JPS58191716A - Preparation of polyester - Google Patents

Abstract

PURPOSE:To prepare a polyester containing a large amount of uniform and fine particles and having excellent opacity and slippery, by adding a P-compound and an Li-compound to the ester exchange reaction product, and carrying out the polycondensation reaction under specific condition. CONSTITUTION:The objective polyester is prepared by (1) carrying out the ester exchange reaction of (A) an acid component composed of a lower alkyl ester of terephthalic acid with (B) a glycol component composed of ethylene glycol, (2) adding (C) a lithium compound (preferably lithium formate, etc.) and (D) a phosphorus compound (e.g. methyl phosphate, etc.) to the system after the completion of the ester exchange reaction, and (3) starting the polycondensation reaction. The amount of the component C is selected to satisfy the formula 60<=GL/Li< 180 (GL and Li are the molar numbers of the component B and C per 1mol of the alkyl terephthalate in the component A, respectively). EFFECT:A film having excellent workability and handleability, etc. can be manufactured therefrom.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing polyester, and more particularly to a method for producing polyester having improved slipperiness, opacity, and surface condition.

In general, polyester, especially polyethylene terephthalate, has excellent mechanical properties, heat resistance, weather resistance, electrical insulation, and chemical resistance, so it is used for clothing and industrial fibers, as well as magnetic tape films, photographic films, electric insulation, and capacitors. Widely used in film fields such as film.

When polyester is used in the film field, it is important to pass through the molding processes of melt extrusion, stretching, and heat treatment, or for film molding, winding, cutting, and surface coating such as magnetic layers.

The best in terms of ease of assembly into electrical parts, slippage of film products, and opacity! Due to its value as a product, it is common practice to create a polyester composition containing fine particles, which gives the surface an appropriate degree of roughness to give it smoothness, facilitate film flow during film production, and make the film opaque. It is being done.

Examples of polyester compositions containing such fine particles include: ■ Polyester obtained by adding and blending inert insoluble inorganic particles such as silicon oxide, titanium dioxide, carunium carbonate, talc, and clay; ■ Used during polyester synthesis. Polyesters obtained by precipitating part or all of catalyst components and adhesion inhibitor components as fine particles during the polymerization reaction process are known. However, such known fine particle-containing polyesters have the following problems: In particular, when molded into a film, its slipperiness, opacity, surface condition, film formability, etc. were not satisfactory.

That is, in the so-called external particle-containing polyester composition of (2) above, it is difficult to make the additive particles finer, and coarse particles are present due to agglomeration of particles.

In addition to non-uniform particle size, there are other drawbacks such as falling off due to lack of affinity between the particles and polyester, tearing during film formation, and coarse protrusions caused by coarse particles when formed into a film. In addition to causing problems such as fine eyes and dropouts, the electrical insulation properties are reduced, and dispersants added to prevent particles from agglomerating often reduce the heat resistance and electrical insulation properties of these polyesters. There are many drawbacks such as being forced to do something.

On the other hand, the polyester obtained by the so-called internal particle method described in (2) above has a small particle content, and it is easy to generate coarse particles, and it is difficult to control the particle size of precipitated particles. There is a large amount of deviation between the layers, and when molded into a film, it is not only difficult to obtain satisfactory slipperiness and opacity, but also has undesirable drawbacks such as fish eyes and dropouts, making it difficult to obtain satisfactory surface characteristics. be.

Furthermore, if the amount of catalytic metal compound added is increased to increase the amount of particles, the amount of coarse particles will increase due to agglomeration of individual particles, and in batch systems, the number of coarse particles will further increase due to the influence of remaining polymer. In addition, problems such as coloration of the polyester, decrease in melting point, and increase in carboxyl terminal groups occur due to an increase in the rate of side reactions.

For example, an example of the internal particle method mentioned above is published in Japanese Patent Publication No. 48-792.
71. Although described in Japanese Patent Application Laid-Open No. 55-4103, etc., it has been found that these conventional methods do not exhibit sufficient effects in the above-mentioned applications.

Particularly in recent years, in the field of magnetic tapes such as audio tapes, video tapes, and memory tapes, it is necessary to reduce the thickness of the tape in order to achieve miniaturization and higher density, and there is a growing demand for finer and finer unevenness on the film surface. . Further, in electrical insulation applications, opacity is required, and in order to improve this opacity, it is necessary to generate a large amount of particles, and the particle size must be fine.

The presence of coarse particles is undesirable because it tends to cause dielectric breakdown. Furthermore, it does not contain particles,
Alternatively, it may be blended with a polyester having a low particle content to impart good surface properties to the polyester and to form a molded product with excellent slipperiness, without coarse particles and containing a large amount of fine particles. Raw materials are required.

