TW202344554A - Polyester and shaped article of the same - Google Patents

Abstract

A polyester according to the present invention contains 0.001-0.2 mol% of a unit derived from a compound represented by formula (I). Said polyester has non-Newtonian properties suitable for extrusion molding, etc., and inhibits coloring or generation of a gel compared to other resins despite polycondensation being performed at high temperatures. Moreover, this polyester is highly safe. [In formula (I), the total of x, y, z, and w is 1-50, and R1-R4 each independently represent a hydrogen atom or an acyl group having 1-18 carbons atoms.].

Description

Polyester and molded products made of it

The present invention relates to a slightly cross-linked polyester in which gelation or coloring is suppressed and a method for producing the same.

Polyester-based products are excellent in various properties such as transparency, mechanical properties, gas barrier properties, and odor barrier properties. There is little concern that monomers or harmful additives will remain when molded products are made, and they are excellent in hygiene and safety. Therefore, polyester systems have recently been widely used as hollow containers for filling juices, soft drinks, seasonings, oils, cosmetics, lotions, and other products instead of conventional vinyl chloride resins.

However, micro-crosslinked polyester, in which a multifunctional cross-linking agent is added to cross-link the molecular chains, is used for extrusion blow molding or special-shaped extrusion molding. By appropriately cross-linking the molecular chains of polyester, it exhibits non-Newtonian properties suitable for extrusion blow molding, etc. Patent Documents 1 and 2 describe copolymerized polyesters using trimellitic anhydride, pyromellitic anhydride, trimethylolpropane, tetramethylolmethane, pentaerythritol, trimellitic acid, etc. as cross-linking agents. However, due to the small molecular weight of these cross-linking agents and the small molecular weight between the minimum cross-linking points, there is a problem of gelation. On the other hand, when a cross-linking agent with a large molecular weight is used in order to increase the molecular weight between the minimum cross-linking points, the amount of the cross-linking agent required to exhibit the required non-Newtonian properties increases. Compared with other resins, the polycondensation of polyester is carried out at high temperatures. When such a cross-linking agent is used, there is a problem of polyester coloring due to its decomposition. [Prior technical literature] [Patent Document]

[Patent Document 1] Japanese Patent Application Laid-Open No. 7-179581 [Patent Document 2] Japanese Patent Application Publication No. 9-157365

[Problem to be solved by the invention]

The present invention was completed in order to solve the above-mentioned problems, and its object is to provide a slightly cross-linked polyester in which gel formation or coloring is suppressed. [Means to solve the problem]

The above problems can be solved by providing a polyester containing 0.001 to 0.2 mol% of units derived from the compound represented by the following formula (I) with respect to all monomer units;

[In the formula (I), the total of x, y, z and w is 1 to 50, and R ¹ to R ⁴ each independently represent a hydrogen atom or a hydroxyl group having 1 to 18 carbon atoms].

At this time, the compound represented by the above formula (I) is preferably selected from the group consisting of polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan monooleate, and tristearate. At least one kind from the group consisting of fatty acid polyoxyethylene sorbitan, monosulfonate polyoxyethylene sorbitan, and trioleic acid polyoxyethylene sorbitan.

It is also preferred that the polyester further contains 0.0005 to 0.2 mol % of units derived from a hindered phenol antioxidant based on all monomer units. The aforementioned polyester is preferably selected from the group consisting of polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, polyethylene furandicarboxylate and polylactic acid. At least one kind, more preferably polyethylene terephthalate containing 1.5 to 25 mol% of cyclohexanedimethanol units or isophthalic acid units. The limiting viscosity of the polyester is preferably 0.7 dl/g or more.

A molded product obtained by extrusion molding the polyester is a suitable embodiment of the present invention, and a molded product obtained by extrusion blow molding or special-shaped extrusion molding is a more suitable embodiment. Since a film or sheet made of the aforementioned molded article is a more suitable embodiment of the present invention, a thermoformed article formed by thermoforming the aforementioned film or sheet is a more preferred embodiment. A container made of the above-mentioned molded product is also a more suitable embodiment of the present invention.

The above-mentioned problems can also be solved by providing a method for producing the aforementioned polyester by polycondensing an ester-forming monomer and the compound represented by the aforementioned formula (I). [Effects of the invention]

The polyester of the present invention has non-Newtonian properties suitable for extrusion molding, etc., and compared with other resins, it suppresses gel formation or coloring despite polycondensation at high temperatures. Furthermore, the above-mentioned polyester type has high safety.

[Form of carrying out the invention]

The polyester of the present invention contains 0.001 to 0.2 mol % of units derived from the compound represented by the following formula (I) based on all monomer units. By using a compound represented by the following formula (I) as a cross-linking agent, a polyester is obtained that has non-Newtonian properties suitable for extrusion molding, etc., and at the same time, compared with other resins, polycondensation proceeds at high temperatures. , but inhibits gel formation or coloration. Furthermore, the compound represented by the following formula (I) is widely used as a food additive internationally and has high safety. Therefore, the aforementioned polyester system has high safety.

[In the formula (I), the total of x, y, z and w is 1 to 50, and R ¹ to R ⁴ each independently represent a hydrogen atom or a hydroxyl group having 1 to 18 carbon atoms].

The polyester of the present invention contains 0.001 to 0.2 mol % of units derived from the compound represented by the following formula (I) based on all monomer units. When the content of units derived from the compound represented by the above formula (I) is less than 0.001 mol%, the aforementioned effect cannot be achieved. The aforementioned content is preferably 0.002 mol% or more, more preferably 0.005 mol% or more, particularly preferably 0.007 mol% or more, and particularly preferably 0.008 mol% or more. From the viewpoint of obtaining a polyester with high melt tension, the content is preferably 0.01 mol% or more, more preferably 0.03 mol% or more, particularly preferably 0.05 mol% or more, and particularly preferably 0.08 mol% or more. , the optimal value is above 0.1. On the other hand, when the content exceeds 0.2 mol%, the required non-Newtonian properties are not obtained and the resulting polyester is colored. The aforementioned content is preferably 0.15 mol% or less. From the viewpoint of obtaining a polyester in which coloring is extremely suppressed, the content is preferably 0.1 mol% or less, particularly preferably 0.02 mol% or less.

