JP3142673B2 - Separation claw for copier - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a separating claw for a copying machine.

[0002]

2. Description of the Related Art Normally, a dry copying machine or the like converts a latent electrostatic image formed on the surface of a photosensitive drum corresponding to characters or figures into a toner image and then transfers the toner image from a paper cassette. The toner image is transferred to the supplied paper surface, and the surface is heated and pressed by a fixing roller heated to fix the transferred toner image to the paper surface, and the toner image and the paper fibers are fused and easily separated from each other. There is a built-in mechanism to prevent this. Then, a method is used in which a separation claw is used to ensure that the copy paper that has passed through such a fixing roller is discharged without being wound around the roller, and the end of the copy paper is scooped up while the tip of the copy paper is brought into close contact with the outer peripheral surface of the roller. Taken.

Therefore, such a separating claw for a copying machine has a small frictional resistance against the outer peripheral surface of the roller, does not damage the surface, has sufficient mechanical strength, particularly high-temperature rigidity, and has a cutting edge or especially its Various characteristics are required, such as sufficient accuracy in the shape of the tip portion, and the fact that the toner is not adhered.

In recent years, in particular, with the increase in copying speed,
In many cases, the heating temperature of the fixing roller is set to a higher temperature, and the separation claw is required to have a heat resistance of 250 ° C. or more, and sometimes 300 ° C. or more. And as the conventionally used heat-resistant separation claw material for copying machines,
Polyamide imide, polyphenylene sulfide, polyetheretherketone, polyetherketone, polyethersulfone, polyetherimide, polysulfone,
And polyether imide.

[0005] As a resin having excellent heat resistance, there is a polyimide resin. The polyimide resins developed so far have excellent properties, but are generally fragile and have insufficient thermal shock resistance, and have high softening temperatures and are insoluble in solvents, so that their molding has been difficult. For example,

[0006]

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A polyimide resin having a basic skeleton represented by the following formula (manufactured by DuPont; Kapton Vespel, etc.)
Is a polyimide resin which does not have a clear glass transition temperature and is excellent in heat resistance, but when used as a molding material, it is difficult to perform thermoforming and is not practical.

In recent years, polyimides described in the claims have been developed as injection-moldable polyimides by improving the moldability of such polyimide resins, and their separation claws have also been proposed (Japanese Patent Laid-Open No. 1-257884). ).

[0009]

However, the separating claws made of the above-mentioned polyimide resin for copying machines are not always satisfactory in abrasion resistance, and in order to improve this, a filler such as potassium titanate fiber is used. Was added as However, when the filling amount is increased, an adverse effect such that the moldability is reduced appears, so that the abrasion resistance cannot be sufficiently improved.

Also, the above-mentioned separation claw made of polyimide resin is not satisfactory in impact resistance and fatigue resistance under high-temperature conditions, and may cause "chip" when repeatedly hitting a high-temperature roller. In addition, there is a problem that deformation is likely to occur due to fatigue when repeatedly loaded.

Therefore, the present invention solves the above-mentioned problems, and makes a separating claw for a copying machine satisfy the injection moldability using a predetermined polyimide resin as a matrix and is excellent in abrasion resistance. It is an object of the present invention to satisfy impact resistance and fatigue resistance.

[0012]

In order to solve the above-mentioned problems, in the present invention, a separating claw for a copying machine is added to 100 parts by weight of a polyimide comprising a repeating unit represented by the following formula and a PH value of 8 or less. A means of forming an injection molded body of a resin composition containing 10 to 100 parts by weight of a zinc oxide whisker having a four-axis radial type and each tapered axis is employed.

[0013]

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A separation claw for a copying machine comprising an injection-molded article of a resin composition obtained by adding 10 to 50 parts by weight of a solid lubricant to the above-mentioned resin composition, wherein the solid lubricant It is also possible to employ a means in which the total amount of the zinc oxide whiskers and the four-axis radial type tapered shafts is 10 to 60% by weight of the total composition.

Further, a separation claw for a copying machine is obtained from an injection molded article of a resin composition obtained by adding 10 to 50 parts by weight of a uniaxial needle filler having a PH value of 8 or less to the above resin composition. May be formed. The details are described below.

