JPH06266257A - Pressure roller - Google Patents

Abstract

PURPOSE:To provide a pressure roller preventing the peeling of a fluororesin layer from an elastic body layer and having good durability. CONSTITUTION:A fluororesin sleeve 5 having the thickness of 0.1mm or below is applied on the outer periphery of an elastic body layer 3 covered on the outer periphery of a core metal 2 to form a pressure roller 1, the elastic body layer 3 and the fluororesin sleeve 5 are stuck with an adhesive layer 4, and the adhesive layer 4 is made of an addition type silicone compound having the breaking elongation of 350% or above and the tensile strength of 3MPa or above.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure roller in a fixing unit of an electronic copying machine or a laser beam printer (hereinafter abbreviated as LBP).

[0002]

2. Description of the Related Art Heretofore, as a pressure roller in a fixing portion of an electronic copying machine or an LBP, there has been known a roller in which a fluorine resin sleeve is coated on the outer periphery of a rubber roller containing a core metal in order to improve the releasing property of toner. .

In recent years, miniaturization of electronic copying machines and LBPs using a fixing roller has progressed, and the outer diameter of the pressure roller and the heating roller used for this has become about 10 to 25 mm, especially in the pressure roller. Is a roller having a small diameter, so that the elastic layer that covers the outer periphery of the cored bar to secure the nip width during fixing tends to have a low hardness,
For example, as disclosed in Japanese Examined Patent Publication (Kokoku) No. 4-77315, one using a porous elastic body (sponge rubber) as an elastic body layer is often used.

Recently, in order to secure the releasability of the pressure roller from the toner, the surface layer is coated with a fluororesin, and such a roller is disclosed in, for example, Japanese Patent Publication No. 47-20747. Can be mentioned,
The elastic roller disclosed in Japanese Patent Publication No. 47-20747 discloses a sleeve in which a mandrel coated with an elastic layer is coated with an adhesive, and the mandrel coated with the adhesive is inserted into a sleeve and heated. Is fixed to a mandrel coated with an elastic layer.

[0005]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
The elastic roller obtained by the manufacturing method disclosed in Japanese Patent No. 20747 uses a solid silicone rubber layer as an elastic layer and a heat-shrinkable tube of about 0.5 mm as a fluororesin sleeve. The silicone rubber layer and the fluororesin are hardly separated from each other because they are strongly adhered by heat shrinking.

However, when a small-diameter roller coated with a fluororesin sleeve having a thickness of 0.1 mm or less is prepared by the above-mentioned method, the space between the silicone sponge rubber layer of the elastic layer and the fluororesin sleeve layer is often used. There was a problem that it peeled off.

In the small-diameter roller described above, the reason why peeling often occurs between the silicone sponge layer of the elastic layer and the fluororesin layer is that the thickness of the fluororesin layer is 0.05 mm.
This is probably because the rigidity is weak as a whole because it is very thin, and it does not adhere sufficiently. Further, in the case of a small-diameter roller, the thickness of the fluororesin layer needs to be 0.1 mm or less in order to obtain the nip width required for the pressure contact between the pressure roller and the heating roller for fixing. It is very difficult to accurately manufacture a heat-shrinkable fluororesin sleeve having a size of 0.1 mm or less.

When the elastic layer is a sponge, it is possible to apply an adhesive to the surface of the elastic layer and then insert the fluororesin sleeve while shrinking the elastic layer, so that the elastic layer has heat-shrinkability. Although it is possible to make a small pressure roller as described above without using a fluororesin sleeve, it is essential to use an adhesive between the fluororesin layer and the sponge layer in this case as well. When the elastic layer is made of a soft material such as sponge rubber when the adhesive is used as described above, the elastic layer is much more extreme than the fluororesin layer which is the surface layer of the elastic layer. Due to the difference in rigidity, when the pressure roller is actually installed in an electronic copying machine or the like and used, a dynamic stress is applied to the adhesive layer which is an intermediate layer between the elastic layer and the fluororesin sleeve. The concentration causes a peeling phenomenon in the adhesive layer.

