JP2005284152A - Oil applying roller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an oil applying roller which is stably usable over a more longer period. <P>SOLUTION: The roller is provided with an oil holding/supplying layer (14) formed so as to cover the outer peripheral surface of a core bar (12), and constituted of a porous elastic body not substantially presenting a swelling property to offset preventing oil in using. The porous elastic body is fixed on the core bar (12) while being compressed with a compressibility of ≥17% along the longitudinal axis of the core bar (12). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an oil application roller used in a fixing unit of an electrophotographic image forming apparatus such as a copying machine, a facsimile machine, or a laser beam printer.

  An electrophotographic image forming apparatus basically includes an electrostatic latent image forming unit for exposing a photosensitive drum based on predetermined image information to form an electrostatic latent image on the photosensitive drum, and an electrostatic latent image forming unit on the photosensitive drum. A developing unit for forming a toner image (visible image) corresponding to the electrostatic latent image by supplying and adhering toner from the developing roller to the formed electrostatic latent image, and a toner image formed on the photosensitive drum A transfer unit for transferring the toner image onto the recording paper, and a fixing unit for firmly fixing the toner image transferred onto the recording paper to the recording paper.

  In the fixing unit, pressure and heat energy are applied to the toner image via a fixing roller, a fixing belt, or the like on a recording paper carrying an unfixed toner image. The toner of the toner image becomes a semi-molten state as energy is applied, and penetrates into the recording paper to complete fixing. Since the toner used for fixing is sticky, an anti-offset oil (for example, silicone oil) is applied from the oil application roller to the surface of the fixing roller or fixing belt in contact with the toner in order to prevent offset. Is done. Such an oil application roller is required to be capable of stably applying a small amount of offset prevention oil (usually in the range of 0.05 to 2 mg / A4 paper) over a long period of time.

As an oil application roller that satisfies this requirement, Patent Document 1 discloses a porous elastic body that does not substantially swell the oil holding / supply layer for holding / supplying the offset preventing oil with respect to the offset preventing oil, for example, porous. An oil application roller is disclosed which is made of melamine resin, impregnated with a curable oil retaining material together with an offset preventing oil, and then cured with the curable oil retaining material.
JP 2001-5323 A

  However, it was found that the strength of the porous elastic body of the coating roller described in Patent Document 1 is not high enough to withstand long-term use.

  Then, an object of this invention is to provide the oil application roller which shows the high intensity | strength which can be used stably over a long period of time.

  According to the present invention, an oil holding / supply layer comprising a cored bar and a porous elastic body which is formed so as to cover the outer peripheral surface of the cored bar and does not substantially swell with respect to the offset preventing oil to be used. The porous elastic body is compressed at a compression rate of 17% or more along the longitudinal axis of the core metal and is fixed to the core metal. .

  The oil application roller of the present invention can be used stably over a long period of time because the strength of the porous elastic body constituting the oil holding / supply layer is high.

  Hereinafter, the present invention will be described in more detail.

  FIG. 1 schematically shows a cross section of an oil application roller according to an embodiment of the present invention.

  As shown in FIG. 1, the oil application roller 10 of the present invention is basically provided with a cylindrical cored bar (roller body) 12 and a cylindrical surface of the cored bar 12 substantially covering the entire surface. An oil holding / supply layer 14 is provided. The cored bar 12 can be made of a metal such as iron.

  The oil holding / supplying layer 14 constitutes the outermost layer of the oil application roller of the present invention, and is composed of an open-celled porous elastic body that does not substantially swell with respect to the offset preventing oil used. . That is, the non-swellable porous elastic body does not substantially increase its volume even when the oil retention / supply layer 14 is fully impregnated with the anti-offset oil to be used. In this case, the degree of volume increase is preferably 5% or less. The oil retention / supply layer 14 may have a foaming ratio of 90 to 100 times. The porous elastic body is an elastic body having rubber-like elasticity as defined on page 29 of JIS Handbook 19 Rubber 1997. The thickness of the oil retaining / supply layer 14 is preferably in the range of 1 mm to 25 mm.

  As the porous elastic body constituting the oil retaining / supplying layer 14, a porous melamine resin is particularly preferable. The porous melamine resin is produced, for example, under the trade name of BASOTECT (registered trademark) from BASF and is commercially available from Duraron Co., Ltd. under the trade name of duramin.

