JP2867550B2 - Copolyester - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial application field> The present invention provides a polymer having a high degree of polymerization by melt polymerization alone, exhibits excellent liquid crystallinity, and has excellent mechanical properties which can be molded by a usual molding machine. The present invention relates to a copolymerized polyester having a high weld strength.

<Conventional technology> In recent years, the demand for higher performance of plastics has been increasing more and more, and a number of polymers having various new performances have been developed. Among them, optically anisotropic liquid crystal polymers have excellent mechanical properties. (JP-A-51-8395)
JP, JP-A-49-72393).

As the liquid crystal polymer, for example, a liquid crystal polymer obtained by copolymerizing p-hydroxybenzoic acid with polyethylene terephthalate is known (JP-A-49-72393). However, injection moldings of this polymer have the disadvantages of insufficient heat resistance and poor mechanical properties, and it has been found that injection moldings satisfying both properties cannot be obtained from this polymer. In addition, p-
Needs more than 80 mol% of hydroxybenzoic acid,
At this time, it was found that solidification occurred during polymerization, and that solid-phase polymerization was necessary.

On the other hand, as a means for improving the flowability of such a polymer, improving the melt moldability, and further improving the mechanical properties, for example, as described in JP-A-51-8395, polyethylene A method has been proposed in which terephthalate is copolymerized with p-acyloxybenzoic acid, a dicarboxylic acid, and an aromatic diol, but this method also improves the mechanical properties of the injection-molded product obtained but has insufficient heat resistance. I understand. On the other hand, as described in JP-B-47-47870, p-hydroxybenzoic acid
Injection molded products of wholly aromatic polyesters obtained by copolymerizing 4,4'-dihydroxybiphenyl and terephthalic acid have good heat resistance, but have a softening temperature of 400 ° C or higher, which makes melt polymerization difficult, resulting in mechanical properties. It turned out not to be very satisfactory.

As a method for solving these problems, Japanese Patent Application Laid-Open
A polymer obtained by copolymerizing p-hydroxybenzoic acid, a specific aromatic dihydroxy compound and an aromatic dicarboxylic acid with polyethylene terephthalate described in JP-A-63-30523 is satisfactory, although the balance between mechanical properties and heat resistance can be satisfied. It has been found that there remains a problem that the mechanical properties of the product, especially the strength of the weld portion is low.

<Problems to be Solved by the Invention> The present invention solves the above-mentioned problems, and is excellent in the balance between mechanical properties and heat resistance, and in particular, can provide a molded polyester having improved weld part strength. The task is to obtain

<Means for Solving the Problems> Accordingly, the present inventors have conducted intensive studies to achieve the above object, and as a result, have found that p-hydroxybenzoic acid, a specific aromatic dihydroxy compound, an aromatic dicarboxylic acid, and ethylene glycol and an aromatic dicarboxylic acid. A polyester formed from an acid is reacted with the copolymerized polyester to further form at least one selected from bis-ethylene oxide adducts of dihydric phenols, ethylene oxide adducts of aromatic hydroxycarboxylic acids and dihydroxynaphthalene having a hydroxyl group at a specific position. The present inventors have found that the above objects can be achieved by copolymerizing one kind of compound, and have reached the present invention.

That is, the present invention uses the following structural units (I) to (IV) as essential structural units, and further includes the following structural units (V) and (VI)
At least one type of structural unit selected from the group consisting of (VI), (VI) and (VI)
I) is the sum of structural units (I), (II), (III),
(V), (VI) and (VII) occupy 0.1 to 10% by mole, and the structural unit (III) is composed of the structural units (I) and (I).
A copolymerized polyester which accounts for 5 to 40 mol% based on the total of I), (III), (V), (VI) and (VII) and has an logarithmic viscosity of 0.5 to 5 dl / g. Things.

