JPS62239166A - Paper feeding roll used in image forming device - Google Patents

Abstract

PURPOSE:To obtain a paper feeding roll superior in durability which eliminates an air layer between a belt and a paper to be carried and stabilizes the electric charge, with which the belt is charged and surely carries the paper, by coating a rotary shaft with a semiconductive coating layer consisting of a specific material and having a prescribed volume resistivity to form the paper feeding roll. CONSTITUTION:A transfer belt 2 consists of a conductive or semiconductive inner layer 3 having <=10<12>OMEGA.cm volume resistivity and an outer layer 4 having >=10<12>OMEGA.cm volume resistivity. A paper P to be carried is pressed to this endless transfer belt 2 by a paper feeding roll 7 to carry the paper P. The rotary shaft 9 is coated with a semiconductive coating layer 8, which consists of at least one material selected from materials consisting of rubber including a conductive filler or not including it, a thermoplastic elastomer, an ionomers, and a synthetic resin and has 10<8>-10<12>OMEGA.cm volume resistivity, to form the paper feeding roll 7. Thus, an air layer S formed between the belt 2 and the roll 7 is eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention is used in image forming apparatuses such as PPCs (plain paper copiers) and laser printers to press conveyed paper into close contact with a transfer belt or a paper conveyance belt. This paper pertains to the paper feed roller used for this purpose.

2. Description of the Related Art In general, a transfer belt in an RPC (plain paper copying machine) functions to convey paper, transfer an image onto the paper, and separate the transferred paper.

A conventional transfer belt is composed of a dielectric outer layer having a volume resistivity of, for example, 10 to 10 17 Ω·α and a dielectric inner layer having a volume resistivity of 10 6 Ω·α or less. DC+1~2KV with brush
The surface area of the transfer belt can be increased by applying a voltage of
The paper was conveyed by being charged with an electric charge of 1000 to 1500 V and being attracted to the surface of the transfer belt by this electric charge. However, when paper is actually placed on the surface of the transfer belt, a slight air layer is formed between the paper and the surface of the transfer belt, and this air layer prevents the paper from adhering to the transfer belt. There was a problem in that the transportation of the materials was extremely unstable.

Therefore, conventionally, free-cutting steel (St.
Previously, the air layer between the paper and the transfer belt was removed by pressing the paper against the surface of the transfer belt using a paper feed roller made of steel, but the steel paper feed roller had a low volume resistivity and was electrically conductive. Because it has a sexual nature,
The problem is that the transfer belt is grounded by this steel roller, and the electric charge on the surface of the transfer belt escapes through the steel roller, making problems such as poor paper conveyance and paper jams more likely to occur. was there.

OBJECTS OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, to eliminate the air layer formed between the belt and the paper to be conveyed in an image forming apparatus, and to remove the electric charges on the belt. A paper feeder that can be stabilized, thereby ensuring reliable paper transport, preventing problems such as paper jams, and having excellent durability and low manufacturing costs. Laura is trying to provide.

Structure of the Invention In order to achieve the above object, this invention
- Pressing the paper to be conveyed onto the surface of the outer layer of an endless annular belt having a conductive or semiconductive inner layer having a volume resistivity of 1 or less and a dielectric outer layer having a volume resistivity exceeding 1012 Ω·α. A paper feed roller, which is made of at least one substance selected from the group consisting of rubber, thermoplastic elastomer, ionomer, and synthetic resin, containing or not containing conductive filler, and 10 to 101
The gist of this paper is a paper feed roller used in an image forming apparatus, in which a rotating shaft is covered with a semiconductive coating layer having a volume resistivity of 2Ω.

In the above, the rubber used as the material for the coating layer of the paper feed roller is acrylonitrile-butadiene rubber, chloroprene rubber, ethylene-propylene-diene rubber,
At least one rubber selected from the group consisting of natural rubber, urethane rubber, fluororubber, and silicone rubber.

In addition, thermoplastic elastomers include polyurethane thermoplastic elastomer, polyester thermoplastic elastomer,
Polystyrene thermoplastic elastomer, polyolefin thermoplastic elastomer, polybutadiene thermoplastic elastomer, polyamide thermoplastic elastomer, ethylene-vinyl acetate thermoplastic elastomer, polyethylene thermoplastic elastomer, fluorine thermoplastic elastomer, polyvinyl chloride thermoplastic At least one thermoplastic elastomer selected from the group consisting of plastic elastomers.

