JP2002363301A - Polyester molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyester polymer having controlled mol.wt., mol.wt. distribution, and morphology and a clean molding which is prepared by using the polymer, has high strengths/high modulus, and contains no impurity. SOLUTION: The polyester polymer mainly comprises repeating units derived from ethylene terephthalate, has a number average mol.wt. [by gel permeation chromatography(GPC), in terms of polystyrene] of 25,000 or higher, does not substantially contain a branched structure, and has a half value width of crystal melting peak of 10 deg.C or narrower and a cyclic trimer content (by GPC) of 0.8 wt.% or lower. Moldings such as fibers, films, and injection molded items are prepared from the polyester polymer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention provides a polyester polymer having a controlled molecular weight, molecular weight distribution, and morphology, and a high-strength / high-modulus-free clean molded article using the same. .

[0002]

2. Description of the Related Art Polyethylene terephthalate (PET)
Polyester represented by is excellent in mechanical properties, and chemical properties, depending on the properties of each polyester, for example, used in high-strength fibers for clothing and industrial materials, films, various molded products I have. In general, it is known that the mechanical properties and thermal properties of these molded products are not controlled solely by the chemical structure of the polyester, but are also changed by the molecular weight, molecular weight distribution and morphology of the polymer chains. In particular, in the case of a high-strength fiber, it is considered that it is preferable to have a morphologically extended and cut chain structure in order to improve the strength and the elastic modulus. In the case of polyethylene terephthalate (PET), which is a typical polyester, bis (2-hydroxyethyl) terephthalate is produced by esterification or transesterification of terephthalic acid or dimethyl terephthalate with ethylene glycol. It is industrially manufactured by a melt polycondensation method in which polycondensation is performed using a catalyst below. In such a method, it takes a very long polymerization time to obtain a high molecular weight, a high polymerization temperature causes thermal degradation in a long-time polymerization reaction, and the molecular weight distribution Mw / Mn is always reduced to 2 by transesterification. There are problems such as that the molecular weight distribution is close to being uncontrollable, that the molecular chain is in a so-called random coil form, that the polyester molecular chain always has a constant entanglement, and that the amount of the generated cyclic trimer is large. Further, as a method for obtaining a high-molecular-weight polyester, a method based on solid-phase polymerization is also known. In this method, a polyester chip obtained by melt polymerization is heated at a temperature lower than the melting point of the polyester under reduced pressure or in an inert gas. In this method, the polymer can be polymerized to a relatively high degree of polymerization while suppressing the deterioration of the polymer, and the amount of the cyclic trimer contained in the polymer can also be suppressed. Since it is a random coil, entanglement of polyester molecular chains cannot be removed. Although the molecular weight distribution Mw / Mn is a value larger than 2, the molecular weight distribution is complicatedly correlated with the chip shape, the polymerization temperature, and the like, and cannot be sufficiently controlled.

There is also a method of polymerizing from a cyclic oligomer as disclosed in JP-A-1-197522. However, in this method, since the polymerization temperature is higher than the melting point of polyester, the obtained polymer is The molecular weight distribution Mw / Mn is 2
And the content of the cyclic trimer is about the same as that of the polyester polymer obtained by melt polymerization. Also, Journal of Polymer Science Part A: p
In Polyester Chemistry, Vol. 38, 3360-3368 (2000), a polyester is polymerized from a cyclic dimer, but the weight average molecular weight in terms of polystyrene measured by GPC is at most about 44500, and a sufficient molecular weight has not been obtained. The reason why the high molecular weight polyester does not reach a high molecular weight by the above method is unknown, but it is presumed that the conditions such as polymerization temperature, polymerization time, polymerization catalyst and the like individually or in a complex manner could not obtain a high degree of polymerization. You. As described above, in the conventional polyester polymerization method, the polymerization time of a product having a high molecular weight is long, the molecular weight distribution and morphology cannot be controlled, and a large amount of cyclic trimer is contained.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to control the molecular weight, molecular weight distribution and morphology,
An object of the present invention is to provide a molded article having a small number of entanglements of molecular chains, an extended chain structure, a small amount of impurities such as cyclic trimmers, and a clean and excellent safety.

[0005]

That is, the present invention provides a polystyrene-equivalent molecular weight of 25 as measured by gel permeation chromatography (GPC) using ethylene terephthalate as a main repeating unit.
A molded article comprising a polyester polymer composed of a polyester substantially free of a branched structure of 000 or more,
The half-width of the crystal melting peak is 10 ° C or less and GPC
A molded product comprising a polyester polymer, wherein the content of the cyclic trimer determined by the above method is 0.8% by weight or less. Specifically, the weight average molecular weight / number average molecular weight is 2 in terms of polystyrene-equivalent molecular weight measured by GPC and a fiber comprising the polyester polymer described above, wherein the melting point is 260 ° C. or higher.
A molded article comprising the polyester polymer described above, characterized by the above. The molded article is a thread, a film, and an injection molded article. Then, by molding the polyester polymer thus polymerized, a clean and safe molded article with less impurities can be obtained for the first time.

