JPH06104718B2 - Method for producing polyester - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a method for producing a polyester,
More specifically, the present invention relates to a method for producing a transparent polyester for a film suitable for an electrostatically applied casting method by a direct polymerization method.

[Prior Art] Since polyethylene terephthalate is excellent in physical and chemical properties, it is widely used not only as fibers but also as packaging films, photographic films, condenser films, magnetic tape and other films.

Known methods for producing polyethylene terephthalate include a transesterification method using dimethyl terephthalate and ethylene glycol as starting materials, and a direct polymerization method using terephthalic acid and ethylene glycol as starting materials.

Conventionally, a polyester film produced by a transesterification method has been used as a polyester film, but in recent years, a polyester produced by a direct polymerization method has also been used.

The polyester film is usually one obtained by melt-extruding polyester into a sheet form by an extruder and then biaxially stretched in the longitudinal and transverse directions.However, in order to improve the thickness and transparency of the film, the extrusion die and the rotation cooling drum are combined. A method is used in which an electrode is provided between the electrodes to apply a high voltage to give an electrostatic charge to the upper surface of the uncured film to bring the film into close contact with the surface of the cooling drum.

However, in such a method, when the film formation speed is increased, the electrostatic charge per unit area is reduced on the film surface adhered to the cooling drum surface, the adhesion between the film and the cooling drum surface is reduced, and the film thickness is not uniform. It becomes uniform and pin-shaped defects occur on the surface. If the applied voltage is increased to increase the amount of electrostatic charge to avoid this, electric discharge may occur between the electrode and the surface of the cooling drum, and the film may be destroyed.

In order to solve such a problem, these problems are solved by adding a metal compound having electrical conductivity to polyester to lower the specific resistance of the polyester, and a polyester film excellent in thickness uniformity is produced at high speed. It is described in JP-A-51-70269 that the polyester contains an alkali metal or an alkaline earth metal in order to form a film, and it is also preferable to add a compound of cobalt and manganese and / or magnesium to the polyester. 51-67392
It is described in Japanese Patent Publication No.

Further, in the direct polymerization method, a technique of adding a metal compound and a phosphorus compound in order to impart electrical conductivity to polyester is proposed in Japanese Patent Publication No. 56-15730, but in this case, the metal compound The phosphorus compound reacts with the phosphorus compound to produce phosphorus compound particles of an undesired metal, so that turbidity is likely to occur and the filterability is likely to deteriorate. Further, in the case where it has sufficient electric conductivity to impart the castability by applying static electricity, there is a difficulty in transparency, and it is not yet satisfactory.

Conventionally, when a polyester is applied to a photographic support, polyethylene terephthalate, which is a polyester which is advantageous in its physical and chemical properties, is usually used.
Of the various characteristics required as a support for photographic film,
Recently, especially, it has high transparency and has no defects on the surface,
In addition, there is an increasing demand for polyester films that do not have a yellow or black tint. For example, for X-ray photography, when determining a photographed image, the transparency of the film is high, so that it is possible to identify a more delicate shadow and find the affected area. Also, from an ergonomic point of view, it is colored blue in order to ease eye fatigue and make it easier to judge, but normally the coloring is set on the polyester film that is the film support, A clear blue color without yellow or red is required. Furthermore, for print photography, the film taken is layered and taken as the original plate,
Due to the characteristic that minute defects are emphasized in black and white, it is becoming more and more demanded that the polyester film as a support has no transparency or surface defects.

The polyester obtained by the conventional technique described above,
Especially when it is applied to photography, the inventors of the present invention have found that the transparency and the color tone are not in a situation where the above requirements are sufficiently satisfied, and the productivity and the transparency of the film are improved. We have determined that improved polyesters need to be developed.

To the inventors' knowledge, the transparency and color tone of the polyester film are affected by the conditions when the polyester is extruded and formed into a film by a biaxially stretched film forming apparatus. Haze) and color tone (L value and b value measured by a color difference meter) are greatly correlated, and when applied to a photographic film, it is clear that transparency and color tone are greatly affected. Generally, in a photographic film, the lower the value of the solution haze of polyester, the higher the transparency of the unexposed area after development, which is preferable. Further, the higher the L value of the color tone of the polyester, the weaker the darkening of the unexposed area after development is, and the closer the b value is to 0, the less yellowish or bluish tint, and a photographic film having a preferable color tone is obtained. can get.

