JPH0141168B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a method for producing polyester containing a large amount of particles and a small content of coarse particles. The present invention relates to a method for producing polyester, which allows molded articles with improved slipperiness, opacity, and surface condition to be obtained. [Prior Art] Polyester in general, and polyethylene tereftate in particular, has excellent mechanical properties, heat resistance, weather resistance, electrical insulation, and chemical resistance, so it is used for textiles for clothing and industrial use, as well as films for magnetic tapes and photographic films. Widely used in film fields such as , electrical insulation, and capacitor films. When polyester is used in the film field, it must be passed through the molding processes of melt extrusion, stretching, and heat treatment, or during film molding, winding, cutting, surface coating of magnetic layers, etc., and incorporation into electrical components are important. Considering the value of the final product, such as stability, slippage of film products, and opacity, we created a polyester composition containing fine particles, which gave the surface an appropriate amount of unevenness to give it smoothness and improve the surface slipperiness during film formation. It is common practice to facilitate film flow and to make the film opaque. Polyester compositions containing such fine particles include polyesters obtained by adding and blending inert insoluble inorganic particles such as silicon oxide, titanium dioxide, calcium carbonate, talc, and clay, and catalyst components used during polyester synthesis. ,
Polyesters obtained by precipitating part or all of a coloring inhibitor as fine particles during a polymerization reaction process are known. However, such conventionally known fine particle-containing polyesters have the following problems, and especially when molded into a film, slipperiness, opacity, surface condition, film formability, etc. are not satisfactory. That is, in the above-mentioned so-called external particle-containing polyester composition, it is difficult to make the additive particles finer, coarse particles are mixed together due to agglomeration of particles, and the particle size is non-uniform, as well as the affinity between the particles and the polyester. There are drawbacks such as falling off due to lack of properties, and tears occur during film formation during molding.Also, when made into a film, coarse protrusions caused by coarse particles are mixed in, causing problems such as sticking eyes and dropouts. There are many drawbacks, such as a decrease in electrical insulation, and furthermore, dispersants added to prevent particles from agglomerating often reduce the heat resistance and electrical insulation of these polyesters. On the other hand, the polyester obtained by the so-called internal particle method described above has a small particle content, and coarse particles are likely to be generated, and it is difficult to control the particle size of the precipitated particles. The deviation between the layers is large, and when molded into a film, not only is it not possible to obtain satisfactory slipperiness and opacity, but there are also undesirable defects such as hard eyes and dropouts, making it difficult to obtain satisfactory surface characteristics. . Furthermore, if the amount of catalytic metal compound added is increased to increase the amount of particles, the amount of coarse particles mixed in will increase due to agglomeration of particles, and in batch systems, the number of coarse particles will further increase due to the influence of miscellaneous polymers. 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
79271, Japanese Patent Laid-Open No. 53-4103, etc., but 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 tapes in order to achieve miniaturization and higher density, and there is a growing demand for more uniform 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, in order to impart good surface properties to the polyester and to make a molded product with excellent slipperiness by blending it into a polyester that does not contain particles or has a small particle content, it is necessary to create a molded product that does not contain coarse particles and has a small particle content. There is a demand for raw materials containing a large amount of particles. However, the finer these internal particles are and the greater the amount of the particles, the more likely coarse particles are to be produced due to aggregation of the particles.
