JP2000255816A - Document conveying belt and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a document conveying belt which has a characteristic basically required as a document conveying belt, and a uniform, stable, and anti-static conductivity, and a permanent elongation characteristic satisfying a level required as a document conveying belt. SOLUTION: This conveying belt is made of a thermoplastic elastomer. On this occasion, the thermoplastic elastomer is of a phase separation structure obtained by reacting active hydrogen base-containing compound and isocyanate base-containing compound under the presence of vinyl chloride-based polymer to thereby form polyurethane. The thermoplastic elastomer is not added with a conductive filler, and is 106-1011 Ω.cm in volume-dependent resistance. The belt manufacture includes a step of forming a seamless belt, and a preliminarily elongating step of heating the formed belt to not less than 60 deg.C to carry out annealing, while elongating it by least 3% in its circumferential direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention conveys paper sheets such as paper and film, particularly originals, in image forming apparatuses such as electrophotographic copying machines, image input apparatuses such as scanners and image readers, and transfer apparatuses. The present invention relates to an elastic seamless belt used for the following. The elastic seamless belt of the present invention can also be used for a paper sheet transport device in another printing machine or the like.

[0002]

2. Description of the Related Art In a document feeder used for transferring a document to an exposure position in a copying machine, an image reader, or the like and stopping the document at a predetermined position, conventionally, a polyurethane resin is woven on a fiber woven fabric of polyester or the like. Coated core belts and elastomeric belts that do not use woven fabric are known.

[0003] Elastomeric belts that do not use a core material have been used in many cases because the manufacturing process of the core belt is complicated and the tension load mechanism when the belt is mounted on the apparatus becomes complicated.

[0004] However, acrylonitrile-butadiene rubber (NBR) and ethylene propylene rubber (EPDM) which are generally used as elastomer belts at present.
Vulcanized rubber original transport belts have a molecular structure in which the polymer materials constituting them are three-dimensionally cross-linked, and are difficult to recycle, and are recyclable from the viewpoint of environmental protection. Is required.

[0005]

A belt generally used in a paper sheet transporting device such as a copying machine is mounted with a predetermined tension applied by at least two rolls. Standard A3 size (about 30cm x 42cm)
The sheet required has a size necessary for pressing the sheet against the platen glass, and has a width of about 300 mm or more, a circumference of about 800 mm or more, and a thickness of about 0.6 to 1.3 mm.

The characteristics required for such an elastomer belt include the following characteristics in addition to the stain prevention performance described in the above-mentioned known art. (1) The belt should not be worn due to the sliding of the platen glass and the belt, and no wear debris should adhere to the glass surface. (2) The document can be accurately stopped at a predetermined image reading position. (3) The coefficient of friction between glass and belt is as small as possible, and the coefficient of friction between paper and belt is as large as possible. (4) The belt should not be charged by friction with a platen glass or the like so as not to cause a problem such as a paper jam when discharging the document. (5) Permanent elongation is small because the belt tension is not reduced due to long-term use, and performance degradation such as reduction in document feeding accuracy does not occur.

[0007]

However, a belt made using a conventionally known thermoplastic elastomer, in particular, has insufficient properties (4) and (5). In the prior art, there is no known document transport belt made of a thermoplastic elastomer whose permanent elongation is at a practical level. In addition, a conductive filler may be added to prevent the electrification of the original transport belt. However, the original transport belt often serves as a background for copying, and carbon black cannot be used. The use of conductive titanium oxide or indium-tin oxide (ITO), which is a white or transparent conductive filler, tends to cause non-uniformity of electrical resistance during molding, and these conductive fillers are expensive. However, this is not preferable.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an original conveying belt with characteristics basically required, and furthermore, to provide a uniform and stable conductive property sufficient for preventing static electricity, and to obtain a permanent image which cannot be achieved by a conventional thermoplastic elastomer. An object of the present invention is to provide a document conveying belt whose elongation satisfies a level required for the document conveying belt and a method of manufacturing the same.

