JPS60199028A - Novel polyester - Google Patents

Abstract

PURPOSE:A novel polyester useful as reinforcing fibers, etc., having improved melt molding properties and thermal mechanical properties, obtained by polymerizing phenylhydroquinone with a 4,4'-biphenol, a terephthalic acid and a p- hydroxybenzoic acid in a specific composition. CONSTITUTION:(A) Phenylhydroquinone or diacetate is polymerized with (B) 4,4'-biphenol (e.g., 2,2'-dimethyl-4,4'-biphenol, etc.), (C) a terephthalic acid (e.g., dimethyl terephthalate, etc.) and (D) a p-hydroxybenzoic acid (e.g., phenyl p- hydroxybenzoate, etc.). to give the desired polymer consisting of structural units shown by the formula I (k is molar fraction), formula II (R and R' are H, methyl, or ethyl; X and X' are 1-4 interger; l is molar fraction), formula III (m is molar fraction), and formula IV (n is molar fraction), and molar fractions of the structural units satisfying the equations shown by the formula V-formula VII.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a novel polyester, more specifically, a polyester in which all the structural units are aromatic, which has good melt moldability and can easily give molded products with excellent physical properties. It concerns polyester.

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 polyparaphenylene 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 the manufacturing process for each fiber is simple and complex, and they are expensive, so they are only used for special purposes. limited.

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. ing. 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 period of time, for example, several hours to several tens of hours, a fiber having a high strength of 15 f/d or more can be obtained. C JP-A No. 50-157619 which is obtained,
JP-A No. 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 polyesters are generally difficult to mold in many cases because of their high melting points. For example, a moldable wholly aromatic polyester consisting of phenylhydroquinone units and terephthalic acid units was proposed (Japanese Patent Laid-Open No. 53-6
5421), but this polyester also has a high melting point and is not necessarily satisfactory for molding, and in order to obtain high-strength fibers, it is necessary to heat-treat the spun fibers for a long time. This is a major cause of difficulty in industrial implementation.

By the way, various polyesters other than those described in JP-A-53-65421 are known as polyesters containing phenylhydroquinone units as a main component. For example, a copolyester consisting of phenylhydroquinone units, hydroxyl units, and terephthalic acid units (JP-A-56-84718), a copolyester consisting of phenylhydroquinone units, terephthalic acid units, and p-hydro[tau]cybenzoic acid units (IP !f table show 5
5-500215) has been proposed. However, the former has a high melting point of 330°C or higher, making it difficult to mold, while in the latter, by selecting the copolymerization ratio, it is possible to lower the melting point to a level around 300°C, which is easy to mold. However, at the same time, the softening point is significantly lowered, which causes problems such as deformation, shrinkage, or fusion when heat treating the molded (spun) product (fiber). I don't like it. In addition, part or all of the terephthalic acid units of the polyester consisting of phenylhydroquinone units and terephthalic acid units 'i4
．． Polyesters substituted with 4'-diphenyldicarboxylic acid units (Japanese Unexamined Patent Publication No. 194919/1982), polyesters containing phenylhydroquinone units and 1,2-bis(phenoxy)ethane-4,4'-dicarboxylic acid groups (specially (Kokai No. 58-194920) has been proposed. However, in the former proposal, it is shown that the melting point can be changed to a range where it is easy to mold by changing the substitution rate of 4,4'-diphenylcarboxylic acid units, but in the case of this polyester, heat treatment also The disadvantage of slow improvement rate of mechanical properties remains unresolved. On the other hand, the polyester mentioned below has a low melting point of about 235°C, and its moldings cannot be heated at high temperatures (for example, 15
It is easily estimated that the performance at 0° C.) is poor.

Salani, phenylhydroquinone units, tert-ferhydroxyne units and terephthalic acid units have also been disclosed (U.S. Pat. No. 4,238,600).
No. 0 specification). However, this material has a melting point of about 3
It has the disadvantage that it is difficult to mold at 70°C.

The present inventors aimed to improve the above-mentioned drawbacks of conventional polyesters that form anisotropic melts, and to provide a polyester that has excellent melt moldability and can be easily formed into molded products with high physical properties. As a result of intensive research, phenylhydroquinone, 4,4'-biphenols, terephthalic acid and
It was discovered that a polyester formed by copolymerizing -hydroxybenzoic acid in a predetermined ratio is suitable for the purpose, and based on this knowledge, the present invention was completed.

