JPH0128942B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a toner image formed on a support by developing a latent image formed by an electrophotographic method, an electrostatic recording method, an electrostatic printing method, etc. with a toner. The present invention relates to a toner image fixing method for fixing toner images.

Conventionally, various fixing devices have been proposed and known for fixing such toner images.
For reasons such as high thermal efficiency and no risk of fire, for example, a contact made of a rotatable fixing heat roller with a built-in heat source and a pressure roller that rotates in the same direction while being in pressure contact with this heat roller. Heating type fixing devices have been widely put into practical use.

The contact heat fixing method is preferable in various respects as described above, but in this method, the toner image and the fixing heat roller come into contact, so the toner adheres to the heat roller and this toner is absorbed by the subsequent image. This has the disadvantage that it re-adheres to the support that supported the toner image, staining the fixed image. Therefore, it is necessary to clean the toner adhering to the heat roller, and conventional cleaning members such as a cleaning web, a cleaning plate, and a cleaning roller have been used.

However, when such a cleaning member is provided, a so-called backside stain phenomenon occurs. This backside staining phenomenon occurs when the toner material deposited on the cleaning member is subjected to excessive heat, and the toner material is transferred to the heated roller and stains the surface of the support such as transfer paper that is subsequently fed. Furthermore, this is a phenomenon in which the back surface of the support is stained by the toner material that is transferred to the pressure roller that is pressed by the heat roller and transferred to the pressure roller.

When we investigated the cause of such backside staining phenomenon, we found that
It has been found that the elasticity of the toner when it is melted has an important relationship with this back surface staining phenomenon. That is, conventionally, thermoplastic resins mainly composed of styrene-acrylic copolymers have been used as binder resins for toners, but these resins have low elasticity when melted and are easily transferred. Therefore, even if the toner substance is once collected on the cleaning member, when the heater of the heat roller is turned on, for example, the toner substance deposited on the cleaning member may be heated to a temperature 10 to 60°C higher than the set temperature of the heat roller. Then, it is transferred to the heat roller, resulting in the back surface staining phenomenon.

The present invention has been made based on the above-mentioned circumstances, and it is an object of the present invention to provide a toner image fixing method that does not involve the phenomenon of back surface staining.

The purpose of this is to fix a toner image on a member that directly or indirectly contacts the outer peripheral surface of the heat fixing roller in a fixing method in which a support supporting a toner image is brought into pressure contact with a heat fixing roller to fix the toner image on the support. This is achieved by a toner image fixing method characterized in that a releasing silicone oil and an elasticity improver that increases the elasticity of the material of the toner when it comes into contact with the toner are present.

The present invention will be specifically explained below.

In the present invention, in a fixing device equipped with a heat fixing roller for fixing a toner image on a support thereof, a member, such as a cleaning member, provided to directly or indirectly contact the outer peripheral surface of the heat roller, An elasticity improver that increases the elasticity of the material forming the toner of the toner image when melted, specifically a substance that reacts with the resin constituting the binder resin of the toner to increase its molecular weight, and/or Alternatively, an elasticity-improving liquid consisting of a reaction promoting substance that promotes such a reaction and silicone oil with releasing properties is present, and in this state, the support is fed to the fixing device and the toner image supported thereon is prepared. Make it established.

The elasticity improver may be selected depending on the material of the toner forming the toner image. For example, the binder resin of the toner may be a polymer or copolymer made of a widely used acrylic ester component. In the case where the base material consists of aliphatic amines such as propylamine, butylamine, and dodecylamine, and other basic substances are used. This can result in a reaction that crosslinks the acrylic ester moieties, thereby increasing the molecular weight of the polymer or copolymer and, as a result, increasing its elasticity when melted.
In addition, reaction accelerators used in the above reaction include calcium oxide, stearic acid, sulfur, and others. Although the mechanism of the reaction is not clear, it is presumed that Claisen condensation of active hydrogen bonded to, for example, the α-carbon of the acrylic acid moiety in the binder resin occurs.

This elasticity improver is made into a liquid elasticity improver as a whole by using a releasing silicone oil as a carrier liquid, which will be described later, and the members that directly or indirectly contact the outer peripheral surface of the heat roller are made of a porous material. or in combination with a liquid holder;
It is preferable to impregnate and retain the elasticity improving liquid.

Specifically, as shown in FIG. 1, there is a fixing heat roller 1 having a coating layer made of Teflon provided on the outer circumferential surface of a metal drum, and a metal drum disposed in pressure contact with the heat roller 1. A pressure roller 2 is provided with a silicone rubber layer on the outer circumferential surface, a heater 3 is disposed in the inner space of the heat roller 1, and a cleaning roller 4 is provided so as to be in contact with and follow the heat roller 1. In the fixing device, the cleaning roller 4 is formed by forming a liquid retaining layer 6 made of silicone foam rubber on the outer peripheral surface of a metal shaft core 5, and further comprising a heat-resistant nylon felt on the outer peripheral surface of the liquid retaining layer 6. A surface layer 7 is provided, and the liquid retaining layer 6 is impregnated and retained with an elasticity improving liquid. P
is a support, T is a toner, and W is a support passage.