In the above formula (I), the total of x, y, z and w is 1 to 50. If the total does not reach 1, the resulting polyester will gel because the molecular weight between the minimum cross-linking points becomes small. The total is preferably 4 or more, more preferably 8 or more, particularly preferably 12 or more, particularly preferably 16 or more, and most preferably 18 or more. On the other hand, when the total number exceeds 50, the required non-Newtonian properties are not obtained and the resulting polyester is colored. The above total is preferably 40 or less, more preferably 32 or less, particularly preferably 28 or less, particularly preferably 24 or less, and most preferably 22 or less.

In the above formula (I), R ¹ to R ⁴ each independently represent a hydrogen atom or a hydroxyl group having 1 to 18 carbon atoms. From the viewpoint of suppressing the formation of gel, the carbon number of the acyl group is preferably 2 or more, more preferably 4 or more, even more preferably 6 or more, particularly preferably 7 or more, most preferably 8 or more. On the other hand, from the viewpoint of availability, the carbon number is 18 or less, preferably 16 or less, more preferably 14 or less, most preferably 12 or less. The aforementioned hydroxyl group may be a straight chain or a branched chain without any problem, but the former is preferred.

The compound represented by the above formula (I) is preferably selected from the group consisting of polyoxyethylene sorbitan monolaurate (polysorbate 20), polyoxyethylene sorbitan monostearate (polysorbate 60), and Polyoxyethylene sorbitan oleate (polysorbate 80), polyoxyethylene sorbitan tristearate (polysorbate 65), polyoxyethylene sorbitan monosulfate (polysorbate 40) ) and trioleic acid polyoxyethylene sorbitan (polysorbate 85), and at least one of the group consisting of trioleic acid polyoxyethylene sorbitan (polysorbate 85), more preferably monolauric acid polyoxyethylene sorbitan.

The reason why the above effect is achieved by using the compound represented by the above formula (I) as a cross-linking agent is not clear, but the compound is not easily decomposed even when polycondensation is performed at high temperatures, and the tetrahydrofuran ring system contained in the compound is soft. , therefore even when a cross-linked structure is formed, gel generation is suppressed.

The polyester of the present invention is preferably obtained by polycondensation of dicarboxylic acid and diol as ester-forming monomers and the compound represented by the above formula (I) and contains dicarboxylic acid units, diol units and derivatives derived from the above formula. The unit of the compound shown in (I).

The dicarboxylic acid is not particularly limited as long as it can be polycondensed with diol, and examples thereof include terephthalic acid, isophthalic acid, phthalic acid, biphenyl dicarboxylic acid, and diphenyl dicarboxylic acid. Ether dicarboxylic acid, diphenyl ketone dicarboxylic acid, diphenyl ketone dicarboxylic acid, sodium sulfoisophthalate, 2,6-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 2,7- Aromatic dicarboxylic acids such as naphthalene dicarboxylic acid; aliphatic dicarboxylic acids such as glutaric acid, adipic acid, azelaic acid, sebacic acid, dimer acid (and their hydrogenated products), etc.; cyclohexanedicarboxylic acid Alicyclic dicarboxylic acids such as acid, norbornene dicarboxylic acid, tricyclodecanedicarboxylic acid, etc.; 2,5-furandicarboxylic acid, 2,4-furandicarboxylic acid, 3,4-furandicarboxylic acid Acids, complex cyclic aromatic dicarboxylic acids, etc. These may be used alone or two or more types may be used in combination. Instead of the dicarboxylic acid, its ester-forming derivative may be used without any problem. Among them, the aforementioned polyester preferably contains aromatic dicarboxylic acid units as dicarboxylic acid units, and more preferably contains terephthalic acid units.

The polyester preferably contains 25 mol% or more of aromatic dicarboxylic acid units based on all monomer units. At this time, the content of the aromatic dicarboxylic acid units is preferably 50 mol% or less based on the total monomer units.

The diol is not particularly limited as long as it can be polymerized and condensed with a dicarboxylic acid, and examples thereof include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, and new Aliphatic glycols such as pentanediol, 1,6-hexanediol, methylpentanediol, etc.; alicyclic glycols such as cyclohexanedimethanol, norbornenedimethanol, tricyclodecanedimethanol, etc. . Alternatively, a glycol in which one or more molecules of ethylene oxide is added to each of two hydroxyl groups of an aromatic glycol may be used. For example, a glycol obtained by adding 1 to 8 molecules of ethylene oxide to each of two phenolic hydroxyl groups of bisphenol A can be exemplified. These may be used individually, or 2 or more types may be used together. In addition, instead of the diol, its ester-forming derivative may be used without any problem. Among them, the aforementioned polyester preferably contains aliphatic diol units as diol units, more preferably contains ethylene glycol units, 1,3-propanediol units or 1,4-butanediol units, and particularly preferably contains ethylene glycol units.

The polyester preferably contains 40 mol% or more of aliphatic diol units based on all monomer units. At this time, the content of the aliphatic diol unit is preferably 55 mol% or less based on the total monomer units.

It is also preferable that the polyester of the present invention contains a hydroxycarboxylic acid unit obtained by polycondensation of a hydroxycarboxylic acid of an ester-forming monomer and a compound represented by the above formula (I) and is derived from a compound represented by the above formula (I). unit of a compound.

At that time, the content of the hydroxycarboxylic acid units in the aforementioned polyester is usually 50 mol% or more, preferably 70 mol% or more, more preferably 80 mol% or more, especially 90 mol% or more.

Examples of the hydroxycarboxylic acid include lactic acid, glycolic acid, 2-hydroxybutyric acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 2-hydroxyisobutyric acid, and 2-hydroxy-2-methylbutyric acid. , 2-hydroxyvaleric acid, 3-hydroxyvaleric acid, 4-hydroxyvaleric acid, 5-hydroxyvaleric acid, 6-hydroxycaproic acid, 10-hydroxystearic acid, 4-hydroxyphenylstearic acid, 4-( β-Hydroxy)ethoxybenzoic acid, preferably lactic acid.

