JP2003002478A - Seamless belt, and manufacturing method for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a seamless belt and a manufacturing method for the same capable of having a high extension modulus while having flexibility required as a belt so as to provide satisfactory carrying accuracy, reducing expansion and contraction caused by tensile force fluctuation in starting and stopping driving and having excellent image accuracy especially when used as a transfer belt, and being formed easily. SOLUTION: The seamless belt contains a polyol component and an isocyanate component as constituents and contains an isocyanurate bond as a copolymer constituent bond. The seamless belt can be manufactured by making the polyol component and isocyanate component of the seamless belt as a prepolymer having an NCO group by reacting the NCO group and an active hydrogen group with an excess NCO group, adding an isocyanurate bond forming catalyst to an NCO prepolymer, and forming in a belt shape by a mold.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a seamless belt and a method for manufacturing the seamless belt. The seamless belt of the present invention, in addition to general belts for conveying articles, particularly copying machines,
It is suitable as a conveyor belt for paper sheets in image forming apparatuses such as printers and facsimiles, and particularly, in toner image formed on a photoconductor, a transfer belt, etc. in an electrophotographic image forming apparatus such as an electrophotographic copying machine. It is suitable as a transfer belt used in the step of transferring onto plain paper or the like. The transfer belt is another device that uses the basic principle of electrophotography, such as a laser beam printer,
It can be used for a facsimile and the like, and can also be used for an intermediate transfer belt used in a color copying machine using a plurality of types of color toners.

[0002]

2. Description of the Related Art An image forming apparatus such as an electrophotographic copying machine, which is generally called a plain paper copying machine, forms a toner image formed by toner electrostatically attached on a photoconductive photoconductor. Copying by transferring to plain paper, film, etc., the paper carrying the transferred toner image is conveyed to the fixing roller by a paper feeding means such as a belt, and passed through the heated fixing roller to be fixed on the paper. The basic principle is to form an image or a print image.

In a color copying machine or a color printer, a structure in which a plurality of color toners are carried and then transferred to a sheet is also used.

In such an image forming apparatus, a transfer belt is being adopted for the purpose of providing a transfer function and a sheet feeding function together to make the transferred image clear and reduce the number of parts.

As transfer belts, elastic belts and resin belts are currently in practical use and are known. The resin belt includes a transfer belt made of polyimide resin and a thermoplastic resin belt made of polycarbonate or the like. The polyimide resin belt has to be manufactured by applying a polyamic acid solution to the surface of a cylindrical mold by a centrifugal molding method, drying, and polymerizing, and the process is complicated, and the polyimide resin itself is expensive. However, it is difficult to meet the demand for cost reduction. Further, since the polyimide resin is hard and brittle, there is a problem that it is damaged due to slight scratches or wrinkles.

On the other hand, as the elastic belt, a rubber belt, a thermoplastic polyurethane belt, and a polyurethane / urea belt are known. Although the rubber belt is high in strength and excellent in flexibility, it has a problem that it is difficult to keep up with the demand for image clarity because it expands and contracts due to tension fluctuations at the start and stop of driving.

The above polyurethane / urea belt is
JP 2000-250328 A, JP 2000-1
It is known in Japanese Patent Application No. 0417, Japanese Patent Application Laid-Open No. 11-231662, and Japanese Patent Application Laid-Open No. 11-125974.

Such a polyurethane / urea belt has flexibility equivalent to that of a rubber belt, and although expansion and contraction due to tension fluctuation at the start and stop of driving is smaller than that of a rubber belt, stress at 100% elongation is at most. The pressure is 20 MPa, which is not sufficient for a transfer belt that requires higher-precision images, and there is room for improvement.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to provide a belt having a high flexibility and a high elongation modulus, and therefore a high conveyance accuracy. Especially, when the belt is used as a transfer belt, driving start or stop is started. An object of the present invention is to provide a seamless belt which is small in expansion and contraction due to fluctuations in tension, has excellent image accuracy, and is low in cost as a material, and a manufacturing method thereof.

[0010]

The seamless belt of the present invention is characterized by containing a polyol component and an isocyanate component as constituent components and an isocyanurate bond as a polymer constituent bond.

