JP2006010832A - Toner-fixing member and toner fixing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixed image of higher image quality, specially, attaining higher uniformity in images, and also of high performance, with separation property of the recording material from a toner-fixing member improved, in the fixed image obtained by this toner-fixing member incorporated into a toner fixing device for an electrophotographic apparatus, as compared with a fixed image obtained by the conventional toner-fixing member manufactured, while controlling the surface shape in the conventional manner, and also, to provide the toner-fixing apparatus for the electrophogoraphic apparatus attaining high function. <P>SOLUTION: The electrophotographic fixing member comprises at least an elastic layer and an outermost layer whose thickness is 10 to 50μm, the problem is solved by the toner fixing member whose arithmetic average roughness of < 50μm wavelength (Ra(<50μm)) is equal to or smaller than 0.05μm, and also, whose arithmetic average roughness of 50 to 500μm wavelength (Ra(50≤)) is 0.1 to 0.4μm, regarding the surface shape of the outermost layer. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a roller or belt-shaped toner fixing member used for toner fixing of an electrophotographic copying machine or printer.

  The electrophotographic toner fixing member is one of the members that determine whether the toner image is good or bad, that is, the image quality, and various improvements and improvements have been made in view of the surface shape.

  In general, the outermost layer of the toner fixing member is formed of a heat resistant material such as a fluororesin or a silicone rubber and hardly adheres to the toner. Regarding the fluororesin, there are known a method of forming a film by melting and solidifying a fluororesin powder, a method of forming a tube of a predetermined size by an extrusion method and the like, and a method of forming as an outermost layer by covering a member. .

  In any case, when the surface is taken as a microscopic shape, that is, as surface roughness, the toner image is fixed when the toner image surface and the fixing member surface are separated after being heated and pressurized by the fixing member. Since the surface shape of the member affects the surface of the toner image and affects the image quality, smoothness is required.

  A parameter generally known as the surface roughness of the toner fixing member is calculated as a standard value determined by JIS from a cross-sectional profile of the surface shape such as the maximum height (Rz) and the ten-point average roughness (Rzjis). Is. By managing the surface shape based on these surface roughness values, it is possible to provide a fixing member capable of obtaining a higher quality toner image.

  However, on the other hand, with the pursuit of higher image quality, it is necessary to control the surface shape at a level that cannot be managed by Rz or Rzjis.

As a special method for evaluating the surface roughness, there is a method in which the profile of the surface shape is considered as a composite wave composed of waves of a plurality of periods, and is evaluated as a characteristic value of amplitude for each frequency band of the wave. More specifically, it is a method of decomposing and analyzing the synthesized wave by Fourier transform. The concept of capturing the surface shape by frequency-resolving in this way is not particularly common in the technical field of electrophotography, as described for the surface roughness of the toner image itself after fixing, but is specifically used. (For example, refer to Patent Document 1). There is also an example in which the concept is applied to a pressure roller of a fixing device (see, for example, Patent Document 2).
Japanese Examined Patent Publication No. 6-95232 JP-A-4-125675

  When the toner fixing member is incorporated in a toner fixing device of an electrophotographic apparatus and used as a toner fixing member, the fixing image obtained by the conventional toner fixing member produced by the control of the surface shape has high image quality, particularly the image tail. To provide a high-performance one that achieves increased uniformity and improved separation of the recording material from the toner fixing member, and also provides a toner fixing device of an electrophotographic apparatus in which the high function is achieved. With the goal.

That is, the present invention provides an electrophotographic toner fixing member having at least an elastic layer and having an outermost layer having a thickness of 10 to 50 μm.
Regarding the surface shape of the outermost layer, the arithmetic average roughness (Ra (<50)) of a wavelength of less than 50 μm is set to 0.05 μm or less, and the arithmetic average roughness (Ra (50 ≦)) of a wavelength of 50 to 500 μm is set. A toner fixing member having a thickness of 0.1 to 0.4 μm.

  In the toner fixing member, it is preferable that the elastic layer is made of silicone rubber and the outermost layer is made of a fluororesin.

  According to another aspect of the present invention, there is provided a toner fixing device including at least one toner fixing member as a fixing member on a heating side.

  The toner residence time in the toner fixing nip formed by the toner fixing member is preferably 50 to 500 msec.

  According to the present invention, the surface shape of the toner fixing member is specifically defined by the surface shape of the portion that cannot be managed by the conventional surface roughness, thereby achieving high image quality of the fixed image, and the toner fixing member and the toner. A more sophisticated fixing device can be provided. In particular, high image quality and high functionality are satisfied in image uniformity focusing on gloss and paper separation from the toner fixing member.

