JPH0873576A - Production of polyester - Google Patents

Abstract

PURPOSE: To obtain a polyester which gives a film, etc., having excellent surface properties and is suited for use in a magnetic recording medium, etc. CONSTITUTION: The process for producing a polyester comprises reacting a diol and/or an ester-forming derivative thereof with a dicarboxylic acid consisting mainly of an aromatic dicarboxylic acid and/or an ester-forming derivative thereof and polycondensing the resulting monomeric and/or oligomeric dicarboxylic acid/glycol ester with stirring at a shear rate of 10sec<-1> or higher.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing polyester. More specifically, the present invention relates to a method for producing a polyester having reduced oligomers that bleed out when formed into a film or the like.

[0002]

2. Description of the Related Art Due to its excellent properties, polyester films are widely used in many applications such as magnetic tape, electrical insulation, photography, metallization and packaging. In particular, polyethylene terephthalate film and polyethylene-2,6-naphthalate film are excellent in flatness, mechanical strength, chemical properties, dimensional stability and the like, and are suitably used as a base film of a magnetic recording medium.

On the other hand, with the recent development of magnetic recording media, the characteristics required for the base film have become increasingly severe.

For example, in order to increase the density of a video tape, the surface of the base film is required to be flatter. However, bleeding out of the oligomer causes many problems such as scratches on the film surface, resulting in coating omission in the step of applying the magnetic layer, resulting in magnetic recording omission (dropout). Also, when using a magnetic tape, dropout of magnetic recording occurs during recording and reproduction. As a method for reducing the oligomer that causes the bleed-out, Japanese Patent Laid-Open No. 1-306421 proposes to reduce the oligomer by solid-state polymerization. However, in this method, the degree of polymerization of the obtained polymer is remarkably high, a higher temperature than usual is required for melting to form a film or the like, and the melt viscosity becomes high, resulting in poor moldability.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned drawbacks of the prior art and to obtain a polyester having a small amount of oligomers.

[0006]

The object of the present invention is obtained by reacting a diol and / or its ester-forming derivative with a dicarboxylic acid mainly containing an aromatic dicarboxylic acid and / or its ester-forming derivative. In producing a polyester by polycondensing a glycol ester of a dicarboxylic acid and / or a low polymer thereof,
It is achieved by polycondensation under stirring with a shear rate of 10 sec ^-1 or more.

The diols used in the present invention include ethylene glycol, 1,2-propanediol, 1,3
-Propanediol, neopentyl glycol, 1,3
-Butanediol, 1,4-butanediol, 1,5-
Aliphatic diols such as pentanediol, 1,6-hexanediol, diethylene glycol, triethylene glycol, polyalkylene glycol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, 1 , 4
-Alicyclic diol such as cyclohexanediol, hydroquine, 2,6-naphthalene diol, 1,5-naphthalene diol, 1,4-naphthalene diol, 4,4 '
-Aromatic diols such as biphenol and 2,2'-bis (4'-β-hydroxyethoxyphenyl) propane are preferred, and aliphatic diols and alicyclic diols are preferred, and aliphatic diols are more preferred. , And more preferably ethylene glycol, 1,3-propanediol, 1,4-butanediol and the like. These diol components may be used alone or in combination of two or more.

The aromatic dicarboxylic acid of the present invention is terephthalic acid, isophthalic acid, 1,3-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 1,6-naphthalenedicarboxylic acid. Acid, 1,7-naphthalenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid,
2,7-naphthalenedicarboxylic acid, 3,3′-biphenyldicarboxylic acid, 3,4′-biphenyldicarboxylic acid,
4,4'-biphenyldicarboxylic acid and the like, terephthalic acid, 1,4-naphthalenedicarboxylic acid,
1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid and 4,4′-biphenyldicarboxylic acid are preferred, and 2,6-naphthalenedicarboxylic acid and 4,4′-
Biphenyldicarboxylic acid is more preferred. These acid components may be used alone or in combination of two or more,
Furthermore, an aromatic oxycarboxylic acid such as p-hydroxybenzoic acid may be partially copolymerized.

