JP6834630B2 - polyester - Google Patents

Description

The present invention relates to polyester. More specifically, the present invention relates to a copolymerized polyester suitable for food containers and medical packaging materials.

Conventionally, polyester resin, for example, polyethylene terephthalate, has excellent mechanical strength, chemical stability, gas barrier property, fragrance retention, hygiene, etc., and is relatively inexpensive and lightweight, so that it is used for packaging various foods and drinks. Widely used as a container and the like. However, in general, polyester has been required to be improved because of its inferior flexibility. Patent Document 1 describes a polyester film in which a dimer acid is copolymerized as a dicarboxylic acid component and has a small amount of cyclic trimer.

Japanese Unexamined Patent Publication No. 9-132653

However, these conventionally known polyesters are poor in blow moldability and extruded film moldability, and it is difficult to mold them into large food containers, medical packaging materials, etc., and impurities such as cyclic trimer are contained. Since the reduction is insufficient, there is a problem that the molded appearance of the molded product is inferior, and the hygiene and fragrance retention are also poor.

The present invention has been made to solve the above problems. That is, it is an object of the present invention to provide a polyester having good blow moldability and extruded film moldability, a good molded appearance, and extremely excellent hygiene.

As a result of diligent research to solve the above problems, the present inventor is a polyester composed of a dicarboxylic acid component and a diol component, and has a specific amount of terephthalic acid, a specific amount of isophthalic acid, and a specific amount of dimer as the dicarboxylic acid component. It is a polyester containing an acid and ethylene glycol as a diol component, and because the cyclic trimer content is a specific amount, the blow moldability and the extrusion film moldability are good, and the molded appearance is good. We have found that it is possible to use polyester, which is extremely excellent in hygiene, and have reached the present invention.

That is, the present invention is as follows.
[1] A polyester composed of a dicarboxylic acid component and a diol component, wherein the dicarboxylic acid component is 77 mol% or more and 92 mol% or less of terephthalic acid, 3 mol% or more and 10 mol% or less of isophthalic acid, and 5 mol% of dimer acid. A polyester containing 13 mol% or more, ethylene glycol as a diol component, and a cyclic trimeric content of less than 4000 mass ppm.
[2] The polyester according to [1], which has an intrinsic viscosity IV of 0.8 dL / g or more and 1.5 dL / g or less.
[3] The polyester according to [1] or [2], wherein the amount of n-heptane eluted in 1 hour at a temperature of 110 ° C. of the sheet obtained by molding the polyester is less than 0.05 mg / cc. [4] The polyester according to any one of [1] to [3], wherein the amount of water eluted in 1 hour at a temperature of 110 ° C. of the sheet formed by molding the polyester is less than 0.0035 mg / cc.
[5] The polyester according to any one of [1] to [4], wherein the polyester contains a titanium compound as a titanium element with respect to the polyester in an amount of 3% by mass or more and 30% by mass or less.
[6] The polyester according to any one of [1] to [5], wherein the polyester contains a magnesium compound as a magnesium element in an amount of 3% by mass or more and 30% by mass or less.
[7] The polyester according to any one of [1] to [6], wherein the polyester contains a phosphorus compound as a phosphorus element in an amount of 3% by mass or more and 30% by mass or less.
[8] The polyester according to any one of [1] to [7] used for food containers.
[9] The polyester according to any one of [1] to [7] used for food packaging materials.
[10] The polyester according to any one of [1] to [7] used for medical packaging materials.

The polyester of the present invention has good blow moldability and extrusion film moldability, has a good molded appearance, and is extremely excellent in hygiene, and is applicable to various food containers, food packaging materials, or medical packaging materials. can do.

(polyester)
The best mode for carrying out the present invention will be described in detail below, but the description of the constituent elements described below is a typical example of the embodiment of the present invention, and the present invention is limited to these contents. It's not a thing. In the present specification, "ppm" representing the content means "mass ppm" unless otherwise specified, such as "mol".
The polyester of the present invention is a polyester composed of a dicarboxylic acid component and a diol component, and contains 77 mol% or more and 92 mol% or less of terephthalic acid, 3 mol% or more and 10 mol% or less of isophthalic acid, and dimer acid as dicarboxylic acid components. It is a polyester containing 5 mol% or more and 13 mol% or less and containing ethylene glycol as a diol component.

