JPH09278871A - Molding made from polyester copolymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a molding, especially a repeatedly usable bottle, made from a polyester copolymer improved in hydrolysis resistance without detriment to the excellent properties of a conventional polyethylene naphthalate. SOLUTION: This molding is made from a polyester copolymer in which the acid component is 2,6-naphthalenedicarboxylic acid, and the glycol component comprises ethylene glycol, 1,4-cyclohexanedimethanol in an amount to give a molar ratio of the ethylene glycol to the 1,4-cyclohexanedimethanol of 99/1 to 60/40 and 0-5wt.%, based on the polyester copolymer, polytetramethylene glycol. The molding is excellent in heat resistance and transparency as well as in hydrolysis resistance.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a molded product made of a polyester copolymer.

[0002]

2. Description of the Related Art Conventionally, glass containers have been widely used as containers for filling seasonings, oils, juices, carbonated drinks, beers, sake, cosmetics, detergents and the like. However, since the glass container has a high manufacturing cost, it is usually recycled by collecting an empty container after use and refilling the contents. When the glass container is recycled in this manner, the glass container is heavy, the transportation cost is high, and it is easily damaged, which is inconvenient to handle.

In an attempt to overcome these drawbacks of glass containers, the conversion from glass containers to various plastic containers has been rapidly progressing recently. As the material, various plastics are adopted depending on the type of filling contents and the purpose of use, and among these plastic materials, saturated crystalline polyester resin such as polyethylene terephthalate is mechanical strength and heat resistant. Since it has excellent properties, transparency and gas barrier properties, it is used as a material for containers such as juices, soft drinks, carbonated drinks, seasonings, detergents and cosmetics. Further, all the filled hollow containers are required to have excellent transparency.

On the other hand, in order to repeatedly fill and reuse a bottle, a bottle that has undergone a washing process and a sterilization process for removing foreign substances adhering to the bottle or adsorbed substances such as taste components and aroma components adsorbed on the bottle can be used. The contents are sent to the filling process. In this washing step, alkaline water such as an aqueous solution of sodium hydroxide is usually used to remove the adsorbed substance on the bottle. At this time, the bottle manufactured from polyethylene terephthalate is not suitable for a bottle that is repeatedly used from the viewpoints of whitening of the surface and deterioration of mechanical strength due to hydrolysis with alkaline water. That is, it must be a molded product having excellent hydrolysis resistance.

In recent years, polyethylene naphthalate has been developed as a polyester having heat resistance, chemical resistance and mechanical properties superior to those of polyethylene terephthalate, but it is not sufficient in terms of hydrolysis resistance to alkaline water as described above. Absent.

[0006]

DISCLOSURE OF THE INVENTION The inventors of the present invention have made earnest studies to improve the hydrolysis resistance of saturated crystalline polyester resins such as polyethylene terephthalate and polyethylene naphthalate, and found that 1,4 It was found that the copolymerization of cyclohexanedimethanol improves the transparency and the hydrolysis resistance, and the copolymerization of polytetramethylene glycol further improves the hydrolysis resistance.

It is an object of the present invention to provide a molded product made of a polyester copolymer having improved hydrolysis resistance while maintaining the excellent properties of conventional polyethylene naphthalate, particularly a bottle which can be used repeatedly. It is in.

[0008]

In the molded article of the present invention, the acid component is 2,6-naphthalenedicarboxylic acid, and ethylene glycol and 1,4-cyclohexanedimethanol are used as glycol components in a molar ratio of ethylene glycol /
1,4-cyclohexanedimethanol = 99 / 1-60
It is characterized by comprising a polyester copolymer which is contained at a ratio of / 40 and which is obtained by copolymerizing polytetramethylene glycol in an amount of 0 to 5% by weight with respect to the polyester copolymer.

