JP2006084679A - Toner fixing member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To stably obtain toner images of very high quality as regards toner fixed images at the time of continuous paper supply. <P>SOLUTION: Toner fixing members are used in a toner fixing unit, and at least one of the members is pressurized to form a nip, and toner is heated and pressurized from inside surfaces of base material within the nip to obtain a multicolor fixed image on a recording medium. Each toner fixing member includes at least an elastic layer which is provided on the base material and contains silicone rubber, and a surface layer containing a fluorinated resin, and the surface layer has a thickness d1 of 10μm to 50μm, and the elastic layer has a thermal diffusivity (a) of 0.1mm<SP>2</SP>/sec to 2.0mm<SP>2</SP>/sec at 25°C and has a JIS-A hardness of 1 to 30 degrees and has a thickness d2 of ≤1,000μm. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  In the present invention, a color image is formed and supported on a recording material (recording medium) by superimposing a plurality of color toner images, and the recording material is heated and pressed by a fixing unit to fix the color image on the recording material. The present invention relates to a toner fixing member used for toner fixing of an electrophotographic copying machine or printer, and a toner fixing device including the toner fixing member.

  In recent years, as color printing has become widespread, there are opportunities to output photographic images and general business documents in color, and full-color fixing devices are applied to copiers, laser beam printers, and personal printers for individuals. Yes. Therefore, higher image quality, higher speed, and higher reliability are required. One of the demands for higher image quality is an appropriate glossiness of a fixed image on paper. In toner fixing in an electrophotographic process, a fixing member in which a surface layer of a fluororesin having a good toner release property is directly or indirectly formed on an elastic layer made of a flexible elastic material such as silicone rubber is used in various variations. ing. For example, the silicone rubber of the elastic layer has been devised to use a low-hardness rubber in order to exert a more elastic effect, or to effectively exert the function of the elastic layer by thinning the fluororesin. .

  Further, when the toner is continuously fixed on the recording material, a contrivance has been made to obtain a stable and good quality toner-fixed image even in the thermal physical properties of the silicone rubber of the elastic layer and even during continuous paper feeding. . These fixing member configurations greatly affect the image quality of the toner image after fixing both during continuous paper feeding. Therefore, in order to stably obtain an appropriate glossiness of a fixed image during continuous paper feeding, the thickness of the surface layer and the elastic layer, and the thermal diffusivity and hardness of the elastic layer are taken into consideration, and these optimum conditions are determined. It is important to guide.

On the other hand, in the conventional fixing device, the optimum condition for improving the image quality of OHP is derived from the relationship between the thickness of the fluororesin surface layer, the thermal conductivity of the elastic layer, and the pressure applied to the nip. (See Patent Document 1). In the embodiment of the present invention, a method of using polyimide as a base material of a fixing member is shown. In some cases, an optimum condition for improving image quality is derived from the relationship between the thermal conductivity and heat capacity of the surface layer and the inner layer (see Patent Document 2). In this invention, the heating method of the fixing member is intended for an external heating system.
JP 09-244450 A JP 2000-112268 A

  However, the fixing members described in Patent Documents 1 and 2 have not been studied from the viewpoint of controlling characteristic values (layer thickness, thermal diffusivity, hardness) that greatly affect the image quality, and are still sufficiently high. The image quality was not improved. Further, in these fixing members, there are cases where the cost is high due to the use of a specific material and it is difficult to control the physical property values. The present invention has been made in view of the above situation.

That is, according to the present invention, in a toner fixing member in which a base material made of metal, an elastic layer of silicone rubber for the purpose of elastic effect, and a surface layer of a fluororesin is formed, the surface layer thickness is d1 [μm]. The thickness range is d1 ≦ 50, the elastic layer JIS-A hardness is 1 ° to 30 °, the thermal diffusivity a is 0.1 ≦ a ≦ 2.0 [mm ² / sec], and the elastic layer thickness By using d2 [μm] in the range of d2 ≦ 1000, it is possible to obtain a high-quality toner-fixed image that can stably express appropriate glossiness even during continuous paper passing in the toner image after fixing. This is the main purpose of the invention. Furthermore, the type of silicone rubber that is an elastic layer uses addition-type silicone rubber in consideration of processing with high accuracy.

In the present invention, a metal having a large heat capacity is used as the base material, and the thermal diffusivity of the silicone rubber as the elastic layer is in the range of 0.4 ≦ a ≦ 1.0 [mm ² / sec], and the thickness is By reducing the layer thickness to 100 ≦ d2 ≦ 500 when d2 [μm], the thermal response is improved from the viewpoint of heat capacity, and the object is to provide excellent thermal characteristics and flexibility.

