JPH0812522B2 - Fixing device and fixing roller - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a fixing device and a fixing roller used in an electrophotographic apparatus or an electrostatic recording apparatus.

(Prior Art and Problems) Conventionally, a fixing device for fixing a dry resinous developer (hereinafter referred to as a toner) image has a form such as pressure fixing, heat fixing, and heat pressure fixing. In terms of the quality and fixability of a fixed image, thermal fixing including thermal compression fixing is generally the mainstream. In particular, a heat roller fixing device is mainly used from the viewpoint of simplicity and safety of the fixing device.

The heat roller fixing fixes a toner image by sandwiching and carrying a support material having an unfixed toner image between a pair of heated rollers.

As for the material of each roller, the fixing roller that comes into direct contact with the toner image has a hollow cylinder made of aluminum and a high release material such as fluororesin (for example, PFA, PTFE) formed in a thickness of several tens of μm. The other roller, which is used as the pressure roller that comes into pressure contact with the fixing roller, is formed with a heat resistant rubber such as silicon rubber or fluororubber on a hollow metal cylinder such as aluminum or stainless steel with a thickness of several mm. What is done is used. In the above-mentioned constitution, the surface temperature of the fixing roller is set to 180 to 200 ° C.,
In addition, the contact width (hereinafter referred to as the nip width) of the pressure roller and the fixing roller in the circumferential direction is 6 to 10 mm and the contact pressure is 5 to 5.
Fixing is performed under the condition of 10's of kg / cm ² .
In this fixing method, the toner image and the support material are sufficiently heated to melt the toner image and fix the toner image on the support material.

However, the conventional fixing roller surface material is PFA, P
Since it is a fluororesin such as TFE, abrasion and peeling are caused by contact of a separation claw for separating the supporting material having the toner image from the fixing roller, contact of a temperature sensor, and passage of paper as a supporting material. It has the drawback of causing That is, not only the quality of the fixed image is significantly deteriorated by the above-mentioned wear and peeling, but also the contact pressure of the separation claw must be reduced to prevent the wear, and as a result, a paper jam called a jam easily occurs. .

Therefore, it is required to reduce wear without lowering the contact pressure of the separation claw. As a countermeasure, the present situation is to prevent the paper jam and prevent the abrasion by gradually changing the contact position of the separation claw. However, this method has a drawback that the apparatus becomes complicated. Further, abrasion beyond a certain level due to the passage of paper is unavoidable. On the other hand, in JP-A-52-23946, a roller having a diameter of several tens to several thousand Å is formed on the surface of a good heat conductor such as metal, and a roll impregnated with an offset preventing material made of fluororesin is used as a fixing roller. There is something to use. However, metals such as aluminum and copper, which are generally said to be good thermal conductors, have low hardness, and if the separation claws are brought into contact with high pressure to prevent paper wrapping, scratches will occur and the durability of the fixing roller will be reduced. Go against improvement.

(Means for Solving Problems) An object of the present invention is to solve the problems of the above-described conventional device and to provide a fixing device and a fixing roller having wear resistance and a releasing effect by a lubricant. There is.

In a fixing device which has a pair of rollers in pressure contact with each other, and which carries and fixes a recording material carrying an unfixed toner image at a pressure contact portion of the roller pair, at least one of the roller pairs is made of an anodized aluminum film. This is achieved by the impregnation and film formation of an anionic or cationic perfluoroalkyl compound on the fine pores and the surface by electrolysis.

Further, regarding the fixing roller, it is also possible that the anionic or cationic perfluoroalkyl compound is impregnated and formed into a film by electrolysis on the fine pores and the surface of the aluminum anodic oxide film.

Embodiment An embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a schematic vertical sectional view of a fixing device F of the embodiment apparatus. This fixing device mainly includes a fixing roller 1, a pressure roller 2, a separating claw 5, and a release agent applying device 6.

The fixing roller 1 has a heat source 3 such as a halogen heater for heating therein. The temperature sensor 4 in contact with the peripheral surface detects the surface temperature of the fixing roller 1, and a temperature control device (not shown). The surface temperature is adjusted by turning on / off the internal heat source 3 by (4).

