JP6085794B2 - Fixing pressure roll - Google Patents

Description

  The present invention relates to a fixing pressure roll including an elastic layer made of an elastomer porous material such as a silicone elastomer porous material, and is useful as a fixing roll, a pressure roll or the like of a fixing portion.

  In electrophotographic image forming apparatuses such as printers and copiers, a fixing roll, a pressure roll, and the like are used in a fixing unit that fixes unfixed toner. The fixing roll and the pressure roll of the fixing unit are pressed and rotated in a high temperature environment in a state where a nip portion is formed. Further, such a fixing pressure roll is required to have a low heat capacity in order to reduce the energy to be heated, and a technique for making it porous is known.

  Therefore, conventionally, an elastic layer made of foamed silicone rubber foamed with a foaming agent is used, but because the cell diameter and the wall thickness between the cells are not uniform, cell destruction occurs due to stress concentration during compression, As a result, the surface pressure of the nip portion is lowered, and there is a problem that fixing failure occurs.

  Therefore, an elastomer porous body having uniform spherical cells, which is produced via an emulsion composition having a liquid rubber material that is cured to produce an elastomer as a continuous phase, has attracted attention (see Patent Document 1, etc.). ).

  However, when such a porous elastomer is bonded to a core with a silane coupling agent, and a fixing roll or pressure roll as an elastic layer is applied to the fixing portion, the vicinity of the core is caused by shear stress during pressing. There was a problem that the elastic layer was broken and the transmission function such as driving force was lost.

Japanese Patent No. 4638714

  In view of such circumstances, an object of the present invention is to provide a fixing pressure roll having improved durability using an elastic layer made of a porous material produced via an emulsion.

A first aspect of the present invention that achieves the above object is provided with a core, a rubber layer having a thickness of 0.005 mm to 0.5 mm provided around the core, and provided around the rubber layer. And an elastic layer made of an elastomer porous body, which is a cured product of an emulsion composition containing a liquid rubber material as a continuous phase, where the thickness of the rubber layer is T1 and the thickness of the elastic layer is T2. The fixing pressure roller is characterized in that the ratio (T1 / T2) is 0.002 to 0.15 .

  The second aspect of the present invention is the fixing pressure roll according to claim 1, wherein the liquid rubber material is a liquid silicone rubber material.

  A third aspect of the present invention is the fixing pressure roll according to claim 1 or 2, wherein the emulsion composition comprises a W / O type emulsion.

  According to the present invention, there is provided a fixing pressure roll having an elastic porous layer having a substantially spherical fine cell and having excellent durability, and preventing peeling and breakage in the vicinity of the core. can do.

It is the longitudinal cross-sectional view and transverse cross-sectional view of the fixing pressure roll of one Embodiment. It is a figure which shows the manufacturing process of the fixing pressure roll of one Embodiment. It is a figure which shows the usage example of the fixing pressure roll of this invention. It is a figure which shows the usage example of the fixing pressure roll of this invention. It is a figure which shows the usage example of the fixing pressure roll of this invention.

  The elastomer porous body employed in the present invention includes a matrix (matrix) made of an elastomer and a large number of substantially spherical cells dispersed and distributed in the matrix.

  Here, as the elastomer constituting the matrix, silicone, urethane, chloroprene, ethylene propylene copolymer (EPM), ethylene propylene terpolymer (EPDM), styrene rubber (SBR), nitrile rubber (NBR), polyester series Elastomers, polyether elastomers, polyolefin elastomers, epichlorohydrin rubbers, and the like can be mentioned. In view of heat resistance as a fixing pressure roll, silicone rubber is preferable.

  That is, the elastomer porous body used in the present invention passes through an emulsion composition having a liquid rubber material that produces an elastomer as a continuous phase, specifically, a liquid rubber that is a continuous phase of the emulsion composition is converted into an emulsion. After curing into an elastomer matrix while maintaining the state, the dispersed phase is removed to form cells, and each cell is spherical and each exists substantially independently.

  Furthermore, the elastomer composition used in the present invention has a large number of very fine cells densely. Therefore, the number of cells per unit area is greatly different from that of a conventional porous body formed by chemical foaming or the like having the same porosity. The porous elastomer used in the present invention has a porosity of, for example, 30% or more, preferably 40% or more, and the number of cells per square mm is 200 or more, preferably 1000 or more, more preferably 2000 or more. .

