JPH038376B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a polyester whose main repeating unit is ethylene terephthalate, which has good resin quality, easy brand switching, and improved transparency and electrostatic adhesion. It is something. Saturated linear polyester, represented by ethylene terephthalate, has excellent mechanical properties, heat resistance, weather resistance, electrical insulation, and chemical resistance, so it is used in a wide range of fields such as packaging, photography, electrical applications, and magnetic tape. It is often used in Polyester films are usually obtained by melt-extruding polyester and then biaxially stretching it. In this case, in order to increase the uniformity of the film thickness and the casting speed, when the sheet material melted and extruded from the extrusion die is rapidly cooled on the surface of the rotating cooling drum, the adhesion between the sheet material and the drum surface is controlled. Must be raised. As a method of increasing the adhesion between the sheet-like material and the drum surface, a wire-shaped electrode is installed between the extrusion die and the rotating cooling drum, and a high voltage is applied to deposit static electricity on the top surface of the unsolidified sheet-like material. It is known that a method of rapidly cooling the sheet-like material while bringing it into close contact with the surface of the cooling body (hereinafter referred to as electrostatic adhesion casting method) is effective. Uniformity of film thickness is a very important property in film quality, and film productivity is directly dependent on casting speed, so increasing the casting speed is extremely important to improve productivity. Therefore, great efforts are being made to improve electrostatic adhesion. An effective means for achieving such electrostatic adhesion is to increase the amount of charge on the surface of the sheet-like object. Therefore, in order to increase the amount of charge on the surface of the sheet-like object in the electrostatic adhesion casting method, polyester It is known that raw materials can be modified to lower their resistivity. Furthermore, as a method of lowering the specific resistance of this polyester raw material, it is known to add an alkali metal or alkaline earth metal compound after the completion of the esterification or transesterification reaction. It is true that this method lowers the specific resistance of the polyester raw material and the electrostatic adhesion reaches a somewhat satisfactory level, but in the manufacturing process of the polyester raw material, in order to increase the electrostatic adhesion, the esterification rate must be significantly increased. To achieve this, a large amount of ethylene glycol (hereinafter referred to as EG) must be used, and the reaction time becomes longer, which inevitably increases the amount of diethylene glycol (hereinafter referred to as DEG) as a by-product, which is a serious drawback. are doing. This by-product DEG
An increase in the amount lowers the softening point of the polyester, which makes the film more likely to stick to the surface of the rotating cooling drum during film formation, increases tearing of the film during stretching, and further reduces the heat resistance of the resulting film. It can cause things like. Furthermore, when the above method is carried out continuously, it has the disadvantage that it cannot easily cope with changing brands or increasing the number of brands. The present inventors improved the above-mentioned conventional drawbacks,
The amount of DEG by-product is small, and brand switching is easy.
The present invention was arrived at as a result of extensive research into a method for producing polyester that also has excellent transparency and electrostatic adhesion. In the present invention, when producing a polyester whose main repeating unit is ethylene terephthalate, the following master polymer or/and master polymer is used as Mg atoms at a stage after the initial condensation reaction is completed and the intrinsic viscosity reaches 0.2 or more. This is a method for producing polyester, characterized in that it is added in an amount of 30 to 400 ppm based on the total polyester. 0.1≦Mg≦3.0 …() 1.2≦Mg/P≦20 …() (where Mg is the weight% of the master polymer as Mg atoms in the added Mg compound,
Mg/P indicates the atomic ratio of Mg metal atoms to phosphorus atoms. ) Master polymer: When reacting dicarboxylic acids, mainly acids, with glycols, mainly ethylene glycol,
At any stage from before the start of the reaction until the intrinsic viscosity reaches 0.2, an amount of Mg compound and P compound that satisfies the above general formulas () and () is added at the same time, and then polycondensation is performed. Polymer over 0.2. Master polymer: An acid component mainly consisting of a lower alkyl ester of terephthalic acid and a glycol component mainly consisting of ethylene glycol are reacted, and when the transesterification reaction is substantially completed, the above general formulas () and () are simultaneously combined. The intrinsic viscosity prepared by adding a satisfactory amount of Mg compound and P compound and then polycondensing
Polymer over 0.2. Here, the intrinsic viscosity is a value measured at 30° C. by dissolving a polymer, master polymer, or oligomer in a mixed solvent of phenol (6 parts by weight) and tetrachloroethane (4 parts by weight). In the present invention, the polyester finally obtained consists of ethylene terephthalate in 80 mol% or more of its repeating units, and other copolymer components include isophthalic acid, P-β-oxyethoxybenzoic acid, 2,6 -naphthalene dicarboxylic acid, 4,4'-dicarboxyl diphenyl, 4,
4'-dicarboxylbenzophenone, bis(4-
carboxyl phenyl) ethane, adipic acid,
Examples include dicarboxylic acids such as sebacic acid and 5-sodium sulfoisophthalic acid, and derivatives thereof. Further, as the glycol component, propylene glycol, butanediol, neopentyl glycol, cyclohexanedimethanol, ethylene oxide adduct of bisphenol A, etc. can be arbitrarily selected and used. In addition, small amounts of amide bonds, urethane bonds, ether bonds, carbonate bonds, etc. may be included as copolymer components. Such polyesters are produced by conventional melt polymerization methods. For example, either a direct polymerization method or a transesterification method may be employed, and either a batch method or a continuous method may be employed.
