JP2000128965A - Polyester resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a polyester resin having excellent transparency and heat- resistant dimensional stability and useful as a material for containers or packaging materials used for foods or drinks by controlling the haze of a drawn molded product and the haze of a drawn and thermally set molded product to specific values or lower, respectively. SOLUTION: This polyester resin (a linear polyester resin containing ethylene terephthalate units in an amount of >=85 mol.%) contains the ethylene terephthalate units as main repeating units, and is produced in the presence of an antimony compound (for example, antimony trioxide, antimony acetate, antimony tartarate, potassium antimony tartarate, antimony oxychloride or antimony glycolate) as a catalyst. Therein, a drawn molded product formed from the polyester has a haze of <=2.0%, and a drawn and thermally set molded product has a haze of <=5.0%. The polyester preferably further has an intrinsic viscosity of 0.70-0.90 dl/g, a copolymerized DEG content of 1.5-5.0 mol.% based on the glycol component, a density of >=1.37 g/cm3, an aldehyde content of <=10 ppm, and a cyclic trimer content of <=0.35 wt.%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a polyester resin used for molded articles such as bottles, films, sheets and the like. More specifically, the present invention relates to a molded article having excellent transparency and heat-resistant dimensional stability, particularly to a polyester resin which gives a hollow molded article.

[0002]

2. Description of the Related Art Polyester resins, especially polyethylene terephthalate (hereinafter simply abbreviated as "PET") are characterized by their excellent transparency, mechanical strength, heat resistance, gas barrier properties, and the like, and are characterized by carbonated beverages, juices, mineral water, and the like. It has been adopted as a material for containers and its use has been remarkable.

[0003] PET generally used for such applications
Is produced mainly using terephthalic acid and ethylene glycol as raw materials, and using a germanium compound, an antimony compound, a titanium compound and a mixture thereof as a polycondensation catalyst. Among the above-mentioned catalysts, antimony catalysts are used as catalysts for producing PET for fibers and films because of their low cost. However, compared to the case where a germanium compound or a titanium compound is used as a catalyst, the crystallization rate of the obtained PET is high, and it is very difficult to obtain a hollow molded article having excellent transparency.

In order to solve these problems, a germanium compound or a mixture of the compound and a titanium compound is used as a polycondensation catalyst. However, if an expensive germanium compound is used, the cost of PET becomes high.

As a method for solving such a problem,
For example, JP-A-6-279579 discloses a method in which the transparency is improved by regulating the ratio of the antimony compound to the phosphorus compound. However, the transparency of the hollow molded article made of PET obtained by this method is not sufficient. Also, JP-A-10-364
No. 95 discloses a continuous production method of polyester having excellent transparency using antimony trioxide, phosphoric acid and a sulfonic acid compound. However, the polyester obtained by such a method has a problem in that the heat stability is poor and the acetaldehyde content of the obtained hollow molded article is high.

[0006]

DISCLOSURE OF THE INVENTION The present invention solves such a problem and provides a molded article having excellent transparency.
An object is to provide an inexpensive polyester resin.

[0007]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, have reached the present invention.
That is, the polyester resin of the present invention is a polyester resin whose main repeating unit is ethylene terephthalate produced using an antimony compound as a catalyst, and the haze of a molded article stretched by the method specified in the text is 2.
A polyester resin having a haze of not more than 0% and a haze of a molded article stretched and heat-fixed by a method specified in the text is not more than 5.0%.

The polyester resin having the above-mentioned properties gives a molded article having excellent transparency and heat-resistant dimensional stability, especially a hollow molded article.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. The polyester resin having a main repeating unit of ethylene terephthalate in the present invention is a linear polyester resin containing at least 85 mol% of ethylene terephthalate units, preferably at most 90 mol%, more preferably at least 95 mol%. Resin. Examples of the dicarboxylic acid used for copolymerization of the polyester resin include aromatic dicarboxylic acids such as isophthalic acid, 2,6-naphthalenedicarboxylic acid, diphenyl-4,4′-dicarboxylic acid, and diphenoxyethanedicarboxylic acid, and functions thereof. Derivatives, p-oxybenzoic acid, oxyacids such as oxycaproic acid and functional derivatives thereof, adipic acid,
Examples include aliphatic dicarboxylic acids such as sebacic acid, succinic acid, and glutaric acid and functional derivatives thereof, and alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid and functional derivatives thereof.

