JPS6335172B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a novel aromatic polyester that is melt moldable and capable of providing molded articles having excellent mechanical properties and optical anisotropy. In recent years, the demand for higher performance plastics has been increasing, and many polymers with various new properties have been developed and put on the market. Among them, polymers with optical anisotropy, which is characterized by parallel arrangement of molecular chains, are particularly popular. Liquid crystal polymers have attracted attention because of their excellent mechanical properties. Fully aromatic polyesters are widely known as such liquid crystal polymers, and for example, homopolymers and copolymers of p-hydroxybenzoic acid are commercially available. However, p-hydroxybenzoic acid homopolymer has a too high melting point and cannot be melt-molded, so copolymers made by copolymerizing p-hydroxybenzoic acid with, for example, terephthalic acid and hydroquinone were developed as "Modern Plastics" in 1975.
As described in the July issue, page 62, its softening point is extremely high at approximately 427-482°C, making it difficult to melt and process, and its mechanical properties are also not fully satisfactory. . As a means of lowering the melting point or softening point of such wholly aromatic polyesters to improve melt moldability and further improve mechanical properties, hydroquinone is used, for example, as described in Japanese Patent Publication No. 55-482. An alternative method is to use chloro or methylhydroquinone in a polycondensation reaction with various dicarboxylic acids, but the polyester obtained by using terephthalic acid as the dicarboxylic acid has the disadvantage that its melting point is higher than 500°C. .
On the other hand, as described in JP-A-53-65421, polyester made from phenylhydroquinone and terephthalic acid has a relatively low melting point of 350°C or less;
Moreover, it is known that the elastic modulus of heat-treated yarn is as high as about 500 g/d. However, this elastic modulus is considerably lower than 1000 g/d of "Kevlar-49", which is widely known as a wholly aromatic polyamide, and an even higher elastic modulus is desired. Therefore, the present inventors conducted intensive studies with the aim of obtaining an aromatic polyester that can be melt-molded and give molded products with excellent mechanical properties and optical anisotropy. The present inventors have discovered that a novel aromatic polyester that satisfies the above objectives can be obtained by substituting part or all of the terephthalic acid with 4,4'-diphenyldicarboxylic acid, thereby achieving the present invention. That is, the present invention consists of the following structural units (A) to (C), a structural unit [] consisting of unit (A) and unit (B), and a structural unit [] consisting of unit (A) and unit (C). ,
Unit [] is 20 to 100 mol% of the whole, unit []
is 0 to 80 mol% of the total weight, and has a logarithmic viscosity of 0.2 to 10 dl/g measured at 60°C at a concentration of 0.1 g/dl in pentafluorophenol. It provides: [In the formula, R is

【formula】

[expression] and

Indicates a group selected from [Formula], and in the units [] and [], the units (A) and the units (B)+(C) are substantially equimolar. ] In the aromatic polyester of the present invention, the above structural unit [] is phenylhydroquinone and 4,4′-
The above-mentioned structural unit [] means a structural unit of a polyester produced from phenylhydroquinone and various aromatic dicarboxylic acids other than 4,4'-diphenyldicarboxylic acid. The aromatic polyester of the present invention has a melting point of 400°C or less,
It is possible to easily mold fibers, films, various molded products, etc. with excellent mechanical properties by ordinary melt molding. For example, the melting point of polyethylene terephthalate is 256°C, and the melting point of polyethylene-4,4'-diphenyl dicarboxylate is 355°C. As the number of benzene nuclei in the structural unit increases, the melting point of polyester increases. Therefore, it is expected that the polyester of the present invention containing 4,4'-diphenyldicarboxylic acid and phenylhydroquinone as essential components will have an extremely high melting point, but contrary to this prediction, the aromatic polyester of the present invention has a very high melting point. It has a relatively low melting point of 400°C or less, and has excellent melt moldability. In the aromatic polyester of the present invention, the proportion of the above structural unit [] is 20 to 100 mol% of the total
and preferably 50 to 95 mol%, particularly 60 to 90 mol%. The proportion of the above structural unit [ ] in the total
If it is less than 20 mol%, the aromatic polyester obtained will have a low melting point and insufficient heat resistance and rigidity, making it impossible to achieve the object of the present invention. The aromatic dicarboxylic acid components of the above structural unit [] are terephthalic acid, 4,4'-diphenyl ether dicarboxylic acid, and 1,2-bis(phenoxy).
At least one selected from ethane-4,4'-dicarboxylic acids, and two or more of these can be used in combination, but 4,4'-diphenyl ether dicarboxylic acid is most preferably used. . 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) Produced by demonocarboxylic acid polycondensation reaction from phenylhydroquinone diesters such as phenylhydroquinone diacetate and phenylhydroquinone dipropionate and dicarboxylic acids mainly composed of 4,4'-diphenyldicarboxylic acid. Method. (2) A method for producing phenylhydroquinone and diphenyl esters of dicarboxylic acids, mainly 4,4'-diphenyldicarboxylic acid, by dephenol polycondensation. (3) Dicarboxylic acids mainly composed of 4,4'-diphenyldicarboxylic acid are reacted with a desired amount of diphenyl carbonate to form diphenyl esters, and then phenylhydroquinone is added and produced by dephenol polycondensation reaction. Method. Acetic acid No. 1 is used as a catalyst for polycondensation reaction.
Metal compounds such as tin, tetrabutyl titanate, lead acetate, and antimony trioxide are representative, and are particularly effective in dephenol polycondensation. In addition, when polycondensing the aromatic polyester of the present invention, isophthalic acid, 3,3'-diphenyl dicarboxylic acid, 3,4'-diphenyl dicarboxylic acid, etc. acids, aromatic dicarboxylic acids such as 2,2'-diphenyldicarboxylic acid, alicyclic dicarboxylic acids such as hexahydroterephthalic acid, aromatic diols such as hydroquinone, chlorohydroquinone, methylhydroquinone, and p-oxybenzoic acid. Other aromatic oxycarboxylic acids can be further copolymerized within a small proportion that does not impair the purpose of the present invention. Note that the logarithmic viscosity of the aromatic polyester of the present invention is 0.2 to 10 dl/g as measured at 60°C at a concentration of 0.1 g/dl in pentafluorophenol, and is 0.4
~5 dl/g is preferred. 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. During molding, reinforcing agents such as glass fiber, carbon fiber, and asbestos, fillers, nucleating agents, pigments, antioxidants, stabilizers, plasticizers, lubricants, mold release agents, etc. may be added to the aromatic polyester of the present invention. Agents and other thermoplastic resins can be added to impart desired properties to the molded article. The molded article obtained from the novel aromatic polyester of the present invention has good optical anisotropy due to its parallel molecular alignment, and has extremely excellent mechanical properties. The present invention will be further explained below with reference to Examples. Example 1 13.5 g (5 x 10 ^-2 mol) of phenylhydroquinone diacetate and 12.1 g (5 x 10 ^-2 mol) of 4,4'-diphenyldicarboxylic acid were placed in a polymerization test tube, and the polymerization was carried out under the following conditions. A deacetic acid polycondensation reaction was carried out. First, the reaction was carried out at 280°C for 1 hour under a nitrogen gas atmosphere, then the temperature was raised to 350°C in 2 hours, the pressure was reduced to 0.6 mmHg, and the polycondensation was completed by further heating for 0.2 hours. 98% acetic acid 5.9
g was distilled out and a brown 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.

