JPH1045890A - Polyester resin for container - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a polyester resin having little contaminated materials and capable of expressing good color tone and transparency by obtaining a polymer through a liquid phase polycondensation reaction using a specific sulfonic acid- based compound as a polymerization catalyst and polymerizing the obtained polymer in a solid phase. SOLUTION: This polyester resin for containers consists of a dicarboxylic acid (A) unit mainly comprising terephthalic acid and a diol (B) unit mainly comprising ethylene glycol and has 0.70-1.20dl/g intrinsic viscosity. The polyester resin is produced by bringing the ingredient A and the ingredient B to a liquid phase polycondensation reaction to obtain a polymer by using a polymerization catalyst expressed by formula I [R<1> is an alkyl or a cycloalkyl substituted with a carboxyl, an OH, an NH2 , etc., or a halogen; X is H or a group of the formula: NA4 (A is H or an alkyl)], formula II (R<2> is an alkylene), formula III [Y is a group of the formula: OR<3> (R<3> is H or a lower alkyl) or the formula: COOR<4> (R<4> is R<3> ), or a halogen; (m) is 1-3; (n) is 0-3] or formula IV, then polymerizing the obtained polymer in a solid phase.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyester resin for a container which has good transparency and color tone and has little foreign matter.

[0002]

2. Description of the Related Art Polyester resins, especially polyethylene terephthalate (PET), have excellent physical and chemical properties and are widely used in applications such as fibers, films and injection molding. In addition, since it is excellent in hygiene, relatively inexpensive and lightweight, it has been remarkably growing as a container for carbonated drinks, mineral water drinks, juice drinks, liquid seasonings, edible oils, alcohol, wine, etc. It is also used for cosmetics containers, eye drops containers and the like.

[0003] PET is industrially obtained by directly esterifying or transesterifying terephthalic acid or dimethyl terephthalate with ethylene glycol to obtain bis (β-hydroxyethyl) terephthalate and a low polymer thereof, which are used as a catalyst. It is produced by a method of performing polycondensation under a high temperature and a high vacuum. It is well known that a compound of a metal such as zinc, calcium, antimony, cobalt, titanium, germanium, tin or the like is used as a catalyst at the time of PET production.

[0004] Among these catalysts, when an antimony compound is used, the obtained resin is inferior in transparency and has a dark greenish yellowish hue. When a titanium, tin or zinc compound is used, a yellowish tint is obtained. However, there is the disadvantage that the When a germanium compound is used, a PET resin having a relatively good color tone can be obtained, but there is a problem that it is difficult to control the polymerization because it is expensive and easily distills out of the reaction system during the polymerization and the catalyst concentration changes. .

[0005] Further, as a common problem when a metal compound is used as a catalyst, the metal compound precipitates as an insoluble substance during the polymerization reaction, adheres to the inner wall of a reaction vessel or piping, and peels off. There is a problem that the quality of the obtained polyester container is deteriorated because it is mixed as foreign matter into the polyester.

In order to solve these problems, a method for producing a polyester using a specific sulfonic acid compound containing no metal as a polymerization catalyst is disclosed in Japanese Patent Publication No. 59-1416,
JP-B-61-36529, JP-B-61-36777, and JP-B
JP-B-61-36779, JP-B-61-59335, JP-B-63-644
No. 49, for example. When a sulfonic acid compound is used as a polymerization catalyst, the obtained PET is excellent in transparency and does not generate foreign matter when a metal compound as described above is used, so that it has favorable performance as a resin for a polyester container. doing. However, when a container is molded using a resin obtained by each of the methods disclosed above, the container is practically insufficient in performance such as strength and heat resistance of the container, and improvement has been demanded.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a polyester resin for a container which has a good color tone, a small amount of foreign matter, and is excellent in transparency in view of the above situation.

[0008]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems and to produce a polyester resin for a container having excellent transparency. As a result, a sulfonate having a specific structure as a polymerization catalyst was obtained. The inventors have found that the object of the present invention is achieved by further solid-phase polymerization of a polymer obtained by a liquid-phase polycondensation reaction using an acid compound or an intramolecular anhydride thereof as a polymerization catalyst, and reached the present invention. .

