JPH0313254B2 - - Google Patents

Description

[Detailed description of the invention]

TECHNICAL FIELD The present invention relates to a method for producing a film or fibrous material made of aromatic polyester. More specifically, a film or fibrous material is formed by melt molding from an aromatic polyester compound containing a highly polymerized aromatic polyester and a melt viscosity reducing agent, and then stretched. The above-mentioned manufacturing method includes a step of removing by extraction. Conventionally, aromatic polyesters, particularly polyethylene terephthalate and polytetramethylene terephthalate, have been used for various purposes such as fibers, films, and injection molded products due to their excellent mechanical properties, chemical resistance, and dimensional stability. There is. Among the physical properties of this polyester, the mechanical properties in particular largely depend on the degree of polymerization, and therefore various methods have been studied and proposed for producing polyester with as high a degree of polymerization as possible. Melt polymerization of polyester is usually a high-temperature condensation reaction, so side reactions (such as thermal decomposition reactions) are likely to occur, and it takes a long time to produce a polymer with a high degree of polymerization. In this case, there are problems such as a decrease in the degree of polymerization. As methods for improving these points, methods using solid phase polymerization, methods using polymerization accelerators (eg, diphenyl carbonate, diphenyl terephthalate, etc.), and the like are well known. However, even if it is attempted to manufacture molded articles by melt molding from the polymer with a high degree of polymerization obtained in this way, it is impossible to manufacture a molded article made of a polymer with a high degree of polymerization while minimizing the decrease in the degree of polymerization. Very difficult. The reason for this is that polymers with a high degree of polymerization have extremely high melt viscosity, and therefore, in order to facilitate melt molding, it is necessary to reduce the melt viscosity by heating to high temperatures. Due to disconnection occurring. Therefore, an object of the present invention is to provide a method for producing a film or fibrous material made of an aromatic polyester with a high degree of polymerization while suppressing the decrease in the degree of polymerization to an extremely low level compared to an aromatic polyester with a high degree of polymerization. It is about providing. Another object of the present invention is to produce a film-like or fibrous material comprising an aromatic polyester having a high degree of polymerization, which exhibits an extremely small decrease in the degree of polymerization at a relatively low molding temperature, and which is made of an aromatic polyester having a sufficiently high degree of polymerization. The purpose is to provide a method for manufacturing. Still another object of the present invention is to provide various properties such as mechanical properties such as strength and elongation, moist heat resistance, etc., which are superior to the above-mentioned products made of corresponding aromatic polyesters with a high degree of polymerization obtained by conventional methods. An object of the present invention is to provide a method for producing a film or fibrous material having the following properties. Yet another object of the present invention is to provide an extremely low oligomer content, for example an oligomer content of about 0.1% by weight.
The object of the present invention is to provide a method for producing a film or fibrous material made of a highly polymerized aromatic polyester as described below. Still another object of the present invention is to provide an extremely thin film, for example 1 μm, made of aromatic polyester with a high degree of polymerization.
(Hereinafter, the unit of length μm is simply abbreviated as μ.) To provide a method for easily producing a film-like material having a thickness of 3 μm or less and an extremely thin fibrous material having a diameter of 3 μm or less, for example. It is in. The objects of the present invention as described above are: a. A highly polymerized aromatic polyester (A) containing an aromatic dicarboxylic acid as the main acid component and an aliphatic diol and/or an alicyclic diol as the main glycol component, and the following ( Compounds selected from a) to (e), which are substantially non-reactive with the aromatic polyester, have a boiling point of about 200°C or more at normal pressure, and have a molecular weight of 1000 or less ( B), (i) an imide compound represented by the following formula (1)-a; Here, A ¹ is a divalent aromatic residue or a chain or cyclic aliphatic residue, which may be substituted; R ¹ is an n-valent aromatic residue or a chain or cyclic aliphatic residue. aliphatic residues, which may be substituted; n is 1 or 2. However, the imide ring in the above formula is 5 or 6 members. (b) An imide compound represented by the following formula (1)-b; Here, A ² is a tetravalent aromatic residue,
This may be substituted; R ² is a monovalent chain or cyclic aliphatic residue, which may be substituted, provided that the imide ring in the above formula is a 5- or 6-membered It is. (c) a trialkyl isocyanurate compound represented by the following formula (1)-c; Here, R ³ is a monovalent alkyl group. (d) A bisphenyl compound represented by the following formula (1)-d; Here, A ³ is -O-, -SO ₂ -, -CO- or an alkylene group, and the phenyl ring in the above formula may be substituted. (e) mononitronaphthalene; and the above-mentioned low molecular weight compound
The blending amount of (B) is 100% of the above aromatic polyester (A)
Forming an unstretched film or fibrous material by melt molding from an aromatic polyester blend in a range of 3 to 300 parts by weight, b. Stretching the film or fibrous material. , c from a stretched film or fibrous material,
The above-mentioned low molecular weight compound is extracted with an organic solvent that can dissolve the compound and does not substantially dissolve the above-mentioned aromatic polyester under extraction conditions. Achieved by the method of manufacturing a product. The method of the present invention is characterized by the combination of steps (1), (2), and (3) above. To explain its characteristics conceptually, for example, polyethylene terephthalate, which has an extremely high degree of polymerization with an intrinsic viscosity of 1 or more, can only be melt-molded at a temperature of 320°C or higher due to constraints on melt viscosity. According to the method of the present invention, even a polymer with a high degree of polymerization can be melt-molded at a low melting temperature of, for example, about 280°C. The first method that can mold a polymer with a high degree of polymerization at such a low melting temperature
The advantage of this is not only that a low melting temperature can be used, which is an advantage in the molding operation, but also that the decrease in the degree of polymerization that occurs during melt molding is kept to an extremely small level, and the resulting molded product also has the same advantage. The purpose is to maintain a high degree of polymerization of the polymer. Therefore, according to the method of the present invention, molded articles made of polymers with a high degree of polymerization can be easily produced,
In addition, since the decrease in the degree of polymerization is small, it is possible to produce a molded article with excellent performance that largely reflects the original characteristics of the polymer with a high degree of polymerization used as a raw material. The second advantage that high polymerization degree polymers can be molded at such a low melting temperature is that even extremely thin films such as 1 μm in diameter or extremely thin fibrous materials with a diameter of 3 μm can be molded using high polymerization degree polymers. It is possible to suppress a decrease in the degree of polymerization due to coalescence and to produce a product stably and with high performance. According to the present invention, such an extremely thin or extremely slender molded article is further removed by an extraction operation to remove the dissolved viscosity reducing agent contained therein, to form an even thinner or narrower film-like product with a thickness of, for example, 0.8 μm. Provided as a product, etc. Surprisingly, the film produced by the method of the invention contains, for example, 50% by weight of melt viscosity reducing agent.
Even those made from aromatic polyester blends containing aromatic polyesters are sufficiently dense that they exhibit moisture permeability that is no different from films made from aromatic polyester alone, regardless of their thickness. ing. The aromatic polyester (A) used in the method of the present invention contains an aromatic dicarboxylic acid as a main acid component and an aliphatic diol and/or an alicyclic diol as a main glycol component. Examples of the aromatic dicarboxylic acids include terephthalic acid, isophthalic acid, naphthalene dicarboxylic acid, diphenyl dicarboxylic acid, diphenylsulfone dicarboxylic acid, diphenoxyethane dicarboxylic acid, diphenyl ether dicarboxylic acid, methyl terephthalic acid, and methyl isophthalic acid. etc. can be given. In addition, examples of the aliphatic diol and/or alicyclic diol as the main glycol component include polymethylene glycols having 2 to 10 carbon atoms such as ethylene glycol, trimethylene glycol, tetramethylene glycol, hexamethylene glycol, decamethylene glycol, etc. , and neopentylene glycol, cyclohexane dimethylol, tricyclodecane dimethylol, 2,2-
Bis(4-β-hydroxyethoxyphenyl)propane, 4,4'-bis(β-hydroxyethoxy)diphenylsulfone, diethylene glycol, or polyoxyethylene glycol, polyoxypropylene glycol, polyoxytrimethylene glycol, poly Oxytetramethylene glycol and two of these oxyalkylene units
Examples include copolymerized polyoxyalkylene glycols having at least one repeating unit. Each of these acid components and glycol components can be used alone or in combination of two or more kinds. Among these, terephthalic acid is preferable as the acid component, and carbon number 2 to 6 is preferable as the glycol component.
Preferred are polymethylene glycols. Examples of the aromatic polyester (A) include polyethylene terephthalate, polytrimethylene terephthalate, polytetramethylene terephthalate, polyethylene 2,6-naphthalene dicarboxylate, poly(ethylene terephthalate/ethylene isophthalate), poly(ethylene terephthalate/neobenchi), etc. lenterephthalate), etc. Among these, polyethylene terephthalate is particularly preferred. The aromatic polyester (A) is, for example, p
-oxyacids such as oxybenzoic acid, succinic acid,
The polymer has substantially linear units derived from fatty acid dicarboxylic acids such as adipic acid, sebacic acid, etc., polyfunctional compounds such as pentaerythritol, trimethylolpropane, trimellitic acid, pyromellitic acid, etc., and monofunctional compounds such as benzoic acid. They may be copolymerized or bonded within a certain range. The above aromatic polyester (A) used in the present invention
has an intrinsic viscosity of preferably 0.6 or more, more preferably 0.7 or more, particularly preferably 0.8 or more. This intrinsic viscosity is measured as a solution of chlorophenol in a solvent at 35°C and is often expressed by the symbol [η]. The aromatic polyester used in the above method of the present invention can be produced by a method known per se, such as a melt polymerization method or a solid phase polymerization method. especially,
Aromatic polyesters with a high degree of polymerization, such as aromatic polyesters with an intrinsic viscosity of about 0.8 or more, can be produced by melt polymerization using various polymerization accelerators [methods using diphenyl carbonate as a polymerization accelerator, methods using diphenyl terephthalate, tetra It can be advantageously produced by a method using phenyl orthocarbonate, a method using a biscyclic imino ester, a method using a biscyclic imino ether] or a solid phase polymerization method. The melt viscosity reducing agent used in the method of the present invention is a specific low molecular weight compound (B ). These low molecular weight compounds have boiling points of approximately
Those having a temperature of 250°C or higher or those having a molecular weight of 800 or less are preferably used. In particular, low molecular weight compounds with a melting point of 100°C or higher have a low degree of raising or lowering the secondary transition point of the aromatic polyester in the mixture obtained by mixing it with the aromatic polyester. It is particularly preferably used in the present invention because it facilitates the operation of molding a molded article. The low molecular weight compound used in the method of the present invention has the following formula (1)-a Here, A ¹ is a divalent aromatic residue or a chain or cyclic aliphatic residue, which may be substituted; R ¹ is an n-valent aromatic residue or a chain or cyclic aliphatic residue. n is 1 or 2, provided that the imide ring in the above formula is 5 or 6 members. An imide compound represented by the following formula ( 1)-b Here, A ² is a tetravalent aromatic residue, which may be substituted; R ² is a monovalent chain or cyclic aliphatic residue, which may be substituted. Good, provided that the imide rings in the above formula are 5 or 6 members, an imide compound represented by the following formula (1)-c Here, R ³ is a monovalent alkyl group, trialkylisocyanurate represented by the following formula (1)-d Here, A ³ is -O-, -SO ₂ -, -CO- or an alkylene group, and the phenyl ring in the above formula may be substituted. Use a bisphenyl compound represented by the following, mononitronaphthalene. Can be done. As the compound of the above formula (1)-a, the above formula (1)-a
At least one of A ¹ or R ¹ is an aromatic residue (these may be nuclear substituted)
Compounds in which A ¹ is a divalent aromatic residue (which may be nuclear-substituted) are preferably used. In addition, as the compound of the above formula (1)-b, the above formula
In (1)-b, a compound in which R ² is a monovalent aliphatic residue (these may be nuclear-substituted) is preferably used. Among the above low molecular weight compounds, the above formula (1)-a or
Imide compounds represented by (1)-b are particularly preferably used in the present invention. In the above general formula (1)-a, the divalent aromatic residue representing A ¹ is, for example, a 1,2-phenylene group, a 1,2-, 2,3- or 1,8-naphthylene group, a 5 ,6,7,8-tetrahydro-1,
Mention may be made of 2- or 2,3-naphthylene groups, and examples of divalent aliphatic residues include linear alkylene groups such as ethylene or trimethylene, or 1,2-cyclohexylene groups, 1,2,3, 4
Mention may be made of cyclic alkylene groups such as -tetrahydro-1,2- or 2,3-naphthylene groups. These groups may be substituted with a substituent that is non-reactive with respect to aromatic polyester. Examples of such substituents include lower alkyl groups such as methyl and ethyl, lower alkoxy groups such as methoxy and ethoxy, halogen atoms such as chlorine and bromine, nitro groups, phenyl groups, phenoxy groups, and methyl groups. Good examples include cyclohexyl. Examples of the n-valent (n=1 or 2) aromatic residue representing R ¹ include phenyl group, naphthyl group,
5,6,7,8-tetrahydro-1-,2- or 3-naphthyl group or formula, (where Z is -O-, -SO ₂ - or -CH ₂ -), or 1,2
-phenylene group, 1,2-, 2,3- or 1,8
-naphthylene group or 5,6,7,8-tetrahydro-1,2- or 2,3-naphthylene group, or the formula, (where Z is -O-, -SO ₂ - or -CH ₂ -), and n-valent (n = 1 or 2) aliphatic residues. Examples of the residue include those having 1 to 1 carbon atoms, such as methyl, ethyl, butyl, hexyl, hebutyl, octyl, nonyl, decyl, dodecyl, myricityl, and stearyl.
18 linear alkyl groups or 5- or 6-membered cyclic alkyl groups such as cyclohexyl or cyclobentyl, or linear alkyl groups having 2 to 12 carbon atoms such as ethylene, trimethylene, tetramethylene, hexamethylene, octamethylene, decamethylene, dodecamethylene. alkylene group, cyclic alkylene group such as 1,3- or 1,4-cyclohexylene group, or

