JPH0142288B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing polyester having excellent particle dispersibility. More specifically, the present invention relates to a method for producing polyester with excellent particle dispersibility, which comprises adding specific inert inorganic fine particles under specific conditions during polyester production, and then completing the polymerization. In general, polyester has excellent physical and chemical properties and is therefore widely used as textiles for clothing and industrial use, as well as for magnetic tapes, photographic films, and the like. However, depending on the use of polyester, inert inorganic fine particles such as titanium oxide, carbon black, silicon oxide, aluminum oxide, etc. are often added as erasers, colorants, friction coefficient lowering agents, etc. Conventionally, when inert inorganic fine particles are added to polyester and polymerized, the inert inorganic fine particles aggregate and become coarse during the polymerization reaction of the polyester.
There were problems such as increased pressure due to sand clogging during spinning and yarn breakage during spinning and drawing. Many techniques have been proposed and implemented as methods for preventing the agglomeration of such inert inorganic fine particles, and they are generally as follows. (1) The average particle size of the primary particles is 20 mμ to 100 mμ,
Silicon oxide with a pH of 3.5 to 4.5 is treated with at least one basic compound selected from the group consisting of quaternary ammonium compounds to lower the pH.
7.0 to 10.5, and then added at any stage until the polymerization of polyester is completed (Japanese Patent Application Laid-Open No. 53-45396). (2) A method of adding lignin and an alkaline inorganic compound as a dispersant when producing an ethylene glycol slurry of a pigment (Japanese Patent Publication No. 32152/1983). (3) A method of adding alumina sol, silica sol, etc. as a dispersant to an ethylene glycol slurry of titanium oxide (US Pat. No. 3,402,141). (4) When polymerizing polyethylene terephthalate, start the transesterification polymerization reaction, keep the temperature below 250℃ until the pressure reaches 0.3 to 1 mmHg, and then raise the temperature (British patent
1069761 specification). (5) A method in which when polymerizing polyester, an ethylene glycol slurry of inert fine particles is heated to a temperature close to that of the reaction mixture and then added (Japanese Patent Publication No. 33468/1983). Among these, (1) to (3) relate to dispersants for inert inorganic fine particles, and although they were certainly effective compared to those that did not use a dispersant, they were not sufficient. In addition, (4) focuses on the fact that the aggregation of particles is affected by the temperature and viscosity of the reaction solution, and attempts to increase the viscosity as much as possible in the low temperature range, but this reduces the polymerization reaction rate and reduces production. The decline in sexuality was inevitable. Furthermore, although (5) attempts to prevent aggregation due to sudden temperature changes during addition, it is still not sufficient. As described above, although the conventional techniques have some effect in preventing agglomeration of inert inorganic fine particles, they are still not sufficient in preventing clogging of sand during spinning, film forming, etc. It is widely known that batch polymerization and continuous polymerization are used as methods for producing polyester by transesterification. Also,
The transesterification process often includes a transesterification step in which dimethyl terephthalate and alkylene glycol are reacted to produce bis-(2-hydroxyalkyl) terephthalate or its low polymer, and a polymerization step to obtain a highly polymerized polymer. Are known. In the case of the batch polymerization method, the transesterification reaction and the polymerization reaction are usually carried out using separate reaction vessels, and after the transesterification reaction is completed, the reaction solution is transferred to the polymerization vessel and polymerized. In addition, the transesterification reaction is carried out while gradually raising the temperature at 140°C to 230°C, and the heater is usually coiled to heat the reaction liquid. The present inventors conducted extensive studies on the causes of agglomeration of inert inorganic fine particles when producing a polymer containing inert inorganic fine particles, and found that a part of the heating coil of the transesterification tank is located above the liquid level. When applied to a heating coil located above the reaction liquid surface, inert inorganic fine particles in the reaction liquid adhere to the heating coil and aggregate, grow to a certain size and then fall off, resulting in coarse particles. The present invention was achieved by discovering that. That is, in the present invention, when producing polyester from dimethyl terephthalate and alkylene glycol by the transesterification method, the raw materials are charged so that the heating coil of the transesterification can is buried in the reaction liquid, and the heating coil is buried in the reaction solution. The present invention relates to a method for producing polyester with excellent particle dispersibility, characterized in that polymerization is completed after adding inert inorganic fine particles having an average primary particle diameter of 100 mμ or less. The polyester in the present invention refers to a polyester containing dimethyl terephthalate as a dicarboxylic acid component and a glycol selected from ethylene glycol or 1,4-butanediol as a glycol component, but polyethylene terephthalate is particularly preferred in terms of versatility. In addition, a part of dimethyl terephthalate is, for example, 5
-Sodium sulfoisophthalic acid, 5-potassium sulfoisophthalic acid, p-β-hydroxyethoxybenzoic acid, p-hydroxybenzoic acid, isophthalic acid, 4,4'-diphenylsulfonedicarboxylic acid, 4,4'-diphenylmethane dicarboxylic acid,
4,4'-diphenyl ether dicarboxylic acid, 4,
Lower alkyl esters of difunctional carboxylic acids such as 4'-diphenyldicarboxylic acid, 1,2'-diphenoxyethane-p,p'-dicarboxylic acid, 2,6-naphthalenedicarboxylic acid, adipic acid, and sebacic acid. or replace part of the glycol component with ethylene glycol, trimethylene glycol,
Fats such as tetramethylene glycol, hexamethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, 1,4-bis-β-hydroxyethoxybenzene, bisphenol A, etc. A copolymerized polyester in which 70 mol% or more of the repeating units in the main chain are ester units selected from ethylene terephthalate units and tetramethylene terephthalate units, which are substituted with group, alicyclic, or aromatic dioxy compounds or their ester-forming derivatives. It may be hot. Furthermore, it is also possible to use a small proportion of a chain branching agent such as pentaerythritol, trimethylolpropane, trimellitic acid, trimesic acid, etc., or a polymerization terminator such as monohydric polyalkylene oxide, phenylacetic acid, etc. In order to produce the polyester of the present invention from such raw materials, for example, dimethyl terephthalate, ethylene glycol or 1,4-butanediol, inert inorganic fine particles with an average primary particle size of 100 mμ or less, and a transesterification catalyst must be completely heated by a heating coil. The mixture was placed in a transesterification can so as to be submerged in the reaction solution, and the temperature was gradually raised while the transesterification reaction proceeded. After the transesterification reaction was completed, a polymerization catalyst and a stabilizer were added at 220 to 240°C, and then the mixture was placed in the polymerization can. A method is adopted in which the mixture is transferred and polymerized by a conventional method. Further, in synthesizing the polyester according to the present invention, catalysts, color inhibitors, ether bond by-product inhibitors, antioxidants, flame retardants, etc., which are well known in the art, can be appropriately used. In the present invention, inert inorganic fine particles include dry process silica, wet process silica, aluminum oxide-containing dry process silica, or special dry process silica having an alkyl group on the particle surface and blocking silanol groups on the particle surface. Examples include dry process silica, silicon-containing inorganic fine particles such as kaolinite, titanium oxide, calcium carbonate, aluminum oxide, and carbon black. Among these, the present invention is particularly effective against silicon oxide and carbon black, which tend to aggregate during polymerization. In the present invention, the aluminum oxide-containing dry process silica is produced by making aluminum halide exist in silicon halide when silicon oxide is produced by a dry process, and the aluminum oxide content is 0.1 to 1.
5% by weight of silicon oxide, preferably 0.3-2% by weight. Further, in the present invention, the dry process silica having an alkyl group on the particle surface and blocking the silanol groups on the particle surface is, for example, a particle surface obtained by reacting dry process silicon dioxide with dialkyldichlorosilane. It is silicon oxide with blocked silanol groups. The method for producing silica using the dry process in the present invention is, for example, the method described on page 524 of "Practical Handbook of Additives for Plastics and Rubber" (Kagaku Kogyosha, published on August 10, 1970). Generally, this is a method in which silicon halide is thermally decomposed together with hydrogen and oxygen in the gas phase. In the present invention, the silanol group blocking rate on the particle surface of the dry process silica having an alkyl group on the particle surface and blocking the silanol groups on the particle surface is preferably 50% or more. Further, the alkyl group of the silica having an alkyl group on the particle surface and blocking the silanol group on the particle surface in the present invention is not particularly limited, but methyl groups and ethyl groups are preferable. The average primary particle diameter of the inert inorganic fine particles in the present invention must be 100 mμ or less. 100mμ
If the diameter exceeds 1, the effect of reducing coarse particles in the inert inorganic fine particles is small and the coarse particles in the polymer increase. The amount of inert inorganic fine particles added in the present invention is not particularly limited, but is preferably 4% or less. If the amount exceeds 4%, coarse particles tend to increase. In the present invention, the inert inorganic fine particles are dispersed in aliphatic glycol, aliphatic alcohol, water, etc. by a known method to form a dispersion slurry at any stage where the heating coil is buried until the transesterification reaction liquid is transferred to the polymerization vessel. However, it is particularly preferable to add it by dispersing it in glycol, which is a raw material for the polyester. Further, the concentration of the glycol slurry is preferably 1 to 20% by weight, particularly preferably 5 to 15% by weight, from the viewpoint of the number of coarse particles and the softening point of the resulting polyester chips. The dispersion slurry of inert inorganic fine particles in the present invention can be prepared by a conventionally known method.
Preferred are the method of dispersing in a high-speed stirrer having a plurality of shearing blades parallel to the rotating direction of the stirring blades and the method of using an ultrasonic dispersion method in combination with the dispersion method, as disclosed in the above publication. The prepared slurry is preferably passed through a filter with 60 meshes or more in order to remove coarse particles in the slurry. Further, it is preferable to use a dispersant for the purpose of preventing agglomeration of inert inorganic fine particles. In particular, as a dispersant for silicon-containing inorganic fine particles, aluminum oxide, etc., tetraalkylammonium is suitable because it has a large aggregation prevention effect. Further, as a dispersant for carbon black, a copolymerized polyester obtained by copolymerizing 10 mol% or more of 5-sodium sulfoisophthalic acid or 5-potassium sulfoisophthalic acid is preferable. The method of heating the transesterification vessel in the present invention is to bring a heating coil into direct contact with the reaction liquid.
Any other method will not bring out the effects of the present invention. In the present invention, the amount of reaction solution charged is at least the amount that allows the heating coil of the transesterification can to be completely submerged in the reaction solution. The fact that the heating coil is completely submerged in the reaction solution means that the heating coil is completely submerged in the reaction solution because methyl alcohol distills out at the start of the transesterification reaction and during the transesterification reaction, and the liquid level of the reaction solution decreases. The state of being completely buried inside. If the heating coil is exposed above the reaction liquid, when adding inert inorganic particles or during transesterification, the inert inorganic particles will adhere to the exposed part and aggregate and fall off, causing coarse particles in the polymer. The number increases. Polyester polymerization equipment is generally designed so that transesterification time and polymerization time are approximately the same when obtaining a specific intrinsic viscosity. However, polyester now comes in many different brands, including fibers and films, and is used for a variety of purposes.
Therefore, the intrinsic viscosity,
The reality is that they are produced by changing catalysts, etc.
