JPWO2016104689A1 - POLYESTER RESIN PELLET, MANUFACTURING METHOD THEREOF - Google Patents

Abstract

Polyester resin pellets obtained by subjecting terephthalic acid, ethylene glycol, cyclohexanedimethanol or bisphenol A ethylene oxide adduct, and polyvalent ester to polycondensation by melt-kneading and then solid-phase polymerization, wherein the polyvalent ester is A carboxylic acid ester of a trivalent or higher polyol, wherein the carboxylic acid has a hindered phenol group, and the content of the component derived from the polyvalent ester in the polyester resin is 0.005 to 0.00. Polyester resin pellets having a mass percentage of 04 mass% and an intrinsic viscosity of the polyester of 0.9 to 1.5 dl / g are provided. Such polyester resin pellets are excellent in draw-down resistance, and molded products obtained using the polyester resin pellets have good impact resistance and color tone.

Description

  The present invention relates to a polyester resin pellet suitable as a raw material for extrusion blow molding, a method for producing the same, and a molded product comprising the same.

  Polyester resins such as polyethylene terephthalate resin are excellent in properties such as transparency, mechanical properties, gas barrier properties, and flavor barrier properties. Furthermore, the polyester resin is less sanitary for residual monomers and harmful additives when formed into a molded product, and is excellent in hygiene and safety. For this reason, polyester resins have been widely used in recent years as hollow containers for filling juices, soft drinks, seasonings, oils, cosmetics, detergents, etc. as an alternative to vinyl chloride resins that have been used in the past, taking advantage of these properties. It is used.

  As a molding method for producing a hollow molded article made of polyester resin, a resin melted and plasticized through a die orifice is extruded as a cylindrical parison, and the parison is sandwiched between molds while it is in a softened state. An extrusion blow molding method is known in which molding is performed by blowing the fluid. Compared with the injection blow molding method, this method is simpler and does not require advanced technology for the production and molding of the mold. Suitable for varieties and small volume production. In addition, there is an advantage that it is possible to manufacture a molded product having a complicated shape having a thin object, a deep object, a large object, a handle, and the like.

  On the other hand, since general-purpose polyester resins generally have a low melt viscosity, when extrusion blow molding is performed, it is difficult for the parison after extrusion to be drawn down and shaped. Therefore, in general, the extrusion blow bottle molding polyester resin has been provided with drawdown resistance by a method of adding a small amount of a crosslinking agent, but even if it can be molded, the resulting molded article has insufficient impact resistance. There was a case. In general, a polyester resin is easily oxidized when heated for a long period of time, such as during melt molding or solid phase polymerization, and causes thermal deterioration such as yellowing, molecular weight reduction, and generation of a gel component.

  In order to solve these problems, various proposals regarding polyester resins suitable for extrusion blow molding and thermoforming have been made. As one of such conventional techniques, a substance to which a hindered phenol-based antioxidant is added (see Patent Documents 1 to 3) is known.

  In Patent Document 1, a terephthalic acid unit, an ethylene glycol unit, and a 1,4-cyclohexanedimethanol unit are the main components, and the content of the hindered phenol antioxidant is 0.2 to 1.0% by mass. Copolyesters in which the contents of germanium element and antimony element (catalyst) satisfy predetermined conditions are described. In Patent Document 1, by using a catalyst having a predetermined composition and a hindered phenol-based antioxidant, a decomposition reaction during polymerization is suppressed, polymerization proceeds promptly, and color tone and transparency are not deteriorated. It is described that a polyester having a high degree of polymerization can be obtained and thermal decomposition at the time of molding can be suppressed, so that color tone deterioration after molding does not occur. In Patent Document 2, a hindered phenol-based antioxidant is added to 100 parts by weight of a polyester resin containing a dicarboxylic acid unit and a diol unit, and 1 to 60 mol% of the diol unit is a diol unit having a cyclic acetal skeleton. A polyester resin composition containing 0.05 to 1 part by weight is described. And it is described in patent document 2 that generation | occurrence | production of yellow coloring and a gel component can be suppressed by adding the said antioxidant. However, molded articles obtained by extrusion blow molding the polyester resins described in Patent Documents 1 and 2 have insufficient impact resistance.

  In Patent Document 3, polyester (A) pellets mainly composed of terephthalic acid units and ethylene glycol units and polyesters mainly composed of terephthalic acid units, ethylene glycol units and cyclohexanedimethanol units by melt polymerization (B ) Of the polyester (A) pellet, the polyester (B) pellet, and the hindered phenol antioxidant are melt-kneaded and then the polyester resin composition is subjected to solid-phase polymerization. A manufacturing method is described. However, since the method has many steps, it is not easy to produce pellets with high productivity. Moreover, the transparency of the molded product obtained using the said pellet may be inadequate.

JP 2002-338664 A JP 2007-326890 A JP 2011-252087 A

  The present invention has been made to solve the above-described problems, and can be used for the production of thick-walled molded products and extrusion blow molding, which can provide molded products having excellent drawdown resistance, impact resistance and color tone. It is an object of the present invention to provide a polyester resin pellet suitable as a raw material for the same and a method for producing the same.

  The above-mentioned problem is a polyester resin pellet obtained by subjecting terephthalic acid, ethylene glycol, cyclohexanedimethanol or bisphenol A ethylene oxide adduct, and polycondensation by melt-kneading a polyvalent ester, followed by solid-phase polymerization, The polyvalent ester is a carboxylic acid ester of a trihydric or higher polyol, and the carboxylic acid has a hindered phenol group, and the dicarboxylic acid unit in the polyester is mainly composed of terephthalic acid units. The diol unit mainly comprises an ethylene glycol unit and a unit derived from a cyclohexanedimethanol unit or a bisphenol A ethylene oxide adduct, and the content of the ethylene glycol unit relative to the total of the diol units is 75 to 98 mol%. The content of the cyclohexanedimethanol unit and the unit derived from the bisphenol A ethylene oxide adduct is 2 to 25 mol%, and the content of the component derived from the polyvalent ester in the polyester resin is 0.005 to 0.005. It is solved by providing polyester resin pellets having a mass viscosity of 04% by mass and an intrinsic viscosity of the polyester of 0.9 to 1.5 dl / g.

  A molded product formed by extrusion blow molding using the pellets is a preferred embodiment of the present invention.

  The above-mentioned problem is that after the terephthalic acid, ethylene glycol, cyclohexanedimethanol or bisphenol A ethylene oxide adduct, and the polyvalent ester are subjected to condensation polymerization by melt kneading to obtain an intermediate pellet, the intermediate pellet This can also be solved by providing a method for producing the polyester resin pellets by solid-phase polymerization.

  The polyester resin pellet of the present invention is excellent in draw down resistance at the time of extrusion blow molding, and a molded product having good impact resistance and color tone is obtained. According to the manufacturing method of the present invention, such a polyester resin pellet can be easily manufactured.

It is the figure which showed how to obtain | require a half crystallization time.

  Hereinafter, embodiments of the present invention will be described, but the present invention is not limited thereto.

  The polyester resin pellet of the present invention is obtained by subjecting terephthalic acid, ethylene glycol, cyclohexanedimethanol or bisphenol A ethylene oxide adduct, and polyvalent ester to condensation polymerization by melt-kneading and then solid-phase polymerization. The polyvalent ester is a carboxylic acid ester of a trihydric or higher polyol, and the carboxylic acid has a hindered phenol group, and the dicarboxylic acid unit in the polyester is mainly composed of a terephthalic acid unit, The diol unit in the polyester is mainly composed of an ethylene glycol unit and a unit derived from a cyclohexanedimethanol unit or a bisphenol A ethylene oxide adduct, and the content of the ethylene glycol unit relative to the total of the diol units is 75 to 98 mol. The content of the cyclohexanedimethanol unit and the unit derived from the bisphenol A ethylene oxide adduct is 2 to 25 mol%, and the content of the component derived from the polyvalent ester in the polyester resin is 0.005 to 0.04. The intrinsic viscosity of the polyester is 0.9 to 1.5 dl / g. In the present invention, the polyester resin pellet may be referred to as a first pellet.

