JP2006039113A - Toner fixing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a toner fixing device capable of extremely high quality toner image in which both appropriate glossiness and character reproducibility (prints with less character crush) are achieved. <P>SOLUTION: In the toner fixing device for forming a multi-color fixed image on a recording medium by applying heat and pressure to toner in a nip, a member that is in contact with the toner has at least an elastic layer formed from a silicone rubber and a surface layer formed from a fluorinated carbon resin. The thickness of the surface layer dl[μm] is within a thickness range expressed by 10≤d1≤50, and nip pressure P[Pa] is within a pressure range expressed by (-2.5×10<SP>3</SP>)dl+3.2×10<SP>5</SP>≤P≤(-1.2×10<SP>3</SP>)dl+1.1×10<SP>5</SP>. Further, the elastic layer formed from the silicone roller has a thermal conductivity of 0.4 to 0.9[W/mk] at 25°C and a JIS-A hardness of 25° to 40°, and its layer thickness d2[μm] is d2≤1000. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electrophotographic method in which a color image is formed and supported on a recording paper by superimposing a plurality of color toner images, and the recording paper is heated and pressed by a fixing means to fix the color image on a recording material. The present invention relates to a toner fixing device used for fixing toner in a copier or printer.

  In recent years, as color printing has become widespread, opportunities for outputting photographic images and general business documents in color have increased, and there has been a demand for character reproducibility (printing with less character crushing) as well as appropriate glossiness of the printed image. ing. Due to such a demand for high image quality, 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 in toner fixing in an electrophotographic process. Fixing members are used in various variations. For example, ingenuity has been made to use a low-hardness rubber so that the silicone rubber of the elastic layer exhibits a more elastic effect, or to effectively exhibit the function of the elastic layer by thinning the fluororesin.

  Or, in order to obtain a high-quality toner-fixed image even under process conditions such as temperature and pressure applied when the toner is fixed to the recording material, and nip residence time. Both the configuration of the fixing member and the process conditions when pressing the toner greatly affect the image quality of the toner image after fixing. Therefore, in order to obtain a high-quality toner image that achieves both appropriate glossiness and character reproducibility (printing with less character crushing), both the member configuration and the process conditions must be considered, and the member configuration It is important to derive the optimum conditions for the process conditions.

  In Patent Document 1, an optimum condition for improving the image quality is derived from the relationship between the thickness of the fluororesin surface layer and the amount of distortion of the fixing member with respect to the pressure. In the embodiment of the present invention, a method using HTV silicone rubber for the elastic layer of the fixing member is shown. In Patent Document 2, the optimum condition for improving the image quality is derived from the relationship between the thickness of the fluororesin surface layer and the pressure. In the present invention, a relatively low hardness silicone rubber is used as the elastic layer.

JP-A-10-213990 JP 2001-215767 A

The present invention provides a toner fixing member in which an elastic layer of silicone rubber for the purpose of elastic effect and a surface layer of fluororesin is formed, and the thickness is in the range of 10 ≦ d1 ≦ 50 when the surface layer thickness is d1 [μm]. When the nip pressure is P [Pa], (−2.5 × 103
) · D1 + 3.2 × 10 5 ≦ P ≦ (−1.2 × 10 3) · d1 + 1.1 × 10 5, by using the toner image after fixing, appropriate gloss and character reproducibility (character The main object is to obtain an extremely high-quality toner image that achieves both printing with less crushing. The type of silicone rubber that is the elastic layer is 25 ° to 40 ° with a relatively high JIS-A hardness, and an addition reaction type is used in consideration of processing with high accuracy.

  The second object of the present invention is to improve the thermal response from the viewpoint of heat capacity by reducing the layer thickness to 100 ≦ d2 ≦ 500 when the thickness of the silicone rubber as the elastic layer is d2 [μm]. Is to provide excellent thermal properties.

  Furthermore, a third 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 when the thickness of the fluororesin surface layer is d1 [μm]. It is.

