JPH0672179B2 - Method for producing polyester - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention relates to an improvement in a method for producing a polyester containing terephthalic acid and ethylene glycol as main raw materials. More specifically, the present invention relates to a method for producing a polyester which contains a large amount of fine particles and is excellent in moldability such as spinnability and film-forming property, slipperiness of a molded article, and surface property.

[Prior art and its problems] Saturated linear polyester, especially polyethylene terephthalate, has excellent mechanical properties, heat resistance, weather resistance, electrical insulation, and chemical resistance, so that it can be used in various fields such as clothing, industrial and other fields. Widely used in the form of films and other molded products.

When polyester is used in these forms, a fine particle-containing polyester composition is prepared from the final product value such as processability in molding process and post-processing process, opacity as clothing, and slippage of film products. Therefore, it is usually performed to facilitate the polymer flow at the time of molding, to make the molded product opaque, and to provide the surface of the molded product with appropriate irregularities so that the molded product has surface slipperiness. Then, as a method for allowing the fine particles to be present in the polyester composition, (1) titanium dioxide, silica, calcium carbonate, carion, etc. are added as they are or after pulverizing and classifying, at the time of polyester production or molding.

(2) A method of depositing fine particles as fine particles at the time of polyester production, using a metal compound residue used at the time of polyester production.

It has been known.

However, in the addition method of the above (1), the reproducibility of the results is good because the amount of fine particles can be controlled, but the formation of coarse particles and agglomerated particles is unavoidable, and operations such as pulverization and classification are not possible. Will be needed.

Further, in such a method, an inorganic compound is often used as particles, but the affinity with polyester is generally poor, and it is often dropped during processing or when it is used as a product, or contamination in the processing process or deterioration of product quality. Cause of.

On the other hand, the method (2) for depositing fine particles using the residue of the metal compound has a drawback that the amount of deposited particles and the particle diameter are likely to change due to subtle variations in the production conditions. It has the advantage that the affinity of the generated particles with polyester is improved, and that complicated operations such as classification and crushing are unnecessary, and if the occurrence of aggregated particles, coarse particles and the above-mentioned drawbacks can be overcome, its utility value Is big.

Taking advantage of the method of depositing fine particles by utilizing such a metal compound residue, efforts have been made to improve the drawbacks, for example, JP-A-49-13234, JP-B-52-32914,
Japanese Patent Publication 53-4103, Japanese Patent Publication 53-36877, Japanese Patent Publication 54-44040,
JP-A-50-144798 and JP-A-51-112860 disclose methods using a lithium compound and a phosphorus compound.

Usually, polyethylene terephthalate is produced in the first step of producing bis- (β-hydroxyethyl) terephthalate and / or its low polymer (hereinafter referred to as BHT), and the second step of polymerizing BHT under high temperature and reduced pressure.

However, BHT is industrially produced by a transesterification reaction from a lower alkyl ester of terephthalic acid and ethylene glycol or an esterification reaction from terephthalic acid and ethylene glycol, but generally the reaction rate is kept constant. Is difficult. Particularly in recent years, an esterification reaction method has been widely adopted in order to reduce the production cost of polyester.

However, according to the esterification reaction method, the above (2)
If a polyester containing precipitated particles based on the metal compound residue is produced, the particle amount and particle diameter of the precipitated particles fluctuate.

[Object of the Invention] As a result of intensive studies to solve the drawbacks of the method of depositing fine particles in polyester by utilizing the above-mentioned metal compound residue, the present inventors added a metal compound and a phosphorus compound by a specific method. If polycondensation is carried out in this way, even if the reaction rate of BHT and the concentration of end groups change when the catalyst metal compound is added,
The present inventors have found that the amount of particles and the particle size can be stabilized, and have reached the present invention.

That is, the object of the present invention is to esterify terephthalic acid and ethylene glycol, and then add a metal compound and a phosphorus compound for polycondensation to stably generate precipitated particles based on the metal compound residue in polyester. It is to provide a method for producing polyester.

[Constitution of the Invention] The above-mentioned object of the present invention is to carry out an esterification reaction of terephthalic acid and ethylene glycol, and then to carry out a polycondensation reaction to produce a polyester whose main structural unit is ethylene terephthalate. After adding an alkali metal compound to BHT or a low polymer thereof, which is substantially completed, phosphoric acid, phosphorous acid, phosphonic acid and two or more kinds of phosphorus selected from lower alkyl esters and phenyl esters thereof. This can be achieved by a method for producing a polyester, which comprises adding a compound and then adding an alkaline earth metal compound and then performing a polycondensation reaction.