[Table] However, the oxygen content (%) is (100%-C%-H%)
Calculated from. Furthermore, this polyester was placed on a sample stage of a polarizing microscope and heated to confirm the melting point and optical anisotropy. As a result, the melting point was 368°C, indicating good optical anisotropy. The logarithmic viscosity of this polyester was measured in pentafluorophenol and was found to be 3.4. On the other hand, the infrared absorption spectrum is 1735, 1600, 1475 cm ^-1
solid-state ^13C NMR (JEOL
FX100 spectrometer) measured 136.7ppm, which was caused by phenylhydroquinone.
145.3ppm, 148.8ppm peaks and 129.3ppm caused by 4,4′-diphenyl dicarboxylic acid,
It was found that there was a peak at 164.6ppm. Examples 2 to 7 In a test tube for polymerization, 5 x 10 ^-2 mol (100 mol%) of phenylhydroquinone diacetate, 4,4'-diphenyldicarboxylic acid and terephthalic acid, 4,
4′-diphenyl ether dicarboxylic acid, 1,2-
Bis(phenoxy)ethane A dicarboxylic acid selected from 4,4-dicarboxylic acid (5 x 10 ^-2 mol = 100 mol % as total dicarboxylic acids) was added in the proportion shown in Table 2, and the same method as in Example 1 was carried out. Polycondensation was performed to obtain a polymer with a logarithmic viscosity of 1.7 to 3.1. When these polyesters were placed on a sample stage of a polarizing microscope and heated to confirm their melting points and optical anisotropy, all of them showed optical anisotropy. Table 2 shows the melting points of each polyester obtained. Further, for all of these polyesters, the carbon, hydrogen, and oxygen contents from the theoretical structural formula and the elemental analysis results showed good agreement.

[Table] Among these polymers, the polyester of Experiment No. 5 was subjected to a Koka type flow tester and spun under the following conditions.
A spun yarn of 34 denier was obtained. Spinning temperature: 380°C Spinneret diameter: 0.2 mmφ Spinning draft: 20 Winding speed: 50 m/min This spun yarn had an elastic modulus of 500 g/d or more without heat treatment.

Claims (1)

[Claims] 1 Consisting of the following structural units (A) to (C), unit (A) and unit
Consisting of a structural unit [ ] consisting of (B) and a structural unit [ ] consisting of unit (A) and unit (C), unit [ ] is 20 to 100 mol% of the total, and unit [ ] is 0 to 80 mol % of the total. % and in pentafluorophenol
Logarithmic viscosity measured at 60°C at a concentration of 0.1 g/dl is 0.2
A melt-formable aromatic polyester characterized in that it has a polyester of ~10 dl/g. [In the formula, R represents a group selected from [Formula] [Formula] and [Formula], and in units [] and [], unit (A) and unit (B) + (C) are substantially equimolar amounts. ].