JPH0326211B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a highly polymerized polyester having excellent transparency and slipperiness, which is suitable for producing films, fibers, and other molded products having excellent surface morphology. Polyester, especially polyethylene terephthalate, is a high-strength polymer with excellent crystallinity, high softening point, heat resistance, weather resistance, electrical insulation resistance, and chemical resistance, so it is used industrially for fibers, films, and molded products. It is widely used. When polyester is used in various forms in various fields, it usually depends on operability in forming processes such as melt extrusion, drawing, stretching, heat treatment, weaving, dyeing, etc.
Operability in secondary processing steps such as processed yarn processing, magnetic layer coating for film, metal deposition, cutting and finishing for molded products, and transparency in the final product. It is necessary to have easy sliding properties and a favorable surface morphology. Conventionally, catalyst additives have been studied for the purpose of improving transparency or improving slipperiness, but it has been difficult to satisfy both simultaneously. For example, in order to improve the relationship between transparency and slipperiness, alkaline earth metals are used as catalysts in the transesterification step, which is the first step in polyester production, as described in Japanese Patent Publication No. 34-5144. A method using a compound to precipitate fine particles (hereinafter referred to as internal particles) in the subsequent polycondensation reaction process, and
As described in Publication No. 24099, Japanese Patent Publication No. 43-12013, etc., fine powders of silica, alumina, calcium carbonate, kaolin, etc. (hereinafter referred to as external particles) are added during the production or molding process of polyester. Methods are known. However, when polyester is produced by the above-mentioned methods, coarse particles are generated in the polymer, the number of particles precipitated in the polymer is not constant, and the operability in the molding and processing steps becomes extremely poor. It was found that the transparency of the product was significantly reduced. On the other hand, in recent years there has been a trend toward miniaturization in the fields of capacitor element winding films and magnetic tape films for audio, video, and computer applications, and as a result, it has become essential to reduce the thickness of the polyester base film itself. It's coming. In such thin films, unless the slipperiness of the raw material polyester is improved, conventional tapes have a problem in that the winding appearance and winding characteristics of the tape are extremely poor. Furthermore, in the field of packaging films for food and the like, in addition to slipperiness, product transparency is also becoming important. In other words, in the conventional technology, when using the external particle method, the presence of coarse particles due to contamination of coarse particles or aggregation of particles may cause yarn breakage during spinning, membrane tearing during film formation,
Troubles such as so-called "Fight Eyes" may occur. ○B Transparency must be significantly reduced in order to obtain sufficient slipperiness. ○C There are drawbacks such as poor affinity with polymers and particles peeling off from molded products. On the other hand, when using the internal particle method, the above drawbacks ○A and ○C have been relatively improved, but not sufficiently, and the reality is that ○B cannot be said to have been improved yet. Ta. In other words, in the past, microparticles were present inside the polymer in order to provide operability during the yarn spinning process and film forming process, maintain transparency and slipperiness, and obtain molded products with excellent surface properties. It was thought to be impossible. The inventors of the present invention conducted intensive research to solve the above-mentioned drawbacks, and found that the esterification reaction or transesterification reaction was followed by prepolymerization, the addition of a phosphorus compound, the depolymerization of the resulting polyester low polymer, and the further The present invention was achieved by discovering that by adding a particle-forming substance and performing polycondensation again, a suitable amount of gradually fine particles can be formed. That is, the gist of the present invention is as follows. Transesterification or esterification reaction and polycondensation using terephthalic acid, a bifunctional carboxylic acid containing terephthalic acid as the main component, or its ester-forming derivative, and ethylene glycol, a glycol containing terephthalic acid as the main component, or its ester-forming derivative as raw materials. When producing polyester by reaction, the transesterification or esterification reaction is followed by prepolymerization until the intrinsic viscosity becomes 0.2 or more and 0.4 or less, and then a phosphorus compound is added to inactivate the resulting polyester low polymer. The above glycol is depolymerized in a gas atmosphere at a temperature higher than the melting point of the polyester until the intrinsic viscosity becomes less than 0.2, and then a lithium compound and a calcium compound are added and polycondensed again to complete the reaction. A method for producing a slippery polyester. Here, the intrinsic viscosity is a value measured at 20° C. using an equal weight mixture of phenol and tetrachloroethane as a solvent. By using the method of the present invention, it is possible to produce a useful polyester for obtaining improved films and other molded products that are excellent in both transparency and slip properties, and also have excellent surface properties such as surface roughness. The bifunctional carboxylic acid or its ester-forming derivative referred to in the present invention mainly refers to ester-forming derivatives such as terephthalic acid or its alkyl ester and phenyl ester.
