Dimethyl terephthalate composition, and polyester

Abstract

To provide a dimethyl terephthalate composition capable of producing a polyester which suppresses blocking between powders when stored for a long period of time in a state of being filled in a packaging material such as a flexible container, is excellent in fluidity of the produced polyester, and is excellent in discharge speed from a die, and to provide a polyester using the dimethyl terephthalate composition.SOLUTION: The dimethyl terephthalate composition contains an amide compound represented by formula (1) in an amount of 0.0001 mass% or more and 1 mass% or less based on dimethyl terephthalate. The polyester is obtained by reacting the dimethyl terephthalate composition with a diol component. (In the above formula (1), R1 represents a linear saturated or unsaturated hydrocarbyl group having 11 to 30 carbon atoms, R2 represents hydrogen or an n-valent hydrocarbyl group, n is 1 or 2, and when R2 is hydrogen, n is 1.). ) SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a dimethyl terephthalate composition and a polyester using this dimethyl terephthalate composition. More specifically, the present invention relates to a dimethyl terephthalate composition that suppresses blocking of powder raw materials and enables the production of a polyester with excellent fluidity and discharge speed from a die, and to a polyester obtained by reacting this dimethyl terephthalate composition with a diol component. [Background technology]

[0002] Polyester is widely used in applications such as fibers, films, and molded products due to its excellent strength, thermal stability, and chemical resistance. Dimethyl terephthalate is widely used as a raw material for the manufacture of polyester, but when stored for long periods in packaging materials such as flexible containers, the powder particles block each other, making it difficult to remove from the packaging. In addition, in the manufacturing process of polyester, the molten resin extruded from a strand die is generally cooled and cut to form pellets. However, when the melt viscosity of the resin is high, the extrusion speed is limited, reducing production efficiency, and the long time required for extraction leads to quality changes over time.

[0003] Patent Document 1 proposes a dimethyl terephthalate composition that suppresses problems arising from by-products of dimethyl terephthalate obtained by the Witten-Hercules process, which involves air oxidation of paraxylene and methyl p-toluate to obtain an oxidation reaction mixture, esterifying it with methanol under high temperature and high pressure conditions, and separating and purifying dimethyl terephthalate from the esterification reaction mixture, thereby improving its properties as a polyester raw material. The composition is primarily composed of dimethyl terephthalate and contains 0.001 to 200 ppm of methyl 4-(1,3-dioxolan-2-yl)benzoate and 0 to 1 ppm of dimethyl hydroxyterephthalate. However, this dimethyl terephthalate composition cannot solve the aforementioned problems. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2002-220362 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] The object of the present invention is to provide a dimethyl terephthalate composition that suppresses blocking between powder particles when stored for a long period of time in a packaging material such as a flexible container, and that enables the production of polyester with excellent fluidity and excellent discharge speed from a die, as well as a polyester using this dimethyl terephthalate composition. [Means for solving the problem]

[0006] The inventors of the present invention conducted extensive research to solve the above problems and found that the above problems can be solved by using a dimethyl terephthalate composition containing a small amount of a specific amide compound in addition to dimethyl terephthalate, thereby completing the present invention. In other words, the present invention relates to the following invention.

[0007] [1] A dimethyl terephthalate composition comprising 0.0001% by mass or more and 1% by mass or less of an amide compound represented by the following formula (1) with respect to dimethyl terephthalate.

[0008] [ka]

[0009] (In the above equation (1), R 1 R represents a straight-chain saturated or unsaturated hydrocarbon group with 11 to 30 carbon atoms. 2 represents a hydrogen atom or an n-valent hydrocarbon group, where n is 1 or 2, and R 2 When n is a hydrogen atom, n is 1.

[0010] [2] The above R 1 The dimethyl terephthalate composition according to [1], wherein is a linear saturated or unsaturated hydrocarbon group having 15 to 21 carbon atoms. [3] The dimethyl terephthalate composition according to [1] or [2], wherein the dimethyl terephthalate composition is obtained by chemical recycling. [4] A polyester obtained by reacting a dimethyl terephthalate composition described in any of [1] to [3] with a diol component. [5] The polyester according to [4], wherein 50 mol% or more of the diol component is 1,4-butanediol. [6] The polyester according to [4] or [5], wherein the diol component is derived from biomass. [7] The polyester according to [4] or [5], wherein the diol component is produced by the depolymerization of the polyester. [Effects of the Invention]

[0011] The dimethyl terephthalate composition of the present invention suppresses blocking of powder raw materials and enables the production of polyesters that have excellent fluidity and a high discharge rate from the die. The polyester obtained by reacting the dimethyl terephthalate composition of the present invention with a diol component can be preferably used for various applications such as electric and electronic parts, automobile parts, films, sheets, filaments and the like.