By using a polymer containing an isocyanurate bond, the elongation modulus is high while having the flexibility required for a belt, and therefore the conveying accuracy is excellent,
In particular, when used as a transfer belt, there is little expansion and contraction due to tension fluctuations at the start and stop of driving, and the image accuracy is excellent, and a seamless belt at a lower cost than the polyimide belt can be obtained.

In the seamless belt of the present invention, at least one of a urethane bond and a urea bond is contained as a polymer constituent bond in addition to the isocyanurate bond,
Furthermore, a bond derived from an isocyanate group such as an allophanate bond or a buret bond may be contained.

The above seamless belt contains a conductive filler and has an average volume resistivity of 10 ⁴ to 10 ^12.
The ratio R _max / R between the maximum value R _max and the minimum value R _min of the volume resistivity measured with the electrodes in contact with each other in the range of Ω · cm.
It is preferable that _min is 10 or less.

[0014] containing a conductive filler, the average value of the volume resistivity of 10 ⁴ ~10 ¹² Ω · the range of cm, and the ratio between the maximum value R _max and the minimum value R _min of the volume resistivity R _max / R _min
By setting 10 to 10 or less, a seamless belt having excellent characteristics such as charging and discharging required for a transfer belt and uniformity of images can be obtained.

The seamless belt of the present invention preferably further has at least one lubricating surface layer.

If the lubricating surface layer is provided on the surface side, that is, on the surface where the toner is wiped out when it is used as an intermediate transfer belt, for example, excess toner is removed by a cleaning means such as a cleaning blade or a cleaning brush after the transfer is completed. In this case, the toner remaining on the surface can be simply and completely removed, and the belt can form a clearer image. If a lubricating surface layer is provided on the back surface, that is, on the contact surface of the drive roller, toner and paper dust that are scattered inside the machine adhere and the friction coefficient with the drive roller fluctuates, or the driving force of the belt fluctuates, or It is possible to prevent a problem such as a decrease in the charge removing effect of the belt due to the charge eliminating electrode.

It is also suitable to add a conductive filler to the lubricating surface layer to adjust the electric resistance in order to form a more desirable image in response to the demand for the performance of the image forming apparatus. Further, a conductive resin such as polyacetylene or polyaniline may be used as the resin itself constituting the surface layer.

The belt manufactured by the manufacturing method of the present invention has a thickness of 0.1 mm to 1.0 mm, more preferably 0.1 to 0.5 mm.

If the thickness is less than 0.1 mm, the strength of the belt may be insufficient, and if it exceeds 1.0 mm, the flexibility may be deteriorated and the belt function may not be sufficiently exhibited.

The seamless belt manufacturing method of the present invention comprises:
The polyol component and the isocyanate component are reacted with each other by reacting the NCO group and the active hydrogen group at an equivalent ratio of NCO group in excess.
A prepolymer having an O group (NCO prepolymer) is prepared, and an isocyanurate bond-forming catalyst is added to the NCO prepolymer to form a belt in a mold.

The NCO index is not particularly limited as long as the necessary isocyanurate bond is formed in the molded belt, but it is preferably 1.2 to 3.0, more preferably 1.3 to 2. 5, and more preferably 1.4 to 2.0. If the NCO index is too high, the concentration of unreacted diisocyanate monomer in the NCO prepolymer becomes high, which is not preferable.

According to this production method, a polyol component,
A seamless belt containing an isocyanate component as a constituent and an isocyanurate bond as a polymer constituent bond can be easily manufactured.

The above NCO prepolymer may contain an isocyanate compound monomer.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION As the polyol component and the isocyanate component used as the constituent components of the seamless belt of the present invention, compounds known in the technical field of polyurethane are used.

Examples of the polyol compound include ether type polyol, ester type polyol, acrylic type polyol, polycarbonate type polyol, polyolefin type polyol and the like.