Examples of the molded article of the present invention include bottles and preforms, which are particularly suitable as reusable bottles. The acid component of the polyester copolymer according to the present invention contains 2,6-naphthalenedicarboxylic acid as a main component.

The glycol component of the polyester copolymer according to the present invention contains ethylene glycol and 1,4-cyclohexanedimethanol as essential components. The copolymerization ratio of 1,4-cyclohexanedimethanol is 1 to 40 mol%, preferably 2 to 30 mol% with respect to the total amount of ethylene glycol and 1,4-cyclohexanedimethanol.
More preferably, it is 3 to 20 mol%. When the copolymerization ratio is 1 mol% or more, excellent hydrolysis resistance can be obtained, and when the copolymerization ratio is 40 mol% or less, the thermal stability of the polyester copolymer and the dimensional stability of the molded product are less likely to decrease. . In the present invention, 1,4-cyclohexanedimethanol may be a cis isomer, a trans isomer or a mixture thereof. In the present invention, polytetramethylene glycol is not an essential component, but the inclusion of this in the copolymer component further improves the hydrolysis resistance. The number average molecular weight of the polytetramethylene glycol used here is preferably 500 to 6000. When the number average molecular weight is 500 or more, the effect of improving hydrolysis resistance is high, and when the number average molecular weight is 6000 or less, phase separation is less likely to occur and the resin is less likely to whiten.

The amount of polytetramethylene glycol copolymerized is 0 to 5% by weight, preferably 0.01 to 5% by weight, more preferably 0.1 to 5% by weight, based on the polyester copolymer.
2% by weight. When the copolymerization amount is 0.01% by weight or more, hydrolysis resistance is further improved, and when the copolymerization amount is 5% by weight or less, reduction in heat resistance of the resin can be suppressed.
The polyester copolymer according to the present invention has hydrolysis resistance,
Other acid components or glycol components may be copolymerized within the range of not impairing transparency and mechanical properties.

Specific examples of such an acid component include terephthalic acid, isophthalic acid, 2,7-naphthalenedicarboxylic acid, adipic acid and sebacic acid. Further, examples of the glycol component include propylene glycol, tetramethylene glycol, neopentyl glycol, diethylene glycol and the like.

[0013]

Preferred embodiments of the present invention will be described below. In producing the polyester copolymer according to the present invention, 2,6-naphthalenedicarboxylic acid and / or its polyester-forming derivative (for example, methyl ester, ethyl ester) is used as a main component as an acid component. The raw material polymer used in the present invention can be produced by a conventionally known polyester production method. For example, a melt polycondensation reaction in which an acid component and a glycol component are directly esterified, or when a dialkyl ester is used as the acid component, a transesterification reaction is performed with the glycol component and then heating under reduced pressure is performed to remove an excess glycol component. By doing so, a polyester copolymer can be produced. That is, the melt polycondensation method will be described more specifically. For example, a condensate of 2,6-naphthalenedicarboxylic acid or an ester derivative thereof and ethylene glycol and 1,4-cyclohexanedimethanol or a dicarboxylic acid thereof, or Further, polytetramethylene glycol is added simultaneously or sequentially, preferably 10
These initial polycondensates are formed by esterification or transesterification reaction at a temperature of 0 to 290 ° C., which is then heated to a temperature above its melting point, preferably 200 to 320 ° C. under vacuum or under an inert gas flow. A method of performing polycondensation with stirring can be exemplified.

The polyester copolymer used in the present invention can also be produced by further solid phase polycondensing the polyester copolymer obtained by the melt polycondensation method as described above to extend the molecular weight. You can Specifically explaining such a solid phase polycondensation method,
For example, a method of holding the polyester copolymer by the melt polycondensation method at a temperature equal to or lower than the melting point, preferably 160 to 240 ° C. under vacuum or under an inert gas flow can be employed.

