JP2005284032A - Oil application roller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an oil application roller with which low heat capacity and low heat conductivity are achieved by a simple method. <P>SOLUTION: In the oil application roller having a core shaft and a porous silicone rubber foam body along the circumference of the core shaft, the silicone rubber foam body includes a bubble section filled with a gas and a three-dimensional net structure section containing a releasing agent. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a low heat capacity and low thermal conductivity oil application roller for applying a release agent in a toner fixing portion of an electrophotographic copying machine or an electrophotographic printing machine.

  In the fixing process of the electrophotographic image forming apparatus, pressure and heat energy are applied to the toner image via a fixing roller or a fixing belt, the toner is made into a semi-molten state, penetrates into the recording paper, and is fixed. ing. Since the toner is in a semi-molten state at the time of fixing, an offset phenomenon in which a part of the semi-molten toner is transferred and adhered to the surface of the fixing roller or the fixing belt, and this is re-transferred to the next recording paper to be fed. May occur. In order to prevent this offset phenomenon, an oil application roller is used, and a release agent such as silicone oil is applied to about 0.1 to 5.0 mg / A4 on the surface of the fixing roller and the fixing belt in contact with the toner.

  In recent years, the use of a polymerized toner containing a wax component having a releasing function has made it possible to prevent offset without applying a releasing agent. However, there is a problem that the surface of the fixing member is easily worn and inferior in durability while being oil-less. For this reason, even in the case of oilless using polymerized toner, a very small amount of oil of about 0.01 to 0.05 mg / A4 is applied to the surface of the fixing member to prevent the surface of the fixing member from being worn.

  On the other hand, the oil application roller is used in contact with a fixing roller or a fixing belt as a heat source directly or via a donor roller and rotated, so that heat energy is transferred to the heat source side at the start of operation or during continuous operation. Robs it, and then dissipates its thermal energy. For this reason, power consumption increases and energy efficiency is deteriorated. In recent years, energy saving measures have been further demanded for electrophotographic copiers and electrophotographic printing machines, and the development of oil application rollers with low heat capacity and low thermal conductivity has been eagerly desired.

  Japanese Patent Application Laid-Open No. 2001-109308 discloses an oil application roller whose application roller body is a solid body made of an elastic body formed by molding a mixture of a silicone rubber component and an offset prevention liquid. In this oil application roller, “solid” means that there is no hole or minute hole, and does not include a porous body. And since this oil application roller has few components and the manufacturing process is simple, it can reduce cost.

Japanese Patent Application Laid-Open No. 2000-259025 discloses a release agent supply roll for supplying a release agent to the surface of a fixing roll, and a mixture of a heat-resistant rubber and a release agent in a gap in a roll-shaped porous elastic body. A mold release agent supply roll is disclosed. In this release agent supply roll, the mixture of the heat-resistant rubber and the release agent is a gel, and the release agent is gradually leached from the surface of the mixture in response to external stimuli such as heat and pressure. The mold can be applied stably and uniformly.
JP 2001-109308 A (Claim 1) JP 2000-259025 A (Claim 1, paragraph 0021)

  However, since the oil application roller described in JP-A-2001-109308 is solid, it has a large heat capacity and a high thermal conductivity. For this reason, there is a problem that a large amount of heat energy is taken from the heat source side during actual operation, and the amount of heat radiation increases, resulting in the consumption of a large amount of power, resulting in a recent reduction in heat capacity and heat conductivity. Does not meet the requirements of Moreover, although the release agent supply roll described in JP-A-2000-259025 has a void portion, since the void portion contains a mixture of the release agent and rubber, the heat capacity is reduced and the thermal conductivity is reduced. So I'm not satisfied with it.

  Accordingly, an object of the present invention is to solve the above-described problems of the conventional oil application roller, and to provide an oil application roller having a low heat capacity and a low thermal conductivity.

  In such a situation, the present inventors have intensively studied, and as a result, have a shaft core and a porous silicone rubber foam attached to the outer periphery of the shaft core, and the silicone rubber foam is air or the like. If the oil application roller is composed of a bubble portion filled with a gas and a three-dimensional network structure portion containing a release agent, it has been found that the heat capacity can be reduced and the thermal conductivity can be reduced, and the present invention has been completed. .

  That is, the present invention (1) is an oil application roller comprising a shaft core and a porous silicone rubber foam attached to the outer periphery of the shaft core, wherein the silicone rubber foam is a bubble portion filled with gas. And an oil application roller comprising a three-dimensional network structure containing a release agent.

