JP2006323229A - Rotating body for fixing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rotating body for fixing by which the sufficient uniformity of the gloss of an image is obtained because pressure applied to toner is uniform while restraining heat conductivity to be low without using an elastic layer using LTV sponge. <P>SOLUTION: The rotating body for fixing includes: a cylindrical base substance 18; at least a porous body layer 32 disposed to surround the outer periphery of the cylindrical base substance and made of closed cell type silicone elastomer which is prepared of emulsion composition; and a tube made of synthetic resin with which the outer periphery of the porous body layer 32 is coated. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a fixing rotating body in which an outer peripheral surface of a cylindrical substrate is covered with a porous body layer, and further, an outer peripheral surface of the porous body layer is covered with a synthetic resin tube.

  In an electrophotographic image forming apparatus such as a copying machine, a printer, or a facsimile, a fixing roller is used as a fixing rotating body for a fixing device used when fixing unfixed toner on a recording material on the recording material. And fixing belts and fixing films.

  As the fixing roller, there are a fixing roller in which the outer peripheral surface of a cylindrical thin core metal is coated with a release layer such as a fluororesin, and a pressure roller in which an outer peripheral surface of the core metal is coated with an elastic layer. A nip portion is formed by pressing and deforming the elastic layer of the pressure roller. A recording material carrying unfixed toner is introduced into the nip portion, and the unfixed toner is covered by heating and pressing. It is fixed on the recording material.

  In recent years, a pressure roller of a fixing device used in a copying machine, a printer, a facsimile machine, or the like, in which a silicone rubber foam layer is formed on a core metal and a PFA tube is coated as a release layer, has been used. Thus, by further reducing the hardness of the pressure roller, it is possible to aim at improving the image quality, particularly when fixing color toner.

  However, the elastic layer of the pressure roller is not only required to reduce the hardness, but also due to the recent demand for shortening the start-up time due to energy saving, the heat of the elastic layer of the pressure roller is made difficult to remove heat from the fixing roller. It is necessary to lower the conductivity. For this purpose, the elastic layer of the pressure roller has a foam made of liquid silicone rubber having a low thermal conductivity and a state before curing (hereinafter simply referred to as an LTV foam). Was needed.

Therefore, according to Patent Document 1, it is said that an LTV foam having a low thermal conductivity and a liquid state before curing is obtained from LTV, a water-absorbing polymer, a surfactant, and water.
JP 2003-226774 A

  However, the LTV foam according to the technique of Patent Document 1 has an average cell diameter of 130 μm to 200 μm in the internal bubble part (cell part), and this LTV foam is coated as an elastic layer of a pressure roller to be unfixed. When the toner is fixed on the recording material, the pressure applied to the toner is different between the cell portion and the elastic material portion (cell wall portion). Therefore, the portion where the pressure is different becomes unevenness of the image. Even though it is coated with the film, there is a problem that the uniformity of gloss of the image is not sufficient.

  In this way, the outer peripheral surface of the metal core of the pressure roller is coated with an elastic layer made of a material other than the LTV foam, and the pressure applied to the toner on the cell portion and the cell wall portion is made uniform while keeping the thermal conductivity low. Therefore, there has been a demand for a pressure roller that can be used and has sufficient gloss uniformity.

  The present invention has been made in view of the above-described circumstances, and an object of the present invention is that the pressure applied to the toner is uniform while keeping the thermal conductivity low without using an elastic layer using an LTV foam. An object of the present invention is to provide a fixing rotating body with sufficient uniformity of image gloss.

  In order to solve the above-mentioned problems and achieve the object, a fixing rotating body according to the present invention is arranged according to claim 1 so as to surround a cylindrical base and an outer periphery of the cylindrical base. It is characterized by comprising at least a closed-cell type silicone elastomer porous body layer prepared from the emulsion composition, and a synthetic resin tube covering the outer periphery of the porous body layer.

  Further, in the fixing rotating body according to the present invention, according to the second aspect, in the porous body layer, cells having a diameter of 50 μm or less occupy 50% or more of the total number of cells, and 60% or more. It is characterized by being formed from a silicone elastomer having a single-bubble ratio.

  According to a third aspect of the present invention, there is provided a fixing rotator according to the third aspect, wherein the formula (A): 0 <= (mn) / m <= 0.5 (where m is the cell A cell satisfying the relationship represented by (major axis, n represents the minor axis of the cell) occupies 50% or more of the total number of cells.

  According to the fourth aspect of the present invention, the fixing rotator includes cells satisfying the relationship represented by the formula (B): 0 <= (mn) / n <= 0.5. It occupies 50% or more of the total number of cells.

  According to a fifth aspect of the present invention, the fixing rotator is characterized in that the silicone elastomer has an average cell diameter of 30 μm or less.

  According to a sixth aspect of the present invention, the fixing rotating body is characterized in that the silicone elastomer has a single bubble ratio of 80% or more.

  According to a seventh aspect of the present invention, the fixing rotator is characterized in that the diameter of the cell is in the range of 0.1 μm to 70 μm.

  According to the fixing rotor according to the present invention, a liquid silicone rubber material in which the porous body is cured to produce a silicone elastomer, a silicone oil material having a surface active action, and It is prepared from a water-in-oil emulsion composition containing water.