The porous elastic body constituting the oil retaining / supplying layer 14 of the present invention is compressed at a compression rate of 17% or more along the longitudinal axis of the cored bar 12. Here, the compression ratio (CR) is expressed by the formula:
CR = {(X−Y) / X} × 100 (1)
(In Expression (1), X is the axial length of the core metal of the porous elastic body before compression; Y is the axial length of the core metal of the porous elastic body after compression) It is. When the compressibility of the porous elastic body is less than 17%, no significant difference is observed in strength compared to the case where compression is not performed.

  By the way, when the porous elastic body used in the present invention is compressed, it has been found that the impregnation capacity is higher than that before compression, and more of the anti-offset oil / curable oil retaining material can be impregnated. In particular, when the compression ratio exceeds 70%, the amount of impregnation becomes almost constant.

  However, the oil holding / supplying layer made of the porous elastic body used in the present invention has a tendency that the outer peripheral end protrudes outward with respect to the inner peripheral end due to the restoring force as the compressibility is higher (end). Part deformation). When it is desired to suppress the end deformation of the oil retaining / supply layer, it is preferable to set the compression rate to 70% or less.

  In order to attach the compressed porous body to the cored bar 12, a through hole for inserting the cored bar 12 is provided in the block of the porous elastic body, the cored bar 12 coated with an adhesive is inserted, and the porous The elastic elastic body block can be compressed along the longitudinal axis of the core metal 12, and the compressed state can be maintained until the porous elastic body block is fixed to the core metal 12. Thereafter, the porous elastic body block can be polished to form the outer circumferential surface.

  After polishing, the compressed porous elastic body is impregnated with a mixture of an offset preventing oil and a curable oil retaining material, and the curable oil retaining material is cured. This impregnation and curing can be performed by the technique disclosed in Japanese Patent Application Laid-Open No. 2001-5323. Briefly, the anti-offset oil and curable oil retaining material to be used are usually an anti-offset oil such as dimethyl silicone oil and a curable oil retaining material such as liquid silicone rubber or one-part silicone rubber, preferably in the initial stage. The weight ratio (that is, the weight ratio when impregnating the oil holding / supply layer 14 to produce the oil application roller) is about 1: 1 to 20: 1, more preferably about 5: 1 to about 10: The mixture is mixed within the range of 1, and the mixture is impregnated into the oil holding / supplying layer 14 made of a compressed porous elastic body by dipping, brushing or the like, and then the curable oil holding material is cured according to the curing conditions. Let When the curable oil retaining material is cured, a reticulated crosslinked structure is formed, and the amount of oil discharged is regulated by the network structure, and it is considered that a constant application amount (discharge amount) can be exhibited. Further, since the oil holding / supply layer 14 does not substantially swell due to the offset prevention oil, the outer diameter does not change even if the oil is discharged during use, and the oil holding / supply layer 14 is not A predetermined nip width can be secured between them, and the oil application roller of the present invention can stably apply a small amount of offset prevention oil over a long period of time.

  As disclosed in Japanese Patent Laid-Open No. 2001-5323, the pores on the surface due to the oil retaining / supply layer 14 being porous are filled, and the surface of the oil retaining / supply layer 14 is smoothed. Therefore, a surface layer (not shown) can be provided on the outer surface of the oil retaining / supplying layer 14. This surface layer may have a thickness of 20 to 300 μm, for example.

  The oil application roller of the present invention can be used as an oil application roller for a fixing roller or a fixing belt in a fixing unit of an electrophotographic image forming apparatus such as an electrophotographic facsimile machine or an electrophotographic printer.

  Hereinafter, the present invention will be described by way of specific examples, but the present invention is not limited thereto.

Examples 1 to 6
Examples 1 to 6 indicate whether there is a difference in the strength of the porous elastic body between when the porous elastic body is impregnated with the mixture of the offset prevention oil and the curable oil retaining material and when the porous elastic body is not impregnated. This is a test conducted to confirm.

  As a sample, a block made of porous melamine resin (BASOTECT (registered trademark) manufactured by BASF) compressed at a compression rate shown in Table 1 and having a size of 3.5 cm in length, 3.5 cm in width, and 2 cm in height was used. Each porous melamine resin block had a core metal having a diameter of 10 mm inserted in the center thereof, and the core metal was bonded with an adhesive (KE45 manufactured by Shin-Etsu Chemical Co., Ltd.). A slit having a width of 20 mm was inserted into the porous melamine resin block, and a square pipe cut to a width of 20 mm was bonded with an adhesive, and the outer frame was bonded so as to apply a uniform force. Three such samples ([1], [2], [3]) were prepared for each example. In addition, what is indicated as impregnated in Table 1 is after impregnation with a mixture of a curable liquid silicone rubber KE108 manufactured by Shin-Etsu Chemical Co., Ltd. and dimethyl silicone oil KF96-300 manufactured by Shin-Etsu Chemical Co., Ltd. in a weight ratio of 1:10. (Impregnation amount 20 g), liquid silicone rubber is cured.

