JP2006152257A - Transparent polyimide tubular product and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a polyimide tubular product free from blister and thickness deviation with surface smoothness and high roundness, free from air foams in the coating film and high in light transmittance, and to provide a method for producing the transparent polyimide tubular product at low cost in high productivity. <P>SOLUTION: The transparent polyimide tubular product is obtained by imidation of a polyimide precursor solution that is prepared by reaction in a polar solvent between at least one diamine selected from those of chemical formula(A) and (B) or its derivative and at least one tetracarboxylic dianhydride or its derivative. For this transparent polyimide tubular product, the water vapor permeability of the coating film thereof is 10-50 g/m<SP>2</SP>×24 h. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a transparent polyimide tubular article having a high light transmittance, no defects such as uneven thickness and bubbles, and high dimensional accuracy, and a method for producing the same. More specifically, for example, a transparent polyimide tubular material which is used as a member of an electrophotographic image forming apparatus such as a copying machine, a printer, a facsimile machine, and a composite machine thereof, and is particularly suitable for use as a transparent support for a back-exposure photosensitive drum and It relates to the manufacturing method.

  Polyimide resins are excellent in heat resistance, dimensional stability, mechanical properties, electrical properties, etc., and are widely used in the electrical, electronic and aerospace fields. Tubular materials and seamless belts made of polyimide resin with these characteristics are used as members in electrophotographic processes such as charging, photosensitivity, transfer conveyance, intermediate transfer, transfer fixing and fixing, especially in electrophotographic image forming apparatuses. Has been. For example, in an intermediate transfer belt, a polyimide resin belt is used as an intermediate transfer member when a toner image formed on a photosensitive drum is transferred to copy paper, and the toner image transferred to the copy paper is heat-fixed. As a fixing belt for this purpose, a composite fixing belt of polyimide resin and fluororesin called an on-demand fixing method is used.

  In recent years, the development of backside exposure (backside exposure) technology has attracted attention as a new trend, as electrophotographic technology has pursued image clarity including colorization as well as miniaturization, weight reduction, and speed. Yes. In this back exposure technology, a transparent electrode such as ITO (indium tin oxide) and a photoconductor layer such as a-Si (amorphous silicon) or OPC (organic photoconductor) are laminated on a cylindrical transparent support. The photosensitive member is formed, the exposure means is housed inside the photosensitive drum, and a latent image is formed by light from the inside of the drum. By storing an exposure power source or the like inside a transparent tubular object having an inner diameter of 30 to 100 mm, a reduction in size and weight can be achieved, and a clear image can be obtained.

  The properties required for the transparent support are high mechanical properties as a photosensitive drum rotating body, heat resistance when forming a transparent conductive layer, chemical resistance when forming a photoconductive layer, and high light transmittance. Therefore, it is a fatal defect that air bubbles or foreign substances that interfere with light transmission are mixed in the coating of the tubular object. At the same time, the thickness, surface roughness, and shape uniformity of the tubular material are important parameters. As a material for the transparent support, polyimide resin is particularly suitable because it is excellent in mechanical properties, heat resistance or chemical resistance.

  All of the polyimide resin tubular products used in these electrophotographic image forming apparatuses have a seamless shape. Since polyimide resins are generally insoluble in solvents and chemicals and are also thermally infusible, as disclosed in Patent Documents 1 and 2, these monomers tetracarboxylic dianhydride and diamine are polar. A polyimide precursor solution is produced by reacting in a polymerization solvent, and this solution is liquid-molded (casting) to a predetermined thickness on the mold surface, and then the temperature is raised stepwise from the drying step to 300 ° C. A method of completing imidization at ˜450 ° C. and separating from the mold to obtain a tubular product is common. Patent Document 3 discloses a method for producing a thin endless belt by a centrifugal molding method by injecting polyamic acid, which is a polyimide precursor, into the inner surface of a cylindrical mold and rotating it while heating.

