JPH0479821B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a novel stretched product (e.g., film, fiber, etc.) made of a specific heat-resistant aromatic polyimide and having extremely excellent physical properties, particularly a high Young's modulus, and its stretched product. This invention relates to a new method for producing molded bodies. The polyimide stretched molded product of the present invention has a high Young's modulus as well as a high level of tensile strength and heat resistance compared to this type of aromatic polyimide film molded by the usual solution casting method. In particular, they can also be used satisfactorily as thin films or fine fibers for various applications. [Prior Art] Conventionally, as a method for producing a heat-shrinkable aromatic polyimide film (stretched film),
For example, as described in Japanese Patent Publication No. 57-41330, a solution of a biphenyltetracarboxylic acid-based aromatic polyimide precursor (polyamic acid or polyamic acid) is kept at a temperature of 20 to 200°C and cast. at least 50 wt.
is converted into polyimide, and then the polyimide film is stretched in at least one direction at a stretching ratio of 100 to 500 times so that the stretching ratio is 1.05 to 5 times.
A method of stretching at a temperature of .degree. C. has been proposed. However, although it is possible to produce a heat-shrinkable polyimide film with the above method, it is difficult to forcibly stretch an "unstretched film with a high imidization rate" that has a low solvent content, or Since stretching is performed at the same time, it is difficult to perform the stretching operation stably, and
It has been difficult or virtually impossible to produce polyimide stretched films with physical properties such as high Young's modulus with good reproducibility. [Problems to be Solved by the Present Invention] The purpose of the present invention is to create a high tensile strength, etc., high Young's modulus while maintaining the excellent heat resistance originally possessed by aromatic polyimide molded products. It is an object of the present invention to provide an aromatic polyimide stretched molded article (e.g., film, fiber, etc.) with novel physical properties, and to industrially produce such a stretched aromatic polyimide molded article with high physical properties with good reproducibility. The goal is to provide a way to do so. [Requirements of the present invention] In other words, the present invention requires the use of an aromatic tetracarboxylic acid component containing 80 mol% or more of biphenyltetracarboxylic acids and an aromatic diamine component containing 70 mol% or more of diaminodiphenyl ethers. Consisting of the obtained aromatic polyimide, and
Tensile strength (ASTM D882) is 30-100Kg/ ^mm2 , and Young's modulus (tensile modulus; ASTM
D882) is 400 to 800 Kg/ ^mm2 . Further, the production method of the present invention includes a soluble aromatic polyimide obtained by polymerizing the above-mentioned aromatic tetracarboxylic acid component and aromatic diamine component in a halogenated phenol solvent, and a content of 50% by weight or less. After sufficiently swelling an unstretched molded body consisting of a halogenated phenolic solvent and a halogenated phenol solvent in a swelling solvent that is compatible with the halogenated phenolic solvent and does not substantially dissolve the aromatic polyimide, the swollen unstretched body is The molded body is placed in the swelling solvent described above,
The present invention relates to a method for producing a polyimide stretched molded body, which comprises stretching the stretched polyimide body by a factor of 1.1 to 3.0 at a stretching temperature of 0 to 200°C, and finally removing the solvent from the stretched body and heat-treating the stretched body. The aromatic tetracarboxylic acid component is, for example, 2,3,3',4'-biphenyltetracarboxylic acid or its acid dianhydride, or an ester of the acid with a lower alcohol having 1 to 5 carbon atoms; ，
3',4,4'-biphenyltetracarboxylic acid or its dianhydride, or the acid having 1 to 5 carbon atoms
An aromatic tetracarboxylic acid component containing biphenyltetracarboxylic acids such as lower alcohol esters of 80 mol% or more, particularly 85 mol% or more, based on the total tetracarboxylic acid component. In this invention, in particular, as the tetracarboxylic acid component,
The aromatic tetracarboxylic acid component containing 80 mol% or more, more preferably 85 mol% or more of 3,3',4,4'-biphenyltetracarboxylic acid or its acid dianhydride is used in the aromatic polyimide obtained. It is optimal because it is excellent in solubility in halogenated phenols, moldability of the polyimide stretched molded product finally obtained, and heat resistance and mechanical properties of the stretched molded product. In addition, the above aromatic tetracarboxylic acid component is