  Another object of the present invention is to provide a good balance between flexibility and mechanical strength by using the fluororesin surface layer in a thickness range of 20 ≦ d1 ≦ 40, where d1 [μm] is the thickness of the fluororesin surface layer.

  The first invention according to the present application is the minimum necessary for the main purpose of the present invention. A base material made of a metal, an elastic layer of silicone rubber for the purpose of an elastic effect, and a surface layer of a fluororesin are formed. In the toner fixing member, the thickness of the fluororesin on the surface layer (d1), the thickness of the elastic layer (d2), the thermal diffusivity of the elastic layer (a), and the JIS-A hardness range of the elastic layer can be specified. An object of the present invention is to stably obtain an extremely high-quality toner image in a toner-fixed image when paper is passed.

In order to achieve the above object, the present invention has the following configuration. That is, the present invention is a toner fixing member having at least an elastic layer containing silicone rubber provided on a substrate and a surface layer containing a fluororesin provided on the elastic layer,
The thickness d1 of the surface layer is 10 μm ≦ d1 ≦ 50 μm,
The elastic layer has a thermal diffusivity a at 25 ° C. of 0.1 mm ² /sec≦a≦2.0 mm ² / sec, a JIS-A hardness of 1 ° to 30 °, and a thickness d2 of d2 ≦ 1000 μm.
The present invention relates to a toner fixing member.

As described above, according to the present invention, in the toner fixing device used in the electrophotographic apparatus, the range of the thermal diffusivity is 0.1 ≦ a ≦ 2.0 (mm ² / mm) on the metal roller or film as the base material. sec), an elastic layer having a JIS-A hardness of 1 to 30 ° and a thickness range of d2 ≦ 1000 (μm) is provided, and a release layer having a thickness range of 10 ≦ d1 ≦ 50 (μm) is provided on the surface layer. By using the toner fixing member and pressing the recording material against the fixing member at the nip by the heating and pressing means, a high-quality color fixed image that can be expressed without deteriorating good glossiness during continuous paper feeding I was able to obtain it stably.

  An example of an embodiment of the present invention is shown in FIG. 11 is a fluororesin on the surface layer, 12 is a silicone rubber as an elastic layer, and 13 is a metal substrate.

  The toner fixing member of the present invention can be implemented in a known form such as a roller or a belt, and can also be applied as a member for heating and pressing. At least the outermost layer (surface layer) is a fluororesin, and the elastic layer is a toner fixing member made of silicone rubber. Known materials can be used for these layers. Moreover, another layer can also be provided between these layers. For example, a primer layer for adhesion or a mixed / single layer of fluororubber and / or fluororesin may be provided as an intermediate layer between the outermost layer and the elastic layer. The elastic layer can be formed on a metal or heat resistant resin substrate.

  The kind of fluororesin can be a known kind of material, but is not particularly limited. Generally well known, such as polytetrafluoroethylene (PTFE), tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene / hexafluoropropylene copolymer (FEP), It is preferable to use a material.

  The thickness d1 of the fluororesin that is the outermost layer (surface layer) needs to be 10 μm or more and 50 μm or less. In order to obtain an expected image quality in consideration of the image quality after toner fixing, a thinness that does not impair the intended flexibility is required. In consideration of mechanical strength, the thickness is more preferably 10 μm or more and 30 μm or less. When d1 is within these ranges, a toner fixing member excellent in toner releasability can be obtained, and an image having a better gloss feeling can be obtained.

  The type of the silicone rubber that is the elastic layer is not particularly limited as the form of the crosslinking reaction, but since the thickness of the silicone rubber of the elastic layer is thin, an addition type silicone rubber is preferably used in consideration of processing with high accuracy.

  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.

  Silicone rubber is blended with an inorganic powdery filler for the purpose of heat resistance, heat transfer, reinforcement, increase, etc., and good thermal responsiveness can be obtained by blending this filler. Moreover, the hardness which can anticipate the elastic effect as an elastic layer can be obtained by using these inorganic type fillers. Known inorganic fillers can be used. Examples thereof include crystalline silica, fumed silica, iron oxide, zinc oxide, and alumina. Preferably, these inorganic fillers are used by blending 0.1 to 100 parts by mass with respect to 100 parts by mass of silicone rubber. In addition, a compounding agent may be added to the silicone rubber for adjusting various properties.

The thermal diffusivity a of the elastic layer needs to be in the range of 0.1 to 2.0 (mm ² / sec). More preferably, the thermal diffusivity a is preferably in the range of 0.4 to 1.0 (mm ² / sec).
Such a thermal diffusivity can be changed by adjusting the kind and blending amount of the inorganic filler. Silicone rubber can be obtained as a commercially available silicone rubber of high thermal conductivity grade, and the thermal diffusivity can be adjusted depending on the type of silicone rubber. At this time, rubber having a desired hardness to some extent is available.