The polyester of the present invention is preferably selected from the group consisting of polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, polyethylene furandicarboxylate and polylactic acid. At least one type of the group, preferably polyethylene terephthalate. Polyethylene terephthalate, polybutylene terephthalate and polytrimethylene terephthalate are composed of terephthalic acid as the aromatic dicarboxylic acid and ethylene glycol as the aliphatic diol. It is obtained by polycondensation of alcohol, 1,4-butanediol or 1,3-propanediol and the compound represented by the above formula (I). Polylactic acid is obtained by polycondensation of lactic acid as the aforementioned hydroxycarboxylic acid and the compound represented by the aforementioned formula (I).

The polyester of the present invention is preferably polyethylene terephthalate containing 1.5 to 25 mol% of cyclohexanedimethanol units or isophthalic acid units based on all monomer units. From the viewpoint of the strength of the molded product, the polyethylene terephthalate preferably contains a cyclohexanedimethanol unit, and from the viewpoint of the polymerization rate, the polyethylene terephthalate preferably contains meta- Phthalic acid unit. The content of cyclohexanedimethanol units or isophthalic acid units is more preferably 1.6 mol% or more, particularly preferably 1.8 mol% or more. On the other hand, the aforementioned content is more preferably 20 mol% or less, even more preferably 10 mol% or less.

When the aforementioned polyethylene terephthalate contains cyclohexanedimethanol units, the content of the ethylene glycol units in the polyethylene terephthalate is preferably 25 mol% relative to the total monomer units. or above, more preferably 30 mol% or more, still more preferably 40 mol% or more. On the other hand, the aforementioned content is preferably 55 mol% or less, more preferably 52 mol% or less, even more preferably 51 mol% or less.

When the aforementioned polyethylene terephthalate contains isophthalic acid units, the content of the terephthalic acid units in the polyethylene terephthalate is preferably 25 or more moles based on the total monomer units. %, more preferably 30 mol% or more, even more preferably 40 mol% or more. On the other hand, the aforementioned content is preferably 50 mol% or less, more preferably 49.99 mol% or less, even more preferably 49.98 mol% or less.

The polyester of the present invention preferably contains 0.0005 to 0.2 mol % of units derived from a hindered phenol antioxidant based on all monomer units. Here, the unit derived from the hindered phenol antioxidant is contained in the polyester by polycondensing the hindered phenol antioxidant with an ester-forming monomer and the compound represented by the formula (I). The middle one. The polyol unit of the hindered phenol-based antioxidant or the carboxylic acid unit having a hindered phenol group is contained in the polyester through a transesterification reaction. By containing the unit system derived from the hindered phenol antioxidant in the polyester, the coloring of the polyester can be further suppressed. Examples of the hindered phenol-based antioxidant include pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 1,3,5-shen[2-[3 -(3,5-di-tert-butyl-4-hydroxyphenyl)propionyloxy]ethyl]hexahydro-1,3,5-tris-2,4,6-trione, etc.

The content of the units derived from the hindered phenol antioxidant in the polyester of the present invention is preferably 0.0005 to 0.2 mol% based on the total monomer units. If the aforementioned content is less than 0.0005 mol%, the aforementioned effects may not be achieved. The aforementioned content is more preferably 0.0006 mol% or more, particularly preferably 0.0007 mol% or more, and most preferably 0.0008 mol% or more. On the other hand, when the content exceeds 0.2 mol %, the degree of crystallization is reduced and physical properties may be reduced. The aforementioned content is more preferably 0.190 mol% or less, particularly preferably 0.150 mol% or less, particularly preferably 0.100 mol% or less, and most preferably 0.050 mol% or less.

From the viewpoint of further suppressing coloration, the molar ratio of the unit derived from the hindered phenol antioxidant to the unit derived from the compound represented by the above formula (I) in the polyester of the present invention (derived from the hindered phenol The unit which is an antioxidant/the unit derived from the compound represented by formula (I)) is preferably 0.001 to 0.1. The molar ratio (units derived from the hindered phenol antioxidant/unit derived from the compound represented by formula (I)) is more preferably 0.005 or more. From the viewpoint of obtaining a polyester in which coloring is extremely suppressed, the molar ratio (units derived from the hindered phenol antioxidant/unit derived from the compound represented by formula (I)) is more preferably 0.01 or more, and particularly preferably 0.05 or above. On the other hand, the molar ratio (units derived from the hindered phenol antioxidant/unit derived from the compound represented by formula (I)) is more preferably 0.095 or less, particularly preferably 0.090 or less, and particularly preferably 0.085 or less. From the viewpoint of obtaining a polyester with high melt tension, the molar ratio (units derived from the hindered phenol antioxidant/unit derived from the compound represented by formula (I)) is preferably 0.05 or less, more preferably 0.02 below, preferably below 0.01.

The polyester of the present invention may contain dicarboxylic acid, dicarboxylic acid, the compound represented by the above formula (I) and the aforementioned hindered phenol-based antioxidant derived from other esters as long as the effect of the present invention is not hindered. Sexually monomeric unit. Examples of the other ester-forming monomer include monocarboxylic acids, monoalcohols, and their ester-forming derivatives; compounds other than the compound represented by the above formula (I) having three or more carboxyl groups, hydroxyl groups, and/or Their ester-forming groups are polyfunctional compounds, etc. Examples of the polyfunctional compound include trimellitic anhydride, pyromellitic anhydride, trimethylolpropane, tetramethylolmethane, pentaerythritol, and trimellitic acid. The content of the aforementioned other ester-forming monomer units in the polyfunctional compound is preferably 5 mol% or less, more preferably 3 mol% or less, and even more preferably 1 mol% or less based on the total monomer units. , the best one is that it does not substantially contain.

