JPH0627848A - Toner fixing device - Google Patents

Abstract

PURPOSE:To increase the copying speed of the device for an electrophotographic copying machine and printer equipped with a heat roll or/and paired rolls having a layer contg. polybenzoimidazole (PBI) by incorporating a high-polymer fluorine compd. or/and low-polymer fluorine compd. into the layer. CONSTITUTION:The heat roll has the PBI layer 2 contg. internally added fillers or/and a binder resin material in addition to the PBI and the high-polymer fluorine compd. or/and the low-polymer fluorine compd. on the surface of a core pipe 3 consisting of aluminum. The heat resistance of the aluminum and the release property of PTFE are maintained while the defects of the aluminum, PTFE and silicone rubber inferior in wear resistance are overcome by using the heat roll having such structure. Consequently, the heat roll having the excellent wear resistance and the excellent heat resistance is eventually obtd. In addition, the release property from copying paper is high and, therefore, the copying speed is increased and the time for continuous copying is prolonged.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toner fixing device used in electrophotographic copying machines and printers, and more particularly to a roll for fixing toner.

[0002]

2. Description of the Related Art The demand for higher copying speed in electrophotographic copying machines and printers is increasing due to the recent spread of office automation. In electrophotographic copying machines and printers, the factor that determines the copying speed is mainly the step of visualizing the electric latent image on the copy paper. That is, in electrophotographic copying machines and printers, toner is fixed on the electric latent image on the copy paper to obtain a visible image, but in order to fix the toner, it is generally necessary to apply heat, pressure or heat and pressure.

In order to increase the copying speed, in recent years, a device using a combined heat and pressure method for fixing toner has become dominant in the market. In particular, a method is known in which heat and pressure are simultaneously applied to melt and fix the toner on the copy paper by passing the copy paper between the upper and lower rolls. According to this method, a heat source is incorporated in the upper roll to serve as a heat roll, and the lower roll serves as a support roll or a counter roll. In order to prevent the molten toner from adhering to the roll at the time of fixing the toner, a material having excellent releasability is selected as the material of the upper and lower rolls. Well-known representatives of such substances are polytetrafluoroethylene (hereinafter also referred to as “PTFE”) and silicone rubber.
For example, JP-B-57-52574 and JP-B-59-13.
No. 731 and Japanese Examined Patent Publication No. 60-17109 describe rolls for a toner fixing device, one having a surface coated with PTFE or relatively hard silicone rubber, and one using a metal tube itself.

However, since these materials have low heat resistance, the surface temperature of the roll cannot be set high or it is difficult to maintain the surface temperature. As a result, the fixing speed of the toner cannot be increased, so there is a limit to increase the copying speed.

[0005]

In view of the above problems, the present invention provides an electrophotographic copying machine having a roll made of a material having excellent heat resistance, heat insulating properties, releasability and abrasion resistance. An object is to provide a toner fixing device for a printer. Another object of the present invention is to provide a toner fixing device having a roll having a layer containing polybenzimidazole (hereinafter also referred to as “PBI”) having a releasability equal to or higher than that of a fluororesin roll. To do.

[0006]

SUMMARY OF THE INVENTION To solve the above problems, a toner fixing device for an electrophotographic copying machine and a printer according to the present invention has an electron having a heat roll having a layer containing polybenzimidazole and / or a counter roll. A toner fixing device for a photocopier and a printer, wherein the layer contains a high molecular weight fluorine compound and / or a low molecular weight fluorine compound.

The PBI used in the hot rolls and / or counter rolls of the present invention is a stable heterocyclic polymer, the process for making which is a number of US patents, eg US Reissue Patent No. 2
6,065, U.S. Pat. No. 3,313,783, 3,5
09, 108, 3, 518, 234, 3, 555, 38
9,3,433,772,3,408,336,3,5
78,644,3,549,603,3,708,43
9, 4,154,919, 4,312, 976, 4,3
77,546,4 and 549,388. Further, the manufacturing method of PBI is described in J. P. Critchl
ey, G.E. J. Knight and W.M. W. Wright
Written "Heat-resistant polymer-Technically useful materials (Heat-
Resistant Polymers-Techno
logically Useful Material
s) ”Plenum Press, New York
(1983), pages 259-322.