Mention may be made of the group of the formula. These groups representing R ¹ may be substituted with the same substituents as described for A ¹ . In the above formula (1)-b, the tetravalent aromatic residue representing A ² is, for example,

【formula】

【formula】

【formula】

[Formula] or

Preferred examples include monocyclic, condensed ring, or polycyclic tetravalent aromatic residues represented by the formula: (Z is the same as defined above). The monovalent chain or cyclic aliphatic residue representing R ² is the same chain alkyl group having 1 to 18 carbon atoms as exemplified for R ¹ in formula (1)-a above, or a 5- or 6-membered alkyl group. Examples include a membered cyclic alkyl group. The groups exemplified for A ² and R ² above may be substituted with the same substituents as described for A ¹ . Examples of the monovalent alkyl group representing R ³ in the above formula (1)-c include chain alkyl groups having 1 to 10 carbon atoms such as methyl, ethyl, propyl, butyl, hexyl, octyl, and decyl. can. In the above formula (1)-d, examples of the alkylene group representing A ³ include a chain alkylene group having 2 to 4 carbon atoms such as ethylene, trimethylene or tetramethylene. The phenyl group of formula (1)-d may be substituted with the same substituents as described for ^A1 . Examples of the imide compound represented by the above formula (1)-a include N-methylphthalimide, N-ethylphthalimide, N-octylphthalimide, N-
Lauryl phthalimide, N-myristyl phthalimide, N-cetylphthalimide, N-stearylphthalimide, N-ethyl-1,8-naphthalimide, N-lauryl-1,8-naphthalimide, N-myricetyl-1,8- Naphthalimide, N-cetyl-1,8-naphthalimide N-
Stearyl-1,8-naphthalimide; formula (1)-
N as a compound when n=2 in a,
N'-ethylene bisphthalimide, N,N'-tetramethylene bisphthalimide, N,N'-hexamethylene bisphthalimide, N,N'-octamethylene bisphthalimide, N,N'-decamethylene Bisphthalimide, N,N'-dodecamethylene bisphthalimide, N,N'-neobenbenzene bisphthalimide, N,N'-tetramethylenebis(1,8-naphthalimide), N,
N'-hexamethylenebis(1,8-naphthalimide), N,N'-octamethylenebis(1,8
-naphthalimide), N,N'-decamethylenebis(1,8-naphthalimide), N,N'-dodecamethylenebis(1,8-naphthalimide),
N,N'-dodecamethylene bissuccinimide,
N,N'-dodecamethylene bishexahydrophthalimide, N,N'-1,4-cyclohexylene bisphthalimide, 1-phthalimide-3
-phthalimidomethyl-3,5,5-trimethylcyclohexane, N,N'-2,2,4-trimethylhexamethylene bisphthalimide, N,
N'-2,2,4-trimethylhexamethylenebisphthalimide, N,N'-2,4,4-trimethylhexamethylenebisphthalimide, 4,
4′-bisphthalimide diphenyl ether,
3,4'-bisphthalimidophenyl ether,
Examples include 3,3'-bisphthalimido diphenyl sulfone, 4,4'-bisphthalimido diphenyl sulfone, and 4,4'-bisphthalimido diphenyl methane. Examples of the imide compound represented by the above formula (1)-b include N,N'-diethylpyromellitimide, N,N'-dibutylpyromellitimide, N,
N'-dihexylpyromellituimide, N,N'-
Dioctylpyromellituimide, N,N'-didecylpyromellituimide, N,N'-dilaurylpyromellituimide, N,N'-dicyclohexylpyromellituimide, N,N'-diethyl-1,
4,5,8-naphthalenetetracarboxylic acid 1,8
-,4,5-diimide and the like can be mentioned. The imide compound represented by the above formula (1)-a can be produced from a corresponding acid anhydride and an organic amine by a known method. The imide compound represented by the above formula (1)-a is used as a dyeability improving agent for modified polyester (see Japanese Patent Publication No. 44-9677) or as a crystallization accelerator for injection molding materials for polyethylene terephthalate (see Japanese Patent Publication No. 44-9677). Kaisho 56
(Refer to Publication No. 84747) Some are known. Examples of the compound represented by the above formula (1)-c include triethyl isocyanurate, tributyl isocyanurate, trihexyl isocyanurate, and trioctyl isocyanurate. Examples of the compound represented by the above formula (1)-d include diphenyl ether, diphenyl sulfone,
Examples include benzophenone, diphenylmethane, 1,2-diphenylethane, and 1,4-diphenylbutane. Furthermore, examples of mononitronaphthalene include α-nitronaphthalene. In the method of the present invention, an unstretched film or fibrous material is melt-molded from an aromatic polyester blend containing the aromatic polyester (A) with a high degree of polymerization and the low molecular weight compound (B) as described above. The first step is to form the object. According to the method of the present invention, the aromatic polyester blend contains 3 to 300 parts by weight, preferably 5 to 200 parts by weight, more preferably 10 to 150 parts by weight of the low molecular weight compound per 100 parts by weight of the aromatic polyester.
Contains parts by weight. The above-mentioned aromatic polyester compound can be prepared, for example, by melt-mixing a high molecular weight aromatic polyester (A) and a low molecular weight compound (B) in a predetermined ratio (first method), or in the presence of a low molecular weight compound (B). Either a polycondensation reaction is carried out to obtain a melt containing a high molecular weight aromatic polyester (A) and a low molecular weight compound (B) in a predetermined amount (second method), or the aromatic polyester is prepared under normal pressure or A polymerization accelerator (chain extender) capable of reacting with the end groups of the aromatic polyester under pressure is melt-reacted in the presence of the low molecular weight compound (B) to form a high molecular weight aromatic polyester (A) and a low molecular weight aromatic polyester. It can be produced by any method of obtaining a melt containing a predetermined amount of the molecular weight compound (B) (third method). According to the first method, predetermined amounts of a preferably sufficiently dried high molecular weight aromatic polyester and a low molecular weight compound are preferably first dry blended and then melt mixed in a melt extruder. At this time, when the amount of the low molecular weight compound used is relatively large, for example, when the low molecular weight compound is used in an amount of about 50 parts by weight or more per 100 parts by weight of the aromatic polyester, the low molecular weight compound is melted in the dry blended mixture. However, the recommended procedure is to apply a temperature that does not melt the aromatic polyester, then cool it, further crush it, and then feed it to a melt extruder and melt-mix it. The second method is that the low molecular weight compound used in the method of the present invention is substantially non-reactive with aromatic polyester and has a relatively high boiling point (boiling point at normal pressure of about 200°C or higher). It is understood that implementation becomes possible. Therefore, in this second method, a low molecular weight compound can be added to the polymerization reaction system at any stage of the polycondensation reaction, but this second method still adds a low molecular weight compound with a relatively low boiling point. When using this second method, the molecular weight of the compound is easily removed from the polymerization reaction system.
It is recommended to use low molecular weight compounds of 440 or higher. The biggest advantage of this second method is that, as can be understood from the above, the low molecular weight compounds present in the polymerization reaction system are In order to provide a polymerization reaction system with a melt viscosity lower than the melt viscosity, this combined with the effect that glycol etc. produced by the polycondensation reaction can be easily removed from the reaction system results in an aroma with a high degree of polymerization at a relatively low temperature. The advantage is that the group polyester can be easily produced. Therefore, according to this second method, the aromatic polyester obtained contains a predetermined amount of low molecular weight compounds and thus provides an aromatic polyester formulation which can be used as is in the method of the invention. The third method uses an aromatic polyester, such as a relatively low molecular weight aromatic polyester that can be relatively easily produced by a melt polymerization method, and passes it through a melt extruder. It is advantageous to be able to produce aromatic polyester blends used in the invention consisting of A) and low molecular weight compounds (B). That is, in the third method, (a) an aromatic polyester having a carboxyl group at the terminal, preferably an aromatic polyester having an intrinsic viscosity of about 0.5 to about 0.6, and the following formula (2): Here, X ¹ and X ² are the same or different,
It has 2 or 3 ring carbon atoms forming an iminoether ring. is a divalent hydrocarbon group that is unreactive under the reaction conditions; D is a divalent hydrocarbon group that is unreactive under the reaction conditions and may contain a heteroatom;
hydrocarbon group or formula

