JPH03182523A - Production of polyester - Google Patents

Abstract

PURPOSE:To obtain a polyester excellent in productivity in forming films and slidability, having a low content of coarse particles and being useful as a base film for magnetic tapes by adding a specified amount of colloidal SiO2 and a specified amount of an alkali metal hydroxide to the reaction system before the completion of the precondensation reaction in the production of an aromatic polyester. CONSTITUTION:Colloidal silicon oxide (A) (of a mean particle diameter <=2.0mum, desirably <=0.5mum, more desirably <=0.2mum) and an alkali metal hydroxide and/or an alkali metal oxide (B) are added to the reaction system in an arbitrary stage before the completion of the precondensation reaction (the time when the intrinsic viscosity reaches 0.2) in the production of a polyester from an aromatic dicarboxylic acid and/or its ester and a glycol (desirably one comprising at least 80mol%, based on the total repeating units, ethylene terephthalate). The amount of component A added is 0.01-2.0wt.%, based on the polymer, and 5.1-20.0wt.%, desirably 6-10wt.%, based on component A to B.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention is characterized in that colloidal silicon oxide particles are uniformly dispersed,
The present invention also relates to a method for producing polyester that has good electrostatic adhesion and can be used as a film raw material with extremely few large protrusions.

The polyester obtained by the method of the present invention has excellent film forming productivity and ease of slipping, and can be made into a polyester film with an extremely low content of coarse particles. Therefore, when used as a base film for a magnetic tape, for example, a metal coating type 8 mm film is used. Although it is extremely suitable as a raw material for manufacturing high-grade applications such as base films for magnetic tapes, it is not limited thereto. For example, since the number of coarse particles is small, it can be suitably used as a raw material for producing ultra-fine denier filaments. Also, in film applications,
It can also be widely applied to other fields such as electrical applications and films for vapor deposition.

(Prior art) Films made from saturated linear polyesters such as polyethylene terephthalate have excellent mechanical properties,
Because it has heat resistance, weather resistance, electrical insulation, chemical resistance, etc., it is widely used in a wide range of fields such as packaging, photography, electrical applications, and magnetic tape. However, these polyester films generally have a large coefficient of friction and are difficult to pass through processes such as film formation and coating, so various polyester manufacturing methods have been proposed that provide films with a small coefficient of friction and excellent slipperiness. .

Generally, the method of improving the slipperiness of polyester film is to include insoluble fine particles in polyester to form fine irregularities on the surface of the film.Specifically, when manufacturing polyester, The so-called external particle method involves adding insoluble and inert fine particles to polyester such as titanium dioxide, kaolinite, talc, colloidal silicon oxide, and calcium carbonate; There is a so-called internal particle method in which fine particles are formed by reacting one of the compounds with a metal compound.

Of the above two methods, the internal particle method requires strict control of polymerization conditions in order to keep the amount of precipitated fine particles and particle size constant at all times. In contrast, the external particle method
This method is widely used because the homogeneity of the product can be easily maintained by keeping the concentration and particle size of the inert particles constant. In particular, among external particles, colloidal silicon oxide is extremely useful in terms of quality control, as slurry of spherical monodisperse particles can be easily produced manually in recent years.

On the other hand, in recent years, in the field of base films for magnetic tapes, which is one of the uses for polyester films, as the recording density of magnetic tapes has increased, there has been a demand for base films that are extremely flat and easily slippery. Opportunities to use monodispersed spherical colloidal silicon oxide are increasing, but when adding microscopic particles to the polyester manufacturing process, microscopic particles tend to agglomerate, making it difficult to obtain the desired flat film. The current situation is that there is no such thing.

Therefore, there is a strong need for the development of a method for producing polyester that uses minute particles and does not cause aggregation.

(Problems to be Solved by the Invention) The present inventors have focused on the above-mentioned circumstances, and have developed a film that has excellent film-forming productivity and slipperiness, and has an extremely low coarse particle content, and is used as a base film for magnetic tapes. The present invention was achieved as a result of extensive research aimed at establishing a method for producing polyester that is suitable as a raw material for producing films that has very little dropout defects.