  The polyester of the present invention is derived from a dicarboxylic acid unit mainly composed of a terephthalic acid unit, an ethylene glycol unit, a diol unit mainly composed of a cyclohexanedimethanol unit or a unit derived from a bisphenol A ethylene oxide adduct, and derived from the polyvalent ester. It consists mainly of units.

  The content of terephthalic acid units in the polyester of the present invention is usually 80 mol% or more, preferably 90 mol% or more, more preferably 95 mol% or more, based on the total of dicarboxylic acid units in the polyester. More preferably, the dicarboxylic acid units in the polyester are substantially only terephthalic acid units.

  The polyester of the present invention contains cyclohexanedimethanol units or bisphenol A ethylene oxide adduct-derived units as diol units other than ethylene glycol units. Here, the said polyester should just contain at least one of the unit derived from a cyclohexane dimethanol unit and a bisphenol A ethylene oxide adduct as diol units other than an ethylene glycol unit. By containing a cyclohexanedimethanol unit or a unit derived from a bisphenol A ethylene oxide adduct as a diol unit other than an ethylene glycol unit, the melting point of the polyester can be lowered, so that the molding temperature in direct blow molding can be lowered. it can. From the viewpoint of impact resistance at low temperature, the polyester preferably contains a cyclohexanedimethanol unit as a diol unit other than the ethylene glycol unit. On the other hand, from the viewpoint of chemical resistance to a high concentration of alcohol, the polyester preferably contains a unit derived from a bisphenol A ethylene oxide adduct as a diol unit other than the ethylene glycol unit.

  The cyclohexanedimethanol unit in the polyester may be at least one divalent unit selected from 1,2-cyclohexanedimethanol unit, 1,3-cyclohexanedimethanol unit and 1,4-cyclohexanedimethanol unit. . Among them, cyclohexanedimethanol is easy to obtain, easy to make the polyester crystalline, difficult to stick between pellets during solid phase polymerization, and further improves the impact resistance of the resulting molded product. The unit is preferably 1,4-cyclohexanedimethanol unit.

  The cyclohexanedimethanol unit has a cis isomer and a trans isomer, but the ratio of the cis isomer and the trans isomer in the cyclohexanedimethanol unit in the polyester is not particularly limited. Among them, in the cyclohexanedimethanol unit in the polyester, the ratio of the cis isomer to the trans isomer is in the range of 0: 100 to 50:50. This is preferable from the viewpoint that sticking between the pellets hardly occurs and the impact resistance of the obtained molded product is further improved.

  The unit derived from the bisphenol A ethylene oxide adduct in the polyester is one in which at least one ethylene oxide is added to each hydroxyl group of bisphenol A. The addition amount of ethylene oxide is usually 2.0 to 4.0 mol with respect to 1 mol of bisphenol A.

  The total content of the cyclohexanedimethanol unit and the unit derived from the bisphenol A ethylene oxide adduct in the polyester of the present invention is 2 to 25 mol% with respect to the total of diol units in the polyester. When the total content of the cyclohexanedimethanol unit and the unit derived from the bisphenol A ethylene oxide adduct is less than 2 mol%, the impact resistance and transparency of the obtained molded product are lowered. The content is preferably 4 mol% or more, and more preferably 8 mol% or more. On the other hand, when the content exceeds 25 mol%, it becomes difficult to increase the solid-phase polymerization temperature, the productivity is lowered, and the color tone of the obtained molded product is deteriorated. The content is preferably 18 mol% or less.

  Content of the ethylene glycol unit in the polyester of this invention is 75-98 mol% with respect to the sum total of the diol unit in the said polyester. When the content of the ethylene glycol unit is less than 75 mol%, it is difficult to increase the solid phase polymerization temperature, the productivity is lowered, and the color tone of the obtained molded product is deteriorated. The content of the ethylene glycol unit is preferably 82 mol% or more. On the other hand, when the content of the ethylene glycol unit exceeds 98 mol%, the impact resistance and transparency of the obtained molded product are lowered. The content of the ethylene glycol unit is preferably 96 mol% or less, and more preferably 92 mol% or less.

  The total content of ethylene glycol units, cyclohexanedimethanol units and units derived from bisphenol A ethylene oxide adduct in the polyester of the present invention is usually 80 mol% or more with respect to the total of diol units in the polyester. 90 mol% or more is preferable, and 95 mol% or more is more preferable. Usually, the polyester of the present invention contains 1 to 5 mol% of diethylene glycol units, which are by-products during the condensation polymerization reaction, based on the total of diol units in the polyester.

  The unit derived from the polyvalent ester in the polyester is a carboxylic acid ester of a trihydric or higher polyol, and the carboxylic acid has a hindered phenol group, terephthalic acid, ethylene glycol, and cyclohexanedimethanol or It is contained in the polyester by melt-kneading together with bisphenol A ethylene oxide adduct to cause condensation polymerization. In the condensation polymerization, the polyol unit of the polyvalent ester and the carboxylic acid unit having a hindered phenol group are contained in the polyester by a transesterification reaction. The polyol unit is contained in the main chain, branched chain or terminal of the polyester. A part of the polyol unit becomes a crosslinking point and acts as a crosslinking agent. On the other hand, a part of the carboxylic acid unit having a hindered phenol group is contained at the terminal of the polyester, and a part is contained in the polyester together with the polyol unit in a state of being bonded to the polyol unit. As described above, when the unit derived from the polyvalent ester is contained in the polyester, the drawdown resistance of the polyester resin pellet of the present invention is improved, and the color tone of the obtained molded product is improved. Conceivable. The polyvalent ester is preferably a carboxylic acid ester of a trivalent to pentavalent polyol. Examples of the polyvalent ester include pentaerythritol tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] and 1,3,5-tris [2- [3- (3,5- And di-tert-butyl-4-hydroxyphenyl) propanoyloxy] ethyl] hexahydro-1,3,5-triazine-2,4,6-trione.

  Content of the unit derived from the said polyvalent ester in the polyester resin of this invention is 0.005-0.04 mass%. Here, the content of the component derived from the polyvalent ester in the polyester resin is the total amount of the unit derived from the polyvalent ester incorporated into the polyester chain and the component not incorporated into the polyester chain. In addition, it is thought that the said polyvalent ester added when melt-kneading is contained in a polyester chain in general. When the content of the unit derived from the polyvalent ester is less than 0.005% by mass, the drawdown resistance of the polyester resin pellet may be lowered, or when the polyester is heated during polymerization or molding. The polyester is likely to yellow, and the color tone of the resulting molded product may be lowered. On the other hand, when the content of the unit derived from the polyvalent ester exceeds 0.04% by mass, crosslinking by the unit derived from the polyvalent ester proceeds too much, and the melt viscosity may become too high or the obtained molded product Impact resistance may be reduced. The content of the unit derived from the polyvalent ester is preferably 0.03% by mass or less, and more preferably 0.02% by mass or less.

  The total content of terephthalic acid unit, ethylene glycol unit, cyclohexanedimethanol unit, unit derived from bisphenol A ethylene oxide adduct and unit derived from polyvalent ester in the polyester of the present invention is the sum of all structural units in the polyester. On the other hand, 80 mol% or more is preferable, 90 mol% or more is more preferable, and 95 mol% or more is more preferable. When a polyester having a content of less than 80 mol% is produced, the solidification is likely to cause sticking due to softening of the resin, which may make it difficult to increase the degree of polymerization.

