JPH0251524A - Preparation of aromatic polyester composition - Google Patents

Abstract

PURPOSE:To obtain the title compsn. having excellent stability of residence during molding, mechanical properties under a use condition at high temp. and resistance to heat discoloration by incorporating a polymn. catalyst and/or a heat-resistant agent under specified conditions when this compsn. forming an anisotropic molten state is prepd. CONSTITUTION:When an arom. polyester contg. a polymn. catalyst (e.g., dibutyltin maleate) and/or a heat-resistant agent (e.g., a compd. of formula I or II) and forming an anisotropic molten state (e.g., a copolymer of p- hydroxybenzoic acid, 4,4'-dihydroxybiphenyl and terephthalic acid) is prepd., 0.001-2wt.%, based on said polyester, polymn. catalyst and/or heat-resistant agent coated with an arom. polyester which is the same as or different from said arom. polyester (e.g., polyethylene terephthalate) is added thereto and homogeneously dispersed before the polymn. of the arom. polyester is completed.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention has good retention stability during melting, especially during molding, and has excellent mechanical properties and thermal coloring under the conditions of use in a high-temperature atmosphere. The present invention relates to a method for producing an aromatic polyester composition that forms an anisotropic melt phase with excellent prevention properties.

[Conventional technology]

In recent years, the demand for higher performance plastics has been increasing, and many polymers with various new performances have been developed and put on the market.Among them, optically anisotropic liquid crystals, which are characterized by parallel alignment of molecular chains, Polymers are attracting attention because of their excellent mechanical properties.

Examples of polymers that form an anisotropic melt phase include liquid crystal polymers obtained by copolymerizing p-hydroxybenzoic acid with 4,4'-dihydroxybiphenyl, terephthalic acid, and isophthalic acid (Japanese Patent Publication No. 57-24407, 60-250
46), a liquid crystal polymer made by copolymerizing 6-hydroxy-2-naphthoic acid with p-hydroxybenzoic acid (Japanese Patent Laid-Open No. 5
4-77691) and the like are known.

In addition, a liquid crystal polymer made by copolymerizing p-hydroxybenzoic acid and polyethylene terephthalate (Japanese Patent Publication No. 56-1801
6) and a liquid crystal polymer prepared by copolymerizing p-hydroxybenzoic acid with 4,4'-dihydroxybiphenyl, t-butylhydroquinone, and terephthalic acid (Japanese Patent Laid-Open No. 164-1982).
No. 719) has been proposed.

However, since these have a higher melting point than general polyesters such as polyethylene terephthalate, there are problems with coloring during polymerization and molding, and deterioration of mechanical properties due to thermal deterioration.

As one of the countermeasures, Japanese Patent Application Laid-Open No. 59-4622,
A method has been proposed in which the polymerization is divided into the steps of (1) prepolymer synthesis and (2) solid phase polymerization of the prepolymer, and a phosphorous acid compound is added immediately before the in-phase polymerization step. This method has been shown to yield polymers with a low degree of coloration and good thermal stability.

Further, JP-A-6LL13821 discloses mixing a phosphorous acid compound with a polymer in a hopper in an extruder before spinning.

[Problem to be solved by the invention]

However, the method of Japanese Patent Application Laid-Open No. 59-4622,
Although it is effective in preventing coloration in the solid-state synthesis process, which requires a long-term high-temperature reaction, the process becomes complicated and is not sufficient for practical use.

It has also been found that the method disclosed in JP-A-61-113821 has the disadvantage that the dispersion is not necessarily sufficient and the process becomes complicated.

An object of the present invention is to provide a method for obtaining a polymer with a low degree of coloration and excellent thermal stability by melt polymerization without going through complicated steps.

[Means to solve the problem]

In order to solve the above problems, the present invention takes the following measures.

That is, the method for producing an aromatic polyester composition of the present invention includes the steps of completing the polymerization of an aromatic polyester when producing an aromatic polyester composition that contains a polymerization catalyst and/or a heat-resistant agent and forms an anisotropic melt state. First, 0.001 to 2% by weight of a polymerization catalyst and/or heat resistant agent is added to the aromatic polyester in a state where the aromatic polyester is coated with an aromatic polyester of the same type or a different type, and is uniformly dispersed. After that, the polymerization is completed.

Examples of the polymerization catalyst used in the present invention include compounds such as antimony, titanium, germanium, tin, zinc, lead, aluminum, magnesium, calcium, manganese, sodium, potassium, and cobalt, including monobutyltin oxide, dibutyltin oxide, and acetic acid. Tin compounds such as stannous, dibutyltin dimaleate, and dibutyltin maleate polymers, potassium acid, zinc acetate, and antimony trioxide are preferred, and dibutyltin dimaleate is most preferred.

Further, examples of the compound used as a heat resistant agent include an organic phosphorus compound and/or a hindered phenol compound. As the organic phosphorus compound, a compound containing one or more trivalent phosphorus atoms in its molecular structure is used. Specific examples include lauryl phosphite, triisooctyl phosphite, trioleylphosphite, triphenyl phosphite, triotadecyl phosphite, triisodecyl phosphite, tri-n-butyl phosphite, tris-2-ethylhexyl phosphite. , tristearyl phosphite, tris-2,4-di-tert-butylphenyl-phosphite, tristridecyl phosphite, tris-4-phenylphenol-phosphite,
Trisnonylphenylphosphite, phenylisodecylphosphite, phenyldioctylphosphite, diphenylnonylphenylphosphite, diphenylisodecylphosphite, diphenylisooctylphosphite, diphenyldecylphosphite, diphenyltridecylphosphite, tetraphenyl Dipropylene glycol diphosphite, tetralauryl bisphenol A diphosphite, tetratridecyl bisphenol A
Organic phosphite compounds such as diphosphite, tetraphenyltetratridecylpentaerythritol tetraphosphite, diisodecylpentaerythritol diphosphite, dilaurylpentaerythritol diphosphite, distearylpentaerythritol diphosphite, dinonylphenylpentaerythritol diphosphite and triphenylphosphine, tri-ethylphosphine, tributylphosphine, trimethylphosphine, tri(p-methylphenyl)phosphine, tri(
Examples include organic phosphine compounds such as nonylphenyl) phosphine.

Particularly preferred compounds are triphenylphosphine and compounds having the structure:

In the formula, when X=t-C41L+, Y=Il, X=H,C
11ff, Cztls indicates a combination of Y=t-CaHq.

The hindered phenol compound used in the present invention has one or more phenolic hydroxyl groups in its molecular structure, and the aromatic hydrogen adjacent to the phenolic hydroxyl group is substituted with a bulky tertiary carbon.

Specific examples include 2,4-dimethyl-6-tert-butylphenol, 2,6-di-tert-butylphenol, 2,6-
Di-tert-butyl-p-cresol, 4-hydroxymethyl-2,6-di-tert-butylphenol, 2,6-di-tert-butylphenol
Butyl-α-dimethylamino-p-cresol, 2,5
-di-tert-butyl-4-ethylphenol, 4,4-bis-(2゜6-di-tert-butylphenol), 2.2'-
Methylene-bis-4-methyl-6-tert-butylphenol, 2,2'-methylene-bis(4-ethyl-6-tert-butylphenol), 4,4'-methylenebis(6-tert-butyl-0- cresol), 414'-methylene-bis (2,6-di-tert-butylphenol), 2,2-methylenebis(4-methyl-6-cyclohexylphenol), 4,4'-ptylidene-bis(3-methyl -6
-tertiary butylphenol), 4,4'-thiobis(6-
Tert-butyl-3-methylphenol, bis(3-methyl-4-hydroxy-5-tert-butylbenzyl) sulfide, 4,4'-thiobis(6-tert-butyl 0-cresol), 2,2'- Thiobis(4-methyl-6-tert-butylphenol), 2,6-bis(2'-hydroxy-3
'-tert-butyl-5-methylbenzyl)-4-methylphenol, diethyl ester of 3,5-di-tert-butyl-4-hydroxybenzylphosphonic acid, 2,2-dihydroxy-3,3'-di(α -methylcyclohexyl)3
．． 5'-dimethyl-diphenylmethane, n-octadecyl-3(3',5-di-tert-butyl-4-hydroxyphenyl)propionate, 6-(4-hydroxy-3,5
-di-tert-butylanilino)-2,4-bis-octyl-
Thio-1,3,5 triazine, hexamethylene glycol-bis[β-(3,5-di-tert-butyl-4-hydroxyphenol)propionate], N,N-hexamethylene-bis(3,5-di-tert-butyl-4-hydroxyphenol)propionate 3-butyl 4-hydroxyhydrocinnamic acid amide), 2,2'thio[diethyl-bis-
3(3,5-di-tert-butyl-4-hydroxyphenyl)
dioctadecyl ester of 3,5-di-tert-butyl-4-hydroxybenzylphosphone;
Tetrakis[methylene-3(3,5-di-tert-butyl-4
-Hydroxyphenyl)propionate comethane, 1,
3.5-trimethyl 2,4゜6-tris(3,5-di-tert-butyl-4-hydroxybenzylbenzene, L L
, 3-)IJs(2-methyl-4-hydroxy-5-ditert-butyl-phenyl)butane, tris(3,5-ditert-butyl-4-hydroxyphenyl)isocyanurate, tris[β-( Examples include 3,5-di-tert-butyl-4-hydroxyphenyl)propionyloxyethyl]isocyanurate, but among these, those with a molecular weight of 500 or more tend to evaporate in high-temperature atmospheres (and are therefore less effective). obtained and preferred.

Particularly preferred compounds are those having the following structure.

(I) In the production method of the present invention, the polymerization catalyst and/or heat resistant agent is added in an amount of 0.001 to 2% by weight, preferably 0.01 to 1% by weight, based on the polymer. o,
If it is less than oot% by weight, the coloring prevention effect is poor, and if it exceeds 2% by weight, it is excessive compared to the effect and also has disadvantages such as lowering the heat resistance of the polymer. Further, the organic phosphorus compound and/or hindered phenol compound used as the heat resistant agent may be used alone or in combination.

The aromatic polyester used in the production method of the present invention is an aromatic polyester that forms an anisotropic melt phase. The temperature at which an anisotropic melt phase is formed needs to be below the decomposition temperature of the additives added, but aromatic polyesters that form an anisotropic melt phase at temperatures below 400°C are usually preferably used. .

In the present invention, the aromatic polyester of the same or different type that coats the polymerization catalyst and/or the heat-resistant agent does not have to be an aromatic polyester that forms an anisotropic melt state (e.g., an aromatic polyester containing ethylene terephthalate units). In this case, it is preferable to coat with a polyalkylene terephthalate such as polyethylene terephthalate.

The coating may be in any form, but it is preferable to completely cover the additive in the form of a film, bottle, etc. If the coating is insufficient, the polymer may be added to the reaction system before it melts. , the effect will be insufficient. That is,
In the case of a film, it is preferable to tie it with a string made of the same polymer, or in the case of a bottle, it is preferable to fill it with a stopper made of the same polymer and add it. These additives may be added at any time before the completion of polymerization, but it is convenient to add them before the start of vacuum polymerization, and they can also be added together with the raw materials at the beginning of the reaction.

If these additives are added without coating,
For example, the acetic acid or acetic anhydride during the acetylation reaction may deactivate it, resulting in no effect at all, or the polymerization activity may be lower than when it is not added.

That is, it has been found that by coating these additives with aromatic polyester, the coated polymer melts and acts efficiently in the latter half of the polymerization, when the amount of acetic acid and acetic anhydride in the system is reduced.

The aromatic polyester used in the production method of the present invention may have a structure containing small amounts of other bonding species such as amide bonds and imide bonds in addition to ester bonds.

Examples of the aromatic polyester preferably used in the present invention include polymers having any of the following structural formulas (V) to (■).

1←0−X−C0+ ・・・・・・・・・・・・ (V) −(−0−Y−0□c−z−co+ ・・・・・・・・・・・・(■) Show Note that the carbonyl groups of the dicarboxylic acid component in formula (Vl) are in a meta and/or para relationship with each other.

) The aromatic polyester particularly preferably used in the present invention has the above structural formula (V), (Vl) and/or (■)
It is a polymer with a structure of

The content of the structural unit (V) is preferably 40 to 90 mol%, more preferably 60 to 80 mol% of the total.

The aromatic polyester that can be preferably used in the present invention can be produced according to a conventional polyester polycondensation method, and is not particularly limited, but a typical production method is when X is -CHzCl
□For other than -, for example, the following (11-(4) method, X is -CI
For l□CH2-, method (5) can be mentioned.

All of these can be efficiently polymerized by applying reduced pressure during polymerization.

(1) Acylated products such as p-acetoxybenzoic acid, 4.
A method for producing by deacetic acid polycondensation reaction from an acylated aromatic hydroxy compound such as 4'-diacetoxybiphenyl and an aromatic dicarboxylic acid such as terephthalic acid.

(2) A method for producing by acetic acid depolymerization reaction from an aromatic dihydroxy compound such as p-hydroxybenzoic acid or 4,4'-dihydroxybiphenyl, an aromatic dicarboxylic acid such as terephthalic acid, and acetic anhydride.

(3) A method for producing phenyl esters of p-hydroxybenzoic acid and aromatic dihydroxy compounds such as 4,4'-dihydroxybiphenyl and diphenyl esters of aromatic dicarboxylic acids such as terephthalic acid by dephenol polycondensation.

(4) After reacting aromatic dicarboxylic acids such as p-hydroxybenzoic acid and terephthalic acid with a desired amount of diphenyl carbonate to form diphenyl esters,
4. A method in which an aromatic dihydroxy compound such as 4'-dihydroxybiphenyl is added and a phenol-depleted polycondensation reaction is performed.

(5) A method of producing by method (1) or (2) in the presence of polyester such as polyethylene terephthalate.

It is also possible to add another additive to the aromatic polyester composition to which the additive has been added before completion of polymerization, just before extrusion or injection molding.

The composition of the present invention may further contain reinforcing agents such as glass fibers and carbon fibers, and fillers such as talc and silica.

In the present invention, the completion of polymerization of the aromatic polyester refers to a state in which the molecular weight has increased to the point where the polymer can sufficiently maintain mechanical strength and toughness, and substantially at 60°C.
In pentafluorophenol, the logarithmic viscosity at a polymer concentration of 0.1 g/d1 is -0-CH2C in the polymer chain.
11□-2.0aj/g or more if it does not contain -〇-, and 1.0aj/g or more if it contains -〇-CHzCHz-0. Refers to the state where the Oa/g or higher.

In addition, the aromatic polyester composition produced according to the present invention has a liquid crystal start temperature of 220°C or higher and a heat distortion temperature of 60°C or higher in terms of heat resistance, and a liquid crystal start temperature of 390°C or lower in terms of molding temperature. Moreover, it is preferable that the heat deformation temperature is 370°C or less, particularly when the liquid crystal start temperature is 260 to 3
It is preferable that the temperature is 50°C and the heat distortion temperature is 190 to 280°C. Here, the heat distortion temperature is based on ASTM 064B at a load of 18.56 kg/c for a 178" thick test piece.
This is the value measured at tA.

〔Example〕

The present invention will be specifically described below with reference to Examples.

The heat resistant agent used in the examples is the following compound.

(Margins below this page) Compound Compound Compound Compound (I a) (I b) (I c) (Id) Compound (n) Compound (V) Compound (III) Compound (Vl) Compound (TV) e e Example 1 75.66 parts by weight of p-acetoxybenzoic acid, 26.80 parts by weight of 4,4-diacetoxybiphenyl, 12.41 parts by weight of t-butylhydroquinone diacetate, 2.83 parts by weight of hydroquinone diacetate, and 27.13 parts by weight of terephthalic acid. Parts by weight and 0.2 parts by weight of a heat-resistant agent (Ic) coated with a polyethylene terephthalate film were charged into a reaction vessel equipped with a stirring blade and a distillation tube, and heated under a nitrogen gas atmosphere for 2 hours.
After reacting at 50 to 340°C for 3.0 hours, the temperature was raised to 350°C, the pressure inside the system was reduced to 1.5 mm and 11 g, and further 1.
The mixture was heated for 0 hours to carry out a polycondensation reaction, and the polymer melt was taken out and cooled. The structural formula of the polymer is shown below. A polymer having this structural formula is referred to as resin A.

1/m/n/o =72/17/8.5/2.
5 In addition, this resin A was placed on the sample stage of a polarizing microscope and the chemical anisotropy was confirmed by raising the temperature, and it showed good optical anisotropy at 307° C. or higher.

Therefore, it is determined that the polymer was in an anisotropic molten state at 307° C. or higher during polymerization.

The logarithmic viscosity of the conopolymer (measured at 60°C and a polymer concentration of 0.Ig/dl in pentafluorophenol) is 4.32.
The melt viscosity at 347° C. and a sliding speed of 1.000 (1/sec) was 2,600 poise. Also, ASTM
The heat distortion temperature of a 1/8” thick test piece (load 18.56 kg/cI11) measured based on 064B is 251
'C.

A pellet of the aromatic polyester composition thus obtained was processed using a Nescool injection molding machine, Promat 40/
25 (manufactured by Jujuki Kogyo 0-suke) under the conditions of a cylinder temperature of 345°C and a mold temperature of 90°C to a thickness of 3 mm x 10 m.
A tensile test piece measuring m x 100 mm was prepared.

This tensile test piece was heat-degraded at 250°C for 500 hours in an open gear, and after measuring the tensile stress retention rate, the whiteness (
A zero value was measured. These results are shown in Table 1.

Examples 2 to 1O Polymerization was carried out in the same manner as in Example 1, except that the polymerization catalyst and/or heat resistant agent listed in Table 1 was used instead of the organic phosphorus compound (Ic) coated with a polyethylene terephthalate film. I evaluated it. These results are shown in Table 1.

Example 11 68.81 parts by weight of p-hydroxybenzoic acid, 12.37 parts by weight of 4,4' dihydroxybiphenyl, 70 parts by weight of acetic anhydride
．． 87 parts by weight of terephthalic acid, 11.04 parts by weight of terephthalic acid and 19.15 parts by weight of polyethylene terephthalate having an intrinsic viscosity of about 0.6 dl/g (polymerization catalyst dibutyltin simalea coated with a polyethylene terephthalate film).
0.015 parts by weight was charged into a reaction vessel equipped with a stirring blade and a distillation tube, and acetic acid depolycondensation was carried out under the following conditions.

First, under a nitrogen gas atmosphere at 100 to 250°C for 5 hours,
After reacting at 50-300℃ for 1.5 hours, 300℃
Then, the pressure was reduced to 0.5 mm and 11 g in 1 hour, and then 2.
When the reaction was allowed to proceed for 25 hours and the polycondensation was completed, a nearly theoretical amount of acetic acid was distilled out, yielding a resin having the following theoretical structural formula. A polymer having this structural formula is referred to as resin B.

1/m/n = 75/10/15 Also,
This polyester was placed on the sample stage of a polarizing microscope, the temperature was raised, and the optical anisotropy was confirmed. As a result, the liquid crystal initiation temperature was 2.
The temperature was 64° C., indicating good optical anisotropy. Therefore, it is determined that the polymer was in an anisotropic molten state at 264° C. or higher during polymerization. The logarithmic viscosity of this polyester (measured under the same conditions as in Example 1) was 2.21 dl/g, and the temperature was 304°C.
The melt viscosity at a rubbing speed of 1,000/sec was 3,500 voids.

Also, 178" measured based on ASTM D648
The heat deformation temperature (load: 18.56 kg/c) of the thick test piece was 206°C.

The pellets of the aromatic polyester composition thus obtained were molded and evaluated in the same manner as in Example 1 under the conditions of a cylinder temperature of 300°C and a mold temperature of 90°C. These results are shown in Table 1.

Example 12 Polymerization catalyst dibutyltin dimaleate 0.015 heat resistant agent 1cO instead of 2 parts and heat resistant agent 0.1
Polymerization and evaluation were conducted in the same manner as in Example 11 except that parts by weight were used. These results are shown in Table 1.

Example 13 p-acetoxybenzoic acid 82.86 parts by weight, 4.4'-
28.18 parts by weight of diacetoxybiphenyl, 9.53 parts by weight of hydroquinone diacetate, and 1 part by weight of terephthalic acid.
9.10 parts by weight, 6.37 parts by weight of isophthalic acid, 0.2 parts by weight of a heat resistant agent coated with Unitika's "U Polymer" U-100 film, and 7001 parts by weight of a heat resistant agent were added to a stirring blade and a distillation tube. After reacting at 250 to 360°C for 3 hours in a nitrogen gas atmosphere,
The pressure was reduced to Hg, and the mixture was further heated for 1 hour to complete polycondensation, thereby obtaining a resin having the following theoretical structural formula. A polymer having this structural formula is referred to as resin C.

7-[Phase] co91 / m / n = 75 / 18.75 / 6.25 In addition, this polyester was placed on the sample stage of a polarizing microscope, the temperature was raised, and the optical anisotropy was observed. The liquid crystal start temperature was 304°C, and good optical anisotropy was exhibited. Therefore, it is judged that the polymer was in an anisotropic molten state at 304° C. or higher during polymerization.

The logarithmic viscosity of this polyester (measured under the same conditions as in Example 1) was 4.37 dl/g, and the melt viscosity at 344° C. and a sliding rate of L 000 /sec was 4,100 poise. In addition, I measured based on ASTM D648
/8" thick test piece heat distortion temperature (load 18.56 kg
/ cII! ) was 261°C.

The pellet of the aromatic polyester composition thus obtained was molded and evaluated in the same manner as in Example 1 under the conditions of a cylinder temperature of 350°C and a mold temperature of 90°C. These results are shown in Table 1.

Example 14 72.58 parts by weight of p-acetoxybenzoic acid and 51.61 parts by weight of polyethylene terephthalate with an intrinsic viscosity of about 0.641/g and 0.2 parts by weight of heat resistant agent Ic and heat resistant agent V0 in a polyethylene terephthalate bottle.
．． 1 part by weight was charged into a reaction vessel equipped with a stirring blade and a distillation tube, and heated at 200 to 250°C for 5 hours at 25°C under a nitrogen gas atmosphere.
After reacting at 0-280'C for 2 hours, 280'C,
The pressure was reduced to 0.6 mm and 11 g in 1 hour, and the reaction was continued for an additional 2 hours, whereupon an almost theoretical amount of acetic acid was distilled out, and a resin having the following theoretical structural formula was obtained. A polymer resin having this structural formula is designated as D.

p/m=60/40 In addition, this polyester was placed on a sample stage of polarized light'; A Soh H, and the temperature was raised to observe the optical anisotropy. It showed good optical anisotropy. Therefore, it is determined that the polymer was in an anisotropic molten state at temperatures above 240''C during polymerization.

