JPH0816815B2 - Separation claw for copier - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a separation claw for a copying machine.

[Conventional technology]

Normally, in a dry copying machine, after converting the electrostatic latent image formed on the surface of the photosensitive drum into a toner image corresponding to characters and figures, this toner image is supplied from the sheet feeding force set. The surface is heated and pressed by a fixing roller that is heated to transfer the toner image onto the paper surface and to fix the transferred toner image on the paper surface so that the toner image and the paper fiber are fused so that they are not easily separated from each other. The mechanism is incorporated. In addition, a separation claw is used to ensure that the copy paper that has passed through the fixing roller is ejected without wrapping around the roller.
A method of scooping up the edge of the copy paper while keeping the tip in close contact with the outer peripheral surface of the roller is adopted. Therefore, in such a separating claw, the frictional resistance against the outer peripheral surface of the roller is small and the surface is not damaged, has sufficient mechanical strength, especially high temperature rigidity, and sufficient precision can be obtained for the tip shape. In addition, characteristics such as not sticking toner are required.

Especially in recent years, with the increase in copying speed,
In many cases, the heating temperature of the fixing roller is set to a high temperature, and heat resistance of 250 ° C. or higher, and sometimes 300 ° C. or higher is required for the separating claw. Conventionally, various proposals have been made to improve the non-adhesiveness of such a separating nail to a printing toner. For example, a coating of a fluororesin or a specific low molecular weight fluoropolymer is formed on the separating nail. Or
A method of kneading a tackiness improver such as a fluororesin into the separating nail material has been adopted, but the improvement of heat distortion resistance is
It essentially depends on the type of heat resistant resin used in the separating nail material. That is, as specific examples of the separating nail material, polyamide imide, polyphenylene sulfide, polyether ether ketone, polyether ketone, polyether sulfone, polyether imide, polysulfone, aromatic polyester and the like can be mentioned. Certain polyether sulfones, polyether imides, polysulfones, etc. have a glass transition point of less than 250 ° C., and at that transition temperature, softening begins and heat resistance is low. Further, since polyphenylene sulfide, polyether ether ketone, and polyether ketone are crystalline resins, glass fiber,
Although the heat resistance is improved to some extent by the reinforcing effect of heat resistant fibers such as carbon fibers or those obtained by adding inorganic powder fillers such as mica and talc to these fibers, heating by the fixing roller can reach 300 ° C or more. In that case, there is a problem that the tip of the separation claw in contact with the roller is gradually deformed, and the separation function is significantly deteriorated. On the other hand, polyamideimide has a heat resistance of more than 250 ° C. as a separating claw material without addition of a reinforcing agent, but at 300 ° C. or higher, the separating claw tip gradually deforms even if a reinforcing agent is added, Similarly, the separation function is deteriorated.

Further, if attention is paid only to heat resistance, there is a polyimide resin. Many of the polyimide resins developed so far have excellent properties, but are generally brittle and have insufficient thermal shock resistance, have high softening temperatures, and are insoluble in solvents. With difficulties. For example A polyimide resin having a basic skeleton represented by (DuPont: Kapton, Vespel, etc.) is a polyimide resin that does not have a clear glass transition temperature and has excellent heat resistance, but is used as a molding material. In some cases, thermoforming is difficult and impractical.

