JPH0362726B2 - - Google Patents

Description

[Detailed description of the invention]

<Industrial Application Field> The present invention relates to a novel high-modulus polyester that can be melt-molded at 400° C. or lower and can provide molded articles having excellent mechanical properties and optical anisotropy. <Conventional technology> In recent years, the demand for higher performance plastics has been increasing, and many polymers with various new performances have been developed and put on the market. Optically anisotropic liquid crystal polymers have attracted attention because of their excellent mechanical properties. (Special Publication No. 55-482). <Problems to be Solved by the Invention> Fully aromatic polyesters are representative of this liquid crystal polymer, and for example, homopolymers and copolymers of p-hydroxybenzoic acid are known. However, these p-hydroxybenzoic acid homopolymers and their copolymers have too high a melting point and cannot be melt-molded or are difficult to melt-mold. As a copolyester, its softening point is as high as about 427 to 482°C, making it difficult to melt-process, and its mechanical properties are not fully satisfactory. On the other hand, as a means of lowering the melting point or softening point of such wholly aromatic polyester to improve melt molding and further improve mechanical properties, for example, as described in Japanese Patent Publication No. 1982-482, One method is to use chloro or methylhydroquinone instead of hydroquinone and cause a polycondensation reaction with a dicarboxylic acid such as terephthalic acid, but it is said that the polyester obtained by using terephthalic acid as the dicarboxylic acid has a melting point higher than 500°C. There are drawbacks. Therefore, a small amount of 4,4'-diphenyldicarboxylic acid or 2,6-dicarboxylic acid is added to terephthalic acid.
It has been proposed to copolymerize naphthalene dicarboxylic acid or 1,2-bis(phenoxy)ethane-4,4'-dicarboxylic acid, but in both cases the resulting fibers have a low elastic modulus and are insufficient. Ta. On the other hand, as described in JP-A No. 53-65421, polyester made from phenylhydroquinone and terephthalic acid has a relatively low melting point of 350°C or less, and has a high elastic modulus of about 500 g/d of heat-treated yarn. It is known that the rate of <Problems to be Solved by the Invention> However, although the aromatic polyester obtained by these methods has a relatively low melting point of 400°C or less, the elastic modulus of the spun yarn is still insufficient, and even higher Modulus of elasticity is desired. Therefore, the present inventors conducted intensive studies with the aim of obtaining aromatic polyesters that can be melt-molded and provide molded products with excellent mechanical properties and optical anisotropy. ′-diphenyldicarboxylic acid,
selected from 2,6-naphthalene dicarboxylic acid, 1,2-bis(2-phenoxy)ethane-4,4'-dicarboxylic acid, and 1,2-bis(2-chlorophenoxy)ethane-4,4'-dicarboxylic acid. The inventors have discovered that a polyester having a specific composition can provide a novel high-modulus polyester that satisfies the above-mentioned objectives, and has thus arrived at the present invention. <Means for solving the problems> That is, the present invention provides the following structural unit [()+
()] or [()+()+()],
The unit () accounts for 30 to 90 mol% of the total, the unit () or [() + ()] accounts for 70 to 10 mol% of the total, (liquid crystal starting temperature + 50 ° C), shear rate 3000 (1/
The present invention provides a melt-moldable high-modulus polyester characterized by a melt viscosity measured in seconds) of 20 to 30,000. (In the formula, X is a methyl group and/or a chlorine atom, Y
represents one or more groups selected from hydrogen atoms and/or chlorine atoms. ) In the aromatic polyester of the present invention, the structural unit () is a structural unit of a polyester purified from methylhydroquinone and/or chlorohydroquinone and 4,4'-diphenyldicarboxylic acid; The above structural unit () is a structural unit consisting of chlorohydroquinone and 2,6-naphthalene dicarboxylic acid, and the above structural unit () is methylhydroquinone and/or
or chlorhydroquinone and 1,2-bis(2
-Phenoxy)ethane-4,4'-dicarboxylic acid 1,2-bis(2-chlorophenoxy)ethane-
A polyester structural unit consisting of a dicarboxylic acid selected from 4,4'-dicarboxylic acids. The high elastic modulus polyester of the present invention having such a structure has a melting point of 400°C or less, and can be molded into fibers, films, various molded products, etc. with excellent mechanical properties and optical anisotropy by ordinary melt molding. It is possible. For example, the melting point of polyethylene terephthalate is 256°C, and polyethylene-4,
The melting point of 4'-diphenylcarboxylate is 355℃
Therefore, it is expected that the polyester of the present invention, which has 4,4'-diphenylcarboxylic acid and methylhydroquinone as essential components and provides a polyester with a higher melting point than terephthalic acid, will have an extremely high melting point. The copolyester of the present invention has a relatively low melting point of 400°C or less, and has good melt fluidity.
Moreover, it has the advantage of having a significantly higher elastic modulus than the polyester examples described in the above publication,
Such novel effects are completely unexpected based on conventional knowledge. In the copolymerized polyester of the present invention, the proportion of the above structural units () is 30 to 90 mol% of the total, more preferably 40 to 85 mol%, particularly 45 to 85 mol%.
Mol% is preferred. That is, the above structural unit () or [() +
()] accounts for 70 to 10 mol% of the total, more preferably 60 to 15 mol%, particularly preferably 55 to 15 mol%. The molar ratio of ()/() is 100/0 to 5/95, preferably 95/5 to 10/90. The proportion of the above structural units () in the total is 0~
