WO1998055529A1 - Polyester, process for producing the same, and gas-barrier container made by using the polyester - Google Patents

Abstract

A polyester which is excellent in transparency, appearance, impact resistance, and heat resistance and is moldable into a gas-barrier container especially suitable for use as the body of a blood-sampling tube. The polyester is made up of 99 to 50 mol % ethylene terephthalate units and 1 to 50 mol % ethylene isophthalate units, and has an acid value of 40 eq/t or lower, a needle penetration at 60 °C of 50 νm or smaller as measured with a Vicat softening point meter under the conditions of a sample thickness of 1 mm, a load of 1 kg/mm2, and a heating rate of 0.83 °C/min, and an oxygen permeability constant of 2.8 ml.mm/m2.24-hr.atm or lower.

Description

 Specification

Polyester, production method thereof, gas barrier container using this polyester

 The present invention relates to a polyester which can be used as a gas barrier container having excellent transparency, appearance, impact resistance and heat resistance, a method for producing the same, and a gas barrier uniform container using the polyester. . In particular, the present invention relates to a gas barrier container that can be suitably used as a blood collection tube main body. Background technology ''

 The blood collection tube used to collect the blood must have a gas barrier property to maintain the reduced pressure required to collect the required amount of blood, or oxygen to prevent the collected blood from altering or discoloring. It is required to have a gas barrier that blocks air and air, and especially oxygen barrier. In addition, transparency is required so that the contents can be seen. For this reason, known blood collection tubes are generally made of glass having excellent gas barrier properties and transparency. However, there is a problem that the blood collection tube body made of glass is easily damaged during blood collection and transportation, and is heavy. Therefore, a light and durable blood collection tube body is required.

In order to solve such problems, light and durable plastic containers have been proposed. For example, a material made of polyethylene terephthalate (hereinafter referred to as “PET”) and a material made of polyethylene isocyanate (hereinafter referred to as “PEI”) have been proposed. Have been. However, plastic containers made of PET are excellent in transparency and moldability, but have high oxygen permeability and poor gas barrier properties. Therefore, for example, when used as a blood collection tube main body, a required amount of blood cannot be collected, or the collected blood is easily discolored or deteriorated. On the other hand, plastic containers made of PEI have excellent gas barrier properties, but because PEI is an amorphous resin, it is usually 1 to 2 at a low temperature of about 50 ° C, which is lower than the glass transition temperature. PEI pellets are being dried for weeks. This takes time and reduces productivity. In addition, PEI has significantly lower impact resistance than PET. Therefore, application to the blood collection tube body is not desirable o

 Japanese Patent Application Laid-Open Nos. Sho 60-134348, Sho 61-43655, and Sho 62-2851 disclose PET and PEI-based weights. A polyester container using a blended product has been proposed. Japanese Patent Publication No. Hei 6-20901 proposes a method for producing a bottle by blow stretching using a blend of a high-viscosity PET and a low-viscosity PEI polymer. Have been. However, none of the publications described in these publications achieve the required gas barrier properties, but do not take measures for heat resistance. Therefore, when a blood collection tube main body reduced in vacuum is constructed, it has low heat resistance and easily deforms during transportation at a temperature of about 50 ° C.

Japanese Patent Application Laid-Open No. Sho 59-64658 proposes a polyester obtained by melt-blending amorphous PEI and highly crystalline PET or a copolymer thereof. However, since this polyester uses amorphous and hygroscopic PEI as an essential component of the molten blend, The above productivity problem cannot be solved. In addition, the melt-blended polyester does not have a controlled acid value, and therefore, when the blood collection tube body is similarly decompressed to a vacuum, the heat resistance is low,

Deforms easily during transportation at temperatures around 50 ° C.

 Japanese Patent Application Laid-Open No. 3-23769-69 proposes a main body of a vacuum blood collection tube using a PET copolymer containing 90 to 98 mol% of ethylene terephthalate units. However, when producing this PET-based copolymer, if more than 10 mol% of ethylene isoflurane units are introduced for the purpose of improving the gas barrier property, the isofluric acid The glass transition temperature of the PET copolymer is lowered due to the use of monoamide as a copolymer component. As a result, the productivity is poor because the polymers adhere to each other during drying and the polymer adheres to the surface of the dryer. In addition, the blood collection tube body obtained by molding the PET copolymer is also easily deformed by heat and has poor transparency. For this reason, the method described in Japanese Patent Application Laid-Open No. 3-23969 cannot introduce an ethylene isophthalate unit sufficient to obtain sufficient gas barrier property.