The polyether polyol can be obtained by adding propylene oxide to one or more polyhydric alcohols such as ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, glycerin, trimethylolpropane and pentaerythritol. Polyoxypropylene polyols, polyoxyethylene polyols obtained by adding ethylene oxide, butylene oxide, polyols obtained by adding styrene oxide, etc., and tetrahydrofuran are added to the polyhydric alcohol by ring-opening polymerization. Examples of the polyoxytetramethylene polyol (PTMG) thus obtained can be given. 2 of the above cyclic ethers
It is also possible to use a copolymer containing at least one species.

As the polyester polyol, one or more of ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, cyclohexanedimethanol, glycerin, trimethylolpropane, pentaerythritol, and other low molecular weight polyhydric alcohols are used. With glutaric acid, adipic acid, pimelic acid, speric acid, sebacic acid, terephthalic acid, isophthalic acid, dimer acid, hydrogenated dimer acid or other low molecular weight dicarboxylic acid or oligomeric acid, or two or more of them. Examples thereof include polyols such as a ring-opening polymer of a ring-opening ester such as a combination, propiolactone, caprolactone, and valerolactone.

Other than those exemplified above, polybutadiene polyol, polyisoprene polyol and the like can be used, and further, copolymers of the above exemplified polyols such as PTMG.
And a block copolymer of caprolactone can also be used.
These copolymers can be synthesized by, for example, a method of ring-opening copolymerization of ε-caprolactone with PTMG, a method of ring-opening copolymerization of tetrahydrofuran, ethylene oxide, or propylene oxide with polyester polyol.

As the polyisocyanate compound, all polyisocyanate compounds well known in the technical field of polyurethane can be used. Specifically, the following polyisocyanate compounds are exemplified.

<Aromatic diisocyanate compound> 4,
4'-diphenylmethane diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, naphthalene diisocyanate, etc. <aliphatic diisocyanate compound> -ethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 1,6-hexamethylene Aliphatic diisocyanates such as diisocyanate (HDI), hydrogenated 4,4′-diphenylmethane diisocyanate (HMDI, trade name Hiren-W, manufactured by Huls),
1,4-Cyclohexane diisocyanate (CHD
I), methylcyclohexylene diisocyanate, isophorone diisocyanate (IPDI), hydrogenated m-
Alicyclic diisocyanates such as xylylene diisocyanate (HXDI) and norbornane diisocyanate <Other diisocyanate compounds> Xylylene diisocyanate (XDI) and tetramethyl xylylene diisocyanate (TMXDI).

In addition to the above diisocyanate compound, 3
It is also possible to use a polyisocyanate mixture having a functionality or higher.
(Millionate MTL; manufactured by Nippon Polyurethane Industry Co., Ltd.), and an adduct type polyisocyanate compound such as Duranate (manufactured by Asahi Kasei).

A low molecular weight active hydrogen group-containing compound may be added to and reacted with the above-mentioned polymer constituents, if desired, and the low molecular weight polyhydric alcohols exemplified as constituents of the polyester polyol, 3,5-diethyl. -2,4-
Aromatic diamines such as toluenediamine, diaminodiphenylmethane having one or more alkyl substituents at the o-position of the amino group, and methylenebis o-chloroaniline can be used.

The isocyanurate bond-forming catalyst is a catalyst that promotes a reaction of forming an isocyanurate bond from an isocyanate group, and is also called a trimerization catalyst. As the trimerization catalyst, a catalyst for polyisocyanurate foam known in the technical field of rigid polyurethane foam can be used, and a carboxylic acid alkali metal salt catalyst,
A quaternary ammonium salt catalyst is exemplified.

As the carboxylic acid in the carboxylic acid alkali metal salt catalyst, as the carboxylic acid having 1 to 20 carbon atoms, known carboxylic acids can be used without limitation, and acetic acid, propionic acid, 2-ethylhexanoic acid (octyl) can be used. Acid), stearic acid and the like.

As the quaternary ammonium salt catalyst, N-
Examples include (2-hydroxypropyl) -N- (2-hydroxyethyl) -N, N-dimethylammonium octylate and N-hydroxyalkyl-N, N, N-trialkylammonium salts. As a commercially available product, Kaolizer 420 (manufactured by Kao) or the like can be used.