  Also, a fixing rotator according to the present invention. According to a ninth aspect of the present invention, the porous body layer is provided with a plurality of through holes that are continuous from one end of the porous body to the opposite end.

  According to a tenth aspect of the present invention, the fixing rotator is a fixing roller having a cored bar as a cylindrical base.

  According to a tenth aspect of the present invention, the fixing rotating body is characterized in that the fixing roller is a pressure roller.

  According to a twelfth aspect of the present invention, the fixing rotator is a fixing belt having a flexible belt base as a cylindrical base. It is a feature.

  According to a thirteenth aspect of the fixing rotary member of the present invention, the synthetic resin tube is made of a fluororesin.

  According to a fifteenth aspect of the present invention, the fixing rotating body is covered by inserting the synthetic resin tube into an outer periphery of the porous body layer. It is characterized by being.

  According to a fifteenth aspect of the present invention, there is provided the fixing rotating body according to the fifteenth aspect, wherein the porous body layer includes the synthetic resin tube fixed to the inner peripheral surface of the cavity of the molding die, and the synthetic resin tube. It is characterized in that it is molded by injecting the silicone elastomer between the base and the substrate set concentrically in a resin tube.

  The fixing rotator of the present invention uses, as an elastic layer, at least a closed cell type silicone elastomer porous body layer prepared from an emulsion composition without using an elastic layer using an LTV foam. Since the pressure applied to the toner is uniform while keeping the thermal conductivity low, a fixing rotator with sufficient uniformity of image gloss is provided.

  The configuration of an embodiment of a fixing rotator according to the present invention will be described below with reference to the accompanying drawings. In the following description, the fixing rotator according to the present invention is applied to a pressure roller. The case will be described in detail.

  The order of the following explanations is as follows. First, a silicone elastomer porous body which is not a foam and is characteristically provided as a configuration of an embodiment of a fixing rotating body according to the present invention. Next, the structure of the pressure roller as an embodiment of the fixing rotating body according to the present invention will be described. Finally, the silicone elastomer porous body is used. A specific example of the pressure roller will be described.

  First, the structure of the silicone elastomer porous body used in the present invention and the method for producing the porous body prepared from this emulsion will be described in detail below.

  First, the porous body described above is a closed-cell silicone elastomer porous body in this embodiment, and more specifically, a cell wall made of silicone elastomer and a large number of dispersed and distributed in the matrix. It can be expressed as including closed cells (closed cells).

  The silicone elastomer porous body is a substantially closed-cell type characterized in that cells having a diameter of 50 μm or less occupy 50% or more of the total number of cells and have a single bubble ratio of 60% or more. It is a silicone elastomer porous body.

  As will be described in detail later, when the single bubble ratio, which is an index of the ratio of the number of closed cells, is less than 60%, the strength of the porous body becomes weak.

  Furthermore, the silicone elastomer porous body may have a cell diameter in the range of 0.1 to 70 μm, and the cell diameter may be in the range of 0.1 to 60 μm. In the silicone elastomer porous body of the present invention, cells having a diameter of 50 μm or less can occupy 80% or more of the total number of cells.

In this silicone elastomer porous body, the following formula (A)
(A): 0 <= (mn) / m <= 0.5
(Where m represents the major axis of the cell and n represents the minor axis of the cell), the cells satisfying the relationship between the major axis and the minor axis can occupy 50% or more of the total number of cells. Is.

Here, the formula (A) is a scale representing how close a cell is to a true sphere (sphericity). In this silicone elastomer porous body, the cells satisfying the conditions given by the following formula (B) can occupy 80% or more of the total number of cells.
(B): 0 <= (mn) / n <= 0.5

  Here, the major axis m of the cell means a linear distance between the maximum two points on the outline of the cell passing through the approximate center of each cell appearing in the cross section of the silicone elastomer porous body, and the minor axis n is For each cell, it means the minimum distance between two points on the cell outline that passes through its approximate center. More specifically, an arbitrary cross section of the silicone porous body is photographed by SEM, and the major axis m and minor axis n of each cell are measured in an area where about 100 to 250 cells exist. This measurement can be performed manually using a caliper. The average cell diameter can also be performed by image processing. The image processing can be performed using, for example, TOYOBO analysis software “V10 for Windows (registered trademark) 95 Version 1.3”.

  The diameter of each cell corresponds to a value obtained by dividing the sum of the major axis m and minor axis n of each cell by 2. Needless to say, if the cell is a true sphere, m = n.

  Furthermore, the silicone elastomer porous body can have an average cell diameter of 30 μm or less, and further 10 μm or less.

  The porous body of the present invention has a uniform cell diameter as the cell size characteristics in the region where about 100 to 250 cells are present represent the cell size characteristics of the entire porous body. In other words, the porous body of the present invention has a cell size characteristic (cell size, average cell size, 50 μm or less) defined in the present invention in a rectangular region where 100 to 250 cells exist in an arbitrary cross section. The proportion of cells having size, sphericity, etc.). The cell size characteristic in an arbitrary region of such a cross-sectional area is the entire cell size characteristic of the porous body, for example, a porous body having a size up to 160 mm (width) × 400 mm (length) × 15 mm (thickness). It is confirmed that it can represent the overall cell size characteristics of Conventionally, in a rectangular region where 100 to 250 cells exist, there is no porous body that exhibits the cell size characteristics defined in the present invention.