BHT is produced by directly performing an esterification reaction from terephthalic acid and ethylene glycol under pressure or normal pressure.

The BHT referred to in the present invention includes, of course, a part thereof such as isophthalic acid, adipic acid, 2,6-naphthalene dicarboxylic acid, 5-
Acid components such as sodium sulfoisophthalic acid, tetramethylene glycol, neopentyl glycol, 1,4-
A glycol component such as cyclohexanedimethanol and polyalkylene glycol can be contained.

The reaction rate of BHT used in the present invention is preferably 92% or more, more preferably 94% or more, most preferably 96% or more. If the reaction rate is less than 92%, the particles produced are aggregated and coarsened, and the amount of particles becomes unstable, which is not preferable.

A feature of the present invention is that after the completion of the esterification reaction, the alkali metal compound is added, two or more phosphorus compounds are added, and then the alkaline earth metal compound is added.

When the order of addition is changed, the particle size and the amount of particles are changed due to the change of BHT reaction rate, and it is difficult to industrially obtain a polymer having stable quality.

As the phosphorus compound used in the present invention, two or more phosphorus compounds selected from phosphoric acid, phosphorous acid, phosphonic acid and lower alkyl esters and phenyl esters thereof can be used. And specifically, phosphoric acid, trimethyl phosphate, triethyl phosphate, triphenyl phosphate, phosphoric acid esters such as acid phosphoric acid methyl ester, phosphorous acid, trimethyl phosphite, phosphorous acid such as triethyl phosphite Mention may be made of esters, methylphosphonic acid, phenylphosphonic acid, benzylphosphonic acid, and phosphonic acid esters such as methylphosphonic acid methyl ester, phenylphosphonic acid ethyl ester, benzylphosphonic acid phenyl ester.

The total amount of the above-mentioned phosphorus compound added is preferably 2 to 30 mol, more preferably 3 to 25 mol, and most preferably 5 to 20 mol, per 10 ⁶ g of the obtained polyester.

When the amount of phosphorus compound added is less than 2 mol per 10 ⁶ g of the obtained polymer, the generation of coarse particles and agglomerated particles cannot be suppressed, and the amount of particles produced is stable against fluctuations in the BHT reaction rate. In addition to being unable to be polymerized, the heat resistance of the produced polyester is lowered and the resulting polymer is colored. Further, when the phosphorus compound addition amount is more than 30 mol, it is not possible to suppress the generation of coarse particles and agglomerated particles, further diethylene glycol by-product, because it reduces the physical properties of the resulting polyester such as a decrease in the softening point is preferable. Absent.

Examples of the alkali metal compound used include alkali metal hydrides, hydroxides, organic carboxylates, halides, glycolates and alcoholates, but it is necessary that the compounds are soluble in ethylene glycol.

Specific examples of the alkali metal compound include lithium acetate,
Examples thereof include sodium propionate, lithium chloride, lithium hydride, potassium hydroxide, and the like. Among them, lithium compounds such as lithium acetate and lithium hydroxide are particularly preferable, and two or more kinds can be used in combination.

The amount of the alkali metal compound added is preferably 1 to 100 mol, more preferably 5 to 50 mol, and most preferably 10 to 30 mol, per 10 ⁶ g of the obtained polyester.

When the amount of the alkali metal compound added is less than 1 mol per 10 ⁶ g of the obtained polymer, the amount of particles produced is insufficient, and BH
It is not preferable because the amount of particles produced varies with the variation of the T reaction rate, and coarse particles and aggregated particles are produced. If the amount of the alkali metal compound added is more than 100 mol, coarse particles and agglomerated particles are generated in the obtained polyester, and the color tone of the obtained polyester is deteriorated, which is not preferable.

Examples of the alkaline earth metal compound used in the present invention include organic carboxylic acid salts and glycolates of an alkaline earth metal compound soluble in ethylene glycol. Specific examples thereof include calcium acetate, barium propionate, strontium butyrate, calcium ethylene glycolate, and the like, and two or more kinds can be used in combination. As an alkaline earth metal compound,
Particularly preferred are calcium compounds such as calcium acetate and calcium ethylene glycolate.

