JP5061255B2 - Manufacturing method of fixing member - Google Patents

Description

The present invention relates to a method for manufacturing a fixing member, a method for producing a thermally conductive elastomer of the fixing member constituting the fixing rotary member such as toner in detail.

  Conventionally, in an electrophotographic copying machine and a printer for the purpose of high image quality, particularly a color electrophotographic output device, it is possible to use silicone rubber as a fixing member to ensure flexible adhesion to toner and heat resistance. Many. However, these heat-resistant rubber materials have low thermal conductivity, and become a heat resistance layer when transferring heat from the heat source to the recording material. In color images, a soft rubber layer is particularly important for improving image quality. However, since the heat capacity is large and the thermal resistance is high, the rise time is delayed. In addition, even in the case of a high-speed machine, the heat supply is not in time. Therefore, as in Patent Document 1 and Patent Document 2, attempts have been made to improve thermal conductivity using a filler.

  However, according to Patent Documents 1 and 2, since the density of the fixing member cannot be lowered, it is impossible to reduce the heat capacity by reducing the density and to shorten the rise time.

  There are two reasons for this. The first reason is that as the expansion ratio is increased, the thermal conductivity may rapidly decrease. This occurs when the thermal conductivity of the original material does not change (see, for example, the Eucken equation in the thermophysical handbook Yokendo C.2 p.179). The second reason is that when the expansion ratio is increased, the wall surface of the fixing member becomes relatively thin, so that the strength decreases. Note that the expansion ratio is obtained by using the volume Vs without bubbles as a denominator and the sum of the bubbles volume Vf and Vs as a numerator.

  Due to these two problems, it has been difficult to develop a fixing member having a low heat capacity (low density) and having both high thermal conductivity and heat resistance in a fixing member that is repeatedly deformed in a high temperature environment.

The present invention is for solving these problems, and can fix a fixing device of an image forming apparatus at high speed, and has a low heat capacity (low density), a high thermal conductivity, and a low rubber hardness . It aims at providing the manufacturing method of a member .

In order to solve the above problems, a fixing rotary member having a built-in heat source, and the constant wear rotator, the nip between the pressing portion for pressing through the recording medium to the fixing rotary member In a method for manufacturing a fixing member that constitutes a fixing rotating body that conveys a recording medium carrying unfixed toner and fixes the unfixed toner on the recording medium , a foaming agent or foam is added to the unvulcanized addition type silicone rubber. It contains particles, further contains pitch-based carbon fibers, performs primary vulcanization and foaming, then performs secondary vulcanization, and includes pores in silicone rubber containing pitch-based carbon fibers. The pitch-based carbon fiber having a shape longer than the hole diameter of the hole portion and the silicone rubber are in a non-bonded state, and the open-celled portion formed by connecting the hole portions has the pitch-based carbon fiber inside. Manufacturing fixing material. Therefore, the path of the pitch-based carbon fiber is thermally conductive, can be easily deformed by sliding the pitch-based carbon fibers are not fixed strongly, by compression set without breaking due to stress concentration to the silicone rubber can be reduced, the pitch to improve the flow of gas between the rigidity and the holes of the system carbon fiber, low heat capacity (low density) and high thermal conductivity, and can be produced fixing member low rubber hardness.

Also, a fixing rotator having a built-in heat source, in which recording is performed with unfixed toner carried in a nip portion between the fixing rotator and a pressure unit that is pressed against the fixing rotator via a recording medium. In a method for manufacturing a fixing member that constitutes a fixing rotating body that transports a medium and fixes unfixed toner to a recording medium, pitch-based carbon fibers and already expanded particles are contained in an unvulcanized addition type silicone rubber. Pitch-based carbon fibers that are subjected to primary vulcanization, followed by secondary vulcanization, and are configured to include pores in silicone rubber containing pitch-based carbon fibers and have a shape longer than the pore diameter of the pores. The silicone foam and the silicone rubber are in a non-bonded state, and the open cell portion formed by connecting the pores produces a fixing material in which pitch-based carbon fibers are present. Therefore, the pitch-based carbon fiber becomes a heat conduction path, and since the pitch-based carbon fiber is not strongly fixed, it can be easily deformed by sliding, and the compression set can be reduced without being broken by stress concentration on the silicone rubber. The fixing member having low heat capacity (low density), high thermal conductivity, and low rubber hardness can be manufactured by improving the rigidity of the carbon fiber and the gas flow between the holes.

