JPH0830926B2 - Rotating body for fixing and fixing device - Google Patents

Description

TECHNICAL FIELD The present invention relates to an electrophotographic copying machine, an electrostatic recording device, a printing machine,
A fixing rotator and a fixing device for fixing, as a permanent image, an unfixed image such as a toner image formed on an image carrier and then transferred onto a transfer material as a recording material in an image forming apparatus such as a printer. In particular, regarding the rotating body for fixing, which has a heat source inside and a contact for fixing the unfixed image transferred to the transfer material on its outer peripheral surface and fixing the unfixed image Also, the present invention relates to a fixing device including the fixing rotating body.

Conventional technology and its problems Conventionally, an unfixed image such as a toner image formed on an image carrier such as a photosensitive drum is transferred onto a transfer material through a process for image formation, and this unfixed image is transferred. It is widely used to use a rotating body such as a belt or a roller for fixing. In particular, a thermal roller fixing device that allows a transfer material having an unfixed image to pass between a pair of rollers and fixes the unfixed image on the transfer material by heat and pressure in a nip portion formed between these rollers is an apparatus. Because of its simplicity, it has been used as the mainstream until now.

Further, when fixing an unfixed image on a transfer material by a fixing device using a rotating body such as a roller, elasticity is provided to increase the layer thickness of the unfixed image and increase the fixing speed. A rotating body for fixing is considered. In order to satisfy the required elasticity and releasability required for fixing, such a fixing rotary member has conventionally been made of silicone rubber, particularly rubber such as RTV and LTV, or an inorganic material such as silica red iron oxide. A mixture of agents is used on the outer circumference of the fixing rotator.

However, in the rubber using the above-mentioned cross-linking agent, re-crosslinking proceeds by heating and becomes brittle, or decomposes by thermal oxidation, so that the performance of the fixing rotary member disposed on the outer peripheral surface is improved. Is damaged. Further, as a release agent, the silicone oil applied to the outer periphery of the fixing rotator swells the rubber disposed on the outer peripheral surface of the rotator, and the outer diameter of the rotator partially changes. result,
There is a problem that the fixed image is adversely affected.

That is, in such a fixing rotator, the material that satisfies the required elasticity and the releasability required for fixing and has sufficient printing durability is not a single material but usually a roller core. A fluororesin layer or a silicone resin layer is provided on a rubber (silicone rubber) layer as an elastic layer formed on gold to form a plurality of layers, and each layer has a function necessary for fixing.

However, in the case where the fluororesin is formed on the rubber layer as described above, the expansion of the lower rubber layer which is the roller core metal and the elastic layer by heating causes the fluororesin to be stretched, and by repeating this heating process, Fine wrinkles may occur on the roller surface. Alternatively, as shown in JP-A-62-255981, JP-A-58-11976, etc., when a silicone varnish is applied onto a rubber-like elastic layer to form a silicone resin coating layer, The hardness of the layer is too high, and the elongation of the varnish is usually as low as 50% or less. No, it may cause peeling.

Therefore, in the case where such a fixing rotator is used in the fixing device, the fixing of the image may be adversely affected and the fixing of the image may be defective.

SUMMARY OF THE INVENTION Therefore, the present invention has been made in view of the above-mentioned prior art, and an object thereof is to suppress thermal oxidation of the surface of a silicone rubber simple substance, and a lower rubber layer as an elastic layer, and For fixing with a surface that has high durability and high releasability, which can sufficiently follow the thermal expansion of the core of the rotating body and does not cause wrinkles, cracks or peeling on the surface of the rotating body. A rotary body and a fixing device using the same.

Means for Solving the Problems The above object is achieved by the fixing rotator and the fixing device according to the present invention. That is, in summary, the present invention has a rubber layer and a phenyl group having a unit of a copolymer of a linear polysiloxane and a polysiloxane having a three-dimensional network structure provided on the rubber layer. And a surface layer made of a silicone resin.

According to another aspect of the present invention, there is provided a pair of rotating bodies that are in pressure contact with each other, and at least one of the rotating body pairs at the pressure contact portion has a rubber layer and a linear chain provided on the rubber layer. And a surface layer made of a silicone resin having a phenyl group whose unit is a copolymer of a polysiloxane having a linear shape and a polysiloxane having a three-dimensional network structure.