The PBI preferably used for the thermo roll and / or counter roll of the present invention is poly-2,2 '-(m-phenylene) -5,5'-bibenzimidazole represented by the following structural formula; The PBI has a deformation temperature of 435 ° C., which is significantly higher in heat resistance than PTFE or silicone rubber. As a result, the set temperature of the heat roll can be increased, and the copying speed can be increased. The PBI has a wear coefficient of 100 hours and a PV of 50,000 of 29, which is excellent in wear resistance, and is suitable as a material for a roll through which copy paper passes at high speed. The number average molecular weight of PBI used in the present invention is 2,000 to 100,
It is 000. Preferably, the number average molecular weight of PBI is 5,
000 to 30,000. A method for manufacturing a PBI sintered body is disclosed in JP-A-1-99,818. For example, the sintered body is Hoechst Celan
It is commercially available as Celazele (registered trademark) manufactured by Ese Co., Ltd., and a liquid in which PBI is dissolved in a solvent has also been developed.

As described above, in the heat roll and / or counter roll used in the toner fixing device for the electrophotographic copying machine and printer of the present invention, the layer containing PBI is a high molecular fluorine compound or a low molecular fluorine compound. including. By containing such a fluorine compound in the layer containing PBI, the releasability between the toner fixing roll and the copy paper can be improved.

The high molecular weight fluorine compound in the present invention broadly refers to a homopolymerization or copolymerization of a monomer containing fluorine or a copolymer of a monomer containing fluorine and another monomer. Examples of such high molecular fluorine compounds include polytetrafluoroethylene, polytrifluorochloroethylene, polyvinyl fluoride, polyvinylidene fluoride, polydichlorodifluoroethylene and the like. Preferably,
In the present invention, polytetrafluoroethylene is used. Particularly preferably, fine particle PTFE (Hostaflon TF9202 and TF9205 (registered trademark)) manufactured and sold by Hoechst AG, or a copolymerized fluororesin H.
ostaflon TF1700 is used.

The low molecular weight fluorine compound referred to in the present invention means an inorganic or organic compound containing a fluorine atom. Preferably, the low molecular weight fluorine compound is a fluorine-containing hydrocarbon having up to 20 carbon atoms. The fluorine-containing hydrocarbon may be substituted with another functional group such as an alkoxy group, an alkenyl group, an aryl group, an aryl group, an oxy group, a hydroxyl group, a carboxyl group, an acyl group, an amino group, a nitro group and a halogen. Good. Particularly preferably, an aliphatic fluoromonomer (Fluowet (registered trademark)) manufactured and sold by Hoechst AG is used as the low molecular weight fluorine compound.

Further, in the present invention, a heat roll or /
Alternatively, the layer containing PBI of the anti-roll and the above-mentioned high molecular weight fluorine compound and low molecular weight fluorine compound may be contained at the same time.

Further, in the present invention, a heat roll or /
In addition to the above-mentioned fluorine compound, an internal filler may be contained in the layer containing PBI and the PBI of the roll. PB
The self-lubricating property and electrical conductivity of PBI can be improved by incorporating an internal filler into the layer containing I.
Such an internally added filler is, for example, SiC, various metal powders, and carbon such as graphite. By improving the self-lubricating property, the paper passing property of the copy paper between the rolls is improved, and by improving the electric conductivity, the generation and accumulation of static electricity due to the friction between the roll, the paper and the toner is prevented. For example, by internally adding graphite to PBI, P
The volume resistivity of BI can be lowered to 10 ⁶ to ⁸ to 10 ¹⁴ Ωcm.

