JPH03221521A - Wholly aromatic polyester, film and molded product thereof - Google Patents

Abstract

PURPOSE:To obtain the subject melt moldable polyester, composed of respective specific four kinds of recurring units, having respective specified melting point and reduced specific viscosity and convertible from a crystal state into an optically isotropic melt by and capable of providing films and molded products with hardly any anisotropy of physical properties. CONSTITUTION:The objective polyester, obtained by polymerizing p- hydroxybenzoic acid, etc., hydroquinone, etc., isophthalic acid, etc., and 1,4-bis(hydroxybenzoyloxy)butane or 1,4-bis(phenoxy)butane-4,4'-dicarboxylic acid, etc., so that the amounts (mol%) x<1> and y<1> of recurring units expressed by formula I in formula V are preferably within the range surrounded by curves (A) and (C) or the amounts (mol%) x<2> and y<2> of recurring units expressed by formula II in formula VI are preferably within the range surrounded by curves (D) and (F) and having the recurring units expressed by formulas I to IV, <=350 deg.C melting point and >=0.4dl/g reduced specific viscosity.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a novel wholly aromatic polyester and a film or molded article thereof. More specifically, the melting point is approximately 350°C.
The following relates to a wholly aromatic polyester which changes from a crystalline state to an optically isotropic melt upon melting, and to a film or molded article comprising the wholly aromatic polyester and having little anisotropy in physical properties. The wholly aromatic polyester can be melt-molded and has excellent and well-balanced physical and chemical properties, so it is useful not only for films and molded products but also as a material for fibers.

(Conventional technology) In recent years, with the advancement of technology, there has been an increasing demand for materials with high physical and chemical performance.
For example, p-hydroxybenzoic acid, 2-hydroxy-6-
Various liquid crystal polymers have been proposed that contain naphthoic acid, terephthalic acid, hydroquinone, etc. as main components and exhibit optical anisotropy when melted.

Compared to polyethylene terephthalate, which has been widely used in various fields such as resins, fibers, and films, this liquid crystal polymer certainly has a higher Young's modulus and melting point, and can be said to be an excellent material. Due to intermolecular forces, melt molding tends to cause orientation in a uniaxial direction, resulting in anisotropy between the orientation direction (mechanical axis direction) and the physical properties in a direction perpendicular thereto.

Generally, adding reinforcing materials or fillers such as glass fiber or talc is used as a method to alleviate this physical anisotropy, but there is a limit to the amount of reinforcing materials and fillers that can be added. It has the disadvantage that it cannot be used in the film field because it impairs the quality of the film.

On the other hand, polyenalene 2,6-naphthalate, 4,4"-(ethylenedioxy)benzoic acid, and ethylene glycol are optically isotropic in the melt and have higher aromaticity and molecular rigidity than polyethylene terephthalate. Polyesters obtained by condensing are known. However, although these do not have physical anisotropy, the above-mentioned properties are still far from satisfactory.

Furthermore, in the case of polyarylates (for example, polyesters consisting of terephthalic acid residues, isophthalic fII residues, and 2,2-bis(4hydroxyphenyl)propane residues), there is no physical anisotropy and heat resistance is improved. However, because the polymer was inferior, it had problems with solvent resistance, oil resistance, etc.

Erdesir et al. synthesized various wholly aromatic polyesters composed of hydroxybenzoic acid, hydroquinone, and isophthalic acid, and produced poly(p-oxybenzoyl) part (hereinafter abbreviated as part A) and poly(p-phenylene isophthalate). The molar ratio of part (hereinafter abbreviated as part B) is 43157
(=Part A/Part B) It has been reported that after melting, the following composition changes from a crystalline state to an optically isotropic melt (Polym
er, 29, 441 (1986)), L. Kashi, A.
No detailed study has been conducted regarding the total acid content of 33 mol% or less, and no reports have been made regarding the anisotropy of physical properties.

If a wholly aromatic polyester with a melting point of about 350°C or less and which changes from a crystalline state to an optically isotropic melt upon melting can be obtained, it can be easily molded, has excellent physical properties, and has different physical properties. It is promising as a well-balanced film or molded product with little orientation.

(Intelligence B to be Solved by the Invention) As described above, in the prior art, it has not yet been possible to obtain a wholly aromatic polyester polymer that can be melt-molded and that changes from a crystalline state to an optically isotropic melt upon melting. Not yet. Furthermore, films and molded products with less anisotropy of physical properties are known from such polymers.

(Means for Solving the Problems) In order to solve the above problems, the present inventors have diligently researched and considered, and as a result, have discovered that the above objects can be achieved with a limited composition that is achieved by a combination of specific monomers, We have finally completed the present invention.

That is, the present invention relates to the following general formulas (I) to (IV) to (IV
) as a repeating structural unit, a wholly aromatic polyester having a melting point of about 350° C. or less, a reduced specific viscosity of 0.4 dl/g or more, and changing from a crystalline state to an optically isotropic melt upon melting. It is.

(IV) (However, R1 is an ether group or a carbonyl group, R1
represents a carbonyl group, and n is 0 or 1.) The present invention also relates to films and molded articles obtained from the wholly aromatic polyester.