Embodiments for Carrying Out the Invention

[0012] Hereinafter, embodiments of the present invention will be described in detail. However, the description of the constituent elements described below is an example of an embodiment of the present invention, and the present invention is not limited to the following description as long as it does not exceed the gist thereof. In the present specification, when the expression "~" is used, it is used as an expression including the numerical values or physical property values before and after it. In the present invention, the "main component" in the dicarboxylic acid component means a component contained in the component at 50 mol% or more. The same applies to the "main component" in the diol component.

[0013] [Dimethyl terephthalate composition] The dimethyl terephthalate composition according to an embodiment of the present invention contains dimethyl terephthalate and a predetermined amount of an amide compound represented by the following formula (1) (hereinafter, may be referred to as "compound (1)" or "amide compound (1)").

[0014]

Chemical formula

[0015] (In the above formula (1), R 1 represents a linear saturated or unsaturated hydrocarbon group having 11 to 30 carbon atoms, R 2 represents a hydrogen atom or an n-valent hydrocarbon group, n is 1 or 2, and when R 2 is a hydrogen atom, n is 1.)

[0016] In the above formula (1), R 1As the linear saturated or unsaturated hydrocarbon group having 11 to 30 carbon atoms, a linear saturated or unsaturated hydrocarbon group having 15 to 21 carbon atoms is preferable from the viewpoints of imparting fluidity and suppressing blocking.

[0017] R 2 As the hydrocarbon group of, when n = 1, examples thereof include alkyl groups having 1 to 10 carbon atoms such as methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, s-butyl group, t-butyl group, etc.; when n = 2, examples thereof include alkylene groups having 1 to 10 carbon atoms such as methylene group, ethylene group, propylene group, butylene group, etc.

[0018] Specific examples of the compound (1) include palmitic acid amide, oleic acid amide, stearic acid amide, erucic acid amide, ethylene bis stearic acid amide, etc.; preferably palmitic acid amide, oleic acid amide, stearic acid amide; particularly preferably stearic acid amide. The compound (1) may be used alone or in combination of two or more.

[0019] By including the compound (1) together with dimethyl terephthalate, it is possible to prevent the fusion of the powders of the dimethyl terephthalate composition. Therefore, blocking during storage under a load such as filling in a plastic container can be suppressed, and the powder raw material can be stored in a state with good handling properties. Further, by producing a polyester using the dimethyl terephthalate composition of the present invention, the fluidity of the obtained polyester is increased. Thereby, the discharge rate from the die in the extraction step during production is increased, the quality change due to the change over time during extraction is suppressed, and the production efficiency can be enhanced. Although the details of the reason for such an effect are not clear, it is considered to be due to the segregation of the amide compound (1) on the surfaces of dimethyl terephthalate and the polyester resin.

[0020] The content of the amide compound (1) in the dimethyl terephthalate composition of the present invention is 0.0001% by mass or more and 1% by mass or less relative to dimethyl terephthalate, preferably 0.0005% by mass or more and 0.7% by mass or less, and more preferably 0.001% by mass or more and 0.5% by mass or less. By having a content of amide compound (1) above the lower limit, the effects of the present invention described above due to the inclusion of amide compound (1) can be fully obtained. Furthermore, by having a content below the upper limit, sufficient reactivity in the polycondensation reaction can be ensured, and a polyester with good color tone can be obtained.

[0021] The dimethyl terephthalate composition of the present invention preferably consists substantially of dimethyl terephthalate and the above-mentioned amide compound (1). Here, "substantially consisting of dimethyl terephthalate and amide compound (1)" means that the total content of dimethyl terephthalate and amide compound (1) in the dimethyl terephthalate composition is preferably 98% by mass or more, more preferably 99% by mass or more, and particularly preferably 99.5 to 100% by mass.

[0022] The method for producing the dimethyl terephthalate composition of the present invention is not particularly limited, but examples include adding and mixing an amide compound (1) to molten dimethyl terephthalate (a method of melting and mixing dimethyl terephthalate and amide compound (1)). To sufficiently suppress the blocking effect of dimethyl terephthalate, it is preferable that the amide compound (1) is uniformly mixed in dimethyl terephthalate.

[0023] Furthermore, the dimethyl terephthalate and amide compounds (1) used in the production of the dimethyl terephthalate composition are not limited to those produced from fossil fuels, but may also be produced from biomass resources, recycled from product waste or defective products, or may be mixtures of two or more of these. For example, the dimethyl terephthalate composition used in the present invention, and the dimethyl terephthalate and amide compound (1) in the dimethyl terephthalate composition, may be obtained by chemical recycling of polyesters such as polyethylene terephthalate or polybutylene terephthalate, for example, by depolymerization of polyesters such as polyethylene terephthalate or polybutylene terephthalate.

[0024] [Method for manufacturing polyester] One method for producing polyester using the dimethyl terephthalate composition of the present invention is to carry out a transesterification reaction between the dimethyl terephthalate composition of the present invention and a diol component in the presence of a transesterification catalyst.