Hereinafter, the present invention will be described in detail. The polyester in the present invention is a polyester in the present invention,
A polyester containing terephthalic acid as a main acid component and at least one glycol, preferably at least one alkylene glycol selected from ethylene glycol, trimethylene glycol and tetramethylene glycol as a main glycol component. Further, a polyester in which part of the terephthalic acid component is replaced by another difunctional carboxylic acid component may be used, and / or part of the glycol component is replaced by the above-mentioned glycol or other diol component other than the main component. It may be polyester. Examples of the bifunctional carboxylic acid other than terephthalic acid used herein include, for example, isophthalic acid, naphthalenedicarboxylic acid, diphenyldicarboxylic acid, diphenoxyethanedicarboxylic acid, β-hydroxyethoxybenzoic acid, p-oxybenzoic acid, adipic acid , Sebacic acid,
Aromatic, aliphatic and alicyclic bifunctional carboxylic acids such as 1,4-cyclohexanedicarboxylic acid can be mentioned. As the diol component other than the above glycol,
For example, cyclohexane-1,4-dimethanol, neopentyl glycol bisphenol A, bisphenol S
And aliphatic, alicyclic, and aromatic diol compounds, and polyoxyalkylene glycol. In the present invention, in the polyester fiber composed of the dicarboxylic acid component and the diol component, it is particularly preferable that 80 mol% or more of the repeating units are ethylene terephthalate units.

Further, a small amount of other optional polymers, antioxidants, antistatic agents, dye improvers, dyes, pigments, matting agents, fluorescent brighteners, inert fine particles and the like may be added to the polyester. An agent may be contained. In particular, when adding inert fine particles, any of the external precipitation method and the internal precipitation method can be adopted.

As a method for obtaining such a polyester cyclic oligomer, H. Repin, E. Papanikolau: Journal of
Polymer Science, A-1, 7, 3426 (1969), etc., or the Journal of Polymer Sci.
ence Part A: polymer Chemistry, Vol. 38, 3360-3368
(2000) and the like, a method of purifying from a powder adhering in the vicinity of a polyester molding apparatus.

The molecular weight of the polyester polymer fiber of the present invention can be controlled by the amount of the polymerization catalyst added. In the present invention, the polyester proceeds not by a polycondensation reaction but by ring-opening addition polymerization. Therefore, in the present invention, the polymerization catalyst functions not only as a catalyst but also as a polymerization initiator. Therefore, it is possible to control the number average molecular weight by controlling the amount of catalyst added. Further, in the ring-opening addition polymerization of the polyester of the present invention, it is important to control water and alcohol before the polymerization. Water and alcohol can be reaction initiators for the ring-opening addition polymerization. Therefore, the presence of water or alcohol needs to be removed in a pre-polymerization stage to reduce the degree of polymerization of the polyester. Conversely, the number-average molecular weight of the polyester can be controlled by adding a small amount of water or alcohol based on the molar ratio before the polymerization.

The polyester ring-opening addition polymerization of the present invention can use any catalyst. For example, antimony compounds include antimony trioxide, antimony pentoxide, antimony acetate, antimony glycooxide, and the like. Germanium compounds include germanium dioxide and germanium tetrachloride, and titanium compounds include tetra-n.
-Propyl titanate, tetraisopropyl titanate, tetra-n-butyl titanate, tetraisobutyl titanate, tetra-tert-butyl titanate, tetracyclohexyl titanate, tetraphenyl titanate, tetrabenzyl titanate, lithium titanate oxalate, potassium oxalate titanate, titanium oxalate Ammonium acid, titanium oxide, complex oxide of titanium with silicon, zirconium, alkali metal, alkaline earth metal, etc., orthoester or condensed orthoester of titanium, reaction of orthoester or condensed orthoester of titanium and hydroxycarboxylic acid Product, reaction product of titanium orthoester or condensed orthoester, hydroxycarboxylic acid and phosphorus compound, titanium orthoester or condensed ortho Examples of the reaction product include a steal and a polyhydric alcohol having at least two hydroxyl groups, a 2-hydroxycarboxylic acid, and a base. The tin compound includes dibutyltin oxide, methylphenyltin oxide, tetraethyltin, and hexaethyltin. Examples include ditin oxide, triethyltin hydroxide, monobutylhydroxytin oxide, triisobutyltin acetate, diphenyltin dilaurate, monobutyltin trichloride, dibutyltin sulfide, dibutylhydroxytin oxide, methylstannic acid, and ethylstannoic acid.

