JPS63304283A - Fixing device - Google Patents

Abstract

PURPOSE:To prevent winding of paper on a press roller, offsetting and bleeding of a line image by forming a surface layer of one roller of an elastic material and adding a surfactant into the elastic material. CONSTITUTION:A fixing roller 1 is driven to rotate by the press roller 3 which is pressurized by a spring, etc. The press roller 3 is constituted by forming the elastic material layer 3B consisting of silicone rubber, fluoroplastic, etc., having heat resistance and release property on an arbor 3A consisting of iron, stainless steel, etc. The surfactant 3B' is dispersed and incorporated into the elastic material layer 3B. The electrostatic charge of the press roller can, therefore, be suppressed in the friction between the paper and the press roller and the attenuation in the surface potential of the press roller is expedited. The generation of the winding of the paper on an image carrier, the bleeding of the line image, the offsetting of a toner, etc., is thereby obviated.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention is used in the field of fixing technology in electrophotographic devices or electrostatic recording devices. The present invention relates to a fixing device that clamps and conveys a carrier material and fixes it under pressure.

(Prior Art and Problems) Conventionally, this type of fixing device includes a fixing roller and a pressure roller that is in pressure contact with the fixing roller and rotates as a result of the fixing roller.

The fixing roller is formed by coating a hollow core metal 9 made of aluminum, iron, or the like with a layer of a material with good mold releasability, such as PTFE, PFA, or silicone rubber. Further, the fixing roller is provided with a heater such as a halogen lamp, if necessary, to raise the temperature of the surface of the fixing roller to a temperature suitable for fixing. Further, in many cases, a sensor is used to control the surface temperature of the fixing roller so that it reaches a set temperature.

Further, the outer peripheral surface of the fixing roller is provided with a cleaner for removing offset toner and paper dust, and a separating claw for preventing the image bearing material from being wrapped around the fixing roller.

On the other hand, the pressure roller has a core metal such as iron or stainless steel covered with an elastic layer having mold releasability such as silicone rubber. The pressure roller is pressed against the fixing roller by a spring or the like.

In this manner, the image bearing material carrying the unfixed toner image is conveyed while being held under pressure by the fixing roller and the pressure roller, and the unfixed toner image is fixed under pressure.

However, in the above-mentioned conventional device, the pressure roller wears during paper feeding. ! There was a problem in that the paper was charged to, for example, 2 kV or more, and the paper wound around the pressure roller. Further, due to the electric field of the pressure roller, unfixed toner scatters and blurs the line image, and toner adheres to the surface of the fixing roller, resulting in increased offset.

As a countermeasure to the above-mentioned problem, conventionally, a charge removal brush was brought into contact with the pressure roller to perform ground charge removal.

However, even with this measure, the potential drops to only about 1 to 2 kV, which limits the static elimination effect and is not sufficient, and an improvement has been desired.

(Means for solving Question 1) The present invention solves the above-mentioned particular problems and suppresses the charging of the pressure roller, thereby preventing paper wrapping of the image bearing material, blurring of line images, and toner An object of the present invention is to provide a fixing device that does not cause offset or the like.

In order to achieve the above object, the present invention provides a fixing device that pressurizes and fixes an unfixed toner image formed on an image bearing material by sandwiching and conveying the image bearing material between a pair of rollers. It is constructed by using an elastic body as the surface layer of the roller, and adding a surfactant to the elastic body.

Furthermore, in order to achieve the above object, in addition to the above structure, a mold release agent to which a surfactant is added is applied to the surface layer of at least one of the rollers.

(Example) Hereinafter, the present invention will be described in detail based on the accompanying drawings.

FIG. 1 is a vertical sectional view showing the II essential structure of the constant M device of this embodiment. In the same figure, ■ is a fixing roller, and the fixing roller l is a core metal 1 made of aluminum, iron, stainless steel, etc.
A resin layer IB made of PFA, PTFE, etc. having heat resistance and mold releasability is formed on the outer surface thereof.