  As described above, the elastomer porous body used in the present invention is formed via the emulsion composition, but it is further substantially eliminated by eliminating the cells caused by the bubbles embraced in the emulsion composition. It becomes an elastomer porous body having only true spherical cells. From this point of view, when preparing the emulsion composition, it is preferable that only the cells formed by removing the dispersed phase by removing the bubbles contained in the emulsion composition, preferably by reducing the pressure. The porous body has a substantially spherical cell.

  Here, FIG. 1 shows a longitudinal section and a transverse section of an example of the fixing pressure roll of the present invention. As shown in FIG. 1, a fixing pressure roll 10 of the present invention includes a metal core body (core metal) 11, a rubber layer 12 provided around the core body 11, and a rubber layer 12 provided on the rubber layer 12. And the elastic layer 13 made of such a porous elastomer as described above.

  As shown in FIG. 2, the elastic layer 13 has a core body 11 provided with a rubber layer 12 set in a mold 21, and a precursor (emulsion composition) 13A of an elastomer porous body is injected around it. In the state where the components of the emulsion composition are not volatilized, the primary heating is performed for curing, and then the secondary heating is performed for complete curing while performing liquid removal treatment. As a result, the elastic layer 13 is formed that is in good close contact with and adhered to the rubber layer 12.

  Here, the rubber layer 12 is a non-foamed rubber layer and functions as an adhesive with the elastic layer 13. Therefore, the same kind of rubber as the rubber material constituting the elastomer porous body, preferably one having a function as an adhesive is preferable. Therefore, when the elastomer porous body is made of silicone rubber, it is preferably formed of liquid silicone rubber or silicone rubber adhesive. Of course, the rubber layer 12 and the elastic layer 13 may be formed of different materials.

  The rubber layer 12 is preferably provided as thin as possible, and has a thickness of 1.0 mm or less, preferably 0.5 mm or less. Further, the rubber layer 12 needs to have a thickness that can eliminate the influence of the core 11 as a base, particularly the influence of the core 11 when it is made of metal. The thickness is 001 mm or more, preferably 0.005 mm or more.

  When the thickness of the rubber layer 12 is T1 and the thickness T2 of the elastic layer 13, the ratio (T1 / T2) between the two is 0.0001 to 0.25, preferably 0.002 to 0.15. Is preferred. This is because the rubber layer 12 eliminates the influence of polar groups on the surface of the core body 11 when the elastic layer 13 made of the elastomer porous body is formed from the precursor, and the emulsion of the emulsion composition as the precursor is removed. It exists stably in the process of becoming an elastomer porous body, and in the elastic layer 13 after heat curing, the cell shape near the rubber layer 12 and the surface of the elastic layer 13 can be made as uniform as possible.

  This is because even if a silane coupling agent is applied to the surface of the metal core as an adhesive layer so as to have a thickness of 1 μm to 10 μm, the exposure of the metal surface cannot be completely eliminated, and it is arranged near the core. May destroy the structure of the resulting emulsion composition. In addition, the rubber layer 12 and the elastic layer are based on the knowledge that when the coating is applied to have a thickness of about 50 to 100 μm in order to suppress exposure, the adhesive layer breaks due to shear stress during compression. As a result of various observations of the cell uniformity in the thickness direction of the elastic layer 13 formed by changing the thickness of the elastic layer 13, the ratio (T1 / T2) of both is 0.0001. It has been found that it is preferably ˜0.25, preferably 0.002˜0.15.

  Further, it is preferable that the rubber layer 12 is not completely cured before the elastic layer 13 is provided, and the rubber layer 12 is completely cured simultaneously when the elastic layer 13 is subjected to secondary heating. Thereby, the adhesiveness of the rubber layer 12 and the elastic layer 13 can further be improved. However, since the rubber layer 12 needs to keep its shape when the elastic layer 13 is molded with a mold, in the case of liquid silicone rubber, the reaction rate such as crosslinking density and degree of crosslinking is 60%. As mentioned above, it is preferable to make it about 80% or less. Of course, the elastic layer 13 may be provided after the elastic layer 13 is completely cured and then applied with a primer or an adhesive.

