JP2638805B2 - Aromatic polyester with excellent fluidity and heat resistance - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an aromatic polyester which can be melt-molded at 400 ° C. or lower and can give a molded article having excellent fluidity, heat resistance and mechanical properties. It is.

<Prior art> In recent years, there has been an increasing demand for higher performance of plastics, and a number of polymers having various new properties have been developed and marketed. Among them, the polymer is characterized by a parallel arrangement of molecular chains. Optically anisotropic liquid crystal polymers have attracted attention because of their 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 obtained by copolymerizing 4,4'-dihydroxybiphenyl and phthalic acid are known.

However, the p-hydroxybenzoic acid homopolymers and copolymers often have too high a melting point and insufficient melt flowability. For this reason, a method of copolymerizing various components with p-hydroxybenzoic acid to lower its melting point has been studied. For example, a method in which phenylhydroquinone, terephthalic acid and / or 2,6-naphthalenedicarboxylic acid is copolymerized with p-hydroxybenzoic acid (Publication No. 55-500215), and p-hydroxybenzoic acid is mixed with 2,6-dihydroxynaphthalene A method of copolymerizing terephthalic acid (JP-A-54-50594) and a method of copolymerizing p-hydroxybenzoic acid with 2,6-dihydroxyanthraquinone and terephthalic acid (US Pat. No. 4,224,43)
No. 3), a method of copolymerizing p-hydroxybenzoic acid with 4,4'-dihydroxybiphenyl, terephthalic acid and isophthalic acid (JP-B-57-24407, JP-B-60-25046), tertiary alkyl Method of copolymerizing p-hydroxybenzoic acid with terephthalic acid and a nucleus-substituted hydroquinone containing a tertiary or aralkyl group, and method of copolymerizing p-hydroxybenzoic acid with hydroquinone and / or 4,4'-dihydroxybiphenyl or isophthalic acid (Japanese Patent Laid-Open No. 60-
235833) and the like. In addition,
JP-47870 proposes a polyester comprising p-oxybenzoic acid and 4,4'-dihydroxybiphenyl, terephthalic acid and isophthalic acid, and a polyester comprising p-oxybenzoic acid and hydroquinone, terephthalic acid and isophthalic acid. It also discloses that the polymer is solidified during the melt polymerization and is polymerized in a high-boiling solvent.

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

Among them, polyesters composed of p-oxybenzoic acid and 4,4'-dihydroxybiphenyl, terephthalic acid and isophthalic acid have a characteristic that heat resistance is relatively good, but the fluidity during polymerization is high. Is bad,
It has a drawback that it is difficult to polymerize only by melt polymerization, and it has also been found that mechanical properties are not sufficient.

Therefore, an object of the present invention is to obtain an aromatic polyester which can be melt-polymerized and melt-molded and has excellent fluidity and heat resistance as well as mechanical properties such as elastic modulus and toughness.

<Means for Solving the Problems> As a result of intensive studies to achieve the above object, the present inventors have found that aromatic dihydroxy containing p-hydroxybenzoic acid, 4,4'-dihydroxybiphenyl and t-butylhydroquinone. The present inventors have found that an aromatic polyester preferably meeting the above-mentioned object can be obtained by copolymerizing a compound and terephthalic acid or terephthalic acid and isophthalic acid, and have accomplished the present invention.

That is, the present invention comprises the following structural units (I) to (V), and the structural unit (I) is [(I) + (II) + (III) +
(IV)], the molar ratio of the structural units (II) and (III) [(II) / (III)] is 5 / 95-20 / 80, and the structural unit (IV) is the structural unit ( II), (III) and (IV) are 0 to 40 mol%, and the logarithmic viscosity when dissolved in pentafluorophenol at a concentration of 0.1 g / dl at 60 ° C.
An aromatic polyester having excellent fluidity and heat resistance of 1.0 to 20.0 dl / g is provided.

O-X-O (IV) (However, X in the formula is Represents one or more groups selected from The carbonyl groups of the structural unit (V) are in a para or meta position with each other,
More than 65 mol% is puta.