The present invention will be explained in more detail below. The fully aromatic polyester in the present invention is represented by the following formula: P-hydroxybenzoic acid or its derivative (V), hydroquinone or its derivative (Vl), isophthalic acid or its derivative ( (2) and 1,4-bis(hydroxybenzoyloxy)butane or its derivative or 1,4-bis(phenoxy)butane-4,4''-dicarboxylic acid or its derivative (VW) at the reduction ratio of the polymer. Viscosity is 0.4dl
/g or more.

Or in the above formula, R3 is a hydrogen atom, a lower alkanoyl group having 7 or less carbon atoms, or a benzoyl group, and R4 is a hydrogen atom or an aryl group having 6 to 12 carbon atoms, and R5,Rh
, R9 and R'. are lower alkanoyl groups and benzoyl groups having 7 or less carbon atoms, respectively; Hff, Re,
R■ and R port each have a hydrogen atom or 6 carbon atoms
~12 aryl groups.

Specific examples of the compounds represented by formulas (V), (Vl), (■) and (■) include p-hydroxybenzoic acid, p-formyloxybenzoic acid, p-acetoxybenzoic acid, and p-propylcarbonyl. Oxybenzoic acid, p-benzoyloxybenzoic acid, phenyl p-hydroxybenzoate, tolyl p-hydroxybenzoate, p-butylphenyl p-hydroxybenzoate, β-naphthyl p-hydroxybenzoate, hydroquinone, 1,4-di Acetoquinobenzene, 14-dipropylcarbonyloxybenzene, 1
4-dibenzoyloxybenzene, isophthalic acid, diphenyl isophthalate, ditolyl isophthalate, diphenyl isophthalate, diphenyl isophthalate, diphenyl isophthalate, 14-bis(phenoxy)butane-4,4°dicarboxylic acid, 1 .4-bis(phenoxy)butane-4
Diphenyl 4′-dicarboxylate, 14-bis(phenoxy)butane-4,4′-dicarboxylic acid ditolyl, 1,4
-bis(phenoxy)butane-4,4′-dicarboxylic acid di p-butylphenyl, 1,4-bis(phenoxy)butane-4,4′-dicarboxylic acid di p-chlorophenyl,
1.4-bis(hydroxybenzoyloxy)butane, 1
．． 4-bis(acetoxyhenzoyloxy)butane, 1.
4-bis(proboxyhenzoyloxy)butane, 1.4
-bis(dibenzoyloxy)butane and the like.

The fully aromatic polyester of the present invention has a melting point of about 350°C or less,
In addition, the molar ratio of the repeating structural units (1) to NV) is very important in order to change from a crystalline state to an optically isotropic melt by melting.

When ill in the above-mentioned formula (IV) is an ether group and R2 is a carbonyl group, when the mole % of each of the repeating units (1) to (■) is expressed as χ1 and yl as shown below, χ1
and yl are preferably within the shaded area in FIG. 1 (the range surrounded by curves A and C).

If the values of χ (χ1 and y + represent mol%) and yl are outside this range, the melting point of the resulting polymer will be lower than 3.
If the temperature is higher than 50°C, or the melt becomes an optically anisotropic melt.

In particular, the values of χ1 and yl are curves B and C in Figure 1.
It is preferable that the range is within the range enclosed by .

Further, 81 in the formula NV) is a carbonyl group, and R1
is an ether group, the repeating units (1) to (IV)
When the number of moles of each of is expressed as χ2 and yZ in the box below, χ
2 and y2 are preferably within the shaded area in FIG. 2 (the range surrounded by the curved line and curve F).

(χ2 and yZ represent mol%) χχ and yZ
If the value of is outside the range, the desired polyester cannot be obtained for the same reason as mentioned above. In particular, if the χ2 and yZ values are within the range surrounded by curve ME and curve F in Figure 2. preferable.

The wholly aromatic polyester of the present invention can be produced in accordance with conventionally known polyester polycondensation methods.

Although there are no particular restrictions on the manufacturing method, typical manufacturing methods include the following methods 1) and 2).

(1) A method for producing the above-mentioned ester compound of aromatic hydroxycarboxylic acid, the above-mentioned ester compound of aromatic diol, and the above-mentioned aromatic dicarboxylic acid by demonocarboxylic acid polycondensation reaction.

(2) A method for producing the phenyl ester compound of the aromatic hydroxycarboxylic acid, the aromatic diol, and the diphenyl ester compound of the aromatic dicarboxylic acid by dephenol polycondensation reaction.

In both methods, a conventionally known phosphorus compound can be used as a catalyst or decomposition inhibitor, if necessary. Also,
Solid phase polymerization may be performed if necessary.

The wholly aromatic polyester thus obtained was 380
Melt molding is possible at temperatures below ℃. Specifically, a film or an injection molded product can be obtained using an ordinary melt extrusion device, but a solvent casting method, a compression molding method, or the like may also be used.