[Problems to be Solved by the Invention] The inventors of the present invention have shown that there is no increase in filtration pressure and turbidity due to metal phosphorus compound particles, and there is no coloring and is a transparent polyester for transparent films. As a result of intensive studies on a method for producing the above-mentioned by a direct polymerization method, a means for solving the above problems was found.

[Means for Solving Problems] That is, in the method of the present invention, when a polyester is produced from a dicarboxylic acid and a glycol, 0.03 × 10 ^{−3 to} 2.0 × 10 ⁻³ mol per mol of the dicarboxylic acid is used. A slurry of a dicarboxylic acid containing a phosphorus compound corresponding to a phosphorus atom and a glycol is continuously or intermittently supplied to bis (β-hydroxylethyl) terephthalate (hereinafter abbreviated as BHET) and / or its low polymer. Then, the esterification reaction is carried out to substantially end the esterification reaction, and then 0.08 × 10 ^{−3 to} 2.0 × 10 ⁻³ mol of a divalent metal compound corresponding to 1 mol of the dicarboxylic acid is added. It is characterized in that it is added and then the polycondensation reaction is carried out in the presence of a catalyst.

BHET and / or its low polymer applicable to the present invention may be produced without containing a phosphorus compound or may be produced from a slurry of a dicarboxylic acid containing the phosphorus compound of the present invention and a glycol. .

Preferred as the polyester obtained by the present invention is polyethylene terephthalate. That is, 80% or more, preferably 90% or more of the constitutional units are composed of ethylene terephthalate units obtained from terephthalic acid and ethylene glycol as starting materials, and contain other copolymerization components in a range of less than 20%. You may stay.

As the copolymerization component, aromatic dicarboxylic acid such as isophthalic acid; aliphatic dicarboxylic acid such as cyclohexanedicarboxylic acid; alicyclic carboxylic acid such as adipic acid and sebacic acid;
Diethylene glycol, propylene glycol, 1,4-
Examples thereof include glycols such as butanediol and cyclohexane-1,4-dimethanol.

The most preferred polyester for the present invention is polyethylene terephthalate. Hereinafter, the dicarboxylic acid will be described as terephthalic acid (hereinafter abbreviated as TPA), and the glycols will be described as ethylene glycol (hereinafter abbreviated as EG).

The slurry applied to the present invention is a phosphorus compound, EG and TPA.
And TPA to EG ratio (molar ratio) is usually 1: 1.05 to 1.50, preferably 1: 1.05 to 1.25.

Examples of the phosphorus compound applied to the present invention include phosphoric acid, phosphorous acid and their monoesters, diesters, triesters, and phosphonic acid, phosphonic acid esters, and the like, but phosphoric acid, phosphorous acid, trimethyl phosphate And triethyl phosphate and the like are preferable. These phosphorus compounds may be used alone or in combination of two or more kinds.

The phosphorus compound is preferably added to TPA or EG to form a uniform slurry, or added to a mixture of TPA and EG to be used as a uniform slurry.

Further, the phosphorus compound is made into a slurry in a state of being contained in EG and TPA in advance, and premixed with EG and TPA in order to obtain the same effect as when continuously added to BHET and / or its low polymer. Alternatively, it may be dissolved in ethylene glycol and added to BHET and / or its low polymer. Further, a small amount of phosphorus compound is added to BHET and / or its low polymer in advance, and then a slurry containing a phosphorus compound is added as described above, or a slurry of EG and TPA containing no phosphorus compound and ethylene glycol. It is also possible to add a solution of a phosphorus compound dissolved in.

The amount of phosphorus compound added is 0.03 per mol of dicarboxylic acid.
The range corresponding to x10 ^{-3 to} 2.0 x 10 ^-3 mol of phosphorus atoms is good, and the amount is preferably 0.1 x 10 ^{-3 to} 0 and 6 x 10 ^-3 mol of phosphorus atoms. If the amount exceeds 2.0 to 10 ^-3 mol, it is not preferable because it causes some reaction with the metal compound added after the esterification reaction is substantially completed to produce metal phosphorus compound particles. On the other hand, if it is less than 0.03 × 10 ⁻³ mol, the heat resistance of the produced polyester tends to deteriorate and the polyester tends to be colored, which is not preferable.