Further, the expansion ratio of the fixing member is 1.5 or more and 3.0 or less. If the expansion ratio is less than 1.5 times, the heat capacity is large, so that the thickness for enlarging the nip cannot be secured. If the expansion ratio exceeds 3.0 times, the wall surface becomes extremely thin, the strength decreases, and the compression set Becomes larger. Therefore, the low heat capacity and the strength are satisfied within the range where the expansion ratio of the fixing member is 1.5 or more and 3.0 or less, and a sufficient fixing operation is possible.

In the method for producing a fixing member of the present invention, the unvulcanized addition type silicone rubber contains a foaming agent or foamed particles, further contains pitch-based carbon fibers, and is subjected to primary vulcanization and foaming. After vulcanization, the pitch-based carbon fiber and the silicone rubber, which are configured to include pores in the silicone rubber containing pitch-based carbon fibers and have a shape longer than the pore diameter of the pores, are in a non-adhesive state. The open cell portion formed by connecting the pores produces a fixing material in which pitch-based carbon fibers are present. Therefore, the path of the pitch-based carbon fiber is thermally conductive, can be easily deformed by sliding the pitch-based carbon fibers are not fixed strongly, by compression set without breaking due to stress concentration to the silicone rubber can be reduced, the pitch to improve the flow of gas between the rigidity and the holes of the system carbon fiber, low heat capacity (low density) and high thermal conductivity, and can be produced fixing member low rubber hardness.

FIG. 3 is a partial cross-sectional view illustrating a configuration of a fixing member according to an embodiment of the present invention. It is an enlarged view which shows the relationship between the open cell structure and carbon fiber in the silicone rubber layer of FIG. It is an enlarged view which shows the silicone rubber layer of a single bubble structure. It is a schematic sectional drawing which shows the structure of the fixing apparatus of another invention using the fixing member of this invention. It is a schematic sectional drawing which shows the structure of the image forming apparatus of another invention carrying the fixing device of this invention. FIG. 3 is a cross-sectional view illustrating a structure of a fixing roller. It is sectional drawing which shows the cut surface using the carbon fiber which is not heat-processed. It is sectional drawing which shows the cut surface of what used the heat-treated carbon fiber.

  FIG. 1 is a partial cross-sectional view showing a configuration of a fixing member according to an embodiment of the present invention. As shown in the figure, the fixing member 10 of the present embodiment is configured by laminating a metal roller 11, a silicone rubber layer 12, and a PFA layer 13. Then, as shown in FIG. 2, the silicone rubber layer 12 contains bubbles 12-2 that are pores and carbon fibers 12-3 that are made open through the open bubbles 12-1. Has been. According to the fixing member 10 of this embodiment having such a laminated structure, as shown in FIG. 1, heat from a heater (not shown) as a heat source is transmitted to the metal roller 11, and heat from the metal roller 11. Is transmitted to the PFA layer 13 through the silicone rubber layer 12. Therefore, the PFA layer 13 can be fixed by applying heat to the toner.

