JPH11217428A - Polyester-based resin and blow molded article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prepare a polyester molded article having a good transparency and appearance by blow molding in a high yield by using a polyester obtained using an antimony catalyst. SOLUTION: A polyester-based resin is obtained by polymerizing at least a carboxylic acid component, mainly terephthalic acid and a diol component, mainly ethylene glycol using an antimony catalyst and a crystallization temperature after a treatment of heating for 1 hour at 290 deg.C and quenching with liquid nitrogen is 6 deg.C or more higher than that before the treatment. A molded article is obtained by blow molding of the same.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a polyester resin which hardly becomes defective due to crystallization and fogging or whitening during heating or blow stretching of a preform in bottle production. The present invention also relates to a blow-molded product using such a polyester resin, particularly to a polyester bottle suitable for filling a soft drink, a fruit drink, tea, and the like.

[0002]

2. Description of the Related Art Conventionally, polyethylene terephthalate polymerized with germanium dioxide as a catalyst has been used as a polyester resin for beverage bottles. Polyethylene terephthalate using a germanium dioxide catalyst has a high crystallization temperature, and did not crystallize and whiten even if the resin was exposed to high temperatures during the bottle manufacturing process. However, cost reduction of raw material resin has recently been strongly demanded. For this reason, the catalyst used for the polymerization of the polyester resin used as the resin for bottles is changed from expensive germanium dioxide to inexpensive antimony trioxide commonly used for the polymerization of polyester resins for fibers and films. That is being considered. However, the polyester resin polymerized using the antimony trioxide catalyst has a low crystallization temperature of 138 to 144 ° C. When trying to obtain a bottle by blow molding such a resin, the resin is crystallized during heating or blow stretching of the preform at a temperature of 101 to 145 ° C., and the obtained bottle is whitened or cloudy. I do. That is, the polyester resin obtained by using antimony trioxide as a polymerization catalyst has a problem that the yield during blow molding is deteriorated.

It is an object of the present invention to provide a polyester resin which is polymerized using an antimony catalyst, but the resin is crystallized during blow molding, for example, during heating or blow stretching of a preform, and becomes cloudy or white. An object of the present invention is to provide a polyester-based resin from which a transparent molded article can be obtained without being converted. Another object of the present invention is to provide a transparent blow-molded article using, as a raw material, a polyester resin polymerized using an antimony-based catalyst.

[0004]

As a result of intensive studies to achieve the above object, the present inventors have found that even a polyester resin obtained using an antimony-based polymerization catalyst has 2
The crystallization temperature after heating at 90 ° C. for 1 hour and then quenching with liquid nitrogen is 6 ° C. lower than the crystallization temperature of the untreated resin.
If it is more expensive, it will be clouded by blow molding,
The inventor discovered that the whitening disappeared and completed the present invention.

That is, the present invention provides (1) at 290 ° C. for one hour obtained by polymerizing at least a dicarboxylic acid component mainly containing terephthalic acid and a diol component mainly containing ethylene glycol using an antimony catalyst. Polyester resin whose crystallization temperature after heating and quenching with liquid nitrogen is 6 ° C. or more higher than the crystallization temperature before the treatment, (2) solid-state polymerization after polymerization is melt-polymerized. A polyester resin according to the above (1),
(3) The polyester resin according to the above (1), wherein the acid value of the polyester resin is 18 eq / t or more; and (4) at least a dicarboxylic acid component mainly composed of terephthalic acid and a diol component mainly composed of ethylene glycol are antimony. 290 ° C. obtained by polymerization using a system catalyst
A molded product obtained by blow-molding a polyester resin having a crystallization temperature of 6 ° C. or more higher than the crystallization temperature before the treatment after performing a treatment of quenching with liquid nitrogen after heating for 1 hour at (5). The present invention relates to a molded article according to the above (4), which is a bottle.

When the polyester resin of the present invention is used, the polyester resin obtained by using germanium dioxide as a polymerization catalyst is used without forming a cloudy molded product or a whitened molded product by blow molding. As in the case, a transparent blow molded product can be obtained with a high yield.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. The crystallization temperature of the polyester resin of the present invention after being subjected to a treatment of heating at 290 ° C. for 1 hour and then rapidly cooling with liquid nitrogen is higher by 6 ° C. or more than the crystallization temperature before the treatment. Is required. If the temperature difference is less than 6 ° C., a molded product obtained by blow molding using this resin is inconvenient because it becomes cloudy or white. Preferably, the temperature is higher by 10 to 32 ° C.

The above treatment is described in detail. 5 g of a polyester resin dried under reduced pressure is put into a glass ampoule,
After purging with nitrogen three times, the glass ampoule was sealed under reduced pressure of about 100 Torr, immersed in a salt bath made of potassium nitrate / calcium nitrate at 290 ° C. for 1 hour, taken out, cooled with liquid nitrogen, and then cooled. Remove the resin from The crystallization temperature of the resin is measured by DSC.

The resin of the present invention can be obtained, for example, by adjusting the acid value of the polyester resin to 18 eq / t or more.