The esterification reaction is carried out by continuously or intermittently adding the slurry to BHET and / or its low polymer, but when polycondensation is carried out batchwise, the amount of BHET and / or its low polymer is esterified. When the total weight after the reaction is 100 parts, it is usually 20 parts to 50 parts, preferably 30 parts to 50 parts. In this case, the esterification reaction temperature is usually 230 ° C. or higher at normal pressure, preferably 240 to 260 ° C. Although the reaction time varies depending on the temperature difference, it is usually about 4 hours when the above numerical value of BHET is 50 parts and the reaction temperature is 250 ° C. under normal pressure, and when the above numerical value is 33 parts, it is about 6 hours.

In the case of applying pressure, the pressure condition is 0.3 to 3.0 kg / cm ² , preferably 1.0 to 2.0 kg / cm ² , and the esterification rate in continuous esterification is applied up to about 85%. At this time, the esterification reaction temperature is usually 240 ℃ ~ 280 ℃, 250 ℃
It is preferably ˜270 ° C. and can be selected regardless of the pressure of the esterification reaction. The reaction time for esterification depends on the pressure and temperature.For example, in the case of continuous esterification, the reaction temperature 27
Esterification rate of about 80% at reaction time of about 1 hour and 30 minutes under pressure condition of 0 ℃ and 1.5 kg / cm ² (pressure 2.5 kg / cm ² ), then reaction temperature of 260 ℃, reaction time and normal time The esterification reaction is completed in about 1 hour and 30 minutes. Therefore, in the case of continuous esterification, the esterification reaction is carried out at a temperature of 260 ° C. to 270 ° C. and a pressure of atmospheric pressure to 2.5 kg / cm ² for a reaction time of about 3 hours.

After the esterification is substantially completed, a divalent metal compound is added, and then a polycondensation reaction is carried out. Here, "substantially completed esterification" means a state in which, in the presence of a polycondensation catalyst, a polycondensate having a high molecular weight can be reliably obtained by a usual method, usually BHET and / or its low polymer. The rate of conversion to (hereinafter referred to as esterification reaction product), that is, the esterification rate is 90% to 98%, preferably 95% to 98%.

The esterification rate can be determined by the following formula by measuring the saponification value and acid value of the sample by a usual analytical method.

Generally, the esterification rate varies depending on the esterification reaction conditions such as the molar ratio of EG and TPA, the temperature, pressure and time of esterification. In order to set the esterification reaction conditions to obtain a desired esterification rate, the final esterification reaction conditions are obtained by adjusting the esterification reaction conditions and confirming the esterification rate of the sample at that time.

In the method of the present invention, TPA and EG usually added with a phosphorus compound
The esterification reaction is carried out while supplying the slurry of and under normal pressure or under pressure. Then, after the supply is completed, the esterification reaction proceeds under normal pressure, and the esterification rate is 90% to 98%.
%, Preferably 95% to 98%, and sent to the polycondensation step.

The divalent metal compound used in the present invention is preferably a glycol-soluble compound such as zinc, magnesium, manganese, calcium, barium or cobalt.

For example, zinc acetate, zinc oxalate, zinc benzoate, zinc chloride, zinc carbonate, magnesium acetate, magnesium oxalate, magnesium benzoate, magnesium carbonate, magnesium chloride, magnesium hydroxide, manganese acetate, manganese oxalate, manganese benzoate, Manganese chloride, calcium acetate, calcium oxalate, calcium benzoate, calcium chloride, cobalt acetate, cobalt chloride, cobalt benzoate, cobalt acetylacetonate, barium acetate, barium oxalate, barium benzoate, barium chloride, barium hydroxide, etc. Is used, but magnesium acetate, manganese acetate, zinc acetate, and calcium acetate are particularly preferable. These divalent metal compounds may be used alone or in combination of two or more kinds. It is generally preferred to use these divalent metal compounds in the form of hydrates.

It is essential that the divalent metal compound be added after the esterification reaction is substantially completed and before the polycondensation reaction is started.

When a metal compound is added when the esterification rate is less than 90%, insoluble fine particles such as terephthalic acid metal salt are generated due to the reaction between the carboxy terminal and the metal compound, and foreign substances are easily generated. Further, when added after the start of the polycondensation reaction, the dispersion in the polyester is not sufficient and insoluble particles are generated, which causes turbidity and an increase in filtration pressure.

The amount of the divalent metal compound added is an amount corresponding to 0.08 × 10 ^{−3 to} 2.0 × 10 ⁻³ mol of metal atoms, preferably 0.15 × 10 ^{−3 to} 1.2 × 10 1 mol of dicarboxylic acid. ^-Amount corresponding to ³ moles of metal atoms. If it is less than 0.08 × 10 ^-3 mol, the castability due to static electricity applied during film formation will be poor.
If it exceeds 2.0 × 10 ^-3 mol, insoluble particles and by-products generated by some reaction with the metal will be generated.