  Here, FIG. 2 is an enlarged view showing the relationship between the open cell structure and the carbon fiber in the silicone rubber layer. In addition, since the continuous bubble part 12-1 is connected with the adjacent bubble 12-2, it means what the inside gas can flow in the case of deformation. On the other hand, FIG. 3 is an enlarged view showing a silicone rubber layer having a single foam structure, and corresponds to Comparative Example 7 described later. As shown in the figure, the silicone rubber layer 20 having a single-bubble structure is configured to include bubbles 21 and carbon fibers 22 that do not have a continuous bubble portion shown in FIG. Therefore, gas cannot move between the holes, and the rigidity of the carbon fiber affects the properties of the silicone rubber. By the way, as a carbon fiber, Pitch-type Nippon Graphite Fiber Co., Ltd. product name: Carbon fiber milled product number: XN-100-15M (150 microns) is optimal. The thermal conductivity is 500 W / mK. On the other hand, the thermal conductivity of the PAN system is 50 W / mK at the maximum. An unvulcanized addition-type silicone rubber containing carbon fiber and already expanded particles and further containing a curing agent, a PFA tube having an adhesive layer formed on the inner surface in advance, and a convex reinforcement on the inner surface of 0.5 mm (hereinafter referred to as ribs) A metal core provided with a metal core is set, and an injection solution is injected between the PFA tube and the metal core. Next, it fixes by secondary heating. At this time, the foaming agent is broken, and the periphery of the carbon fiber is released from the silicone rubber. At this time, glycerin, ethylene glycol, diethylene glycol, triethylene glycol, or the like is used in order to effectively release the carbon fiber from the silicone rubber and create a space in the release portion. These can create a space by the volatilization effect. Similarly produced silicone uncrosslinked liquid can be applied to a roller and vulcanized to produce a fluororesin coat layer or coated with a fluororesin tube.

  FIG. 4 is a schematic cross-sectional view showing a configuration of a fixing device of another invention using the fixing member of the present invention. In the fixing device 1 of another invention using the fixing member of the present invention shown in the same figure, a heater 15 is provided inside a roller-shaped metal core 14, and the fixing member 10 of the present invention is provided on the outer peripheral surface of the metal core 14. Is formed. A pressure roller 16 is provided so as to face the fixing roller formed as described above, and the pressure roller 16 is pressed toward the fixing roller by a pressure mechanism 17 such as a spring. Therefore, the recording medium on which the unfixed toner image is formed is sandwiched and pressed between the fixing roller and the pressure roller 16 to fix the unfixed toner on the recording medium.

  FIG. 5 is a schematic cross-sectional view showing the configuration of an image forming apparatus according to another invention equipped with the fixing device according to the present invention. According to the image forming apparatus 100 of another invention in which the fixing device of the present invention shown in the figure is mounted, a charging device 102, a writing device 103, a developing device 104, a transfer device 105, and a cleaning device are disposed around the photosensitive member 101. 106 is arranged. The photosensitive member 101 is charged to, for example, a positive electrode by the charger 102, and optical information based on the image information is written on the photosensitive member 101 charged by the writing device 103 to form a visible latent image. Next, the visible latent image becomes a toner image by the toner stirred and charged by the developing device 104, and the toner image is transferred to a recording medium by the transfer device 105. As shown in FIG. 4, the unfixed toner on the transferred recording medium is transported by the recording medium carrying the unfixed toner to the nip portion between the fixing roller and the pressure roller in the fixing device 1. Unfixed toner is fixed on the recording medium.

  Here, as the fluororesin used in the present invention, a resin having a good melt film forming property by firing and a relatively low melting point (preferably 250 to 300 ° C.) is preferably selected. Specific examples include fine powders of low molecular weight polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), and tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA). It is done. As the low molecular weight polytetrafluoroethylene (PTFE) powder, Lubron L-5, L-2 (Daikin Industries), MP1100, 1200, 1300 and TLP-10F-1 (Mitsui DuPont Fluorochemical) are known. As the tetrafluoroethylene-hexafluoropropylene copolymer (FEP) powder, 532-8000 (DuPont) is known. As the tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), MP-10, MP102, (Mitsui DuPont Fluorochemical) are known. In particular, MP103, MP300 (Mitsui Dupont Fluorochemical), AC-5600, AC5539 (Daikin Industries) and the like are suitable for the present invention as those having a low MFR (melt flow rate) and low fluidity.