In addition, the thermal diffusivity a can be calculated | required by Formula (1).
Formula (1): a = κ / (Cp × ρ) × 10 ⁶
Here, a: thermal diffusivity (mm ² / sec), κ: thermal conductivity (W / m · K), Cp: specific heat (J / kg · K), ρ: density (kg / m ³ ) .

  Regarding the specific heat Cp in the formula (1), a differential scanning calorimeter (Seiko Instruments Inc.) was used by using a sample of elastic layer silicone rubber cut out to a weight of about 10 mg according to the method described in JIS K 7123. The specific heat Cp can be obtained by measuring under the condition that the temperature is raised at a rate of 10 ° C./min from room temperature to 400 ° C. in a nitrogen atmosphere with RDC 220).

  Moreover, the JIS-A hardness of the silicone rubber which is an elastic layer needs to be 1-30 degrees. In order to obtain an expected image quality in consideration of the image quality after toner fixing, a softness that does not impair the intended flexibility is required. The JIS-A hardness of the elastic layer is preferably 5 to 30 ° considering the durability of the silicone rubber. The JIS-A hardness was measured according to JIS K 6301 by preparing a sheet having a thickness of 6 mm at 25 ° C. as described in the Examples. Such JIS-A hardness can be changed by blending an inorganic filler into silicone rubber or adjusting the crosslinking form / crosslinking density of the silicone rubber. It can be obtained from the material manufacturer.

  The thickness d2 of the silicone rubber that is the elastic layer needs to be 1000 μm or less. d2 is preferably 100 μm or more, and this is to obtain a thickness at which an elastic effect can be expected as the elastic layer. Further, although not particularly limited, the thickness d2 of the elastic layer is preferably 500 μm or less so that the relationship between the surface layer thickness and the nip pressure, which is the object of the present invention, is more effectively exhibited. d2 is more preferably 200 to 400 μm. When d2 is within these ranges, the flexibility and durability and the toner fixing property to the recording medium can be excellent.

  The nip residence time is up to 400 msec. The nip residence time is the time required for the recording medium on which the toner is transferred to pass through the nip formed by pressurizing one member.

  Normally, the nip residence time can be designed from several tens to several hundreds msec, but a range of 50 to 100 msec is preferable in consideration of high-speed fixing. This time, in order to confirm the effect of the present invention more practically, the evaluation target was up to 400 msec.

  FIG. 2 shows an outline of a toner fixing device provided with the toner fixing member of the present invention. In the toner fixing device of the present invention, the fixing roller 21 and the pressure roller 22 rotate in the directions 2a and 2b, respectively, and the recording material P carrying the unfixed toner Ta passes through the nip of the rollers 21 and 22 during this rotation. To do. At this time, the toner Ta is heat-fixed on the recording material P. The fixing roller 21 and the pressure roller 22 have a built-in heater 23 so that the roller can be heated.

(Glossy evaluation method)
A fixing member for carrying out the present invention and confirming the effect was prepared, and incorporated in a fixing device as shown in FIG. ) Was continuously applied while a non-fixed toner image was passed through, and the image quality of the toner fixed image in the initial and latter half of the paper pass was evaluated.

Cyan toner (manufactured by Canon Inc.) for color laser copier 800 (CLC800) was used for toner image creation. The toner image was prepared so that the sheet could be taken out before the fixing device, and an unfixed toner image was obtained. As the paper, cast-coated paper (product number: 0611A008 Canon Sales Co., Ltd.) was used. For the evaluation of gloss, an unfixed solid image having a toner paste amount (mg / cm ² ) per unit area of 1.0 was prepared.

The evaluation of the image was performed by sensory evaluation in order to accurately determine the extremely high quality toner image that is the object of the present invention. First, with regard to the glossiness of the image, in order to give universality to the evaluation, a standard sample image was prepared and the evaluation criteria were matched. That is, three sample images having gloss values of 50, 60, and 70 (Horiba, Ltd. IG-320 using an incident angle of 60 °) were prepared. This was prepared by placing cyan toner on an aluminum sheet, which is a smooth surface, so that the amount of toner (mg / cm ² ) per unit area was 1.0 and hot pressing under various conditions. After showing these three sample images to several test subjects and recognizing that “the glossiness is sufficient”, for the solid image in which the present invention was implemented, “◎ = appropriate glossiness”, Evaluation was made at four levels: “◯ = glossy”, “Δ = low glossy”, and “× = no glossy”. In this way, each of the initial image and the 50th fixed image was evaluated. In addition, the gross value of such sensory evaluation was roughly ◯ for 70 or more, ◯ for 50 to 70, and Δ and X as it became lower than 50.