  Also, the present invention (2) manufactures an oil application roller obtained by pouring a mixture containing a liquid silicone rubber, a foaming agent and a release agent into a mold having a shaft core at the center, curing, and demolding. A method is provided.

  The silicone rubber foam of the oil application roller of the present invention constitutes a roll body, holds the release agent, and supplies the release agent to the fixing member. The silicone rubber foam has a low heat capacity and a low thermal conductivity because it consists of a gas-filled bubble part and a three-dimensional network structure part containing a release agent. That is, the silicone rubber foam has two kinds of pores, a bubble portion generated during production and a void in the three-dimensional network structure, and the bubble portion contributes to lower heat capacity and lower thermal conductivity. The voids in the structure perform a release agent holding function. For this reason, it can contribute to energy saving in an electronic copying machine or an electrophotographic printing machine. In addition, since the method for manufacturing the oil application roller of the present invention is a simple process, the cost can be reduced.

  Next, the oil application roller according to the embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a side view showing an installation state of an oil application roller according to the present embodiment in a fixing device, FIG. 2 is a sectional view in the radial direction of the oil application roller according to the present embodiment, and FIG. It is sectional drawing of the axial direction of a certain oil application roller. In the figure, an oil application roller 1 includes a shaft core 10 and a porous silicone rubber foam 2 attached to the outer periphery of the shaft core and having a function of holding a release agent and supplying the release agent to a fixing roller. . The oil application roller 1 is incorporated in the fixing device 4, and the fixing device 4 passes the recording paper 7 between the heat fixing roll 5 and the pressure roll 6, and fixes the toner 8 transferred to the surface 7 a of the recording paper 7. However, the oil application roller 1 is brought into contact with the heat fixing roll 5 so as to form the nip portion 9, and silicone oil as a release agent is applied to the heat fixing roll 5.

  The silicone rubber foam 2 is a porous body composed of a gas-filled bubble part and a three-dimensional network structure part containing a release agent, and forms a mixture containing liquid silicone rubber, a foaming agent and a release agent. It is obtained by curing. Bubbles are also referred to herein as pores. Since the release agent filled in the voids in the three-dimensional network structure has high affinity with liquid silicone, it is stably held in the voids and does not leach into the bubble. On the other hand, in the state of being used in contact with the fixing member, when an external stimulus such as heat or pressure is applied, the release agent is leached from the roll surface to the fixing roll, and when the concentration of the release agent on the roll surface portion is reduced, Due to the diffusion phenomenon, the release agent is supplied (moved) from the inside of the silicone rubber foam 2. Even in this case, the release agent does not leach into the bubble part. For this reason, the oil application roller can stably achieve low heat capacity and low thermal conductivity throughout the period of use. The gas is usually a foaming gas, specifically air, hydrogen or carbon dioxide.

  The liquid silicone rubber is not particularly limited, but is generally composed of a polymer such as polydimethylsiloxane, an inorganic filler such as silica, a crosslinking agent, and a catalyst. Type liquid silicone rubber. The addition reaction type liquid silicone rubber is a crosslinked rubber obtained by adding polymethylsiloxane having a silicon atom-bonded hydrogen atom (liquid B) to polydimethylsiloxane having a vinyl terminal (liquid A). The addition reaction type liquid silicone rubber may contain an inorganic filler, or the inorganic filler may be contained in a trace amount or not, but the one containing the inorganic filler has a three-dimensional network structure. This is preferable in that the fine holes are appropriately blocked to limit the coating amount, and a very small amount of oil of about 0.01 to 0.05 mg / A4 can be applied to the surface of the fixing member. “KE1300” (manufactured by Shin-Etsu Chemical Co., Ltd.) can be used as an addition reaction type liquid silicone rubber compounded with an inorganic filler. Although it does not restrict | limit especially as the said inorganic filler, For example, the average particle diameter is 0.005-0.2 micrometer, Especially 0.01-0.03 micrometer silica filler is mentioned. Examples of addition reaction type liquid silicone rubber with a small amount of inorganic filler or non-formulation include oil bleed type “KE1311T” (manufactured by Shin-Etsu Chemical Co., Ltd.), “KE106” (with no filler) Shin-Etsu Chemical Co., Ltd.).