As the dicarboxylic acid component, terephthalic acid is preferably 79 mol% or more and 91 mol% or less, and more preferably 81 mol% or more and 89 mol% or less. Too little terephthalic acid can result in poor heat resistance. Moreover, if the amount of terephthalic acid is too large, the flexibility may be inferior. As the dicarboxylic acid component, isophthalic acid is preferably 4 mol% or more and 9 mol% or less, and more preferably 5 mol% or more and 8 mol% or less. Too little isophthalic acid can reduce transparency. If too much isophthalic acid is used, heat resistance and mechanical properties may be inferior. As the dicarboxylic acid component, the dimer acid is preferably 5 mol% or more and 12 mol% or less, and more preferably 6 mol% or more and 11 mol% or less. Too little dimer acid can reduce the flexibility of the polyester. Further, if the amount of dimer acid is too large, the thermal stability may decrease.
The dimer acid in the present invention refers to a dimer of an unsaturated aliphatic carboxylic acid having 16 or more carbon atoms or a hydrogenated product thereof. This dimer acid is an unsaturated carboxylic acid having 16 or more carbon atoms (for example, an unsaturated fat containing linoleic acid or oleic acid as a main component) extracted from non-petroleum raw materials such as soybean oil, rapeseed oil, beef fat, and tall oil. A mixture of group carboxylic acids) can be obtained by dimerizing or watering it. When dimer acid is obtained by using such a production method, an excessively reacted trimer and an unreacted unsaturated aliphatic carboxylic acid are contained as impurities. Since the impurities cause bleed-out and gelation in polyester, it is preferable that the impurities are as small as possible.
The dimer acid contains an unsaturated bond, and if used as it is, a branching reaction may proceed during the polymerization or the color tone of the polyester resin may be deteriorated. Therefore, the dimer acid is preferably hydrogenated.
The dicarboxylic acid component of polyester can be quantified by measuring ^{1 1 H-NMR spectrum.}

The polyester of the present invention may contain a dicarboxylic acid other than terephthalic acid, isophthalic acid and dimer acid as a dicarboxylic acid component as long as the effect of the present invention is not impaired. Other dicarboxylic acids include, for example, phthalic acid, flangecarboxylic acid, sodium sulfoisophthalate, phenylenedioxydicarboxylic acid, 4,4'-diphenyldicarboxylic acid, 4,4'-diphenyletherdicarboxylic acid, 4,4'-diphenyl. Aromatic dicarboxylic acids such as ketone dicarboxylic acid, 4,4'-diphenoxyetanedicarboxylic acid, 4,4'-diphenylsulfonedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, hexahydroterephthalic acid, hexahydroisophthalic acid and the like. Alicyclic dicarboxylic acids, aliphatic dicarboxylic acids such as succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecadicarboxylic acid, dodecadicarboxylic acid, and 1 carbon number thereof. Examples thereof include an ester having an alkyl group of about 4 to 4, a halide and the like, and one or more of these may be mixed and contained.

Ethylene glycol is contained as a diol component. Ethylene glycol is preferably 95 mol% or more and 98 mol% or less, more preferably 96 mol% or more and 98 mol% or less, based on the total diol component. There is a possibility that the polyester will have better thermal stability than the above range.

The diol other than ethylene glycol preferably contains diethylene glycol, and the diethylene glycol is preferably 2 mol% or more and 5 mol% or less, more preferably 2 mol% or more and 4 mol% or less, based on the total diol component. Within the above range, the thermal stability of the polyester is improved, and the transparency tends to be improved.
Each diol of polyester can be quantified by hydrolyzing the polyester and then measuring the decomposed product by gas chromatography.
As a method of controlling the amount of diethylene glycol quantified from polyester, first, there is a method of adjusting the amount of diethylene glycol used as a raw material in the production of polyester.
Further, in diethylene glycol, two molecules of ethylene glycol used as a raw material in polyester production are dehydrated and bonded to become diethylene glycol, which may be incorporated as a diol component in polyester. As a control method, when the molar ratio of the diol component containing ethylene glycol used as a raw material to the dicarboxylic acid component used as a raw material is increased, the binarization of ethylene glycol is promoted and the amount of diethylene glycol tends to increase. There is. Further, when the esterification reaction is carried out in the presence of a metal hydroxide such as sodium hydroxide or an alkaline component such as tetraethylammonium hydroxide, the binarization of ethylene glycol may be suppressed and the amount of diethylene glycol may tend to decrease.

The polyester of the present invention may contain diols other than ethylene glycol and diethylene glycol as diol components as long as the effects of the present invention are not impaired. Examples of other diols include trimethylene glycol, tetramethylene glycol, pentamethylene glycol, hexamethylene glycol, octamethylene glycol, decamethylene glycol, neopentyl glycol, 2-ethyl-2-butyl-1,3-propanediol, and the like. Aliphatic diols such as polyethylene glycol, polytetramethylene ether glycol, 1,2-cyclohexanediol, 1,4-cyclohexanediol, 1,1-cyclohexanedimethylol, 1,4-cyclohexanedimethylol, 2,5-norbornan Alicyclic diols such as dimethylol, xylylene glycol, 4,4'-dihydroxybiphenyl, 2,2-bis (4'-hydroxyphenyl) propane, 2,2-bis (4'-β-hydroxyethoxy) Addition of aromatic diols such as phenyl) propane, bis (4-hydroxyphenyl) sulfone and bis (4-β-hydroxyethoxyphenyl) sulfonic acid, and ethylene oxide of 2,2-bis (4'-hydroxyphenyl) propane. Examples thereof include substances, propylene oxide adducts, dimerdiols, etc., and one or a mixture of two or more of them may be contained.

The polyester of the present invention preferably contains a titanium compound. The content of the titanium compound is preferably 3 mass ppm or more and 30 mass ppm or less, more preferably 3 mass ppm or more and 20 mass ppm or less, and 5 mass ppm or more and 10 mass ppm or less with respect to polyester as a titanium atom. It is more preferably ppm or less. When it is within the above range, the color tone of the polyester tends to be good and the thermal stability tends to be improved. The titanium atom content in polyester can be quantified by inductively coupled plasma emission spectroscopy.
The titanium compound is preferably used as a transesterification catalyst in producing the polyester of the present invention. As the titanium compound used as the transesterification catalyst, conventionally known titanium compounds can be appropriately selected and used, and titanium oxides, hydroxides, alkoxides, acetates, carbonates, oxalates, and halogens can be used. Examples include compounds.

The polyester of the present invention preferably contains a magnesium compound. The content of the magnesium compound is preferably 3 mass ppm or more and 30 mass ppm or less, more preferably 3 mass ppm or more and 20 mass ppm or less, and 5 mass ppm or more and 10 mass ppm or less with respect to polyester as a magnesium atom. It is more preferably ppm or less. When it is within the above range, the color tone of the polyester tends to be good and the polymerization reactivity tends to be improved. The magnesium atom content in polyester can be quantified by inductively coupled plasma emission spectroscopy.
It is preferable that the magnesium compound is used as a transesterification catalyst in producing the polyester of the present invention. As the magnesium compound, a conventionally known magnesium compound can be appropriately selected and used, and examples thereof include magnesium oxides, hydroxides, alkoxides, acetates and carbonates.

The polyester of the present invention preferably contains a phosphorus compound. The content of the phosphorus compound is preferably 3 mass ppm or more and 30 mass ppm or less, more preferably 3 mass ppm or more and 20 mass ppm or less, and 5 mass ppm or more and 10 mass ppm or less with respect to polyester as a phosphorus atom. It is more preferably ppm or less. Within the above range, the thermal stability of polyester tends to be improved. The phosphorus atom content in polyester can be quantified by inductively coupled plasma emission spectroscopy.
The phosphorus compound is preferably used as a stabilizer in producing the polyester of the present invention.

The polyester of the present invention has a cyclic trimer content of less than 4000 mass ppm, preferably 3000 mass ppm or less, and more preferably 2000 mass ppm or less. Since it is within the above range, when the polyester is used as a food packaging material, a medical packaging material, or the like by blow molding or extrusion film molding, it is possible to obtain a molded product having a good molded appearance such as few fish eyes. In addition, the cyclic trimer may have an affinity for foods and medical drugs, and when used as a food packaging material or medical packaging material for a long period of time, the cyclic trimer leaks into foods or medical drugs. However, if it is within the above range, the leakage of the cyclic trimer to foods and medical drugs may be significantly eliminated. The content of the cyclic trimer in the polyester can be quantified by liquid chromatography.

The intrinsic viscosity (sometimes referred to as "IV") of the polyester of the present invention is preferably 0.8 dL / g or more and 1.5 or less dL / g, and more preferably 0.9 dL / g or more and 1.4 dL / g. g, more preferably 0.95 dL / g or more and 1.35 dL / g or less. When the intrinsic viscosity is within the above range, polyester having good blow moldability and extruded film moldability can be obtained. The intrinsic viscosity is determined as a value measured at 30 ° C. using a mixed solution of phenol / tetrachloroethane (mass ratio 1/1) as a solvent.

The amount of terminal carboxyl groups of the polyester of the present invention is preferably 1 equivalent / ton or more and 50 equivalents / ton or less, more preferably 2 equivalents / ton or more and 40 equivalents / ton or less, and further preferably 4 equivalents / ton or more 20. Equivalent / ton or less. When the amount of the terminal carboxyl group is in the above range, the hydrolysis resistance tends to be improved. The amount of terminal carboxyl groups in polyester can be determined by a titration method using sodium hydroxide.

The amount of n-heptane eluted in 1 hour at a temperature of 110 ° C. of the polyester-molded sheet of the present invention is preferably less than 0.05 mg / cc, more preferably 0.04 mg / cc or less, and more preferably. Is 0.03 mg / cc or less. When the amount of n-heptane eluted is in the above range, hygiene tends to be excellent. In particular, when the polyester is used as a container or packaging material for containing a hydrophobic food or a hydrophobic medical drug, the polyester-containing material does not leak into the inclusion and the hygiene is excellent.

The amount of water eluted in the sheet formed by molding the polyester of the present invention at a temperature of 110 ° C. for 1 hour is preferably less than 0.0035 mg / cc, more preferably 0.030 mg / cc or less, and more preferably 0. It is .025 mg / cc or less. When the amount of water eluted is in the above range, hygiene tends to be excellent. In particular, when the polyester is used as a container or packaging material for containing a hydrophilic food or a hydrophilic medical drug, the polyester-containing material does not leak into the inclusion and the hygiene is excellent.

(Polyester manufacturing method)
The method for producing the polyester of the present invention is not particularly limited, and a usual method can be applied. For example, a dicarboxylic acid component containing terephthalic acid or an ester-forming derivative thereof, isophthalic acid or an ester-forming derivative thereof and an ethylene glycol, preferably a diol component containing diethylene glycol are mixed at a predetermined ratio with stirring to form a raw material slurry. Then, the raw material slurry is heated under normal pressure or pressure to undergo an esterification reaction to obtain a polyester low polymer (hereinafter, may be referred to as “oligomer”), and then the obtained oligomer is used. A step of adding dimeric acid or an ester-forming derivative thereof, gradually reducing the pressure in the presence of an ester exchange catalyst, etc., and heating to obtain a polyester by melt polycondensation reaction, or a polyester obtained as needed. May be further subjected to a solid phase polycondensation reaction.

It should be noted that either the method of adding the dimer acid or the ester-forming derivative thereof to the raw material slurry or the method of adding to the oligomer can be applied.

[Melted polycondensation]
The oligomer becomes a prepolymer by melt polycondensation in the presence of an ester polycondensation catalyst.
Examples of the ester exchange catalyst include antimony compounds such as diantimon trioxide; germanium compounds such as germanium dioxide and germanium tetroxide; titanium alcoholates such as tetramethyl titanate, tetraisopropyl titanate and tetrabutyl titanate, and tetraphenyl titanate. Titanium compounds such as titanium phenolate; dibutyltin oxide, methylphenyltin oxide, tetraethyltin, hexaethylditinoxide, cyclohexahexyl distin oxide, didodecyltin oxide, triethyltin hydroxide, triphenyltin hydroxide, triisobutyl Tin compounds such as tin acetate, dibutyl tin diacetate, diphenyl tin dilaurate, monobutyl tin trichloride, tributyl tin chloride, dibutyl tin sulfate, butyl hydroxytin oxide, methylstannoic acid, ethylstannoic acid, butylstannonic acid; magnesium acetate, hydroxide Examples thereof include magnesium compounds such as magnesium, magnesium carbonate, magnesium oxide, magnesium alcoholide and magnesium hydrogen phosphate, and calcium compounds such as calcium acetate, calcium hydroxide, calcium carbonate, calcium oxide, calcium alcoholide and calcium hydrogen phosphate. .. Of these, titanium compounds and magnesium compounds are preferable because of their good reaction efficiency. Tetrabutyl titanate is more preferable as the titanium compound, and magnesium acetate is more preferable as the magnesium compound. It should be noted that these catalysts can be used alone or in combination of two or more.

Further, in the production of polyester, it is preferable to use a stabilizer together with an ester exchange catalyst, and the stabilizers include orthophosphorous acid, polyphosphoric acid, and trimethylphosphate, triethyl phosphate, tri-n-butyl phosphate, and trioctyl phosphate. , Triphenyl phosphate, tricresyl phosphate, tris (triethylene glycol) phosphate, ethyl diethylphosphonoacetate, methyl acid phosphate, ethyl acid phosphate, isopropyl acid phosphate, butyl acid phosphate, monobutyl phosphate, dibutyl phosphate, dioctyl phosphate, Five-valent phosphorus compounds such as triethylene glycol acid phosphate, phosphorous acid, hypophosphite, and trivalent phosphorus compounds such as diethyl phosphite, trisdodecyl phosphite, trisnonyl decyl phosphite, and triphenyl phosphite. Can be mentioned. Of these, trivalent phosphorus compounds are generally more reducing than pentavalent phosphorus compounds, and metal compounds added as polycondensation catalysts may be reduced and precipitated, causing foreign matter to be generated. A pentavalent phosphorus compound is preferable.

The reaction pressure in the melt polycondensation reaction is preferably 0.001 kPa to 1.33 kPa in absolute pressure. The reaction temperature is preferably 220 ° C. to 280 ° C., more preferably 230 ° C. to 260 ° C. Further, the reaction time is preferably 1 hour to 8 hours, more preferably 2 hours to 6 hours.
By setting the reaction pressure, reaction temperature, and reaction time, a prepolymer having a high degree of polymerization and a good color tone can be produced.

The glass transition temperature (Tg) of the prepolymer obtained through the melt polycondensation can be determined by a differential scanning calorimeter. The lower limit is preferably 0 ° C, more preferably 5 ° C. The upper limit thereof is preferably 60 ° C., more preferably 50 ° C. If the glass transition temperature (Tg) is too low, the thermal stability tends to be poor. On the other hand, if it is too high, the flexibility may be inferior.

The intrinsic viscosity of the prepolymer obtained through the melt polycondensation is determined as a value measured at 30 ° C. using a mixed solution of phenol / tetrachloroethane (mass ratio 1/1) as a solvent. The lower limit is preferably 0.20 dL / g, more preferably 0.40 dL / g. The upper limit thereof is preferably 1.50 dL / g, more preferably 1.30 dL / g. If the intrinsic viscosity is less than 0.02 dL / g, the mechanical properties tend to be inferior. On the other hand, if it exceeds 1.50 dL / g, the polymerization time may become long and the color tone may deteriorate.

The amount of terminal carboxyl groups of the prepolymer obtained through the melt polycondensation step is preferably 30% by weight / ton or less, and more preferably 20% by weight / ton or less. If the amount of the terminal carboxyl group exceeds this value, the hydrolysis resistance tends to deteriorate.

The prepolymer obtained by the melt polycondensation step is usually extracted in a strand shape from an extraction port provided at the bottom of the polycondensation tank, and then the strand-shaped prepolymer is water-cooled or water-cooled with a cutter. It is preferable to cut it into pellet-shaped or chip-shaped granules.

[Shearing]
It is preferable to roughen the surface of the granules by subjecting the prepolymer obtained as described above to a shearing treatment.

The method of shearing treatment is not particularly limited, and can be carried out using a known shearing treatment apparatus. Generally, it is carried out by stirring the resin pellets so that the resin pellets rub against each other using a shaker, a rice mill, a Henschel mixer, a V blender, a ribbon blender, a tumbler blender, or the like. The temperature (T) of the shearing treatment in the present invention is preferably a temperature equal to or higher than the glass transfer temperature (Tg) of the prepolymer. Further, a more preferable range of the temperature (T) of the shearing treatment is a range satisfying the following formula (1).
Tg ≤ T ≤ Tg + 30 ° C (1)
By setting the temperature (T) of the shearing treatment within the above range, the polyester obtained by solid-phase polycondensation of the sheared prepolymer has good intrinsic viscosity and also reduces the content of cyclic trimer. It is possible to obtain a molded product having an appropriate melt flow volume (MVR), good blow moldability and extruded film moldability, and a small number of fish eyes. Can be done. The temperature (T) of the shearing process is the maximum temperature in the shearing process device when the shearing process is performed by the shearing process device.

[Solid phase polycondensation]
The sheared prepolymer is made into polyester by solid polycondensation. Solid phase polycondensation is usually carried out under a pressure of usually 100 kPa or less, preferably 20 kPa or less as a relative pressure with respect to atmospheric pressure in an atmosphere of an inert gas such as nitrogen, carbon dioxide or argon, or about 5 to 30 hours or so. As the absolute pressure, the upper limit is usually 6.5 kPa, preferably 1.3 kPa, the lower limit is usually 0.013 kPa, preferably 0.065 kPa under reduced pressure, usually about 1 to 20 hours, and the lower limit temperature is usually 190 ° C., preferably. Is generally carried out by heating at 195 ° C. and an upper limit temperature of usually 230 ° C., preferably 225 ° C. By this solid phase polycondensation, the degree of polymerization can be further increased, and the amount of by-produced acetaldehyde or the like can be reduced.
The polyester obtained by the above-mentioned melt polycondensation or solid phase polycondensation can be subjected to the following treatment in order to inactivate the polyester polycondensation catalyst contained therein. Treatments for deactivating the polyester polycondensation catalyst include water treatment in which it is immersed in warm water at 40 ° C. or higher for 10 minutes or longer, steam treatment in which it is in contact with steam at 60 ° C. or higher or a water vapor-containing gas for 30 minutes or longer, and treatment with an organic solvent. , Treatment with acidic aqueous solution or organic solvent solution such as various mineral acids, organic acids, phosphoric acid, phosphite, phosphoric acid ester, treatment with alkaline aqueous solution or organic solvent solution such as Group 1A metal, Group 2A metal, amine, etc. Is commonly done.
By setting the melt polycondensation reaction conditions, shearing treatment conditions, and solid polycondensation reaction conditions, the desired cyclic trimer content, desired intrinsic viscosity, desired n-heptane elution amount, desired water elution amount, and the like can be obtained. It is possible to have polyester.