The total of the structural units (II), (III) and (IV) and the structural unit (V) are substantially equimolar. In the aromatic polyester of the present invention, the structural unit (I) is a structural unit generated from p-hydroxybenzoic acid.

The structural unit (II) is a structural unit generated from t-butylhydroquinone.

The structural unit (III) is a structural unit formed from 4,4'-dihydroxybiphenyl.

The structural unit (IV) is an aromatic dihydroxy compound such as hydroquinone, 4,4'-dihydroxybiphenyl ether, 2,6-dihydroxynaphthalene, 2,7-dihydroxynaphthalene, chlorohydroquinone, methylhydroquinone, or phenylhydroquinone, preferably hydroquinone. And at least one structural unit selected from aromatic dihydroxy compounds such as 2,6-dihydroxynaphthalene and phenylhydroquinone, particularly preferably hydroquinone. The structural unit (V) indicates a structural unit generated from terephthalic acid or terephthalic acid and isophthalic acid.

Of the terephthalic acid and / or isophthalic acid constituting the structural unit (V), it is essential that terephthalic acid is at least 65 mol%, and it is particularly preferable that terephthalic acid be at least 70 to 100 mol%. If the amount of terephthalic acid is less than 65 mol%, the heat resistance becomes insufficient and it is not practical.

The structural unit (I) includes structural units (I), (II), and (II)
It is essential that the content is 30 to 90 mol%, preferably 40 to 80 mol%, particularly preferably 50 to 90 mol%, based on the total of I) and (IV).
75 mol% is preferred. When the structural unit (I) exceeds 90 mol% or less than 30 mol%, based on the total of the structural units (I), (II), (III) and (IV), the fluidity becomes insufficient, It is not practical because melt polymerization and melt molding become difficult.

Also, the molar ratio of the structural units (II) and (III) [(II) /
(III)] is 5/95 or more and less than 20/80, and 10/90 or more
Less than 80 is preferred. When the molar ratio is less than 5/95, the fluidity is poor, and thus it is impractical. When the molar ratio is 20/80 or more, the heat resistance is lowered, so that it is not practical.

The structural unit (IV) is composed of the structural units (II), (III) and (I)
It is 0 to 40 mol%, preferably 5 to 35 mol%, based on the total of V). If it exceeds 40 mol%, the melting point of the aromatic polyester increases, the fluidity decreases, and melt polymerization and melt molding become difficult, which is not practical.

In the polycondensation of the aromatic polyester of the present invention, 4,4'-diphenyldicarboxylic acid, 3,3'-diphenyldicarboxylic acid, 3,4 '-Diphenyldicarboxylic acid, 2,2'-diphenyldicarboxylic acid, 1,2-bis (phenoxy) ethane-4,
Aromatic dicarboxylic acids such as 4'-dicarboxylic acid, 1,2-bis (2-chlorophenoxy) ethane-4,4'-dicarboxylic acid, alicyclic dicarboxylic acids such as hexahydroterephthalic acid, bisphenol A, bisphenol S , Resorcinol, aromatic dihydroxy compounds such as 44'-dihydroxydiphenyl sulfide, aromatic oxycarboxylic acids such as m-oxybenzoic acid and 2,6-oxynaphthoic acid, and p-
Aminophenol, p-aminobenzoic acid, and the like can be further copolymerized in a small proportion that does not impair the purpose of the present invention.

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 (1).
(4) method.

(1) acylated oxycarboxylic acid such as p-acetoxybenzoic acid; acylated aromatic hydroxy compound such as t-butylhydroquinone diacetate and 4,4'-diacetoxybiphenyl; and aromatic dicarboxylic acid such as terephthalic acid From acetic acid by a polycondensation reaction.

(2) A method of producing from an aromatic dihydroxy compound such as p-oxybenzoic acid, t-butylhydroquinone and 4,4'-dihydroxybiphenyl with an aromatic dicarboxylic acid such as terephthalic acid and acetic anhydride by a deacetic acid polycondensation reaction. .