  Examples of the foaming agent include azobisisobutyronitrile (AIBN), and examples of the foamed particles include Matsumoto Yuka Pharmaceutical's F-30, F-30VS, F-46, F-50D, and F-55D. . Further, as the already expanded particles, Matsumoto Yuka Pharmaceutical's 100CA, 80CA, F-80ED, F-30E, F-50E, F-80SDE and the like are available. Carbon fibers include PAN (polyacrylonitrile) carbon fibers made from synthetic acrylic long fibers and pitch carbon fibers made from coal tar and petroleum pitch. The PAN-based carbon fiber is obtained by carbonizing a PAN precursor (polyacrylonitrile fiber) and has properties of high strength and high elastic modulus. Pitch-based carbon fibers are obtained by carbonizing pitch precursors (pitch fibers obtained from coal tar or heavy petroleum oil as a raw material). Under various manufacturing conditions, low-modulus to ultra-high modulus / high strength A wide range of properties can be obtained. Ultra-high modulus products have excellent thermal conductivity and conductivity characteristics, as well as high rigidity applications.

<Example A and Comparative Example A>
An addition type liquid silicone containing a curing agent is prepared by dispersing F-80ED and XN-100-15M (150 micron) powders. As XN-100-15M, one previously mixed with 1/8 amount of glycerin is used. Mixing was performed using a Mazerustar from Kurashiki Spinning Co., Ltd. The carbon fibers used are those mixed with glycerin other than those subjected to heat treatment. This is used to reduce the adhesion between carbon fiber and silicone rubber. As shown in FIG. 6 (a), this unvulcanized addition type silicone rubber is provided with a PFA tube having an adhesive layer formed on the inner surface in advance, and a rib 31 serving as a convex reinforcement on the inner surface of 0.5 mm inside. A cored bar is set, and in the meantime, it is injected between the PFA tube and the cored bar as an injection solution. In addition, as a cross-sectional shape of the rib 31, there exists a thing as shown to (b)-(d) of FIG. At this time, primary vulcanization is performed by heating at 120 ° C., and then secondary vulcanization is performed at 200 ° C. for 4 hours. At this time, the foaming agent is broken and the periphery of the carbon fiber is released from the silicone rubber. In a series of steps, an outer diameter of φ40 (mm) was produced. The silicone rubber layer was 3 mm. This was set in a fixing unit of a copying machine MF4570 manufactured by Ricoh Co., Ltd., and the temperature rise time (seconds) up to 160 ° C. with a 1000 (W) halogen heater was measured. Instead of the standard silicone rubber, the pressure roller was made of the same silicone rubber that did not use carbon fiber. The temperature was measured by providing a thermocouple in the upper part of the fixing roller. The foaming ratio was obtained from the volume, weight, and blending amount of the same blending composition as that for the roller production by injection and vulcanization in a mold having a thickness of 2 mm and a width and width of 100 mm. With this sample, the rubber hardness was measured. Moreover, it cut | disconnected to 50 mm square, piled up three sheets, and measured the compression set of 25% compression 180 degreeC 22 hours. The core metal thickness is 0.4 mm with ribs. The rubber hardness was measured using Polymer Instruments Co., Ltd. Micro Rubber Hardness Meter MD-1: Type A for general rubber (JIS A approximate value). In the table, it is expressed as rubber hardness (MD-1). Comparative Example A-4 is an example of carbon fibers treated in air at 600 ° C. for 2 hours. Comparative Examples A-5 and A-6 are examples using glass fibers. Comparative example A-5 is an Asahi fiber glass and is an example without 06MW2-20 length 100-300 micrometers primer. Comparative Example 6 is an example of the same glass fiber treated with 20MH2-20, 100 to 300 μm in length, and a silane-based primer. FIG. 7 is a cross-sectional view showing a cut surface obtained by cutting a carbon fiber that is not heat-treated with a razor. The carbon fiber that is shining in a straight line is visible because it is peeled off from the silicone rubber. FIG. 8 is a cross-sectional view showing a cut surface obtained by cutting a carbon fiber heat-treated in air at 600 ° C. for 2 hours with a razor. Silicone rubber is adhered around the carbon fiber. Moreover, carbon fiber is not observed so much because the silicone rubber portion is cut during cutting. Thus, it can be easily confirmed that there is a remarkable non-bonded portion around the carbon fiber.

