JPH0365816B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a method for producing polyester having excellent surface properties and excellent slipperiness. Specifically, we use high-polymerized polyester that has excellent moldability when molded into fibers, films, and other molded products, and has excellent transparency, slipperiness, and surface morphology as a product after molding. The present invention relates to a method for manufacturing with high productivity in a short period of time. B. Prior art and its problems Polyester, which is used industrially today,
In particular, polyethylene terephthalate has high crystallinity, high softening point, strength, chemical resistance, heat resistance,
Because it has excellent properties in terms of weather resistance and electrical insulation, it is widely used industrially for fibers, films, and molded products. Generally, when polyester is used in various industrial fields, it is usually difficult to operate in forming processes such as melt extrusion, drawing, stretching, and heat treatment, or in the case of weaving, dyeing, processed yarn processing, or film production.
Operability in secondary processing processes such as magnetic layer coating, metal vapor deposition, cutting and finishing when molded products are made, and transparency, slipperiness, and favorable surface morphology when the final product is made. is needed. Conventionally, catalysts and additives have been developed and improved for the purpose of improving transparency or improving slipperiness, but it has been difficult to satisfy both at the same time. As a method for improving the transparency and slipperiness, for example, as seen in Japanese Patent Publication No. 34-5144,
There is a method in which an alkaline earth metal compound is used as a catalyst in the transesterification reaction step, which is the first step in the production of polyester, and fine particles (hereinafter referred to as internal particles) are precipitated in the subsequent polycondensation reaction step. Are known. However, when polyester is produced by this method, coarse particles are generated in the produced polyester, and the number of internal particles produced is not constant, which significantly impairs operability in molding and processing steps. However, it had the disadvantage of significantly reducing the transparency of the product. On the other hand, in the field of films for winding capacitor elements and films for various magnetic tapes, there has been a noticeable trend in recent years to reduce the thickness of the films, and as a result, it has become necessary to reduce the thickness of the polyester base film itself. . In such thin films, a problem has arisen in that unless the lubricity of the raw material polyester is further improved, the tape winding appearance and winding characteristics will be extremely poor. As a method to improve the above problem, for example, as described in Japanese Patent Application Laid-open No. 54-90397, a phosphorus compound is added when the esterification reaction rate reaches 91 to 99%, and the reaction is continued for a certain period of time. A method of adding a lithium compound or a lithium compound and a calcium compound after melting and holding, and a method of adding ethylene glycol before adding a particle-forming substance as described in JP-A-54-113696 have been proposed. However, the improvement effect is insufficient. That is, in the former case, the esterification product bis-(β-hydroxyethyl) terephthalate and/or its low polymer and the phosphorus compound have a low melting retention temperature, and when the phosphorus compound and other additives are added, There is a drawback that coarse particles are likely to be generated due to temperature changes, and in the latter case, there is also a drawback that the amount of particles generated will be insufficient unless the particle-forming substance and ethylene glycol are added substantially simultaneously. This tendency was particularly noticeable when phosphoric acid was used as the phosphorus compound, and the improvement effect was unsatisfactory. As a method to solve the above drawback, as described in Japanese Patent Application Laid-Open No. 59-64626, which was previously proposed by the present inventors, when the esterification reaction rate reaches 90% or more, the concentration is reduced to 1. Add a glycol solution of phosphoric acid with a concentration of ~10 mol/ml, stir and mix at 270 to 290°C for 5 minutes or more, then add a glycol solution of a particle-forming substance, and add a catalyst at the same time or immediately before polycondensation to perform polycondensation. There is a way to do it. However, even with this method, the following problems still remain. In other words, when a catalyst is added at the same time as a particle-forming substance, a polyester with fine particles and good transparency and slipping properties can be produced, but the polycondensation catalyst activity is weak and it is difficult to produce a highly polymerized polyester in a short time. There was a problem with productivity as it was impossible to do so. Furthermore, if the catalyst is added just before the start of the polycondensation reaction, the polycondensation catalyst activity will be sufficient and a polyester with a high degree of polymerization can be obtained, but on the other hand, it will have the disadvantage of producing coarse particles, which may cause undesirable phenomena. C. Purpose of the Invention The present invention provides a method for producing easily slippery polyester without such problems, that is, a method for producing polyester with a high degree of polymerization in an extremely short period of time, and which has excellent transparency, slipperiness, and surface properties when made into a product. It is an object of the present invention to provide a method for producing polyester having a shape. D. Structure of the Invention The present invention achieves the above object, and the gist thereof is as follows. When producing polyester by esterification reaction and polycondensation reaction using terephthalic acid and ethylene glycol as the main starting materials, when the esterification reaction rate reaches 90% or more, the produced bis-(β-hydroxyethyl) Terephthalate and/or its low polymer (hereinafter referred to as BHET)