The first invention is the minimum necessary for the main purpose of the present invention, and is a toner fixing member in which an elastic layer of silicone rubber for the purpose of elastic effect and a surface layer of a fluororesin are formed. The relationship between the thickness (d1) and the nip pressure is (−2.5 × 10 ³ ) · d1 + 3.2 × 10 ⁵ ≦ P ≦ (−1.2 × 10 ³ ) · d1 + 1.1 × 10 ⁵ By using the relationship, it is an object to obtain a toner image with extremely high image quality in the toner image after fixing.

  2nd invention is invention about the silicone rubber of 1st invention, and it aims at achieving the main objective of this invention more effectively.

  The third invention is an invention relating to the silicone rubber of the first or second invention, and aims to provide excellent thermal characteristics and simultaneously achieve the main object of the present invention.

  A fourth invention is an invention relating to the fluororesins of the first to third inventions, and aims to provide a good balance between flexibility and mechanical strength and simultaneously achieve the main object of the present invention.

  The fifth invention is an invention relating to the toner fixing device of the first to fourth inventions, and aims to more effectively achieve the object of each invention.

  A sixth invention is an invention relating to the toner fixing device of the first to fifth inventions, and aims to achieve the object of each invention more effectively.

In order to achieve the above object, according to the first aspect of the present invention, a nip is formed by pressurizing at least one member, and a toner is heated and pressed in the nip to obtain a multicolor fixed image on a recording medium. In the toner fixing device, the member in contact with the toner has at least an elastic layer made of silicone rubber and a surface layer made of fluororesin, and the thickness of the surface layer is d1 [μm], and a thickness range of 10 ≦ d1 ≦ 50. When the nip pressure is P [Pa], (−2.5 × 10 ³ ) · d1 + 3.2 × 10 ⁵ ≦ P ≦ (−1.2 × 10 ³ ) d1 + 1.1 × 10 ⁵ In an elastic layer made of silicone rubber, the thermal conductivity at 25 ° C. is 0.4 to 0.9 [W / m · k], and the JIS-A hardness is 25 ° to 40 °. When the layer thickness is d2 [μm], The thickness is d2 ≦ 1000.

  According to a second aspect of the present invention, in the first aspect of the present invention, the elastic layer uses an addition type silicone rubber.

  A third aspect of the invention is characterized in that, in the first or second aspect of the invention, when the thickness of the silicone rubber layer is d2 [μm], the thickness range is 100 ≦ d2 ≦ 500.

  The invention according to claim 4 is characterized in that, in the invention according to any one of claims 1 to 3, when the thickness of the surface layer is d1 [μm], the thickness range is 20 ≦ d1 ≦ 40.

The invention according to claim 5 is the invention as set forth in any one of claims 1 to 4, wherein (-1.9 × 10 ³ ) · d1 + 2.1 × 10 ⁵ ≦ when the nip pressure is P [Pa]. It is used in a pressure range of P ≦ (−1.2 × 10 ³ ) · d1 + 1.1 × 10 ⁵ .

  According to a sixth aspect of the present invention, in the invention according to any one of the first to fifth aspects, the time during which the recording paper is heated and pressurized in the nip (nip residence time) is 400 msec or less. .

According to the present invention, in an electrophotographic toner fixing device, an elastic layer having a thickness range of d2 ≦ 1000 (μm) is provided on a metal or resin film as a base layer, and a thickness range of 10 ≦ d2 ≦ 50 ( (μm) using a toner fixing member provided with a release layer, the nip pressure (P) of the recording material is set to (−2.5 × 10 ³ ) · d1 + 3.2 × 10 ⁵ ≦ P ≦ (−1.2 × 10 ³ ) · d1 + 1.1 × 10 ⁵ is pressed against the fixing member, and the toner image after fixing exhibits a good glossiness and high-quality color fixing with less character crushing. An image can be obtained.

  An example of the 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 substrate.