In addition, in the batch polymerization method, the polymer from the previous batch remains, and the decomposition of this remaining polymer and the particle aggregates in the remaining polymer have an adverse effect on the next low polymer, which causes coarse particles to form during the particle generation process. It has been found that extremely inconvenient phenomena occur, such as causing the formation of [Problems to be Solved by the Invention] The purpose of the present invention is to address the problems of the prior art, particularly the lack of particle numbers in the so-called internal particle method, and to improve the amount of catalyst added in order to increase the number of particles. The problem is that the production of coarse particles due to agglomeration of particles increases when the polymer is increased, and that when producing polymer continuously, coarse particles tend to be produced due to the influence of the polymer of the previous batch. The object of the present invention is to provide a method for producing polyester with high productivity, which has a low content of coarse particles and a large amount of fine particles. [Means for Solving the Problems] The above-mentioned object of the present invention is to produce a polyester mainly composed of polyethylene terephthalate by transesterification or esterification reaction of terephthalic acid or its ester-forming derivative with glycol and subsequent polycondensation reaction. Immediately after the transesterification reaction or esterification reaction and while the polycondensation reaction proceeds and the intrinsic viscosity of the product does not exceed 0.2, lithium compounds and phosphorus compounds are added in an amount that satisfies the following formula. A polycondensation reaction is carried out using a polycondensation reaction, and the number of particles by the measurement method defined in the text is 10 ⁴ particles/mm ² or more and 0.5 μ
A method for producing polyester, characterized by obtaining a polyester in which the ratio of the number of coarse particles of 7μ or more to the total number of particles is less than 10%. 1.2<Li<2.5 0.25<P<1.2 1.0<(1/2Li)/P<4.0 (In the formula, Li and P are the mol% of the lithium compound and phosphorus compound, respectively, based on the polyester raw acid component)
represents. ) can be achieved. Next, the present invention will be explained in detail. The number of particles and the proportion of coarse particles in the polymer referred to in the present invention are measured by the following method. A. Number of particles in the polymer 20 mg of polymer was sandwiched between two cover glasses, melt-pressed at 280℃ to a diameter of about 20 mm, rapidly cooled, and then heated using an image analyzer [luzex500
(manufactured by Nippon Regulator Co., Ltd.)] is used to count the number of particles larger than 0.5μ present in 1 mm ² by bright field method. B. Proportion of coarse particles in polymer The number of particles of 7μ or more is expressed as a percentage of the total number of particles of 0.5μ or more measured by method A. The polyester targeted by the present invention has a particle count of 10 ⁴ particles/mm ² or more as measured by the method described above, and a proportion of coarse particles of 7 μ or more is less than 10%. The polyester in the present invention is a polyester whose main constituent unit is ethylene terephthalate, which can be molded into fibers, films, and other molded products, and is produced by a conventionally known method. Of course, these polyesters may be homopolyesters or copolyesters, and examples of copolymerizable components include diethylene glycol, propylene glycol, neopentyl glycol, polyalkylene glycol, p-
Diol components such as xylylene glycol, 1,4-cyclohexanedimethanol, 5-sodium sulforesorcin, adipic acid, sebacic acid, phthalic acid, isophthalic acid, 2,6-naphthalene dicarboxylic acid, 5-sodium sulfoisophthalic acid, etc. Examples include dicarboxylic acid components, other functional dicarboxylic acid components such as trimellitic acid and pyromellitic acid, and oxycarboxylic acid components such as p-oxyethoxybenzoic acid. When the dicarboxylic acid component is a dicarboxylic acid, after an esterification reaction with a glycol, and when a dicarboxylic acid ester is used, after an esterification reaction with a glycol, the resulting prepolymer is polycondensed at high temperature under vacuum to obtain a polyester. It is also possible to carry out polycondensation using the prepolymer itself as a starting material. The phosphorus compound used in the present invention is preferably one or more selected from the group consisting of phosphoric acid, phosphorous acid, or their methyl esters, ethyl esters, phenyl esters, and half esters, and in particular methyl phosphoric acid. Ester, ethyl ester and phenyl ester are preferred. The lithium compound referred to in the present invention is a glycol-soluble compound, and includes monocarboxylic acid lithium salts such as lithium formate and lithium acetate, lithium halides such as lithium chloride and lithium bromide, lithium hydride, ethyllithium, butyllithium, etc. Organic lithium compounds, lithium carbonate, and the like are preferably used. The amount of the soluble lithium compound added is 1.2 to 2.5 mol% (based on the dicarboxylic acid or its alkyl ester). If the amount of lithium compound added exceeds 2.5 mol%, lithium metal compounds will precipitate in the polyester produced, and the proportion of coarse particles will increase.
When molded into a film or fiber, it increases surface roughness, which is undesirable. On the other hand, if it is less than 1.2 mol%, the number of particles in the polyester produced is less than 10 ⁴ particles/mm ² ,
As a result, slipperiness becomes insufficient and opacity decreases, which is not preferable. The amount of the phosphorus compound added is also related to the amount of the lithium compound added, but is selected between 0.25 and 1.2 mol % based on the acid component of the polyester raw material.
