JP4356508B2 - Polyamic acid composition, image forming apparatus, polyimide endless belt using the same, and method for producing the same - Google Patents

Description

  The present invention relates to a polyamic acid composition that is a raw material for a polyimide material used in electrical and electronic equipment. In particular, for example, the present invention relates to a polyamic acid composition as a raw material for a polyimide endless belt used in electrophotographic apparatuses such as photographic copying machines, laser beam printers, facsimiles, and composite apparatuses thereof, and a polyimide endless belt using the same.

  2. Description of the Related Art Conventionally, an electrophotographic apparatus forms a charge uniformly on a photosensitive material made of a conductive material, forms an electrostatic latent image using a laser beam or the like on a modulated image signal, and then charges the electrostatic latent image with charged toner. To develop 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 an image.

  Here, a method of primary transfer of a toner image on a photosensitive member to an intermediate transfer member and then secondary transfer of the toner image on the intermediate transfer member to a recording medium such as paper, an image forming apparatus adopting a so-called intermediate transfer method. The intermediate transfer belt used is, for example, polyvinylidene fluoride (for example, see Patent Document 1), polycarbonate (for example, see Patent Document 2), a blend of an ethylene-tetrafluoroethylene copolymer and polycarbonate (for example, Patent Document). A conductive endless belt in which a conductive agent such as carbon black is dispersed in a thermoplastic resin such as 3) has been proposed.

  Furthermore, in recent years, a method for fixing a toner image on a recording medium by heating the intermediate transfer member, that is, an intermediate transfer and fixing method has been disclosed (for example, see Patent Document 4).

  In the intermediate transfer / fixing method, after the toner image is secondarily transferred to the recording medium via the intermediate transfer member, the intermediate transfer member is directly or indirectly heated to contact the intermediate transfer member. This is a method for fixing a toner image on a recording medium, and has an advantage that the apparatus can be reduced in size and cost compared with a conventional apparatus in which the intermediate transfer mechanism and the fixing mechanism are separated.

  Here, the belt material used in the intermediate transfer and fixing method is required to have a mechanical strength that can withstand the stress during driving and at the same time be able to withstand the heat of about 200 ° C. that is applied during fixing. From this demand, a polyimide resin having both high mechanical strength and heat resistance is suitable for the material used for the intermediate transfer and the fixing belt.

  Thus, conventionally, polyimide resins have been widely used as electrical equipment materials, not limited to electrophotographic devices, because of their excellent properties such as high mechanical strength and heat resistance.

  However, since polyimide resins are generally insoluble in solvents and do not melt even when heated, the precursor polyamic acid solution is applied onto a substrate, dried and baked, and then subjected to a dehydration ring closure reaction. Manufactures resin molded products.

  Polyimide firing is often performed at 300 ° C. or higher, which is a big problem in terms of energy consumption and environmental impact. In addition, due to the dehydration of the polyamic acid, the film surface and the voids in the film are generated, the film thickness is not uniform due to the stress generated by the volume shrinkage accompanying the dehydration ring-opening reaction, and the resistance value varies. There is a big problem in terms of the quality of molded products.

For these problems, application of a soluble polyimide material has been studied (for example, see Patent Document 6 ). The soluble polyimide material is obtained by dissolving a polyimide resin that has been previously imidized in a solvent, and a polyimide molded product can be produced simply by drying the solvent after being applied to a substrate. Since the solvent can be dried at a lower temperature than the firing step shown above, energy consumption and generation of voids can be suppressed compared to the step of performing a thermal imidization reaction of polyamic acid. Are better.

  However, the soluble polyimide material contains a side chain substituent group composed of a bent structure or a large molecular structure in order to ensure solubility in a solvent, and therefore has a polyimide resin obtained by baking polyamic acid. High mechanical properties and heat resistance cannot be achieved. For example, when used as a belt, the strength is generally small, and elongation and fracture are likely to occur.

  Moreover, in order to promote imidation of polyamic acid at the time of baking, the method of heating by coexisting tertiary amine etc. is disclosed by patent documents 7-10 etc., but the imidization promotion effect by addition of such tertiary amines is disclosed. Is small and difficult to put into practical use.

An example in which the composition of the polyamic acid and the solvent is a mixture of N-methyl-2-pyrrolidone and γ-butyrolactone is disclosed in Patent Document 11, but the invention is The purpose of the present invention is to improve the printing performance of the liquid crystal aligning agent, which is essentially different from the invention according to the present application for the purpose of promoting the imidization reaction, the industrial application field, and the purpose of the invention. is there. That is, the liquid crystal aligning agent is formed with a polyamic acid composition according to the present invention, whereas the liquid crystal aligning agent is formed on a substrate such as glass with a thickness of 1000 μm or less and does not require the self-supporting property developed by the progress of imidization reaction Since the polyimide molded product is intended to be used as a thick film such as a belt base material, self-supporting property due to the progress of the imidization reaction is indispensable.
Japanese Patent Laid-Open No. 5-200904 JP-A-6-228335 Japanese Patent Laid-Open No. 6-149083 JP-A-6-258960 Japanese Patent Laid-Open No. 10-45910 Japanese Patent Laid-Open No. 6-207014 JP 2002-127165 A JP 2002-283366 A JP 2002-296919 A JP-A-6-138463

An object of the present invention is to solve the conventional problems and achieve the following objects. That is, an object of the present invention is to provide a polyamic acid composition which can obtain a high imidization reaction rate even at a low baking treatment temperature and a short baking treatment time, and can reduce the baking temperature and the baking time.
Another object is to provide a polyimide endless belt using the above polyamic acid composition, preventing deterioration in film quality due to insufficient imidization reaction, and having characteristics such as sufficient strength, and a method for producing the same. Another object of the present invention is to provide an image forming apparatus provided with this polyimide endless belt.

The above problem is solved by the following means. That is, the present invention
(1) and γ- butyrolactone, and a mixed solvent of N- methyl-2-pyrrolidone down,
A polymer containing a polyamic acid structure;
Tertiary amines,
A carboxylic anhydride,
A polyamic acid composition comprising:

(2) The polyamic acid composition as described in (1), further comprising a conductive agent .

(3) A polyimide endless belt obtained by imidizing the polyamic acid composition according to (1) or (2) .

(4) An image forming apparatus comprising the polyimide endless belt described in (3).

(5) A method for producing a polyimide endless belt, wherein the polyamic acid composition according to (1) or (2) is applied to a mold and then imidized by a drying and firing step .

According to the polyamic acid composition of the present invention, a high imidization reaction rate can be obtained even at a low baking treatment temperature and a short baking treatment time, and it is possible to reduce the baking temperature and the baking time.
In addition, according to the polyimide endless belt of the present invention and the method for producing the same, since the polyamic acid composition of the present invention is used, deterioration of film quality due to insufficient imidization reaction is prevented, and characteristics such as sufficient strength are provided. There is an effect.

  Hereinafter, the present invention will be described in detail.

[Polyamic acid composition]
The polyamic acid composition according to the first aspect of the present invention includes a specific coating solvent, a polyamic acid, and / or a polyamic acid-polyimide copolymer. Further, it contains a tertiary amine and a carboxylic acid anhydride. Moreover, additives, such as a electrically conductive agent, can also be included as needed.

  In the polyamic acid composition of the first aspect of the present invention, the thermal imidization reaction is promoted and the firing temperature can be reduced and the firing time can be shortened by using a specific coating solvent described later as the solvent component in the composition. In addition, since the conventional process and equipment can be used as they are, the industrial applicability is high. Moreover, since the specific coating solvent mentioned later can be applied to a polyimide material having a rigid molecular structure without any restriction on the polyimide molecular structure, a polyimide molded product having characteristics such as sufficient strength can be obtained.