  The toner fixing member of the present invention can be implemented by a known member such as a roller or a belt, and can also be applied as a member for heating and pressing. At least the outermost layer is a fluororesin, the elastic layer is a toner fixing member made of silicone rubber, and the layer structure can take a known form. For example, a primer layer for adhesion or a mixture / single layer of fluoro rubber and / or fluoro resin 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, and 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 of the fluororesin as the outermost layer is 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. The lower limit of the thickness is not particularly limited, but considering mechanical strength, it can be said that 1 μm or more, particularly 10 μm or more is preferable.

  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 reaction type 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.

  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 used by blending 0.1 to 100 parts by weight with respect to 100 parts by weight of silicone rubber. In addition, compounding agents may be added to the silicone rubber to adjust various properties.

  The thickness of the silicone rubber as the elastic layer is set to 1000 μm or less. More preferably, it is 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 upper limit of the thickness of the elastic layer is preferably 500 μm 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.

  The nip residence time is up to 400 msec. The nip residence time is a time required for the recording medium on which the toner is transferred to pass through a 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. In this embodiment, in order to confirm the effect of the present invention more practically, the evaluation target is up to 400 msec.

  In order to confirm the effect of the present invention, two types of fixing members having different thicknesses of the surface layer PFA were prepared and incorporated in a fixing device as shown in FIG. 2, and dimethyl silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd.) was formed on the surface of the surface layer PFA. , Trade name, KF-96SS), and an unfixed toner image was passed through while applying a small amount, and the image quality of the toner fixed image 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 evaluation of gloss and character crushing, the amount of applied toner per unit area (mg / cm 2)
) 1.0 and an unfixed solid image and a 5-point character printed unfixed image were prepared.

The evaluation of the image was carried out by sensory evaluation in order to determine with high sensitivity the extremely high quality toner image that is the object of the present invention. First, with respect 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. using IG-320 incident angle of 60 °) were prepared. This is because the amount of applied toner (mg / cm 2) per unit area of cyan toner on an aluminum sheet that is a smooth surface.
) Was 1.0, and it was manufactured by hot pressing under various conditions. After showing these three sample images to several test subjects and recognizing that “the glossiness is sufficient”, the solid images in which the present invention was implemented were “o = glossy”, “× = We had you evaluate in two levels of "less glossiness". Furthermore, as for the character collapse of the image, a fixed image of a 5-point character was used, and it was evaluated at two levels: “○ = characters clearly understood” and “× = characters are collapsed (or difficult to read)”. .

  First, as the silicone rubber of the elastic layer, an addition reaction type two-component mixed liquid silicone rubber raw material was prepared. Regarding the physical properties of the rubber after thermosetting, the thermal conductivity was 0.8 W / m · K. Further, the JIS-A hardness at 25 ° C. of a 6 mm sheet of this silicone rubber was measured and found to be 30 °.

  Next, a fixing member for image evaluation was prepared. First, an aluminum roller core having a length of 10 cm and an outer diameter of φ60 mm was prepared as a base material. Usually, the length of the base material is 20 to 30 cm in accordance with A3 or A4 paper, but in this embodiment, in order to confirm only the effect of the present invention, a short base material is used so that the fixing member can be easily manufactured. Using. 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 stock solution was applied to a thickness of 480 μm on the roller mandrel, and heat treatment was performed for 30 minutes in a warm air oven at 150 ° C.

  Next, a PFA sheet having a thickness of 12 μm was prepared. After defluorinating the inner surface of this PFA sheet, a silicone primer (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) was applied. The PFA sheet is wrapped around a roller heat-treated with the above-described silicone stock solution, sandwiched at both ends in the circumferential direction so that the PFA does not wrinkle, and heat-treated at 200 ° C. for 4 hours to form an elastic layer and a surface layer. Was vulcanized and bonded, and both ends in the circumferential direction were cut. As a result, a fixing member having an elastic layer having a silicone rubber thickness of 500 μm and a surface layer PFA having a thickness of 12 μm was obtained.