(Means for Solving the Problems) When producing a polyester from an aromatic dicarboxylic acid and/or an ester-forming derivative thereof and a glycol, the present invention provides that colloidal silicon oxide is used together with colloidal silicon oxide at any stage until the initial condensation reaction is completed. A method for producing polyester, characterized in that an alkali metal hydroxide and/or oxide is added in an amount of 5.1% to 20.0% by weight based on colloidal silicon oxide, and more preferably M solubilized in polyester measured by the method defined in
The amount of g and P compound simultaneously satisfy the following general formula 30; ff1Mg≦400… (I) 0, 8≦Mg
/P≦3... (II) [In the formula, Mg is the content of the Mg compound as an Mg atom in the polyester (pp
), Mg/P indicates the atomic ratio. ] This can be achieved by

The polyester used in the present invention is a crystalline polyester with polyethylene terephthalate, polyalkylene naphthalate, etc., and although it is not particularly limited, polyethylene terephthalate is particularly suitable, and in particular, 80 mol% or more of its repeating units are composed of ethylene terephthalate. Other copolymerization components include isophthalic acid, p-β-oxyethoxybenzoic acid, 2,6-naphthalene dicarboxylic acid, 4,4'-dicarboxyl diphenyl, 4,4'-dicarboxyl benzophenone, Dicarboxylic acid components such as bis(4-carboxylphenyl)ethane, adipic acid, sebacic acid, 5-sodium sulfoisophthalic acid, cyclohexane-1,4-dicarboxylic acid, propylene glycol, butanediol, neopentylglyfur, diethylene glycol, cyclohexane Glycol components such as dimetatool, ethylene oxide adduct of bisphenol A, polyethylene glyfur, polypropylene glycol, and polytetramethylene glycol, and oxycarboxylic acid components such as p-oxybenzoic acid can be arbitrarily selected and used. In addition, a small amount of a compound containing an amide bond, urethane bond, ether bond, carbonate bond, etc. may be included as a copolymerization component.

The colloidal silicon oxide of the present invention is produced by, for example, an alkoxy metal hydrolysis method in which an alkoxysilane is used as a starting material and is produced by hydrolysis and condensation, or a sodium silicate method in which it is produced by dealkalization of sodium silicate. Can be mentioned.

The colloidal silicon oxide used in the present invention usually has an average particle size of 2IJJ or less, but is particularly suitable for a base film for a metal-coated 8 mm video, preferably 0.5- or less, preferably 0.2- The following are desirable.

If the average particle size exceeds 2, the number of coarse particles in the film will increase when used as a base film for video.
This is not preferable because it causes drawbacks such as dropouts.

Note that the average particle diameter referred to herein refers to the diameter at the cumulative 50% point of the equal borosilicate diameter particle size distribution calculated based on Stokes' equation.

The amount of colloidal silicon oxide added is preferably 0.01 to 2.0% by weight based on the polyester produced.

If the amount added is less than 0.01% by weight, the effect of improving slipperiness will be insufficient, which is not preferable. On the other hand, if it exceeds 2.0% by weight, the smoothness of the film deteriorates, which is not preferable.

The alkali metal hydroxide and/or oxide used in the present invention is a hydroxide and/or oxide of lithium, sodium, potassium, rubidium, etc., and is added together with colloidal silicon oxide, and the amount added is The amount is 5.1% by weight or more and 20% by weight or less based on colloidal silicon oxide, preferably 6% by weight to 10% by weight.

If the amount of alkali metal hydroxide and/or oxide is less than 5% by weight, the effect of preventing aggregation will be small, and if it exceeds 20% by weight, the quality of the polyester, especially the color tone and electrostatic adhesion during film formation will deteriorate. Undesirable.

In the present invention, it is essential to use colloidal silicon oxide as the lubricant.

