JPH0681783B2 - Aromatic polyester with improved fluidity - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Field of Industrial Application> The present invention relates to an aromatic polyester capable of being melt-molded at 400 ° C. or lower and capable of giving a molded article having excellent fluidity, heat resistance and mechanical properties. is there.

<Prior Art> In recent years, the demand for higher performance of plastics has increased more and more, and many polymers having various new performances have been developed and put on the market, and in particular, they are characterized by a parallel arrangement of molecular chains. Attention has been paid to the optically anisotropic liquid crystal polymer having excellent mechanical properties.

As the liquid crystal polymer, a wholly aromatic polyester is widely known. For example, a homopolymer of p-hydroxybenzoic acid and a copolymer of 4,4'-dihydroxybiphenyl and phthalic acid are known.

However, the melting point of these p-hydroxybenzoic acid homopolymers and copolymers are too high and their melt flowability is often insufficient. Therefore, a method of copolymerizing various components with p-hydroxybenzoic acid and lowering the melting point thereof has been investigated. For example, p-hydroxybenzoic acid is mixed with phenylhydroquinone, terephthalic acid and / or 2,6.
-A method of copolymerizing naphthalenedicarboxylic acid (published patent publication 55-500215), a method of copolymerizing p-hydroxybenzoic acid with 2,6-dihydroxynaphthalene and terephthalic acid (JP-A-54-50594) and p-hydroxy For benzoic acid
A method of copolymerizing 2,6-dihydroxyanthraquinone and terephthalic acid (U.S. Pat. No. 4,224,433), a method of copolymerizing p-hydroxybenzoic acid with 4,4'-dihydroxybiphenyl, terephthalic acid and isophthalic acid (JP-B-57). −2440
7, JP-B-60-25046), a method of copolymerizing phenylhydroquinone and terephthalic acid with p-hydroxybenzoic acid (US Pat. No. 4,242,496) and the like have been proposed.

Further, a method of copolymerizing terephthalic acid with p-hydroxybenzoic acid and 4,4'-dihydroxybiphenyl and t-butylhydroquinone has been proposed (JP-A-62-132920), but the heat resistance is poor. Moreover, since the intrinsic viscosity is low and the molecular weight is small, it cannot be used in actual use. On the other hand, a method has been proposed in which p-hydroxybenzoic acid is copolymerized with 4,4'-dihydroxybiphenyl, t-butylhydroquinone and terephthalic acid to obtain a polymer having a high intrinsic viscosity and a sufficiently increased molecular weight. 62-1647
19).

<Problems to be Solved by the Invention> However, although many of the aromatic polyesters obtained by these methods have relatively low melting points of 400 ° C. or less, they have insufficient fluidity or insufficient heat resistance. Therefore, further improvement of fluidity and higher heat resistance are desired.

Among them, polyester composed of p-oxybenzoic acid, 2,6-dihydroxynaphthalene and terephthalic acid (Japanese Patent Laid-Open No. 54-50594) is characterized by good fluidity, but has a heat distortion temperature. It was found that the heat resistance was low and the heat resistance was insufficient, and that 2,6-dioxynaphthalene or a derivative thereof was extremely sublimated during polymerization, so that a polymer having a uniform composition could not be obtained.

On the other hand, polyester composed of p-oxybenzoic acid, 4,4'-dihydroxybiphenyl, terephthalic acid and isophthalic acid has a characteristic of relatively good heat resistance, but has a fluidity during polymerization. It has been found that it is poor and has a drawback that it is difficult to polymerize only by melt polymerization.

Further, it has been found that even in the case of a copolymerization system of p-hydroxybenzoic acid, 4,4'-dihydroxybiphenyl and t-butylhydroquinone, it is necessary to further improve fluidity when molding thin-walled molded articles. .

<Means for Solving Problems> The inventors of the present invention have conducted extensive studies to achieve the above object, and as a result, p-hydroxybenzoic acid, 4,4′-dihydroxybiphenyl, t-butylhydroquinone and phenylhydroquinone have been obtained. , 2,6-dihydroxynaphthalene, 2,7-dihydroxynaphthalene, and two or more aromatic dihydroxy compounds selected from hydroquinone, terephthalic acid and / or isophthalic acid, and 4,4'-diphenyl ether dicarboxylic acid It has been found that an aromatic polyester which meets the above object can be obtained by polymerization, and the present invention has been completed.