The surface hardness of PBI is as very high as 110 on the Rockwell hardness K scale, but elasticity and surface hardness can be improved by including a binder resin substance in the layer containing PBI. By improving the elasticity and surface hardness, the contact area of the hot roll and the counter roll,
That is, it is possible to control the fixing efficiency of toner by giving the nip width a degree of freedom. Such a binder resin material may be, for example, HTV (High Temperature).
Vulcanized Silicone Rubber, RTV (Ro
om Temperature Vulcanize
d) Silicone rubber, LTV (Low Tempera)
pure Vulcanized) silicone rubber.

Embodiments of a heat roll and / or a counter roll used in a toner fixing device for an electrophotographic copying machine and a printer according to the present invention will be described below with reference to the drawings. However, they do not limit the scope of the invention. In the drawings, 1 is a heat source for fixing toner, 2 is a layer containing PBI and a high molecular weight fluorine compound and / or low molecular weight fluorine compound, 3 is a core tube, 4 is an outermost layer, 5 is an intermediate layer, 6 is a silicone rubber layer, and 7 is a PTFE layer.

The heat roll used in the toner fixing device of the present invention may be a sintered body of a mixture of PBI and a high molecular fluorine compound and / or a low molecular fluorine compound as shown in FIG. Since PBI has excellent heat resistance as described above, the surface temperature of the heat roll can be set high, and the copying speed can be increased. Further, the mixture may be used together with the internally added filler and / or together with the binder resin substance. Further, the hot roll of the present invention is shown in FIGS.
It may have a layered structure as shown in.

That is, in the hot roll shown in FIG. 2, in addition to PBI, a high molecular weight fluorine compound and / or a low molecular weight fluorine compound, an internal filler or / and a binder resin substance is added to the surface of the core tube 3 made of aluminum. It has a PBI layer 2 contained. By having such a structure of the heat roll, the heat roll used in the toner fixing device of the present invention covers the drawback of aluminum, PTFE and silicone rubber that the wear resistance is inferior, while at the same time improving the heat resistance and PT of aluminum.
The releasability of FE is maintained. As a result, the heat roll has excellent wear resistance and heat resistance, and since it has a high releasability from the copy paper, it is possible to increase the copying speed and prolong the continuous copying. .

FIG. 3 shows a core tube 3 made of aluminum.
A release agent such as PTFE or silicone rubber is applied to the outermost layer 4 as the outermost layer, and PBI is further provided between the core tube 3 and the outermost layer 4.
And a high molecular weight fluorine compound and / or a low molecular weight fluorine compound, as well as a PBI layer 2 containing an internally added filler or / and a binder resin substance. The heat transfer coefficient of PBI is 0.41 W / mK, which is smaller than the heat transfer coefficient of PTFE (for example, P used in the comparative example below).
In the case of TFE, it is 0.78 W / mK.) As a result, since PBI has an excellent heat insulating property, the surface temperature of the heat roll can be stabilized by using it as an intermediate layer of the heat roll, and a uniform copy image can be obtained even in high-speed copying.

Further, FIG. 4 shows a PBI layer 2 containing an internal filler or / and a binder resin substance in addition to PBI and a high molecular weight fluorine compound and / or a low molecular weight fluorine compound in a core tube 3 made of aluminum. And a heat roll having one or more intermediate layers 5. Providing the intermediate layer 5 may improve the adhesion between the core tube 3 and the layer 2 containing PBI. Examples of the material of the intermediate layer 5 include PTFE
And silicone rubber is used. The layer 2 containing PBI on the surface is used for imparting abrasion resistance to the roll surface.

The counter roll used in the conventional toner fixing device has a layered structure shown in FIGS. That is, the silicone rubber layer 6 or the PTFE layer 7 is provided on the surface of the core tube 3 made of aluminum (FIGS. 5 and 6), or the silicone rubber layer 6 and the PTFE layer 7 are formed on the surface of the core tube 3 made of aluminum. Are sequentially laminated (FIG. 7). Similar to the heat roll, the heat resistance and wear resistance are required for the anti-roll. However, in the toner fixing device of the present invention, in addition to the above PBI and the high molecular weight fluorine compound or / and the low molecular weight fluorine compound,
PBI containing internally added filler and / or binder resin substance
The hot roll with layer 2 can also be used in combination with such a conventional counter roll.