  In addition, you may provide the tube and coating layer which consist of fluororesins, such as PFA, a silicone rubber, etc. on the surface of the elastic layer 13 as needed. Further, when the tube is provided, it may be covered on the elastic layer 13, but the elastic layer 13 is formed between the rubber layer 12 and the tube by being disposed in the mold 21 in the manufacturing process described above. It may be.

  Here, the elastomer porous body used in the present invention and the method for producing the same will be further described taking a silicone elastomer porous body as an example.

  The silicone elastomer porous body is basically produced from a liquid silicone rubber material which is cured to produce a silicone elastomer, and a water-in-oil emulsion containing water containing water or an aqueous solvent such as alcohol as a dispersed phase. be able to. At this time, the liquid silicone rubber material, preferably a liquid silicone rubber material having a low viscosity, and water are sufficiently stirred under reduced pressure to form an emulsion, which can be heated and cured immediately thereafter. However, the porous silicone elastomer of the present invention is produced by producing, under reduced pressure, 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. It can be suitably manufactured via this.

  The liquid silicone rubber material 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.

  Here, when the liquid rubber material is other than silicone, the liquid rubber material is used as a continuous phase, and a solvent that is phase-separated from the continuous phase is used as a dispersed phase. An emulsion composition may be prepared by adding substances to form an emulsion.

  The elastomer porous body has substantially true spherical cells as described above, but in order to produce this, it is necessary to prepare an emulsion composition under reduced pressure. Here, preparing an emulsion composition under reduced pressure means performing a process of mixing and stirring the raw materials into an emulsion under reduced pressure, and adding a step of degassing the prepared emulsion composition under reduced pressure. Even that is not enough.

  Commercially available liquid silicone rubber materials can be used. For example, the addition reaction curable liquid silicone rubber is provided in separate packages for the polysiloxane having an unsaturated aliphatic group and the active hydrogen-containing polysiloxane, which are necessary for curing both of which will be described in detail later. The catalyst is added to a polysiloxane having unsaturated aliphatic groups. 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.

  Needless to say, water is present in the water-in-oil emulsion dispersed as a discontinuous phase (dispersed 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 (bubble) diameter of the porous silicone elastomer of the present invention.

  In the water-in-oil emulsion, the silicone oil material having a surface active action is used in a proportion of 0.2 to 10 parts by weight and water in a proportion of 10 to 250 parts by weight with respect to 100 parts by weight of the liquid silicone rubber material. Is preferable 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. Needless to say, two or more kinds of silicone oil materials having a surface active action may be used in combination.

  Here, when the liquid rubber material is other than silicone, the emulsion composition uses a liquid rubber material as a continuous phase and a solvent that phase-separates from the continuous phase as a dispersed phase. An emulsion composition may be obtained by adding a substance having the above to an emulsion.

  Moreover, the 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.).

  The emulsion composition used in the present invention can be produced by various methods. Taking a water-in-oil emulsion composition containing a silicone elastomer as an example, in general, a liquid silicone rubber material, a silicone oil material having a surface-active action, and water are reduced in pressure with further additives as necessary. Produced by mixing under stirring and stirring well. Here, the decompression condition is, for example, −30 kPa or less, preferably −60 kPa or less. Instead of mixing and stirring under reduced pressure, each raw material may be degassed in advance and then stirred in a state where it does not come into contact with a gas such as air to form an emulsion.

  In order to produce an elastomer porous body using an emulsion composition, if necessary, curing is performed by primary heating in the presence of a curing catalyst without causing the components of the emulsion composition to volatilize. Subsequent heating is performed to completely cure while dehydrating.

  In order to produce a silicone elastomer porous body, the emulsion composition is first heated primarily. 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. Secondary heating is performed to remove moisture from the cured silicone rubber containing the water particles. 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, the elastomer porous body used in the present invention can be produced from the emulsion composition without accompanying a foaming phenomenon such as chemical foaming. The dispersed phase such as water particles in the emulsion composition is trapped in the cured elastomer by primary heating, and simply volatilizes during secondary heating.

  Here, the usage mode of the fixing pressure roll 10 described above will be exemplified below.

  FIG. 3A shows an example in which the fixing pressure roll of the present invention is used as the pressure roll 10A used in a state of being pressed by a fixing belt 32 having a pressing member 31 containing a heater therein. .