If the amount of the phosphorus compound added is less than 0.25, the particles formed in the resulting polyester may become coarse, or
Causes a decrease in thermal stability. On the other hand, if the amount of the phosphorus compound added exceeds 4.0, the film tends to stick to the casting drum when used as a film, causing film breakage. Next, the important point in the present invention is that the amount of the lithium compound used is 1.0 to 4.0 times equivalent to the phosphorus compound. Equivalence of the lithium compound to the phosphorus compound is expressed by the following formula. (1/2Li)/P (In the formula, Li and P represent the mol% of the lithium compound and phosphorus compound, respectively, with respect to the polyester raw acid component.) That is, if the equivalent ratio of the lithium compound to the phosphorus compound is less than 1.0, This is not preferred because the amount of particles produced is small and the softening point of the polyester is lowered. In addition, if the equivalent ratio of the lithium compound to the phosphorus compound exceeds 4.0, the proportion of particles consisting of metal salts of carboxylic acid will increase, and these will aggregate and become coarse to form coarse particles, which will further lead to the continuous production of polyester. When doing,
Due to the influence of previous batching, the proportion of aggregated coarse particles may vary greatly, or the proportion may become large, resulting in a roughened surface when formed into a film or fiber. The lithium metal compound and phosphorus compound used in the present invention undergo polycondensation from the time when esterification from dicarboxylic acid and glycol is substantially completed, or from the time when transesterification from alkyl ester of dicarboxylic acid and glycol is substantially completed. It can be added at any time until it progresses and reaches an intrinsic viscosity of 0.2. Adding the phosphorus compound before the completion of the esterification or transesterification reaction inhibits the progress of the transesterification reaction, and particularly reduces the catalytic ability of the transesterification catalyst, which is not preferable. Furthermore, if it is added at a stage when the intrinsic viscosity of the polyester exceeds 0.2, the object of the present invention, which is to increase the number of particles, cannot be achieved, and the opacity and sliding properties of the molded product will not be achieved. In addition, in the present invention, the esterification reaction or the transesterification reaction is carried out using a suitable amount of alkali metals selected from the group consisting of lithium, sodium, and potassium, and alkaline earth metals selected from the group consisting of magnesium, calcium, strontium, and barium. Metals and hydrides of zinc, manganese,
Alcoholates, chlorides and glycol-soluble salts of monocarboxylic acids are preferably used as catalysts. Particularly preferred examples include lithium acetate, calcium acetate, strontium acetate, zinc acetate, manganese acetate, and manganese chloride. Typical catalyst systems used for the polycondensation of bishydroxyalkyl esters of aromatic dicarboxylic acids are glycol-soluble antimony or germanium compounds, such as antimony trioxide, antimony potassium tartrate, antimony oxychloride, and germanium oxide. The catalyst is preferably used in an appropriate amount. The polyester obtained by the method of the present invention is
It can be preferably used not only for fibers such as multifilaments and staples, and non-oriented, uniaxially oriented, and biaxially oriented films, but also for monofilaments and plastics. [Example] The present invention will be described in detail with reference to Examples below. Incidentally, various characteristic values of the obtained polyester were measured according to the following method. A Solution haze 0.5g of polymer is mixed with 4/4 of tetrachloroethane/phenol.
6 Add to 20 cc of mixed solvent and dissolve by heating at 100℃. The solution was sampled into a quartz glass cell with a thickness of 20 mm, and the haze value was measured using a direct reading haze computer (manufactured by Suga Test Instruments Co., Ltd.) and expressed in %. B Intrinsic viscosity and softening point of polymer The intrinsic viscosity is determined by using o-chlorophenol as a solvent.