The transesterification and polycondensation catalysts can be appropriately selected from conventionally known catalysts, and it goes without saying that lubricants made of inorganic or organic fine particles and various other additives may also be used. A major feature of the present invention is that a master polymer prepared in advance is added at a stage after the completion of the initial condensation reaction product in an amount of 30 to 400 ppm as Mg atoms based on the total polyester. The master polymer is preferably added to the reaction system after the initial condensation reaction has been completed and its intrinsic viscosity has reached 0.2 or more. If the master polymer is added when the above-mentioned intrinsic viscosity is less than 0.2, the mixing of the master polymer will be incomplete, making it difficult to achieve the effect of the blending method, and depolymerization of the master polymer will occur, which is economically disadvantageous. So I don't like it. It is preferable that the difference between the above-mentioned intrinsic viscosity and the intrinsic viscosity of the master polymer to be added be as small as possible, because mixing will occur completely and the effects of the polymer blending method will be more easily exhibited. The master polymer may be prepared by either a direct polymerization method or a transesterification method. Regardless of whether direct polymerization or transesterification is used, it is necessary to add Mg and P compounds in amounts that simultaneously satisfy the following general formula. 0.1≦Mg≦3.0 …() 1.2≦Mg/P≦20 …() (In the formula, Mg is the weight percent of the polyester unit as an Mg atom in the Mg compound,
Mg/P indicates the atomic ratio of Mg atoms to P atoms. ) If the amount of Mg compound added when preparing the master polymer is less than 0.1% by weight as Mg atoms per polyester conversion unit, the amount of master polymer used will be large, which is economically disadvantageous;
If it exceeds % by weight, the amount of DEG by-products and the amount of coarse particles precipitated due to Mg compounds will increase, which is not preferable. In particular, it is more preferable to add 1 to 2% by weight. Further, the ratio of the Mg compound and the P compound to be added is not preferable because if Mg/P is less than 1.2, the specific resistance of the polyester raw material will decrease less, and as a result, the electrostatic adhesion will not be improved sufficiently. On the other hand, if it exceeds 20, the electrostatic adhesion will decrease, and the heat resistance and resin color tone of the polyester ultimately obtained will deteriorate, which is not preferable. In particular, the range of 1.6 to 10 is more preferable. The timing of adding these Mg compounds and P compounds can be selected as appropriate at any stage from before the start of esterification to the end of the initial condensation reaction when preparing by direct polymerization method. It is preferable to add it after the rate has reached 91% or more. After the initial condensation reaction is completed, the viscosity of the reaction system is too high, which is undesirable because the added components will not be mixed uniformly and a homogeneous product will not be obtained. On the other hand, when preparing by the transesterification method, it is necessary to add it when the transesterification reaction is substantially completed. It is not preferable to add the Mg compound before the transesterification reaction is substantially completed because it becomes difficult to control the transesterification reaction. The order of addition of the Mg compound and the P compound is not particularly limited, and either compound may be added first or may be added at the same time. As the Mg compound used in preparing the master polymer, any Mg compound can be used as long as it is soluble in the reaction system. Examples include magnesium hydride, lower fatty acid salts such as magnesium acetate, and alkoxides such as magnesium methoxide. Examples of P compounds include phosphoric acid, phosphorous acid, phosphonic acid, and derivatives thereof. Specific examples include phosphoric acid, trimethyl phosphate, triethyl phosphate, tributyl phosphate, and triphenyl phosphate. Esters, phosphoric acid monomethyl ester, phosphoric acid dimethyl ester, phosphoric acid monoethyl ester, phosphoric acid diethyl ester, phosphoric acid monobutyl ester, phosphoric acid dibutyl ester, phosphorous acid, phosphorous acid trimethyl ester, phosphorous acid triethyl ester,