In the present invention, PBI is used as a counter roll.
In addition to the high molecular weight fluorine compound and / or the low molecular weight fluorine compound, an internal filler or / and a binder resin substance may be used. That is, in the counter roll of the present invention, a sintered body of a mixture of PBI and a high molecular weight fluorine compound or / and a low molecular weight fluorine compound may be used alone, or in addition to this, with an internal filler or /
And a binder resin substance. The pair of rolls of the present invention is a core tube 3 made of aluminum as shown in FIG.
In addition to PBI and the high molecular weight fluorine compound or / and the low molecular weight fluorine compound, the surface of the may have a PBI layer 2 containing an internally added filler or / and a binder resin substance.
Further, the anti-roll of the present invention, as shown in FIG. 9, has a core tube 3 made of aluminum, in addition to PBI and a high molecular weight fluorine compound or / and a low molecular weight fluorine compound, an internally added filler or / and a binder resin substance. It may have the PBI layer 2 contained therein and further have one or more intermediate layers 5. As the material of the intermediate layer 5, for example, PTFE and silicone rubber are used. The anti-roll of the present invention is a conventional PBI.
It can be used in combination with a heat roll having no layer containing PBI, or can be used in combination with the heat roll having a layer containing PBI as described above. In view of increasing the temperature of toner fixing, increasing the copying speed of electrophotographic copying machines and printers, and prolonging the continuous copying, in the present invention, both the heat roll and the counter roll are PBI.
In addition to the high molecular weight fluorine compound and / or the low molecular weight fluorine compound, it is preferable to have a PBI layer containing an internally added filler or / and a binder resin substance.

The hot roll and counter roll used in the toner fixing device of the present invention are prepared by dissolving PBI in a solvent and adding a high molecular weight fluorine compound and / or a low molecular weight fluorine compound to make the core uniform. It can be manufactured by coating a tube. That is, the liquid in which PBI and a high molecular weight fluorine compound or a low molecular weight fluorine compound are dissolved in a solvent is dipped in a core tube or electrostatically coated to impart PBI to the surface of the core tube, and then the solvent is dried. As a result, the desired hot roll and counter roll can be obtained. As the solvent, N, N
-Dimethylacetamide, N, N-dimethylformamide, dimethylsulfoxide and N-methyl-2-pyrrolidone can be selected from the solvents commonly used in the production of PBI dry spinning solutions. Particularly preferred solvents are N, N-dimethylacetamide, N-
It is methyl-2-pyrrolidone.

The hot roll and counter roll used in the toner fixing device of the present invention are formed by sintering a mixture of PBI and a high molecular fluorine compound or / and a low molecular fluorine compound into a cylindrical shape, or by sintering. It can also be manufactured later by processing it into a cylindrical shape. Although PBI is a thermoplastic resin as described above, it cannot be melt-extruded because its melting point is higher than the decomposition point. Therefore, in order to manufacture a molded body, a powdered body of PBI or the like is sintered to obtain a molded body.

The present invention will be described in more detail with reference to the following examples.

[0025]

Example 1 Poly-2,2 '-(m with a solid content of 20 parts by weight
-Phenylene) -5,5'-bibenzimidazole was dissolved in 80 parts by weight of N, N-dimethylacetamide.
30 wt% Hostaflo with respect to PBI in solution
nTF9205 was added and uniformly stirred with a homogenized mixer to obtain a coating liquid. This coating liquid was applied to the surface of a blank tube made of aluminum and having a diameter of 20 mm by the dipping method. Then, the coating film was baked at 320 ° C. to obtain a PBI film having a film thickness of 20 μm.