[Formula] (where D' may contain a heteroatom. R ⁴ and R ⁵ are the same or different and are hydrogen atoms or monovalent hydrocarbon groups that are unreactive under the reaction conditions. is a hydrocarbon group, or R ⁴ and R ⁵ may be bonded to each other to form a 5- or 6-membered ring with two nitrogen atoms and D';
is 0 or 1, a biscyclic imino ether compound represented by
A melt reaction is performed in the presence of a low molecular weight compound having a molecular weight of 1000 or less and which is substantially non-reactive with the aromatic polyester and the bis-cyclic imino ether compound and has a boiling point of about 200° C. or more at normal pressure and a molecular weight of 1000 or less, or (b) an aromatic polyester having a terminal hydroxyl group, preferably an aromatic polyester having an intrinsic viscosity of about 0.5 to about 0.6, and the following formula (3)-a Here, Y is a divalent hydrocarbon group which may contain a heteroatom; X ³ has one or two ring member carbon atoms forming the iminoester ring. A divalent hydrocarbon group that is non-reactive under the reaction conditions; l is 0 or 1; or the following formula (3)-b Here, A ⁴ is the following formula (h) Here, R ⁸ is a monovalent hydrocarbon group, or the following formula (i) Here, the definition of R ⁸ is the same as above, it is a group represented by the following, R ⁷ is a tetravalent aromatic group which may contain a hetero atom, and R ⁶
is a monovalent hydrocarbon group that is the same as or different from ^R8 , and a biscyclic iminoester compound represented by
The above aromatic polyester and the above biscyclic iminoester compound are subjected to a melt reaction in the presence of a low molecular weight compound having a molecular weight of 1000 or less and having a boiling point of about 200°C or higher and a boiling point of about 200°C or higher at normal pressure, or It is carried out by either procedure. The bis-cyclic imino ether compound and bis-cyclic imino ether compound used in the procedure (a) above are reacted with an aromatic polyester having a terminal carboxyl group at normal pressure to pressurization to give a high molecular weight aromatic polyester. It is disclosed in the specification of European Patent Publication No. 0020944 filed by the present inventors. Further, the bis-cyclic imino ester compound and the bis-cyclic imino ester compound used in the step (b) above are reacted with an aromatic polyester having a terminal hydroxyl group at normal pressure to pressurization to give a high molecular weight aromatic polyester. is also disclosed in European Patent Publication No. 0019061 filed by the present inventors. The only difference between the above procedures (a) and (b) is that the bis-cyclic imino ether or bis-cyclic imino ester described in the above specification is used and the melt reaction is carried out in the presence of a low molecular weight compound. It can be operated exactly as described in the book. Therefore, the disclosures of the above-mentioned patents are herein incorporated by reference. Similarly to the second method, the third method has the advantage that aromatic polyester with a high degree of polymerization can be easily produced at a relatively low temperature. Aromatic polyester formulations containing low molecular weight compounds are provided. According to the method of the present invention, the aromatic polyester blend produced as described above is first melt-molded and converted into an unstretched film or fibrous material. The melt-forming process can be carried out using equipment known per se in the art and under conditions well known per se. However, according to the method of the present invention, melt molding can be performed at a temperature lower than the known molding temperature conditions for polymers having the same degree of polymerization, which is an excellent feature and advantage of the method of the present invention. As already described in detail. These advantages will become clearer from the examples described below. Although it varies depending on the type or content of the low molecular weight compound contained, for example, the aromatic polyester used in the present invention containing high polymerization degree polyethylene terephthalate with an intrinsic viscosity of 1.0 usually has a viscosity of about 270 It can be easily formed into a film or fiber at a temperature of ~290°C. As can be understood from the above-mentioned method for producing an aromatic polyester blend, the melt of the aromatic polyester blend to be subjected to melt molding in the method of the present invention can be obtained by any of the first to third methods described above. The melt itself obtained by the method described above can be used. This applies, for example, to the first method or the third method.
This means that a slit or nozzle for the above-mentioned melt molding is connected to the melt extruder in the method (1) or the polymerization reactor in the second method. Thus, according to the above-mentioned molding according to the method of the present invention, a thickness of about 5 mm, which is suitable for stretching and extraction as described later, can be obtained.
Unstretched film of less than mm or approximately 3 mm in diameter
The following undrawn fibrous materials can be produced. According to the method of the present invention, the unstretched film and fibrous products thus produced are then stretched and optionally further heat-set. Stretching is carried out in a manner known per se uniaxially (fibers or films) or biaxially (films) simultaneously or sequentially. Assuming that the heat distortion temperature of the aromatic polyester compound used is Tg (°C), the stretching temperature (T ₁ , °C) for uniaxial stretching and simultaneous biaxial stretching is more preferably expressed by the following formula: Tg−10≦T ₁ ≦Tg+30 The range satisfies the following formula: Tg-5≦T ₁ ≦Tg+20. In addition, in the case of final biaxial stretching, the first stage stretching temperature is a temperature (T ₁ , °C) that satisfies the above formula,
The second stage stretching temperature (T ₂ , °C) is set in a range that satisfies the following formula: T ₁ +5≦T ₂ ≦T ₁ +50, more preferably T ₁ +10≦T ₂ ≦T ₁ +40. The stretching ratio is usually about 3 to 6 times for fibrous materials, and the area ratio for film materials is usually about 3 to 6 times.
It is about 30 times larger. According to the method of the present invention, since the aromatic polyester blend used contains the above-mentioned low molecular weight compound, the melt viscosity of the aromatic polyester blend is higher than the melt viscosity of the aromatic polyester contained in the blend. low molecular weight and therefore make it possible to produce very fine fibers or very thin films even from formulations containing high molecular weight aromatic polyesters. For example, drawn films with a thickness of about 1 micron or drawn fibers with a diameter of about 3 microns can be produced from formulations containing high molecular weight aromatic polyesters with an intrinsic viscosity of 1.0. According to the research of the present inventors, when the thickness of a stretched film-like material is made thinner than about 2 μm, it is necessary to use a film made of, for example, aromatic polyester or polypropylene, which can be fully stretched under the stretching conditions. It has become clear from the viewpoint of the stretching operation that it is desirable to superimpose an unstretched film produced from an aromatic polyester compound according to the method of the present invention on a stretched film and stretch the film together in the superimposed state. . The films obtained by stretching are relatively strongly bonded when stacked, but they easily separate after being subjected to extraction, which will be explained later. Therefore, a very thin aromatic polyester film was can be obtained easily. The thus obtained stretched film or fibrous material is then optionally heat-set and then subjected to extraction with an organic solvent. Heat fixation is carried out under tension. The heat setting temperature (Ts, °C) of the material subjected to uniaxial stretching and simultaneous biaxial stretching is as follows, where the stretching temperature is T ₁ (°C) and the melting point of the aromatic polyester compound used is Tm (°C). This is a range that satisfies the formula T ₁ +5≦Ts≦Tm−10. Further, in the case of a film subjected to sequential biaxial stretching, the second stage stretching temperature is T ₂ (° C.), which satisfies the following formula T ₂ +5≦Ts≦Tm−10. Heat fixation can usually be carried out for 1 second to 10 minutes. Extraction with an organic solvent is performed using an organic solvent that does not substantially dissolve the aromatic polyester used under the extraction conditions, preferably also at room temperature (ambient temperature).
This is carried out using an organic solvent that is liquid and has a boiling point lower than about 200° C. at normal pressure. Such an organic solvent may have, for example, a carbon number of 6 to 9.
aromatic hydrocarbon, halogenated aliphatic hydrocarbon having 1 or 2 carbon atoms, aliphatic ketone or aliphatic ester having 3 to 6 carbon atoms, 5- or 6-membered cyclic ether, or aliphatic having 1 to 3 carbon atoms Alcohol is preferably used. Specifically, aromatic hydrocarbons having 6 to 9 carbon atoms such as benzene, toluene, ethylbenzene, xylene, cumene, and pseudocumene; halogenated aliphatic hydrocarbons having 1 or 2 carbon atoms such as methylene chloride, chloroform, and dichloroethane; ; Aliphatic ketones having 3 to 6 carbon atoms such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; 3 to 6 carbon atoms such as methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, and propyl propionate.
