JP2000302306A - Rolling element for feeding sheet in image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rolling element free from the abrasion and superior in the durability and the non-stickiness to the toner by using a composition containing a fluororesin and zinc oxide particles, and specifying a content of zinc oxide particles to the total amount of the fluororesin and the zinc oxide particles. SOLUTION: Respectively 20 pts.wt. of a perfluoro(alkyl vinyl ether) copolymer (melting point of 303 deg.C) and zinc oxide particles (average particle size of 0.3 μm) are measured and mixed in advance. Then they are introduced into an uniform direction biaxial extruding kneader where a cylinder temperature is set at 370 deg.C, and a screw having a kneading part is set, for thermally melting and kneading the raw material. After the kneading, a pellet of 3 mm cut length is prepared. The pellet is injected into an injection molding machine where a cylinder temperature is set at 370 deg.C, and injected into a mold heated at 230 deg.C to mold a cylindrical rolling element ring of an inner diameter of 20 mm, an outer diameter of 25.6 mm, and a height of 15 mm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine, a facsimile, a laser beam printer, etc.
The present invention relates to a sheet conveying rolling element for conveying an image-formed sheet, for example, a sheet discharging roller, an intermediate guide roller, a kicking roller, and the like.

[0002]

2. Description of the Related Art Image forming apparatuses such as copiers, facsimile machines, and laser beam printers transfer an image formed on a photoreceptor as a toner image onto transfer paper, and fix the image on the transfer paper by a fixing device. Discharge outside. This fixing device
It consists of a fixing roller with a built-in heater and a pressure roller that presses against it, and the transfer paper carrying the fixed toner image is passed through the nip portion, and the toner is melted and fixed on the transfer paper by heating and pressing, Thereafter, the transfer paper is discharged out of the apparatus by a discharge roller and a discharge roller. Such a rolling element for conveying a sheet is required to have heat resistance and flame retardancy, and also needs to be able to follow the sheet. Therefore, chloroprene rubber, polyacetal, or the like has been used as a material for forming the sheet rolling element.

On the other hand, in image forming apparatuses such as copiers, facsimile machines, laser beam printers, etc., there is an increasing demand for a reduction in processing time, and it is necessary to raise the fixing temperature, that is, to raise the ambient temperature of the surrounding area of the fixing. In addition, the image forming apparatus is required to be compact, and it is necessary to shorten the distance between the fixing unit and the rolling element for sheet conveyance.

As shown in FIG. 1, the sheet conveying rolling element generally includes a roller body having shafts at both ends and a shaft body hole. If you have a shaft hole,
Often the shaft is a metal shaft. However, the number of cases used in a structure with a shaft is increasing due to a reduction in assembly costs. The shafted structure is integrally formed of the same material for ease of manufacture.

[0005] Roller bearings as shown in FIG. 2 are set on the sheet transporting rolling elements to constitute the sheet transporting rolling elements of the image forming apparatus. Roller bearings are often made of stainless steel metal, but polybutylene terephthalate resin (hereinafter referred to as PBT) from the viewpoints of ease of assembly with rollers, cost reduction, and imparting hinge properties.
Resin bearings such as these are being adopted.

Japanese Patent Application Laid-Open No. Hei 10-114443 proposes forming a rolling element for sheet conveyance with a composition in which a specific fibrous reinforcing material is mixed with a fluororesin. JP-A-9-
No. 132691 proposes making a paper discharge roller with a composition obtained by adding a fibrous filler to a fluororesin and a thermoplastic resin other than the fluororesin. When the bearing material is metal, there is no problem in abrasion of the shaft portion of the rolling element with a shaft formed of the composition in which the fibrous reinforcing material is mixed with the fluororesin. But,
When a resin bearing is used, when the rolling element is formed solely of the fluororesin, the shaft portion is significantly worn, and when the rolling member is formed of a composition in which the fibrous reinforcing material is mixed with the fluororesin, the bearing portion is worn. There was a problem that was significant.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a sheet conveying rolling element (hereinafter, sometimes referred to as a roller) which is extremely worn even when a resin roller bearing is used. An object of the present invention is to provide a sheet transporting rolling element which is small, durable, and excellent in non-adhesion to toner.

