JP2004018666A - Tubular polyimide molding and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tubular polyimide molding for use in electrophotographic equipment including laser beam printers and facsimiles, significantly improved in service life. <P>SOLUTION: The tubular polyimide molding has birefringence of 0.13-0.19. A method for producing said tubular polyimide molding is characterized by involving incorporating an aciculate filler in the resin matrix and using a chemically curing technique. With this tubular molding, the electrophotographic equipment affords extremely clear images even after driven for a long period of time, the service life of the tubular molding as an article of consumption for the equipment can be significantly improved, and the running cost of the equipment can be dramatically reduced as well. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a tubular molded article containing a polyimide resin and a method for producing the same.
[0002]
[Prior art]
Electrophotographic devices form a uniform charge on a photoconductor made of a conductive material, form an electrostatic latent image with laser light that modulates image signals, and then develop the electrostatic latent image with charged toner. To form a toner image. Next, the toner image is transferred to a recording medium such as paper directly or via an intermediate transfer member to obtain a desired image.
[0003]
Here, an electrophotographic apparatus employing an intermediate transfer method, in which a toner image on a photoreceptor is primarily transferred to an intermediate transfer body and then a secondary transfer of the toner image on the intermediate transfer body to a recording medium such as paper. The intermediate transfer material to be used is, for example, polyvinylidene fluoride (JP-A-5-200904), polycarbonate (JP-A-6-228335), or a blend of an ethylene-tetrafluoroethylene copolymer and polycarbonate (JP-A-6-1990). JP-A-149083) discloses a conductive resin tubular body in which a conductive agent such as carbon black is dispersed in a thermoplastic resin.
[0004]
However, the intermediate transfer material has a problem in that cracks are generated due to insufficient mechanical properties such as strength and friction and abrasion resistance, and a good transferred image cannot be obtained due to deformation due to the load of the intermediate transfer member during driving.
[0005]
In order to solve this problem, it has been proposed to use a polyimide resin as the material of the intermediate transfer member, and particularly to use a tubular molded body thereof. Nevertheless, in recent years, with the speeding up of the electrophotographic apparatus, the load applied when driving the intermediate transfer member tends to increase. Therefore, even when a polyimide resin is used, deformation during driving of the intermediate transfer member is inevitable, and is particularly remarkable in driving for a long time. Due to the above factors, there has been a problem that a satisfactory image cannot be obtained even when an intermediate transfer body made of a polyimide resin is used.
[0006]
[Problems to be solved by the invention]
The present invention, for example, when used as an intermediate transfer material for an electrophotographic apparatus, can provide a good image even after long-time driving, and has a dramatically improved life, and a polyimide tubular molded article having a significantly improved life and a method for producing the same. The purpose is to provide.
[0007]
[Means for Solving the Problems]
The present inventors have conducted intensive studies to solve the above problems, and as a result, in the polyimide tubular molded body, the polyimide molecular chain was oriented and controlled in the plane direction, in other words, the polyimide in which the birefringence was controlled in a certain range By using the tubular molded body, it was found that when used as an intermediate transfer body material, the deformation was extremely small even when driven for a long time, and the present invention was completed. The degree of orientation in the plane direction can be evaluated alternately by birefringence.
[0008]
That is, the first aspect of the present invention relates to a polyimide tubular molded body, which has a birefringence of 0.13 or more and 0.19 or less.
[0009]
In a preferred embodiment, the polyimide resin constituting the polyimide tubular molded body has a residue derived from biphenyltetracarboxylic dianhydride, and the content of the residue is a total acid dianhydride residue. The present invention relates to the above-mentioned polyimide tubular molded body, which is 50 mol% or more as a standard.
[0010]
In a further preferred embodiment, the polyimide resin constituting the polyimide tubular molded body has a residue derived from phenylenediamines, and the content of the residue is 50 mol% or more based on all diamine residues. The present invention relates to the polyimide tubular molded article according to any one of the above.
[0011]
A further preferred embodiment relates to the polyimide tubular molded body according to any one of the above, wherein the polyimide tubular molded body contains 20 to 100 parts by weight of a needle filler with respect to 100 parts by weight of a polyimide resin. .