The fiber comprising the polyester polymer according to the present invention can be prepared by gel permeation chromatography (GP) using ethylene terephthalate as a main repeating unit.
The first feature is that the fiber is a polyester polymer consisting of a polyester substantially free of a branched structure and having a number average molecular weight of 25,000 or more in terms of polystyrene equivalent measured by C). That is, if the number average molecular weight is less than 25,000, a problem such as a decrease in the strength of the molded product occurs. Preferably 28000 or more,
More preferably, it is 29000 or more. In addition, the presence of the branch causes a problem such as a disorder of the extended cut chain due to the branch, or a decrease in the strength of the molded product due to a defect in the branch itself. Therefore, branching within a range where such a problem does not occur is not excluded from the present invention. In the present invention, the molecular weight distribution of the polyester depends on the state of dispersion of the polymerization catalyst in the polyester cyclic oligomer in the polymerization preparation stage.
If they are uniformly dispersed, the molecular weight distribution Mw / Mn will be close to 1,
If non-uniform, Mw / Mn becomes large and becomes a value larger than 2.

The second feature of the fiber comprising the polyester polymer of the present invention is that the half width of the crystal melting peak is 10 ° C. or less. It is presumed that the reason why the half width of the melting point peak is so small is that the molecular chain of the fiber made of the polyester polymer has an extended chain structure or a structure close thereto. This extended chain structure appears because the molecular chain is extended and the molecular chain is fixed by ring-opening addition polymerization. Therefore, the half width of the crystal melting peak is 1
When the temperature exceeds 0 ° C., the molecular chain does not have an extended chain structure, and it is difficult to achieve the object of the present invention.
The half width of the crystal melting peak is preferably 8 ° C or less, more preferably 5 to 6 ° C.

The fiber comprising the polyester polymer according to the present invention preferably has a cyclic trimer content of 0.8% by weight or less as determined by GPC. If the content exceeds 0.8% by weight, not only will impurities be formed, but also problems such as a decrease in the strength of the molded product will occur. Preferably it is 0.7% by weight or less, more preferably 0.5 to 0.6% by weight.

Further, the fiber comprising the polyester polymer according to the present invention preferably has a melting point of 260 ° C. or higher.
If the temperature is lower than 260 ° C., the melting point is lower than the melting point of the polyester, so that the heat resistance of the polymer fiber is lowered. Preferably it is 265 degreeC or more, More preferably, it is 268-290 degreeC.

The fiber comprising the polyester polymer according to the present invention preferably has a weight average molecular weight / number average molecular weight of 2 or more in terms of polystyrene equivalent molecular weight measured by GPC. If it is less than 2, a problem occurs in the flow characteristics during fiber molding. Preferably it is 2.5 or more, more preferably 3-7.

For such various polyesters,
It can be formed into fibers, films, etc. by any method. For example, after rolling, drawing, solid phase extrusion and the like can be mentioned. However, in any of the molding methods, the molding temperature is low and the molding time is preferably short, and more preferably the melting point of the polyester or less. It is also possible to deactivate the catalyst by a known method such as treating the polyester polymer of the present invention in boiling water or the like to suppress thermal degradation, molecular weight change, and molecular weight distribution change of the polymer. Furthermore, in the case of a molding method using a mold such as blow molding, injection molding, cast film molding, etc., ring-opening addition polymerization is performed in the mold by disposing a catalyst on the mold surface in advance. Can also be performed directly.

[0017]

EXAMPLES The present invention will now be described specifically with reference to examples, but the present invention is not limited to these examples. In addition, the evaluation method of various characteristics followed the following method.

DSC: 1 sample of polyester
0 mg was used. Using Perkin Elmer DSC-7,
The temperature was measured at a heating rate of 20 ° C./min up to 300 ° C.

Number average molecular weight, weight average molecular weight, weight average molecular weight / number average molecular weight, CT content: 10 mg of a sample was dissolved in 0.1 mL of hexafluoroisopropanol (HFIP), and then diluted with 2.5 mL of chloroform, and diluted with SHODEX GPC.
2 columns of KF-606M and KF-502.5 in SYSTEM 24H (chloroform solvent, reference: polystyrene)
At a temperature of 40 ° C and a flow rate of 0.5 ml / min.
V detected. The weight average molecular weight / number average molecular weight (Mw / Mn) was determined from the obtained number average molecular weight (Mn) and weight average molecular weight (Mw). The CT content was calculated from the area ratio between the CT peak and the whole.

Example 1 A polyester cyclic dimer was synthesized by a known synthesis method, and 100 mg of the cyclic dimer and tetrabutoxytitanate as a catalyst were sealed in an ampoule and heated at 190 ° C. for 500 minutes. Table 1 shows the physical properties of the obtained polymer. The DSC pattern is as shown in Fig. 1, GPC
The half width of the melting point peak was determined from the peak near 260 ° C. as shown in FIG. Next, the obtained polymer was spun at a nozzle temperature of 255 ° C. When the amount of cyclic trimmer contained in the filament was measured,
It was 0.91 wt%, and was a filament with very few impurities.

