JP2007011407A - Silicone rubber roller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a silicone rubber roller which is used in a heat-pressure fixing device composed of a fixing member, a pressure member and an oil application means for applying dimethylsilicone oil as a release oil, and which can prevent offset of toner, has a long release lifetime and ensures less roller scuffing. <P>SOLUTION: The silicone rubber roller is surfaced with dimethylsilicone rubber having a storage modulus E' in a range of >1.0×10<SP>6</SP>to <1.5×10<SP>7</SP>dyn/cm<SP>2</SP>and a loss modulus E" in a range of >1.0×10<SP>5</SP>to <7.5×10<SP>5</SP>dyn/cm<SP>2</SP>and containing ferric chloride. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a silicone rubber roller used in an electrophotographic image forming apparatus such as a copying machine or a laser beam printer.

  An electrophotographic image forming apparatus such as a copying machine or a laser beam printer has a fixing device for fixing toner as a permanent image on a recording sheet. The fixing device generally has a configuration in which a pressure is applied between a pair of heating members such as heated rollers and rollers, a film and rollers, and a belt and rollers and a pressure member. The recording sheet on which the unfixed toner image is formed passes between the heated and pressurized members, so that the toner is fixed on the recording sheet as a permanent image. As the recording sheet, paper or an OHP transparency sheet is generally used. Such an apparatus for fixing toner as a permanent image is generally called a heat and pressure fixing apparatus, a heat fixing apparatus, a toner fixing apparatus or the like, or simply a fixing apparatus.

  Among the heat and pressure fixing devices, those in which the pair of heating and pressure members are both rollers are called roller-type heat and pressure fixing devices or roller fixing devices. In the heat and pressure fixing device, the member that is in direct contact with the unfixed toner image is called a fixing member, and the other member is called a pressure member.

  The outermost layer of the fixing member and the pressure member of the heat and pressure fixing device is called a surface layer. Since the surface layer is in direct contact with the toner image and the recording sheet, the function and performance of the surface layer greatly affect the image quality of the permanent image.

  Among the functions and performance required for the surface layer, one of the most important is toner releasability. Toner releasability refers to the difficulty of toner adhesion to the surface layer. The adhesion of toner from an unfixed toner image to the surface layer is generally called toner offset or simply offset.

  For example, if the toner releasability on the surface layer of the fixing roller is poor, that is, if the toner is likely to adhere to the surface layer, a toner offset occurs from the unfixed toner image, and toner omission occurs in the permanent image. Worsen. Further, the offset toner is fixed to the next unfixed toner image, which causes toner contamination and an image defect called an offset image. Further, toner offset causes a problem that, when there is a part in contact with the fixing roller, the offset toner is fixed to the contact part, and the surface layer is damaged or the function of the part is impaired. Cause.

  Furthermore, when the toner releasability of the surface layer of the pressure member is poor, there may be a problem when performing double-sided image formation. In this double-sided image formation, the heated and pressure-fixed recording sheet on which the image on the first side is formed is reversed so that an image can be formed on the second side automatically or manually, and the toner image on the second side is recorded. Generally, it is formed on a sheet, and then heat-press fixing is performed again. For this reason, when the second-surface toner image is fixed, the already-fixed first-surface permanent image is in contact with the surface layer of the pressure member. Problems such as deterioration and winding of the recording sheet around the pressure member occur.

  In particular, full-color image forming apparatuses such as full-color copying machines and full-color laser beam printers require a particularly high toner releasability on the surface layer as compared to monochrome image forming apparatuses. This is because in a full-color image forming apparatus, a multi-color toner forms two to four layers, so that the toner used has good meltability and color mixing when heated. This is because a sharp melt toner having a low softening point and a low melt viscosity is used. Such a toner is called a sharp melt color toner, a sharp melt toner, or simply a color toner.

  In order to solve the above-described problems, it is common to use a material having good toner releasability and excellent wear resistance and heat resistance, such as fluororesin or silicone rubber, for the surface layer of the fixing member. Is.

  Especially in heat and pressure fixing devices of color copiers, they are used under severe conditions where toner releasability on the surface of the fixing member deteriorates due to demands for higher image quality such as improved color reproducibility. Therefore, a silicone rubber having particularly excellent toner releasability tends to be used for the surface layer.

  Also, in an electrophotographic image forming apparatus other than a color copying machine, when importance is attached to improvement in toner releasability, silicone rubber is preferably used for the surface layer of the fixing member for the same reason as described above.

  In the invention relating to the surface layer of the conventional fixing member, there are some that aim to improve the toner releasability, wear resistance and heat resistance.

  According to Japanese Patent Laid-Open No. 05-214250, for example, a branched organopolysiloxane is blended as a silicone rubber reinforcing material and used as a surface layer of a fixing member, thereby improving toner releasability and physical strength. I am trying.

  According to Japanese Patent Application Laid-Open No. 07-311508, the surface layer of the fixing member is made of, for example, addition-type dimethyl silicone rubber containing branched dimethylpolysiloxane and inorganic fine powder, so that further physical strength and toner releasability can be obtained. We are trying to achieve both.

However, when these materials are used in the surface layer of a fixing member in a color copying machine, the heat and pressure fixing device is uniformly coated with a release oil on the surface layer in order to ensure toner releasability. Means are essential. In general, when the surface layer is made of the dimethyl silicone rubber as described above, dimethyl silicone having a viscosity at 25 ° C. of 100 to 1000 cS is used as the release oil. Further, in the heat and pressure fixing device using the fixing member whose surface layer is the dimethyl silicone rubber, the amount of oil applied to the surface of the release oil is 40 mg / 621 cm ² (to ensure the toner release property). A4 or more) is necessary.

  On the other hand, the application of such release oil includes a problem that the oil stickiness of the sheet, particularly in the copy of the OHP film sheet. When the application amount of the release oil is 40 mg or more as in the above-described heat and pressure fixing device, the oil stickiness of the OHP film sheet is remarkably confirmed, which may cause a practical problem. In order to solve this stickiness problem, it is essential to reduce the amount of release oil applied, and the toner releasability of the surface layer of the fixing roller under such a small amount of release oil application conditions as before. Is required.

  An object of the present invention is to provide a silicone rubber roller excellent in toner releasability and long-term stability of physical strength.