Further, in order to improve the non-adhesiveness of the separating claw for a copying machine, the fluorocarbon resin coating formed on the surface is roughly classified into the following two types. One of them is a binder in which a fluorocarbon resin such as tetrafluoroethylene (TFE), tetrafluoroethylene-hexafluoropropylene polymer (FEP), tetrafluoroethylene-perfluoroalkyl vinyl ether polymer (PFA) is dispersed in an organic solvent. Resin, for example, enamel type mixed in epoxy resin, ferrule resin or polyamide-imide resin, etc. Normally, it is not necessary to raise the processing and firing temperature to the melting point of the fluorocarbon resin,
The melting or curing temperature of the binder resin (about 180 to 250 ° C) was sufficient. Therefore, the conventional heat-resistant resin could be treated. In this type, the binder resin leans toward the base material side due to the difference in surface energy during firing, and adhesion is obtained, and the fluorocarbon resin appears on the surface layer,
Although the properties of fluorocarbon resin have come to appear, the original non-adhesive property cannot be obtained because the coating film surface is not entirely fluorocarbon resin. However, with this type of binder resin using polyphenylene sulfide, excellent non-adhesiveness can be obtained. The reason is that the firing temperature is 300 to 350 ° C, so the mixed TFE, FEP, or PFA melts in the surface layer,
Since it is in the form of a film, the non-adhesiveness of the surface of the coating becomes almost the same as the original characteristics of the fluorocarbon resin. The separating claw material for a copying machine to which this coating material can be applied is the above-mentioned polyimide resin (manufactured by DuPont: Kapton, Vespel, etc.), and there is no injection-moldable material. On the other hand, the other type is one in which the temperature of the fluorocarbon resin is heated to a temperature equal to or higher than the melting point to cause fusion, and in this type, since the entire surface is a fluorocarbon resin, sufficient non-adhesiveness is obtained. You can As the fluorocarbon resin to be fused, TFE and its telomer, FEP, PFA and the like, which are excellent in non-adhesiveness, are desirable, but all have melting points of 280 ° C or higher, and a fusion temperature of at least 300 ° C is required. However, no moldable resin could withstand this temperature. Therefore, a trifluorochloroethylene polymer (CTFE) and a fluorovinylidene polymer (PVDF) were used as the fluorocarbon resin having a melting point of 200 ° C. or lower, but none of these were sufficiently non-adhesive.

[Problems to be Solved by the Invention]

As described above, in the conventional technique, there is a problem that a separating claw for a copying machine having excellent dimensional stability and thermal deformation resistance and capable of being melt-molded cannot be obtained. Met.

[Means for solving the problem]

In order to solve the above problems, the present invention provides In a molded product made of a molding material containing a novel polyimide having a repeating unit represented by, at a temperature of 250 ° C or higher and 340 ° C or lower, a time sufficient for the density of the novel polyimide component in the molded product to increase by at least 1.5% or more. Means for forming separation claws for copying machines with greatly improved heat distortion resistance after heat treatment, and the novel polyimide described above as the molding material.
50-90% by weight, 5-40% by weight of fibrous reinforcement and 5-30% by weight of solid lubricant, the total amount of fibrous reinforcement and solid lubricant is 10-50% by weight of the total composition. Molded products obtained by injection molding using the new polyimide resin composition
After heat treatment at a temperature of 250 ° C or higher and 340 ° C or lower for a time sufficient to cause the density of the new polyimide component in the molded product to increase by at least 1.5% or more, tetrafluoroethylene (TFE), tetrafluoroethylene- Hexafluoropropylene polymer (FEP) or tetrafluoroethylene-perfluoroalkyl vinyl ether polymer (PFA) or other fluorocarbon resin is used as a main component to melt a coating film during firing, and at least the surface of the fluorocarbon resin is continuous. It adopts a means of forming a film to form a separating claw for a copying machine with improved non-adhesiveness of the surface. The details are described below.

First, the above novel polyimide used in the present invention is 4,4'-bis (3-aminophenoxy) as a raw material.
It is obtained by imidizing biphenyl and pyromellitic dianhydride, and has thermoplasticity.

Further, as the molding material used in the present invention, use is made of a novel polyimide in which a predetermined amount of a fibrous reinforcing material and a solid lubricant are mixed and melt-kneaded, for example, a material which is uniformly kneaded and granulated by a heating extruder. You can Then, after the molding material is heated to a temperature range of 390 to 450 ° C. to be plasticized, the target separating claw can be obtained by filling in a mold, solidifying and releasing, and the obtained separating claw. By subjecting the above to a predetermined heat treatment, it is possible to obtain a separating claw excellent in heat deformation resistance and dimensional stability that has never been obtained.