However, the finer these internal particles are and the larger the amount of particles, the more likely coarse particles are produced due to agglomeration of particles. In the cased batch method, the polymer from the previous batch remains, and the decomposition of this remaining polymer and particle aggregates in the remaining polymer have an adverse effect on the next low polymer, causing the formation of coarse particles during the particle generation process. It has been found that extremely inconvenient phenomena occur.

In view of the above circumstances, the present inventors have completed the present invention as a result of intensive study on a method for producing a large amount of fine particles in polyester.

The present invention relates to a method for producing polyester using a lower alkyl ester of terephthalic acid as the main acid component and carrying out a polycondensation reaction in the presence of an ethylene glycol metal compound and a phosphorus compound. and a phosphorus compound, and then a polycondensation reaction is initiated within a range where the glycol component 1 for the lithium compound satisfies the following formula (II).

Li (In the formula, GL and Li represent the respective moles of the glycol component and lithium compound added to 1 mole of the alkyl ester of terephthalic acid.) Next, the present invention will be explained in detail. is mainly composed of polyethylene terephthalate, which can be formed into fibers, films, and other molded products.

In the present invention, the lower alkyl ester of terephthalic acid as the acid component of the polyester raw material mainly refers to the alkyl ester of terephthalic acid having 1 to 4 carbon atoms, especially dimethyl terephthalate, but some of it is also used as the acid component of other acid components. For example, dicarboxylic or oxycarboxylic acids other than terephthalic acid, lower alkyl esters such as p-hydroxybenzoic acid, adipic acid, and sebacic acid may be substituted.

The glycol component of the polyester raw material mainly refers to ethylene glycol, but a part of it may be replaced with other glycol components such as trimethylene glycol, tetramethylene glycol, hexamethylene glycol, etc. The compounds are glycol-soluble compounds, including lithium monocarboxylate salts such as lithium formate and lithium acetate, lithium halides such as lithium chloride and lithium bromide, organolithium compounds such as lithium hydride, ethyllithium, butyllithium, and Lithium carbonate and the like are preferably used.

The phosphorus compound used in the present invention is preferably one selected from the group consisting of phosphorus phosphorous acid, or their methyl esters, phenyl esters, and noph esters, and in particular phosphorus compounds. Methyl ester, ethyl ester and phenyl ester are preferred.

The amount of the soluble lithium metal compound added is 1.2 to 2.5 mol% (based on lower alkyl ester of terephthalic acid). If the amount of the lithium compound added exceeds 2.5 mol %, the added lithium compound will precipitate or agglomerate particles will occur in the polyester produced, which is not preferable. Also 1 or 2 mol%
If it is less than that, the amount of particles formed in the polyester produced is small, and slipperiness is insufficient and opacity is decreased, which is not preferable.

Further, the amount of the phosphorus compound added can be suitably preferably used in a range of 0.25 to 1.2 mol% (based on lower alkyl ester of terephthalic acid).

In the present invention, after the lithium compound and the phosphorus compound are added after the transesterification reaction is completed, the amount of the glycol component relative to the lithium compound at the start of the polycondensation reaction must be within the range shown in (1) above.

If the value shown by formula +11 is less than 60, not only will the generated particles become coarse, but also the generated fine particles will begin to aggregate, resulting in a decrease in the dispersibility of the particles in the polymer, resulting in coarse particles. exists, making it impossible to obtain the desired polymer. When the value indicated by 2m exceeds 180υ, not only no further effect can be found in improving the dispersibility of particles, but also an extension of the polycondensation reaction time.

This is not preferable because it results in a decrease in productivity.

Furthermore, the amount of by-products such as diethylene glycol produced increases, resulting in undesirable results in terms of polymer properties and the like.

In addition, in the present invention, the transesterification reaction includes an appropriate amount of catalysts such as alkali metals selected from the group consisting of lithium, sodium, and potassium, alkaline earth metals selected from the group consisting of magnesium, calcium, strontium, and halium, and zinc and manganese. The hydrides, alcoholades, chlorides and glycol-soluble salts of monocarboxylic acids can be used as catalysts. Preferred examples include calcium acetate, strontium acetate, zinc acetate, manganese acetate, and manganese chloride.

The typical catalyst systems still used for the polycondensation of bishydroxyalkyl esters of aromatic dicarboxylic acids are glycol-soluble antimony or hakermanium compounds, such as antimony trioxide.

Potassium antimony tartrate, antimony oxychloride.

Germanium oxide or the like is preferably used in an appropriate amount as a catalyst.