[0012]
A second aspect of the present invention is a polyamic acid obtained by reacting an acid dianhydride component containing 50 mol% or more of diphenyltetracarboxylic dianhydride with a diamine component containing 50 mol% or more of phenylenediamines. The present invention relates to a method for producing a polyimide tubular molded body, which comprises subjecting an acid to ring-closing imidization by a chemical curing method.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, embodiments of the polyimide tubular molded article and the method for producing the same according to the present invention will be described in more detail.
[0014]
In the polyimide tubular molded article according to the present invention, it is important that the main component of the resin is polyimide. Here, the main component of the resin means that the polyimide is 50% by weight or more of all the resin components, and more preferably 70% by weight or more. Polyimide is obtained by a curing reaction of polyamic acid, and polyamic acid is obtained by polymerizing an acid dianhydride component, preferably an aromatic tetracarboxylic dianhydride component and a diamine component in an organic polar solvent. It is obtained.
[0015]
There is no particular limitation on the tetracarboxylic dianhydride component. For example, butanetetracarboxylic dianhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,3-dimethyl-1,2,2 3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3,4-cyclopentanetetracarboxylic dianhydride, 2,3,5-tricarboxycyclopentylacetic dianhydride, 3,5,6-tri Carboxynorbonane-2-acetic acid dianhydride, 2,3,4,5-tetrahydrofurantetracarboxylic dianhydride, 5- (2,5-dioxotetrahydrofural) -3-methyl-3-cyclohexene-1, Aliphatic or cycloaliphatic tetracarboxy such as 2-dicarboxylic dianhydride, bicyclo [2,2,2] -oct-7-ene-2,3,5,6-tetracarboxylic dianhydride Acid dianhydride; pyromellitic dianhydride, 3,3 ', 4,4'-benzophenonetetracarboxylic dianhydride, 3,3', 4,4'-biphenylsulfonetetracarboxylic dianhydride, 2,4,5,8-naphthalenetetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 3,3 ', 4,4'-biphenylethertetracarboxylic dianhydride, 3,3 ', 4,4'-dimethyldiphenylsilanetetracarboxylic dianhydride, 3,3', 4,4'-tetraphenylsilanetetracarboxylic dianhydride, 1,2,3,4-furantetra Carboxylic acid dianhydride, 4,4'-bis (3,4-dicarboxyphenoxy) diphenyl sulfide dianhydride, 4,4'-bis (3,4-dicarboxyphenoxy) diphenyl sulfone dianhydride 4,4'-bis (3,4-dicarboxyphenoxy) diphenylpropane dianhydride, 3,3 ', 4,4'-perfluoroisopropylidene diphthalic dianhydride, 2,3,3', 4 '-Biphenyltetracarboxylic dianhydride, 3,3', 4,4'-biphenyltetracarboxylic dianhydride, bis (phthalic acid) phenylphosphine oxide dianhydride, p-phenylene-bis (triphenylphthalic acid ) Dianhydride, m-phenylene-bis (triphenylphthalic acid) dianhydride, bis (triphenylphthalic acid) -4,4'-diphenyl ether dianhydride, bis (triphenylphthalic acid) -4,4 ' -Aromatic tetracarboxylic dianhydride such as diphenylmethane dianhydride; 1,3,3a, 4,5,9b-hexahydro-2,5-dioxo-3-furanyl) -naph [1,2-c] furan-1,3-dione, 1,3,3a, 4,5,9b-hexahydro-5-methyl-5- (tetrahydro-2,5-dioxo-3-furanyl)- Naphtho [1,2-c] furan-1,3-dione, 1,3,3a, 4,5,9b-hexahydro-8-methyl-5- (tetrahydro-2,5-dioxo-3-furanyl)- Examples thereof include aliphatic tetracarboxylic dianhydrides having an aromatic ring such as naphtho [1,2-c] furan-1,3-dione. These tetracarboxylic dianhydrides can be used alone or in combination of two or more. When used alone, biphenyltetracarboxylic dianhydrides are preferred because heat resistance, mechanical properties and birefringence are easily controlled within a predetermined range. Even when used in combination of two or more, all acid dianhydrides are preferred. It is preferable to use 50 mol% or more of biphenyltetracarboxylic dianhydride based on the components. The acid dianhydride component and the diamine component are converted into residues derived from each component in the course of the polymerization reaction and the curing reaction, and these residues determine various properties of the polyimide. By using the biphenyltetracarboxylic acid dianhydride in an amount of 50 mol% or more based on the total acid dianhydride component, the residue derived from the biphenyltetracarboxylic acid dianhydride in the finally obtained polyimide Is preferably 50 mol% or more based on the total acid dianhydride residues, so that heat resistance, mechanical properties, and birefringence can be easily controlled within predetermined ranges. The biphenyltetracarboxylic dianhydride is particularly preferably 2,3,3 ', 4'-biphenyltetracarboxylic dianhydride or 3,3', 4,4'-biphenyltetracarboxylic dianhydride. .