The polyimide represented by the formula (3) used in the present invention is obtained by imidizing 4,4'-bis (3-aminophenoxy) biphenyl and pyromellitic dianhydride as raw materials. , Indicating thermoplasticity. Commercial products of such a polyimide resin include Mitsui Toatsu Chemicals; New-TPI.

As shown in FIGS. 1 (a) and 1 (b), the zinc oxide whiskers used in the present invention are four-axis radial type and each axis is tapered. Commercially available products of such zinc oxide whiskers include Matsushita Amtech; Panatetra.

Such a zinc oxide whisker can be used in kneading and injection molding of a resin as a matrix at a rate of 40 to 60.
% Are considered to be broken and exist in the state of the tapered shaft shown in FIG. It is considered that the tapered shaft is hard to come out of the resin when exposed to the sliding surface, and is easily oriented by injection molding to enter the nail tip, that is, it is considered that the nail tip is efficiently reinforced. For this reason, zinc oxide whiskers have a shaft length of 2 to 50 μm and a shaft diameter of 0.2 μm.
３3 μm is preferred.

The PH value of the above zinc oxide whiskers is 8 or less. This is because, on the alkaline side exceeding PH8, polyimide is easily decomposed and injection molding becomes difficult, which is not preferable. In order to further enhance the reinforcing effect of these zinc oxide whiskers, it is preferable to improve the wettability and bonding property between the zinc oxide whiskers and the matrix polyimide resin by surface treatment with a coupling agent. At this time, the coupling agent to be used includes an aminosilane type and an epoxysilane type.

The amount of such zinc oxide whiskers in the polyimide resin is 10 to 100 parts by weight based on 100 parts by weight of the polyimide resin. If the amount of the zinc oxide whisker is less than 10 parts by weight, a sufficient reinforcing effect cannot be obtained. If the amount exceeds 100 parts by weight, a uniform composition cannot be obtained by mixing, and the fluidity of the resin is lost. Is difficult.

In addition to the zinc oxide whiskers, uniaxial needle fillers such as potassium titanate whiskers (see FIG. 2), graphite, and polytetrafluoroethylene (hereinafter referred to as PTFE) may be used as additives to the polyimide resin. ),
Solid lubricants such as molybdenum disulfide, graphite fluoride and lead monoxide may be added. In particular, the separation claw filled with graphite and PTFE has a very small frictional resistance against the outer peripheral surface of the roller, and the non-aggressiveness to the roller is improved.

The amount of the solid lubricant is 10 to 5 parts by weight per 100 parts by weight of the polyimide resin.
0 parts by weight, and the total amount of the solid lubricant and the zinc oxide whiskers is preferably 10 to 60% by weight of the entire composition. If the total amount of the zinc oxide whisker and the solid lubricant exceeds 60% by weight of the total composition, that is, if the amount of the polyimide resin is less than 40% by weight, a uniform composition cannot be obtained and the fluidity of the resin is lost. Molding becomes difficult. When the total amount of the zinc oxide whiskers and the solid lubricant is less than 10% by weight, a sufficient reinforcing effect cannot be obtained. further,
Even when the amount of zinc oxide whiskers is within the above-mentioned predetermined range, when the amount of zinc oxide whiskers is less than 5% by weight, the effect of reinforcing heat-resistant deformation is insufficient and the wear resistance is poor. Conversely, if the amount of the solid lubricant is less than 5% by weight, the effect of non-aggression on the outer peripheral surface of the mating roller is not sufficient. On the other hand, if the amount of zinc oxide whisker exceeds 100 parts by weight, the bulk density will be significantly different from that of polyimide, and a uniform composition cannot be obtained. If the amount of the solid lubricant exceeds 50 parts by weight, the fluidity of the composition is remarkably reduced, and the heat deformation resistance of the obtained molded article is also remarkably reduced, which is not preferable.

Here, the mixing means such as polyimide, zinc oxide whisker and solid lubricant can be supplied to a melt mixer individually, or they can be supplied to a general-purpose mixer such as a Henschel mixer, a tumbler mixer, a ribbon blender in advance. After dry-mixing with a mixer, the mixture may be supplied to a melt mixer, and the specific method is not particularly limited.