Known catalysts can be used. Specific examples of the transesterification reaction catalyst include compounds such as magnesium, manganese, titanium, zinc, calcium and cobalt, and as a polycondensation catalyst. A compound such as antimony, germanium or titanium can be used. The transesterification catalyst and polycondensation catalyst may be added in any amounts as long as the reactivity and heat resistance of the polyester are not impaired, but they are usually 10 to 300 ppm based on the total weight of the raw material monomers.

The preform according to the present invention is formed of the above polyester copolymer. The polyester copolymer constituting the preform for the hollow molded article of the present invention is, if necessary, a conventionally known nucleating agent, inorganic filler, lubricant, slip agent, antiblocking agent, stabilizer, antistatic agent, Various additives such as antifogging agents and pigments may be contained within the range not impairing the object of the present invention.

The method for producing the preform for hollow molded article of the present invention is not particularly limited, but a conventionally known method can be used. ASTM D-2 in a mixed solution of phenol / 1,1,2,2-tetrachloroethane of the polyester copolymer according to the present invention (weight ratio = 1/1)
The intrinsic viscosity measured at 25 ° C by the method according to 857 is usually 0.4 to 1.2 dl / g, preferably 0.45.
~ 1.0 dl / g.

The polyester copolymer having such an intrinsic viscosity has excellent stretchability. The hollow container made of the polyester copolymer according to the present invention can be molded by, for example, stretch blow molding the preform made of the polyester copolymer. As a stretch blow molding method, the preform is stretched in the machine direction within the stretching temperature range of the copolymer and then further blown.
A method of stretching in the transverse direction by molding (biaxial stretching blow method) and the like can be mentioned.

For example, by the biaxial stretching blow molding method,
To produce the polyester container of the present invention, a bottomed parison formed by a usual injection molding machine or a parison obtained by bottoming one end of the parison formed by an extrusion molding machine is used as a polyester copolymer. At a stretching temperature of 90 to 150 ° C., a rod that moves in the longitudinal direction in a blow molding die and a blow of a pressurized gas blows 1 to 1 in the vertical direction.
3.5 times, preferably 2 to 3 times and 2 to 6 in the horizontal axis direction
An example is a method of stretching twice, preferably 3 to 5 times. The blow molding die temperature is usually room temperature or higher, preferably 30 to 230 ° C., and more preferably 100.
~ 200 ° C. As a molding method by injection molding,
Either a two-stage system using a cold parison or a one-stage system using a hot parison may be used.

In the present invention, it is desirable to heat-set the obtained stretch-blow molded bottle after the stretch-blow molding as described above. When the stretch blow molded bottle is heat set in this manner, the hydrolysis resistance is further improved. The heat setting is usually carried out by stretching the blow-molded polyester copolymer bottle in the mold as described above at a mold temperature of 100 to 230 ° C., preferably 130 to 200 ° C. for 1 second or longer, preferably 3 seconds. It is performed by holding the above.

[0021]

EXAMPLES The present invention will be described below with reference to examples and comparative examples, but the present invention is not limited to these examples. In the following examples and comparative examples, the hydrolysis resistance was evaluated as follows. A press sheet having a thickness of 0.5 mm was prepared at a temperature of 300 ° C. using each polyester. Cut out to a length of 50 mm and a width of 30 mm, 80
Add 3 to 50 ml of 4% sodium hydroxide solution heated to ℃.
Soaked for hours. During the immersion, the shaker was shaken 60 times per minute.

The following items were evaluated for the samples before and after immersion. Surface whitening degree The surface of the sample before and after immersion was visually evaluated. ◯: No change, ×: Change Transparency The haze of the sample before and after the immersion was measured by using a haze meter, NDH-20D manufactured by Nippon Denshoku Co., Ltd., and ASTM D 10
According to No. 03, the haze of the test piece was measured three times, the average value was obtained, and the difference in haze before and after immersion was calculated. Rate of change in intrinsic viscosity Rate of change in intrinsic viscosity of the sample before and after immersion:

[0023]

[Equation 1] I asked.