This heat treatment needs to be performed in the range of 250 to 340 ° C, preferably 270 to 330 ° C. Because 340
This is because at a temperature of ℃ or higher, the thermal separation of the separating claw is remarkable, which is not preferable in practice, and at a temperature of lower than 250 ℃, improvement in heat resistance deformability cannot be obtained. Furthermore, the heat treatment time varies greatly depending on the heating temperature, and at least 2
It takes more than a minute, and sometimes weeks. That is,
According to this invention, there is a certain rule between the improvement of the heat deformation resistance of the separating nail by heat treatment and its density change, and the density of the novel polyimide component in the molding material in the separating nail is increased by at least 1.5% or more. Sufficient time may be set as the heat treatment time. Here, the density increase rate of the novel polyimide component can be calculated by measuring the density of the separating claws before and after heat treatment according to ASTM-D792, and calculating from the compounding ratio and density of each component in the molding material. Regarding the heat treatment time, according to the results of experiments conducted by the inventors, the heat treatment time is 12 degrees under 270 degrees heating.
More than 1 hour, under heating at 280 ° C for over 1 hour, under heating at 300 ° C for over 10 minutes, under heating for 330 ° C for over 2 minutes, under heating for 340 ° C for over 10 minutes. The time required is minimal.

Further, in the case of heat treatment at 260 ° C. or lower, several weeks or more is required, and conversely, in the case of heat treatment at 340 ° C. or higher, the separation claw is remarkably deformed, which is not practical in any case.

Such heat treatment of the separating claw is carried out in a heating device in which the separating claw is controlled to a predetermined temperature, but the type of the heating device is not particularly limited. However, it is usually convenient to use the electric heating method, and the atmosphere inside the device is
For example, a hot air circulation type or hot air circulation can be used.

Further, as a compounding material in the molding material used in the present invention, for example, potassium titanate fiber, asbestos fiber, aromatic polyimide fiber, carbon fiber, boron fiber,
It is also possible to use fibrous reinforcing materials such as glass fibers, solid lubricants such as graphite, PTFE, molybdenum disulfide, graphite fluoride, and lead monoxide. And, among the fibrous reinforcing materials, especially for potassium titanate fibers, the effect of improving the heat distortion resistance due to the filling is remarkable, and the diameter is 0.5 to 20 μm.
m, and a length of 0.005 to 0.05 mm are preferable, and a silane coupling agent, a titanate coupling agent, and other surface treatment agents depending on the purpose can be applied in order to have an affinity with the resin. , But not limited to these.

On the other hand, by filling graphite or PTFE among the solid lubricants, the frictional resistance between the separating claw and the outer peripheral surface of the roller becomes very small, and the effect of improving non-aggressiveness against the roller is excellent.

The compounding amount of the new polyimide is 50 to 90% by weight, the fibrous reinforcing material is 5 to 40% by weight, and the solid lubricant is 5 to 30% by weight (the total amount of the fibrous reinforcing material and the solid lubricant is the total resin composition). Ten~
50% by weight) is preferable. Here, when the total amount of the fibrous reinforcing material and the solid lubricant exceeds 50% by weight of the resin and the amount of the new polyimide is less than 50% by weight, the composition is not sufficiently mixed and a uniform composition cannot be obtained. Loses its fluidity and makes molding difficult. Further, when the total amount of the fibrous reinforcing material and the solid lubricant is less than 10% by weight, a sufficient reinforcing effect cannot be obtained. Furthermore, the total amount of fibrous reinforcement and solid lubricant is
Even if 10 to 50% by weight, the amount of fibrous reinforcing agent is 5% by weight.
When the amount is less than the above, the effect of reinforcing the heat distortion resistance is sufficient, and conversely, when the amount of the solid lubricant is less than 5% by weight, the effect of not attacking the outer peripheral surface of the mating roller is insufficient. If the amount of the fibrous reinforcing material exceeds 40% by weight, the bulk density of the new polyimide and the fibrous reinforcing material will be significantly different, resulting in insufficient mixing, which makes the compounding process difficult and results in a uniform composition. I can't get anything. 30% by weight of solid lubricant
When it exceeds, the fluidity of the composition is remarkably lowered, and the heat distortion resistance of the obtained molded article is remarkably lowered, which is not preferable.