The polyester obtained by the method of the present invention contains a large amount of uniform and fine internal particles, and has excellent opacity and slipperiness. Therefore, when producing fibers or films from the polyester, it is impossible to achieve with conventional methods. The following effects are achieved.

■ There is less clogging of filters during the process of melt molding into fibers and films, and less chance of fibers being cut or film membranes being torn due to foreign matter contamination.

(2) When a biaxially stretched film is obtained by high-speed film forming at 200 m/min or more, a film with less curling and good workability in post-processing steps can be obtained.

Furthermore, the obtained film has excellent opacity and slipperiness, and can be made into a good film product.

■ Even when molded into an extremely thin film with a film thickness of 4μ or less, it has a large number of uniform fine particles and is extremely slippery without blocking phenomena between film and film, between film and metal, or between film and felt. A polyester film with excellent handling properties can be obtained.

■ Also, since it contains a large amount of uniform fine particles, it can be used diluted, and in this case too, there is no film fisheye, and especially in magnetic tape applications, there is no dropout or single image unevenness during playback.

There is no skipping and it is extremely useful.

The polyester obtained by the method of the present invention can be used not only for fibers such as multifilament staples, unoriented, -axially oriented, and biaxially oriented films, but also for monofilaments,
It can also be preferably used for plastics.

The present invention will be explained in detail by giving Examples below DI.

Incidentally, each characteristic value of the obtained polyester was measured according to the following method.

A, Number of particles in polymer: 20 m9 of polymer was sandwiched between two cover glasses, 2
After melt pressing at 80°C and quenching.

The number of particles of 0.5 μm or more present in 1- was counted by bright field method using an image analyzer (Luzex 500 (Japan Regulator Co., Ltd.)) and displayed in the following judgment.

1st grade: ≧20,000 ko/- 2nd grade: 10,000 or more and less than 20,000 ko/- 3rd grade:
5 oooυ and above 10,000 pieces/- less than 4th grade: (50
00 pieces/- Up to 2nd class can be used for practical purposes.

B. Particle dispersibility in polymer The number of particles of 7 μm or more compared to the total number of particles of 0.5 μm or more measured in A is expressed as a percentage and is expressed by the following judgment.

1st class = Particle abundance ratio of 7μ or more <5qb2nd class:
〃 Grade 3: 5% and less than 10%: 4th grade: ≧30 and 2nd grade: 10% and less than 30 particles.

1.0g of C1 solution haze polymer in 4/6 of tetrachloroethane/phenol
Add to 20 cc of mixed solvent and heat to dissolve at 100°C.

The solution was sampled into a quartz glass cell with a thickness of 20 m, and the haze value was measured using a direct reading haze computer (manufactured by Suga Test Instruments Co., Ltd.) and expressed as a value.

D. Intrinsic viscosity and softening point of polymer Intrinsic viscosity is a value measured at 25°C using 0-chlorophenol as a solvent, and softening point is a value measured at 25°C using 0-chlorophenol as a solvent. This is the value measured at the temperature at which the tip of the load penetrates 51Eilυ into the chip after heating.

E, film properties (al film haze (turbidity) ASTM-D
1003-52.

(b) Coefficient of Friction of Film Measured using a slip tester according to ASTM-D-1894B method. The coefficient of static friction was used as a measure of the slipperiness of the film.

(C) Roughness of surface irregularities of film The surface of the film was observed using a stylus roughness meter, and the difference between the highest and lowest parts of the obtained surface irregularities was expressed in μ units.

Example 1 0.09 parts by weight of calcium acetate was added as a catalyst to 100 parts by weight of dimethyl terephthalate and 70 parts by weight of ethylene glycol, and a transesterification reaction was carried out by a conventional method.

The product was then added with 0.03 parts by weight of antimony trioxide;
0.8 parts by weight of lithium acetate and 0.2 parts by weight of trimethyl phosphate were added, and then 30 parts by weight of ethylene glycol was distilled off. Thereafter, a polycondensation reaction was carried out in a conventional manner under high temperature vacuum to obtain a polymer having an intrinsic viscosity of 0.613.

The number of particles in the polymer, solution haze, and particle dispersibility were good as shown in Table 1.

The obtained polymer was formed into a sheet at 290°C by a conventional method,
Using a biaxial stretching machine, the longitudinal stretch ratio is 3.3 times, and the transverse stretch ratio is 5.
After stretching at 4 times, heat treatment was performed at 215° C. to obtain a film having a thickness of 20 μm. Work stability during film formation was good, and there were no problems such as film breakage. The haze of the obtained film was 48%, the coefficient of friction was 0.45, the average roughness of the film surface was 0.030μ, and the maximum roughness of the film surface was 027μ.
It was good.