These polyesters include dicarboxylic acids such as adipic acid, sebacic acid, phthalic acid, diphenoxyethanedicarboxylic acid, dichlorophenoxyethanedicarboxylic acid, diphenyletherdicarboxylic acid, diphenylsulfonedicarboxylic acid and diphenylketonedicarboxylic acid as copolymerization components. Acid and its ester-forming derivatives, trimellitic acid, pyromellitic acid, glycerol,
Pentaerythritol, 2,4-dioxybenzoic acid,
The polymer substantially linearizes other compounds such as trifunctional or higher-functional compounds such as 2,4-dioxybenzoic acid and 4-oxyisophthalic acid, and monofunctional compounds such as benzoic acid, lauryl alcohol and phenyl isocyanate. It may be copolymerized within a certain range.

The polyester used in the present invention may be blended with various additives such as an ultraviolet absorber, an antistatic agent, a stabilizer and a coloring agent.

Further, the polyester used in the present invention is blended with various particles for the purpose of improving the process passability in the molding step, the handleability of the obtained molded articles such as fibers and films, the workability and the commercial value. It may have been done. Specifically, natural products can be crushed and classified, or various particles produced by a synthetic method can be used. Specifically, inorganic particles such as silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, cerium dioxide, molybdenum oxide, tungsten oxide, calcium phosphate, barium sulfate, iron oxide, kaolin and carbon, alkali metals and alkaline earths. Particles precipitated in the polyester polymerization reaction system containing at least one kind of metal and phosphorus as a part of constituent components, that is, internal particles, further silicone resin particles, epoxy resin particles, polyimide particles, crosslinked polystyrene particles, alkyd particles, etc. Examples thereof include crosslinked polymer particles such as various vinyl particles.

In producing the polyester of the present invention,
A diol and / or an ester-forming derivative thereof,
In order to obtain a glycol ester of a dicarboxylic acid and / or a low polymer thereof by reacting with a dicarboxylic acid mainly containing an aromatic dicarboxylic acid and / or an ester-forming derivative thereof, a known method can be adopted. When the obtained polycarboxylic acid glycol ester of dicarboxylic acid and / or its low polymer is further polycondensed, a known method and apparatus can be adopted, but at this time, it is necessary to perform polymerization under stirring at a shear rate of 10 sec ^-1 or more. is there. Below this, it is not possible to obtain the low-oligomer polyester which is the effect of the present invention. For that purpose, it is important to control the stirring speed and the gap between the stirring blade and the inner wall.

The amount of oligomers extracted from the polyester obtained by the production method of the present invention is preferably 1.0% or less. When the characteristic value is within the above range, for example, the surface smoothness when formed into a film is excellent and preferable. It is more preferably 0.7% or less, still more preferably 0.5% or less.

When a film made of polyester obtained by the production method of the present invention is produced, the film can be applied to either a single layer or a laminated layer, but the running property and the surface smoothness of the film can be carried out on different sides. A laminated film composed of two or more layers is particularly preferable, and when the polyester film obtained by the production method of the present invention is applied to at least one layer, particularly to three or more laminated films, at least one of the laminated films is used. It is preferably the outermost layer. When a layer containing various particles is provided in order to improve the slipperiness of the film, the layer is preferably at least one of the outermost layers, and from the viewpoint of abrasion resistance, the film layer The relationship between the thickness t and the particle diameter d of the contained particles is preferably 0.2d ≦ t ≦ 10d, more preferably 0.5d ≦ t ≦ 5d, and further preferably 0.5d ≦ t ≦. 3d.

