JPH045045B2 - - Google Patents

Description

[Detailed description of the invention]

<Industrial Application Field> The present invention relates to a novel aromatic polyester that can be melt-molded 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 widely known as liquid crystal polymers. For example, homopolymers and copolymers of p-hydroxybenzoic acid are used.However, the melting point of this p-hydroxybenzoic acid homopolymer is too high. is too expensive and cannot be melt-molded.
Methods of copolymerizing p-hydroxybenzoic acid with various components to lower its melting point have been studied, such as p-hydroxybenzoic acid.
- Method of copolymerizing hydroxybenzoic acid with phenylhydroquinone, terephthalic acid and/or 2,6-naphthalene dicarboxylic acid
55-500215), a method of copolymerizing p-hydroxybenzoic acid with 2,6-dihydroxynaphthalene and terephthalic acid (Japanese Patent Application Laid-open No. 54-50594), and a method of copolymerizing p-hydroxybenzoic acid with 2,6-dihydroxyanthra A method of copolymerizing quinone and terephthalic acid (US Pat. No. 4,224,433) has been proposed. 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 there is a desire for an even higher elastic modulus. Therefore, the present inventors conducted intensive studies with the aim of obtaining an aromatic polyester that is melt moldable and has excellent balance between mechanical properties such as a high modulus of elasticity and optical anisotropy. Substituting part or all of the aromatic dicarboxylic acid of an aromatic polyester consisting of an acid, a specific aromatic dihydroxy compound such as phenylhydroquinone, and an aromatic dicarboxylic acid such as terephthalic acid with 4,4'-diphenyldicarboxylic acid. We have found that a novel aromatic polyester that satisfies the above objectives can be obtained by this method, and have filed an application (Japanese Unexamined Patent Publication No. 59-41328). The present inventors have discovered that even when aromatic dihydroxy compounds such as the following are used, they have a good ability to form liquid crystals despite their rigid structures. <Means for solving the problems> That is, the present invention consists of the following structural units () and () or (), () and (),
The unit () accounts for 10 to 90 mol% of the total, the structural unit () + () accounts for 90 to 10 mol% of the total, and the molar ratio of the unit ()/() is 100/0 to 30/70. , (liquid crystal start temperature +60℃), shear rate 3000
The present invention provides a melt-moldable aromatic polyester characterized by having a melt viscosity measured at 1/sec (1/sec) of 10 to 30,000 poise and a liquid crystal initiation temperature of 400°C or less. (However, R in the formula is

【formula】

【formula】

[Formula] O call

1 selected from [expression] The radical of the species, R′ is

【formula】

【formula】

[Formula] andbi

Indicates one or more groups selected from [Formula]. ) In the aromatic polyester of the present invention, the above structural unit () is a structural unit of a polyester produced from p-hydroxybenzoic acid, and the above structural unit () is a structural unit of a polyester produced from p-hydroxybenzoic acid, and the above structural unit () is a structural unit formed from an aromatic dihydroxy compound such as chlorohydroquinone and 4,4'-diphthalate. The structural unit of polyester produced from enyldicarboxylic acid, and the above structural unit () is produced from an aromatic dioxy compound such as chlorohydroquinone and an aromatic dicarboxylic acid other than 4,4'-diphenyldicarboxylic acid such as terephthalic acid. Each refers to the structural unit of polyester. The aromatic polyester of the present invention has a liquid crystal initiation temperature of 400°C or less, and in many cases has a melting point of 400°C.
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℃,
The melting point of polyethylene-4,4'-diphenylcarboxylate is 355°C, and as the number of benzene angles in the structural unit increases, the melting point of polyester increases. It is expected that the polyester of the present invention, which has an essential component of It has relatively low melt moldability and excellent melt moldability. 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 emits opalescent light under shear stress. In the aromatic polyester of the present invention, the proportion of the above-mentioned structural units ( ) is preferably 10 to 90 mol %, particularly 20 to 80 mol % of the total. is not possible, and if it is less than 10 mol%, melt fluidity often becomes poor, which is not preferable. The ratio of the above structural units () and () to the total is 90 to 10 mol%, especially 80 to 20 mol%, and the molar ratio of units ()/() is 100/0.
~30/70, particularly preferably 100/0 ~ 50/50.
Here, the proportion of unit () in unit () + () is
If it is less than 30 mol%, the mechanical properties of the resulting aromatic polyester will deteriorate, which is not preferable. In the aromatic polyester of the present invention, the aromatic dihydroxy components forming the structural units () and () are chlorohydroquinone, methylhydroquinone, 4,4'-dihydroxydiphenyl sulfide, 4,4'-dihydroxybenzo It is at least one selected from phenones, and chlorohydroquinone or methylhydroquinone is most preferred. In addition, the dicarboxylic acid components forming the structural unit () are terephthalic acid, 4,4'-diphenyl ether dicarboxylic acid, 1,2-bis(phenoxy)ethane-4,4'-dicarboxylic acid, 1,2
-bis(2-chlorophenoxy)ethane-4,
At least one selected from 4'-dicarboxylic acid and 2,6-naphthalene dicarboxylic acid. Among these, 1,2-bis(2-chlorophenoxy)ethane-4,4'-dicarboxylic acid is most preferred. 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) Demonocarboxylic acid removal from aromatic dicarboxylic acids mainly consisting of p-acetoxybenzoic acid and diesters of aromatic dihydroxy compounds such as chlorohydroquinone diacetate and chlorhydroquinone dipropionate, and 4,4'-diphenyldicarboxylic acid. A method of manufacturing by polycondensation reaction. (2) Manufactured by dephenol polycondensation from phenyl ester of p-oxybenzoic acid and aromatic dihydroxy compound such as chlorohydroquinone and diphenyl ester of aromatic dicarboxylic acid mainly composed of 4,4'-diphenyldicarboxylic acid. how to. (3) Aromatic dicarboxylic acids mainly consisting of p-oxybenzoic acid and 4,4'-diphenyldicarboxylic acid are reacted with a desired amount of diphenyl carbonate to form diphenyl esters, and then aromatic dicarboxylic acids such as chlorohydroquinone are added. A method of manufacturing by adding a group dihydroxy compound and performing a phenol-free 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. be. Many of the aromatic polyesters of the present invention can be measured for their logarithmic viscosity in pentafluorophenol at 60 °C at a concentration of 0.1% (w/v).
A value of 0.35 or higher is preferable, especially 0.4~
15.0 is preferred. Further, the melt viscosity of the aromatic polyester of the present invention is preferably 10 to 30,000 poise, particularly preferably 20 to 10,000 poise. In addition, this melt viscosity is (liquid crystal starting temperature + 60℃)
This is a value measured using a Koka type flow tester at a shear rate of 3000 (1/sec). In addition, when polycondensing the aromatic polyester of the present invention, the above structural units (), () and ()
In addition to the constituent components, aromatic dicarboxylic acids such as isophthalic acid, 3,3'-diphenylcarboxylic acid, 3,4'-diphenyldicarboxylic acid, 2,2'-diphenyldicarboxylic acid, hexahydroterephthalic acid, etc. Other aromatic diols such as alicyclic dicarboxylic acids, hydroquinone, and other aromatic oxycarboxylic acids such as m-oxybenzoic acid and 2,6-oxynaphthoic acid may be added in small amounts to the extent that the object of the present invention is not impaired. Further copolymerization can be carried out within a range of proportions. 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 is possible to process 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, and flame retardants are added to the aromatic polyester of the present invention during molding. 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 the elastic modulus can also be increased in many cases. 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 aromatic polyester 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 5.4 g of p-acetoxybenzoic acid in a polymerization test tube
(3.0 x 10 ^-2 mol), 16.0 g (7.0 x 10 ^-2 mol) of chlorohydroquinone diacetate, and 17.0 g (7.0 x 10 ^-2 mol) of 4,4'-diphenyldicarboxylic acid were prepared under the following conditions. Acetic acid depolymerization was performed. First, after reacting for 2.5 hours at 200 to 330°C in a nitrogen gas atmosphere,
Reduce the pressure to 1.0 mmHg at 330 °C and heat for an additional 0.5 h.
When the polycondensation was completed, almost the theoretical amount of acetic acid was distilled out and a brown polymer was obtained. The theoretical structural formula of this polymer is as follows,
The elemental analysis results of this polyester showed good agreement with the theoretical values as shown in Table 1. (m/n molar ratio = 30/70)

