JP2017160359A - Polytetramethylene glycol copolymerized polybuthylene terephthalate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a PTMG copolymer suitable for food packages, medical package bags or the like as it has good flexibility, low temperature property and impact resistance, less in elution of low molecular weight component to solvents, water or the like and excellent in hygiene property or aroma retention property.SOLUTION: There is provided a polytetramethylene glycol copolymerized polybutylene terephthalate containing a dicarboxylic acid component mainly containing terephthalic acid and a diol component containing 1,4-butanediol and polytetramethylene glycol and satisfying following (1) to (3). (1) number average molecular weight of the polytetramethylene glycol in the polytetramethylene glycol copolymerized polybutylene terephthalate is 650 to 2000. (2) content of the polytetramethylene glycol to the polytetramethylene glycol copolymerized polybutylene terephthalate is 8 to 35 mass%. (3) cyclic polybutylene terephthalate oligomer amount contained in the polytetramethylene glycol copolymerized polybutylene terephthalate is 2500 mass.ppm or less, where the cyclic polybuthylene terephthalate oligomer amount is total amount of cyclic dimer and cyclic trimer.SELECTED DRAWING: None

Description

  The present invention relates to polybutylene terephthalate obtained by copolymerizing polytetramethylene ether glycol (hereinafter, also referred to as PTMG), which is a soft segment, using crystalline PBT (hereinafter, sometimes referred to as PBT) as a hard segment. It relates to a copolymer.

  Polyester resins occupy an important industrial position due to their excellent mechanical and chemical properties. For example, aromatic polyester resins such as polyethylene terephthalate and polybutylene terephthalate (PBT) are resins with excellent heat resistance and chemical resistance. They are easy to process and economical, so that they can be used in fibers, films, sheets, bottles, electrical and electronic equipment. It is widely used in the fields of extrusion molding, injection molding, etc. for parts, automobile parts, precision equipment parts, etc. However, in recent years, there has been a demand for a polyester having new functions such as flexibility, low-temperature characteristics, and impact resistance while maintaining the basic characteristics of the polyester, and further, it is hoped that such a polyester can be efficiently produced. It is rare.

In PBT, many copolymerizations have been studied so far in order to improve the physical properties, but the cases leading to practical use have been extremely limited. This is because the copolymer component is likely to be randomly incorporated into the PBT chain, causing a decrease in the melting point of the PBT and a decrease in the crystallization rate, and acting in a direction to counteract the advantages of the PBT such as heat resistance and moldability.
When the copolymer component is incorporated into the PBT chain in a long-chain block, the melting point drop corresponding to the introduced weight is small, so that physical property modification can be performed without reducing the heat resistance of the PBT. As a typical copolymerization component example, it is known to use polytetramethylene ether glycol (PTMG) (Patent Document 1; Examples).

  By making PBT, which is crystalline, a hard segment and copolymerizing PTMG, which is a soft segment, flexibility can be imparted to the PBT, and it is currently widely used in the film field and the like. Patent Document 2 describes an example in which a PTMG copolymer having a PTMG content of 10% by weight is used as one layer of a laminated film, and also describes that hygiene is good (Patent Document 2; Paragraph 0037).

  However, Patent Document 2 relates to a thermoplastic resin laminated film manufactured by an inflation method with the content of the fine granular lubricant in the outermost layer and the ratio of the thickness of the lubricant and the layer being in a specific range. Because it is a thin film, there is little elution or falling off of the lubricant when the mixed solution of ethanol and water is kept for a long time under specific conditions in the packaging bag made of the film, that is, it is excellent in hygiene. Therefore, it does not pay attention to the elution of low molecular weight components, and it is considered that there are relatively many low molecular weight components such as oligomer components from the technical common sense at the time when the document was filed.

  On the other hand, Patent Document 3 describes an example in which the amount of butylene terephthalate oligomer generated as a result of thermal decomposition reaction of polybutylene terephthalate is reduced (claim 1 and the like). However, this document relates to polybutylene terephthalate and is not a copolymer with PTMG, and it also improves hydrolysis resistance when used as an optical fiber by reducing the amount of butylene terephthalate oligomer. It does not focus on elution of low molecular weight components.

JP-A-49-31795 JP 2007-307708 A Japanese Patent Laid-Open No. 2000-1111768

  The present invention has good flexibility, low-temperature characteristics, and impact resistance for a copolymer imparted flexibility to PBT by copolymerizing PTMG, which is a soft segment, with crystalline PBT as a hard segment. And a copolymer suitable for use in food packaging, medical packaging bags, etc. due to the low elution of low molecular weight components into solvents, water, etc., resulting in excellent hygiene and aroma retention. The issue is to provide.

As a result of examining the above problems, the present inventors have found for the first time that the main component of the eluate in hot water, a solvent, etc. is a cyclic polybutylene terephthalate oligomer, and have reached the present invention. That is, the gist of the present invention is as follows.
(1) A polytetramethylene glycol copolymer polybutylene terephthalate containing a dicarboxylic acid component mainly composed of terephthalic acid and a diol component containing 1,4-butanediol and polytetramethylene glycol,
A polytetramethylene glycol copolymer polybutylene terephthalate satisfying the following (1) to (3):
(1) The number average molecular weight of polytetramethylene glycol in polytetramethylene glycol copolymer polybutylene terephthalate is 650 to 2000. (2) Polytetramethylene glycol content relative to polytetramethylene glycol copolymer polybutylene terephthalate (3) The amount of cyclic polybutylene terephthalate oligomer contained in the polytetramethylene glycol copolymer polybutylene terephthalate is 2500 mass ppm or less (however, the amount of cyclic polybutylene terephthalate oligomer is cyclic 2 (The total amount of the monomer and the cyclic trimer.)
(2) MVR is equal to or less than 50 cm ^3/10 min, polytetramethylene glycol copolymer polybutylene terephthalate according to (1).
(3) The polytetramethylene glycol copolymer polybutylene terephthalate according to the above (1) or (2), which contains a titanium atom and a group 2A metal atom of the periodic table.