(3) phenyl ester of p-oxybenzoic acid and t
-A method of producing from an aromatic dihydroxy compound such as butylhydroquinone or 4,4'-dioxybiphenyl and a diphenyl ester of an aromatic dicarboxylic acid such as terephthalic acid by dephenol polycondensation.

(4) A desired amount of diphenyl carbonate is reacted with an aromatic dicarboxylic acid such as p-oxybenzoic acid and terephthalic acid to form a diphenyl ester, and then an aromatic compound such as t-butylhydroquinone and 4,4'-dihydroxybiphenyl. A method in which a dihydroxy compound is added to produce by a phenol removal polycondensation reaction.

Typical catalysts used for the polycondensation reaction include metal compounds such as stannous acetate, tetrabutyl titanate, lead acetate, antimony trioxide, agnesium, sodium acetate, potassium acetate, and trisodium phosphate. Is valid.

The melt viscosity of the aromatic polyester of the present invention is 50 to 50.
15,000 poise is preferable, and 100 to 10,000 poise is more preferable.

The melt viscosity is a value measured by a Koka type flow tester under the condition of (liquid crystal onset temperature + 40 ° C) and a shear rate of 3,000 (1 / sec).

The logarithmic viscosity of these aromatic polyesters is determined by dissolving in pentafluorophenol at a concentration of 0.1 g / dl at 60 ° C., and the value is 1.0 to 10.0 dl / g, particularly 2.0 to 6.0 dl / g.
It is preferably g.

The aromatic polyester thus obtained has a melting point of 40.
As low as 0 ° C or less, it can be subjected to ordinary melt molding such as extrusion molding, injection molding, compression molding, blow molding, etc.
It can be processed into films, three-dimensional molded products, containers, hoses and the like.

In addition, for the aromatic polyester of the present invention, glass fiber, carbon fiber, reinforcing agents such as asbestos, filler, nucleating agent,
Adds additives such as pigments, antioxidants, stabilizers, plasticizers, lubricants, mold release agents and flame retardants, and other thermoplastic resins to impart desired properties to the molded article of the aromatic polyester of the present invention. can do.

The strength of the molded article thus obtained can be increased by heat treatment, and the elastic modulus can be increased in many cases.

This heat treatment causes the molded article to be placed in an inert atmosphere (eg, nitrogen,
The heat treatment can be carried out at a temperature lower than the melting point of the polymer in an atmosphere containing argon (helium or water vapor), in an oxygen-containing atmosphere (eg, air), or under reduced pressure. This heat treatment may or may not be carried out under tension, and can be carried out for several tens of minutes to several days.

The molded article obtained from the aromatic 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 by way of examples.

Example 1 In a test tube for polymerization, 51.89 g of p-acetoxybenzoic acid (I) was added.
(28.8 x 12 ^-2 mol), t-butyl hydroquinone diacetate (II) 4.00 g (1.60 x 10 ^-2 mol), 4,4'-diacetoxybiphenyl (III) 21.62 g (8.00 x 10 ^-2 mol) ,
Hydroquinone diacetate (IV) 3.11 g (1.60 × 10 ^-2
Mol), 13.95 g (8.40 × 10 ^-2 mol) of terephthalic acid (V), and 4.65 g (2.80 × 10 ^-2 mol) of isophthalic acid (VI) as (I) / [(I) + (II) + (III) + (IV)] is 72 mol%, the molar ratio of (II) / (III) is 17/83, and (IV) /
[(II) + (III) + (IV)) was 14.3 mol%, (V) /
[(V) + (VI)] was charged so as to be 75 mol%, and deacetic acid polymerization was carried out under the following conditions. First, after reacting at 250 to 340 ° C. for 3.0 hours in a nitrogen gas atmosphere, the temperature was raised to 360 ° C., the pressure was reduced to 1.5 mmHg, and the mixture was further heated for 1.0 hour to perform a polycondensation reaction to obtain a brown polymer. Further, five batch polymerizations were carried out under the same conditions, and the polymer was recovered. The polymer was pulverized with a pulverizer manufactured by Horai Co., Ltd.