Glycols used for copolymerization of the polyester resin include aliphatic glycols such as diethylene glycol, trimethylene glycol, tetramethylene glycol and neopentyl glycol; alicyclic glycols such as cyclohexanedimethanol; bisphenol A; Aromatic glycols such as an alkylene oxide adduct of A and the like can be mentioned.

Further, other copolymerizable components comprising a polyfunctional compound in the polyester resin include trimellitic acid and pyromellitic acid as acid components, and glycerin and pentaerythritol as glycol components. Can be mentioned. The amount of the copolymerization component composed of these polyfunctional compounds must be such that the polyester resin maintains a substantially linear shape.

In the polyester resin of the present invention, the main repeating unit produced using an antimony compound as a catalyst is ethylene terephthalate, and the haze of a molded article stretched by the method specified in the text is 2.0% or less, preferably It is 1.5% or less, more preferably 1.0% or less, and the haze of the molded article stretched and heat-fixed by the method specified in the text is 5.0% or less, preferably 4.0% or less, more preferably Is a polyester resin having a content of 3.0% or less.

When the haze of the molded article stretched by the method specified in the text exceeds 2.0% and the haze of the heat-stretched molded article by the method specified in the text exceeds 5.0%, The transparency of the obtained molded product, particularly the molded product fixed by stretching and heat, becomes extremely poor.

The polyester resin of the present invention can be obtained by a direct esterification method in which terephthalic acid and ethylene glycol and / or a third component are directly reacted to remove water and esterify the mixture, followed by polycondensation under reduced pressure, or Dimethyl terephthalate is reacted with ethylene glycol and / or a third component to remove the methyl alcohol and transesterify. Then, it is produced by a transesterification method in which polycondensation is carried out under reduced pressure. , At least one metal compound selected from Ca compounds, Co compounds, Mn compounds and Zn compounds and a P compound are added in two or more portions, and after the esterification or transesterification is substantially completed. To before the polycondensation reaction, by adding the Sb compound to carry out the polycondensation. Further, solid-state polymerization may be performed to increase the molecular weight of the polyester resin and reduce the acetaldehyde content.

The above-mentioned esterification reaction, transesterification reaction, melt polycondensation reaction and solid-state polymerization reaction may be carried out in a batch reactor or a continuous reactor. Mg compound used in the present invention, Ca compound,
All of the Co compound, Mn compound and Zn compound can be used as long as they are soluble in the reaction system.

Examples of the Mg compound include lower fatty acid salts such as magnesium hydride, magnesium oxide and magnesium acetate, and alkoxides such as magnesium methoxide. Examples of the Ca compound include lower fatty acid salts such as calcium hydride, calcium hydroxide and calcium acetate, and alkoxides such as calcium methoxide.

Examples of the Co compound include lower fatty acid salts such as cobalt acetate, organic acid salts such as cobalt naphthenate and cobalt benzoate, chlorides such as cobalt chloride, and cobalt acetylacetonate.

Examples of the Mn compound include organic acid salts such as manganese acetate and manganese benzoate; chlorides such as manganese chloride;
Alkoxides such as manganese methoxide, manganese acetylacetonate and the like can be mentioned.

Examples of the Zn compound include organic acid salts such as zinc acetate and zinc benzoate, chlorides such as zinc chloride, alkoxides such as zinc methoxide, and zinc acetylacetonate.