  The polytetramethylene copolymer polybutylene terephthalate (hereinafter sometimes abbreviated as PTMG copolymer PBT) according to the present invention has greatly improved flexibility, low temperature characteristics, and impact resistance, and has a low molecular weight component. Since there is little elution to a solvent, water, etc., since it is excellent in hygiene and aroma retention property, it is suitable for food packaging, medical packaging bags, and the like.

  Embodiments of the present invention will be described in detail below. However, the description of the constituent elements described below is an example (representative example) of an embodiment of the present invention, and is not specified by these contents. In the present specification, a numerical range expressed using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value. Moreover, the lower limit value or the upper limit value in this specification means a range including the value of the lower limit value or the upper limit value. Further, in the present specification, “main component” means occupying 70 mol% or more of the component. For example, the “dicarboxylic acid component containing terephthalic acid as a main component” means that 70 mol% or more of the total acid components constituting the polyester are terephthalic acid components. In the present specification, a step of performing an esterification reaction and / or a transesterification reaction is referred to as an esterification reaction step.

The PTMG copolymer PBT of the present invention may be a composition mixed with PBT not containing PTMG.
[1] Raw material of PTMG copolymerized PBT The PTMG copolymerized PBT in the present invention is a dicarboxylic acid mainly composed of terephthalic acid, 1,4-butanediol (hereinafter sometimes referred to as 1,4-BG) and PTMG. It is obtained by subjecting a diol containing a diol, and other components used as necessary, to an esterification reaction and / or a transesterification reaction, followed by a polycondensation reaction, and preferably a solid phase polycondensation reaction. In the esterification reaction and / or transesterification reaction and polycondensation reaction, a reaction catalyst can be used.

<Dicarboxylic acid component>
In the present invention, the dicarboxylic acid component is a dicarboxylic acid or an ester-forming derivative thereof formed by an esterification reaction and / or transesterification reaction of a dicarboxylic acid or an ester-forming derivative thereof described below with a diol or other component. Is a structural unit derived from Examples of the dicarboxylic acids in the present invention include terephthalic acid, dicarboxylic acids described below, and ester-forming derivatives thereof, and terephthalic acid from the viewpoint of mechanical strength, heat resistance, flavor retention, and the like of the resulting polyester. Is preferably the main component. The dicarboxylic acid used in the present invention is a dicarboxylic acid and / or an ester-forming derivative thereof produced by a petrochemical method and / or a production method having a fermentation process derived from biomass resources. As ester-forming derivatives of dicarboxylic acids, ester-forming derivatives such as acid anhydrides and acid chlorides are preferred in addition to lower alcohol esters of dicarboxylic acids. Here, the lower alcohol usually refers to a linear or branched alcohol having 1 to 4 carbon atoms.

(Terephthalic acid component)
In the present invention, the content of the terephthalic acid component in the total dicarboxylic acid component is preferably 80 mol% or more, and more preferably 90 mol% or more. When the proportion of the terephthalic acid component is equal to or higher than the above lower limit value, it is easy to crystallize when forming into an electrical component or the like, and from the point of orientation crystallization of molecular chains by stretching when forming into a film, fiber, etc. Mechanical strength, heat resistance, fragrance retention, etc. as a body tend to be good.

(Dicarboxylic acids other than terephthalic acid)
The dicarboxylic acids used in the present invention may contain dicarboxylic acids other than terephthalic acid.
Specific examples of dicarboxylic acids other than terephthalic acid used in the present invention include oxalic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecadicarboxylic acid, and dodecanedicarboxylic acid. Aliphatic chain dicarboxylic acids and ester-forming derivatives thereof such as hexahydroterephthalic acid and hexahydroisophthalic acid and alicyclic dicarboxylic acids and ester-forming derivatives thereof; phthalic acid, isophthalic acid, dibromoisophthalic acid, sulfoisophthalic acid Acid sodium, phenylenedioxydicarboxylic acid, 4,4′-diphenyldicarboxylic acid, 4,4′-diphenylether dicarboxylic acid, 4,4′-diphenylketone dicarboxylic acid, 4,4′-diphenoxyethanedicarboxylic acid, 4, 4'-diphenylsulfone dicarboxylic acid, 2 Aromatic dicarboxylic acids and ester-forming derivatives such as 6-naphthalene dicarboxylic acid. The ester-forming derivative is preferably an anhydride such as succinic anhydride or adipic anhydride or a lower alcohol ester.

Among these, from the viewpoint of the physical properties of the obtained polyester, other dicarboxylic acids are preferably aromatic dicarboxylic acids such as isophthalic acid and naphthalenedicarboxylic acid, and aliphatic dicarboxylic acids such as succinic acid, adipic acid, sebacic acid, and dodecanedicarboxylic acid. . These dicarboxylic acids can be used alone or as a mixture of two or more thereof.

<Diol component>
In the present invention, the diol component is a structural unit derived from a diol formed by an esterification reaction and / or a transesterification reaction of a dicarboxylic acid or an ester-forming derivative thereof with a diol or other component.
The diols in the present invention include 1,4-BG and PTMG, and in the diol component in the present invention, a structural unit derived from 1,4-BG and a structural unit derived from PTMG constitute the main component as a whole, 70 mol% or more, preferably 80 mol% or more, more preferably 90 mol% or more.

In addition, the ratio of the structural unit derived from PTMG with respect to the total of the structural unit derived from 1,4-BG and the structural unit derived from PTMG is 0.5 mol% or more normally, Preferably, it is 1.0 mol% or more. On the other hand, it is 20 mol% or less, preferably 15 mol% or less. By being in this range, a copolymerized PBT having a good balance between flexibility and impact strength can be obtained.
In the present invention, examples of diols other than 1,4-BG and PTMG include the following.