In addition, as long as the object of the present invention is not impaired, antioxidants, heat stabilizers, ultraviolet absorbers, lubricants, mold release agents, coloring agents, flame retardants, antistatic agents, crystallization accelerators, etc. Needless to say, may be added as appropriate.

The molding material mixed as described above is heated to a temperature in the range of 390 to 450 ° C., plasticized, filled in a mold, solidified, and released to obtain a desired copy machine. Obtain separation nails. Further, by performing a predetermined heat treatment on the separation claw, a separation claw for a copying machine having excellent heat resistance, dimensional stability, and abrasion resistance and having a long life can be obtained.

This heat treatment must be performed at a temperature in the range of 250 to 340 ° C., preferably 270 to 330 ° C. If the temperature exceeds 340 ° C., remarkable thermal deformation occurs in the separation claw, which is not practically preferable.
This is because if the temperature is lower than 0 ° C., the heat deformation resistance cannot be improved. Further, the heat treatment time greatly varies depending on the heating temperature, and requires at least 2 minutes or more, and in some cases, several weeks. That is, according to the present invention, there is a certain law between the improvement of the thermal deformation resistance of the separation claw by heat treatment and the density change, and the density of the polyimide component in the molding material of the separation claw is at least 1.5% or more. The time required for increasing the density may be the heat treatment time. Here, the density increase rate of the polyimide component can be obtained by measuring the density of the separation claw before and after the heat treatment according to ASTM-D792 and calculating from the mixing ratio and the density of each component in the molding material. According to the experimental results of the inventors, the heat treatment time is 12 hours or more at 270 ° C. heating condition, 1 hour or more at 280 ° C. heating condition, 10 minutes or more at 300 ° C. heating condition,
It takes at least 2 minutes under the heating condition of 0 ° C. and at least 10 minutes under the heating condition of 340 ° C., and the required time is minimized under the heating condition of 330 ° C.

Heat treatment at 260 ° C. or lower requires several weeks or more. Conversely, heat treatment at 340 ° C. or higher results in significant deformation of the separation claw. Not a target.

Although the heat treatment of the separation claw is performed in a heating device in which the separation claw is controlled to a predetermined temperature, the type of the heating device is not particularly limited. However, an electric heating system is usually convenient, and a hot air circulation system, a hot air circulation system, or the like can be used as an atmosphere in the apparatus.

Further, in order to impart excellent non-adhesiveness to the surface of the separation nail, the surface of the resin composition of the present invention which has been subjected to a heat treatment so that the density of the polyimide is increased by 1.5% or more, is added to the surface of the resin composition. The resin may be coated, and the film may be melted during firing to form a continuous fluorocarbon resin film on at least the surface. As the fluorocarbon resin-based coating material at this time, as an enamel type, Chuko Kasei Kogyo Co., Ltd .: Lite SF-301 or Daikin Industries Co., Ltd .: Toughcoat Enamel TCW-880
9 BK and the like. As a type to be fused, PFA manufactured by Mitsui Fluoro Dupont Co., Ltd.
-X500CL, manufactured by DuPont: Vidax AR, etc., and may be a low molecular weight powder or dispersion such as TFE and its telomer, FEP, PFA.

As a method for applying the coating material to the surface of the molded article, any of a spray coating method, a dip coating method, an electrostatic coating method, and a powder coating method may be employed. Further, in this case, it is preferable to apply a primer coating in advance for those requiring a primer coating. The heating device in the firing step may be the same as the above-described heat treatment furnace for polyimide.

The thickness is preferably 5 to 40 μm.
This is because a thin film having a thickness of less than 5 μm is inferior in wear resistance, and a thick film having a thickness of more than 40 μm has a risk of adversely affecting the size of the tip of the cutting edge of the separation claw.

Further, it is preferable to add a reinforcing material and a lubricant for improving abrasion resistance to the PFA resin-based coating material to be fused, and for the purpose of preventing static electricity, an antistatic agent such as carbon black. Etc. may be added.