Alternatively, in the present invention, the linear polysiloxane is dimethylpolysiloxane or methylphenylpolysiloxane, and the three-dimensional network polysiloxane is RSiO _2/3 , R ₂ SiO, R ₃ SiO _{1 / 2} , SiO ₂ (R is a methyl group or a phenyl group) is a silicone varnish in which the respective structural units are Si—O—Si bonded to each other.

That is, according to the present invention, a transfer material having an unfixed toner image as an unfixed image is passed between a pair of heat rollers used as a fixing rotator, and unfixed on the transfer material by heat and pressure. In one or both rollers of a fixing device for melting and fixing a toner image, a heat-resistant elastic layer is provided as a lower layer, and a linear polysiloxane and 3
A fixing rotator having a film of a silicone resin layer having a phenyl group, the unit of which is a copolymer with a polysiloxane having a three-dimensional network structure, and a fixing device constituted by using the fixing rotator. The present invention provides a highly durable fixing rotating body that is thermally stable and highly stretchable, and a fixing device that can obtain good image fixing without adversely affecting image fixing.

Examples Hereinafter, the present invention will be described based on the examples with reference to the accompanying drawings.

Referring to FIGS. 1 and 2, there is shown a fixing device using a fixing rotary member according to the present invention. The fixing device 100 includes a fixing roller 1 as a fixing rotary member.
And a pressure roller 2. The fixing roller 1 is provided with a hollow cylinder 3 as a cored bar made of aluminum or iron or the like. Inside the hollow cylinder 3, a heat source 5a such as a halogen lamp is provided, and on the outer peripheral surface of the hollow cylinder 3, A heat resistant elastic layer 4 is provided, and a silicone resin release layer 41 according to the present invention is provided as a surface layer on the elastic layer 4.

Similarly to the fixing roller 1, the pressure roller 2 also includes a hollow cylinder 7 as a cored bar made of aluminum, iron, or the like. Inside the hollow cylinder 7, a heat source 5a such as a halogen lamp is provided, and On the outer peripheral surface of the cylinder 7, there is provided a fluororesin layer such as PTFE or PFA or a fluorolatex layer, or a silicone resin release layer 6 similar to the fixing roller 1.

Further, the fixing roller 1 and the pressure roller 2 are in contact with each other with a width, that is, a nip width, which is pressed by a spring or the like (not shown) and can sufficiently supply the heat required for fixing to the transfer material and the toner.

The operation of the fixing device having the above-described configuration will be described. When the power switch (not shown) of the main body of the fixing roller 1 and the pressure roller 2 or the fixing roller 1 is turned on,
It is heated by internal heat sources 5 and 5a, and the temperature of each surface is adjusted by a temperature sensor (not shown) so as to be optimum for fixing.

Next, a transfer material 10 having a toner image 11 as an unfixed image, which is created by a known electrophotographic method and transferred onto a transfer material 10 such as paper or a plastic film, is supplied toward the fixing device 100. When started, each roller 1, 2 rotates in the direction of arrow A. Furthermore, this transfer material 10
However, when the transfer material 10 enters the pressure contact portion formed by both the fixing roller 1 and the pressure roller 2, the transfer material 10 is nipped and conveyed by these both rollers, and the transfer material 10 is pressed and heated by the pressure contact portion. The upper toner image is fused and fixed, and thereafter, the transfer material 10 and the separation claw 9 on which the toner image is fixed are separated from the rollers 1 and 2 and discharged.

The surface of the rollers that have completed the fixing process, especially the fixing roller 1 that has come into contact with the toner image surface on the transfer material 10, is cleaned by the cleaning member 8 to prepare for the next fixing process.

Although not particularly shown in FIG. 1, if necessary, on the surface of the roller contacting the toner image on the transfer material 10,
There is no problem even if an appropriate amount of release agent such as dimethyl silicone oil is applied.

Here, regarding the above-mentioned fixing rotator in the present invention,
Further details will be described.

Although the following description also applies to the pressure roller 2,
Here, first, the fixing roller 1 will be described.

The lower rubber layer disposed as the heat resistant elastic layer 4 on the outer peripheral surface of the hollow cylinder 3 is made of high heat resistant heat vulcanizing silicone rubber, and particularly, methyl vinyl silicone rubber or methyl phenyl silicone rubber, or these Is used. Further, since the rubber alone is inferior in strength, a reinforcing filler such as silica or red iron oxide may be mixed, and a filler such as carbon or alumina may be kneaded in order to improve thermal conductivity. Furthermore, in order to improve the oil resistance of the base rubber, increasing the number of phenyl groups (C ₆ H ₅ ) contained in the rubber used and making it incompatible with dimethyl silicone oil improves durability. Is the preferred choice.