That is, the present invention comprises the following structural units (I) to (IV), wherein the structural unit (I) is 40 to 90 mol% of [(I) + (II)], and the structural unit [(III) + (IV)] ] Is [(I) + (I
I)] in an amount of 60 to 10 mol% and a logarithmic viscosity of 1.0 to 20.0 dl / g when dissolved in pentafluorophenol at a concentration of 0.1 g / dl at 60 ° C. Group polyester is provided.

(However, X in the formula is The carbonyl group of the structural unit (III) is in the para or meta position with respect to each other, and 65 mol% or more of the carbonyl groups are in the para position. The structural unit (II) and the structural unit [(III) + (IV)] are substantially equimolar. ) In the aromatic polyester of the present invention, the structural unit (I) is a structural unit of a polyester produced from p-hydroxybenzoic acid.

The structural unit (II) is produced from two or more kinds selected from 4,4'-dihydroxybiphenyl, t-butylhydroquinone, phenylhydroquinone, 2,6-dihydroxynaphthalene, 2,7-dihydroxynaphthalene and hydroquinone. It is a structural unit.

Of these, preferred are structural units formed from 4,4'-dihydroxybiphenyl and hydroquinone, 4,4'-dihydroxybiphenyl and / or hydroquinone, and t-butylhydroquinone and / or phenylhydroquinone.

The structural unit (III) is a structural unit produced from terephthalic acid and / or isophthalic acid, and the structural unit (IV) is a structural unit produced from 4,4′-diphenyl ether dicarboxylic acid.

The carbonyl groups of the structural unit (III) are in a para position or a meta position with respect to each other, and it is essential that 65 mol% or more of them be in the para position.

Further, when used together with as an aromatic dihydroxy compound, the dicarboxylic acid of the structural unit (III) is
Since it has good heat resistance, a compound corresponding to the para position, that is, terephthalic acid is used in an amount of 80 mol% or more, particularly preferably 100%.

In the above structural unit (I), 40 to 90 mol% of [(I) + (II)] structural unit [(III) + (IV)] is [(I) + (II)].
Of 60 to 10 mol% is essential, and if the structural unit (I) exceeds 90 mol% or less than 40 mol% of [(I) + (II)], the fluidity is insufficient. Therefore, it is not practical.

The structural unit (IV) is an essential component of less than 15 mol% of the total amount, preferably 0.5 mol% or more and less than 12 mol% of the total amount, particularly preferably 1 to 10 mol%.

When the structural unit (IV) is not copolymerized, or (IV) is 15
When it is more than mol%, the fluidity or heat resistance is not improved,
Is insufficient.

The aromatic polyester of the present invention can be produced according to a conventional polyester polycondensation method, and the production method is not particularly limited, but typical production methods include, for example, the following (1) to
(4) method.

(1) Deacetic acid polycondensation reaction from an acylated product of a hydroxycarboxylic acid such as p-acetoxybenzoic acid or an acylated product of an aromatic hydroxy compound such as 4,4′-diacetoxybiphenyl and an aromatic dicarboxylic acid such as terephthalic acid. Manufacturing method according to.

(2) A method for producing from an aromatic dihydroxy compound such as p-hydroxybenzoic acid or 4,4'-dihydroxybiphenyl, an aromatic dicarboxylic acid such as terephthalic acid and acetic anhydride by a deacetic acid polycondensation reaction.

(3) A method for producing from a phenyl ester of p-hydroxybenzoic acid and an aromatic dihydroxy compound such as 4,4'-dihydroxybiphenyl and a diphenyl ester of an aromatic dicarboxylic acid such as terephthalic acid by dephenol polycondensation.

(4) After reacting an aromatic dicarboxylic acid such as p-hydroxybenzoic acid and terephthalic acid with a desired amount of diphenyl carbonate to form each diphenyl ester,
A method for producing by a dephenol polycondensation reaction by adding an aromatic dihydroxy compound such as 4,4'-dihydroxybiphenyl.