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

l / m / n / o / p = 72/4/20/4/28 However, it was calculated from O (%) = 100 (%)-C (%)-H (%).

The polyester was placed on a sample stage of a modified microscope and heated to apply shear stress, and the optical anisotropy was confirmed. As a result, good optical anisotropy was exhibited at 313 ° C. or higher.

Sumitomo Nestal injection molding machine
40/25 (manufactured by Sumitomo Heavy Industries, Ltd.), under conditions of cylinder temperature 350 ° C and mold temperature 120 ° C, 1/8 "thickness X1 / 2" width X
A 5 ″ long test piece and a 1/4 ″ thick X2 · 1/2 ″ long impact test piece were prepared. The test pieces were strained at a strain rate of 1 mm / cm using Toyo Baldwin Tensilon UTM-100.
When the flexural modulus was measured under the conditions of a distance between spans of 50 mm for 1 minute, it was 16.8 GPa. The Izod impact value (cut notch) was as high as 20 kg · cm / cm. Further, when the heat deformation temperature of a 1/8 ″ thick test piece was measured using a heat deformation measuring device manufactured by Toyo Seiki, it was found to have excellent heat resistance of 265 ° C. (18.56 kg / cm ² ).

The polymer had a melt viscosity of 353 ° C and a shear rate of 3,000.
The fluidity at 4,500 poise (1 / sec) was extremely good. The logarithmic viscosity of this polymer was 4.2 dl / g.

The polymer was further polymerized for 5 batches under the same conditions, and the polymer was pulverized using a pulverizer manufactured by Hora Co., Ltd.

Examples 2 to 15 Comparative Examples 1 to 3 p-acetoxybenzoic acid (A), t-butylhydroquinone diacetate (B), 4,4'-diacetoxybiphenyl (C), hydroquinone diacetate, (D-
1), 4,4'-diacetoxybiphenyl ether (D-
2), 2,6-diacetoxynaphthalene (D-3), 2,7-
A diacetate component comprising diacetoxynaphthalene (D-4), chlorohydroquinone diacetate (D-5), methylhydroquinone diacetate (D-6), and phenylhydroquinone diacetate (D-7); and terephthalic acid (E) , And a dicarboxylic acid component composed of isophthalic acid (F) were combined as shown in Table 2 and charged in a polymerization tube such that the diacetate component = the number of moles of the dicarboxylic acid component. The polycondensation reaction was carried out in the same manner as in Example 1. The liquid crystal onset temperature and melt viscosity (logarithmic viscosity) of the obtained polymer were measured.

Table 2 shows that the polymer of the present invention has good fluidity and high heat resistance, but the composition other than the present invention (Comparative Examples 1 and 2) has poor fluidity and cannot be solidified during polymerization or spinning is impossible. Yes,
It is impossible to obtain a molded product with high toughness and high elasticity, or the fluidity is poor even if the heat resistance is good (Comparative Example 3)
It is clear that the object of the present invention cannot be achieved.

<Effect of the Invention> The aromatic polyester of the present invention can be melt-molded at 400 ° C. or lower, and a molded article obtained from the aromatic polyester of the present invention has fluidity, heat resistance, and mechanical properties. It can be used in various fields such as electronic and electric equipment parts.

Claims (1)

(57) [Claims] (1) It comprises the following structural units (I) to (V), wherein the structural unit (I) is 30 to 90 mol based on the total of the structural units (I), (II), (III) and (IV). %, Structural unit (II)
The molar ratio of [(II) / (III)] is 5 to 95 or more
Less than 20/80, structural unit (IV) is structural unit (II), (III)
And 0 to 40 mol% based on the sum of
An aromatic polyester excellent in fluidity and heat resistance having a logarithmic viscosity of 1.0 to 20.0 dl / g when dissolved in pentafluorophenol at a concentration of 0.1 g / dl in pentafluorophenol. O-X-O (IV) (Where X is Represents one or more groups selected from The carbonyl groups of the structural unit (V) are in a para or meta position with each other,
More than 65 mol% of it is in the para position. The total of the structural units (II), (III) and (IV) and the structural unit (V) are substantially equimolar. )