JPH09315615A - Sheet transporting roller body for image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a sheet transporting roller element of a image forming device, capable of dealing with the request for the high speed for the treatment of the picture image forming device or the compactness of a device main body, and excellent in heat resistance, frame resistance, abrasion resistance, and the unadhesiveness of a toner. SOLUTION: A rolling element; in the sheet transporting rolling element of a image forming device, for carrying a sheet on which picture image formed; is formed of fuluorocarbonresin such as tetrafluoroethylene, tetrafluoroethylene- perfloroallkylvinylethel copolymer, tetrafluoroetylene-hexafuloroporpylene copolymer, tetrafluoroethylene-ethylene copolymer. Or, the sheet carrying rolling element is formed of a resin composition wherein fiber-like reinforcing material is added to fluorocarbon resin.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet-conveying rolling element of an image forming apparatus that conveys an image-formed sheet in an image forming apparatus such as a copying machine, a facsimile, and a laser beam printer.

[0002]

2. Description of the Related Art An image forming apparatus utilizing an electrophotographic process such as an electrophotographic copying machine or a laser printer transfers an image formed on a photoconductor by an electrophotographic process onto a transfer paper as a toner image and transfers the image. After fixing on paper with a fixing device, it is ejected out of the machine.

The fixing device includes a fixing roller having a built-in heater and a pressure roller pressed against the fixing roller. A transfer paper carrying a fixed toner image is passed through a nip portion of the fixing roller, and the toner is heated and pressed to apply the toner. The sheet is melted and fixed on the transfer sheet, and then the transfer sheet is discharged out of the apparatus by a discharge roller, a discharge roller and the like.

FIG. 1 shows a schematic structural example of a fixing device having a heating roller. In this fixing device A, a fixing roller 2 having a built-in heater 1 is provided with a pressure roller 3 which is driven and rotated by sandwiching a transfer paper path. The pressure roller 3 is conveyed by a conveyor belt 4 from a transfer section (not shown). The transfer paper 5 carrying the deposited toner image is guided by the fixing inlet guide 6 to be inserted into the nip portion between the fixing roller 2 and the pressure roller 3, and when it is nipped by the pair of rollers 2 and 3, the toner image is transferred. Is fixed and sent out. After the fixing, the leading end of the transfer paper 5 is separated from the fixing roller 2 by the tip of the separation claw 7 that contacts the lower side of the nip portion of the fixing roller 2.

The sheet peeled off from the fixing roller passes through a conveyance path, and passes between a discharge roller 9 that is driven to rotate at that time and a discharge roller 8 that is pressed against and driven by the discharge roller 9 and the like. Emitted outside the machine.

In the color laser printer shown in FIG. 2, the transfer paper carrying the unfixed toner image passes through the contact portion of the fixing roller 10 and the pressure roller 11 with a built-in heater, and then is fixed by the separating claw 12. After being peeled off from the roller 10, it is sent out through the contact portion between the paper discharge roller 13 and the paper discharge roller 14 as it is, and further after passing between the pair of intermediate guide rollers 15, the driving roller 16 is driven to rotate. It is conveyed to the outside of the machine through between the kicking rollers 17.

In FIG. 2, reference numeral 30 denotes a laser unit, 31 denotes a toner storage unit, 32 denotes a drum for forming an unfixed toner image, 33 denotes a transfer device, 34 denotes a paper (sheet) storage cassette, and 35 denotes a fixing device. Is shown.

In the image forming apparatus as described above, the rolling elements for sheet conveyance, such as the paper discharge rollers, intermediate guide rollers, and kick-out rollers, have shapes as shown in FIGS. That is, the rolling element for sheet conveyance used as the discharge roller or the intermediate guide roller as shown in FIG. 3 has the boss portions 19 serving as the rotation shafts at both ends of the roller body 18, and is also used in FIG. The rolling element as shown in (1) has a shaft hole 20.

The rolling member for sheet conveyance used as a kicking roller as shown in FIG.
Have bosses 22 with gears at both ends.

Since such a sheet-conveying rolling element is required to have heat resistance and flame retardancy as well as a sheet discharging roller, and further, it is necessary to follow the sheet, and therefore chloroprene rubber is used as a material for molding it. Materials such as (CR) and polyacetal (POM) have been widely used.

By the way, a copying machine, a facsimile (Fa)
x), in an image forming apparatus such as a laser beam printer (LBP), there is an increasing demand for a reduction in processing time, and therefore, the printing function is speeded up and the fixing temperature is raised (250 ° C.).
Nearby). For example, the normal use atmosphere temperature around the fixing area of the device thus accelerated is 25 to 150 ° C., and 50 to 250 ° C. instantaneously.
It may reach ℃.

Further, since the downsizing of the main body of the image forming apparatus is also an important technical problem, the distance between the fixing section and the rolling element for sheet conveyance tends to be short.

[0013]

However, in order to satisfy the above-mentioned demand for shortening the processing time, it is necessary to prevent the sheet-conveying rolling elements, such as the sheet-discharge rollers and the sheet-discharge sliding guide, from being contaminated by toner and heat. A new problem, which has not occurred in the conventional image forming apparatus, has arisen.

Further, in a rolling element which has a boss portion and a shaft hole and is driven to rotate, the boss portion and the shaft hole are worn and deformed due to sliding friction with the mounting portion (shaft and bearing), and the mounting portion of the housing is worn. The problem occurs.

Particularly, in the rolling element having the boss portion, the pressing force from other rollers or rollers contacting the roller body causes
Further, there is a case where the boss is deformed by the temperature of the use atmosphere and the frictional heat.