5- or 6-membered cyclic ethers such as tetrahydrofuran and dioxane; or aliphatic alcohols having 1 to 3 carbon atoms such as methanol, ethanol, and propanol. Among these, aromatic hydrocarbons having 6 to 9 carbon atoms, halogenated hydrocarbons having 1 or 2 carbon atoms, or 5
Particularly preferably used are 6-membered or 6-membered cyclic ethers. Extraction with organic solvents is advantageously carried out on film-like materials with a thickness of about 1 mm or less, preferably from about 1 .mu.m to about 500 .mu.m, or on fibrous materials with a diameter of about 1 mm or less, preferably from about 3 to about 400 .mu.m. Extraction with organic solvents is preferably carried out under tension and can be carried out at temperatures between ambient temperature and the boiling point of the organic solvent used. The optimal extraction time required for extraction depends on the organic solvent used, the thickness or diameter of the film-like material or fibrous material subjected to extraction, the amount of low molecular weight compounds contained in the film-like material or fibrous material, and the extraction temperature. It varies depending on etc. Generally speaking, for example, the thinner the film-like material, the smaller the diameter of the fibrous material, or the higher the extraction temperature, the shorter the optimum time required for extraction. According to the present invention, the extraction can be completed in about a few seconds to about an hour in most cases, and the low molecular weight compounds thus contained are about 70% by weight or more, preferably about 80% by weight or more, especially about 90% by weight. It is possible to obtain a film-like material or a fibrous material in which % or more is extracted. Extraction with an organic solvent can be carried out by passing a moving film or fibrous material through an organic solvent, or by immersing a stationary film or fibrous material in an organic solvent. You can also do it. In either case, the organic solvent may be fluid or stationary, but it is desirable that at least one of the film (or fibrous material) or the organic solvent is fluid. It goes without saying that the amount of organic solvent used for extraction must be at least enough to dissolve all of the low molecular weight compounds to be extracted, but it is necessary to It is at least about 15 times the weight, preferably about 15 times the weight or more. The extracted film or fibrous material is dried or heat-fixed if necessary. Heat setting is carried out under the same conditions as above. Drying can also serve as heat fixing. Thus, according to the method of the present invention, a film-like product of an aromatic polyester that is substantially free of the above-mentioned low-molecular-weight compound or contains at most 1 part by weight of the above-mentioned low-molecular-weight compound per 100 parts by weight of the aromatic polyester. Alternatively, a fibrous material can be produced. The film or fibrous material obtained by the method of the present invention is produced from an aromatic polyester compound that contains a very large amount of low molecular weight compounds despite being subjected to the extraction treatment as described above. Surprisingly, no holes were observed on both sides of the film. This was proven by the fact that the film obtained by the method of the present invention showed almost the same gas permeability and moisture permeability as those obtained from the corresponding aromatic polyester alone (see below). (see Examples). According to the research of the present inventor, the thickness (d ₁ , μ) of the film-like material obtained by the method of the present invention is equal to the thickness (d ₂ , μ) of the stretched film-like material before being subjected to extraction. ) and the content of low molecular weight compounds in the aromatic polyester formulation used (x, wt%)
According to the following formula d ₁ d ₂ (100−α・x)/100, where d ₁ , d ₂ and x are defined as above, α is the extraction rate of low molecular weight compounds, and the following Formula α = Amount of low molecular weight compounds extracted/Amount of low molecular weight compounds before extraction, usually about 0.7 to about 1, often about 0.9
It has been shown that it can be approximately calculated by taking a value of ~1. According to the above formula, for example, after extraction from a 6.4μ thick film containing 50% by weight of low molecular weight compounds (before extraction), the residual rate of low molecular weight compounds is 1% by weight (α = 99%). ), it can be seen that a film-like material with a thickness of about 3.2μ is produced. The film or fibrous material obtained by the method of the invention also has an extremely low oligomer content.
This, together with the fact that the film or fibrous material is made of high molecular weight aromatic polyester, contributes to further improving the performance of these film or fibrous materials. It can be inferred that. The film or fibrous material obtained by the method of the present invention has various properties that are superior to the film or fibrous material obtained by the conventional method from the corresponding aromatic polyester with a high degree of polymerization, such as strength and elongation. Because it has high mechanical properties or moisture and heat resistance, it is extremely suitable for use in various fields where such properties are required, such as various industrial materials such as rubber reinforcing materials, magnetic tape, insulating films, etc. Can be done. Hereinafter, the method of the present invention will be explained in more detail with reference to Examples. In the examples, all parts mean parts by weight. Further, throughout this specification, various physical property values were measured by the following methods. (1) Intrinsic viscosity ([η]) Measured at 35°C at a concentration of 1.2 g/dl in o-chlorophenol. (2) Terminal carboxyl group ([-COOH]) and terminal hydroxyl group ([-OH]) Measured according to the method of A. Conix (Makromol. Chem. 26 226 (1958)). (3) Heat deformation temperature (Tg) of aromatic polyester compound An amorphous test thin film with a thickness of 500 μ, a width of 1 cm, and a length of approximately 6 cm was melt-molded, and was placed between two fulcrums with a spacing of 3 cm (the width of the fulcrum is Place it on a support stand with 2 cm).
Furthermore, a weight weighing 10 g was placed on top of the test thin set in this manner and approximately at the center of the two supporting points, and the weight was submerged in the water bath, and then the temperature of the water bath was increased at a rate of approximately 4°C/min. Make sure that the center of the test strip with the weight placed on it is 1 cm from the top of the fulcrum.
The temperature at the time of falling was measured and defined as the above heat distortion temperature. (4) Melting point (Tm) of aromatic polyester blend Measure the melting point using a micro melting point measuring device at a heating rate of 10°C/min. On the other hand, a differential thermal chart is determined using a differential thermal measuring device (DSC) at a heating rate of 10°C/min. Among the endothermic peaks of the differential thermal chart, the temperature of the peak showing the temperature closest to the melting point measured using the micro melting point measuring device was defined as the melting point (Tm) of the aromatic polyester blend. (5) Extraction rate of low molecular weight compounds (%) Calculated as an approximate value from the difference in weight of the residue before and after extraction. (6) Oligomer content (%) Cross-linked polystyrene (G2000H8, G3000H8, G4000H8,
G5000H6 (manufactured by Toyo Soda)), the sample was dissolved in hexafluoroisopropanol, and measurement was performed at 30°C using chloroform as a developing solvent. (7) Strength and elongation and Young's modulus using an Instron measuring machine at a tensile rate of 100
Measured in %/min. (8) Moisture permeability of film Put 15 g of phosphorus pentoxide into a cylindrical glass bottle with a height of about 6 cm and a bottom part with a cross-sectional area of about 4 cm ² , seal the bottom part with a sample film, and set the bottle at a temperature of about 15°C. The water permeability of the sample film was calculated from the weight increase due to water absorption by phosphorus pentoxide after being left in an atmosphere with a relative humidity of approximately 50%. (9) Film thickness Electronic Micrometer (Anietsu K-
351). Examples 1 to 4 and Comparative Examples 1 and 2 After drying polyethylene terephthalate chips with an intrinsic viscosity of 1.03, 100 parts of the chips were dry-blended with a predetermined amount of the imide compound shown in Table 1 below,
Melt and mix at approximately 280℃ using a twin-screw ruder, and
It was extruded through a die to obtain an unstretched film with a thickness of about 200 μm. Next, the unstretched film was simultaneously biaxially stretched by a factor of 3.8 in both the length and width at the temperature shown in Table 1 below.
Heat treated at 180℃ for 2 minutes for a fixed length, then the following table 1
Using the organic solvent shown in , extraction treatment was carried out for 10 minutes at a constant length at the reflux temperature of the organic solvent. Then at 150℃
After drying for 15 minutes, it was heat-treated at 220°C for 2 minutes to obtain a stretched film. The physical properties of this stretched film are shown in Table 1 below. For comparison, film formation was attempted under the same conditions as above without adding an imide compound, but due to the high viscosity, T
It could not be extruded from the die (Comparative Example 1). Therefore, when the film was formed by increasing the temperature to 320°C, the intrinsic viscosity of the resulting unstretched film decreased to 0.77.
This unstretched film was biaxially stretched under the same conditions as above. The results obtained for this biaxially stretched film are also shown in Table 1 below as Comparative Example 2.