[0025] The present invention will primarily describe a method for producing polyester using a diol component containing 1,4-butanediol (hereinafter sometimes abbreviated as "BDO") as the diol component, and producing polybutylene terephthalate (hereinafter sometimes abbreviated as "PBT") as the polyester. However, according to the present invention's method for producing polyester, polyesters other than PBT, such as polyethylene terephthalate (hereinafter sometimes abbreviated as "PET"), can be produced using diol components other than 1,4-butanediol, in a similar manner to the method described below.

[0026] In the following, polyester produced by the polyester production method of the present invention may be referred to as "the polyester of the present invention," and PBT produced by the polyester production method of the present invention may be referred to as "the PBT of the present invention."

[0027] PBT refers to a polymer having a structure in which dicarboxylic acid and diol components are ester-bonded, wherein 50 mol% or more of the dicarboxylic acid component consists of terephthalic acid, and 50 mol% or more of the diol component consists of BDO. The proportion of terephthalic acid component in the total dicarboxylic acid component is preferably 70 mol% or more, more preferably 80 mol% or more, and even more preferably 95 mol% or more, and the proportion of BDO in the total diol component is preferably 70 mol% or more, more preferably 80 mol% or more, and even more preferably 95 mol% or more. If the terephthalic acid component or BDO is less than 50 mol%, the crystallization rate of PBT decreases, leading to deterioration of moldability.

[0028] <Dicarboxylic acid component> In the polyester production method of the present invention, the dimethyl terephthalate composition of the present invention is used as the dicarboxylic acid component.

[0029] As for the dicarboxylic acid component, any dicarboxylic acid component other than dimethyl terephthalate can be used, as long as the proportion of the terephthalic acid component satisfies the above preferred ratio. Examples of dicarboxylic acid components other than dimethyl terephthalate include aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, 4,4'-diphenyldicarboxylic acid, 4,4'-diphenyletherdicarboxylic acid, 4,4'-benzophenonedicarboxylic acid, 4,4'-diphenoxyethanedicarboxylic acid, 4,4'-diphenylsulfonedicarboxylic acid, and 2,6-naphthalenedicarboxylic acid; alicyclic dicarboxylic acids such as 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, and 1,4-cyclohexanedicarboxylic acid; and dialkyl esters of aliphatic dicarboxylic acids such as malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, and sebacic acid. The number of carbon atoms in the alkyl group of these dialkyl esters of dicarboxylic acids is preferably 1 to 6. These dicarboxylic acid components other than dimethyl terephthalate may be used individually or as a mixture of two or more. Furthermore, these dicarboxylic acid components other than dimethyl terephthalate may be manufactured using fossil fuels, biomass resources, or recycled from product waste or defective products.

[0030] <Diol component> There are no particular restrictions on the diol components other than BDO that are subjected to the transesterification reaction. Examples include aliphatic diols such as ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, 1,8-octanediol, and dibutylene glycol; alicyclic diols such as 1,2-cyclohexanediol, 1,4-cyclohexanediol, 1,1-cyclohexanedimethylol, and 1,4-cyclohexanedimethylol; polyalkylene glycols such as xylylene glycol, polyethylene glycol, polytrimethylene glycol, and polytetramethylene ether glycol; and aromatic diols such as 4,4'-dihydroxybiphenyl, 2,2-bis(4-hydroxyphenyl)propane, and bis(4-hydroxyphenyl)sulfone. These diol components other than BDO may be used individually or in combination of two or more.

[0031] The diol components such as BDO may be petroleum-derived diol components manufactured from fossil fuels, diol components manufactured from biomass resources, or chemically recycled diol components manufactured from recycled product waste or defective products, or mixtures thereof. Using diol components manufactured from biomass resources or recycled from product waste or defective products is preferable from the perspective of building a circular economy.

[0032] For example, among diol components such as BDO produced from biomass resources, diol components produced by fermentation are preferred. Examples include diol components produced by direct fermentation of sugars, and biomass-derived diol components produced by hydrogenating succinic acid or succinic acid derivatives produced using biomass resources, such as succinic anhydride, dialkyl succinate (more specifically, dialkyl succinate with an alkyl group having 1 to 4 carbon atoms, preferably 1 to 3, more preferably 1 to 2, and most preferably a methyl group with 1 carbon atom) and other succinic acid esters. Furthermore, examples of chemically recycled diol components produced by the depolymerization of waste polyester include chemically recycled BDO obtained by depolymerizing polybutylene terephthalate and chemically recycled ethylene glycol obtained by depolymerizing polyethylene terephthalate.

[0033] <Other monomers> In the present invention, PBT can be produced using one or more copolymer components, such as lactic acid, glycolic acid, m-hydroxybenzoic acid, p-hydroxybenzoic acid, 6-hydroxy-2-naphthalenecarboxylic acid, p-β-hydroxyethoxybenzoic acid, and other hydroxycarboxylic acids, alkoxycarboxylic acids, monofunctional components such as stearyl alcohol, benzyl alcohol, stearic acid, benzoic acid, t-butylbenzoic acid, and benzoylbenzoic acid, and trifunctional or polyfunctional components such as tricarbaryl acid, trimetic acid, trimesic acid, pyrometic acid, gallic acid, trimethylolethane, trimethylolpropane, glycerol, and pentaerythritol.

[0034] The polyester of the present invention may also be PTMG copolymer PBT, which is obtained by copolymerizing crystalline PBT as a hard segment with polytetramethylene ether glycol (hereinafter sometimes referred to as "PTMG") as a soft segment.

[0035] PTMG copolymer PBT can be obtained by transesterifying the dimethyl terephthalate composition of the present invention with a diol component containing BDO and PTMG, and other components as needed, followed by a polycondensation reaction, and preferably a further solid-phase polycondensation reaction.

[0036] In this case, the number-average molecular weight of the PTMG used is preferably 650 to 2000, and more preferably 800 to 1500. A molecular weight within this range results in good reactivity during PTMG copolymerization PBT production, minimal melting point depression due to copolymerization, and yields PTMG copolymerized PBT with good mechanical properties. The molecular weight of PTMG is controlled by the reaction temperature, reaction time, and catalyst amount during PTMG production.

[0037] Furthermore, the lower limit of the copolymerization amount of the PTMG component in PTMG copolymerized PBT is preferably 8% by mass, more preferably 10% by mass, and even more preferably 15% by mass, while the upper limit is preferably 35% by mass, more preferably 30% by mass, and even more preferably 25% by mass. Here, the copolymerization amount (content) of PTMG refers to the proportion of PTMG units as diol components in the PTMG copolymer PBT, that is, the proportion of the amount of PTMG obtained by subtracting the water molecules due to ester bond formation from PTMG, expressed in mass percent relative to the PTMG copolymer PBT. By keeping the PTMG copolymerization ratio within this range, a PTMG copolymerized PBT with a good balance of flexibility and impact strength can be obtained. The amount of PTMG copolymerized can be controlled by the amount of PTMG added during the copolymerization of the PBT.

[0038] <Method for manufacturing polyester> The method for producing polyester according to the present invention is not particularly limited, and the production method may be continuous or batch. One example is a method that involves the following transesterification reaction step and polycondensation reaction step.

[0039] (Transesterification reaction process) An example of the process of transesterifying the dimethyl terephthalate composition of the present invention with a diol component to obtain an oligomer is to use a single transesterification reactor or a multi-stage reactor in which multiple transesterification reactors are connected in series, and carry out the transesterification reaction with or without a catalyst, under atmospheric pressure or reduced pressure, while removing the alcohol produced in the reaction and excess diol component from the system, until the transesterification reaction rate (the proportion of all ester groups of the starting material dicarboxylic acid component that react with the diol component to undergo transesterification) reaches 90% or more, to obtain an oligomer. Typically, the temperature for a transesterification reaction is around 210-230°C, the pressure is around 10-133 kPa, and the residence time in the reaction vessel, which corresponds to the reaction time, is around 1-4 hours.

[0040] (Polycondensation reaction process) An example of a polycondensation reaction process is a multi-stage reactor using a single molten polycondensation tank or multiple molten polycondensation tanks connected in series, for example, a fully mixed reactor with a stirring blade in the first stage, and horizontal plug-flow reactors with stirring blades in the second and third stages, in which the diol produced is distilled out of the system while heating under reduced pressure in the presence of a catalyst. Typically, the polycondensation reaction is carried out at a temperature of 210-280°C, preferably around 220-250°C, and under reduced pressure of 27 kPa or less, preferably 13 kPa or less.

[0041] The reaction vessel may be a single vessel or a multi-stage vessel, but in order to suppress discoloration and deterioration and to suppress the increase of terminal groups such as vinyl groups, it is preferable to carry out the reaction in at least one reaction vessel under a high vacuum of usually 1.3 kPa or less, preferably 0.3 kPa or less.

[0042] Polyester obtained by polycondensation reaction is usually extracted in strand or sheet form from an outlet at the bottom of the polycondensation reaction tank, and then cut with a cutter while or after water cooling to form granular material such as pellets or chips (for example, about 3 to 10 mm in length). Alternatively, the molten resin is released from the polycondensation reaction tank through piping into cold water adjusted to a predetermined temperature and cut with a cutter to form spherical material (about 2 to 10 mm in diameter).

[0043] <Polycondensation catalyst> When polycondensing oligomers obtained by transesterification reactions between diol and dicarboxylic acid components, titanium compounds and, more preferably, Group 2A metal compounds of the periodic table are typically used as catalysts. These catalyst components may be used in the transesterification reaction and then proceed directly to the polycondensation reaction, or they may not be used in the transesterification reaction, or only the titanium catalyst may be used, with the remaining catalyst components added at the polycondensation stage. Furthermore, a portion of the final amount of catalyst to be used may be used in the transesterification reaction, and additional catalysts may be added as appropriate as the polycondensation reaction progresses. In any case, in the present invention, the final polyester will inevitably contain titanium and preferably more Group 2A metals of the periodic table. The content will be described later.

[0044] (Examples of titanium compounds) Specific examples of titanium compounds used as catalysts include inorganic titanium compounds such as titanium oxide and titanium tetrachloride, tetraalkyl titanates such as tetramethyl titanate, tetraisopropyl titanate, and tetrabutyl titanate, and tetraaryl titanates such as tetraphenyl titanate. These may be used individually or in combination of two or more. Among these, tetraalkyl titanate is preferred, and among those, tetrabutyl titanate is preferred.

[0045] (Amount of titanium catalyst) The titanium catalyst content in the polyester of the present invention is preferably 5 to 200 ppm by mass ratio of titanium atoms to polyester. More preferably 10 ppm or more, even more preferably 20 ppm or more, and most preferably 25 ppm or more. Furthermore, more preferably 190 ppm or less, even more preferably 180 ppm or less, particularly preferably 170 ppm or less, especially preferably 160 ppm or less, and most preferably 150 ppm or less. If the titanium content is too high, problems arise with color, hydrolysis resistance, deterioration of solution haze, and an increase in fisheye in the resulting molded product. If the titanium content is too low, polymerization is impaired.

[0046] (Group 2A metal compound) Specific examples of Group 2A metal compounds used as catalysts include various compounds of beryllium, magnesium, calcium, strontium, and barium. However, magnesium compounds and / or calcium compounds are preferred in terms of ease of handling and availability, as well as catalytic effect, and magnesium compounds, which exhibit excellent catalytic effect, are particularly preferred. Specific examples of magnesium compounds include magnesium acetate, magnesium hydroxide, magnesium carbonate, magnesium oxide, magnesium alkoxide, and magnesium hydrogen phosphate. Specific examples of calcium compounds include calcium acetate, calcium hydroxide, calcium carbonate, calcium oxide, calcium alkoxide, and calcium hydrogen phosphate.

[0047] These Group 2A metal compounds may be used individually or in combination of two or more. Among these, magnesium acetate is preferred.

[0048] (Group 2A metal catalyst amount) The content of the Group 2A metal catalyst in the polyester of the present invention is not particularly limited, but it is preferably 3 to 150 ppm by mass ratio of Group 2A metal atoms to the polyester. This amount is more preferably 5 ppm or more, and even more preferably 10 ppm or more. Furthermore, this amount is more preferably 140 ppm or less, even more preferably 130 ppm or less, and particularly preferably 100 ppm or less. If the content of Group 2A metals is too high, the color tone and hydrolysis resistance will deteriorate, and if it is too low, the polymerization properties will deteriorate.

[0049] When using acetate salts of Group 2A metals of the periodic table, the acetic acid source enters the reaction system, so it is preferable that the amount of Group 2A metal in the polyester be 100 ppm or less.

[0050] (M / Ti ratio) The molar ratio (group 2A metal / titanium) of titanium atoms to group 2A metal atoms in the polyester of the present invention is typically 0.01 to 100, preferably 0.1 to 10, more preferably 0.3 to 3, and even more preferably 0.3 to 1.5.

[0051] (Metal analysis method) The metal content, such as titanium atoms, in polyester can be measured using methods such as atomic emission, atomic absorption, or ICP emission after recovering the metals from the polymer by methods such as wet ashing.

[0052] (Other catalysts) In the production of the polyester of the present invention, in addition to the titanium compounds and Group 2A metal compounds of the periodic table mentioned above, reaction aids such as antimony compounds such as antimony trioxide, germanium compounds such as germanium dioxide and germanium tetroxide, manganese compounds, zinc compounds, zirconium compounds, cobalt compounds, orthophosphate, phosphite, hypophosphite, polyphosphate, phosphorus compounds such as esters and metal salts thereof, sodium hydroxide, and sodium benzoate may also be used.

[0053] [Intrinsic viscosity of PBT] When the PBT of the present invention is used in compounding and injection molding, the intrinsic viscosity of the PBT is preferably 0.6 to 1.3 dL / g. If the intrinsic viscosity is less than 0.6 dL / g, the mechanical strength of the molded product will be insufficient, and if it exceeds 1.3 dL / g, the melt viscosity will be high, fluidity will deteriorate, and moldability will tend to worsen. The intrinsic viscosity of the PBT of the present invention is more preferably 0.65 to 1.26 dL / g, and even more preferably 0.7 to 1.2 dL / g.

[0054] Furthermore, when the PBT pellets of the present invention are used for extrusion applications of films, sheets, or filaments, the intrinsic viscosity of PBT is typically 1.00 to 1.60 dL / g, preferably 1.03 to 1.50 dL / g, more preferably 1.05 to 1.55 dL / g, particularly preferably 1.10 to 1.50 dL / g, and especially preferably 1.15 to 1.35 dL / g. If the intrinsic viscosity is less than 1.00 dL / g, the extrusion moldability deteriorates, leading to resin drawdown and molding losses, resulting in insufficient mechanical strength of extruded products such as films, or the melt viscosity becomes low, resulting in excessive fluidity and poor extrusion moldability. On the other hand, if the intrinsic viscosity exceeds 1.60 dL / g, the melt viscosity becomes high, fluidity deteriorates, and extrusion moldability tends to worsen.

[0055] [Compound] The polyester of the present invention can be produced with high productivity using the dimethyl terephthalate composition of the present invention, with excellent reaction efficiency and manufacturing stability, and also exhibits excellent quality in terms of color tone and other characteristics. The polyester of the present invention can be compounded into a product by adding various additives or compounding materials as needed during the polyester manufacturing process or after the polyester has been manufactured. [Examples]

[0056] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples unless it exceeds the gist of the invention.

[0057] [Raw materials and reagents] Dimethyl terephthalate, tetrabutyl titanate, palmitic acid amide, oleic acid amide, stearic acid amide, erucic acid amide, and ethylenebisstearic acid amide were reagents manufactured by Tokyo Chemical Industry Co., Ltd. The petroleum-derived 1,4-butanediol used was a product of Mitsubishi Chemical Corporation. The 1,4-butanediol derived from biomass resources used was 1,4-butanediol manufactured by Zhejiang Boju New Materials Co., Ltd., produced by the hydrogenation of succinic acid. In addition, ADEKA's "ADEKA Stab AO-60" was used as a phenolic antioxidant.

[0058] [Measurement and Evaluation Methods] <Analysis of Dimethyl Terephthalate Composition> The dimethyl terephthalate composition was analyzed by gas chromatography using the following apparatus and conditions. • Equipment: Shimadzu Corporation "GC-2014" • Column: Agilent Technologies "DB-1" (Inner diameter 0.53 mm, column length 30 m, film thickness 1 μm) • Carrier gas: Helium • Carrier gas flow rate: 5.58 cm / min 3 Line speed: 47.4 cm per second ·Inlet temperature: 250℃ Detector temperature: 280℃ • Column heating pattern: First, hold at 150°C for 5 minutes, then increase the temperature at 13°C per minute to 295°C, and hold at 295°C for 15 minutes for analysis.

[0059] <Blocking resistance evaluation> Inner diameter 1cm 2 Ten g of dimethyl terephthalate composition was placed in a cylinder and a load of 0.1 MPa was applied, and the mixture was held at 80°C for 3 hours. After that, the degree to which the powder was loosened by hand was checked, and the blocking resistance was evaluated as follows. S: No blocking A: Some parts are blocked off, but they can be loosened by hand. B: Even after breaking it apart by hand, there are still coarse parts.

[0060] <Transesterification time> In the transesterification reaction, the time at which 90% or more of the theoretical amount of alcohol produced as a by-product when the dimethyl terephthalate composition is completely reacted was defined as the transesterification time.

[0061] <Melt Flow Rate (MFR: [g / 10 min])> Measurements were taken in accordance with JIS K7210 under conditions of 250°C and a load of 2.16 kgf. The MFR of polybutylene terephthalate is preferably 5 g / 10 min or higher from the viewpoint of fluidity, and preferably 300 g / 10 min or lower from the viewpoint of the resulting molded article. While the MFR generally decreases with resins that have high intrinsic viscosity, a higher MFR is preferable from the viewpoint of fluidity for equivalent intrinsic viscosity.

[0062] <Intrinsic viscosity of polybutylene terephthalate> The viscosity was determined using a fully automatic viscosity measuring device (model DT553, capillary type) manufactured by Sentec Co., Ltd., in the following manner. A mixture of phenol and 1,1,2,2-tetrachloroethane (mass ratio 1 / 1) was used as the solvent. At 30°C, the number of seconds for dropping the 1.0 g / dL PBT sample solution and the solvent alone was measured and calculated using the following formula. Intrinsic viscosity (dL / g)=((1+4K H η sp ) 0.5 -1) / (2K H C) (However, η sp =η / η0-1, where η is the number of seconds the sample solution falls, η0 is the number of seconds the solvent falls, C is the PBT concentration of the sample solution (g / dL), and K H K is Huggins' constant. H (0.33 was adopted.)

[0063] <Color tone of polybutylene terephthalate> The color tone of polybutylene terephthalate was evaluated using a color difference meter "Z-300A" manufactured by Nippon Denshoku Co., Ltd., in the L, a, and b color systems.

[0064] <Production Example 1: Production of BDO by depolymerization of polybutylene terephthalate> The 1,4-butanediol obtained by chemical recycling was manufactured in accordance with Example 3 of Japanese Patent Application Publication No. 2004-323378. 1030 parts by mass of polyethylene terephthalate, 3200 parts by mass of methanol, and 13 parts by mass of sodium carbonate were supplied to an autoclave equipped with a stirring blade. The autoclave was immersed in an oil bath at 200°C and the reaction was carried out with stirring at a pressure of 1.3 MPa for 8 hours. The autoclave was removed from the oil bath and cooled to below 10°C in ice water to obtain a slurry. The obtained slurry was separated into solid and liquid components using filter paper to obtain a filtrate. The obtained filtrate was placed in a distillation apparatus equipped with a thermometer, vacuum control device, stirring blade, condenser, and fractionation receiver. Methanol and tetrahydrofuran were recovered as the initial fraction, and then the main fraction was obtained by vacuum distillation. A portion of the obtained main fraction was extracted and analyzed by gas chromatography, revealing a 1,4-butanediol content of 99% by mass or more. This main fraction was used as chemically recycled 1,4-butanediol.

[0065] [Evaluation of blocking resistance, reaction efficiency, etc.] [Example 1] <Production of Dimethyl Terephthalate Composition> 2000 parts by mass of dimethyl terephthalate and 0.1 parts by mass of palmitate were charged into a 5 L separable flask reactor, and the system was purged with nitrogen. The system was then heated to 160°C and maintained at 160°C, and stirred in a molten state for 30 minutes. After that, the molten contents were withdrawn and cooled to obtain dimethyl terephthalate composition 1. The content of compound (1) (palmitate) in this dimethyl terephthalate composition 1 relative to dimethyl terephthalate was 0.005% by mass. The obtained dimethyl terephthalate composition was evaluated for blocking resistance, and the evaluation was S.

[0066] <Transesterification reaction> 132 parts by mass of dimethyl terephthalate composition 1 and 74 parts by mass of petrochemical-derived 1,4-butanediol were supplied to a glass reaction vessel equipped with a stirrer and a distillation tube. The glass reaction vessel was reduced to approximately 100 Pa, and then the pressure was restored to atmospheric pressure with nitrogen, a process that was repeated three times to replace the inside of the reaction vessel with nitrogen. After that, the reaction vessel was immersed in an oil bath at 150°C. After confirming that the contents had melted, the rotation speed was set to 150 revolutions per minute. Next, a butanediol mixture containing 94% by mass of petrochemical-derived 1,4-butanediol and 6% by mass of tetrabutyl titanate was supplied to the resulting polybutylene terephthalate in a concentration of 33 ppm by mass of titanium atoms. Subsequently, the oil bath temperature was increased from 150°C to 210°C over 105 minutes to obtain the transesterification reaction solution. A fraction of 40 parts by mass (91% of the theoretical amount of alcohol produced as a byproduct) was obtained in the receiver at the end of the distillation tube. The transesterification reaction time (transesterification time) from the addition of the BDO solution of tetrabutyl titanate until 40 parts by mass of the fraction were obtained was 131 minutes.

[0067] <Polycondensation reaction> To the obtained transesterification reaction solution, a butanediol mixture containing 70% by mass of petrochemical-derived 1,4-butanediol, 10% by mass of magnesium acetate tetrahydrate, and 20% by mass of water was supplied so that the magnesium atoms amounted to 48 ppm by mass relative to the resulting polybutylene terephthalate. Furthermore, a butanediol mixture containing 94% by mass of petrochemical-derived 1,4-butanediol and 6% by mass of AO-60 was supplied so that the AO-60 amounted to 530 ppm by mass relative to the resulting polybutylene terephthalate. Finally, a butanediol mixture containing 94% by mass of petrochemical-derived 1,4-butanediol and 6% by mass of tetrabutyl titanate was supplied so that the titanium atoms amounted to 61 ppm by mass relative to the resulting polybutylene terephthalate. The oil bath was heated from 210°C to 240°C over 45 minutes, while the internal pressure of the glass reaction vessel was reduced from 101 kPa to 133 Pa over 85 minutes to carry out the polycondensation reaction. Subsequently, the internal pressure was reduced to a full vacuum, and the polymerization reaction was terminated when the agitator in the reaction vessel reached a predetermined stirring power. The polycondensation reaction time (polycondensation time) from the start of pressurization to the stopping of the agitator was 170 minutes.

[0068] Next, the reaction vessel was repressurized to 101 kPa with nitrogen, then increased to a predetermined pressure, and polybutylene terephthalate was extracted in strand form from the bottom of the reaction vessel to obtain strand-shaped polybutylene terephthalate. Subsequently, the strands were pelletized using a rotary cutter to obtain pellet-shaped polybutylene terephthalate. The intrinsic viscosity of the obtained pelletized polybutylene terephthalate was 0.968 dL / g. Regarding color, the L value was 86.4, the a value was -0.6, and the b value was 1.8. The MFR of the obtained polybutylene terephthalate was measured to be 36.8 g / 10 min.

[0069] [Examples 2-7, Comparative Examples 1,2] The procedure was carried out in the same manner as in Example 1, except that the dimethyl terephthalate composition shown in Table 1 was prepared and used.

[0070] Table 1 summarizes the results of the evaluation of blocking resistance, transesterification time, and polycondensation time for Examples 1 to 7 and Comparative Examples 1 and 2, as well as the intrinsic viscosity, color (L, a, b values), and MFR measurements of the obtained polybutylene terephthalate.