If an alkali metal compound within the preferred range of the present invention is added without using colloidal silicon oxide, the color tone and electrostatic adhesion during film formation will be significantly reduced, whereas when an alkali metal compound is used in combination with colloidal silicon oxide. As a result, a remarkable anti-coagulation effect can be exhibited without deteriorating these qualities.

Examples of the Mg compound used in the present invention include magnesium hydroxide, lower fatty acid salts such as magnesium oxide and magnesium acetate, and alphoxides such as magnesium methoxide.

On the other hand, P compounds include phosphoric acid, phosphorous acid, phosphonic acid, and derivatives thereof, and specific examples include phosphoric acid, trimethyl phosphate, triethyl phosphate, tributyl phosphate, and triphenyl phosphate. Ester, phosphoric acid monomethyl ester, phosphoric acid dimethyl ester, phosphoric acid monobutyl ester, phosphoric acid dibutyl ester, phosphorous acid, phosphorous acid trimethyl ester,
Phosphite triethyl ester, phosphite tributyl ester, methylphosphonic acid, methylphosphonic acid dimethyl ester, ethylphosphonic acid dimethyl ester, phenylphosphonic acid dimethyl ester, phenylphosphonic acid diethyl ester, phenylphosphonic acid diphenyl ester, etc. Can be used alone or as 2fl! The above may be used in combination. Particular preference is given to using phosphoric acid, phosphorous acid and their ester derivatives.

In order to produce a polyester that has excellent electrostatic adhesion during film formation and has a small number of coarse particles in the polymer, the amount of solubilized Mg should be between 30 ppm and 4001) pl, preferably between 50 ppm and 150 ppm. Something between ppm,
In addition, when alkaline earth metals other than Mg are used together, the atomic weight ratio of Mg should be within the above range, and the atomic ratio of Mg and P should be between 0.8 and 3.0, preferably 1. ．．
It is important that it be between 0 and 2.0. If it is outside the above range, problems such as good electrostatic adhesion may not be obtained, scale will be generated in the reaction vessel during polyester polymerization, and this will be mixed into the polyester, resulting in an abnormally large number of coarse particles in the polymer.

In the present invention, inert fine particles other than colloidal silicon oxide may be used in combination as a lubricant.

As these inert fine particles, any inorganic or organic fine particles may be used as long as they are insoluble and inactive with respect to the polyester produced.

Other inorganic fine particles that may be used in combination include calcium carbonate, titanium oxide, zirconium oxide, aluminum oxide,
Examples include metal oxides such as iron, olinite, and talc, sulfates such as calcium sulfate and barium sulfate, carbonates such as magnesium carbonate, and sulfides such as zinc sulfide. Further, examples of the organic fine particles include fine particles of a crosslinked polymer compound such as a styrene-divinylbenzene copolymer.

Further, fine particles precipitated during the polyester manufacturing process, so-called internal particles, may also be used together.

Furthermore, colloidal silicon oxides of class 281 or higher having different particle sizes may be used in combination.

The method of using two or more types of lubricants in combination is one of the useful methods because it can widen the range of changes in the surface properties of the final product film.

However, in order to produce an extremely smooth film, the effects of the present invention are most pronounced when a combination of two or more types of spherical monodisperse colloidal silicon oxide having different particle sizes is used.

Furthermore, other dispersants may be used in combination, but their effects are not so pronounced.

Ethylene glycol (EG) is preferred as the solvent for the colloidal silicon oxide slurry, but other solvents such as water and alcohols may be mixed as long as the amount is 50% by weight or less.

The alkali metal hydroxide and/or oxide may be added to the slurry at any stage from the start of slurry preparation to the addition to the polyester manufacturing process.

The slurry may be added to the polyester manufacturing process at any stage until the initial condensation reaction is completed.

Note that the intrinsic viscosity at the end of the initial condensation reaction is approximately 0.
2, after which the viscosity of the reaction system is too high and the added components become unevenly mixed, making it impossible to obtain a homogeneous product. Furthermore, depolymerization of oligomers occurs, which is undesirable because it causes a decrease in productivity and an increase in the amount of diethylene glycol (DEC) by-product.