That is, the gist of the present invention is as follows. It was obtained by polycondensation reaction using terephthalic acid as a dicarboxylic acid component and ethylene glycol as a diol component as main components, and using one or more sulfonic acid compounds represented by the following formulas (1) to (4) as a polymerization catalyst. Intrinsic viscosity obtained by further solid-phase polymerization of polymer
0.70 to 1.20dl / g polyester resin for containers. R ¹ -SO ₃ X (1) R ^2- (SO ₃ X) ₂ (2) (Y) _n -Ar- (SO ₃ H) _m (3)

Embedded image (4) Here, R ¹ is an alkyl group, a cycloalkyl group, an aralkyl group or a halogen atom (however, when R ¹ is an alkyl group, COOH, OH, NH ₂ , a halogen atom, OSO
₃ H, and may have a substituent group selected from the group consisting of a morpholino group) R ² is an alkylene group and X is hydrogen or NA ₄ (A represents hydrogen or an alkyl group) Y is, OR ^3, COOR ⁴ , a halogen atom (R ³ , R ⁴
Is hydrogen or a lower alkyl group, and when n ≧ 2, Y may be the same or different. Ar is an aromatic group m is 1-3, n is 0-3

[0010]

DETAILED DESCRIPTION OF THE INVENTION The dicarboxylic acid component used in the present invention is mainly composed of terephthalic acid, but a small amount of a dicarboxylic acid component other than terephthalic acid may be present. Examples of dicarboxylic acid components other than terephthalic acid include phthalic acid, isophthalic acid, naphthalenedicarboxylic acid, diphenoxyethanedicarboxylic acid, diphenyldicarboxylic acid, aromatic dicarboxylic acids such as diphenylsulfondicarboxylic acid, adipic acid, and aliphatic acids such as sebacic acid. Examples thereof include dicarboxylic acid and cyclohexane-1,4-dicarboxylic acid. Also, a small amount of an oxycarboxylic acid component such as oxybenzoic acid or glycolic acid may be present. These dicarboxylic acid components may be used alone or in combination of two or more.

The diol component used in the present invention is mainly composed of ethylene glycol.
Other diols may be used in small amounts. As diol components other than ethylene glycol, aliphatic diols such as 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, pentamethylene glycol, hexamethylene glycol, neopentyl glycol, and diethylene glycol; Examples thereof include ethylene oxide adducts of aromatic diol compounds such as bisphenol A and bisphenol S. These diol components may be used alone or in combination of two or more.

As the sulfonic acid compound used in the present invention, those having the structures of the above formulas (1) and (2) include, for example, methanesulfonic acid, ethanesulfonic acid, methionic acid, cyclopentanesulfonic acid, 1
-Ethanedisulfonic acid, 1,2-ethanedisulfonic acid,
1,2-ethanedisulfonic anhydride, 1,3-propanedisulfonic acid, sulfoacetic acid, β-sulfopropionic acid,
Isethionic acid, ethionic acid, ethionic anhydride, 3-oxy-1-propanesulfonic acid, propanesultone, butanesultone, 2-aminoethanesulfonic acid, 2-chloroethanesulfonic acid, 2-chlorosulfonic acid, fluorosulfonic acid , Trifluoromethanesulfonic acid, phenylmethanesulfonic acid, α-phenylethanesulfonic acid, β
-Phenylethanesulfonic acid, 2- (N-morpholino)
Examples include ethanesulfonic acid, 3- (N-morpholino) propanesulfonic acid, ammonium chlorosulfonate, and triethylammonium ethanesulfonate.