In addition to biphenyltetracarboxylic acids, examples of tetracarboxylic acids that can be used in combination include pyromellitic acid or its acid dianhydride, benzophenonetetracarboxylic acid or its acid dianhydride, bis(3,4-dicarboxylic acid) phenyl)methane or its acid dianhydride, 2,2-bis(3,4-dicarboxyphenyl)propane or its acid dianhydride, bis(3,4-dicarboxyphenyl)sulfone or its acid dianhydride Examples include anhydrides. The aromatic diamine component mentioned above includes diaminodiphenyl ethers such as 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, and 3,3'-diaminodiphenyl ether, and wholly aromatic diamines. The aromatic diamine component is contained in an amount of 70 mol % or more, particularly 80 mol % or more, and more preferably 90 mol % or more. In this invention, in particular, 4,4'-
An aromatic diamine component containing diaminodiphenyl ether at a content of 70 mol% or more, particularly 80 mol% or more is optimal. In addition, in the above-mentioned aromatic diamine component, in addition to diaminodiphenyl ethers, aromatic diamines that can be used in combination include, for example,
4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylpropane, 4,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfide, o-, m- or p- Examples include phenylenediamine. In this invention, when the content of diaminodiphenyl ethers in the aromatic diamine component for producing the aromatic polyimide becomes too low, the aromatic diamine component and the aromatic tetracarboxylic acid component are separated from each other. The aromatic polyimide obtained has a reduced solubility in halogenated phenols, and it may not be possible to stably produce an unstretched molded product, so it is not suitable. However, it is not suitable because only a stretched molded product can be obtained that has poor heat resistance or any of the above-mentioned mechanical properties. In particular, the polyimide stretched molded article of the present invention contains an aromatic tetracarboxylic acid component whose main component is the above-mentioned biphenyltetracarboxylic acids (content of 90 mol or more), and a main component of diaminodiphenyl ethers (content of 80 mol or more). It is made of a halogenated phenol-soluble aromatic polyimide obtained from an aromatic diamine component (mol% or more), and has a tensile strength of 30 to 100 Kg/mm ² , preferably 35 to 80 Kg/mm ² In addition, Young's modulus (elastic modulus) is 400 to 1000
Kg/mm ² , preferably about 410 to 800 Kg/mm ² ,
More preferably, the elongation at break is 10 to 70.
%, particularly about 15 to 60%, is an aromatic polyimide stretched molded product with high physical properties such as a "film-like material (sheet-like material) with a thickness of about 5 to 200 μm". As in this invention, with sufficient heat resistance, 25
Aromatic polyimide soluble in halogenated phenols (stretched) with tensile strength higher than Kg/mm ² and Young's modulus (modulus) higher than 350 Kg/mm ²
Conventionally, "molded bodies" were completely unknown. In the production method of the present invention, for example, approximately equimolar amounts of an aromatic tetracarboxylic acid component and an aromatic diamine component are mixed in an organic polar solvent, preferably about
A "high molecular weight aromatic polyimide that is soluble in halogenated phenols" obtained by polymerization at a temperature of 120°C or higher, particularly preferably 140 to 300°C, and a content of 50% by weight or less in the unstretched molded body, Preferably 1
~45% by weight of a halogenated phenol solvent (self-supporting film);
An unstretched molded body such as a solidified fibrous body is used. In this invention, (1) the above-mentioned compound is added to a swelling solvent that is compatible with the halogenated phenol solvent, does not substantially dissolve the aromatic polyimide, and has the property of swelling an unstretched molded article. The unstretched molded body is immersed in a swelling solvent, preferably at a temperature of 0 to 200°C (particularly preferably 20 to 150°C), for 0.5 to 20 hours (especially 1 to 10 hours). (2) The swollen unstretched molded body is soaked in the swelling solvent.
1.1 to 3.0 times, preferably at a stretching temperature of 0 to 200 °C (particularly within a temperature range higher than 10 °C and lower than the boiling point of the solvent in the swelling solvent).
(3) Finally, the solvent is removed from the stretched molded product, and the stretched molded product is stretched by 0.5 to 2.5 times, preferably at a temperature of 150°C or higher (particularly preferably 180 to 400°C).
The aromatic polyimide stretched molded article is produced by performing heat treatment for 10 hours, particularly 1 to 5 hours. In this invention, in order to remove the swelling solvent etc. from the stretched molded product, water or the like is added at 10 to 50°C, especially at 20 to 20°C.