The silicone rubber roller according to the present invention has a storage elastic modulus E ′ in a range larger than 1.0 × 10 ⁶ dyn / cm ^{2 and} smaller than 1.5 × 10 ⁷ dyn / cm ² and a loss elastic modulus E ″ of 1 It is in a range larger than 0.0 × 10 ⁵ dyn / cm ^{2 and} smaller than 7.5 × 10 ⁵ dyn / cm ² , and has a dimethyl silicone rubber containing ferric chloride as a surface layer. is there.

  The fact that the silicone rubber roller according to the present invention can maintain good toner releasability for a long period of time under a low coating amount of dimethyl silicone oil will be explained as follows.

  The inventors paid attention to the correlation between the toner releasability of the dimethyl silicone rubber on the surface layer of the fixing member and the dynamic viscoelasticity. First, toner releasability is separated into two factors: initial releasability that indicates toner releasability of unused surface layers, and release rate that indicates the rate of decrease in toner releasability for each surface layer use. did. Next, the dynamic viscoelasticity of the surface layer was separated into two factors: a storage elastic modulus E ′ indicating an elastic term and a loss elastic modulus E ″ indicating a viscous term. The correlation between these four factors was analyzed, and as a result, there was a tendency for the mold release rate to decrease by decreasing the storage elastic modulus, and the initial mold release by decreasing the loss elastic modulus. In this case, if it is defined that the release life is the life until the offset image is generated, the initial release property is increased and the release rate is reduced. Since the release life becomes longer by making it smaller, the knowledge that the release life becomes synergistically longer by reducing the storage elastic modulus and the loss elastic modulus can be obtained. Excellent dimethyl series Which means that it is possible to obtain a Ngomu.

Based on the knowledge of toner releasability as described above, when the coating amount of dimethyl silicone oil as a release oil is 1 mg to 20 mg / A4, the storage elastic modulus of the dimethyl silicone rubber as the surface layer is 1.5. It has been found that by making it smaller than × 10 ⁷ dyn / cm ² , a dimethyl silicone rubber exhibiting a long release life and excellent toner release properties can be obtained. On the other hand, when the loss elastic modulus is smaller than 7.5 × 10 ⁵ dyn / cm ² , a long release life is exhibited. It was found that a dimethyl silicone rubber excellent in toner releasability can be obtained.

Further, from the viewpoint of physical strength, the storage elastic modulus and the loss elastic modulus must be used at a value larger than a certain lower limit value. That is, in the case of dimethyl silicone rubber, the surface layer is dimethyl silicone rubber having a storage elastic modulus larger than 1 × 10 ⁶ dyn / cm ² and a loss elastic modulus larger than 1.0 × 10 ⁵ dyn / cm 2. I found out.

Based on the above knowledge, an apparatus for heat-pressing and fixing an image, and in the heat-pressure fixing apparatus having at least a fixing member and means for applying release oil to the fixing member, the release oil is dimethyl silicone oil. The coating amount is 1 to 20 mg / A4 (621 cm ² ), and at least the surface layer of the fixing member is dimethyl silicone rubber, and the storage elastic modulus E ′ of the dimethyl silicone rubber at 170 ° C. is represented by the following formula:
1 × 10 ⁶ dyn / cm ² <E ′ <1.5 × 10 ⁷ dyn / cm ²
And the loss elastic modulus E ″ at 170 ° C. is
1.0 × 10 ⁵ dyn / cm ² <E ″ <7.5 × 10 ⁵ dyn / cm ²
By using a heat and pressure fixing device characterized by being in the range of the above, a release oil amount that is small enough to reduce the oil stickiness of the OHP transparency sheet can be realized, and a release amount that is so low. Therefore, it is possible to provide a heat and pressure fixing device including a fixing member having a surface layer capable of exhibiting excellent toner releasability even when the amount of the mold oil is applied.

The dimethyl silicone rubber forming at least the surface of the fixing member used in the fixing device according to the present invention is preferably produced by addition polymerization of an addition type liquid silicone rubber, and an addition type liquid silicone rubber having the following composition is suitable. is there.
(A) (a) 50 to 70% by weight of an organopolysiloxane having two or more vinyl groups in one molecule and having a branched polysiloxane segment, and (b) a viscosity at 25 ° C. of 10,000 Pa · s or more. A polysiloxane mixture containing 30 to 50% by weight of linear polydimethylsiloxane having vinyl groups at both ends,
(B) an organopolysiloxane having two or more silicon-bonded hydrogen atoms in one molecule;
(C) a platinum-based catalyst, and ferric chloride in an amount sufficient to be 3 to 300 ppm on the iron component basis with respect to the total amount of (D) (A) + (B) + (C),
(A) The organopolysiloxane of component (a) increases physical strength.
(A) (b) component linear polydimethylsiloxane improves toner releasability. In the mixture of (A) (a) component and (A) (b) component, the proportion of (A) (b) component Is 30% by weight or more for improving toner releasability, and 50% or less for preventing physical strength from being lowered. Further, when the viscosity of the components (A) and (b) at 25 ° C. is 10000 Pa · s or more, the toner releasability is improved.
The organopolysiloxane of component (B) is a crosslinking agent for curing the mixture of component (A), and is blended in such an amount that the desired curing is sufficiently performed.
The platinum-based catalyst as the component (C) is a catalyst for subjecting the components (A) and (B) to an addition crosslinking reaction.
The ferric chloride component (D) is an effective component for obtaining dimethyl silicone rubber with little change in physical strength and little change in dynamic viscoelasticity in cured dimethyl silicone rubber. In order to properly exhibit the effect, 3 ppm or more is necessary, and the necessary upper limit is about 300 ppm or less.

In order to further improve toner releasability,
As the organopolysiloxane which is the component (A) (a), at least one branched polysiloxane segment having a vinyl group and a linear polysiloxane segment having at least 100 bifunctional siloxane units continuously, It is particularly preferable to use an organopolysiloxane having a viscosity of 1 Pa · s or more at 25 ° C.

The branched polysiloxane segment is preferably composed of a polysiloxane containing at least one of trifunctional and tetrafunctional siloxane units. Trifunctional siloxane units CH3SiO _3/2 and tetrafunctional siloxane units are SiO _2. The vinyl groups of the branched polysiloxane segment are (CH ₂ ═CH) (CH ₃ ) ₂ SiO _1/2 , (CH ₂ ═CH) (CH ₃ ) SiO and (CH ₂ ═CH) SiO _3/2. As vinyl group-containing siloxane units such as The branched polysiloxane segment may contain a bifunctional siloxane unit (CH ₃ ) ₂ SiO.