Dissolution test The UV spectrum of the sodium hydroxide aqueous solution after the test was measured using a spectrophotometer MPS-2000 (manufactured by Shimadzu Corporation). The absorbance was calculated from the value of the absorption peak observed at the position of 284.4 nm. Further, the amount of 2,6-naphthalenedicarboxylic acid was calculated in terms of monomer from the obtained absorbance value.

Example 1 140 parts by weight of ethylene glycol, 1,4-cyclohexanedimethanol (hereinafter referred to as "C
Abbreviated as "HDM") 15 parts by weight, 244 parts by weight of dimethyl 2,6-naphthalenedicarboxylate, and 0.25 parts by weight of manganese acetate tetrahydrate are charged into a reactor, and under a nitrogen atmosphere at atmospheric pressure at 240 ° C. for 3 hours The reaction was carried out with stirring. Then
The heating temperature was set to 260 ° C. and the reaction was carried out for 3 hours. The methanol produced by this reaction was always distilled out of the system.

Next, 0.2 of a mixture solution containing germanium dioxide and ethylene glycol in a weight ratio of 1:10.
After adding 4 parts by weight to the reaction system and stirring for 20 minutes, 0.08 parts by weight of phosphoric acid was added and reacted for 1 hour. Then 1
The temperature was raised to 280 ° C. over time, the pressure inside the system was reduced to 1 torr, the reaction was continued for 4 hours, and excess ethylene glycol was distilled out of the system. After completion of the reaction, the reaction product was taken out of the reactor in a strand shape, immersed in water, cooled, and then cut into a chip shape by a strand cutter.

The intrinsic viscosity measured at 25 ° C. in a mixed solution of phenol / 1,1,2,2-tetrachloroethane (weight ratio = 1/1) of the polyester copolymer obtained by the above liquid phase polymerization is It was 0.57 dl / g. As a result of NMR analysis, the copolymerization ratios of ethylene glycol and CHDM were 95 mol% and 5 mol%, respectively.
Alkaline hydrolysis test using a press sheet of the obtained polyester copolymer (surface whitening degree, intrinsic viscosity change rate,
Dissolution test) was performed.

The obtained polyester copolymer was molded with a molding machine (M-100A manufactured by Meiki Seisakusho Co., Ltd.) to obtain a preform for bottle molding. The molding temperature at this time is 28
It was 0-300 degreeC. Next, the preform obtained as described above was used as LB-01 manufactured by CORPOPLAST.
It was molded with a molding machine to obtain a biaxially stretched bottle. At this time, the stretching temperature was 140 to 150 ° C, and the mold temperature was 100 ° C. The stretching ratio is 2.0 times in the longitudinal direction and 5.0 in the transverse direction.
It was 0 times. The molded bottle body was cut out and subjected to an alkali hydrolysis test (change in transparency). Table 1 shows the results
It was shown to.

(Examples 2 to 4) Bottles were molded according to Example 1 except that the addition amount of the glycol component in Example 1 was changed as shown in Table 1. The results are shown in Table 1.

Example 5 140 parts by weight of ethylene glycol, 15 parts by weight of CHDM, 244 parts by weight of 2,6-naphthalenedimethyl, polytetramethylene glycol (hereinafter abbreviated as "PTMG") (number average molecular weight 1000)
1 part by weight and 0.25 part by weight of manganese acetate tetrahydrate were charged into a reactor and reacted under a nitrogen atmosphere at atmospheric pressure at 240 ° C. for 3 hours with stirring. Then, the heating temperature was set to 260 ° C. and the reaction was carried out for 3 hours. The methanol produced by this reaction was always distilled out of the system.

Next, 0.2 of a mixture solution containing germanium dioxide and ethylene glycol in a weight ratio of 1:10.
After adding 4 parts by weight to the reaction system and stirring for 20 minutes, 0.08 parts by weight of phosphoric acid was added and reacted for 1 hour. Then 1
The temperature was raised to 280 ° C. over time, the pressure inside the system was reduced to 1 torr, the reaction was continued for 4 hours, and excess ethylene glycol was distilled out of the system. After completion of the reaction, the reaction product was taken out of the reactor in a strand shape, immersed in water, cooled, and then cut into a chip shape by a strand cutter.

The intrinsic viscosity measured at 25 ° C. in a mixed solution of phenol / 1,1,2,2-tetrachloroethane (weight ratio = 1/1) of the polyester copolymer obtained by the above liquid phase polymerization is It was 0.57 dl / g. As a result of NMR analysis, the copolymerization ratios of ethylene glycol and CHDM were 95 mol% and 5 mol%, respectively.
The copolymerization ratio of PTMG was 0.95% by weight with respect to the polyester copolymer. An alkaline hydrolysis test (surface whitening degree, limiting viscosity change rate, elution test) was performed using the obtained polyester copolymer press sheet.

The obtained polyester copolymer was molded with a molding machine (M-100A manufactured by Meiki Seisakusho Co., Ltd.) to obtain a preform for bottle molding. The molding temperature at this time is 28
It was 0-300 degreeC. Next, the preform obtained as described above was used as LB-01 manufactured by CORPOPLAST.
It was molded with a molding machine to obtain a biaxially stretched bottle. At this time, the stretching temperature was 140 to 150 ° C, and the mold temperature was 100 ° C. The stretching ratio is 2.0 times in the longitudinal direction and 5.0 in the transverse direction.
It was 0 times. The molded bottle body was cut out and the alkali hydrolysis test (change in transparency) was measured. The results are shown in Table 1.

(Examples 6 to 8) Bottles were molded according to Example 5 except that the addition amount of the glycol component in Example 5 was changed as shown in Table 1. The results are shown in Table 1.

(Example 9) The bottle molded in Example 5 was held in a mold having a mold temperature of 150 ° C for 20 seconds and heat set. The results are shown in Table 1.

Comparative Example 1 According to Example 1, except that 132 parts by weight of ethylene glycol and 246 parts by weight of dimethyl 2,6-naphthalenedicarboxylate were used as raw materials.
The bottle was molded. The results are shown in Table 1.

Comparative Example 2 A bottle was molded according to Example 1 except that 132 parts by weight of ethylene glycol and 190 parts by weight of dimethyl terephthalate were used as raw materials. The results are shown in Table 1.

[0038]

[Table 1]

[0039]

EFFECT OF THE INVENTION Since the polyester copolymer molded article of the present invention is excellent in hydrolysis resistance, deterioration of surface appearance and strength reduction due to washing with alkaline water are small, and heat resistance and transparency are excellent. Therefore, it is particularly suitable as a bottle that can be repeatedly used.

Front page continuation (72) Inventor Shoji Hiraoka 6-1-2 Waki, Waki-cho, Kuga-gun, Yamaguchi Prefecture Mitsui Petrochemical Industries, Ltd. (72) Takashi Hama 6-Waki, Waki-cho, Kuga-gun, Yamaguchi No. 1 and 2 Mitsui Petrochemical Industry Co., Ltd.

Claims (4)

[Claims] 1. The acid component is 2,6-naphthalenedicarboxylic acid, and ethylene glycol and 1,4-cyclohexanedimethanol are used as glycol components in a molar ratio of ethylene glycol / 1,4-cyclohexanedimethanol = 99/1. A molded product comprising a polyester copolymer which is contained in a proportion of from 60 to 40 and which is obtained by copolymerizing polytetramethylene glycol into the polyester copolymer in an amount of from 0 to 5% by weight. 2. The molded product according to claim 1, which is a preform. 3. The molded product according to claim 1, which is a bottle. 4. The molded product according to claim 3, which is a bottle that can be repeatedly used.