JP5515196B2 - Polyester composition, polyester film comprising the same, and method for producing the same - Google Patents

Description

  The present invention relates to a polyester composition, a method for producing the same, and a film comprising the same. More specifically, the present invention relates to a film that is used in magnetic recording media, steel sheet bonding, and optical equipment and has few defects due to cyclic trimer precipitation, a polyester resin having excellent film forming properties that gives the film, and a method for manufacturing the same.

  A polyester resin is obtained by polycondensation of a dicarboxylic acid component and a diol component, and is a linear polymer produced from terephthalic acid or its ester-forming derivative and ethylene glycol, and is excellent in versatility and practicality. And is suitably used as a material for films, sheets, fibers and the like.

  However, precipitation of cyclic compounds is a problem in polyester molding processes and the like. For example, in the case of a base film for magnetic recording materials, the cyclic compound forms coarse protrusions by precipitation, thereby inhibiting magnetic recording. In the case of an optical base film, the cyclic compound is precipitated by heating in the processing step. Thus, optical turbidity and bright spots are generated, and in the case of a film for laminating steel sheets, haze is generated in the appearance after being laminated to the steel sheets.

  Various reports have been made on these cyclic compounds. For example, for polyethylene terephthalate, the main component of the cyclic compound is a cyclic trimer, which can be produced by an equilibrium reaction during the polycondensation reaction of polyethylene terephthalate. For example, it is reported by nonpatent literatures 1 and 2.

  Further, in the production of these polyethylene terephthalates, antimony compounds are mainly used as polycondensation catalysts. However, a polyester resin polymerized using an antimony compound as a polycondensation catalyst has a rate at which the cyclic trimer increases at the time of melt molding even when a polyester whose cyclic trimer content is reduced by solid phase polymerization or the like is used. Since it is fast, the amount of the cyclic trimer contained in the molded product tends to increase. Therefore, it is desired that antimony is not used at all or even if it is used, the amount is extremely low, or other metals are used.

  A polyester resin polymerized by using a germanium compound instead of the antimony catalyst is also known. However, although the rate of increase of the cyclic trimer at the time of melt molding is slightly slower than that of the antimony compound, the germanium compound is very expensive because it has a small reserve, and a catalyst that can be used as an alternative is desired. It was. Therefore, various polyester resins polymerized using an inexpensive titanium compound have been proposed. Titanium catalysts are more active than antimony catalysts and germanium catalysts, and can be used in small quantities. Furthermore, the rate of increase of cyclic trimers during melt molding is slower than antimony catalysts and germanium catalysts. Resins are an industrially valuable consideration. However, even if a polyester resin obtained by polymerization using a titanium catalyst and reducing the cyclic trimer by solid phase polymerization or the like is used, the effect of suppressing the increase in the cyclic trimer amount during melt molding cannot be said to be sufficient.

  In order to solve the above problems, a method of solid-phase polymerization of polyester chips polymerized with a specified amount and a specified type of polymerization catalyst (Patent Documents 1 and 2), a method of treating chips with an aqueous phosphorous solution (Patent Document 3), intrinsic viscosity And a method of setting the carboxyl group amount to a specific value (Patent Document 4) has been studied. However, in these methods, since the amount of the cyclic trimer in the obtained polyester fluctuates, it is very difficult to industrially obtain a certain quality polyester.

  In addition, the technology for reducing the number of cyclic compounds by such a solid-state polymerization method is also unsuitable as a raw material for producing molded articles with a low content of cyclic compounds because the polycondensation reaction of the polyester proceeds at the same time and the degree of polymerization increases. Met.

  That is, when the degree of polymerization of the polyester increases, the viscosity of the polymer at the time of molding increases during molding, which increases the load during extrusion, and the polymer temperature rises due to shearing heat generation, causing problems such as thermal decomposition. Will occur.

  Then, the heat processing which reduces a cyclic compound by heating in inert gas atmosphere are implemented.

  However, it has been clarified that the amount of cyclic trimer in the molded body cannot be sufficiently reduced even when a polyester polymerized with the above-described titanium catalyst and heat-treated is used.