[0008]

According to the present invention, there is provided a composition comprising a fluororesin and zinc oxide particles, wherein the content of the zinc oxide particles is 10 to 60% by weight of the total amount of both. And a sheet conveying rolling element of the image forming apparatus.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The fluororesin used in the present invention is:
Those having heat resistance are preferred. As for the degree of heat resistance, the melting point is preferably 250 ° C. or higher. Specific examples of the fluororesin include tetrafluoroethylene (hereinafter, referred to as TFE)-
Perfluoro (alkyl vinyl ether) copolymer (hereinafter referred to as PFA), TFE-hexafluoropropylene (hereinafter referred to as HFP) copolymer (hereinafter referred to as FEP), TFE-ethylene copolymer (hereinafter referred to as ETFE) Shown).

The above PFA is composed of TFE and CF ₂ ＣＦCF—O
It is a copolymer with at least one kind of perfluoro (alkyl vinyl ether) represented by -Rf (wherein, Rf represents a perfluoroalkyl group having 1 to 10 carbon atoms).
The PFA is preferably a copolymer having 99 to 92% by weight of polymerized units based on TFE and 1 to 8% by weight of polymerized units based on perfluoro (alkyl vinyl ether). Further, a polymerized unit based on another monomer other than the above, for example, a fluoroolefin, HFP, (perfluoroalkyl) ethylene, or the like, may be contained as long as the properties of PFA are not impaired.

FEP is a polymerized unit based on TFE 99 to
Copolymers having 80% by weight and 1 to 20% by weight of polymerized units based on HFP are preferred. Further, a polymerized unit based on another monomer other than the above, for example, a fluoroolefin, perfluoro (alkyl vinyl ether), (perfluoroalkyl) ethylene, or the like may be contained in a range that does not impair the properties of FEP. ETFE includes a copolymer having 90 to 74% by weight of polymerized units based on TFE and 10 to 26% by weight based on ethylene. Furthermore, a polymerized unit based on another monomer other than the above, for example, (perfluoroalkyl) ethylene, fluoroolefin, or the like, may be contained in a range that does not impair the properties of ETFE.

As the zinc oxide particles used in the present invention, those obtained by any production method can be employed. The particle shape of the zinc oxide particles is not particularly limited, and zinc oxide having an irregular shape or zinc oxide particles having a three-dimensional shape, for example, Panatetra (trade name, manufactured by Matsushita Amtech) can be employed.

The average particle size of the zinc oxide particles used in the present invention is preferably 50 μm or less, particularly preferably 1 μm or less.
0 μm or less. When the particle size is large or when it is blended with a fluororesin, uniform dispersion is difficult. The lower limit of the average particle size of the zinc oxide particles is not particularly limited. However, if it is too small, the melt viscosity of the composition increases and molding becomes difficult.
It is preferably at least 01 μm.

The surface-treated zinc oxide particles can be used. As the surface treatment agent used for the surface treatment of the zinc oxide particles, those capable of firmly binding to the surface of the zinc oxide particles and of making the particle surface hydrophobic are preferable.
An organosilicon compound in which a hydrolyzable group such as an alkoxy group, a hydroxyl group, an isocyanate group, or a chlorine atom is bonded to a silicon atom is preferably used. As the hydrolyzable group, an alkoxy group having 4 or less carbon atoms is particularly preferable. The number of hydrolyzable groups is not particularly limited, but is preferably 2 to 3.
Further, an organosilicon compound having a hydrolyzable group and having a hydrophobic non-hydrolyzable group bonded to a silicon atom is preferred.

Examples of the hydrophobic non-hydrolysable group include an alkyl group, an alkenyl group, an aryl group, and a mono (or poly) group.
Preferred are a fluoroalkyl group, a mono (or poly) fluoroaryl group and the like. In particular, it may be substituted with an alkyl group having 2 to 20 carbon atoms, a mono (or poly) fluoroalkyl group having 2 or more carbon atoms having one or more fluorine atoms, an alkyl group or a mono (or poly) fluoroalkyl group. A phenyl group and the like are preferred.