  The polyester has a bifunctional compound unit other than a terephthalic acid unit, an ethylene glycol unit, a cyclohexanedimethanol unit, a unit derived from a bisphenol A ethylene oxide adduct and a unit derived from the polyvalent ester, if necessary. May be. The content of other bifunctional compound units (the total when two or more units are included) is preferably 20 mol% or less with respect to the total of all structural units constituting the polyester. It is more preferably at most mol%, further preferably at most 5 mol%. Examples of other difunctional compound units that can be contained in the polyester include dicarboxylic acid units, diol units, and hydroxycarboxylic acid units, aliphatic bifunctional compound units, and alicyclic bifunctional units. Either a compound unit or an aromatic bifunctional compound unit may be used. For example, aromatic dicarboxylic acids such as isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, 4,4′-biphenyldicarboxylic acid and ester-forming derivatives thereof; cyclohexanedicarboxylic acid, adipic acid, sebacic acid, dimer acid Aliphatic dicarboxylic acids such as, or ester-forming derivatives thereof; aliphatic diols such as neopentyl glycol, 1,4-butanediol, 1,5-pentamethylene diol, 1,6-hexamethylene diol, diethylene glycol, dimer diol A divalent structural unit derived from an ethylene oxide adduct of bisphenol S;

  As long as the polyester does not impair the effects of the present invention, a terephthalic acid unit, an ethylene glycol unit, a cyclohexanedimethanol unit, a unit derived from a bisphenol A ethylene oxide adduct, a unit derived from the polyvalent ester, and the others described above In addition to the bifunctional compound unit, other polyfunctional compound units may be included. Another polyfunctional compound unit is a polyfunctional compound unit derived from a polyfunctional compound having three or more carboxyl groups, hydroxyl groups and / or ester-forming groups thereof. The content of other polyfunctional compound units (the total when two or more units are included) is preferably 0.04% by mass or less based on the total of all structural units of the polyester. More preferably, it is 0.02 mass% or less, and it is further more preferable that it is not contained substantially. Examples of other polyfunctional compound units include those derived from trimellitic acid, pyromellitic acid, trimesic acid, trimethylolpropane, and glycerin.

  In addition, the polyester is optionally derived from other monofunctional compounds derived from at least one monocarboxylic acid other than the carboxylic acid having a hindered phenol group, a monoalcohol, and an ester-forming derivative thereof. You may have a monofunctional compound unit. The other monofunctional compound unit functions as a sealing compound unit and seals molecular chain end groups and / or branched chain end groups in the polyester, thereby preventing excessive crosslinking and gel formation in the polyester. . When the polyester has such other monofunctional compound units, the content of other monofunctional compound units (the total when two or more units are included) is the total structural unit of the polyester. It is preferably 1 mol% or less, more preferably 0.5 mol% or less, based on the total. When the content of the other monofunctional compound unit in the polyester exceeds 1 mol%, the polymerization rate in producing the polyester becomes slow, and the productivity tends to decrease. Examples of other monofunctional compound units include units derived from monofunctional compounds selected from benzoic acid, 2,4,6-trimethoxybenzoic acid, 2-naphthoic acid, stearic acid, and stearyl alcohol. .

  The polyester resin pellet of the present invention is obtained by subjecting terephthalic acid, ethylene glycol, cyclohexanedimethanol or bisphenol A ethylene oxide adduct and the polyvalent ester to condensation polymerization by melt-kneading and then solid-phase polymerization. .

  The method of polycondensation by melt-kneading terephthalic acid, ethylene glycol, cyclohexanedimethanol or bisphenol A ethylene oxide adduct and the polyvalent ester is not particularly limited, but terephthalic acid or its ester-forming derivative, ethylene glycol , Cyclohexanedimethanol or bisphenol A ethylene oxide adduct, the polyvalent ester, and, if necessary, other bifunctional compounds, polyfunctional compounds or monofunctional compounds as raw materials, An example is a method in which the obtained polyester oligomer is melt polycondensed after the transesterification reaction. Specifically, after performing esterification reaction or transesterification reaction using terephthalic acid, ethylene glycol, and cyclohexanedimethanol or bisphenol A ethylene oxide adduct, the polyvalent ester is added to the obtained polyester oligomer. Polyester oligomer obtained after performing the esterification reaction or transesterification reaction using terephthalic acid, ethylene glycol, cyclohexanedimethanol or bisphenol A ethylene oxide adduct, and the polyvalent ester. For example, a melt polycondensation method. The polyvalent ester may be added before performing the esterification reaction or transesterification reaction, or may be added after performing these reactions. In addition, raw materials other than the polyvalent ester can be appropriately added before the esterification reaction or transesterification reaction, or after these reactions have been performed.

  As described above, it is one of the features of the present invention that the polyvalent ester is subjected to polycondensation by melt-kneading with terephthalic acid, ethylene glycol, and cyclohexanedimethanol or bisphenol A ethylene oxide adduct. Thereby, the drawdown resistance of the polyester resin pellet is improved. Moreover, the thermal deterioration of the polyester resin in the subsequent polymerization process or molding is suppressed, and a molded product having a good color tone can be obtained.

  In the above esterification reaction or transesterification reaction, the above-mentioned raw materials, polymerization catalyst and, if necessary, additives such as anti-coloring agents are charged into the reactor, and the absolute pressure is about 0.5 MPa or less under pressure or normal pressure. It is preferable to carry out at a temperature of 160 to 280 ° C. while distilling off generated water or alcohol.

  The melt polycondensation reaction following the esterification reaction or transesterification reaction is carried out by adding additives such as the above-mentioned raw materials, polycondensation catalyst and coloring inhibitor to the obtained polyester oligomer as necessary. It is preferable to carry out under reduced pressure at a temperature of 260 to 290 ° C. until a polyester having a desired viscosity is obtained. When the reaction temperature of the melt polycondensation reaction is less than 260 ° C., the polymerization activity of the polymerization catalyst is low, and there is a possibility that a polyester having a target polymerization degree cannot be obtained. On the other hand, when the reaction temperature of the melt polymerization reaction exceeds 290 ° C., the decomposition reaction easily proceeds, and as a result, there is a possibility that a polyester having a target degree of polymerization cannot be obtained. The melt polycondensation reaction can be performed using, for example, a tank-type batch polycondensation apparatus or a continuous polycondensation apparatus including a biaxial rotating horizontal reactor.

  As the polymerization catalyst used for the condensation polymerization, a compound containing a germanium element, an antimony element, or a titanium element is preferable. As the compound containing antimony element, antimony trioxide, antimony chloride, antimony acetate, etc. are used. As the compound containing germanium element, germanium dioxide, germanium tetrachloride, germanium tetraethoxide, etc. are used. As the compound to be contained, tetraisopropyl titanate, tetrabutyl titanate, or the like is used. Among these, antimony trioxide and germanium dioxide are preferable from the viewpoint of polymerization catalyst activity, physical properties of the resulting polyester, and cost. When a polycondensation catalyst is used, the amount added is preferably in the range of 0.002 to 0.8 mass% based on the mass of the dicarboxylic acid component.

  When using an anti-coloring agent in the above condensation polymerization, for example, a phosphoric acid compound such as phosphorous acid or an ester thereof can be used, which can be used alone or in combination of two or more. Good. Examples of the phosphoric acid compound include phosphorous acid, phosphite, phosphoric acid, trimethyl phosphate, and triphenyl phosphate. It is preferable that the usage-amount of a coloring inhibitor exists in the range of 80-1000 ppm with respect to the sum total of a dicarboxylic acid component and a diester component. Moreover, in order to suppress the coloring by thermal decomposition of polyester, it is preferable to add a cobalt compound such as cobalt acetate, and the amount used is in the range of 100 to 1000 ppm with respect to the total of the dicarboxylic acid component and the diester component. It is more preferable.

