JP2001287230A - Application mold for molding endless belt and method for molding endless belt - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an application mold for molding an endless belt which can prevent lifting from the mold up to curing treatment in the molding of the endless belt by centrifugal molding and improve easiness of peeling the endless belt after curing treatment. SOLUTION: When a coating solution is applied on a peeling layer 42 as the inner wall surface of an approximately cylindrical mold main body 41, and the solution is dried to form a coating film, the surface of the layer 42 is low in peelability and compatible with a solvent, and when the coating film is cured, the layer 42 is high in peelability and incompatible with the solvent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a copying machine,
The present invention relates to a metal endless belt used for an image forming apparatus such as a printer and a facsimile machine, and more particularly to a coating die for forming the endless belt by centrifugal molding and a method of forming an endless belt using the coating die.

[0002]

2. Description of the Related Art Conventionally, an image forming apparatus such as a copying machine, a printer, a facsimile, and the like, heats a toner on transfer paper at the time of image formation by heating with a heating element.

In recent years, as a means for increasing the processing speed, it is conceivable to improve the heating and heating speed of the heating element. As an example, as shown in FIG. An endless belt 3 is provided between at least two shafts of the above, and a belt fixing method in which toner is fixed by rotating the endless belt 3 is seen.

On the other hand, as a method for forming such an endless belt 3, a method using a centrifugal molding method as disclosed in JP-A-11-170284 and JP-A-11-320586 is known. .

[0005] This centrifugal molding method, as shown in FIG.
The coating liquid is poured into the rotating cylindrical coating die 4, and the thickness of the coating liquid is made uniform by high-speed rotation centrifugal force to form a coating film 3 ′. It is cured to form an endless belt 3 (in FIG. 5, apparently the same as the coating film 3), and is peeled from the coating die 4 in this state.

In the endless belt 3 formed by such a centrifugal molding method, the film thickness can be arbitrarily adjusted by adjusting the injection amount of the coating solution, and the injection amount of the coating solution is minimized. As a result, the efficiency of the material can be improved, and since the interior of the coating mold 4 is a closed space, when removing the solvent, a solvent trap is provided in the exhaust path to efficiently remove the solvent discharged to the outside. There are excellent advantages such as being able to be recovered.

[0007]

However, when the endless belt 3 is formed by such a centrifugal molding method, there is a problem that the formed endless belt 3 sticks to the coating die 4 and cannot be easily separated. Had occurred.

Therefore, it is conceivable to improve the releasability of the endless belt 3 by providing various releasable material layers 4b (for example, glass or fluorine resin) on the inner surface of the mold body 4a of the coating die 4. Can be

When such a releasable material layer 4b is provided, the coating film is adhered to the inner wall of the coating mold 4 until the coating liquid is dried to form a coating film 3 ', so that the coating film does not have thickness unevenness. It has the advantage of obtaining 3 '.

On the other hand, when the coating film 3 'is heated in the curing reaction stage, the coating film 3' before the endless belt 3 starts to float from its peripheral portion, and in extreme cases, the entire film floats. In addition, the floating portion shrinks unevenly, and the endless belt 3 having a desired diameter cannot be formed.

Therefore, as a countermeasure, the coating film 3 'is peeled off from the coating mold 4 once the coating film is dried to the touch dry level, and a cylindrical mold is newly inserted inside the coating film 3'. A method was employed in which the endless belt 3 was obtained by heating and curing the coating film 3 'in the state.

However, in such a molding method,
Since the drying step and the curing step of the coating film 3 'are completely independent and separate operations, a basic problem that the number of working steps is increased newly occurs, and the releasable material layer 4b and the coating film 3' If air enters between the endless belt 3 and the air, the deformed endless belt 3 is formed without being able to escape.

In order to prevent air from entering between the release material layer 4b and the coating film 3 ', a clearance for inserting a cylindrical mold inside the coating film 3' is increased. In this case, the shrinkage becomes uneven, and the endless belt 3 is wrinkled.