Accordingly, an object of the present invention is to solve the above-mentioned problems and to provide heat resistance, abrasion resistance, and toner properties so as to meet the demands for increasing the processing speed of the image forming apparatus and reducing the size of the apparatus body. An object of the present invention is to provide a sheet conveying rolling element of an image forming apparatus having excellent non-adhesiveness.

[0017]

In order to solve the above-mentioned problems, according to the present invention, in a sheet-conveying rolling element of an image forming apparatus for conveying an image-formed sheet, the rolling element is formed of a fluorocarbon resin. Of.

Alternatively, in a rolling element for sheet conveyance of an image forming apparatus that conveys an image-formed sheet, the rolling element is formed of a resin composition in which a fibrous reinforcing material is added to a fluorocarbon resin.

When the sheet conveying rolling elements of the image forming apparatus are formed of a fluorocarbon resin, an image forming apparatus capable of obtaining a clear image to which no toner adheres can be obtained, and the sheet conveying rolling elements have heat resistance and flame retardancy. It also has the nature.

Further, a rolling element for sheet conveyance made of a resin composition obtained by adding a fibrous reinforcing material to a fluorocarbon resin has excellent abrasion resistance and small thermal deformation, so that an image forming process with a higher processing speed can be achieved. It becomes a rolling element for sheet conveyance that can also be used in the apparatus.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION Sheet-conveying rolling elements such as a paper discharging roller, an intermediate guide roller, and a kicking roller are formed of a fluorocarbon resin as follows. As the fluorocarbon resin, a molten fluorocarbon resin is preferable in terms of moldability, and a fluorocarbon resin capable of injection molding is more preferable. Among them, PFA, FEP and ETFE are particularly preferable.

As a typical example of the fluorocarbon resin,
The resins as listed below may be mentioned. In addition, []
Inside, heat distortion temperature (under bending stress of 4.6 kgf / cm ² , JIS K 7207), melting point, thermal decomposition temperature, melt viscosity, number average molecular weight, hardness (ASTM
D2240, JIS K 7215), limiting oxygen index (ASTM D2863), and UL94 flammability standard are shown in this order, and all numerical values are representative values.

(1) Polytetrafluoroethylene (PT
FE), [121 ° C, 327 ° C, about 508-53
8 ° C, 10 ¹¹ to 10 ¹² poise (340 to 380 ° C),
About 10 ⁶ to 10 ⁷ , D50 to D65, 95% by volume
(Equivalent to V-0) (2) Tetrafluoroethylene-perfluoroalkylvinyl ether copolymer (PFA), [74 ° C., 3
00 to 310 ° C., 464 ° C. or higher, 10 ⁴ to 10 ⁵ poise <380 ° C.>, (2 to 3) × 10 ⁵ , D60 to
D64, 95% by volume or more, equivalent to V-0] (3) Tetrafluoroethylene-hexafluoropropylene copolymer (FEP), [72 ° C, 250 to 28
2 ° C., 419 ° C. or higher, 4 × 10 ⁴ to 10 ⁵ poise (380 ° C.), (3 to 5) × 10 ⁵ , D60 to D6
5, 95% by volume or more, equivalent to V-0] (4) Tetrafluoroethylene-ethylene copolymer (E
TFE), [89-104 ° C, 260-270 ° C,
347 ° C or higher, 10 ⁴ to 10 ⁵ poise <300
° C>, 1 x 10 ⁵ , D75, 30% by volume, V-
0) (5) Polychlorotrifluoroethylene (PCTF
E), [126 ° C, 210-212 ° C, 347-
418 ° C., 10 ⁷ poises <230 ℃>, (1~5)
× 10 ⁵ , D90, 95% by volume or more, equivalent to V-0] (6) Chlorotrifluoroethylene-ethylene copolymer (ECTFE), [116 ° C, 245 ° C, 330
° C or higher, 2 × 10 ³ to 10 ⁵ poise <260 to 315
℃>, (1~5) × 10 5, D55~D75,6
0 volume%, equivalent to V-0] (7) Polyvinylidene fluoride (PVDF), [
149 ° C, 156-170 ° C, 400-475 ° C,
2 × 10 ³ to 10 ⁵ poise (210 to 270 ° C.),
(3 to 8) × 10 ⁵ , D70 to D80, 44% by volume, V-0 equivalent] (8) Polyvinyl fluoride (PVF), [195
~ 205 ° C, 372-480 ° C, (2-5) x 10
⁵ , 23% by volume, equivalent to V-0] (9) Tetrafluoroethylene-hexafluoropropylene-perfluoroalkylvinylether copolymer (EPE) [440 ° C or higher].

The fluorocarbon resin is not limited to a homopolymer, but may be a copolymer of two or more of the above-mentioned monomers of the fluorocarbon resin in a polymerization amount of, for example, about 1:10 to 10: 1, or a terpolymer. It may be a fluorinated polyolefin such as a coalesced or the like, and all of them show properties as a solid lubricant. Among them, PTFE is
It is preferable because it has excellent properties such as heat resistance, chemical resistance, non-adhesion, and low coefficient of friction.

These fluorocarbon resins are preferred because of their relatively high differential pyrolysis onset temperatures. For example, P
The decomposition points of TFE and PVDF are about 490 ° C. and about 350 ° C., respectively, and their differential thermal decomposition initiation temperatures also show about 555 ° C. and about 460 ° C., respectively.