  As described above, the porous silicone elastomer is substantially of the closed cell type. The proportion of closed cells (closed cells) in the total number of cells of the porous body can be expressed by “single bubble ratio”. This single bubble rate can be measured as described in the Examples section below. The silicone elastomer porous body of the present invention can have a single bubble rate of 60% or more, and can further have a single bubble rate of 80% or more.

  This porous silicone elastomer can be basically produced from a liquid silicone rubber material that is cured to produce a silicone elastomer, and a water-in-oil emulsion containing water. At that time, when the liquid silicone rubber material has a low viscosity, the liquid silicone rubber material and water can be sufficiently stirred to form an emulsion, and then heated and cured immediately thereafter. However, the porous silicone elastomer of the present invention is preferably produced from a water-in-oil emulsion containing a silicone oil material having a surface active action together with a liquid silicone rubber material that cures to form a silicone elastomer and water. Can do.

  The liquid silicone rubber material described above is not particularly limited as long as it is cured by heating to produce a silicone elastomer, but it is preferable to use a so-called addition reaction curable liquid silicone rubber. The addition reaction curable liquid silicone rubber contains a polysiloxane having an unsaturated aliphatic group as a main agent and an active hydrogen-containing polysiloxane as a crosslinking agent. In the polysiloxane having an unsaturated aliphatic group, the unsaturated aliphatic group is introduced at both ends and can also be introduced as a side chain. Such polysiloxane having an unsaturated aliphatic group can be represented by, for example, the following formula (1).

In Formula (1), R ¹ represents an unsaturated aliphatic group, and each R ² represents a C ₁ -C ₄ lower alkyl group, a fluorine-substituted C ₁ -C ₄ lower alkyl group, or a phenyl group. a + b is usually 50 to 2000. The unsaturated aliphatic group represented by R ¹ is usually a vinyl group. Each R ² is usually a methyl group.

  The active hydrogen-containing polysiloxane (hydrogen polysiloxane) acts as a crosslinking agent for the polysiloxane having an unsaturated aliphatic group, and has hydrogen atoms (active hydrogen) bonded to silicon atoms in the main chain. It is preferable that 3 or more hydrogen atoms exist per molecule of active hydrogen-containing polysiloxane. Such an active hydrogen-containing polysiloxane can be represented, for example, by the following formula (2).

In the formula (2), R ³ represents hydrogen or a C _{1 to} C ₄ lower alkyl group, and R ⁴ represents a C _{1 to} C ₄ lower alkyl group. c + d is usually 8 to 100. The lower alkyl group represented by R ³ and R ⁴ is usually a methyl group.

  These liquid silicone rubber materials are commercially available. In addition, in the commercial product, the polysiloxane having an unsaturated aliphatic group constituting the addition reaction curable liquid silicone rubber and the active hydrogen-containing polysiloxane are provided in separate packages, and are necessary for curing both described in detail below. The curing catalyst is added to the active hydrogen-containing polysiloxane. Needless to say, two or more liquid silicone rubber materials can be used in combination.

  The silicone oil material having a surface active action acts as a dispersion stabilizer for stably dispersing water in the emulsion. That is, the silicone oil material having a surface-active action exhibits affinity for water and also for liquid silicone rubber material. This silicone oil material preferably has a hydrophilic group such as an ether group. Further, this silicone oil material usually exhibits an HLB value of 3 to 13, preferably 4 to 11. More preferably, two types of ether-modified silicone oils having different HLB values of 3 or more are used in combination. In that case, more preferably, a first ether-modified silicone oil having an HLB value of 7 to 11 and a second ether-modified silicone oil having an HLB value of 4 to 7 are used in combination. Any ether-modified silicone oil can be obtained by introducing a polyether group into the side chain of polysiloxane, and can be represented by, for example, the following formula (3).

In the formula (3), R ⁵ represents a C _{1 to} C ₄ lower alkyl group, and R ⁶ represents a polyether group. e + f is usually 8 to 100. The lower alkyl group represented by R ⁵ is usually a methyl group. The polyether group represented by R ⁶ is usually a (C ₂ H ₄ O) _x group, a (C ₃ H ₆ O) _y group, or a (C ₂ H ₄ O) _x (C ₃ H ₆ O). ) _{Contains y} group. The HLB value is determined mainly by the number of x and y. These silicone oil materials having a surface active action are commercially available.

  Needless to say, water is present in the water-in-oil emulsion dispersed as a discontinuous phase in the form of particles (water droplets). As will be described in detail later, the particle size of the water particles substantially determines the cell diameter of the porous silicone elastomer of the present invention.

  The above-described water-in-oil emulsion can contain a curing catalyst in order to cure the liquid silicone rubber material. As the curing catalyst, a platinum catalyst can be used as known per se. The amount of the platinum catalyst is about 1 to 100 ppm by weight as platinum atoms. The curing catalyst may be added to the water-in-oil emulsion when producing the silicone elastomer porous body, but can also be added when producing the water-in-oil emulsion.