(However, R ₁ in the formula (II) is And at least one group selected from Also, in equation (IV)
R ₂ And at least one group selected from Here, Y represents a base atom or a hydrogen atom. In addition, one or two Ar ₁
Ar ₂ is a divalent residue containing two aromatic rings Ar ₃ is at least one group selected from At least one group selected from Further, the structural unit [(II) + (III) + (V) + (VII)] and the structural unit (I
V) is substantially equimolar. The present invention also relates to a molded article obtained by molding the above-mentioned copolymerized polyester and the above-mentioned molded article having a welded portion.

The structural unit (I) is a structural unit of a polyester formed from (A) p-hydroxybenzoic acid, and the structural unit (II) is (B) 4,4'-dihydroxybiphenyl, hydroquinone, 2,6-dihydroxynaphthalene. From one or more aromatic dihydroxy compounds selected from 4,4'-dihydroxydiphenyl ether, t-butylhydroquinone, phenylhydroquinone and 3,3 ', 5,5'-tetramethyl-4,4'-dihydroxybiphenyl Structural units generated, structural unit (III) is a structural unit generated from ethylene glycol, and structural unit (IV) is terephthalic acid, isophthalic acid, 4,4'-diphenylcarboxylic acid, 2,6-naphthalenedicarboxylic acid. Acid, 1,2-bis (phenoxy) ethane-4,4'-dicarboxylic acid, 1,2-bis (2-
Chlorphenoxy) ethane-4,4'-dicarboxylic acid, 4,
1 selected from 4'-diphenyl ether dicarboxylic acid
The structural units generated from at least one kind of aromatic dicarboxylic acid are shown.

Of these, R ₁ But as R ₂ Is most preferred.

Further, the structural unit (V) is a structural unit generated from a dihydroxy compound obtained by adding ethylene oxide to a phenolic hydroxyl group of at least one aromatic dihydroxy compound having one or two aromatic rings. Preferred specific examples of the aromatic dihydroxy compound having one or two aromatic rings constituting the structural unit (V) include:
Hydroquinone, resortin, 4,4'-dihydroxybiphenyl, 3,3 ', 5,5'-tetramethyl-4,4'-dihydroxybiphenyl, 2,2-bis (4-hydroxyphenyl) propane (bisphenol A), Bis (4-hydroxyphenyl) sulfone (bisphenol S), 2,2-
Bis (3,5-dimethyl-4-hydroxyphenyl) propane, 4,4'-dihydroxydiphenyl ether, 4,4 '
-Dihydroxydiphenyl sulfide, 4,4'-dihydroxybenzophenone, 2,6-dihydroxynaphthalene and 2,7-dihydroxynaphthalene. The structural unit (VI) is p-hydroxybenzoic acid, m-hydroxybenzoic acid, 4'-hydroxybiphenyl-4-
A structural unit formed from a hydroxycarboxylic acid obtained by adding ethylene oxide to a phenolic hydroxyl group of at least one aromatic hydroxycarboxylic acid selected from carboxylic acid and 6-hydroxy-2-naphthoic acid is converted into a structural unit ( VII) is 2,7-dihydroxynaphthalene and / or
Or a structural unit formed from 1,5-dihydroxynaphthalene.

On the other hand, among the above structural units, structural units (V) and (VI)
And the total of (VII) is the same as the structural units (I), (II), (I)
0.1) to the sum of (II), (V), (VI) and (VII)
It must be copolymerized so as to be ~ 10 mol%.
The sum of the structural units (V), (VI) and (VII) is the sum of the structural units (I), (II), (III), (V), (VI) and (V)
When the amount is less than 0.1 mol with respect to the total of II), the effect of the present invention is not remarkable, and the improvement in weld strength is not sufficient.
On the other hand, if it is more than 10 mol%, the heat resistance tends to decrease, and either case is not preferable.

As for the structural unit (III), the structural units (I), (II), (III), (V), (VI) and (VI)
It must be 5 to 40 mol% based on the total of I). The structural unit (III) is a structural unit (I), (II), (III),
5 mol% based on the total of (V), (VI) and (VII)
If the amount is less than the above, the melt fluidity decreases and solidifies at the time of polymerization. If the amount is more than 40 mol%, the heat resistance becomes poor, and neither is preferable.