[0033]

The separating claw for a copying machine according to the present invention can be melt-molded since a predetermined thermoplastic polyimide resin is used as a matrix, and also satisfies injection moldability. Since the zinc oxide whisker has a predetermined PH value, it does not decompose when mixed with the polyimide resin. In addition, it is considered that several tens% of the four-axis radial zinc oxide whiskers are present in a tapered shaft state when the matrix resin is kneaded and molded.
The tapered shaft is hard to fall out of the resin when exposed to the sliding surface, and is easily oriented to enter the nail tip, that is, efficiently reinforces the nail tip. For this reason, the separation claw has excellent wear resistance, and also has extremely excellent impact resistance and fatigue resistance. Further, when a solid lubricant and a uniaxial needle filler are used in combination, the above tendency is more remarkable.

[0034]

EXAMPLES The raw materials used in Examples and Comparative Examples are collectively shown below. The mixing ratios of these raw materials are all shown in parts by weight.

(1) Polyimide Made by Mitsui Toatsu Chemical: New-TPI # 450 (2) Zinc oxide whisker Made by Matsushita Amtech: Panatetra, PH 7.0 (3) Potassium titanate whisker Made by Otsuka Chemical: TISMO-N , PH 7.0 (4) Potassium titanate whisker manufactured by Otsuka Chemical Co., Ltd .: TISMO-D102, PH 9.0 (5) Aluminum borate whisker manufactured by Shikoku Chemicals: Arbolex-5, PH 7.5 (6) Phenolic resin Kanebosha Manufactured by: Bellpearl C-2000 (7) Polytetrafluoroethylene resin [PTFE] Made by Kitamura: KTL 610 (8) Coating primer liquid: Made by Mitsui Fluoro Dupont: MP-902Al (9) PFA liquid for coating: Mitsui Fluoro DuPont: X500Cl [Examples 1 to 8, Comparative Examples 1 to 4] Preliminary mixing of each raw material in the mixing ratio shown in Table 1 or Table 2 After expression mixed, twin-screw melt extruder (Ikegai Corporation: PCM-30) was supplied to 390
The mixture was kneaded and extruded under the conditions of ~ 400 ° C and granulated. The obtained pellets are supplied to an injection molding machine and the cylinder temperature is 390.
~ 400 ° C, injection pressure 1000kg / cm ² , mold temperature 180 ° C, injection molding, and a separation claw-shaped molded product (a separation claw used for a copying machine FX5055 manufactured by Fuji Xerox Co., Ltd.). (Identical shape). This molded article was subjected to a heat treatment at 320 ° C. for 5 hours, further spray-coated with a coating primer solution (8), dried, and further spray-coated with a PFA coating solution (9) in the same manner. 340 ℃, 3
A test piece was heated for 0 minutes and subjected to fusion coating.

With respect to the obtained test pieces, the moldability, abrasion resistance, impact resistance, fatigue resistance and filling amount at the tip of the nail were examined. The results are shown in Table 1 or Table 2. The measurement and evaluation methods are as follows.

Formability With respect to each of the 50 formed separation claws, the shape of the claw tip R (see FIG. 3A) was measured from the side using a projector, and the average radius of curvature R (μm) was obtained. .

Abrasion Resistance As shown in FIGS. 3A and 3B, the separation claw 1 is
Temperature 196 ± 3 ° C, rotation speed 1 for 45C roller 2
Sliding contact was performed under the conditions of 48 rpm, a load of 20 gf, and 350 hours, and the difference (mm) in the distance L ′ from the center of the hole diameter before and after the test to the tip of the nail was measured.

Impact Resistance The impact resistance was measured using a high impact tester (schematic diagram shown in FIG. 4) at the tip of the blade of the separation claw. That is, the lever (length L = 8
5 mm), the other end of the lever is rotatably supported, and when this is spontaneously rotated from an upright state to a horizontal state, the tip of the blade edge of the separation claw 1 is a roller. 2, load (W) 20 gf, contact angle (θ) 1
The collision was performed under the condition of 00 °, and the number of collisions until a defect occurred in the separation claw 1 was measured. The number of collisions is 1
0 times was the upper limit.