The amount of the alkaline earth metal compound added is preferably 1 to 50 mol, more preferably 2 to 30 mol, and most preferably 3 to 20 mol, per 10 ⁶ g of the obtained polyester.

The amount of alkaline earth metal compound added is 10 ⁶ g of polymer
When the amount is less than 1 mol, the amount of particles produced is insufficient,
On the other hand, when the amount is more than 50 mols, the generation of coarse particles and agglomerated particles cannot be avoided, and the amount of particles generated varies with the variation of the BHT reaction rate, and a polyester of stable quality cannot be obtained.

As described above, the unique constitution of the present invention is that, after the alkali metal compound is added to the BHT after the esterification reaction, two or more phosphorus compounds are added, and then the alkaline earth metal compound is added. .

In this case, the addition interval of the alkali metal compound and the phosphorus compound and the addition interval of the phosphorus compound and the alkaline earth metal compound are each preferably 1 to 30 minutes, and more preferably 3 to 20 minutes. The addition interval of 1 to 30 minutes is preferable because uniform particles can be obtained and a decrease in the softening point of the polyester can be prevented.

After the alkali metal compound, the phosphorus compound and the alkaline earth metal compound are added in the above-mentioned predetermined order, immediately after preferably 1 to 20 minutes, the polycondensation reaction is carried out in the presence of a usual polycondensation reaction catalyst. Suitable polycondensation reaction catalysts include antimony trioxide, germanium dioxide and the like, but other catalysts such as tetraethyl titanate and antimony-glycolate can also be used.

[Advantages of the Invention] By adopting the above-described specific configuration, aggregated foreign matter and coarse particles are not generated even when the reaction rate of BHT obtained by the esterification reaction is changed, and the content amount of particles and the particle size are stable. Polyester can be produced. This polyester is useful for forming fibers and for forming films.

Hereinafter, the present invention will be described in detail with reference to Examples. Parts in Examples are parts by weight, and each property was measured according to the following measuring methods.

A. Polyester color tone A direct-reading color difference meter (Suga Test Instruments Co., Ltd.) was used to measure in chip form, and the value was shown as b value.

B. Intrinsic viscosity Measured at 25 ° C using 0-chlorophenol as a solvent.

C. Solution haze 2.7 g of polyester is dissolved in 20 ml of a mixed solvent of phenol / ethane tetrachloride (6/4 weight ratio), and the integrating sphere type HTR Meter SEP-H type haze meter manufactured by Nippon Seimitsu Optical Co., Ltd. is used to measure ASTM.
-Measure the solution haze according to D-1003-62 and use it as a guide for the amount of particles in the polyester.

D. State of Particles 10 mg of polyester chips are sandwiched between two cover glasses and melt pressed at 280 ° C. to prepare a preparation,
It was observed under a dark-field polarizing microscope and evaluated according to the following criteria.

Example 1 105.5 parts of BHT having an esterification reaction rate of 97.3% (ethylene glycol / terephthalic acid molar ratio of 1.2) composed of terephthalic acid and ethylene glycol was stored in a reactor at 240 ° C., and terephthalic acid was 86.5 parts at normal pressure. A slurry of 38.8 parts of ethylene glycol (molar ratio of 1.2) was continuously fed at a constant rate for 4 hours.

During the slurry supply, the reaction temperature was controlled at 230 to 245 ° C, and after the slurry supply was completed, the reaction temperature was controlled at 240 to 250 ° C to allow the esterification reaction rate to reach 98.1%.

105.5 parts of the produced BHT was transferred to a reactor for polymerization, and lithium acetate was charged to 0.
2 parts were added and after 5 minutes 0.2 parts trimethyl phosphate and 0.026 parts phosphorous acid were added.

After a further 10 minutes, 0.15 part of calcium acetate and 0.03 part of antimony trioxide were added. After 5 minutes, decompression and temperature increase were started, and the degree of vacuum was reduced to 1 mmHg or less in 60 minutes.
The temperature was raised to 88 ° C and polycondensation was performed for 2 hours and 30 minutes under the conditions to obtain polyethylene terephthalate having an intrinsic viscosity of 0.620.

Its quality is b value 4.0, softening point 261.0 ℃, solution haze 48%, and the size of particles in the polymer is about 1.5μ and uniform.
No aggregated particles of 0 μ or more and coarse particles were observed.

Example 2 An esterification reaction was carried out in the same manner as in Example 1 to obtain a reaction rate of 96.
Got a% BHT.

Polyethylene terephthalate obtained by adding a metal compound and a phosphorus compound to this BHT in the same manner as in Example 1 and polycondensing the product had a b value of 3.8, a softening point of 260.5 ° C. and a solution haze of 47%. The size of the particles inside was about 1.5μ, and no aggregated particles or coarse particles of 10μ or more were observed.

Comparative Example 1 In Example 1, except that BHT having a reaction rate of 96% was used and the addition order of the phosphorus compound and the calcium compound was changed,
Polycondensation was carried out in the same manner as in Example 1.

The quality of the obtained polyethylene terephthalate has ab value of 1.
5. The softening point was 260.0 ℃, the solution haze was 90%, and there were many agglomerated particles and coarse particles of 20-30μ in polyethylene terephthalate.

Comparative Examples 2 to 7 In exactly the same manner as in Example 2, BHT having a reaction rate of 96% was obtained.
The polycondensation reaction was carried out in the same manner as in Example 1 except that the alkali metal compound, the alkaline earth metal compound and the phosphorus compound added thereafter were added in the order shown in Table 1. The quality of the obtained polyethylene terephthalate is shown in Table 1.

In the addition order other than the present invention, there are many agglomerated particles and coarse particles.

Examples 3 and 4 Polyethylene terephthalate was obtained in the same manner as in Example 2 except that the reaction rates were changed to 92% and 94%. It can be seen that coarse aggregated particles are not observed in the order of addition according to the present invention.

Example 5 A polyethylene retephthalate was obtained in exactly the same manner as in Example 1 except that 0.14 parts of phosphoric acid and 0.026 part of phosphorous acid were added instead of 0.2 parts of trimethyl phosphate and 0.026 part of phosphorous acid. It was

Its quality is b value 4.2, softening point 261.1 ℃, solution haze 56%.
The size of the particles in the polymer was about 1.6 μm (rank B) and was uniform, and coarse particles of 10 μm or more were not observed (rank 1 grade).

Example 6 Instead of 0.2 parts of trimethyl phosphate and 0.026 parts of phosphorous acid in Example 1, phenylphosphonic acid ethyl ester was used.
Polyethylene terephthalate was obtained in the same manner as in Example 1 except that 0.29 part and 0.026 part of phosphorous acid were added.

Its quality is b value 5.2, softening point 260.9 ℃, solution haze 51%
The size of the particles in the polymer was about 0.8 μm (rank A) and uniform, and the level of coarse particles was second grade.

Comparative Example 8 Polyethylene terephthalate was obtained in the same manner as in Example 1 except that 0.23 part of trimethyl phosphate alone was added instead of 0.2 part of trimethyl phosphate and 0.026 part of phosphorous acid in Example 1.

The quality of the obtained polyethylene terephthalate has ab value of 1
1.3, softening point of 259.6 ° C., solution haze of 87%, coarse particles of 20 μ or more were present (rank 3 grade), and average diameter was 3.0 μ or more (rank C).

Comparative Example 9 Polyethylene terephthalate was obtained in exactly the same manner as in Example 1 except that 0.19 part of phosphorous acid alone was added instead of 0.2 part of tolumethyl phosphate and 0.026 part of phosphorous acid.

Its quality is as follows: b value 0.3, softening point 259.6 ° C, solution haze 98%
The average diameter of the particles in the polymer was 3.0 μm or more (rank C), and a large number of coarse particles of 20 μm or more were present (rank 3 grade).

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Claims (1)

[Claims] 1. A bis (ethylene glycol) bisulfate which has been subjected to an esterification reaction of terephthalic acid and ethylene glycol and then a polycondensation reaction to produce a polyester whose main constituent unit is ethylene terephthalate, and which has substantially completed the esterification reaction. After adding an alkali metal compound to-(β-hydroxyethyl) terephthalate and its low polymer, two or more phosphorus compounds selected from phosphoric acid, phosphorous acid, phosphonic acid and their lower alkyl esters and phenyl esters. A method for producing a polyester, which comprises adding a compound, and then adding an alkaline earth metal compound, and then performing a polycondensation reaction.