Further, the structural units (II) and (VI) of the structural unit (I)
Molar ratio to the sum of I) [(I) / [(II) + (VII)]]
Is preferably 75/25 to 95/5, particularly preferably 82/18 to 92/8.

The method for producing the copolymerized polyester of the present invention is not particularly limited, and the copolymerized polyester can be produced according to a known polyester polycondensation method.

For example, (1) In the presence of a polyester copolymer comprising an aromatic dicarboxylic acid such as terephthalic acid and a compound such as an ethylene oxide adduct of ethylene glycol and bisphenol A or an oligomer thereof, p-hydroxybenzoic acid,
An aromatic dihydroxy compound such as 4'-dihydroxybiphenyl, an acetic anhydride is allowed to act on an aromatic dicarboxylic acid such as terephthalic acid to acetylate a hydroxyl group,
A method of producing by deacetic acid polycondensation reaction.

(2) p-hydroxybenzoic acid, 4,4'-dihydroxybiphenyl in the presence of a polyester or oligomer comprising an aromatic dicarboxylic acid such as terephthalic acid and ethylene glycol or an bis (β-hydroxyethyl) ester of an aromatic dicarboxylic acid And acetylation of a hydroxyl group obtained by reacting acetic anhydride with an aromatic hydroxy compound such as 1,5-dihydroxynaphthalene or an aromatic dicarboxylic acid such as terephthalic acid, followed by a deacetic acid polycondensation reaction.

 And the like are preferred examples.

A catalyst may be used for the polycondensation reaction, and examples thereof include metal compounds such as stannous acetate, tetrabutyl titanate, potassium acetate, antimony trioxide, magnesium, and sodium acetate.

The melt viscosity of the copolymerized polyester of the present invention is 10 to 1
5,000 poise is preferred, and particularly preferably 20 to 5,000 poise.

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

On the other hand, the logarithmic viscosity of the copolymerized polyester of the present invention is 0.1 g.
The value measured in pentafluorophenol at a / dl concentration of 60 ° C. is 0.5 to 5 dl / g, preferably 1.0 to 3.0 dl / g. 0.
If it is less than 5 dl / g, the mechanical strength is not sufficient, and if it is more than 5 dl / g, the fluidity becomes poor, which is not preferable.

In the polycondensation of the copolymerized polyester of the present invention, in addition to the components constituting the above structural units (I) to (VII), 3,3′-diphenyldicarboxylic acid and 2,2′-diphenyldicarboxylic acid Aromatic dicarboxylic acids such as aromatic dicarboxylic acids, adipic acid, azelaic acid, sebacic acid, dodecanedioic acid, alicyclic dicarboxylic acids such as hexahydroterephthalic acid, chlorohydroquinone, and aromatic dihydroxy compounds such as methylhydroquinone; 1,4-
Aliphatic, alicyclic diols such as butanediol, 1,6-hexanediol, neopentyl glycol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol and m-hydroxybenzoic acid, 2,6-hydroxynaphthoe An aromatic hydroxycarboxylic acid such as an acid and an aromatic imide dicarboxylic acid, an aromatic imide dihydroxy compound, an aromatic imide hydroxy carboxylic acid, etc. having an imide bond in the molecule and capable of forming a polyester can be used for the purpose of the present invention. Copolymerization can be further performed in a small proportion that does not impair.

The optically anisotropic polyester of the present invention thus obtained has a high polymerization degree polymer only by melt polymerization, exhibits excellent melt fluidity, excellent mechanical properties with improved weld strength and heat resistance, and is extruded and injected. It can be subjected to ordinary melt molding such as molding, compression molding, and blow molding, and can be processed into fibers, films, three-dimensional molded products, containers, hoses, and the like.

Further, since it has excellent weld strength, it is useful as a molded article having a weld portion.