[0009]

According to the present invention, there is provided a seamless document conveying belt formed of a thermoplastic elastomer, wherein the thermoplastic elastomer has a vinyl chloride polymer component and an elastomer component phase-separated into a sea-island structure. Volume resistivity having a micro phase-separated structure of 10 ⁶ to 10 ¹¹ Ω
・ Cm is a thermoplastic elastomer.

By using such a thermoplastic elastomer, it is possible to obtain a document conveying belt having a stable antistatic property without change in electric resistance due to long-term use and non-uniformity in electric resistance during molding. Can be Further, since an expensive conductive filler such as ITO is not used, the cost is low and the recycling is possible.

Further, the thermoplastic elastomer has a sea-island structure microphase-separated structure,
A belt having high strength and low permanent elongation is obtained, which meets the object of the present invention. The sea-island structure may be either a vinyl chloride polymer or elastomer component at sea and any island may be an island, but the physical properties of the vinyl chloride polymer at sea are suitable for a document transport belt. Is preferable.

The elastomer component is preferably at least one of a polyester elastomer and a polyurethane elastomer.

The ester bond of the polyester elastomer and the urethane bond and urea bond of the polyurethane elastomer have a high cohesive energy, and the thermoplastic elastomer using them has particularly high strength and low permanent elongation.

In the document conveying belt of the present invention, the thermoplastic elastomer is obtained by reacting an active hydrogen group-containing compound with a polyisocyanate compound in the presence of a vinyl chloride polymer to form a polyurethane elastomer. It is preferably a thermoplastic elastomer having a microphase-separated structure having a phase-separated structure.

By using the above-mentioned thermoplastic elastomer, it is possible to obtain a document conveying belt having a particularly high strength, a small permanent elongation, and a predetermined volume resistivity. The sea-island structure may be such that any of the vinyl chloride polymer and the elastomer component is at sea and any of the islands are islands. A thermoplastic elastomer having a structure,
It is particularly suitable as the material for the original transport belt of the present invention.

It is preferable that the original conveying belt is formed by forming the thermoplastic elastomer into a seamless belt shape, and then annealing it by heating it to 60 ° C. or more in a state of being stretched at least 3% in the circumferential direction. .

When the above-mentioned thermoplastic elastomer is used, the belt subjected to such treatment has a particularly small permanent elongation.

The present invention also relates to a method for manufacturing a seamless document conveying belt formed of a thermoplastic elastomer, wherein the thermoplastic elastomer has a microstructure in which a vinyl chloride polymer component and an elastomer component are phase-separated into a sea-island structure. It has a phase-separated structure and the volume resistivity is 10 ⁶ to 10 ¹¹ Ω
cm, forming the thermoplastic elastomer into a seamless belt, and at least 3% in the circumferential direction.
The method is characterized by including an annealing treatment step of heating to 60 ° C. or more in a stretched state.

[0019]

According to such a manufacturing method, it is possible to obtain a document conveying belt having a practical level of antistatic performance and permanent elongation. That is, after forming a molded belt by molding a thermoplastic elastomer into a belt shape, the molded belt is heated to 60 ° C. or more while being stretched at least 3% in the circumferential direction, thereby obtaining a permanent belt particularly required as a document conveying belt. It is possible to achieve an elongation of 10% or less at 50% elongation, 5% or less at 20% elongation, and 1% or less at 3% elongation commonly used in copiers for elongating document transport belts. it can.

If the elongation percentage in the preliminary elongation is less than 3%, the permanent elongation may not be able to achieve a practical level. The upper limit of the elongation at the time of molding is not particularly limited. However, if the elongation is too large, the width and thickness also fluctuate. Therefore, the upper limit is preferably 50% or less, and particularly preferably 5 to 20%. The heating temperature is not lower than 60 ° C. and not higher than the flow start temperature of the resin. Particularly, the range of 60 ° C to 100 ° C is preferable. The heating time varies depending on the temperature, but is preferably about 300 minutes at 60 ° C. and about 120 minutes at 90 ° C.
A more preferred heating temperature is 65 to 80 ° C.