Next, a method for producing a laminated film having a layer made of the polyester of the present invention will be described. Pellets consisting of polyester obtained by the production method of the present invention and, if necessary, after drying pellets containing a predetermined amount of particles, supplied to a known melt lamination extruder,
An unstretched film is produced by extruding a sheet from a slit die and cooling and solidifying it on a casting roll.
That is, two or three extruders, two or three layers of manifolds or merging blocks are used to laminate the polyester in a molten state. In this case, a method of installing a static mixer and a gear pump in the flow path of the polymer containing particles is effective in further improving the effect of the present invention. Next, this unstretched film is biaxially stretched and biaxially oriented. As a stretching method, a sequential biaxial stretching method or a simultaneous biaxial stretching method can be used. However, using a sequential biaxial stretching method in which stretching is first performed in the longitudinal direction and then in the width direction, the stretching in the longitudinal direction is divided into three or more steps, and the longitudinal stretching temperature is 500 to 170 ° C. and the total longitudinal stretching ratio is 3.0. ~ 8.0
The double and longitudinal stretching speeds are preferably in the range of 5,000 to 50,000% / min. As a stretching method in the width direction, a method using a stenter is preferable, the stretching temperature is 50 to 170 ° C., the stretching ratio in the width direction is 3.0 to 8.0 times, and the stretching speed in the width direction is 100.
The range of 0 to 20000% / min is preferable. Further, it is also preferable to stretch in the machine direction or subsequently in the transverse direction.
Next, this stretched film is heat-treated. In this case, the heat treatment temperature is preferably 100 to 250 ° C. and the time is preferably 0.5 to 60 seconds.

The coarse protrusions number of the laminate surface using a polyester obtained by the process of the present invention in the film obtained as above is preferably from 100/100 cm ² or less, and more is 70/100 cm ² or less preferable. More preferably, it is 50 pieces / 100 cm ² or less.

[0017]

EXAMPLES The present invention will be described in detail below with reference to examples. The characteristic values of the obtained polyesterm were determined according to the following methods.

(1) Amount of Oligomers Extracted The polymer was pulverized to a size of 20 mesh to 35 mesh, and then 20 times with chloroform using a Soxhlet extractor.
The amount of chloroform-soluble components extracted by time was determined as a ratio (% by weight) to the polymer used for extraction.

(2) Number of Coarse Protrusions on the Film Surface Two measurement surfaces (100 cm ² ) of the film are superposed and brought into close contact with each other by electrostatic force (applied voltage 5.4 kV).
The height of the coarse protrusions was determined from the Newton's ring caused by the interference of the light of the coarse protrusion between the two films, and the coarse protrusions of one ring or more were counted. 10 because two sheets are stacked
It means that 200 cm ^{2 is} measured with the sample film of 0 cm ² . The light source used was a halogen lamp with a 564 nm bandpass filter.

(3) Sliding property of the film The film was slit into a width of 1/2 inch, and a tape running tester TBT-300 type [manufactured by Yokohama System Laboratory Co., Ltd.] was used.
Was run in an atmosphere of 20 ° C. and 60% RH, and the initial coefficient of friction μk was determined from the following formula. The guide diameter is 6 mmφ, the guide material is SUS27 (surface roughness 0.2S), the winding angle is 180 ° C., and the traveling speed is 3.3 cm / sec. μk = 0.733 × log (T ₁ / T ₂ ) T ₁ : Outlet tension T ₂ : Inlet tension

Example 1 In a transesterification reactor equipped with a stirrer, a rectification column and a condenser, dimethyl naphthalene-2,6-dicarboxylate 65.8.
Part, ethylene glycol 33.5 parts and manganese acetate tetrahydrate 0.08 part were gradually heated to 170 ° C. to 240 ° C. and simultaneously produced methanol was continuously distilled out of the reaction system. A transesterification reaction was performed. To the thus obtained reaction product, 0.04 part of trimethyl phosphate was added and reacted for 15 minutes, then 0.03 part of antimony trioxide was added and further reacted for 5 minutes.

Subsequently, while continuously distilling ethylene glycol, the temperature was raised to 290 ° C. and 0.2 mmH
The polycondensation reaction was carried out by advancing the reduced pressure to g.
A shear rate of 5 sec ^-1 was established between the stirring blade and the inner wall. The intrinsic viscosity of the obtained polyester is 0.65
The amount of oligomer extracted was 0.3%. Let this polymer be A.