As having the structure of the above formula (3),
For example, benzenesulfonic acid, m-benzenedisulfonic acid, p-benzenedisulfonic acid, 1,3,5-benzenetrisulfonic acid, p-toluenesulfonic acid, o-, m
-Or p-sulfobenzoic acid, 5-sulfosalicylic acid, o-hydroxybenzenesulfonic acid, phenol-
2,4,6-trisulfonic acid, anisole-o-sulfonic acid, 1,5-naphthalenedisulfonic acid, 1-naphthol-2-sulfonic acid, o-, m-, or p-chlorobenzenesulfonic acid, o- , M- or p-bromobenzenesulfonic acid, o-, m- or p-fluorobenzenesulfonic acid, 4-chloro-3-methylbenzenesulfonic acid, chlorobenzene-1,4-disulfonic acid, 1-chloro Examples thereof include naphthalene-4-sulfonic acid, 2-chloro-4-sulfobenzoic acid, o-, m-, and p-iodobenzenesulfonic acid.

As having the structure of the above formula (4),
For example, 2-sulfobenzoic anhydride, 3,4-dimethyl-2-sulfobenzoic anhydride, 4-methyl-2-sulfobenzoic anhydride, 5-methoxy-2-sulfobenzoic anhydride, 1- Sulfonaphthoic acid (2) anhydride, 8-sulfonaphthoic acid (1) anhydride, 3,6-disulfophthalic anhydride, 4,6-disulfoisophthalic anhydride, 2,5
-Disulfoterephthalic anhydride.

As a method for polymerizing the polyester resin of the present invention, a dicarboxylic acid component such as terephthalic acid and a diol component such as ethylene glycol are mixed, and the esterification reaction is directly carried out under pressure. There are a method of performing polycondensation while gradually reducing the pressure, and a method of performing a transesterification reaction using a lower alkyl ester of dicarboxylic acid and a diol, and further polycondensing the obtained reaction product. The sulfonic acid compound and the phosphorus compound as a polymerization stabilizer in the present invention can be added in optional steps, but are preferably added immediately before the start of polymerization from the viewpoint of productivity and ease of handling.

The polymerization reaction may be performed in one step or may be performed in a plurality of steps. When performing in multiple steps,
The reaction temperature of the first stage polycondensation is usually from 250 to 300 ° C, preferably from 260 to 290 ° C, and the pressure is usually from 10 to 0.1 Torr, preferably from 5 to 0.5 Torr. The intrinsic viscosity (η) reached in each of these polycondensation reaction steps is not particularly limited, but it is desirable that the ratio of the intrinsic viscosity in each stage is smoothly distributed, and that the final stage polycondensation reactor The intrinsic viscosity of the polyester obtained from 0.45 to 0.80
dl / g, preferably 0.50 to 0.70 dl / g. The prepolymer obtained by the above polycondensation is desirably formed into chips having a length, width and height of 2.0 to 5.5 mm.

Solid phase polymerization is subsequently carried out to increase the intrinsic viscosity of this prepolymer and to reduce the content of low molecular weight substances and acetaldehyde. That is, the prepolymer chips are usually heated at 190 to 230 ° C, preferably at 195 to 225 ° C.
At a pressure of 1 kg / cm ² G to 10 Torr, preferably normal pressure to 100
Solid-state polymerization is carried out under an inert atmosphere of nitrogen, argon, carbon dioxide, etc. under the conditions of torr. The polymerization time reaches the desired physical properties in a shorter time as the temperature is higher, but usually 1 to 50 hours,
Preferably, it is 5 to 30 hours, more preferably 10 to 25 hours.

By the solid phase polymerization treatment described above, the limiting viscosity is 0.6
A polyester of 0-1.50 dl / g, preferably 0.70-1.20 dl / g, is obtained. When the intrinsic viscosity is less than 0.60 dl / g, when a container is molded using the obtained polyester resin,
Practically sufficient strength cannot be obtained. In addition, the intrinsic viscosity is
If it exceeds 1.50 dl / g, the melt viscosity will be too high,
It is not preferable because a large amount of shear heat is generated at the time of injection and extrusion molding to cause a decomposition reaction and generate bubbles.