Ethylene glycol, diethylene glycol, polyethylene glycol, 1,2-propanediol, 1,3-propanediol, polypropylene glycol, dibutylene glycol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, 1,8 A linear aliphatic diol such as octanediol; a cyclic aliphatic diol such as 1,2-cyclohexanediol, 1,4-cyclohexanediol, 1,1-cyclohexanedimethylol, 1,4-cyclohexanedimethylol; Lenglycol, 4,4′-dihydroxybiphenyl, 2,2-bis (4-hydroxyphenyl) propane, bis (4
-Aromatic diols such as hydroxyphenyl) sulfone; diols derived from plant materials such as isosorbide, isomannide, isoidet, and erythritan. Ethylene glycol, 1,3-propanediol, 1,4-butanediol and the like can also be derived from biomass resources. Of these, ethylene glycol, 1,3-propanediol, and 1,4-cyclohexanedimethylol are preferable from the viewpoint of physical properties of the polyester obtained. These diol components can be used alone or as a mixture of two or more.

(PTMG copolymerization amount)
In the PTMG copolymerized PBT of the present invention, the lower limit of the copolymerization amount of the PTMG component is 8% by mass, preferably 10% by mass, more preferably 15% by mass, and the upper limit is 35% by mass, preferably 30% by mass. Preferably it is 25 mass%.
Here, the copolymerization amount (content) of PTMG is the ratio of the PTMG unit as the diol component in the PTMG copolymerization PBT, that is, the amount of the PTMG copolymer obtained by subtracting the water molecule due to ester bond formation from PTMG. The ratio with respect to PBT is expressed by mass%. When the proportion of PTMG copolymerization is within this range, a copolymerized PBT having a good balance between flexibility and impact strength can be obtained. The amount of PTMG copolymerization can be controlled by the amount of PTMG charged when the copolymerized PBT is produced.

(PTMG molecular weight)
In the present invention, the PTMG has a number average molecular weight of 650 to 2000, preferably 800 or more, and preferably 1500 or less. When the molecular weight is within this range, the reactivity during copolymer production is good, the degree of melting point drop due to copolymerization is small, and a copolymerized PBT with good mechanical properties and the like is obtained. The molecular weight of PTMG is controlled by the reaction temperature, reaction time, amount of catalyst, etc. during the production of PTMG.

<Other copolymerizable components>
In addition to the diol component and dicarboxylic acid component, the PTMG copolymerized PBT of the present invention may further contain a structural unit (component) derived from another copolymerizable compound. Examples of other copolymerizable compounds that can be used as a raw material for polyester in the present invention include hydroxycarboxylic acids and alkoxycarboxylic acids such as glycolic acid, p-hydroxybenzoic acid, and p-β-hydroxyethoxybenzoic acid; Monofunctional carboxylic acids such as heneicosanol, octacosanol, benzyl alcohol, stearic acid, behenic acid, benzoic acid, t-butylbenzoic acid, benzoylbenzoic acid; tricarballylic acid, trimellitic acid, trimesic acid, pyromellitic acid, naphthalenetetracarboxylic acid Trifunctional or higher polyfunctional carboxylic acids such as acid and gallic acid; trifunctional or higher functional alcohols such as trimethylolethane, trimethylolpropane, glycerol, pentaerythritol, sugar ester, and the like. These other copolymerizable components can be used alone or in admixture of two or more.

<Catalyst and additive>
(Esterification reaction or transesterification catalyst)
In the present invention, examples of the esterification reaction or transesterification reaction catalyst used for producing PTMG copolymerized PBT include antimony compounds such as antimony trioxide; germanium compounds such as germanium dioxide and germanium tetroxide; tetramethyl Titanium compounds such as titanium alcoholates such as titanate, tetraisopropyl titanate and tetrabutyl titanate, titanium phenolates such as tetraphenyl titanate; dibutyltin oxide, methylphenyltin oxide, tetraethyltin, hexaethyldistinoxide, cyclohexahexyldistinoxide , Didodecyltin oxide, triethyltin hydroxide, triphenyltin hydroxide, triisobutyltin acetate, dibutyltin diacetate Tin compounds such as magnesium acetate; magnesium compounds such as magnesium acetate, magnesium hydroxide, magnesium carbonate, magnesium oxide, magnesium alkoxide, magnesium hydrogen phosphate, calcium acetate, calcium hydroxide, calcium carbonate, calcium oxide, calcium alkoxide In addition to compounds of Group 2 metal of the periodic table such as calcium compounds such as side and calcium hydrogen phosphate, manganese compounds, zinc compounds and the like can be mentioned. In the present invention, the Group 2 metal of the periodic table is a Group 2 element of the long-period periodic table of Nomenclature of Inorganic Chemistry IUPAC Recommendations 2005. Among these, titanium atoms and Group 2 metal compounds of the periodic table are preferable, titanium compounds and tin compounds are particularly preferable, and tetrabutyl titanate is particularly preferable. These catalysts can be used alone or in admixture of two or more.

In the present invention, the catalyst is preferably added so that the metal concentration derived from the reaction catalyst contained in the PTMG copolymerized PBT is within the following range.
In the case of an esterification reaction, the lower limit of the metal concentration is usually 1 ppm by mass or more, preferably 5 ppm by mass or more, more preferably 10 ppm by mass or more, particularly preferably 20 ppm by mass or more, and most preferably 30 ppm by mass or more. It is. On the other hand, the upper limit of the metal concentration is usually 300 ppm by mass or less, preferably 200 ppm by mass or less, more preferably 150 ppm by mass or less, still more preferably 100 ppm by mass or less, particularly preferably 90 ppm by mass or less, most preferably. It is 60 mass ppm or less. When the metal concentration is less than or equal to the above upper limit value, it is difficult to cause foreign matters, and there is a tendency that deterioration reaction and gas generation at the time of thermal residence of the obtained PTMG copolymerized PBT do not easily occur. , Side reactions tend not to occur easily.