[0016]
The diamine component to be used next is not particularly limited as long as it is a diamine. For example, p-phenylenediamine, m-phenylenediamine, 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenylethane, 4,4 ′ -Diaminodiphenyl ether, 4,4'-diaminodiphenylsulfide, 4,4'-diaminodiphenylsulfone, 1,5-diaminonaphthalene, 3,3-dimethyl-4,4'-diaminobiphenyl, 5-amino-1- ( 4'-aminophenyl) -1,3,3-trimethylindane, 6-amino-1- (4'-aminophenyl) -1,3,3-trimethylindane, 4,4'-diaminobenzanilide, 3, 5-diamino-3'-trifluoromethylbenzanilide, 3,5-diamino-4'-trifluoromethyl Rubenzanilide, 3,4'-diaminodiphenyl ether, 2,7-diaminofluorene, 2,2-bis (4-aminophenyl) hexafluoropropane, 4,4'-methylene-bis (2-chloroaniline), , 2 ', 5,5'-Tetrachloro-4,4'-diaminobiphenyl, 2,2'-dichloro-4,4'-diamino-5,5'-dimethoxybiphenyl, 3,3'-dimethoxy-4 4,4'-diaminobiphenyl, 4,4'-diamino-2,2'-bis (trifluoromethyl) biphenyl, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis [4- (4-aminophenoxy) phenyl] hexafluoropropane, 1,4-bis (4-aminophenoxy) benzene, 4,4'-bis (4-aminophenoxy) ) -Biphenyl, 1,3'-bis (4-aminophenoxy) benzene, 9,9-bis (4-aminophenyl) fluorene, 4,4 '-(p-phenyleneisopropylidene) bisaniline, 4,4'- (M-phenyleneisopropylidene) bisaniline, 2,2'-bis [4- (4-amino-2-trifluoromethylphenoxy) phenyl] hexafluoropropane, 4,4'-bis [4- (4-amino- Aromatic diamines such as 2-trifluoromethyl) phenoxy] -octafluorobiphenyl; aromatics having two amino groups bonded to an aromatic ring such as diaminotetraphenylthiophene and a hetero atom other than a nitrogen atom of the amino group Diamine; 1,1-methaxylylenediamine, 1,3-propanediamine, tetramethylenediamine, pentame Tylenediamine, octamethylenediamine, nonamethylenediamine, 4,4-diaminoheptamethylenediamine, 1,4-diaminocyclohexane, isophoronediamine, tetrahydrodicyclopentadienylenediamine, hexahydro-4,7-methanoindanylenediamine Methylenediamine, tricyclo [6,2,1,0 ^2.7 ] -Undecylenedimethyldiamine, aliphatic diamines such as 4,4'-methylenebis (cyclohexylamine) and alicyclic diamines. These diamine compounds can be used alone or in combination of two or more. When used alone, phenylenediamines are preferred because heat resistance, mechanical properties, and birefringence are easily controlled within predetermined ranges. Even when two or more phenylenediamines are used in combination, 50 mol% based on the total diamine component is used. It is preferable to use the above phenylenediamines. By using the phenylenediamines in an amount of 50 mol% or more based on the total diamine components, the content of the residues derived from the phenylenediamines in the finally obtained polyimide is reduced by the total diamine residues. Since the content is 50 mol% or more as a reference, heat resistance, mechanical properties, and birefringence are easily controlled within a predetermined range, which is preferable. The phenylenediamines are particularly preferably p-phenylenediamine or m-phenylenediamine.