  Carbon fiber is said to be oxidized in a very small amount from 300 ° C. in the air, and it is considered that the adhesion is improved because of the presence of an oxide layer on the surface. Although not shown, both glass fibers are almost completely bonded to the silicone rubber. For comparison, XN-100-05M (50 microns) used in Comparative Example A-7 was treated at 600 ° C. for 2 hours in air.

  As can be seen from Tables 1 and 2, in Examples A-1, A-2, and A-3, the rubber hardness can be made extremely small, and the compression set is also small. Furthermore, it stands up within 30 seconds. In Comparative Examples A-1 and A-3, the rise is slow, and in Comparative Example A-2, the compression set is large, and deformation of the heating roller is observed by heating and pressing at 160 ° C. for 100 hours. In Comparative Example A-4, Comparative Example A-5, Comparative Example A-6, and Comparative Example A-7, no roller was produced, but the rubber hardness was large and the compression set was also large.

<Example B and Comparative Example B>
Next, F-30 and XN-100-15M (150 micron) powders are dispersed in addition-type liquid silicone containing a curing agent. This unvulcanized addition-type silicone rubber is set with a PFA tube with an adhesive layer formed on the inner surface in advance and a cored bar with ribs that are convex reinforcement on the inner surface of 0.5 mm inside. Inject between PFA tube and cored bar. At this time, primary vulcanization is performed by heating at 130 ° C. to foam F-30. Next, secondary vulcanization is performed at 200 ° C. for 4 hours. Evaluation and the like were performed in the same manner as in Example A.

  Examples B-1, B-2, and B-3 have small rubber hardness and small compression set. Also, it stands up within 30 seconds. In Comparative Example B-1 and Comparative Example B-3, the rise is slow, and in Comparative Example B-2, the compression set is large, and the heating roller is deformed by heating and pressing at 160 ° C. for 100 hours.

<Comparative Example C>
An addition-type liquid silicone containing a curing agent is prepared by dispersing F-30 and XN-100-15M (150 micron) powders. This unvulcanized addition-type silicone rubber is set with a PFA tube with an adhesive layer formed on the inner surface in advance and a cored bar with ribs that are convex reinforcement on the inner surface of 0.5 mm inside. Inject between PFA tube and cored bar. At this time, primary vulcanization is performed by heating at 130 ° C. to foam F-30. Secondary vulcanization was not performed at 200 ° C. for 4 hours, and an outer diameter of 40 mm was produced. This was set in a fixing unit of a copying machine MF4570 manufactured by Ricoh Co., Ltd., and the temperature rise time (seconds) up to 160 ° C. with a 1000 (W) halogen heater was measured. The blending was performed in parts by weight, but F-30 was converted by volume as foaming ratio as bubbles after foaming. The core metal thickness is 0.4 mm with ribs.

  When Examples A-5 and A-6 are compared with Comparative Examples C-1 and C-2, the compression set is much smaller when foamed, fixed, and secondarily vulcanized during the first vulcanization.

<Example C>
In Example C, the fixing member of Example A-5 was produced by changing the thickness of the cored bar.

  It is 20 seconds or less at 0.5 mm or less, and breaks at 0.2 mm.

