the foam layer is an inscribed circle diameter in the largest inscribed true sphere 3 in the irregular foam (cell) 2, and is almost equal to the diameter of the longest foam 2. It is an approximation. When the average cell diameter of such a foamed layer is less than 30, the air layer in the roll is small and the thermostatic property of the roll is inferior. When the average cell diameter exceeds 200 μm, the foamed layer does not constitute a fine cell, so that the intended effects of the present invention such as durability and grip properties cannot be sufficiently obtained.
[0029]
  The roll molded body according to the present invention has a temperature250It is foamed and vulcanized in the range of 400 to 400 ° C. The vulcanization temperature is25When the temperature is lower than 0 ° C. or higher than 400 ° C., the cell balance is lost and a foam layer having low hardness and fine cells is not obtained.
  The roll molded body according to the present invention has an Asker C hardness of 5 ° to 40 °, particularly preferably in the range of 10 ° to 40 °. When the hardness is lower than 5 °, the strength of the foamed layer is insufficient, and when the pressure is applied, cell destruction is likely to occur. If the hardness exceeds 40 °, the desired low hardness cannot be imparted to the roller.
[0030]
The roll molded body according to the present invention is preferably formed so that the thickness of the foamed layer of the silicone rubber is in the range of 1 to 20 mm, particularly in the range of 5 to 15 mm.
When the thickness of the foamed layer of the silicone rubber is less than 1 mm, sufficient elastic deformation cannot be obtained, and when it is used for a roller, a low hardness cannot be obtained. On the other hand, when it exceeds 20 mm, it is difficult to realize a fine cell.
[0031]
The roll molded body according to the present invention may be characterized in that the outer periphery of the foam layer is coated with a fluororesin.
Examples of the fluororesin to be coated include fluorinated ethylene-propylene copolymer (FEP), fluorinated ethylene-perfluoroalkyl vinyl ether copolymer (PFA), and polytetrafluoroethylene (PTFE). Fluorinated ethylene-perfluoroalkyl vinyl ether copolymer (PFA) can be preferably used. In particular, it is preferable to coat a PFA or PTFE tube. The thickness of the tube to be coated is preferably in the range of 10 to 60 μm. If the thickness is less than 10 μm, the processing is difficult, and if it is more than 60 μm, the foamed layer does not sufficiently work due to the hardness of the tube itself.
[0032]
Such a fluororesin can be added with a conductivity-imparting agent as described above, and the resistivity of the fluororesin is 10 by such a conductivity-imparting agent.¹³A conductive material having a conductivity of Ω · cm or less can be used.
[0033]
In the roll molded body according to the present invention, an adhesive layer is desirably provided between the foam layer and the fluororesin, and the thickness of the adhesive layer is desirably in the range of 10 to 100 μm. Adhesives such as addition reaction type silicone RTV are suitable. Adhesive strength cannot be obtained when the thickness of the adhesive layer is less than 10 μm, and when the thickness exceeds 100 μm, the surface of the fluororesin is smooth. May be lost.
[0034]
In the roll molded body according to the present invention, it is desirable that a heat transfer layer is provided on the outer periphery of the foam layer, and the heat conductivity of the heat transfer layer is 1 W / k · m or more.
When the roll molded body is used for a fixing roller or the like, it is desirable to provide such a heat transfer layer on the surface of the foam layer in order to save power and shorten the wait time (improve quick start properties). If the thermal conductivity of the heat transfer layer is less than 1 W / k · m, the effect of shortening the wait time cannot be obtained sufficiently.
In order to form such a heat transfer layer, a heat conductive material may be applied or a heat conductive film may be coated. As long as it has high thermal conductivity, the thermal conductive material or film may be a single substance or a mixed substance.
For example, a metal powder or a metal oxide powder having a high thermal conductivity can be added to and mixed with a liquid heat-resistant organic insulating substance to obtain a heat conductive material. In this case, the thermal conductivity and the heat capacity can be appropriately adjusted depending on the amount of the metal powder or the metal oxide powder having a high thermal conductivity. Moreover, you may coat | cover high heat conductive metals, such as copper and aluminum.
[0035]
Various known materials can be used as the heat-resistant organic insulating material. For example, a metal powder or a metal oxide powder having a high thermal conductivity is appropriately mixed in a liquid polyamide resin. Any metal can be used as the metal powder, such as zinc, aluminum, iron, copper, silver, lead, platinum, and molybdenum. Furthermore, high-purity aluminum oxide (Al₂O_Three) Powder can also be used.
[0036]
The low-hardness roller according to the present invention comprises the roll molded body provided on the outer peripheral surface of the cored bar.
The core metal does not need to be a metal, and is not particularly limited, but is usually made of iron, aluminum, SUS, brass, or the like. Moreover, you may shape | mold with the conductive resin which mix | blended carbon black or a metal powder etc. as a electroconductivity imparting agent in a thermoplastic resin, a thermosetting resin, etc. Such a mandrel may be heated, bias voltage applied, or the like if necessary for the purpose of use of the roller, but it is not particularly necessary for a pressure roller with a simple function.
[0037]
  The low hardness roller according to the present invention directly forms a roll molding on the core metal..
  As a low-hardness roller, an adhesive primer is applied in advance to the outer peripheral surface of the core metal, the uncured silicone rubber is extruded onto the outer peripheral surface of the core metal, the roll molded body is preformed, heated and heated. It is desirable to bond the roll molded body to the outer peripheral surface of the core metal while performing sulfur foaming.