Next, the silicone resin layer formed as the surface release layer 41 on the heat resistant elastic layer 4 will be described. Here, the resin used for the surface release layer 41 has characteristics of both silicone rubber and silicone varnish, and the unit constituting the resin has a molecular weight of 10 ^{4 to} 5 × 10 ^5.
A rubber-like linear polysiloxane composed of dimethylpolysiloxane or methylphenylpolysiloxane, and RSiO _2/3 , R ₂ SiO, R ₃ SiO _1/2 , SiO ₂ (R is a methyl group or a phenyl group) It is a copolymer with a polysiloxane compound having a three-dimensional network structure in the form of a so-called silicone varnish, in which each structural unit is connected to each other by a Si-O-Si bond and has a phenyl group.

That is, the surface release layer 41 made of this resin becomes a block copolymer of rubber-like silicone and varnish-like silicone after curing.

The characteristics of the resin coating film thus formed as the surface release layer 41 are as follows: the molecular weight of the rubber-like silicone described above, the number of side chain methyl groups and phenyl groups, and the functionality and methyl of the varnish-like silicone portion. It can be changed by selecting the number of groups and phenyl groups.

For example, in order to further enhance the releasability at the time of fixing, it is preferable that the rubber-like silicone has a molecular weight of about 30,000 to 200,000 and a side chain methyl group of 50% or more. In particular, when the molecular weight is 200,000 or more, the resin itself becomes rubber-like, and when dimethyl silicone oil is used as a release aid, oil swelling in the lower rubber layer as the elastic layer 4 becomes remarkable, and the outer diameter of the fixing roller 1 is increased. Is not very preferable for the stability of Further, when the molecular weight is 30,000 or less, the rubber properties are deteriorated and the flexibility is deteriorated. Further, in order to reduce oil swelling, it is preferable that the side chain has a slight amount of phenyl groups. However, if the number of phenyl groups exceeds 50%, sufficient releasability cannot be obtained.

Next, the varnish portion of the silicone resin formed on the elastic layer 4 as the surface release layer 41 will be described. It should have a rubber layer as the elastic layer 4 in the lower layer, and this resin must have sufficient flexibility. However, no matter how the molecular weight of the rubber portion is set to 30,000 or more, the functionality in the varnish portion is R / Si (R is the number of methyl groups or phenyl groups, Si is the number of silicon). When the ratio is less than 1, the hardness of the resin coating film formed as the surface release layer 41 becomes too high, and the rubber cannot be deformed, causing cracks and the like.

An appropriate value of this R / Si ratio is 1 or more and less than 2, and preferably 1 or more and 1.7 or less in order to obtain coating strength. Further, also on the varnish side, the number of methyl groups / number of phenyl groups is also an important factor. When this value is 5 or less, the resin coating film hardness becomes high and subtle peeling occurs due to repeated bending, and this peeling is fixed. The time offset may be triggered from the beginning. Also,
In order to obtain sufficient releasability in a wide range of toner viscosity at the time of fixing of 10 ² to 10 ¹² poise, the methyl / phenyl ratio is preferably 8 or more and 1000 or less, and more preferably 50 to 200. Set it in between.

As the release layer 41, in the actual resin coating film formation,
First, after forming the elastic layer 4 on the core metal as the hollow cylinder 3 made of aluminum, iron or the like by the molding method such as compression and injection of the above-mentioned HTV silicone rubber, in order to obtain finishing accuracy if necessary. Then, polish and grind.

Next, the above silicone resin diluted with a solvent such as toluene at a ratio of 10 to 50% by weight is coated on the elastic layer 4 by a method such as a dip method or a spray method, and dried to release the surface. Form layer 41. The thickness of the resin coating film as the surface release layer 41 is 5 to 300 μm.
And preferably 10 to 70 μm. When the thickness of the resin coating film is 5 μm or less, not only the base rubber layer, which is the elastic layer 4, may be partially exposed due to coating unevenness, but also abnormal pressure increase such as paper jam may occur. If it occurs, the resin coating film may be damaged, making it practically impossible to use. Also, the thickness of the resin coating film is 300 μm
If you try to form the above coating film, it will be created by repeating the coating operation several times or by increasing the solid component of the coating liquid itself, causing unevenness in the coating film due to dripping and unevenness in dry curing conditions. , It is difficult to obtain a uniform coating film.