On the other hand, polyethylene-2,6-naphthalate (hereinafter referred to as polymer B) containing silica particles of 0.5 μm was obtained by a known polymerization method. After drying the two polymers under reduced pressure, the polymers A and B were respectively supplied to the extruder 1 and the extruder 2 and melted, followed by high-precision filtration, and then two layers were laminated at the rectangular confluence portion. This was wound around a casting drum by an electrostatically applied casting method and cooled and solidified to prepare an unstretched film. This unstretched film was stretched 5.0 times in the longitudinal direction and 6.0 times in the width direction and heat-treated to obtain a biaxially oriented laminated film having a total thickness of 15 μm. When the characteristics of this film were examined, the number of coarse protrusions on the surface of the laminated part using the polyester obtained by the production method of the present invention was 24.
The number of particles / cm ² was small and the surface properties were good, and μk of the laminated surface containing the silica particles was 0.32, which was a good running property.

Example 2 26.3 parts of dimethyl terephthalate, 39.5 parts of dimethyl 4,4'-biphenyldicarboxylate and 33.5 parts of ethylene glycol were placed in a transesterification reactor equipped with a stirrer, a rectification column and a condenser. And 0.08 part of manganese acetate tetrahydrate were gradually heated to 170 ° C. to 240 ° C., and simultaneously produced methanol was continuously distilled out of the reaction system to carry out transesterification reaction. To the reaction product thus obtained, 0.04 part of trimethyl phosphate was added and reacted for 15 minutes, and then 0.03 part of antimony trioxide was added,
The reaction was continued for 5 minutes.

Subsequently, while continuously distilling ethylene glycol, the temperature was raised to 290 ° C. and 0.2 mmH
The pressure was reduced to g and the polycondensation reaction was carried out.
A shear rate of 5 sec ^-1 was established between the stirring blade and the inner wall. The intrinsic viscosity of the obtained polyester is 0.71.
The amount of oligomer extracted was 0.4%. Let this polymer be C.

On the other hand, a polymer D having a composition similar to that of the polymer C and containing silica particles of 0.5 μm was obtained by a known polymerization method. After vacuum drying the two polymers,
Polymers C and D were respectively supplied to the extruder 1 and the extruder 2 and melted, followed by high-precision filtration, and then two layers were laminated at the rectangular confluence portion. This was wound around a casting drum by an electrostatically applied casting method and cooled and solidified to prepare an unstretched film. This unstretched film was stretched 5.0 times in the longitudinal direction and 6.0 times in the width direction and heat-treated to obtain a biaxially oriented laminated film having a total thickness of 17 μm. When the characteristics of this film were examined, the number of coarse projections on the surface of the laminated part using the polyester obtained by the production method of the present invention was as small as 17 pieces / cm ² , which showed good surface characteristics and contained silica particles. The μk of the laminated surface was 0.25, indicating good runnability.

Comparative Example 1 A polyester was obtained in the same manner as in Example 1 except that the shear rate generated between the stirring blade and the inner wall was changed to 7 sec ^-1 . The oligomer extraction of this polymer was 1.3%. Further, a film was obtained in the same manner as in Example 1. When the characteristics of this film were examined, the number of coarse projections on the surface of the laminated portion using the polyester obtained under the conditions deviating from the production method of the present invention was as high as 124 / cm ² , and the particles contained silica particles. The μk of the laminated surface was 0.37, which was not good running property.

[0028]

The polyester obtained by the method of the present invention has few oligomers and has excellent surface properties when formed into a film or the like, and can be suitably used for magnetic recording medium applications and the like.

Claims (4)

[Claims] 1. A glycol ester of a dicarboxylic acid obtained by reacting a diol and / or an ester-forming derivative thereof with a dicarboxylic acid mainly containing an aromatic dicarboxylic acid and / or an ester-forming derivative thereof and / or the same. A method for producing a polyester, which comprises polycondensing a low polymer under stirring at a shear rate of 10 sec ^-1 or more when producing a polyester by polycondensation. 2. The method for producing a polyester according to claim 1, wherein the aromatic dicarboxylic acid is 2,6-naphthalenedicarboxylic acid. 3. The method for producing a polyester according to claim 1, wherein the aromatic dicarboxylic acid is a mixture of 4,4′-biphenyldicarboxylic acid and terephthalic acid. 4. The method for producing a polyester according to claim 1, wherein the diol is ethylene glycol.