Since the thickness of the adhesive layer in a small pressure roller is as thin as about 25 μm, the cushioning effect of the entire adhesive layer is small, so that the adhesive layer cannot withstand external stress and the adhesive layer is destroyed. However, if the thickness of the adhesive layer is thicker than 0.5 mm, a dynamic stress is dispersed due to the buffering effect of the entire adhesive layer, resulting in adhesion. There is no peeling at the agent layer, and peeling usually occurs between the fluororesin layer and the adhesive layer.

Since the pressure roller for fixing is used at a high temperature of around 200 ° C., the adhesive must also have good heat resistance, and the elastic material composed of a fluororesin layer and silicone sponge or the like. Silicone-based adhesives are preferable for adhering the body layer. Furthermore, in order to adhere to the deep inside of the sleeve, an addition-type silicone rubber composition that does not generate a reaction by-product upon curing is generally used as an adhesive. ing.

The object of the present invention is to cover the elastic layer with a fluororesin layer having a thickness of 0.1 mm or less by using the above-mentioned adhesive of the addition type silicone rubber composition, and to make the fluororesin even if the roller system is made small. An object of the present invention is to provide a pressure roller excellent in durability without peeling between a layer and an elastic layer.

[0012]

The inventors of the present invention have conducted various studies in order to achieve the above-mentioned object, and as a result, the phenomenon of the pressure roller peeling by the above-mentioned addition type silicone adhesive is mainly caused by the adhesive layer. The present invention has found that by increasing the physical strength and elongation, the occurrence of a peeling phenomenon in the adhesive layer can be eliminated, and the durability as a pressure roller can be significantly improved, Is the result of completing.

That is, in the pressure roller according to the present invention, the outer periphery of the core metal is covered with the elastic layer, and the outer periphery of the elastic layer is covered with the fluororesin layer having a thickness of 0.1 mm or less. In the roller, the elastic layer and the fluororesin layer are adhesively fixed to each other with an adhesive layer made of an addition type silicone rubber composition having a breaking elongation of 350% or more and a tensile strength of 3 MPa or more. Is its characteristic.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the pressure roller of the present invention will be described with reference to FIG. 1. Reference numeral 1 denotes a pressure roller, and 2 is a core metal of the pressure roller 1 made of iron, aluminum or the like. The surface of 2 is covered with an elastic layer 3 made of sponge rubber,
Further, a fluororesin sleeve 5 is provided on the surface of the elastic layer 3 and an adhesive layer 4 made of an addition type silicone rubber composition.
It is fixed by adhesion.

Fluororesin sleeve 5 used in this embodiment
Generally, a copolymer of tetrafluoroethylene and perfluoroalkyl vinyl ether (hereinafter abbreviated as PFA) is used as the inner surface of the fluororesin sleeve 5 by the sodium-naphthalene-tetrahydrofuran method or the sodium-liquid one-liquid method. Good to process.

The composition of the silicone-based resin agent of this embodiment is not particularly limited, but (A) vinyl group-containing diorganosiloxane, (B) onoganohydrosiloxane, (C) platinum catalyst. And a reaction control agent as an essential component, and an adhesiveness-imparting agent such as an isocyanate or an epoxy compound can be used if necessary.
And, the above-mentioned isocyanate is disclosed in JP-A-51-1398.
The compounds disclosed in JP-A No. 54-124455 are exemplified, and the epoxy compounds disclosed in JP-A No. 52-126455 are exemplified. Further, when a primer is applied to the inner surface of the fluororesin sleeve and then adhered with an addition type silicone composition, an adhesiveness-imparting agent is not always necessary. In this case, the primer composition may be a primer for an addition type silicone composition, and examples thereof include those disclosed in JP-A-57-21457.