The polycondensation of the esterification reaction product may be carried out by a conventional method in either a batch system or a continuous system, and may be carried out using a polycondensation catalyst such as antimony trioxide or germanium dioxide.

When the esterification reaction product is polycondensed by a batch method, it generally requires 30 to 60 minutes at a temperature of 260 ° C to 280 ° C, and a precondensation reaction from atmospheric pressure to 10 mmHg / cm ² is performed. Through, 280 ℃
Polycondensation is normally carried out for 3 to 6 hours at 290 ° C. and a pressure of 0.1 to 0.5 mmHg / cm ² to produce a polyester having an intrinsic viscosity of 0.6 to 0.7. When the esterification reaction product is polycondensed by a continuous method, it is generally 270 ° C to 280 ° C and 10 to 100 mmHg / cm.
^At a pressure of ² , through a pre-condensation reaction by a pre-condenser with a residence time of 30-45 minutes, at a temperature of 280 ℃ ~ 290 ℃ 0.1 ~ 0.5 mmHg
Polycondensation is carried out with a polymerization finisher at a pressure of / cm ² for a residence time of 60 to 75 minutes to produce a polyester having an intrinsic viscosity of 0.6 to 0.7. The polycondensation of the esterification reaction product takes 3 to 6 hours in the case of the batch method, whereas it is performed in a short time of 1.5 to 2 hours in the case of the continuous method.

In the present invention, various additives such as a lubricant containing a metal oxide such as silicon dioxide, aluminum trioxide, magnesium dioxide, calcium carbonate as a main component, a matting agent such as titanium dioxide, a pigment, etc. may be used according to the application. You can

(Effect) According to the method for producing a polyester of the present invention, in order to carry out the esterification reaction of a glycol represented by ethylene glycol and a dicarboxylic acid represented by terephthalic acid in the presence of a phosphorus compound, the phosphorus compound is added to BHET. The reaction is surely carried out, and a predetermined amount of phosphorus can be stably and uniformly contained in the obtained polyester. When a phosphorus compound is added before the start of polycondensation as in the prior art, the phosphorus content of the obtained polyester tends to vary, which is a problem in quality control of the polyester. This is considered to be due to difficulty in controlling the reaction rate with BHET when a phosphorus compound is added at the start of polycondensation. It is common knowledge in the art that the phosphorus content has a great influence on the quality of polyester.

Further, according to the method for producing a polyester of the present invention, phosphorus is already contained after the esterification reaction is completed.
A bivalent metal compound is added to BHET and a polyester is produced by a polycondensation method in the presence of an ordinary polycondensation catalyst.However, the reaction between the divalent metal compound and BHET is very mild, and the polyester is produced. It is possible to efficiently secure the various functions required when forming a film. According to the conventional method, BH
After adding the metal compound to the ET, the phosphorus compound is added about 10 minutes later, and the reaction between the two acts radically, resulting in the generation of particles of the undesirable metal compound, which is why polyester is not produced. Obstacles to the membrane are seen.

Furthermore, according to the production method of the present invention, not only the conventional esterification under normal pressure but also the esterification under pressure can be performed, whereby the reaction time of esterification can be significantly shortened, and the productivity can be improved. Not only can this contribute to the rationalization of equipment with the improvement of the above, but the original effect of the present invention can be sufficiently obtained. In the method for producing a polyester from a glycol represented by ethylene glycol and a dicarboxylic acid represented by terephthalic acid, in which esterification and polycondensation are continuously performed, a so-called direct continuous polymerization method of polyester, the effect of the present invention is particularly high. To be demonstrated. In particular, if the esterification rate in the esterification reaction in this case is up to about 85% under pressure, the reaction time can be greatly shortened.

Polyester is generally produced through a reaction at a relatively high temperature and for a relatively long time among polymer compounds, so it is considered that the polyester is produced while deteriorating the quality. This is an essential issue in improving the quality of polyester. In addition, our experience is that the contribution to the quality improvement of polyester by shortening the time required for esterification and polycondensation is almost the same.

As already explained, if the polycondensation reaction of the esterification reaction product is carried out by a continuous method, the polycondensation reaction time can be greatly shortened.Therefore, by the so-called direct continuous polymerization method of polyester from EG and TPA, This task can be achieved advantageously. Therefore, based on the direct continuous polymerization method of the polyester, by carrying out the method for producing a polyester of the present invention, in terms of the usual quality of the polyester, not only a higher level can be achieved, but also in the prior art for a film. The technical level of polyester that could not be achieved, especially transparency, color tone and processability can be obtained.

Furthermore, according to the method for producing a polyester of the present invention, the addition amount of a metal compound sufficient to impart the same electrostatically applied castability is small as compared with the conventional method, and thus a polyester having excellent transparency can be obtained. You can In addition, according to the method for producing a polyester of the present invention, essentially any metal compound can be used as long as it is a divalent metal compound for imparting the electrostatically applied castability, so that the degree of freedom in selection is high. It has the advantage of being large. Therefore, particularly when applied to a photographic support, it is easy to stably obtain a film in which surface defects due to coarse particles are less likely to occur and coloring due to a metal compound is less likely to occur.

As described above, the polyester obtained by the method of the present invention is stable in quality, and particularly excellent in transparency and color tone, and it is possible to produce a film for a long period of time because the filtration pressure rise during film formation is small. In addition, since it is excellent in electrostatically applied castability, it can be operated at a high speed, and therefore a high quality film can be produced with good productivity.

A polyester film having excellent transparency, a uniform film thickness without surface defects, and a good color tone, which is produced from the polyester obtained by the polyester production method of the present invention, is used as a photographic support, especially for X-ray photography. When applied to a film, a polyester film produced from a polyester obtained by a conventional method has a yellowish tint, and its transparency is unsatisfactory, and it is difficult to obtain a clear blue coloring. Since it has a small taste and is transparent, it is possible to obtain a clear blue-colored super-transparent high-quality photographic film for X-ray. Further, when applied to a photographic film for printing, while the polyester film produced from the polyester obtained by the conventional method was unsatisfactory in terms of transparency and the occurrence of surface defects, the polyester production method of the present invention By applying the obtained polyester, it is possible to obtain a highly transparent polyester film having no surface defects with high productivity. Of course, the polyester obtained in the present invention can be used for applications other than the film, and other additives, lubricants, matting agents, dyes, and pigments can also be used as necessary to impart performance.

(Examples) The present invention will be described in detail below with reference to examples. The measuring methods of the respective characteristic values in the examples are as follows. The parts are parts by weight.

[Intrinsic viscosity] Dissolve in a mixed solvent of phenol / ethane tetrachloride = 6/4 (weight ratio) and measure at 25 ° C with an Ubbelohde viscometer.

[DEG content] After polyester is decomposed with alkali, it is quantified by gas chromatography (manufactured by Shimadzu).

[Solution haze] 5.4 g of polyester is phenol / ethane tetrachloride = 6/4
After being dissolved in 40 ml (by weight) of a mixed solvent at 100 ° C. for 2 hours, haze is measured using a digital turbidimeter (manufactured by Tokyo Denshoku Co., Ltd.) using a 10 mm cell.

[Color tone of polyester and film] L value and b value by a fully automatic color difference meter (manufactured by Tokyo Denshoku Co., Ltd.) were used. The larger the L value, the stronger the lightness, and the b value shows the degree of yellow and blue, and the larger the (+) side, the stronger the yellow.

[Polyester melt specific resistance value] Two copper plate electrodes are allowed to stand in polyester melted at 290 ° C, and the current value when a high voltage of 1 KV is applied is read to calculate the specific resistance value (Ω · cm). .

[Static Application Castability] In the die of the extruder, a voltage of 10 KV is applied between the electrode on the upper part of the extruded film and the casting drum,
A film is formed at a casting speed of 30 m / min, and the quality of the obtained film is evaluated visually for the flatness and the presence or absence of pin-shaped defects.

The judgment criteria are displayed as shown in the following table.

[Increase of filtration pressure] When polyester is dried and melted, it is extruded from the extrusion die at a constant extrusion speed through a filter at a constant extrusion speed, and when a film is formed by an ordinary method, the pressure difference before and after the extrusion filter with the extrusion time is Read and evaluated.

[Film Haze] Polyester was molded into a non-stretched sheet having a thickness of 1200 μm by a conventional method and then biaxially stretched to obtain a stretched film having a thickness of 100 μm. Using this as a sample, the white plate slide knob of a light scattering photometer (manufactured by Tokyo Denshoku Co., Ltd.) was adjusted and the displayed value was read and displayed.