On the other hand, the pressure roller 2 is pressed against the fixing roller 1 by a spring or the like (not shown) to form a nip portion N.
Further, in the nip portion N, the support material 8 having the unfixed toner image 7 formed by a known electrophotographic method is nipped and conveyed, so that the toner image is fixed to the support material 8.

Next, the fixing roller 1 of the present invention is shown in FIG.
This will be described in detail using (b). 2 (a) and 2 (b) are partially enlarged cross-sectional views of the surface of the fixing roller 1 of the present invention.
First, (a) will be described. A core metal 42 made of aluminum or an aluminum alloy is formed into alumite (Al ₂ O ₃ ) with a thickness of several μm to several tens of μm by a known anodic oxidation method.
FIG. 2 (a) shows what can be obtained by forming the layer 43 of FIG. 3B, and then filling the fine holes 45 existing in the alumite layer 43 with the solid lubricant. Fine holes here
45 is an aluminum core metal 42 from the surface of the alumite layer.
And has an active layer (barrier layer) 44 at the interface with the aluminum cored bar 42. The diameter of the fine holes 45 varies depending on the treatment liquid used for the anodizing treatment, but is preferably about 100 to 500Å, and the number of pores is 5 to 40% of the treated area of the aluminum surface, preferably 10 to 40.
It is preferable to select the processing liquid so that the percentage of the opening area is occupied by the holes. For example, using a 4% phosphoric acid bath, 20V at 24 ℃
When the anodization is carried out under the voltage of, the pore diameter becomes 330Å and the opening area occupied by the pores becomes 16-18%. Further, in the case of alumite by sulfuric acid treatment, which is generally obtained as a hard film,
The pore size obtained is 100-150Å, but the number of pores can be increased by the applied voltage, so that an opening area of 10-20% can be obtained.
The aluminum anodic oxide film obtained as described above is dipped in water of an anionic or cationic fluorine compound or a mixed solution of water and a medium such as isopropanol, and the anodized aluminum roller is used as an electrode for direct current. Alternatively, by applying an AC electric field, the above-mentioned fluorine compound is accumulated in the fine holes 45 in the anodized film from the bottom of the holes, whereby the desired fixing roller 1 is obtained. The fluorine compound agent used here comprises a perfluoroalkyl phosphate ester, a perfluoroalkylcarboxylic acid salt, a perfluoroalkyltrimethylammonium salt and the like, and is generally called a fluorine-based surfactant. Further, in order to ensure the durability of the fixing roll 1 sufficiently, the fine holes 45 have a depth of 5 μm or more, preferably 10 μm or more, and the depth from the bottom to the surface is almost in the fine holes. It is desirable that 80% or more of the micropores are completely filled with the fluorine compound. However, if the depth of the fine pores 45 is 50 μm or more, the hardness of the anodic oxide film formed is reduced, and many fine pores not filled with the fluorine compound are not suitable for practical use.

The examples having the anodic oxide film obtained by the primary electrolytic treatment have been described above. However, in order to further increase the opening area ratio, as shown as another example in FIG. The coating may be chemically dissolved. Alternatively, by electrolyzing in a phosphoric acid bath, it is possible to expand the micropores, increase the filling amount of the above-mentioned fluorine compound, and increase the area exposed at the surface of the fluorine compound, thereby improving the releasability. It is possible. In particular, since the fluorine compound, which is a release agent, has poor ductility, it is difficult for the entire surface of the fixing roller to be covered with the fluorine compound, and the enlargement of fine pores is more effective. However, since the enlargement of the fine pores reduces the hardness of the anodic oxide coating itself, the pore diameter can be up to 2 in the practical range.
It is desirable to keep the magnification up to 2.5 times.