It is also a preferred embodiment that various fillers and additives are added to the seamless belt of the present invention as needed. As the filler, a filler for imparting lubricity,
There are fillers for imparting conductivity, fillers for increasing the strength, etc., and one filler may exhibit two or more effects.

As a filler for imparting lubricity,
Examples include graphite, molybdenum disulfide, polytetrafluoroethylene fine powder, and boron nitride.

The filler for imparting conductivity is as follows:
Metallic materials such as silver powder, copper powder, nickel powder, metal oxides such as tin oxide and indium oxide, inorganic materials such as mica coated with metal, graphite, carbon fibers, carbon compounds such as carbon black, and lithium perchlorate. Examples thereof include ionic additives such as ammonium thiocyanate.

Carbon black exhibits some conductivity when added to a certain extent or more, but the iodine adsorption amount (I) is 36 (mg / g) or more or the DBP oil absorption amount (d).
Is preferably 80 (ml / 100 g) or more because the electrical resistance can be lowered without adding a large amount. Specifically, EC (Extra Cond
uctive) carbon, ECF (Extra Conductive Furnanc)
e) Carbon, SCF (Super Conductive Furnance)
Carbon, CF (Conductive Furnance) carbon, acetylene black, SAF, ISAF, HAF, FE
Examples include carbon blacks such as F, GPF, SRF, FT and MT. These may be used alone or in combination of two or more.

As the filler for the purpose of resin reinforcement,
Examples thereof include silica, titanium oxide, magnesium oxide, calcium carbonate, calcium sulfate, clay, talc and the like.

In addition to the above components, it is also suitable to use an organic solvent if necessary. As such an organic solvent, N
Compounds which do not have active hydrogen groups which react with CO groups are used. Specifically, acetone, methyl ethyl ketone, ketones such as cyclohexanone, ethyl acetate, isoamyl acetate, butyl acetate, isoamyl propionate, esters such as γ-butyrolactone, ethers such as dioxane and tetrahydrofuran, toluene, xylene, etc. Suitable aromatic hydrocarbons, cellosolve alkyl esters such as ethyl cellosolve acetate, aliphatic or alicyclic hydrocarbons such as n-hexane, cyclohexane and tetralin, dimethylformamide, dimethylacetamide and N-methylpyrrolidone are suitable solvents. It is illustrated.

As a method for molding a seamless belt, an NCO is formed in the cavity of a mold composed of a middle mold and an outer mold forming a cavity having a predetermined belt size.
A method for casting a seamless belt by pouring a prepolymer, and a cylindrical die having an inner surface shape corresponding to the circumferential length of the belt is rotated around its axis while the inner surface of the die is NC.
An example is a centrifugal molding method in which an O prepolymer is poured, a film having a predetermined thickness is formed by centrifugal force, and the film is cured to form a seamless belt.

The heating during belt molding is performed at a temperature at which isocyanurate bonds are effectively formed. Specifically, it is 50 ° C. or higher, and more preferably 60 to 120 ° C.

A seamless belt having a lubricious surface layer can be obtained by forming a film of the material for forming a lubricious surface layer on the above mold, and then casting an NCO prepolymer to form a base material layer.

A seamless belt having a lubricious back surface layer can be obtained by forming a film of the material for forming a lubricious back surface layer on the inner surface of the base material layer after forming the base material layer.

The lubricious surface layer can also be formed by applying a lubricant film-forming coating material after forming the base material layer.

[Other Embodiments] The seamless belt of the present invention can be manufactured by the one-shot method. That is, a predetermined amount of a polyol compound, a polyisocyanate compound, a trimerization catalyst, and other necessary components are mixed without forming an NCO prepolymer, and the mixture is used as a belt-shaped film in a mold. A seamless belt is obtained by reacting and curing.

In the production of the seamless belt of the present invention by the above one-shot method, it is also a preferable embodiment to use a so-called resinification catalyst, which promotes the reaction between isocyanate groups and hydroxyl groups, together with a trimerization catalyst. As the resin-forming catalyst, a metal catalyst such as a tertiary amine catalyst or an organic tin catalyst known in the technical field of polyurethane can be used.