Then, a specific coating solvent discussed later, by combining the tertiary amine, greatly promote give imidization reaction during firing, the addition of only a tertiary amine, further combination of carboxylic acid anhydride as a dehydrating agent By doing so, a greater promotion effect can be obtained. Compared with the conventional technology in which only a tertiary amine is used as a catalyst, the imidization reaction is used, and by using a polyamic acid composition having a specific solvent composition, high imidization even at a low baking treatment temperature and a short baking treatment time. A reaction rate is obtained, a deterioration in film quality due to insufficient imidization reaction is prevented, and a molded product having characteristics such as sufficient strength can be obtained. As a result, since the firing temperature can be reduced and the firing time can be shortened as compared with the prior art, the industrial applicability is expected such that energy saving and productivity can be improved. Furthermore, the leveling performance at the time of coating is improved as an effect of the combined use of a specific coating solvent and a tertiary amine, and the smoothness of the belt after the drying / firing process is improved and the quality is improved.

  Hereinafter, each composition will be described.

((A) polymer containing polyamic acid structure)
The polymer containing a polyamic acid structure is a polymer that can be a polyimide precursor, and examples thereof include a polyamic acid and a polyamic acid-polyimide copolymer.

  As the polyamic acid, a polyamic acid represented by the following general formula (1) is preferably exemplified. Moreover, as a polyamic acid-polyimide copolymer, the polyamic acid-polyimide copolymer represented by following General formula (2) is mentioned suitably.

In general formula (1), R ₁ represents a tetravalent organic group, and R ₂ represents a divalent organic group. On the other hand, in the general formula (2), R ₃ represents a tetravalent organic group, R ₄ represents a divalent organic group, R ₅ represents a tetravalent organic group, and R ₆ represents a divalent organic group. Indicates.

Here, the divalent organic groups R ₂ , R ₄ , and R ₆ are represented as a residue structure obtained by removing two amino groups from the corresponding diamine compound. Further, the tetravalent organic groups R ₁ , R ₃ , and R ₅ are represented as residues obtained by removing four carbonyl groups from the corresponding tetracarboxylic acid compound.

  Hereinafter, the polyamic acid and the polyamic acid-polyimide copolymer will be described in more detail.

  The polyamic acid can be obtained by polymerizing a tetracarboxylic dianhydride and a diamine compound in a substantially equimolar amount in an organic polar solvent. The polyimide-polyamic acid copolymer is synthesized by partially imidizing after the polyamic acid polymerization.

-Tetracarboxylic dianhydride-
There is no restriction | limiting in particular as tetracarboxylic dianhydride which can be used for manufacture of a polyamic acid, Either an aromatic type or an aliphatic type compound can be used.

  Examples of the aromatic tetracarboxylic acid include pyromellitic dianhydride, 3,3 ′, 4,4′-benzoenone tetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenyl sulfone. Tetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenyl Ether tetracarboxylic dianhydride, 3,3 ′, 4,4′-dimethyldiphenylsilane tetracarboxylic dianhydride, 3,3 ′, 4,4′-tetraphenylsilane tetracarboxylic dianhydride, 1, 2,3,4-furantetracarboxylic dianhydride, 4,4′-bis (3,4-dicarboxyphenoxy) diphenyl sulfide dianhydride, 4,4′-bis (3,4-dicarboxyphenoxy) Phenylsulfone dianhydride, 4,4′-bis (3,4-dicarboxyphenoxy) diphenylpropane dianhydride, 3,3 ′, 4,4′-perfluoroisopropylidenediphthalic dianhydride, 3, 3 ′, 4,4′-biphenyltetracarboxylic dianhydride, bis (phthalic acid) phenylphosphine oxide dianhydride, p-phenylene-bis (triphenylphthalic acid) dianhydride, m-phenylene-bis (tri Phenylphthalic acid) dianhydride, bis (triphenylphthalic acid) -4,4′-diphenyl ether dianhydride, bis (triphenylphthalic acid) -4,4′-diphenylmethane dianhydride, and the like.

  Aliphatic tetracarboxylic dianhydrides include butanetetracarboxylic dianhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,3-dimethyl-1,2,3,4-cyclobutane. Tetracarboxylic acid, 1,2,3,4-cyclopentanetetracarboxylic dianhydride, 2,3,5-tricarboxycyclopentylacetic acid dianhydride, 3,5,6-tricarboxynorbonane-2-acetic acid dianhydride Anhydride, 2,3,4,5-tetrahydrofurantetracarboxylic dianhydride, 5- (2,5-dioxotetrahydrofural) -3-methyl-3-cyclohexene-1,2-dicarboxylic dianhydride, An aliphatic or alicyclic tetracarboxylic dianhydride such as bicyclo [2,2,2] -oct-7-ene-2,3,5,6-tetracarboxylic dianhydride; 4 5,9b-Hexahydro-2,5-dioxo-3-furanyl) -naphtho [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 Examples include aliphatic tetracarboxylic dianhydrides having an aromatic ring such as -5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] furan-1,3-dione. Can do.

  As tetracarboxylic dianhydride, aromatic tetracarboxylic dianhydride is preferable, and pyromellitic dianhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, 3, 3 ', 4,4'-biphenylsulfone tetracarboxylic dianhydride is optimally used.

  These tetracarboxylic dianhydrides can be used alone or in combination of two or more.

-Diamine compound-
Next, the diamine compound that can be used for producing the polyamic acid is not particularly limited as long as it is a diamine compound having two amino groups in the molecular structure.

  For example, p-phenylenediamine, m-phenylenediamine, 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenylethane, 4,4′-diaminodiphenyl ether, 4,4′-diaminodiphenyl sulfide, 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′-trifluoromethylbenzanilide, 3,4′-diaminodiphenyl ether, 2,7- Aminofluorene, 2,2-bis (4-aminophenyl) hexafluoropropane, 4,4'-methylene-bis (2-chloroaniline), 2,2 ', 5,5'-tetrachloro-4,4' -Diaminobiphenyl, 2,2'-dichloro-4,4'-diamino-5,5'-dimethoxybiphenyl, 3,3'-dimethoxy-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-bis (4-aminophenyl) fluorene, 4,4 ′-(p-phenyleneisopropylidene) bisaniline, 4,4 ′-(m-phenyleneisopropylidene) bisaniline, 2,2′-bis [4- ( Aromatic aminodiamines such as 4-amino-2-trifluoromethylphenoxy) phenyl] hexafluoropropane, 4,4′-bis [4- (4-amino-2-trifluoromethyl) phenoxy] -octafluorobiphenyl; An aromatic diamine having two amino groups bonded to an aromatic ring such as tetraphenylthiophene and a hetero atom other than the nitrogen atom of the amino group; 1,1-metaxylylenediamine, 1,3-propanediamine, tetra Methylenediamine, pentamethylenediamine, octamethylenediamine, nonamethylenediamine, 4, 4-diaminoheptamethylenediamine, 1,4-diaminocyclohexane, isophoronediamine, tetrahydrodicyclopentadienylenediamine, hexahydro-4,7-methanoindanylene methylenediamine, tricyclo [6,2,1,02. 7] -undecylenedimethyldiamine, aliphatic diamines such as 4,4′-methylenebis (cyclohexylamine), and alicyclic diamines.

As the diamine compound, p-phenylenediamine, 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenyl ether, 4,4′-diaminodiphenyl sulfide, and 4,4′-diaminodiphenyl sulfone are preferable.
These diamine compounds can be used alone or in combination of two or more.

-Combination of tetracarboxylic dianhydride and diamine compound-
As a polyamic acid, Preferably, what consists of aromatic tetracarboxylic dianhydride and aromatic diamine from a viewpoint of the intensity | strength of a molded object is preferable.