[0017]
Here, as the organic polar solvent used in the reaction for forming the polyamic acid, for example, sulfoxide solvents such as dimethyl sulfoxide and diethyl sulfoxide, formamide solvents such as N, N-dimethylformamide and N, N-diethylformamide, Acetamide solvents such as N, N-dimethylacetamide, N, N-diethylacetamide, pyrrolidone solvents such as N-methyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, phenol, o-, m- or p -Phenolic solvents such as cresol, xylenol, halogenated phenol, catechol, etc .; ether solvents such as tetrahydrofuran, dioxane, dioxolane, alcoholic solvents such as methanol, ethanol, butanol, cellosolves such as butyl cellosolve, etc. Sa-methyl phosphoramide, .gamma.-butyrolactone, etc. can be mentioned, although it is desirable to use them alone or as a mixture, further xylene, aromatic hydrocarbons such as toluene can be used. The solvent is not particularly limited as long as it dissolves the polyamic acid. In addition, water must be removed as much as possible to promote the decomposition of the polyamic acid.
[0018]
When a polyimide tubular molded body is used as an intermediate transfer body material, it is preferable that the polyimide molecular chains are oriented in the plane direction in order to reduce deformation during long-time driving. More preferably, the polyimide molecular chains are oriented in the horizontal direction with the tension applied to the body. The birefringence is closely related to the orientation state of the polyimide molecular chains, and a large birefringence means that the degree of the plane orientation of the polyimide molecular chains is high. Therefore, as the birefringence is larger, a polyimide tubular molded body that undergoes less deformation during long-time driving can be obtained.
[0019]
However, when the degree of plane orientation, that is, the birefringence is too large, the polyimide tubular molded body may be peeled off or the tear propagation strength may be significantly reduced.
[0020]
On the other hand, if the birefringence of the polyimide tubular molded body is controlled in the range of 0.13 or more and 0.19 or less, the above-mentioned problem is solved, and even when the intermediate transfer material is driven for a long time, the stability is excellent. Images can be provided. Further, when the birefringence is 0.14 or more and 0.18 or less, more preferable results are obtained. As described above, when the birefringence of the polyimide tubular molded product is smaller than 0.13, deformation due to long-time driving may occur. Conversely, when the birefringence exceeds 0.19, the toughness of the polyimide tubular molded product is reduced. Is unpreferable because the value may significantly decrease.
[0021]
The birefringence according to the present invention can be easily obtained by measuring the refractive index in the plane direction and the thickness direction using, for example, an Abbe birefringence meter and a light source having a wavelength of 589 nm, and inserting the refractive index into the following equation. .
[0022]
Birefringence (Δn) = refractive index in plane direction−refractive index in thickness direction
Here, the refractive index in the plane direction is an average value of the refractive index in the circumferential direction of the polyimide tubular molded body and the refractive index in the direction orthogonal to the circumferential direction.
[0023]
A method for controlling birefringence will be described below.
[0024]
As a method of increasing the birefringence, for example, a method using a raw material having no bending group as an acid dianhydride component or a diamine component, ring closure while applying tension to a semi-imidized / semi-dried state tubular material Representative examples include a method of performing imidation and a method of employing a chemical curing method described later in the case of ring-closing imidization. In addition, according to the study of the present inventors, it seems that the blending of the filler with the polyimide resin also affects the birefringence.
[0025]
Among these methods, there are cases where the selection of raw materials is restricted in terms of the properties and production cost of the tubular molded product, and the tension during ring-closing imidization is limited in terms of the size and shape of the tubular molded product to be produced. In this case, the chemical curing method can be an effective means of controlling birefringence.
[0026]
The chemical curing method is a method using a catalyst and a curing agent as a means for curing a polyamic acid. The method of introducing the catalyst and the curing agent into the raw material solution containing the polyamic acid is not particularly limited, and the method of kneading the catalyst and the curing agent in the raw material solution, the method of kneading only the catalyst in the raw material solution, the curing agent or Examples thereof include a method of contacting a solution containing a curing agent with a raw material solution by a method such as spraying, coating, and dipping, and a method of bringing a solution containing a catalyst and a curing agent into contact with the raw material solution.
[0027]
The curing agent used herein can be used without limitation as long as it is a dehydration ring-closing agent for polyamic acid. For example, aliphatic acid anhydride, aromatic acid anhydride, N, N'-dialkylcarbodiimide can be used as the main components. , Lower aliphatic halides, halogenated lower aliphatic acid anhydrides, arylsulfonic acid dihalides, thionyl halides, or mixtures of two or more thereof can be preferably used. Among them, aliphatic acid anhydrides and aromatic acid anhydrides work well.