[0049]

EXAMPLES Examples and the like specifically showing the constitution and effects of the present invention will be described below. (Example) 46 g of Praxel 210 (polycaprolactone diol, molecular weight 1000, manufactured by Daicel Chemical Industries, Ltd.), Praxel 220 (polycaprolactone diol, molecular weight 2000, Daicel Chemical Industries Ltd.) in a 2 L capacity reaction vessel equipped with a stirrer and a nitrogen inlet 796 g) and 660 g of Millionate MT (diphenylmethane diisocyanate, manufactured by Nippon Polyurethane Industry Co., Ltd.) were added and reacted in a nitrogen stream at 80 ° C. for 1.5 hours to obtain a prepolymer having an NCO group. The NCO group content of this NCO prepolymer was 12%. Using the obtained NCO prepolymer as a solvent, toluene was used to prepare a solution having a concentration of 60% by weight. To 200 g of this prepolymer solution, 0.05 g of potassium acetate (0.04% by weight based on the prepolymer) was added to obtain a raw material for producing a seamless belt.

A cylindrical mold having an inner surface of 325 mm in diameter and 350 mm in width was used, and the mold was rotated at 250 RPM with the shaft center horizontal in an oven adjusted to 80 ° C. NCO that is a manufacturing raw material
The prepolymer solution was cast so that the film thickness after drying was 0.5 mm, reaction-cured and dried to obtain a seamless belt.

A sample was cut out from this belt and the JI
When the physical properties were measured by SK7127, the tensile strength was 45 MPa and the elongation was 60%. That is,
The obtained seamless belt had flexibility equivalent to that of the polyurethane elastomer, but was less likely to be stretched and deformed.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G03G 15/16 G03G 15/16 4J034 // B29K 75:00 B29K 75:00 B29L 29:00 B29L 29:00 C08L 75:04 C08L 75:04 (72) Inventor Tatsuya Sugihashi 1-17-18 Edobori, Nishi-ku, Osaka-shi, Osaka Toyo Tire & Rubber Co., Ltd. F term (reference) 2H200 FA13 GA47 HA02 JA02 JB07 JB42 JB43 JB45 JB46 JC04 JC12 JC13 JC15 JC16 LB02 LB12 LB13 LC03 LC04 LC09 MA02 MA11 MA12 MA13 MA14 MA20 MB01 MB04 3F024 AA09 BA04 CA08 3F049 AA10 BA11 LA05 LA07 LB03 4F071 AA53 AC09 AE02 AE02 AE02 AE02 AE02 AE02 AE02 HI02 AB16 A02 AB16 A02 AB16 A02 AB16 AB12 A03 AB01 AB03 A01 AB02 AB16 AB12 AB03 A02 AB16 AB12 AB03 AB01 AB03 AB01 AB03 AB01 GF03 GN01 4J034 AA01 AA02 AA06 BA03 DA01 DB03 DC50 DF11 DF12 DF14 DF15 DF16 DF21 DF22 DG01 DG02 DG03 DG04 DG05 DG06 DG16 HC11 HC12 HC13 HC54 HC61 HC64 HC67 HC71 KA01 KB03 KC02 KC07 KD02 KD12 QA03 QD03 RA11 RA12

Claims (4)

[Claims] 1. A seamless belt comprising a polyol component and an isocyanate component as constituent components and an isocyanurate bond as a polymer constituent bond. 2. A conductive filler is included, the volume resistivity has an average value in the range of 10 ⁴ to 10 ¹² Ω · cm, and the volume resistivity has a maximum value R _max and a minimum value R _min . Ratio R _max /
The seamless belt according to claim 1, wherein R _min is 10 or less. 3. The seamless belt according to claim 1, further comprising at least one lubricating surface layer. 4. A prepolymer having an NCO group (NCO prepolymer) is obtained by reacting a polyol component and an isocyanate component at an equivalent ratio of NCO groups and active hydrogen groups in excess of NCO groups, and the NCO prepolymer is an isocyanate. A method for producing a seamless belt, which comprises adding a catalyst for forming a nurate bond to form a belt in a mold.