As a result of intensive studies, the present inventors have clarified that a polyester molded article having a target cyclic trimer amount can be obtained by adding crystal nuclei to polyester. In other words, by including a crystal nucleating agent in polyester, shear heat generation occurs quickly during molding, and polyester can be melted in a short time, which shortens the time required for molding and suppresses the generated cyclic trimer. I found out that I can do it.
P.J.Flory "Polymer Chemistry" (Oka Koten, Kanamaru Kyodo, Maruzen Publishing Co., Ltd.) P90-97 Yuki Kazuo Saturated Polyester Resin Handbook (Nikkan Kogyo Shimbun) P167-178 JP 2001-048966 A JP 2003-089747 A JP 2004-346223 A JP 2006-096840 A

  An object of the present invention is to solve the above-described conventional problems, use a titanium catalyst, have a low cyclic trimer content, be suitable for extrusion molding, and have excellent film forming properties, a method for producing the same, and a polyester To provide a film.

The object of the present invention described above is a polyester comprising 90 mol% or more of ethylene terephthalate units, the polymerization catalyst metal compound is a titanium compound, and the content of ethylene terephthalate cyclic trimer is 0.4 wt% or less. And 0.1 to 1000 ppm of sodium acetate as a crystal nucleus added after esterification or after transesterification, and further comprising 1 to 1000 ppm of polyethylene glycol as a crystallization accelerator. Is done.

  According to the present invention, it is possible to provide a polyester composition having a small amount of cyclic trimer, a viscosity suitable for extrusion molding, and excellent film forming properties. The polyester composition of the present invention can prevent defects due to precipitation of a cyclic trimer when the molded body is used, and can be effectively used for fibers, films, bottles and the like. In particular, it is effective for magnetic recording media such as magnetic tapes, optical base materials such as optical films, food containers, steel sheet laminating, packaging applications, and electrical insulating films. In addition, spinning, film formation, and molding can be performed without changing the conditions that are normally used.Furthermore, contamination of the oil agent during yarn production by the cyclic trimer, contamination of casting / drawing equipment during film formation, etc. It becomes possible to prevent.

  Examples of the polyester resin composition of the present invention include polyethylene terephthalate, polyethylene isophthalate, polybutylene terephthalate, polypropylene terephthalate, polycyclohexanedimethylene terephthalate, and polyethylene naphthalate, and these copolymers may also be used. . Among these polyesters, polyethylene terephthalate and polyethylene naphthalate are preferable because of their good film properties, and polyethylene terephthalate is most preferable. Polyethylene terephthalate may be copolymerized, but 90 mol% or more of the polyester structural units are preferably ethylene terephthalate units. When the ethylene terephthalate component is less than 90 mol%, the crystallinity of the polyester is deteriorated, and it may be difficult to satisfy the crystallinity in the method for producing a polyester resin composition of the present invention.

  Examples of copolymer components of these polyesters include dicarboxylic acid components, glycol components, and polyfunctional components. Examples of dicarboxylic acid components include terephthalic acid, 2,6-naphthalenedicarboxylic acid, diphenyldicarboxylic acid, phthalic acid, and isophthalic acid. , Aromatic dicarboxylic acid components such as sodium sulfoisophthalate and their alkyl esters, aliphatic dicarboxylic acid components such as adipic acid, sebacic acid, and their alkyl esters, fats such as 1,4 cyclohexanedicarboxylic acid and their alkyl esters Mention may be made of cyclic dicarboxylic acid components. Examples of the glycol component include ethylene glycol, diethylene glycol, propylene glycol, butanediol, 1,4 cyclohexanedimethanol, neopentyl glycol, spiro glycol, ethylene oxide adduct of bisphenol A, isosorbate, and the like. Examples of the polyfunctional component include polyfunctional carboxylic acid components such as trimellitic acid and pyromellitic acid, and polyfunctional alcohols such as trimethylolpropane and pentaerythritol. Furthermore, hydroxycarboxylic acids such as p-hydroxybenzoic acid may be used as a copolymerization component.

  Furthermore, the above polyester contains at least one of an alkali metal salt derivative of a sulfonic acid that is non-reactive with the polyester, a polyalkylene glycol substantially insoluble in the polyester, and the like so as not to exceed 5% by weight. Or it may be copolymerized.