  In the water-in-oil emulsion described above, with respect to 100 parts by weight of the liquid silicone rubber material, a ratio of 0.2 to 5.5 parts by weight of the silicone oil material having a surfactant activity and a ratio of 10 to 250 parts by weight of water. Is preferably used for obtaining an emulsion particularly excellent in water dispersion stability. By using such an emulsion excellent in water dispersion stability, a good porous body can be produced more stably.

  Further, when the silicone oil material having a surface active action is a combination of the first ether-modified silicone oil and the second ether-modified silicone oil, the first amount is 100 parts by weight with respect to 100 parts by weight of the liquid silicone rubber material. Use ether-modified silicone oil in an amount of 0.15-3.5 parts by weight, and use a second ether-modified silicone oil in an amount of 0.05-2 parts by weight (total 0.2-5.5 parts by weight). Is preferred. Moreover, when a liquid silicone rubber material consists of a combination of polysiloxane having an unsaturated aliphatic group and active hydrogen-containing polysiloxane, the weight ratio of the former to the latter is preferably 6: 4 to 4: 6.

  Moreover, this silicone elastomer porous body can contain various additives according to the use. Examples of such additives include colorants (pigments, dyes), conductivity imparting materials (carbon black, metal powder, etc.), and fillers (silica, etc.). These additives can be blended in the water-in-oil emulsion. Furthermore, the water-in-oil emulsion may contain a non-reactive silicone oil having a low molecular weight in order to adjust the viscosity of the emulsion for the purpose of facilitating defoaming, for example. When the water-in-oil emulsion has a viscosity of 1 cSt to 200,000 cSt, defoaming can be easily performed and it is convenient for handling.

  The water-in-oil emulsion can be produced by various methods. In general, it is produced by mixing a liquid silicone rubber material, a silicone oil material having a surface-active action, and water together with further additives as necessary, and stirring sufficiently. When the liquid silicone rubber material is provided by a combination of a polysiloxane having an unsaturated aliphatic group and an active hydrogen-containing polysiloxane, a silicone oil material having a surface active activity with a polysiloxane having an unsaturated aliphatic group A first mixture can be obtained by mixing and stirring a part of the mixture, and the second mixture can be obtained by mixing and stirring the active hydrogen-containing polysiloxane and the remainder of the silicone oil material having a surface active action. Next, while mixing and stirring the first mixture and the second mixture, water is gradually added and stirred to obtain a desired emulsion.

  Needless to say, the method for producing the water-in-oil emulsion is not limited thereto. The order of addition of the liquid silicone rubber material, the silicone oil material having a surface-active action, water, and the additive added as necessary may be arbitrary. Agitation to form a suitable water-in-oil emulsion can be performed, for example, at a stirrer speed of 300 rpm to 1000 rpm. After the formation of the emulsion, the water-in-oil emulsion can be subjected to a defoaming treatment without heating, for example, using a vacuum decompressor to remove air present in the emulsion.

  In order to produce a silicone elastomer porous body using a water-in-oil emulsion as described above, the water-in-oil emulsion is heated and cured (primary heating) under the presence of a curing catalyst. Can be used. In the primary heating, it is preferable to use a heating temperature of 130 ° C. or lower in order to heat and cure the liquid silicone rubber material without volatilizing water in the emulsion. The heating temperature at the time of primary heating is usually 80 ° C. or higher, and the heating time is usually about 5 to 60 minutes. By this primary heating, the liquid silicone rubber material is cured, and water particles in the emulsion are confined in the state of the emulsion. The cured silicone rubber is cured to such an extent that it can withstand the expansion force upon evaporation of water by secondary heating described below.

  Next, secondary heating is performed to remove moisture from the cured silicone rubber in which water particles are trapped. This secondary heating is preferably performed at a temperature of 70 ° C to 300 ° C. When the heating temperature is less than 70 ° C., it takes a long time to remove water, and when the heating temperature exceeds 300 ° C., the cured silicone rubber may be deteriorated. In heating at 70 ° C. to 300 ° C., moisture is volatilized and removed in 1 hour to 24 hours. The water is volatilized and removed by the secondary heating, and the final curing of the silicone rubber material is also achieved. The volatilized and removed water leaves cells having a diameter approximately equal to that of water particles in the cured silicone rubber material (silicone elastomer).

  Thus, this silicone elastomer porous body can be produced from a water-in-oil emulsion as described above without causing a foaming phenomenon. Further, the water particles in the water-in-oil emulsion described above are confined in the silicone rubber cured by the primary heating, and only volatilize during the secondary heating.

  Next, although the porous body mentioned above is demonstrated more concretely by several Example, it cannot be overemphasized that this porous body is not limited to these Examples.

In the following examples, the single bubble ratio of the silicone elastomer porous material was determined as follows.
<Measurement of single bubble ratio>
Since the silicone elastomer porous body of the present invention has high surface tension and its cells are fine, it is difficult for water to enter. Accordingly, a surfactant is used in order to improve the wettability of the silicone elastomer porous body to water.