Therefore, it is desirable to form the endless belt 3 while the coating film 3 'is formed by the coating die 4 using the releasable material layer 4b, and the floating of the endless belt 3 is generated from the peripheral portion. Attention was paid to the fact that the periphery was held down by a ring during drying and curing of the coating film 3 ′ to prevent floating.

This method is a useful means, and the coating film 3 '
It has been found that when the peripheral portion of the belt is pressed accurately, a good endless belt 3 can be obtained without floating as it is. However, the ring cannot be set accurately at a predetermined position, or the ring and the coating film 3 ′ cannot be obtained. It has been found that when a gap is generated between the coating film 3 ′ and the coating film 3 ′, the coating film 4 is lifted from the coating die 4, and the installation of the ring requires careful attention and skill, and a product of stable and constant quality. It was difficult to provide.

The present invention, in consideration of these problems and the like, can prevent the occurrence of floating while improving the releasability, and can also prevent the work process from becoming complicated and highly skilled. It is an object to provide an endless belt that can be used.

[0017]

According to a first aspect of the present invention, there is provided a coating die for forming an endless belt, wherein a coating liquid is applied to an inner wall surface of a substantially cylindrical mold body. When the coating liquid is dried to form a coating film, the surface of the inner wall surface is made to have a low lipophilic property of a solvent-philic property, and when the coating film is cured, the inner wall surface has a high releasing property. The gist is that it is lyophobic.

According to a second aspect of the present invention, in the coating die for forming an endless belt, the inner wall surface is made of a fluorine-based highly releasable material, and the inner wall surface changes to a solvent-philic property by heating a corona charger. The gist is that it has been done.

The coating die for forming an endless belt according to claim 3, wherein a length of a charging portion of the corona charging device is shorter than a width of the inner wall surface and substantially equal to a width of the endless belt.
The gist of the present invention is that the peripheral portion of the inner wall always maintains the solvent-phobicity.

According to a fourth aspect of the present invention, in the coating die for forming an endless belt, a relative position between the charging portion and the inner wall surface is determined by rotation of a rotating portion that is driven when the mold body is rotating. The gist of the present invention is to heat the inner wall surface in a state where the inner wall is heated.

According to a fifth aspect of the present invention, in the method of forming an endless belt, the inner wall surface of a substantially cylindrical mold body having a high lyophobic property is rendered lyophilic by corona charging, and then a coating liquid is applied to the inner wall surface. Then, after forming the coating film by centrifugal force accompanying the rotation of the mold body, the coating solution is cured, the coating film is cured to form an endless belt, and then the inner wall surface is changed to solvent-phobic. Make a summary.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of a coating die for forming an endless belt according to the present invention will be described with reference to the drawings.

In FIG. 1A, reference numeral 40 denotes a coating type. The coating mold 40 includes a substantially cylindrical mold body 41,
Release layer 4 as inner wall surface located inside mold body 41
2 and a corona charging device 43 inserted into the release layer 42.

The release layer 42 is formed of a fluororesin film or the like having a high release property.
And a non-charging portion 42b positioned at both ends (periphery) of the coating solution applying portion 42a to maintain the solvent repellency.
And

The corona charging device 43 is shown in FIGS.
As shown in (D), a pair of left and right rollers 43b shown in the drawing, which rotate in contact with the release layer 42, are fixed between the rollers 43b, and the relative position of the release layer 42 is fixed by the rotation of the rollers 43b. Shaft 43c, mounting legs 43d provided near both ends of the shaft 43c, and a charging portion 43a provided between the mounting legs 43d.

Next, a method of forming the endless belt 3 using the coating die 40 will be described.