  In the present invention, it is preferable to add an antioxidant to the polyester resin composition. As the antioxidant, a phenol-based antioxidant, a phosphorus-based antioxidant, an amine-based antioxidant, a lactone-based antioxidant, and the like are suitable. In particular, phosphorus-based antioxidants are also preferable from the viewpoint of suppressing cyclic trimer regeneration when the polyester resin is melted. The phosphorus-based antioxidant is a phosphorus compound that is conventionally added in the production process of polyester, and is not particularly limited, but is not limited to normal phosphoric acid, phosphorous acid, trimethyl phosphate, triethyl phosphate, tri-n-butyl phosphate, triethyl phosphate. Phonoacetate is preferable.

  In the present invention, the content of the cyclic trimer in the polyester is 0.4% by weight or less, preferably 0.3% by weight or less. When the content of the cyclic trimer in the polyester composition exceeds 0.4% by weight, the cyclic trimer is precipitated from the surface when formed into a film or the like, and the precipitate becomes a surface defect.

  Since the cyclic trimer cannot exist in the crystal part of the polyester, if the crystallization of the polyester proceeds during the film forming process, it will be unevenly distributed in the amorphous part. The cyclic trimer unevenly distributed at a high concentration in the amorphous part is in a state of being easily precipitated on the polyester surface, and is precipitated when the amount of the cyclic trimer in the amorphous part exceeds about 1.2% by weight. For this reason, if the crystallinity of the polyester resin composition is c% (volume%), the content (% by weight) of the cyclic trimer is smaller than 1.2 × ((100−c) / 100). It is preferable. If the film has a crystallinity of 50%, the content of the cyclic trimer is preferably less than 0.6% by weight, and more preferably less than 0.5% by weight.

  The polyester resin composition of the present invention has a carboxyl end group in the range of 20 to 50 equivalent / ton. In the case of less than 20 equivalents / ton, the adhesion between the stretching roll and the film is lowered in the film forming step and the film becomes slippery, and the film surface is easily damaged. Furthermore, the adhesiveness when processing the film surface is insufficient. On the other hand, when it exceeds 50 equivalents / ton, the winding property of the film is lowered, the film is likely to be damaged, and the precipitation of the cyclic trimer tends to increase. The preferred range is 25-40 equivalents / ton, and the most preferred range is 28-40 equivalents / ton.

  The polyester resin composition of the present invention has an intrinsic viscosity in the range of 0.50 to 0.75. In the present invention, the intrinsic viscosity is measured at 25 ° C. using orthochlorophenol as a solvent. However, if it is less than 0.50, it becomes insufficient mechanical properties as a molded product, whereas if it exceeds 0.75, it is melt extruded. In this case, the shear heat generation becomes remarkable and may cause thermal decomposition of the polymer. A preferred range is 0.55 to 0.70, and most preferred is a range of 0.60 to 0.68.

  As a titanium catalyst used as a polymerization catalyst for the polyester of the present invention, a titanium chelate compound or a tetraalkoxytitanium compound is preferable. For example, titanium chelate or tetraisopropyl such as titanium acetylacetonate, titanium tetraacetylacetonate, titanium octylene glycolate, titanium lactate, titanium ethyl acetoacetate, titanium citrate, titanium oxalate, titanium lactate, titanium peroxocitrate ammonium ammonium Alkyl titanates such as titanate, tetrabutyl titanate, tetra (2-ethylhexyl) titanate, and tetramethyl titanate can be mentioned. Among them, titanium chelate and tetrabutyl titanate are preferably used.

  The crystal nucleating agent may be inorganic or organic. Specifically, for example, clays such as talc and clay; metal oxides such as zinc oxide, magnesium oxide, alumina, and iron oxide; carbonates (eg, magnesium carbonate), silicates, sulfates (eg, barium sulfate) Etc.), inorganic salts such as phosphates; metal salts of monocarboxylic acids (eg lithium salts, sodium salts, magnesium salts, calcium salts, barium salts etc.), metal salts of benzoic acids (eg sodium salts, potassium salts, calcium) Organic acid salts such as metal salts of organic phosphorus compounds (eg, magnesium salts and zinc salts); polymer powders such as ionomers, alkali metal salts of polyester oligomers, wholly aromatic polyesters; carbon black, graphite, An inorganic simple substance powder such as aluminum can be mentioned. These crystal nucleating agents can be used alone or in combination of two or more. Of these crystal nucleating agents, sodium acetate is preferred. The one having an average particle diameter of 0.1 to 100 μm is most preferably used.