[Table] In addition, the film obtained in Example 2 was subjected to gel permeation chromatography (GPC).
The oligomer content was determined from the peak area ratio and was 0.1% by weight. On the other hand, the biaxially stretched film obtained in Comparative Example 2 was extracted under the same conditions as in Example 2, and the amount of oligomer was determined to be 1.2%. Examples 5, 6 and 7 After drying 100 parts of polyethylene terephthalate chips ([-COOH] = 36 eq/10 ⁶ g) with an intrinsic viscosity of 0.86, 0.3 of 2,2'-bis(2-oxazoline) as a chain extender was added. The mixture was dry-blended with a predetermined amount of an imide compound shown in Table 2 below, melt-mixed at about 280° C. using a twin-screw extruder, and extruded from a T-die to obtain an unstretched film with a thickness of about 100 μm. Next, the unstretched film was simultaneously biaxially stretched by 3.6 times in the longitudinal and lateral directions at the temperature shown in Table 2 below, and then immersed in xylene under reflux conditions for 15 minutes at a constant length. The film was then dried at 150°C for 15 minutes and then heat treated at 230°C for 2 minutes at a constant length. The physical properties of the obtained stretched film are shown in Table 2 below. Table 2 also shows a film produced using polyethylene terephthalate with an intrinsic viscosity of 0.68 without using an imide compound or a chain extender (Comparative Example 3).