In the above-mentioned production method, the thermoplastic elastomer may have a sea-island structure obtained by reacting an active hydrogen group-containing compound with a polyisocyanate compound in the presence of a vinyl chloride polymer to form a polyurethane. Particularly preferred is a thermoplastic elastomer having a separated microphase separation structure.

By using such a thermoplastic elastomer, it is possible to manufacture a document conveying belt having particularly excellent antistatic performance, high strength and small permanent elongation.

It is a preferred embodiment to provide unevenness such as a grain on the contact surface of the document conveying belt of the present invention with the document in order to secure a high frictional force with the document. It is also preferable that the belt be colored white or light.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION The document conveying belt of the present invention is formed of a thermoplastic elastomer having a microphase-separated structure and has a volume resistivity of 10 ⁶ to 10 ¹¹ without adding a conductive filler. Ω · cm can be achieved uniformly, triboelectric charging does not occur, and permanent elongation is small.

The copolymerizable monomer of the vinyl chloride polymer, which is a constituent material of the thermoplastic elastomer used for the document conveying belt of the present invention, includes olefins such as ethylene;
Examples thereof include vinyl alcohol esters such as vinyl acetate, and commercially available ethylene vinyl chloride copolymers and vinyl chloride vinyl acetate copolymers can be used.

It is a preferred embodiment that a plasticizer is added to the vinyl chloride polymer as required, and a phthalate plasticizer such as dioctyl phthalate (DOP), diisononyl phthalate, dibutyl phthalate, etc .; Examples include adipate plasticizers such as adipate, and sebacate plasticizers such as diisobutyl sebacate and dioctyl sebacate. It is also preferable to use a high-molecular-weight plasticized resin in place of such a low-molecular-weight plasticizer, and an ionomer resin is exemplified as a suitable plasticized resin. When a plasticizing resin is used in place of the plasticizer, there is no component that dissolves the toner, so that the fusion of the toner to the back surface of the belt or the like can be more completely prevented, and it is particularly preferable from the viewpoint of environmental protection.

As the polyester elastomer which is another constituent material of the thermoplastic elastomer used for the transfer belt of the present invention, an aromatic dicarboxylic acid such as terephthalic acid, naphthalenedicarboxylic acid, diphenyldicarboxylic acid or isophthalic acid is used as a main component. Ethylene glycol, propylene glycol, low molecular weight glycols such as 1,4-butanediol and polyoxytetramethylene glycol,
Molecular weight of 400 to 1 such as polyoxypropylene glycol
A polyester elastomer having a structure formed by a low molecular weight glycol and an aromatic dicarboxylic acid as a hard segment and an oligomer glycol as a soft segment is used as an example.

Polyurethane, which is another component of the document conveying belt of the present invention, is formed by reacting a diisocyanate compound with a polyol compound as an active hydrogen group-containing compound and a low molecular weight polyfunctional chain extender,
An elastomer having a structure composed of a diisocyanate compound and a chain extender as a hard segment and a polyol compound as a soft segment.

Examples of the polyol compound include polyester polyols, polyether polyols, polycarbonate polyols, polybutadiene polyols, polyisoprene polyols, polyolefin polyols, which are well-known polyol compounds in the field of polyurethane.
Polyacrylic ester-based polyols and telechelic polyols (disclosed in JP-A-7-206973) can be used without limitation.

As the chain extender, any chain extender known in the polyurethane technical field which is used for improving physical properties and the like of polyurethane can be used without limitation. 4-butanediol,
Neopentyl glycol, 1,6-hexanediol,
Aliphatic polyhydric alcohols such as spiroglycol, aromatic polyhydric alcohols such as bishydroxyethoxybenzene, xylylene glycol, bis (β-hydroxyethyl) terephthalate, and aromatic compounds such as methylenebis-o-chloroaniline (MOCA) Aromatic diamines are exemplified.