Example 2 The polymer obtained in Example 1 was used
Extrusion was performed at a die temperature of 255 ° C. When the amount of cyclic trimmer contained in the film was measured,
The content was 0.9 wt%, and a film with very few impurities could be obtained.

(Example 3) After the polymer obtained in Example 1 was preformed into a parison, the parison was blow-molded, molded into a bottle, and the amount of cyclic trimmer was measured. Yes, a bottle with very few impurities could be obtained.

Example 4 The polymer obtained in Example 1 was used
Injection molding was performed at a cylinder temperature of 255 ° C. When the amount of the cyclic trimmer contained in the injection molded product was measured, it was 0.93 wt%, and an injection molded product with very few impurities was obtained. (Comparative Example 1) A high-purity terephthalic acid and a 2-fold molar amount of ethylene glycol were charged into a heating medium circulating 2-liter stainless steel autoclave equipped with a stirrer, and 0.3 mol% of triethylamine was added to the acid component to give 0.25 MPa. Under pressure 245
The esterification reaction was carried out for 120 minutes while distilling water out of the system at ℃ to obtain a mixture of bis (2-hydroxyethyl) terephthalate (BHET) and oligomer with 95% esterification rate (hereinafter referred to as BHET mixture). Was. To this BHET mixture, a 2.5 g / l ethylene glycol solution of antimony trioxide was added so as to be 0.05 mol% as an antimony atom with respect to an acid component in the polyester. For 10 minutes. Then, over 50 minutes, the temperature of the reaction system was gradually lowered while the temperature was raised to 275 ° C. to 0.1 Torr, and the polycondensation reaction was further performed at 275 ° C. and 0.1 Torr. The time required for the PET IV to reach 0.65 was 39 minutes. In addition, IV obtained by the above polycondensation
A 0.65 dlg ^-1 polyethylene terephthalate was formed into chips in a conventional manner. Table 1 shows the physical properties of the obtained polymer. Next, the obtained polymer was spun at a nozzle temperature of 255 ° C. The amount of the cyclic trimmer contained in the filament was measured and found to be 2.1% by weight, which was inferior to that of the example having much impurities.

(Comparative Example 2) The polymer obtained in Comparative Example 1 was
Extrusion was performed at a die temperature of 255 ° C. When the amount of cyclic trimmer contained in the film was measured,
The content was 2.1 wt%, and the film was very rich in impurities.

Comparative Example 3 After preliminarily molding the polymer obtained in Comparative Example 1 into a parison, the parison was blow-molded, molded into a bottle, and the amount of the cyclic trimmer was measured. The bottle was very impure.

(Comparative Example 4) The polymer obtained in Comparative Example 1 was
Injection molding was performed at a cylinder temperature of 255 ° C. The amount of the cyclic trimmer contained in the injection molded product was measured and found to be 2.1 wt%, indicating that the injection molded product was very rich in impurities.

[0027]

[Table 1]

[0028]

According to the present invention, the molecular weight, molecular weight distribution and morphology, which are not found in conventional polyesters, are controlled, and a polyester polymer having a short chain structure with little entanglement of molecular chains is obtained. In addition, the molded product is very clean, with few impurities such as cyclic trimmers.

[Brief description of the drawings]

FIG. 1 is a DSC pattern of a polymer according to the present invention and a comparative polymer.

FIG. 2 shows GPC patterns of a polymer according to the present invention and a comparative polymer.

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Claims (8)

[Claims] 1. A polyester containing ethylene terephthalate as a main repeating unit and having a number average molecular weight of 25,000 or more in terms of polystyrene measured by gel permeation chromatography (GPC) and containing substantially no branched structure. A fiber comprising a polyester polymer, wherein the half width of the crystal melting peak is 10
A polyester molded article comprising a polymer having a cyclic trimer content of 0.8% by weight or less as determined by GPC at a temperature of not more than ° C. 2. The polyester molded article according to claim 1, wherein the melting point is 260 ° C. or higher. 3. The polyester molded article according to claim 1, wherein the weight average molecular weight / number average molecular weight is 2 or more in terms of polystyrene equivalent molecular weight measured by GPC. 4. The polyester molded article according to claim 1, wherein the molded article is a thread. 5. The polyester molded article according to claim 4, wherein the thread is a short fiber or a long fiber. 6. The polyester molded article according to claim 1, wherein the molded article is a film. 7. The polyester molded article according to claim 1, wherein the molded article is an injection molded article. 8. The polyester molded article according to claim 7, wherein the injection molded article is a blow molded article.