Methylphosphonic acid, methylphosphonic acid dimethyl ester, ethylphosphonic acid dimethyl ester, phenylphosphonic acid dimethyl ester, phenylphosphonic acid diethyl ester, phenylphosphonic acid diphenyl ester, etc., and these may be used alone or in combination of two or more. It's okay. The master polymer may have any composition as long as it satisfies the above requirements. For example, the molecular weight of the master polymer is such that its intrinsic viscosity is 0.2
There is no particular limitation as long as it is above. However, in order to exhibit the effect of the polymer blending method in the method of the present invention, it is preferable that the intrinsic viscosity be as close as possible to that of the base resin. In addition, terephthalic acid, dicarboxylic acids other than EG, and glycol may be used as copolymerization components as long as they are 20 mol % or less. In the present invention, the amount of master polymer added to the reaction system is within the range of 30 to 400 ppm as Mg atoms based on the total polyester. If it is less than 30 ppm, the specific resistance of the polyester raw material decreases little, resulting in insufficient improvement in electrostatic adhesion, which is not preferable. On the other hand, if it exceeds 400 ppm, the decrease in the specific resistance of the polyester raw material reaches a plateau, and the precipitation of coarse particles due to the Mg compound increases, resulting in a decrease in the transparency of the film, which is not preferable. Furthermore, the amount of DEG by-products increases,
This causes quality deterioration such as decreased stability of polyester. In addition, the supply of master polymer to the reaction system is as follows:
It may be carried out either in the form of chips or in a molten state, but it is preferable to carry out the process in a molten state from the viewpoint of feeding accuracy and ease of mixing. Further, it is preferable to use a mixing and kneading device to blend a master polymer with an intrinsic viscosity exceeding 0.5. Especially JP-A-56-44031, JP-A-56-
44032, patent application No. 10635 and application No. 57-57772
Most preferably, an apparatus such as that described in . Next, Examples and Comparative Examples of the present invention will be shown. All parts in the examples mean parts by weight unless otherwise specified. In addition, the measurement method used is shown below. (1) Esterification reaction rate Calculated from the amount of carboxyl groups remaining in the reaction product and the saponification value of the reaction product. (Saponification value) - (Amount of remaining carboxyl groups) / Saponification value x 100 (2) Intrinsic viscosity Polymer master polymer or oligomer is dissolved in a mixed solvent of phenol (6 parts by weight) and tetrachloroethane (4 parts by weight). Dissolve and measure at 30°C. (3) Amount of DEG in the polymer The polymer is decomposed with methanol and measured as mol% relative to EG by gas chromatography. (4) Polymer melt specific resistance Two electrode plates were placed in polyester melted at 275℃, the current value (io) was measured when a voltage of 120V was applied, and the specific resistance value (ρi) was calculated using the following formula. Find it by ρ (Ω・cm)=A/l×V/io A=electrode area (cm ² ), l=interelectrode distance (cm), V=voltage (V) (5) Electrostatic adhesion Extruder mouthpiece A tungsten wire electrode was installed between the casting drum and the casting drum, and a voltage of 10 to 15 KV was applied between the electrode and the casting drum to perform casting, and the surface of the resulting casting material was observed with the naked eye. , the casting speed at which pinner bubbles begin to occur is evaluated. The higher the casting speed of the polymer, the better the electrostatic adhesion. (6) Film haze Measure with a direct reading haze meter (manufactured by Toyo Seiki Co., Ltd.). Example 1 (1) Preparation of master polymer 519 parts of terephthalic acid, 431 parts of EG, 0.16 parts of triethylamine and 0.23 parts of antimony trioxide were charged into a stainless steel autoclave equipped with a stirrer, a distillation column and a pressure regulator, and the mixture was purged with nitrogen and then added. The esterification reaction was carried out while maintaining the pressure at a gauge pressure of 2.5 kg/cm ² at 250° C. and continuously removing water produced from the top of the distillation column. 100 after the start of the reaction