  In the above condensation polymerization, a terephthalic acid ester may be used to form a terephthalic acid unit. The alcohol part of the terephthalic acid ester is not particularly limited, and examples thereof include monools such as methanol and ethanol; polyols such as ethylene glycol, cyclohexane dimethanol, and bisphenol A ethylene oxide adduct, which are constituent units of the polyester.

  In the above condensation polymerization, ethylene glycol monoester or diester may be used to form an ethylene glycol unit. The carboxylic acid moiety of the carboxylic acid ester is not particularly limited, and examples thereof include monocarboxylic acids such as formic acid, acetic acid, and propionic acid.

  The intrinsic viscosity of the polyester obtained by melt polycondensation is preferably in the range of 0.4 to 0.9 dl / g from the viewpoint of handleability. When the intrinsic viscosity of the polyester obtained by melt polycondensation is less than 0.4 dl / g, when the polyester is taken out from the reactor, the melt viscosity is too low and it becomes difficult to extrude in the form of a strand or a sheet. Moreover, it becomes difficult to cut into pellets uniformly. Further, when the polyester obtained by melt polycondensation is subjected to solid-phase polymerization, it takes a long time to increase the molecular weight, which may reduce productivity. The intrinsic viscosity of the polyester is more preferably 0.5 dl / g or more, and still more preferably 0.6 dl / g or more. On the other hand, if the intrinsic viscosity of the polyester is higher than 0.9 dl / g, the melt viscosity is too high, so that it may be difficult to take out the polyester from the reactor, or coloring may easily occur due to thermal degradation. is there. The intrinsic viscosity of the polyester is more preferably 0.85 dl / g or less, and still more preferably 0.8 dl / g or less.

  The polyester obtained as described above is extruded into a strand shape, a sheet shape, and the like, cooled, and then cut with a strand cutter, a sheet cutter, or the like to have a shape such as a column shape, an elliptical column shape, a disk shape, or a die shape. Intermediate pellets are produced. The above-described cooling after extrusion can be performed by, for example, a water cooling method using a water tank, a method using a cooling drum, an air cooling method, or the like.

  In order to further increase the polymerization degree of the intermediate pellet thus obtained, the intermediate pellet is subjected to solid phase polymerization. It is preferable to crystallize a part of the polyester by heating before solid phase polymerization. By doing so, it is possible to prevent the pellets from sticking during solid phase polymerization. The crystallization temperature is preferably 100 to 180 ° C. As a crystallization method, crystallization may be performed in a vacuum tumbler, or crystallization may be performed by heating in an air circulation type heating apparatus. When heating in an air circulation heating device, the internal temperature is preferably 100 to 160 ° C. When heating using an air circulation type heating device, compared with crystallization using a vacuum tumbler, heat conduction is good, so the time required for crystallization can be shortened and the device is also inexpensive. The time required for crystallization is not particularly limited, but is usually about 30 minutes to 24 hours. It is also preferred to dry the pellets at a temperature below 100 ° C. prior to crystallization.

  The temperature of the solid phase polymerization is preferably 170 to 250 ° C. When the temperature of the solid phase polymerization is lower than 170 ° C., the time for the solid phase polymerization becomes long and the productivity may be lowered. The temperature of solid phase polymerization is more preferably 175 ° C. or higher, and further preferably 180 ° C. or higher. On the other hand, when the temperature of the solid phase polymerization exceeds 250 ° C., the pellets may be stuck. The temperature of the solid phase polymerization is more preferably 240 ° C. or lower, and further preferably 230 ° C. or lower. The time for solid phase polymerization is usually about 5 to 70 hours. Moreover, you may coexist the catalyst used by melt polymerization at the time of solid-phase polymerization.

  The solid phase polymerization is preferably performed under reduced pressure or in an inert gas such as nitrogen gas. Further, it is preferable to perform solid-state polymerization while moving the pellets by an appropriate method such as a rolling method or a gas fluidized bed method so that no sticking occurs between the pellets. The pressure when solid-state polymerization is performed under reduced pressure is preferably 1 kPa or less.

  The polyester resin may contain other additives as long as the effects of the present invention are not impaired, for example, a colorant such as a dye or a pigment, a stabilizer such as an ultraviolet absorber, an antistatic agent, Examples include flame retardants, flame retardant aids, lubricants, plasticizers, and inorganic fillers. The content of these additives in the polyester resin is preferably 10% by mass or less, and more preferably 5% by mass or less.

  The intrinsic viscosity of the polyester obtained by solid phase polymerization needs to be in the range of 0.9 to 1.5 dl / g. When the intrinsic viscosity is less than 0.9 dl / g, the drawdown resistance is deteriorated, and the strength, impact resistance and transparency of the obtained molded product are lowered. The intrinsic viscosity is preferably 1.0 dl / g or more, and more preferably 1.05 dl / g or more. On the other hand, when the intrinsic viscosity exceeds 1.5 dl / g, the melt viscosity becomes too high and the melt moldability may be lowered, and the productivity is also lowered. The intrinsic viscosity is preferably 1.4 dl / g or less, and more preferably 1.3 dl / g or less.

  From the viewpoint of further improving the transparency of the obtained molded article, it is preferable that the half crystallization time at the crystallization peak temperature of the polyester contained in the polyester resin pellet obtained by solid phase polymerization is 30 minutes or more. More preferably, the semi-crystallization time is 30 minutes or longer. In the present invention, the “crystallization peak temperature” refers to the temperature of the amorphous polyester resin pellets from room temperature (20 ° C.) to a temperature equal to or higher than the melting point (280 ° C.) at 10 ° C./min using a differential calorimeter (DSC). This is the temperature of the exothermic peak that accompanies crystallization as measured by increasing the temperature. The “half crystallization time at the crystallization peak temperature” means that the polyester resin pellets are heated to a temperature equal to or higher than the melting point (280 ° C.) using a differential calorimeter (DSC), then − After rapidly cooling to the crystallization peak temperature at 50 ° C./min and then isothermal crystallization is performed while maintaining the crystallization peak temperature, the amount of heat generated by the isothermal crystallization is reached after reaching the crystallization peak temperature. It means the time until it becomes 1/2 of the total calorific value.

  From the viewpoint of preventing the pellets from sticking inside the tumbler during solid phase polymerization, it is preferable that the crystal melting enthalpy of the polyester contained in the polyester resin pellet is 20 J / g or more. Since the pellet obtained by solid phase polymerization contains polyester that has been crystallized at a high temperature for a long time, it has such a large crystal melting enthalpy. The crystal melting enthalpy is more preferably 23 J / g or more. The crystal melting enthalpy is usually 60 J / g or less.

  Various molded products can be obtained by melt-molding the obtained polyester resin pellets. The molding method is not particularly limited, and various melt molding methods such as extrusion molding and injection molding can be employed. Further, the melt molded product can be further subjected to secondary processing to obtain a molded product. Among these, the polyester resin pellet of the present invention is suitable for extrusion molding because of its high viscosity during melt molding. The temperature of the resin composition at the time of extrusion molding is preferably set to a temperature within the range of (melting point of polyester resin + 10 ° C.) to (melting point of polyester resin + 70 ° C.), and (melting point of polyester resin + 10 ° C.) to (polyester). More preferably, the temperature is within the range of the melting point of the resin + 40 ° C. By extruding at a temperature relatively close to the melting point, drawdown can be suppressed.

  For example, when a sheet or film is produced by extrusion molding such as a T-die method or an inflation method using the polyester resin composition of the present invention, there is no occurrence of drawdown, neck-in, film sway, and unmelted blisters. High-quality sheets or films can be produced with high productivity. And when performing secondary processing such as thermoforming using the sheet or film thus obtained, when forming deep-drawn molded products and large molded products, the drawdown is small, The degree of crystallization is good, and it is difficult to cause thickness unevenness or whitening in the step of applying an external force such as vacuum suction or compressed air, and the desired molded product can be obtained with good formability.

  Among the extrusion moldings, it is extrusion blow molding that is particularly suitable for using the polyester resin pellets of the present invention. The method of extrusion blow molding is not particularly limited, and can be performed in the same manner as conventionally known extrusion blow molding methods. For example, the polyester resin pellet of the present invention is melt-extruded to form a cylindrical parison, and the parison is sandwiched between blow molds while the parison is in a softened state, and a gas such as air is blown to blow the parison into the mold cavity. It can be performed by a method of expanding into a predetermined hollow shape along the shape. When the polyester resin pellets of the present invention are used, the extruded parison has good drawdown properties, and a hollow molded product can be produced with high productivity.

  The molded article thus obtained has excellent transparency, good appearance and color tone, and high mechanical strength, particularly impact resistance. In addition, since it has excellent properties such as gas barrier properties, flavor barrier properties, moisture resistance, and chemical resistance, it can be used in various applications. Moreover, it can also be set as the molded article which has a laminated structure with other thermoplastic resins.

  Polyester resin pellets, wherein the dicarboxylic acid unit in the polyester is mainly composed of terephthalic acid units, and the diol unit in the polyester is mainly composed of ethylene glycol units and cyclohexanedimethanol units or units derived from bisphenol A ethylene oxide adducts. The content of ethylene glycol units relative to the total of the diol units is 75 to 98 mol%, the content of cyclohexanedimethanol units and units derived from bisphenol A ethylene oxide adduct is 2 to 25 mol%, and the polyester resin Contains 0.005 to 0.04 mass% of a component derived from a polyvalent ester, the polyvalent ester is a carboxylic acid ester of a trivalent or higher polyol, and the carboxylic acid has a hindered phenol group In The intrinsic viscosity of the polyester is 0.9~1.5dl / g, crystal melting enthalpy is at 20 J / g or more, and the half crystallization time is also preferable that at least 30 minutes. A molded product obtained using the polyester resin pellets has particularly excellent transparency.

  The polyester mainly comprises dicarboxylic acid units mainly composed of terephthalic acid units, ethylene glycol units, cyclohexane dimethanol units or diol units mainly composed of units derived from bisphenol A ethylene oxide adducts, and units derived from polyvalent esters. Is. Each structure of the dicarboxylic acid unit, the diol unit, and the unit derived from the polyvalent ester is the same as that of the first pellet.

  Content of the unit derived from the said polyvalent ester in the said polyester resin is 0.005-0.04 mass%. The content of the unit derived from the polyvalent ester is preferably 0.03% by mass or less, and more preferably 0.02% by mass or less.

  The total content of terephthalic acid units, ethylene glycol units, cyclohexanedimethanol units, units derived from bisphenol A ethylene oxide adducts and units derived from the polyvalent esters in the polyester is the sum of all structural units in the polyester. On the other hand, 80 mol% or more is preferable, 90 mol% or more is more preferable, and 95 mol% or more is more preferable.

  The polyester has a bifunctional compound unit other than a terephthalic acid unit, an ethylene glycol unit, a cyclohexanedimethanol unit, a unit derived from a bisphenol A ethylene oxide adduct and a unit derived from a polyvalent ester, if necessary. Also good. The content of other bifunctional compound units (the total when two or more units are included) is preferably 20 mol% or less with respect to the total of all structural units constituting the polyester. It is more preferably at most mol%, further preferably at most 5 mol%. Other bifunctional compound units that can be contained in the polyester include those described above as those contained in the polyester in the first pellet.

  As long as the polyester does not impair the effects of the present invention, a terephthalic acid unit, an ethylene glycol unit, a cyclohexanedimethanol unit, a unit derived from a bisphenol A ethylene oxide adduct, a unit derived from a polyvalent ester, and the other units described above In addition to the bifunctional compound unit, other polyfunctional compound units may be included. The content of other polyfunctional compound units (the total when two or more units are included) is preferably 0.04% by mass or less based on the total of all structural units of the polyester. More preferably, it is 0.02 mass% or less, and it is further more preferable that it is not contained substantially. Other polyfunctional compound units include those described above as contained in the polyester in the first pellet.

  The polyester may optionally contain other monofunctional compounds derived from at least one monofunctional compound of monocarboxylic acids other than carboxylic acids having a hindered phenol group, monoalcohols, and ester-forming derivatives thereof. May have a functional compound unit. When the polyester has such other monofunctional compound units, the content of other monofunctional compound units (the total when two or more units are included) is the total structural unit of the polyester. It is preferably 1 mol% or less, more preferably 0.5 mol% or less, based on the total. Other monofunctional compound units include those described above as contained in the polyester in the first pellet.

  The half crystallization time at the crystallization peak temperature of the polyester contained in the polyester resin pellet needs to be 30 minutes or more. When the half crystallization time is less than 30 minutes, the transparency of the resulting molded product is lowered. More preferably, the half crystallization time is 40 minutes or more. The definition and preferred range of the half crystallization time are the same as those of the first pellet.

  The crystal melting enthalpy of the polyester contained in the polyester resin pellet needs to be 20 J / g or more. The crystal melting enthalpy is preferably 23 J / g or more. On the other hand, the crystal melting enthalpy is usually 60 J / g or less.

  The intrinsic viscosity of the polyester needs to be in the range of 0.9 to 1.5 dl / g. The intrinsic viscosity of the polyester is preferably 1.0 dl / g or more, and more preferably 1.05 dl / g or more. On the other hand, the intrinsic viscosity of the polyester is preferably 1.4 dl / g or less, and more preferably 1.3 dl / g or less.

  The polyester resin may contain other additives as long as the effects of the present invention are not impaired, for example, a colorant such as a dye or a pigment, a stabilizer such as an ultraviolet absorber, an antistatic agent, Examples include flame retardants, flame retardant aids, lubricants, plasticizers, and inorganic fillers. The content of these additives in the polyester resin is preferably 10% by mass or less, and more preferably 5% by mass or less.

  The method for producing the polyester resin pellet is not particularly limited, but the method described above as the method for producing the first pellet, that is, terephthalic acid, ethylene glycol, cyclohexanedimethanol or bisphenol A ethylene oxide adduct, and the polyvalent ester A method in which the intermediate pellets are melt-kneaded and melt-kneaded and then cut to obtain intermediate pellets, which are then solid-phase polymerized.

  When using an anti-coloring agent in the above condensation polymerization, for example, a phosphoric acid compound such as phosphorous acid or an ester thereof can be used, which can be used alone or in combination of two or more. Good. Examples of the phosphoric acid compound include phosphorous acid, phosphite, phosphoric acid, trimethyl phosphate, and triphenyl phosphate. It is preferable that the usage-amount of a coloring inhibitor exists in the range of 80-1000 ppm with respect to the sum total of a dicarboxylic acid component and a diester component. Moreover, in order to suppress the coloring by thermal decomposition of polyester, it is preferable to add a cobalt compound such as cobalt acetate, and the amount used is in the range of 100 to 1000 ppm with respect to the total of the dicarboxylic acid component and the diester component. It is more preferable.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited at all by this Example.

(1) Intrinsic Viscosity The intrinsic viscosity of polyester was measured at a temperature of 30 ° C. using an equal mass mixture of phenol and ethane tetrachloride as a solvent.

(2) Glass transition temperature (Tg), crystal melting enthalpy (ΔHm) and semi-crystallization time Polyester (solids) at a heating rate of 10 ° C./min using a differential scanning calorimeter (TA Q2000 manufactured by TA Instruments). The glass transition temperature (Tg) and crystal melting enthalpy (ΔHm) of the pellet after phase polymerization were measured. The glass transition temperature (Tg) is 20 at −50 ° C./min after raising the temperature of polyester (pellet after solid-phase polymerization) from normal temperature (20 ° C.) to 280 ° C. at a heating rate of 10 ° C./min. It was calculated from the data when the temperature was increased again at a temperature increase rate of 10 ° C./min after the amorphous pellet was obtained by rapid cooling to 0 ° C.

  Using a differential scanning calorimeter (TA Q2000 manufactured by TA Instruments), the polyester (pellet after solid phase polymerization) was heated from room temperature (20 ° C.) to 280 ° C. at a heating rate of 10 ° C./min. After rapidly cooling to 20 ° C. at −50 ° C./min to obtain amorphous pellets, the temperature was raised again to a temperature equal to or higher than the melting point (280 ° C.) at a heating rate of 10 ° C./min. From the curve in which the amount of heat was plotted against the temperature at this time, the temperature of the exothermic peak accompanying crystallization (crystallization peak temperature) was determined. Then, the polyester melted at 280 ° C. was rapidly cooled to the peak temperature at a temperature decrease rate of −50 ° C./min, and then kept at the crystallization peak temperature to allow isothermal crystallization to proceed. From the curve in which the integrated heat quantity is plotted against the time at this time, by measuring the time from when the crystallization peak temperature is reached until the calorific value due to isothermal crystallization becomes 1/2 of the total calorific value, The half crystallization time (second) was determined. FIG. 1 is a diagram showing how to determine the half crystallization time.

(3) Resin color (b value)
The resin color (b value) of the polyester resin pellets was measured using a colorimetric color difference meter “ZE-2000” manufactured by Nippon Denshoku Industries Co., Ltd. according to ASTM-D2244 (color scale system 2).

(4) Resin pressure Using an extrusion blow molding apparatus (“MSE-40E type” manufactured by Tahara Co., Ltd.), the maximum cylinder temperature is 290 ° C., the die temperature is 250 ° C., the molding cycle is 15 seconds, the screw rotational speed is 22 rpm, and the mold temperature is 20. A transparent bottle container (27.5 g ± 0.5 g) having a volume of 220 mL at 0 ° C. was extrusion blow molded. The resin pressure applied to the die during bottle molding was measured.

(5) Impact resistance 220 ml of water was put into a polyester hollow container, covered with a screw cap, and dropped repeatedly from a height of 1.5 m until the hollow container was cracked on the concrete surface. The impact resistance was evaluated from the number of times the hollow container was dropped when it broke.

Example 1
[Melt polymerization]
100.0 parts by mass of terephthalic acid, 38.1 parts by mass of ethylene glycol, and cyclohexane-1,4-dimethanol [CHDM, mixing ratio of cis isomer to trans isomer (cis isomer / trans isomer) is 30/70] 13.0 A slurry composed of parts by mass was prepared, and 0.012 parts by mass of germanium dioxide, 0.012 parts by mass of phosphorous acid and 0.043 parts by mass of cobalt acetate were added thereto. This slurry was heated to a temperature of 250 ° C. under pressure (absolute pressure 0.25 MPa) to carry out an esterification reaction to produce a low polymer. Subsequently, the obtained low polymer was transferred to a polycondensation tank, and pentaerythritol tetrakis [3- (3,5-di-tert-butyl-4-yl ester) was added as a polyvalent ester to 100 parts by mass of the low polymer. Hydroxyphenyl) propionate] 0.024 parts by mass and 3,9-bis (2,6-di-tert-butyl-4-methylphenoxy) -2,4,8,10-tetraoxa-3,9 as an anti-coloring agent -0.048 parts by weight of diphosphaspiro [5,5] undecane was added. Under a reduced pressure of 1 hPa, the low polymer was melt polycondensed at a temperature of 280 ° C. to produce a polyester resin having an intrinsic viscosity of 0.70 dl / g. The obtained polyester resin was extruded in a strand form from a nozzle and cooled with water, and then cut into a cylindrical shape (diameter: about 2.5 mm, length: about 2.5 mm) to obtain an intermediate pellet of polyester resin.

[Crystallization of intermediate pellets]
The polyester resin intermediate pellets thus obtained were put into a rolling vacuum solid phase polymerization apparatus, dried at 90 ° C. for 24 hours at 1 hPa, and then crystallized at 160 ° C. for 10 hours.

[Solid-state polymerization]
Following the above crystallization, solid phase polymerization was performed at 200 h for 1 hour at 1 hPa to obtain polyester resin pellets (solid phase polymerization pellets) containing a copolymerized polyester. The intrinsic viscosity of the copolyester was measured by the method described above and was 1.15 dl / g. Moreover, it was -1.10 when b value of the obtained solid-phase-polymerization pellet was measured by the above-mentioned method. When the ratio of the monomer component constituting the copolymer polyester was confirmed by 1H-NMR spectrum (apparatus: “JNM-GX-500 type” manufactured by JEOL Ltd., solvent: deuterated trifluoroacetic acid), terephthalic acid Unit: ethylene glycol unit: 1,4-cyclohexanedimethanol unit: diethylene glycol = 100.0: 82.8: 14.2: 3.0 (molar ratio), content of unit derived from polyvalent ester is 0 0.025% by mass. Table 1 shows Tg, ΔHm, and semi-crystallization time of the copolyester obtained by measuring polyester resin pellets using a differential scanning calorimeter by the above-described method.

[Formation of extrusion blow bottle]
Using the polyester resin pellets obtained as described above, a cylindrical bottle was produced by the method described in “(4) Resin pressure”. The resin pressure at this time was 21.2 MPa. The transparency of the mouth portion of the obtained cylindrical bottle was visually evaluated. The cylindrical bottle was evaluated by the method described in “(5) Impact resistance”. The results are shown in Table 1.

Example 2
Polyester resin in the same manner as in Example 1 except that the amount of polyvalent ester added to 100 parts by mass of the low polymer was changed to 0.009 parts by mass, and the amount of coloring inhibitor added was changed to 0.019 parts by mass. Pellets were manufactured, cylindrical bottles were produced using the pellets, and their evaluation was performed. The results are shown in Table 1. The ratio of the monomer component which comprises the obtained copolymer polyester is a terephthalic acid unit: ethylene glycol unit: 1,4-cyclohexane dimethanol unit: diethylene glycol = 100.0: 82.6: 14.5: 2. 9 (molar ratio), and the content of the unit derived from the polyvalent ester was 0.010% by mass.

Example 3
A polyester resin pellet was produced in the same manner as in Example 1 except that no anti-coloring agent was added to the low polymer, and a cylindrical bottle was produced using the pellet. went. The results are shown in Table 1. The ratio of the monomer component which comprises the obtained copolymer polyester is a terephthalic acid unit: ethylene glycol unit: 1,4-cyclohexane dimethanol unit: diethylene glycol = 100.0: 80.9: 16.0: 3. 1 (molar ratio), and the content of the unit derived from the polyvalent ester was 0.025% by mass.

Example 4
Except having changed the addition amount of the polyvalent ester with respect to 100 mass parts of low polymers into 0.005 mass part, and not having added the coloring inhibitor with respect to the low polymer, it carried out similarly to Example 1. Polyester resin pellets were produced, cylindrical bottles were produced using the pellets, and their evaluation was performed. The results are shown in Table 1. The ratio of the monomer component which comprises the obtained copolyester is terephthalic acid unit: ethylene glycol unit: 1,4-cyclohexanedimethanol unit: diethylene glycol = 100.0: 83.2: 14.0: 2. 8 (molar ratio), and the content of the unit derived from the polyvalent ester was 0.005% by mass.

Example 5
Using a slurry comprising 100.0 parts by mass of terephthalic acid, 35.5 parts by mass of ethylene glycol, and 18.3 parts by mass of cyclohexane-1,4-dimethanol, the amount of polyvalent ester added to 100 parts by mass of the low polymer The polyester resin pellets were produced in the same manner as in Example 1 except that the colorant was changed to 0.009 parts by mass and the anti-coloring agent was not added to the low polymer. Shaped bottles were produced and evaluated. The results are shown in Table 1. The ratio of the monomer component which comprises the obtained copolymer polyester is a terephthalic acid unit: ethylene glycol unit: 1,4-cyclohexane dimethanol unit: diethylene glycol = 100.0: 77.1: 20.0: 2. 9 (molar ratio), and the content of the unit derived from the polyvalent ester was 0.010% by mass.

