JPH07238151A - Production of polyester - Google Patents

Abstract

PURPOSE:To produce a polyester markedly improved in the ability to disperse particles therein. CONSTITUTION:A process for producing a polyester mainly consisting of repeating ethylene terephthalate units by the direct polymerization process, comprises performing esterification provided that the viscosity of a bis (beta- hydroxyethyl) terephthalate and/or an oligomer comprising a low polymer thereof is 100mPa.s or below at a degree of esterification of 91% or above, adding 0.01-5wt.% fine particles of a mean particle diameter of 0.01-5mum, and conducting polycondensation.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing polyester. More particularly, this invention relates to a method of making polyesters with highly improved particle dispersibility.

[0002]

2. Description of the Related Art Polyester films represented by polyethylene terephthalate are widely used as graphic arts, displays, packaging materials and the like by taking advantage of their excellent physical and chemical properties. It is also widely used in fields such as base films and capacitor derivatives of magnetic recording media.

As an industrial method for producing polyethylene terephthalate, terephthalic acid and ethylene glycol are heated at atmospheric pressure or under pressure to directly form an esterified product from dicarboxylic acid, or dimethyl terephthalate and ethylene glycol are present in the presence of a catalyst. A method is known in which a polyester is obtained by subjecting it to a low-polymer esterification product by heating it under esterification to form a low-polymer esterification product and continuously subjecting it to a polycondensation reaction in the presence of a polymerization catalyst. As a recent industrial manufacturing method, a method of directly obtaining an esterified product, which is very economically advantageous, that is, a direct polymerization method is often carried out.

However, when it is attempted to produce a film that makes the best use of the characteristics of polyester, the coefficient of friction of the film is generally large and the process passability during film formation is poor, so the coefficient of friction is small and easy. There is a long-felt need to establish a process for making polyesters that gives films with excellent lubricity. Generally, as a method of improving the slipperiness of a polyester film, a method of mixing insoluble fine particles with polyester to form fine irregularities on the surface of the film is adopted. Alumina, calcium carbonate, silica,
The so-called addition method of adding fine particles such as kaolinite, talc, titanium dioxide and organic cross-linked polymer, and fine particles are produced by reacting either a carboxylic acid component, an oligomer or a P compound with a metal compound during the polyester production reaction. There is a so-called precipitation method of forming.

Of the above-mentioned two methods, the precipitation method is difficult to control the amount of particles, the particle size and the formation of coarse particles, and the fine particles are easily broken by stretching, so that the running property and wear resistance are poor. It is also difficult to recycle. On the other hand, the addition method is a useful method because the homogeneity of the product can be easily maintained by keeping the concentration and particle size of the fine particles to be added constant. However, since all the fine particles added by the addition method lack affinity for polyester, they often cause agglomeration during the polyester manufacturing process, resulting in product defects such as fish eyes.

A large amount of agglomerated particles such as fisheyes not only leads to product defects such as opacity, deterioration of optical characteristics such as change in glossiness, deterioration of electromagnetic conversion characteristics such as dropout, and also in the case of producing an ultrathin film. Is not preferable because it may cause membrane breakage and deteriorate the operation of the polymer such as deterioration of filter passing property. The formation of fish eyes and the like due to the aggregation of the fine particles tends to occur more easily when the polyester is produced by the direct polymerization method than when it is produced by the transesterification method, and particularly when the polyester is produced by the direct polymerization method. It becomes a big problem. The reason for this is not clear, but it is considered that the viscosity of the low polymer obtained during the esterification reaction by the direct polymerization method is usually higher than the viscosity of the low polymer obtained during the transesterification reaction by the transesterification method. . A dispersant is also used in combination to prevent aggregation of the added fine particles, but this is not always sufficient, and a method for directly producing a polyester having good particle dispersibility without aggregation of the added fine particles is used. Is eagerly awaited.

[0007]

[Means for Solving the Problems] As a result of intensive investigations, the inventors of the present invention have paid attention to the above circumstances and have established a method for producing a polyester having a highly improved particle dispersibility by a direct polymerization method. The present invention has been completed. That is, the gist of the present invention is that when a polyester whose main repeating unit is ethylene terephthalate is produced by a direct polymerization method, the esterification rate is 91% or more, and the viscosity of bis (β-hydroxyethyl) terephthalate and its low polymer is 1% or less.
A method for producing a polyester is characterized in that an esterification reaction is carried out at a pressure of 00 mPa · s or less, then 0.01 to 5% by weight of fine particles having an average particle diameter of 0.01 to 5 μm is added, and then a polycondensation reaction is carried out. .

The present invention will be described in more detail below. The polyester referred to in the present invention means terephthalic acid (hereinafter, TP
A) and ethylene glycol (hereinafter referred to as EG)
A polyester obtained by carrying out an esterification reaction and then a polycondensation reaction using as a main starting material, but may contain other third component. in this case,
Examples of the dicarboxylic acid component include isophthalic acid, 2,
One or more of 6-naphthalenedicarboxylic acid, adipic acid and sebacic acid can be used in combination. As the glycol component, one or more of diethylene glycol, propylene glycol, butanediol, 1,4-cyclohexanedimethanol, neopentyl glycol and the like can be used in combination. In any case, the polyester of the present invention refers to a polyester whose main repeating structural unit has an ethylene terephthalate unit.

In the present invention, the esterification rate is 91% or more and the viscosity of the oligomer comprising bis (β-hydroxyethyl) terephthalate and / or its low polymer is 100 mPa · s or less, preferably 50 mPa · s or less, The esterification reaction is preferably carried out so as to be 10 mPa · s or less. The viscosity of the oligomer referred to in the present invention means a B-type viscometer manufactured by Rion (Viscotester VT-03
It is the melt viscosity of the oligomer measured directly by the (type), and the measurement temperature is 250 ° C.

If the viscosity of the oligomer exceeds 100 mPa · s, the added fine particles are likely to aggregate, and fish eyes and the like are formed when the film is formed, which is not preferable in terms of product quality. The esterification reaction may be either a batch system or a continuous system. The esterification reaction may be carried out without a catalyst, or a catalyst such as a Ti or Sb compound may be used in combination so that the esterification reaction proceeds smoothly.

In order to control the esterification reaction so that the viscosity of the oligomer becomes 100 mPa · s or less when the esterification rate reaches 91% or more, for example, the following reaction conditions may be adopted. First, TPA and E
The G slurry has an EG / TPA molar ratio of 1.4-
It is preferable to adjust it so that it falls within the range of 2.2. When the molar ratio is less than 1.4, the polymerization degree of the oligomer becomes high, and the viscosity thereof often exceeds 100 mPa · s. On the other hand, when the molar ratio exceeds 2.2, the by-product of diethylene glycol (hereinafter referred to as DEG) tends to significantly increase. Particularly, the molar ratio of EG / TPA is more preferably in the range of 1.6 to 2.0. The slurry of TPA and EG is prepared by an appropriate kneading machine, and is continuously or intermittently supplied to the reaction system by a supply pump.

The temperature of the esterification reaction is 210 to 250.
C., especially in the range of 220 to 240.degree. C. is preferred. When the esterification reaction temperature is less than 210 ° C, the reaction time becomes long.
Further, when the esterification reaction temperature exceeds 250 ° C., the reaction proceeds remarkably, so that not only the oligomer has a high degree of polymerization and its viscosity becomes high, but also the side reactions such as an increase in the amount of DEG by-product and coloration increase. There is a fear.

In the present invention, if the fine particles added to the polyester are substances having an average particle size of 0.01 to 5 μm,
There is no particular limitation, and either inorganic fine particles or organic fine particles may be used. Specific examples of the fine particles that can be used include alumina, calcium carbonate, silica, kaolinite, talc, titanium dioxide, and organic crosslinked polymers.

These fine particles may be used alone,
You may use together 2 or more types. In particular, the method of using two or more kinds in combination is a useful method because the abrasion resistance of the film is improved. The average particle size referred to in the present invention means a centrifugal sedimentation type particle size distribution measuring device (SA-CP3 manufactured by Shimadzu Corporation).
Type) and the cumulative volume fraction in the equivalent spherical distribution 50
% Particle size (diameter). If the average particle diameter of the fine particles to be added is less than 0.01 μm, the improvement of slipperiness cannot be satisfied, which is not preferable. Further, if the average particle size exceeds 5 μm, when formed into a film, optical properties such as opacity and gloss reduction and electromagnetic conversion properties such as dropout are deteriorated, which is not preferable. The average particle size is preferably
0.01 to 2 μm, more preferably 0.03 to 1 μm
Is.

The amount of these fine particles added is 0.01 to 5% by weight, preferably 0.1 to 5% by weight, more preferably 1 to 5% by weight, based on the finally obtained polyester.
Is. If the amount of the fine particles added is less than 0.01% by weight, the slipperiness of the film cannot be improved, which is not preferable. On the other hand, if the amount of the fine particles added exceeds 5% by weight, opacity and a decrease in gloss will occur when a film is formed, which is not preferable.

The above-mentioned fine-particle ethylene glycol slurry to be added to the reaction system is highly dispersed by a high-speed stirrer, an ultrasonic disperser or the like in advance, and then a wet classifier such as a screw decanter or a filter such as a cartridge filter. It is preferable to remove coarse particles and foreign substances. The addition timing of the fine particle-containing slurry to the polyester production process is from the time when the esterification rate of the esterification reaction proceeds to 91% or more, preferably 95% or more, provided that the viscosity of the oligomer is 100 mPa · s or less. It can be arbitrarily selected during the initial stage of the polycondensation reaction.

It is not preferable to add the fine particle slurry at an esterification rate of less than 91% because the esterification reaction cannot proceed smoothly. Further, when the polycondensation reaction has progressed to some extent, it is difficult to obtain good particle dispersibility by adding the fine particle slurry because the viscosity of the oligomer exceeds 100 mPa · s. In addition,
The polycondensation reaction may be either batch-wise or continuous. The polycondensation catalyst can be appropriately selected and used from conventionally known catalysts.

[0018]

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist. Incidentally, the measuring methods of various physical properties and characteristics in Examples,
The definition is as follows. In addition, “part” in the examples and comparative examples means “part by weight”.

(1) Esterification Rate The amount of carboxyl groups (acid value) remaining in the esterification reaction product (oligomer) and the saponification value of the reaction product were determined and calculated by the following formula.

[Equation 1] Esterification rate (%) = (saponification value−acid value) × 1
00 / saponification value Here, the acid value is the value obtained by dissolving the reaction product in benzyl alcohol under N ₂ atmosphere and titrating with alkali, and the saponification value is the value obtained by alkaline hydrolysis of the reaction product and reversing with acid. It is the value obtained by titration.

(2) Viscosity of Oligomer The viscosity was measured using a single cylinder rotational viscometer (B type Viscotester VT-03) manufactured by Rion Co. Insert the rotor directly into the oligomer solution heated to 250 ℃, 62.5 rp
It measured at the rotation speed of m. Depending on the viscosity range of the oligomer,
The type of rotor was changed as follows. 2-33CP ... No.4 rotor (cylindrical part φ78 × 46m
m) 15-150 CP ... No. 5 rotor (cylindrical part φ61.2 ×
36 mm)

(3) Average particle size Centrifugal sedimentation type particle size distribution measuring device (SA-CP manufactured by Shimadzu Corporation)
Equivalent spherical distribution measured by type 3) 5
The particle size (diameter) of 0% was taken as the average particle size.

(4) Diethylene glycol (DEG) content 5 g of polymer was added to KOH methanol solution (concentration 4N) 50
In addition to ml, it was heated and hydrolyzed. This sample solution was analyzed by gas chromatography, and the DEG in the polymer was analyzed.
The content was quantified.

(5) Particle dispersibility in the film The state of dispersion of the particles added to the biaxially stretched film was observed with a microscope and judged according to the following criteria. ○: good dispersion, ×: poor dispersion, XX: extremely poor dispersion

(6) Slipperyness (F / Fμd) Two films cut into a width of 15 mm and a length of 150 mm are laminated on a smooth glass plate, a rubber plate is placed on the film, and a load is further applied to the film. Was placed, the contact pressure between the two films was set to 2 g / cm ² , and the films were slid at 20 mm / min to measure the frictional force. The coefficient of friction at the point of sliding by 5 mm was defined as the dynamic coefficient of friction (F / Fμd), and the judgment was made according to the following criteria.

[Formula 2] F / Fμd ≦ 0.50 ... ○ (good) 0.50 <F / Fμd ≦ 0.60 ... Δ (normal) 0.60 <F / Fμd ... × (poor) The measurement was performed at a temperature of 23. The test was conducted in an atmosphere of ± 1 ° C and a humidity of 50% ± 5%.

(7) Number of Coarse Protrusions Aluminum was vapor-deposited on the film surface, and the number was measured using a two-beam interference microscope. The measurement wavelength was 0.54 μm, and the number showing the interference fringes of the third order or higher was converted per 25 cm ² .

Example 1 [Production of polyester] Bis (β-hydroxyethyl)
In the presence of 100 parts of terephthalate oligomer, 87 parts of terephthalic acid and 65 parts of ethylene glycol (EG / TPA
The molar ratio = 2.0) was reacted at 220 ° C. under atmospheric pressure to carry out the esterification reaction. Five hours after the start of the reaction, a polyester oligomer having an esterification rate of 96% was obtained. When the viscosity of this oligomer was measured separately at 250 ° C, it was 8 mP.
It was as low as a.s. On the other hand, average particle size 0.03μ
20 parts of alumina and 80 parts of ethylene glycol were mixed and stirred, and 10 parts of the resulting slurry was added to 132 parts of the above polyester oligomer (corresponding to 100 parts of polyester). Ethyl acid phosphate (0.1 part) was added to the reaction system. 012 parts, 0.088 parts of magnesium acetate tetrahydrate and 0.04 parts of antimony trioxide are added,
While raising the temperature from 220 ° C. to 285 ° C. in 2 hours, the degree of vacuum was simultaneously reduced from 760 mmHg to 1 mmHg, and the polycondensation reaction was continued under the conditions of 285 ° C. and 1 mmHg for 4 hours and 30 minutes to obtain a polyester.