[0071] [Table 1]

[0072] [Comparison of strand discharge rates] [Example 8] Polybutylene terephthalate was produced by conventional methods using a polyester manufacturing facility equipped with a transesterification reactor and a polycondensation reactor, with 145 kg of a dimethyl terephthalate composition containing 0.005% by mass of stearic acid amide relative to dimethyl terephthalate, and 76 kg of petrochemical-derived 1,4-butanediol as raw materials. After the polycondensation reaction was complete, the polycondensation reaction tank was pressurized to 0.32 MPaG, the molten resin was discharged from the strand die, and after cooling, it was cut to obtain polybutylene terephthalate pellets. The discharge rate from the strand die at this time was 2.26 kg / min, and the intrinsic viscosity of the resulting pellet was 1.201 dL / g.

[0073] [Comparative Example 3] Polybutylene terephthalate was produced in the same manner as in Example 8, except that dimethyl terephthalate was used instead of the dimethyl terephthalate composition. The discharge rate from the strand die was 2.03 kg / min, and the intrinsic viscosity of the resulting polybutylene terephthalate pellets was 1.196 dL / g.

[0074] [Evaluation of blocking resistance, reaction efficiency, etc.] [Example 9] The procedure was carried out in the same manner as in Example 3, except that 1,4-butanediol derived from biomass resources was used instead of 1,4-butanediol derived from petrochemicals.

[0075] [Example 10] In Example 3, the procedure was carried out in the same manner as in Example 3, except that chemically recycled 1,4-butanediol produced in Production Example 1 was used instead of petrochemical-derived 1,4-butanediol.

[0076] In Examples 9 and 10, the results of the evaluation of blocking resistance, transesterification time, and polycondensation time, as well as the intrinsic viscosity, color L, a, and b values, and MFR measurements of the obtained polybutylene terephthalate, are summarized in Table 2.

[0077] [Table 2]

[0078] From the above results, it can be seen that a dimethyl terephthalate composition containing 0.0001% by mass or more and 1% by mass or less of the amide compound represented by formula (1) relative to dimethyl terephthalate can suppress blocking of powder raw materials, exhibit excellent resin fluidity, and produce polyester with excellent discharge speed from the die without impairing the reactivity of the polycondensation process or affecting the quality of the resulting polyester. Furthermore, this effect is similarly achieved when using biomass resource-derived 1,4-butanediol or chemically recycled 1,4-butanediol, not just petrochemical-derived 1,4-butanediol. In contrast, Comparative Example 1, which did not contain an amide compound and used only dimethyl terephthalate, exhibited problems such as blocking in the powder raw material and poor resin fluidity. Furthermore, as is clear from Comparative Example 3, the discharge speed from the die was also insufficient. In Comparative Example 2, where the dimethyl terephthalate composition contained too much amide compound, the reactivity in the polycondensation reaction was poor, the intrinsic viscosity of the resulting polyester decreased, and furthermore, the b-value deteriorated.

Claims

1. Dimethyl terephthalate contains 0.0001% by mass or more and 1% by mass or less of an amide compound represented by the following formula (1), A dimethyl terephthalate composition in which the total content of dimethyl terephthalate and the amide compound represented by the following formula (1) is 98% by mass or more. 【Chemistry 1】 (In the above formula (1), R 1 R represents a straight-chain saturated or unsaturated hydrocarbon group having 11 to 30 carbon atoms. ２ represents a hydrogen atom or an n-valent hydrocarbon group, where n is 1 or 2, and R ２ (When n is a hydrogen atom, n is 1.)

2. The aforementioned R 1 The dimethyl terephthalate composition according to claim 1, wherein is a linear saturated or unsaturated hydrocarbon group having 15 to 21 carbon atoms.

3. A method for producing a dimethyl terephthalate composition, comprising the step of obtaining a dimethyl terephthalate composition by chemical recycling, The dimethyl terephthalate composition contains, with respect to dimethyl terephthalate, 0.0001% by mass or more and 1% by mass or less of an amide compound represented by the following formula (1), A method for producing a dimethyl terephthalate composition, wherein the total content of dimethyl terephthalate and the amide compound represented by the following formula (1) is 98% by mass or more. 【Chemistry 2】 (In formula (1) above, R1 represents a straight-chain saturated or unsaturated hydrocarbon group having 11 to 30 carbon atoms, and R2 represents a hydrogen atom or an n-valent hydrocarbon group, where n is 1 or 2, and when R2 is a hydrogen atom, n is 1.)

4. A method for producing a polyester, comprising the step of reacting the dimethyl terephthalate composition according to claim 1 or 2 with a diol component.

5. The method for producing polyester according to claim 4, wherein 50 mol% or more of the diol component is 1,4-butanediol.

6. The method for producing polyester according to claim 4, wherein the diol component is derived from biomass.

7. The method for producing polyester according to claim 4, wherein the diol component is produced by the depolymerization of polyester.

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