Example 6
Polyester resin pellets in the same manner as in Example 5 except that a slurry comprising 100.0 parts by mass of terephthalic acid, 42.3 parts by mass of ethylene glycol, and 4.6 parts by mass of cyclohexane-1,4-dimethanol was used. Were manufactured and cylindrical pellets were produced using the pellets, and their evaluation was performed. The results are shown in Table 1. The ratio of the monomer component which comprises the obtained copolyester is terephthalic acid unit: ethylene glycol unit: 1,4-cyclohexanedimethanol unit: diethylene glycol = 100.0: 92.0: 5.0: 3. It was 0 (molar ratio), and the content of the unit derived from the polyvalent ester was 0.010% by mass.

Example 7
Other than using a slurry consisting of 100.0 parts by mass of terephthalic acid, 38.1 parts by mass of ethylene glycol and 13.0 parts by mass of cyclohexane-1,4-dimethanol, and changing the time of solid phase polymerization to 100 hours Manufactured the polyester resin pellet like Example 5, produced the cylindrical bottle using the said pellet, and evaluated those. The results are shown in Table 1. The ratio of the monomer component which comprises the obtained copolymer polyester is a terephthalic acid unit: ethylene glycol unit: 1,4-cyclohexanedimethanol unit: diethylene glycol = 100.0: 83.1: 14.0: 2. 9 (molar ratio), and the content of the unit derived from the polyvalent ester was 0.010% by mass.

Example 8
Other than using a slurry comprising 100.0 parts by mass of terephthalic acid, 38.1 parts by mass of ethylene glycol and 13.0 parts by mass of cyclohexane-1,4-dimethanol, and changing the time of solid-phase polymerization to 18 hours Manufactured the polyester resin pellet like Example 5, produced the cylindrical bottle using the said pellet, and evaluated those. The results are shown in Table 1. The ratio of the monomer component which comprises the obtained copolymer polyester is a terephthalic acid unit: ethylene glycol unit: 1,4-cyclohexanedimethanol unit: diethylene glycol = 100.0: 83.1: 14.0: 2. 9 (molar ratio), and the content of the unit derived from the polyvalent ester was 0.010% by mass.

Example 9
Polyester resin pellets are produced in the same manner as in Example 1 except that a slurry comprising 100.0 parts by mass of terephthalic acid, 42.6 parts by mass of ethylene glycol and 11.4 parts by mass of bisphenol A ethylene oxide 2 mol adduct is used. And while producing the cylindrical bottle using the said pellet, those evaluation was performed. The results are shown in Table 1. The ratio of the monomer component which comprises the obtained copolyester is terephthalic acid unit: ethylene glycol unit: bisphenol A ethylene oxide 2 mol adduct unit: diethylene glycol = 100.0: 92.1: 5.0: 2. 9 (molar ratio), and the content of the unit derived from the polyvalent ester was 0.010% by mass.

Example 10
Polyester resin pellets are produced in the same manner as in Example 1 except that a slurry comprising 100.0 parts by mass of terephthalic acid, 43.5 parts by mass of ethylene glycol, and 6.85 parts by mass of an adduct of bisphenol A ethylene oxide 2 mol is used. And while producing the cylindrical bottle using the said pellet, those evaluation was performed. The results are shown in Table 1. The ratio of the monomer component which comprises the obtained copolyester is terephthalic acid unit: ethylene glycol unit: bisphenol A ethylene oxide 2 mol adduct unit: diethylene glycol = 100.0: 94.1: 3.0: 2. 9 (molar ratio), and the content of the unit derived from the polyvalent ester was 0.010% by mass.

Comparative Example 1
Intermediate pellets were obtained in the same manner as in Example 1. The glass transition temperature and resin color of the obtained intermediate pellet were measured. The intermediate pellets were extrusion blow molded in the same manner as in Example 1. These results are shown in Table 1. The ratio of the monomer component constituting the intermediate pellet is as follows: terephthalic acid unit: ethylene glycol unit: 1,4-cyclohexanedimethanol unit: diethylene glycol = 100.0: 82.9: 14.2: 2.9 (mol) The content of the unit derived from the polyvalent ester was 0.025% by mass. In addition, when the said intermediate pellet was extrusion blow molded, since the parison was drawn down, the container was not obtained.

Comparative Example 2
Except having changed the addition amount of the polyvalent ester with respect to 100 mass parts of low polymers into 0.048 mass part, and not having added the coloring inhibitor with respect to the low polymer, it carried out similarly to Example 1. Polyester resin pellets were produced, cylindrical bottles were produced using the pellets, and their evaluation was performed. The results are shown in Table 1. The ratio of the monomer component which comprises the obtained copolymer polyester is a terephthalic acid unit: ethylene glycol unit: 1,4-cyclohexane dimethanol unit: diethylene glycol = 100.0: 82.8: 14.2: 3. It was 0 (molar ratio), and the content of the unit derived from the polyvalent ester was 0.050% by mass.

Comparative Example 3
A polyester resin pellet is produced in the same manner as in Example 1 except that a polyvalent ester and a coloring inhibitor are not added to the low polymer, and a cylindrical bottle is produced using the pellet. And evaluated them. The results are shown in Table 1. The ratio of the monomer component which comprises the obtained copolymer polyester is a terephthalic acid unit: ethylene glycol unit: 1,4-cyclohexanedimethanol: diethylene glycol = 100.0: 82.2: 15.0: 2.8. (Molar ratio). In addition, when the polyester resin pellet (solid phase polymerization pellet) was extrusion-molded and blow-molded, since the parison was drawn down, a container was not obtained.

Comparative Example 4
A slurry composed of 92.0 parts by mass of terephthalic acid, 8.0 parts by mass of isophthalic acid (IPA) and 44.4 parts by mass of ethylene glycol was used, and the addition amount of the polyvalent ester was 100 parts by mass with respect to 100 parts by mass of the low polymer. Except having changed to 009 mass parts, it carried out similarly to Example 1, and manufactured the polyester resin pellet, produced the cylindrical bottle using the said pellet, and evaluated those. The results are shown in Table 1. The ratio of the monomer component constituting the obtained copolymer polyester is as follows: terephthalic acid unit: isophthalic acid unit: ethylene glycol unit: diethylene glycol = 92.0: 8.0: 96.9: 3.1 (molar ratio) The content of the unit derived from the polyvalent ester was 0.010% by mass.

Comparative Example 5
Use of a slurry composed of 100.0 parts by mass of terephthalic acid, 38.1 parts by mass of ethylene glycol and 8.32 parts by mass of 1,4-butanediol (BD), and addition of polyvalent ester to 100 parts by mass of the low polymer A polyester resin pellet was produced in the same manner as in Example 1 except that the amount was changed to 0.009 part by mass, and a cylindrical bottle was produced using the pellet and evaluated. The results are shown in Table 1. The ratio of the monomer component which comprises the obtained copolymer polyester is a terephthalic acid unit: ethylene glycol unit: 1,4-butanediol :: diethylene glycol = 100.0: 83.0: 14.0: 3.0. (Molar ratio), and the content of the unit derived from the polyvalent ester was 0.010% by mass.

Comparative Example 6
A polyester resin pellet was produced in the same manner as in Example 1 except that the polyvalent ester was not added, and a cylindrical bottle was produced using the pellet and evaluated. The results are shown in Table 1. The ratio of the monomer component which comprises the obtained copolymer polyester is terephthalic acid unit: ethylene glycol unit: 1,4-cyclohexanedimethanol: diethylene glycol = 100.0: 80.0: 17.0: 3.0 (Molar ratio). In addition, when the polyester resin pellet (solid phase polymerization pellet) was extrusion-molded and blow-molded, since the parison was drawn down, a container was not obtained.