[0028]
The catalyst referred to here can be used without limitation as long as it is a component having an effect of accelerating the dehydration and ring closure of the curing agent with respect to polyamic acid. Examples thereof include an aliphatic tertiary amine, an aromatic tertiary amine, and a complex tertiary amine. Cyclic tertiary amines can be used. Among them, a substituted or unsubstituted nitrogen-containing heterocyclic compound such as imidazole, benzimidazole, isoquinoline, quinoline, or substituted pyridine such as β-picoline is preferable.
[0029]
Furthermore, introduction of an organic polar solvent into the solution containing the curing agent and the catalyst may be appropriately selected.
[0030]
Next, a case where a needle filler is mixed with the polyimide resin will be described.
[0031]
By mixing an appropriate amount of the acicular filler into the polyimide tubular molded body, when the polyimide tubular molded body is used as an intermediate transfer member material, the degree of deformation when driven for a long time can be reduced. Further, by using the conductive acicular filler, the resistance value of the polyimide tubular molded article can be controlled to a value suitable for the intermediate transfer material.
[0032]
The needle-like filler according to the present invention is a rod-like material having an aspect ratio of 10 or more and having a major axis of 0.5 to 30 μm. It is preferable because the effect of controlling to a suitable range is high. Further, a part of the structure may include an acicular filler. Therefore, a filler having a rod-like shape having an aspect ratio of 10 or more may have a structure in which needle-like fillers are randomly aggregated, or a filler having a tetrapod structure, a sword mountain structure, or the like.
[0033]
The shape of the needle filler according to the present invention is extremely important, and the material is not particularly limited. Accordingly, any conventionally known materials such as titanium oxide, tin oxide doped with antimony, and glass can be used. Furthermore, those having a surface coated with a conductive metal or carbon, those having been subjected to a coupling treatment, and the like can also be used favorably. Among them, tin oxide in which at least the outermost surface is doped with titanium oxide or antimony can be preferably used because the resulting polyimide tubular molded article can have a favorable resistance value.
[0034]
Further, the introduction of the acicular filler is preferably 20 to 100 parts by weight, more preferably 25 to 70 parts by weight, based on 100 parts by weight of the dry weight of the polyimide resin. When the introduction amount of the acicular filler is less than 20 parts by weight, the resistance cannot be sufficiently reduced when the polyimide tubular molded article of the present invention is used for electrophotography. On the other hand, if the amount is more than 100 parts by weight, the toughness of the obtained polyimide tubular molded article may be significantly reduced.
[0035]
Polyimide tubular molded article according to the present invention, including the polyimide resin, other components are not particularly limited, in order to control the properties of the finally obtained polyimide tubular molded article, regardless of organic or inorganic materials, Various materials can be introduced. For example, for the purpose of controlling the resistance value, a method of mixing an appropriate amount of conductive inorganic powder such as carbon black into a resin is most effective. In addition to carbon black, small-diameter metal particles, metal oxide particles, titanium oxide, various inorganic particles and whiskers formed with a film of a conductive material such as a metal oxide can provide the same effect. . Further, an ion conductive substance such as LiCl can be added. For the purpose of controlling the thermal conductivity, for example, aluminum nitride, boron nitride, alumina, silicon carbide, silicon, silica, graphite, or the like can be used. Among them, boron nitride is particularly preferable in that it has a high heat conduction function, exhibits a releasing effect, is chemically stable, and is harmless.
[0036]
The volume resistivity of the polyimide tubular molded article according to the present invention is 10 ⁷ -10 ¹¹ It is preferably Ω · cm. When the polyimide tubular molded article is used as an intermediate transfer member of a laser beam printer, if the volume resistivity is too small, white spots occur, and if it is too large, transfer dust occurs, which is not preferable.
[0037]
In addition, the polyimide tubular molded article according to the present invention means a hollow molded article, regardless of its diameter or thickness. Therefore, the present invention can be applied to a large-diameter one often called a belt and a small-diameter one often called a tube. Moreover, even if it is a seamless molded body, it can be applied to a hollow molded body formed by joining films by means of overlapping or butting. However, when the polyimide tubular molded article of the present invention is used, for example, as an intermediate transfer belt of an electrophotographic apparatus, even a minute step may lead to deterioration of image quality. Seamless molded articles are preferred over tubular molded articles joined together.
[0038]
In this polyimide tubular molded body, it is also possible to appropriately select to laminate a layer having other components on the outer layer. Examples of the outer layer include poly (tetrafluoroethylene) and poly (vinylidene fluoride), but are not limited thereto.