The fixing member obtained as described above is incorporated into a fixing device as shown in FIG. 2, the surface temperature is set to 150 ° C., and 1 to 10 mg of silicone oil is applied to the surface of the PFA on each A4 sheet, while undetermined. A solid image of the clothes was passed through. The nip pressure was tested at five levels of 4.9 × 10 ⁴ Pa, 9.8 × 10 ⁴ , 19.6 × 10 ⁴ , 29.4 × 10 ⁴ , and 39.2 × 10 ⁴ Pa. At the pressure, the number of rotations (nip residence time) was set so that the gloss evaluation of the image after fixing was good. The nip residence time was in the range up to 400 msec. Usually, 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. In this example, in order to confirm the effect of the present invention more practically, the evaluation target was up to 400 msec.

  Next, at a nip pressure of 5 levels, the unfixed image on which a 5-point character was printed was passed through at a rotation speed set so that the gloss evaluation was ◯, and the crushing of the fixed image was evaluated (gross evaluation was (If the nip residence time in which it becomes o takes more than 400 msec, character collapse evaluation at that pressure level is not performed). As a result, the relationship as shown in Table 1 below was clarified.

実験結果から、圧力が４．９×１０⁴Ｐａと低い場合は、グロスが良好な画像を得るためにはニップ滞留時間が４００ｍｓｅｃ以上掛かるため、グロス及び文字潰れの評価を行うことができなかった。

From the experimental results, when the pressure is as low as 4.9 × 10 ⁴ Pa, the nip residence time is 400 msec or more in order to obtain an image with good gloss, so it was not possible to evaluate gloss and character collapse. .

Further, according to the table, it is understood that even if the surface temperature and the nip residence time are good gloss conditions, if the pressure is too high, characters are crushed and a defective image is obtained. Therefore, when the thickness of the surface layer PFA is 12 μm and the nip pressure range is 93.8 × 10 ⁴ ≦ P ≦ 29.4 × 10 ⁴ , high-quality toner fixing with good gloss and less character crushing The result was that an image could be obtained.

  In the fixing device of Example 1, an evaluation experiment was performed at a surface temperature of 170 ° C. by the same method. As a result, the relationship shown in Table 2 below was clarified.

実施例１の結果と同様、表面温度１７０℃においても、圧力が４．９×１０４ Ｐａのときは、グロスが良好な画像を得るためにはニップ滞留時間が４００ｍｓｅｃ以上掛かるため、グロス及び文字潰れの評価を行うことができなかった。

Similar to the result of Example 1, even at a surface temperature of 170 ° C., when the pressure is 4.9 × 10 4 Pa, the nip residence time takes 400 msec or more to obtain an image with good gloss. Could not be evaluated.

Further, it can be seen from the table that the same tendency as in Example 1 is shown. Therefore, even when the surface temperature is 170 ° C. and the thickness of the surface layer PFA is 12 μm, the gloss is good and the characters are crushed when the nip pressure range is 9.8 × 10 ⁴ ≦ P ≦ 29.4 × 10 ^4. As a result, it was possible to obtain a high-quality toner-fixed image with less image quality.

  A fixing device having a surface PFA thickness of 50 μm was produced in the same manner as in Example 1, and evaluation of gloss and character collapse was similarly performed at a surface temperature of 150 ° C. As a result, the relationship as shown in Table 3 below was clarified.

表によれば、表面温度やニップ滞留時間が良好なグロスになる条件であっても、圧力が高いと文字が潰れてしまい、不良画像となることが分かる。よって、表層ＰＦＡの厚みが５０μｍの場合においては、ニップ圧力の範囲が４．９×１０⁴Ｐａ≦Ｐ≦１９．６×１０⁴のとき、グロスが良好であり文字潰れの少ない高画質なトナー定着画像を得ることができるという結果になった。

According to the table, it can be seen that even under conditions where the surface temperature and the nip residence time are good gloss, the characters are crushed when the pressure is high, resulting in a defective image. Therefore, in the case where the thickness of the surface layer PFA is 50 μm, when the nip pressure range is 4.9 × 10 ⁴ Pa ≦ P ≦ 19.6 × 10 ⁴ , high-quality toner with good gloss and less character collapse As a result, a fixed image can be obtained.