Fatigue resistance The impact was measured using an impact fatigue tester (schematic diagram shown in FIG. 5) at the tip of the blade edge of the separation claw. That is, the separation claw 1 is attached to one end of the lever, the other end of the lever is rotatably supported, and the rotating cam 5 is brought into contact with the lower surface of the lever to intermittently raise the separation claw from the height h = 1 mm. And naturally collided with the roller 2. The measurement conditions were as follows: the roller 2 was heated to a surface temperature of 200 ° C. by the heater 4, and the load (W) applied to the tip of the blade of the separation claw 1 was 20 gf, and the contact angle (θ) was 10
0 ° and the deformation amount t of 100,000 collisions (n = 10)
(Μm, see FIG. 6).

Amount of filling at the tip of the nail The side of the tip of the separating nail is mirror-finished using a lapping machine, and the amount of the whisker is observed with a scanning electron microscope (SEM). The evaluation was made in three grades: a circle marked with a mark and a triangle marked with almost no filling.

[0042]

[Table 1]

[0043]

[Table 2]

As is clear from the results in Tables 1 and 2, Comparative Example 2 in which the pH exceeded the predetermined range and was filled with potassium titanate whiskers on the alkali side was impossible to mold, and the predetermined zinc oxide whiskers were not used. Comparative Example 1 not formulated
And Comparative Example 4 or Comparative Example 3 in which no compound was added, inferior abrasion resistance and other test results, and the amount of whisker filling the tip of the nail was small.

On the other hand, in Examples 1 to 8 satisfying the predetermined conditions, all of the test items such as moldability, abrasion resistance, impact resistance, fatigue resistance, and whisker filling amount at the tip of the nail were used. Excellent results were obtained.

[0046]

As described above, the present invention provides a polyimide resin composition in which a predetermined thermoplastic polyimide resin is used as a matrix and zinc oxide whiskers each having a predetermined PH value and a four-axis radial taper shape are blended. Since this is a separation claw for copying machines molded from, this one satisfies the melt moldability and the injection moldability, and at the tip of this separation claw, a tapered shaft of zinc oxide whisker is efficiently used. As a result, the claw tip is efficiently reinforced. For this reason, there is an advantage that the separation claw is excellent in abrasion resistance and also extremely excellent in impact resistance and fatigue resistance. When the solid lubricant and the uniaxial needle filler are used in combination, the above effect is more remarkable.

[Brief description of the drawings]

FIG. 1A is an enlarged perspective view illustrating the shape of a four-axis radial zinc oxide whisker. FIG. 1B is an enlarged perspective view illustrating the shape of the zinc oxide whisker shaft.

FIG. 2 is an enlarged perspective view illustrating the shape of a uniaxial needle filler.

FIG. 3A is a side view of a separating claw for a copying machine used in a wear resistance test. FIG. 3B is a schematic side view illustrating a measurement state of a wear resistance test.

FIG. 4 is a schematic side view of an impact resistance tester.

FIG. 5 is a schematic side view of a fatigue resistance tester.

FIG. 6 is a side view of the separation claw for a copying machine showing the deformation amount t of the tip of the claw.

[Explanation of symbols]

 1 Separating Claw 2 Roller 3 Weight 4 Heater 5 Cam R Separating Claw Tip Angle L 'Distance L Lever Length θ Contact Angle t Deformation W Load L Lever Length h Impact Height

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G03G 13/20 G03G 15/20

Claims (3)

(57) [Claims] 1. 100 parts by weight of a polyimide composed of a repeating unit represented by the following formula is added to a zinc oxide whisker 10 having a PH value of 8 or less and having a four-axis radial shape and a tapered axis.
A separating claw for a copying machine comprising an injection-molded article of a resin composition containing 100 parts by weight. Note: 2. A separating claw for a copying machine, comprising an injection-molded product of a resin composition obtained by adding 10 to 50 parts by weight of a solid lubricant to the resin composition according to claim 1. Lubricant and 4
A separation claw for a copying machine, characterized in that the total amount of each of the axially-radiating and tapered zinc oxide whiskers is 10 to 60% by weight of the entire composition. 3. The uniaxial needle-like filler 1 having a PH value of 8 or less and the resin composition according to claim 1 or 2.
A separating claw for a copying machine comprising an injection-molded article of a resin composition to which 0 to 50 parts by weight is added.