As the polyisocyanate compound which is a material constituting the above-mentioned polyurethane, a diisocyanate compound known in the technical field of polyurethane can be used without any limitation. Specifically, 4,4′-diphenylmethane diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, aromatic diisocyanate compounds such as naphthalene diisocyanate, ethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, Aliphatic diisocyanate compounds such as 1,6-hexamethylene diisocyanate (HDI), hydrogenated 4,4′-diphenylmethane diisocyanate (HMDI, trade name Hylen-W, manufactured by Huls), 1,4-cyclohexane diisocyanate (CHDI), Isophorone diisocyanate (IP
DI), hydrogenated m-xylylene diisocyanate (H
XDI), alicyclic diisocyanates such as norbornane diisocyanate, xylylene diisocyanate (XDI), tetramethyl xylylene diisocyanate (TMXDI) and the like.

When producing a thermoplastic elastomer, a tin-based compound for promoting a polyurethane-forming reaction,
It is also preferable to use a known catalyst such as a tertiary amine compound.

Among the thermoplastic elastomers described above, a thermoplastic elastomer containing polyurethane as an elastomer component is obtained by mixing a polyurethane constituent material such as an isocyanate group-containing compound and an active hydrogen group-containing compound in the presence of a vinyl chloride polymer. It is manufactured by applying a shearing force to cause polymerization.

The thermoplastic elastomer thus obtained has a phase separation structure having a sea-island structure including islands of about 0.1 to 100 μm. If the size of the island is out of the above range, the physical properties required for the present invention cannot be sufficiently exhibited, which is not preferable.

The thermoplastic elastomer containing polyurethane as an elastomer component includes Elastage ES.
5000A, ES5001A, ED1920N, ED1
101W (manufactured by Tosoh Corporation) and the like are commercially available and can be used.

When a belt is formed from the thermoplastic elastomer of the present invention, it is a preferred embodiment to add various additives, for example, a coloring agent such as a coloring matter or a pigment, a processing aid, and the like. In particular, use of a white filler is preferable, and use of rutile-type titanium oxide, anatase-type titanium oxide, silica, barium carbonate, calcium carbonate, or the like is preferable.

Known compounds can be used as the ionic conductive filler that can be added as necessary. Specifically, lithium perchlorate, ammonium thiocyanate, lithium thiocyanate and the like are suitable compounds. Is exemplified.

The document conveying belt of the present invention can be molded by any of the thermoplastic resin molding methods such as injection molding and extrusion molding. The belt may be formed thicker and polished to a predetermined thickness.

The document conveying belt generally has a thickness of about 0.1 mm.
The width is 5 to 1.5 mm, the width is 200 mm or more, and the circumference is about 150 mm to 1200 mm, depending on the application. In a preferred embodiment, a coating layer is provided on the original contact surface of the original conveying belt of the present invention in order to further improve the prevention of contamination. Such a coating film layer is a coating resin layer having a relatively high hardness or a resin layer containing a material having excellent lubricity, and specifically, polytetrafluoroethylene fine powder, boron nitride (BN) fine powder, or the like. It is preferably a transparent or white coating layer obtained by coating a lubricating paint obtained by dispersing a highly lubricious material having a white color or a color close to the above in a polyurethane paint or the like.

In the production of the original conveying belt of the present invention,
The following method is specifically exemplified as a method of heating in a stretched state, which is a means for improving the permanent elongation of the belt in the preliminary stretching step. (1) A method of extending and inserting into a cylindrical mold (mandrel) having an outer circumference larger than the circumference of the forming belt and heating. (2) A method in which the forming belt is set on two rollers, the gap between the rollers is enlarged to a predetermined elongated state, and preferably, the belt is heated while being driven. (2) A method in which a molding belt is set on a roller having two fixed shafts, and a third roller is pressed against the belt to bring it into a predetermined elongated state, and preferably, the belt is heated while being driven.

As described above, in the case of coating the belt surface to form a coating film layer, the pre-stretching step of the belt is performed by preparing a coating mandrel for holding the belt at the time of coating so as to have a predetermined elongation rate. It is also a preferable embodiment to use the method simultaneously with the step of applying a molded belt and heating the paint for drying and curing.