This is a value measured at 25℃, and the softening point is the value measured by placing a polymer chip in a heating bath and heating it at a rate of 6℃/5 minutes, and measuring the temperature at which the tip of the load penetrates 5 mm or more into the chip. It is. C Film properties (a) Film haze (turbidity) Measured in accordance with ASTM-D1003-52. (b) Coefficient of friction of film ASTM-D-1894B using slip tester
Measure according to the law. The coefficient of static friction was used as a measure of the slipperiness of the film. (c) Roughness of film surface unevenness The film surface was observed using a stylus roughness meter, and the difference between the highest and lowest surface unevenness obtained was expressed in μ units. Example 1 A transesterification reaction was carried out using 100% by weight of dimethyl terephthalate and 70% by weight of ethylene glycol using 0.09% by weight of calcium acetate as a catalyst, and the product contained 0.03% by weight of antimony trioxide,
0.8% by weight of lithium acetate and 0.2% by weight of trimethyl phosphate were added and polymerized by a conventional method to obtain a polymer having an intrinsic viscosity of 0.62. The number of particles in the polymer, solution haze, and particle dispersibility were good as shown in Table 1. Example 2 A polymer having an intrinsic viscosity of 0.610 was obtained by polymerizing in exactly the same manner as in Example 1, except that 0.16% by weight of methyl acid phosphate was added as a phosphorus compound after the transesterification reaction was completed. number of particles in the polymer,
The solution haze and particle dispersibility were good as shown in Table 1. Comparative Example 1 Polymerization was carried out in exactly the same manner as in Example 1, except that 0.09% by weight of calcium acetate was used as a transesterification catalyst, transesterification was carried out in a conventional manner, and 0.216% by weight of lithium acetate was added to the resulting product. A polymer with an intrinsic viscosity of 0.615 was obtained. The number of particles in the polymer, solution haze, and particle dispersibility were unfavorable as shown in Table 1. Comparative Example 2 Using 0.09% by weight of calcium acetate as a transesterification catalyst, adding 0.8% by weight of lithium acetate,
Polymerization was carried out in the same manner as in Example 1 without adding a phosphorus compound to obtain a polymer with an intrinsic viscosity of 0.618. 1st
As shown in the table, the particle dispersibility was poor and undesirable. Example 3 A polymer was obtained by polymerizing in the same manner as in Example 1, with various addition amounts of lithium acetate and trimethyl phosphate. Table 2 shows the measurement results for the number of particles, solution haze, and particle dispersibility of each polymer. Example 4 Example 4 except that 100% by weight of dimethyl terephthalate and 70% by weight of ethylene glycol were transesterified by a conventional method using 0.09% by weight of calcium acetate as a catalyst, and 0.37% by weight of lithium chloride was added to the product. Polymerizes in the same way as 1 to obtain the limiting viscosity
A polymer of 0.607 was obtained. The number of particles in the polymer is
The density was 20,800 particles/mm ² , the solution haze was 89%, and the proportion of coarse particles of 7μ or more was 2.5%, which was good. Example 5 The polymer obtained in Example-1 was formed into a sheet at 290°C by a conventional method, and the longitudinal stretching ratio was 3.3 times using a biaxial stretching machine.
After stretching at a transverse stretching ratio of 3.4 times, heat treatment was performed at 215°C to obtain a film with a thickness of 20 μm. Work stability during film formation was good, and there were no problems such as film breakage.
The obtained film had a good haze of 55%, a static friction coefficient of 0.42, an average film surface roughness of 0.03μ, and a maximum film surface roughness of 0.25μ. Comparative Example 3 The polymer obtained in Comparative Example-1 was heated to 290°C by a conventional method.
Formed into a sheet with a thickness of 20 μm using the same method as in Example-5.