A part of it (usually 30 mol% or less) can be added to, for example, methyl terephthalic acid, isophthalic acid, methyl isophthalic acid, diphenyl dicarboxylic acid, diphenyl sulfone dicarboxylic acid, diphenoxyethane dicarboxylic acid, naphthalene dicarboxylic acid, adipic acid, sebacic acid, It may be replaced with one or more of p-hydroxyethoxybenzoic acid or its ester-forming derivatives. In addition, glycol or its ester-forming derivative mainly refers to ester-forming derivatives of ethylene glycol such as ethylene glycol or ethylene oxide, but a portion (usually 30 mol% or less) of ethylene glycol and ester-forming derivatives thereof, such as propylene glycol and tetramethylene Glycol, triethylene glycol, diethylene glycol, polyethylene glycol, 1,4-cyclohexanedimethanol, 1,4-cyclohexanediol, 1,4
It may be replaced with one or more of aliphatic, aromatic, alicyclic diol compounds such as -hydroxyethoxybenzene, or ester-forming derivatives thereof. Any known method can be used to produce polyester from these difunctional carboxylic acids and glycols. For example, transesterification involves transesterification of dimethyl terephthalate and ethylene glycol, or addition of ethylene oxide to terephthalic acid to form bis-(β-hydroxyethyl) terephthalate and/or its lower polymer (hereinafter referred to as BHET). Alternatively, it can be produced by an esterification step and a polycondensation step in which the formed BHET is polycondensed to obtain predetermined properties. In normal cases, the two steps are carried out continuously, except in unavoidable cases such as when it is necessary to add additives between the transesterification or esterification step and the polycondensation step, or when transport is necessary. is common. That is, providing a third step between the transesterification or esterification step and the polycondensation step without any reason may promote deactivation of the catalyst, increase the concentration of diethylene glycol bonds (hereinafter referred to as DEG), The general consensus was that it was undesirable because it would cause quality deterioration such as coloring of the polymer. Regardless of this, in the present invention, by providing a prepolymerization and depolymerization step between the two steps, the opacity of the polymer is not promoted,
Furthermore, it is possible to generate an appropriate amount of fine particles necessary to obtain good slipperiness. In the prepolymerization referred to in the present invention, the intrinsic viscosity is
It is preferable to obtain a polyester low polymer having a molecular weight of 0.1 or more and 0.4 or less, more preferably 0.1 or more and 0.2 or less. If the intrinsic viscosity is less than 0.1, coarse particles are likely to be generated, and the result will be substantially the same as in the case where no prepolymerization is performed. On the other hand, if the intrinsic viscosity exceeds 0.4 during prepolymerization, the melt viscosity becomes too high, making it difficult for the phosphorus compound added in the next depolymerization step to be uniformly dispersed in the system, resulting in the formation of particles that precipitate. Both of these are undesirable as they may cause chemical reactions. In the depolymerization step of the present invention, a phosphorus compound is added as a solution or slurry of the glycol to the polyester low polymer obtained by prepolymerization in an inert gas atmosphere at a temperature higher than the melting point of the polyester, and the glycol is Depolymerization is carried out until the intrinsic viscosity is less than 0.2, preferably 0.15 or less, optimally 0.1 or less. If the intrinsic viscosity of the product resulting from depolymerization is 0.2 or more, the required amount of particles cannot be obtained. In addition, it is undesirable that the generated particles tend to be localized. The temperature during depolymerization may be at least the melting point of the polyester in the reaction system, but it should preferably be a relatively low temperature, suitably less than 300°C. If the depolymerization temperature is too high, particle formation tends to be inhibited, which is undesirable. If an insoluble particle-forming substance is added at a time other than the depolymerization step in the present invention, that is, at the transesterification or esterification step and the polycondensation step, although particle formation is observed, coarse particles are likely to be formed. Furthermore, it is difficult to control the particles formed. In the method of the present invention, after prepolymerization, the phosphorus compound is added, the particles are depolymerized once, and then the particle-forming substance is added, and almost no particle formation is observed, but when the polymerization is started again, the particles gradually become smaller. generate. Additionally, surprisingly, the particles produced were very fine, and no coarse particles were produced.