  As disclosed in Patent Document 4, since the polyimide precursor solution has a high viscosity of 50 to 10,000 poise, it is defoamed in a liquid molding process on the mold surface. Further, as disclosed in Patent Document 5, a molding die is inserted into a polyimide precursor solution tank, and the mold is rotated in the liquid tank to remove bubbles on the mold surface. By letting it pass, air bubbles contained in the solution can be prevented from being brought in. Further, as disclosed in Patent Document 6, in order to prevent uneven thickness due to gas accumulation and swelling phenomenon generated in the process of heating the liquid molded product of the polyimide precursor solution and promoting imidization, A metal mold can be used.

  Thus, the manufacturing method of the polyimide tubular product is based on the method disclosed in Patent Documents 1 to 3, and solutions to the problems of bubbles and uneven thickness generated in the manufacturing process are proposed in Patent Documents 4 to 6. Has been. However, in these methods, it is difficult to obtain a transparent polyimide tubular material that does not contain bubbles in the coating, has no uneven thickness or swelling, and satisfies the required characteristics as a transparent support of the back-exposure photoreceptor. The reason is as follows.

  That is, the polyimide precursor liquid formation on the mold surface undergoes imidization by heating or the like, and a tough and smooth polyimide coating is obtained by the completion thereof. However, since it involves thermal or chemical reactions such as evaporation of polar polymerization solvent and generation of condensed water, it becomes a major obstacle to producing a smooth, transparent and excellent mechanical product.

  For example, in the process of applying a polyimide precursor solution to the outer surface of a mold with a predetermined thickness and heating in an oven to proceed with imidization, evaporation of solvent and condensed water starts from the outermost surface of the liquid molded product. At the same time, filming (filming) is promoted. After that, when heating is continued and imidization proceeds, the imidization reaction proceeds from the surface of the liquid molded body toward the inside in the thickness direction, so the surface layer becomes a film (film). Progressing, it becomes increasingly difficult to release the evaporation gas of the solvent and condensed water generated by the ongoing imidization reaction inside the coating film. If this state is continued as it is, water vapor or solvent gas is confined at the interface where the mold and the polyimide layer are in contact, the mold and the coating are separated locally, and gas can be accumulated in this part, The coating on the mold surface is pushed up in a convex shape and swells. This phenomenon becomes uneven, roundness and smoothness are impaired, and light transmission is hindered. When used as a member of an image forming apparatus, these phenomena become fatal defects.

  In addition, since the polyimide precursor solution has a very high viscosity, it is difficult to remove bubbles once generated in the solution, and the bubbles in the solution are brought directly into the liquid molding on the mold surface, and are coated by imide conversion. It is contained inside and becomes a void, which hinders light transmission and leads to a decrease in mechanical properties. In order to eliminate such problems, Patent Documents 4 and 5 disclose bubble removal methods, but this is not sufficient, and the number of bubbles once generated gradually increases. Bubbles are gradually brought in and voids increase.

As for the improvement of uneven thickness or swelling phenomenon, as disclosed in Patent Document 6, a method of removing generated steam and gas from a porous layer using a porous metal mold has been proposed. With this method, the generated gas and water vapor are removed, and uneven thickness and swelling are improved. However, since the mold surface is porous of sintered metal, the fine shape of the mold surface is tubular as it is. There is still a problem that it is transferred to the inner surface of the object to become a ground glass and the light transmittance is extremely lowered.
Japanese Patent Laid-Open No. 06-23770 Japanese Patent Laid-Open No. 01-156017 JP 05-075252 A JP 2003-1628 A Japanese Patent Laid-Open No. 07-164456 JP 2003-285341 A

  The present invention solves the above-mentioned conventional problems, has a smooth surface with a smooth surface and high roundness, has no bubbles in the coating, has a high light transmittance, and this transparent polyimide tube It is an object of the present invention to provide a method capable of producing a product at low cost with high productivity.

The transparent polyimide tubular product of the present invention is characterized in that the water vapor permeability of the coating is in the range of 10 to 50 g / m ² · 24 hr. Further, the light transmittance of the film at least at a wavelength of 420 nm is 50% or more when the film thickness is 50 ± 10 μm, and the glass transition temperature of the film is 200 ° C. or more. It is what. In addition, the method for producing a transparent polyimide tubular product of the present invention is a method in which the polyimide precursor solution having a concentration of 10% by weight to 50% by weight is formed on the mold surface in a predetermined thickness, dried, and then at a temperature of 400 ° C. or less. It is characterized by performing imide conversion.

In the present invention, by setting the water vapor transmission rate of the polyimide resin tubular product to a range of 10 to 50 g / m ² · 24 hr, liquid polyimide is formed from the polyimide precursor solution and is generated in the process of producing the tubular product by imidization reaction. A tubular product with high dimensional accuracy can be produced by eliminating meat and swelling. Therefore, even in the production of a thick tubular product, there is no generation of voids, and a tubular product free from defects can be produced. When the monomer of the present invention is used, a transparent tubular product having a high light transmittance and a high glass transition temperature can be produced. In addition, when a tubular product having a water vapor transmission rate in the above-mentioned range is manufactured, the removal of moisture and gas contained in the polyimide tubular product is processed in a short time in the subsequent step of forming a transparent conductive film in vacuum. can do. The polyimide resin tubular product prepared in the present invention can be suitably used as an intermediate transfer or heat fixing belt, and the transparent polyimide resin tubular product can be suitably used as a transparent support such as a back exposure photosensitive drum.

The transparent polyimide tubular product of the present invention has a water vapor transmission rate of 10 to 50 g / m ² · 24 hr. If it is less than 10 g / m ² · 24 hr, a swelling phenomenon due to gas accumulation occurs as in the conventional case, and it becomes difficult to remove bubbles and voids. On the other hand, when it exceeds 50 g / m ² · 24 hr, the water absorption rate of the polyimide is substantially increased, so that the dimensional stability is lowered. The light transmittance of at least a wavelength of 420 nm of the polyimide tubular coating is preferably 50% or more when the coating thickness is 50 ± 10 μm. That is, as shown in Examples 1 to 4, not only for the green and red light sources, but also for at least the blue light source, in other words, over the entire visible light region, the light transmittance is 50% or more. It is preferable to have the property. Furthermore, it is more preferable that it is 70% or more. This is because if the light transmittance is 50% or more, more preferably 70% or more, it can be suitably used for applications such as back exposure. Moreover, it is preferable that the glass transition temperature of a film is 200 degreeC or more. Furthermore, 250 degree C or more is more preferable, and 300 degree C or more is most preferable. In the backside exposed photoconductor, a process of forming a transparent conductive thin film such as ITO on the outer surface of the transparent support and annealing at a high temperature is required. This is because it can be processed without problems.

Next, the selection of the preferred material composition of the transparent polyimide tubular article of the present invention, a large atomic group in which -SO 2 - is _(sulfone) the presence of groups, the transmission of water vapor and gas is smoothly is the finished product This is considered to prevent the presence of voids that cause problems in tubular materials and defects such as uneven thickness due to gas accumulation.

Therefore, the transparent polyimide tubular product of the present invention comprises at least one diamine selected from the following chemical formula (A) or chemical formula (B) containing a —SO ₂ — group or a derivative thereof (hereinafter referred to as a diamine component) and at least one. It is preferable that a raw material composition is a polyimide precursor composition obtained by reacting a seed tetracarboxylic dianhydride or a derivative thereof (hereinafter referred to as a tetracarboxylic dianhydride component) in a polar solvent.

  As the diamine component, diamine, diisocyanate, and diaminodisilane can be used, and diamine is preferable.

  In the embodiment of the present invention, diaminodiphenyl sulfone represented by the following chemical formula (A) is particularly preferable. The diaminodiphenylsulfone may be a para-form (4,4'-diaminodiphenylsulfone) or a meta-form (3,3'-diaminodiphenylsulfone). Moreover, you may make it react by mixing a para body and a meta body.

  When the transparent polyimide precursor solution of the present invention is produced, there is no problem even if one or more of the following diamines are mixed and reacted within the range not impairing the properties of the present invention. For example, metaphenylenediamine, paraphenylenediamine, 2,5-diaminotoluene, 2,6-diaminotoluene, 4,4′-diaminobiphenyl, 3,3′-dimethyl-4,4′-biphenyl, 3,3 ′ -Dimethoxy-4,4'-biphenyl, 2,2-bis (trifluoromethyl) -4,4'-diaminobiphenyl, 3,3'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, 2,2-bis -(4-aminophenyl) propane, 3,3'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether 1,5-diaminonaphthalene, 4,4′-diaminodiphenyldiethyl Lan, 4,4′-diaminodiphenylsilane, 4,4′-diaminodiphenylethylphosphine oxide, 1,3-bis (3-aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 1, 4-bis (4-aminophenoxy) benzene, bis [4- (3-aminophenoxy) phenyl] sulfone, bis [4- (4-aminophenoxy) phenyl] sulfone, 2,2-bis [4- (4- Aminophenoxy) phenyl] propane, 2,2-bis (3-aminophenyl) 1,1,1,3,3,3-hexafluoropropane, 2,2-bis (4-aminophenyl) 1,1,1 , 3,3,3-hexafluoropropane, aromatic diamines such as 9,9-bis (4-aminophenyl) fluorene, tetramethylene diamine, hexame Aliphatic diamine, cyclohexane diamine such as phenylenediamine, isophoronediamine, norbornanediamine, bis (4-aminocyclohexyl) methane, bis (4-amino-3-methylcyclohexyl) include alicyclic diamines such as methane.

  On the other hand, examples of the tetracarboxylic dianhydride component include tetracarboxylic acid, carboxylic acid ester, tetracarboxylic dianhydride, and the like. Preferred is tetracarboxylic dianhydride.

The tetracarboxylic dianhydride component has the following chemical formula (I) or chemical formula (II) (X is —O—, —S—, —SO ₂ —, —CH ₂ —, —CF ₂ —, —C ( It is preferably at least one compound selected from CH ₃ ) ₂ —, —C (CF ₃ ) ₂ —, —CO— or a direct bond.

  In a preferred embodiment of the present invention, the tetracarboxylic dianhydride component includes 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (BPDA) of the following chemical formula (III) and the following chemical formula (IV): 2,2-bis [4- (dicarboxyphenoxy) phenyl] propane dianhydride (BPADA). BPDA and BPADA are preferably mixed and reacted.

  The molar ratio in the case of mixing BPDA and BPADA is preferably in the range of BPDA: BPADA = 9: 1 to 5: 5. This is because within this range, the toughness can be increased while maintaining the transparency high.

  When the transparent polyimide precursor solution of the present invention is produced, there is no problem even if one or more of the following tetracarboxylic dianhydrides are mixed and reacted within a range not impairing the properties of the present invention. For example, pyromellitic dianhydride, 1,2,5,6-naphthalene tetracarboxylic dianhydride, 1,4,5,8-naphthalene tetracarboxylic dianhydride, 2,3,6,7-naphthalene Tetracarboxylic dianhydride, 2,2 ′, 3,3′-biphenyltetracarboxylic dianhydride, 2,3,3′4′-biphenyltetracarboxylic dianhydride, 2,2 ′, 3,3 '-Benzophenone tetracarboxylic dianhydride, 2,3,3', 4'-benzophenone tetracarboxylic dianhydride, bis (3,4-dicarboxyphenyl) sulfone dianhydride, bis (2,3-di Carboxyphenyl) methane dianhydride, bis (3,4-dicarboxyphenyl) methane dianhydride, 1,1-bis (2,3-dicarboxyphenyl) ethane dianhydride, 1,1-bis (3 4-dicarbo Ciphenyl) ethane dianhydride, 4,4 ′-(hexafluoroisopropylidene) diphthalic anhydride, oxydiphthalic anhydride, bis (3,4-dicarboxyphenyl) sulfone dianhydride, bis (3,4-di Carboxyphenyl) sulfoxide dianhydride, thiodiphthalic dianhydride, 3,4,9,10-perylenetetracarboxylic dianhydride, 2,3,6,7-anthracenetetracarboxylic dianhydride, 1,2, 7,8-phenanthrenetetracarboxylic dianhydride, 9,9-bis (3,4-dicarboxyphenyl) fluorene dianhydride and 9,9-bis [4- (3,4'-dicarboxyphenoxy) phenyl ] Aromatic tetracarboxylic dianhydrides such as fluorene dianhydride, cyclobutane tetracarboxylic dianhydride, 1,2,3,4-cyclopentane Lacarboxylic dianhydride, 2,3,4,5-tetrahydrofurantetracarboxylic dianhydride, 1,2,4,5-cyclohexanetetracarboxylic dianhydride, 3,4-dicarboxy-1-cyclohexylsuccinic acid And dianhydride, 3,4-dicarboxy-1,2,3,4-tetrahydro-1-naphthalene succinic dianhydride.

  In a preferred embodiment of the present invention, a transparent polyimide precursor solution is prepared by reacting a tetracarboxylic dianhydride component and a diamine component in an inert atmosphere at a temperature below 90 degrees C. in a polar solvent. . The reaction time is 6 hours or more.

  When producing a transparent polyimide precursor solution, it is preferable to increase the molecular weight by reacting the tetracarboxylic dianhydride component and the diamine component in an equimolar ratio as much as possible. Therefore, the molar ratio of tetracarboxylic dianhydride component / diamine component is preferably maintained in the range of 0.9 to 1.1 / 1.0, more preferably 1.00 to 1.04 / 1.0. . The molecular weight of the transparent polyimide precursor of the present invention is preferably 5,000 to 500,000, more preferably 15,000 to 100,000.

  Polar solvents useful in the preparation of transparent polyimide precursor solutions include, for example, N, N-dimethylformamide, N, N-dimethylacetamide, N, N-diethylacetamide, N-methyl-2-pyrrolidone, 1,3- Examples thereof include dimethyl-2-imidazolidinone, N-methylcaprolactam, hexamethylphosphoric triamide, 1,2-dimethoxyethane, diglyme and triglyme. A preferred solvent is N, N-dimethylacetamide (DMAC). These solvents can be used alone or as a mixture or mixed with other solvents such as toluene, xylene, that is, aromatic hydrocarbons.

The transparent polyimide precursor solution includes a processing aid or a flow aid (for example, MODAFLOW (registered trademark) flow aid), an antioxidant, and an antistatic agent within a range that does not impair the properties of the present invention. , Inorganic pigments (eg, titanium dioxide, TiO ₂ ), and fillers (eg, polytetrafluoroethylene, fluorinated ethylene / propylene copolymers) can also be included.

  In order to facilitate the handling of the transparent polyimide precursor solution, the concentration of the polyimide precursor in the solution is in the range of 10 to 50% by weight, preferably 20 to 40% by weight, and the viscosity of the solution is It is preferably in the range of about 500 to about 5,000 poise.

  When the film forming step is completed, the polar solvent is removed from the polyimide precursor solution, and the polyamic acid is thermally imidized to become a polyimide. It may be imidized by a chemical imidization method.

  In the method for producing a transparent polyimide tubular product according to the present invention, a polyimide precursor solution having a concentration of 10% by weight to 50% by weight is formed on a mold surface with a predetermined thickness, dried, and then imidized at a temperature of 400 ° C. or lower. It is preferable. The concentration in the polyimide precursor solution is preferably in the range of 20 to 40% by weight because the thickness can be increased in one film formation. The transparent polyimide tubular product of the present invention can produce a tubular product free from uneven thickness due to remaining or swollen bubbles even if the molding thickness is increased once. Moreover, it is preferable that the polyimide precursor liquid molded product formed on the mold surface is completely imidized stepwise after drying at a temperature of about 80 ° C. and at a temperature of 400 ° C. or less. Since the polyimide precursor solution used in the present invention is a polyimide resin in which the specific monomer described above is selected in order to increase the water vapor transmission rate as well as the light transmission rate, the light transmission rate, mechanical properties, and glass transition temperature. In order to obtain the optimum value, it is preferable to complete imidization in the range of 275 to 325 ° C.

At least one transparent conductive film may be further formed on at least one surface of the transparent polyimide tubular body. The surface resistivity of the transparent conductive film is preferably 10 ¹⁰ Ω / □ or less. Examples of the transparent conductive film include an indium-tin oxide alloy, and the film thickness is preferably in the range of 50 nm to 5 μm. This conductive film can be formed by, for example, vacuum deposition, sputtering, ion plating, plasma CVD, or a coating method. Further, the film may be heat-treated (annealed) at a high temperature of 170 ° C. or higher for a relatively short time to improve transparency, heat resistance, and conductivity. Since the transparent polyimide layer has a high Tg, it can be annealed.

Details will be described below based on Examples and Comparative Examples. The viscosity of the precursor solution of the transparent polyimide produced in each Example and Comparative Example and various characteristics of the transparent polyimide tubular product were measured by the following measuring methods.
(1) Viscosity Using a viscometer LVT manufactured by Brookfield, the viscosity of the transparent polyimide precursor solution at 23 ± 1 ° C. was measured.
(2) Light transmittance The light transmittance was measured using a spectrophotometer UV-2550 manufactured by Shimadzu Corporation.
(3) Glass transition temperature Using a thermomechanical analyzer TMA-50 manufactured by Shimadzu Corporation, the temperature at which the elongation changes at a heating rate of 10 degrees C / min was measured as the glass transition temperature.
(4) Film thickness The film thickness was measured using an eddy current film thickness meter EDY-1000 manufactured by Sanko.
(5) Mechanical properties Measured at a tensile speed of 50 mm / min using an autograph AGS-10kNG manufactured by Shimadzu Corporation.
(6) Water vapor transmission rate The water vapor transmission rate in 40 degree C-90% RH was measured using GTR-10XACT made from GTR Tech.

(A) Synthesis of Transparent Polyimide Precursor Solution A 3000 mL three-necked separable flask was equipped with a stirring rod and a nitrogen gas inlet tube equipped with a stirring blade made of polytetrafluoroethylene to form a reaction vessel. Performed under atmosphere. 4,4′-Diaminodiphenylsulfone (44DDS) 203.44, sold as a diamine component under the trade name “Seika Cure S” as a diamine component so that the concentration of the polyimide precursor solution is 33% by weight. 86 g (0.822 mol) and 1,005 g of N, N-dimethylacetamide (DMAC) sold by Mitsubishi Gas Chemical Company as the reaction solvent were added, and after 44DDS was completely dissolved in DMAC, tetracarboxylic dianhydride As a component, 107.93 g (0.208) of 2,2-bis [4- (dicarboxyphenoxy) phenyl] propane dianhydride (BPADA) sold under the trade name “BPADA” from the Shanghai Synthetic Resin Research Institute Mol) and 3,3 ′, 4,4′-biphenyltetracarbo, sold by Mitsubishi Chemical Corporation under the trade name “BPDA” 183.07 g (0.623 mol) of acid dianhydride (BPDA) was added as a solid and reacted at 40 ° C. for 12 hours to obtain a viscous transparent polyimide precursor solution having a viscosity of 1,000 poise. It was.

(B) Production of transparent polyimide tubular body An aluminum mold having an outer diameter of 30.4 mm and a length of 510 mm was prepared. The mold is polished so that the average surface roughness (Rz) of the outer surface is 1 μm or less, and a silicon oxide coating agent is coated on the surface by a dipping method, 30 minutes at 150 ° C. and 30 minutes at 370 ° C. A mold that was heated and baked and coated with a silicon oxide film was used. Next, the mold is immersed in the transparent polyimide precursor solution of the item (a) up to 400 mm, and after applying the polyimide precursor, a ring-shaped die having an inner diameter of 31.4 mm is inserted from above the mold. Then, it was dropped and traveled by its own weight, and liquid-molded on the surface of the mold. Then, as an imidization treatment, the temperature is raised at 80 ° C. for 45 minutes, 120 ° C. for 45 minutes, 200 ° C. for 30 minutes, 250 ° C. in 45 minutes, 250 ° C. for 30 minutes, 300 ° C. for 20 minutes. A transparent polyimide tubular product was prepared by imidizing for a minute. After cooling, the tubular product separated from the mold is partially swollen due to the effects of the solvent that volatilizes during the imidization process and the vaporized gas of condensed water, even though the film thickness is 75 ± 2 μm. In addition, there were no defects such as uneven thickness and bubbles, and the inner and outer surfaces of the tubular product were smooth and had a high roundness. That is, the light transmittance at wavelengths of 420 nm, 550 nm, and 780 nm of the tubular product film was 71.0%, 85.2%, and 87.1%, respectively, and the water vapor transmittance was 31 g / m ² · 24 hr. The tensile strength and tensile modulus, respectively ^{12.0kgf / mm 2, 339kgf / mm} 2, the glass transition temperature was 310 ° C.

As the diamine component, 152.90 g (0.617 mol) of 44DDS and 3,3′-diamino sold under the trade name “DAS” from Konishi Chemical Industry Co., Ltd. are used so that the concentration of the polyimide precursor solution is 33% by weight. Diphenylsulfone (33DDS) 50.97 g (0.206 mol) and DMAC 1,005 g as a reaction solvent were added. After 44DDS and 33DDS were completely dissolved in DMAC, BPADA 107.93 g (0 208 mol) and 183.07 g (0.623 mol) of BPDA were added as solids and reacted at 40 ° C. for 12 hours to obtain a viscous transparent polyimide precursor solution having a viscosity of 620 poise.
Thereafter, a transparent polyimide tubular product having a coating thickness of 76 ± 3 μm was produced under the same conditions as described in Example 1 (b). The light transmittance at wavelengths of 420 nm, 550 nm, and 780 nm of the tubular material coating was 70.4%, 85.4%, and 86.9%, respectively, and the water vapor transmittance was 28 g / m ² · 24 hr. The tensile strength and tensile modulus, respectively ^{12.6kgf / mm 2, 306kgf / mm} 2, the glass transition temperature was 285 ° C. This tubular product was free from defects such as voids, uneven thickness, and blisters, and had excellent light transmittance and a high glass transition temperature.

44DDS 101.93 g (0.411 mol) and 33DDS 101.93 g (0.411 mol) as diamine components and DMAC 1,005 g as a reaction solvent were added so that the concentration of the polyimide precursor solution was 33 wt%. After 33DDS is completely dissolved in DMAC, 107.93 g (0.208 mol) of BPADA and 183.07 g (0.623 mol) of BPDA are added as a tetracarboxylic dianhydride component as a solid, at 40 ° C. The mixture was reacted for 12 hours to obtain a viscous transparent polyimide precursor solution having a viscosity of 500 poise. Thereafter, a transparent polyimide tubular product having a coating thickness of 78 ± 5 μm was produced under the same conditions as described in Example 1 (b). The light transmittance at wavelengths of 420 nm, 550 nm, and 780 nm of the tubular material coating was 69.8%, 84.1%, and 86.1%, respectively, and the water vapor transmittance was 21 g / m ² · 24 hr. The tensile strength and tensile modulus, respectively ^{14.5kgf / mm 2, 340kgf / mm} 2, the glass transition temperature was 267 ° C. This tubular product was free from defects such as voids, uneven thickness, and blisters, and had excellent light transmittance and a high glass transition temperature.