The hardness of the rubber-cured product of the addition-type silicone composition in this example is not particularly limited.
Although it can be arbitrarily selected in the range of 60 degrees, when the elastic layer is sponge rubber, it is preferably in the range of 8 to 35 degrees in view of the balance between hardness and physical strength. Further, the formulation of the filler and the like is not particularly limited, and the mechanical properties of the cured addition-type silicone composition layer, that is,
It is decided in consideration of physical strength, rubber hardness, compression set, and the like. This includes aerosil, fumed silica, wet silica such as nipsil, diatomaceous earth such as celite and radiolite, minusil and crystallite. Examples thereof include quartz powder, and these fillers are usually used in combination. In addition to the above fillers, aluminum oxide (alumina), titanium oxide, magnesium oxide, aluminum silicate, zinc oxide, iron oxide, calcium carbonate, and conductive materials are added in order to impart properties such as thermal conductivity and conductivity. Carbon or the like may be used. Furthermore,
A heat-resistant agent such as cerium oxide and an acid acceptor such as magnesium oxide may be added in consideration of the sealing aging property.

The elastic layer 3 in this embodiment is not particularly limited, but the volume resistivity of the elastic layer is 10 or less.
^It is common to use silicone sponge rubber of ¹⁴ Ω · cm or more. For the purpose of preventing offset, a conductive silicone sponge rubber having a volume resistivity of 10 ⁵ Ω · cm or less may be used.

In order to manufacture the processing roller 1 described above, the core metal 2 and the elastic layer 3 are bonded to each other by extruding a silicone rubber in which a foaming agent and a vulcanizing agent are kneaded in advance with an extruder to form a raw rubber tube. After doing HAV (Hot Air Vulcanizat
ion) method or FBV (Fludized Bed Vulcanization) method to heat-foam to form a silicone sponge tube.
After inserting the core metal 2 coated with an additional adhesive such as E322 (trade name of Toshiba Silicone Co., Ltd.), further heat the adhesive to cure the adhesive to adhere the silicone sponge tube to the core metal 2. The primer NO. Silicone rubber layer obtained by kneading a foaming agent and a vulcanizing agent on the core metal 2 by passing the core metal 2 coated with an adhesive such as 8 (trade name of Shin-Etsu Chemical Co., Ltd.) through a crosshead die of an extruder. May be formed, and then this may be heated and foamed in a constant temperature bath or in a heated mold and simultaneously bonded. In any of the above-mentioned bonding methods, after forming the silicone sponge layer on the core metal, it is necessary to polish the outer periphery of the sponge in order to remove the skin layer formed on the surface and to obtain the accuracy of the outer diameter.

When the elastic layer 2 is made of a soft material such as sponge rubber as in this embodiment, it is necessary to increase the physical strength and elongation of the adhesive layer so that the elastic layer 2 and the elastic layer 2 in the pressure roller can be improved. The durability can be improved without peeling off the fluororesin sleeve 5. In the present embodiment, the elastic layer 2 and the fluororesin sleeve 5 described above are used by using the addition type silicone composition shown in the specific examples 1 and 2 described below in which the tensile strength and the elongation are increased as the adhesive layer. It was possible to prevent the peeling from.

[0021]

Concrete Example 1 A core metal having a total length of 243 mm and an outer diameter of 9 mm is coated with a silicone sponge rubber having a hardness of 30 degrees (Asker C) and then polished to have an outer diameter of 17 mm. KE1830 (trade name of Shin-Etsu Chemical Co., Ltd.), which is a one-component addition type silicone adhesive, was uniformly applied on the surface with a doctor blade, and a PEA sleeve with a thickness of 50 μm, which had an inner surface etched, was inserted.
The pressure roller was molded by heating at 0 ° C. for 1 hour to cure. The surface of the pressure roller produced in this way is 10
A slit with a width of mm is engraved and pulled by the autograph, PF
When an adhesion peeling test was performed between the A sleeve layer and the sponge layer, the adhesive layer was firmly bonded and the peel strength was 1,
It was 000 g / cm. In addition, the above-mentioned adhesive K
As shown in Table 1, the physical properties of E1830 were found to have a tensile strength (MPa) of 3.2 and an elongation (%) of 350, and both tensile strength and elongation were large. The adhesive peeling of the pressure roller was a break in the sponge layer. Then, the above-mentioned pressure roller was attached to a copying machine (trade name: Mini Copia FC-2, manufactured by Canon Inc.) and an actual machine durability test was carried out. As a result, adhesion that would pose a problem even after the 30,000 sheet passing durability test It was found that the agent did not peel off and had sufficient durability.

[0022]

[Table 1]

[0023]

[Example 2] A pressure roller was molded in the same manner as in Example 1 using SE6721A & B (trade name of Toray Silicone Co., Ltd.) as a two-component addition type silicone rubber composition as an adhesive. Since the adhesion between the adhesive layer and the above-mentioned adhesive layer was not always good, P
After the inner surface of the FA sleeve was treated with primers X and Y (trade name of Toray Silicone Co., Ltd.) which are addition type silicone rubber primers, a pressure roller was prepared again in the same manner as in Example 1. It was firmly adhered to the sponge layer via the adhesive layer. When the pressure-sensitive roller thus produced was subjected to an adhesion peeling test in the same manner as in Example 1, the peeling strength was 1,000 g / cm, and the peeling was breakage of the sponge layer. As shown in Table 1 above, the physical properties of the adhesive are tensile strength (M
Pa) was 9.8 and elongation (%) was 650, and it was found that both tensile strength and elongation were strong. Then, this pressure roller is attached to a copying machine similar to that of the first embodiment.
A paper passing test of 000 sheets was carried out, but no problematic peeling of the adhesive was observed.

[0024]

[Comparative Example 1] TSE as a one-component addition type silicone adhesive
A pressure roller was molded in the same manner as in Example 1 except that 322 (trade name of Toshiba Silicone Co., Ltd.) was used, and an adhesive peeling test was performed on the pressure roller in the same manner as in Example 1. The adhesive layer was not so strongly adhered, and the peel strength was 700 g / cm. Moreover, this adhesive peeling surface was mainly an adhesive layer. When the physical properties of the adhesive TSE322 used in this comparative example were measured, the tensile strength (MPa) showed a high value of 3.3, but the elongation (%) was 240, indicating that the elongation was short. Next, when this pressure roller was attached to the copying machine used in Example 1 and a paper passing test was carried out, image disturbance occurred at 10,000 sheets, and the pressure roller was investigated. Of P
A circular bulge of about 10 mm was generated between the FA layer and the sponge layer, and it was found that the adhesive durability was not good.

[0025]

Comparative Example 2 SE which is a two-component addition type silicone composition
1740A & B (trade name of Torre Silicone Co., Ltd.)
A pressure roller was molded in the same manner as in Example 2 except that was used as the adhesive. When this pressure roller was subjected to an adhesion peeling test in the same manner as in Example 1, it was found that the pressure roller was easily peeled off from the adhesive layer, the peeling strength was 10 g / cm or less, and there was no adhesive strength. When the physical properties of the above-mentioned adhesive were measured, it was found that the elongation was as large as 500% and the tensile strength (MPa) was as small as 0.1.

[0026]

The pressure roller according to the present invention is a pressure roller in which the outer periphery of the elastic layer coated on the outer periphery of the core metal is coated with the fluororesin layer having a thickness of 0.1 mm or less, and the breaking elongation is 350. % Or more and the tensile strength is 3 MPa or more, the elastic layer and the fluororesin layer are bonded with an adhesive composed of an addition type silicone rubber composition, so that the adhesion of the fluororesin layer is extremely excellent. It is possible to obtain a pressure roller.

[Brief description of drawings]

FIG. 1 is an enlarged sectional view showing the structure of a pressure roller.

[Explanation of symbols]

 1 Pressure Roller 2 Core Metal 3 Elastic Layer 4 Addition Type Silicone Composition Layer 5 Fluorine Resin Layer

Claims (1)

[Claims] 1. A core metal is coated with an elastic layer on the outer periphery thereof, and further,
In a pressure roller in which the outer periphery of the elastic layer is covered with a fluororesin layer having a thickness of 0.1 mm or less, the breaking elongation is 350%.
A pressure roller characterized in that the elastic layer and the fluororesin layer are adhesively fixed by an adhesive layer made of an addition type silicone rubber composition having a tensile strength of 3 MPa or more.