An ethylene glycol solution of phosphoric acid with a concentration of 1 to 10 mol/mole was added in an amount such that phosphoric acid was 0.001 to 0.01 mol per 1 mol of the acid component constituting the polyester, and then heated at a temperature of 240 to 290°C for 50 minutes. Stir and mix for at least 5 minutes, then add the lithium compound, calcium compound, and antimony compound as the primary addition catalyst, stir and mix again at a temperature of 240 to 290°C for 5 minutes or more, and then add the antimony compound as the secondary addition catalyst. This is a method for producing easily slippery polyester, which is characterized by completing the polycondensation. The esterification method in the present invention is usually carried out by continuously supplying a slurry of terephthalic acid (hereinafter referred to as TPA) and ethylene glycol (hereinafter referred to as EG) to an esterification reaction tank in which BHET is present. The so-called direct esterification method is used. The above BHET may partially contain components other than TPA residues and EG groups. Further, BHET may be obtained by any known method, but it is preferable to use the BHET obtained by the above method as is. Rather, the TPA and EG slurry contains other acid components, such as isophthalic acid, adipic acid, sebacic acid, 5-sodium sulfoisophthalate, etc., and other glycol components, such as tetramethylene glycol, neopentyl glycol, 1, 4-
Cyclohexane dimethanol or the like may be contained to an extent not exceeding 30 mol%. Esterification is carried out in this way, and when the esterification reaction rate reaches 90% or more (at this point, no unreacted
It is necessary to add an EG solution of phosphoric acid with a concentration of 1 to 10 mol/ml (no TPA particles will disappear) and stir and mix at 240 to 290°C for 5 minutes or more. The stirring and mixing temperature of phosphoric acid and BHET is preferably 240°C or higher, as the diameter of the particles produced will be smaller, but if it exceeds 290°C, diethylene glycol (hereinafter referred to as DEG) will increase and the physical properties will be impaired. This is not desirable. In addition, when polycondensing polyester, additives are usually added as an EG solution, but
This is to improve the dispersion and mixing of the additives within the reaction system, and to suppress the formation of high melting point gels due to local reactions of the additives. In the present invention, phosphoric acid must be added at a time when the esterification reaction rate reaches 90% or more. If phosphoric acid is added when the esterification reaction rate is less than 90%, coarse particles will be generated, which is undesirable. The amount of phosphoric acid added needs to be 0.001 to 0.01 mol per mol of the acid component constituting the polyester. In other words, if the amount of phosphoric acid added is less than 0.001 mole per mole of the acid component, the amount of internal particles generated will be insufficient, and conversely, if the amount added exceeds 0.01 mole, coarse particles will be generated or transparency will be reduced. It is not desirable as it may cause significant damage. It is important to add phosphoric acid in the form of an EG solution having a concentration of 1 to 10 mol/, preferably 3 to 7 mol/. If the concentration of phosphoric acid added is less than 1 mol/mol, it is not preferable because the amount of particles produced is so small that the desired slippery polyester cannot be obtained. On the other hand, if the concentration exceeds 10 mol/mol, the resulting polyester may be colored yellow or coarse particles may be generated, which is also undesirable. In the present invention, the stirring and mixing time after adding the phosphoric acid to the EG solution must be 5 minutes or more. That is, if the lithium compound and the calcium compound are added for less than 5 minutes, coarse particles will be generated, causing problems. As described above, the stirring and mixing time may be 5 minutes or more, but in order to suppress the generation of DEG, it is preferably 60 minutes or less, and optimally 30 minutes or less. Then add lithium compound, calcium compound and antimony compound and further add 240-290
The esterification product and the particle-forming substance are reacted by stirring and mixing at a temperature of 50°C for 5 minutes or more, and then the polycondensation catalyst is added again to complete the polycondensation reaction. As the lithium compound used in the present invention, lithium salts of carboxylic acids such as lithium acetate, lithium chloride, lithium carbonate, lithium sulfate, etc. can be used, and lithium acetate is preferred. Further, the amount of the lithium compound added is preferably 0.5 to 2.0 times the amount of the phosphoric acid added. If the amount added is less than 0.5 times equivalent, coarse particles will be formed in the produced polyester, which is not preferable. On the other hand, adding more than 2.0 times the equivalent does not substantially increase the effect and only increases the cost.