-Synthetic solvent-
Examples of the organic polar solvent used in the polyamic acid production reaction include sulfoxide solvents such as dimethyl sulfoxide and diethyl sulfoxide, formamide solvents such as N, N-dimethylformamide and N, N-diethylformamide, N, Acetamide solvents such as N-dimethylacetamide and N, N-diethylacetamide, pyrrolidone solvents such as N-methyl-2-pyrrolidone and N-vinyl-2-pyrrolidone, phenol, o-, m-, or p-cresol Phenol solvents such as xylenol, halogenated phenol and catechol, ether solvents such as tetrahydrofuran, dioxane and dioxolane, alcohol solvents such as methanol, ethanol and butanol, cellosolve such as butyl cellosolve and hexame Ruhosuhoruamido, etc. can be mentioned γ- butyrolactone, but 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 polyamic acid and polyamic acid-polyimide copolymer.

-Solid content concentration during polyamic acid polymerization-
The solid content concentration of the polyamic acid solution is not particularly limited, but is preferably 5 to 50% by weight, more preferably 10 to 30% by weight. When the solid content concentration is less than 5% by weight, the degree of polymerization of the polyamic acid is low, and the strength of the molded product finally obtained is lowered. Moreover, when the solid content concentration at the time of polymerization is higher than 50% by weight, an insoluble part of the raw material monomer is generated during the reaction, and the reaction hardly proceeds. As a result, the strength of the finally obtained molded body is reduced.

-Polyamic acid polymerization temperature-
As reaction temperature at the time of polyamic acid polymerization, it is carried out in the range of 0 ° C to 80 ° C. This is because when the reaction temperature is 0 ° C. or lower, the viscosity of the solution increases and the reaction system cannot be sufficiently stirred. On the other hand, when the reaction temperature is higher than 80 ° C., a part of the imidization reaction occurs in parallel with the polymerization of the polyamic acid, which causes a problem in terms of reaction control.

-Imidation reaction-
The polyamic acid-polyimide copolymer is obtained by heat-treating the polyamic acid and / or chemically imidating a dehydrating agent and / or a catalyst to act on a part of the amic acid group in the polyamic acid. Obtained by conversion to an imide group by dehydration ring closure reaction.

  The heating temperature in the heat treatment method is usually 60 ° C. or higher and 200 ° C. or lower, preferably 100 ° C. or higher and 170 ° C. or lower. When the heating temperature is less than 60 ° C., dehydration ring closure does not proceed sufficiently, and when the heating temperature exceeds 200 ° C., the molecular weight of the polymer obtained is small.

  On the other hand, in the chemical imidization method, a dehydrating agent and / or a catalyst is added to the polyamic acid solution to advance the imidization reaction chemically. The dehydrating agent is not particularly limited as long as it is a monovalent carboxylic anhydride. For example, one type or two or more types selected from acid anhydrides such as acetic anhydride, propionic anhydride, trifluoroacetic anhydride, butanoic anhydride, and oxalic anhydride can be used. The amount of the dehydrating agent used is preferably 0.01 mol or more and 2 mol or less with respect to 1 mol of the polyamic acid repeating unit.

  As the catalyst, for example, one kind or two or more kinds selected from tertiary amines such as pyridine, picoline, collidine, lutidine, quinoline, isoquinoline and triethylamine can be used, but the catalyst is not limited thereto. The amount of the catalyst used is preferably 0.01 mol or more and 2 mol or less with respect to 1 mol of the dehydrating agent to be used.

  This chemical imidation reaction is performed by adding a dehydrating agent and / or a catalyst to the polyamic acid solution and heating as necessary. The reaction temperature for dehydration and ring closure is usually 0 ° C. or higher and 180 ° C. or lower, preferably 60 ° C. or higher and 150 ° C. or lower.

  There is no particular limitation as long as it is partially imidized, but the composition ratio of the imidized structure to the unreacted amic acid structure is 0/100 (mol / mol) to 80/20 (mol / mol). ) Is preferable. When the composition ratio between the imide group and the amic acid group is 80/20 (mol / mol) or more, the polyamic acid-polyimide copolymer may be insolubilized.

  Although the dehydrating agent and / or the catalyst that acted on the polyamic acid-polyimide copolymer need not be removed, the polyamic acid-polyimide copolymer may be removed by the following method in order to improve the stability of the solution viscosity over time. As a method for removing the dehydrating agent and / or the catalyst that has acted, heating under reduced pressure or a reprecipitation method can be used. The reduced pressure heating is performed at a temperature of 80 ° C. or higher and 120 ° C. or lower under vacuum to distill off the tertiary amine, unreacted dehydrating agent and hydrolyzed carboxylic acid used as a catalyst. The reprecipitation method uses a poor solvent that dissolves the catalyst, unreacted dehydrating agent and hydrolyzed carboxylic acid, and does not dissolve the polyamic acid-polyimide copolymer. , By adding the reaction solution. The poor solvent is not particularly limited, and water, alcohol solvents such as methanol and ethanol, ketone solvents such as acetone and methyl ethyl ketone, hydrocarbon solvents such as hexane, and the like can be used. The precipitated polyamic acid-polyimide copolymer is filtered and dried, and then dissolved again in a solvent such as γ-butyrolactone and N-methyl-2-pyrrolidone.

  The polymer containing the polyamic acid structure described above preferably has a solid content concentration in the polyamic acid composition of 10% by weight or more from the viewpoint of obtaining a desired thickness as a belt material. On the other hand, conventionally, when this solid content concentration is high, the coating performance on the mold deteriorates, and the solvent cannot be sufficiently removed in the drying and baking process, and the quality is lowered in terms of shape and film strength. However, the present invention can be effectively improved. The solid concentration is preferably 15% by weight or more, and the upper limit is 50% by weight.

((B) coating solvent)
The specific coating solvent (hereinafter referred to as the first coating solvent) is a mixed solvent of a first solvent selected from γ-butyrolactone and a second solvent selected from N-methyl-2-pyrrolidone.

The first coating solvent, especially γ- first and solvent butyrolactone is down or we selected to be a mixed solvent of a second solvent selected from N- methyl-2-pyrrolidone, imides during firing It is suitable in terms of allowing the crystallization reaction to proceed smoothly and in terms of leveling properties during coating.

  In the first coating solvent, the weight ratio of the first solvent to the second solvent (first solvent / second solvent) is preferably in the range of 90/10 to 10/90, more preferably 80 / It is in the range of 20 to 30/70, more preferably in the range of 49/51 to 30/70.

The first coating solvent may be used from the previous polyamic acid synthesis, or may be replaced with a predetermined solvent after polyamic acid polymerization or after imidization reaction. For solvent replacement, a method of adding a predetermined solvent to a polyamic acid solution or a polyamic acid-polyimide copolymer solution and diluting, a method of re-precipitating a polymer and then re-dissolving in the predetermined solvent, a solvent gradually Any method of adjusting the composition by adding a predetermined solvent while distilling off may be used.

((C) Tertiary amine)
The tertiary amine functions as a catalyst for imidization reaction, and for example, one or more selected from pyridine, picoline, collidine, lutidine, quinoline, isoquinoline, and triethylamine can be preferably used.

  The content of the tertiary amine may be added in an amount of 0.1 to 30 parts by weight with respect to 100 parts by weight of the resin component in the polyamic acid composition. This is because if the addition amount is 0.1 parts by weight or less, the imidization promoting effect cannot be exhibited, and if it is 30 parts by weight or more, the stability of the polyamic acid composition cannot be ensured.