That is, the present invention is based on the general formula %: (wherein R and R' are hydrogen atoms, methyl groups, or ethyl groups,
x, x' are integers from 1 to 4, k, 1. m and n are the mole fractions of the respective units, which are 0.95 m
< k + 1 ≦ 1.05 m --- satisfies the relationship (2)).

The general formula (11 units can be derived from lower fatty acid esters such as phenylhydroxyne or its diacetate) constituting the polyester of the present invention, and the general formula (It)
The units are 4,4'-biphenol, 2,2'-dimethyl-4,4'-biphenol, 2.2', 6.6'-tetramethyl-4,4'-biphenol, 2.2', 6.
It can be derived from lower fatty acid esters such as 6'-tetraethyl-4,4'-biphenol or their diacetates, and the units on the general formula side can be derived from terephthalic acid, dimethyl terephthalate, diphenyl terephthalate, etc. can.

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

In the polyester of the present invention, the content ratio of the units represented by the general formula (1) and the units represented by the general formula (nl) is extremely important;
It is necessary that the molar fraction of the units represented by is in the range of 0.3 to 75. If this molar fraction is less than 0.3, the melting point of the polyester is high and melt molding is difficult.
On the other hand, if it exceeds 0.75, the melting point of the polyester becomes too high and melt molding becomes difficult when the general formula unit is missing, and the degree of polymerization of the polyester obtained by melt polymerization generally becomes small. , The strength of the molded product (fiber) as formed (or spun) is low and difficult to handle, the chemical resistance of the polymer is poor, high modulus fibers cannot be obtained, the linear expansion coefficient of the molded product (fiber) is low. This results in drawbacks such as thick fibers, and above all, the advantage of the present invention, which is the in-phase polymerization by heat treatment of the fibers and the high rate of increase in strength and elongation based thereon, is lost. Therefore, the general formula (1
It is more preferable that the molar fraction of the units of general formula (1) to the total of the units of ) and the units of general formula (■) is within the range of 0.5 to 0.7.

In addition, the unit of general formula 11V) has the effect of imparting appropriate fluidity to polyester, but when it is included, it is necessary to make it a proportion of 40 moles or less in all structural units. be. If this ratio exceeds 40 moles, the advantage of the polyester of the present invention, which is the high solid state polymerization rate of molded products, is lost. The preferred content ratio of this unit is 30 molar or less in all structural units, especially 1O~
25 molar range.

Furthermore, K, all diol components of the present invention, that is, general formula (1)
The total molar figure of the units of and ([l) is 95 to 105 of the units of the general formula button forming the carboxylic acid component of the polyester.
It is necessary to contain it in a molar range, preferably 97 to 103 mol, more preferably 9
It is desirable to contain it in a range of 8 to 102 molar ratios. In this way, a polyester having a degree of polymerization necessary to ensure the desired level of performance of molded articles such as fibers, films, sheets, and injection molded articles can be obtained.

As described above, the polyester of the present invention has the general formula (1)
, Ql) , (Ill) and V), but may contain units other than those mentioned above within a range that does not impair the desired physical properties.

Examples of such units include phenylresorcin units, resorcin units, methylresorcin units, chlororesorcin units, inphthalic acid units, m-hy)'roxybenzoic acid units, bisphenol A units, 1,2-ethylenebis(p- carboxyphenoxy) units, etc. These units can be contained up to 5 mol or less, preferably 3 mol or less in all the structural units.

The polyester of the present invention exhibits optical anisotropy when melted. The melt optical anisotropy referred to herein refers to the property of allowing light to pass through an optical system equipped with a pair of polarizers crossed at 90° in the melted state.

This melt optical anisotropy is closely related to the high degree of orientation in the as-molded state.

Intrinsic viscosity of the polyester of the present invention [η1n) 1 * p
- measured in a mixed solvent of chlorophenol, phenol, and tetrachloroethane 40:25:35 (by weight)] is usually about 0.2 by changing the polymerization conditions.
As mentioned above, a polyester of about 20 or less can be obtained, but from the viewpoint of moldability and mechanical properties of the molded product, in the case of polyester before molding, 1
．． The range is preferably 0 or more and 10.0 or less.

The polyester of the present invention may have a significantly high intrinsic viscosity or may become poorly soluble in the above-mentioned mixed solvent after undergoing solid phase polymerization through so-called heat treatment, but such polyesters may also be subject to the present invention. Figure 1 is one embodiment of the polyester of the invention.