It is disadvantageous. Examples of the calcium compound used in the present invention include calcium stearate, calcium benzoate, calcium acetate, calcium carbonate, and calcium chloride, with calcium acetate being preferred. Further, the amount of the calcium compound added is usually 0.1 to 1.0 times the amount of the phosphoric acid added. If the amount added is less than 0.1 times equivalent, the effect of addition will not be exhibited substantially, while if it is added in an amount exceeding 1.0 times equivalent, coarse particles will be generated, both of which are undesirable. Examples of the antimony catalyst used in the present invention include antimony trioxide, antimony acetate, and antimony glycolate, but antimony trioxide is suitable because it is easy to handle and is inexpensive. It is preferable that the lithium compound and calcium compound, which are particle-forming substances in the present invention, and the primary addition polycondensation catalyst are added at the same time. If the catalyst is added later than the addition of the lithium compound or calcium compound, it is undesirable because particles tend to become coarse, and if the antimony compound is added first, coarse particles are likely to be generated, which is undesirable. Further, the timing of adding the secondary addition catalyst is preferably 5 minutes or more, preferably 10 to 30 minutes after the lithium compound, calcium compound and primary addition catalyst have been added at 240 to 290°C. If the secondary catalyst is added within 5 minutes after the addition of the particle-forming substance and the primary catalyst, the reaction time between the esterification product and the particle-forming substance will not be sufficient, so the secondary catalyst will contribute to particle formation, and the catalyst will Not only does it make no sense to carry out the addition in two stages, but it is also undesirable because the particle size becomes non-uniform, and if the secondary addition catalyst is added after 30 minutes or more and the polycondensation reaction is carried out, by-products will be added to the polyester. Not only is this undesirable because the amount of DEG, which is a generated component, increases, but it is also undesirable because it impairs the advantage of being able to produce polyester with a high degree of polymerization in a short period of time, which is the objective of the present invention. The amount of the primary catalyst added in the present invention is usually 0.5 x 10 ^-4 to 4 x mol of antimony metal atoms per mol of the acid component constituting the polyester.