Here, the mixing means such as the new polyimide, the fibrous reinforcing material and the solid lubricant may be supplied individually to the melt mixer, or they may be mixed in advance with a general-purpose mixer such as a Henschel mixer, a tumbler mixer or a ribbon blender. It may be dry-mixed by a machine and then supplied to the melt mixer, and its specific method is not particularly limited.

Incidentally, within a range not impairing the object of the present invention, further antioxidant, heat stabilizer, ultraviolet absorber, colorant, flame retardant,
It goes without saying that an antistatic agent, a crystallization accelerator, etc. may be added as appropriate.

In addition, in order to impart excellent non-adhesiveness to the surface, a fluorocarbon resin is coated on the surface of the novel polyimide of the present invention that has been heat-treated so that the density is increased by 1.5% or more, and a film is formed during firing. It is sufficient to melt and form a continuous fluorocarbon resin film on at least the surface. Examples of the fluorocarbon resin-based coating material at this time include, as an enamel type, Chukoh Kasei Kogyo KK: Lighty SF-301, or Daikin Kogyo KK: Toughcoat Enamel TCW-8809BK. Also,
As a type to be fused, there are PFX-X500CL manufactured by Mitsui Fluoro DuPont, and Vidax AR manufactured by DuPont, and low molecular weight powders or dispersions of TFE and its telomer, FEP, PFA and the like may be used.

As a coating method on the surface, spray coating method,
Any of a dip coating method, an electrostatic coating method and a powder coating method may be used. Further, in this case, it is preferable to preliminarily perform the necessary coating of the primer. The heating device in the firing step may be the same as the above-mentioned heat treatment furnace for polyimide.

The film thickness is preferably 5 to 40 μm. because,
This is because a thin film having a thickness of less than 5 μm is inferior in abrasion resistance, and a thick film having a thickness of more than 40 μm may adversely affect the dimension of the tip of the separating claw.

Further, it is preferable to add a reinforcing material and a lubricant for improving wear resistance to the fluorocarbon resin coating material of the fusion type, and carbon black or the like may be added for the purpose of preventing static electricity.

[Action]

It is considered that the separating claw for a copying machine according to the present invention is remarkably improved in heat distortion resistance and dimensional stability as the density is increased by subjecting a molding material containing a novel polyimide to melt molding and then subjecting it to predetermined heat treatment. Further, by coating the surface thereof with a fluorocarbon resin, melting the coating film during firing, and forming a continuous fluorocarbon resin on at least the surface, it becomes possible to impart excellent non-adhesiveness to the surface.

〔Example〕

The raw materials used in Examples and Comparative Examples are collectively shown as follows. The mixing ratios of these raw materials are all shown in% by weight.