[Table] Example 8 Polyethylene terephthalate with intrinsic viscosity 0.88
100 parts of 1-phthalimido-3-phthalimidomethyl-3,5,5-trimethylolcyclohexane were dry-blended, then melt-mixed at 260°C using a Ruder, and extruded and spun through a spinneret with a diameter of 0.5 mmφ. . The obtained fiber was stretched 6.0 times at 80°C, and then heat-treated at 160°C under 5% stretching.
Next, it was immersed in chloroform under reflux conditions for 30 seconds, and further dried at 150°C for a fixed length. By this chloroform immersion treatment, 96% of 1-phthalimide
3-phthalimidomethyl-3,5,5-trimethylcyclohexane was extracted. The intrinsic viscosity of the obtained fiber is 0.80 and the strength is
8.1g/de, elongation is 12.7%, Young's modulus is 174g/de
It was hot. Example 9 100 parts of polyethylene terephthalate chips with an intrinsic viscosity of 0.90 and 15 parts of diphenyl sulfone were dry blended, and then the mixture was heated using an extruder.
The mixture was melt-mixed at 285°C and extruded and spun using a spinneret with a diameter of 0.5 mmφ. The obtained undrawn yarn was heated to 5.5 at 60°C.
The film was stretched twice, extracted by immersion in refluxing chloroform for about 1 minute, and then dried at 100°C for about 10 minutes. When further stretched 1.1 times at 100℃, the intrinsic viscosity
0.86, strength 8.3 g/de, and elongation 12%. Example 10 100 parts of polyethylene terephthalate chips with an intrinsic viscosity of 0.90 were dry blended with 30 parts of α-nitronaphthalene, and the mixture was heated to 260°C using an extruder.
The mixture was melt-mixed at °C and extruded and spun through a spinneret with a diameter of 0.5 mm to obtain a monofilament. At this time, the melt viscosity was approximately 1000 boids. The obtained unstretched monofilament was stretched 5.0 times at 50°C, immersed in refluxing chloroform for about 1 minute, dried at 100°C for about 10 minutes, and further stretched 1.1 times at 160°C. The obtained drawn yarn has an intrinsic viscosity of 0.85, a strength of 8.6 g/de, and an elongation.
It was 10.6%. Examples 11 to 14 and Comparative Example 4 (1) 194 parts of dimethyl terephthalate, 128 parts of ethylene glycol, and 0.06 parts of calcium acetate were charged into a reaction vessel, and the methanol produced was distilled off while stirring at a temperature of 150 to 220°C. The transesterification reaction was carried out until the exchange rate reached 95%.
Next, 0.06 part of trimethyl phosphate, 0.10 part of antimony trioxide, and a predetermined amount of the imide compound shown in Table 3 were added, the temperature was raised to 280°C, the reaction was carried out for 20 minutes under normal pressure in a nitrogen stream, and then the The polycondensation reaction was carried out under vacuum for 15 minutes and further under high vacuum of about 0.5 mmHg for about 5 hours. Table 3 shows the melt viscosity of the polymer determined from the torque during stirring, and the intrinsic viscosity and intrinsic viscosity of the polymer after the obtained polymer was chipped and the chips were immersed in refluxing xylene for 2 hours to extract the imide compound. Table 3 shows the melting points of the polymers before and after extraction. For comparison, Table 3 also shows a case in which polymerization was carried out in the same manner as above without using any imide compound (Comparative Example 4).