Comparative Example 7
A slurry comprising 100.0 parts by mass of terephthalic acid and 44.8 parts by mass of ethylene glycol was prepared, and 0.010 parts by mass of germanium dioxide, 0.010 parts by mass of phosphorous acid and 0.010 parts by mass of cobalt acetate were added thereto. . This slurry was heated to a temperature of 250 ° C. under pressure (absolute pressure 2.5 kg / cm 2), and an esterification reaction was carried out until the esterification rate reached 95% to produce a low polymer. Subsequently, the obtained low polymer was transferred to a polycondensation tank having a capacity of 5 m 3, and the low polymer was melt polycondensed at a temperature of 270 ° C. under a reduced pressure of 0.1 Torr to obtain an intrinsic viscosity of 0.70 dl. / G of polyester was synthesized. The obtained polyester was extruded in a strand form from a nozzle, cooled with water, and then cut into a cylindrical shape (diameter: about 2.5 mm, length: about 2.5 mm) to obtain polyester (A) pellets.

  A slurry composed of 100.0 parts by mass of terephthalic acid, 17.8 parts by mass of ethylene glycol and 62.5 parts by mass of 1,4-cyclohexanedimethanol (mixing ratio of cis isomer: trans isomer 30:70) was prepared. 0.015 parts by mass of germanium, 0.010 parts by mass of phosphorous acid and 0.010 parts by mass of cobalt acetate were added. This slurry was heated to a temperature of 250 ° C. under pressure (absolute pressure 2.5 kg / cm 2), and an esterification reaction was carried out until the esterification rate reached 95% to produce a low polymer. Subsequently, the obtained low polymer was transferred to a polycondensation tank having a capacity of 5 m 3, and the low polymer was melt polycondensed at a temperature of 270 ° C. under a reduced pressure of 0.1 Torr to obtain an intrinsic viscosity of 0.70 dl. / G of polyester was produced. The obtained polyester was extruded into a strand form from a nozzle, cooled with water, and then cut into a cylindrical shape (diameter: about 2.5 mm, length: about 2.5 mm) to obtain polyester (B) pellets.

    The above-mentioned polyester (A) and polyester (B) pellets are blended so that the mass ratio (A / B) is 70/30, and further, 100 parts by mass in total of polyester (A) and polyester (B). , 0.024 parts by mass of pentaerythritol tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] as a polyvalent ester and 3,9-bis (2,6-dioxy) as an anti-coloring agent -Tert-butyl-4-methylphenoxy) -2,4,8,10-tetraoxa-3,9-diphosphaspiro [5,5] undecane 0.048 parts by mass was added and premixed, and then a twin screw extruder (Toshiba Machine Co., Ltd. “TEM-48SS”). The extruder was set to a cylinder temperature of 330 ° C., a die temperature of 320 ° C., melt-kneaded at a vent vacuum pressure of 700 mmHg (absolute pressure of 60 mmHg) and an extrusion rate of 150 kg / hr to extrude a strand. When the molten resin was directly measured with a thermometer at the exit of the extruder die, the resin temperature was 332 ° C. The extruded strand was immediately cooled with water and then cut into a cylindrical shape (diameter: about 2.5 mm, length: about 2.5 mm) to obtain an intermediate pellet of the polyester resin composition.

  The intermediate pellet of the polyester resin composition obtained as described above was put into a rolling vacuum solid phase polymerization apparatus, dried at 90 ° C. for 24 hours under a reduced pressure of 0.01 Torr, and then at 160 ° C. for 10 hours. Crystallization was performed.

  Following the crystallization, solid phase polymerization was performed at 200 ° C. for 38 hours under a reduced pressure of 0.01 Torr to obtain a solid phase polymerization pellet of a polyester resin composition. Cylindrical bottles were produced using the obtained pellets and evaluated. The results are shown in Table 1. The ratio of the monomer component which comprises the obtained copolyester is terephthalic acid unit: ethylene glycol unit: 1,4-cyclohexanedimethanol unit: diethylene glycol = 100.0: 82.8: 14.2: 3. It was 0 (molar ratio), and the content of the unit derived from the polyvalent ester was 0.025% by mass.

Comparative Example 8
The same as Comparative Example 7 except that polyester (B) was prepared using a slurry comprising 100.0 parts by mass of terephthalic acid, 37.3 parts by mass of ethylene glycol and 31.8 parts by mass of bisphenol A ethylene oxide 2 mol adduct. Polyester resin pellets were manufactured, cylindrical bottles were produced using the pellets, and their evaluation was performed. The results are shown in Table 1. The ratio of the monomer component which comprises the obtained copolyester is terephthalic acid unit: ethylene glycol unit: bisphenol A ethylene oxide 2 mol adduct unit: diethylene glycol = 100.0: 92.0: 5.0: 3. It was 0 (molar ratio), and the content of the unit derived from the polyvalent ester was 0.010% by mass.

  The polyester resin pellets of the present invention had an appropriate melt viscosity with a resin pressure of 18 to 23 MPa when extrusion blow molded, and were excellent in drawdown resistance. Moreover, the molded article obtained using these pellets had good impact resistance and color tone. On the other hand, when the intermediate pellet obtained by melt polycondensation was extrusion blow molded (Comparative Example 1), the parison was drawn down and a container was not obtained. When the polyvalent ester was not added (Comparative Examples 3 and 6), the parison was drawn down and a container was not obtained, and the color tone of the obtained resin was poor. On the other hand, when there was too much addition amount of polyvalent ester (comparative example 2), the impact resistance of the obtained container was inadequate. When the copolymer component was isophthalic acid (Comparative Example 4) or 1,4-butanediol (Comparative Example 5), the resulting container had insufficient impact resistance. When two types of pellets obtained by polycondensation by melt-kneading a low polymer are melt-kneaded with a polyvalent ester and then subjected to solid phase polymerization (Comparative Examples 7 and 8), the resulting molded article The transparency of was insufficient.

  As demonstrated in the above examples, a polyester resin is obtained by adding a predetermined amount of a polyvalent ester of a trivalent or higher polyol carboxylic acid having a hindered phenol group during melt polycondensation. A molded article having improved resistance to drawdown and improved impact resistance and color tone when molding pellets was obtained.

Claims (3)

Polyester resin pellets obtained by subjecting terephthalic acid, ethylene glycol, cyclohexanedimethanol or bisphenol A ethylene oxide adduct, and polyhydric ester to polycondensation by melt-kneading and then solid-phase polymerization,
The polyvalent ester is a carboxylic acid ester of a trivalent or higher polyol, and the carboxylic acid has a hindered phenol group,
The dicarboxylic acid unit in the polyester mainly consists of terephthalic acid units,
The diol unit in the polyester mainly comprises an ethylene glycol unit and a unit derived from a cyclohexanedimethanol unit or a bisphenol A ethylene oxide adduct, and the content of the ethylene glycol unit relative to the total of the diol units is 75 to 98 mol%, cyclohexane The content of the dimethanol unit and the unit derived from the bisphenol A ethylene oxide adduct is 2 to 25 mol%,
The content of the component derived from the polyvalent ester in the polyester resin is 0.005 to 0.04% by mass, and the intrinsic viscosity of the polyester is 0.9 to 1.5 dl / g, Polyester resin pellets.   A molded article formed by extrusion blow molding using the pellets according to claim 1.   After terephthalic acid, ethylene glycol, cyclohexanedimethanol or bisphenol A ethylene oxide adduct, and the polyvalent ester are subjected to condensation polymerization by melting and kneading to obtain an intermediate pellet, the intermediate pellet is solid-phase polymerized. The manufacturing method of the polyester resin pellet of Claim 1 to do.

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