From the viewpoint of further improving the melt formability of the polyester of the present invention or the production stability of the resulting molded article, the limiting viscosity of the polyester is preferably 0.67 dl/g or more, more preferably 0.7 dl/g or more. More preferably, it is 0.8dl/g or more, still more preferably, it is 0.9dl/g or more, and particularly preferably, it is 1.0dl/g or more. On the other hand, the limiting viscosity is preferably 1.5 dl/g or less, more preferably 1.4 dl/g or less, even more preferably 1.3 dl/g or less.

From the viewpoint of improving heat resistance, the glass transition temperature of the polyester is preferably 75°C or higher, more preferably 77°C or higher. On the other hand, the glass transition temperature is preferably 100°C or lower. In this case, it is preferable to perform extrusion blow molding of the polyester since it is not necessary to heat the mold above room temperature.

From the viewpoint of further improving the sag resistance during extrusion blow molding, the melting point of the polyester is preferably 225°C or higher, more preferably 230°C or higher, and particularly preferably 235°C or higher. On the other hand, from the viewpoint of lowering the barrel temperature during extrusion blow molding and further improving the color tone of the molded product, the melting point of the polyester is preferably 260° C. or lower.

As a method for producing the polyester, a method of polycondensing an ester-forming monomer and a compound represented by the above formula (I) is preferred. As the ester-forming monomer, it is preferable to use the above-mentioned dicarboxylic acid and diol together, or to use the above-mentioned hydroxycarboxylic acid.

The method for polycondensing the aforementioned ester-forming monomer and the compound represented by the aforementioned formula (I) is not particularly limited. However, when using the aforementioned dicarboxylic acid and glycol as the aforementioned ester-forming monomer, it is preferred to use A method of condensation polymerizing the dicarboxylic acid, the diol and the compound represented by the formula (I) by melting and kneading them. Specifically, the above-mentioned dicarboxylic acid, the above-mentioned diol and the compound represented by the above-mentioned formula (I) are used as raw materials, and after performing an esterification reaction or transesterification reaction, the resulting polyester oligomer is melted and polycondensed. . The compound represented by the above formula (I) may be added before performing the esterification reaction or transesterification reaction, or may be added after performing the reaction. Moreover, raw materials other than the compound represented by the said formula (I) can also be added suitably before carrying out an esterification reaction or a transesterification reaction, or after carrying out these reactions.

The above-mentioned esterification reaction or transesterification reaction is preferably carried out by adding the above-mentioned raw materials, polymerization catalyst and optionally the aforementioned hindered phenol antioxidant and other additives into a reactor, under pressure at an absolute pressure of about 0.5 MPa or less or at normal pressure. The process is carried out while distilling off the generated water or alcohol at a temperature of 160 to 280°C.

In the melt polycondensation reaction after the esterification reaction or transesterification reaction, it is preferable to add the above-mentioned raw materials, polycondensation catalyst, and the aforementioned hindered phenolic antioxidant and other additives to the obtained polyester oligomer as necessary. Under reduced pressure below 1 kPa, proceed at a temperature of 260 to 290°C until polyester with the desired viscosity is obtained. When the reaction temperature of the melt polycondensation reaction does not reach 260°C, the polymerization activity of the polymerization catalyst is low, and there is a risk that polyester with the target polymerization degree may not be obtained. On the other hand, when the reaction temperature of the melt polymerization reaction exceeds 290° C., the decomposition reaction proceeds easily, and as a result, there is a risk that a polyester with a target degree of polymerization may not be obtained. The melt polycondensation reaction can be performed using, for example, a tank-type batch-type polycondensation device, a continuous polycondensation device composed of a biaxial rotary horizontal reactor, and the like.

As the polymerization catalyst used in the above-mentioned condensation polymerization, any catalyst that can be used in the production of polyester can be selected, and preferably includes germanium, titanium, zirconium, hafnium, antimony, tin, magnesium, calcium, zinc, aluminum, cobalt, Compounds of metal elements such as lead, cesium, manganese, lithium, potassium, sodium, copper, barium, and cadmium. Among them, compounds containing germanium element, antimony element, and titanium element are preferred. As compounds containing antimony elements, antimony trioxide, antimony chloride, antimony acetate, etc. can be used; as compounds containing germanium elements, germanium dioxide, germanium tetrachloride, germanium tetraethoxide, etc. can be used; as compounds containing titanium elements, As compounds, tetraisopropyl titanate, tetrabutyl titanate, etc. can be used. Furthermore, examples of the polymerization catalyst include composite particles of hydrotalcite and titanium dioxide. Among these, antimony trioxide and germanium dioxide are preferred from the viewpoint of polymerization catalyst activity, physical properties of the polyester obtained, 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.

In the above-described condensation polymerization, phosphoric acid compounds including phosphorous acid or esters thereof may be used in the above-described condensation polymerization as long as they are within a range that does not impede the effects of the present invention. These compounds may be used alone or in combination of two or more types. Examples of the phosphoric acid compound include phosphorous acid, phosphite ester, phosphoric acid, trimethyl phosphate, triphenyl phosphate, and the like. The amount of the anti-coloring agent used is preferably in the range of 20 to 1000 ppm relative to the total of the dicarboxylic acid component and the diester component. In order to suppress coloring due to thermal decomposition of the polyester, a cobalt compound such as cobalt acetate may be added. The usage amount is preferably in the range of 20 to 1000 ppm based on the total of the dicarboxylic acid component and the diester component.

In the above-mentioned condensation polymerization, in order to form the aforementioned dicarboxylic acid unit, a dicarboxylic acid ester can be used. The alcohol part of the dicarboxylic acid ester is not particularly limited, and examples thereof include monoalcohols such as methanol and ethanol; and polyols such as the diols that are the constituent units of the polyester.