  A crystallization accelerator can also be added. As the crystallization accelerator, a low-molecular compound or a high-molecular compound that acts as a plasticizer for PET can be used, and those having a melting point of 80 ° or less can be suitably used. Examples of the low molecular weight compound include ketones such as benzophenone; halogenated hydrocarbons such as tetrachloroethane; esters such as neopentyl glycol dibenzoate, triphenyl phosphate and phthalate; amides such as N-substituted aromatic amides. There can be mentioned. Examples of the polymer compound include caprolactone and other various aliphatic polyesters; end-capped aliphatic polyesters; polyglycols such as polyethylene glycol, polypropylene glycol, and polybutylene glycol; end-capped polyglycols; alicyclic carboxylic acid Mention may be made of polyolefins such as modified polyolefins; polyamides such as nylon 6. These crystallization accelerators can be used alone or in combination of two or more.

  The addition amount of the crystal nucleating agent in the present invention is preferably 0.1 to 1000 ppm, more preferably 50 to 600 ppm with respect to PET. When the addition amount is 0.1 ppm or less, the amount of crystal nuclei generated in the polymer is not sufficient, the rate of generation of shear heat generation is slow at the time of melt molding, and the amount of cyclic trimer produced is increased due to the longer melting time. Will increase. Moreover, when 1000 ppm or more is added, since the amount of crystal nuclei produced | generated in a polymer is too much and becomes a foreign material, it is not preferable. Moreover, it is preferable that the addition amount of a crystallization accelerator is 1-1000 ppm with respect to PET.

  The addition amount of the crystal nucleating agent and the crystallization accelerator differs depending on the type of PET used. However, if the amount is too small, the crystallinity tends to be small, and conversely if too large, the crystallinity increases. In addition, the original physical properties of PET are likely to be impaired, and the mechanical strength of the obtained molded product tends to decrease.

  A metal salt soluble in ethylene glycol such as sodium acetate can be obtained by heating ethylene glycol to 50 to 100 ° C., stirring it for 30 minutes or more, and then adding it to the reaction system to obtain a crystal nucleus having an excellent particle size. When it is 50 ° C. or lower or 100 ° C. or higher, crystal nuclei are not formed well. The ethylene glycol solution can be added before or during melt polycondensation.

  A method for obtaining the above-described polyester resin composition will be described below.

The crystal nucleating agent and the crystallization accelerator can be added before and / or during the esterification reaction or transesterification reaction and / or during and / or during the polycondensation reaction. Can be manufactured by any process. (1) A process in which terephthalic acid and ethylene glycol are used as raw materials, a low polymer is obtained by direct esterification reaction, and a high molecular weight polymer is obtained by subsequent polycondensation reaction, and (2) dimethyl terephthalate and ethylene glycol are used as raw materials. In this process, a low polymer is obtained by a transesterification reaction, and a high molecular weight polymer is obtained by a subsequent polycondensation reaction. In the present invention, either method (1) or (2) can be adopted. (1) or (2) In both methods, it is possible to add a nucleating agent after the esterification reaction or ester exchange reaction, can be further added crystallization accelerator. Furthermore, an antioxidant, an antiblocking agent, etc. can be added before reaction during reaction as needed.

  The intrinsic viscosity of the polyester resin can determine the end point of polymerization by the stirring torque of the polymer. When the stirring torque is high, the polymer has a high melt viscosity and a high intrinsic viscosity. What is necessary is just to set the end point determination stirring torque of a superposition | polymerization apparatus so that it may become the target intrinsic viscosity.

  The obtained polyester resin after polymerization may be discharged in the form of a strand from the lower part of the polymerization apparatus and cut with a cutter while cooling with water.

  The obtained polyester resin is preferably dried before heat treatment. Drying may be performed by heating the chip to 120 ° C. to 180 ° C. under reduced pressure or flowing hot air for 2 hours or more. By such a drying process, the crystallinity of the polyester resin can be increased to 30% or more.