New polyimide (Mitsui Toatsu Chemicals: NEW TPI), potassium titanate fiber (Otsuka Chemicals: Tismo D102), graphite (Nippon Graphite: ACP), PTFE (Kitamura: KTL600), firing temperature Coating material PFA coating liquid (Mitsui Fluoro DuPont: X5
00CL), conductive PFA coating liquid (manufactured by the same company: X500KB), coating primer liquid (manufactured by the same company: MP-902A)
L), enamel type coating liquid (made by Chukoh Chemical Industries, Ltd .: SF
-301), coating material with baking temperature of 250 ° C or higher Enamel type coating liquid (Daikin Co .: TC-740
9BK), Examples 1 to 9: New polyimide and various materials are dry-mixed at a ratio (% by weight) as shown in Table 1 and then extruded at 390 to 400 ° C. using a twin-screw melt extruder. Granules, and the resulting pellets are supplied to an injection molding machine (cylinder temperature 390 to 400 ° C, injection pressure 1000 kg / cm ² , mold temperature 150 to 200 ° C) for molding, and a molded product in the shape of a separating claw ( Fuji Xerox Co .: Dry copying machine FX-2700 type was obtained with the same shape as the separating claw used, heat treatment at 280 ° C. for 5 hours in Examples 1 to 5 and 300 ° C. for 1 hour in Example 6. In Example 7, as in Example 1, a molded product that had been heat-treated at 280 ° C. for 5 hours was spray-coated with a primer solution for coating and then dried, and a PFA coating solution was applied thereon. Spray-coated on 340 ° C for 30 minutes. Then, in Example 8, the same treatment as in Example 7 was performed except that the PFA coating liquid was a conductive PFA coating liquid. As in Example 1, the enamel-type coating liquid was spray-coated on the molded product that had been heat-treated at 280 ° C. for 5 hours, and then baked at 340 ° C. for 60 minutes.

With respect to the obtained separated nail test pieces, the heat resistance (deformation amount) of the nail tip, the shape of the nail tip and the non-aggressiveness of the mating roller, and the density increase rate of the novel polyimide were evaluated. The results are summarized in Table 2. The method of each evaluation is as follows.

B) Heat resistance: Using a nail tip thermal deformation tester (schematic diagram is shown in Fig. 1), roller surface temperature 300 ° C, nail tip load 20g, contact angle (θ) 100 °, contact time 20 seconds Tested with (n = 50)
The deformation amount (see FIG. 2) t was measured, and the average value and the variation (displayed by the minimum value and the maximum value) were measured.

(B) Shape of nail tip: The radius of curvature of the nail tip was measured (n = 50) with a projector (magnification 20 times) on the molded separation nail, and displayed in the range from the minimum to the maximum.

C) Non-aggressiveness: Fuji Xerox Co .: Dry copier FX-2700 type is used.
The same type of separation claw and the same shape of claw are attached in place, 99 sheets of B5 size separation paper are continuously fed, and 50,000 sheets in total are passed, and the degree of scratches on the surface of the fixing roller is “No at all”. , "Relatively small amount (marked with △)" and relatively large amount (marked with ×) 3
Graded.

D) Density increase rate of the new polyimide component: According to ASTM-D792, the density of each of the separating claws before and after heat treatment was measured, and the increase rate of the density of the polyimide component of the base material was obtained from Equation-1 and Equation-2. .

ρ _A : Density (measured value) of the molded product (separation claw) before heat treatment, ρ _C : Density (measured value) of the molded product (separation claw) after heat treatment, ρ _H : True density of the filler (equation-1) Calculated), α: blending ratio [wt%] of polyimide component, (100−α): blending ratio [wt%] of filler, Here, x ₁ , x ₂ , x ₃ ... are the filler components 1 mixed,
Each of the compounding ratios [weight%] of 2, 3 ...
ρ ₁ , ρ ₂ , ρ ₃ ... Are the blended filler components 1, 2, 3
It is each true density (actual measurement) of.

E) Non-adhesiveness: The contact angle of pure water was determined for each test piece with a goniometer.

Comparative Examples 1-10: Except for the blending ratios shown in Table 3, the same operations as in Example 1 were carried out to carry out extrusion granulation and molding of separated claw shapes, and further performance evaluation thereof. The results obtained are summarized in Table 4. The mixing ratios are shown in Table 1 and Table 3.
As is clear from the table, Comparative Example 1 is Example 1, Comparative Example 2
Is the same as Example 3, Comparative Example 3 is the same as Example 5 and Comparative Example 7 is the same as Examples 4 and 6, respectively, but the heat treatment conditions (temperature or time) are as shown in Tables 2 and 4. Is also different.

Further, in Comparative Example 10, an enamel type coating material, that is, Toughcoat Enamel TC-7409 BK manufactured by Daikin Industries, Ltd. was applied by spraying to the same composition and heat treatment conditions as in Example 1, and baked at 250 ° C. for 30 minutes. It is a thing. The results obtained are summarized in Table 4.