Example 1 0.0422 parts of trimethyl phosphate (TMP) (as phosphorus
0.30 × 10 ^-3 mol) and ethylene glycol (EG) 7
4.4 parts (1.20 mol) and terephthalic acid (TPA) 166 parts (1.0
20 mol parts of the esterification reaction product (corresponding to 1.00 mol of TPA) having an esterification rate of 97.0% obtained from
Stored in the TMP16, and TMP0.0422 and EG74.4 and TPA16
While continuously adding 6 parts of the slurry at a constant rate, the esterification reaction was carried out at 250 ° C. under normal pressure, and the produced water was continuously distilled out of the system from the rectification column. TMP and EG
The supply of the slurry of TPA and TPA was completed in 3 hours and 30 minutes, the esterification reaction was continued for another 30 minutes, and the esterification reaction was completed in 4 hours. 205.5 parts (corresponding to 1.00 mol of TPA) of the obtained esterification reaction product was left in the reactor, and the esterification reaction was performed again by the same method as described above. These operations were repeated a total of 3 times to finally obtain an esterification reaction product having an esterification rate of 97.0%. The esterification rate was obtained by measuring the saponification value and acid value of the sample and using the above formula. this
Take 205.5 parts in a polycondensation reactor, add 0.116 parts of magnesium acetate tetrahydrate (corresponding to 0.54 × 10 ^-3 mol of magnesium), stir to solubilize, and then add 0.05 parts of antimony trioxide.
Add 7 parts by the usual method final temperature 282 ℃, vacuum degree 0.5mmHg
Polycondensation was carried out for 4 hours and 30 minutes to obtain a polyester. Also, after taking this polyester into a dryer and drying it, send it to a melt extruder equipped with a filter, melt it, pressurize it through a filter and remove coarse particles, foreign matters, etc. while rotating it into a sheet from the extrusion die. A polyester film having a thickness of 100 μ was obtained by extruding the film onto a drum and performing biaxial stretching in the lengthwise and crosswise directions to form a film by a conventional electrostatic applied casting method. The results are shown in Table-3. The obtained polyester had a particularly small solution haze and excellent transparency, a small b value and thus a small yellowish color, a good color tone, and a low melt specific resistance value and excellent electrostatic castability. Further, the obtained 100μ biaxially stretched film has less yellowish color and has no pin-shaped defect,
It was suitable for photographic use because it was particularly excellent in flatness and transparency with little unevenness in film thickness.

Example 2 EG68.2 parts (corresponding to 1.1 mol), esterification rate 97.5%
A polyester and a polyester film were obtained in the same manner as in Example 1 except that 199.1 parts of the esterification reaction product (corresponding to 1.0 mol of TPA) and the esterification reaction time were completed in 4 hours and 15 minutes. The results are shown in Table-3.

The obtained polyester had a good color tone and excellent transparency like the one obtained in Example 1, and had a low melting specific resistance value, was of high quality and was excellent in productivity and was suitable for photography. .

Examples 3 to 5 Table 2 shows the types and addition amounts of phosphorus compounds and divalent metal compounds.
A polyester and a polyester film were obtained in the same manner as in Example 1 except that the change was made as shown in FIG. The results are shown in Table-3. Each of the obtained polyesters was suitable for photography in terms of color tone, transparency and melt specific resistance.

Examples 6 and 7 Polyesters and polyester films were obtained in the same manner as in Example 2 except that the addition amounts of TMP and magnesium acetate tetrahydrate were changed as shown in Table-2. 3 shows. Added TMP and magnesium acetate 4
The addition amount of the hydrate is within the range specified in the present invention, and all of the obtained polyesters are excellent in transparency and have good castability for electrostatic application because of their small melt specific resistance. However, it had a good color tone and was suitable for photography.

Comparative Example 1 Example 1 without containing TMP in the slurry of EG and TPA
An esterification reaction product was obtained in the same manner as in Example 1, except that the same amount of magnesium acetate tetrahydrate as in Example 1 was added and 10 minutes later, the same amount of TMP was added. Polyester and polyester film were obtained. The results are shown in Table-3. The obtained polyester was yellowish and inferior in transparency, and was of insufficient quality for photography.

Comparative Example 2 A polyester and a polyester film were obtained in the same manner as in Example 1 except that the esterification reaction product was obtained without containing TMP in the slurry of EG and TPA. The results are shown in Table-3.

The obtained polyester had a strong yellow tint, had a large solution haze, and when a film was formed, an increase in filtration pressure was observed in a short time, and it was unsuitable for photography because of its quality and productivity.

Comparative Example 3 As shown in Table 2, the divalent metal compound to be added is 0.0483 parts (0.34 parts) of lithium acetate dihydrate which is a monovalent metal compound.
A polyester and a polyester film were obtained in the same manner as in Example 5, except that the amount was changed to × 10 ⁻³ mol). The results are shown in Table-3.

The obtained polyester had a very strong yellowish tint, the solution haze was extremely large, and when the film was formed, an increase in filtration pressure was recognized in a short time, and it was unsuitable for photography because of its quality and productivity.

Comparative Examples 4 to 6 The amount of TMP contained was 0.00124 parts (0.02
A polyester was obtained in the same manner as in Example 7 except that the amount was changed to (corresponding to × 10 ^-3 mol) (Comparative Example 4). A polyester was obtained in the same manner as in Example 7 except that the amount of magnesium acetate tetrahydrate added was changed to 0.0121 parts (corresponding to 0.05 × 10 ⁻³ mol) (Comparative Example-5). In addition, contains TM
The amount of P was 0.00124 parts (equivalent to 0.02 × 10 ^-3 mol), and the amount of magnesium acetate tetrahydrate added was 0.0121 parts (0.05
A polyester and a polyester film were obtained in the same manner as in Example 1 except for the change of (corresponding to × 10 ⁻³ ) (Comparative Example 6). The results are shown in Table 3 for each.

Each of the obtained polyesters had a color tone with a strong yellow tint, had a large melt specific resistance value, and had extremely poor castability under static electricity application, and was unsuitable for photography.

Comparative Example 7 As shown in Table 2, the amount of TMP contained was 0.304 part (2.17 parts).
× corresponding to 10 ^-3 moles), except changes to the amount of 0.515 parts of added magnesium acetate tetrahydrate (2.4 equivalent to × 10 ^-3 mol), polyesters and polyester film in the same manner as in Example 2 Obtained. The results are shown in Table-3. The obtained polyester was yellowish and had a large solution haze, which was unsuitable for photography.

Comparative Example 8 As shown in Table 2, comparison was made except that magnesium acetate tetrahydrate was 0.03 part (corresponding to 0.14 × 10 ⁻³ mol) and TMP 0.02 part (corresponding to 0.07 × 10 ⁻³ mol). A polyester and a polyester film were obtained in the same manner as in Example 1, and the results are shown in Table-3.
Shown in.

The obtained polyester was able to improve the transparency as compared with Comparative Example 1, but the melt specific resistance was large and the castability under static electricity application was poor. Film formation rate 30m / min, applied voltage 10KV
When the film is formed with, the adhesion between the film and the cooling drum is poor,
The flatness of the film after biaxial stretching was uneven. Although the film formation speed could be reduced to 16 m / min to obtain a film having no problem in flatness, the productivity of film formation is significantly reduced.

Example 8 A polyester was prepared by a configuration of a complete mixing tank each equipped with a rectification column, a horizontal multi-stage tank, and a complete mixing tank operated under reduced pressure and a horizontal polymerization finisher, in which an esterification step and a polycondensation step were successively performed. In the continuous polymerization apparatus, the slurry of EG and TPA containing TMP used in Example 2 (EG / TPA = 1.10, molar ratio) was continuously charged into the first reactor (complete mixer) of the esterification step. Then, magnesium acetate tetrahydrate and antimony trioxide, the same amount as in Example 2, respectively, were continuously added to the last front section and the last section of the horizontal multi-stage tank in the esterification step, respectively, and the conditions shown in Table 1 were used. Polyester was obtained in the same manner as in Example 1 and a polyester film was obtained in the same manner as in Example 1. The results are shown in Table-3.

Comparative Example 9 Example 2 without containing TMP in the slurry of EG and TPA
In the same way as above, an esterification reaction product was obtained, and then the same amount of magnesium acetate tetrahydrate and the same amount of antimony trioxide and the same amount of TMP were added to the section before the end of the horizontal multistage tank of the esterification process. Was continuously added to the final section to obtain a polyester and a polyester film under the same conditions as in Example 8. The results are shown in Table-3.

In Example 8, the esterification reaction time was greatly shortened as compared with Example 2, and the respective characteristic values and film moldability of the polyester obtained by this pressure method were the same as those obtained in Example 2. Compared with, the yellowish color was smaller and the transparency was more excellent. Furthermore, using this polyester, an appropriate amount of blue dye is added to this polyester, and melt-extruded on a rotating cooling drum by an extruder to form a film by a static film casting method at a film forming speed of 20 m / min and an applied voltage of 10 KV. Stretched to a film thickness of 175
A blue colored polyester film of μ was obtained. This blue colored film had a uniform film thickness, had no pin-like defects, had a clear blue color tone without yellowing, was excellent in transparency, and was suitable for X-ray photography.

On the other hand, in Comparative Example 9, for example, as in Comparative Example 1, after the esterification reaction was performed without including the phosphorus compound in the slurry of EG and TPA, the conventional method of adding the phosphorus compound was changed to the pressure method. This is an example of application, but as is clear from comparison with Comparative Example 1, unlike Example 8, almost no improvement in quality due to the application of the pressurizing method is observed. Further, as compared with Example 8, the obtained polyester and film were inferior in transparency, were inferior in castability by electrostatic application and in color tone and were unsuitable for photography.

Example 9 The polyesters shown in the above Examples 1 to 8 and Comparative Examples 1 to 9 were applied and the film thickness was 17 as a support for an X-ray photographic film.
5μ blue colored film, 100μ film thickness clear (colorless) film as a support for printed photographic film were prepared by the conventional electrostatic applied cast method and undercoated. Photosensitive emulsion was coated by a conventional method and dried to prepare photographic film samples Nos. 1 to 17.

Using the obtained photographic film, the exposure amount is changed stepwise for exposure, and development processing is performed to obtain the color tone, fog value and devitrification (transparency) of the unexposed area, and spots (small circular defects). Then, there was sensitization and desensitization) and uneven photosensitive failure.
Each evaluation method is as follows. The results are shown in Table-4.

[Color tone of photographic film] In addition to the color tone of the photosensitive emulsion to be coated, the color tone of the photographic film mainly consists of the color tone of the polyester itself as the film support and the color tone of the added blue dye. To tell. As the evaluation method of color tone of photographic film,
It is common to visually judge an unexposed photographic film by subjecting it to a development process by a white light.

The evaluation standard of the color tone of the present invention is defined and displayed as follows.

[Transparency of photographic film] Five samples of unexposed photographic film developed by a usual method were superposed, passed through white light, and judged and displayed according to the following criteria.

[Fault of photographic film] Among the faults of the photographic film, as the fault considered to be caused by the film support, coating unevenness caused by unevenness of the surface,
There was sensitization or desensitization due to foreign matter, devitrification due to scratches and crystallization, etc., and the number and strength of failures per unit area (m ² ) were judged and displayed based on the following criteria. .

[Suitability of photographic film] The suitability of each of the above photographic film supports was comprehensively evaluated, and judged according to the following criteria and displayed.

As is clear from Table 4, the polyesters of Examples 1 to 8 to which the method for producing a polyester of the present invention is applied are all suitable as a photographic film support. On the other hand, none of Comparative Examples 1, 8 and 9 using the conventional method sufficiently satisfied the quality of the photographic film support.

Claims (4)

[Claims] 1. When a polyester is produced from a dicarboxylic acid and a glycol, the amount of the dicarboxylic acid is 0.
03 × 10 ^{−3 to} 2.0 × 10 ⁻³ A slurry of a dicarboxylic acid containing a phosphorus compound corresponding to a phosphorus atom and a glycol is mixed with bis (β-hydroxylethyl) terephthalate and / or
Alternatively, the esterification reaction is carried out by continuously or intermittently supplying to the low polymer thereof to substantially complete the esterification reaction, and then 0.08 × 10 ^-3 to 2.
A process for producing a polyester, which comprises adding a divalent metal compound corresponding to 0 × 10 ⁻³ mol of a metal atom, and then causing a polycondensation reaction in the presence of a catalyst. 2. The method for producing a polyester according to claim 1, wherein the phosphorus compound is selected from phosphoric acid, phosphorous acid, trimethyl phosphate and triethyl phosphate. 3. The method for producing a polyester according to claim 1, wherein the slurry has a molar ratio of dicarboxylic acid to glycols of 1: 1.05 to 1.25. . 4. The divalent metal compound is zinc, magnesium,
Claim 1 characterized in that it is selected from manganese, calcium, barium and cobalt compounds.
The method for producing a polyester according to item (2) or (3).