A pressure roller 3 is pressed by a spring or the like (not shown) and rotates as a result of the fixing roller I. The pressure roller 3 has an elastic layer 3B made of silicone rubber, fluororubber, or the like having heat resistance and mold releasability formed on the core metal 3 made of iron, stainless steel, or the like. This elastic layer 3B contains a surfactant 3B'' dispersed therein.

Around the fixing roller 1, there is a thermistor 4 that detects the temperature of the fixing roller 1, a separation claw 5 that separates the paper sheet 14, which is an image bearing material, from the fixing roller 1, and a separation claw 5 that comes into contact with the fixing roller 1 to clean its surface. A cleaner 6 for cleaning, an entrance guide 11 for guiding the paper confectionery between the fixing roller l and the pressure roller 3, and the like are provided.

On the other hand, a conductive plate spring i5 for grounding is in contact with the core metal 3B of the pressure roller 3.

The apparatus of this embodiment is constructed as described above, but since experiments were conducted on each part under various conditions, a description will be given here showing specific numerical values.

[Experiment example 1] As a standard roller L, straight f ¥251 ugly, wall thickness 0.8 ■■
An aluminum cored pipe coated with a PFA layer of 25 mm was used, and the pressure roller was made of silicone rubber with a thickness of 51 mm attached to a stainless steel core shaft with a diameter of 1 mm. . The hardness of this silicone rubber is J l5-
Results of measuring test pieces based on A standard! 6''.Furthermore, the heater 2 was controlled so that the surface of the fixing roller 1 was at about 180°C.

In the conventional example, silicone rubber is used as it is.

As shown by the broken line in FIG. 2, the surface potential of the pressure roller becomes more than 12 kV due to friction with the paper. Therefore, in one experiment, a fluorinated alkyl ester, which is a fluorine-based surfactant, was added to this silicone rubber at a concentration of 0:1 from 0.0 old gastric Lz.
When the pressure was dispersed between wL$, it was confirmed that the surface potential of the pressure roller 3 during sheet feeding was as low as -1 kV or less, as shown by the solid line in the second UA.

The solid line and the broken line shown in FIG. 2 show changes in the surface potential of the pressure roller over time, comparing the changes in the surface potential of the pressure roller when one sheet is printed using the product of the present invention and the conventional product, respectively. As is clear from the figure, the effect of adding a fluorine-based surfactant into the silicone rubber is that it can suppress the charging of the pressure roller due to the friction between the paper and the pressure roller.
The next objective is to speed up the attenuation of the surface potential of the pressure roller.

As a result, wrapping of paper sheets around the pressure roller no longer occurs, and the amount of toner accumulated in the cleaner 6 that is in contact with the fixing roller l is less than 1/1O compared to the conventional case, reducing offset. It was confirmed that it did. Furthermore, line image blur no longer occurs on the image.

In the present invention, preferred surfactants include fluorine-based surfactants. The reason is that it is more heat resistant than other surfactants.

The surface temperature of the rubber layer of the pressure roller reaches 110° C. or higher, which causes the splitting of ordinary surfactants, but fluorine-based surfactants do not decompose and maintain their effectiveness.

[Experimental Example 2] In the above-mentioned [Experimental Example 1], a fluorinated alkyl ester was used as the fluorine-based surfactant, but in addition, perfluoroalkyl polyoxyethylene ethanol and perfluoroalkyl carboxylate were used.

Perfluoroalkyl ammonium salts, perfluoroalkyl betaines, perfluoroalkyl amine oxides, perfluoroalkyl ethylene oxide adducts, perfluoroalkyl phosphate esters, non-dissociable perfluoroalkyl compounds and EFTOP manufactured by Mitsubishi Metals Corporation
-EF122B (product name) etc. are also effective.