 In Japanese Patent Publication No. 5-672282, crystalline PET and 1,3-bis (2-hydroxyethoxybenzene) component or 1,4-bis (hydroxyethoxybenzene) component are described. A blood collection tube body made of a blend with a PEI-based copolymer having a special chemical structure into which 5 to 90 mol% of the compound has been introduced has been proposed. However, the blood collection tube body made of this blend is expensive because it uses a special diol component.

The present invention provides a gas having excellent transparency, appearance, impact resistance and heat resistance. It is a technical object to provide a polyester that can be used as a barrier-unique container, a method for producing the same, and a gas-barrier container made of the polyester that can be suitably used particularly as a blood collection tube main body. Disclosure of the invention

 The present inventors have made intensive studies to solve the above problems, and as a result, have accomplished the present invention.

The polyester of the present invention is composed of 99 to 50 mol% of ethylene terephthalate units and 1 to 50 mol% of ethylene isophthalate units, and has an acid value of 40 eq / t or less; with VICAT softening point measuring apparatus, a sample having a thickness of l mm, when the temperature was raised under a load LKG / mm ^2, heating rate 0. 8 3 ° C / min, a load of 6 0 ° C Placing needle penetration displacement Ri der than 5 0〃M, the oxygen permeability coefficient is 2. 8 mi - According to the polyesters of the _c the present invention which is characterized in that less ^{mm / m 2 · 2 4 hrs} · atm For example, by containing an ethylene isophthalate unit in the range of 1 to 50 mol%, a gas-barrier property is imparted to a container made of this polyester. Ethylene ethylene resin alone gives a polyester with poor moldability in container production and impact resistance of the container, but it should contain ethylene terephthalate in the range of 99 to 50 mol%. As a result, a polyester having improved moldability / impact resistance and excellent transparency is obtained. When the acid value is 40 eq / t or less, the polyester has excellent heat resistance. With VICAT softening point measuring apparatus, a sample having a thickness of l mm, load LKG / mm ^2, when the temperature was raised under the condition of heating rate 0. 8 3 ° C / min , a load of 6 0 ° C Penetration displacement of hooked needle should be 50 5m or less This also makes the polyester excellent in heat resistance. The blood collection tube is formed by combining the ethylene terephthalate unit and the ethylene isophthalate unit so that the oxygen permeability coefficient is 2.8 β · mm / m ² '24 hrs' atm or less. A polyester excellent in gas barrier properties that can be suitably used as a main body can be obtained.

In order to further improve gasoline and liability, it is necessary to use an ethylene terephthalate unit of 92 to 50 mol% and an ethylene isocyanate unit of 8 to 50 mol% with an oxygen permeability coefficient of More preferably, the bond is made to be 2.3 β. Mm / m ² · 24 hrs · atm or less.

 In order to produce a polyester having excellent heat resistance and gas barrier properties, a highly crystalline polyethylene terephthalate having an acid value of 30 eq / t or less and an acid value of 40 eq / t or less are required. It is preferable to form a molded blend (a dry blend) with an ethylene terephthalate / ethylene phthalate copolymer. By this molding blend method, a polyester having an acid value of 40 eq / t or less and excellent in heat resistance and gas barrier properties can be obtained. This polyester also has excellent impact resistance. Furthermore, the polyester has improved crystallinity, which can reduce sticking troubles during molding, eliminate white spots (silver) on molded products, and improve appearance. Get better. Further, the time required for drying the copolymer is shorter than that of the PEI homopolymer, and the productivity is improved.