The synthetic resin is at least one synthetic resin selected from the group consisting of epoxy resin, phenol resin, polyester resin, polystyrene resin, polyolefin resin, polyamide resin, and fluorine resin.

Further, the conductive filler contained in the material of the coating layer of the paper feed roller is made of at least one conductive substance selected from the group consisting of carbon black, metal powder, carbon fiber, and metal fiber.

The content of the conductive filler is usually 0 to 30% by weight, preferably 5 to 20% by weight.

The material of the rotating shaft of the paper feed roller is not limited, and steel or other materials having the required rigidity may be used.

The coating layer of the paper feed roller has a volume resistivity of 10 to 1012 Ω. Here, if the volume resistivity of the coating layer is less than 108 Ω·1, the conductivity will be high, so the belt will be grounded by pressing the roller against the belt, and the electric charge on the belt surface will escape through the roller. This is undesirable because the charging performance of the belt decreases, causing problems such as poor paper feeding and paper jams. In addition, when the volume resistivity of the coating layer exceeds 1012Ω・crx, the dielectricity becomes large, so the charge on the belt surface transfers to the surface of the coating layer on the roller side, and as a result, the charge potential on the belt surface decreases, and vice versa. This is undesirable because the surface of the coating layer of the roller is charged, causing the paper to be conveyed to wrap around the roller, resulting in poor conveyance.

In order to prevent the surface of the coating layer of the paper feed roller from being contaminated by toner or paper scraps adhering to the transfer belt, for example, from transferring and adhering to the surface of the coating layer, it is preferable to perform the following treatment. .

(i) The surface of the coating layer of the paper feed roller is polished to make it a smooth surface with irregularities of 5 μm or less.

(ii) Coating the surface of the coating layer with a fluororesin.

(iii) For example, when using acrylonitrile-butadiene rubber (NBR), the surface is treated with concentrated sulfuric acid with a concentration of 95% or more to lower the frictional resistance of the surface. Note that for this acid treatment, concentrated hydrochloric acid or the like may also be used. Further, as a similar treatment, the rubber surface may be halogenated using, for example, sulfur chloride (32C/2).

Although it is not a treatment, for example, dioctyl phthalate (DO
It is desirable to use a material that does not contain plasticizers such as P) or dibutyl phthalate (DBP).

Note that since the paper is conveyed by being attracted to the surface of the charged belt, the hardness of the paper feed roller is not particularly limited, but it is preferably approximately 20° to 95'' (JISA).

The belt used for the paper feed roller as described above has a conductive or semiconductive inner layer having a volume resistivity of 1012 Ω·α or less and a dielectric outer layer having a volume resistivity exceeding 1012 Q-1. It has an endless ring shape.

As such a belt, the following belts (a) to (c) can be used, for example.

(a) Made of a thermoplastic elastomer or ionomer containing or not containing a conductive filler and having 10 to 10
consisting of a semiconductive inner layer having a volume resistivity of 12Ω・α, and a thermoplastic elastomer or an ionomer;
A dielectric outer layer having a volume resistivity exceeding 0.012Ω·α, and a dielectric outer layer having a volume resistivity exceeding 0.012Ω·α, and both layers are integrally bonded in an endless ring shape.

Here, the thermoplastic elastomer used as the material for the semiconductive inner layer and the dielectric outer layer and the conductive filler contained in the material include the thermoplastic elastomer and conductive filler that constitute the coating layer of the paper feed roller. Similar types can be used.

(b) A belt consisting of a conductive inner layer made of a thermoplastic elastomer or ionomer containing a conductive filler and a dielectric outer layer made of a thermoplastic resin, both layers being integrally joined in an endless ring shape.

Here, the volume resistivity of the conductive inner layer is less than 10 7 Ω·1, preferably 10 6 Ω·α or less, and the volume resistivity of the dielectric outer layer exceeds 101012 Q-, preferably 10
It is 14Ω·1 or more.

Here, the thermoplastic elastomer used as the material for the conductive inner layer and the conductive filler contained in the material are of the same type as the thermoplastic elastomer and conductive filler that constitute the coating layer of the paper feed roller. be able to.

The thermoplastic resins that make up the dielectric outer layer include polyethylene terephthalate, ionomer, polybutylene terephthalate, polyvinyl chloride, olefinic thermoplastic elastomer, polypropylene, polyethylene, fluororesin, polyacetal resin, polycarbonate, and ABS.
At least one resin selected from the group consisting of resin and polyester resin. Among these, polyethylene terephthalate and ionomer are preferably used from the viewpoint of processability.