10 ^-4 mol is added. If the amount added is less than 0.5×10 ⁻⁴ mol, the effect of making the particles finer during the formation of internal particles will be small and undesirable. Also, 4×
Adding more than 10 ^-4 mol of an antimony compound only unnecessarily increases the particle size of the internal particles produced, which not only hardly contributes to the activation enhancement effect, but also makes the internal particles produced non-uniform. This is not preferable, and the polyester becomes dull, which is characteristic of antimony catalysts, resulting in poor color tone. The amount of secondary catalyst added is preferably 1 x 10 ^-4 to 6 x 10 ^-4 mol based on the acid component constituting the polyester, and if it is less than 1 x 10 ^-4 mol, it is insufficient to compensate for the catalytic activity of the polycondensation reaction. If the amount exceeds 6×10 ^-4 mol, the color tone will deteriorate significantly due to the dullness characteristic of antimony catalysts, and the activation effect will reach a plateau. Furthermore, a particularly preferable range of the amount of catalyst added is a range in which the amount of primary catalyst added (A) and the amount of secondary catalyst added (B) satisfy the following formula. 2/1<A/B<1/2 (However, A and B are the number of moles of the antimony catalyst added primarily and secondarily to 1 mole of the acid component constituting the polyester.) Outside the range of the above formula In some cases, an imbalance occurs between the particle forming ability of the primary added catalyst and the productivity improvement ability of the secondary added catalyst, resulting in the various problems described above, which may be undesirable. E Effects of the invention Next, the effects of the invention will be explained. The principle of the invention is as follows. In other words, when producing a slippery polyester with excellent transparency, slipperiness, and surface morphology by the internal particle method, when cheap phosphoric acid is used as a glycol solution as a phosphorus compound, the antimony catalyst is used as a particle-forming substance. Highly polymerized with excellent slipperiness and transparency by forming fine particles by completing polycondensation by adding the primary and secondary components at the time of addition and at least 5 minutes later. Polyester can be produced in a short period of time with high productivity. That is, by including an antimony catalyst in the reaction between the esterification product and the lithium compound or calcium compound that is a particle-forming substance, uniform and fine particles can be stably formed. However, since it is involved in the formation of internal particles of the antimony catalyst, even if the amount of catalyst is increased in the primary addition, hardly any enhancement of polycondensation catalyst activity is observed. However, if the antimony catalyst is secondarily added after the reaction between the esterified product and the particle-forming substance is completed, that is, at least 5 minutes have passed after the first addition of the catalyst, the second-added catalyst will have no polymerization activity. This greatly contributes to the As a result, the polycondensation reaction time is shortened to about 1/2 to 2/3 of the conventional method, and the low productivity, which was a drawback of the conventional internal particle method, can be significantly improved, which has a large economic effect. It is something. F. Examples Hereinafter, the method of the present invention will be explained in more detail with reference to Examples. In the examples, "parts" indicate "parts by weight." In addition, each characteristic value was measured by the following method. The transparent slippery polyester preferably has a solution haze of about 20 or more, has good transparency of the molten polymer, and does not contain large particles. (1) Intrinsic viscosity of polymer [η] It was determined from the solution viscosity measured at 20°C using a mixed solvent of equal weights of phenol and tetrachloroethane. (2) Solution haze Precisely weigh 2.86 g of polymer, add 20 ml of an equal weight mixture of phenol and tetrachloroethane to it, heat it, and then place it in a quartz glass cell with a transmission length of 10 mm.
It was measured using a direct reading haze computer manufactured by Suga Test Instruments Co., Ltd. (3) Melt polymer transparency Polymer transparency was evaluated as follows. Phthalic anhydride/maleic anhydride (molar ratio 1/
1) and a mixture consisting of 49% by weight of a condensate of ethylene glycol/propylene glycol (molar ratio 1/1) and 51% by weight of styrene monomer,
Titanium dioxide fine powder 0.5, 1, 2, 3, 4,
5, 10, 15, 20, 25, 30, 35, 40, 45, 50ppm
Disperse, add 1% by weight of benzoyl peroxide to the mixture, and solidify by reacting at 40 to 60°C for about 4 hours to obtain a standard polymer composition (a standard polymer composition with a titanium dioxide content of 0 ppm is transparent). is in very good condition). The transparency of this standard polymer composition and the sample molten polymer were visually compared, and the titanium dioxide content of the standard polymer composition with the closest transparency was taken as the transparency of the sample polymer. (4) Particle size A sample of 25 to 3 mg is sandwiched between two preparations heated to 270°C, melt-pressed, and then rapidly cooled. This was visually observed using a 200x phase contrast microscope.
They were divided into the following five ranks based on their size. Rank A: There are no particles larger than 1μ. Rank B: No particles larger than 3μ. Rank C: No particles larger than 5μ. Rank D: No particles larger than 10μ. Rank E: There are particles of 10μ or more. (However, rank B or higher is considered good.) Reference example 1 TPA and BHET are added to the esterification reaction tank.