[0043]

Embodiments of the present invention will be described below. (Example 1) Elastage ES5021A was used as a thermoplastic elastomer, and a thickness of 0.1 mm was obtained using an extruder.
A belt having a length of 8 mm and a circumference of 870 mm is continuously extruded and cut to a width of 315 mm to form a formed belt, which has a diameter of 304 mm (outer circumference = 958 mm, elongation ratio = 10.
(0%), and stretched and inserted through a cylindrical mold, and heated in an oven at 70 ° C. for 180 minutes to obtain a document conveying belt.

(Comparative Example 1) A belt having a circumference of 958 mm was formed from the beginning by extrusion molding, and a comparative example belt was obtained without preliminary stretching.

[Evaluation] A strip-shaped sample having a width of 10 mm and a length of 130 mm was prepared from the belt samples of Example 1 and Comparative Example 1, and the permanent elongation (PS) was measured.

The measurement of permanent elongation is as follows. In the above measurement sample, the distance between the reference lines is set to 90 mm, and the distance between the reference lines is extended to be 135 mm (50% elongation), and is maintained at 50 ° C. for 24 hours in this state. After releasing the elongation, leave at room temperature for 10 minutes, and distance between marked lines L (mm)
Is measured, and the permanent elongation is determined by the following equation. PS (%) = 100 (L−90) / 90 In the belt of Example 1, PS = 0.6%, which is almost the same value as the vulcanized rubber-based document conveying belt used so far. Although practical, the belt of Comparative Example 1 was made of PS
= 2.2%, which was not practical.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Riichiro Ohara 1-17-18 Edobori, Nishi-ku, Osaka-shi, Osaka F-term in Toyo Tire & Rubber Co., Ltd. 3F049 BA11 LA02 LA03 LA05 LA07 LB02 4F213 AA15 AA24 AA31 AA45 AE03 AG16 AH12 WA06 WA53 WA83 WA90 WB01 WW02

Claims (6)

[Claims] 1. A seamless document conveying belt formed of a thermoplastic elastomer, wherein the thermoplastic elastomer has a volume having a microphase-separated structure in which a vinyl chloride polymer component and an elastomer component are phase-separated into a sea-island structure. A document transport belt made of a thermoplastic elastomer having a specific resistance of 10 ⁶ to 10 ¹¹ Ω · cm. 2. The document conveying belt according to claim 1, wherein said elastomer component is at least one of a polyester elastomer and a polyurethane elastomer. 3. A microphase phase-separated into a sea-island structure obtained by reacting an active hydrogen group-containing compound with a polyisocyanate compound in the presence of a vinyl chloride polymer to form a polyurethane elastomer. 3. A thermoplastic elastomer having a separation structure.
The document transport belt described in 1. 4. The document conveying belt is formed by forming the thermoplastic elastomer into a seamless belt shape, and then annealing it by heating it to 60 ° C. or more in a state where it is stretched at least 3% in the circumferential direction. Item 4. The document transport belt according to any one of Items 1 to 3. 5. A method for manufacturing a seamless document conveying belt formed of a thermoplastic elastomer, wherein the thermoplastic elastomer has a microphase-separated structure in which a vinyl chloride polymer component and an elastomer component are phase-separated into a sea-island structure. A step of forming the thermoplastic elastomer into a seamless belt shape having a volume resistivity of 10 ⁶ to 10 ¹¹ Ω · cm, and heating to 60 ° C. or more in a state where the thermoplastic elastomer is elongated by at least 3% in the circumferential direction. A method of manufacturing a document transport belt including an annealing process. 6. Microphase separation obtained by reacting an active hydrogen group-containing compound with a polyisocyanate compound in the presence of a vinyl chloride polymer to form a polyurethane, wherein the thermoplastic elastomer is phase-separated into a sea-island structure. The method according to claim 5, wherein the method is a thermoplastic elastomer having a structure.