When dihydroxynaphthalene is used in the methods (1) to (4), it is preferable to polymerize using diacetoxynaphthalene.

Typical catalysts used in the polycondensation reaction are metal compounds such as stannous acetate, tetrabutyl titanate, lead acetate, antimony trioxide, magnesium, sodium acetate, potassium acetate and trisodium phosphate, and especially potassium acetate. It is valid.

Further, the melt viscosity of the aromatic polyester of the present invention is 50 to 1
5,000 poise is preferable, and 100 to 10,000 poise is particularly preferable.

The melt viscosity is a value measured by a Koka flow tester under the condition of (liquid crystal starting temperature + 40 ° C) and shear rate of 1,000 (1 / sec).

The logarithmic viscosity of these aromatic polyesters is 1.0 to 20.0 dl / g when dissolved at a concentration of 0.1 g / dl in pentafluorophenol at 60 ° C., preferably 1.0 to 10.0 dl / g, particularly preferably 2.0 to 6.0 dl / g is preferable.

When polycondensing the aromatic polyester of the present invention, in addition to the components constituting the above (I) to (IV), 2,2'-diphenyldicarboxylic acid, 1,2-bis (phenoxy) ethane- Aromatic dicarboxylic acids such as 4,4′-dicarboxylic acid, 1,2-bis (2-chlorophenoxy) ethane-4,4′-dicarboxylic acid, alicyclic dicarboxylic acids such as hexahydroterephthalic acid, bisphenol A, Aromatic dihydroxy compounds such as bisphenol S, resorcin, 4,4'-dihydroxydiphenyl sulfide, m-hydroxybenzoic acid,
Aromatic hydroxycarboxylic acids such as 2,6-hydroxynaphthoic acid and p-aminobenzoic acid can be further copolymerized in a small proportion within a range not impairing the object of the present invention.

The aromatic polyester of the present invention thus obtained has a melting point of 400.
As low as ℃ or less, it can be used in common melt molding such as extrusion molding, injection molding, compression molding, blow molding, and can be processed into fibers, films, three-dimensional molded products, containers, hoses, etc. .

At the time of molding, with respect to the aromatic polyester of the present invention,
Reinforcing agents such as glass fiber, carbon fiber, asbestos, fillers, nucleating agents, pigments, antioxidants, stabilizers, plasticizers, lubricants,
Additives such as release agents and flame retardants and other thermoplastic resins can be added to impart desired properties to the molded article.

The use of the molded product obtained from the aromatic polyester of the present invention is not limited. In addition to general electronic parts and structural materials, it can be preferably used for IC sealants, speaker diaphragms, and magnetic materials.

The molded product thus obtained can be increased in strength by heat treatment and the elastic modulus can 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 an oxygen containing atmosphere (eg air) or under reduced pressure at a temperature below the melting point of the polymer. . This heat treatment may or may not be performed under tension and can be performed for several tens of minutes to several days.

The molded article obtained from the aromatic compound of the present invention has good optical anisotropy and heat resistance due to its parallel molecular arrangement, and has extremely excellent mechanical properties and fluidity.

<Example> Hereinafter, the present invention will be described in more detail with reference to Examples.

Example 1 In a test tube for polymerization equipped with a stirring blade, 51.89 g (28.8 x 10 ^-2 mol) of p-acetoxybenzoic acid (A) and 21.62 g (8.0 x 10) of 4,4'-diacetoxybiphenyl (B). ^-2 mol), diacetoxyhydroquinone (C) 7.76 g (4.0 x 10 ^-2 mol), terephthalic acid (F) 13.29 g (8.0 x 10 ^-2 mol),
4,4'-Diphenyl ether dicarboxylic acid (H) 10.32g
(4.0 × 10 ⁻³ mol) was charged, and deacetic acid polymerization was carried out under the following conditions. First, after reacting in a nitrogen gas atmosphere at 250 to 340 ° C for 3.0 hours, the temperature was raised to 350 ° C, the pressure was reduced to 0.5 mmHg, the temperature was further raised to 370 ° C, and the polycondensation reaction was performed for 1.0 hour to brown. Got the polymer of.