Hereinafter, examples performed under the above-described conditions according to the present invention and comparative examples as conventional examples will be described together. Further, all the rubber hardness described in the experimental example according to the present invention and the comparative example as the conventional example are measured values of the spring type hardness test A type based on the JIS vulcanized rubber physical test method.

Experimental Example 1 An HTV methylphenyl silicone rubber having a rubber hardness of 40 ° was formed as an elastic layer 4 with a thickness of 1 mm on an aluminum core metal having a diameter of 38 mm as the hollow cylinder 3, and a rubber of silicone resin was formed on the elastic layer 4. A block copolymer silicone resin with a molecular weight of 100,000 and a three-dimensional network varnish with a methyl / phenyl ratio of 50 and an R / Si ratio of 1.7 was used to form a dimethylpolysiloxane in the shape of dimethylpolysiloxane. The one formed as the mold layer 41 is used as a fixing roller, the color toner for C2-1 (manufactured by Canon) whose toner viscosity at the time of fixing is 10 ⁴ poise or less is used as the toner, the roller surface temperature is 170 ° C., and the peripheral speed is 90 mm. A fixing test of a full-color image was conducted at / sec.

Experimental Example 2 The conditions were the same as 1 except that the methyl / phenyl ratio of the varnish-like portion of the silicone resin as the surface release layer 41 was 100.

Experimental Example 3 The hardness of the lower rubber as the elastic layer 4 was set to 70 °, and the molecular weight of the rubber portion of the silicone resin was set on the elastic layer 4.
40,000, methyl / phenyl ratio of 2, block copolymerized silicone resin consisting of varnish of silicone resin with methyl / phenyl ratio of 8 and R / Si ratio of 1.5, surface release with a thickness of 30 μm The one formed as the layer 41 was used as a fixing roller, polyester toner for NP-7550 (manufactured by Canon) was used, and the roller temperature was 185 ° C.
A fixing test was conducted at mm / sec.

Comparative Example 1 An RTV silicone rubber having a hardness of 40 ° was formed as an elastic layer 4 with a thickness of 3 mm on an aluminum cored bar having a diameter of 58 mm as a hollow cylinder 3 and used as a fixing roller. I went.

Comparative Example 2 An HTV silicone rubber having a hardness of 40 ° was formed as an elastic layer 4 with a thickness of 1 mm on an aluminum core metal having a diameter of 58 mm as the hollow cylinder 3, and a methyl / phenyl ratio of 50, R was formed on the elastic layer 4. A silicone resin having no rubber-like portion of a / Si ratio of 1.5 was formed as the surface release layer 41 with a thickness of 30 μm, and this was used as a fixing roller under the same conditions as in Experimental Example 3. A fixing test was performed.

In the above 5 cases, as a release aid in all experiments,
Dimethyl silicone oil having a viscosity of 100 cs was used in a form of being applied in an amount of 0.05 to 0.2 g per one transfer material.

 The results are shown in Table 1 below.

As is apparent from the surface 1, in Experimental Example 1, the amount of swelling due to oil is reduced, that is, the oil resistance is improved, and the toner having a low viscosity can be released.
Then, although the amount of swelling due to oil is larger than in Experimental Example 1,
It was possible to use at higher temperatures, and in Experimental Example 3, the effect that there was almost no swelling due to oil was obtained. On the other hand, in Comparative Example 1, swelling due to oil is significantly inadequate in dimensional stability, and in Comparative Example 2, only a small number of transfer materials have durability, and a small number of sheets cause small peeling, resulting in offset. I was there.

In the above description, the fixing rotator according to the present invention is used as a fixing roller that contacts and fixes an unfixed toner image, but as described above, the fixing rotator according to the present invention is used. Of course, the pressure roller 2 shown in FIG. 1 can also be used.

In this case, the main purpose of the pressure roller 2 is to form a contact width (nip width) by the fixing roller 1 and the pressure roller 2, and the production of the surface release layer by the silicone resin of the present invention is for this purpose. It is enough.