The logarithmic viscosity of this polyester (measured under the same conditions as in Example 1) was 0.71 dl/g, and the melt viscosity at 280° C. and a shear rate of 1,000/sec was 810 voids. In addition, 1 measured based on ASTM D648
/8' thick test piece heat distortion temperature (load 18.56 kg/
cIl) was 63°C.

A pellet of the aromatic polyester composition obtained in this way was heated at a cylinder temperature of 280°C and a mold temperature of 90°C.
It was molded and evaluated in the same manner as in Example 1 under the following conditions. These results are shown in Table 1.

Example 15 101.88 parts by weight of p-acetoxybenzoic acid, and 6
- Acetoxy-2-naph I-heat resistant agent I coated with 43.40 parts by weight of engineering acid and polyethylene terephthalate film
0.2 parts by weight of I and 0.1 part by weight of heat resistant agent (I) were charged into a reaction vessel equipped with a stirring blade and a distillation tube, and after reacting for 4 hours at 250 to 280 in a nitrogen gas atmosphere, the mixture was heated to 300'C.
After raising the temperature to 0.9 mm and 11 g,
．． It was heated for 5 hours to perform a polycondensation reaction, and the polymer melt was taken out and cooled. The structural formula of the polymer is shown below. A polymer having this structural formula is referred to as resin E.

It/m = 75/25 Also, place this polyester on the sample stage of a polarizing microscope,
As a result of observing the optical anisotropy at elevated temperature, the liquid crystal initiation temperature was 256° C., indicating good optical anisotropy. Therefore, it is determined that the polymer was in an anisotropic molten state at temperatures above 256"C during polymerization.

This polyester had a logarithmic viscosity (measured under the same conditions as Example 1) of 4.87 dl/g, and a melt viscosity of 2.800 poise at 296° C. and a rubbing rate of 1,000/sec. In addition, the heat distortion temperature of a 1/8” thick test piece (load 18.56 kg) was measured based on ASTM D648.
/cI11) was 177°C.

The pellet of the aromatic polyester composition thus obtained was molded and evaluated in the same manner as in Example 1 under the conditions of a cylinder temperature of 300°C and a mold temperature of 90°C. These results are shown in Table 1.

Example 16 65.30 parts by weight of p-acetoxybenzoic acid, 48.26 parts by weight of 4.4' dihydroxyphenyl, 29.66 parts by weight of terephthal% and 0.2 parts by weight of heat resistant agent 1c coated with polyethylene terephthalate film, and 0.1 part by weight of the heat resistant agent (1) was charged into a reaction vessel equipped with a stirring blade and a distillation tube, and the mixture was reacted for 5 hours at 250 to 280 ℃ in a nitrogen gas atmosphere, and then the contents were cooled and pulverized.

This polyester was placed on the sample stage of a polarizing microscope, the temperature was raised, and the optical anisotropy was observed. As a result, the liquid crystal onset temperature was 3.
The temperature was 28°C, showing good optical anisotropy. Therefore, it is determined that the polymer was in an anisotropic molten state at temperatures above 328° C. during polymerization.

This was reduced in pressure to 0.7 mm and 11 g in a rotary heating container, and reacted at 300 to 350°C for 15 hours to obtain a resin having the following theoretical structural formula. A polymer having this structural formula is referred to as resin F.

(!/m = 67/33 The logarithmic viscosity of this polyester (measured under the same conditions as in Example 1) is 3.21 dl/g, and the melt viscosity at 413°C and a sliding speed of 1,000/sec is 3800 voids. 178 measured based on ASTM 0648.
"Heat deformation temperature of thick test piece (load 18.56 kg 10+
I) is ivy at 331℃.

The pellets of the aromatic polyester composition obtained in this way were heated at a cylinder temperature of 390'C and a mold temperature of 220'C.
It was molded and evaluated in the same manner as in Example 1 under the following conditions. These results are shown in Table 1.