An appropriate amount can be produced in proportion to the added phosphorus compound. If the prepolymerization and depolymerization steps in the present invention are omitted and phosphorus compounds, lithium compounds, and calcium compounds are added to BHET, particles will be generated all at once, making it easier to generate coarse particles or causing polycondensation again. This is not preferable because the particles may aggregate. In addition, it is necessary to add phosphorus compounds after prepolymerization and before depolymerization, and if phosphorus compounds are added at the same time as lithium and calcium compounds after depolymerization, the phosphorus compounds will not be uniformly dispersed and coarse particles will form. do. Examples of the phosphorus compound used in the present invention include the following. Namely, phosphoric acid, phosphorous acid, phosphoric acid mono-n-butyrate, phosphoric acid di-n-butyrate, phosphoric acid mono-n-diisopropylate, phosphoric acid diisopropylate, phosphoric acid monooctylate, phosphoric acid dioctylate, etc. can be mentioned. The amount added is per mole of the total acid component of the raw material.
The amount is preferably 10×10 ⁻⁴ to 100×10 ⁻⁴ mol.
If the amount of phosphorus compound is less than this range, particles will not be formed in an amount sufficient to impart sufficient slipperiness, while if it is more than this range, the amount of particles will be too large and may impair transparency or cause the DEG in the polymer to become too large. If the proportion becomes too high, the melting point of the polymer may decrease, which is undesirable. Calcium compounds used in the present invention include, for example, calcium salts of carboxylic acids, such as calcium acetate, calcium benzoate, and calcium stearate, with calcium acetate being preferred. Examples of the lithium compound used in the present invention include lithium acetate, lithium chloride, and lithium carbonate, with lithium acetate being preferred. If the amount of calcium compounds and lithium compounds added is small, it will not be possible to form enough particles to provide good operability in the silk-spinning and film-forming processes that are the objectives of the present invention, and if they are too large, the transparency of the polymer will be impaired. This is undesirable as it may cause the particles to agglomerate. The amount added is preferably 0.1 to 1.5 times the molar amount of the phosphorus compound. Further, as the form of addition, a glycol slurry or solution is preferable. The present invention will be explained in detail with reference to Examples below. Each characteristic value in the examples was measured by the following method. (Intrinsic viscosity of polymer) Measured at 20°C using an equal weight mixture of phenol and tetrachloroethane as a solvent. Note that the polymer was dissolved at 100°C, and the viscosity was measured after cooling to 20°C. (Solution haze) Add 2.86 g of polymer to 20 ml of an equal weight mixture of phenol and tetrachloroethane, dissolve at 105°C, and then dissolve 10 ml.
The haze value was measured using a DC haze computer HGM-30 (Suga Test Kikai Co., Ltd.). (Method for observing particles) 2.5 to 3 mg of the polymer was sandwiched between prepared plates heated to 290°C, and melt-pressed to obtain a flaky sample, which was observed using a phase contrast microscope. (Transparency of molten polymer) 1, 2, 3, 5, 10, 20, separately prepared,
The transparency of the molten polymer was visually compared with a standard polymer sample containing titanium oxide particles at 30, 40, and 50 ppm, and the transparency was expressed as the equivalent concentration of titanium oxide in the standard polymer sample, which was observed to have the same transparency as the molten polymer. (Friction coefficient of film) A 2.5μ biaxially stretched film was produced from a polymer, and tested using a Shimadzu universal testing machine to test ASTM-D-
Measured according to the 1894B method. The coefficient of static friction was used as a measure of the slipperiness of the film. (Observation of the surface of the film) Al was deposited on the surface of the film, and a photograph was taken and observed using a surface microscope manufactured by Olympus. Example 1 Bis-(β-hydroxyethyl) terephthalate and its low polymer (BHET) were produced from terephthalic acid (TPA) and ethylene glycol (EG) by a known method. The esterification reaction rate of this product was 96%, and the intrinsic viscosity was 0.10.
