JPH0718064A - Production of polyester resin - Google Patents

Abstract

PURPOSE:To obtain a resin which provide a biaxially oriented film excellent in slipperiness and transparency by adding a Ca compound and a P compound in a specific manner after completion of esterification or transesterification and conducting polycondensation to produce a poly(ethylene terephthalate) resin. CONSTITUTION:The process comprises (trans)esterifying an aromatic dicarboxylic acid or an ester-forming derivative thereof with a diol ingredient consisting mainly of ethylene glycol, adding a solution of 1 pt.wt. calcium compound in at least 32 pts.wt. ethylene glycol after completion of the reaction in such an amount that the calcium content in the polymer to be obtained will be 200-450ppm, adding successively or simultaneously a solution of a phosphorus compound in ethylene glycol in such an amount that the phosphorus amount is 0.6-1.5 times the calcium amount, and then conducting polycondensation to obtain the objective resin.

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 resin used for various packaging materials, and more specifically, a polyester useful for obtaining a biaxially stretched polyester film excellent in slipperiness and transparency. It relates to a method for producing a resin.

[0002]

2. Description of the Related Art Biaxially stretched polyester films represented by polyethylene terephthalate and the like have physical properties such as transparency, mechanical strength and dimensional stability, and chemical properties such as chemical resistance. Due to its excellent characteristics, it is widely used for magnetic tapes, capacitors, food packaging, etc. In particular, in magnetic tape applications, high slipperiness is required on the film surface in terms of running stability and wear resistance, and if sufficient slipperiness is not obtained, running troubles and wear reduce tape life. In addition, the surface is likely to be scratched, resulting in deterioration of quality.

Also, in general packaging applications such as food packaging, slipperiness above a certain level is indispensable in the manufacturing process and the processing process, and if it does not reach a certain level, wrinkles occur in the winding process. In addition to the defective winding shape, in some cases, the value as a product is significantly reduced.

From the above, the polyester film has excellent physical and chemical properties as described above, but has a high friction coefficient due to its resin property, and therefore has a slipperiness. It wasn't good enough.

Therefore, in order to improve the slipperiness of the polyester film, a method of roughening the surface of the film is generally performed. As a roughening method, an external particle method in which inorganic fine particles having a refractive index close to that of polyester are added during the polymerization step, and an internal particle method in which particles are precipitated in the polymer in the condensation process of polyester have been proposed.

The external particle method is a method in which inert inorganic compound particles are added to polyester such as calcium carbonate, titanium dioxide and calcium phosphate. In this method, the film surface is not broken or deformed by stretching. A sharp protrusion is formed on the surface to obtain high slipperiness. However, since the inorganic compound particles have a poor affinity with polyester, there is a problem that particles are likely to fall off due to the generation of voids in the particle peripheral portion during stretching, and a white powder is generated on the film surface. ing. Further, the inorganic compound particles also have an unfavorable property of significantly impairing the transparency of the film even when added in a small amount. Therefore, silica particles having a relatively good affinity with polyester are generally used. However, since silica particles have extremely poor dispersibility in polyester and easily aggregate during the production of polyester, and many coarse particles are generated on the film surface, the use of silica particles cannot prevent a decrease in transparency of the film. .

On the other hand, the internal particle method is an application of a catalyst residue or the like deposited during the production of polyester. But,
When the internal particle method is used, it is extremely difficult to control the amount of precipitated particles and particle size, and coarse particles are easily generated, which causes a rapid increase in filtration pressure in the film-forming process and induces product defects. Have the problem of. Furthermore, since the internal particles are easily broken by the deformation during stretching, running stability and wear resistance are poor, and recycling is also difficult.

[0008]

DISCLOSURE OF THE INVENTION The inventors of the present invention are concerned with a method for producing a polyester resin capable of obtaining a polyester film which produces a small amount of coarse particles and which simultaneously satisfies sufficient sliding characteristics and high transparency. As a result of earnest research, the present invention has been achieved. That is, the present invention produces a polyester resin by performing a polycondensation reaction after an esterification reaction or a transesterification reaction between an aromatic dicarboxylic acid or an ester-forming derivative thereof and a diol component containing ethylene glycol as a main component. In this case, after the esterification or transesterification reaction is substantially completed, a solution obtained by dissolving the calcium compound in ethylene glycol at a weight ratio of 32 times or more is added to obtain a polymer having a calcium element content of 200 or more. After adding an amount of about 450 ppm, an ethylene glycol solution of a phosphorus compound is added successively or simultaneously so as to add an amount of an element amount ratio of phosphorus element to calcium element of 0.6 to 1.5. There is a method for producing a polyester resin.

The polyester resin obtained by the production method of the present invention is a polyester resin obtained by using a difunctional aromatic dicarboxylic acid such as terephthalic acid or its ester and a diol component containing ethylene glycol as a main component as starting materials. . Preferably 80% of repeating units
The above is the polyester resin composed of ethylene terephthalate.

As the aromatic dicarboxylic acid used to obtain the polyester resin, terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, etc., and as the glycol component, other than ethylene glycol as the main component, Diethylene glycol, propylene glycol,
Examples thereof include butanediol, 1,4-cyclohexanedimethanol, triethylene glycol, neopentyl glycol, an ethylene oxide adduct of a bisphenol compound or its derivative, and the like. If necessary, other third component such as an aliphatic dicarboxylic acid such as glutaric acid, adipic acid, sebacic acid, oxalic acid or succinic acid may be used in combination.

One of the features of the manufacturing method of the present invention is that
After the esterification or transesterification reaction is substantially completed, an ethylene glycol solution of a calcium compound prepared to have a specific concentration, that is, a solution of the calcium compound dissolved in ethylene glycol at a weight ratio of 32 times or more is added. is there.

The calcium compound used in the present invention may be a compound generally used as an esterification catalyst, and specifically, it is an inorganic substance such as calcium hydroxide, oxide, carbonate or hydrogen carbonate. And organic substances such as acetate, propionate, butyrate, stearate and the like, and one or more of these may be used in combination. Of these, calcium acetate is preferably used from the viewpoints of solubility in ethylene glycol, influence on polymerization reaction, and cost.

The method of dissolving the calcium compound in ethylene glycol is not particularly limited. In the method of the present invention, it is preferable to use a solution in which the calcium compound is completely dissolved in ethylene glycol to be uniformly transparent. When the dissolution is not sufficient and the calcium compound is added to the esterified product in the aggregated state, coarse particles are likely to be generated in the obtained polymer, and product defects such as fish eyes are likely to occur on the film surface. This leads to an unfavorable situation such as an increase in the filter pressure. Therefore, the effect of the present invention cannot be sufficiently exerted.

The amount of ethylene glycol with respect to the calcium compound in the ethylene glycol solution of the calcium compound is 32 times or more, preferably 40 times or more, by weight ratio,
More preferably, it is 46 times or more. That is, it is necessary that the concentration of the calcium compound in the solution does not exceed 3% by weight, preferably 2% by weight. If the calcium compound concentration exceeds 3% by weight, if a calcium compound ethylene glycol solution is added to the system,
The calcium compound easily aggregates in the system, which easily causes the generation of coarse particles. For this reason, it is preferable that the calcium concentration in the solution is small, and the generation of coarse particles tends to be gradually suppressed as the concentration is lowered, but as the concentration is lowered, the amount of ethylene glycol added is necessarily increased. Therefore, the temperature in the system decreases after the addition, and when the decrease is large, the esterified product precipitates in the system, which adversely affects the subsequent polymerization reaction.
Therefore, the calcium concentration of the ethylene glycol solution to be added is preferably 1 to 2% by weight.

The second feature of the manufacturing method of the present invention is
The content of calcium element in the obtained polymer is 200
It is to add the ethylene glycol solution of the above-mentioned calcium compound so that it may become -450 ppm. In the production method of the present invention, the amount of calcium element contained in the polymer is an important factor. That is, the polyester resin obtained by the present invention has sufficient slipperiness and high transparency, and therefore the addition amount of the calcium compound is as important as the addition amount of the phosphorus compound described below. Have meaning. The added amount of the calcium compound, that is, the content of the calcium element has a great influence on the slipperiness, and the slipperiness of the obtained film gradually improves as the added amount of the calcium compound increases. However, excessive addition induces the formation of coarse particles by aggregating the calcium compound in the system, so it is preferable that the addition amount is within a range that provides the minimum slipperiness required for the film. The amount added is in the range of 200 to 450 ppm as the content of calcium element in the polymer. When the content of calcium element is less than 200 ppm, the slipperiness of the film is not sufficient, and when it exceeds 450 ppm, not only the slipperiness is excessive but also coarse particles are easily generated in the polymer, the process passability and the film It leads to unfavorable results on the surface morphology.

The third feature of the manufacturing method of the present invention is that
The calcium compound is added so that the calcium compound exists in the system before the phosphorus compound is added, that is, at the time when the phosphorus compound is added. Therefore, the phosphorus compound needs to be added after the time when the addition of the calcium compound is substantially completed, or simultaneously with the calcium compound. When the calcium compound was added after the phosphorus compound was added, the amount of internal particles that affect the slip property was extremely small, or even if they were generated, the particle size was extremely small, and the film was excellent. Although it has transparency, its slipperiness is low and sufficient practicality cannot be obtained.

Further, in the present invention, "successively" means that the calcium compound is added substantially no time after the addition of the calcium compound, and the phosphorus compound is added within 15 minutes after the addition of the calcium compound. It is more preferable to add the phosphorus compound within 5 minutes, and it is preferable to add the phosphorus compound continuously if the process allows. This is because it is preferable that the time from the addition of the calcium compound to the addition of the phosphorus compound is short, and as the addition interval becomes long, coarse particles are likely to be generated. The cause is unknown, but it is considered that after the calcium compound is added to the system, the dispersion state of the calcium compound in the system changes with the lapse of time, and the calcium compound is more likely to aggregate.

The phosphorus compound used in the present invention is
There is no particular limitation, and a generally used stabilizer can be used. Specifically, phosphoric acid, phosphorous acid, or esterified products thereof, for example, trimethyl phosphate, triethyl phosphate, triphenyl phosphate, trimethyl phosphite,
Examples thereof include triphenyl phosphite, and these compounds can be used alone or in combination of two or more.

It is necessary to determine the addition amount of the phosphorus compound based on the amount of elemental calcium. This is because the internal particles are formed through the reaction of phosphorus and calcium, so that it is not necessary to add a certain amount or more to the amount of calcium element, and an excess amount of phosphorus compound to calcium element is added. When added, the polymerization reaction of the polyester is suppressed and the polymerization time becomes long, which may cause unfavorable results such as coloring, and in some cases, a predetermined polymerization degree may not be obtained. . On the other hand, when the addition amount of the phosphorus compound is less than a certain amount, excess calcium that has not reacted with phosphorus induces thermal decomposition of the polymer, resulting in unfavorable results such as coloration and increase in acid value. Therefore, the addition amount of the phosphorus compound is in the range of 0.6 to 1.5 in terms of the element amount ratio of the phosphorus element to the calcium element. The phosphorus compound is added as a solution dissolved in ethylene glycol or the like.

The polyester resin obtained by the present invention is useful for obtaining a polyester film excellent in slipperiness and transparency. As a method for producing the polyester film, a known production method, for example, polyester resin at 270 to 300 ° C. is used. Melt-extruded at 40 ° C. to 80 ° C. and then solidified by cooling to obtain a substantially non-oriented sheet which is biaxially stretched longitudinally and transversely at 80 ° C. to 120 ° C. or longitudinally, and then stretched in a tenter. By a so-called sequential stretching, in which the film is stretched in the transverse direction in one or more stages, and after the transverse stretching is substantially completed, heat treatment is subsequently performed in a denter at 200 to 240 ° C. for crystallization. It can be obtained by a method of fixing orientation and increasing dimensional stability.

The thickness of the obtained polyester film is
Although not particularly limited, it is in the range of 6 to 380 μm.

[0022]

EXAMPLES The present invention will be specifically described below with reference to Examples and Comparative Examples. Evaluations in Examples and Comparative Examples were performed by the following methods.