[Example 1]
First, an addition reaction type two-component liquid silicone rubber raw material A (product number: DY35-4039A / B manufactured by Toray Dow Corning Silicone) was prepared as a silicone rubber for the elastic layer. Regarding the physical properties of rubber after thermosetting, the thermal diffusivity was 2 mm ² / sec. Moreover, it was 30 degrees when JIS-A hardness in 25 degreeC of the 6 mm sheet | seat of this silicone rubber was measured.

  Next, a fixing member for image evaluation was prepared. First, an aluminum roller core having an outer diameter of 60 mm was prepared as a base material. A primer for silicone (DY39-051, Toray Dow Corning Silicone Co., Ltd.) was thinly coated on the surface of this base material, and heat-treated for 1 hour in a 200 ° C. hot air oven. After cooling, the silicone rubber raw material A was applied to a roller core metal with a thickness of 1000 μm, and heat-treated in a warm air oven at 150 ° C. for 30 minutes. Next, a PFA sheet having a thickness of 10 μm was prepared. After defluorinating the inner surface of this PFA sheet, a primer for silicone (DY39-051, Toray Dow Corning Silicone Co., Ltd.) was thinly coated, and heat-treated in a hot air oven at 200 ° C. for 1 hour. Unvulcanized silicone rubber (same type as the elastic layer: liquid silicone rubber raw material A) was applied. The PFA sheet coated with the liquid silicone rubber raw material A is wound around the roller coated with the liquid silicone rubber raw material A so that the liquid silicone rubber raw material A is in contact with each other. Then, both ends in the circumferential direction were sandwiched so as not to become, and heat treatment was performed at 200 ° C. for 4 hours to vulcanize and bond the elastic layer and the surface layer, and both ends in the circumferential direction were cut. As a result, as shown in FIG. 1, a fixing member was obtained in which the elastic layer 12 had a silicone rubber thickness of 1000 μm and the surface layer 11 had a PFA thickness of 10 μm.

The fixing member obtained as described above is incorporated into a fixing device as shown in FIG. 2, and the surface temperature is set to 150 ° C. by the halogen heater 23 in the hollow portion of the upper and lower rollers and a temperature detection sensor (not shown) on the roller surface. In this way, 10,000 sheets of unfixed solid images were continuously passed through while applying 1 to 10 mg of silicone oil per A4 sheet on the PFA surface. The nip pressure was controlled to 2.0 × 10 ⁴ Pa by spring-pressing the upper roller 21 and the lower roller 22, and the experiment was conducted by adjusting the rotational speed of the upper and lower rollers so that the nip residence time was 200 msec. Normally, the nip residence time can be designed from several tens to several hundreds msec, but a range of 50 to 100 msec is preferable in consideration of high-speed fixing. This time, in order to confirm the effect of the present invention more practically, the evaluation was performed at 200 msec.

  Table 1 shows the results of glossiness (gross) at the initial stage of passing paper and after passing 10,000 sheets. It was possible to obtain a toner-fixed image that appeared without deteriorating appropriate glossiness even during continuous paper feeding. Table 1 summarizes the implementation details and evaluation results of Examples 1 to 12 and Comparative Examples 1 to 4.

[Example 2]
In the fixing device of Example 1, an evaluation experiment was performed by the same method except that the thickness of the silicone rubber of the elastic layer was changed from 1000 μm to 300 μm. As a result, good results were obtained for both the initial gloss and the gloss after passing 10,000 sheets.

  Hereinafter, in Examples 3 to 12 and Comparative Examples 3 and 4, fixing members having different thermal diffusivity and JIS-A hardness from those of Examples 1 and 2 were prepared by changing the type and composition of the material of the elastic layer. .

[Example 3]
In the fixing device of Example 1, an evaluation experiment was conducted by the same method except that the thermal diffusivity a of the silicone rubber of the elastic layer was changed from 2 mm ² / sec to 0.1 mm ² / sec. I was able to get it.

[Example 4]
In the fixing device of Example 3, when an evaluation experiment was performed by the same method except that the JIS-A hardness of the silicone rubber of the elastic layer was changed from 30 ° to 1 °, good results could be obtained.

  A slight decrease was observed in the gloss after passing 10,000 sheets. This is thought to be due to the fact that the durability of the rubber is inferior because the hardness of the rubber is reduced, and the result is reflected in the gloss. However, this is a level that can withstand practical use.