In the measurement, after fixing the core metal to the torque gauge, the torque gauge was rotated, and the torque value (torque at break) when the porous melamine resin block broke was measured. The measuring instrument used was a TORQUE GAGE SGK (II) type manufactured by BESTTOOL KANON. From this torque value, the breaking strength (kg / cm ² ) BSPUA per unit area was calculated by the following formula.

BSPUA (kg / cm ² ) = BS ÷ A
Here, BS is the breaking strength between the cored bar and the porous melamine resin, and A is the surface area of the cored bar where the torque is applied (1 (cm) × circumferential ratio (π) × 2 (cm) = 6.26 cm ² ).
BS = torque at break / core radius (0.5 cm).

  In all samples, all fractures occurred in the porous melamine resin.

The results are shown in Table 1.

  From the results shown in Table 1, there is no significant difference in the strength of the porous elastic body between when the porous elastic body is impregnated with the mixture of the offset prevention oil and the curable oil retaining material and when the porous elastic body is not impregnated. confirmed.

Examples 7-10
Except having changed the compression rate of the used porous melamine resin block as shown in Table 2, the intensity | strength of the porous melamine resin block was measured like Example 1-6. In Examples 1-6, there is no significant difference in the strength of the porous elastic body between when the porous elastic body is impregnated with the mixture of the offset prevention oil and the curable oil retaining material and when the porous elastic body is not impregnated. As confirmed, in Examples 7-10, the porous melamine resin block was not impregnated with a mixture of anti-offset oil and curable oil retaining material.

  The results are also shown in Table 2. Table 2 also lists the results of Examples 1, 3, and 5.

The results shown in Table 2 are also shown in FIG.

  As can be seen from the results shown in Table 1 and FIG. 2, when the compressibility of the porous elastic body is 17% or more, the strength of the porous elastic body is significantly improved.

Examples 11-17
In order to investigate the influence of the compressibility of the porous elastic body on the oil impregnation amount, a sample was prepared by changing the compressibility of the porous melamine resin (BASOTECT (registered trademark) manufactured by BASF) as shown in Table 3. . Each sample had a porous melamine resin layer (core metal axial length 40 mm, outer diameter 25 mm) compressed at each compression rate around a core metal having an outer diameter of 10 mm. Two samples ([1] and [2]) were prepared for each case. Each sample was immersed in silicone oil (KF-96-100cs made by Shin-Etsu Chemical Co., Ltd.) for 1 hour, and the impregnation amount was calculated from the sample weight before and after the impregnation. The results are shown in Table 3.

  From the results shown in Table 3, the amount of impregnation increases as the compression rate increases up to 67%. However, when the compression rate is 67% or more, the amount of impregnation may be substantially constant regardless of the compression rate. Understand.

Examples 18-24
In order to investigate the influence of the compressibility on the end deformation of the porous elastic layer, each sample was prepared in the same manner as in Examples 11 to 17, and the deformation amount of the end was examined. That is, after preparing the sample, it is left for a day. At that time, as shown in FIG. 3, the length A from the inner ends of the porous elastic body 32 provided around the cored bar 31 to the outer ends. , B was measured. The results are shown in Table 4.

  From the results shown in Table 4, it can be seen that the end deformation can be significantly suppressed when the compression ratio is 67% or less.

The schematic sectional drawing of the oil application roller which concerns on one aspect of this invention. The graph which shows the relationship between the compressibility and intensity | strength of a porous elastic body. The figure which shows the edge part deformation | transformation of a porous elastic body.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Oil application roller 12 ... Core metal 14 ... Oil retention and supply layer

Claims (4)

  Comprising a cored bar and an oil retaining / supplying layer formed of a porous elastic body which is formed so as to cover the outer peripheral surface of the cored bar and does not substantially swell with the offset preventing oil to be used. An oil application roller, wherein the elastic body is compressed at a compression rate of 17% or more along the longitudinal axis of the core bar and fixed to the core bar.   2. The oil application roller according to claim 1, wherein a compression ratio of the porous elastic body along a longitudinal axis of the cored bar is 70% or less.   The oil application roller according to claim 1, wherein the porous elastic body is made of a porous melamine resin.   4. The oil retaining / supply layer is impregnated with a mixture containing an offset preventing oil and a curable oil retaining material, and the curable oil retaining material is cured. The oil application roller according to claim 1.

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