[Table] * Stirring became impossible after about 2 hours under high vacuum, and the reaction was thereafter carried out without stirring.
These results show that when an imide compound is added to the polymerization reaction system and polymerization is performed, the melt viscosity in the polymerization system is lower than that of the normal method (Comparative Example 1), and a polyester with a high degree of polymerization that is not normally obtained can be obtained. It can be seen that the imide compound can be easily extracted by the extraction process. (2) Polyethylene terephthalate chips containing the imide compounds obtained in Examples 11 to 14,
After drying at 120° C. for about 10 hours, it was melt-extruded from a T-die using an extruder at the temperature shown in Table 4 to obtain a raw film with a thickness of about 200 μm. The raw film was simultaneously biaxially stretched by 3.8 times in the longitudinal and transverse directions at a predetermined stretching temperature, and then stretched under a fixed length by 180 mm.
After heat treatment at ℃ for 2 minutes, immersion in refluxing xylene for about 5 minutes, drying at 150℃ for about 10 minutes, and further heating at 220℃ for 2 minutes.
Heat treated for minutes. Table 4 shows the physical properties of the obtained film.

[Table] Examples 15 to 18 100 parts of polyethylene terephthalate chips with an intrinsic viscosity of 1.15 were dry-friended with the specified amount of the imide compound shown in Table 5, and the conditions were that the polymer temperature was about 275°C and the average residence time was about 10 minutes using an extruder. Below, a film was formed by melt extrusion using a T-die to obtain a raw film with a thickness of about 30 μm. Next, the raw film was simultaneously biaxially stretched 3.5 times x 3.5 times at a temperature of 90°C to a thickness of approx.
A stretched film of 2.4μ was obtained. The stretched film was immersed in xylene at a fixed length for 5 minutes to extract the imide compound, and then dried and heat-treated at 180° C. for 10 minutes.
Table 5 shows the amount of imide compound extracted and the intrinsic viscosity, thickness, and physical properties of the film.