[0039]
Next, a specific method for producing a polyimide tubular molded body will be described with reference to an example.
[0040]
A tetracarboxylic dianhydride component and a diamine component are polymerized in an organic solvent to prepare a polyimide resin precursor acid solution, that is, a polyamic acid solution. In this case, the polyamic acid obtained by reacting an acid dianhydride component containing 50 mol% or more of diphenyltetracarboxylic dianhydride with a diamine component containing 50 mol% or more of phenylenediamines for the reason described above. Is preferred.
[0041]
At this time, it is also possible to appropriately select an appropriate amount of an inorganic powder such as a needle filler or carbon black mixed in the solution. As a method of mixing additives such as needle-like fillers and inorganic powders, a method of mixing additives in an organic solvent, and then polymerizing the above components in the organic solvent, a step in the middle of the polymerization reaction or termination of the reaction There is a method in which an additive or a dispersion thereof is mixed into the subsequent solution. Techniques for dispersing needle-like fillers and inorganic powders and reducing the size of the aggregates include physical methods such as stirring with a mixer or stirrer, parallel rolls, ultrasonic dispersion, ball mills, and the introduction of dispersants. However, the present invention is not limited thereto.
[0042]
The catalyst and the curing agent described above are kneaded into the raw material of the polyimide tubular molded body obtained in this way, but the means is not particularly limited. Furthermore, after kneading only the catalyst in the raw material and forming it into a cylindrical or film shape, and then contacting a solution containing a curing agent, after forming the raw material into a cylindrical or film shape, a solution containing the catalyst and the curing agent is added. The contact method may be used.
[0043]
The raw material of the polyimide tubular molded body obtained by the above-mentioned means is molded into a tubular or film shape. There is no particular limitation on the method of molding the polyimide tubular molded material into its shape, a method of extruding the polyimide tubular molded material from a die, a method of immersing the mold in the polyimide tubular molded material, and a method of molding the polyimide tubular molded material in the mold. Is sprayed. Further, in the case of a cylindrical shape, a so-called centrifugal molding method of applying a centrifugal force to make the thickness of the cylindrical coating film constant can be used. In this step, heating the polyimide tubular molded body material at about 100 ° C., substantially at a temperature of 70 ° C. to 140 ° C., to promote the curing reaction may be appropriately selected.
[0044]
The coating film, which has developed into a semi-cured state due to its self-supporting property through the above-described process, is further heated to remove the solvent and almost completely terminate the curing reaction. In the heating step, in order to prevent thickness unevenness and molding failure due to shrinkage of the resin, when molded into a cylinder, it is preferable to insert a cylindrical or cylindrical mold inside the cylindrical coating film, and a film When it is formed into a shape, it is preferable to heat it while applying a certain tension in the plane direction. When it is formed into a film, it is slit into an appropriate size, and the end is processed into a cylindrical shape by overlapping or butting.
[0045]
Thus, the desired polyimide tubular molded body can be obtained.
[0046]
【Example】
An embodiment according to the present invention will be described below.
[0047]
(Example 1)
1500 g of dimethylformamide (DMF) sufficiently dehydrated with a molecular sieve was put into a vessel equipped with a stirring blade, 108 g of p-phenylenediamine was added, and the mixture was stirred until it was completely dissolved. The system was cooled to about 0 ° C., and 294 g of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride was gradually added, followed by thorough stirring. The viscosity of the system is about 3 × 10 ² When Pa · s was reached, the stirring was stopped to obtain a polyimide precursor solution.
[0048]
Next, 60 g of the metal filler FT-1000 manufactured by Ishihara Sangyo Co., Ltd. and 300 g of DMF were placed in another container, stirred well, and further applied to an ultrasonic disperser to uniformly disperse the metal filler in the dispersion. FT-1000 is an acicular filler made of titanium oxide coated on its surface with tin oxide doped with antimony, and has an average major axis length of about 1.68 μm.
[0049]
196 g of the needle-like filler dispersion liquid obtained above was collected and stirred well. In this beaker, 300 g of the polyimide precursor solution obtained above was dissolved and stirred well. In this way, a raw material of a polyimide tubular molded body containing about 50 parts by weight of the needle-shaped metal filler based on 100 parts by weight of the cured polyimide dry weight was prepared.