[Production of Polyester Film] After drying the obtained polyester, it is melt extruded at 290 ° C. to obtain an amorphous sheet, which is 3.5 times at 90 ° C. in the longitudinal direction and 3.7 at 110 ° C. in the lateral direction. The film was double-stretched and heat-treated at 210 ° C. for 3 seconds to obtain a film having a thickness of 15 μm. The obtained polyester was good in terms of the amount of DEG, the dispersibility of particles, the slipperiness of the film, the number of coarse projections, and the like. The obtained results are summarized in Table 1 below together with other examples and comparative examples.

Example 2 Polyesters and films were obtained in the same manner as in Example 1 except that the EG / TPA molar ratio in the esterification reaction was changed to 1.8 and the esterification reaction temperature was changed to 230 ° C. Example 3 A polyester and a film were obtained in the same manner as in Example 1 except that the EG / TPA molar ratio in the esterification reaction was changed to 1.6 and the esterification reaction temperature was changed to 240 ° C.

Example 4 Instead of alumina in Example 1, the average particle size was 0.42.
A polyester and a film were obtained in the same manner as in Example 1 except that calcium carbonate of μm was used. Example 5 Instead of alumina in Example 1, the average particle size is 0.10.
A polyester and a film were obtained in the same manner as in Example 1 except that silica having a thickness of μm was used.

Comparative Example 1 A polyester and a film were obtained in the same manner as in Example 1 except that the EG / TPA molar ratio in the esterification reaction was changed to 1.2 and the esterification reaction temperature was changed to 250 ° C. It was Comparative Example 2 A polyester and a film were obtained in the same manner as in Example 1 except that the EG / TPA molar ratio in the esterification reaction was changed to 1.1 and the esterification reaction temperature was changed to 260 ° C.

Comparative Example 3 A polyester and a film were obtained in the same manner as in Example 4, except that the EG / TPA molar ratio in the esterification reaction was changed to 1.1 and the esterification reaction temperature was changed to 260 ° C. It was Comparative Example 4 A polyester and a film were obtained in the same manner as in Example 5 except that the EG / TPA molar ratio in the esterification reaction was changed to 1.2 and the esterification reaction temperature was changed to 250 ° C.

Comparative Example 5 100 parts of dimethyl terephthalate, 65 parts of ethylene glycol and 0.086 part of magnesium acetate tetrahydrate were placed in a reactor, heated and heated, and methanol was distilled off to conduct an ester exchange reaction. It took 4 hours to raise the temperature to 230 ° C. to complete the substantial transesterification reaction. When the viscosity of this oligomer was separately measured at 250 ° C., it was 10 mPa · s. On the other hand, average particle size 0.0
After adding 10 parts of a slurry obtained by mixing 20 parts of 3 μm alumina and 80 parts of ethylene glycol to the reaction system, 0.012 parts of ethyl acid phosphate was added, and 0.033 parts of antimony trioxide was further added. Plus 2
While increasing the temperature from 30 ° C. to 285 ° C. in 1 hour and 40 minutes, the vacuum degree was simultaneously reduced from 760 mmHg to 1 mmHg, and the polycondensation reaction was continued for 4 hours at 285 ° C. and 1 mmHg to obtain a polyester.

As shown in Table 1, the particle dispersibility of Examples 1 to 5, which is a category of the present invention, was remarkably improved as compared with Comparative Examples 1 to 4 under the conventional esterification reaction conditions. The properties of polyester, ie the amount of DEG,
The film has good slipperiness and a large number of protrusions. The quality of the polyester produced by the direct polymerization method is comparable to that of the transesterification method shown in Comparative Example 5, and the production method is industrially very useful.

[0034]

[Table 1]

[0035]

EFFECTS OF THE INVENTION According to the present invention, the improvement of particle dispersibility is extremely excellent, and the characteristics when formed into a film can be sufficiently satisfied, and it can be applied to various uses, and its industrial value is high.

Claims (1)

[Claims] 1. When a polyester having ethylene terephthalate as a main repeating unit is produced by a direct polymerization method, an esterification rate of 91% or more and an oligomer of bis (β-hydroxyethyl) terephthalate and / or a low polymer thereof are used. The esterification reaction is carried out with a viscosity of 100 mPa · s or less, and then an average particle size of 0.01 to 5 μm.
A method for producing a polyester, wherein the polycondensation reaction is carried out after adding 0.01 to 5% by weight of the fine particles of m.