  The content of the organopolysiloxane having two or more silicon-bonded hydrogen atoms in one molecule as the component (B) is the total amount contained in the mixture of the components (A) (a) and (A) (b). With respect to the molar amount of the vinyl group, the molar amount of the hydrogen atom is 0.6 times or more from the viewpoint of increasing the hardness of the dimethyl silicone rubber, and 20 times or less from the viewpoint of improving heat resistance and strength. It is preferable to set so that.

  The platinum-based catalyst that is the component (C) is preferably 0.1 to 500 parts by weight as the platinum metal component with respect to 1 million parts by weight of the mixture of the components (A), (B), (C), and (D). It is. As the platinum catalyst, chloroplatinic acid, an alcohol solution of chloroplatinic acid, a complex of chloroplatinic acid and an olefin, a complex of chloroplatinic acid and vinylsiloxane, platinum-supported silica, platinum-supported activated carbon, or the like is used.

  In order to further improve the toner releasability, 5 to 20 parts by weight of dimethyl silicone oil is added to 100 parts by weight of the total amount of the above (A), (B), (C) and (D). Is also effective. Furthermore, by adding dimethyl silicone oil, the value of the storage elastic modulus can be reduced without greatly changing the value of the loss elastic modulus of the silicone rubber, and the degree of decrease in the storage elastic modulus can be controlled. . As a result, a silicone rubber having a desired viscoelastic value can be easily designed.

  The toner image is generally fixed by heating the toner image via a roller or a film as a fixing member by causing a current to flow through a halogen lamp or a heating resistor to generate heat. Alternatively, as described in JP-A-7-114276, an electromagnetic induction is used to generate eddy current in the conductive layer of the film having the conductive layer, and the resulting heat generates a toner image. Let it settle.

  As the pressure member for pressing the toner image against the fixing member, a roller, a belt, or the like that rotates or moves while pressing and holding a recording sheet carrying the toner image together with the fixing member is used.

  As an example of heat and pressure fixing according to the present invention using a fixing film as a fixing member, there is a fixing device using an endless film as a fixing device for shortening the warm-up time. This includes a heating body, a heat-resistant endless fixing film whose one surface slides on the heating body and the other surface moves in contact with the recording sheet, a suspension member around which the fixing film is wound, It has a heating member and a pressure member that forms a nip through a film. A recording sheet carrying an unfixed image is sandwiched and conveyed in the nip, and an unfixed image is recorded by heat from the heating member through the fixing film. A fixing device that heat-fixes on a sheet. In general, an elastic body pressure roller is disposed as the pressure member.

  As the heat-resistant endless fixing film, a film in which a dimethyl silicone rubber layer having a thickness of 100 to 300 μm is formed on a heat-resistant resin substrate such as polyimide having a thickness of 20 to 80 μm via a primer is used.

  When forming a toner image on both sides of the recording sheet, at least the surface of the pressure member is also formed of dimethyl silicone rubber used for the fixing member, in order to prevent toner offset to the pressure member. It is valid.

  Regarding the fixing member and the pressure member, when at least the surface of these members is formed of dimethyl silicone rubber defined in the present invention, these members have a multilayer structure, and the surface layer is the dimethyl silicone rubber layer. In some cases, the fixing member and the entire pressure member may be formed of the dimethyl silicone rubber.

  When the silicone rubber specified in the present invention is used as a fixing member or a pressure member, it is generally used in a thickness of 1 μm to 2 mm. Further, when the fixing member or the pressure member has a structure of two or more layers, the surface layer is made of silicone rubber and the lower layer is made of an elastic layer, the thickness of the surface layer is preferably 1 μm to 300 μm, In particular, 50 μm to 300 μm is preferable from the viewpoint of toner fixing properties and image quality.

  The fixing device according to the present invention is particularly effectively applied to fixing a toner image formed with three or more color toners. The color toner is required to have a sharp melt property in order to easily cause a melt color mixture between the toners.

  By using the sharp melt color toner, the color reproducibility of the permanent image can be improved, and a permanent image faithful to the multicolor or full color image of the original can be obtained. However, a decrease in cohesion between the molecules of the toner component polymer at the time of heat melting increases the adhesion to the surface layer, and a toner offset caused by excessive melting of the toner, commonly called high temperature offset, occurs. Therefore, the fixing device of the present invention, which is excellent in preventing offset by using a small amount of offset preventing silicone oil, is particularly effectively applied.

  Generally, there are the following sharp melt color toners.

  For example, color toners are manufactured by melt-kneading, pulverizing, and classifying toner forming materials such as binder resins such as polyester resins or styrene-acrylic ester resins, colorants (dyes, sublimation dyes), and charge control agents. The If necessary, an external addition step of adding various external additives (for example, hydrophobic colloidal silica) to the toner may be added. As such a color toner, a toner using a polyester resin as a binder resin is particularly preferable in consideration of fixability and sharp melt property. Examples of the sharp melt polyester resin include polymer compounds having an ester bond in the main chain of a molecule synthesized from a diol compound and a dicarboxylic acid. In particular, the following formula

(Wherein R is an ethylene or propylene group, x and y are each a positive integer of 1 or more, and the average value of x + y is 2 to 10) or a bisphenol derivative represented by Carboxylic acid component comprising a diol component and a divalent or higher carboxylic acid or its acid anhydride or its lower alkyl ester (for example, fumaric acid, maleic acid, maleic anhydride, phthalic acid, terephthalic acid, trimellitic acid, pyromellitic A polyester resin obtained by cocondensation polymerization with an acid or the like is more preferable because it has sharp melting characteristics.

  The softening point of the polyester resin is 75 to 150 ° C, preferably 80 to 120 ° C.

  An example of the softening characteristics of a sharp melt toner containing this polyester resin as a binder resin is shown in FIG. The measurement conditions are as follows.