However, while the transesterification reaction time does not depend so much on the amount charged, the polymerization reaction time has a very large dependence on the amount charged. Therefore, when producing a product with a high intrinsic viscosity or a product with a slow polymerization reaction rate, it is common to reduce the amount of feed so that the transesterification reaction time and the polymerization reaction time are approximately equal. For some varieties, even if they are polymerized using the same polymerization equipment, the amount charged must be reduced to about half that of varieties that require a relatively large amount. When such a small amount is reacted in the transesterification can, a part of the heating coil of the transesterification can is exposed from the reaction liquid, making it impossible to carry out the present invention. Therefore, the number of coarse particles in the obtained polymer increases significantly. As a result of intensive studies by the present inventors on this problem, the transesterification reaction is carried out so that the heating coil is completely submerged in the reaction liquid, and inert inorganic fine particles are added between the heating coil and the reaction solution. It was then discovered that by transferring an amount to the polymerization reactor in such an amount that the polymerization reaction time would reach a predetermined time to complete the polymerization, both the reaction time and the number of coarse particles in the polymer could be made very good. . The reaction solution left in the transesterification tank is used as a raw material in the next transesterification reaction. In this case, there were concerns that the residence time in the reactor would be longer, resulting in coloring of the resulting polymer and lowering of the melting point due to an increase in diethylene glycol, but this was at a level that caused almost no problems. The present invention will be specifically described below with reference to Examples. In addition, various measurement methods in the present invention are as follows. (Average primary particle size) 3000~
A photograph is taken at a magnification of 100,000 times, the longest diameter of each primary particle is measured from the resulting image, and the value is determined as the average of 200 particles. (Intrinsic viscosity [η]) Dissolve the polymer in O-chlorophenol and heat at 25°C.
This is the value measured at (b value) The polymer is molded into a cylindrical shape with a diameter of 2.5 to 3.5 mm and a height of 4.5 to 5.5 mm, and measured using a direct-reading color difference computer manufactured by Suga Test Instruments Co., Ltd. The larger the b value, the greater the yellowing tendency of the polymer. (Number of coarse particles) A polyester chip was formed into a biaxially stretched film with a thickness of 25μ by a conventional method, and this ^25cm2 film was observed with a stereomicroscope (60x magnification) to measure coarse particles with a maximum length of 30μ or more. The number of coarse particles per gram of sample was calculated. The number of coarse particles was measured 10 times per level.
It was expressed as the average value. (Melting point) Using Perkin-Elmer's DSC-1B, using 10 mg of sample polymer, under nitrogen gas atmosphere, from room temperature to
The temperature was raised at a rate of 16°C/min, and the minimum point (Tm) of the melting point peak was measured. Example 1 250 parts of dimethyl terephthalate, 113.8 parts of ethylene glycol, 0.25 parts of calcium acetate monohydrate, having methyl groups on the particle surface and blocking 75% of the silanol groups on the particle surface, with an average primary particle size of 16 m
Janke&
Kunkel Ultra Turrax T45DX (10000rpm)
2.50 parts of the slurry dispersed for 30 minutes as silicon oxide having methyl groups on the particle surface and blocking the silanol groups on the particle surface was charged into a transesterification tank, and the temperature was raised to 150 to 230°C under a nitrogen atmosphere. While continuously distilling the generated methanol out of the system,
A transesterification reaction was carried out, and the reaction was completed 3 hours after the start of the reaction. 0.25 part of trimethyl phosphate and 0.1 part of antimony trioxide were added to the obtained product. Next, the reaction mixture was transferred to a polymerization tank, and the pressure of the polymerization reaction system was gradually reduced to 760 mm over 1 hour and 30 minutes.
The pressure was reduced from Hg to 1 mmHg, and at the same time the temperature was raised from 230°C to 285°C over 1 hour and 30 minutes. Polymerization was carried out for an additional 3 hours at a polymerization temperature of 285° C. for a total of 4 hours and 30 minutes under reduced pressure of 1 mmHg or less. After the reaction is completed, the polymer has a diameter of 3
It was discharged into water in the form of a mm rod and cut into 5 mm lengths to obtain polyester chips. The polymer properties of the obtained polyester chips are shown in Table 1. Note that the heating of the polymerization apparatus used in this example is by a heating coil method, and when the raw materials as in this example are charged in the ratio as in this example, when 250 parts of dimethyl terephthalate is charged, the heating coil starts the transesterification reaction. When 210 parts of dimethyl terephthalate is charged, the heating coil will be completely submerged in the reaction solution at the beginning of the reaction, but in the latter half of the reaction, methyl alcohol will be distilled out and the liquid level will drop. Therefore, part of the heating coil is distilled out above the liquid level. Furthermore, if the amount of dimethyl terephthalate charged is less than 210 parts, part of the heating coil will be exposed above the liquid level from the beginning of the reaction. Example 2 In Example 1, dimethyl terephthalate was used as the first
Polyester chips were obtained in the same manner as in Example 1, except that the changes were made as shown in the table and other raw materials were also changed so that the composition of the obtained polyester was the same as in Example 1. However, the reaction time was changed as appropriate to obtain a polymer with the desired intrinsic viscosity. The properties of each polyester are shown in Table 1. Note that Experiment No. 3 is a comparative experiment for clarifying the effects of the present invention. It is clear from Table 1 that the number of coarse particles is particularly good when the amount of reaction solution charged satisfies the present invention.