((D) Carboxylic anhydride)
Carboxylic anhydride serves as a dehydrating agent during the imidization reaction and promotes the imidization reaction. Examples of the carboxylic acid anhydride include acetic anhydride, trifluoroacetic acid anhydride, propionic acid anhydride, butanoic acid anhydride, oxalic acid anhydride, and the like. Among these, acetic anhydride is preferable. These may be used alone or in combination of two or more.

  The content of the carboxylic acid anhydride may be added in an amount of 0.1 to 30 parts by weight with respect to 100 parts by weight of the resin component in the polyamic acid composition. This is because if the addition amount is 0.1 parts by weight or less, the imidization promoting effect cannot be exhibited, and if it is 30 parts by weight or more, the stability of the polyamic acid composition cannot be ensured.

((E) Conductive agent)
The polyamic acid composition of the present invention can also contain a conductive agent. For example, when the obtained polyimide molded product is used for an intermediate transfer member in an electrophotographic apparatus, a conductive material is dispersed and a polyimide molded product (for example, a semiconductive belt) having a desired electrical resistivity can be obtained. it can.

  As the conductive agent, conductive or semiconductive fine powder can be used, and there is no particular limitation as long as the desired electric resistance can be stably obtained. However, carbon black such as Ketchen Black and Acetylene Black, aluminum and the like Examples thereof include metals such as nickel, metal oxide compounds such as tin oxide, and potassium titanate. These may be used alone or in combination. In the present invention, since the dispersibility in the resin is good, good dispersion stability is obtained, resistance variation of a molded product (for example, a semiconductive belt) can be reduced, and electric field dependency is also reduced. In view of the stability over time of the electrical resistance at which the electric field concentration due to the transfer voltage is difficult to occur, it is proposed to add preferably oxidized carbon black having a pH of 5 or lower.

―Oxidized carbon black―
Oxidized carbon black can be produced by oxidizing carbon black to give a carboxyl group, a quinone group, a lactone group, a hydroxyl group or the like to the surface. This oxidation treatment is an air oxidation method in which contact is made with air in a high-temperature atmosphere to react, a method of reacting with nitrogen oxides or ozone at room temperature, and air oxidation at high temperature, followed by ozone oxidation at a low temperature. It can be performed by a method or the like.

  Specifically, the oxidized carbon black can be produced by, for example, a contact method. Examples of the contact method include a channel method and a gas black method. Oxidized carbon black can also be produced by a furnace black method using gas or oil as a raw material. If necessary, after these treatments, a liquid phase oxidation treatment with nitric acid or the like may be performed.

  Acidic carbon black can be produced by a contact method, but is usually produced by a closed furnace method. In the furnace method, only carbon black having a high pH and a low volatile content is usually produced, but the pH can be adjusted by subjecting it to the above-mentioned liquid phase acid treatment. For this reason, the carbon black obtained by the furnace method manufacturing and adjusted to have a pH of 5 or less by the post-treatment is also considered to be included in the present invention.

  The pH value of the oxidation-treated carbon black is pH 5.0 or less, preferably pH 4.5 or less, more preferably pH 4.0 or less. Oxidized carbon having a pH of 5.0 or less has an oxygen-containing functional group such as a carboxyl group, a hydroxyl group, a quinone group, and a lactone group on the surface, so that it has good dispersibility in the resin, and thus good dispersion stability is obtained. As a result, the resistance variation of the molded product (for example, a semiconductive belt) can be reduced, and the electric field dependency is also reduced.

  Here, pH is calculated | required by adjusting the aqueous suspension of carbon black and measuring with a glass electrode. Moreover, pH of acidic carbon black can be adjusted with conditions, such as processing temperature in an oxidation treatment process, and processing time.

  The oxidation-treated carbon black preferably contains 1 to 25%, preferably 2 to 20%, more preferably 3.5 to 15% of a volatile component. When the volatile content is less than 1%, the effect of the oxygen-containing functional group attached to the surface is lost, and the dispersibility in the binder resin may be reduced. On the other hand, when the content is higher than 25%, the appearance of the molded product obtained may be decomposed when dispersed in the binder resin or the amount of water adsorbed on the oxygen-containing functional group on the surface increases. May cause problems such as worsening. Therefore, the dispersion | distribution in binder resin can be made more favorable by making a volatile content into the said range. This volatile content can be determined by the ratio of organic volatile components (carboxyl group, hydroxyl group, quinone group, lactone group, etc.) that come out when carbon black is heated at 950 ° C. for 7 minutes.

  Specific examples of the oxidation-treated carbon black include “Printex 150T” (pH 4.5, volatile content 10.0%) and “Special Black 350” (pH 3.5, volatile content 2.2%) manufactured by Degussa. ), "Special Black 100" (pH 3.3, volatile matter 2.2%), "Special Black 250" (pH 3.1, volatile matter 2.0%), "Special Black 5" (pH 3.0) Volatile content 15.0%), "Special Black 4" (pH 3.0, volatile content 14.0%), "Special Black 4A" (pH 3.0, volatile content 14.0%), "Special" "Black 550" (pH 2.8, volatile content 2.5%), "Special Black 6" (pH 2.5, volatile content 18.0%), "Color Black FW200" (pH 2.5, volatile content 20. 0% "Color Black FW2" (pH 2.5, volatile content 16.5%), "Color Black FW2V" (pH 2.5, volatile content 16.5%), "MONARCH1000" (pH 2.5, manufactured by Cabot Corporation) Volatile content 9.5%), Cabot “MONARCH 1300” (pH 2.5, volatile content 9.5%), Cabot “MONARCH 1400” (pH 2.5, volatile content 9.0%), “MOGUL- L ”(pH 2.5, volatile matter 5.0%),“ REGAL400R ”(pH 4.0, volatile matter 3.5%) and the like.

-Addition amount of oxidized carbon black-
Oxidized carbon black has good dispersibility in the resin composition due to the effect of oxygen-containing functional groups present on the surface as described above compared to general carbon black. Is preferably increased. As a result, the amount of carbon black in the molded product (for example, a semiconductive belt) increases, so that the effect of using oxidized carbon black that can suppress the in-plane variation of the electrical resistance value is maximized. It can be demonstrated.

  By containing 10 to 30% by weight of the oxidized carbon black, the effects of the oxidized carbon black are exhibited, such as suppressing in-plane variation in the surface resistivity of a molded product (for example, a semiconductive belt). When this content is less than 10% by weight, it is difficult to obtain a desired resistance value. On the other hand, if it exceeds 30% by weight, it becomes difficult to obtain a desired resistance value, the uniformity of the electrical resistance is lowered, and the in-plane unevenness of the surface resistivity and the electric field dependency are increased. Furthermore, by containing 18 to 30% by weight of oxidized carbon black, the effect can be maximized, and the in-plane unevenness of the surface resistivity and the electric field dependency can be remarkably improved.

  Although the polyamic acid composition according to the present invention has been described above, the present invention is not limited only to these embodiments, and various improvements can be made based on the knowledge of those skilled in the art without departing from the spirit of the present invention. The present invention can be implemented in a mode in which changes, modifications are made.

[Polyimide endless belt and manufacturing method thereof]


The polyimide endless belt of the present invention is mainly composed of a polyimide molded body obtained by applying the polyamic acid composition of the present invention to a mold and then imidizing it by a drying and firing process.

  Specifically, the polyimide endless belt of the present invention is produced, for example, as follows.

  First, for example, the polyamic acid composition of the present invention is prepared as follows. First, a polyamic acid solution, which is a polyimide resin precursor obtained by polymerizing a tetracarboxylic dianhydride component and a diamine component in an organic solvent, is added to a poor solvent such as methanol to precipitate polyamic acid. Reprecipitate and purify. After the precipitated polyamic acid is filtered off, it is redissolved in a solvent such as γ-butyrolactone to obtain a polyamic acid solution.

A predetermined amount of tertiary amine and carboxylic anhydride are added to the polyamic acid solution and dissolved by stirring to obtain a polyamic acid composition.

  Next, in this solution, a conductive agent such as carbon black is added in a total amount of 5 to 60 parts by weight with respect to 100 parts by weight of the dry weight of the polyamic acid resin as necessary.

  Here, the conductive agent is dispersed and the aggregate is crushed by a physical method such as stirring by a mixer or a stirrer, a parallel roll, ultrasonic dispersion, or a chemical method such as introduction of a dispersing agent. Although a method is illustrated, it is not limited to these.

  Next, this solution is applied to the inner or outer surface of the mold. As the mold, a cylindrical mold is preferable, and instead of the mold, molds made of various known materials such as resin, glass, and ceramic work well as the mold according to the present invention. obtain. It is also possible to appropriately select to provide a glass coat, a ceramic coat or the like on the surface of the mold, and to use a silicone-based or fluorine-based release agent. Further, the film thickness control mold with the clearance adjusted to the cylindrical mold is moved in parallel through the cylindrical mold, so that the excess solution is eliminated and the thickness of the solution on the cylindrical mold is made uniform. If the uniform thickness control of the solution is performed at the stage of applying the solution onto the cylindrical mold, it is not necessary to use a film thickness control mold.

  Next, this cylindrical mold coated with the polyimide resin precursor solution is placed in a heating environment, and drying is performed to volatilize 30% by mass or more, preferably 50% by mass or more of the contained solvent.

  A drying temperature performs drying in the temperature range of 50-200 degreeC.

  Further, this mold is heated at 150 ° C. to 450 ° C. to advance the imide conversion reaction. The imidization temperature varies depending on the types of the raw material tetracarboxylic dianhydride and diamine, or added tertiary amine, but must be set to a temperature at which imidization is completed. Insufficient imidization results in poor mechanical and electrical properties.

  Thereafter, the resin is removed from the mold, and the target polyimide endless belt can be obtained. The obtained polyimide endless belt may be further subjected to slit processing, punching drilling processing, tape winding processing, or the like as necessary.

  In addition, when using a polyimide endless belt as an electrophotographic transfer body, it is necessary to contain a conductive agent in the polyamic acid composition as described above so as to obtain a desired electric resistance.

  When a polyimide endless belt is used as an electrophotographic fixing member, a non-adhesive resin layer may be formed on the belt surface (outer peripheral surface) in order to prevent fusion of toner adhering to the surface (outer peripheral surface). is necessary.

  Examples of the material constituting the resin layer include fluorine resins such as polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), and tetrafluoroethylene-hexafluoropropylene copolymer (FEP). Is mentioned. For non-adhesive layers, carbon powder, inorganic compound powders such as titanium oxide and barium sulfate, etc. are used to improve wear resistance, electrostatic offset, and compatibility with toner adhesion prevention oil. Materials other than resin may be included.

  A preferable polyimide endless belt as a fixing body has a thickness of 25 to 200 μm, and a non-adhesive layer has a thickness of 5 to 50 μm.

  In order to form a fluororesin layer on the outer peripheral surface of the polyimide endless belt, a method in which the aqueous dispersion is applied to the belt surface and baked is preferable. Moreover, when the adhesiveness of a fluororesin layer is insufficient, there is a method of forming a primer layer on the endless belt surface as necessary. Examples of the material constituting the primer layer include polyphenylene sulfide, polyethersulfone, polysulfone, polyamideimide, polyimide, and derivatives thereof, and it is preferable that at least one compound selected from fluorine resins is included. The thickness of the primer layer is preferably in the range of 0.5 to 10 μm.

  In order to form the primer layer and the fluororesin layer on the outer peripheral surface of the polyimide endless belt, the material for forming these layers is applied and formed on the PI resin film (after heat treatment) formed on the outer peripheral surface of the core body. Can do. Alternatively, a dispersion containing the material constituting the primer layer and the material constituting the fluororesin layer is applied on the coating film of the polyamic acid composition (before the heat treatment) formed on the outer peripheral surface of the core, and then heated. Then, the imidization condensation reaction and the baking treatment of the fluororesin may be performed simultaneously. In the latter case, even if there is no primer layer, the adhesion between the polyimide resin layer and the fluororesin layer may be sufficiently strong. In this case, it is not necessary to form the primer layer.

  As mentioned above, although the manufacturing method of the polyimide endless belt concerning the present invention was explained, the present invention is not limited only to these embodiments, and it is based on the knowledge of those skilled in the art without departing from the spirit thereof. The present invention can be implemented with various improvements, changes, and modifications.

[Image Forming Apparatus of the Present Invention]
The image forming apparatus of the present invention is an electrophotographic image forming apparatus including the polyimide endless belt of the present invention.

  The image forming apparatus of the present invention includes, for example, an image carrier, a charging unit that charges the surface of the image carrier, an exposure unit that exposes the surface of the image carrier to form an electrostatic latent image, and is formed on the surface of the image carrier. The latent image is developed with a developer to form a toner image, a transfer unit for transferring the toner image on the transfer material, a fixing unit for fixing the toner image on the transfer material, and an image carrier. Examples of the image forming apparatus include a cleaning unit that removes toner, dust, and the like, and a static elimination unit that removes an electrostatic latent image remaining on the surface of the image bearing member. In the image forming apparatus having such a configuration, the polyimide endless belt of the present invention is applied as a secondary transfer type transfer unit using an intermediate transfer belt or a belt type fixing unit using a fixing belt. .

Specific examples of the image forming apparatus of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic cross-sectional view showing a specific example of the image forming apparatus of the present invention. In FIG. 1, 1 is an image forming apparatus, 2 is an image processing apparatus, 3 is ROS (Raster Output Scanning), and 4 is a rotating polygon mirror. 5 is an f · θ lens, 6 is a reflection mirror, 7 is a photosensitive drum, 8 is a scorotron (charger), 9 is a developing device, 10 is a pre-transfer charger, 11 is an intermediate transfer belt, and 12 is a primary transfer roll. , 13 is a driving roll, 14a is a driven roll, 14b is a tension roll, 15 is a backup roll, 16 is a recording sheet, 17 is a secondary transfer roll, 18 is a paper feed cassette, 18a is a feed roll, 19 is an intermediate transfer belt cleaning. Unit, 20 is a photosensitive member cleaning unit, 21 is a developer storage unit, 22 is a transport roll, 23 is a resist roll, 24 is a transport belt, 25 Fixing device using the fixing belt 26 is the manual paper feed unit, 60 represents a discharge tray.

  A primary transfer roll 12 (primary) is disposed around the photosensitive drum 7 in a clockwise direction (rotation direction) through a scorotron 8, a developing device 9, a pre-transfer charger 10, and an intermediate transfer belt 11. A transfer unit) and a photoconductor cleaning unit 20 are disposed. On the surface of the photosensitive drum 7 between the scorotron 8 and the developing device 9, a laser beam emitted from the ROS 3 having the rotary polygon mirror 4, the f · θ lens 4 and the reflection mirror 6 is used to cause latent images corresponding to image information. An image can be formed. The developing device 9 communicates with the developer storage unit 21 and can receive supply of the developer from the developer storage unit 21 as appropriate.

  When the image is formed, the surface of the photosensitive drum 7 is charged by the scorotron 8, and a latent image is formed on the charged surface of the photosensitive drum 7 by the laser light emitted from the ROS 3. Subsequently, the latent image is developed with a developer by the developing device 9 to obtain a toner image, and then transferred to the outer peripheral surface of the intermediate transfer belt 11. The toner remaining on the surface of the photosensitive drum 7 after the transfer is removed by the photosensitive member cleaning unit 20.