Next, as still another embodiment of the present invention, the filler is not a perfluoroalkyl compound alone, but other water repellent,
It is also possible to use together with a fatty acid metal salt having a high lubricating property or a metal sulfide. In particular, fatty acid metal salts are
In general, it is excellent in ductility, and also exhibits a desirable effect in terms of compensating for the poor ductility of the perfluoroalkyl compound. However, since the fatty acid metal salt generally has a low melting point, it is necessary to appropriately set the mixing ratio with the perfluoroalkyl compound and the type of the fatty acid metal salt depending on the use temperature of the fixing roller. That is, in the constant use at 200 ° C. or higher, it is preferable that the mixing ratio of the perfluoroalkyl compound is 50% or more and the fatty acid metal salt used is magnesium oleate or the like having relatively high heat resistance. In addition, sodium stearate or the like can be used when used at about 150 ° C. Typical examples of fatty acid metal salts applicable to the present invention are shown below. In particular, salts of magnesium, potassium, sodium and the like are water-soluble, which is preferable in terms of production cost. Examples include potassium stearate, sodium stearate, potassium palmitate, sodium palmitate, magnesium oleate and the like.

It is also possible to fill the above-mentioned metal sulfide, such as molybdenum disulfide, with the perfluoroalkyl compound into the fine pores in the anodized film. In this case, since the metal sulfide itself has a high heat resistant temperature and high corrosion resistance,
It withstands higher temperatures than the above fatty acid metal salts. Further, like the fatty acid metal salt, the metal sulfide has a good ductility, so that it is possible to compensate for the poor extension of the fluorine compound. As usable metal sulfide, molybdenum disulfide,
Tungsten sulfide etc. are good.

Further, it is also possible to use a mixture of the aforementioned metal sulfide, fatty acid metal salt, and ionic perfluoroalkyl compound.

The solid lubricants that can be used in the present invention have been described above. Next, the filling method of these solid lubricants will be described. The filling method is not only the filling method by electrolysis of the ionic perfluoroalkyl compound described above, but also the electrolytic method in which a metal is electrodeposited in the fine pores in the anodic oxide film and then a reverse electric field is applied to this metal. By the third electrolytic method in which the ionic perfluoroalkyl compound is filled in such a way that it is eluted into the electrolytic solution and replaced with it.
Further, according to this third electrolysis method, when a metal is eluted, by mixing a water-soluble fatty acid or a sulfide in the electrolytic solution, a fatty acid metal salt or a metal sulfide is formed between the metal and the above metal. It is also possible to generate and fill with the perfluoroalkyl compound at the same time. This method has a larger filling amount than the method of directly coating or melting and dipping the three types of solid lubricants, and is a particularly desirable method.

(Effects of the Invention) As described above, according to the present invention, a perfluoroalkyl compound simple substance having a polar group, a metal sulfide, or a fatty acid metal salt is formed into fine pores of a film obtained by anodizing the surface of aluminum by an electrolytic method. Since the filled one is used as the surface of the fixing roller, the following effects are brought about.

The surface hardness is more than 10 times that of the conventional fluororesin coated type, the roller surface is not scraped by the contact of the resin separating claw, and the image stability is improved and the durability is higher than that of the conventional fixing roller. Also increases.

The contact pressure of the separation claw can be increased more than before, and the jam of the transfer paper is significantly reduced.

[Brief description of drawings]

FIG. 1 is a sectional view of a fixing device using a fixing roller as an embodiment of the present invention, and FIGS. 2 (a) and 2 (b) are sectional views showing an enlarged surface of the fixing roller of FIG. 1 ... Fixing roller 2 ... Pressure roller 3 ... Heat source 42 ... Core metal (aluminum core) 43 ... Coating (alumite layer)

Claims (2)

[Claims] 1. A fixing device comprising a pair of rollers which are in pressure contact with each other, and a recording material carrying an unfixed toner image is nipped and conveyed at a pressure contact portion of the roller pair, and at least one of the roller pair is made of aluminum. An anionic or cationic perfluoroalkyl compound is impregnated and formed into a film by electrolysis on the fine pores and the surface of the anodic oxide film. 2. A fixing roller, wherein an anion-based or cation-based perfluoroalkyl compound is impregnated and formed into a film by electrolysis on the fine pores and the surface of an anodized film of aluminum.