  That is, the surface layer (about 1.0 mm from the surface) of the manufactured silicone elastomer porous body is removed, and the weight of the porous body after removal (the weight of the porous body before water absorption) is measured. This porous body is immersed in a mixed solution of 100 parts by weight of water and 1 part by weight of hydrophilic silicone oil (polyether-modified silicone oil (KF-618 manufactured by Shin-Etsu Chemical Co., Ltd.)) and left under reduced pressure (70 mmHg) for 10 minutes. To do. Then, it returns to atmospheric pressure, takes out a porous body from a mixed solution, wipes off the water adhering to the porous body surface cleanly, and measures the weight (porous body weight after water absorption) of the porous body. The water absorption rate, open cell rate, and single bubble rate are calculated sequentially from the following formula.

Water absorption rate (%) = {(weight of porous body after water absorption−weight of porous body before water absorption) / weight of porous body before water absorption} × 100
Open cell ratio (%) = (specific gravity of porous body × water absorption / 100) / {specific gravity of mixed solution− (specific gravity of porous body / specific gravity of silicone elastomer)} × 100
Single bubble rate (%) = 100-open bubble rate (%).

  Here, the specific gravity of the silicone elastomer is the specific gravity of a liquid silicone rubber material cured as it is, and is also described in the product catalog.

Example 1
In Example 1, liquid silicone rubber (trade name KE-1353) obtained from Shin-Etsu Chemical Co., Ltd. was used as the liquid silicone rubber material. In this liquid silicone rubber, active hydrogen-containing polysiloxane (viscosity: 16 Pa · S) and vinyl group-containing polysiloxane (viscosity: 15 Pa · S) are provided as separate packages. An amount of platinum catalyst was added. Hereinafter, the former is indicated as silicone rubber A agent, and the latter is indicated as silicone rubber B agent. The active hydrogen-containing polysiloxane has a structure of the above formula (2) in which each R ⁴ is a methyl group, while the vinyl group-containing silicone oil has each R ¹ is a vinyl group and each R ² is a methyl group. It has a certain structure of the above formula (1). Further, as dispersion stabilizers, KF-618 (HLB value: 11), which is a polyether-modified silicone oil manufactured by Shin-Etsu Chemical Co., Ltd .; hereinafter, “dispersion stabilizer I”) and KF-6015 (HLB value: 4). Hereinafter, dispersion stabilizer II) was used. The specific gravity of the silicone elastomer itself obtained from the liquid silicone rubber material used in this example is 1.04 (catalog value).

  Add a mixture of 0.7 parts by weight of dispersion stabilizer I and 0.3 parts by weight of dispersion stabilizer II in advance to 50 parts by weight of silicone rubber A agent, and stir for 5 minutes with a hand mixer. To prepare a mixture A. On the other hand, a mixture prepared by previously mixing 0.7 parts by weight of dispersion stabilizer I and 0.3 parts by weight of dispersion stabilizer II is added to 50 parts by weight of silicone rubber B agent, and stirred for 5 minutes with a hand mixer. Mix well and prepare mixture B.

  The obtained mixture A and mixture B were mixed, and 10 parts by weight of water was added while stirring with a hand mixer for 3 minutes, followed by further stirring for 2 minutes. While stirring this mixture with a hand mixer, 90 parts by weight of water was gradually added to prepare an emulsion.

  The obtained emulsion is defoamed in a vacuum decompressor to remove mixed air, and then poured into a 6 mm deep compression mold and heated (primary heating) at a set temperature of 100 ° C. for 30 minutes using a press machine. Molded. The obtained molded body (porous body precursor) was heated (secondary heating) at 150 ° C. for 5 hours in an electric furnace to remove water. In this way, a rectangular elastomeric silicone elastomer porous test piece having a length of 42 mm, a width of 20 mm, and a thickness of 6 mm was produced. The test piece was cut in the width direction, the cut surface was observed with an SEM, the major axis and minor axis of the cell were measured with calipers, and the cell size characteristics were determined. Moreover, the single bubble rate was measured about this test piece. The results are shown in Table 1 below. Moreover, when the specific gravity of the porous elastomer obtained in the present Example was measured, it was 0.66 and the hardness (Asker-C) was 40. In addition, the SEM photograph (magnification 100 times) of the cut surface of this test piece is shown in FIG. Thus, a closed cell porous body having a very fine and uniform cell diameter was obtained.

Example 2
In Example 2, liquid silicone rubber (trade name DY35-7002) obtained from Toray Dow Corning was used as the liquid silicone rubber material. In this liquid silicone rubber, active hydrogen-containing polysiloxane (viscosity: 15 Pa · S) and vinyl group-containing polysiloxane (viscosity: 7.5 Pa · S) are provided as separate packages. A catalytic amount of platinum catalyst was added. Hereinafter, the former is indicated as silicone rubber A agent, and the latter is indicated as silicone rubber B agent. The active hydrogen-containing polysiloxane has a structure of the above formula (2) in which each R ⁴ is a methyl group, while the vinyl group-containing silicone oil has each R ¹ is a vinyl group and each R ² is a methyl group. It has a certain structure of the above formula (1). As the dispersion stabilizer, the above dispersion stabilizer I and dispersion stabilizer II were used. The specific gravity of the silicone elastomer itself obtained from the liquid silicone rubber material used in this example is 1.03 (catalog value).