  Below the photosensitive drum 7, an intermediate transfer belt 11, a primary transfer roll 12, a drive roll 13, which are arranged in the clockwise direction on the inner peripheral surface of the intermediate transfer belt 11 to stretch the intermediate transfer belt 11, An intermediate transfer unit including a backup roll 15, a driven roll 14a, and a tension roll 14b is provided. Further, on the outer peripheral surface of the intermediate transfer belt 11, an intermediate transfer belt cleaning unit 19 disposed opposite to the drive roll 13 with the intermediate transfer belt 11 interposed therebetween, and an intermediate transfer belt 11 sandwiched between the backup roll 15. A secondary transfer roll 17 disposed oppositely is provided.

A recording medium can be inserted between the secondary transfer roll 17 and the outer peripheral surface of the intermediate transfer belt 11 (secondary transfer portion). The recording medium is conveyed / supplied to the secondary transfer section automatically by the recording sheet (recording medium) 16 stored in the paper feed cassette 18 via the feed roll 18a, the conveyance roll 22, and the registration roll 23. However, it can also be performed from the paper feed tray 26 via the registration roll 23.
A conveying belt 24 that conveys the recording sheet 16 to which the toner image is transferred is provided on the side opposite to the side on which the two sheet feeding units are provided (the side on which the recording sheet 16 is discharged). A fixing device 25 for fixing the recording sheet 16 conveyed by the conveying belt 24 and a discharge tray 60 for discharging the recording sheet 16 on which the image after the fixing process is formed to the outside of the apparatus are provided. . As the fixing device 25, a known belt nip type fixing device using a belt-belt type or belt-roll type fixing belt is applied.

  The toner image transferred to the outer peripheral surface of the intermediate transfer belt 11 at the primary transfer portion is conveyed to the secondary transfer portion when the intermediate transfer belt 11 rotates counterclockwise, and is recorded at the secondary transfer portion. Transferred onto the sheet 16. The recording sheet 16 to which the toner image has been transferred is conveyed to the fixing device 25 by the conveying belt 24, and the toner image is heated and fixed on the surface of the recording sheet 16 as described above to form an image. Thereafter, the recording sheet 16 after the image is formed is discharged to a discharge tray 60.

  The configuration of the image forming apparatus according to the present invention is not particularly limited, and may be a known configuration.

  EXAMPLES Next, although an Example demonstrates this invention in detail, this invention is not limited only to these Examples.

(Synthesis Example 1) Polymerization of polyamic acid (A)
Into a flask equipped with a stirrer, a thermometer and a dropping funnel, nitrogen gas dried with phosphorus pentoxide was passed through 29.42 g (0.1 mol) of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride. ) And 117.68 g of N-methyl-2-pyrrolidone were injected. After sufficiently stirring and dissolving, a solution prepared by dissolving 20.02 g (0.1 mol) of 4,4′-diaminodiphenyl ether in 80.08 g of γ-butyrolactone was gradually added dropwise into a flask maintained at 10 ° C. After the diamine solution was dropped, the mixture was stirred and polymerized at 10 to 15 ° C. The reaction solution was poured into methanol, and the precipitated polyamic acid was filtered off. Redissolved in γ-butyrolactone to obtain a 20% strength polyamic acid (A) solution.

(Synthesis Example 2) Synthesis of Polyamic Acid-Polyimide Copolymer (B) After polymerizing polyamic acid (A) in the flask as in Synthesis Example 1, 7.91 g (0.1 mol) of pyridine and acetic anhydride 10 were polymerized. .21 g (0.1 mol) was added sequentially. Reaction was performed at 60 degreeC for 2 hours. The reaction solution was poured into methanol, and the precipitated polyamic acid-polyimide copolymer was filtered off. The polyamic acid-polyimide copolymer (B) was obtained by redissolving in γ-butyrolactone and adjusting the concentration to 20%.

  In addition, since the solubility of the polyamic acid-polyimide copolymer (B) was lower than that of N-methyl-2-pyrrolidone for γ-butyrolactone, the solution was subjected to heat treatment.

[ Reference Example 1]
(Production Examples 1-1 to 1-16)
According to Table 1, a polyamic acid composition was prepared, and using this polyamic acid composition, a drying / firing process was performed to prepare a sample, and the obtained sample was evaluated. The results are shown in Table 1.

  As shown in Table 1, various solvents were added to the polyamic acid (A) and the polyamic acid-polyimide copolymer (B) to prepare a 1 wt% polyamic acid composition. A film was formed on a silicone wafer by spin coating. And after heating on the hotplate adjusted to predetermined temperature and drying a solvent, the baking process was performed in the clean oven adjusted to predetermined temperature.

-Measurement of imidization rate-
The obtained sample was subjected to infrared absorbance measurement in the range of 1000 to 2000 cm ⁻¹ using a microscopic Fourier transform infrared spectrophotometer FT-530 manufactured by Horiba. The imidization ratio was quantified using the peak ratio of the peak due to the imide group at 1780 cm ⁻¹ and the peak of the benzene ring at 1500 cm ⁻¹ . The results are shown in Table 1.

(Production Examples 1-17 to 1-30)
As shown in Table 2, various solvents were added to the polyamic acid (A) and the polyamic acid-polyimide copolymer (B) to prepare a 10% by weight polyamic acid composition. It coated with the coating thickness of 500 micrometers using the bar coater on the metal plate which gave the mold release agent process. The solvent was dried on a hot plate at 100 ° C. for 30 minutes, and then baked at 150 ° C. for 30 minutes in a clean oven. A polyimide film was prepared by peeling from the metal plate.

  In the case of carbon black-dispersed polyimide products (Production Examples 1-23 and 1-30), polyimide molded products were prepared and evaluated as follows. First, various solvents are respectively added to the polyamic acid (A) and the polyamic acid-polyimide copolymer (B) to prepare a 10% by weight polyamic acid composition. As a conductive agent, carbon black “Printex 150T manufactured by Degussa Co., Ltd. is used. Was added so as to be 20 parts by weight relative to the polyamic acid content. Dispersion treatment was performed with a disper. A metal plate having been subjected to a release agent treatment was applied with a coating thickness of 500 μm using a bar coater. The solvent was dried on a hot plate at 100 ° C. for 30 minutes, and then baked at 150 ° C. for 30 minutes in a clean oven. A polyimide film obtained by peeling from a metal plate was prepared.

-Mechanical strength of polyimide molded products-
A dumbbell-shaped test piece having a width of 5 mm was produced from the obtained polyimide film using a punching machine. And tensile strength (speed 100mm / min), elastic modulus, tensile strength, and elongation at break were measured using a tensile tester 1605N manufactured by Aiko Engineering. The results are shown in Table 2.

[Comparative Example 1]
(Production Examples 1-31 to 1-40)
According to Tables 3 and 4, tests were performed in the same manner as in Reference Example 1 except that the solvent composition in the polyamic acid composition was N-methyl-2-pyrrolidone alone. The results are shown in Tables 3 and 4.

  From the results of Tables 1 to 4, when a polyamic acid composition containing a specific solvent composition is used, an imidization reaction can be performed at a lower firing temperature and in a shorter time compared to a conventional polyamic acid composition. Recognize.

[ Reference Example 2]
(Adjustment Example 1) Preparation of polyamic acid composition (A) 3,3 ′, 4,4′-biphenyl was passed through a nitrogen gas dried with phosphorus pentoxide through a flask equipped with a stirrer, thermometer and dropping funnel. 29.42 g (0.1 mol) of tetracarboxylic dianhydride and 117.68 g of N-methyl-2-pyrrolidone were injected. After sufficiently stirring and dissolving, a solution prepared by dissolving 20.02 g (0.1 mol) of 4,4′-diaminodiphenyl ether in 80.08 g of N-methyl-2-pyrrolidone was gradually put in a flask maintained at 10 ° C. It was dripped. After dropwise addition of the diamine solution, stirring and polymerization were performed at 10 to 15 ° C. The reaction solution is poured into a large amount of methanol, the precipitated polyamic acid is filtered and dried, and then dissolved in a mixed solvent of γ-butyrolactone and N-methyl-2-pyrrolidone (50/50 weight ratio) to give 20 weight. % Polyamic acid composition (A) was obtained.

(Adjustment Example 2) Preparation of polyamic acid-polyimide copolymer composition (B) After polymerizing polyamic acid (A) in the flask in the same manner as in Preparation Example 1, 7.91 g (0.1 mol) of pyridine and anhydrous Acetic acid 10.21 g (0.1 mol) was added sequentially. Reaction was performed at 60 degreeC for 2 hours. The reaction solution was poured into methanol, and the precipitated polyamic acid-polyimide copolymer (B) was filtered off. After drying, it was dissolved in a mixed solvent of N-methyl-2-pyrrolidone and γ-butyrolactone (50/50 weight ratio) to obtain a 20% by weight polyamic acid-polyimide copolymer composition (B).

(Adjustment Examples 3 to 6) Preparation of polyamic acid compositions (C) to (F) The polyamic acid composition was the same as in Synthesis Example 1 except that the solvent to be redissolved after filtration was changed as shown in Table 1. Items (C) to (F) were prepared.

(Preparation Example 7) Preparation of carbon black-dispersed polyamic acid composition liquid (a) In 200 g of the polyamic acid composition (A), dried oxidized carbon black (SPECIAL BLACK4 (manufactured by Degussa, pH 4.0, volatile content: (14.0%) 8.0 g was added and treated in a ball mill for 6 hours to obtain a carbon black-dispersed polyamic acid composition (a).

(Adjustment Examples 8 to 10) Adjustment of the carbon black-dispersed polyamic acid compositions (b) to (e) The carbon black-dispersed polyamic acid composition was the same as the adjustment example 7 except that the used polyamic acid composition was changed. Products (b) to (d) were obtained.

(Production Example 2-1)
The obtained polyamic acid composition (A) was uniformly applied to the surface of a cylindrical SUS mold having an inner diameter of 90 mm and a length of 450 mm. The cylindrical mold was preliminarily coated with a fluorine-based release agent to improve the peelability after belt molding. Next, a drying process was performed for 30 minutes at a temperature of 120 ° C. while rotating the mold. After the drying treatment, the mold was placed in an oven and baked at 220 ° C. for about 30 minutes to advance the imidization reaction. Thereafter, the mold was allowed to cool at room temperature, the resin was removed from the mold, and the target polyimide endless belt was obtained.

  The obtained polyimide endless belt was subjected to mechanical properties such as imidization rate, thickness measurement, and tensile strength as follows. The results are shown in Table 7.

-Imidization rate-
A test piece was cut out from the obtained polyimide endless belt and measured by FT-IR. The 400 ° C. calcined product as 100% imidization ratio was determined by the ratio of the vibration peaks of the aromatic ring of the stretch peak and 1500 cm ^-1 of the carbonyl group derived from the imide groups of the 1776 cm ^-1.

-Belt thickness measurement-
Ten test pieces were randomly cut out from the obtained polyimide endless belt, and a film thickness meter was used.

-Mechanical strength-
The elastic modulus, tensile strength, and elongation at break were measured with a tensile tester (1605N manufactured by Aiko Engineering Co., Ltd.). Using a punch molding machine, a test piece having a length of 100 mm and a width of 5 mm was prepared, and a tensile test was performed with a length of 40 mm.

-Belt appearance-
The appearance of the obtained belt was visually observed and evaluated as follows.
○: No voids were observed at all, and the film uniformity was excellent.
○ to Δ: Some voids are observed, but there is no problem in practical use.
Δ: Generation of voids is observed, which is somewhat hindered in practical use.
X: Void frequently occurs and cannot be used practically.

  As a result, the imidization ratio of this polyimide endless belt was approximately 100% and the thickness was 70 ± 2 μm, and the film thickness unevenness seen in the progress of the imidization reaction was suppressed and uniform. Moreover, since the imidation reaction has substantially progressed, the belt has high film strength. It showed characteristics suitable as a fixing belt.

(Production Examples 2-2 to 2-14)
A polyimide endless belt was produced in the same manner as in Production Example 2-1, except that the polyamic acid composition prepared in Preparation Examples 1 to 10 was used and the firing temperature and firing time were changed as shown in Table 7. The properties of the obtained polyimide belt are shown in Table 7. It was confirmed that the belt obtained under any of the conditions had suitable characteristics similar to those of Production Example 2-1.

Further, when the volume resistivity of the semiconductive belt obtained from the polyamic acid composition containing carbon black was measured under the following conditions, the volume resistance value of any belt showed 1 × 10 ⁸ Ωcm, It was confirmed that the toner had suitable characteristics as an intermediate transfer belt.

-Volume resistance value-
A test piece of 10 × 10 cm ² was cut out from the obtained polyimide endless belt, and its volume resistance value was measured with an ultra-high resistance measuring device manufactured by Advantech.

(Electronic camera mounting test)
Production Examples 2-9 to 2-14 The obtained endless belt made of polyimide was incorporated in an electrophotographic apparatus “DocuCentreColor400CP” manufactured by Fuji Xerox Co., Ltd. as an intermediate transfer belt, and the initial copy image quality was evaluated. As evaluation items for copy image quality, the presence / absence of printing deviation, the presence / absence of uneven printing density, the presence / absence of ghost, etc. were evaluated. The image quality after the 50,000 sheet passing test was similarly evaluated. The belt length before and after the paper passing test was measured, and the belt durability when using the actual machine was evaluated and compared. The evaluation results are shown in Table 8.

[Comparative Example 2]
(Adjustment Example 11) Preparation of polyamic acid composition (G) In the same manner as in Adjustment Example 1, a polyamic acid was synthesized. Then, after depositing in methanol, it was dissolved in an N-methyl-2-pyrrolidone single solvent to obtain a 20 wt% polyamic acid composition (G).

(Adjustment Example 12) Preparation of Polyamic Acid-Polyimide Copolymer Composition (H) A polyamic acid-polyimide copolymer (B) was synthesized in the same manner as in Adjustment Example 2. Then, after depositing in methanol, it was dissolved in a single solvent of N-methyl-2-pyrrolidone to obtain a 20% by weight polyamic acid-polyimide copolymer composition (H).

(Adjustment Examples 13 and 14) Adjustment of the carbon black-dispersed polyamic acid composition liquid (g) (h) The adjustment was performed except that the polyamic acid composition (G) and the polyamic acid-polyimide copolymer composition (H) were used. In the same manner as in Example 7, carbon black-dispersed polyamic acid compositions (g) and (h) were obtained.

(Production Examples 2-15 to 2-24)
A polyimide belt was manufactured using the polyamic acid compositions (G), (H), (g), and (h) as the polyamic acid composition. Table 9 shows the characteristics of the manufactured belt as in Reference Example 2. Table 10 shows evaluation results of the polyimide endless belts produced from the polyamic acid compositions containing carbon black in Production Examples 21 to 24, incorporated in an electrophotographic apparatus as an intermediate transfer belt, as in Reference Example 2.

  From the results shown in Tables 7 to 10, it can be seen that the polyimide endless belt improved only in terms of mechanical properties and electrical properties and improved in film quality was the one according to the present invention.