[0038]
Next, a roll molded body according to the present invention and a method for producing a roller using the roll molded body will be briefly described.
First, an adhesion primer treatment is applied to the core metal in advance. A core metal and a composition in which each component is blended with the silicone rubber are integrally extruded using a crosshead with an extruder, and then heated in a HAV furnace, gear oven, or IR (infrared) furnace to be vulcanized and foamed. . As described above, a roller having excellent adhesiveness can be obtained by simultaneously performing the bonding process between the core metal and the silicone rubber and the vulcanization foaming process of the silicone rubber.
The vulcanization temperature at this time is set in the range of 200 ° C. to 400 ° C., particularly in the range of 250 ° C. to 400 ° C. As described above, when an organic foaming agent is added to silicone rubber to form a foam, in order to obtain a foamed layer having a uniform cell diameter, the curing rate of silicone rubber and the decomposition rate of organic foaming agent are increased. adjust. If the vulcanization temperature is within the above range, a foamed layer having a fine cell with a low cell-balanced hardness can be obtained.
[0039]
The roll molded body and roller thus obtained may be subjected to secondary vulcanization using a gear oven or the like to stabilize physical properties. The secondary vulcanization temperature in this case is preferably in the range of 100 to 225 ° C. Further, the outer peripheral surface of the roller can be polished by a cylindrical grinder to obtain an arbitrary product outer diameter value. At this time, the thickness of the foamed layer of silicone rubber is formed in the range of 1 to 20 mm.
As a method for coating the roll molded body with a fluororesin, a method of coating a fluororesin tube or a method of heating and firing after coating a fluororesin powder and a fluororesin dispersion is known. Among these, the method of heating and baking the fluororesin is performed by heating to a melting point of the fluororesin or higher.
[0040]
In the roll molded body configured as described above, a sufficiently low hardness can be maintained and a foamed layer having fine and uniform cells can be obtained. In the low hardness roller using such a roll molded body, the developing roller, the charging roller, the toner conveying roller, the transfer roller of the image forming apparatus such as an electrophotographic copying machine, a laser printer, a facsimile machine, and an OA machine It can be suitably used as a photosensitive drum cleaner roller, a fixing roller, or a pressure roller thereof, and particularly preferably used as a pressure roller or a nip roller of a fixing roller. When used as a roller of such a fixing device, sufficient durability and gripping properties are sufficiently obtained, and high resolution can be secured at the fixing portion even when toner having a fine particle size is used.
[0041]
【Example】
  Hereinafter, examples of the roll molded body according to the present invention and a roller using the roll molded body and comparative examples will be sequentially described in detail.
(Reference Example 1 and Example 2To 4 and Comparative Examples 1 to 4)
  Silicone rubber compound “KE571U” (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.) 100 parts by weight, organohydrodiene polysiloxane 2 parts by weight, blowing agent dimethyl-1,1′-azo-bis (1-cyclohexanecarboxy) Rate) 5 parts by weight, and chloroplatinic acid as a catalyst was added to prepare a silicone rubber composition.
  Further, a metal shaft body (φ14 × 350 mm, SUM22 electroless nickel plated) is washed with toluene, and “Primer No 101A / B” (Shin-Etsu Chemical Co., Ltd.) is applied as a primer.
[0042]
  The primer-treated metal shaft is baked in a gear oven at a temperature of 180 ° C. for 30 minutes and cooled at room temperature for 30 minutes or more. The primer-treated metal shaft and the silicone rubber composition are integrally put out by an extruder, and the vulcanization temperature condition is changed to 200 ° C. by changing the furnace temperature setting in an IR furnace.Reference example1 and Comparative Example 1), 250 ° C. (Example 2 and Comparative Example 2), 300 ° C. (Example 3 and Comparative Example 3), and 400 ° C. (Example 4 and Comparative Example 4). Thus, a sponge roller having a desired average cell diameter is formed.
  The unvulcanized silicone rubber was measured for plasticity according to the JIS K6249 plasticity test method.
[0043]
The obtained sponge roller was further baked in a gear oven at a temperature of 200 ° C. for 7 hours and left at room temperature for 1 hour. Thereafter, external grinding was performed with a cylindrical grinder to obtain a foam layer having a predetermined thickness, and the product hardness was examined. The surface of the foamed layer thus obtained was photographed with an electron micrograph and 1 cm²The average particle size of the cells inside was measured. The definition of the cell diameter is as described above as shown in FIG.
[0044]
Use a Asker C hardness tester (manufactured by Kobunshi Keiki Co., Ltd.) and a constant pressure loader CL-150 for rubber hardness tester (manufactured by Kobunshi Keiki Co., Ltd.) as the product hardness, and load 1 kgf perpendicular to the roller surface. And measured according to SRIS 0101.
An adhesive is applied to the surface of the foam layer, and a PFA tube having a thickness of 50 μm is pressed into the surface, and a baking treatment is performed at a temperature of 120 ° C. for 1 hour.
[0045]
Each of the obtained pressure rollers was incorporated into a heat fixing device, and a printing paper passing test was actually performed in order to examine whether or not fixing failure occurred.
The determination results of each pressure roller obtained from the paper passing test are shown in Table 1 below. The fixing property is a level of printing unevenness after fixing with an actual machine, where ◎ indicates no problem, × occurrence of a serious problem, and ○ indicates a problem level depending on use conditions.
[0046]
[Table 1]

[0047]
  From the results in Table 1,referenceIn Example 1 and Comparative Example 1, it can be seen that the fixing property is deteriorated when the thickness of the foamed layer of the roller is 0.5 mm and 25 mm.
  In Example 2 and Comparative Example 2, it can be seen that sufficient product hardness cannot be obtained when the thickness of the foamed layer of the roller is 0.5 mm.
  In Example 3 and Comparative Example 3, it can be seen that the product hardness value increases as the vulcanization temperature increases.
  Reference Example 1,Example2From 4 to 4, regarding the cell diameter, it can be seen that there is a vulcanization temperature at which the cell diameter is minimum between 250 ° C. and 400 ° C.
[0048]
(Example 5 and Comparative Example 5)
In the filler of the silicone composition of Example 1, the amount of the filler was adjusted so as to obtain a desired plasticity, and the same as Example 1 except that the vulcanization temperature was 250 ° C., the outer diameter was 30 mm, and the rubber thickness was 8 mm. A pressure roller was manufactured and evaluated. The results are shown in Table 2.
[0049]
[Table 2]

[0050]
In Example 5 and Comparative Example 5, it can be seen that the fixability of the pressure roller using a silicone composition having a plasticity of 140 or less and 420 or more is poor.
[0051]
(Example 6) and (Comparative Example 6)
A pressure roller was manufactured and evaluated in the same manner as in Example 1 except that the vulcanization temperature was changed to the desired temperature by changing the set temperature of the IR furnace, the outer diameter was 30 mm, and the rubber thickness was 8 mm. The results are shown in Table 3.
[0052]
[Table 3]

[0053]
In Example 6 and Comparative Example 6, since the product hardness value is too small at a vulcanization temperature of 150 ° C., the fixability as a pressure roller is deteriorated. Further, at the vulcanization temperature of 450 ° C., the product hardness value was increased and the measurement showed great variation.
[0054]
(Example 7) and (Comparative Example 7)
The foaming agent is 1,1′-azo-bisisobutylnitrile, the amount added is changed, the product hardness is changed, the product hardness and the average cell diameter are adjusted, the vulcanization temperature is 300 ° C., the outer diameter is φ24 mm, rubber A pressure roller was produced and evaluated in the same manner as in Example 1 except that the thickness was 5 mm. The results are shown in Table 4.
[0055]
[Table 4]

[0056]
In Example 7 and Comparative Example 7, when the cell diameter of the foam layer is 250 or more, the fixability is deteriorated when the pressure roller is used. Although depending on the vulcanization temperature and the type of foaming agent, it can be seen that the appropriate amount of foaming agent in this case does not exceed 5% by weight.
[0057]
(Example 8) and (Comparative Example 8)
A pressure roller was manufactured and evaluated in the same manner as in Example 1 except that the vulcanization temperature was 250 ° C., the outer diameter was 30 mm, the rubber thickness was 8 mm, and the surface of the foam layer was a PFT tube. The results are shown in Table 4.
[0058]
[Table 5]

[0059]
In Example 8 and Comparative Example 8, when the thickness of the adhesive layer is 7 μm, the adhesive is defective, and when it is 120 μm, the fixing property as a pressure roller is adversely affected.
For this reason, the pressure roller according to the present invention satisfies the above-described configuration and has a small heat capacity at the time of fixing and easily transfers heat. At the same time, high-resolution print quality can be maintained, and a roller with extremely high industrial utility value can be provided.
[0060]
【The invention's effect】
  As described above, according to the fixing roller using the roll molded body according to the present invention, the uncured plasticity (conforming to JIS K6249 plasticity test method) is in the range of 150 to 400. A vulcanized silicone rubber is extruded on the outer surface of the core metal, and is formed of a roller having a cylindrical roll molded body formed by foaming and vulcanizing the rubber in a range of 1 to 20 mm. temperature250It has a foam layer in which the Asker C hardness after foam vulcanization in the range of to 400 ° C. is in the range of 5 ° to 40 ° and the average cell diameter is in the range of 30 to 200 μm. A molded product with a reduced Asker C hardness can be obtained, and a low-hardness roller using the same has sufficient durability and gripping properties. High resolution can be secured.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view of a cell present in a foam layer according to the present embodiment.
[Explanation of symbols]
1 Cell diameter
2 Amorphous foam
3 largest inscribed true sphere

Claims (7)

An unvulcanized silicone rubber having an uncured plasticity (according to JIS K6249 plasticity test method) in the range of 150 to 400 is extruded onto the outer surface of the cored bar, foam vulcanized, and consists roller provided with the cylindrical roll molded body formed by forming a range of rubber thickness 1 to 20 mm, molded type body has an Asker C hardness after foaming vulcanized at a temperature ranging 2 5 0 to 400 ° C. 5 A fixing roller having a foamed layer in a range of 0 to 40 ° and an average cell diameter in a range of 30 to 200 μm.   The fixing roller according to claim 1, wherein the foaming agent in the foam vulcanization is an organic azo compound dimethyl-1,1′-azobis (1-cyclohexanecarboxylate).   The fixing roller according to claim 1, wherein a fluororesin is coated on an outer periphery of the foam layer.   4. The fixing roller according to claim 3, wherein an adhesive layer is provided between the foam layer and the fluororesin, and the thickness of the adhesive layer is in the range of 10 to 100 [mu] m.   The fixing roller according to claim 3, wherein at least one of the foam layer and the fluororesin has conductivity.   The fixing roller according to claim 1, wherein a heat transfer layer is provided on an outer periphery of the foam layer, and the heat conductivity of the heat transfer layer is 1 W / k · m or more.   An adhesive primer is applied in advance to the outer peripheral surface of the core metal, the uncured silicone rubber is extruded onto the outer peripheral surface of the core metal, the roll molded body is preformed, heated, vulcanized and foamed while being vulcanized and foamed. The fixing roller according to claim 6, wherein the roll molding is bonded to an outer peripheral surface.

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