  In the fixing device of Example 3, an evaluation experiment was conducted at a surface temperature of 170 ° C. by the same method. As a result, the relationship shown in Table 4 below was clarified.

表によれば、表面温度やニップ滞留時間がグロスが良好になる条件であっても、圧力が高いと文字が潰れてしまい、不良画像となることが分かる。よって、表面温度１７０℃においても、表層ＰＦＡの厚みが５０μｍの場合においては、ニップ圧力の範囲が４．９×１０⁴Ｐａ≦Ｐ≦１９．６×１０⁴のとき、グロスが適切であり文字潰れの少ない高画質なトナー定着画像を得ることができるという結果になった。

According to the table, it can be seen that even if the surface temperature and the nip residence time are conditions where the gloss is good, if the pressure is high, the characters are crushed and a defective image is obtained. Therefore, even when the surface temperature is 170 ° C. and the thickness of the surface layer PFA is 50 μm, when the nip pressure range is 4.9 × 10 ⁴ Pa ≦ P ≦ 19.6 × 10 ⁴ , the gloss is appropriate and the characters As a result, it was possible to obtain a high-quality toner-fixed image with little crushing.

  When the results of Examples 1 to 4 are summarized in relation to the thickness of the surface layer PFA, the nip pressure is P, and the thickness of the surface layer PFA is such that the gloss and character collapse evaluations are both ◯ in the sensory evaluation. Where d1 is the following inequality relationship.

(−2.5 × 10 ³ ) · d1 + 3.2 × 10 ⁵ ≦ P ≦ (−1.2 × 10 ³ ) d1
+ 1.1 × 10 ⁵
Therefore, in the fixing device embodying the present invention, it is clear that when the relationship between the nip pressure and the surface PFA thickness is the inequality relationship as described above, the desired high image quality can be achieved, and the effectiveness of the present invention is improved. It could be confirmed.

It is a figure which shows the example of the form which implemented this invention. 1 is a configuration diagram of a toner fixing device according to the present invention. FIG.

Explanation of symbols

11 Surface layer 12 Elastic layer 13 Base material 21 Upper roller 22 Lower roller 23 Halogen heater

Claims (6)

In a toner fixing device that forms a nip by pressurizing at least one member and heats and pressurizes toner in the nip to obtain a multicolor fixed image on a recording medium.
The member on the side in contact with the toner has at least an elastic layer made of silicone rubber and a surface layer made of fluororesin, and when the surface layer thickness is d1 [μm], the thickness range is 10 ≦ d1 ≦ 50, and the nip when the pressure was P [Pa], (- 2.5 × 10 3) · d1 + 3.2 × 10 5 ≦ P ≦ (-1.2 × 10 3) is a pressure range of d1 + 1.1 × 10 ^5, In the elastic layer made of silicone rubber, the thermal conductivity at 25 ° C. is 0.4 to 0.9 [W / m · k], the JIS-A hardness is 25 ° to 40 °, and the layer thickness is A toner fixing device having a thickness of d2 ≦ 1000 when d2 [μm].   2. The toner fixing device according to claim 1, wherein the elastic layer is made of addition-type silicone rubber.   3. The toner fixing device according to claim 1, wherein the thickness of the silicone rubber layer is in a range of 100 ≦ d2 ≦ 500 when d2 [μm].   4. The toner fixing device according to claim 1, wherein the thickness of the surface layer is in a range of 20 ≦ d1 ≦ 40, where d1 [μm]. When the nip pressure was P [Pa], (- 1.9 × 10 3) · d1 + 2.1 × 10 5 ≦ P ≦ (-1.2 × 10 3) · d1 + 1.1 in the pressure range of × 10 ⁵ The toner fixing device according to claim 1, wherein the toner fixing device is used.   6. The toner fixing device according to claim 1, wherein a time during which the recording paper is heated and pressed in the nip (nip residence time) is 400 msec or less.

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