After a minute had elapsed, the pressure was released to obtain a product with an esterification rate of 98%. The intrinsic viscosity of the ester product is
It was less than 0.1. 25.9 parts of trimethyl phosphate was added to this esterification product, and
Heat and stir at 240°C for 10 minutes, then add a slurry of 63.5 parts of magnesium acetate tetrahydrate (1.2% by weight as Mg atoms, Mg/p=1.8) dispersed in 210 parts of EG, and heat at the same temperature at normal pressure. heated for 15 minutes. While raising the reaction temperature to 280℃, gradually lower the pressure of the reaction system to 0.05mmHg,
A polycondensation reaction was carried out at 280°C and 0.05 mmHg for about 60 minutes to obtain a master polymer with an intrinsic viscosity of 0.321. (2) Polymer production Using a continuous esterification reactor consisting of a two-stage complete mixing tank equipped with a stirrer, a partial condenser, a raw material inlet, and a product outlet, esterification is carried out in the first esterification reactor. To the system where the reaction products are present, the molar ratio of EG to terephthalic acid is 1.7.
An EG slurry of terephthalic acid which was adjusted to 289 ppm per terephthalic acid unit and contained antimony trioxide as an antimony atom was continuously supplied. Average residence time 4.5 hours at normal pressure, temperature 255
The reaction was carried out at ℃. This reaction product is continuously taken out of the system,
It was supplied to the second esterification reactor. Furthermore, 0.5 parts by weight of EG was added continuously per finished polyester unit, and the average residence time was 5.0 at normal pressure.
The reaction was carried out at a temperature of 260°C. The esterification rate of the first esterification reactor was 70%, and the esterification rate of the reaction product in the second esterification reactor was 98%. The esterification reaction product is continuously filtered through a stainless wire mesh filter with an opening of 600 mesh, and the first stage polycondensation reaction is equipped with a stirrer, a partial condenser, a raw material inlet, and a product outlet. Continuously supplied to the equipment, polycondensation reaction takes place, and the intrinsic viscosity increases.
A polymer of 0.320 was obtained. This polymer is continuously taken out, using a stirring device,
In the method of completing the polycondensation reaction by continuously supplying the polycondensation reactor to the second stage polycondensation reactor equipped with a dephlegmator, a raw material inlet, and a product outlet,
A line mixer is installed in the middle of the piping connecting the first stage and second stage polycondensation reactor, and the master polymer prepared in advance by the above method is added to this line mixer at a rate of 0.83 parts per 100 parts of the polymer passing through the pipe.
Percentage of parts (per polyester as Mg atoms)
100 ppm), and a polymer with an intrinsic viscosity of 0.620 was finally obtained.
The quality of this polymer was obtained by melt extruding the polymer at 290°C, stretching it 3.5 times in the longitudinal direction at 90°C, stretching 3.5 times in the transverse direction at 130°C, and then heat-treating it at 220°C.
Table 1 shows the film haze of the 12μ film. As is clear from Table 1, the polyester obtained by the method of the present invention has good electrostatic adhesion, transparency, and DEG content, and is of good quality. Comparative Example 1 In the method of Example 1-(2), except that the master polymer was not supplied all at once to the line mixer,
Table 1 shows the quality and film haze of the polymer obtained by the same method as in Example 1-(2). It can be seen that although the method of this comparative example has good transparency and DEG content, the electrostatic adhesion is extremely poor. Comparative Example 2 In the method of Example 1-(2), magnesium acetate tetrahydrate and trimethyl phosphate were used instead of the master polymer fed to the line mixer.