[Conditions] Conditions for forming a good endless belt 3 include the following. 1. Since the floating of the film at the time of heating always starts from the peripheral portion, it is sufficient to prevent the floating of the peripheral portion at the time of curing. 2. In order to prevent the peripheral portion from floating, it is sufficient that the coating film has adhesiveness only in the peripheral portion region. 3. The image forming area in the center of the coating film preferably has a smooth surface that does not affect the image. 4. If the adhesiveness with the coating die is high, the peripheral portion is extremely bent at the time of peeling, so that it is better that the adhesiveness with the coating film is small. 5. The adhesion between the coating type and the coating film depends on the affinity of the coating film material and the coating liquid coating material (there is low releasability if it is solvent-philic,
The degree of releasability is high if solvent repellency is high), and a solvent repellent material having high releasability such as fluororesin is preferable for easy peeling. 6. Since it is better that the affinity with the coating mold when the coating liquid is applied is small, a solvent-philic material having low releasability is preferred. 7. It is preferable to use a lyophilic material having good wettability so that the peripheral portion does not float.

Although there is no substance which simultaneously fulfills the above-mentioned conditions 5 to 7 with the same substance, solubilizing and lyophobic properties at the same time,
By carrying out a certain treatment, both characteristics can be reversibly expressed.

As one of them, a fluororesin (solvent-phobic) having a high releasability is changed to a solvophilic property by corona charging the surface, and then the releasability is restored by leaving it to stand. be able to.

Therefore, as shown in FIG. 1 (A), when the release layer 42 of the coating die 40 is formed of a fluororesin film using such a substance, and the coating liquid 3 'is applied to the corona-charged surface. By improving the adhesiveness and recovering the releasability during the subsequent drying and curing, it is possible to easily prevent the floating of the endless belt 3 during the molding process and easily ensure the releasability at the end of the molding.

In order to make the corona charging amount uniform, the distance between the rotating inner wall surface (release layer 42) of the coating die 40 and the charger (charging portion 43a) should be maintained at a constant interval. Therefore, in the present embodiment, the roller 43b that rotates by the rotation of the coating die 40
(Bearing) is abutted, and the charging unit 43a is suspended from a shaft 43c provided between the rollers 43b to fix the position.

When corona charging is performed by the charging section 43a, the coating liquid application section 42a of the release layer 42 changes to be lipophilic, and the non-charging section 42b maintains solvent repellency.

From this state, as shown in FIG. 2, when the coating liquid 3 'is applied from the vicinity of this boundary, the coating liquid 3' can be adapted in the coating liquid application section 42a which has been subjected to the charging treatment. .

On the other hand, in the non-charging portion 42b, as shown in FIG. 3 (A), it seems that the coating liquid 3 'has become familiar immediately after application, but thereafter, as shown in FIG. 3 (B). The non-charged portion 42b is repelled and pushed back to the coating liquid application portion 42a by the property of the solvent repellency having a high releasability at the same time as being rounded by the surface tension of the liquid.

Next, a specific method of forming the endless belt 3 will be described.

[Embodiment] A cylindrical aluminum mold body 41
A coating layer 40 was formed by applying a fluororesin coating on the entire inner surface of the substrate to form a release layer 42. The corona discharge device 43 shown in FIG. 1A is inserted into the coating die 40 thus formed, and a corona discharge is performed at an applied voltage of −8 kV, so that the charging voltage of the coating liquid coating portion 42 a of the release layer 42 is charged. Was set to -2 kV.

Next, the coating liquid application section 42 subjected to the charging treatment
A solution containing a polyimide precursor solution of polyamic acid (Trenice well 3000 manufactured by Toray Industries Co., Ltd.) and a solution obtained by diluting carbon black as a conductive agent to 30% in a solvent DMAC is applied, and the coating solution is uniformly rotated while rotating at high speed I made it.

After applying the coating solution, the coating solution was heated at 80 ° C. while continuing to rotate to dry the coating solution. Thereafter, the rotation of the coating mold 40 was stopped, the mold was taken out, and the dam was removed,
After being transferred to a thermostat, the solution was first heated at 100 ° C. to completely remove the solvent, and further heated at 300 ° C. for complete curing.