I got the film. The haze of the obtained film was 13%, the coefficient of static friction was 0.54, the average roughness of the film surface was 0.025μ, the maximum roughness of the film surface was 0.21μ,
The film haze was much poorer than the film made from the polyester of the present invention. Example 6 A transesterification reaction was carried out using 100% by weight of dimethyl terephthalate and 70% by weight of ethylene glycol using 0.09% by weight of calcium acetate as a catalyst, and the resulting product contained 0.03% by weight of antimony trioxide,
0.04% by weight of trimethyl phosphate was added and polymerized by a conventional method to obtain a polymer having an intrinsic viscosity of 0.630 and a solution haze of 2.5%. After blending 80% by weight of the polymer and 20% by weight of the polymer obtained in Example-1, a film with a thickness of 12 μm was obtained in the same manner as in Example-5. The static friction coefficient of the obtained film was 0.6,
The maximum surface roughness of the film was 0.37μ, which was good. Comparative Example 4 After blending 80% by weight of the polymer with an intrinsic viscosity of 0.630 and solution haze of 25% obtained in Example-6 and 20% by weight of the polymer obtained in Comparative Example-2,
A film with a thickness of 12 μm was obtained in the same manner as in Example-5. The static friction coefficient of the film was 0.5, and the maximum film surface roughness was 0.7μ, which was far inferior to the film blended with the polyester of the present invention in terms of maximum film surface roughness. Example 7 Polyester was produced in Example-1, and the polymerization reaction vessel from which the polyester was taken out (the polyester was
Example - 10g remaining as residual polymer)
A polymerization reaction was carried out in the same manner as in Example 1, except that the transesterified product that had been subjected to the transesterification reaction in the same manner as in Example 1 was added. The obtained polyester had an intrinsic viscosity of 0.63, and the number of particles in the polymer was 22,000 particles/mm ² .
Solution haze is 91.5%, the proportion of particles larger than 7μ is
It was good at 2.5%. Comparative Example 5 In Example-7, 0.12 parts [1/2
(Li/P)=4.57] Polyester was produced in exactly the same manner as in Example-1 except that the polyester was changed to (Li/P)=4.57]. The intrinsic viscosity of the polyester obtained in the first batch is 0.62,
The number of particles was 25,000 particles/mm ² , the solution haze was 94%, and the proportion of coarse particles of 7μ or more was 12%, but the intrinsic viscosity of the polyester obtained in the second consecutive batch was 0.61, and the number of particles was is 28000 co/ ^mm2 , solution haze is
96%, and the proportion of coarse particles of 7μ or more is 20%, which is not preferable because the amount of coarse particles produced when continuously produced is large.

【table】

【table】

[Table] [Effects of the Invention] The polyester obtained by the method of the present invention contains a large amount of uniform, fine internal particles and has excellent opacity and slipperiness. The following effects that could not be achieved with conventional methods are exhibited. There is less clogging of filters during the process of melt molding into fibers and films, and there is less chance of fiber cutting or film tearing due to foreign matter contamination. When a biaxially stretched film is obtained by high-speed film forming at 200 m/min or more, a film with less tearing and good workability in post-processing steps can be obtained. In addition, the obtained film has excellent opacity and slipperiness,
A product film of good quality can be obtained. Even if it is formed into an extremely thin film with a thickness of 4μ or less, it contains many uniform fine particles, so there is no blocking phenomenon between films, between films and metals, and between films and felts, making it extremely slippery. A polyester film with excellent handling properties can be obtained. In addition, since it contains a large amount of uniform fine particles, it can be used diluted, and in this case too, there is no film stickiness, and it is especially useful for magnetic tape applications because there are no dropouts, image unevenness, or sound skipping during playback. be. The polyester obtained by the method of the present invention is
It can be preferably used not only for fibers such as multifilament staples, non-oriented, uniaxially oriented, and biaxially oriented films, but also for monofilaments and plastics.

Claims (1)

[Claims] When producing a polyester containing polyethylene terephthalate as a main component by a transesterification reaction or esterification reaction between terephthalic acid or its ester-forming derivative and glycol and a subsequent polycondensation reaction, the transesterification reaction or Immediately after the esterification reaction, while the polycondensation reaction progresses and the intrinsic viscosity of the product does not exceed 0.2, a lithium compound and a phosphorus compound are added in an amount that satisfies the following formula, and the polycondensation reaction is carried out. The number of particles by the defined measurement method is 10 ⁴ particles/mm ² or more and 0.5μ
A method for producing polyester, characterized by obtaining a polyester in which the ratio of the number of coarse particles of 7μ or more to the total number of particles is less than 10%. 1.2<Li<2.5 0.25<P<1.2 1.0<(1/2Li)/P<4.0 (In the formula, Li and P are the mol% of the lithium compound and phosphorus compound, respectively, based on the polyester raw acid component)
represents. )