To 100 g of this product, 2×10 ^-4 mol of antimony trioxide was added as a polycondensation catalyst per 1 mol of raw material TPA.
Add 2ml of solution to the reaction system, start reducing pressure at 270°C, and perform polycondensation at 10 torr for 30 minutes until the intrinsic viscosity is 0.22.
of product was obtained. Then, the pressure was returned to 760 torr with N ₂ gas, and 50×10 ^-4 phosphoric acid was added to 1 mole of raw material TPA.
Add 10 ml of EG solution to the reaction system and add 270 mol of EG solution.
Depolymerization was performed at ℃ for 15 minutes to obtain a product with an intrinsic viscosity of 0.09. In addition, 40% of lithium acetate per mole of raw material TPA
×10 ^-4 mol and calcium acetate 20 × 10 ^-4 mol were added to the reaction system as a total of 8 ml of EG solution, and 285
The temperature was gradually raised to 0.1 Torr and the pressure was reduced to carry out a polycondensation reaction for a total of 2 hours. The final polymer has an intrinsic viscosity of 0.66
It was hot. Further, when the obtained polymer was observed using a phase contrast microscope using the above-mentioned particle observation method, uniform particles with a particle size of about 1 μm were observed, and there were no coarse particles with a particle size of 10 μm or more. Furthermore, the melt polymer clarity of this polymer is 10 ppm, and the solution haze is 42.3.
%, and the polymer had an appropriate amount of particles. The biaxially stretched film produced from this polymer had a coefficient of static friction of 0.53, and was excellent in slipperiness, and the surface condition was also good as seen from observation of photographs of the film surface. Comparative Example 1 After the esterification reaction, a phosphorus compound, a lithium compound, and a calcium compound were added and reacted in the same manner as in Example 1 without performing prepolymerization and depolymerization to obtain a polymer with an intrinsic viscosity of 0.68. When the obtained polymer was observed using a phase contrast microscope in the same manner as in Example 1, it was found that particles of 1 μ to 3 μ were unevenly present, and some particles were larger than 10 μ. The solution haze of this polymer was 59.7%, and the molten polymer transparency was 30 ppm, indicating that the polymer had poor transparency. A biaxially stretched film made from this polymer had a coefficient of static friction of 0.70 and had good slipperiness, but when a photograph of the film surface was observed, the surface was uneven and uneven and the surface condition was not good. Example 2 The reaction was carried out in the same manner as in Example 1, except that 60 x 10 ^-4 mol of lithium acetate and 10 x 10 ^-4 mol of calcium acetate were added to 1 mol of raw material TPA, and the results shown in Table 1 were obtained. Example 3 The reaction was carried out in the same manner as in Example 1, except that 30 x 10 ^-4 mol of lithium acetate and 30 x 10 ^-4 mol of calcium acetate were added to 1 mol of raw material TPA, and the results shown in Table 1 were obtained. Example 4 Phosphoric acid 30×10 ^-4 mol, lithium acetate 40×10 ^-4 mol, calcium acetate 30× for 1 mol of raw material TPA
The reaction was carried out in the same manner as in Example 1, except that 10 ^-4 mol was added, and the results shown in Table 1 were obtained. 【table】

Claims (1)

[Claims] 1. Transesterification using terephthalic acid, a bifunctional carboxylic acid containing terephthalic acid as a main component, or an ester-forming derivative thereof, and ethylene glycol, a glycol containing terephthalic acid as a main component, or an ester-forming derivative thereof as raw materials. Alternatively, when producing polyester by esterification reaction and polycondensation reaction, following transesterification or esterification reaction, prepolymerization is performed until the intrinsic viscosity becomes 0.2 or more and 0.4 or less, and then a phosphorus compound is added,
The resulting polyester low polymer is depolymerized using the above glycol at a temperature higher than the melting point of the polyester in an inert gas atmosphere until the intrinsic viscosity becomes less than 0.2, then a lithium compound and a calcium compound are added, and then the polyester is depolymerized again. A method for producing a slippery polyester, which comprises completing the reaction by polycondensation. Here, the intrinsic viscosity is a value measured at 20° C. using an equal weight mixture of phenol and tetrachloroethane as a solvent.