The polyester of the present invention is usually prepared by: (1) mixing noenylhydroxyne diacetate, 4,4'-biphenol diacetate or its methyl or ethyl substituted product, terephthalic acid and, if necessary, p-acetoxybenzoic acid;
Method for carrying out acetic acid depolycondensation reaction while stirring, (+l)
By mixing phenylhydroquinone, 4,4'-hyphenol or its methyl or haethyl substituted product, diphenyl terephthalate and, if necessary, phenyl p-hydroxybenzoate, and carrying out a dephenol polycondensation reaction while heating and stirring. will be outfitted.

To explain method (1) in more detail, the monomers described above are charged into a polymerization reactor equipped with a stirrer, a nitrogen gas inlet pipe, and a vacuum distillation device, and heated at a temperature of 200 to 350°C under a full nitrogen atmosphere. Heat and react while stirring for 5 minutes to 4 hours. Reduce the pressure to each stopper, and reduce the pressure to 0.1 t.
orr~2. 280~350℃ under Otorr vacuum
A polyester is obtained by carrying out a polycondensation reaction at a temperature of 1 minute to 4 hours. 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 obtained in step 7 can be melt-molded into trench fibers, etc., or it can be cooled and solidified to form so-called chips or powder, and then re-melted and molded. You can also do it. It is also possible to increase the degree of polymerization by performing in-phase polymerization of the solidified (second polymer) under vacuum or in an inert atmosphere below the melting temperature.3 The melting point of the polyester of the present invention before molding is approximately 250°C LJ.
Preferably, the temperature is in the range of about 360°C or less, and more preferably 340°C or less. Here the melting point is DS
Although it can be observed as an endothermic peak by thermal analysis such as C or DTA, it almost coincides with the softening point measured by the following measurement method, and the melting point may be estimated by this method. That is, a flaky sample is sandwiched between cover glasses, and while observed with a polarizing microscope, the sample is heated at a heating rate of approximately 0°C/min, and the melting point is determined by measuring the temperature at which it begins to flow (softening point). presume.

The polyester of the present invention can be easily formed into, for example, WI navy blue, a film, a tape, a resin, etc. using a known method. [i- For production, normal 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. This i
A linois diameter of 0.08 to 1.0 mm is usually used. The polyester melt extruded in this way is ν) either quenched at present, or passed through a high-temperature, roaring atmosphere provided by a heating cylinder or heat-insulating cylinder under the spinneret (C), and then cooled and solidified. The draft rate at this time is usually 1.2 to 1000, and the winding speed is F.
The range of i30 to 5000 m/min is preferable.

The polyester fiber thus obtained has a high modulus 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; it is not preferable to carry out the heat treatment under such a high tension that the structure of the fibers will be destroyed, but under tension lower than this, the effect is small. Further, during the heat treatment, an anti-fusing agent such as talc or graphite may be attached if necessary. moreover,
To prevent the decomposition of polyester by oxygen and remove the 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.

Also, in the case of films, tapes, resin moldings, etc. other than fibers, there is a difference between the above-mentioned case of fibers and the like. ! 1, each is molded and heat treated using conventional methods.

The polyester of the present invention has an unusually low melting point suitable for melt molding as an aromatic polyester whose main chain is composed only of p-oriented benzene rings, biphenylene rings, and ester bonds, and has a fluidity in the molten state. Therefore, it has excellent properties such as extremely smooth melt molding and stiffness. In addition, the fibers melt-spun from the polyester of the present invention have an extremely high strength increase rate due to heat treatment, so that a high strength of 189/d or more can be obtained by heat treatment within an extremely short time, for example, within 2 hours. ] The problem of long processing times, which was considered to be a major factor in the difficulty of implementing the two-article system, can be easily resolved.

In addition, Japanese Patent Publication No. 58-502227 states that if fibers are made from melt-anisotropic polyester, coated with an aqueous solution of potassium chloride or potassium iodide, and then heat-treated, the strength of the fibers can be increased with a short heat treatment. Although it is disclosed that this type of coating process increases
In certain applications, for example as reinforcing fibers in rubber and plastics, problems with adhesion often arise.

In this regard, the polyester of the present invention has a high rate of improvement in physical properties by heat treatment, due to the inherent properties of the polyester itself, even without such coating processing.

Such improvements in physical properties through heat treatment are 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. can.