[Table] We also confirmed the optical anisotropy by placing this polyester on the sample stage of a polarizing microscope and increasing the temperature.
The liquid crystal onset temperature was 238°C, and good optical anisotropy was exhibited. Also, when this polymer was measured with a differential scanning calorimeter (Perkin Elmer type), the glass transition temperature was 86°C, the melting point was 269°C, and the cooling crystallization temperature was 216°C.
It was warm at ℃. This polyester was subjected to a Koka type flow tester and spun at a spinning temperature of 310℃ and a spinneret hole diameter of 0.3mmφ.
A spun yarn with a diameter of 0.06 mm was obtained. Melt viscosity shear rate
It was 5000 poise (298°C) at 3000 (1/sec). This spun yarn was processed at a frequency of 110Hz using a Leovibron DDV--EA manufactured by Toyo Baldwin Co., Ltd.
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 as high as 75 GPa at 30°C. Examples 2-16 p-acetoxybenzoic acid (), chlorhydroquinone diacetate (), methylhydroquinone diacetate (), 4,4'-diacetoxydiphenyl sulfide (), 4,4'-diacetoxybenzo Phenone (), 4,4'-diphenyldicarboxylic acid (), Terephthalic acid (), 4,
4'-Dicarboxydiphenyl ether (), 1,
2-bis(phenoxy)ethane-4,4'-dicarboxylic acid (), 1,2-bis(2-chlorophenoxy)ethane-4,4'-dicarboxylic acid (), 2,
6-Dicarboxynaphthalene (XI) (of which components () to () and components () to (XI) are charged in the same number of moles) was charged into a polymerization test tube, and the mixture was heated under the same conditions as in Example 1. A polycondensation reaction was carried out. The obtained polymers are as shown in Tables 2 and 3.
It showed good optical anisotropy at temperatures below 400°C. The melting points of some of the polymers were measured using a differential scanning calorimeter.

【table】

【table】

[Table] Values Among these, the polymer of Experiment No. 6 and the polymer of Experiment No. 8 were spun at 340℃ and 350℃ in the same manner as in Example 1.
It was found that the fiber has an extremely high modulus of elasticity of 106GPa at 0.1mmφ. <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 in various applications such as engineering plastics as metal substitute plastics.

Claims (1)

[Scope of Claims] 1 Consisting of the following structural units () and () or (), () and (), the unit ()
is 10 to 90 mol% of the total, the above structural unit () +
() accounts for 90 to 10 mol% of the total, the molar ratio of units ()/() is 100/0 to 30/70, and the shear rate is 3000 at (liquid crystal starting temperature + 60°C).
A melt-mouldable aromatic copolyester characterized by having a melt viscosity of 10 to 30,000 poise measured at (1/sec) and a liquid crystal onset temperature of 400°C or less. (However, R in the formula is one type of group selected from [formula] [formula] [formula] and [formula], and R' is [formula] and represents one or more groups selected from [Formula]. )