A slurry of EG (EG/TPA molar ratio = = 1.6) was continuously supplied and reacted at 250°C under normal pressure, and the residence time was adjusted to 6 hours to continuously produce an esterified product with a reaction rate of 95%. I got it. Example 1 100 parts of BHET obtained in Reference Example 1 (no unreacted TPA particles) was transferred to a polymerization tank, heated to 285°C, and 8 x 10 ^-3 mol of phosphoric acid was added to EG for 1 mol of acid component. 5
Added as a solution of mol/ml and incubated at 285 °C for 10 min.
Stir and mix under _N2 atmosphere. After that, 80×10 ^-4 mol and 24×10 ^-4 mol of lithium acetate and calcium acetate were added to 1 mol of the acid component, respectively.
At the same time, 2 x 10 ^-4 mol of antimony trioxide was added per 1 mol of the acid component (hereinafter referred to as primary catalyst addition) and the mixture was stirred for 10 minutes. After that, 2 × × 10 ^-4 mol of antimony trioxide was added per 1 mol of the acid component (hereinafter referred to as secondary addition of catalyst), the pressure was gradually reduced to 0.1 mmHg, and the target viscosity was reached at 285°C. Polycondensation was carried out until [η]=0.70. The polycondensation reaction time was 1 hour and 40 minutes, and the solution haze was 52.8
%, the transparency of the molten polymer was 8 ppm, and the particle size was A rank. Examples 2 and 3 The reaction was carried out in the same manner as in Example 1, except that the timing of catalyst addition and the amount of catalyst were changed, and the results shown in Table 1 were obtained. Comparative Examples 1 and 2 The reaction was carried out in the same manner as in Example 1, except that the amount of catalyst added in the primary addition was changed and the catalyst was not added secondary, and the results shown in Table 1 were obtained. In Comparative Example 1, the polycondensation time was very long and the productivity was very poor. Comparative Example 3 The primary addition amount of catalyst was 4×10 ^-4 mol/mol of acid component,
The reaction was carried out in the same manner as in Example 1, except that the addition time was 10 minutes after the addition of the lithium compound and the calcium compound, and the secondary addition of the catalyst was not performed, and the results shown in Table 1 were obtained. Comparative Example 4 The reaction was carried out in the same manner as in Example 1, except that the first addition of the catalyst was before the addition of the lithium compound and the calcium compound, and the second addition of the catalyst was immediately after the addition of the particle-forming substance, and the results shown in Table 1 were obtained. I got it. Comparative Example 5 The reaction was carried out in the same manner as in Example 1, except that the timing of primary catalyst addition and the amount of catalyst added were changed, and the results shown in Table 1 were obtained. 【table】

Claims (1)

[Scope of Claims] 1. When producing polyester by esterification reaction and polycondensation reaction using terephthalic acid and ethylene glycol as the main starting materials, the product produced when the esterification reaction rate reaches 90% or more. An ethylene glycol solution of phosphoric acid having a concentration of 1 to 10 mol/bis-(β-hydroxyethyl) terephthalate and/or its low polymer is added to 1 mol of the acid component constituting the polyester, at a concentration of 0.001 to 10 mol/mol of phosphoric acid. Add an amount of 0.01 mol,
After that, the mixture is stirred at a temperature of 240 to 290°C for 5 minutes or more, and then the lithium compound, calcium compound,
and an antimony compound as a primary addition catalyst, stirred again at a temperature of 240 to 290°C for 5 minutes or more,
A method for producing an easily slippery polyester, which comprises subsequently adding an antimony compound as a secondary addition catalyst to complete the polycondensation reaction. 2. The method for producing a slippery polyester according to claim 1, wherein the amounts of the primary addition catalyst (A) and the secondary addition catalyst (B) satisfy the following formulas () to (). 0.5×10 ^-4 ≦A≦4×10 ^-4 () 1×10 ^-4 ≦B≦6×10 ^-4 () 1/2<A/B<2/1 () (However, A and B are (This is the number of moles of the antimony catalyst added primarily and secondarily to 1 mole of the acid component constituting the polyester.)