In order to increase the acid value of the polyester resin to 18 eq / t or more, for example, the acid value of the reaction mixture after the completion of the esterification is usually adjusted to about 350 eq / t. , Preferably 500 eq
Adjust around / t. As a method of adjusting the acid value of the esterification reaction mixture in this way, for example, in batch polymerization, the reaction time of the esterification reaction product is shorter than usual. In the continuous polymerization, an initial esterification tank (oligomer acid value at the outlet: 1000 to 3000 e) is produced at a normal production amount.
When the temperature of (q / t) is lowered by 1 ° C., the oligomer acid value at the outlet of the initial esterification tank increases by 150 to 250 eq / t. Thus, the acid value at the end of the esterification is adjusted to a desired value.

Further, there is a correlation between the acid value of the polyester resin and the polymerization rate, in particular, the solid-state polymerization rate.
When q / t, the polymerization rate becomes maximum, and when the acid value is larger than that, the polymerization rate becomes gradually lower. Therefore, the preferred acid value of the polyester resin is 21 to 53 eq / t, and more preferably 33 to 43 eq / t.

The main component of the dibasic acid in the polyester resin of the present invention is terephthalic acid. The amount of terephthalic acid in the dibasic acid is not particularly limited, but is preferably 90% by weight or more. Acids that can be used other than terephthalic acid include aromatic dicarboxylic acids such as isophthalic acid, 2,6-naphthalenedicarboxylic acid, diphenyl-4,4′-dicarboxylic acid, diphenoxyethanedicarboxylic acid and functional derivatives thereof, adipic acid, Aliphatic dicarboxylic acids such as sebacic acid, azelaic acid and succinic acid and their functional derivatives, alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid and hexahydroterephthalic acid and their functional derivatives, p
Oxyacids such as oxybenzoic acid and oxycaproic acid, and functional derivatives thereof.

The main component of the diol of the polyester resin of the present invention is ethylene glycol. The amount of ethylene glycol in the diol component is not particularly limited, but is preferably 65% by weight or more. Components that can be used other than ethylene glycol include aliphatic glycols such as diethylene glycol, trimethylene glycol, tetramethylene glycol, neopentyl glycol, alicyclic glycols such as cyclohexane dimethanol, bisphenol A, and alkylene oxide adducts of bisphenol A. And aromatic glycols.

As an antimony compound which is a polymerization catalyst for a polyester resin, compounds described in JP-B-39-6397, JP-B-43-15999, JP-B-46-3998 and the like can be used. it can. For example, antimony trioxide, antimony triacetate,
Triethoxyantimony, antimony trilinoleate,
Examples include antimony trioleate, trimethylantimony oxide, and antimony pentoxide. Among them, antimony trioxide is the most excellent because it is easy to handle and the cost is low. The addition amount of the antimony compound is preferably 140 to 410 ppm based on the resin. If the amount is small, the time required for polymerization of the resin is prolonged. If the amount is too large, the resin becomes dark.

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, followed by polycondensation under reduced pressure, or It is produced by a transesterification method or the like in which dimethyl terephthalate is reacted with ethylene glycol and / or a third component to remove the methyl alcohol and transesterify, followed by polycondensation under reduced pressure. In particular, it is preferable to raise the acid value of the esterification reaction mixture higher than usual by shortening the aging time after the completion of the ester reaction, for example, by solid-phase polymerization after melt polymerization, as described above.

The intrinsic viscosity of the polyester resin of the present invention is preferably from 0.7 to 1.0 dl / g, more preferably from 0.75 to 1.0 dl / g.
0.85 dl / g is more preferred.

The crystallization temperature of the polyester resin of the present invention is preferably 135 to 169 ° C., and 140 to 162 ° C.
C is more preferred.

When a molded article such as a bottle is obtained from the polyester resin thus obtained by blow molding, a heat stabilizer, a (thermal) oxidation stabilizer, an antistatic agent, a weather resistance stabilizer, a lubricant, a pigment, Dyes, pigment dispersants, and the like can be appropriately added as long as the object of the present invention is not impaired.

The blow-molded product is a two-stage stretch blow-molding method (cold parison method) in which a parison molded by a known injection molding machine or the like is stretch-blown using a stretch blow molding machine. One-step method (hot parison method) in which stretching and stretch blow molding are performed by the same machine
Can be formed by a stretch blow molding method, a direct blow molding method, an extrusion blow molding method, or the like. In order to reduce the acetaldehyde content of molded articles such as bottles, blow molding using a vent type injection molding machine is preferred.

For example, in a polyester bottle, the temperature of a blow mold at the time of bottle blow molding is set to 120 so that the filling temperature of the beverage can withstand a high temperature of 85 to 93 ° C.
Heat set to ~ 140 ° C. When the polyester resin of the present invention is used for this blow molding, the crystallization temperature of the resin is sufficiently high, so that the resin is crystallized and fogged during heating or blow-stretching of the preform, and becomes white and defective. And a good bottle can be manufactured.