In the case of transesterification, the lower limit of the metal concentration is usually 1 ppm by mass or more, preferably 5 ppm by mass or more, more preferably 10 ppm by mass or more, particularly preferably 20 ppm by mass or more, and most preferably 25 ppm by mass or more. It is. On the other hand, the upper limit of the metal concentration is usually 3
It is 00 mass ppm or less, preferably 250 mass ppm or less, more preferably 225 mass ppm or less, still more preferably 200 mass ppm or less, particularly preferably 175 mass ppm or less, and most preferably 150 mass ppm or less.

(Polycondensation reaction catalyst)
In the present invention, as a polycondensation reaction catalyst used for producing PTMG copolymerized PBT, a catalyst for esterification reaction or transesterification reaction may be used as it is as a polycondensation reaction catalyst, or the catalyst may be further added. Also good. The polycondensation reaction catalyst is not particularly limited, but is preferably added so that the metal concentration derived from the polycondensation reaction catalyst contained in the obtained PTMG copolymerized PBT falls within the following range.

  In the case of polycondensation following the esterification reaction, the lower limit of the metal concentration is usually 0.5 mass ppm or more, preferably 1 mass ppm or more, more preferably 3 for the same reason as the catalyst for the esterification reaction. It is at least ppm by mass, particularly preferably at least 5 ppm by mass, and most preferably at least 10 ppm by mass. The upper limit of the metal concentration is usually 300 ppm by mass or less, preferably 200 ppm by mass or less, more preferably 100 ppm by mass or less, particularly preferably 50 ppm by mass or less, and most preferably 30 ppm by mass or less.

  In the case of polycondensation after the transesterification reaction, the lower limit of the metal concentration is usually 5 ppm by mass or more, preferably 10 ppm by mass or more, more preferably 15 ppm by mass for the same reason as the catalyst for the transesterification reaction. As described above, it is particularly preferably 20 ppm by mass or more, and most preferably 30 ppm by mass or more. The upper limit of the metal concentration is usually 300 ppm by mass or less, preferably 200 ppm by mass or less, more preferably 150 ppm by mass or less, particularly preferably 100 ppm by mass or less, and most preferably 50 ppm by mass or less.

Moreover, when using a titanium compound as an esterification reaction catalyst, from the viewpoint of foreign matter suppression, the metal concentration of titanium contained in the finally obtained PTMG copolymerized PBT is preferably 250 ppm by mass or less, More preferably, it is 100 mass ppm or less, Most preferably, it is 60 mass ppm or less, Most preferably, it is 50 mass ppm or less.
The metal concentration (mass) in the PTMG copolymerized PBT should be measured using the atomic emission, Induced Coupled Plasma (ICP) method, etc. after recovering the metal contained in the PTMG copolymerized PBT by a method such as wet ashing. Can do.

(Reaction aid)
In the esterification reaction, transesterification reaction and polycondensation reaction described later, in addition to the above catalyst, phosphorus compounds such as orthophosphoric acid, phosphorous acid, hypophosphorous acid, polyphosphoric acid and esters and metal salts thereof; sodium acetate and benzoic acid Reaction aids such as sodium compounds such as sodium, compounds of group 1A metal elements of the periodic table such as potassium compounds such as lithium acetate and potassium acetate; compounds of group 2A metal elements of the periodic table such as magnesium acetate and calcium acetate Can be added as

(Other additives)
In the esterification reaction, transesterification reaction, and polycondensation reaction described later, 2,6-di-t-butyl-4-octylphenol, pentaerythrityl-tetrakis [3- (3 ′, 5′-t-butyl- 4′-hydroxyphenyl) propionate]; thioether compounds such as dilauryl-3,3′-thiodipropionate, pentaerythrityl-tetrakis (3-laurylthiodipropionate); triphenyl phosphite, tris Antioxidants such as phosphorus compounds such as (nonylphenyl) phosphite and tris (2,4-di-t-butylphenyl) phosphite; representative of paraffin wax, microcrystalline wax, polyethylene wax, montanic acid and montanic acid ester Long chain fatty acids and esters thereof; A release agent such as Ile can also be used.

[2] Method for Producing PTMG Copolymerized PBT The PTMG copolymerized PBT of the present invention is a diol containing PTMG containing dicarboxylic acids mainly composed of terephthalic acid or an ester-forming derivative thereof, and 1,4-BG as a major component. Through an esterification step for performing esterification reaction and / or transesterification reaction with a polymer, a polycondensation reaction for polycondensation reaction of oligomers obtained by the esterification step, and preferably a polycondensation step for performing solid-phase polycondensation The method is to obtain polyester.

  As for the usage-amount of dicarboxylic acid and diol, it is preferable that the latter is 1.1-3.0 normally with respect to 1 mol of the former, and also 1.1-2.0 are more preferable. If this value is too small, the esterification reaction tends to be slow, and if it is too large, the production of tetrahydrofuran by 1,4-BG decomposition tends to increase. In addition, the amount used when other components are copolymerized is usually 0.5 mol or less, preferably 0.3 mol or less, relative to 1 mol of the dicarboxylic acids.

In the present invention, it is important that the PTMG copolymer PBT obtained in the above reaction is produced under the conditions that satisfy the following physical properties (1) to (3).
(1) Polytetramethylene glycol copolymer The number average molecular weight of polytetramethylene glycol in polybutylene terephthalate is 650 to 2000. (2) Polytetramethylene glycol content relative to polybutylene terephthalate (3) The amount of cyclic polybutylene terephthalate oligomer contained in the polytetramethylene glycol copolymer polybutylene terephthalate is 2500 ppm by mass or less (however, the amount of cyclic polybutylene terephthalate oligomer is the amount of cyclic 2 The total amount of the body and the cyclic trimer.)