The polyester of the present invention can be further subjected to a crystal nucleating agent, an antioxidant, an antioxidant, a pigment, a dye, an ultraviolet absorber, a mold release agent, a lubricant, a flame retardant, an antistatic agent, an inorganic substance and / or Organic particles and the like can be blended.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples as long as the gist thereof is not exceeded.

<Intrinsic viscosity (IV)>
About 0.25 g of the sample is dissolved in about 25 mL of a mixed solvent of phenol / 1,1,2,2-tetrachloroethane (mass ratio 1/1) so as to have a concentration of 1.00 g / dL, and then 30 Cool to ℃, measure the falling speed of the sample solution and the number of seconds of falling of the solvent alone with a fully automatic solution viscometer (“DT553” manufactured by Centec) at 30 ℃, and use the following formula to measure the intrinsic viscosity ( IV) was calculated.
IV = ((1 + 4KHη _sp ) ^0.5 -1) / (2KHC)
Here, η _sp = η / η _0-1 , η is the falling speed of the sample solution, η ₀ is the number of seconds for the solvent to fall, C is the sample solution concentration (g / dL), and KH is the Huggins constant. is there. KH adopted 0.33. The dissolution conditions of the sample were 110 ° C. for 30 minutes.

<Amount of terminal carboxyl group>
After crushing the sample, it was dried at 140 ° C. for 15 minutes in a hot air dryer, 0.1 g was precisely weighed from the sample cooled to room temperature in a desiccator, collected in a test tube, and 3 ml of benzyl alcohol was added. , Dissolved at 195 ° C. for 3 minutes while blowing dry nitrogen gas, and then gradually added 5 ml of chloroform and cooled to room temperature. One or two drops of a phenol red indicator was added to this solution, and the solution was titrated with a benzyl alcohol solution of 0.1 N sodium hydroxide under stirring while blowing dry nitrogen gas, and the process was terminated when the color changed from yellow to red. Further, as a blank, the same operation was carried out without dissolving the polyester sample, and the amount of terminal carboxyl groups (acid value) was calculated by the following formula.
Amount of terminal carboxyl (equivalent / ton) = (ab) × 0.1 × f / w
(Here, a is the amount of 0.1 N sodium hydroxide benzyl alcohol solution required for titration (μl), and b is the amount of 0.1 N sodium hydroxide benzyl alcohol solution required for titration without a sample. Amount (μl), w is the amount of polyester sample (g), and f is the titer of 0.1 N sodium hydroxide solution in benzyl alcohol.)

<Quantification of each diol in polyester>
A hot plate with a magnetic stirrer (surface temperature 200) was set with a reflux condenser by adding 30 ml of 4N-KOH / methanol solution to 3 g of polyester crushed using a 1.5 mm hole perforated plate with a Willey type crusher. The mixture was hydrolyzed by heating under reflux for 90 minutes while stirring on (° C.). After cooling by soaking in running water, add about 12 g of high-purity terephthalic acid, shake sufficiently to neutralize, filter the slurry having a pH of 9 or less using an 11G-4 glass filter, and then use 2 ml of methanol for 2 After washing once, the filtrate and the washing solution are combined to prepare a test solution for gas chromatography. 1 μl of the test solution is injected into gas chromatography (type GC-14A) manufactured by Shimadzu Corporation with a microsyringe, and the molar% of each diol component with respect to the total diol component is lowered from the peak area of each diol component. Calculated according to the formula.
Mol% of specific diol component = (ACO × CfCO) / (Σ (A × Cf)) × 100
ACO: Area of specific diol component (μV · sec), CfCO: Correction coefficient of specific diol component A: Area of each diol component (μV · sec), Cf: Correction coefficient of each diol component In addition, in gas chromatography As a condition of use,
Column: "DB-WAX" manufactured by J & W (0.53 mm x 30 m)
Column temperature: 80 ° C to 160 ° C, vaporization chamber temperature: 230 ° C, detector temperature: 230 ° C, gas flow rate: carrier (nitrogen): 10 ml / min, hydrogen: 0.5 kg / cm ² , air: 0.5 kg / cm ^2, detector: FID, sensitivity: was ¹⁰ 2 M.OMEGA..

<Quantification of each dicarboxylic acid in polyester>
About 20 mg of polyester was dissolved in 0.75 ml of a deuterated chloroform / deuterated hexafluoroisopropanol (7/3) mixed solvent, and 25 μl of deuterated pyridine was added to prepare a sample solution. The sample solution is placed in an NMR sample tube having an outer diameter of 5 mm, and Bruker's AVANCE 400 is used.
^{A 1} H-NMR spectrum was measured at room temperature using a spectrometer, and the ratio of each dicarboxylic acid unit to the total dicarboxylic acid units of polyester was determined.