Comparing Tables 2 and 4, in Examples 1 to 6, there was no attack on the fixing roller, and the surface temperature of the contact roller was
Despite the high temperature of 300 ° C, the amount of deformation of the tip of the nail was not recognized at all, or the deformation was very small. Further, in Examples 7 to 9, excellent non-adhesiveness was obtained by being coated with the fluorocarbon resin-based coating material, and the deformation of the coating was slight even for a roller having a surface temperature of 300 ° C. Therefore, it can be seen that Examples 1 to 10 are separation claws having excellent heat resistance at high temperatures. On the other hand, Comparative Examples 1 to 3 which are low in heat treatment temperature under the condition of the present invention of 240 ° C. Further, Comparative Example 5 in which only the solid lubricant was added, Comparative Example 8 in which the filler was added to the polyamide-imide resin, and Comparative Example 9 in which the filler was not added at all had good non-aggressiveness to the roller. However, the amount of deformation of the nail tip at 300 ° C is large. Further, in Comparative Example 4 in which only the fibrous reinforcing material was added, Comparative Example 6 in which the fibrous reinforcing material was added in the range of the present invention or more, the amount of deformation of the nail tip at 300 ° C. was not observed at all, but the fixing roller was used. In addition, the radius of curvature of the tip of the claw is large and the dimensional stability is poor. Further, in Comparative Example 7 in which the heat treatment temperature was 350 ° C., which was higher than the conditions of the present invention, the tip of the nail was deformed and it was impossible to measure.

Further, Comparative Example 11 in which the enamel type coating material was baked at 250 ° C was excellent in non-aggressiveness and non-adhesiveness to the roller, but the heat resistance of the coating was not sufficient for the roller having a surface temperature of 300 ° C. The amount of deformation was large.

[Effects] As is clear from the above, the separation nail made of the novel polyimide of the present invention has the heat resistance of the nail tip remarkably improved by the predetermined heat treatment, and its variation is small, and further, the nail tip The shape is accurately molded. Further, in this new polyimide, it is possible to melt a coating film containing a fluorocarbon resin as a main component at the time of firing to form a continuous fluorocarbon resin film on at least the surface, and it is possible to obtain excellent non-adhesiveness by the coating film. it can. As described above, the present invention is extremely excellent especially in high temperature use, and therefore, the significance of the present invention can be said to be extremely great.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a nail tip thermal deformation tester, and FIG. 2 is a diagram showing the amount of nail tip deformation. 1 ... Separation claw, 2 ... Heat roller, 3 ... Load, θ ... Contact angle, t ... Deformation amount.

Claims (2)

[Claims] 1. A formula A molded article made of a molding material containing a polyimide having a repeating unit represented by (hereinafter referred to as a new polyimide) is heated at a temperature of 250 ° C. or higher and 340 ° C. or lower, and the density of the new polyimide component in the molded article is at least 1.5% or more. Separation claws for copiers, characterized by being heat-treated for a sufficient time to cause an increase. 2. A fibrous reinforcing material comprising 50-90% by weight of a novel polyimide, 5-40% by weight of a fibrous reinforcing material and 5-30% by weight of a solid lubricating material as a molding material according to the above (1). Using a new polyimide resin composition in which the total amount of material and solid lubricant is 10 to 50% by weight of the total composition, the molded product obtained by injection molding is molded at a temperature of 250 ° C or higher and 340 ° C or lower. After heat treatment for a time sufficient to cause the density of the new polyimide component to increase by at least 1.5% or more, tetrafluoroethylene (TFE), tetrafluoroethylene-hexafluoropropylene polymer (FEP) or tetrafluoroethylene- A fluorocarbon resin such as a perfluoroalkyl vinyl ether polymer (PFA) is used as a main component and is melted at the time of firing, and at least the surface of the fluorocarbon resin is continuous. Bon resin film is formed, non-tacky improved copier separation nail surface.