  Specifically, for the control of (1), the molecular weight of the polytetramethylene glycol in the polytetramethylene glycol copolymerized polybutylene terephthalate is usually maintained as it is, The polytetramethylene glycol used as a raw material is selected by selecting one that satisfies the scope of the present invention. The control of (2) is performed by adjusting the amount of PTMG added in the production of polytetramethylene glycol copolymer polybutylene terephthalate. For (3), solid phase polycondensation, thin film melt polycondensation, auxiliary agent Examples of the method include addition of (Na diphosphite). Among these methods, solid phase polycondensation is performed for a relatively long time.

The PTMG copolymerized PBT of the present invention comprises a known PBT production method except that PTMG is used as a part of the diol component, that is, dicarboxylic acids mainly composed of terephthalic acid or an ester-forming derivative thereof, and 1,4BG. An esterification step in which esterification and / or transesterification with a diol containing PTMG as a main component is performed, and a polycondensation reaction in which an oligomer obtained by the esterification step is polycondensed, It can carry out according to the method of obtaining polyester through the polycondensation process which performs phase polycondensation, Operation other than the above can employ | adopt general manufacturing conditions of polyester. That is, as a method for producing PTMG copolymerized PBT, a so-called direct polymerization method in which terephthalic acid is used as a main raw material and a transesterification method in which a dialkyl ester of terephthalic acid is used as a main raw material There are no particular restrictions.

The reaction conditions for the esterification step are arbitrary as long as the esterification reaction and / or transesterification reaction can proceed, and the reaction temperature is 120 ° C. or higher, preferably 150 ° C. or higher, while 245 ° C. or lower, preferably Is 230 ° C. or lower. The reaction time is 2 to 8 hours, preferably 2 to 6 hours, and more preferably 2 to 4 hours.
By the esterification step, an oligomer is produced in which a diol containing 1,4BG as a main component and a dicarboxylic acid containing terephthalic acid or an ester-forming derivative thereof as a main component are reacted. And in the polycondensation process mentioned later, this oligomer polycondensation reaction is performed.

  The polycondensation reaction is usually performed by a melt polycondensation reaction. The conditions in the melt polycondensation reaction are arbitrary as long as the polycondensation reaction can proceed. The reaction temperature during the polycondensation reaction is preferably 250 ° C. or lower, more preferably 245 ° C. or lower, on the other hand, preferably 230 ° C. or higher, more preferably 235 ° C. or higher. When the reaction temperature is at most the upper limit value, the thermal decomposition reaction during production tends to be suppressed and the color tone tends to be improved. If the reaction temperature is equal to or higher than the lower limit, the polycondensation reaction is likely to proceed efficiently.

  The lower the pressure in the reaction tank during the polycondensation reaction, the easier the reaction proceeds, but usually it is 27 kPa or less, preferably 20 kPa or less, more preferably 13 kPa or less, and at least one polycondensation reaction tank preferably has a state of 2 kPa or less. It is preferable to take. The time required for the polycondensation reaction is adjusted so as to make the range constant by measuring the melt viscosity and intrinsic viscosity of the obtained PBT, but is usually 2 to 12 hours, preferably 2 to 10 hours. When the polycondensation reaction is carried out continuously, the average residence time in the polycondensation reaction tank is regarded as the time required for the polycondensation reaction.

  In the present invention, PTMG is added to the reaction system during the esterification reaction and / or after the start of the transesterification reaction until the end of the polycondensation reaction. By adding during this period, the block property as a copolymerization component is easily maintained, and a PTMG copolymerized PBT with a low melting point reduction is obtained. The addition time is preferably from the time of esterification reaction and / or from the end of the transesterification to before the start of the polycondensation reaction in terms of the addition operation and securing the blocking property.

  After completion of the polycondensation reaction, it is extracted in a strand form from the reaction vessel and cut into water or pellets by cutting after water cooling. If necessary, the pellets can be solid-phase polycondensed to further increase the degree of polymerization, or reduce impurities such as cyclic polybutylene terephthalate oligomers (hereinafter sometimes referred to as cyclic oligomers) and THF contained in the pellets. Therefore, solid phase polycondensation is preferably employed in the present invention.

The solid-phase degeneracy reaction is performed under reduced pressure in an inert gas atmosphere such as nitrogen, or under an inert gas flow. The reaction temperature is 180 ° C. or higher, preferably 190 ° C. or higher, while 210 ° C. or lower, preferably 200 ° C. or lower. The reaction time is relatively long until the desired MVR, desired cyclic oligomer, tetrahydrofuran, etc. are obtained.
The reaction time is usually 5.5 to 20 hours, preferably 6 to 15 hours.
The solid phase polycondensation can be carried out batchwise or continuously.

[3] Physical properties of PTMG copolymerized PBT (MVR of PTMG copolymerized PBT)
PTMG copolymer MVR at 250 ° C. of PBT of the present invention (melt volume flow rate Unit: ^cm 3/10 min, the test method conforms according ISO 1133) is, 100 cm ^3/10 minutes or less, and more preferably 50 cm ^3/10 Minutes or less, more preferably 30 or less, particularly preferably 25 or less. The lower limit is sure if possible film forming is usually ^{5 cm} 3/10 min. When the MVR is within this range, a copolymerized PBT having good moldability and good physical properties when formed into a molded product can be obtained.

(Terminal carboxyl group amount of PTMG copolymer PBT)
The terminal carboxyl group amount (AV: equivalent / ton) of the PTMG copolymerized PBT of the present invention is preferably 3 to 50 equivalent / ton, more preferably 3 to 35 equivalent / ton, and further preferably 5 to 20. When the amount of terminal carboxyl groups is within this range, heat resistance and hydrolysis resistance are improved.

(Intrinsic viscosity of PTMG copolymer PBT)
The intrinsic viscosity (IV: dl / g) of the PTMG copolymerized PBT of the present invention is 0.90 to 1.50, preferably 1.00 to 1.50, more preferably 1.20 to 1.50.
When the intrinsic viscosity is within this range, a copolymerized PBT having good moldability and good physical properties when formed into a molded product can be obtained.