If the ratio of 30 mol%, () or [() + ()] is 100 to 70 mol% of the total, the resulting aromatic polyester may have too high a melting point or have insufficient heat resistance or mechanical properties. Therefore, the object of the present invention cannot be achieved. In addition, when the proportion of the above structural units () is 90 to 100 mol% of the total, and the proportion of () or [() + ()] is 10 to 0 mol% of the total, the resulting aromatic polyester has poor fluidity. As a result, it is impossible to achieve the object of the present invention. The aromatic polyester of the present invention can be produced according to a conventional polyester polycondensation method, and there are no particular restrictions on the production method, but typical production methods include, for example, the following methods (1) to (3). (1) By demonocarboxylic acid polycondensation reaction of diesters of aromatic dihydroxy compounds such as chlorohydroquinone diacetate and chlorhydroquinone dipropionate and aromatic dicarboxylic acids mainly composed of 4,4'-diphenylcarboxylic acid. How to manufacture. (2) A method for producing by dephenol polycondensation from an aromatic dihydroxy compound such as chlorohydroquinone and a diphenyl ester of an aromatic dicarboxylic acid mainly composed of 4,4'-diphenylcarboxylic acid. (3) Aromatic dicarboxylic acids, mainly 4,4'-diphenylcarboxylic acid, are reacted with a desired amount of diphenyl carbonate to form diphenyl esters, and then an aromatic dihydroxy compound such as chlorohydroquinone is added to decompose them. A method for producing by phenol polycondensation reaction. Typical catalysts used in polycondensation reactions are metal compounds such as stannous acetate, tetrabutyl titanate, lead acetate, sodium acetate, potassium acetate, and antimony trioxide, and are particularly effective in dephenol polycondensation. It is. For some of the aromatic polyesters of the present invention, it is possible to measure the logarithmic viscosity in pentafluorophenol, where the viscosity is 0.1 (weight/volume).
% concentration measured at 60° C. is preferably 0.35 or more, particularly preferably 0.4 to 15.0. Further, the melt viscosity of the aromatic polyester of the present invention is preferably 20 to 30,000 poise, particularly preferably 50 to 10,000 poise. In addition, this melt viscosity is (liquid crystal start temperature + 50℃)
This is a value measured using a Koka type flow tester at a shear rate of 3000 (1/sec). Note that the liquid crystal start temperature is the temperature at which a small piece of polymer is placed between two cover glasses and heated on a sample stage of a polarizing microscope, and a milky white color is produced under shear stress. When polycondensing the high modulus polyester of the present invention, in addition to the components constituting the structural units (), (), and (), terephthalic acid, isophthalic acid, 3,3'-diphenyldicarboxylic acid,
Aromatic dicarboxylic acids such as 3,4'-diphenyldicarboxylic acid and 2,2'-diphenyldicarboxylic acid,
Alicyclic dicarboxylic acids such as hexahydroterephthalic acid, other aromatic diols such as hydroquinone, and other aromatic oxycarboxylic acids such as p-oxybenzoic acid, etc., in small proportions that do not impair the purpose of the present invention. can be further copolymerized. The aromatic polyester of the present invention thus obtained has a low melting point of 400°C or less, and can be subjected to ordinary melt molding such as extrusion molding, injection molding, compression molding, and blow molding, and can be used to make fibers, films, three-dimensional molded products,
It can be processed into containers, hoses, etc. In addition, during molding, reinforcing agents such as glass fiber, carbon fiber, and asbestos, fillers, nucleating agents, pigments, antioxidants, stabilizers, plasticizers, lubricants, mold release agents, and flame retardants are added to the aromatic polyester of the present invention. Additives such as and other thermoplastic resins can be added to impart desired properties to the molded article. The strength of the thus obtained molded article can be increased by heat treatment, and in many cases the elastic modulus can also be increased. This heat treatment can be carried out by heat treating the molded article in an inert atmosphere (eg nitrogen, argon helium or water vapor) or in an oxygen-containing atmosphere (eg air) at a temperature below the melting point of the polymer. This heat treatment may or may not be under tension and can be carried out for a period of several minutes to several days. The molded article obtained from the novel polyester resin of the present invention has good optical anisotropy due to its parallel molecular arrangement and has extremely excellent mechanical properties. <Example> The present invention will be further described below with reference to Examples. Example 1, Comparative Examples 1 and 2 In a polymerization test tube, 11.48 g (5 x 10 ^-2 mol) of chlorhydroquinone diacetate, 8.47 g (3.5 x 10 ^-2 mol) of 4,4'-diphenyldicarboxylic acid, 2 ,6
- 1.62 g (0.75 x 10 ^-2 mol) of naphthalene dicarboxylic acid, 1,2-bis(phenoxy)ethane-4,
2.27 g (0.75 x 10 ^-2 mol) of 4'-dicarboxylic acid was charged, and acetic acid depolymerization was carried out under the following conditions. First, the reaction was carried out at 250 to 330℃ for 3 hours in a nitrogen gas atmosphere, then the pressure was reduced to 0.7mmHg, and the temperature was further increased to 330℃.
After heating for 1.5 hours to perform a polycondensation reaction, a highly fibrillated gray-black polymer was obtained. The theoretical structural formula of this polymer is as follows,
The elemental analysis results of the polyester showed good agreement with the theoretical values as shown in Table 1. Further, the thermal stability of this polymer was measured using a differential scanning calorimeter (Perkin Elmer type) and found that the glass transition temperature was 103°C and the melting point was 299°C. (l/m/n molar ratio = 70/15/15)