The method of the present invention can be applied to both the so-called transesterification method, in which dimethyl ester of aromatic dicarboxylic acid and glycol are transesterified, and the so-called direct polymerization method, in which aromatic dicarboxylic acid and glycol are directly reacted. can. Moreover, it can be applied to both batch-type and continuous-type production methods. When carrying out the transesterification method, there are no particular limitations on the transesterification catalyst, and any conventionally known catalyst can be used.

When carrying out the direct polymerization method, there are no restrictions on the use of amines, quaternary ammonium salts, etc. as inhibitors of DEC formation.

Although the polycondensation catalyst is not subject to particular restrictions, it is preferable to use an appropriate selection from among sb compounds, Ge compounds, and TI compounds.

The film formed from the polyester produced in the present invention may be either a uniaxially oriented film or a biaxially oriented film, but a biaxially oriented film is particularly preferred.

(Example) Next, Examples and Comparative Examples of the present invention will be shown. All parts in the examples mean parts by weight unless otherwise specified.

In addition, the measurement method used is shown below.

(1) Average particle size Centrifugal sedimentation type particle size distribution analyzer manufactured by Shimadzu Corporation (SA-CP3
) is used as the value at the cumulative 50% point in the equal borosilicate diameter distribution.

■ Number of coarse particles in the polymer A small amount of the polymer is sandwiched between two cover glasses.
After melt-pressing at 0°C and quenching, it was observed using a phase contrast microscope, and the number of particles with a maximum length of 3/jj or more in the particle image (measurement area 4° 8 - Count the number of pieces per piece).

(3) Quantitative resin of metal and P content solubilized in polymer 500μ
(2) Dissolve in Q and filter under pressure using a 0.1μ nitrocellulose membrane filter.

The filtrate is poured into 100 W, Q ethanol to reprecipitate the polymer. The metal and P contents in the reprecipitated polymer were determined by plasma emission X! Quantitate using method 1.

(2) Melting specific resistance of polymer Place two electrode plates in polyester melted at 275°C, apply a voltage of 120 V, measure the current value (io), and calculate the specific resistance value (ρi) using the following formula. Find it by

A=electrode area (cd), Chu=interelectrode distance (c-)■=
Voltage (V) ■ Film surface smoothness (TAR) The film surface was measured using a stylus-type three-dimensional surface roughness meter (SE-3AK) manufactured by Koita Research Institute, with a needle radius of 2 mm and a load of 30 mm.
The cutoff value is 0.25 in the longitudinal direction of the film.
Measurement is performed over one measurement length, and data in the height direction is imported into an external storage device every 2ta with a quantization width of 0.00312u.

Such measurements were carried out 150 times in succession in the transverse direction of the film at 2-interval intervals, i.e. 0.3 in the transverse direction of the film.
．． , measured across the width of . The data in the height direction at this time is h (i, j) [: i=1 to 500. j
= 1 to 150, the value obtained by calculating the following formula and expressed in one unit is TAR [three
Dimensional Average Roughness].

... ■ (6) Film slipperiness According to ASTM-D-1894-83T, 23°C, 65°C
It is expressed as a dynamic friction coefficient (μd) measured at %RH and a tensile speed of 200 m/min.

(7) Number of coarse protrusions on the film surface Aluminum is deposited on the film surface, and a field of view of 5 IIIli or more is observed using a two-beam interference microscope.

The number of interference rings of secondary or higher order is counted, converted to the number per 1- and displayed.

Example 1 Using a continuous esterification reactor consisting of a two-stage complete mixing tank equipped with a stirrer, a partial condenser, a raw material inlet, and a product outlet, the esterification reaction product in the first esterification reactor was The molar ratio of EG to terephthalic acid (TPA) was adjusted to 1.7, and antimony trioxide was used as an antimony atom to give 28 Qpp- per TPA unit.
The EG slurry of TPA containing was continuously fed.