The organosilicon compound may be an organosilicone compound having a hydrolyzable group bonded directly to a silicon atom. As the non-hydrolyzable group in the organosilicone compound, an alkyl group having 4 or less carbon atoms or a phenyl group is preferable. As the organosilicone compound, a compound called a silicone oil can be used.

Specific examples of the organosilicon compound include trialkoxysilanes such as isobutyltrimethoxysilane, hexyltrimethoxysilane, (3,3,3-trifluoropropyl) trimethoxysilane, ethyltriethoxysilane, and dimethyl silicone. Oils, silicone oils such as methyl hydrogen silicone oil and phenylmethyl silicone oil are preferred, and isobutyltrimethoxysilane, hexyltrimethoxysilane, ethyltriethoxysilane and dimethylsilicone oil are particularly preferred.

The content of the surface treating agent is preferably from 0.1 to 5 parts by weight, particularly preferably from 0.3 to 3 parts by weight, based on 100 parts by weight of the zinc oxide particles. The method of surface treatment of the zinc oxide particles is not limited, but the surface treatment agent is dispersed,
A method in which zinc oxide particles are dispersed in dissolved water, alcohol, acetone, n-hexane, or the like, and then dried is preferable.

The content of the zinc oxide particles in the composition of the present invention is 10 to 60% by weight, more preferably 15 to 40% by weight, based on the total amount of the fluororesin and the zinc oxide particles. If it is less than 10% by weight, the effect of imparting abrasion resistance is poor, and if it is more than 60% by weight, the melt viscosity of the composition becomes high, and the fluidity during injection molding is poor.

In the composition of the present invention, an antioxidant, a heat stabilizer, an ultraviolet absorber, a lubricant, a dye, a pigment, an antistatic agent and the like can be blended as long as the object of the present invention is not impaired.
The preparation of the composition for use in the present invention is not particularly limited. A method of melting and kneading with a screw having a kneading function using a twin-screw extruder in the same direction or a different direction to form pellets is used.

The melting and kneading temperature may be at least the temperature at which the fluororesin melts. For example, PFA (melting point: 303
C), it is preferable to carry out melt-kneading at 350 to 400 ° C.

The rolling element for sheet conveyance of the image forming apparatus of the present invention can be obtained by molding the above composition by various molding methods such as injection molding and transfer molding.

As a preferable molding method, the pellets of the above composition are put into an injection molding machine having a cylinder temperature of 350 to 400 ° C., and are injected into a cavity having a predetermined shape set at 200 to 250 ° C. to form an image forming apparatus. And a method of forming the sheet transporting rolling element.

The rolling elements for conveying the sheet of the image forming apparatus include a discharge roller, an intermediate guide roller, a kicking roller and the like, and any rolling element for conveying the sheet of the image forming apparatus may be used. .

[0025]

EXAMPLES Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited to these Examples. The raw materials used in the examples and comparative examples of the present invention are shown below.

PFA: Aflon PFA P manufactured by Asahi Glass Co., Ltd.
-62X, melting point 303 ° C, contact angle (23 ° C water): 110
Degree, FEP; manufactured by Asahi Glass Co., Aflon FEP, melting point 270 ° C,
Contact angle (23 ° C. water): 114 °, ETFE; Asahi Glass Co., Aflon COP, melting point 265
° C, contact angle (23 ° C water): 96 degrees, PTFE; Lubricant L-150J, manufactured by Asahi Glass Fluoropolymers Co., Ltd., zinc oxide particles; Sakai Chemical Industry Co., Ltd., No. 3, zinc flower; average particle size 0.3 µm, boric acid Aluminum whisker; manufactured by Shikoku Chemical Industry Co., Ltd., Y
S3A, potassium titanate whisker; manufactured by Otsuka Chemical Co., Tismo D-102, PBT resin; manufactured by GE Plastics Japan, Baroques 3
10SE0.