In addition, with respect to the optically anisotropic polyester of the present invention, reinforcing agents such as glass fiber, carbon fiber and asbestos, fillers, lubricants, release agents, nucleating agents, plasticizers, flame retardants (preferably brominated polystyrene, etc.) Polymer flame retardants), heat stabilizers, ultraviolet absorbers, pigments, dyes, and other thermoplastic resins can be added as needed to impart desired properties.

Reinforcing agent, filler, in the optically anisotropic polyester of the present invention,
Means for blending additives and the like are arbitrary, but for example, a screw extruder or the like can be preferably used.

In addition, the strength of the injection-molded article obtained in this manner can be increased by heat treatment, and the elastic modulus can also be increased in some cases.

This heat treatment can be performed by heat treating the injection molded article in an inert atmosphere (eg, nitrogen, argon, helium, or water vapor) or an oxygen-containing atmosphere (eg, air) at a temperature equal to or lower than the melting point of the polymer. This heat treatment may or may not be under tension and can take place in tens of minutes to several days.

<Example> Hereinafter, the present invention will be further described with reference to examples.

Example 1 In a reaction vessel equipped with a stirrer and a distilling tube, 994 g (7.2 mol) of p-hydroxybenzoic acid, 101 g (0.54 mol) of 4,4'-dihydroxybiphenyl, 89.7 g (0.54 mol) of terephthalic acid, and 930 g of acetic anhydride (9.11 mol) and 276 g (1.26 mol) of a polyester copolymer (A) composed of ethylene glycol, bisphenol A ethylene oxide adduct and terephthalic acid having an intrinsic viscosity of about 0.6 represented by the following structural formula, and deacetic acid under the following conditions: Polymerization was performed.

x / y = 89.3 / 10.7 First, 250 ~ 3 at 100 ~ 250 ℃ under nitrogen gas atmosphere for 5 hours
After reacting at 20 ℃ for 1.5 hours, 0.5mmHg at 320 ℃ for 1 hour
The reaction was further reduced for 1.0 hour to complete the polycondensation. As a result, an almost theoretical amount of acetic acid was distilled off, and a polymer having the following theoretical structural formula was obtained.

k / l / m / n / o = 80/6 / 12.5 / 1.5 / 20 The polyester was placed on a sample stage of a polarizing microscope and the temperature was raised to confirm the optical anisotropy. Was 282 ° C., showing good optical anisotropy.

The obtained polymer is supplied to Sumitomo Nestal injection molding machine Promat 40/25 (manufactured by Sumitomo Heavy Industries, Ltd.), and the cylinder temperature is 320 ° C. and the mold temperature is 90 ° C., 1/8 ″ × 1/2. ″ ×
A 5 ″ test piece and ASTM No. 4 dumbbell were molded. The ASTM No. 4 dumbbell is a normal mold with a gate at one end of the dumbbell (dumbbell I) and a weld mold with a gate at both ends of the dumbbell (dumbbell II). According to ASTM D648 standard, a 1/8 ″ thick test piece was measured for a deflection temperature [HDT] (18.6 kg f / cm ² ). Further, the breaking strength of ASTM No. 4 dumbbell was measured according to the ASTM D638 standard, and the ratio of the breaking strength of dumbbell II to dumbbell I was defined as the weld strength retention.

As a result, HDT 222 ° C, strength of dumbbell I (non-weld) 190 kg f / cm ² , strength of dumbbell II (weld) 1160 k
gf / cm ² , and the weld strength retention was 16.3%.

The logarithmic viscosity of the polymer (in pentafluorophenol at 60 ° C.) is 1.88 dl / g, and the melt viscosity is a shear rate of 1,000 (1
Per second) and the fluidity was extremely good.