Comparative Example 1 Evaluation was carried out in the same manner as in Example 1, except that polymerization was carried out in Example 1 without adding the heat-resistant agent Ic, and 0.2% by weight of the heat-resistant agent 1c was dry-blended with the obtained polymer. These results are shown together in Table I.

Comparative Examples 2 to 10 Comparative Examples 2, 3, 4, 5, 6, 7, 8, 9, and 10 are the same as the examples except that the polymerization catalyst and/or heat resistant agent were added without being coated with aromatic polyester. 1. 4.10.
Polymerization and evaluation were conducted in the same manner as in 11.12.13.14.15.16. These results are shown in Table 1.

Comparative Examples 11 to 13 Comparative Examples 11, 12, and 13 are the same as those of Example 1, respectively, except that the polymerization catalyst and/or heat resistant agent were not coated with aromatic polyester and were added 1 hour before the start of pressure reduction during polymerization. 11
．． Polymerization and evaluation were conducted in the same manner as in Example 12. These results are shown in Table 1.

Comparative Example 14.15 Comparative Example 14.15 is the same as Example 1, except that the polymerization catalyst and/or heat resistant agent were not added before the polymerization was completed, and after the polymerization was completed, they were melt-mixed in a 40mm diameter single-screw extruder. Polymerization and evaluation were conducted in the same manner as in Example 12. These results are shown in Table 1.

Comparative Examples 16 to 21 Comparative Examples 16, 17, 18, 19, 20, and 21 were polymerized in the same manner as Examples 1, 11, 13, 14, 15, and 16, respectively, except that no polymerization catalyst and/or heat resistant agent was added. ,evaluated. These results are shown together on the front surface.

(Margins below this page) As seen in Examples 1 to 16, the aromatic polyester produced by the method of the present invention has a high tensile strength retention rate of 90% or more, a high whiteness of 49 or more, and can be used in high-temperature atmospheres. Excellent mechanical properties and heat discoloration resistance under conditions of use.

On the other hand, when a heat-resistant agent is triblended after polymerization as seen in Comparative Example 1, as seen in Comparative Examples 2-10, the polymerization catalyst and/or heat-resistant agent is coated with an aromatic polyester. Comparative Example 11~
As seen in Comparative Example 14.15, when the polymerization catalyst and/or heat resistant agent was added during polymerization without being coated with aromatic polyester, and when the heat resistant agent was melt-kneaded after polymerization as seen in Comparative Example 14.15. As seen in Comparative Examples 16 to 21, when no polymerization catalyst and/or heat resistant agent is added, the tensile strength retention rate is as low as 78% or less,
The whiteness is also low, at 39 or less (poor mechanical properties and thermal discoloration resistance under conditions of use in a high-temperature atmosphere).

〔Effect of the invention〕

The present invention achieves good retention stability during molding by adding additives coated with aromatic polyester before completion of polymerization and then uniformly dispersing them in an anisotropic molten state. Under the conditions of use in a high-temperature atmosphere, an aromatic polyester composition with improved mechanical properties and thermal discoloration resistance (X) can be obtained without going through a complicated process.

Claims (3)

[Claims] (1) When producing an aromatic polyester composition containing a polymerization catalyst and/or a heat-resistant agent and forming an anisotropic melt state, 0.001 It is characterized by adding ~2% by weight of a polymerization catalyst and/or a heat-resistant agent in a state covered with an aromatic polyester of the same kind or a different kind to the aromatic polyester, and completing the polymerization after uniformly dispersing the aromatic polyester. A method for producing an aromatic polyester composition. (2) The method for producing an aromatic polyester composition according to claim 1, characterized in that a tin compound is used as a polymerization catalyst. (3) The method for producing an aromatic polyester composition according to claim 1, characterized in that an organic phosphorus compound and/or a hindered phenol compound is used as the heat resistant agent.