Further, among the fluorocarbon resins, there is a tetrafluoroethylene fluorocarbon resin, and the following can be exemplified in addition to the above-mentioned PTFE. -Tetrafluoroethylene-perfluoro [alkyl (methyl, ethyl, propyl, butyl)] vinyl ether copolymer (PFA) -Tetrafluoroethylene-hexafluoropropylene copolymer (FEP) -Tetrafluoroethylene-hexafluoropropylene-per Fluoro [olefin (alkyl, propyl)]
Vinyl ether terpolymer (EPE) -Ethylene-tetrafluoroethylene [alternating] copolymer (ETFE) (ETFE may contain a third component. Alternation is 90-100%. Those having stable properties are preferable).

Since the tetrafluoroethylene-based fluorocarbon resin has (--CF ₂ --CF _2- ) (tetrafluorocarbon) in the molecular structure in its skeleton, a strong bond between C--F provides heat resistance and a low coefficient of friction. Excellent. Among these, perfluoro-based tetrafluorocarbon resins such as PTFE, PFA, and FEP are all surrounded by a fluorine atom or a trace amount of an oxygen atom around a carbon atom as a skeleton, and a strong bond between C-F is formed. And, since the circumference of the carbon skeleton is protected by fluorine, it is excellent in heat resistance, low friction coefficient, lubricity, and also excellent in various properties such as non-adhesion, chemical resistance, etc., so that molten toner and dust, It is expected that dust and the like are less likely to adhere to the surface of the paper discharge roller, and that the wear of the sliding surface due to the adhesion of foreign matter is expected to be reduced.

For example, the heat distortion temperature (JIS K 7207) will be described as an evaluation criterion for heat resistance. The heat distortion temperature (JIS K 7207, 4.6 kgf)
/ Cm ² bending stress) of 50 ° C. or more, preferably 70 to
A fluorocarbon resin composition at 250 ° C. is preferable because the amount of deformation due to heat is small. The load is small under the use conditions such as the rolling element for sheet conveyance in the invention of the present application, so it is appropriate to judge under the bending stress condition of 4.6 kgf / cm ² .

The fluorocarbon resin is preferably used in the present invention in view of its excellent heat resistance. The upper limit of the crystal melting point is determined by the bond energy between fluorine and carbon and the bond energy between carbon atoms in the main chain. From a point of view,
The highest one is considered to be 400 ° C. or less. By the way,
The crystal melting point is a physical property exhibiting a thermal characteristic of 250 ° C. or higher.

The fluorocarbon resin preferably has a thermal decomposition temperature of 300 ° C. or higher, more preferably 400 to 550 ° C.
The thermal decomposition temperature referred to here is a temperature that can be measured by gravimetric analysis or the like, and specifically, thermal analysis (DSC, differential scanning calorimetry,
DTA, TDA, etc.) can be obtained from a thermobalance weight loss curve (TG) such as a thermobalance method and a differential thermal analysis curve (DTA). For example, a sample of 15 mg was heated at a heating rate of 1
Heat at 0 ° C./min in air or nitrogen gas to determine the temperature at which the specimen loses 5%, or the temperature at which the sample loses 5 mg, or the percent weight loss at each temperature, and The temperature corresponding to the weight% can be determined, and this can be determined as the 50% weight loss temperature by thermal decomposition.
It is also evaluated as the differential pyrolysis onset temperature.

According to JIS K 7210, a fluorocarbon resin having a melt viscosity of 10 ³ to 10 ⁵ poise at a shear rate of 10 ² to 10 ⁴ (sec ^-1 ) has excellent injection moldability. It is preferable because it exists. From the viewpoint of such injection moldability, the melt viscosity of the fluorocarbon resin is more preferably 10 ⁴ to 10 ⁵ poise.

Incidentally, the melt viscosity of PFA and FEP is 3
10 ⁴ to 10 ⁵ poise at 80 ° C., 4 × 10 ⁴ to
It is 10 ⁵ poise and ETFE is 10 ⁴ to 1 at 300 ° C.
0 is ⁵ poise, also in PTFE 340~380 ℃
It is 10 ¹¹ to 10 ¹² poise, and a fluorocarbon resin having a viscosity characteristic of about 10 ³ to 10 ¹² poise even under such a high temperature is preferable because it has high viscosity characteristics and thus has excellent heat resistance. .

[0033] However, the melt viscosity at two hundred eighty to three hundred and eighty ° C. exceeds ¹⁰⁷ poises, a large load on the cylinder, such as a melt molding machine during granulation and injection molding described later, the injection molding and stable granulation In consideration of heat resistance, moldability and mass productivity, the melt viscosity of the fluorocarbon resin at 280 to 380 ° C. is preferably 10 ³ to 10 ⁶ poise.

The above-mentioned PFA is a chain fluororesin having a perfluoroalkoxy side chain, and is a modified product of PTFE, which is a homopolymer, and a monomer containing a perfluoroalkoxy group, or PTFE and the above-mentioned side chain. It is a copolymer containing a comonomer that gives a chain as an essential component.

The melt viscosity of such PFA or FEP is
370 to 380 according to the evaluation method of ASTM D3307.
° C, specifically, the specific melt viscosity at 372 ± 1 ° C, and in the case of ETFE, the specific melt viscosity at 290 to 300 ° C, the specific melt viscosity of these injection-moldable fluorocarbon resins is 1 × 10 ³ -1 × 1
0 is a ⁶ poise. The melt flow index (melt flow rate) is from 1 to 36 g / 10 minutes, preferably from 1 to 18 g / 10 minutes, and from 3 to 18 g / 10 from the viewpoint of compatibility between injection moldability and heat resistance. Minutes (A
STM D3307) is more preferred.