[0050]
20 g of isoquinoline as a catalyst and 32 g of acetic anhydride as a curing agent were kneaded in the raw material of the polyimide tubular molding.
[0051]
The polyimide tubular molded body material obtained above is uniformly cast and applied to the inner wall of a glass tube having an inner diameter of 82 mm and a length of 450 mm so that the thickness after firing becomes 60 μm, and the coating film exhibits self-supporting properties. Until 23 ° C. and 55% RH for 10 minutes. Next, the coating film was removed from the glass tube, mounted on a SUS mold having an outer diameter of 80 mmφ, and heated from 100 ° C. to 380 ° C. over about 30 minutes. Finally, the system was cooled to room temperature to obtain the desired polyimide tubular molded body.
[0052]
Image evaluation, birefringence measurement, and volume resistivity measurement when the polyimide tubular molded body obtained by the above-described means was used as an intermediate transfer belt were performed.
[0053]
Image evaluation when used as an intermediate transfer belt was performed according to the following procedure. The obtained polyimide tubular molded body was mounted on a pre-tail of a full-color copying machine manufactured by Ricoh Co., Ltd. as a copying machine and used as an intermediate transfer belt to form 10,000 A4 size images. Thereafter, one more image was formed, and the image was evaluated.
[0054]
A process until a color image is completed in the copying machine will be briefly described. After the electrostatic latent image is formed on the photoconductor, development of each color (cyan, magenta, yellow, black) is repeated by the developing unit, and each color image (toner image) is sequentially formed on the photoconductor. Each color toner image is sequentially transferred to the same position on the intermediate transfer belt for each single color. This transfer is caused by a predetermined bias voltage applied to the transfer bias roller. After the image is transferred onto the intermediate transfer belt, it is collectively transferred onto a transfer material such as paper by a paper transfer bias roller. After the transfer is completed, the transfer material is sent to a fixing device, where the toner image is fixed, and appears as a full-color image.
[0055]
The volume resistivity measurement was performed according to the following procedure. 10 film-like polyimide tubular moldings ² cm ² The test pieces were divided into nine test pieces and allowed to stand in an atmosphere of 23 ° C. and 55% RH for 24 hours or more. Thereafter, the volume resistivity was measured for each of the nine test pieces under the same atmosphere using a high resistance measurement device R8340 manufactured by Advantest equipped with a resistance chamber R12702A. The voltage used for the measurement was 500 V.
[0056]
Further, the birefringence of the polyimide tubular molded body obtained by the above-described means was measured in the plane direction using an Atago 4T type Abbe birefringence meter and a light source having a wavelength of 589 nm under an atmosphere of 23 ° C. and 55% RH. And the refractive index in the thickness direction were measured, and the refractive index was determined by inserting the refractive index into the following equation.
[0057]
Birefringence (Δn) = refractive index in plane direction−refractive index in thickness direction
Here, the refractive index in the plane direction is an average value of the refractive index in the circumferential direction of the polyimide tubular molded body and the refractive index in the direction orthogonal to the circumferential direction.
[0058]
As a result, a good image could be formed on the image obtained by using the polyimide tubular molded body, without any transfer deviation, unevenness, and insect-eating image. Further, the volume resistance value of the polyimide tubular molded product is (3.2 ± 0.1) × 10 ⁹ Ω · cm and birefringence Δn were 0.16.
[0059]
(Example 2)
A polyimide tubular molded body was prepared in the same manner as in Example 1, except that the raw material of the polyimide tubular molded body was formed into a film shape and then formed into a tubular molded body by end joining.
[0060]
The formation into a film was performed by the following procedure. A polyimide tubular molded material obtained by kneading isoquinoline and acetic anhydride according to the method of Example 1 was fired to have a film thickness of 60 μm and a film area of 30 × 30 cm after firing. ² The coating was uniformly applied on an aluminum foil using a bar coater, and allowed to stand in an atmosphere at 23 ° C. for 10 minutes until the coating film exhibited self-supporting properties. Next, the temperature was raised from 100 ° C. to 380 ° C. over about 30 minutes. Thereafter, the aluminum foil was removed by etching with a mixed acid solution of ferric chloride / hydrochloric acid. The end portion of the film was overlapped by 5 mm, and the overlapped portion was bonded with a silicone-based adhesive to obtain an intended polyimide tubular molded body.