  The heat processing method for obtaining the polyester resin composition of this invention is demonstrated below.

  A method of heating at a temperature of 190 ° C. or more and 250 ° C. or less for 0.5 hours or more and 60 hours or less in an inert gas atmosphere with a pressure of 960 hPa or more and 1160 hPa or less and a flow rate of less than 0.1 liter / hr per kg of polyester Can be preferably employed.

  Examples of the inert gas atmosphere include rare gases such as helium, neon, and argon, nitrogen gas, and carbon dioxide gas. Of these, nitrogen gas is easily available and can be preferably used. The concentration of oxygen and moisture contained in these inert gases is preferably 500 ppm by volume or less. When the concentration of oxygen or moisture exceeds 500 ppm, the polyester is likely to be deteriorated, which causes coloring of the polyester.

  In the above treatment, the amount of terminal carboxyl groups tends to increase as the pressure increases. If the pressure exceeds 1160 hPa, the terminal carboxyl group concentration increases too much, or the winding property of the film deteriorates and the film is damaged. And the precipitation of the cyclic trimer tends to increase.

  On the other hand, the lower the pressure, the closer to solid phase polymerization, the lower the amount of terminal carboxyl groups tends to decrease. When the pressure is less than 960 hPa, the adhesion between the stretching roll and the film decreases in the film forming process, and it becomes slippery. The film surface tends to be damaged, and it tends to be difficult to suppress the precipitation of the cyclic trimer. 1000 hPa-1100 hPa is more preferable.

  When the flow rate of the inert gas is 0.1 liter / hr or less per kg, so-called solid-phase polymerization does not occur. Therefore, the terminal carboxyl group concentration of the polyester does not decrease, and the suppression of the cyclic trimer is preferable. .

  About processing time, it is preferable that it is 0.5 hour or more and 60 hours or less because precipitation suppression of a cyclic trimer is favorable.

  The intrinsic viscosity of the polyester subjected to the heat treatment is in the range of 0.50 to 0.75. If it is less than 0.50, the cyclic trimer tends to decrease, but the obtained polyester molded product has insufficient mechanical properties. When the intrinsic viscosity exceeds 0.75, the rate of reduction of the cyclic trimer is slow, and a long-time heat treatment is required, which is economically disadvantageous. The intrinsic viscosity is preferably in the range of 0.55 to 0.70, more preferably in the range of 0.60 to 0.68. A polyester resin having an intrinsic viscosity in such a range can be obtained by controlling the polymerization stirring torque in ordinary melt polymerization.

Carboxyl terminal group content of the polyester is subjected to a heat treatment in the range of 20~50eq / 10 ⁶ g, more preferably 25~40eq / ¹⁰ 6 g, and most preferably 28~40eq / 10 ⁶ g. If it is 20 eq / 10 ⁶ g or less, the amount of carboxyl terminal groups of the polyester after the heat treatment is small, which causes tearing during film formation. Moreover, when it is 50 eq / 10 ⁶ g or more, the decrease rate of the cyclic trimer during the heat treatment is undesirably low.

  The polyester resin subjected to the heat treatment has a crystallinity of 30% or more. Since the cyclic trimer exists in the amorphous part of the polyester resin, the cyclic trimer is concentrated in the amorphous part as crystallization proceeds. In the polyester in such a state, the cyclic trimer supersaturated in the amorphous part is reduced to the equilibrium amount, so that the amount of the cyclic trimer as the whole polyester resin can be reduced. When the degree of crystallinity is less than 30%, a large cyclic trimer reduction effect cannot be expected because the supersaturation degree of the cyclic trimer in the amorphous part is insufficient. Note that the crystallinity can be increased even during the heat treatment, and it is preferable that the crystallinity be 70% or higher in the end. In the method of setting the crystallinity to 30% or more, it is preferable to provide a crystallization treatment step before the heat treatment. For example, the polyester resin is heated at 120 to 180 ° C. for 2 hours or more under reduced pressure or hot air flow. Is preferred. You may combine this process with a drying process.

The crystallinity of the polyester resin can be confirmed by a change in density. For example, if the density of the complete amorphous part is 1.335 g / cm ³ and the crystal density is 1.455 g / cm ³ , the crystallinity = (chip). Density-1.335) / (1.455-1.335).