As described above, when a polyamic acid composition containing a specific solvent composition is used from Reference Examples 1 and 2 and Comparative Examples 1 and 2, an imidization reaction is performed at a lower firing temperature compared to a conventional polyamic acid composition. I understand that I can do it. As a result, it can be seen that the polyimide endless belt made of the polyimide molded body according to the present invention can be manufactured with low energy at the time of firing, and can greatly contribute to reduction of energy consumption and environmental load suppression. In addition, the polyimide endless belt according to the present invention has few defects such as generation of voids seen at the time of thermal imidization, and it is understood that nonuniformity of the film due to in-plane variation of imidization reaction is prevented. .
It can also be seen that the polyimide endless belt according to the present invention exhibits excellent characteristics when used as an intermediate transfer belt.

(Examples 3-1 to 3-17)
-Measurement of film formation, drying, firing process and imidization rate-
According to Table 11, 1% by weight of a polyamic acid composition was prepared by adding predetermined amounts of pyridine and acetic anhydride as various solvents and tertiary amines to the polyamic acid (A) and the polyamic acid-polyimide copolymer (B), respectively. A film was formed on a silicone wafer by a spin coating method (spin coating conditions; 300 rpm × 10 seconds + 3000 rpm × 60 seconds).

The solvent was dried by heating at 100 ° C. for 30 minutes on a hot plate adjusted to a predetermined temperature, and then baked in a clean oven adjusted to the predetermined temperature. The obtained sample was subjected to infrared absorbance measurement in the range of 1000 to 2000 cm ⁻¹ using a microscopic Fourier transform infrared spectrophotometer FT-530 manufactured by Horiba.

The imidization ratio was quantified using the peak ratio of the peak due to the imide group at 1780 cm ⁻¹ and the peak of the benzene ring at 1500 cm ⁻¹ .

The results are shown in Table 11. However, Example 3-5, 3-7, Example excluding 3-9,3-17 corresponds to a reference example.

(Examples 3-18 to 3-31)
-Polyimide endless belt-
According to Table 12, to the polyamic acid (A) and the polyamic acid-polyimide copolymer (B), pyridine and acetic anhydride were added in predetermined amounts as various solvents and tertiary amines, respectively, to prepare a 15% by weight polyamic acid composition. This was uniformly applied to the surface of a cylindrical SUS mold having an inner diameter of 90 mm and a length of 450 mm. The cylindrical mold was preliminarily coated with a fluorine-based release agent to improve the peelability after belt molding. Next, a drying process was performed at 150 ° C. for 30 minutes while rotating the mold. After the drying treatment, the mold was placed in an oven and baked at 200 ° C. for about 30 minutes to advance the imidization reaction. Thereafter, the mold was allowed to cool at room temperature, the resin was removed from the mold, and the target polyimide endless belt was obtained.

The obtained polyimide endless belt was evaluated for mechanical properties such as tensile strength and surface condition as follows. The results are shown in Table 12. However, the examples except Examples 3-21, 3-23, and 3-25 correspond to reference examples.

-Mechanical property evaluation of polyimide endless belt-
A dumbbell-shaped test piece having a width of 5 mm was produced from the obtained polyimide endless belt using a punching machine. And tensile strength (speed 100mm / min), elastic modulus, and elongation at break were measured using a tensile tester 1605N manufactured by Aiko Engineering.

―Evaluation of surface condition―
In order to investigate the surface state of the obtained polyimide endless belt, the surface roughness Ra was measured. The surface roughness Ra is measured using a surface roughness meter Surfcom 1400A (manufactured by Tokyo Seimitsu Co., Ltd.) according to JIS B0601-1994, with an evaluation length Ln of 4 mm, a reference length L of 0.8 mm, and a cut. The measurement was performed under the measurement conditions with an off value of 0.8 mm.

(Examples 3-32 to 3-45)
(Carbon black dispersed polyimide endless belt)
According to Table 13, the polyamic acid (A) and the polyamic acid-polyimide copolymer (B) were each added with a predetermined amount of pyridine and acetic anhydride as various solvents and tertiary amines to prepare a 15 wt% polyamic acid composition. As a conductive agent, Degussa carbon black “Printex 150T” was added in an amount of 20 parts by weight based on the polyamic acid content. Dispersion treatment was performed with a disper.

  This was uniformly applied to the surface of a cylindrical SUS mold having an inner diameter of 90 mm and a length of 450 mm. The cylindrical mold was preliminarily coated with a fluorine-based release agent to improve the peelability after belt molding. Next, a drying process was performed at 150 ° C. for 30 minutes while rotating the mold. After the drying treatment, the mold was placed in an oven and baked at 200 ° C. for about 30 minutes to advance the imidization reaction. Thereafter, the mold was allowed to cool at room temperature, the resin was removed from the mold, and the target polyimide endless belt was obtained.

The obtained belt was evaluated for mechanical strength and volume resistance. The obtained polyimide endless belt was incorporated as an electrophotographic apparatus DocuCentreColor400CP intermediate transfer belt manufactured by Fuji Xerox Co., Ltd., and the initial copy image quality was evaluated. As evaluation items for copy image quality, the presence / absence of printing deviation, the presence / absence of uneven printing density, the presence / absence of ghost, etc. were evaluated. The image quality after the 50,000 sheet passing test was similarly evaluated. The belt length before and after the paper passing test was measured, and the belt durability when using the actual machine was evaluated and compared. The results are shown in Table 13. However, the examples except Examples 3-35, 3-37, and 3-39 correspond to reference examples.

(Comparative Examples 3-1 to 3-33)
According to Table 14, Table 15, and Table 16, the case where the solvent composition was a single solvent was tested in the same manner as in the Examples. The results are shown in Table 14, Table 15, and Table 16.

From the results of Tables 11 to 16, when a specific solvent composition according to the present invention and a polyamic acid composition containing a tertiary amine are used, an imidization reaction can be performed at a lower firing temperature compared to a conventional polyamic acid composition. It turns out that it can be done. As a result, it is possible to manufacture with low energy at the time of firing, which can greatly contribute to the reduction of energy consumption. In addition, it can be seen from the surface state that defects observed during thermal imidization are suppressed, and belt non-uniformity due to in-plane variation of imidization reaction is improved. In particular, it can be seen that these defects and non-uniformities are likely to occur even in a high concentration polyamic acid composition.
It can also be seen that the polyimide endless belt according to the present invention exhibits excellent characteristics when used as an intermediate transfer belt.

1 is a schematic cross-sectional view showing one specific example of an image forming apparatus of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Image processing apparatus 3 ROS
4 rotating polygon mirror 5 f · θ lens 6 reflecting mirror 7 photosensitive drum 8 scorotron 9 developing device 10 pre-transfer charger 11 intermediate transfer belt 12 primary transfer roll 13 driving roll 14a driven roll 14b tension roll 15 backup roll 16 recording sheet 17 Secondary transfer roll 18 Paper feed cassette 18a Feed roll 19 Intermediate transfer belt cleaning unit 20 Photoconductor cleaning unit 21 Developer storage unit 22 Transport roll 23 Registration roll 24 Transport belt 25 Fixing device

Claims (5)

and γ- butyrolactone, and a mixed solvent of N- methyl-2-pyrrolidone down,
A polymer containing a polyamic acid structure;
Tertiary amines,
A carboxylic anhydride,
A polyamic acid composition comprising:   The polyamic acid composition according to claim 1, further comprising a conductive agent. Polyimide endless belt, characterized in that it is obtained by imidizing the polyamic acid composition according to claim 1 or 2. An image forming apparatus comprising the polyimide endless belt according to claim 3 . A method for producing a polyimide endless belt, comprising applying the polyamic acid composition according to claim 1 or 2 to a mold and then imidizing by applying a drying and firing step.

Images