Using a flow tester CFT-500A type (manufactured by Shimadzu Corporation), with a die (nozzle) diameter of 0.2 mm and a thickness of 1.0 mm, an extrusion load of 20 kg was applied, an initial setting temperature of 70 ° C., and a preheating time of 300 seconds, A toner plunger drop-temperature curve (hereinafter referred to as a softened S-shaped curve) drawn when the temperature was increased at a constant rate of 6 ° C./min was obtained. The toner used as a sample is a fine powder precisely weighed 1 to 3 g, and the plunger cross-sectional area is 1.0 cm ² . The softened S-shaped curve is as shown in FIG. As the temperature rises at a constant speed, the toner is gradually heated and starts to flow out (plunger lowering A → B). When the temperature further rises, the melted toner largely flows out (B → C → D), and the plunger lowering stops and ends (D → E).

The height H of the S-shaped curve indicates the total outflow amount, and the temperature T ₀ corresponding to the point C of H / 2 indicates the softening point of the toner.

  Whether the toner and the binder resin have a sharp melt name can be determined by measuring the apparent melt viscosity of the toner or the binder resin.

The toner or binder resin having such a sharp melt last name is T ₁ when the apparent melt viscosity shows 10 ³ poise, and T ₂ when the temperature shows 5 × 10 ² poise.
T ₁ = 90 to 150 ° C.
| ΔT | = | T ₁ −T ₂ | = 5 to 20 ° C.
Those that meet the conditions of

  The sharp melt resin having these temperature-melt viscosity characteristics is characterized in that the viscosity is lowered sharply when heated. Such a decrease in viscosity causes proper mixing of the uppermost toner layer and the lowermost toner layer, and further increases the transparency of the toner layer itself, thereby causing good subtractive color mixing. That is, the color reproducibility in the permanent image is improved.

  As described above, according to the present invention, in a heat and pressure fixing apparatus having at least a fixing member, a pressure member, and a release oil application means composed of dimethylsilicone oil, a small amount of release oil is applied. However, it is possible to provide a fixing device that can prevent toner offset, has a long release life, and is less likely to cause roller scratches.

  An image forming apparatus to which the present invention is applied will be specifically described.

  FIG. 2 is a schematic view showing an embodiment of the image forming apparatus of the present invention. The apparatus according to this aspect forms an image on both sides of the recording material by transporting the recording material on which the image has been fixed on the first surface again to the image forming unit and the fixing unit and executing image forming fixing on the second surface. An electrophotographic color image forming apparatus having a double-sided image forming function. It is also possible to use only single-sided image formation without performing double-sided image formation.

  In the figure, reference numeral 1 denotes an apparatus main body outer casing, and A denotes a document scanning / reading unit disposed at an upper portion of the apparatus main body outer casing. The original O is set on the original platen glass 2 with the image surface facing downward, based on a predetermined apparatus standard, and the original presser plate 3 is placed on the original O to start reading, thereby moving the optical system below the original platen glass. 4 is moved from one side to the other side along the lower surface of the platen glass, and the downward image surface of the set original on the platen glass 3 is illuminated and scanned. 5 is imaged and separated by a color separation filter, and each color separation component image of the original image is photoelectrically read as a color image signal (time-series electric digital pixel signal) and stored in a memory circuit.

  Reference numeral 6 denotes an electrophotographic photosensitive drum as an image carrier of the image forming unit. The photosensitive drum 6 has a diameter of 180 mm, for example, and is rotationally driven at a predetermined process speed (circumferential speed) in the clockwise direction indicated by an arrow. Reference numeral 7 denotes a charger for uniformly charging the photosensitive drum 6 to a predetermined polarity and potential. Reference numeral 8 denotes image exposure means including a laser output unit, a polygon mirror, a lens system, a mirror and the like. The surface of the photosensitive drum charged by the charger 7 is scanned and exposed by the laser beam E modulated and output from the image exposure means 8 in response to the time-series electric digital pixel signal from the memory circuit, thereby rotating the photosensitive drum. An electrostatic latent image corresponding to the scanning exposure pattern is formed on the six surfaces.

  A composite developing device 9 includes a cyan developing device 9C containing cyan toner, a magenta toner developing device 9M containing magenta toner, a yellow toner developing device 9Y containing yellow toner, and a black developing device 9K containing black toner. There are four developing devices, and these four developing devices 9C-9M-9Y-9K selectively act on the rotating photosensitive drum 6 to develop the electrostatic latent image on the surface of the rotating photosensitive drum 6 with toner. The

  Reference numeral 11 denotes a transfer drum which is in contact with the photosensitive drum 6 at the next position of the composite developing device 9 and is driven to rotate in the forward direction with the rotation of the photosensitive drum 6 at substantially the same peripheral speed as the photosensitive drum. The transfer drum 11 has a diameter of, for example, 180 mm, and a recording material carrying sheet 11a made of a film-like dielectric material serving as a recording material carrying means is integrally stretched in a cylindrical shape in the peripheral opening area. Further, an adsorption corona charger 11b as an adsorption charging means for adsorbing the recording material to the outer peripheral surface of the transfer drum 11, an adsorption (contact) roller 11C as the counter electrode, and a recording adsorbed on the transfer drum 11. A transfer corona charger 11d, an inner corona charger 11e, an outer corona charger 11f, a recording material separation charger 11g, a recording material separation claw 11h, etc. are provided for transferring the toner image on the photosensitive drum 6 side to the material. It is.

  Reference numerals 12, 13, and 14 denote first to third recording material automatic paper feeding mechanisms, and 15 denotes a recording material manual paper feeding unit. A recording material (transfer material) P is fed to one of the selected first to third recording material automatic paper feeding mechanisms 12, 13, and 14, and is a predetermined sheet made up of a guide plate / conveying roller pair, etc. It is conveyed to the registration roller pair 16 through the path. Alternatively, the recording material is manually conveyed from the manual paper feeding unit 15 to the registration roller pair 16.

  The recording material is fed to the transfer drum 11 at a predetermined timing by the registration roller pair 16, wound around the outer peripheral surface of the transfer drum 11, electrostatically held, and rotated and conveyed integrally with the transfer drum 11. The toner image on the photosensitive drum 6 side is transferred to the outer surface of the recording material by the transfer corona charger 11d. The surface of the rotating photosensitive drum 6 after the transfer of the toner image to the recording material P is cleaned by a cleaner (cleaning device) 10 after removal of residual deposits such as transfer residual toner.