In the above-mentioned condensation polymerization, in order to form the aforementioned diol unit, a monoester or diester of a linear aliphatic diol can be used. The carboxylic acid part 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 ultimate viscosity of the polyester obtained by melt polycondensation is preferably 0.4 dl/g or more. This improves operability, and when the polyester obtained by melt polycondensation is further subjected to solid-phase polymerization, a high molecular weight can be achieved in a short time, thereby improving productivity. The aforementioned ultimate viscosity is more preferably 0.55 dl/g or more, particularly preferably 0.65 dl/g or more. On the other hand, the limiting viscosity is preferably 0.9 dl/g or less, more preferably 0.85 dl/g or less, and particularly preferably from the viewpoint of easily removing the polyester from the reactor or suppressing coloration due to thermal deterioration. It is below 0.8dl/g.

The polyester thus obtained is suitable as a raw material for extrusion molding. Furthermore, it is also preferable to further subject the polyester obtained by melt polycondensation to solid phase polymerization. This solid phase polymerization will be described below.

The polyester obtained in the above manner is extruded into shapes such as strands and sheets. After cooling, it is cut by a strand cutting machine or a sheet cutting machine to produce cylindrical, elliptical columnar, or cylindrical shapes. Intermediate particles (pellets) in the shape of discs, grains, etc. The cooling after extrusion can be performed, for example, by a water cooling method using a water tank, a method using a cooling cylinder, an air cooling method, or the like.

In order to further increase the degree of polymerization of the intermediate particles thus obtained, solid phase polymerization is performed. It is preferable to heat and crystallize part of the polyester in advance before solid phase polymerization. This prevents particle sticking during solid phase polymerization. The crystallization temperature is preferably 100 to 180°C. As a method of crystallization, it can be crystallized in a vacuum rolling machine, or it can be heated in an air circulation heating device to crystallize it. When heating in an air circulation heating device, the internal temperature is preferably 100 to 160°C. When using an air circulation heating device for heating, compared to using a vacuum rolling machine for crystallization, the time required for crystallization can be shortened due to good heat conduction, and the device is also cheaper. The time required for crystallization is not particularly limited, but is usually about 30 minutes to 24 hours. Prior to crystallization, the particles can be dried at temperatures up to 100°C.

The temperature of solid phase polymerization is preferably 170 to 250°C. When the temperature of solid phase polymerization is less than 170° C., the time for solid phase polymerization becomes long and productivity may decrease. The temperature of solid phase polymerization is more preferably 175°C or higher, and particularly preferably 180°C or higher. On the other hand, when the temperature of solid-state polymerization exceeds 250°C, there is a risk of particle sticking. The temperature of solid phase polymerization is more preferably 240°C or lower, particularly preferably 230°C or lower. The time for solid phase polymerization is usually about 5 to 70 hours. In addition, the catalyst used in melt polymerization may be coexisting during solid phase polymerization.

In addition, solid phase polymerization is preferably performed under reduced pressure or in an inert gas such as nitrogen. In addition, in order to prevent the particles from sticking together, it is preferable to perform solid-phase polymerization while rolling the particles by an appropriate method such as a rotation method or a gas fluidized bed method. When solid phase polymerization is performed under reduced pressure, the pressure is preferably 1 kPa or less.

The polyester obtained by solid phase polymerization is suitable for extrusion molding, especially as a raw material for extrusion blow molding.

As mentioned above, the polyester obtained by carrying out melt polycondensation or further solid-state polymerization may contain other additives, such as dyes or pigments, as long as the effects of the present invention are not impaired. stabilizers, antistatic agents, flame retardants, flame retardant auxiliaries, lubricants, plasticizers, inorganic fillers, etc. The content of these additives in the polyester is preferably 10 mass% or less, more preferably 5 mass% or less.

The ultimate viscosity of the polyester obtained by solid phase polymerization is preferably 0.9 dl/g or more. Thereby, the sag resistance of the polyester during extrusion blow molding is further improved. The aforementioned ultimate viscosity is more preferably 1.0 dl/g or more, particularly preferably 1.05 dl/g or more. On the other hand, the limiting viscosity is preferably 1.5 dl/g or less.

The manufacturing method of the aforementioned polylactic acid is not particularly limited, and a general manufacturing method of polylactic acid can be adopted. Specifically, a one-stage direct polymerization method in which lactic acid and the compound represented by the above formula (I) are dehydrated and polycondensed in a solvent can be used.

Examples of the catalyst include metals such as tin, zinc, lead, titanium, bismuth, zirconium, germanium, antimony, aluminum and their derivatives. As the derivative, metal alkoxides, carboxylates, carbonates, oxides, and halides are preferred. Specific examples include tin chloride, tin acetate, tin octoate, zinc chloride, lead oxide, lead carbonate, titanium chloride, titanium alkoxide, germanium oxide, zirconium oxide, etc. Among them, the more Preferably it is a tin compound, more preferably it is tin acetate or tin octoate.

The polymerization reaction is carried out in the presence of the above-mentioned catalyst. Although it also varies depending on the type of catalyst, it can usually be carried out at a temperature of 100 to 200°C. In addition, in order to remove water generated along with the polymerization reaction, the polymerization reaction is preferably performed under reduced pressure conditions, preferably 7 kPa or less, more preferably 1.5 kPa or less.

In addition, during the polymerization reaction, a compound containing two or more hydroxyl groups or amine groups in the molecule can be used as a polymerization initiator. Here, compounds containing two or more hydroxyl groups or amine groups in the molecule used as the polymerization initiator include ethylene glycol, propylene glycol, butylene glycol, hexylene glycol, octanediol, and neopentyl glycol. , diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol, glycerin, trimethylolpropane, pentaerythritol, dipentaerythritol, tripentaerythritol, sorbitol, poly(vinyl alcohol), poly(methyl) Polyols such as hydroxyethyl acrylate) and poly(hydroxypropyl methacrylate), polyamines such as ethylenediamine, propylenediamine, butanediamine, hexamethylenediamine, diethylenetriamine, melamine, etc. Among them, polyols are more preferred.

The amount of the polymerization initiator added is not particularly limited, but it is preferably 0.001 to 5 parts by mass, more preferably 0.01 to 3 parts by mass based on 100 parts by mass of the raw materials (L-lactic acid, D-lactic acid) used. share.