(Molecular weight of PTMG component in PTMG copolymerized PBT)
In the present invention, the number average molecular weight of PTMG is 650 to 2000, preferably 800 to 1500. When the molecular weight is within this range, the degree of melting point drop due to copolymerization is small, and a copolymerized PBT having good mechanical properties and the like can be obtained. The molecular weight distribution of the PTMG component in the PTMG copolymerized PBT and the method for measuring the molecular weight are described in detail in Examples.

(Amount of cyclic PBT oligomer)
The amount of cyclic PBT oligomer in the PTMG copolymerized PBT in the present invention is 2500 mass ppm or less, preferably 2000 mass ppm or less, more preferably 1600 ppm or less. The lower limit is preferably 500 ppm because the lower the amount, the lower the extractables due to water, solvents, etc.

  The “cyclic PBT oligomer amount” in the present invention is defined as the total amount of a dimer and a trimer. Cyclic PBT oligomers are found to exist from dimers to heptamers, but most are dimers and trimers, and oligomers of tetramers and higher are in a negligible amount. is there. When the cyclic PBT oligomer is in the above range, PTMG copolymer PBT formed into a film or laminated film has less extract to water (hot water), solvent (alcohol, etc.), food packaging, and medical use It can be suitably used for packaging bags and the like.

  As described above, as a method for reducing the cyclic oligomer in the copolymerized PBT, there are methods such as solid phase polycondensation, thin film melt polycondensation, and addition of an auxiliary agent (Na diphosphite). It is desirable to carry out the polycondensation for a relatively long time. The above-mentioned Patent Document 1 (Japanese Patent Laid-Open No. 49-31795) focuses on the moldability of the resin, not on the elution of components when formed into a film, and transesterification and polycondensation. The polymer obtained by the reaction is extruded into strands, and the pellets obtained by cutting are dried and injection molded, and solid phase polymerization is not performed. Therefore, it is reasonable to consider that the amount of cyclic PBT oligomer is large.

(Catalyst-derived metal component)
The PTMG copolymerized PBT of the present invention contains a metal component derived from the above-mentioned catalyst, and preferably contains a titanium atom and a group 2A metal atom of the periodic table. The content is in accordance with the amount described in the above-mentioned catalyst usage.

[4] Composition The PTMG copolymer PBT of the present invention can be blended with various additives such as stabilizers, fillers, flame retardants, PBT and other resins, if necessary, to obtain a polyester composition. . Moreover, it can be set as a molded object using this resin composition.

(Formulation method)
The method of blending the various additives and resins is not particularly limited, but a method of using a uniaxial or biaxial extruder having equipment capable of devolatilization from the vent port as a kneader is preferable. Each component including the additional components can be supplied to the kneader in a lump or can be supplied sequentially. In addition, two or more kinds of components selected from each component, including additional components, can be mixed in advance.

(Molding method)
The PTMG copolymer PBT of the present invention and the composition thereof are molded by molding methods generally used for thermoplastic resins, that is, molding methods such as injection molding, hollow molding, extrusion molding, press molding, stretch molding, inflation molding, and the like. It can be a body.

(Use)
The PTMG copolymerized PBT of the present invention has good flexibility, low temperature characteristics and impact resistance, and has low elution of low molecular weight components into solvents, water, etc., resulting in excellent hygiene and aroma retention. It is suitable as a resin for food packaging, medical packaging bags and the like.

  Hereinafter, the present invention will be described in more detail by way of examples. However, the present invention is not limited to the following examples unless it exceeds the gist. In addition, the measurement method of the physical property and evaluation item which were employ | adopted in the following examples is as follows.

<PTMG number average molecular weight SEC (GPC) measurement>
The SEC (size exclusion chromatography) measurement of PTMG molecular weight was performed using a high-speed GPC apparatus HLC-8120 GPC manufactured by Tosoh Corporation.
The sample was dissolved in a reagent primary THF (containing the antioxidant dibutylhydroxytoluene) as a mobile phase liquid, and filtered through a 0.45 μm PTFE (polytetrafluoroethylene) filter for measurement.
The number average molecular weight (Mn) was calculated from the measured data using a high-speed GPC device Tosoh GPC-8020 model II manufactured by Tosoh Corporation and calculated as a polystyrene equivalent value.

The SEC conditions are shown below.
High-speed GPC device: HLC-8120 GPC (manufactured by Tosoh Corporation)
Analysis software: GPC-8020 modelII (manufactured by Tosoh Corporation)
Detector: RI (built-in device)
Mobile phase: Reagent grade 1 THF (containing antioxidant dibutylhydroxytoluene)
Flow rate: 0.6 ml / min Injection: 0.1 wt% x 20 μL
Column: TSKgel SuperHM-L (6.0mm ID x 15cmL x 2) (manufactured by Tosoh Corporation)
Column temperature: 40 ° C
Calibration sample: Monodisperse polystyrene calibration method: Polystyrene conversion calibration curve approximation formula: cubic formula.

<Number average molecular weight SEC measurement of PTMG component in PTMG copolymerized PBT>
To about 10 g of PTMG copolymerized PBT pulverized into a fine powder, 50 ml of a 20% by mass aqueous sodium hydroxide solution is added and heated to reflux until dissolved in a reflux apparatus with a Dimroth condenser. Thereafter, the mixture is cooled, and excess sodium hydroxide is neutralized with terephthalic acid. The solution is filtered. The filtrate contains PTMG that has formed a copolymer. The filtrate was analyzed and calculated by the method described in <PTMG number average molecular weight SEC (GPC) measurement> to calculate the molecular weight.