  In the case of the full color image forming mode: Charging on the rotating photosensitive drum 6 → Image exposure E with laser light converted by the cyan image signal of the above-described color separation image signal of the target color image → Development by the cyan developing device 9C → Recording of the cyan toner image 1. Transfer to the material P → cleaning process of the rotating photosensitive drum 6. Charging on the rotating photosensitive drum 6 → Image exposure E with laser light modulated by the magenta image signal of the above-described color separation image signal of the target color image → Development by the magenta developer 9M → Recording material of the magenta toner image 2. transfer to P → rotating photosensitive drum 6 cleaning step; Charging of the rotating photosensitive drum 6 → Image exposure E with a laser beam modulated by a yellow image signal among the color separation image signals of the target color image → Development by the yellow developing unit 9Y → Recording material of the yellow toner image 3. transfer to P → rotating photosensitive drum 6 cleaning process; Charging on the rotating photosensitive drum 6 → Image exposure E with a laser beam modulated by the black image signal among the color separation image signals of the target color image → Development by the black developing device 9K → Recording material of the black toner image Transfer to P → cleaning process of rotating photosensitive drum 6, the rotation of the photosensitive drum 6 and the transfer drum 11 in the above four image forming / transfer cycles 1 to 4 is successively executed and rotated. Four toner images of the above-mentioned cyan toner image, magenta toner image, yellow image, and black toner image are positioned at predetermined positions relative to the outer surface (first surface) of the same recording material P that is wound around the drum 11. A color toner image corresponding to the target color image is formed on the recording material P by registration and registration. Formed is formed.

  When the transfer of the toner images for the four colors onto the same recording material P held on the rotary transfer drum 11 is completed, the recording material is neutralized by the separation charger 11g, and the transfer drum 11 is separated by a separation claw 11h as separation means. And is sent to a fixing device (in this example, a heat roller fixing device) 18 by a conveying means 17, where toner images for four colors are collectively fixed on a recording material surface.

  In the single-sided image forming mode, the recording material on which data has been formed and fixed on the fixing device 18 is discharged from the paper discharge port 19 to the paper discharge tray 20 outside the apparatus.

  In the double-sided image forming mode, the recording material on which the single-sided image is formed and fixed that has exited the fixing device 18 is introduced into the re-conveying sheet path a, and is reversed upside down through the path of the switchback sheet path b → sheet path c. To the intermediate tray 21. Then, the sheet is conveyed from the intermediate tray 21 to the registration roller pair 16 and is fed again to the transfer drum 11, and is wound around the transfer drum 11 so that the image-formed first surface side is inward and the second surface side is outward. Is done.

  Similar to the image formation on the first surface, the four color separation toner images of the color image for the second surface sequentially formed on the photosensitive drum 6 are transferred to the second surface of the recording material. A color toner image is synthesized and formed sequentially.

  Then, the recording material is separated from the transfer drum 11 and sent again to the fixing device 18 where the four color toner images formed on the second surface are fixed together, and the recording material on which the full-color double-sided image has been formed is discharged. The paper is discharged from the outlet 19 to the paper discharge tray 20.

  The recording material on which one side (first side) image is formed and fixed is once discharged to the paper discharge tray 20, the recording material is directed upward on the second side, and re-introduced from the manual paper feeding unit 15 to the apparatus. Image formation can also be executed.

  The order of forming the four color separation toner images is not limited to the order of this example. For black-and-white image copying, only the black developer 9K operates. A self-black image double-sided copy mode and an image forming mode in which one side of the recording material is a color image and the other side is a monochrome image can be selected and executed.

<Configuration of heat and pressure fixing device>
The heat and pressure fixing apparatus to which the present invention is applied will be described in detail.

  FIG. 3 is a sectional view of a heat and pressure fixing apparatus to which the present invention is actually applied. The fixing roller 100 and the pressure roller 102 are in pressure contact with each other to form a nip width of about 7 mm.

  In the fixing roller 101, an elastic layer 112 made of HTV (millable type) silicone rubber having a thickness of about 2 mm is formed on a cored bar 111 using aluminum or the like as a base material, and about 50 μm is formed on the elastic layer 112. An oil barrier layer 113 made of fluororubber having a thickness of approximately 200 μm is formed, and a surface layer 114 made of dimethyl silicone rubber having a thickness of about 200 μm is formed on the oil barrier layer 113. The fixing roller 101 is configured to have an outer diameter of about 60 mm.

  Similarly, in the pressure roller 102, an elastic layer 122 made of HTV (millable type) silicone rubber having a thickness of about 2 mm is formed on a cored bar 121 made of aluminum or the like as a base material. An oil barrier layer 123 made of fluorine rubber having a thickness of about 50 μm is formed thereon, and a surface layer 124 made of, for example, dimethyl silicone rubber having a thickness of about 200 μm is formed on the oil barrier layer 123. The pressure roller 102 is also configured to have an outer diameter of about 60 mm.

  The fixing roller 101 includes an oil application unit 103 for uniformly applying release oil, a cleaning web unit 4 for cleaning dirt such as toner adhering to the surface of the fixing roller 101, and a separation on the fixing roller 1. An elastic oil regulating blade 107 that regulates and controls the amount of mold oil is disposed so as to contact.

  The oil application unit 103 includes an oil pan 131 that holds the release oil 132, a metal oil pickup roller 133 that rotates to pump up the release oil 132, and the release oil 132 that has been pumped up to the surface of the fixing roller 1. And an elastic body oil application roller 134 that is applied while rotating, and an elastic body oil regulating blade 135 that regulates and controls the amount of release oil on the oil application roller 134.

  Dimethyl silicone oil was used as the release oil. As this dimethyl silicone oil, dimethyl silicone oil (trade name, KF-96SS, manufactured by Shin-Etsu Chemical Co., Ltd.) having a kinematic viscosity at 25 ° C. of 300 cSt (centistokes) was used.

  The cleaning web unit 104 includes a cleaning web 141 that is a nonwoven fabric for cleaning dirt such as toner, and an elastic web pressing roller 42 that presses the cleaning web 141 against the surface of the fixing roller. The cleaning web 141 is wound up little by little in the direction d.

  The pressing force of the elastic body oil regulating blade 107 can be arbitrarily changed by a spring (not shown) of the support body, thereby changing the amount of release oil applied to the surface of the surface layer 114 of the fixing roller 1. Can be made to.

  The pressure roller 102 is disposed so as to contact an elastic body oil removing blade 105 for removing excess release oil.

  A heater 106 is disposed at the center of the cores 111 and 121 on the fixing roller 101 and the pressure roller 102, and thermocouples (not shown) are disposed so as to contact the surfaces of the surface layers 114 and 124 of the respective rollers. The heater energization timing is controlled so that the surface temperature becomes a set value based on the temperature detected in (1). In this example, the set value was 170 ° C.

  In the heat and pressure fixing apparatus shown in FIG. 3, the fixing roller 101 rotates in the direction a, the pressure roller 102 rotates in the direction b, the paper P is conveyed in the direction c, and the unfixed toner T1 is The toner passes through the nip portion between the fixing roller 101 and the pressure roller 102 and becomes the fixing toner T2 to form an image.

<Method for manufacturing fixing member>
The fixing roller 101 as a fixing member was manufactured by the following method. First, heat resistant grade HTV silicone rubber (millable type) was vulcanized and bonded onto the core metal 111, and the desired outer diameter was obtained by polishing. Next, the fluororubber paint was spray-coated with a thickness of about 50 μm and dried at 150 ° C. for 30 minutes to obtain a fluororubber-coated roller. Next, on the fluororubber-coated roller that has been treated with a siloxane-based primer in advance, the uncured addition-type liquid silicone rubber is used as a surface layer. Then, it was cured by primary vulcanization at 130 ° C. for 1 hour, and then secondary vulcanized at 200 ° C. for 4 hours to obtain a fixing roller 101 coated with dimethyl silicone rubber having a thickness of 200 μm.

  The pressure roller 102 that is a pressure member was also manufactured by the same method as that for the fixing roller 101.

<Measurement method of oil application amount>
The amount of release oil applied to the surface layer 114 of the fixing roller 101 was measured as follows. First, the pressure roller 102 and the cleaning web unit 104 of the heat and pressure fixing apparatus shown in FIG. 3 are removed and heated by the heater 106 until the surface temperature of the fixing roller 101 reaches 170 ° C., and then the fixing roller 101 is rotated half a turn. Thereby, the release oil is applied to the half circumference of the surface of the fixing roller. Thereafter, a general-purpose quantitative filter paper (5 cm × 30 cm square, weighed) is quickly pressed onto the coated surface for 1 minute at a pressure of about 50 g / cm ² and peeled off. Take 10 such filter paper samples, weigh the sample weight with a precision balance (1/1000 g), calculate the amount of oil adhering to the filter paper per unit area from the difference from the weight of the filter paper weighed in advance, This was defined as the amount of oil applied per unit area to the surface of the fixing roller.

<Measurement method of dynamic viscoelasticity of surface layer>
The dynamic viscoelasticity of the surface layers 114 and 124 of the fixing roller 101 and the pressure roller 102 was measured as follows. First, the same uncured addition-type liquid silicone rubber used for the surface layer was prepared, formed into a sheet having a thickness of 2 mm, and cured by heating and vulcanization to obtain a sheet-shaped measurement sample. The measurement sample having a thickness of 2 mm was cut into a width of about 5 mm and a length of about 40 mm, and the dynamic viscoelasticity was measured with a viscoelasticity measuring device (DVEREHOSPECTORER DVE-V4) manufactured by Rheology Co., Ltd. The measurement conditions at this time were set under the conditions of a pulling jig (175% elongation), a measurement temperature of 170 ° C., and a sine wave distortion (frequency of 100 Hz).

<Details of materials used>
Details of the surface layer materials used in this example will be described below.

<Implementation material 1>
A linear polysiloxane segment having a viscosity of about 30 Pa · s at 25 ° C. and having about 300 consecutive bifunctional dimethylsiloxane units, and a branch having one vinyl group bonded to both ends thereof Linear dimethylpolysiloxane (Ab-1) having vinyl groups at both ends having a viscosity of about 10,000 Pa · s at 25 ° C. in 60 parts by weight of a block copolymer (Aa-1) composed of a linear polysiloxane segment 40 parts by weight of an organopolysiloxane having 2 or more silicon-bonded hydrogen atoms in one molecule as a crosslinking agent in a mixture of the components (A-a-1) and (A-b-1) Is added in such an amount that the molar amount of the hydrogen atom is 1.3 times the molar amount of all vinyl groups contained in. Furthermore, a platinum-based catalyst is added to the mixture, and ferric chloride (D-1) is added to the mixture so that the amount is 50 ppm based on the iron component, and an uncured addition-type liquid silicone rubber ( S-1) was obtained.

By curing this addition-type liquid silicone rubber (S-1) by heating and vulcanization, the storage elastic modulus is 1.37 × 10 ⁷ dyn / cm ² and the loss elastic modulus is 5.28 × 10 ⁵ dyn. A dimethylsilicone rubber of / cm ² could be obtained.

<Implementation material 2>
20 parts by weight of dimethyl silicone oil having a weight average molecular weight of 1.6 × 10 ⁵ is mixed with 100 parts by weight of the uncured addition-type liquid silicone rubber (S-1) of Example Material 1 to add uncured Type liquid silicone rubber (S-2) was obtained.

  The cross-linking agent and the catalyst were the same as those in Example Material 1.

By curing the addition-type liquid silicone rubber (S-2) by heating and vulcanization, the storage elastic modulus is 0.89 × 10 ⁷ dyn / cm ² and the loss elastic modulus is 7.0 × 10 ⁵ dyn. A dimethylsilicone rubber of / cm ² could be obtained.

<Implementation material 3>
A linear oil segment having a viscosity of about 20 Pa · s at 25 ° C. and having about 200 continuous bifunctional dimethylsiloxane units, and a branched chain having one vinyl group bonded to both ends thereof Linear dimethylpolysiloxane (Ab-2) having vinyl groups at both ends having a viscosity of about 11000 Pa · s at 25 ° C. in 55 parts by weight of a block copolymer (Aa-2) comprising a polysiloxane segment 45 parts by weight are mixed, and an organopolysiloxane having two or more silicon-bonded hydrogen atoms in one molecule as a cross-linking agent and a platinum-based catalyst are added, and only 50 ppm based on iron components is added to these mixtures. An amount of ferric chloride (D-1) was added to obtain an uncured addition-type liquid silicone rubber (S-3).

  The cross-linking agent and the catalyst were the same as those in Example Material 1.

By curing the addition-type liquid silicone rubber (S-3) by heating and vulcanization, the storage elastic modulus is 0.9 × 10 ⁷ dyn / cm ² and the loss elastic modulus is 3.0 × 10 ⁵ dyn. A dimethylsilicone rubber of / cm ² could be obtained.