Examples of the P compound used in the present invention include phosphoric acid, phosphorous acid, phosphonic acid and derivatives thereof. Specific examples include phosphoric acid, trimethyl phosphate, triethyl phosphate, tributyl phosphate, triphenyl phosphate, monomethyl phosphate, dimethyl phosphate, monobutyl phosphate, dibutyl phosphate, and dibutyl phosphate. Phosphoric acid, trimethyl phosphite, triethyl phosphite, tributyl phosphite, methyl phosphonic acid, dimethyl methyl phosphonate, dimethyl ethyl phosphonate, dimethyl phenyl phosphonate, diethyl phenyl phosphonate,
Phenyl phosphonic acid diphenyl ester and the like,
These may be used alone or in combination of two or more.

The Sb compound used in the present invention includes:
Examples include antimony trioxide, antimony acetate, antimony tartrate, antimony potassium tartrate, antimony oxychloride, antimony glycolate, antimony pentoxide, and triphenylantimony.

The Mg compound, Ca compound, Co compound, Mn compound and Zn compound used in the present invention are preferably added at least twice in the course of the production of the polyester resin. The amount is from 0.03 mol / ton of polymer as metal atom to 5.
It is added so as to be in a range of 0 mol.

It is preferable that the P compound used in the present invention be added at least twice in the course of the production of the polyester resin. It is added so that the total metal atom ratio of the compound, the Mn compound, and the Zn compound is in the range of 0.1 to 3.0.

Mg compound, Ca compound, Co compound, M
The method of adding the n-compound, Zn-compound and P-compound in a divided manner is to stagger the addition time when the production of the polyester resin is carried out batchwise, or to change the place of addition when carrying out the continuous production. Can be performed. When the production of the polyester resin is performed in a continuous manner, a method of increasing the number of reaction vessels and separately adding the reaction vessels to at least two reaction vessels, separately adding at least two or more locations in the same reaction vessel in the progress of the reaction. And various methods such as a method of line-mixing a reaction vessel and a continuous section of the reaction vessel.

Mg compound, Ca compound, Co compound, M
As for the division ratio of the addition amount of the n compound and the Zn compound, the initial addition amount is preferably about 50% or less of the total addition amount, and particularly preferably 30% or less. The division ratio of the addition amount of the P compound is such that the initial addition amount is about 50% of the total addition amount.
It is preferably at most 30%, particularly preferably at most 30%. It is also preferable to add them after adding the Mg compound, Ca compound, Co compound, Mn compound and Zn compound, respectively.

The first Mg compound, Ca compound, Co
The addition time of the compound, the Mn compound, the Zn compound and the P compound may be before or during the esterification and transesterification reaction, or after the completion, but the addition time after the second time is during the esterification or transesterification reaction. Or after termination.

The Sb compound used in the present invention is added so that the content in the produced polymer is in the range of 0.1 to 2.5 mol per 1 ton of the polymer as metal atoms. The limiting viscosity of the polyester resin of the present invention is 0.57 to 0.9.
0 dl / g, preferably 0.58 to 0.88 dl / g,
More preferably, it is in the range of 0.60 to 0.85 dl / g. If it is 0.57 dl / g or less, the mechanical properties of the obtained molded article and the like are poor. On the other hand, when it exceeds 0.90 dl / g, the resin temperature increases during melting by a molding machine or the like, and thermal decomposition becomes severe, so that free low-molecular-weight compounds that affect fragrance retention increase, Problems such as yellowing occur.

The amount of diethylene glycol constituting the polyester resin of the present invention is 1.5 to 1.5 of the glycol component.
It is 5.0 mol%, preferably 1.6 to 4.5 mol%, and more preferably 1.7 to 4.0 mol%. When the amount of diethylene glycol is 1.5 mol% or less, the crystallization rate is increased, and the resulting molded article has poor transparency. When the amount of diethylene glycol is 5.0 mol% or more,
The glass transition point of the polyester resin is lowered, the heat resistance of the obtained molded product is lowered, and the thermal stability is poor, so that the amount of acetaldehyde content increased during molding becomes large, which adversely affects the fragrance retention.

The polyester resin of the present invention has an acetaldehyde content of 10 ppm or less, preferably 8 ppm.
Or less, more preferably 5 ppm or less. When the content of acetaldehyde is 10 ppm or more, the contents such as containers molded from the polyester resin have poor flavor and odor.