  FIG. 3B shows an example in which the fixing pressure roll of the present invention is used as the pressure roll 10 </ b> B used in a state of being pressed by the fixing belt 32 including the heater 34 separately from the pressing member 33.

  FIG. 4A shows an example in which a fixing roll 10C with a built-in heater is disposed inside the fixing belt 32. The fixing pressure roll of the present invention can also be used as such a fixing roll 10C. The fixing pressure roll of the present invention can also be used as the pressure roll 10D pressed against the fixing roll 10C via the fixing belt 32.

  In FIG. 4B, an inner roll 10E and a halogen heater 36 incorporating a heater 35 are arranged inside the fixing belt 32, and a pressure roll 10F pressed against the inner roll 10E via the fixing belt 32 is provided. The fixing pressure roll of the present invention can be used as the inner roll 10E and the pressure roll 10F.

  FIG. 5 shows an example in which a fixing roll 10H having a halogen heater 36 built therein is disposed facing the pressure roll 10G, and the fixing pressure roll of the present invention is used as the pressure roll 10G and the fixing roll 10H. it can.

(Preparation of emulsion composition)
In a vacuum stirrer (at a reduced pressure of −60 kPa), 5 parts by weight of filler and 5 parts by weight of surface-active silicone oil are added to 100 parts by weight of the liquid silicone rubber material. Got. Next, the mixture was stirred while gradually adding 140 parts by weight of water to prepare a water-in-oil emulsion composition.

Example 1
A methyl vinyl silicone-based liquid silicone rubber is placed on the surface of a metal core having a diameter of 20 mm so as to have a thickness of 0.005 mm and cured to such an extent that the shape can be maintained. The emulsion described above was poured and heated (primary heating) at a preset temperature of 130 ° C. for 40 minutes to form. The obtained molded body (porous body precursor) was heated in an electric furnace at 200 ° C. for 6 hours (secondary heating) to remove water. Thereafter, polishing was performed to obtain a roll having an outer diameter of 40 mm and a hardness (Asker C) of 20 °.

(Example 2)
A roll of Example 2 was obtained in the same manner as in Example 1 except that the thickness of the rubber layer provided on the surface of the metal core having a diameter of 20 mm was changed to 0.5 mm.

(Comparative Example 1)
A roll of Comparative Example 1 was obtained in the same manner as in Example 1 except that a silane coupling agent was provided at a thickness of 0.005 mm on the surface of a metal core having a diameter of 20 mm.

(Comparative Example 2)
A roll of Comparative Example 2 was obtained in the same manner as in Example 1 except that the surface of a metal core having a diameter of 20 mm was provided with a silane coupling agent having a thickness of 0.05 mm.

(Test Example 1)
The rolls of Examples 1 and 2 and Comparative Examples 1 and 2 were used as pressure rolls pressed against a fixing roll having an outer diameter of 40 mm and containing a halogen lamp so that the compression rate was 50% (see FIG. 5). ), The fixing roll was rotated at a temperature of 180 ° C., and the time until the pressure roll was broken was measured.

  As a result, the pressure rolls of Comparative Examples 1 and 2 were broken in 500 hours, but the pressure rolls of Examples 1 and 2 were not broken even when driven for 2000 hours. Therefore, it was found that the pressure rolls of Examples 1 and 2 had durability four times or more as compared with Comparative Examples 1 and 2.

DESCRIPTION OF SYMBOLS 10 Fixing pressure roll 11 Core body 12 Rubber layer 13 Elastic layer 21 Mold 31, 33 Pressing member 32 Fixing belt 34, 35 Heater 36 Halogen heater

Claims (3)

Curing of an emulsion composition having a core, a rubber layer having a thickness of 0.005 mm to 0.5 mm provided around the core, and a liquid rubber material provided around the rubber layer as a continuous phase And an elastic layer made of an elastomer porous body, and the ratio of the rubber layer (T1 / T2) when the thickness of the rubber layer is T1 and the thickness of the elastic layer is T2 is 0.002 A fixing pressure roll characterized by being 0.15 .   The fixing pressure roll according to claim 1, wherein the liquid rubber material is a liquid silicone rubber material.   The fixing pressure roll according to claim 1 or 2, wherein the emulsion composition comprises a W / O type emulsion.

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