<Implementation material 4>
20 parts by weight of dimethyl silicone oil having a weight average molecular weight of 1.6 × 10 ⁵ is mixed with 100 parts by weight of the uncured addition-type liquid silicone rubber (S-3) of execution material 3, and uncured addition Type liquid silicone rubber (S-4) was obtained.

  The cross-linking material and the catalyst were the same as those of Example Material 1.

By curing the addition-type liquid silicone rubber (S-4) by heating and vulcanization, the storage elastic modulus is 0.4 × 10 ⁷ dyn / cm ² and the loss elastic modulus is 4.6 × 10 ⁵ dyn. A dimethylsilicone rubber of / cm ² could be obtained.

<Comparative material 1>
As a crosslinking agent, 60 parts by weight of the organopolysiloxane (Aa-1) described in Example Material 1 is mixed with 40 parts by weight of the linear dimethylpolysiloxane (Ab-1) described in Example Material 1. An organopolysiloxane having two or more silicon-bonded hydrogen atoms in one molecule and a platinum-based catalyst are added, and 3% by weight of heat-resistant silica powder (R972, manufactured by Nippon Aerosil Co., Ltd.) is added to the mixture. Addition and mixing were performed to obtain an uncured addition-type liquid silicone rubber (S-5).

  The cross-linking agent and the catalyst were the same as those in Example Material 1.

By curing the addition-type liquid silicone rubber (S-5) by heating and vulcanization, the storage elastic modulus is 2.01 × 10 ⁷ dyn / cm ² and the loss elastic modulus is 7.88 × 10 ⁵ dyn. Dimethyl silicone rubber having a / cm ² was obtained.

<Comparative material 2>
To 100 parts by weight of the organopolysiloxane (Aa-1) described in the execution material 1, an organopolysiloxane having two or more silicon-bonded hydrogen atoms in one molecule as a crosslinking agent and a platinum-based catalyst are added. A cured addition type liquid silicone rubber (S-6) was obtained.

  The cross-linking agent and the catalyst were the same as those in Example Material 1.

This addition-type liquid silicone rubber (S-6) is cured by heating and vulcanization, whereby the storage elastic modulus is 5.95 × 10 ⁷ dyn / cm ² and the loss elastic modulus is 2.04 × 10 ⁶ dyn. A dimethylsilicone rubber of / cm ² could be obtained.

<Comparative material 3>
A linear polysiloxane segment having a viscosity at 25 ° C. of about 5 Pa · s and having a bifunctional dimethylsiloxane unit, and a branched polysiloxane segment having one vinyl group bonded to both ends thereof 20 parts by weight of linear dimethylpolysiloxane (Ab-3) having vinyl groups at both ends having a viscosity of about 1000 Pa · s at 25 ° C. are mixed with 80 parts by weight of the block copolymer (Aa-3). Then, an organopolysiloxane having two or more silicon-bonded hydrogen atoms in one molecule as a cross-linking agent and a platinum-based catalyst are added, and a second chloride chloride in an amount sufficient to be 50 ppm based on the iron component is added to these mixtures. Iron (D-1) was added to obtain an uncured addition-type liquid silicone rubber (S-7).

  The cross-linking agent and the catalyst were the same as those in Example Material 1.

By curing the addition-type liquid silicone rubber (S-7) by heating and vulcanization, the storage elastic modulus is 4.0 × 10 ⁷ dyn / cm ² and the loss elastic modulus is 13 × 10 ⁵ dyn / cm. A dimethyl silicone rubber of ² was obtained.

<Comparative material 4>
60 parts by weight of the resinous organopolysiloxane (A-a-3) described in Comparative Material 3 and a terminal vinyl-blocked linear dimethylpolysiloxane (A-b-4) having a viscosity at 25 ° C. of about 500 Pa · s 40 parts by weight are mixed, and an organopolysiloxane having two or more silicon-bonded hydrogen atoms in one molecule as a cross-linking agent and a platinum-based catalyst are added, and only 50 ppm based on iron components is added to these mixtures. An amount of ferric chloride (D-1) was added to obtain an uncured addition-type liquid silicone rubber (S-8).

  The cross-linking agent and the catalyst were the same as those in Example Material 1.

By curing the addition-type liquid silicone rubber (S-8) as described above by heating and vulcanization, the storage elastic modulus is 3.9 × 10 ⁷ dyn / cm ² and the loss elastic modulus is 11 × 10 ^5. A dimethyl silicone rubber having a dyn / cm ² of could be obtained.

<Example>
Examples in which the effects of the present invention are confirmed will be described below.

<Example 1>
First, the following experiment was conducted in order to clarify the relationship between the amount of the release oil applied to the surface layer of the fixing roller and the stickiness of the PHP transparency sheet.

In this experiment, an image forming apparatus (Color Laser Copier 800 (CLC800) manufactured by Canon Inc.) shown in FIG. 2 was used. Experimental conditions are
Copy original: Black Copy mode: Full color mode, single-sided copy Recording sheet: Color laser copier transparency (Canon, CT-700), A4
It was. A blank copy original is a blank original. The color laser copier transparency is an OHP transparency sheet for CLC.

  As shown in Table 1, a roller having a surface layer of dimethyl silicone rubber as a working material and a comparative material was used as a fixing roller and a pressure roller of a heat and pressure fixing device.

  Moreover, the pressing pressure of the oil regulating blade 7 was changed, and the amount of release oil applied to the surface layer was changed to 20, 40, and 60 mg / A4.

  The OHP transparency sheet stickiness was evaluated by the stickiness when one OHP transparency sheet was copied and placed on a glass plate and peeled off.

  As shown in Table 1, which is the experimental result, stickiness of the OHP transparency sheet was confirmed at coating amounts of 40 and 60 mg / A4. On the other hand, no stickiness was confirmed at a coating amount of 20 mg / A4.

<Experimental example 2>
Next, in order to clarify the relationship between the amount of release oil applied to the surface layer of the sticking roller and the image defect at the time of double-sided image formation, the following experiment was conducted.

For this experiment, the same image forming apparatus as in Experimental Example 1 was used, and the experimental conditions were as follows:
Copy manuscript: magenta,
Copy mode: full-color mode, the double-sided copy a recording sheet: plain paper (81.4g ^/ m 2), A4
It was. A magenta copy original is an image formed with an image forming apparatus at a magenta density of 100%.