Separately from the polyester, a transesterification reaction was carried out using 100 parts by weight of dimethyl terephthalate and 70 parts by weight of ethylene glycol using 0.09 parts by weight of calcium acetate as a catalyst. .03 parts by weight and 0.04 parts by weight of trimethyl phosphate were added and polymerized by a conventional method to obtain an intrinsic viscosity of 0.624.
A polymer having a solution haze of 6.1 was obtained. (Polymer A
After blending 20 parts by weight of the polymer AEIO and 20 parts by weight of the polymer of the present invention obtained above, a thickness of 12 parts by weight was obtained.
A film of μ was obtained. The obtained film had a static friction coefficient of 0.68, a maximum film surface roughness of 0.36μ,
It was good.

Example 2 0.09 parts by weight of calcium acetate was added as a catalyst to 100 parts by weight of dimethyl terephthalate and 60 parts by weight of ethylene glycol, and a transesterification reaction was carried out by a conventional method. The product was then added with 0.03 parts by weight of antimony trioxide, 1.65 parts by weight of lithium acetate, and 0.0 parts by weight of trimethyl phosphate.
．． Polycondensation was carried out in exactly the same manner as in Example 1 except that 2 parts by weight of ethylene glyfur was added and then 5 parts by weight of ethylene glyfur was distilled off to obtain a polymer having an intrinsic viscosity of 0.616.

The number of particles in the polymer, solution haze, and particle dispersibility were good as shown in Table 1.

Example 3 After completion of the transesterification reaction, 0.03 parts by weight of antimony trioxide, 0.8 parts by weight of lithium acetate, and 0.15 parts by weight of methyl acid phosphate were added, and then 12 parts by weight of ethylene glycol was distilled off. was polycondensed in exactly the same manner as in Example 1, and the intrinsic viscosity was 0.618.
of polymer was obtained. Number of particles in polymer, solution haze,
The particle dispersibility was even better as shown in Table 1.

Example 4 Polycondensation was carried out in Example 1 by varying the amounts of ethylene glycol and lithium acetate and the molar ratio of GL/Li to obtain a polymer. The results of particle number, solution haze, and particle dispersibility of each polymer are shown in Table 2.

Comparative Example 1 0.09 parts by weight of calcium acetate was added as a catalyst to 100 parts by weight of dimethyl terephthalate and 60 parts by weight of ethylene glycol, and a transesterification reaction was carried out by a conventional method.

The product was then added with 0.05 parts by weight of antimony trioxide;
1.65 parts by weight of lithium acetate, 0.2 parts of trimethyl phosphate
After adding 30 parts by weight of ethylene glycol, polycondensation was carried out in the same manner as in Example 1 to obtain a polymer having an intrinsic viscosity of 0.607. The particle dispersibility in the polymer was not favorable as shown in Table 1.The obtained polymer was formed into a sheet by a conventional method, and a film having a thickness of 20 μm was obtained in the same manner as in Example 1. The resulting film had a haze of 55 and a static friction coefficient of 0.38.
, the average surface roughness was 0.048μ, and the maximum film surface roughness was 0.58μ, and the film surface characteristics were extremely inferior to those of the film of the present invention.

Comparative Example 2 0.09 parts by weight of calcium acetate was added as a catalyst to 100 parts by weight of dimethyl terephthalate and 80 parts by weight of ethylene glycol, and a transesterification reaction was carried out by a conventional method. The product was then added with 0.06 parts by weight of antimony trioxide and 0.16 parts by weight of lithium acetate (GL/Li −=8
22), 0.04 parts by weight of trimethyl phosphate was added, and then 10 parts by weight of ethylene glycol was distilled off.

Thereafter, 9-polycondensation was carried out in a conventional manner under high temperature vacuum to obtain a polymer having an intrinsic viscosity of 0.617. A film having a thickness of 12 μm was obtained using the polymer in the same manner as in Example 1. The obtained film had a static friction coefficient of 0.57 and an average surface roughness of 0.57. '06
The film surface roughness was 1μ and the maximum film surface roughness was 0.6Sμ, and the film surface characteristics were poor.

Claims (1)

[Claims] A method for producing polyester by using a lower alkyl ester of terephthalic acid as the main acid component and ethylene glycol as the main glycol component, followed by transesterification and then polycondensation reaction in the presence of a lithium compound and a phosphorus compound. After the transesterification reaction is completed, a lithium compound and a phosphorus compound are added, and then a polycondensation reaction is started within a range in which the amount of glycol component relative to the lithium compound satisfies the following equation: Law. i (In the formula, GL and Ll represent the number of moles of each of the glycol component and lithium compound added to 1 mole of the alkyl ester of terephthalic acid.)