Further, the cyclic 3 of the polyester resin of the present invention
The content of the monomer is 0.35% by weight or less, preferably 0.3% by weight.
It is at most 3% by weight, more preferably at most 0.32% by weight. When molding a heat-resistant hollow molded article or the like from the polyester resin of the present invention, heat treatment is performed in a heating mold. However, when the content of the cyclic trimer is 0.35% by weight or more, the heating mold is used. Oligomer attachment to the mold surface increases rapidly,
The transparency of the obtained hollow molded article and the like is extremely deteriorated.

The polyester resin of the present invention can be formed into a hollow molded product, a film, a sheet or the like by a generally used melt molding method. When manufacturing a hollow molded article, a transparent, heat-resistant hollow molded article can be produced from the polyester resin of the present invention using a known method such as a hot parison method or a cold parison method.

In the case of producing a hollow molded article using the polyester resin of the present invention, first, a preform is molded by injection molding and then stretch blow-molded to form a bottle. Injection molding is generally performed at an injection temperature of about 265 to about 300 ° C. and an injection pressure of about 30 to about 70 kg / cm ² to form a preform. The plug portion of this preform is crystallized by heat treatment. In the case of the cold parison method, the preformed body obtained in this manner is used in an amount of about 80 to about 12
Preheat to 0 ° C, and about 80-
Cool to about 120 ° C. The preform is stretch blow molded in a blow mold at about 120 to about 210C and then heat treated for about 0.5 to about 30 seconds. The stretching ratio is usually 1.3 to 3.5 times in the machine direction and 2 to 6 in the circumferential direction.
It is better to double.

Further, the polyester resin of the present invention can be used for a laminated film with a different kind of film, a laminated sheet, a laminated body with a metal plate, and a multilayer hollow molded article.
The polyester resin of the present invention may contain various known additives such as a nucleating agent, a stabilizer, an antistatic agent, a coloring agent, an ultraviolet ray inhibitor, an antioxidant, a lubricant, and a release agent, if necessary. Is also good.

[0034]

EXAMPLES The present invention will be described below in more detail with reference to examples, but the present invention is not limited to these examples. The method for measuring the main characteristic values will be described below.

1) Intrinsic viscosity (IV) It was determined from the solution viscosity at 30 ° C in a 1,1,2,2-tetrachloroethane / phenol (2: 3 weight ratio) mixed solvent.

2) Diethylene glycol content (hereinafter referred to as [D
Decomposed with methanol, the amount of DEG was quantified by gas chromatography, and expressed as a ratio (mol%) to the total glycol component.

3) Acetaldehyde content (hereinafter referred to as "AA content") A resin pellet sample / distilled water = 1 g / 2 ml was put into a glass ampoule purged with nitrogen, and the upper portion was sealed and heated at 160.degree.
After performing the time extraction treatment, after cooling, the acetaldehyde in the extract was measured by high-sensitivity gas chromatography, and the concentration was determined as pp.
Indicated by m.

4) Cyclic trimer content of polyester resin A resin pellet sample was prepared by mixing hexafluoroisopropanol /
Dissolve in chloroform mixed solution, further add chloroform and dilute. After adding methanol to precipitate a polymer, the mixture is filtered. The filtrate was evaporated to dryness, made up to volume with dimethylformamide, and quantified by liquid chromatography.

5) Haze (% haze) A section cut out from the trunk of the following stretched molded article and stretched heat-set molded article is measured using a haze meter manufactured by Nippon Denshoku Co., Ltd.