The carbon number of the alkyl group contained in PFA and FEP is about 1 to 10 or 1 to 4, and the alkyl group may be a methyl group, an ethyl group, a propyl group, a butyl group or the like. The proportion of one or more alkyl groups constituting the resin in the resin is 0.1 to 10% by weight, preferably 1 to 8% by weight, more preferably 3 to 6% by weight. The hexafluoropropylene portion of FEP is from 8 to 16
% By weight, preferably 8 to 10% by weight, PFA, F
Both EPs have an optimum melt viscosity, and are excellent in moldability and heat resistance, so that they are rolling elements for sheet conveyance. In consideration of various properties such as heat resistance, non-adhesion, and melt viscosity, it is preferable that the alkyl group portion of PFA or FEP is mainly a propyl group.

On the other hand, hydrogen-containing fluorocarbon resins such as ETFE, PCTFE, PVDF are PTFE, P
Compared with a relatively flexible resin group such as FA and FEP, it has a large mechanical strength and is excellent in abrasion resistance and the like, which is preferable. Among them, ETFE has heat resistance with a glass transition point of about 100 ° C. or higher and good impact resistance. For example, since ETFE does not break even in a notched Izod impact test at room temperature, inadvertent cracking of the molded product occurs. It is considered that no such phenomenon occurs. Due to such ETFE characteristics, a resin molded article mixed with a fibrous reinforcing material in order to improve heat deformation temperature, flexural modulus and abrasion resistance,
It is possible to compensate for the adverse effect of the addition of the fibrous reinforcing material that the impact strength of this product is lowered.

The composition ratio of the tetrafluoroethylene portion to the ethylene portion in ETFE is from 70:30 to 3
The ratio may be in the range of 0:70, preferably in the range of 40:60 to 60:40. The crystal melting point of ETFE reaches its maximum when the content of tetrafluoroethylene is about 50 mol%, so that the above ratio is from 45:55 to 55 :.
A range of 45 is considered more preferable in terms of heat resistance. In addition, a small amount of the third
A component may be contained.

When the above-mentioned PTFE is powdered and added to a hydrogen-containing fluorocarbon resin other than PTFE, for example, ETFE, the particle diameter is 70 μm.
m or less, a perfluoro-based or tetrafluorocarbon-based resin powder such as PTFE powder or PFA powder is preferable for homogenizing the composition, and a more preferable particle diameter is 1 to 50 μm.
It is. When importance is attached to the mechanical characteristic value of the rolling element for sheet conveyance, a fibrous PTFE powder (a virgin PTF) may be used.
E powder) may be used.

In the present invention, more preferable results can be obtained by using recycled PTFE instead of virgin PTFE. The regenerated PTFE powder is a powder obtained by firing the virgin material once and then pulverizing it, and has a property that it is difficult to form a fibrous material. It does not significantly increase the melt viscosity of the product and does not impair injection moldability.
Also, since the regenerated PTFE powder has been fired once,
This is an additive that can provide a stable molded product without causing a dimensional change, a shape change, or a crack in a resin molded product obtained by mixing them.

Commercially available recycled PTFE powders include, for example, KT300M, KT300H, and KT40 manufactured by Kitamura Corporation.
0M, KT400H, KTL610 and the like.

PTFE powder, regenerated PTFE powder, PFA powder, F
When a perfluorotetrafluoroethylene such as EP powder is added to improve non-adhesion and avoid damage to a sliding partner, the proportion of the perfluorotetrafluoroethylene in the total composition is as follows. 1 to 25% by weight, preferably 2 to 20% by weight, more preferably 5 to 1% by weight.
5% by weight. If the amount is less than the predetermined range, the sliding characteristics of the rolling element for conveying the sheet are not improved, and if the amount exceeds the predetermined range, the formability is deteriorated.

The number average molecular weight (Mn) of the fluorocarbon resin is preferably from 1 × 10 ⁴ to 1 × 10 ⁸ . The reason is that if the number average molecular weight is smaller than the predetermined range, it does not have abrasion resistance, and if it exceeds the predetermined range, injection molding becomes difficult and efficient molding becomes difficult. From such a tendency, a more preferable number average molecular weight (Mn) is
It is 1 × 10 ⁵ to 1 × 10 ⁷ , and when importance is placed on injection moldability, it is 1 × 10 ⁵ to 1 × 10 ⁶ .

In addition, at least one surface of the sheet transporting rolling element, the cavity of the sheet transporting rolling element of the injection mold, or the support shaft of the sheet transporting rolling element, for example, the sheet transporting rolling element and the sheet Rotary sliding parts such as members, support shafts and the like that frictionally rub, specifically, the inner peripheral surface of paper discharge rollers and intermediate guide rollers that slide and rotate with the outer peripheral surface of the support shaft,
And the outer peripheral surface of the roller body of the sheet conveying rolling element that slides in contact with a sheet member such as paper, and also because of the releasability of the sheet conveying rolling element from the injection molding die, the inside of the roller main body.・ The smaller the surface shape and surface roughness of the outer peripheral surface, the better.

Further, in the rolling element for sheet conveyance or its cavity, a sliding portion where the rolling element for sheet conveyance rubs is used to smoothly pass the sheet or for the rolling element for sheet conveyance from the injection molding die. In order to improve the releasability, the surface shape and the surface roughness of the surface in contact with the sheet are preferably small.

Such surface shape, roughness and shape roughness are, for example, evaluation methods defined by JIS such as Rmax (maximum roughness), Ra (arithmetic mean roughness), Rz (ten-point mean roughness). The value is, for example, 25 μm or less by the evaluation method of arithmetic mean roughness (Ra), and is 10 μm.
Or less, more preferably 3.2 μm or less. If the surface roughness exceeds the above value, the sliding surface is likely to have many scratches, which is considered to cause wear.
Further, the mold releasing property of the sheet conveying rolling element from the injection molding die is deteriorated, which is not efficient and the yield is reduced.