A container molded using such a gas-barrier polyester has sufficient transparency and gas-barrier properties, and is lighter and more durable than a glass blood collection tube main body. Can be used for BEST MODE FOR CARRYING OUT THE INVENTION

The polyester of the present invention contains ethylene terephthalate units in the range of 99 to 50 mol%, ethylene soleate units in the range of 1 to 50 mol%, and has an acid value of 40 to 50 mol%. eq / t Ri der below using VICAT softening point measuring apparatus, a sample having a thickness of 1 mm, when the temperature was raised under a load LKG / mm ^2, heating rate 0. 8 3 ° C / min , 6 0 ° needle penetration displacement under a load of C is Ri der 5 0〃 m or less, the oxygen permeability coefficient obtained in a manner discussed later is 2. 8 m ^ · mm / m z - 2 4 hrs * Atm or less.

 Ethylene softphthalate units can achieve the required gas barrier properties with only a small amount contained in the polyester, but must contain at least 1 mol%. If the blending ratio of ethylene isophthalate unit is less than 1 mol%, the required gas barrier property cannot be obtained. The higher the content of ethylene isophthalate units, the better the gas barrier properties of the polyester. However, the ethylene isophthalate unit reduces the impact resistance and has a hygroscopic property. Therefore, if the content of the polyester in the polyester is too large, the viscosity is reduced when a container is formed using the polyester. Wear problems are more likely to occur, and white spots are more likely to occur on the molded product, resulting in poor appearance. Therefore, in the present invention, the content of the ethylene isophthalate unit contained in the polyester is

It is necessary to make 50 mol% the upper limit.

Correspondingly, ethylene terephthalate units are contained in the range of 99 to 50 mol%. Contains this ethylene terephthalate unit As a result, the polyester has the required moldability, as well as transparency and appearance.

The acid value as an index of heat resistance must be 40 eq / t or less. If the acid value is higher than this, the desired heat resistance cannot be obtained, and when the container is made of a polyester, it tends to be deformed during transportation at a temperature of about 50 ° C. Similarly, a 1-mm-thick sample was heated at a load of 1 kg / mm ² and a heating rate of 0.83 ° C / min using a VICAT softening point measuring device, which is also an indicator of heat resistance. At that time, the penetration displacement of the needle with a load at 60 ° C must be 50 zm or less. If the intrusion displacement becomes larger than this, similarly, the desired heat resistance cannot be obtained, and the container made of polyester tends to be deformed during transportation at a temperature of about 50 ° C.

Oxygen permeability coefficient which is a gas barrier one of indicators, it is necessary that 2 or less ^{8 m · mm / m z ·} 2 4 hrs · atm. If the oxygen permeability coefficient is higher than this, when applied to the blood collection tube main body, the required amount of blood cannot be collected, and the blood will be discolored or deteriorated, making it impossible to perform the required test. .

In order to further ensure the gas barrier property, transparency, appearance, etc., the polyester of the present invention may contain from 92 to 50 mol% of an ethylene terephthalate unit and from 8 to 50 mol% of an ethylene isophthalate unit. Do Ri, the oxygen permeability coefficient is 2. 3 m ^ - particularly preferably ^{mm / m z · 2 4 hrs} · atm or less.

The production method for obtaining the polyester of the present invention is not particularly limited. For example, if terephthalic acid, isofluric acid, and ethylene glycol are the main components produced by melt copolycondensation After mixing PET and ethylene terephthalate / ethylene isophthalate copolymer (hereinafter referred to as “ET / EI copolymer”) using a blender such as a turn-blender blender, A method of melt blending using a melt kneader or a method of simply blending PET and ET / EI copolymer during injection molding (this method is called “molding blend” or “dry blending”. ) And the like. Of these, molded blends are particularly preferred.

 Specifically, the molded blend is made of ET / EI copolymer obtained by melt copolycondensation with terephthalic acid, isofluric acid, and ethylene glycol as main components, and PET. This is to produce polyester by pellet blending during injection molding.

 The polyester of the present invention can be produced using only the ET / EI copolymer. However, although the obtained polyester has good transparency and gas barrier properties, it tends to cause sticking troubles during molding. Therefore, in order to improve moldability, it is preferable to blend the ET / EI copolymer and PET as described above. It is necessary to completely dry the / EI copolymer and then blend it with PET PET drying generally takes about 1 to 2 weeks at a low temperature of about 50 ° C to dry the PEI homopolymer pellet. However, in the present invention, since the ET / EI copolymer is used, the ET / EI copolymer is dried at about 60 ° C. compared to the PEI homopolymer. It can be reduced to about 5 days, and productivity is high.