<Contents of various elements in polyester>
Weigh 2.0 g of the sample into a Kjeldahl flask, add 12 mL of sulfuric acid and hydrogen peroxide (add hydrogen peroxide as appropriate), perform wet decomposition until completely dissolved, and then add ultrapure water to the specified concentration. Diluted. The amounts of various elements in this solution were quantified using an inductively coupled plasma emission spectrophotometer (JY46P manufactured by JOBIN YVON) and converted into the amount per sample (mass ppm).

<Melting flow volume per unit time (MVR)>
The polyester sample was vacuum dried at 120 ° C. for 8 hours. Then, the dried polyester sample melt indexer Model L242-4531 (manufactured by Tateyama Kagaku), conforming to ISO 1133, melt flow volume per 240 ° C., the unit was measured at a load 2.16kg time ^(cm 3/10 min) Was MVR (2.16).
If the MVR (2.16) is in the range of 1.0 to 10.0, it can be judged that the blow moldability and the extrusion film moldability are good.

<Cyclic trimer content>
10 g of the polyester sample was dried in an inert oven ("IPHH-201 type" manufactured by EPSEC) under a nitrogen gas stream of 50 L / min at 160 ° C. for 2 hours, and then 4.0 mg was precisely weighed and chloroform /. It was dissolved in 2 mL of a mixed solvent of hexafluoroisopropanol (volume ratio 3/2). Chloroform (20 mL) was added to this solution to dilute it, and methanol (10 mL) was further added to precipitate the solution. The filtrate obtained by filtration was evaporated to dryness and then dissolved in 25 mL of dimethylformamide. The amount of cyclic trimer (cyclotriethylene terephthalate) in this solution was quantified by liquid chromatography (“LC-10A” manufactured by Shimadzu Corporation) and converted to mass ppm per polyester.
When the content of the cyclic trimer is small, the molded appearance is excellent. In particular, if it is less than 4000 mass ppm, it can be judged that the effect is remarkably excellent in the applicability of applications such as blow molding and extrusion molding to prevent mold stains after long-term use and for pharmaceutical purposes where elution component regulation is strict.

<N-heptane elution amount>
The polyester sample was press-molded into a sheet having a length of 20 cm, a width of 20 cm, and a thickness of 0.6 mm. The sheet is immersed in a dish infused with 200 cc of heptane and has a temperature of 110 ° C.
Was heat-treated for 1 hour. Then, the immersion liquid was evaporated to dryness, and the evaporation residue was precisely weighed. The smaller the amount of n-heptane eluted, the less the polyester-containing material leaks into the inclusions, especially when the polyester is used as a container or packaging material for containing hydrophobic foods or hydrophobic medical agents. The hygiene is excellent, and if it is less than 0.05 mg / cc, it can be determined that the effect is remarkably excellent.

<Amount of water eluted>
The polyester sample was press-molded into a sheet having a length of 20 cm, a width of 20 cm, and a thickness of 0.6 mm. The sheet is immersed in a dish infused with 200 cc of water, and at a temperature of 110 ° C., 1
Heat treated for hours. Then, the immersion liquid was evaporated to dryness, and the evaporation residue was precisely weighed. The smaller the amount of water eluted, the more hygienic the polyester-containing material does not leak into the inclusions, especially when the polyester is used as a container or packaging material for containing hydrophilic foods or hydrophilic medical agents. Is excellent, and if it is less than 0.0035 mg / cc, it can be determined that the effect is remarkably excellent.

(Example 1)
50.0 parts by mass of terephthalic acid, 2.60 parts by mass of isophthalic acid and 53.6 parts by mass of ethylene glycol were charged into an esterification reaction tank equipped with a stirrer, a temperature raising device and a distillate separation column, and the temperature was 250 ° C. The esterification reaction was carried out at a pressure of 0.90 kg / cm ^{2 for 4 hours.}
Next, a slurry prepared with 33.3 parts by mass of terephthalic acid, 1.89 parts by mass of isophthalic acid and 16.9 parts by mass of ethylene glycol was continuously charged into the esterification reaction tank and the temperature was 250 ° C. , The esterification reaction was carried out under normal pressure for 4 hours to obtain a polyester low polymer (oligomer).
Next, the oligomer was transferred to a polycondensation reaction vessel equipped with a distiller and equipped with a stirrer, and 8.9 parts by mass of hydrogenated dimer acid (Propol 1009 manufactured by Crowder Japan) having 36 carbon atoms was added, and further used as an ester exchange catalyst. , Ethylene glycol solution of magnesium acetate (3.0% by weight) in 0.15 parts by mass, ethylene glycol solution of tetrabutoxytitanate (1.0% by weight) in 0.36 parts by weight, ethyl acid phosphate as stabilizer Ethylene glycol solution (1.5% by weight) was added in an amount of 0.15 parts by mass.