<MVR melt volume flow rate unit: ^cm 3/10 minutes>
Before measurement, the sample was vacuum-dried at 120 ° C. for 8 hours. MVR was measured at 245 ° C. under a load of 2.16 kg using a melt indexer model L242-4431 manufactured by Tateyama Kagaku in accordance with the test method described in ISO1133. Specifically, 6 g of the sample is put in a cylinder of a melt indexer set at 245 ° C., a piston is set, a 2.16 kg load is applied to the resin heated to 245 ° C., and the orifice passes through 2.095 mm, It was determined in terms and MVR ^(cm 3/10 min) from the capacitance of time flowing resin in volume flowing out in 10 minutes.

<Cyclic PBT oligomer content in PTMG copolymerized PBT (mass ppm)>
Weigh accurately 0.10 g of sample, add 3 mL of HFIP (hexafluoroisopropanol) / chloroform = 2/3 (vol), dissolve at room temperature, add 20 mL of chloroform, add dropwise 10 mL of methanol with stirring, and remove the polymer component. Precipitated. The stationary separation was performed for 3 hours. Subsequently, 2 mL of the supernatant was filtered with a 0.45 μm PTFE filter. 1 mL of the filtrate was concentrated to dryness with nitrogen blowing at room temperature, redissolved in 1 mL of DMSO (dimethyl sulfoxide), and used as a measurement sample. About 5 mg of dimethyl terephthalate (DMT) was collected and precisely weighed, then DMSO was added to dissolve the sample, and the volume was increased to 10 mL. A solution obtained by diluting the solution with DMSO about 10 times was used as a standard sample.

  The LC conditions were as follows. The apparatus was an Agilent 1100 series, the mobile phase was A: 2% acetic acid water, B: acetonitrile, 0 min (B = 20%) → 22 min (B = 100%) → 35 min (B = 100%) gradient conditions. The flow rate is 1.0 mL / min, the column temperature is 40 ° C., and the UV detection wavelength is 254 nm. The column was quantified using “MCI-GEL ODS-1LU” manufactured by Mitsubishi Chemical Corporation.

<Terminal carboxyl group concentration (AV: equivalent / ton)>
After pulverizing the sample, it was dried at 140 ° C. for 15 minutes in a hot air drier, cooled to room temperature in a desiccator, 0.1 g was accurately weighed and collected in a test tube, and 3 ml of benzyl alcohol was added. The solution was dissolved at 195 ° C. for 3 minutes while blowing dry nitrogen gas, and then 5 ml of chloroform was gradually added and cooled to room temperature. One to two drops of phenol red indicator were added to this solution, and titrated with a 0.1N sodium hydroxide benzyl alcohol solution with stirring while blowing dry nitrogen gas, and the procedure was terminated when the color changed from yellow to red. Moreover, the same operation was implemented as a blank, without melt | dissolving a polyester resin sample, and the terminal carboxyl group amount (acid value) was computed by the following formula | equation.

Terminal carboxyl content (equivalent / ton) = (ab) × 0.1 × f / w
(Where a is the amount of benzyl alcohol solution of 0.1N sodium hydroxide required for titration (μl), b is the amount of benzyl alcohol solution of 0.1N sodium hydroxide required for titration without sample. The amount (μl), w is the amount of the polyester resin sample (g), and f is the titer of 0.1N sodium hydroxide in benzyl alcohol.)

<Intrinsic viscosity (IV: dL / g)>
It calculated | required in the following way using the Ubbelohde type viscometer. That is, a mixed solution of phenol / tetrachloroethane (mass ratio 1/1) was used as a solvent, and at 30 ° C., the sample solution having a concentration of 1.0 g / dL and the falling seconds of the solvent alone were measured. Asked.

IV = ((1 + 4K _H η _sp ) ^0.5 −1) / (2K _H C)
(Where ηSP = η / η0−1, η is the sample solution drop seconds, η0 is the solvent drop seconds, C is the sample solution concentration (g / dL), and KH is the Huggins constant. 0.33 was adopted.)

<Bending elastic modulus MPa>
The pellet was dried with an air dryer at 120 ° C. for 8 hours, and a molded piece used for measuring the following mechanical properties was injection-molded under the following conditions using Nissei Plastic Industries FE80S12ASE.
Molding temperature: 250 ° C (cylinder setting)
Mold temperature: 80 ℃ (surface temperature)
Injection speed: 200mm ± 100mm / s (injection time about 2 seconds)
Holding time: 20 seconds Cooling time: 10 seconds

The obtained test piece was subjected to a bending test by the method of JIS K7171 using a bending tester manufactured by Toyo Seiki Seisakusho Co., Ltd .: Product name: Bendgraph II Model: B, and the flexural modulus was measured.
Bendgraph II, load cell 2kN
Test speed = 2mm / min
Test piece: 80 × 10 × 4mm
Distance between fulcrums: 64mm
Indenter = 5R, support base = 5R
Elastic modulus calculation: P1 = 0.05%, P2 = 0.25%

<Elution amount mg>
20 g of pellets were filled with 100 mL of water and heat-treated at a temperature of 120 ° C. for 1 hour. Thereafter, the eluate was evaporated to dryness, and the evaporation residue was precisely weighed (unit: mg). The smaller the amount of elution, the better the hygiene. If it is less than 0 mg, it can be determined that the hygiene is excellent.
[Example 1]

  In a transesterification reaction tank equipped with a stirrer, a nitrogen inlet, a heating device, a thermometer, and a distillation tube, 80.0 parts by mass of dimethyl terephthalate, 44.2 parts by mass of 1,4-BG, and a number average molecular weight of 1000 PTMG of 10.2 parts by mass, and tetrabutyl titanate as a catalyst were added as a 1,4-BG solution so as to be 33 mass ppm with respect to the polymer to be produced (PTMG copolymerized PBT) in terms of titanium metal. Next, the liquid temperature in the tank was held at 150 ° C. for 60 minutes, and then the temperature was raised to 210 ° C. over 90 minutes and held at 210 ° C. for 30 minutes. During this time, the ester exchange reaction was carried out for 180 minutes in total while distilling the produced methanol.

15 minutes before the end of the transesterification reaction, magnesium acetate tetrahydrate is dissolved in 1,4-BG so as to be 48 mass ppm with respect to the polymer produced as magnesium metal, and further produced polymer Hindered phenolic antioxidant [Ciba Geigy Co., Ltd., Irganox 1010: tetrakis [methylene-3 (3
5-ditert-butyl-4-hydroxy-phenyl) propionate] methane is added in a 1,4-BG slurry, followed by an amount of 25 ppm by weight as titanium metal to the polymer that produces tetrabutyl titanate. After adding as a solution of 1,4-BG, it is transferred to a polycondensation reaction tank equipped with a stirrer, nitrogen inlet, heating device, thermometer, distilling tube, and pressure reducing exhaust port, and reduced pressure is applied. A condensation reaction was performed.

The polycondensation reaction was gradually reduced from normal pressure to 0.4 KPa over 85 minutes, and continued at 0.4 KPa or less. The reaction temperature was maintained at 210 ° C. for 15 minutes from the start of depressurization, and then increased to 240 ° C. over 45 minutes and maintained at this temperature. Predetermined stirring torque (MVR at 250 ° C. is equivalent to 57cm ^3/10 minutes) the reaction was completed when it reaches the. The time required for the polycondensation reaction was 180 minutes (the polycondensation reaction time was defined as the time from the start of pressure reduction to the return pressure with nitrogen). Next, the inside of the tank was decompressed with nitrogen from the depressurized state, and then pressurized for extracting the polymer.
The heat medium temperature of the die at the time of extraction was set to 235 ° C., the polymer was extruded from the die in the form of a strand, and then the strand was cooled in a cooling water tank, and then cut with a strand cutter and pelletized. The intrinsic viscosity of the obtained polybutylene terephthalate copolymer composition was 0.85, and the number average molecular weight of polytetramethylene glycol in the polytetramethylene glycol copolymer polybutylene terephthalate was 1000. Next, the polybutylene terephthalate copolymer composition pellets, 195 ° C., by performing solid-phase polycondensation for 8 hours under reduced pressure (0.133 kPa or less), intrinsic viscosity 1.22, MVR18cm ^3/10 min, cyclic A polybutylene terephthalate copolymer composition having a PBT oligomer of 1700 mass ppm, an elution amount of 0.8 mg, and a flexural modulus of 760 MPa was obtained.
The results are shown in Table-1.
[Example 2]

The same procedure as in Example 1 was performed except that the solid phase polycondensation time was changed to 14 hours in Example 1. The results are shown in Table-1.
[Example 3]

Example 1 was performed in the same manner as in Example 1 except that 71.8 parts by mass of dimethyl terephthalate, 39.3 parts by mass of 1,4-BG, and 20.2 parts by mass of PTMG having a number average molecular weight of 1000 were changed to 20.2 parts by mass. . The results are shown in Table-1.
[Example 4]

Example 1 is the same as Example 1 except that 63.6 parts by mass of dimethyl terephthalate, 34.6 parts by mass of 1,4-BG, and 30.2 parts by mass of PTMG having a number average molecular weight of 1000 are changed to 30.2 parts by mass.
As well as. The results are shown in Table-1.
[Comparative Example 1]

In Example 1, it carried out like Example 1 except having changed the solid-phase polycondensation time into 5 hours. The results are shown in Table-1.
[Comparative Example 2]

The same procedure as in Example 1 was performed except that the solid phase polycondensation was changed to that in Example 1.
The results are shown in Table-1.
[Comparative Example 3]

Example 1 was carried out in the same manner as in Example 1 except that 88.2 parts by mass of dimethyl terephthalate, 49.1 parts by mass of 1,4-BG, PTMG were omitted, and solid phase polycondensation was omitted. The results are shown in Table-1.

As is clear from the above Examples and Comparative Examples, the PTMG copolymerized PBTs of Comparative Examples 1 and 2 containing PTMG as a copolymerization component have good flexibility, but have a large amount of cyclic polybutylene terephthalate oligomer. As a result, there are many effluents by heat treatment in water. The PBT of Comparative Example 2 that does not contain PTMG as a copolymer component has a large flexural modulus and inferior flexibility and a large amount of cyclic polybutylene terephthalate oligomer, resulting in a large amount of eluate due to heat treatment in water. Therefore, the PTMG copolymerized PBT and PBT of Comparative Examples 1 to 3 are inferior in hygiene and aroma retention, and are unsuitable for food packaging, medical packaging bags, etc.
In contrast, the PTMG copolymerized PBT of the examples has good flexibility and a small amount of cyclic polybutylene terephthalate oligomer, and as a result, there are few eluates due to heat treatment in water. Since it has excellent fragrance retention, it is suitable for food packaging, medical packaging bags, and the like.

Claims (3)

A polytetramethylene glycol copolymer polybutylene terephthalate comprising a dicarboxylic acid component based on terephthalic acid and a diol component comprising 1,4-butanediol and polytetramethylene glycol,
A polytetramethylene glycol copolymer polybutylene terephthalate satisfying the following (1) to (3):
(1) Polytetramethylene glycol copolymer The number average molecular weight of polytetramethylene glycol in polybutylene terephthalate is 650 to 2000. (2) Polytetramethylene glycol content relative to polybutylene terephthalate (3) The amount of cyclic polybutylene terephthalate oligomer contained in the polytetramethylene glycol copolymer polybutylene terephthalate is 2500 mass ppm or less (however, the amount of cyclic polybutylene terephthalate oligomer is cyclic 2 (The total amount of the monomer and the cyclic trimer.) MVR is equal to or less than 50 cm ^3/10 min, polytetramethylene glycol copolymer polybutylene terephthalate of claim 1.   The polytetramethylene glycol copolymer polybutylene terephthalate according to claim 1 or 2, comprising a titanium atom and an atom of a Group 2A metal of the periodic table.