(c) EP containing conductive filler such as carbon black
A conductive sheet made of DM or polyurethane rubber, etc. and having a volume resistivity of less than 107Ω・α, preferably 106Ω・α or less, is placed inside, and a volume resistivity of 1012Ω
・Both are bonded with the dielectric film having insulation properties exceeding 1, preferably 1014 Ω·α or more on the outside,
A belt manufactured by joining both ends of a composite sheet of the required length after lamination to create an endless belt.

In the belt of (a) above, the amount of conductive filler blended with respect to the base material of the inner layer having semiconductivity is usually 5 to 20% by weight.

In addition, the thermoplastic elastomer or ionomer constituting the dielectric outer layer is preferably a linear polymer in terms of molecular structure.

The thickness of the dielectric outer layer is usually 10-100 μm, preferably 20-60 μm. Here, the thickness of the outer layer is 100
If it exceeds μ, the charging voltage becomes low during charging due to corona discharge, which may cause transfer defects. Further, the voltage for corona discharge must be increased, which is undesirable because power consumption increases. Also, if it is less than 10 μm,
This is not preferable because the durability of the belt is deteriorated due to abrasion of the outer layer due to contact with the photoreceptor drum.

The thickness of the semiconductive inner layer is not particularly limited, but is usually 2.
It is used in the range of 00 μm to 1111 m.

Further, the inner diameter of the inner layer is, for example, 100 to 1501 m1m.

The above belt has a semiconductive inner layer of 107 to 1012 Ω.
The dielectric outer layer has a volume resistivity of 10120.1
It is said to have a volume resistivity exceeding . Therefore, when the outer layer of this belt is positively charged by a charger using corona discharge, it is charged to a required level of potential, and this is maintained for a certain period of time necessary for conveyance, transfer, etc.

Thereafter, the charge moves to the inner layer, which has a lower volume resistivity than the outer layer, so that the charged potential gradually attenuates and the charge disappears. Therefore, after the transfer, there is no need to remove the electric charges remaining on the belt surface using a static eliminator as in the conventional case.

An adhesive layer is optionally interposed between the semiconductive inner layer and the dielectric outer layer. Here, an appropriate adhesive layer is used depending on the type of thermoplastic elastomer or ionomer constituting the base material of the inner layer and the thermoplastic elastomer or ionomer constituting the outer layer.

The thickness of the conductive inner layer of the belt (b) above is approximately 0.
1-2 mm, and the thickness of the dielectric outer layer is 20-20 mm.
0 μm, preferably 40 to 100 μm. The inner diameter of the conductive inner layer is, for example, 100 to 150 ml.

The conductive inner layer is made of a thermoplastic elastomer or ionomer as a base material, into which about 20 to 30% by weight of a conductive filler is mixed, and the dielectric outer layer is made of the above-mentioned thermoplastic resin.

The belts (a) and (b) above are produced by simultaneously and integrally molding a conductive or semiconductive inner layer, a dielectric outer layer, and in some cases an intermediate adhesive layer, for example by extrusion blow molding. It will be done.

That is, a 2-layer or 3-layer spiral mandrel die (if an intermediate adhesive layer is provided) is set, and the inner layer material is applied to this die using an extruder with a diameter of 5QI1m, for example.
Extrude the outer layer material at the same time using a mm extruder, thereby obtaining a tubular molded product in which a conductive or semiconductive inner layer and a dielectric outer layer are integrated, and an air ring is provided at the die exit to keep the shape constant. The resin is held, then cooled to solidify the resin in both layers, and then cut to a certain size.

Example Next, embodiments of the present invention will be described based on the drawings.

Embodiment 1 FIG. 1 shows an RPC using a paper feed roller according to the present invention.
(plain paper copy m>).

In the figure, (1) is a photoreceptor drum, (2) is a transfer belt arranged horizontally below the photoreceptor drum (1), and this is a pair of front and rear rotation drive rollers (5) and (6). The photoreceptor drum (1) is rotated in synchronization with the photoreceptor drum (1). (7) is the paper feed roller of the present invention arranged above the starting end of the transfer belt (2), and (10) is the transfer belt (2).
2) is a pair of upper and lower paper feeding timing rolls arranged near the starting end; (11) is a charger; and (12) is a cleaning blade arranged below the terminal end of the transfer belt (2).