The PBI-coated aluminum tube thus obtained was used in a Casio Electronic Printer Pagepres.
The toner fixing device of t98 CP-2100 was mounted as a heat roll to carry out a toner fixing test on paper.

As a result, during the continuous paper feed test of 200,000 sheets,
There was no paper jam once and no damage was observed on the roll surface. On the other hand, when the dynamic friction coefficient of the roll surface was measured, it was found that μ = 0.07, which was equivalent to that of PTFE alone, and was excellent in releasability.

Further, although the roll surface temperature was raised to 260 ° C., neither offset of toner to the roll nor thermal decomposition of PBI was observed. This has 2 PTFE rolls
In contrast to the occurrence of offset at 20 ° C. and thermal decomposition of PTFE was observed.

[0029]

Example 2 A PBI solution similar to that in Example 1 was prepared.
30 wt% Hostaflo with respect to PBI in solution
nTF1700 was added and uniformly stirred with a homogenized mixer to obtain a coating liquid. This coating solution was applied to the surface of the same tube as in Example 1 by the dipping method.
Then, the coating film was baked at 320 ° C. to obtain a PBI film having a film thickness of 20 μm.

The PBI-coated aluminum tube thus obtained was mounted as a heat roll of the toner fixing device similar to that of Example 1, and a toner fixing test on paper was carried out.

As a result, during the continuous paper feed test of 200,000 sheets,
There was no paper jam once and no damage was observed on the roll surface. On the other hand, when the dynamic friction coefficient of the roll surface was measured, it was found that μ = 0.08, which was equivalent to that of the copolymerized fluororesin and was excellent in releasability.

Further, the roll surface temperature was raised to 260 ° C., but neither offset of toner to the roll nor thermal decomposition of PBI was observed. This was in contrast to the case where the copolymer fluororesin roll caused an offset at 220 ° C. and thermal decomposition of the fluororesin was observed.

[0033]

Example 3 A PBI solution similar to that in Example 1 was prepared.
30 wt% Fluowet based on PBI in solution
EA800 was added and uniformly stirred with a homogenized mixer to obtain a coating liquid. Fluowet EA800
Is RCH ₂ CH ₂ OH (about 95% of R is C ₈ F ₁₇
Is a fluorinated alcohol. This coating solution was applied to the surface of the same tube as in Example 1 by the dipping method. Then, the coating film was baked at 200 ° C. to obtain a PBI film having a film thickness of 20 μm.

The PBI-coated aluminum tube thus obtained was mounted as a heat roll of a toner fixing device similar to that in Example 1, and a toner fixing test on paper was carried out.

As a result, during the continuous paper feed test of 200,000 sheets,
There was no paper jam once and no damage was observed on the roll surface. On the other hand, when the dynamic friction coefficient of the roll surface was measured, it was found that μ = 0.07, which was equivalent to that of PTFE alone, and was excellent in releasability.

Further, although the roll surface temperature was raised to 260 ° C., neither offset of toner to the roll nor thermal decomposition of PBI was observed. This was in contrast to the case where the copolymer fluororesin roll caused an offset at 220 ° C. and thermal decomposition of the fluororesin was observed.

[0037]

Example 4 A PBI solution similar to that in Example 1 was prepared.
15% by weight Hostaflo, based on PBI in solution
n TF9205 and 15% by weight Hostaflon
TF1700 was added and uniformly stirred with a homogenized mixer to obtain a coating liquid. This coating solution was applied to the surface of the same tube as in Example 1 by the dipping method. Then, the coating film was baked at 320 ° C. to obtain a PBI film having a film thickness of 20 μm.

The PBI-coated aluminum tube thus obtained was mounted as a heat roll of a toner fixing device similar to that in Example 1, and a toner fixing test on paper was carried out.

As a result, during the continuous paper feed test of 200,000 sheets,
There was no paper jam once and no damage was observed on the roll surface. On the other hand, when the dynamic friction coefficient of the roll surface was measured, it was found that μ = 0.07, which was equivalent to that of PTFE alone, and was excellent in releasability.