6) Molding of a molded article Using a dried polyester resin, an M-M
Resin temperature 290 ° C (nozzle 2
The preform was molded at a cycle time of 70 seconds at 95 ° C., a first barrel at 290 ° C., a second barrel at 290 ° C., and a lower portion of the hopper at 250 ° C.). Preform shape is 22mm inside diameter
φ, body part thickness 3.7 mm, length 143 mm below support ring part, total weight 58 g. After the plug portion of this preform was heated and crystallized by a home-made plug portion crystallizing device, it was preheated to 90 to 105 ° C., and a room temperature mold was formed using a Corpoplast LB-01 stretch blow molding machine. Biaxial stretch blow molding (primary blow pressure 12-18 kgf / cm ² ,
A secondary blow pressure of 30 to 38 kgf / cm ² ) was used to form a 1500 ml hollow molded container (average wall thickness of 0.4 mm). As a heat-set stretch molded body, a preform was prepared under the same conditions as above, and the plug portion of this preform was heated and crystallized with a home-made plug portion crystallization apparatus, and then LB manufactured by Corpoplast Co., Ltd. Approximately 1 using stretch blow molding machine
Biaxially stretch blow molding was performed in a mold set at 40 ° C., and then heat-set in the mold for 5 seconds to form a 1500 ml hollow molding container (average wall thickness of 0.4 mm).

7) Density of polyester resin pellets: 25 using a density gradient tube of a mixed solvent of carbon tetrachloride / n-heptane.
Measure in ° C.

Example 1 As an esterification apparatus, a first esterification reaction apparatus provided with a stirrer, a decomposer, a raw material charging port and a product taking-out port, and the inside of a reaction vessel were divided into two tanks, A stirrer was attached to the reaction tank, and a three-stage complete mixing tank type continuous esterification reaction apparatus comprising a second esterification reaction apparatus provided with a separator, a raw material inlet, and a product outlet was used. The molar ratio of EG to TPA 1.7 was added to the system where the reaction product was present in the first esterification reactor.
The EG slurry of TPA adjusted to the above was continuously supplied.
At the same time, an EG solution of magnesium acetate tetrahydrate is supplied from another supply port different from the TPA EG slurry supply port so that the Mg atom becomes 0.33 mol (about 8 ppm based on the produced polyester resin) per 1 ton of the produced polyester resin. At a normal pressure, an average residence time of 4 hours and a temperature of 25
The reaction was performed at 5 ° C.

The reaction product was continuously taken out of the system, supplied to the first tank of the second esterification reactor, and continuously taken out of the second tank. The transfer from the first tank to the second tank employed an overflow method. An EG solution of phosphoric acid in an amount of 0.33 mol (about 10 ppm) as P atoms per ton of the produced polyester resin from the supply port on the inlet side of the first tank, the supply port on the inlet side of the second tank 0.9 mg as Mg atoms per ton of polyester resin produced
An EG solution of magnesium acetate tetrahydrate in an amount of 1 mol (about 22 ppm) and 0.61 mol (about 19 ppm) as P atoms per ton of the produced polyester resin from the supply port at the intermediate position of the second tank. An EG solution of phosphoric acid was continuously added in such an amount as to give an average residence time of 2.5 hours for each tank at normal pressure and a reaction was carried out at a temperature of 260 ° C.

Then, the second esterification reaction device
Continuously remove the tellurization reaction product, stirrer,
Two-stages with a vessel, raw material inlet and product outlet
It was continuously fed to a continuous polycondensation reactor. Anti-esterification
From the polycondensation catalyst supply pipe connected to the
As Sb atoms per 1 ton of the produced polyester resin, 1.
6 moles (about 195 ppm) of ammonium trioxide
An EG solution of thymon is supplied to the esterification reaction product, and
Polycondensation at about 270 ° C under reduced pressure using the continuous polycondensation reactor described above
Was done. The IV of the obtained PET resin was 0.54.
Was. This resin was subsequently sent to a continuous solid-state polymerization apparatus, where
Solid phase polymerization was carried out at about 205 ° C. under a hydrogen atmosphere. PE obtained
The T resin has an IV of 0.75, a DEG content of 2.8 mol%,
AA content is 3.2 ppm, cyclic trimer content is 0.33
%, Density 1.400 g / cm ^ThreeMet. Got
Hollow molding of PET resin stretch blown by the above method
The haze of the molded body and the heat-set hollow molded body
It was as good as 0.8% and 2.2%.