[Table] However, the oxygen content (%) is (100%-C%-H%
−Cl%). The melting point and optical anisotropy were confirmed by placing this polyester on the sample stage of a polarizing microscope and confirming the melting point and optical anisotropy.As a result, the liquid crystal initiation temperature was 246°C, indicating good optical anisotropy. This polyester was subjected to a Koka type flow tester and spun at a spinning temperature of 330℃ and a spinneret hole diameter of 0.3mmφ.
A spun yarn with a diameter of 0.06 mm was obtained. The melt viscosity measured at 296°C was 1700 poise at a shear rate of 3000 (1/sec). This spun yarn was processed at a frequency of 110Hz using Toyo Baldwin Co., Ltd.'s Leo Vibron DDV--EA.
When the elastic modulus was measured at a heating temperature of 2°C/min and a chuck distance of 40 mm, it was 101 GPa, which was an extremely high elastic modulus. Example 2 In a polymerization test tube, 10.45 g (5 x 10 ^-2 mol) of methylhydroquinone diacetate, 10.29 g (4.25 x 10 ^-2 mol) of 4,4'-diphenyldicarboxylic acid, 2,
6-naphthalene dicarboxylic acid 0.81g (0.375×10 ^-2
mole), 1,2-bis(phenoxy)ethane-4,
1.13 g (0.375 x 10 ^-2 mol) of 4'-dicarboxylic acid was charged, and acetic acid depolymerization was carried out under the following conditions. First, the reaction was carried out at 250 to 340℃ for 3 hours in a nitrogen gas atmosphere, then the pressure was reduced to 0.6mmHg, and the temperature was further increased to 340℃.
After heating for 1.0 hour to perform a polycondensation reaction, a highly fibrillated brown polymer was obtained. The theoretical structural formula of this polymer is as follows,
The elemental analysis values of the polyester showed good agreement with the theoretical values as shown in Table 2. Further, the thermal stability of this polymer was measured using a differential scanning calorimeter (Perkin-Elmer type), and the melting point was 269°C. (l/m/n molar ratio = 8.5/0.75/0.75)