44DDS 50.97 g (0.206 mol) and 33DDS 152.9 g (0.617 mol) are used as the diamine component, and N, N-dimethylacetamide (DMAC) is used as the reaction solvent so that the concentration of the polyimide precursor solution is 33% by weight. ) 1,005 g was added, and 44DDS and 33DDS were completely dissolved in DMAC. Then, 107.93 g (0.208 mol) of BPADA and 183.07 g (0.623 mol) of BPDA were added as tetracarboxylic dianhydride components. It was added as it was and reacted at 40 ° C. for 12 hours to obtain a viscous transparent polyimide precursor solution having a viscosity of 650 poise. Thereafter, a transparent polyimide tubular product having a coating thickness of 76 ± 4 μm was produced under the same conditions as described in Example 1 (b). The light transmittance at wavelengths of 420 nm, 550 nm, and 780 nm of the tubular material coating was 70.2%, 85.3%, and 87.2%, respectively, and the water vapor transmittance was 20 g / m ² · 24 hr. The tensile strength and tensile modulus, respectively ^{14.8kgf / mm 2, 333kgf / mm} 2, the glass transition temperature was 253 ° C. This tubular product was free from defects such as voids, uneven thickness, and blisters, and had excellent light transmittance and a high glass transition temperature.

(Comparative example)
An aluminum mold having an outer diameter of 30.4 mm and a length of 510 mm was prepared. The mold is polished so that the average surface roughness (Rz) of the outer surface is 1 μm or less, and a silicon oxide coating agent is coated on the surface by a dipping method, 30 minutes at 150 ° C. and 30 minutes at 370 ° C. A mold that was heated and baked and coated with a silicon oxide film was used. Next, the mold was immersed in a polyimide precursor solution (RC5063 PyreML varnish, manufactured by IST) having a concentration of 18% and a viscosity of about 1,500 poises, and the polyimide precursor solution was applied. A 0 mm ring die was inserted from the upper part of the mold and dropped by running under its own weight, and liquid molded on the surface of the mold. Then, as an imidization treatment, the temperature is raised at 80 ° C. for 45 minutes, 120 ° C. for 45 minutes, 200 ° C. for 30 minutes, 250 ° C. in 45 minutes, 250 ° C. for 30 minutes, 300 ° C. for 20 minutes. Partial firing was performed to prepare a polyimide tubular product. The tubular material was separated from the mold and various properties were measured. The tubular product film had a water vapor transmission rate of 1.4 g / m ² · 24 hr. Further, the light transmittances of the tubular product coating at wavelengths of 420 nm, 550 nm and 780 nm were 0%, 56.0% and 79.0%, respectively. The thickness of the tubular film was 79 ± 7 μm. However, voids remained in the film, and the portion where the partial gas accumulation occurred was thinned and an uneven thickness state was observed. .

Claims (6)

A transparent polyimide tubular product comprising a polyimide resin coating, wherein the coating has a water vapor transmission rate of 10 to 50 g / m ² · 24 hr.   2. The transparent polyimide tubular article according to claim 1, wherein the light transmittance of the coating at least at a wavelength of 420 nm is 50% or more when the coating thickness is 50 ± 10 μm.   The transparent polyimide tubular article according to claim 1, wherein the glass transition temperature of the coating is 200 ° C or higher. A polyimide precursor obtained by reacting at least one diamine selected from the following chemical formula (A) or chemical formula (B) or a derivative thereof with at least one tetracarboxylic dianhydride or a derivative thereof in a polar solvent. The transparent polyimide tubular article according to claim 1, which is obtained by imidizing a solution.

The tetracarboxylic dianhydride or a derivative thereof is represented by the following chemical formula (I) or chemical formula (II) (X is —O—, —S—, —SO ₂ —, —CH ₂ —, —CF ₂ —, —C _{(CH 3) 2 -, -} C (CF 3) 2 -, - CO- or transparent polyimide tubular article according to claim 4, characterized in that it consists of at least one compound selected from a direct bond represents a) .

The polyimide precursor solution having a concentration of 10% by weight to 50% by weight on the mold surface is liquid-molded to a predetermined thickness, dried, and then subjected to imide conversion at 400 ° C. or less to produce a transparent polyimide tubular product Method.