While maintaining the temperature inside the polycondensation reaction tank at 250 ° C., the pressure was reduced to 0.13 kPa over 2 hours, then the reaction was carried out at the same pressure for 3 hours, and the reaction system was returned to normal pressure to complete the reaction. .. The obtained polyester was extracted as a strand from the bottom of the polycondensation reaction tank, submerged in water, and then the strand was cut with a cutter to obtain polyester pellets (hereinafter sometimes referred to as "pellets").
The obtained pellets were filled in a polybin in which sandpaper was wrapped around the inner wall. Then, shearing treatment was performed with a polybin shaker (Recipro shear SR-25 manufactured by TAITEC).
The pellets after the shearing treatment were subjected to solid phase polycondensation at 190 ° C. under reduced pressure (0.133 Kpa or less) for 74 hours to obtain polyester. The results are summarized in Table 1.

<Example 2>
In Example 1, an ethylene glycol solution (3.0% by weight) of magnesium acetate as an ester exchange catalyst was 0.20 parts by mass, and an ethylene glycol solution (1.0% by weight) of tetrabutoxytitanate was 0.47 parts by mass. As a stabilizer, ethylene glycol solution of ethyl acid phosphate (1.5% by weight concentration) was 0.20 parts by mass, terephthalic acid amount was 30.5 parts by mass, isophthalic acid amount was 1.79 parts by mass, and dimer acid amount. The procedure was the same as in Example 1 except that 12.1 parts by mass and the amount of ethylene glycol were changed to 16.1 parts by mass and 39 kg of the esterification reaction product was transferred to the polycondensation reaction tank. The results are summarized in Table 1.

<Comparative example 1>
Polyester was prepared in the same manner as in Example 1 except that shearing treatment and solid polycondensation were not performed in Example 1. The results are summarized in Table 1.

<Comparative example 2>
Polyester was prepared in the same manner as in Example 2 except that shearing treatment and solid polycondensation were not performed in Example 2. The results are summarized in Table 1.

As shown in Examples, the polyester having the specific composition of the present invention has good blow moldability and extrusion film moldability because it has an appropriate MVR (2.16). Further, since the content of the cyclic trimer is low, when it is used as a food packaging material, a medical packaging material, or the like by blow molding or extrusion film molding, it is possible to obtain a molded product having a good molding appearance such as less fish eyes. .. In addition, the leakage of the cyclic trimer into foods and medical agents may be significantly eliminated. In addition, since the amount of n-heptane eluted is small, when the polyester is used as a container or packaging material for encapsulating hydrophobic foods or hydrophobic medical agents, leakage of the polyester-containing material to the inclusions, etc. When the polyester is used as a container or packaging material for containing hydrophilic foods or hydrophilic medical agents, the polyester is added to the inclusions because of its excellent hygiene and low water elution amount. There is no leakage of inclusions and the hygiene is excellent.
From the above, the polyester of the present invention has good low moldability and extruded film moldability, has a good molded appearance, and is extremely excellent in hygiene. Therefore, food containers, food packaging materials, and medical packaging materials It is useful for.

Claims (11)

A polyester composed of a dicarboxylic acid component and a diol component, which contains 77 mol% or more and 92 mol% or less of terephthalic acid, 3 mol% or more and 10 mol% or less of isophthalic acid, and 5 mol% or more and 13 mol of dimer acid as dicarboxylic acid components. % Or less, containing ethylene glycol as a diol component,
A polyester having a cyclic trimer content of 3000 mass ppm or less. The polyester according to claim 1, wherein the cyclic trimer content is 2000 mass ppm or less. The polyester according to claim 1 or 2 , wherein the intrinsic viscosity is 0.8 dL / g or more and 1.5 dL / g or less. The polyester according to any one of claims 1 to 3, wherein the amount of n-heptane eluted in 1 hour at a temperature of 110 ° C. of the sheet obtained by molding the polyester is less than 0.05 mg / cc. The polyester according to any one of claims 1 to 4 , wherein the amount of water eluted in 1 hour at a temperature of 110 ° C. of the sheet formed by molding the polyester is less than 0.0035 mg / cc. The polyester according to any one of claims 1 to 5 , wherein the polyester contains a titanium compound as a titanium element in an amount of 3 mass ppm or more and 30 mass ppm or less. The polyester according to any one of claims 1 to 6 , wherein the polyester contains a magnesium compound as a magnesium element in an amount of 3% by mass or more and 30% by mass or less. The polyester according to any one of claims 1 to 7 , wherein the polyester contains a phosphorus compound as a phosphorus element in an amount of 3% by mass or more and 30% by mass or less. The polyester according to any one of claims 1 to 8 , which is used for a food container. The polyester according to any one of claims 1 to 8 , which is used as a food packaging material. The polyester according to any one of claims 1 to 8 , which is used as a medical packaging material.