[Example 5] to [Example 8]
All obtained good results.

[Example 9]
In the fixing device of Example 7, when an evaluation experiment was performed by the same method except that the film thickness d1 of the surface PFA was changed from 10 μm to 50 μm, both the initial gloss and the gloss after passing 10,000 sheets were slightly inferior. became. This is because the thickness of the surface layer PFA is large, which hinders heat conduction as a member, and the result is considered to be reflected in the gloss. However, this is a level that can withstand practical use.

[Example 10]
In the fixing device of Example 9, when an evaluation experiment was performed by the same method except that the film thickness d2 of the silicone rubber of the elastic layer was changed from 1000 μm to 300 μm, good results were obtained.

[Example 11] to [Example 12]
All obtained good results.

[Comparative Example 1]
In the fixing device of Example 1, an evaluation experiment was performed by the same method except that the film thickness d1 of the PFA on the surface layer was changed from 10 μm to 500 μm. However, satisfactory results were not obtained. This is presumably because the surface layer was too thick, which hindered heat conduction.

[Comparative Example 2]
In the fixing device of Example 1, an evaluation experiment was performed by the same method except that the thickness d2 of the silicone rubber of the elastic layer was changed from 1000 μm to 5000 μm. However, satisfactory results were not obtained. This is presumably because the heat conduction was hindered because the elastic layer was too thick.

[Comparative Example 3]
In the fixing device of Example 1, an evaluation experiment was performed by the same method except that the thermal diffusivity a of the silicone rubber of the elastic layer was changed from 2 mm ² / sec to 0.01 mm ² / sec. It was not obtained. This is presumably because the thermal diffusivity of the elastic layer is inappropriate.

[Comparative Example 4]
In the fixing device of Example 1, an evaluation experiment was performed by the same method except that the JIS-A hardness of the silicone rubber of the elastic layer was changed from 30 ° to 90 °. However, satisfactory results were not obtained. This is presumably because the hardness of the elastic layer is inappropriate and the followability to the toner image on the surface of the member is deteriorated.

The thermal diffusivity of the elastic layer silicone rubber in which any of the gloss evaluations at the initial stage of passing paper and the 10,000th paper passing becomes “◎” or “○” in the sensory evaluation based on the results of the above Examples and Comparative Examples. And the JIS-A hardness range is 0.1 mm ² /sec≦a≦2.0 mm ² / sec when the thermal diffusivity of the elastic layer silicone rubber is a, and the JIS-A hardness is 1-30. ° is appropriate. Accordingly, in the fixing device embodying the present invention, when the relationship between the thermal diffusivity a of the elastic layer silicone rubber and the JIS-A hardness is in the range as described above, the glossiness is lowered even during continuous paper feeding. It became clear that stable and high image quality fixing could be achieved, and the effectiveness of the present invention could be confirmed.

Examples of embodiments of the present invention Example of roller fixing device (used in embodiments of the present invention)

Explanation of symbols

11 Surface layer 12 Elastic layer 13 Base material 21 Upper roller 22 Lower roller 23 Halogen heater 2a Upper roller rotation direction 2b Lower roller rotation direction P Recording material Ta Toner

Claims (6)

A toner fixing member having at least an elastic layer containing silicone rubber provided on a base material and a surface layer containing a fluororesin provided on the elastic layer,
The thickness d1 of the surface layer is 10 μm ≦ d1 ≦ 50 μm,
The elastic layer has a thermal diffusivity a at 25 ° C. of 0.1 mm ² /sec≦a≦2.0 mm ² / sec, a JIS-A hardness of 1 ° to 30 °, and a thickness d2 of d2 ≦ 1000 μm.
And a toner fixing member.   The toner fixing member according to claim 1, wherein an addition-type silicone rubber is used as the silicone rubber. The thermal diffusivity a is, the toner fixing member according to claim 1 or 2, characterized in that a 0.4mm ² /sec≦a≦1.0mm ² / sec.   The toner fixing member according to claim 1, wherein a thickness d2 of the elastic layer satisfies 100 μm ≦ d2 ≦ 500 μm.   The toner fixing member according to claim 1, wherein a thickness d1 of the surface layer is 10 μm ≦ d1 ≦ 30 μm. A nip is formed by a toner fixing member and a pressure roller pressed against the toner fixing member, and a recording medium on which an unfixed toner image is formed is passed through the nip. During this passage, the recording medium is heated and pressurized. A fixing device for fixing the unfixed toner image on a recording medium to obtain a multicolor fixed image,
The fixing device according to claim 1, wherein the toner fixing member is the toner fixing member according to claim 1.

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