  The foaming agent is not particularly limited, and examples thereof include silicone foam, water, and volatile substances. Of these, silicone foam is preferable in that it can efficiently generate a foaming gas. Although it does not restrict | limit especially as a silicone foam, Generally the composition itself of a silicone rubber contains the foaming mechanism, and says what foams using gas, such as hydrogen generated in the case of hardening reaction. In the foaming mechanism, a liquid silicone polymer having Si—OH groups and a cross-linking agent having H—Si groups are cross-linked by a catalytic reaction, and at this time, hydrogen gas is generated and foamed while being cured by this gas. For example, a rubber-like porous body can be obtained by foaming and curing a mixture of a commercially available silicone foam composed of a low-viscosity two-component component and a liquid silicone rubber at room temperature or by heating. Examples of the silicone foam include those in the form of mixed use of two liquid components of “KE524A” and “KE524B” (manufactured by Shin-Etsu Chemical Co., Ltd.).

The release agent is not particularly limited as long as it is a liquid that can be added to the liquid silicone rubber and can prevent toner adhesion, and examples thereof include silicone oil, fluorine-modified silicone oil, and mixtures thereof. Examples of the silicone oil include straight silicone oils such as dimethyl silicone oil and methylphenyl silicone oil, and modified silicone oils in which some of the dimethyl groups are replaced with other organic groups. Of these, straight silicone oil is particularly preferable in that it has miscibility with an addition reaction type liquid silicone rubber and excellent releasability. The viscosity of the silicone oil at 25 ° C. is 0.1 to 10 cm ² / s (10 to 1000 cSt), preferably 0.1 to ³ cm ² / s (10 to 300 cSt).

  As a blending ratio of the liquid silicone rubber (SG1), the silicone foam (SG2), and the release agent (R), the total amount of (SG1) and (SG2) and the weight blending ratio of (R) ((SG1 + SG2) in the mixture. ) / R) is preferably 1/2 to 3/1. If the weight ratio ((SG1 + SG2) / R) exceeds 3/1, the amount of release agent held will be reduced, so the replacement time will be shortened and the flexibility of the silicone rubber foam will be reduced, resulting in a nip. Therefore, oil applicability tends to be unstable. On the other hand, if it is less than ½, the strength of the silicone rubber foam is reduced, and defects are likely to occur during removal from the mold or in actual use. Moreover, as for the mixture ratio (weight part ratio) of (SG1) and (SG2) in this mixture, (SG1) / (SG2) has preferable 20 / 80-80 / 20. When (SG1) / (SG2) is less than 20/80, the porosity becomes too high, and the strength of the silicone rubber foam is lowered, so that it is easy to cause defects during demolding or actual use. . On the other hand, if (SG1) / (SG2) exceeds 80/20, the porosity is too small to achieve low heat capacity and low thermal conductivity. In the silicone rubber foam, other optional components other than the liquid silicone rubber, the foaming agent and the release agent in the mixture may be appropriately blended as long as the effects of the silicone rubber foam are not impaired.

  The silicone rubber foam is obtained by pouring a mixture containing a foaming agent such as liquid silicone rubber and silicone foam and a mold release agent into a mold having a shaft core at the center, curing and demolding. The curing conditions are not particularly limited, and are appropriately determined in the range of room temperature to 150 ° C, preferably 40 to 100 ° C, and 15 minutes to 2 hours. The method for obtaining the mixture is not particularly limited, and examples thereof include a method in which liquid silicone rubber, a foaming agent, and a release agent are weighed and stirred for several minutes at room temperature with a hybrid mixer to obtain a mixture.

  The silicone rubber foam has a porosity of 3 to 40%, preferably 5 to 40%, formed by a three-dimensional network structure formed by crosslinking of reaction components in a rubber component and a silicone foam (foaming agent). It is a porous body having a bubble part filled with gas. If the porosity is less than 3%, it is not possible to achieve low heat capacity and low thermal conductivity. On the other hand, if the porosity exceeds 40%, the strength of the silicone rubber foam is reduced, and defects are likely to occur during removal from the mold or in actual use. The size of the bubbles is not particularly limited, but is about 100 μm, which is larger than the voids of the three-dimensional network structure. Further, since the release agent in the three-dimensional network structure portion has high affinity with the liquid silicone, it is stably held in the three-dimensional network structure portion and does not leach into the bubble portion. Moreover, since the rubber hardness (Asker C) of the silicone rubber foam is 2.0 to 30, preferably 2.0 to 18.0, since it has both appropriate hardness and flexibility, it can be removed from the mold. It is preferable in that the mold can be smoothly formed and the nip portion can be formed at the time of use.

  The oil application roller of the present invention may be further provided with a release agent application control layer on the outer peripheral surface of the silicone rubber foam 2. The release agent application control layer 3 is not particularly limited, and examples thereof include a PTFE film in which fine pores are formed, or a heat-cured body of a mixture containing silicone rubber and silicone oil. This heat-cured body is a mixture of silicone rubber (SG) and silicone oil (SO) having a weight ratio (SG / SO) of 1/2 to 9/1, preferably 1/1 to 4/1. It is obtained by uniformly applying to the outer periphery of 2 and heating.