The method of molding a container using the polyester resin of the present invention includes direct blow molding, biaxial stretch blow molding, extrusion molding into a sheet, vacuum molding,
A method of obtaining a container by air pressure molding or the like can be used. For example, in a biaxial stretch blow molding method, after forming a preform by injection molding or extrusion molding,
Reheat and biaxially stretch blow. In this case, the molding temperature is
270-300 ° C, stretching temperature 70-120 ° C, preferably 80-
The stretching ratio is usually in the range of 1.5 to 3.5 times in the vertical direction and 2 to 5 times in the horizontal direction. The obtained hollow molded body can be used as it is, but especially in the case of a content liquid that requires hot filling, such as fruit juice beverage, oolong tea, mineral water, etc., generally, it is further heat-fixed in a blow mold and further heat-resistant. Is imparted. Heat fixing is under tension due to compressed air, etc., 100 to 200
C., preferably 120-180.degree. C., for several seconds to several minutes.

Next, the present invention will be described more specifically with reference to examples. Various measurement methods used in the examples are shown below.

(1) Intrinsic viscosity (η) 200 mg of a sample collected from a preform or a bottle is dissolved in 20 ml of a phenol / tetrachloroethane (weight ratio 1: 1) mixed solvent at 105 ° C. for 20 minutes with stirring. 20 solution
The solution viscosity was measured by a Ubbelohde viscometer in a constant temperature water bath at ℃, and the intrinsic viscosity was calculated from this. (2) Crystallinity A density gradient tube of n-heptane and carbon tetrachloride was prepared, and the density of the container was determined at 20 ° C. From this, the crystallinity was calculated according to the following equation. Crystallinity Xc (%) = [(ρc / ρ) × (ρ−ρam) / (ρ
c−ρam)] × 100 ρ: measured density (g / cm ³ ) ρam: amorphous density (1.335 g / cm ³ ) ρc: crystal density (1.455 g / cm ³ ) (3) Haze ASTM-D-1003- It was measured according to 59T. (4) Gloss The panel of the body of the container was cut out, and the gloss of the outer surface was measured with a mirror mirror at 60 degrees (JIS Z 8741). (5) Amount of oligomer 400 sample collected from preform or bottle body
mg was dissolved in 5 ml of 0-chlorophenol at 130 ° C., allowed to cool, and dropped into 300 ml of a tetrahydrofuran (THF) solution to precipitate a polymer. After filtration and washing, the filtrate was concentrated to finally give 20 ml of a 0-chlorophenol / THF mixed solution,
It was analyzed and quantified by liquid chromatography. (6) Acetaldehyde content The PET preform was finely pulverized in liquid nitrogen, and this powder was heated at 145 ° C for 2 hours by 4CM type gas chromatography manufactured by Shimadzu Corporation, and the amount of acetaldehyde released from the production peak was determined. Was. (7) Color tone Cut out the body panel of the container and use the color difference meter to measure L, a,
b value was determined. L value is lightness (larger value is brighter),
The a value indicates a red-green hue (+ indicates reddish,-indicates greenish), and the b value indicates a yellow-blue hue (+ indicates yellowish and-indicates blueish). The color tone is better as the L value is larger, the a value is closer to 0, and the b value is smaller unless the value is extremely small. (8) Foreign matter amount The foreign matter amount was measured by a foreign matter inspection device including a stereo microscope, a CCD television camera, a CRT monitor, and attached devices. 1 kg of the polymer chip after the solid-phase polymerization was magnified 100 times by the above-mentioned foreign substance measuring apparatus, and the number of foreign substances of 0.1 mm (10 mm on the screen) or more was measured.