  Add a mixture of 0.7 parts by weight of dispersion stabilizer I and 0.3 parts by weight of dispersion stabilizer II in advance to 50 parts by weight of silicone rubber A agent, and stir for 5 minutes with a hand mixer. To prepare a mixture A. On the other hand, a mixture prepared by previously mixing 0.7 parts by weight of dispersion stabilizer I and 0.3 parts by weight of dispersion stabilizer II is added to 50 parts by weight of silicone rubber B agent, and stirred for 5 minutes with a hand mixer. Mix well and prepare mixture B.

  The obtained mixture A and mixture B were mixed, and 10 parts by weight of water was added while stirring with a hand mixer for 3 minutes, followed by further stirring for 2 minutes. While stirring this mixture with a hand mixer, 90 parts by weight of water was gradually added to prepare an emulsion.

  Using this emulsion, a porous test piece of silicone elastomer was prepared in the same manner as in Example 1, the cell size characteristics were measured in the same manner as in Example 1, and the single bubble ratio was measured. The results are also shown in Table 1 below. When the specific gravity of the porous elastomer obtained in this example was measured, it was 0.55 and the hardness (Asker-C) was 56. In addition, the SEM photograph (100-times multiplication factor) of the cut surface of this test piece is shown in FIG. Thus, a closed cell porous body having a very fine and uniform cell diameter was obtained.

Example 3
In this Example 3, the silicone rubber A agent and the silicone rubber B agent used in Example 2 described above were mixed, and after stirring for 3 minutes with a hand mixer, 10 parts by weight of water was added, and then for another 2 minutes. Stir. While stirring this mixture with a hand mixer, 90 parts by weight of water was gradually added to prepare an emulsion.

  Using this emulsion, a porous test piece of silicone elastomer was prepared in the same manner as in Example 1, the cell size characteristics were measured in the same manner as in Example 1, and the single bubble ratio was measured. The results are also shown in Table 1 below. The specific gravity of the porous elastomer obtained in this example was measured and found to be 0.53 and the hardness (Asker-C) was 58.

Example 4
In Example 4, the liquid silicone rubber material used in Example 2 described above and the liquid silicone rubber obtained from Toray Dow Corning (trade name DY35-615) were used. This liquid silicone rubber DY35-615 is provided as separate packages of active hydrogen-containing polysiloxane (viscosity: 113 Pa · S) and vinyl group-containing polysiloxane (viscosity: 101 Pa · S). In which a catalytic amount of a platinum catalyst was added. Hereinafter, the former is indicated as the present silicone rubber A agent and the latter as the present silicone rubber B agent. The active hydrogen-containing polysiloxane has a structure of the above formula (2) in which each R ⁴ is a methyl group, while the vinyl group-containing silicone oil has each R ¹ is a vinyl group and each R ² is a methyl group. It has a certain structure of the above formula (1).

  In 50 parts by weight of a 50:50 volume ratio mixture of this silicone rubber A agent and the silicone rubber A agent used in Example 2, 0.7 part by weight of dispersion stabilizer I and 0.3 part by weight of dispersion stabilizer. A mixture preliminarily mixed with II was added, stirred for 5 minutes with a hand mixer, and sufficiently dispersed to prepare a mixture A. On the other hand, 0.7 parts by weight of dispersion stabilizer I and 0.3 parts by weight of dispersion were added to 50 parts by weight of a 50:50 volume ratio of the present silicone rubber B agent and the silicone rubber B agent used in Example 2. A mixture pre-mixed with Stabilizer II was added, stirred for 5 minutes with a hand mixer, and fully dispersed to prepare Mixture B.

  The obtained mixture A and mixture B were mixed, and 10 parts by weight of water was added while stirring with a hand mixer for 3 minutes, followed by further stirring for 2 minutes. While stirring this mixture with a hand mixer, 90 parts by weight of water was gradually added to prepare an emulsion.

  Using this emulsion, a porous test piece of silicone elastomer was prepared in the same manner as in Example 1, the cell size characteristics were measured in the same manner as in Example 1, and the single bubble ratio was measured. The results are also shown in Table 1 below. The specific gravity of the silicone elastomer itself obtained from the liquid silicone rubber material used in this example was 1.07. Moreover, the specific gravity of the porous body obtained in this example was 0.60, and the hardness (Asker-C) was 35.

Comparative Example 1
Remove the pressure roller from Fuji Xerox printer Able 1405, and remove the test piece from the silicone elastomer porous material (foamed with 2,2-azobisisobutyronitrile as the foaming agent), which is the elastic layer. Cut out. About this test piece, the cell size characteristic and the single bubble rate were measured similarly to Example 1. The results are also shown in Table 1 below. In addition, the SEM photograph (100-times multiplication factor) of the cut surface of this test piece is shown in FIG.

(Description of pressure roller)
Next, the pressure roller 14 according to one embodiment of the present invention is manufactured by a manufacturing method described later. As shown in FIG. Further, a porous body layer 32 disposed so as to surround the primer 30 and a release layer 34 made of a synthetic resin film coated on the outer periphery of the porous body layer 32. Yes.

  Here, as described above, the porous body layer 32 is composed of a silicone elastomer containing at least closed cells, that is, a closed cell type silicone elastomer. The porous body layer 32 is processed by an outer diameter polishing apparatus (not shown) so as to have a predetermined outer diameter.

  The synthetic resin film constituting the release layer 34 described above is made of a fluororesin film, more specifically, a PFA resin in this embodiment. The PFA tube used in this example has a thickness of 20 to 150 [mu] m and the inner surface is etched.