The lower limit of the surface shape and roughness is 0.1 μm or more in consideration of the cavity surface of the injection molding die, the support shaft, and the efficiency at the time of precision cutting of the rolling element for sheet conveyance. Or, considering workability, it may be 1 μm or more. Since it takes a long time to finish the injection mold and the surface of the support shaft, it may not be efficient and may be affected by the formation of the transfer film of the resin material. It is presumed that the surface shape / roughness of each of the above may be in the range of about 2 to 8 μm according to the specifications and conditions.

The hardness of the rolling element for sheet conveyance is, for example, Shore hardness (ASTM D2240, <JIS K
7215>, durometer hardness meter) D40 to D9
The hardness is preferably 0, more preferably D50 to D80. If the hardness is too low, the part where the rolling element rotates and slides and comes into contact with the mating member, and the part where the transfer paper comes into contact with the OHP transfer member or the transfer paper due to contact or sliding, may cause wear. It is considered that if it is too high, the rolling element rotates and slides and comes into contact with the mating member.
It is considered that it is difficult to suppress damage to the HP transfer member and the like. To obtain such hardness, 1 to 50 weight parts of various fillers such as organic fillers and inorganic fillers (grains such as flakes, spheres and various shapes such as fibrous) are used as necessary. % May be mixed. The various fibrous fillers such as whiskers will be described later in detail.

The non-adhesiveness of the surface of the resin molded body forming the sheet conveying rolling element of the image forming apparatus can be determined by measuring the contact angle of water droplets. For example, when the contact angle of a water droplet is 80 ° or more, it is regarded as a resin molded product having sufficient non-adhesiveness in the present invention, and a more preferable contact angle is 90 ° or more.

Incidentally, the method of measuring the contact angle is, for example, using a goniometer type contact angle tester manufactured by Elma Optical Co., Ltd., and a droplet of 0.01 to 0.1 ml, preferably 0.05 ml at room temperature and atmospheric pressure. A typical method is to drop the water droplet of No. 3 on the surface of the test piece and measure the contact angle for 1 minute (30 seconds and 1 minute) immediately after the dropping. Of course, it may be a measuring method.

The fibrous reinforcing material used in the present invention preferably has a fiber diameter of 0.05 to 8 μm and a fiber length of 1 to 100 μm, particularly a fiber diameter of 0.1 to 3 μm and a fiber length of 1 to 40.
μm is preferred. Because, if the fiber diameter and the fiber length are smaller than the predetermined range, the wear resistance of the fluorocarbon resin cannot be improved, and there is no reinforcing effect,
Exceeding the predetermined range is not preferable because the above-mentioned surface roughness becomes larger than a required range and it becomes impossible to form a square end precisely.

Specific examples of the fibrous reinforcing material are potassium titanate whiskers, aluminum borate whiskers, magnesium borate whiskers, zinc oxide whiskers, titanium oxide whiskers, calcium carbonate whiskers, aluminum sulfate whiskers, calcium sulfate whiskers, magnesium sulfate whiskers. , Calcium silicate whiskers, wollastonite whiskers, carbon fibers, glass fibers, graphite fibers, various whiskers containing silicon oxide as a main component, mineral whiskers obtained by melting and processing igneous rocks, silicon nitride whiskers, silicon carbide whiskers , Various ceramic whiskers such as alumina whiskers.

The potassium titanate whisker is, for example, K _{2
O · 6TiO 2, K 2 O} · 6TiO 2 · 1 / 2H 2 O
And K ₂ Ti ₂ O ₅ , K ₂ Ti ₄ O ₉ , K ₂ Ti
₆ O _13, such as K ₂ Ti ₈ O _17, formula K ₂ O ·
Examples thereof include potassium titanate whiskers represented by nTiO ₂ (n is an integer of 1 or more or an even number of 2 or more). These have a specific gravity of 3.2 to 3.3 and a melting point of 1300 to 1400.
C., and is manufactured by the flux method, the melt method, or the like.

In the flux method, the raw material (Ti
A mixture of O ₂ , K ₂ CO ₃ ) and a flux is melted and gradually cooled to synthesize K ₂ Ti ₄ O ₉ whiskers (primary compound). Then, this whisker is treated with a dilute acid aqueous solution or boiling water to extract a part of K between the layers and denature the composition,
It is heat-treated at 1000 ° C. and has a tunnel structure K
₂ Ti ₆ O ₁₃ whiskers are synthesized as a secondary compound. The whisker size has a diameter of 0.1-0.5 μm and a length of 1
Many are about 50 μm, and commercially available products include Tismo N, Tismo L and Teismo D manufactured by Otsuka Chemical Co., Ltd.

In the melt method, the raw materials are mixed with K ₂ Ti ₂ O ₅ in an equivalent stoichiometric composition ratio, melted at 1100 ° C., and the melt is rapidly solidified to form needle-shaped K ₂ Ti ₂ O ₅ . Synthesized as a primary compound. Next, this whisker is treated by a composition / structure conversion process in the same manner as K ₂ Ti ₄ O ₉ to synthesize a K ₂ Ti ₆ O ₁₃ whisker as a secondary compound. The whisker size is characterized by being thicker than the flux method.
Many of them have a length of 0 to 30 μm and a length of about 80 to 500 μm, and examples of the commercially available product include Tesakus A manufactured by Kubota.

For aluminum borate whiskers,
It may be whitened by adding S (sulfur) thereto, but may have the chemical formula 9Al ₂ O ₃ .2B ₂ O ₃ or 2A
a white needle crystal represented by _{l 2 O 3 · B 2 O} 3,
Average fiber diameter 0.05-5μm, average fiber length 1-100μ
m.

[0057] aluminum borate whisker represented by _{9Al 2 O 3 · 2B 2 O} 3 is a true specific gravity from 2.93 to 2.9
5, a melting point of 1400-1500 ° C., and at least one of aluminum hydroxide and aluminum inorganic salt,
At least one of boron oxide, oxyacid and alkali metal salt in the presence of a flux comprising at least one of alkali metal sulfate, chloride and carbonate;
It is manufactured by heating to 00 ° C. to react and grow.

Meanwhile, aluminum borate whisker represented by _{2Al 2 O 3 · B 2 O} 3 is a true specific gravity 2.92～
2.94, melting point 1000-1100 ° C, 9Al ₂ O ₃
・ Using the same components as those for producing B ₂ O ₃ ,
It can be produced by heating to 00 to 1000 ° C. to react and grow.

In order to further improve the reinforcing effect of various whiskers including these aluminum borate whiskers, a surface treatment with a coupling agent may be performed. In this case, the coupling agent may be a silicone type,
Titanium-based, aluminum-based, zirconium-based, zirco-aluminum-based, chromium-based, boron-based, phosphorus-based, amino acid-based and the like.

Preferred commercial products of aluminum borate whisker include Alvolex Y, manufactured by Shikoku Chemicals.
Alborex G, etc., and the average fiber diameter is 0.1.
The average fiber length is 5 to 1 μm and the average fiber length is 1 to 30 μm.

The whiskers other than those described above include P
General formula TiO such as yellow or gray tetrapot containing impurities such as b and Cd, or zinc oxide whisker (ZnO) or rutile-type white needle-like crystal in which these are broken and conical or tapered Titanium oxide whiskers ₂ and the like can also be used in the present invention.

Incidentally, the average diameter of general whiskers is as follows:
In the present invention, the average diameter is preferably 0.05 to 8 μm as described above. Furthermore, the average length of common whiskers is 1 μm or more, and is 1 to 300 μm on average, and some reach 50 to 60 mm (aspect ratio is 1 to 200). In the present invention, a fiber having a fiber length of 1 to 100 μm is preferable for the above-described reason.

When the above-mentioned whiskers are employed as the fibrous reinforcing material of the present invention, injection molding and, if necessary, cutting, are performed, whereby dimensional accuracy is improved, reinforcement is achieved, and burrs are reduced. A rolling element for sheet conveyance is obtained.

Regarding the fibrous reinforcing material such as whiskers used in the present invention, considering the damage to the mating member with which the rolling member for sheet conveyance is in sliding contact, a Mohs hardness of 1 to 10 is preferable, and 3 is more preferable. ~ 9. If the Mohs' hardness is too low, the reinforcing property cannot be expected, and if it is too high, it is difficult to suppress the damage of the sliding member.

As the Mohs hardness, either the new Mohs hardness or the old Mohs hardness evaluation test standard may be adopted.
The Mohs hardness described in the present application is evaluated based on the old Mohs hardness. In this case, for example, Mohs hardness 5 can be evaluated as one critical point, those having a Mohs hardness of less than 5 can be evaluated as having a low hardness, and those having a Mohs hardness of 5 or more can be evaluated as having a high hardness.

Whiskers having such hardness include potassium titanate whiskers, calcium carbonate whiskers, wollastonite whiskers, magnesium sulfate whiskers, aluminum borate whiskers, and the like, but in terms of fiber shape and mechanical strength, titanium is used. Particularly preferred are potassium acid whiskers and aluminum borate whiskers.

The whiskers such as potassium titanate whisker and aluminum borate whisker in the resin composition are:
The average fiber length becomes less than 10 μm when the pellet is broken during granulation or molding, and depending on the type, 1 to 5 μm
It is believed that Whiskers of such dimensions provide a very smooth surface of the rolling elements for sheet transport without impairing the fluidity during injection molding, improve non-adhesiveness, and improve the corners of molded products of rolling elements for sheet transport. Burrs are reduced in parts.

The mixing ratio of the fibrous reinforcing material in the resin composition as described above is from 65 to 10 of fluorocarbon resin.
0% by weight, fibrous reinforcing material 0 to 35% by weight, preferably 2
~ 25% by weight. If the amount of the fibrous reinforcing material exceeds 35% by weight, the non-adhesion of the fluorocarbon resin to the toner or the like is impaired, which is not preferable.

The UL standard for flammability indicated by the physical property values of the fluorocarbon resin will be described below. The flammability test method specified in UL94 includes two test methods, a horizontal flammability test 94HB and a vertical flammability test 94V. In general, a 94V evaluation method is applied to flame-retardant materials, and UL94V-0 ( Hereinafter, it is abbreviated as V-0.)
Is a stricter certification standard.

Here, as a characteristic relating to flame retardancy, a limiting oxygen index (ASTM D 2863, JIS K 7201) indicated by the physical property value of the fluorocarbon resin described above.
Will be described below. For example, PTFE, PFA,
FEP and PCTFE have a limiting oxygen index of 95% by volume or more and are nonflammable. ETFE has a limiting oxygen index of 3
0 vol%, which is less self-extinguishing than PFA, FEP, etc. However, if the limiting oxygen index is 27 vol% or more and 100 vol% or less, it has self-extinguishing properties. It can also be used accordingly. However, if importance is attached to safety with respect to flammability, it is preferable that the limiting oxygen index is at least 50% by volume or more, preferably 80 to 100% by volume.

The volume of the sheet conveying rolling element of the image forming apparatus is preferably 30,000 mm ³ or less. This is because a molded product having a volume exceeding a predetermined amount has a large “sink” and it is difficult to maintain dimensional accuracy. In addition, since it is difficult to mold a compact having a volume smaller than a predetermined volume, it is more preferably 10 to 10,000.
mm ^3, more preferably from 50~5000mm ^3.

The sheet-conveying rolling element of the image forming apparatus according to the present invention forms a recording pattern on a medium such as a photoconductor in response to an electric signal applied from the outside, and detects the amount of electricity formed on the medium. Of course, it can be applied to a printer that employs various methods of converting a pattern into a visible pattern. Examples of such a printer system include an electrophotographic system, an inkjet system, a thermal system, an optical printer system, and an electronic recording system. The types of electrophotography described above include the Carlson method, light / charge injection method, optical polarization method, photovoltaic method, charge transfer method, electrolytic electrophotography method, electrostatic latent image photography method, photoelectrophoresis method, thermostat method. The plastic method can be mentioned. Also, as an optical printer,
Laser printer, LED (light emitting diode) printer,
Examples include liquid crystal shutter printers and CRT printers.
Examples of the electronic recording method include an electrostatic recording method, a current recording method, an electrolytic recording method, and a discharge recording method, and further include a direct method and an indirect method. Also, with these electrostatic recording methods,
There are methods such as a wet method of applying oil and the like and a dry method of applying the same.

Specifically, a light-emitting diode (toner image transfer type dry electrostatic copying machine, wet electrostatic copying machine (PPC), laser beam printer (LBP), liquid crystal shutter (LCD) printer, facsimile printer, etc. L
ED), a silver salt photographic printer (CRT), a printer such as a printer, and the like.

Further, the application parts of the rolling element for conveying a sheet of the image forming apparatus according to the present invention, such as a sheet discharging section such as a photosensitive section, a developing section, and a fixing section, are not particularly limited. If the excellent heat resistance of the fluorocarbon resin is applied, it is mainly a fixing device such as a discharging roller or a middle guide roller of a fixing section or a discharging section used at a temperature higher than that of a photosensitive section or a developing section, or a kicking roller. Is suitable as a rolling element for sheet conveyance which is used on the downstream side of the transfer sheet in the conveyance direction.

[0075]

EXAMPLES The raw materials used in Examples and Comparative Examples of the present invention are collectively shown below. In addition, in [],
Heat deformation temperature (under bending stress of 4.6 kgf / cm ² , JI
SK 7207), melting point, thermal decomposition temperature, melt viscosity, number average molecular weight, hardness (ASTM D2240,
JIS K 7215), limiting oxygen index (ASTM)
D2863), the flame-retardant UL94 standard is shown in this order, and all numerical values are representative values.

(1) Polytetrafluoroethylene (PT
FE-1) made by DuPont: Teflon 7J [121 ° C, 327
° C, about 508 to 538 ° C, 10 ¹¹ to 10 ¹² poise (340 to 380 ° C), about 10 ⁶ to 10 ⁷ , D50
~ D65, 95% by volume or more, V-0] (2) Recycled polytetrafluoroethylene (PTFE-
2) Kitamura Co., Ltd .: KTL610 (3) Tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA) Asahi Glass Co., Ltd .: Aflon PFA P-63 [74 ° C.,
300 to 310 ° C, 464 ° C or higher, 10 ⁴ to 10 ⁵
Poise <380 ° C>, (2-3) × 10 ⁵ , D60
-D64, 95% by volume or more, V-0] (4) Tetrafluoroethylene-hexafluoropropylene copolymer (FEP) Asahi Glass Co., Ltd .: Aflon FEP H-330B [72
° C, 250-282 ° C, 419 ° C or higher, 4 × 10
⁴ -10 ⁵ poise <380 ℃>, (3~5) × 1
0 ^5, D60~D65,95% by volume or more, V-
0] (5) Tetrafluoroethylene-ethylene copolymer (E
TFE) Asahi Glass Co .: Aflon COP C88A [89-10
4 ° C, 260-270 ° C, 347 ° C or more, 10 ⁴
〜１０10 ⁵ poise <300 ° C.>, 1 × 10 ⁵ , D7
5, 30% by volume, V-0] (6) Aluminum borate whiskers (whisker-1) Shikoku Chemicals Co., Ltd .: Arbolex Y (fiber diameter 0.5 to
1 μm, fiber length 10 to 30 μm, Mohs hardness 7) (7) Potassium titanate whisker (whisker-2) Otsuka Chemical Co., Ltd .: Tismo N (fiber diameter 0.1 to 0.3 μm)
m, fiber length 20-30 μm, Mohs hardness 4) (8) Chloroprene rubber (CR) Denka chloroprene (9) Polyacetal (POM) Polyplastics DURACON AW-01.

[Examples 1 to 8 and Comparative Examples 1 and 2] In Example 1, the raw materials were dry-mixed and compression-molded, and the obtained molded product had an outer diameter of 9 mm, an inner diameter of 7 mm, and a width of 13.
A paper discharge roller was created by processing with 5 mm. Example 2
In Examples 4 to 5 and 8 and Comparative Example 2, raw materials were melt-mixed in the formulations shown in Table 1 and pellets formed by granulation were injection-molded by an injection molding machine under conditions suitable for each resin, and the diameter was 9 mm. ×
A paper discharge roller having a size of φ7 mm × 13.5 mm (volume of about 340 mm ³ ) was formed. Comparative Example 1 is a paper discharge roller cut out from a chloroprene rubber round bar into the above shape. The physical properties of the formed paper ejection rollers were evaluated by the following test methods, and the results are summarized in Table 1.