[Table] Example 3 A transesterification reaction was carried out in the same manner as in Example 1. Next, after transferring the transesterification reaction solution equivalent to 150 parts of dimethyl terephthalate to the polymerization can,
Polyester chips were obtained by polymerization in the same manner as in Example 1. The polymer properties of the obtained polyester chips are shown in Table 2. In addition, raw materials were added to the reaction solution left in the transesterifier in the same manner as in Example 1, except that the amount of dimethyl terephthalate was changed to 150 parts, and the other raw materials were changed accordingly. Then, a transesterification reaction was carried out in the same manner as in Example 1. Next, a reaction solution equivalent to 150 parts of dimethyl terephthalate was transferred to a polymerization vessel and polymerized to obtain polyester chips. The polymer properties of the obtained polyester chips are shown in Table 2. For comparison, transesterification and polymerization were carried out in the same manner as in Example 1, and polyester chips were obtained by transferring the entire transesterification reaction solution to a polymerization can. The polymer properties of the obtained polyester chips are shown in Table 2. As is clear from this table, when a portion of the transesterification reaction solution is left in the transesterification tank, the polymerization time is very short and favorable. Further, even when a portion of the transesterification reaction solution remains, the polymer properties of the obtained polyester chips in the next polymerization batch are also good.

[Table] Example 4 In Example 1, particles having methyl groups on the surface,
Polyester chips were obtained by carrying out transesterification and polymerization reactions in the same manner as in Example 1, except that the amount of dry process silicon oxide used to block the silanol groups on the particle surface was changed as shown in Table 3. The polymer properties of the obtained polyester chips are shown in Table 3. As is clear from this table, when the amount of silicon oxide added is within the range of the present invention, the number of coarse particles in the obtained polymer is small and good. For comparison, the test was also carried out using 150 parts of dimethyl terephthalate.

[Table] Example 5 Polyester chips were obtained by carrying out transesterification and polymerization in the same manner as in Example 1 except that the type of inert inorganic fine particles was changed as shown in Table 4. Table 4 shows the polymer properties of the polyester chips obtained. As is clear from this table, when the particle size of the inert inorganic fine particles is 1 μm or less, the number of coarse particles is small and good. For comparison, the test was also carried out using 150 parts of dimethyl terephthalate.

【table】

[Table] Example 6 Transesterification and polymerization were carried out in the same manner as in Example 1, except that the type and amount of the dispersant for inert inorganic fine particles were changed as shown in Table 5, and polyester chips were obtained. Ta. Table 4 shows the polymer properties of the polyester chips obtained. As can be seen from this table, the Examples of the present invention in which a dispersant was added had good effects. For comparison, the test was also carried out using 150 parts of dimethyl terephthalate.

【table】

Claims (1)

[Scope of Claims] 1. When producing polyester from dimethyl terephthalate and ethylene glycol or 1,4-butanediol by the ester method, the raw materials are charged so that the heating coil of the transesterification can is submerged in the reaction liquid, and the coil 1. A method for producing polyester with excellent particle dispersibility, which comprises adding inert inorganic fine particles having an average primary particle diameter of 100 mμ or less between the particles embedded therein, and then completing polymerization. 2. The method for producing polyester with excellent particle dispersibility according to claim 1, characterized in that a part of the transesterification reaction liquid is left in the transesterification can when the transesterification reaction liquid is transferred to the polymerization can. 3. The method for producing a polyester with excellent particle dispersibility according to claim 1 or 2, wherein the inert inorganic fine particles are silicon oxide or carbon black.