The theoretical structural formula of this polymer is as follows, and the elemental analysis results are as shown in Table 1, showing good agreement with the theoretical values.

Structural unit (I) () is 70 mol% of the whole, structural unit (I
I) (m ₁ + m ₂ ) is 20 mol% of the whole, structural unit (III) (n ₁
+ N ₂ ) is 10 mol% of the whole.

However, it was calculated from O (%) = 100 (%)-C (%)-H (%).

In addition, when this polymer was placed on the sample stage of a polarization microscope and heated to apply shear stress, the optical anisotropy was confirmed,
Good optical anisotropy was shown at 350 ° C or higher.

The melt viscosity of this polymer is 390 ° C and the shear rate is 1,000.
It had good fluidity at 890 poise (1 / sec). 60% of this polymer in a 0.1 g / dl solution in pentafluorophenol
The logarithmic viscosity measured at ° C was 3.4 dl / g.

This polymer was further subjected to 5 batch polymerization under the same conditions,
The polymer was crushed with a crusher manufactured by Tomoki Co., Ltd.

Then, this polymer was subjected to Sumitomo connector injection molding machine Promat 40/25 (Sumitomo Heavy Industries, Ltd.), 1/8 "thickness x 1/2" under the conditions of cylinder temperature 390 ° C and mold temperature 30 ° C.
A test piece with a width of 5 ″ was created, and the heat distortion temperature of a 1/8 ″ thick test piece was measured using a heat distortion measuring device manufactured by Toyo Seiki. It was excellent at 260 ℃ (18.56kg / cm ² ). It had heat resistance.

Comparative Example 1 In a polymerization test tube equipped with a stirring blade, 51.89 g (28.8 × 10 ^-2 mol) of p-acetoxybenzoic acid (A) and 21.62 g (8.0 × 10) of 4,4′-diacetoxybiphenyl (B). ^-2 mol), diacetoxyhydroquinone (C) 7.76 g (4.0 × 10 ^-2 mol) and terephthalic acid (F) 19.94 g (12.0 × 10 ^-2 mol) were added, and deacetic acid was applied under the same conditions as in Example 1. Polymerization was performed.

During depressurization at 370 ° C., the polymer was wrapped around a stirring blade and solidified, making it impossible to continue the polymerization. For this reason, no polymer suitable for practical use has been obtained. This indicates that the polymer has a poor fluidity as the degree of polymerization increases during the polymerization.

Examples 2 to 4 and Comparative Example 2 (A), (B), (C), as the polymerization raw material,
Polymerization was performed using diacetoxy-t-butylhydroquinone (D) and diacetoxyphenylhydroquinone (E) in addition to (F) and (H), and the same evaluation as in Example 1 was performed. These are summarized in Table 2. The melt viscosity was measured at a liquid crystal starting temperature of + 40 ° C. and a shear rate of 1000 s ⁻¹ . The cylinder temperature during injection molding was set to the liquid crystal starting temperature + 40 ° C.

The polymers of the present invention are all polymers having improved heat resistance and fluidity.

It is not clear why such effects occur, but
A small amount of 4'-diphenyl ether dicarboxylic acid, which has flexibility and good heat resistance, is incorporated into the polymer chain, so that the packing between polymer chains is loosened to the extent that heat resistance is not adversely affected. It is presumed that this is because it is done.

<Effects of the Invention> According to the present invention, an aromatic polyester having good heat resistance and improved fluidity can be provided.

Claims (1)

[Claims] 1. The following structural units (I) to (IV), wherein the structural unit (I) is 40 to 90 mol% of [(I) + (II)] and the structural unit (IV) is [(I) + (II)] as an essential component in an amount of less than 15 mol%, and the structural unit [(III) + (IV)] is [(I)]
+ (II)] in an amount of 60 to 10 mol% and having a logarithmic viscosity of 1.0 to 20.0 dl / g when dissolved in pentafluorophenol at a concentration of 0.1 g / dl at 60 ° C. Aromatic polyester. (However, X in the formula is The carbonyl group of the structural unit (III) is in the para or meta position with respect to each other, and 65 mol% or more of the carbonyl groups are in the para position. The structural unit (II) and the structural unit [(III) + (IV)] are substantially equimolar. )