[0061]
As a result of evaluation by the same procedure as that of Example 1, an image obtained by using the polyimide tubular molded body was free from transfer misalignment, shading, and bug-eating images, and a good image was formed. Further, the volume resistance value of the polyimide tubular molded body is (2.8 ± 0.1) × 10 ⁹ Ω · cm and birefringence Δn were 0.15.
[0062]
(Comparative Example 1)
A polyimide tubular molded body was prepared in the same manner as in Example 1, except that a metal filler ET-300W manufactured by Ishihara Sangyo Co., Ltd. was used instead of the needle filler. ET-300W is a spherical filler made of titanium oxide coated on its surface with tin oxide doped with antimony, and has a diameter of about 0.03 to 0.06 μm.
[0063]
As a result of evaluation by the same procedure as in Example 1, the polyimide tubular molded body was broken after outputting about 7000 images. Further, the volume resistance value of the polyimide tubular molded product is (3.6 ± 7.2) × 10 ¹³ Ω · cm and birefringence Δn were 0.20.
[0064]
(Comparative Example 2)
A polyimide tubular molded body was prepared in the same manner as in Example 1, except that a metal filler TM-200 manufactured by Otsuka Chemical Co., Ltd. was used instead of the needle-shaped filler. TM-200 is a plate-like filler composed of mica whose surface is coated with antimony-doped tin oxide, and has an average width of about 10 μm and an average thickness of 0.1 μm.
[0065]
As a result of evaluation by the same procedure as in Example 1, cracks occurred at the end of the polyimide tubular molded body, and linear insect biting occurred. The volume resistance value of the polyimide tubular molded product is (5.4 ± 0.8) × 10 ¹⁶ Ω · cm and birefringence Δn were 0.20.
[0066]
(Comparative Example 3)
Except for not containing a catalyst and a curing agent, the same raw material solution as in Example 1 was uniformly cast and applied to the inner wall of a glass tube having an inner diameter of 82 mmφ and a length of 450 mm so that the thickness after firing was 60 μm, The solvent was volatilized by exposing to hot air of 100 ° C. for 40 minutes. Next, the coating film was removed from the glass tube, mounted on a SUS mold having an outer diameter of 80 mmφ, and heated from 100 ° C. to 380 ° C. over about 30 minutes. Finally, the system was cooled to room temperature to obtain the desired polyimide tubular molded body.
[0067]
As a result of evaluation by the same procedure as in Example 1, transfer misregistration occurred in an image obtained using the polyimide tubular molded body. The volume resistance value of the polyimide tubular molded body is (1.8 ± 3.2) × 10 ⁹ Ω · cm and birefringence Δn were 0.12.
[0068]
As described above, the polyimide tubular molded body according to the present invention and the method for producing the same have been described, but the present invention is not limited to the above-described embodiment. Needless to say, the present invention can be implemented in various modified forms within the described range.
[0069]
【The invention's effect】
When the polyimide tubular molded article according to the present invention is used as a material for an intermediate transfer member of an electrophotographic apparatus, an extremely good image can be provided even after driving for a long time. Therefore, the life of the polyimide tubular molded article, which is a consumable for the electrophotographic apparatus, is dramatically improved, and the running cost of the electrophotographic apparatus can be dramatically reduced.
[0070]
As described above, the effects exhibited by the present invention, such as all the problems existing in the prior art are solved, are remarkably large.

Claims (5)

A polyimide tubular molded article having a birefringence in the range of 0.13 or more and 0.19 or less. The polyimide resin constituting the polyimide tubular molded body has a residue derived from biphenyltetracarboxylic dianhydride, and the content of the residue is 50 mol% based on the total acid dianhydride residue. The polyimide tubular molded article according to claim 1, wherein: The polyimide resin constituting the polyimide tubular molded article has a residue derived from phenylenediamines, and the content of the residue is 50 mol% or more based on all diamine residues. The polyimide tubular molded article according to claim 1 or 2, wherein 4. The polyimide tubular molded product according to claim 1, wherein the polyimide tubular molded product contains 20 to 100 parts by weight of an acicular filler with respect to 100 parts by weight of the polyimide resin. 5. A polyamic acid obtained by reacting an acid dianhydride component containing not less than 50 mol% of biphenyltetracarboxylic dianhydride with a diamine component containing not less than 50 mol% of phenylenediamine is subjected to a ring-closing imide by a chemical curing method. A method for producing a polyimide tubular molded article, comprising: