JPS60130619A - Aromatic polyester - Google Patents

Abstract

PURPOSE:The titled polyester which shows anisotropy when molten, is excellent in melt moldability and can easily give a molding of excellent properties, comprising specified aromatic monomer units. CONSTITUTION:A melt-anisotropic fully aromatic polyester comprising monomer units of formulas I , II, III, and IV (wherein Ar is naphthyl, or biphenyl, R is H, Cl, or methyl, and the molar fractions of the units k, l, m, and n satisfy the relationships V, VI, and VII). The above polyester is formed by reacting naphthoxy or biphenoxyhydroquinone diacetate, optionally togehter with hydroquinone diacetate (derivative), with terephthalic acid, optionally together with p- acetoxybenzoic acid, at about 200-350 deg.C and further polycondensing the reaction mixture in vacuum at about 280-350 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a polyester, more specifically, a wholly aromatic polyester in which all constituent units are composed of aromatic compounds, which has good melt moldability and can easily give molded products having excellent physical properties. It is something.

Conventionally, polyamide fibers such as polyhexamethylene adipamide, which have relatively high strength or high Young's modulus, have been used as reinforcing fibers for organic polymeric materials such as rubber and plastics.
polyester fibers such as polyethylene terephthalate,
Alternatively, inorganic fibers such as steel and glass are widely used depending on the purpose. However, due to recent advances in technology in various industrial fields and the desire to save energy due to concerns about the supply of energy resources, it is of course necessary to improve the performance and weight of organic polymer materials, and also to develop metal substitutes. There is also a need for high performance materials that can be used as To meet these objectives,
Reinforcement fibers with high performance, especially excellent mechanical and thermal properties, are required. However, the mechanical properties of the conventionally widely used reinforcing fibers, namely tensile strength and Young's modulus, are not very high, and although methods for strengthening various physical properties including these mechanical properties are being researched,
The reality is that dramatic improvements in physical properties cannot be expected.

Aramid fibers such as polybara phenylene terephthalamide, which are known as high-performance reinforcing fibers,
Carbon fiber and other materials have considerably superior performance and have been put into practical use in some areas, but their manufacturing processes are quite complex and their costs are high, so their use is limited to special applications. On the other hand, it is known that from polyester that forms an anisotropic melt called "liquid crystal polyester," fibers with a high Young's modulus can be obtained by ordinary melt spinning, and fibers with high strength can be obtained by further heat treatment. It is being This fiber is expected to be used as a reinforcing fiber with good mechanical properties. The characteristics of the polyester that forms this anisotropic melt are that due to its liquid crystal orientation in the molten state, it can be spun into a highly oriented fiber with a high Young's modulus without drawing. By heat-treating this as-spun fiber in an inert atmosphere at a high temperature close to the softening temperature for a relatively long time, for example, several hours to several tens of hours, the fiber has a high strength of 15J7/(1 or more). (Japanese Unexamined Patent Publication No. 157-1989)
619, JP-A-54-77691, etc.).

Among the polyesters that form this anisotropic melt, aromatic polyesters whose main chain is composed only of p-oriented benzene rings and ester bonds have favorable properties in terms of heat resistance and mechanical properties. It is thought that However, such aromatic poly(I) esters are generally difficult to mold due to their high melting points. For example, a moldable wholly aromatic polyester consisting of phenylhydroquinone and terephthalic acid was proposed (Japanese Patent Laid-Open No. 53,654).
21), but this polyester is also Mdt
It has a high score and is not necessarily satisfactory in terms of molding.

Generally, in order to obtain high-strength fibers, it is necessary to subject the spun fibers to heat treatment for a long period of time, which is a major cause of difficulty in industrial implementation.

The present inventors have improved the above-mentioned drawbacks of conventional polyesters that form anisotropic melts, and have provided an aromatic polyester that has excellent melt moldability and can easily give molded products with high physical properties. As a result of extensive research, we have found that naphthoxy or binenoxyhydroquinone, or naphthoxy or binenoxyhydroquinone and hydroxyl or certain hydroquinone derivatives, terephthalic acid and p-
It was discovered that a wholly aromatic polyester made by copolymerizing hydroxybenzoic acid at a predetermined ratio is suitable for the purpose, and based on this knowledge, the present invention was completed.

That is, the present invention relates to the general formulas OO and ○ (where Ar is a naphthyl group or a biphenyl group, R is a hydrogen atom, a chlorine atom or a methyl group,
is the mole fraction of each unit, and these satisfy the relationship klj5:m...(6)) and has melting anisotropy. The purpose of the present invention is to provide a fully aromatic polyester with special characteristics.

The wholly aromatic polyester of the present invention needs to contain a naphthoxy- or biphenoxy-substituted hydroquinone unit of the general formula +11 and a terephthalic acid unit of the general formula (lit), and if desired, a mol of the general formula +1). It is possible to replace up to the fractional units with substituted or unsubstituted hydroquinone units of the general formula (11), and up to the 7D molar unit of all structural units can be replaced with p-hydroxybenzoic acid units of the general formula.

General formula (I
) units can be derived from lower fatty acid esters such as naphthoxy or binenoxy hydroxynes or their diacetates. This naphthoxy or binenoxyhydroquinone can be obtained, for example, by hydrolyzing naphthoxy or binenoxyhydroquinone dimethyl ether produced by the reaction of bromohydroquinone dimethyl ether with sodium naphthoxide or biphenoxide.

Further, the unit of the general formula (11) can be derived from a lower fatty acid ester such as hydroquinone, chlorohydroquinone, methylhydroxyne or their diacetate, and the unit of the general formula (II [l unit is terephthalic acid, terephthalic acid It can be derived from dimethyl, diphenyl terephthalate, etc.

Furthermore, the units on the general formula side are p-hydroxybenzoic acid, p
-acetoxybenzoic acid, or ester compounds such as phenyl p-hydroxybenzoate.

The unit of the general formula (I) in the aromatic polyester of the present invention has the effect of suppressing the excessive crystallinity of the polyester and lowering its melting point, so it can be replaced with the unit of the general formula ([). In the case of substitution, if the molar fraction increases to more than 50 mol% of the total diol component, the melting point increases and melt molding becomes difficult. Therefore, it is desirable that the proportion of the units of general formula m to the total diol component be 80 mol% or more, particularly 90 mol% or more. General formula (as the unit of 11, specifically α-naphthoxyhydroquinone, β-naphthoxyhydroquinone,
Units such as 4-binenoxyhydroquinone and 3-binenoxyhydroquinone can be mentioned, and two or more of these units may be combined, and in some cases, these units and phenoxyhydroquinone units may be combined. It may be.

Further, the unit of the general formula has the effect of imparting appropriate fluidity to the polyester, but when it is included, it is necessary to make it a proportion of 10 moles or less in all the structural units. If this proportion exceeds 70 mol%, the homopolymer character of p-hydroxybenzoic acid becomes strong, the melting point becomes high, and the moldability deteriorates. The preferred proportion of goldstone in this unit is 5 to 40 moles, especially 15 to 40 moles in all constituent units.
25 molar range. On the other hand, the units of the general formula (1+11) forming the carboxylic acid component of the polyester are advantageously chosen in such a way that they are approximately equal to the total molar amount of the entire diol component, ie the units of the general formulas (1) and (11).

In this way, deterioration of moldability and other physical properties due to the incorporation of unreacted components can be suppressed.

As mentioned above, the wholly aromatic polyester of the present invention consists essentially of units represented by the general formulas fl), fU), fil, and the sides, but within the range that does not impair the desired physical properties, It can also contain units other than those mentioned above. Such units include, for example, phenoxyresorcin units, resorcin units, methylresorcin units,
Examples include chlororesorcinol units, isontal acid units, m-hydroxybenzoic acid units, bisphenol A units, and 1,2-ethylenebis(p-carboxyphenoxy) units. These units constitute 5 of the total constituent units.
It can be contained up to a molar ratio or less, preferably up to 6 molar ratio.

The polyester of the present invention is characterized by having melt anisotropy, which means that in the molten state, light is transmitted through an optical system equipped with a pair of polarizers crossed at 90°. It is the property of causing

This melt anisotropy is a necessary property to ensure high orientation in the as-molded state.

Intrinsic viscosity of the polyester of the present invention [ηinh; p-chlorophenol, phenol, tetone chloroethane 40:
25:35 (weight ratio) in a mixed solvent], by changing the polymerization conditions, a value of about 0.2 to about 20 can usually be obtained, but it may be difficult to improve the moldability and mechanical properties of the molded product. In the case of polyester before molding, from 1.0 to 10.0
The following ranges are preferred.

Note that after the polyester of the present invention undergoes solid phase polymerization through so-called heat treatment, it may have a significantly high intrinsic viscosity or may become insoluble in the above-mentioned mixed solvent. is one embodiment of the polyester.

The polyester of the present invention is usually prepared by mixing (1) naphthoxy or binenoxyhydroquinone diacetate, or hydroxyne diacetate or its methyl or chloro substituted product, terephthalic acid, or p-acetoxybenzoic acid, and then removing acetic acid while heating and stirring. A method for carrying out a polycondensation reaction, (11) Mixing nandoxy or biphenoxy hydroxyne, or hydroxyl or its methyl or chloro substituted product, diphenyl terephthalate, or phenyl p-hydroxybenzoate, and removing phenol while heating and stirring. Manufactured by methods such as polycondensation reactions.

To be more specific about the method (i) above, naphthoxy or binenoxyhydroquinone diacetate, or hydroxyne diacetate or its methyl or chloro substituted product, terephthalic acid, p-acetoxybenzoic acid are mixed in a stirrer, nitrogen It was charged into a polymerization reactor equipped with a gas introduction pipe and a vacuum distillation device, and heated for 200 min while flowing nitrogen.
Heat and react at a temperature of ~350°C for 5 minutes to 4 hours with stirring. After that, the pressure will be reduced to 0゜1 torr.
A polyester is obtained by carrying out a polycondensation reaction at a temperature of 280 to 350° C. for 1 minute to 4 hours under a reduced pressure of 2.0 torr.

During this reaction, a polycondensation catalyst such as an antimony or germanium compound, a stabilizer such as a phosphorus compound, a matting agent such as titanium oxide, etc. can be added at any time from the start to the end of the reaction.

The polyester melt thus obtained can be directly melt-molded into fibers or the like, or it can be cooled and solidified to form so-called chips or powder, and then re-melted and molded. The degree of polymerization can also be increased by subjecting the solidified polymer to solid phase polymerization at a temperature below its melting temperature under vacuum or in an inert atmosphere.

The melting point of the polyester of the present invention before molding is preferably in the range of about 2800C or more and about 380C or less, more preferably 350C or less. Here, the melting point is DSC
Alternatively, it can be observed as an endothermic peak by thermal analysis such as DTA, but it also almost matches the softening point measured by the following measurement method, and the melting point may be estimated by this method. That is, sandwiching a flaky sample between cover glasses,
The sample is heated at a heating rate of about 0° C./min while being observed with a polarizing microscope, and the melting point is estimated by measuring the temperature at which it begins to flow (softening point).

The polyester of the present invention can be easily formed into fibers, films, tapes, resins, etc. using known methods. When producing fibers, conventional melt spinning methods are used. That is, an extruder is used to extrude the polyester from a spinneret having one or more orifices at a temperature above the softening point and below about 400°C. The diameter of this orifice is usually 0.08 to 1.0 mm. The polyester melt extruded in this way is either rapidly cooled under the spinneret, or passed through a high-temperature atmosphere provided under the spinneret by a heating tube or a heat-insulating tube.
It is cooled and solidified and wound up as fiber. The draft rate at this time is usually 1.2 to 1000, and the winding speed is 30 to 500.
A range of 0 m1 min is preferable.

The polyester fiber thus obtained has a high modulus.
It has laths and can be used as is, or can be further heat treated to increase its strength.

This heat treatment is carried out under no tension or under a slight tension, and it is not preferable to carry out the heat treatment under a high tension that would cause structural destruction of the fibers, but under a tension lower than that, the effect is small. Further, during the heat treatment, an anti-fusing agent such as Merck or graphite may be attached if necessary. moreover,
10 tor to prevent the decomposition of the polyester by oxygen and to remove volatile products produced by the polymerization reaction.
It is carried out under a vacuum of less than r or under an inert gas such as nitrogen or argon flowing intermittently or continuously. The heat treatment temperature is usually carried out in a temperature range of several tens of degrees below the softening point of the fibers, but since the softening point generally increases as the heat treatment progresses, the heat treatment temperature may be increased in stages. In addition, heat treatment is generally carried out within a range of several minutes to 24 hours, but in the polyester of the present invention, the rate of increase in the degree of polymerization and fiber strength due to heat treatment is extremely large.
Approximately 2 hours will be selected.

Furthermore, in the case of films, tapes, resin moldings, etc. other than fibers, they are molded and heat treated in the same manner as in the case of fibers.

The polyester of the present invention has an unusually low melting point suitable for melt molding for a wholly aromatic polyester whose main chain is composed only of p-oriented benzene rings and ester bonds, and has fluidity in the molten state. is extremely good,
Therefore, it has an excellent feature of being able to perform melt molding extremely smoothly. In addition, the fibers melt-spun from the polyester of the present invention have an extremely high rate of increase in strength due to heat treatment, so that a high strength of 2 o 17 / d or more can be obtained by heat treatment in an extremely short time, for example, within one hour. , the long-time problem, which was conventionally considered to be a one-dog factor that was difficult to implement industrially, can be easily solved.

Such improvements in physical properties through heat treatment can be expected to improve toughness, tensile strength, impact strength, tear strength, heat resistance, etc. when the polyester of the present invention is processed into films, sheets, and other molded products. .

The polyester of the present invention has a faster rate of increase in the strength of molded products by heat treatment than conventional polymers (the polymer proposed in JP-A-53-65421) that have a relatively similar molecular structure. It's noticeably thick. Although the reason for this is not clear, it is thought that the phenoxy group is unique in its influence on thermal mobility and the reactivity of the ester bond-forming molecular terminal.

Another feature of the polyester of the present invention is that it is resistant to oxidative deterioration even at high temperatures.

Due to these characteristics, for example, when heat-treated in an oxygen-containing atmosphere, molded products made of conventionally known polyester cannot be expected to improve in strength or elongation, whereas molded products made using the polyester of the present invention cannot be expected to improve their strength or elongation. Their improvement is possible and extremely advantageous for industrial implementation.

Another feature of the polyester of the present invention is that its molded articles, such as fibers, have high strength, relatively high elongation, high toughness, and extremely high knot strength; It not only has excellent physical properties at high temperatures, but also has excellent physical properties at high temperatures, such as 150°C.
It has excellent strength and modulus at temperatures of These characteristics are fully exhibited when the molded article is heat treated to increase its softening point and degree of polymerization.

The excellent high-temperature physical properties of the molded article made of the polyester of the present invention can be explained by the fact that, for example, the ratio of the elastic modulus at a temperature of 150°C to the elastic modulus at room temperature is 0.46 in the case of the heat-treated fiber in Example 1 described below. In contrast, Japanese Patent Application Publication No. 1983-
In the case of the heat-treated fibers tested in Example 1 of Publication No. 77691, the value was 0.26, which is easily understood.

Since the polyester of the present invention has the various characteristics described above, it can be used mainly for industrial materials such as reinforcing fibers such as tire cords, films, and resins.

Next, the present invention will be explained in more detail with reference to Examples.