It can be carried out by extraction at a temperature of 45°C, or it can be removed by evaporation of the solvent by heating the stretched molded body under normal pressure or reduced pressure. During the treatment, it is preferable from the viewpoint of physical properties to perform the heat treatment while fixing at least both ends of the stretched body at a certain distance with a frame, etc.; however, it is not necessary to fixation is not an essential requirement. In addition, the above heat treatment is performed at a temperature of about 150 to 260
It is also possible to carry out a primary heat treatment at a relatively low temperature of 260 to 450 °C, followed by a secondary heat treatment at a high temperature of 260 to 450 °C. It is preferable to do this in a fixed manner. The aromatic polyimide is a biphenyltetracarboxylic acid-based soluble polyimide obtained by polymerizing an aromatic tetracarboxylic acid component and an aromatic diamine component at high temperatures, and has a logarithmic viscosity (measurement temperature: 50°C, Concentration: 0.5 g/100 ml (solvent; ] is greater than 90%, especially 95% or more (no peak in the infrared absorption spectrum due to polyamic acid is observed), and furthermore, about 5 to 40% by weight of the halogenated phenolic solvent
It is preferable to use a polymer that can be uniformly dissolved up to a concentration of . The above-mentioned logarithmic viscosity is a value calculated by the following formula. Logarithmic viscosity = natural logarithm (solution viscosity/solvent viscosity)/concentration of solution In the above-mentioned infrared analysis method for determining the imidization rate, the imidization rate is determined from the absorbance of the absorption peak 1770 cm ^-1 based on the imide bond in the infrared absorption spectrum of the sample. can be found. The above-mentioned halogenated phenol solvent may be any type as long as it can dissolve the above-mentioned biphenyltetracarboxylic acid-based soluble aromatic polyimide at a ratio of 5% by weight or more at a temperature of 50 to 150°C. It may be a halogenated phenol compound having a melting point of about 100°C or less, especially 80°C or less, and a boiling point of 300°C or less at normal pressure,
Particularly preferred are halogenated phenol compounds whose temperature is 280°C or lower. Examples of the halogenated phenol solvents include o-chlorophenol, m-chlorophenol, p-chlorophenol, o-bromophenol, m-bromophenol, p-bromophenol, 2-chloro-4-hydroxytoluene, and 2-chlorophenol.
Chlor-5-hydroxytoluene, 3-chloro-
6-hydroxytoluene, 4-chloro-2-hydroxytoluene, 2-bromo-4-hydroxytoluene, 2-bromo-5-hydroxytoluene,
Examples include 3-bromo-6-hydroxytoluene and 4-bromo-2-hydroxytoluene, or a mixed solvent of two or more of these halogenated phenol compounds may be used. The swelling solvent is incapable of uniformly dissolving the aromatic polyimide at a temperature of 50°C at a temperature of about 3% by weight or more, especially 1% by weight or more, and has excellent compatibility with halogenated phenols. In particular, any organic polar solvent that has the property of swelling the unstretched molded article described above may be used. Such swelling solvents include mixed solvents of halogenated phenols and alcohols (as mixed solvents, the weight ratio of halogenated phenols/alcohols is
30/70 to 90/10, particularly preferably about 50/50 to 90/10), or N,N-dimethylformamide, N,N-diethylformamide,
N,N-dilower alkylcarboxylamides such as N,N-dimethylacetamide, N,N-diethylacetamide, N,N-dimethylmethoxyacetamide, 1,3-dimethyl-2-imidazolidinone, N-methyl- Examples include organic polar solvents such as 2-pyrrolidone, dimethyl sulfoxide, diethyl sulfoxide, dimethyl sulfone, diethyl sulfone, and hexamethyl sulfolamide. Examples of the alcohols include those having 1 to 6 carbon atoms, such as methanol, ethanol, propanol, isopropanol, butanol, and amino alcohol.
Preferred examples include lower alcohols of about 100%. In this invention, an unstretched molded body such as a solidified film-like body or a solidified fibrous body made of the above-mentioned high-molecular-weight aromatic polyimide and a halogenated phenol solvent with a content of 50% by weight or less is (a) self-stretched; (b) contains 50% by weight or less of a halogenated phenol solvent; (c) is a substantially unstretched molded article that has not been stretched by a stretching ratio of more than 1.1 times; It can be manufactured in
In this invention, the method for producing the unstretched molded body is not particularly limited, and for example, a polyimide solution in which the aromatic polyimide is uniformly dissolved in a halogenated phenol solvent is used to
Most of the solvent is evaporated from the liquid film or fibrous material formed by casting at 150°C or by spinning at a similar temperature. (dry method)
Or, it can be removed by an extraction method using an extraction solvent mainly composed of water, alcohol, etc. (wet method).