Further, when the roll surface temperature was raised to 260 ° C., neither offset of toner to the roll nor thermal decomposition of PBI was observed. This has 2 PTFE rolls
In contrast to the occurrence of offset at 20 ° C. and thermal decomposition of PTFE was observed.

[0041]

Comparative Example 1 Using the same fixing device for Casio electronic printer as in Example 1, a continuous paper feed test of 100,000 sheets was carried out. The roll of this fixing device consists of an aluminum core tube and a P
It was coated with TFE + PFA (perfluoroalcohol) + graphite. As a result of the test, abrasion was observed on the roll surface after passing 50,000 sheets.

[0042]

Comparative Example 2 Poly-2,2 '-(m with a solid content of 20 parts by weight
-Phenylene) -5,5'-bibenzimidazole was dissolved in 80 parts by weight of N, N-dimethylacetamide and uniformly stirred with a homogenized mixer to obtain a coating solution. This coating solution was applied to the surface of the same tube as in Example 1 by the dipping method. The coating film was baked at 320 ° C. to obtain a PBI film having a film thickness of 20 μm.

The PBI-coated aluminum tube thus obtained was mounted as a heat roll of a toner fixing device similar to that in Example 1, and a toner fixing test on paper was carried out.

As a result, during the continuous paper feed test of 100,000 sheets,
Although there was no paper jam once, paper jam occurred 12 times during the continuous paper passing test up to 200,000 sheets after passing 100,000 sheets. No damage was observed on the roll surface. On the other hand, when the dynamic friction coefficient of the roll surface was measured, it was μ = 0.27.

Further, although the roll surface temperature was raised to 260 ° C., neither offset of toner to the roll nor thermal decomposition of PBI was observed. This was in contrast to the case where the copolymer fluororesin roll caused an offset at 220 ° C. and thermal decomposition of the fluororesin was observed.

[0046]

As described above, in the toner fixing device of the present invention, since the toner fixing set temperature can be set to a higher temperature, the copying speed can be increased. Also, because it has excellent heat insulation, there is little fluctuation in the toner fixing set temperature,
It is possible to reduce power consumption required for temperature control.
Further, since the mutual wear performance is excellent for metal, plastic, paper, toner, etc., the surface wear of the roll is small and the life of the toner fixing device can be extended. Moreover,
Since it has excellent releasability from copy paper, it is possible to carry out continuous paper feeding for a long time.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a heat roll made of PBI and a high molecular weight fluorine compound and / or a low molecular weight fluorine compound.

FIG. 2 is a cross-sectional view of a thermo roll having a layer containing PBI on the surface of a core tube.

FIG. 3 is a cross-sectional view of a thermo roll having a layer containing PBI between a core tube and an outermost layer.

FIG. 4 is a cross-sectional view of a thermo roll having an intermediate layer between a core tube and a layer containing PBI.

FIG. 5 is a cross-sectional view of a conventional paired roll in which silicone rubber is applied to the surface of a core tube.

FIG. 6 is a cross-sectional view of a conventional counter roll having PTFE applied to the surface of a core tube.

FIG. 7 is a cross-sectional view of a conventional paired roll in which silicone rubber and PTFE are sequentially laminated on the surface of a core tube.

FIG. 8 is a cross-sectional view of a pair of rolls having a layer containing PBI on the surface of a core tube.

FIG. 9 is a cross-sectional view of a twin roll having an intermediate layer between the core tube and the layer containing PBI.

[Explanation of symbols]

 1 heat source 2 layer containing PBI 3 core tube 4 outermost layer 5 intermediate layer 6 silicone rubber layer 7 PTFE layer

Claims (1)

[Claims] 1. A toner fixing device for electrophotographic copying machines and printers having a heat roll and / or counter roll having a layer containing polybenzimidazole, wherein the layer is a high molecular fluorine compound and / or a low molecular weight compound. The above device comprising a fluorine compound.