Example 1 Polymerization step α-Nandoxyhydroquinone diacetate 77°3fl
(0.23 mol), terephthalic acid 54.71 (0,
22 mol), p-acetoxybenzoic acid 12.8 g (
0.07 mol) was charged into a polymerization reactor equipped with a stirrer and a vacuum distillation device, and 8 mol was added while stirring in a nitrogen stream.
The temperature was raised to 320°C in 0 minutes, and the reaction was carried out at 320°C for 20 minutes. The pressure was gradually reduced over a further 5 minutes, and then the reaction was carried out for 30 minutes at a reduced pressure of 0.2 torr.

After the reaction was completed, nitrogen was introduced to return the system to normal pressure, and the polyester melt was taken out, rapidly cooled and solidified, and then crushed with a crusher to form chips.

The elemental analysis values of the polyester thus obtained are shown below.

Actual value i 075.2%, H3,6% theoretical value; O7
The formation of polyester was confirmed from the infrared absorption spectrum measured by the 4.9% and H3.6% potassium bromide tablet method.

The differential thermal analysis (DTA) chart of this polyester had a small melting endothermic peak at 280°C, and the decomposition temperature determined by thermogravimetric analysis (TG) was 420°C. Further, the softening point was 290°C, and it exhibited optical anisotropy in a molten state. The intrinsic viscosity was 1.31, and the melt viscosity at 320°C was 35 voids.

Spinning process After drying the obtained chips under reduced pressure at 180°C for 8 hours,
Extruder with screw diameter of 25mm and spinneret diameter of 0°25mm,
It was extruded at a spinning hole temperature of 320° C. using a melt spinning device equipped with six spinning holes, and wound up at a speed of 650 m/min. The obtained polyester fiber has a single yarn denier of 11
．． 2. Strength was 1.7.9/d, elongation was 0.8%, and initial modulus was 276 g/d.

Heat treatment process volume 10j? The fibers were placed in a cylindrical flask, heated to 285°C for 25 minutes while nitrogen was flowing at 21/min, and then heat-treated at 285°C for an additional 20 minutes. The resulting heat-treated system had a strength of 18.8 g/d1, an elongation of 6.0%, and an initial modulus of 265 I/d, and the strength and elongation were significantly increased by a short heat treatment.

Comparative Example 1 In this comparative example, fibers obtained from a polyester composed of phenylhydroxyl residues and terephthalic acid residues described in JP-A No. 55-65421 showed a rate of increase in strength due to heat treatment. This illustrates its inferiority compared to fibers obtained from the inventive polyester.

phenylhydroquinone diacetate) 1309 (0,4
Polyester was obtained in the same manner as in Example 1 from terephthalic acid 761/(0.46 mol). This polyester had a softening point of 340°C and an intrinsic viscosity of 2°1. This polyester was extruded using the same melt spinning apparatus as in Example 1 at a spinning hole temperature of 350° C. and wound at a speed of 73 m/min. The obtained polyester fiber has a single yarn denier of 18
, strength 1.1 j)/d, elongation 0.4%, and initial modulus 322 y/d. This polyester fiber was heat-treated at 330'C for 1 hour, 6 hours, and 14 hours using the same equipment as in Example 1, and the strength of the fiber was 5. sy
/d, 16.99/d, and 18.2 fl/d, and the rate of increase in strength due to heat treatment is slower than that of the polyester fiber of Example 1.

Example 2.3 Polyesters having different monomers and monomer composition ratios were produced in the same manner as in Example 1. The softening point, intrinsic viscosity, and elemental analysis values of these polyesters are shown in the following table.

All cholera polyesters exhibit melt anisotropy;
When taken out from the polymerization apparatus, it had stringability.

/′ / / / /

Claims (1)

[Claims] 1 General formula (in the formula, Ar is a naphthyl group or a biphenyl group, R is a hydrogen atom, a chlorine atom, or a methyl group, and k, t!, m and n are the mole fraction of each unit. , these satisfy the relationship k+l k+l km ) A wholly aromatic polyester characterized by having melt anisotropy and consisting essentially of structural units represented by the formula: k+l k+l km . The wholly aromatic polyester according to claim 1.