The solvent used is not particularly limited as long as it does not affect polymerization, and water or an organic solvent can be used. In the case of organic solvents, aromatic hydrocarbons can be cited, for example. Examples of aromatic hydrocarbons include toluene, xylene, naphthalene, chlorobenzene, diphenyl ether, and the like. In addition, polymerization can be accelerated by discharging water generated by the condensation reaction out of the system. As a method of discharging to the outside of the system, polymerization is preferably carried out under reduced pressure conditions, specifically 7 kPa or less, preferably 1.5 kPa or less.

By melt-molding the obtained polyester, various molded products can be obtained. In the polyester of the present invention, since gelation and coloring are suppressed, a molded article having excellent appearance is obtained. The b value of the polyester (pellet) of the present invention is usually 0 to 20. The lower the value, the less yellowish tone, and the appearance of the resulting molded article becomes beautiful and preferable. Therefore, the b value is preferably 10 or less, more preferably 5 or less, and particularly preferably 3 or less. The b value of the polyester of the present invention is measured by the method described in the Examples.

The molding method is not particularly limited, and extrusion molding can be suitably used. Since the polyester of the present invention has non-Newtonian properties suitable for extrusion molding and the like, it is suitable for such molding methods. A molded article obtained by extruding the polyester is a preferred embodiment of the present invention. A film or sheet formed by extruding the aforementioned polyester is a better embodiment of the present invention. In addition, a container formed by extruding the polyester is also a more preferred embodiment of the present invention. The aforementioned polyester has non-Newtonian properties suitable for extrusion molding. The temperature of the resin composition during extrusion molding is preferably within the range of (melting point of polyester + 10°C) to (melting point of polyester + 70°C), more preferably (melting point of polyester + 10°C) ~ (melting point of polyester + 40°C). By extruding at a temperature closer to the melting point, drawdown can be suppressed.

When using the above-mentioned polyester to produce sheets or films by extrusion molding such as the T-die method or the inflation method, no sagging, necking, film unevenness, or gelling will occur, and high-quality products can be produced with good productivity. Thin or film. Furthermore, when the sheet or film thus obtained is subjected to secondary processing such as thermoforming, the intended molded article can be obtained with good formability when forming into a deep-drawn molded article or a large-sized molded article. Such thermoformed products obtained by thermoforming a sheet or film, especially a container formed by thermoforming the aforementioned sheet or film, are also suitable embodiments of the present invention.

Furthermore, among extrusion moldings, extrusion blow molding is particularly suitable for using the above-mentioned polyester. The method of extrusion blow molding is not particularly limited and can be carried out in the same manner as the conventional extrusion blow molding method. For example, it can be carried out by melt-extruding the polyester to form a cylindrical parison, clamping the parison with a blow mold while the parison is in a softened state, and blowing gas such as air into the parison. The parison expands into a predetermined hollow shape that conforms to the shape of the mold cavity. When the above-mentioned polyester is used, the extruded parison has good sag resistance, and hollow molded products can be manufactured with good productivity.

As the above-mentioned extrusion molding, special-shaped extrusion molding is also preferred. Even if the polyester has a high melt tension, it suppresses gel formation or coloring, so it is also suitable for special-shaped extrusion molding. The method of special-shaped extrusion molding is not particularly limited and can be carried out in the same manner as the conventional special-shaped extrusion molding method. For example, the polyester can be formed by melt-extruding it from a die of a specific shape. Even if the polyester has a high ultimate viscosity or melt tension, gel formation or coloring is suppressed, so special-shaped extrusion molded products having a specific cross-sectional shape can be manufactured with good productivity.

A molded article obtained by extrusion blow molding of the polyester or a molded article obtained by special-shaped extrusion molding is also a suitable embodiment of the present invention. The polyester of the present invention has non-Newtonian properties suitable for extrusion blow molding. At the same time, compared with other resins, despite polycondensation at high temperatures, gel formation or coloring is suppressed, resulting in a molded article with excellent appearance. . In addition, even if the melt tension of the polyester is high, gel formation or coloring is suppressed, so a molded article obtained by special-shaped extrusion molding of the polyester also has an excellent appearance. Furthermore, the polyester of the present invention is safe. Therefore, these molded products can be used for various purposes. A container formed from the extrusion blow molded product is a suitable embodiment of the molded product. Such a container can be used as a container for filling soft drinks, seasonings, oils, cosmetics, lotions, and other products. A price rail made of the aforementioned special-shaped extrusion molded product is a suitable embodiment of the molded product. Furthermore, a molded article having a laminated structure of the above-mentioned polyester and its thermoplastic resin or the like may also be used. [Example]

Hereinafter, the present invention will be explained more specifically using examples.

(1) Ultimate viscosity The ultimate viscosity of polyester particles after melt polymerization and polyester after solid-state polymerization is measured using an equal mass mixture of phenol and 1,1,2,2-tetrachloroethane as a solvent at a temperature of 30°C.

(2) Melting point Tm and glass transition temperature Tg The melting point Tm and glass transition temperature Tg of polyester were measured using a differential scanning calorimeter (TA Q2000 model manufactured by TA Instruments). The melting point Tm and glass transition temperature Tg are the data when the temperature is raised from 30°C to 280°C at a heating rate of 10°C/min, rapidly cooled to 30°C at -50°C/min, and then heated again at a heating rate of 10°C/min. Come figure it out.

(3) Composition The ratio of ^each monomer unit constituting the polyester (Model Ear%).

(4)b value The b value of the resin particles was measured using a colorimeter "LabScan XE" manufactured by HunterLab. Place resin particles in the quartz tank, tap the side of the container while filling, cover with a black cup, measure 5 times, and calculate the average value. The lower the b value is from 0 to 20, the yellower tone is reduced, and the appearance of the resulting molded product becomes more beautiful and preferable.

(5) Production of bottles Using the electric blow molding machine MSE-40E/32M-A (T1) manufactured by TAHARA Co., Ltd., the maximum temperature of the barrel is 280°C, the mold temperature is 250°C, the molding cycle is 15 seconds, the screw rotation speed is 22rpm, and the extrusion resin pressure The obtained polyester was extruded and blow molded at 26 MPa and a mold temperature of 30° C. to obtain a transparent bottle (27.5 g ± 0.5 g) with a volume of 220 ml.

(6) Melt tension Using Capilograph 1D manufactured by Toyo Seiki Seisakusho Co., Ltd., the melt tension (mN) was measured by extruding polyester into a strand shape at a measurement temperature of 290°C, a capillary length of 10 mm, a capillary diameter of 1 mm, and a piston lowering speed of 10 mm/min. , evaluated based on the following criteria. AA: More than 0.63mN A: More than 0.6mN and less than 0.63mN B: 0.6mN or less

(7)Hang speed Using an electric blow molding machine MSE-40E/32M-A (T1) manufactured by TAHARA Co., Ltd., polyester was extruded with a lip opening of 0.8mm. The time it took for the formed parison to reach 277mm from the tip of the lip was measured, and the droop speed was calculated. (mm/s). AA: less than 18.0mm/s A: 18.0mm/s or more and less than 20.0mm/s B: 20.0mm/s or more and less than 25.0mm/s C: 25.0mm/s or more

(8) Number of pits: Use Toyo Seiki's single-screw extruder D2020 to produce 100 μm sheets with the maximum barrel temperature of 280°C, screw rotation speed of 65rpm, traction speed of 1.6m/min, and traction roller temperature of 70°C. Disadvantages of use The detector uses a microscope with a ^25x lens to count the number of pits that can visually identify the boundary between the pitted part and the normal part with a diameter (circle equivalent diameter) of 50 μm or more for 0.5m2. A: Less than 3,000 B: More than 3,000

Example 1 Preparation of 50.97 parts by mass of terephthalic acid, 22.86 parts by mass of ethylene glycol and cyclohexane-1,4-dimethanol [CHDM, the mixing ratio of cis and trans isomers (cis isomer/trans body) is a slurry composed of 2.16 parts by mass of 30/70], to which polyoxyethylene (20) sorbitan monolaurate (a compound represented by formula (I), formula (I)) is added as a cross-linking agent ), the total of x, y, z and w is 20, R ² to R ⁴ are hydrogen atoms, R ¹ is C=O(CH ₂ ) ₁₀ CH ₃ ) 0.082 parts by mass, and germanium dioxide 0.00864 as a catalyst Parts by mass: 0.006 parts by mass of phosphorous acid as an antioxidant. Table 1 also shows the feed amount at this time. This mixed solution is heated to a temperature of 250°C under pressure (absolute pressure 0.25MPa) to perform an esterification reaction to produce a low polymer. Under reduced pressure of 1 hPa, the aforementioned low polymer was melted and polycondensed at a temperature of 280°C to obtain a polyester with an ultimate viscosity of 0.76 dl/g. The obtained polyester was extruded from a nozzle into a strand shape, water-cooled, and then cut into a cylindrical shape (diameter about 2.5 mm, length about 2.5 mm) to obtain polyester pellets (melt polycondensation pellets). Table 2 shows the evaluation results of the obtained polyester particles.

Example 2 It was carried out in the same manner as in Example 1 except that 0.006 parts by mass of phosphorous acid and 0.006 parts by mass of pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] were used as antioxidants. Polyester particles (melt polycondensation particles) were obtained. Table 2 shows the ultimate viscosity of the obtained polyester and the evaluation results of the polyester particles.

Example 3 In addition to using 48.9 parts by mass of terephthalic acid, 19.63 parts by mass of ethylene glycol and cyclohexane-1,4-dimethanol [CHDM, the mixing ratio of cis and trans isomers (cis isomer/trans isomer) Polyester particles (melt polycondensation particles) were obtained in the same manner as in Example 2 except that the slurry was 30/70]7.42 parts by mass. Table 2 shows the ultimate viscosity of the obtained polyester and the evaluation results of the polyester particles.

Example 4 Polyester particles (melt polycondensation particles) were obtained in the same manner as in Example 2 except using a slurry composed of 49.23 parts by mass of terephthalic acid, 24.19 parts by mass of ethylene glycol, and 2.59 parts by mass of isophthalic acid. Table 2 shows the ultimate viscosity of the obtained polyester and the evaluation results of the polyester particles.

Example 5 In a reaction container equipped with a stirring device, 150 parts by mass of lactic acid was heated at 800 Pa and 160° C. for 3.5 hours to obtain an oligomer. Next, 0.12 parts by mass of tin acetate (II) (manufactured by Kanto Chemical Co., Ltd.), 0.33 parts by mass of methanesulfonic acid (manufactured by Wako Pure Chemical Industries, Ltd.), polyoxyethylene (20) sorbitan monolaurate 0.199 parts by mass was added to the oligomer and heated at 500 Pa and 180° C. for 7 hours to obtain a prepolymer. Next, the prepolymer was heated at 120°C for 2 hours in an oven to crystallize. The obtained prepolymer was pulverized using a hammer mill and sieved to obtain powder with an average particle diameter of 0.1 mm. In solid-state polymerization, 150 parts by mass of the prepolymer was introduced into an oven connected to an oil rotary pump, and heated and depressurized. The pressure was set to 50 Pa, and the heating temperature and heating time were set to 140°C: 10 hours, 150°C: 10 hours, and 160°C: 20 hours. Table 2 shows the ultimate viscosity of the obtained polyester and the evaluation results of the polyester particles.

Comparative example 1 Polyester particles were obtained in the same manner as in Example 1 except that polyoxyethylene (20) sorbitan monolaurate was not added and the feed amount was changed as shown in Table 1. Table 2 shows the ultimate viscosity of the obtained polyester and the evaluation results of the polyester particles.

Comparative example 2 Polyester particles were obtained in the same manner as in Example 1 except that polyoxyethylene (20) sorbitan monolaurate was not added and the feed amount was changed as shown in Table 1. Table 2 shows the ultimate viscosity of the obtained polyester and the evaluation results of the polyester particles.

Comparative example 3 Polyester particles were obtained in the same manner as in Example 1 except that polyoxyethylene (20) sorbitan monolaurate was not added and the feed amount was changed as shown in Table 1. Table 2 shows the ultimate viscosity of the obtained polyester and the evaluation results of the polyester particles.

Comparative example 4 Polyester particles were obtained in the same manner as in Example 1 except that polyoxyethylene (20) sorbitan monolaurate was not added and the feed amount was changed as shown in Table 1. Table 2 shows the ultimate viscosity of the obtained polyester and the evaluation results of the polyester particles.

Example 6 The polyester particles obtained in Example 1 were put into a universal mixer and heated at 120° C. for 2 hours while stirring to obtain pre-crystallized polyester.

The preliminarily crystallized polyester was put into a rotary vacuum solid-state polymerization apparatus, and solid-phase polymerized at 200° C. and 1 torr for 107 hours to obtain polyester particles (solid-phase polymerized particles). Table 2 shows the evaluation results of the obtained polyester particles.

Example 7 Polyester particles (solid phase polymerization particles) were obtained in the same manner as in Example 6, except that the polyester particles obtained in Example 2 were used. Table 2 shows the evaluation results of the obtained solid phase polymer particles.

Example 8 Polyester particles (solid phase polymerization particles) were obtained in the same manner as in Example 6, except that the polyester particles obtained in Example 3 were used. Table 2 shows the evaluation results of the obtained solid phase polymer particles.

Example 9 Polyester particles (solid phase polymerization particles) were obtained in the same manner as in Example 6, except that the polyester particles obtained in Example 4 were used. Table 2 shows the evaluation results of the obtained solid phase polymer particles.

Comparative example 5 In addition to using 51.00 parts by mass of terephthalic acid, 22.89 parts by mass of ethylene glycol and cyclohexane-1,4-dimethanol [CHDM, the mixing ratio of cis and trans isomers (cis isomer/trans isomer) Polyester particles (melt polycondensation particles) were obtained in the same manner as in Example 1, except that a slurry consisting of 2.16 parts by mass of 30/70] and 0.02 parts by mass of trimellitic anhydride as a cross-linking agent were used.

Polyester particles (solid phase polymerization particles) were obtained in the same manner as in Example 6, except that the obtained polyester particles (melt polycondensation particles) were used. Table 2 shows the evaluation results of the obtained solid phase polymer particles.

Comparative example 6 In addition to using 50.98 parts by mass of terephthalic acid, 22.87 parts by mass of ethylene glycol and cyclohexane-1,4-dimethanol [CHDM, the mixing ratio of cis and trans isomers (cis isomer/trans isomer) Polyester particles (melt polycondensation particles) were obtained in the same manner as in Example 1, except that a slurry composed of 2.16 parts by mass of 30/70] and 0.07 parts by mass of trimethylolpropane as a cross-linking agent were used.

Polyester particles (solid phase polymerization particles) were obtained in the same manner as in Example 6, except that the obtained polyester particles (melt polycondensation particles) were used. Table 2 shows the evaluation results of the obtained solid phase polymer particles.

Example 10 In addition to using 50.50 parts by mass of terephthalic acid, 22.61 parts by mass of ethylene glycol and cyclohexane-1,4-dimethanol [CHDM, the mixing ratio of cis and trans isomers (cis isomer/trans isomer) Polyester particles (melt polycondensation particles) were obtained in the same manner as in Example 2, except that a slurry consisting of 2.14 parts by mass of 30/70] and 0.817 parts by mass of a cross-linking agent were added. Table 2 shows the ultimate viscosity of the obtained polyester and the evaluation results of the polyester particles.

Comparative example 7 In addition to using 50.01 parts by mass of terephthalic acid, 22.36 parts by mass of ethylene glycol and cyclohexane-1,4-dimethanol [CHDM, the mixing ratio of cis and trans isomers (cis isomer/trans isomer) Polyester particles (melt polycondensation particles) were obtained in the same manner as in Example 2 except that a slurry consisting of 2.12 parts by mass of 30/70] and 1.565 parts by mass of a cross-linking agent were added. Table 2 shows the ultimate viscosity of the obtained polyester and the evaluation results of the polyester particles.

Claims (13)

A polyester containing 0.001 to 0.2 mol % of units derived from the compound represented by the following formula (I) relative to all monomer units; [In the formula (I), the total of x, y, z and w is 1 to 50, and R ¹ to R ⁴ each independently represent a hydrogen atom or a hydroxyl group having 1 to 18 carbon atoms]. The polyester of claim 1, wherein the compound represented by the above formula (I) is selected from the group consisting of polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monostearate, and polyoxyethylene sorbitol monooleate. At least one kind from the group consisting of tristearic acid polyoxyethylene sorbitan anhydride, trioleic acid polyoxyethylene sorbitan anhydride and trioleic acid polyoxyethylene sorbitan anhydride. The polyester of claim 1 or 2 further contains 0.0005 to 0.2 mol% of units derived from hindered phenol antioxidants relative to all monomer units. The polyester of claim 1 or 2, wherein the polyester is selected from the group consisting of polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, and polyethylene furandicarboxylate. At least one kind from the group consisting of ester and polylactic acid. The polyester of claim 1 or 2, wherein the polyester is polyethylene terephthalate containing 1.5 to 25 mol% of cyclohexanedimethanol units or isophthalic acid units based on all monomer units. . For example, the polyester of claim 1 or 2 has an ultimate viscosity of 0.70dl/g or above. A molded article obtained by extruding the polyester according to any one of claims 1 to 6. The molded article of claim 7 is obtained by extrusion blow molding the polyester. The molded article of claim 7 is obtained by subjecting the polyester to special-shaped extrusion molding. A film or sheet made of the molded article of claim 7 or 8. A thermoformed product obtained by thermoforming the film or sheet according to claim 10. A container made of the molded article of claim 7 or 8. A method for producing a polyester according to any one of claims 1 to 6, which comprises polycondensing an ester-forming monomer and a compound represented by the above formula (I).