At the same time, from a supply port different from the TPA EG slurry supply port, the EG hot solution of four salts of magnesium acetate was passed through the reactor so that the amount of Mg atoms per polyester unit in the reaction product was 100 pp-. Continuously supplied, average residence time 4.5 hours at normal pressure, temperature 25
The reaction was carried out at 5°C.

This reaction product was continuously taken out of the system and supplied to the second esterification reactor. 0.5N part of EG per polyester unit in the reaction product passing through the second esterification reactor,) EG of remethyl phosphate
75 pp garden as hot solution P atoms and average particle size 0.18
/Jj spherical colloidal silicon oxide dispersed in EG at a concentration of 10% by weight, 40g/Q of sodium hydroxide aqueous solution as solid content, 6.0% by weight based on the colloidal silicon oxide in the slurry. %, and the sodium hydroxide-containing slurry was continuously fed from separate supply ports so that the amount of colloidal silicon oxide was 0.2% by weight, and the average residence time was 3.0% at normal pressure. time,
The reaction was carried out at a temperature of 260°C.

The esterification reaction product is continuously supplied to a two-stage continuous polycondensation reactor equipped with a stirrer, a partial condenser, a raw material inlet, and a product outlet for polycondensation, and the intrinsic viscosity is 0.
．． 820 polyester was obtained. The polymer and the polymer were melt extruded at 290°C and extruded in the machine direction at 90°C for 3
．． 5 times, stretched 3.5 times in the transverse direction at 130°C and then 220
Table 1 shows the properties of the 15/Jj film obtained by heat treatment at °C.

The polymer obtained in this example has excellent high-speed film forming properties, has a small number of coarse particles, and has an extremely small number of coarse protrusions on the film surface. Furthermore, it can be seen that the film obtained in this example has excellent slipperiness and is of extremely high quality.

Comparative Example 1 The method described in Example 1 except that the solid content of an aqueous solution of IJium (40 g/l of hydroxide to the colloidal silicon oxide slurry) was 1% by weight based on the colloidal silicon oxide in the slurry. Table 1 shows the quality of the polymer and film obtained by polycondensation and film formation in exactly the same manner as described above. Although the film obtained in this comparative example had good slipperiness, it was found that the number of coarse particles in the polymer was significantly large, and the number of coarse protrusions on the film surface was large, resulting in low quality.

Examples 2 to 5, Comparative Examples 2 to 4 Table 1 shows the results when the average particle size of colloidal silicon oxide and the amount and type of alkali metal compound relative to colloidal silicon oxide were changed from Example 1. .

Comparative Example 5 Table 1 shows the quality of the polymer and film obtained by performing polycondensation and film formation in the same manner as in Example 3, except that the addition of colloidal silicon oxide was discontinued.

The following margins (effects of the invention) As described above, by using the production method of the present invention, secondary aggregation of colloidal silicon oxide particles is reduced in the polyester production process, and the number of coarse particles in the obtained polymer and film is reduced. The number of coarse protrusions is extremely small,
The film-forming process has good productivity and has the excellent effect of producing an easily slippery film.

Claims (1)

[Scope of Claims] (1) When producing polyester from aromatic dicarboxylic acid and/or its ester-forming derivative and glycol, an alkali metal is added together with colloidal silicon oxide at any stage until the initial condensation reaction is completed. A method for producing polyester, which comprises adding hydroxide and/or oxide in an amount of 5.1% by weight or more and 20.0% by weight or less based on colloidal silicon oxide. (2) The method for producing polyester according to claim 1, characterized in that the amounts of Mg and P compounds solubilized in the polyester, measured by the method defined in the text, simultaneously satisfy the following general formula: . 30≦Mg≦400...(I) 0.8≦Mg/P≦3...(II) [In the formula, Mg is the Mg relative to the polyester of the Mg compound
The atomic content (ppm) and Mg/P indicate the atomic ratio. ]