After the coating film 3 ′ was sufficiently cured, it was cooled and taken out. However, the coating film 3 ′ did not float, and the endless belt 3 was formed well.

As described above, both edges of the endless belt 3 are repelled so as to be pushed back to the coating liquid application section 42a by the solvent releasing property of the non-charging section 42b having high releasability. Since the liquid was rounded due to the surface tension of the liquid, the knife edge was easily inserted, slightly floated at the knife edge, and peeled off from the peripheral edge by hand, but the peeling was smooth and no trace of peeling was left. Further, the outer surface of the center of the endless belt 3 which is in contact with the release layer 42a also has gloss, and an extremely smooth surface was obtained.

[Comparative Example 1] A coating liquid was applied to a coating die 4 without corona charging (see FIG. 4). Then, the coating liquid does not wet the mold and repels it (not adapted). If the rotation speed is slow, the coating liquid is aggregated, and the coating film 3 ′ floats from the peripheral portion in the heat curing process,
The floating coating film 3 ′ shrank further, and a good endless belt 3 could not be formed.

[Comparative Example 2] The same coating die 40 as in Example 1
Then, the corona charging was performed while being gradually fed into the coating die 40 rotating at the charging portion 43a having a charger length of 100 mm.

After the completion of charging, the charging portion 43a was pulled out, and a coating liquid was applied.

Although the coating solution spread on the inner wall surface of the coating mold 40 by wetting, unevenness occurs in the spreading manner. If the rotation speed is slow, the coating solution is partially aggregated, and unevenness is formed on the peripheral portion. When there was, the coating film 3 ′ floated from the peripheral portion at the time of the heat curing treatment, and the floating coating film 3 ′ was further shrunk, so that a good endless belt 3 could not be formed.

As described above, the coating liquid application portion 42a of the release layer 42 having high releasability is uniformly subjected to the corona charging treatment, so that the coating liquid application portion having a substantially coincident width between the peripheral edges of the endless belt 3. 42a is made to have a low release solvent affinity, and the peripheral part of the release layer 42 located outside the peripheral part of the endless belt 3 maintains the high release solvent lyophobicity from the coating film 3 ′. The coating mold 40 having good releasability can be obtained by preventing floating in the process of forming the endless belt 3 and returning the coating liquid application section 42a to the high releasability after the endless belt 3 is formed.

Then, the endless belt 3 after molding is used as a predetermined dimension by cutting off the peripheral edge thereof. Further, the endless belt 3 formed by such a centrifugal molding method.
Was mounted on a Ricoh full-color copier to evaluate images.

As a result, the surface of the endless belt 3 formed in the above example was always smooth and the image was good (good toner fixation).

[0048]

As described above, in the coating die for forming an endless belt according to the first aspect, the coating liquid is applied to the inner wall surface of the substantially cylindrical mold body, and the coating liquid is applied. When the coating film is dried to form a coating film, the surface of the inner wall surface is made to have a low lipophilic property and the inner wall surface is made to have a high releasing property when the coating film is cured. Accordingly, in the molding of the endless belt by centrifugal molding, it is possible to improve the prevention of floating from the coating die until the curing treatment and the ease of peeling the endless belt after the curing treatment.

According to the coating die for forming an endless belt according to the present invention, the inner wall surface is made of a fluorine-based highly releasable material, and the inner wall surface changes to a solvophilicity by heating of a corona charging device. By being corona-charged, it is possible to modify the fluorine-based material, which is a material having a high mold release property, a low affinity for a liquid, a poor affinity for a liquid, a poor wettability and a tendency to repel a liquid, to a solvent-philic property In addition, since the solvent-repellent property can be obtained when left as it is, repeated use is possible.