  The fixing roller of the heat and pressure fixing device, the dimethyl silicone rubber on the surface layer of the pressure roller, and the amount of release oil applied to the surface layer were the same as in Experimental Example 1.

  The evaluation of the image defect was performed by performing a double-sided copy test for 50 sheets, and the presence or absence of the image defect caused by the photosensitive drum oil stain was evaluated by visual confirmation of the fixed image at the time of copying 50 sheets.

  As shown in Table 2 as the experimental results, image defects during double-sided image formation were confirmed at application amounts of 40 and 60 mg / A4. On the other hand, no image defect was confirmed at a coating amount of 20 mg / A4.

<Experimental example 3>
In order to clarify the releasability of the working material of the present invention and the comparative material for clarifying the effect of the present invention as a fixing roller, the following experiment was conducted.

For this experiment, the same image forming apparatus as in Experimental Example 1 was used, and the experimental conditions were as follows:
Copy original: Magenta halftone Copy mode: Full color mode, single-sided copy Recording sheet: Plain paper (81.4 g / m ² ), A4
It was. A magenta halftone copy original is an image having a magenta density of 50% and an image formed by the image forming apparatus in a halftone mode.

  In addition, this experiment is an experiment for clarifying the performance of the fixing roller, and the surface layer material of the pressure roller can be arbitrarily selected, but here, the same material as the material of the fixing roller was used.

  The releasability was evaluated by the release life of the fixing roller. The release life was defined as the number of sheets passed when the toner offset was visually confirmed on the image after fixing.

  As shown in Table 3, which is the experimental result, the experimental material is less than 0.5 mg / A4 when the application amount of the release oil is 20 mg / A4 or less, compared to the comparative material. It showed a sufficiently long release life.

<Experimental example 4>
In order to clarify the releasability of the working material of the present invention and the comparative material as a pressure roller in double-sided image formation, the following experiment was conducted.

For this experiment, the same image forming apparatus as in Experimental Example 1 was used, and the experimental conditions were as follows:
Copy original: Magenta halftone Copy mode: Full color mode, Duplex copy Recording sheet: Plain paper (81.4 g / m ² ), A4
It was.

  The releasability of the pressure roller is as follows. For every 100 sheets, a fixed image whose back side (pressure roller side) is magenta is used as a recording sheet, a single copy is made with a blank copy original, and a back side magenta image. The release property of the pressure roller was evaluated based on the degree of image omission. In this evaluation, when the releasability is poor, an image dropout occurs in the back side image after passing the paper, which can be visually confirmed.

  As shown in Table 4, which is the experimental result, when the applied amount of the release oil is 20 mg / A4 or less, the magenta solid image on the pressure roller side is less than that of the comparative material. It does not occur and has excellent releasability.

<Experimental example 5>
As Experimental Example 5, an experiment was performed to confirm the performance of the material used in image formation using three or more colors of toner.

For this experiment, the same image forming apparatus as in Experimental Example 1 was used, and the experimental conditions were as follows:
Copy manuscript: full color photographic manuscript Copy mode: full color mode, single-sided copy Recording sheet: plain paper (81.4 g / m ² ), A4
It was. Here, the full-color photographic document is a document on which a person photograph is arranged so that toners of four colors of CMYK are used with good balance when image formation is performed.

  The performance of the implementation material was evaluated by visually confirming the image after fixing and determining whether an image defect such as toner offset occurs.

  As shown in Table 5 which is the experimental result, the execution material exhibited the image fixing performance over 100,000 sheets and was able to perform the heat and pressure fixing without any problem.

Softening characteristics of sharp melt toner Explanatory drawing of an image forming apparatus provided with a heat and pressure fixing device Sectional drawing of the heat-pressure fixing apparatus of the Example of this invention

Claims (4)

The storage elastic modulus E ′ is larger than 1.0 × 10 ⁶ dyn / cm ^{2 and} smaller than 1.5 × 10 ⁷ dyn / cm ² , and the loss elastic modulus E ″ is 1.0 × 10 ⁵ dyn / A silicone rubber roller having a dimethyl silicone rubber containing ferric chloride on at least a surface thereof in a range larger than cm ^{2 and} smaller than 7.5 × 10 ⁵ dyn / cm ² . The dimethyl silicone rubber is
(A) (a) Two or more vinyl groups in one molecule, 50 to 70% by weight of branched organopolysiloxane, and (b) vinyl at both ends having a viscosity at 25 ° C. of 10,000 Pa · s or more. A polysiloxane mixture comprising 30 to 50% by weight of linear polydimethylsiloxane having groups,
(B) an organopolysiloxane having two or more silicon-bonded hydrogen atoms in one molecule;
(C) a platinum-based catalyst, and ferric chloride in an amount sufficient to be 3 to 300 ppm on the iron component basis with respect to the total amount of (D) (A) + (B) + (C),
2. The silicone rubber roller according to claim 1, which is a dimethyl silicone rubber obtained by addition polymerization of an addition type liquid silicone rubber having at least the components (A) + (B) + (C) + (D). The dimethyl silicone rubber is
(A) (a) 50 to 70% by weight of a branched organopolysiloxane having two or more vinyl groups in one molecule, and (b) having both terminal vinyl groups having a viscosity at 25 ° C. of 10,000 Pa · s or more. A polysiloxane mixture comprising from 30 to 50% by weight of linear polydimethylsiloxane;
(B) an organopolysiloxane having two or more silicon-bonded hydrogen atoms in one molecule;
(C) platinum-based catalyst,
(D) Ferric chloride in an amount of 3 to 300 ppm on the iron component basis with respect to the total amount of (A) + (B) + (C), and (E) (A) + (B) Dimethyl silicone oil in an amount of 5 to 20 parts by weight with respect to 100 parts by weight of the total amount of + (C) + (D),
2. The silicone according to claim 1, which is a dimethyl silicone rubber obtained by addition polymerization of an addition-type liquid silicone rubber having at least the components (A) + (B) + (C) + (D) + (E). Rubber roller.   Fixing used for fixing a toner image in cooperation with a pressure roller in a heat and pressure fixing device for a toner image in which the silicone rubber roller has means for applying a release oil made of dimethyl silicone oil to a fixing roller. The silicone rubber roller according to claim 1, which is a roller.

Images