In addition, the dispersion ratio of the fluorine-based surfactant to the silicone rubber was set to 0.1wt1 in the above-mentioned [Experimental Example 1], or preferably between 0.00:1wL$ and 0.3wt1, which is better. Preferably 0.01 kou (0.1 w from $
T! Good.

The limit value here was determined based on the effect of reducing surface tension, which is the main effect of surfactants. The reason for this is that the effects targeted by the present invention, which are the effects of reducing the surface potential and accelerating the attenuation of the surface potential, become more significant as the surface energy is lowered. 1Surface energy is correlated with surface tension. Therefore, based on FIG. 3 showing changes in surface tension, the concentration required to obtain the desired effect of the present invention is determined.

For example, it can be said that an effect of 1/2 or more of the saturation level had a sufficient static elimination effect, but for that purpose a minimum of 0. Ot1
It can be seen that a surfactant concentration of about 3 wL$ or more is sufficient. Also, if more than 0.01 wL$ is mixed in, the surface tension will be lowered almost to its limit, and the static elimination effect will also reach its limit. Therefore, it is preferable to add the surfactant at a concentration of 0.00'l<11> or more, more preferably 0.01 wt$ or less.

On the other hand, if too much surfactant is added, curing of the rubber will be inhibited, so this will determine the upper limit of the amount added. From this, it has been found that the amount of surfactant added is preferably 0.3 wt$ or less, and more preferably 0.1 wt$ or less.

In this experimental example, the pressure roller may be grounded by applying a plate spring to the core metal, or by performing static neutralization with a brush as in the conventional case. Further, a bias voltage having a polarity opposite to the frictional charging potential of the pressure roller may be applied to the brush or the leaf spring to increase the static elimination effect.

[Experimental Example 3] In the aforementioned experimental example, a fluorine-based surfactant was added to the rubber of the pressure roller, but the surfactant may come out of the rubber after long-term use. For example, the above [Experiment Example 1]
However, when more than 100,000 sheets of A4 size paper are printed, the surfactant tends to escape from the rubber and the anti-offset and anti-wrapping effects tend to decline.

Therefore, a fluorine-based surfactant was added to the silicone oil impregnated into the cleaning felt of the cleaner 6 as shown in FIG. 1, and the mixture was supplied to the surface of the pressure roller via the fixing roller.1- Good results were obtained that changed the previous trend.

Specifically, a cleaner felt made of woven aromatic polyamide-imide fibers with a density of 0.15 g/cm' was used, with a thickness of 6 am, a diameter of 1/2, and a total length of 220/2. Also, add 2g of dimethyl silicone oil (F-96, 10,000cs manufactured by Shin-Etsu Silicone Co., Ltd.) to this.
Add 0.06g of fluorinated alkyl ester to this silicone oil and apply it to the fixing roller at a rate of about 0.5mg per sheet of A4 size paper4.011
It was assumed that the felt would be replaced if there was no felt.

As a result, the surface potential of the pressure roller could be maintained at 11 kV or less over 200,000 sheets or more, and the offset prevention effect and paper wrapping prevention effect could be maintained.

In this case, a fluorinated alkyl ester was used as the surfactant, but the surfactant may be selected from among the various fluorine-based surfactants listed in Experimental Example 2 above.

Furthermore, the fluorine-based surfactant added to the silicone rubber of the pressure roller and the fluorine-based surfactant added to the silicone oil may be a different combination.

In addition, the lower limit of the fluorine-based surfactant added to silicone oil is 0.00 wLx for the same reason as the above experimental example.
It is preferably at least 0.01wt1 or more. Also, depending on the type of fluorine-based surfactant, is it possible to add it to silicone oil? There are some substances that cause gelation, which will be determined from now on. Silicone oil did not gel with most fluorine-based surfactants at 3wt$ or less. Furthermore, since fluorine-based surfactants are expensive, the less the better. In terms of effectiveness, sufficient effects can be obtained even with 1wL$, so for practical use, 0.00:L is preferable.
Between 豐tX and 3wt$, more preferably 0.01wL
A value between $1 and 1wL$ is good).