When using an apparatus having such a configuration, the cleaning roller 4 collects the toner adhering to the heat roller 1 on its outer circumferential surface, so that toner substances are deposited on the outer circumferential surface of the cleaning roller 4. Since the elasticity improving liquid has oozed out from the internal liquid retaining layer 6 to the outer peripheral surface of 4, the elasticity of the toner collected or deposited on the outer peripheral surface increases when it is melted. As a result, even if the heater 3 of the heat roller 1 is turned on and the toner material on the cleaning roller 4 is heated and melted, it is prevented from being transferred to the heat roller 1, and as a result, the toner material on the cleaning roller 4 is prevented from being transferred to the pressure roller 2. However, since the toner material does not transfer, it is possible to prevent the back surface staining phenomenon from occurring.

The releasable silicone oil in the elasticity-improving liquid is a heat-stable liquid and serves as a carrier liquid for the elasticity-improving agent. Since this silicone oil having mold releasability is also supplied to the surface of the heat roller, even if only in a small amount, it is possible to obtain the effect of suppressing the toner of the toner image to be fixed from adhering to the heat roller. The ratio of silicone oil and elasticity improver varies depending on conditions, but is 1:
Selected from the range of 99 to 99:1, usually 95 to 50:5
~50.

FIG. 2 shows a liquid supply roller 11 having the same configuration as the cleaning roller 4 in FIG.
The cleaning web 14 is conveyed by the rolls 12 and 13 and is brought into contact with the heating roller 1. According to this example, the toner substance collected and deposited on the cleaning web 14 is melted. The cleaning web 14 has increased elasticity, which reliably prevents the occurrence of contamination on the back surface, and also extends the service life of the cleaning web 14.

FIG. 3 shows a device having a brush type cleaning roller 20, a liquid holding material 21 is provided so as to be in contact with this cleaning roller 20, and this liquid holding material 21 is impregnated with an elasticity improving liquid. Also in this example, the same effects as in the example of FIG. 1 can be obtained.

As described above, according to the present invention, when fixing a toner image using a contact heating fixing method, the elasticity of the toner substance that adheres to the fixing heat roller and then is collected on the cleaning member increases, so that the elasticity increases. Transfer of the toner substance to the heat roller, which would otherwise occur if there was no increase in the amount of toner, does not occur.Therefore, there is no further transfer of the toner substance to the pressure roller, and it is possible to prevent the back surface staining phenomenon, and as a result, the toner material is always kept clean. A fixed visible image can be obtained. Furthermore, in order to prevent the back surface staining phenomenon, it is not necessary to use a binder resin of the toner that has high elasticity when melted, and therefore it is possible to avoid sacrificing the fixing properties of the toner itself. A good visible image is formed even at points.

It goes without saying that the method of the present invention can be carried out using an apparatus having a configuration other than that of the illustrated example.
In addition, the elasticity improving liquid is not limited to being supplied to the cleaning member as in the illustrated example, but a roller-shaped member holding the elasticity improving liquid may be brought into contact with the outer peripheral surface of the fixing heat roller. In this case, the member holding the elasticity-improving liquid is heated upstream of the cleaning area by the cleaning member so that the toner adhering to the heated roller comes into contact with the elasticity-improving liquid and is then cleaned by the cleaning member. Preferably, it is provided opposite the area of the roller.

Examples of the present invention will be described below.

Example 1 An electrophotographic copying machine "U-BixV" (manufactured by Konishiroku Photo Industry Co., Ltd.) was modified to have a fixing device as shown in FIG. Copying was performed 5,000 times using a developer consisting of a toner impregnated with a releasable silicone oil containing 10% by weight of undecene and 10% by weight of stearic acid and containing a styrene-butyl acrylate copolymer as a binder. I did a test.

As a result, almost no stains were observed on either the front or back sides of the 5,000 copies obtained. Furthermore, the toner material on the cleaning roller after the copy test was solidified.

On the other hand, in a similar copying test in which the liquid retaining layer of the cleaning roller was impregnated with only silicone oil, stains appeared on the back side of the copies after 3000 copies were made.

Example 2 Using a releasable silicone oil containing 10% by weight of dodecylamine and 10% by weight of stearic acid.
When a copy test similar to that in Example 1 was conducted using toners mixed and added at a ratio of , similar good results were obtained.

On the other hand, when using silicone oil that does not contain dodecylamine, the number of copies is reduced.
Around the 3000th cycle, staining on the back surface was observed.

[Brief explanation of drawings]

FIGS. 1 to 3 are explanatory sectional views each showing an example of the structure of a fixing device suitably used in carrying out the method of the present invention. 1... Heat roller, 2... Pressure roller, 3... Heater, 4... Cleaning roller, 5... Axis core,
6...Liquid holding layer, 7...Surface layer, 11...Liquid supply roller, 12, 13...Roll, 14...Cleaning web, 20...Brush type cleaning roller, 21...Liquid holding material.

Claims (1)

[Scope of Claims] 1. In a fixing method in which a support supporting a toner image is brought into pressure contact with a heat fixing roller to fix the toner image to the support, the toner image is directly or indirectly contacted with the outer circumferential surface of the heat roller for fixing. 1. A method for fixing a toner image, characterized in that a releasable silicone oil and an elasticity improver that increases the elasticity of the material of the toner when it comes into contact with the toner are present in the member. 2. The toner image fixing method according to claim 1, wherein the elasticity improver is a substance that causes a reaction that increases the molecular weight of the binder resin of the toner and/or a reaction promoter for such a reaction.