Example 1 A slurry of terephthalic acid and ethylene glycol (ethylene glycol / terephthalic acid molar ratio: 1.5) was continuously supplied to an esterification reactor in which bis (β-hydroxyethyl) terephthalate and its oligomer were present.
The esterification reaction was carried out for 6 hours at a normal pressure and a reaction rate of 96
% Esterification product was obtained continuously. 1.5 mol of 5-sulfosalicylic acid was added to 1 mol of the acid component.
× 10 ^-4 mol, and reduced the pressure in the polycondensation tank to finally 0.1
The polycondensation was carried out at 285 ° C. for 2 hours. The obtained polymer had an η of 0.70 and was almost colorless and had good transparency. After crystallizing the prepolymer chip surface at 150 ° C. with a stirring crystallization machine, the prepolymer chip was transferred to a stationary solid-state polymerization tower, and
After drying at 150 ° C for 3 hours under nitrogen flow of L / Kg · hr, 215
Solid-state polymerization was performed at 20 ° C. for 20 hours to obtain a solid-phase polymerization chip having η of 0.78. Next, using this solid-phase polymerization chip, using an injection molding machine manufactured by Nissei ASB Co., Ltd., cylinder parts and nozzle temperature 280 ℃, screw rotation speed 100 rpm, injection time 10
The preform was molded at a mold temperature of 10 ° C. for seconds. This preform was blow molded at a preheating furnace temperature of 90 ° C., a blow pressure of 20 kg / cm ² , and a molding cycle of 30 seconds.
The bottle had an internal volume of 1 L. As shown in Table 1, the properties of the obtained bottle were such that the haze was low, the color tone was good, the transparency was excellent, and the amount of foreign matters was small. .

Comparative Example 1 The esterification product obtained in Example 1 was added to the acid component 1
2.5 × 10 ^-4 mole of germanium dioxide was added to the mole,
The pressure was reduced in the polycondensation tank and polycondensation was finally performed at 0.1 Torr and 285 ° C. for 2 hours. The obtained polymer had an η of 0.72 and was almost colorless and had good transparency. After crystallizing the prepolymer chip surface at 150 ° C with a stirring crystallizer, it is transferred to a stationary solid-state polymerization tower, dried at about 150 ° C for 3 hours under a nitrogen flow of 20 L / Kg · hr, and then dried at 215 ° C. Solid phase polymerization was performed for 20 hours to obtain a solid phase polymerization chip having η of 0.79. Next, using this solid-phase polymerization chip, the content was reduced to 1 in the same manner as in Example 1.
L bottles were molded. The obtained bottle had a low haze, but had a slightly large amount of foreign substances. Table 1 shows the characteristics of the bottle.

Examples 2 to 11 and Comparative Examples 2 to 3 Except that polymerization was carried out by adding various sulfonic acid compounds shown in Table 1 to the esterified product obtained in Example 1 while changing the amount of addition. In the same manner as in Example 1, a bottle having an internal volume of 1 L was formed. The results are shown in Table 1.

Comparative Example 4 The same procedure as in Example 1 was repeated, except that the esterification product obtained in Example 1 was replaced by another metal compound shown in Table 1 as a catalyst instead of the sulfonic acid compound. Bottles were molded. The results are shown in Table 1.

[0026]

[Table 1]

[0027]

According to the present invention, it is possible to obtain a polyester resin for a container which has good transparency and color tone and has little foreign matter.

Claims (1)

[Claims] 1. A terephthalic acid as a dicarboxylic acid component,
As a diol component, ethylene glycol is used as a main component,
A polymer obtained by a liquid phase polycondensation reaction using one or more sulfonic acid compounds represented by the following formulas (1) to (4) as a polymerization catalyst is further subjected to solid-state polymerization to obtain an intrinsic viscosity 0.70. Polyester resin for containers up to 1.20dl / g. R ¹ -SO ₃ X (1) R ^2- (SO ₃ X) ₂ (2) (Y) _n -Ar- (SO ₃ H) _m (3) (4) Here, R ¹ is an alkyl group, a cycloalkyl group, an aralkyl group or a halogen atom (however, when R ¹ is an alkyl group, COOH, OH, NH ₂ , a halogen atom, OSO
₃ H, and may have a substituent group selected from the group consisting of a morpholino group) R ² is an alkylene group and X is hydrogen or NA ₄ (A represents hydrogen or an alkyl group) Y is, OR ^3, COOR ⁴ , a halogen atom (R ³ , R ⁴
Is hydrogen or a lower alkyl group, and when n ≧ 2, Y may be the same or different. Ar is an aromatic group m is 1-3, n is 0-3