The polyester of the present invention has a faster rate of increase in the strength of molded products by heat treatment than conventional polymers (polymer proposed in Japanese Patent Publication No. 53-65421) that have a relatively similar molecular structure. significantly larger. The reason for this is not clear, but the thermal mobility of the polyester chain is based on the fact that the phenyl-substituted paraphenylene group, 4,4'-biphenylene group, and paraphenylene group are arranged in a sea fence. It is thought that this process is unique in terms of the diffusional mobility of low-molecular substances produced as by-products during phase polymerization.

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 atmosphere completely containing oxygen, 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 advantageous for industrial implementation.

Other features of the polyester of the present invention are that its molded articles, e.g. It also has excellent physical properties. Furthermore, the polyester of the present invention has high strength and elongation of the molded product (fiber) as it is molded (spun).
It has excellent chemical resistance and the molded product (411 fiber) has a low expansion rate.

Since the polyester of the present invention has the various characteristics described above, it can be used as reinforcing fibers such as tire cords, fibers used in ropes, cables, woven fabrics, bulletproof clothing, etc., films, and resins. It can be mainly used for industrial materials such as.

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

Example 1 Polymerization step Phenylhydroquinone diacetate 54.2 F, (0
, 20 mol), 4,4'-biphenol diacetate 2
7.1? (0.10 mol), terephthalic acid 47.3
F (0.3 o mol) and p-acetoxybenzoic acid 36.
79 (0.20 mol) was charged into a polymerization reactor equipped with a stirrer and a vacuum distillation apparatus, and the temperature was raised to 320°C over 80 minutes while stirring in a nitrogen stream, and the reaction was carried out at 320°C for 300 minutes. The pressure was gradually reduced over a further 5 minutes, and then the reaction was carried out for 15 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: 0 74.7%, H3.6% theoretical value; 0
74.7%, H3.7% These results show that a polyester having a copolymerization composition approximately corresponding to the monomer charge ratio was produced. That is, the proportion of each structural unit is as follows.

The differential thermal analysis (DTA) chart of this polyester is
It has a small melting endothermic peak at 290°C, and thermogravimetric analysis (
The decomposition temperature determined by TG) was approximately 430°C. Further, the softening point was 300°C, and it exhibited optical anisotropy in a molten state. The intrinsic viscosity was 4.1, and the melt viscosity at 320°C was 88 poise.

After drying the resulting spun chip at 180°C for 8 hours under reduced pressure,
Extruder with screw diameter 25 mm and spinneret diameter 0, 251
It was extruded at a spinning hole temperature of 330° C. using a melt-spinning equipment ft equipped with a spinning hole of 6 holes and wound at a speed of 180 m/min. The obtained polyester fiber has a single yarn denier of 16. L strength 8. : M/d, elongation ratio: 1.9, initial modulus: 46 (1/d).

Heat Treatment Process The sample was placed in a cylindrical flask having an internal volume of 10 tons, and while nitrogen was flowing at 2/min, the temperature was raised to 300° C. for 40 minutes, and heat treatment was further performed at 300° C. for 60 minutes. The resulting heat-treated system had a strength of 18.89/d, an elongation of 5.1%, and an initial modulus of 4459/d, indicating that 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. 53-65421 showed a strength increase rate of This illustrates the inferiority compared to fibers obtained from the inventive polyester.

Phenylhydroquinone diacetate 1309 (0,48
Polyester was obtained in the same manner as in Example 1 from terephthalic acid 769 (0.46 mol). This polyester had a softening point of 340°C and an intrinsic viscosity of 2.1. This polyester was processed using the same melt spinning apparatus as in Example 1.
It was extruded at a spinning hole temperature of 350°C and wound at a speed of 73 m/min. The obtained polyester fiber had a single yarn denier of 18 and a strength of 1.1 f/d.

Shin! 10.4s, initial modulus was 322 f/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 5.5 r/d and 16.9 S'/d, respectively.
18.2 y/a, 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 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 of these polyesters exhibit melt anisotropy,
When taken out from the polymerization apparatus, it had stringability.

In addition, a strong sheet-like material was obtained using a hot press heated to a temperature higher than the softening point of any of the polyesters.

Claims (1)

[Claims] ] General formula % Formula % (R and R' in the formula are hydrogen atoms, methyl groups or ethyl groups,
x and x' are integers of 1 to 4, and the molar fraction of each unit of k, l, m, and nFi, and these are 0.95m≦
1<+z≦1.05m) A polyester substantially consisting of structural units represented by the formula: