JP2818098B2 - Polyester production method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a polyester, and more particularly, to a method for producing a polyester having good moldability such as spinning and drawing, and in particular, having very little foreign matter deposited around a die hole during spinning.

[0002]

2. Description of the Related Art Polyesters, especially polyethylene terephthalate, have many excellent properties and are therefore widely used in various applications, especially in fibers and films .

[0003] Polyethylene terephthalate is usually prepared by an esterification reaction of terephthalic acid and ethylene glycol, a transesterification reaction of dialkyl terephthalate and ethylene glycol, or a reaction of terephthalic acid with ethylene oxide. Of ethylene glycol ester and / or a low polymer thereof, and then the product is heated under reduced pressure to undergo a polycondensation reaction until a predetermined degree of polymerization is reached.

[0004] The polyester thus obtained is
Generally, it is extruded into a fibrous or film form from a spinning nozzle or slit in a molten state, and then stretched for practical use.

[0005] In the above polycondensation reaction, by using an appropriate catalyst, the reaction proceeds smoothly, and a polyester having commercial value is obtained. That is, the quality of the reaction rate and the resulting polyester according to the type of catalyst used in the reaction is largely. Conventionally, as a polycondensation catalyst used in the production of polyethylene terephthalate, an antimony compound such as antimony trioxide has an excellent polycondensation reaction accelerating effect, and a polyester having a relatively good color tone can be obtained. , The most widely used. However, polyesters obtained using an antimony compound as a catalyst have a drawback in that they are inferior in moldability, especially in spinnability over a long period of time.

That is, when a polyester obtained by using an antimony compound as a polycondensation catalyst is melt-spun, after a lapse of time from the start of the spinning, a bending phenomenon (hereinafter referred to as bending) of the polymer flow occurs around the outside of the spinning hole. And
Lapping often occurs during spinning and drawing, and eventually spinning itself becomes impossible. For this reason, when bending occurs, the spinneret needs to be replaced, and production is significantly impaired.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing a polyester in which the occurrence of bending during melt spinning is substantially suppressed. Another object of the present invention is to provide a method for producing a polyester having excellent moldability such as spinnability and stretchability.

[0008]

Means for Solving the Problems The present inventors have conducted intensive studies on the bending which occurs during melt spinning of polyester. As a result, foreign matter which adheres and accumulates around the spinning hole after the start of spinning (hereinafter referred to as die foreign matter). There is a close relationship between the bending and the bending, and it has been found that bending can be prevented by suppressing the adhesion and accumulation of the foreign matter in the die.

Further analysis of the foreign matter in the die revealed that the main component was antimony used as a polycondensation catalyst and a thermally degraded polymer, and the antimony compound in the polymer sublimated during spinning and adhered to the periphery of the die hole. In addition, it was found that a degraded product generated by thermal decomposition of a polymer during spinning oozes out and deposits as foreign matter on a die.

Based on these findings, the present inventors have considered and considered that it is important to suppress the sublimation of antimony in polyester in order to suppress the accumulation of foreign matter in a die. As a result, it has been found that a polyester obtained by adding a specific amount of ammonium sulfonate during the polycondensation reaction in the production of polyester has very little foreign matter in a die, and has reached the present invention.

Thus, according to the present invention, a low molecular weight dicarboxylic acid diol ester comprising an aromatic dicarboxylic acid as a main dicarboxylic acid component and an alkylene glycol as a main glycol component is prepared by using an antimony catalyst and the following general formula (1):

[0012]

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(In the formula, A represents an organic group having no ester-forming functional group, and R ₁ , R ₂ , R ₃ and R ₄ each independently represent an alkyl group optionally substituted with a hydroxyl group or a cyano group. Which is a group, an aryl group or an aralkyl group, and n is a positive integer). Achieved.

Hereinafter, the present invention will be described in detail, but other objects, configurations and advantages of the present invention will become apparent.

The low molecular weight dicarboxylic acid diol ester of the present invention is mainly composed of an aromatic dicarboxylic acid component and an alkylene glycol component. The ester is usually a dimer to a dimer, preferably a trimer to a pentamer. Here, when there are N aromatic dicarboxylic acid components in one molecule, it is regarded as an N-mer.

The low molecular weight dicarboxylic acid diol ester is obtained by reacting an aromatic dicarboxylic acid or an ester-forming derivative thereof with an alkylene glycol.
Alternatively, it can be obtained by reacting an aromatic dicarboxylic acid with an alkylene oxide. These reactions are known per se, and appropriate reaction conditions can be selected according to the raw materials used to obtain a desired low-molecular-weight dicarboxylic acid diol ester.

Examples of the aromatic dicarboxylic acid include terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, diphenyldicarboxylic acid, diphenoxyethanediphenoxy and the like.

As the ester-forming derivative of an aromatic dicarboxylic acid, an alkyl ester of an aromatic dicarboxylic acid is generally used. Specific examples include dimethyl terephthalate, diethyl terephthalate, dimethyl isophthalate, and naphthalenedicarboxylic acid dimethyl ester.

Examples of the alkylene glycol include ethylene glycol, trimethylene glycol, and tetramethylene glycol. Examples of the alkylene oxide include ethylene oxide, trimethylene oxide, and tetramethylene oxide.

The low molecular weight dicarboxylic acid diol ester of the present invention can contain a dicarboxylic acid component other than the aromatic dicarboxylic acid component in an amount of 10 mol% or less, preferably 5 mol% or less based on all dicarboxylic acid components. Further, it may contain a diol component other than the alkylene glycol component, and the amount thereof is 10 mol% or less based on all diol components.
In particular, it is preferably at most 5 mol%.

Examples of dicarboxylic acids other than aromatic dicarboxylic acids include aliphatic and alicyclic bifunctional carboxylic acids such as adipic acid, sebacic acid and 1,4-cyclohexanedicarboxylic acid. As the diol other than the alkylene glycol, for example, cyclohexane-1,
Examples include alicyclic and aromatic diol compounds such as 4-dimethanol, neopentyl glycol, bisphenol A and bisphenol S, and polyoxyalkylene glycol.

Further, the low molecular weight dicarboxylic acid diol ester may be a 5-diol as long as the object of the present invention is not impaired.
An isophthalic acid component having a sulfonic acid salt such as sodium sulfoisophthalic acid, a polycarboxylic acid component such as trimellitic acid and pyromellitic acid, and a polyol component such as glycerin, trimethylolpropane and pentaerythritol can be contained.

In the present invention, the low molecular weight aromatic dicarboxylic acid diol ester described above is subjected to polycondensation by heating under reduced pressure and in the presence of a polymerization catalyst until a desired degree of polymerization is obtained, thereby obtaining a high molecular weight polyester.

The antimony catalyst as the polycondensation catalyst used in the present invention is known per se, and examples thereof include antimony trioxide, antimony pentoxide, antimony acetate, antimony glycolate and the like. The above may be used in combination.

In the polycondensation reaction, the ammonium sulfonate represented by the above formula (1) is present. In the formula (1), A is an organic group having no ester-forming functional group, and is exemplified by a phenyl group, an alkyl-substituted phenyl group, a naphthyl group, an alkyl-substituted naphthyl group, a diphenyl group, an alkyl-substituted diphenyl group, and the like. Aryl groups; linear alkyl groups having 3 to 50 carbon atoms; and alkyl groups having a branched side chain.

In the formula (1), R ₁ , R ₂ , R ₃ and R ₄ each independently represent a methyl group, an ethyl group, a propyl group, a butyl group,
An alkyl group which may be substituted with a hydroxyl group such as an octyl group, a lauryl group, a stearyl group, a hydroxyethyl group, and a cyanoethyl group or an aryl group such as a phenyl group, a tolyl group, and a xylyl group; and a benzyl group;
It is selected from an aralkyl group such as a cumyl group.

In the formula (1), n is a positive integer, and the organic group A
Is the same as the valence of Preferably, n ranges from 1-4.

Specific examples of the sulfonate anion of the ammonium sulfonate represented by the formula (1) include (substituted) phenylsulfonates such as phenylsulfonate, butylphenylsulfonate, octadecylphenylsulfonate and dibutylphenylsulfonate, naphthylsulfonate, diisopropyl Naphthyl sulfonate, dibutyl naphthyl sulfonate, naphthyl sulfonates such as naphthalenedi sulfonate, butyl sulfonate, octyl sulfonate, lauryl sulfonate,
Examples thereof include alkyl sulfonates such as hexadecyl sulfonate, and these may be a mixture.

On the other hand, specific examples of the ammonium cation of the ammonium sulfonate represented by the formula (1) include tetramethylammonium, tetraethylammonium, tetrabutylammonium, triethylmethylammonium, tributylmethylammonium, tributylethylammonium and trimethylbutylammonium. ,
Aliphatic ammonium such as trimethyloctyl ammonium, trimethyl lauryl ammonium, trimethyl stearyl ammonium, trimethyl octyl ammonium, tributyl octyl ammonium, triphenyl methyl ammonium, triphenyl ethyl ammonium,
Examples include ammonium containing an aromatic group such as triethylbenzylammonium and tributylbenzylammonium.

Furthermore, tri (3-hydroxypropyl) methylammonium, tri (2-cyanoethyl) methylammonium and tributyl (2-hydroxyethyl) ammonium can be mentioned.

The ammonium sulfonate of the formula (1) may be added at a stage before the completion of the polycondensation reaction. As a preferable method, a method of adding at the time when the reaction for synthesizing the low molecular weight dicarboxylic acid diol ester is completed is exemplified.

The ammonium sulfonic acid salt is preferably present in an amount of 0.005 to 0.5 mol%, more preferably 0.01 to 0.1 mol%, based on all carboxylic acid components during the polycondensation reaction. When the content is within this range, excellent results can be obtained in suppressing the formation of foreign matter in the die, and the polymerization reaction rate of polycondensation can be appropriately maintained.

The conditions such as pressure, temperature and time for the polycondensation may be appropriately selected from those known per se.

The polyester produced by the method of the present invention described above may optionally contain any additives such as an ether bond inhibitor, a stabilizer, a coloring inhibitor, a heat-resistant agent, a flame retardant, an antioxidant, Matting agents, coloring agents, inorganic fine particles and the like can be included.

[0035]

According to the production method of the present invention described in detail above, a polyester having good moldability such as spinning and drawing, and in particular, having little accumulation of foreign matter in a spinneret can be obtained. The reason has not been elucidated yet, but is presumed as follows.

That is, it is presumed that the antimony compound as the polycondensation reaction catalyst reacts with the ammonium sulfonate compound to suppress the sublimability thereof.

Therefore, the polyester produced by the method of the present invention can be molded stably under a wide range of molding conditions. For example, at the time of spinning, 500 to 250
Spinning at a speed of 0 m / min, stretching and heat treatment, 15
A method of spinning at a speed of 00 to 5000 m / min and simultaneously or successively performing the drawing and false twisting, a spinning speed of 5000 m / min or more, and depending on the application, a spinning condition such as a method of omitting a stretching step is employed. The yarn can be stably produced.

When forming into a film or sheet, a method of imparting anisotropy by applying tension only in one direction after film formation, a method of stretching in two directions simultaneously or in an arbitrary order, a method of forming two or more steps Arbitrary conditions such as a multi-stage stretching method can be employed without any trouble, and the industrial significance of the present invention is extremely large.

The method of the present invention can be preferably used when producing polyethylene terephthalate.

[0040]

The present invention will be described below in more detail with reference to examples.
In addition, the part in an Example represents a weight part, and each measured value followed the following method. (1) Intrinsic viscosity of polymer [IV]: It was determined from a value measured with an orthochlorophenol solution at 35 ° C. (2) Spinnability: using a spinneret having 30 spin holes having a diameter of 0.3 mm, a discharge rate of 80 g / min, and a winding speed of 1
The table shows the height of foreign matters around the outside of the spinning hole when spinning was performed at 200 m / min for 7 days, and the state of occurrence of bending during the spinning. (3) Stretchability: The undrawn yarn obtained in (2) is drawn at a drawing temperature of 85.
C., stretching ratio 3.5 times, stretching speed 1100 m / min, 150 denier / 30 filament 25 kg
The wrap rate when wound was shown.

Examples 1 to 8, Comparative Example 1 Transesterification of 100 parts of dimethyl terephthalate, 60 parts of ethylene glycol, and 0.031 part of manganese acetate tetrahydrate (0.025 mol% based on dimethyl terephthalate) The mixture was charged in a can, and subjected to a transesterification reaction while elevating the temperature from 140 ° C. to 220 ° C. over 3 hours in a nitrogen gas atmosphere while distilling out the generated methanol outside the system. Next, after adding 0.097 parts of trimethyl phosphate as a stabilizer and ammonium sulfonate described in Table 1, the temperature was elevated to remove excess ethylene glycol. After 10 minutes, 0.04 parts of antimony trioxide (0.027 mol% based on dimethyl terephthalate) was added as a polycondensation reaction catalyst. 24 internal temperature
When the temperature reached 0 ° C., the expulsion of ethylene glycol was terminated, and the reaction product was transferred to a polymerization vessel.

Then, the reaction was carried out at normal pressure for 30 minutes while increasing the temperature, and then the pressure was reduced from 760 mmHg to 1 mmHg over 1 hour, and the internal temperature was raised to 290 ° C. over 1 hour and 30 minutes. Under reduced pressure of 1 mmHg or less, polymerization temperature is 290 ° C
When the polymerization was further continued for 2 hours, the polymerization reaction was terminated by breaking the vacuum with nitrogen gas, and the polymer was discharged at 290 ° C. under nitrogen gas pressure. The evaluation results of the quality and the spinning property of the obtained polymer were as shown in Table 1.

[0043]

[Table 1]

In Table 1, the ammonium sulfonate A
-E are as follows.

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[0045]

According to the production method of the present invention, a polyester having good formability such as spinnability and stretchability, particularly having a small amount of foreign matter in a spinneret and substantially suppressing the occurrence of bending can be obtained.

Claims (2)

(57) [Claims] 1. A low-molecular-weight dicarboxylic acid diol ester containing an aromatic dicarboxylic acid as a main dicarboxylic acid component and an alkylene glycol as a main glycol component, is prepared by using an antimony catalyst and the following general formula (1). (In the formula, A represents an organic group having no ester-forming functional group, and R ₁ , R ₂ , R ₃ and R ₄ each independently represent an alkyl group or aryl which may be substituted with a hydroxyl group or a cyano group. A group or an aralkyl group, and n is a positive integer)
Wherein the polycondensation is carried out in the presence of an ammonium sulfonate represented by the formula: 2. The process for producing a polyester according to claim 1, wherein the ammonium sulfonic acid salt of the formula (1) is present in an amount of 0.005 to 0.5 mol% based on all carboxylic acid components.