  By controlling the surface shape as described above, high image quality of the fixed image is achieved, and the toner fixing member has a higher function. In particular, image uniformity focusing on gloss and the toner fixing member Satisfies high image quality and high functionality in terms of paper separation.

  Furthermore, an effect is exhibited more by comprising an elastic layer and an outermost layer with the said material.

  The toner fixing member of the present invention will be described below.

  FIG. 1 is a cross-sectional view of an example of a toner fixing member of the present invention.

  The toner fixing member of the present invention is formed, for example, by forming at least an elastic layer 12 and a surface layer 13 on a roll-shaped cored bar 11. Inside the hollow, a heat source (not shown) such as a halogen heater is arranged.

  For the metal core, a material such as aluminum or iron, which has a relatively high heat conductivity and can ensure rigidity, is usually selected.

  The elastic layer 12 is required to have heat resistance and flexibility, and the material is not particularly limited, but is preferably made of silicone rubber in view of the function.

  The type of the silicone rubber is not particularly limited as a form of the crosslinking reaction, but an addition reaction type or a peroxide reaction type is preferable in view of use in the toner fixing member. In particular, addition-reaction type silicone rubber is a material that can carry out the present invention more effectively due to incidental convenience such as ease of processing.

  Further, various types of functional groups are known for silicone rubber, but silicone rubbers having these known types of functional groups may be used. In particular, dimethyl silicone rubber having only a methyl group and methyl phenyl silicone rubber / phenyl silicone rubber having a phenyl group are well known and preferably used for toner fixing members, and can also be preferably used in the present invention.

  The silicone rubber may be blended with an inorganic powder filler for the purpose of heat resistance, heat transfer, reinforcement, increase in weight, and the like. Known inorganic fillers can be used. Examples thereof include crystalline silica, fumed silica, iron oxide, and alumina. Preferably, these inorganic fillers are blended in an amount of 0.1 to 100 parts by weight with respect to 100 parts by weight of the silicone rubber.

  In addition, a compounding agent may be added to the silicone rubber for adjusting various properties.

  The outermost layer 13 is required to have heat resistance and difficulty in adhesion of toner. The material is not particularly limited, but fluororesin and silicone rubber are suitable in view of functionality. In particular, fluororesin is a material that can more effectively implement the present invention in consideration of the characteristics of various fixing members.

  As the fluororesin, a known type of material can be used and is not particularly limited. Generally well-known polytetrafluoroethylene (PTFE), tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene / hexafluoropropylene copolymer (FEP), etc. are used singly or in combination. Can be used.

  Although the toner fixing member of the present invention is shown in FIG. 1 as a roller, it may be a belt using a metal or heat-resistant resin belt instead of the cored bar.

  Further, the thickness of the elastic layer is not particularly limited, but the effect of the present invention is exhibited in the thickness range of 50 μm to 1 mm, and more preferably in the range of 100 μm to 500 μm.

  Further, the thickness of the outermost layer is not particularly limited, but in the thickness range of 50 μm or less, the effect of the present invention can be expected more effectively, and more preferably 30 μm or less is particularly recommended as an embodiment of the present invention. The The lower limit of the thickness varies depending on the required mechanical strength, but it is practical to set the thickness to 10 μm or more.

  In the present invention, the surface shape of the outermost layer of the toner fixing member is important. Hereinafter, the surface shape will be described.

  The surface shape of the toner fixing member was measured using a three-dimensional surface structure analysis microscope (trade name: Zygo New View 5000, Canon Sales Co., Ltd.) with a 10 × objective lens and an image zoom of 1.0 × field of view. The obtained measurement data was separated by two-dimensional FFT at a wavelength of 50 μm using the analysis program Advanced Texture attached to the microscope, and the surface shape of less than 50 μm was digitized based on the arithmetic average roughness. As a value (Ra (<50)), similarly, a surface shape with a wavelength of 50 to 500 μm is obtained as a numerical value (Ra (50 ≦)) based on the arithmetic average roughness. The numerical values at this time are 0.05 μm or less and 0.1 to 0.4 μm, respectively, in order to achieve the effects of the present invention. That is, high image quality of a fixed image formed by heat-fixing a toner image is achieved, image uniformity is achieved in terms of gloss, and paper separation from the toner fixing member is satisfied.