Example 2 p-Hydroxybenzoic acid was placed in the same reaction vessel as in Example 1.
994 g (7.2 mol), 4,4'-dihydroxybiphenyl 101 g
(0.54 mol), 21.6 g of 1,5-dihydroxynaphthalene (0.
135 mol), 960 g of acetic anhydride (9.4 mol), terephthalic acid 11
When 2 g (0.675 mol) and 216 g (1.125 mol) of polyethylene terephthalate having an intrinsic viscosity of about 0.6 were charged and subjected to deacetic acid polymerization under the same conditions as in Example 1, a polymer having the following theoretical structural formula was obtained.

k / l / m / n / o = 80/6 / 12.5 / 1.5 / 20 This polyester was placed on a sample stage of a polarizing microscope, and the temperature was raised to confirm the optical anisotropy.
3 ° C.

This polymer was molded in the same manner as in Example 1 to obtain an HD.
When T and breaking strength were measured, HDT224 ° C., dumbbell I strength (non-weld) was 185 kg f / cm ² , dumbbell II strength (weld) was 1180 kg f / cm ² , and the weld strength retention was 15.6%. .

The logarithmic viscosity of this polymer (in pentafluorophenol at 60 ° C.) is 1.92 dl / g, and the melt viscosity is a shear rate of 1,000.
(1 / sec), it was found to have a good fluidity of 1270 poise.

Comparative Example 1 An experiment similar to that of Example 1 was performed on a polymer having a composition not containing the structural units (V), (VI), and (VII) in the present invention.

In a reaction vessel similar to that in Example 1, 994 g (7.2 mol) of p-hydroxybenzoic acid and 4,4'-dihydroxybiphenyl 12
6 g (0.675 mol), 960 g (9.4 mol) of acetic anhydride, 112 g (0.675 mol) of terephthalic acid and 216 g (1.125 mol) of polyethylene terephthalate having an intrinsic viscosity of about 0.6 were charged and subjected to deacetic acid polymerization under the same conditions as in Example 1. A polymer having the following theoretical structural formula was obtained.

k / l / m / n = 80 / 7.5 / 12.5 / 20 Also, as a result of placing this polyester on a sample stage of a polarizing microscope and raising the temperature to check the optical anisotropy, the liquid crystal onset temperature was 294 ° C. there were.

This polymer was molded in the same manner as in Example 1 to obtain an HD.
As a result of measuring the T and the breaking strength, the HDT was 231 ° C., the strength of dumbbell I (non-weld) was 1200 kg f / cm ² , and the strength of dumbbell II (weld) was 150 kg f / cm ² , and the weld strength retention was 12.5%. It was found to be lower than.

<Effects of the Invention> The copolymerized polyester of the present invention can obtain a polymer having a high degree of polymerization only by a melt polymerization method.From this polymer, the heat resistance and the mechanical properties are excellently balanced, and the mechanical properties, particularly the strength of the weld portion, are improved. Since an improved molded product can be obtained, it can be used for various applications such as a metal substitute plastic.

Claims (3)

(57) [Claims] 1. The following structural units (I) to (IV) are essential constituent units, and the following structural units (V), (VI) and (VI)
At least one type of structural unit selected from (I) is copolymerized, and the total of structural units (V), (VI) and (VII) is the sum of structural units (I), (II), (III) and ( V), (VI) and (VII) occupy 0.1 to 10% by mole, and the structural unit (III) is composed of the structural units (I), (II), (III),
A copolymerized polyester comprising 5 to 40 mol% of the total of (V), (VI) and (VII), and having a logarithmic viscosity of 0.5 to 5.0 dl / g. (However, R ₁ in the formula (II) is And at least one group selected from Also, in equation (IV)
R ₂ And at least one group selected from Here, Y represents a chlorine atom or a hydrogen atom. In addition, one or two Ar ₁
Ar ₂ is a divalent residue containing two aromatic rings Ar ₃ is at least one group selected from At least one group selected from The total of the structural units (II), (III), (V) and (VII) and the structural unit (IV) are substantially equimolar. ) 2. A molded article obtained by molding the copolymerized polyester of claim 1. 3. The molded article according to claim 2, wherein the molded article has a weld portion.