(Examples 1 to 3 and Comparative Examples 1 to 4)
After weighing a predetermined amount of the components shown in (2) and (2), they are premixed, and are charged into a co-axial twin-screw extruder kneader set at a cylinder temperature of 370 ° C and a screw having a kneading part, and the raw materials are mixed. It was hot melt kneaded. After kneading, a pellet shape with a cut length of 3 mm was obtained. The pellets are put into an injection molding machine set at a cylinder temperature of 370 ° C., injected into a mold heated to 230 ° C., and the inner diameter is set to 20 m.
m, a cylindrical slide ring having an outer diameter of 25.6 mm and a height of 15 mm was formed. PB as a mating material for the sliding test
The T pellet is put into an injection molding machine set at a cylinder temperature of 250 ° C., injected into a mold heated to 80 ° C., and has a cylindrical sliding ring having an inner diameter of 20 mm, an outer diameter of 25.6 mm, and a height of 15 mm. Was molded.

The sliding test was performed in accordance with JIS K7218 method A.
m / min was performed for 48 hours. The wear weight was determined from the weight difference before and after the test, and the wear volume per 24 hours is shown in Tables 1 and 2. Further, as an evaluation of the non-adhesive performance of the toner, a contact angle (degree) at 23 ° C. of water was measured.

As is clear from Tables 1 and 2, PBT is employed as a bearing member of the rolling element for sheet conveyance.
In the case of 100% PFA as a rolling element for sheet conveyance,
The rolling elements have a large amount of wear. In addition, when PFTE, which is generally known as a slidability imparting agent, is blended and when fiber reinforcing material, which is known in the prior art, is blended, the amount of wear of one or both of the rolling elements and their bearings is reduced. However, there is a problem in durability. In contrast, when zinc oxide particles are blended, the abrasion loss of both the rolling element and its bearing is small.

[0030]

[Table 1]

[0031]

[Table 2]

(Example 4) A predetermined amount was weighed at the weight ratio shown in Example 1 of Table 1 and preliminarily mixed. The cylinder temperature was set at 370 ° C, and a screw having a kneading portion was set in the same direction. The raw materials were put into a shaft extrusion kneader and kneaded with hot melt. After kneading, a pellet shape with a cut length of 3 mm was obtained. The pellets were put into an injection molding machine set at a cylinder temperature of 370 ° C., and injected into a mold heated to 230 ° C., to obtain a shaft-equipped paper discharging roller of a molded product as shown in FIG. Figure 3 is a cross-sectional view of the shaft structure with the paper discharge roller, L ₄ rollers body 1 of cylindrical shape is 14 mm,
L ₂ is 13 mm, the inside is hollow, the weight is reduced, and L ₃ of the cylindrical roller shaft portion 2 is φ4 mm.
In it, L ₁ is a 7mm.

Using the shaft-equipped paper discharge roller, the paper discharge roller was installed as a paper discharge roller in the immediate vicinity of a fixing unit of a copying machine. PBT was used for the bearing member at that time. When the copying test was carried out 50,000 times in the state set in this manner, no deformation as a discharge roller and no toner adhesion were observed.

[0034]

The rolling element for conveying a sheet of the image forming apparatus according to the present invention has durability even when the bearing member is made of resin and has non-adhesiveness to toner.

[Brief description of the drawings]

FIG. 1A is a perspective view illustrating an example of a sheet conveying rolling element having a shaft, and FIG. 1B is a perspective view illustrating an example of a sheet conveying rolling element having a shaft.

FIG. 2 is a perspective view showing an example of a roller bearing.

FIG. 3 is a cross-sectional view showing an example of a shaft-equipped paper discharge roller.

[Explanation of symbols]

 1: Roller body 2: Roller shaft 3: Roller shaft hole 4: Hollow

Claims (2)

[Claims] A fluororesin and zinc oxide particles are contained, and the content of zinc oxide particles is 10 to 60% by weight of the total amount of both.
A rolling element for conveying a sheet of an image forming apparatus, wherein the rolling element is formed of the following composition. 2. The method according to claim 1, wherein the fluororesin is tetrafluoroethylene-
The image forming apparatus according to claim 1, wherein the image forming apparatus is at least one selected from the group consisting of a perfluoro (alkyl vinyl ether) copolymer, a tetrafluoroethylene-hexafluoropropylene copolymer, and a tetrafluoroethylene-ethylene copolymer. Rolling element for sheet conveyance.