  The temperature at which the heat treatment is performed is in the range of 190 ° C to 250 ° C. If it is less than 190 ° C, the cyclic trimer reduction rate is slow, resulting in a long treatment time, which is economically disadvantageous. On the other hand, if the treatment temperature exceeds 250 ° C, the polyester resin is likely to be fused, and further heat Since the deterioration also occurs, the coloring of the polyester becomes intense. A preferable temperature range is 200 ° C to 240 ° C, and further a range of 220 ° C to 235 ° C is preferable.

  The time for performing the heat treatment is in the range of 0.5 to 60 hours. Although the time varies depending on the amount of the polymerization catalyst remaining in the polyester resin and the treatment temperature, it is difficult to sufficiently reduce the cyclic trimer if it is less than 0.5 hour, and it is economically disadvantageous if it exceeds 60 hours. It becomes. By the above production method, only the cyclic trimer can be reduced without increasing the degree of polymerization of the polyester and without coloring it. More preferably, it is 10 to 50 hours, and most preferably 15 to 35 hours.

  As the heat treatment apparatus used for the above heat treatment, those capable of uniformly heating the polyester are preferable. Specifically, a stationary dryer, a rotary dryer, a fluid dryer, a dryer having various stirring blades, a continuous tower dryer, or the like can be used.

  In the polyester film obtained from the polyester resin composition of the present invention, the cyclic trimer is less likely to precipitate on the film surface even during long-term storage, and even if the film is processed in a heated state, the cyclic trimer remains on the film surface. Since it is difficult to deposit, it is suitable for magnetic recording media, optical and packaging films. If it is desired to suppress the precipitation of the cyclic trimer only on the specific surface of the film, a laminated film can be formed. If the polyester resin of this invention is laminated | stacked, the cyclic | annular trimer precipitation of not only the surface which laminated | stacked but the surface which is not laminated | stacked can also be decreased. When laminating, it is preferable that at least one surface contains the above-described polyester resin composition of the present invention.

  The polyester resin after the heat treatment is cooled and taken out from the tank.

  When forming into a film, a polyester resin is put into an extruder, and a molten sheet is continuously extruded from a slit base provided in the extruder. The extruded molten sheet is brought into close contact with the mirror cooling drum by an electrostatic application method to obtain an amorphous cast sheet. In addition, when setting it as a laminated | multilayer film, a polymer can be fuse | melted using two or more extruders, and the fuse | melted polymer can be united and laminated | stacked within a laminated block or a nozzle | cap | die.

  The obtained amorphous sheet is then stretched biaxially by various stretching methods such as a roll stretching method or a tenter stretching method and wound up. The order of stretching may be either sequential or simultaneous.

  Here, stretching in the longitudinal direction refers to stretching for imparting a molecular orientation in the longitudinal direction to the film. For example, the stretching is performed by using a stretching roll depending on a difference in peripheral speed of the roll. This stretching may be performed in one stage, or may be performed in multiple stages using a plurality of roll pairs. The stretching ratio is preferably 2 to 15 times, more preferably 2.5 to 7 times.

  Stretching in the transverse direction refers to stretching for giving the film an orientation in the width direction. For example, the film is stretched in the width direction by using a tenter while gripping both ends of the film with clips. The stretching ratio is preferably 2 to 10 times.

  In the case of simultaneous biaxial stretching, the film is stretched simultaneously in the longitudinal direction and the lateral direction while being conveyed while being gripped by clips in the tenter, and this method may be used.

  The biaxially stretched film is preferably subjected to a heat treatment at a temperature not lower than the stretching temperature and not higher than the melting point in the tenter in order to impart flatness and dimensional stability. After uniform cooling, the film is cooled to room temperature and wound. In the film of the present invention, the heat treatment temperature is preferably 120 to 240 ° C. from the viewpoints of flatness and dimensional stability.

  In addition, when forming an easy-adhesion layer, particle layer, etc., the coating components may be applied in-line before stretching or between longitudinal stretching and lateral stretching using a coating technique such as gravure coating or metering bar. It is also possible to perform off-line coating after stretching.