1. Haze (%) The haze of the film was measured with a haze meter (MODEL TC-H III) manufactured by Tokyo Denshoku Co., Ltd.

2. Dynamic friction coefficient Using a surface tester manufactured by Shinto Kagaku Co., Ltd., the same film was attached to both fixed and movable parts to measure the dynamic friction coefficient.

3. Filter pressure 1000 for normal extruder for polyester film production
A filter having a diameter of 100 mm was attached using a mesh, and the system was operated at a discharge rate of 260 g / minute, and after 30 minutes, the elevated filtration pressure was measured and evaluated. ◯: Filtration pressure increase is less than 5 (kg / cm ² ) Δ: Filtration increase is 5 (kg / cm ² ) or more 10 (kg / c)
less than m ² ) ×; increase in filtration pressure 10 (kg / cm ² ) or more

Example 1 100 parts of terephthalic acid and 140 parts of ethylene glycol were charged into a reaction vessel equipped with a rectification column and a stirrer, the temperature was gradually raised to 260 ° C. with stirring, and the water flowing out was discharged from the system. While discharging, BHT (bis (β-hydroxyethyl) terephthalate) having a conversion rate of 93% was obtained by esterification. The obtained BHT was transferred to a polycondensation reactor, to which calcium acetate prepared separately was added. To the monohydrate, 25 parts of an ethylene glycol solution of calcium acetate containing 45 times the amount of ethylene glycol was added, and after the addition was substantially completed, a separately prepared 10% ethylene glycol solution of trimethyl phosphate was added. 3.5 parts was added and 10
After stirring for 1 minute while raising the temperature, 2 parts of a 2% ethylene glycol solution of antimony trioxide was added as a polymerization catalyst. Start depressurization 15 minutes later and set the vacuum to 1 mm in 30 minutes
After the temperature was reduced to Hg or less and the temperature was raised to 290 ° C., polycondensation was performed for 3 hours to obtain a polyethylene terephthalate chip having an intrinsic viscosity of 0.67. This chip at 120 ℃ 10
After vacuum drying for a period of time, the film was formed by an ordinary extruder used for polyester film to obtain a 150 μm original fabric. Further, it was stretched 3.5 times in the machine direction at 90 ° C. by a stretching machine connected to an extruder, and then transversely stretched 3.5 times at 90 ° C. in a tenter to obtain a film having a thickness of 12 μm. .
Table 1 shows the evaluation results of the obtained film.

Examples 2 to 4 In Example 1, the concentration of calcium acetate with respect to ethylene glycol, the addition amount of calcium acetate as a calcium element, and the element amount ratio of phosphorus element with respect to calcium element were changed as shown in Table 1. The method of Example 1 was repeated to obtain films each having a thickness of 12 μm.
The evaluation results of the obtained film are shown in Table 1.

Comparative Examples 1 to 8 In Example 1, the concentration of calcium acetate with respect to ethylene glycol, the amount of calcium element added, the timing of adding the phosphoric acid compound, and the element amount ratio of phosphorus element to calcium element were changed as shown in Table 1. Then, the method of Example 1 was repeated to produce a film having a thickness of 12 μm. Table 1 shows the evaluation results of the obtained film.

[0029]

[Table 1]

[0030]

As described above, the method for producing a polyester resin of the present invention, by adopting the production method having the above-mentioned constitution, produces less coarse particles and has sufficient slipperiness and high transparency. It is extremely useful for obtaining a polyester film having the same.

Claims (1)

[Claims] 1. A polyester resin is produced by subjecting an aromatic dicarboxylic acid or its ester-forming derivative to an esterification reaction or transesterification reaction between a diol component containing ethylene glycol as a main component, and then performing a polycondensation reaction. At this time, after the esterification or transesterification reaction is substantially completed, a solution obtained by dissolving the calcium compound in ethylene glycol at a weight ratio of 32 times or more is added to obtain a polymer having a calcium element content of 200 to 200%. 450p
After adding an amount of pm, a polyester compound is added successively or simultaneously with an ethylene glycol solution of a phosphorus compound in an amount such that the element amount ratio of phosphorus element to calcium element is 0.6 to 1.5. Resin manufacturing method.