Here, a paper feed roller manufactured as follows was used.

NBR100 parts by weight Conductive carbon black 20 〃15AF carbon black 20 〃Anti-aging agent
1 Zinc oxide (ZnO) 5
t+stearin W1 1 〃Vulcanization accelerator 1.5 〃Vulcanizing agent
3.

Knead the NBR compound with the above blending ratio in a kneader,
After forming the mixed wire into a tube shape using an extrusion molding machine, the tubular extrusion molded product is steam-vulcanized in a vulcanizer to create a coating layer (8) made of a vulcanized tube,
The rotating shaft (9) is inserted into the coating layer (8), and then the surface of the coating layer (8) is polished, treated with concentrated sulfuric acid for 5 seconds, and the surface is washed and dried. A feed roller (7) was manufactured. The properties of this paper feed roller (7) were as follows.

Paper feed roller (7) Outer diameter of coating layer 15mm Length of N layer 3131 Outer diameter of rotating shaft Bmm Rubber hardness (JISA) 75° Volume resistivity of coating layer 108Ω・ctg Frictional resistance of roller surface 0.3 ( Roughness of the roller surface (relative to copy paper): 5 μm On the other hand, the transfer belt (2) is coated with carbon black 1 as a conductive filler.
Polyurethane thermoplastic elastomer containing 0% by weight (
A semiconductive inner layer (3) made of ester-based thermoplastic elastomer and a dielectric outer layer (4) made of polyamide (nylon 12)-based thermoplastic elastomer are integrally bonded in an endless ring shape. The inner diameter of the transfer belt (2) is 115ml
The length and width are 320911, and the thickness of the outer layer (4) is 50μ. Here, the properties of the inner layer (3) and the outer layer (4) are as follows.

Semi-conductive (3) Hardness J l5A) 80° breaking strength
430 Ka/cm2 elongation at break
550% tear strength 90 to Q/lx volume resistivity
1.6X1011Ω・Thickness 3
00μm Inner diameter 115111 Dielectric outer layer (4) Hardness Shore D) 62° break 17 strength K 400g/CIa2 elongation at break 300% Volume resistivity 1X1013Ω・crn thickness
50 μm Paper feed roller (7) and transfer belt (2) according to the present invention
) was used to implement the PPC transfer mechanism, and the charge M on the transfer belt (2) was stable at +1200 to +1400V.
The conveyed paper (P) is firmly attached to the transfer belt (2).
The air layer (S) was removed, and the paper (P) was reliably attracted to the transfer belt (2) and conveyed, and there were no problems such as poor conveyance or paper jams. Note that after the transfer, the charged potential of the transfer belt (2) gradually attenuates and the charge disappears.
There is no need to remove static electricity when separating paper.
Therefore, a static eliminator is not required.

Example 2 Although not shown in the drawings, a paper feed roller (7) and a conveyance belt (
2) was used in the conveyance section of the transfer mechanism of a laser printer.

Blending ratio: 100 parts by weight of thermoplastic urethane elastomer, 54 parts by weight, 15 parts by weight of electrically conductive carbon black.The compound having the above-mentioned mixing ratio was put into a kneader. Next, this pellet is put into the injection molding machine, and the rotating shaft (9) is placed in the mold in advance.
was inserted, and the coating m (8) was integrally formed on the rotating shaft (9) using an injection molding machine, thereby producing an elastic paper feed roller (7). The properties of this paper feed roller (7) are as follows:
It was as follows.

Paper feed roller (7) Outer diameter of coating layer 12+n+n Length of covering layer m 280m 111 Outer diameter of rotating shaft
Bmm Rubber hardness (JISA) 83° Volume resistivity of coating layer 109Ω・art Roller surface friction resistance 0.5 (relative to copy paper) Roller surface roughness 4 μm On the other hand, the conveyor belt (2) is made of conductive filler. carbon black 3
A conductive inner layer (3) made of a thermoplastic polyurethane elastomer containing 0% by weight and a dielectric outer layer (4) made of an ionomer are integrally bonded in an endless ring shape. The inner diameter of the conveyor belt (2) is 115 mm+ and the width is 320 mm. Here, the properties of the inner layer (3) and the outer layer (4) are as shown below.