  The polyester resin composition and polyester film of the present invention are suitable for films for magnetic recording media and optical substrates, films for laminating steel sheets, and packaging films.

Hereinafter, the present invention will be described in more detail with reference to examples.
(1) Determination of cyclic trimer in polyester
A 20 mg sample is dissolved in OCP (orthochlorophenol) at 150 ° C. for 30 minutes and cooled at room temperature. Thereafter, 1,4-diphenylbenzene is added as an internal standard, 2 ml of methanol is added, the polymer is separated with a high-speed centrifuge, and the liquid layer portion is measured.

Device: Shimadzu LC-10ADvp
Column: YMC-Pack ODS-2 150 mm x 4.6 mm
Column temperature: 40 ° C
Flow rate: 1.3ml / min
Injection amount: 10 μm
Detector: UV240nm
Eluent: Liquid A (pure water): Liquid B (methanol) = 25: 75
(2) Measurement of crystal nucleus content Polyester was dissolved in orthocresol / chloroform (weight ratio 7/3) at 90 to 100 ° C. and centrifuged with a centrifuge, and the precipitate was orthocresol / chloroform (weight ratio 7 / After washing in 3) and drying, the weight was measured.
(3) Intrinsic viscosity
Measurement was performed at 25 ° C. using orthochlorophenol.
(4) Carboxy end group concentration
The polyester was dissolved in orthocresol / chloroform (weight ratio 7/3) at 90 to 100 ° C., and the potential difference was measured with an alkali.
(5) Cyclic trimer forced precipitation test
After heating a vertical and horizontal 5cm square film at 150 ° C for 30 minutes in a hot air oven, the surface of the film is observed with a scanning electron microscope, and the number of cyclic trimer precipitates with a diameter of 1µm or more per 100µm square is counted. did.
(Reference Example) Method for synthesizing sodium lactate sodium chelate compound
Lactic acid (226.8 g, 2.52 mol) was dissolved in warm water (371 g) in a 3 L flask equipped with a stirrer, condenser and thermometer. To this stirred solution, titanium tetraisopropoxide (285 g, 1.00 mol) was slowly added from a dropping funnel. The mixture was heated to reflux for 1 hour to produce a cloudy solution from which the isopropanol / water mixture was distilled under reduced pressure. The product was cooled to a temperature below 70 ° C. and a 32 wt / wt% aqueous solution of NaOH (380 g, 3.04 mol) was slowly added via a dropping funnel to the stirred solution. The resulting product was filtered and then mixed with ethylene glycol (504 g, 80 mol) and heated under reduced pressure to remove isopropanol / water and a slightly cloudy light yellow product (titanium content 5 .6% by weight). {Titanium lactate sodium chelate compound}
Example 1
100 parts by weight of dimethyl terephthalate and 62 parts by weight of ethylene glycol were charged into a transesterification reactor and melted at 150 ° C. Subsequently, 0.05 part by weight of magnesium acetate tetrahydrate was added, and transesterification was carried out while distilling methanol. The temperature of the reaction product was raised to 235 ° C. over 3 hours, and after the transesterification reaction was completed, 0.025 parts by weight of sodium acetate and 0.01 parts by weight of polyethylene glycol were stirred at 80 ° C. for 1 hour, Added. Subsequently, the sodium titanium lactate chelate compound prepared in the reference example was added as a titanium element so as to be 5 ppm (weight) with respect to dimethyl terephthalate. Thereafter, the reaction product was transferred to a polycondensation apparatus.

  While stirring the low polymer at 30 rpm, the reaction system was gradually heated from 235 ° C. to 285 ° C. and the pressure was reduced to 130 Pa. The time to reach the final temperature and final pressure was both 90 minutes. When the predetermined stirring torque was reached, the reaction system was returned to normal pressure with nitrogen gas, the polycondensation reaction was stopped, discharged into cold water as a strand, and immediately cut to obtain a polyester chip.

  The obtained polyester chip had an intrinsic viscosity of 0.64 and a cyclic trimer content of 1.2% by weight.