Films and molded products that are superior to the fully aromatic polyester of the present invention have excellent heat resistance, and have a physical property ratio of 0.7 to 163 in the mechanical axis direction and the direction perpendicular to it, which is said to have little physical property anisotropy. The physical property ratio between the 0 mechanical axis direction and the direction perpendicular thereto is preferably 0.8 or more and 1.2 or less,
Particularly preferred is 0.9 or more and 1.1 or less.

It is also possible to heat-treat films and molded products at temperatures below their melting point to increase their molecular weight and crystallize them, thereby improving their physical properties.

The wholly aromatic polyester of the present invention requires various thermoplastic polymers, stabilizers such as ultraviolet absorbers, antioxidants, plasticizers, fillers, or reinforcing materials such as glass fiber, carbon fiber, ashest, etc. It may be blended accordingly.

The measurement method used in the present invention will be explained below.

Melting point: Measured using Birkin Elmer's DSC-7 at a heating rate of 20°/min.

Optical properties: Measured using a Renkuro melting point measuring instrument manufactured by Yanagimoto Seisakusho under crossed Nicol conditions by observing the brightness and darkness of the field of view in the molten state of a sample sandwiched between two glass plates. When it becomes a dark field, it is an optically isotropic melt, and when it becomes a bright field, it is an optically anisotropic melt.

Reduced specific viscosity: 1.0g/using a mixed solvent of p-chlorophenol/tetrachloroethane (75/25 weight ratio)
Measurements were made at 30°C at the concentration of di.

Tensile test: Measured using Tensilon manufactured by Toyo Baldwin.

(Examples) The present invention will be specifically illustrated below using Examples, but the present invention is not limited by these.

Example 1 5.48 g of p-acetoxybenzoic acid (3,04 xi
o-”mol), 1,4-diacetoxybenzene 11
゜40 g (5,87X10-”% le), iso7
9 Ruic acid 10.26 g (6,18×10-” mole),
1.4-bis(acetoxybenzoyloxy)butane1.
28 g (3,09xlO-gomol) and 40 m acetic acid
1 was added, heated under a nitrogen atmosphere, and reacted at 305° C. for 1 hour while removing acetic acid produced as a result of the reaction. Thereafter, the pressure of the system was gradually reduced, and the reaction was carried out for 1 hour at an absolute pressure of about 0.5-8 g over 20 minutes.The zero reaction temperature was then raised to 350°C, and the reaction was continued in this state for an additional 10 minutes. The taken out polymer was pulverized and dried, and then solid-phase polymerized at 230°C.As shown in Table 1, the reduced specific viscosity of the obtained polymer was 2.82 dl/
g and had a melting point of 319°C, and upon melting, it changed from a crystalline state to an optically isotropic melt.

This polymer was heat pressed at 350°C to obtain an unstretched film. The radial direction from the center of the film was defined as the mechanical axis direction, and the physical properties in the mechanical axis direction and the direction perpendicular to this direction were measured using a dumbbell-shaped sample.

As a result, as shown in Table 1, a film with a physical property ratio close to 1 and almost no physical anisotropy was obtained.

Examples 2 to 7 and Comparative Examples 1 to 3 Polymerization was carried out in exactly the same manner as in Example 1 except for the conditions shown in Table 1. However, in Example 7 and Comparative Examples 2 and 3, solid phase polymerization was not performed. The melting points, optical properties, and physical property ratios of the resulting polymers are also listed in Table 1. The infrared spectra of the polymers obtained in Example 1.7 and Comparative Example 1 are shown in FIGS. 3, 4, and 5, respectively.

The following margin (effects of the invention) The wholly aromatic polyester of the present invention having the above structure can be melt-molded and changes from a crystalline state to an optically isotropic melt upon melting, so it has excellent physical and chemical properties. However, it is possible to obtain a well-balanced film or molded product with less anisotropy of physical properties, which will greatly contribute to the industrial world.

[Brief explanation of drawings]

FIGS. 1 and 2 are graphs showing the relationship between the optically isotropic region and the composition of the wholly aromatic polyester of the present invention. In addition, FIGS. 3, 4, and 5 show Example 1.7, respectively.
and shows the infrared absorption spectrum of the polymer obtained in Comparative Example 1.

Claims (3)

[Claims] (1) The following general formulas (I) to (IV) are used as repeating structural units, the melting point is approximately 350°C or less, and the reduced specific viscosity is 0.4 dl/
A wholly aromatic polyester, which has a molecular weight of at least 100 g and is characterized in that it changes from a crystalline state to an optically isotropic melt upon melting. ▲There are mathematical formulas, chemical formulas, tables, etc.▼(I) ▲There are mathematical formulas, chemical formulas, tables, etc.▼(II) ▲There are mathematical formulas, chemical formulas, tables, etc.▼(III) ▲There are mathematical formulas, chemical formulas, tables, etc.▼( IV) (However, R^1 is an ether group or carbonyl group, R
^2 represents a carbonyl group, and n is 0 or 1. ) (2) A film obtained from the wholly aromatic polyester according to claim 1. (3) A molded article obtained from the wholly aromatic polyester according to claim 1.