[0021]

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 of measuring the characteristic values measured in the examples will be described below. (1) Intrinsic viscosity (IV) of polyester resin (dl /
g) It was determined from the solution viscosity at 30 ° C. in a 1,1,2,2-tetrachloroethane / chlorophenol (2: 3 weight ratio) mixed solvent. (2) Measurement of crystallization temperature by DSC 10 mg of each sample was weighed using a DSC type RDC220 of Seiko Denshi Kogyo Co., Ltd., and measured at a heating rate of 10 ° C / min. Analysis of crystallization temperature is based on JIS K
The temperature at the top of the crystallization peak was defined as the crystallization temperature. (3) Acid value (AV) (eq / t) A sample is heated and dissolved in benzyl alcohol, and after cooling, chloroform is added. Next, it titrated with 1 / 50N-KOH and measured. (4) Haze A 1.5L bottle was cut out at the top, middle and bottom of the shoulder and body, and measured with a haze meter of Toyo Seiki Co., Ltd.
The average of the two was displayed.

Examples 1 to 7 and Comparative Examples 1 to 4 Using terephthalic acid and ethylene glycol,
Esterification at ℃, each using antimony trioxide, antimony acetate, germanium dioxide as a polymerization catalyst,
Polymerization was performed at 280 ° C. and casting was performed to produce chips. IV, AV and crystallization temperature (T
cl, ° C) are shown in Table 1.

Each of these chips was weighed into a 5 g glass ampule, and the ampule dried under reduced pressure at 105 ° C. for 24 hours was replaced with nitrogen three times and sealed. This ampoule
The ampoule was immersed in an oil bath at 90 ° C. for one hour, and then the ampoule was quenched in liquid nitrogen. The crystallization temperature of the resin thus treated was measured. Table 1 shows the results.

[0024]

[Table 1]

In particular, when the resin has an AV of 18 eq / t or more, the crystallization temperature of the resin is significantly increased by the heat retention treatment at 290 ° C. as the acid value of the resin is higher than before the heat treatment. Such a resin had a ΔTcl of 6 ° C. or more after the above-mentioned heat treatment at 290 ° C. for one hour, and the heat did not increase the haze value. On the other hand, ΔTc
The resin having l less than 6 ° C. had a haze value of 10 or more due to heat, and the appearance of the molded article was clouded.

Examples 8 to 10 and Comparative Examples 5 to 7 In the same manner as in Examples 1 to 7, a resin whose polymerization catalyst was antimony trioxide, antimony acetate or germanium dioxide was polymerized. The resin was crystallized at 160 ° C. for 4 hours, followed by 20
Solid phase polymerization was carried out at 5 ° C until the IV shown in Table 2 was reached. Table 2 shows the AV and IV of the obtained resin. Using these resins, a preform was molded at 290 ° C. in a 1.5 L heat-resistant bottle mold at 290 ° C. using a Dino Melter M-1 manufactured by Meiki Seisakusho Co., Ltd.
At 00, injection molding was performed. Next, KRUPP CORPOL
Using a AST made LB01-E, the parison was blow molded at a surface temperature of 102 ° C. to produce a 1.5 L heat-resistant bottle. The plug of the heat-resistant bottle was cut off, and the crystallization temperature was measured by DSC measurement. Table 2 also shows the results.
The haze was measured when the bottle was heat set (HS) with the temperature of the blow mold at 140 ° C. and when the heat was not set at 70 ° C. with the mold. Table 2 shows the results.

[0027]

[Table 2]

As can be seen from Table 2, especially when the resin has an AV of 18 eq / t or more, ΔTcl is 6 ° C. or more, the crystallization temperature of the plug is increased, and the haze of the bottle body is small. It was good. When the resin had a ΔTcl of less than 6 ° C., the crystallization temperature of the plug was not increased, and the haze of the body of the bottle was large, resulting in a defective product.

[0029]

When a bottle is blow-molded using the polyester resin of the present invention, a transparent and good-looking bottle can be produced without whitening or fogging of the bottle.

Claims (5)

[Claims] 1. A method comprising polymerizing at least a dicarboxylic acid component mainly composed of terephthalic acid and a diol component mainly composed of ethylene glycol using an antimony catalyst, heating the mixture at 290 ° C. for 1 hour and then using liquid nitrogen. A polyester resin having a crystallization temperature after quenching treatment of at least 6 ° C. higher than the crystallization temperature before the treatment. 2. The polyester resin according to claim 1, wherein the polymerization comprises melt polymerization followed by solid phase polymerization. 3. The polyester resin having an acid value of 18 eq / t.
The polyester resin according to claim 1, which is as described above. 4. Heating at least 290 ° C. for 1 hour, obtained by polymerizing at least a dicarboxylic acid component mainly composed of terephthalic acid and a diol component mainly composed of ethylene glycol, followed by liquid nitrogen A molded article obtained by blow-molding a polyester resin having a crystallization temperature after quenching treatment of at least 6 ° C. higher than the crystallization temperature before the treatment. 5. The molded article according to claim 4, which is a bottle.