<Example D>
The roller of Example A-5 was mounted on a fixing unit of MF4570 manufactured by Ricoh Co., Ltd., and 10,000 sheets were passed through a black solid image of imgio MP C4500 manufactured by Ricoh Co., Ltd., as shown in Table 6 below. The toner adhesion amount and the paper wrapping were observed. As a result, it was confirmed that if the surface roughness (ten-point average roughness: JIS B0601-1994) Rz was 5 μm or less, there was an effect. The 7μm one is 7325, and the experiment has been canceled due to frequent jams.

<Example E>
An unfixed image created with IPSIO Color 8100 manufactured by Ricoh Co., Ltd. was tested. Since the toner of this IPSIO Color 8100 has insufficient releasability, an oil application member impregnated with silicone oil is added to apply silicone oil to the fixing roller. Through this IPSIO Color 8100, 10,000 black solid images were passed, and the toner adhesion state on the roller surface was observed. In particular, no large adhesion was observed, and there was no difference from the normal one. With the application member removed, 60,000 sheets showed remarkable adhesion of toner to the roller.

<Example F>
In Example F, the roller of Example A-1 with a surface roughness Rz of 2 μm or less was produced. A fixing tester using a fixing unit of MF4570 was prepared, and an unfixed image of imagio MP C4500 was passed through this roller while changing the pressing force. As shown in Table 7 below, the fixing property was very poor at 2.9 (N / cm ² ) or less, and toner adhesion to the fixing roller was observed at 19.6 (N / cm ² ) or more. . Paper wrapping is caused by further deterioration of the toner adhesion state and wrapping. Paper wrapping is not observed at 39.2 (N / cm ² ) or less. The fixability was simply determined by rubbing the cloth on the surface against the solid image after fixing, and having the toner markedly attached with the toner as defective fixing.

  In addition, this invention is not limited to the said embodiment, It cannot be overemphasized that various deformation | transformation and substitution are possible if it is description in a claim.

1; fixing device, 10; fixing member, 11; metal roller,
12; Silicone rubber layer, 12-1; Open cell part, 12-2; Air bubble,
12-3; carbon fiber, 13; PFA layer, 14; cored bar,
15; heater, 16; pressure roller, 17; pressure mechanism, 31; rib,
100: an image forming apparatus.

JP 2006-133576 A JP 2005-292218 A

Claims (3)

A fixing rotator having a built-in heat source, wherein the recording medium carries unfixed toner in a nip portion between the fixing rotator and a pressure unit that presses the fixing rotator through the recording medium. In a method for manufacturing a fixing member that constitutes a fixing rotating body that conveys the toner and fixes unfixed toner to a recording medium,
An unvulcanized addition type silicone rubber contains a foaming agent or foamed particles, further contains pitch-based carbon fibers, and performs primary vulcanization and foaming, followed by secondary vulcanization, and the pitch-based carbon. The pitch-based carbon fiber having a shape longer than the hole diameter of the hole portion and the silicone rubber are configured to include a hole portion in the silicone rubber containing fibers, and the hole portion is not bonded. The connected foamed portion is a fixing member manufacturing method in which a fixing material in which the pitch-based carbon fiber is present is manufactured. A fixing rotator having a built-in heat source, wherein the recording medium carries unfixed toner in a nip portion between the fixing rotator and a pressure unit that presses the fixing rotator through the recording medium. In a method for manufacturing a fixing member that constitutes a fixing rotating body that conveys the toner and fixes unfixed toner to a recording medium,
An unvulcanized addition-type silicone rubber is mixed with pitch-based carbon fibers and pre-expanded particles for primary vulcanization, followed by secondary vulcanization, and the silicone rubber containing the pitch-based carbon fibers is empty. The pitch-based carbon fiber that is configured to include a hole portion and has a shape longer than the hole diameter of the hole portion and the silicone rubber are in a non-bonded state, and the open cell portion formed by connecting the hole portions is A fixing member manufacturing method comprising manufacturing a fixing material in which the pitch-based carbon fiber is present. The method for manufacturing a fixing member according to claim 1, wherein the expansion ratio of the fixing member is 1.5 or more and 3.0 or less.

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