  The toner fixing member of the present invention is formed on a base material made of a core metal or an endless belt so that an elastic layer material made of, for example, silicone rubber, fluorine rubber, preferably silicone rubber, has a thickness after heat curing of 300 μm. And then heat-cured to form an elastic layer. Further thereon, an outermost layer preferably made of a fluororesin is provided. As a forming method at this time, in the case of a roller-shaped toner fixing roller, a solution in which a fluororesin powder is dispersed is directly applied on an elastic layer, and after drying, the fluororesin is melted and fired to have a thickness of about 10 to 20 μm. It may be formed to a thickness or may be covered with a tube having a thickness of 20 to 50 μm. In any case, it is preferable to use an adhesive if necessary.

  The surface shape of the present invention may be processed by sandblasting after forming the outermost layer. However, an unevenness is formed on the elastic layer by spraying the elastic layer material as a solution, and this surface is unevenly formed in advance. A tube made of the outermost layer material may be put on the elastic layer on which the is formed, and the irregularities on the surface of the elastic layer may be reflected on the outermost layer surface. The unevenness of the elastic layer surface can be controlled by the material combination, spraying speed, spraying distance, spraying solution concentration, and the like.

  FIG. 2 is a schematic diagram of a toner fixing device incorporating the toner fixing member of the present invention.

  In the figure, reference numeral 21 denotes an upper roller, and reference numeral 22 denotes a lower roller arranged to be pressed against the upper roller 21. In the present invention, the toner fixing member of the present invention is used as at least the upper roller. The toner fixing member of the present invention may be used as the lower roller. A heater (not shown) is disposed in the upper roller, and the temperature is adjusted to a desired temperature through a thermistor (not shown).

  The portion sandwiched between the upper and lower rollers is called a toner fixing nip, and a recording material such as paper on which a toner image is formed is nipped and conveyed in this nip, and the toner is fixed and fixed by receiving heat and pressure. Get an image.

  The time required for the toner to pass through the nip is called the residence time, and is obtained from the width of the nip and the conveyance speed of the recording material passing therethrough (retention time = nip width / conveyance speed). The conveyance speed can be changed by controlling the rotation speed of the roller. The toner residence time is preferably 50 to 500 msec. If it is less than 50 msec, the toner may not be sufficiently fixed, and if it exceeds 500 msec, the recording material or the toner is thermally denatured or the required fixing time becomes too long.

  Hereinafter, the present invention will be described by way of examples.

Examples 1-2 and Comparative Examples 1-2
An aluminum pipe (roller) having an outer diameter of 30 mm, a thickness of 1.5 mm, and a length of 230 mm was prepared by applying a silicone primer (trade name: DY35-051, manufactured by Toray Dow Corning Silicone) on the surface.

  Addition reaction type two-component liquid silicone rubber raw material (average viscosity of two components: 290 Pa · s, thermal conductivity after thermosetting: 0.85 W / (m · K), 6 mm thick silicone rubber sheet) JIS-A hardness at 25 ° C. (30 °) was weighed and stirred, and uniformly coated to a thickness of 300 μm on the primer-coated aluminum pipe.

  Next, a solution prepared by mixing the silicone-based primer, the liquid silicone rubber raw material, and toluene at a weight ratio of 1: 1: 1 was sprayed onto the coated silicone rubber raw material surface by air spray. At this time, the spraying distance and the moving speed were repeatedly changed by trial and error, and a spray surface state of several levels was created on each roller. These rollers were treated in a hot stove at 150 ° C. for 30 minutes to perform primary vulcanization.

  Next, a heat-shrinkable PFA fluororesin tube having a thickness of 30 μm and an inner diameter of 30.8 mm and having an inner surface defluorinated was prepared, and the silicone primer was applied to the inner surface and dried naturally.

  The first vulcanized roller is covered with a naturally dried PFA fluororesin tube and treated in a hot air oven at 200 ° C. for 4 hours to finish the secondary vulcanization of silicone rubber and molding as a roller. A toner fixing member was produced.

  Then, the surface shape was measured with a three-dimensional surface structure analysis microscope, and the arithmetic average roughness of the surface shape with a wavelength of less than 50 μm and a wavelength of 50 to 500 μm was obtained from the measurement data using an analysis program. The results are shown in Table 1.

Example 3
A fixing member was produced in the same manner as in Example 1 except that the thickness of the PFA fluororesin tube was 50 μm. Table 1 shows the surface shape of the fixing member.