  The outer diameter of the PFA tube is 2 to 10% smaller than the outer diameter of the fixing roller as the final product coated with the PFA tube. That is, if a PFA tube whose outside diameter is smaller than the product outside diameter by 2% or less (substantially substantially equal) is used, the contact between the PFA tube and the rubber roller R becomes insufficient, and the PFA tube A problem occurs in the adhesion between the rubber roller R and the rubber roller R. On the other hand, if a material having a size smaller than 10% is used, the elastic elongation range of the PFA tube is exceeded at the time of molding.

  The pressure roller 14 is not limited to such a configuration. As shown in FIG. 5, the pressure roller 14 has several hollow holes 36 that are continuous in parallel with the cored bar in the silicone elastomer porous body layer 32. Can be provided. The hollow hole 36 has been described as being parallel to the cored bar 18, but is not necessarily parallel to the cored bar 18, and is continuous from one end of the silicone elastomer porous body layer 32 to the other end. Needless to say, the shape, size, number, and the like of the hollow holes 36 can be freely provided in the hollow hole 36. By providing such a hollow hole 36, it is possible to prevent the outer diameter of the pressure roller 14 from expanding even if the silicone elastomer porous body is heated and expanded by receiving heat from the fixing roller.

  Thus, the configuration of the pressure roller 14 is such that the silicone elastomer porous body layer 32 is formed on the outer peripheral surface of the cored bar 18, and the outer periphery of the porous body layer 32 is formed by a release layer 34 configured by a PFA tube. Since it is covered, the structure is simple, the heat capacity is small, the rise time is short, the average cell diameter is small, and the uniformity of the gloss of the image is obtained, and many of the cells are closed cells and have a nearly spherical shape It is easy to disperse the pressure at the nip portion, the cell is not easily destroyed, and since some hollow holes 36 are provided, the outer diameter is hardly expanded by heating, which has an unprecedented unique effect. A durable pressure roller is obtained.

  Incidentally, this silicone elastomer porous body can be used not only for the pressure roller 14 as in this embodiment, but also for a fixing roller, a fixing belt, and a fixing film. All rollers and belts have the same basic configuration, and any configuration may be used as long as a porous layer made of a silicone elastomer porous body is provided on the outer periphery of the substrate. The thickness of the porous layer varies depending on the individual, but is generally about 0.1 mm to 20 mm, and the length is usually up to 400 mm. The outer diameter of the substrate also varies from individual to individual, but is usually about 5 mm to 100 mm.

Example 5
Next, a method for manufacturing the pressure roller 14 will be schematically described. First, an iron core 18 having a rubber surface length of 310 mm and an outer diameter of 14 mm is set in the mold, and the emulsion of Example 4 is injected into the mold and cured by heating. And grinding so that the outer diameter of the porous body layer 32 is 25.0 mm. Thereafter, a pressure roller was obtained by inserting the PFA tube into the outer periphery of the porous body 32 so as to fit outside and bonding the two together.

  The silicone rubber porous body layer thus obtained was measured for cell size characteristics and single bubble rate in the same manner as in Example 1. As a result, the average cell diameter was about 5 μm and the single bubble rate was 99.7%. there were.

  The pressure roller thus obtained was incorporated into a printer Able 1405 manufactured by Fuji Xerox Co., Ltd., and the gloss uniformity of the obtained image was evaluated. In the evaluation method, a solid image was passed, and the presence or absence of occurrence of gloss unevenness in the obtained image was visually confirmed. The evaluation criteria are good: ○, usable: Δ, unusable: x, and the evaluation results are shown in Table 2.

Comparative Example 2
The same core 18 as in Example 5 was set in a mold, and a silicone rubber mixture kneaded with silicone rubber XE15-9036 manufactured by GE Toshiba Silicone was injected into the mold and cured by heating. By attaching to a polishing apparatus, grinding the LTV foam layer to have an outer diameter of 25.0 mm, inserting a PFA tube similar to that of Example 5 to fit, and bonding the two together A pressure roller was obtained.

  With respect to this LTV foam layer, the cell size characteristics and the single bubble rate were measured in the same manner as in Example 1. The average cell diameter was 150 μm and the single bubble rate was 10%. The specific gravity of the silicone elastomer itself obtained from the silicone rubber material used in this comparative example was 1.05. The specific gravity of the LTV foam obtained in this comparative example was 0.49, and the hardness (Asker-C) was 40. Then, in the same manner as in Example 5, the gloss uniformity of the image obtained by paper passing was evaluated. The evaluation results are shown in Table 2.

  As described above, the pressure roller having the conventional LTV foam layer having an average cell diameter of about 150 μm does not have sufficient gloss uniformity of the solid image obtained by passing the paper, but the average cell diameter of the present invention is The pressure roller of the silicone elastomer porous body elastic layer having a very fine size of 30 μm or less had sufficient gloss uniformity in a solid image obtained by passing paper.

  Needless to say, the fixing rotator according to the present invention is not limited to the above-described configuration and can be variously modified without departing from the gist of the present invention. The configuration of another embodiment of the fixing rotator will be described below with reference to the accompanying drawings. In the following description, the same parts as those described above are denoted by the same reference numerals, and the description thereof is omitted.