[Table] However, the oxygen content (%) is (100%-C%-H%
−Cl%). The optical anisotropy was confirmed by placing this polyester on the sample stage of a polarizing microscope and raising the temperature. As a result, the liquid crystal initiation temperature was 262°C, indicating good optical anisotropy. This polyester was subjected to a Koka type flow tester and spun at a spinning temperature of 350° C. and a spindle hole diameter of 0.3 mmφ to obtain a spun yarn of 0.08 mmφ. The melt viscosity measured at 312°C was 1700 poise at a shear rate of 3000 (1/sec). This spun yarn was processed at a frequency of 110Hz using Toyo Baldwin Co., Ltd.'s Leo Vibron DDV--EA.
When the elastic modulus was measured at a heating temperature of 2°C/min and a chuck distance of 40 mm, the elastic modulus was extremely high at 30°C, 116 GPa. Comparative Example 1 In a polymerization test tube, 10.45 g (5 x 10 ^-2 mol) of methylhydroquinone diacetate, 7.56 g (3.5 x 10 ^-2 mol) of 2,6-naphthalene dicarboxylic acid, 1,2
-Bis(phenoxy)ethane-4,4'-dicarboxylic acid (4.53 g, 1.5 x 10 ^-2 mol) was charged and polycondensation was carried out in the same manner as in Example 2 to obtain an optically anisotropic polyester having a melting point of 316°C. 350 using this polyester
Although spinning was carried out in the same manner as in Example 2 at .degree. C., a uniform spun yarn could not be obtained. Comparative Example 2 In a polymerization test tube, 10.45 g (5 x 10 ^-2 mol) of methylhydroquinone diacetate, 7.56 g (3.5 x 10 ^{-2 mol) of 2,6-naphthalene dicarboxylic acid, and 2.49 g (1.5 x 10 -2} mol) of terephthalic acid were added ^. Example ²
Polycondensation was carried out by raising the reaction temperature to 250 to 260°C under the following conditions to obtain an optically anisotropic polyester with a melting point of 343°C. Using this polyester, spinning was carried out at a spinning temperature of 390°C, but a uniform spun yarn could not be obtained. Examples 3 to 8, Comparative Examples 3 to 7 In a test tube for polymerization, 5 x 10 ^-2 moles of diacetate consisting of chlorohydroquinone diacetate () and methylhydroquinone diacetate (), and 4,
4'-diphenyldicarboxylic acid (), 2,6-naphthalene dicarboxylic acid (), 1,2-bis(phenoxy)ethane-4,4'-dicarboxylic acid (),
1,2-bis(2-chlorophenoxy)ethane-
A dicarboxylic acid consisting of 4,4'-dicarboxylic acid (2) was charged and polymerized in the same manner as in Examples 1 and 2. Examples 3 to 8 were spun, and the elastic modulus was measured using a vibron in the same manner as in Examples 1 and 2. As shown in Table 3, the elastic modulus showed good fluidity.
It has a high elastic modulus of over 50 GPa. On the other hand, in Comparative Examples 3, 4, and 7, uniform spun yarns were not obtained, and in Comparative Examples 5 and 6, the melting point was 400° C. or higher, and they were able to be spun.

[Table] <Effects of the present invention> The aromatic polyester of the present invention can be melt-molded and molded products with a high modulus of elasticity can be obtained, so it can be used for various purposes such as engineering plastics.

Claims (1)

[Claims] 1 The following structural unit [()+()] or [()
+()+()], and the unit () is the total
30-90 mol%, unit () or [()+()]
accounts for 70 to 10 mol% of the total, (liquid crystal starting temperature +
50°C) and a shear rate of 3000 (1/sec), the melt viscosity is 20 to 30000. (In the formula, X is a methyl group and/or a chlorine atom, Y
represents one or more groups selected from hydrogen atoms and/or chlorine atoms. )