  This polyester was dried at 170 ° C. under reduced pressure to obtain a polyester having a crystallinity of 60%. Next, 100 parts by weight of the dried chips were charged into a rotary heat treatment machine, the interior was filled with nitrogen gas having a moisture content and an oxygen concentration of 40 ppm or less, and the internal pressure was 1024 hPa. Next, the temperature in the tank was raised, and after maintaining the temperature for 20 hours from 230 ° C., the chip was taken out.

  The obtained chip had an intrinsic viscosity of 0.64 dl / g, a cyclic trimer amount of 0.25% by weight, and a crystallinity of 70%. Other characteristics are shown in Table 1.

  The processed chip was put into an extruder, melted at 285 ° C., and extruded from the die into a sheet. The molten sheet was cooled by being brought into close contact with a mirror drum whose surface temperature was controlled at 25 ° C. by an electrostatic application method. Next, the obtained amorphous polyester sheet was stretched 3.3 times in the longitudinal direction by a stretching roll heated to 90 ° C., and then stretched 3.8 times in the width direction at 110 ° C. by a tenter type stretching machine. The stretched film was heat-set at 230 ° C. and wound on a roll. The film thickness was 30 μm, and the content of the cyclic trimer contained in the film was 0.42% by weight. When a cyclic trimer forced precipitation test was performed, no cyclic trimer precipitation was observed.

Examples 2 and 3
Polymerization was carried out in the same manner as in Example 1 except that the polymerization catalyst in Example 1 was changed to tetra-n-butyl titanate and titanium oxalate, and the chip was heated to form a film.

Examples 4-7
Only the amount of sodium acetate added in Example 1 was changed, and polymerization was carried out in the same manner.

Examples 8 and 9
A film was formed in the same manner as in Example 1 except that the polymerization termination determination torque was changed and the intrinsic viscosities were changed to 0.50 dl / g and 0.75 dl / g, respectively.
Due to the low or high intrinsic viscosity of the polymer, it was difficult to make the thickness of the extruded sheet uniform, and tearing occurred during film formation.

Examples 10-15
A film was prepared in the same manner as in Example 1 except that the heat treatment conditions were changed as shown in Table 1.

Reference Example 16
A film was prepared in the same manner as in Example 1 except that talc was added instead of sodium acetate.

Comparative Example 1
A film was obtained in the same manner as in Example 1 except that sodium acetate was not added. A large amount of cyclic trimer was deposited, which was not suitable as a product.

Comparative Example 2
Only the amount of sodium acetate added in Example 1 was changed, and polymerization was carried out in the same manner. Many foreign bodies were seen. Moreover, the cyclic trimer precipitation amount was large, and it was not suitable as a product.

Comparative Example 3
A film was formed in the same manner as in Example 1 except that the heat treatment conditions were changed as shown in Table 1. A large amount of cyclic trimer was deposited, which was not suitable as a product.

Comparative Examples 4 and 5
A film was prepared in the same manner as in Example 1 except that the polymerization catalyst was changed as shown in Table 1. A large amount of cyclic trimer was deposited, which was not suitable as a product.

  The results are summarized in Table 1.

Claims (4)

90 mol% or more of a polyester comprising an ethylene terephthalate unit, the polymerization catalyst metal compound is a titanium compound, the ethylene terephthalate cyclic trimer content is 0.4 wt% or less, and after esterification or transesterification A polyester composition characterized by containing 0.1 to 1000 ppm of sodium acetate as a crystal nucleus added later and further containing 1 to 1000 ppm of polyethylene glycol as a crystallization accelerator.   A biaxially stretched polyester film comprising the polyester composition according to claim 1, wherein the ethylene terephthalate cyclic trimer content is 0.6 wt% or less.   A laminated polyester film, wherein at least one surface is a layer comprising the polyester composition according to claim 1. Above 90 mol% is ethylene terephthalate units, and an intrinsic viscosity of 0.50~0.75dl / g, polymerization catalyst metal compound is a titanium compound, and as the added crystal nuclei after the esterification or after ester interchange It contains 0.1 to 1000 ppm of sodium acetate , and further contains polyester containing 1 to 1000 ppm of polyethylene glycol as a crystallization accelerator under an inert gas atmosphere in the range of 960 to 1,160 hPa at a temperature of 190 ° C. to 250 ° C. A method for producing a polyester composition that is heated for 5 to 60 hours.