Example 4
Instead of coating the outermost layer with a PFA fluororesin tube coating, a silicone primer is applied to the surface of the elastic layer forming roller and air-dried, and a coating liquid (product name: PFA fluororesin powder dispersed thereon) AD-2CR (manufactured by Daikin Industries Co., Ltd.), dried and calcined in a heated hot air circulating furnace at 320 ° C. for 30 minutes, and then pressed the roller surface against a smooth metal plate heated to 330 ° C. A fixing member was produced in the same manner as in Example 1 except that the surface was smoothed. Table 1 shows the surface shape of the fixing member.

Comparative Example 3
Using the toner fixing member produced in the same manner as in Example 1, the surface was lightly polished with a cloth containing diamond paste, and the surface shapes were Ra (<50) = 0.08 μm, Ra (50 ≦) = A toner fixing member having a size of 0.3 μm was obtained.

  Two rollers are prepared for each of the rollers of Examples 1 to 4 and Comparative Examples 1 to 3, and the upper and lower rollers are incorporated in the toner fixing device shown in FIG. 2, and the residence time at the toner fixing nip is 100 msec. Thus, each performance was evaluated. The heat source was a 500-w halogen lamp inserted into the upper and lower rollers.

  The performance was evaluated by both image quality evaluation and paper separation property evaluation.

  For the toner image, a creative processor 680 (trade name: CP680, Canon Inc.) was used so that the paper could be taken out before the fixing device, and an unfixed toner image was obtained.

  For image evaluation, color laser copier paper (trade name: TKCL-A4, Canon Sales Co., Ltd.) was used as the paper. The image was a solid image with a cyan density of 100%. In the paper separation evaluation, thin paper was used as the paper, and the image was a solid image with a cyan density of 100%.

  The image was evaluated by sensory evaluation in order to determine the toner image with high sensitivity. A plurality of toner-fixed images to be evaluated were prepared, and each of them was randomly repeated 10 times, and attention was paid to uneven glossiness of the image, and “◯ = not feel uneven” or “× = feel uneven” was determined. In addition, when it was difficult to determine, “△ = somewhat felt” was set. Here, in order to maintain consistency of evaluation, the image obtained in Comparative Example 2 was adopted as a sample of “◯ = no unevenness” and evaluated as a relative comparison from the sample.

  The evaluation of the paper separation property was made by visually observing the vicinity of the nip exit where the paper comes out of the toner fixing device, and making the determination of “◯ = no problem” and “× = with upper winding” by repeating 20 times, When “× = with upper winding” is 50% or more, the determination is “× = with upper winding”.

  The evaluation results are shown in Table 1.

  Regarding gloss unevenness, Examples 1-4 and Comparative Example 2 with small Ra (<50) had good image quality. In Comparative Example 3 having a large Ra (<50), gloss unevenness occurred and the desired high image quality could not be obtained. In Comparative Example 1, although Ra (<50) was small, large waviness that was attributed to the size of Ra (50 ≦) was generated on the paper, and the gloss unevenness was somewhat felt.

  In addition, as for paper separation properties, Ra 1 (50 ≦) was 0.1 or more and Examples 1 to 4 and Comparative Example 1 showed no problem, but Ra (50 ≦) was less than 0.1. In the comparative example 2, it was a result of winding up.

  From the above results, it was proved that the intended effect can be obtained by the means of the present invention.

FIG. 3 is a cross-sectional view of an example of a toner fixing member according to the present invention. FIG. 2 is a schematic diagram illustrating an example of a toner fixing device according to the present invention.

Explanation of symbols

11 Core Bar 12 Elastic Layer 13 Outermost Layer 21 Upper Roller 22 Lower Roller 23 Recording Material (Paper)

Claims (4)

In an electrophotographic fixing member having at least an elastic layer and having an outermost layer having a thickness of 10 to 50 μm formed thereon,
About the surface shape of the outermost layer, the arithmetic average roughness (Ra (<50)) of a wavelength of less than 50 μm is 0.05 μm or less, and the arithmetic average roughness (Ra (50 ≦)) of a wavelength of 50 to 500 μm. A toner fixing member, wherein the toner fixing member is 0.1 to 0.4 μm.   The toner fixing member according to claim 1, wherein the elastic layer is made of silicone rubber, and the outermost layer is made of a fluororesin.   3. A toner fixing device, wherein at least one toner fixing member according to claim 1 is disposed as a fixing member on a heating side.   The toner fixing device according to claim 3, wherein a toner residence time is 50 to 500 msec in a toner fixing nip formed by the toner fixing member.

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