Alternatively, by removing them in combination, it is possible to produce an unstretched molded product such as a solidified film or solidified fiber made of aromatic polyimide and a halogenated phenol solvent with a content of 50% by weight or less. can. In this invention, an unstretched molded body made of the above-mentioned biphenyltetracarboxylic acid-based aromatic polyimide is swollen with a swelling solvent, then stretched in the swelling solvent, and then halogenated from the stretched molded body. The main characteristics are that phenols are removed and heat treatment is performed at high temperatures, and as mentioned above, by using a swelling solvent during stretching, aromatic compounds with excellent Young's modulus with good reproducibility can be easily produced. This makes it possible to produce a stretched polyimide body. [Example] In the Examples and Comparative Examples, physical property tests were conducted on sample pieces (length: 20 mm, width: 5 mm). Examples 1 to 8 Polymerization of 3,3',4,4'-biphenyltetracarboxylic dianhydride and 4,4'-diaminodiphenyl ether at 160°C for 1 hour in p-chlorophenol solvent and the aromatic polyimide solution obtained by imidization [polymer concentration: 18% by weight, polymer logarithmic viscosity: 1.4, solution viscosity at 25°C (solution viscosity measured by rotational viscometer): 1000 poise],
The resulting liquid thin film was solution cast at approximately 50 °C to a uniform thickness on a glass plate using 50 °C.
℃ for 1 hour, and then vacuum-dried at 50℃ for 24 hours to form a biphenyltetracarboxylic acid-based aromatic polyimide (imidization rate of 95% or more).
A long solidified film (unstretched film of polyimide-halogenated phenol solvent) with a thickness of 50 μm was formed, comprising 12% by weight of the above solvent. Using the solidified film, 1,3-
After swelling for 1.5 hours using dimethyl-idasolidinone as a swelling solvent, it was uniaxially stretched in the swelling solvent at 75°C at the stretching ratio shown in Table 1 in the longitudinal direction at a stretching speed of 125%/min and fixed. The stretched film was subjected to solvent extraction with water at 50°C to remove the swelling solvent, and then both ends in the stretching direction were fixed to a frame and treated at the temperature and time shown in Table 1 to obtain the first A stretched film made of aromatic polyimide having the physical properties shown in the table was molded. Comparative Examples 1 and 2 The above-mentioned solidified film (unstretched film) was fixed to a frame on all four sides and heat-treated at the temperature and time shown in Table 1 to evaporate and remove the solvent to form an aromatic polyimide film. was manufactured. The physical properties of the film are shown in Table 1. Comparative Examples 3 and 4 The solidified film (unstretched film) described above was swollen in a swelling solvent, but without any stretching.
An aromatic polyimide film was prepared in the same manner as in Example 1, except that the four sides were fixed to a frame and treated at the temperature and time shown in Table 1 to evaporate and remove the solvent, swelling solvent, and water. was manufactured. The physical properties of the film are shown in Table 1.

【table】

[Table] Stretching ratio Temperature Time Tensile strength Young's modulus Elongation
(times) (℃) (minutes)
(Kg/mm ² ) (Kg/mm ² ) (%)

Claims (1)

[Scope of Claims] 1. An aromatic compound obtained from an aromatic tetracarboxylic acid component containing 80 mol% or more of biphenyltetracarboxylic acids and an aromatic diamine component containing 70 mol% or more of diaminodiphenyl ethers. Made of polyimide and has a tensile strength of 30 to 100
Kg/mm ² and Young's modulus of 400 to 800 Kg/mm ²
A polyimide stretched molded body. 2. An aromatic tetracarboxylic acid component containing 80 mol% or more of biphenyltetracarboxylic acids and an aromatic diamine component containing 70 mol% or more of diaminodiphenyl ethers in approximately equal moles in a halogenated phenol solvent. An unstretched molded body consisting of an aromatic polyimide obtained by polymerization and a halogenated phenol solvent having a content of 50% by weight or less is prepared in a manner that is compatible with the halogenated phenol solvent and substantially frees the aromatic polyimide. After sufficiently swelling in a swelling solvent that does not dissolve in 1. A method for producing a stretched polyimide molded body, which comprises removing a solvent and heat-treating the stretched molded body.