Conductive inner layer (3) Hardness JISA) 82° Breaking strength 450g/cI12 Breaking elongation 500% Tear strength 90 KQ/as Volume resistivity 1×106Ω・1 Thickness 400 μm Inner diameter 115 mm Dielectric outer layer (4) Hard Shore D) 50~65° breaking strength
300 KM cm2 elongation at break
500% Dielectric constant 2~3 Volume resistivity 1X1018Ω'cm thickness
50μl Paper feed roller (7) and transfer belt (2) according to the present invention
) was used to carry out the conveyance part of the transfer mechanism of a laser printer, and the charge on the conveyor belt (2) was +15.
00V and stable, and as in the case of Example 1, the paper to be transported (P) is firmly pressed against the surface of the transport belt (2) by the paper feed roller (7), and the air layer (S)
was removed, the paper (P) was reliably attracted to the transfer belt (2) and conveyed, and no troubles such as poor conveyance or paper jams occurred.

Effects of the Invention The paper feed roller used in the image forming apparatus of this invention is
As mentioned above, a conductive or semiconductive inner layer (3) having a volume resistivity of 10 12 Ω·α or less, and a 10 12 Ω
- A paper feed roller (7) that presses the paper to be conveyed (P) onto the surface of the outer layer (4) of an endless annular belt (2) having a dielectric outer layer (4) having a volume resistivity exceeding at least one substance selected from the group consisting of rubber, thermoplastic elastomer, ionomer, and synthetic resin containing or not containing conductive filler;
Since the semiconductive coating layer (8) having a volume resistivity of 0 to 1012 Ω is placed on the rotating shaft (9), when the paper (P) is conveyed in the image forming apparatus,
The air layer (S) formed between the belt (2) and the conveyed paper CP) can be removed, and the belt (2)
This allows the paper (P) to be transported reliably, prevents troubles such as paper jams, and has excellent durability. , and has the effect of reducing manufacturing costs.

[Brief explanation of drawings]

Fig. 1 is a schematic side view of a PPC (plain paper copying machine) using the paper feed roller of the present invention, Fig. 2 is a partially omitted enlarged front view of the product of the present invention, and Fig. 3 is a paper feed mechanism according to the product of the present invention. FIG. (1)...Photosensitive drum, (2)...Transfer belt (
@Feeding belt), (3)...inner layer, (4)...outer layer,
(7)...Paper feed roller, (8)...Coating layer, (9
)...rotating shaft, (P)...conveyed paper, (S)...
air layer. The above procedures have been amended! i Crime June 24, 1985 1, Incident Indication 1985 Patent Application No. 844748
2. Name of the invention: Paper feed roller 3 used in an image forming apparatus, name of person who corrects it: Yamauchi Rubber Industries Co., Ltd.

Claims (2)

[Claims] (1) A conductive or semiconductive inner layer having a volume resistivity of 10^1^2 Ω·cm or less, and 10^1^2 Ω·c
A paper feed roller that presses the paper to be conveyed against the outer surface of an endless annular belt having a dielectric outer layer having a volume resistivity exceeding m, the paper feed roller comprising rubber, thermoplastic elastomer, with or without conductive filler, A semiconductive coating layer made of at least one substance selected from the group consisting of ionomers and synthetic resins and having a volume resistivity of 10^8 to 10^1^2 Ωcm is placed on the rotating shaft. A paper feed roller used in an image forming apparatus. (2) The rubber used as the material for the coating layer of the paper feed roller is selected from the group consisting of acrylonitrile-butadiene rubber, chloroprene rubber, ethylene-propylene-diene rubber, natural rubber, urethane rubber, fluororubber, and silicone rubber. at least one rubber;
The thermoplastic elastomer is a polyurethane thermoplastic elastomer, a polyester thermoplastic elastomer, a polystyrene thermoplastic elastomer, a polyolefin thermoplastic elastomer, a polybutadiene thermoplastic elastomer, a polyamide thermoplastic elastomer, an ethylene-vinyl acetate thermoplastic elastomer, At least one thermoplastic elastomer selected from the group consisting of a polyethylene thermoplastic elastomer, a fluorine thermoplastic elastomer, and a polyvinyl chloride thermoplastic elastomer, and the synthetic resin is an epoxy resin, a phenolic resin, or a polyester. The conductive filler contained in the material of the coating layer is carbon black, The paper feed roller according to claim 1, which is made of at least one conductive material selected from the group consisting of metal powder, carbon fiber, and metal fiber.