Example 1-(2) except that the EG solution was continuously supplied under pressure to the polyester passing through the pipes at 100 ppm as Mg atoms and 71 ppm as P atoms (Mg/p = 1.8). ) The quality and film haze of the polymer obtained by the same method as above are shown in Table 1. Among the qualities of the polyester obtained by the method of this comparative example, the electrostatic adhesion and transparency are relatively good, but the DEG content is high. Also, with this method,
Addition of EG solution causes depolymerization of the prepolymer and decreases polymerization productivity, so the intrinsic viscosity
In order to obtain a polymer of 0.620, the polycondensation temperature must be higher than in the method of Example 1-(2),
It is also inferior in that it is economically disadvantageous. Example 2 (1) Preparation of master polymer In a polymerization reactor, 607 parts of dimethyl terephthalate,
486 parts of EG and 0.31 parts of magnesium acetate tetrahydrate were charged, and the mixture was heated at 195° C. for about 4 hours in a nitrogen atmosphere to carry out transesterification. As the transesterification reaction progresses, the reaction temperature increases until the final 240
℃, substantially completing the transesterification reaction. 25.9 parts of trimethyl phosphate were added to this reaction product, heated and stirred at normal pressure at 240°C for 10 minutes, and then 63.2 parts of magnesium acetate tetrahydrate (1.2% by weight as Mg atoms, Mg/p = 1.8) was added.
A slurry liquid dispersed in 210 parts of EG was added and heated at the same temperature under normal pressure for 15 minutes, and then 19.22 parts by volume of an EG solution containing antimony trioxide at a concentration of 12 g/ml was added. While raising the reaction temperature to 280°C, the pressure of the reaction system was gradually lowered to 0.05mmHg, and the polycondensation reaction was carried out at 280°C and 0.05mmHg for about 60 minutes to obtain a master polymer with an intrinsic viscosity of 0.315. (2) Production of polymer In the method of Example 1-(2), the master polymer supplied to the line mixer was changed to the method of Example 2-(1).
Table 1 shows the quality and film haze of a polymer obtained by the same method as in Example 1-(2) except that the master polymer prepared by the method described above was used instead. It can be seen that the obtained polymer and film are of high quality. Example 3 (1) Preparation of master polymer Example 1 except that the polycondensation time was about 120 minutes
-A master polymer with an intrinsic viscosity of 0.512 was obtained using the same method as in (2). (2) Production of polymer Example 1-
A polymer with an intrinsic viscosity of 0.620 was obtained using the same method as in (2). This polymer was continuously taken out and continuously supplied to a mixing and kneading device installed after the second-stage polycondensation reaction device, and at the same time, the polymer prepared in advance by the method of Example 3-(1) was fed to the mixing and kneading device. A blended polymer was obtained by continuously supplying the blended polymer in a molten state at a ratio of 0.83 parts to 100 parts of the polymer passing through the master polymer (addition of 100 ppm as Mg atoms to the polyester). Table 1 shows the quality of this blend polymer and the film haze of a film obtained by forming the blend polymer in the same manner as in Example 1-(2). It can be seen that the obtained polymer and film are of high quality. 【table】

Claims (1)

[Claims] 1. When producing a polyester whose main repeating unit is ethylene terephthalate, the following master polymer or/
and a method for producing polyester, characterized in that a master polymer is added as Mg atoms in an amount of 30 to 400 ppm based on the total polyester. 0.1≦Mg≦3.0...() 1.2≦Mg/P≦20...() (In the formula, Mg is the weight% of the master polymer as Mg atoms in the added Mg compound,
Mg/P indicates the atomic ratio of Mg metal atoms to phosphorus atoms. ) Master polymer: When reacting dicarboxylic acids, mainly acids, and glycols, mainly ethylene glycol,
At any stage from before the start of the reaction until the intrinsic viscosity reaches 0.2, an amount of Mg compound and P compound that satisfies the above general formulas () and () is added at the same time, and then polycondensation is performed to prepare a compound with an intrinsic viscosity of 0.2. or more polymers. Master polymer: An acid component mainly consisting of a lower alkyl ester of terephthalic acid and a glycol component mainly consisting of ethylene glycol are reacted, and when the transesterification reaction is substantially completed, the above general formulas () and () are simultaneously combined. The intrinsic viscosity prepared by adding a satisfactory amount of Mg compound and P compound and then polycondensing
Polymer over 0.2.