  In the oil application roller 1 of the present embodiment, the silicone rubber foam 2 has bubbles with a porosity of 3 to 40% filled with gas, so that a low heat capacity and a low thermal conductivity can be achieved. The release agent is stably taken into the rubber elastic body that is a cross-linked three-dimensional network structure. The release agent is used from the surface of the silicone rubber foam 2 due to heat, external stress, or a diffusion phenomenon that attempts to make the viscosity in the mold uniform, in a state where it is used in contact with the fixing member. A moderate amount oozes out. In particular, when an addition reaction type liquid silicone rubber compounded with a silica filler having a particle size of 0.01 to 0.2 μm is used for the silicone rubber foam 2, the silica filler closes the micropores of the crosslinked rubber and moves the release agent. In order to suppress more reliably, a very small amount can be applied. In addition, since the release agent does not leach into the bubble portion even when the release agent moves, the oil application roller can stably achieve a low heat capacity and a low thermal conductivity throughout the period of use.

  EXAMPLES Next, although an Example is given and this invention is demonstrated more concretely, this is only an illustration and does not restrict | limit this invention.

  80 parts by weight of addition reaction type liquid silicone rubber “KE1300” containing silica filler having a particle size of 0.02 μm, 20 parts by weight of silicone foam, 120 parts by weight of dimethyl silicone oil “KF96-100cs” (manufactured by Shin-Etsu Chemical Co., Ltd.) and a predetermined amount The reaction catalyst was mixed for 3 minutes at room temperature with a hybrid chemiser to obtain a mixture A. The silicone foam used was a mixture of two liquid components “KE524A” and “KE524B” (both manufactured by Shin-Etsu Chemical Co., Ltd.) (abbreviated as “KE524AB” in Table 1).

On the other hand, a solid shaft core having an outer diameter of 6 mm was set at the center of a hollow split mold having a diameter of 20 mm and a length of 306 mm. Next, the mixed solution A was poured into the mold of the split mold. Then, after putting in a dryer at 50 ° C. for 1 hour to crosslink the rubber, the mold is removed and the end of the roller is cut to obtain a silicone rubber foam having an outer diameter of 20 mm, an inner diameter of 6 mm, and a length of 306 mm. A coating roller A was obtained. The “bulk density”, “porosity”, “specific heat”, “heat capacity”, “thermal conductivity (λ)”, “rubber hardness (Asker C)”, “durability” of the silicone rubber foam of this oil application roller A The roller strength "was measured. The results are shown in Table 1. The volume of the silicone rubber foam was 87.4364 cm ^{3 as} shown in Table 1.

(Porosity)
The true specific gravity before foaming of the addition reaction type liquid silicone rubber, silicone foam, dimethyl silicone oil and reaction catalyst is calculated using an air comparison type hydrometer “1000 type” (manufactured by Tokyo Science). Next, the apparent density of the silicone rubber foam is calculated based on the true specific gravity value, and the porosity is calculated from the density difference (see the following formula). Porosity (%) = (true specific gravity−apparent density of foam) × 100 / true specific gravity

(Roller strength during durability)
An endurance test was performed under the conditions of 500 gf on one side of the roller load, a fixing unit temperature of 180 ° C., a roller peripheral speed of 185 mm / sec, and a total of 10,000 sheets, and the subsequent roller portion was visually observed. In particular, those with no deformation, off-axis, etc. were indicated with “◯”, and those with rubber breakage, off-axis, and deformation were indicated with “x”.

  Example 1 except that the blending ratio of the addition reaction type liquid silicone rubber and the silicone foam was changed to 80 parts by weight / 20 parts by weight, and the blending ratio of the addition reaction type liquid silicone rubber and the silicone foam was 70 parts by weight / 30 parts by weight. An oil application roller B was obtained in the same manner as above. The results are shown in Table 1.

  Example 1 except that the blending ratio of the addition reaction type liquid silicone rubber and the silicone foam was changed to 80 parts by weight / 20 parts by weight, and the blending ratio of the addition reaction type liquid silicone rubber and the silicone foam was 60 parts by weight / 40 parts by weight. An oil application roller C was obtained in the same manner as above. The results are shown in Table 1.

  Example 1 except that the blending ratio of the addition reaction type liquid silicone rubber and the silicone foam was changed to 80 parts by weight / 20 parts by weight, and the blending ratio of the addition reaction type liquid silicone rubber and the silicone foam was 50 parts by weight / 50 parts by weight. An oil application roller D was obtained in the same manner as above. The results are shown in Table 1.