Example 2 Using the same apparatus as in Example 1, the esterification reaction and melt polymerization were carried out under the same conditions as in Example 1 except that the amount and position of the metal compound added were changed. An EG solution of magnesium acetate tetrahydrate in such an amount as to give 0.16 mol (about 4 ppm) of Mg atoms per ton of the produced polyester resin from the supply port on the inlet side of the first tank of the second esterification reactor. From the supply port at the intermediate position of the first tank, P
An EG solution of phosphoric acid in an amount of 0.39 mol (about 12 ppm) as atoms, and 0.1 mg as Mg atoms per ton of polyester resin produced from the supply port on the inlet side of the second tank.
An EG solution of magnesium acetate tetrahydrate in an amount of 45 mol (about 11 ppm) and 1.16 mol (about 36 ppm) as P atoms per ton of the produced polyester resin from the supply port at the intermediate position of the second tank. An EG solution of phosphoric acid was continuously added in such an amount as to obtain an esterification reaction.

Then, an EG solution of antimony trioxide in an amount of 1.5 mol (about 183 ppm) as Sb atom per ton of the produced polyester resin was supplied to the esterification reaction product in the same manner as in Example 1. To carry out a polycondensation reaction. IV of the obtained PET resin was 0.53. This resin was subsequently sent to a continuous solid-state polymerization apparatus and subjected to solid-state polymerization at about 205 ° C. under a nitrogen atmosphere. The obtained PET resin had an IV of 0.74, a DEG content of 3.3 mol%, an AA content of 3.5 ppm, and a cyclic trimer content of 0.
32% by weight and a density of 1.400 g / cm ³ . The haze of the hollow molded article obtained by stretch-blowing the obtained PET resin by the above-described method and the hollow molded article obtained by stretching and heat-setting are:
It was good at 0.7% and 2.3%, respectively.

(Comparative Example 1) The total amount of phosphoric acid added in two portions in Example 1 and the same amount of antimony trioxide as in Example 1 were used in the first esterification apparatus. The total amount of magnesium acetate added in two portions was added to the first tank of the second esterification apparatus, and polycondensation was performed under the same conditions as in Example 1 to obtain a prepolymer having an IV of 0.54. Obtained. This was subjected to solid-phase polymerization using the same solid-phase polymerization equipment as in Example 1 under the same conditions, and had an IV of 0.75 and a DEG content of 2.9.
PET with a molar%, AA content of 3.5 ppm, a cyclic trimer content of 0.34% by weight and a density of 1.398 g / cm ³
A resin was obtained. Molding was performed in the same manner as in Example 1, and the haze was measured. As a result, it was as high as 4.8% and 7.2%, and the transparency was poor.

[0048]

The polyester resin of the present invention is inexpensive,
It can be advantageously used as a molded product having excellent transparency and dimensional stability under heat.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B29L 22:00 (72) Inventor Yoshitaka Eto 248-20 Takajo, Shiga-cho, Shiga-gun, Shiga Prefecture F-term (reference) 4F208 AA24 AG01 AG07 AH55 AR15 AR17 AR18 AR20 LA05 LB01 LG01 4J029 AA03 AB01 AC01 AC02 AD01 AE01 AE03 BA03 BA04 BA05 BA10 BB13A BD06A BF09 BF26 CA02 CA04 CA05 CA06 CB05A CB06A CB10A CC06A CD03 CF15

Claims (4)

[Claims] 1. A polyester resin whose main repeating unit produced by using an antimony compound as a catalyst is ethylene terephthalate. The haze of a stretched molded product is 2.0% or less, and the haze of a stretched heat-set molded product is not more than 2.0%. 5.
A polyester resin having a content of 0% or less. 2. The polyester resin according to claim 1, wherein the polyester resin is for a hollow molded article. 3. An intrinsic viscosity of 0.70 to 0.90 dl /
g, the amount of the copolymerized DEG is 1.5 to 1.5 of the glycol component.
2. The polyester resin according to claim 1, which has 5.0 mol% and a density of 1.37 g / cm ³ or more. 4. The polyester resin according to claim 2, wherein the acetaldehyde content is 10 ppm or less and the cyclic trimer content is 0.35% by weight or less.