(Description of another configuration example of the pressure roller)
For example, the pressure roller 14 described above has been described as having a configuration in which the outer peripheral surface of the core metal 18 is uniformly covered with the silicone elastomer porous body layer 32. However, the pressure roller 14 is limited to such a configuration. Instead, several hollow holes 36 that are continuous in parallel with the core metal 14 can be provided in the silicone elastomer porous body layer 32. The hollow hole 36 has been described as being parallel to the cored bar 18, but is not necessarily parallel to the cored bar 18, and is continuous from one end of the silicone elastomer porous body layer 32 to the other end. Needless to say, the shape, size, number, and the like of the hollow holes can be freely provided.

  Further, in the above-described embodiment 5, it has been described that the PFA tube is inserted so as to be fitted on the outer periphery of the porous body layer 32 after being ground. The PFA tube is fixed in the cavity of the molding die, and the cored bar 18 is set concentrically with the PFA tube in the cavity. It goes without saying that the pressure roller 14 may be obtained by injecting the above-described emulsion between the tubes, heating, cooling, and removing from the molding die.

(Description of other application examples of fixing rotator)
Further, although the case where the fixing rotator according to the present invention is applied to the pressure roller has been described, the fixing rotator according to the present invention is applied to the fixing roller without being limited to such application. Needless to say, the present invention may be applied to a fixing belt in a belt fixing device or the like, or a fixing film of a film fixing device.

  Further, in the procedure of the embodiment of the manufacturing method described above, in order to form the porous body of the pressure roller, the core metal 18 is set in the mold, and the raw material of the porous body is formed on the outer periphery of the core metal 18. However, the present invention is not limited to such a procedure, and an insertion hole is formed in the center portion in advance. Needless to say, the pressure roller may be formed by forming the formed cylindrical porous body and inserting the cored bar 18 through the cylindrical porous body. In short, as long as the porous body layer 32 is formed on the outer periphery of the cored bar 18, the formation procedure is not particularly limited.

3 is a SEM photograph of a cross section of the silicone elastomer porous body produced in Example 1. FIG. 3 is a SEM photograph of a cross section of the silicone elastomer porous body produced in Example 2. 3 is a SEM photograph of a cross section of the porous silicone elastomer of Comparative Example 1. It is sectional drawing which shows a structure at the time of applying the rotary body for fixing concerning this invention to a pressure roller. It is a figure which shows roughly the structure concerning the other structural example at the time of applying the rotary body for fixing concerning this invention to a pressure roller.

Explanation of symbols

14 Pressure roller 18 Core metal 30 of pressure roller 14 Primer 32 between core metal of pressure roller 14 and porous body layer Porous body layer 34 of pressure roller 14 Release layer 36 of pressure roller 14 Porous body Hollow holes in the layer

Claims (15)

A cylindrical substrate;
A porous body layer made of at least closed-cell silicone elastomer prepared from an emulsion composition disposed so as to surround the outer periphery of the substrate;
A synthetic resin tube covering the outer periphery of the porous body layer;
A fixing rotator characterized by comprising:   2. The porous body layer is formed of a silicone elastomer having cells having a diameter of 50 μm or less occupying 50% or more of the total number of cells and having a single bubble ratio of 60% or more. The fixing rotating body according to 1. Formula (A): 0 <= (mn) / m <= 0.5
(Where m represents the major axis of the cell and n represents the minor axis of the cell) cells satisfying the relationship represented by 50% or more of the total number of cells. The fixing rotating body as described. Formula (B): 0 <= (mn) / n <= 0.5
The fixing rotating body according to claim 3, wherein the cells satisfying the relationship represented by the formula occupy 50% or more of the total number of cells.   The fixing rotor according to claim 2, wherein the silicone elastomer has an average cell diameter of 30 μm or less.   The fixing rotating body according to claim 2, wherein the silicone elastomer has a single bubble ratio of 80% or more.   The fixing rotating body according to claim 2, wherein a diameter of the cell is in a range of 0.1 μm to 70 μm.   The porous body is prepared from a liquid silicone rubber material that cures to produce a silicone elastomer, a silicone oil material that has a surface active action, and a water-in-oil emulsion composition containing water. The fixing rotating body according to claim 1.   The fixing rotation according to any one of claims 1 to 8, wherein the porous body layer is provided with a plurality of through holes continuous from one end of the porous body to the opposite end. body.   The fixing rotator according to claim 1, wherein the rotator is a fixing roller having a cored bar as a cylindrical base.   The fixing roller according to claim 10, wherein the fixing roller is a pressure roller.   10. The fixing rotator according to claim 1, wherein the rotator is a fixing belt provided with a belt substrate as a cylindrical substrate. 11.   2. The fixing rotating body according to claim 1, wherein the synthetic resin tube is made of a fluororesin.   2. The fixing rotating body according to claim 1, wherein the synthetic resin tube is covered by being inserted into an outer periphery of the porous body layer so as to be fitted.   The porous body layer is formed between the synthetic resin tube fixed to the inner peripheral surface of the cavity of the molding die and the base body set concentrically in the synthetic resin tube. The fixing rotating body according to claim 1, wherein the fixing rotating body is formed by injecting a silicone elastomer.