For example, in the past, several tens of layers were used as a release layer on the HTV methylphenyl silicone rubber layer with a thickness of 5 mm or more, which is an elastic layer.
A roller covered with a fluororesin tube such as PFA having a thickness of μm is used as the pressure roller. However, even if the hardness of the rubber itself is lowered, the PFA tube is hard and the hardness is substantially increased. For this reason, conventionally, the pressure for securing the necessary nip width increases, and the pressure distribution easily occurs.

On the other hand, the silicone resin used in Experimental Example 1 was coated on an elastic layer having a rubber hardness of 40 ° and a thickness of 5 mm to form a pressure roller having an outer diameter of 50 mm. When a fixing roller coated with polytetrafluoroethylene on the surface without a layer is used in combination, the nip width is
The pressure for obtaining 5 mm was 16 kg, and the pressure distribution did not occur.

On the other hand, when the same lower rubber layer is used as the elastic layer and a PFA tube with a thickness of 25 μm is covered with an adhesive layer on this elastic layer to form a pressure roller, the average nip width is 5 mm. In addition to the pressure of 20 kg or more, the center of the roller in the longitudinal direction and the end of the roller have a difference in nip width of about 1 mm, and a pressure distribution is generated. In addition, all the above-mentioned rollers are formed in a right cylindrical shape.

Further, in the above description, the roller-shaped fixing member has been described, but it goes without saying that the present invention is also applicable to a belt-shaped member.

As described above, according to the fixing rotator and the fixing device of the present invention, a linear structure polysiloxane (dimethyl) is formed on the surface of the fixing rotator having an elastic layer such as a rubber layer as a lower layer. Or methylphenyl) and a polysiloxane having a three-dimensional network structure (methyl or methylphenyl), a heat-resistant and oil-resistant surface layer by forming a release layer using a silicone resin having a phenyl group of a block copolymer. It was possible to effectively prevent the deterioration of the rotating body, and the following effects were obtained. That is, 1) It has high releasability similar to RTV silicone rubber, and since it is a surface release layer having a density higher than that of rubber, impact resistance and durability are improved as compared with conventional ones.

2) Despite being a high-density resin, since it has elasticity twice or more that of varnish, reliability was increased without causing cracks or peeling on the surface.

3) Since the elastic layer has high adhesion to the lower rubber and has a low hardness, the lower rubber can be deformed at a lower pressure than PFA tube coat, and pressure distribution is less likely to occur.

[Brief description of drawings]

FIG. 1 is a schematic vertical sectional view of an embodiment of a fixing device using a fixing rotary member according to the present invention. FIG. 2 is a schematic enlarged partial sectional view of the surface portion (X portion) of the fixing rotator used in FIG. 1: fixing roller 2: pressure roller 3: hollow cylinder 4: elastic layer 5, 5a: heat source 6, 41: release layer 10: transfer material 11: toner image 100: fixing device

Claims (4)

[Claims] 1. A rubber layer and a silicone resin having a phenyl group whose unit is a copolymer of a linear polysiloxane and a polysiloxane having a three-dimensional network structure provided on the rubber layer. A rotating body for fixing, comprising: a surface layer. 2. The linear polysiloxane is dimethylpolysiloxane or methylphenylpolysiloxane, and the three-dimensional network polysiloxane is RSi.
A silicone varnish in which each structural unit of O _2/3 , R ₂ SiO, R ₃ SiO _1/2 , and SiO ₂ (R is a methyl group or a phenyl group) is Si—O—Si bonded to each other. The rotating body for fixing described. 3. A fixing device comprising a pair of rotating bodies that are in pressure contact with each other, wherein a recording material carrying an unfixed image is nipped and conveyed at the pressure contact portions to perform heat fixing, at least one of the rotating body pairs being A rubber layer, and a surface layer made of a silicone resin having a phenyl group whose unit is a copolymer of a linear polysiloxane and a polysiloxane having a three-dimensional network structure provided on the rubber layer,
A fixing device having: 4. The linear polysiloxane is dimethylpolysiloxane or methylphenylpolysiloxane, and the polysiloxane having a three-dimensional network structure is RSi.
4. A silicone varnish in which constituent units of O _2/3 , R ₂ SiO, R ₃ SiO _1/2 , and SiO ₂ (R is a methyl group or a phenyl group) are Si—O—Si bonded to each other. The fixing device described.