(1) Actual machine test A discharge roller with a boss as shown in FIG. 3 for testing is attached to a fixing device of a dry electrostatic copying machine, and 50,000 sheets of A4 size copying machine paper are continuously passed. After repeating copying for 10,000 times, the ejection rollers were taken out and the surface thereof was observed. (A) Adhesion of Toner The toner was not observed on the paper discharge roller at all, and the toner was observed at the mark of X. (B) Heat resistance The paper discharge roller, in which no deformation was observed, was evaluated as "O", and the paper discharge roller, in which deformation was recognized, was evaluated as "X" in two steps. (C) Abrasion resistance When the boss of the paper ejection roller was not worn,
Marks and those with abrasion were rated as x and evaluated in two stages. (2) Physical property test (d) Non-adhesiveness The contact angle with water was determined using a goniometer-type contact angle measuring device manufactured by Elma Optical Co., Ltd. ○ when the contact angle is 90 ° or more
The evaluation was performed by setting the mark and the contact angle less than 90 ° as the mark X. (E) Moldability Regarding whether or not it is suitable for mass production, those that can be injection-molded are marked with a circle, those that cannot be injection-molded but do not require post-processing are marked with a triangle, and post-processing without injection molding is possible. What was required was evaluated with x. (F) Flame retardancy Evaluated based on UL standard, UL94. (G) Wear resistance Using a thrust abrasion tester, inner diameter φ17 × outer diameter φ21
× Cylindrical test piece of length 10 mm, 150 ° C, load 0.5k
gf, rotation speed 200 rpm, mating material stainless steel SUS3
04. A test was performed under non-lubricated conditions to determine the amount of wear (mg).

[0079]

[Table 1]

As is clear from the results shown in Table 1, Examples 2 to 8 are capable of injection molding, have no problem in moldability, and have excellent heat resistance, flame retardancy, and abrasion resistance. It has been found that it is a paper discharge roller that does not adhere to toner due to its excellent non-adhesiveness and obtains a clear image. In addition, Example 1 had no problem other than the moldability and could be used as a rolling element for sheet conveyance.

Further, since Examples 2, 3 and 4 made of PFA, FEP and ETFE can be manufactured by the injection molding method, they are paper discharge rollers which can be manufactured at a low cost and can be molded into a complicated shape, so that productivity is improved. It was excellent in efficiency.

On the other hand, in Comparative Examples 1 and 2, adhesion of toner was observed, and heat resistance and non-adhesion (non-adhesion of toner) were poor.

[0083]

INDUSTRIAL APPLICABILITY The sheet transporting rolling element of the image forming apparatus according to the present invention can meet the demands for higher processing speed of the image forming apparatus and downsizing of the apparatus main body, and has heat resistance, flame retardancy and abrasion resistance. It is advantageous in that it is a rolling member for sheet conveyance of an image forming apparatus which is excellent in the property and non-adhesion of toner.

[Brief description of drawings]

FIG. 1 is a cross-sectional view illustrating a schematic configuration of a fixing device.

FIG. 2 is a cross-sectional view illustrating a schematic configuration of a fixing device of the color laser printer.

FIG. 3 is a perspective view of a roller with a boss.

FIG. 4 is a perspective view of a roller with a shaft hole.

FIG. 5 is a perspective view of a kicking roller.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 Heater 2, 10 Fixing roller 3, 11 Pressure roller 4 Conveying belt 5 Transfer paper 6 Inlet guide 7, 12 Separation claw 8, 13 Discharge roller 9, 14 Discharge roller 15 Intermediate guide roller 16 Drive roller 17 Kick-out roller 18, 21 Roller body 19, 22 Boss part 20 Shaft hole 30 Laser unit 31 Toner storage part 32 Drum 33 Transfer device 34 Paper storage cassette 35 Fixing device

Claims (10)

[Claims] 1. A sheet-conveying rolling element for an image-forming apparatus, which conveys an image-formed sheet, wherein the rolling element is formed of a fluorocarbon resin. 2. A rolling element for sheet conveyance of an image forming apparatus for feeding an image-formed sheet, wherein the rolling element is formed of a resin composition in which a fibrous reinforcing material is added to a fluorocarbon resin. Rolling element for sheet conveyance of image forming apparatus. 3. The fibrous reinforcing material has a fiber diameter of 0.05 to
The sheet conveying rolling member of the image forming apparatus according to claim 2, which is a fibrous reinforcing material having a fiber length of 8 μm and a fiber length of 1 to 100 μm. 4. The sheet conveying rolling element of the image forming apparatus according to claim 1, wherein the fluorocarbon resin is a tetrafluoroethylene resin. 5. The method according to claim 1, wherein the tetrafluoroethylene resin is
5. A perfluorotetrafluoroethylene.
A rolling member for conveying a sheet of the image forming apparatus according to item 1. 6. The fluorocarbon resin is a melt type fluorocarbon resin having a crystal melting point of 250 ° C. or higher and a melting point viscosity at 280 to 380 ° C. of 1 × 10 ³ to 1 × 10 ⁶ poises. The sheet conveying rolling element of the image forming apparatus according to any one of claims 1 to 3. 7. The fluorocarbon resin is a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, wherein the fluorocarbon resin is a fluorocarbon resin.
The rolling element for sheet conveyance of the image forming apparatus according to any one of items 1 to 3. 8. The sheet conveying rolling element of the image forming apparatus according to claim 1, wherein the fluorocarbon resin is a tetrafluoroethylene-hexafluoropropylene copolymer. 9. The sheet conveying device for an image forming apparatus according to claim 1, wherein the fluorocarbon resin is a tetrafluoroethylene-ethylene copolymer. Rolling body. 10. A method for manufacturing a sheet-conveying rolling element for an image-forming apparatus, which comprises forming the sheet-conveying rolling element for an image-forming apparatus by injection molding with a fluorocarbon resin.