Alternatively, a felt impregnated with silicone oil containing a fluorine-containing surfactant may be brought into direct contact with the surface of the pressure roller 3. This allows the fluorine-containing surfactant to be applied to the surface of the pressure roller more efficiently. can be supplied to

In the above cases, including this experimental example, when the pressure roller has multiple rubber layers, it is sufficient to add the fluorine-based surfactant only to the outermost rubber layer. As a result, the amount of use of the fluorine-based surfactant can be reduced, making it possible to obtain the desired performance at low cost.

[Experimental Example 4] In the following experimental example, a fluorine-based surfactant was used because the temperature of the fixing roller l was as high as about 180°C. However, since the melting point of the toner itself is lowered to fix the toner at a fixing roller temperature of about 140°C, in this case, the surface temperature of the pressure roller 3 is only around 90°C. Therefore, the decomposition temperature of the surfactant added to the pressurized [1-ra] may be less than 1-too'c, and even surfactants other than fluorine-based surfactants with low heat resistance can be used.

(Effects of the First Sword) As described in 1- above, the present invention provides an apparatus for pressure-fixing an unfixed toner image formed on an image-bearing material by sandwiching and conveying the image-bearing material between a pair of rollers. Since the surface layer of at least one roller is made of an elastic material and a surfactant is added to the elastic material, the surface potential of the pressure roller is reduced.

By suppressing the attenuation of the potential, it is possible to prevent phenomena such as wrapping of paper around the pressure roller, offsetting, and blurring of line images.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of the device of the present invention, FIG. 2 is a diagram showing changes in surface potential of the pressure roller in an embodiment of the device shown in FIG. 1, and FIG. FIG. 3 is a diagram showing a decrease in surface tension due to the addition of a chemical agent. ■, 3...Roller (l...Fixing roller, 3...Pressure roller) 2...Heating means (Heater) 8
・・・・・・・・・・・・Surface layer (elastic body) 3[1′・
... Surfactant μm, -) Fig. 2 Engraving of the passing period drawing, 001. 01. 1 1
Surfactant solid content concentration (wtχ) Procedural official document (method) September 16, 1985 Director General of the Patent Office Kunio Ogawa 1, Indication of the case 1988 Patent application No. 139917 2, Title of the invention Fixing device 3, relationship with the amended person case Patent applicant address 3-30-2 Shimomaruko, Ota-ku, Tokyo Name (100) Canon Co., Ltd. Representative Kaku
Ryu Sanbu 4, Agent 8150 Telephone 03-770-904
0 August 5, 1988 (shipment date: August 25, 1988) 6. Drawings subject to amendment

Claims (7)

[Claims] (1) In a fixing device that pressurizes and fixes an unfixed toner image formed on an image bearing material by conveying the image bearing material between a pair of rollers, the surface layer of at least one of the rollers is made of an elastic material, A fixing device characterized in that a surfactant is added to the elastic body. (2) The fixing device according to claim (1), wherein at least one of the rollers has heating means. (3) Claim (1) or (3) characterized in that the decomposition temperature of the surfactant is 100 degrees Celsius or higher.
The fixing device described in section 2). (4) The amount of surfactant is 0.001 relative to the amount of elastic body.
% by weight to 0.3% by weight.
) The fixing device described in section 2. (5) The fixing device according to claim (3), wherein the surfactant is a fluorine-based surfactant. (6) The fixing device according to claim (1), wherein the elastic body is made of silicone rubber or fluororubber. (7) In a fixing device that pressurizes and fixes an unfixed toner image formed on an image bearing material by conveying the image bearing material between a pair of rollers, the surface layer of at least one of the rollers is made of an elastic material, A fixing device characterized in that a surfactant is added to the elastic body, and a release agent to which the surfactant is added is applied to the surface layer of at least one of the rollers.