[Table] Example 19 1-phthalimido-3-phthalimidomethyl-
3,5,5-trimethylcyclohexane (melting point
213°C) was melted at 240°C in a nitrogen stream and heated to 150°C. The intrinsic viscosity was 1.15, [COOH] =
11 eq/10 ⁶ g of polyethylene terephthalate chips were thoroughly mixed and then kept at 150° C. for 1 hour to solidify the imide compound, which was then ground to obtain polyethylene terephthalate chips with the imide compound adhered to the surface. The chips were heated to 150℃.
After drying for 16 hours, 0.15% of 2,2'-bis(2-oxazoline) was added as a chain extender to 100 parts by weight of the chips.
and 0.25 parts of 2,2'-bis(3,1-benzoxazin-4-one) were mixed, and this was heated to T using a twin-screw extruder at a polymer temperature of 275°C and an average residence time of about 8 minutes. Intrinsic viscosity extruded from a die
1.03, an original film with a thickness of about 25μ was obtained. The film was simultaneously biaxially stretched at a temperature of 90°C at a magnification of 3.8 times x 3.8 times to obtain a stretched film with a thickness of 1.7 μm. Next, the stretched film was heat treated at 180°C for 2 minutes under a fixed length,
Subsequently, 99.4% of the above imide compound was extracted by treatment in refluxing xylene for 1 minute, and then further treated at 150°C for 10 minutes.
Dry for a minute. The thickness of the obtained film is 0.8μ
Strength: 28.7Kg/ ^mm2 , elongation: 80%, Young's modulus: 510
It had physical properties of Kg/mm. Furthermore, when GPC analysis was performed, no oligomers could be detected at all. Examples 20 to 23 and Comparative Example 5 To 100 parts of polyethylene terephthalate having an intrinsic viscosity of 0.93 and a terminal hydroxyl group content of 40 equivalents, a predetermined amount of the low molecular compound shown in Table 6 and 2,2'-bis(3,
1-benzoxazin-4-one) was dry-blended and heated to T using a twin-screw extruder at a polymer setting temperature of 280°C and an average residence time of about 7 minutes.
It was melt-extruded through a die to obtain an unstretched film with a thickness of about 100 μm. The film is heated vertically and horizontally at a specified temperature by 3.6
The film was simultaneously biaxially stretched twice, heat treated at 210°C for 2 minutes under constant length, extracted in refluxing toluene for 5 minutes, and then dried at 150°C for 15 minutes. Table 6 shows the physical properties of the obtained film.

[Table] Examples 24, 25 and 26 Intrinsic viscosity 1.08, terminal carboxyl group amount 37eq/
100 parts of polytetramethylene terephthalate chips (10 ⁶ g) were dry blended with predetermined amounts of the low molecular weight compounds shown in Table 7 and 0.5 part of 2,2'-bis(2-oxazoline), and the mixture was heated to temperature using an extruder. It was melt-extruded through a T-die at 245° C. for an average residence time of about 5 minutes and rapidly cooled to obtain a transparent unstretched film with a thickness of about 50 μm. The film was stretched 3.0 times in the longitudinal and transverse directions at 70°C, and then stretched 1 times at 180°C under a fixed length.
heat treated for 5 minutes, immersed in refluxing xylene for 5 minutes,
It was dried at 150°C for 10 minutes. Table 7 shows the thickness and physical properties of the stretched film obtained. When we tried to form a film under the same conditions without using a low-molecular compound, we were unable to form a film due to the high melt viscosity. (Comparative example 6)

【table】

Claims (1)

[Scope of Claims] 1 a A highly polymerized aromatic polyester (A) containing an aromatic dicarboxylic acid as the main acid component and an aliphatic diol and/or an alicyclic diol as the main glycol component, and the following (A): A low molecular weight compound (B) selected from ~(e), which is substantially non-reactive with the aromatic polyester, has a boiling point of about 200°C or more at normal pressure, and has a molecular weight of 1000 or less , (a) an imide compound represented by the following formula (1)-a; Here, A ¹ is a divalent aromatic residue or a chain or cyclic aliphatic residue, which may be substituted; R ¹ is an n-valent aromatic residue or a chain or cyclic aliphatic residue. aliphatic residues, which may be substituted; n is 1 or 2. However, the imide ring in the above formula is 5 or 6 members. (b) An imide compound represented by the following formula (1)-b; Here, A ² is a tetravalent aromatic residue,
It may be substituted; R ² is a monovalent linear or cyclic aliphatic residue, which may be substituted. However, the imide ring in the above formula is 5 or 6 members. (c) a trialkyl isocyanurate compound represented by the following formula (1)-c; Here, R ³ is a monovalent alkyl group. (d) A bisphenyl compound represented by the following formula (1)-d; Here, A ³ is -O-, -SO ₂ -, -CO- or an alkylene group, and the phenyl ring in the above formula may be substituted. (e) mononitronaphthalene; and the above-mentioned low molecular weight compound
The blending amount of (B) is 100% of the above aromatic polyester (A)
Forming an unstretched film or fibrous material by melt molding from an aromatic polyester blend in a range of 3 to 300 parts by weight, b. Stretching the film or fibrous material. c. Extracting the low molecular weight compound from the stretched film or fibrous material with an organic solvent that can dissolve the compound and does not substantially dissolve the aromatic polyester under extraction conditions. A method for producing a film-like or fibrous material of aromatic polyester. 2. The method of claim 1, wherein the aromatic polyester (A) has an intrinsic viscosity of at least about 0.6, measured as a solution in o-chlorophenol at 35°C. 3. The manufacturing method according to claim 1, wherein the low molecular weight compound (B) is a compound having a melting point of about 100°C or higher. 4. The manufacturing method according to claim 1, 2 or 3, wherein the amount of the low molecular weight compound (B) is 5 to 200 parts by weight based on 100 parts by weight of the aromatic polyester (A). . 5 The organic solvent used in the extraction is liquid at room temperature and has a boiling point lower than about 200°C at normal pressure.
The manufacturing method according to claim 1, wherein the method is: 6 The organic solvent is an aromatic hydrocarbon having 6 to 9 carbon atoms, a halogenated aliphatic hydrocarbon having 1 or 2 carbon atoms, an aliphatic ketone or aliphatic ester having 3 to 6 carbon atoms, a 5- or 6-membered cyclic The manufacturing method according to claim 5, which is an ether or an aliphatic alcohol having 1 to 3 carbon atoms. 7. The manufacturing method according to claim 1, 5 or 6, wherein the extraction is carried out under tension. 8. The manufacturing method according to claim 2, wherein the aromatic polyester (A) is a polyester containing terephthalic acid as the main acid component and polymethylene glycol having 2 to 6 carbon atoms as the main glycol component.