The coating die for forming an endless belt according to claim 3, wherein a length of a charging portion of the corona charging device is shorter than a width of the inner wall surface and substantially equal to a width of the endless belt.
Since the peripheral portion of the inner wall always maintains the solvent-phobicity, the releasability of a portion corresponding to the peripheral portion of the endless belt after application of the coating liquid can be improved.

According to a fourth aspect of the present invention, in the coating die for forming an endless belt, the relative position between the charging portion and the inner wall surface is determined by rotation of a rotating portion that is driven when the mold body is rotating. By heating the inner wall surface in the closed state, the relative distance between the charging unit and the coating die can be kept constant by rotating following the rotation of the coating die, and the charge amount of the inner wall of the coating die is reduced. The coating liquid becomes uniform, the wettability and fluidity of the coating liquid are not varied, and a good coating film can be formed.

In the method of forming an endless belt according to a fifth aspect, the inner wall surface of a substantially cylindrical mold body rich in solvent-phobicity is made lipophilic by corona charging, and then a coating liquid is applied to the inner wall surface. Then, after forming a coating film by the centrifugal force accompanying the rotation of the mold body, the coating solution is cured, the coating film is cured to form an endless belt, and then the inner wall surface is changed to a solvent-phobic property. By using a highly release layer made of a fluorine-based material which has been subjected to corona charging treatment for endless belt molding, it is possible to form a good endless belt since it can be easily peeled off without lifting.

[Brief description of the drawings]

FIG. 1 shows an application mold for forming an endless belt according to an embodiment of the present invention, wherein (A) is a longitudinal sectional view of the application mold, (B) is an enlarged sectional view of a main part of the application mold, and (C). Is A- in FIG.
FIG. 1D is a cross-sectional view along the line A-B, and FIG. 1D is a cross-sectional view along the line BB in FIG.

FIG. 2 is a cross-sectional view of a coating mold in a coating film forming state.

3A is an enlarged cross-sectional view of the periphery of the coating die immediately after the application of the coating liquid, and FIG. 3B is an enlarged cross-sectional view of the peripheral edge of the coating die after the application of the coating liquid.

FIG. 4 is a perspective view of a main part of the fixing device.

FIG. 5 is a sectional view of a conventional coating die for forming an endless belt.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 3 ... Endless belt 3 '... Coating film 40 ... Coating type 41 ... Mold main body 42 ... Release layer 42a ... Coating liquid application part 42b ... Non-charging part 43 ... Corona charging device

Claims (5)

[Claims] 1. A coating liquid is applied to an inner wall surface of a substantially cylindrical mold body, and when the coating liquid is dried to form a coating film, the surface of the inner wall surface has low mold release characteristics. A coating die for forming an endless belt, wherein the coating wall is made to be lyophilic and, when the coating film is cured, the inner wall surface has a solvent repellency having a high releasing property. 2. The endless end according to claim 1, wherein said inner wall surface is made of a fluorine-based highly releasable material, and said inner wall surface is changed to a solvent-philic property by heating a corona charging device. Coating mold for belt molding. 3. The length of the charging portion of the corona charging device is shorter than the width of the inner wall surface and substantially equal to the width of the endless belt, and the peripheral portion of the inner wall surface always maintains solvent-phobic properties. The coating die for forming an endless belt according to claim 1 or 2, wherein the coating die is provided. 4. The heating of the inner wall surface in a state where the relative position between the charging portion and the inner wall surface is determined by rotation of a rotating portion that is driven when the mold body is rotating. The coating die for forming an endless belt according to claim 3. 5. A coating liquid is applied to the inner wall surface of a substantially cylindrical mold body rich in solvent-phobicity by making the inner wall surface lyophilic by corona charging, and the coating liquid is applied to the mold body. A method for forming an endless belt, comprising forming a coating film by centrifugal force caused by rotation, curing the coating film to form an endless belt, and then changing the inner wall surface to solvent-phobic.