  Example 1 except that the blending ratio of the addition reaction type liquid silicone rubber and the silicone foam was changed to 80 parts by weight / 20 parts by weight, and the blending ratio of the addition reaction type liquid silicone rubber and the silicone foam was 40 parts by weight / 60 parts by weight. An oil application roller E was obtained in the same manner as above. The results are shown in Table 1.

  Example 1 except that the blending ratio of the addition reaction type liquid silicone rubber and the silicone foam was changed to 80 parts by weight / 20 parts by weight, and the blending ratio of the addition reaction type liquid silicone rubber and the silicone foam was 30 parts by weight / 70 parts by weight. The oil application roller F was obtained by the same method as that described above. The results are shown in Table 1.

  Example 1 except that the addition ratio of the addition reaction type liquid silicone rubber and the silicone foam is 80 parts by weight / 20 parts by weight, and the addition ratio of the addition reaction type liquid silicone rubber and the silicone foam is 20 parts by weight / 80 parts by weight. An oil application roller G was obtained in the same manner as described above. The results are shown in Table 1.

Comparative Example 1
Example 1 except that the blending ratio of the addition reaction type liquid silicone rubber and the silicone foam is 80 parts by weight / 20 parts by weight, and the blending ratio of the addition reaction type liquid silicone rubber and the silicone foam is 100 parts by weight / 0 part by weight. The oil application roller H was obtained by the same method as that described above. The results are shown in Table 1.

Comparative Example 2
Example 1 except that the blending ratio of the addition reaction type liquid silicone rubber and the silicone foam is 80 parts by weight / 20 parts by weight, and the blending ratio of the addition reaction type liquid silicone rubber and the silicone foam is 10 parts by weight / 90 parts by weight. The oil application roller I was obtained in the same manner as described above. The results are shown in Table 1.

  Further, in the results of Table 1, the relationship between the blending ratio of silicone foam and “bulk density”, “porosity”, “heat capacity”, “thermal conductivity (λ)”, “rubber hardness (Asker C)” is shown respectively. 1 to FIG.

  As is apparent from Table 1, an oil application roller using a porous silicone rubber foam obtained by molding and heat-curing a mixture containing liquid silicone rubber, silicone foam and a release agent as a roll member has a low It had a heat capacity and a low thermal conductivity. Further, as is apparent from FIGS. 1 to 5, particularly in the examples where the porosity is between 5.5% and 39.1%, the roller strength at the time of durability was sufficient.

  According to the oil application roller of the present embodiment, a low heat capacity and a low thermal conductivity can be achieved. Further, the structure is simple, the manufacturing method can be simplified, and the cost of the oil application roller can be reduced.

It is a side view which shows the installation state in the fixing device of the oil application roller which is this Embodiment. It is sectional drawing of the radial direction of the oil application roller which is this Embodiment. It is sectional drawing of the axial direction of the oil application roller which is this Embodiment. It is a figure which shows the relationship between the compounding ratio of a silicone foam, and a bulk density. It is a figure which shows the relationship between the compounding ratio of a silicone foam, and a porosity. It is a figure which shows the relationship between the compounding ratio of a silicone foam, and a heat capacity. It is a figure which shows the relationship between the compounding ratio of a silicone foam, and heat conductivity. It is a figure which shows the relationship between the compounding ratio of a silicone foam, and rubber hardness.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Oil application roller 2 Silicone rubber foam 4 Fixing device 5 Heat fixing roll 6 Pressure roll 7 Recording paper 7a Recording paper surface 8 Toner 9 Nip part

Claims (6)

  An oil application roller comprising a shaft core and a porous silicone rubber foam attached to the outer periphery of the shaft core, wherein the silicone rubber foam contains a gas-filled bubble part and a release agent An oil application roller comprising a mesh structure.   The oil application roller, wherein the silicone rubber foam is obtained by molding and curing a mixture containing a liquid silicone rubber, a foaming agent and a release agent.   The oil application roller according to claim 1 or 2, wherein the porosity of the silicone rubber foam is 3 to 40%.   The oil application roller according to any one of claims 1 to 3, wherein the rubber hardness (Asker C) of the silicone rubber foam is 2.0 to 30.0.   The oil application roller according to any one of claims 1 to 4, wherein a release agent application control layer is further provided on the outer peripheral surface of the silicone rubber foam. A method for producing an oil application roller, wherein a mixture containing a liquid silicone rubber, a foaming agent and a release agent is poured into a mold having a shaft core at the center, cured, and demolded.

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