At this time, the intrinsic viscosity of PET is preferably in the range of 0.6 to 0.9. If the intrinsic viscosity is lower than 0.6, the gas barrier When the intrinsic viscosity is higher than 0.9, it becomes difficult to mold into a gas barrier container.

 When producing an ET / EI copolymer, the component ratio between the ethylene terephthalate unit and the ethylene terephthalate unit is ET / EI = 35/65 to 5/95 in molar ratio. It is particularly preferred that If the ethylene isophthalate unit is less than 65 mol%, a large amount of ET / EI copolymer must be added at the time of molding to introduce the ethylene isophthalate unit. Inferior. On the other hand, if the ethylene isophthalate exceeds 95 mol%, the drying efficiency is poor and the productivity is poor.

 The intrinsic viscosity of the ET / EI copolymer is preferably in the range of 0.6 to 0.9. If the intrinsic viscosity is lower than 0.6, the physical properties of the gas barrier uniform container are reduced, and if the intrinsic viscosity is higher than 0.9, it becomes difficult to mold the gas barrier uniform container.

Therefore, according to the present invention, it is possible to reliably achieve an oxygen permeability coefficient of 2.8 m · mm / m ² · 24 hrs · atm or less, and furthermore, a gas barrier having good moldability with less adhesion trouble during molding. Thus, an acidic polyester is obtained.

In the polyester of the present invention, the acid value thereof is 40 eq / t or less so that the blood collection tube main body depressurized in vacuum is not thermally deformed even when transported at a high temperature of about 50 ° C. It is necessary. Specifically, as described above, PET and ET / EI are obtained by molding and blending an ET / EI copolymer having an acid value of 4 Oeq / t or less and a PET having an acid value of 30 eq / t or less. Compared to melt blended EI copolymers, ester exchange between ethylene terephthalate units and ethylene phthalate units Since the conversion reaction is suppressed and the thermal decomposition reaction is suppressed, the acid value of the obtained polyester is controlled to 40 eq / t or less.

 In this way, it is possible to prevent a decrease in heat resistance due to moisture absorption of the acid terminal group (carboxyl group) by adjusting the acid value of the polyester to 40 eq / t or less, especially by applying a molding blend. Becomes

 If the acid value of the polyester is larger than 40 eq / t, the molded article formed by this polyester will absorb more moisture, and thus the heat resistance will be reduced.

 If the acid value of the ET / EI copolymer described above is greater than 40 eq / t or the acid value of PET is greater than 30 eq / t, ethylene terephthalate units and ethylene Since the ester exchange reaction with the evening rate unit easily proceeds, the heat resistance of the molded article formed by this polyester is lowered, which is not preferable.

In the present invention, for the purpose of similarly improved heat resistance, VI CA T with a softening point measuring apparatus, a sample having a thickness of l mm, load LKG / mm ^z, heating rate 0. 8 3 ° C / When the temperature is raised under the min condition, the penetration displacement of the loaded needle at 60 ° C must be 50 m or less. If the intrusion displacement is larger than this, the softening at high temperatures exceeds the allowable limit, and the required heat resistance cannot be achieved.

In the present invention, in addition to the above-described container such as the blood collection tube main body, a food container such as a jelly container or a purine container that requires gas barrier properties is formed by injection molding using the polyester. be able to. Known techniques can be adopted during the injection molding. (These containers made of polyester have a gas barrier property, and Since it has good appearance and excellent transparency and heat resistance, it can be suitably used particularly as a blood collection tube main body. Example

 Next, the present invention will be specifically described based on examples. However, the present invention is not limited to only these examples.

 In the examples and comparative examples described below, various physical property values were measured by the following methods.

 (1) Intrinsic viscosity: Measured at a temperature of 20 ° C using an equal weight mixture of phenol and tetrachloride as solvent, and calculated in d / g units.

 (2) Glass transition temperature [T g] (° C): Measured at a heating rate of 20 ° C / min using a differential scanning calorimeter (DT-40, manufactured by Toritsu Seisakusho Co., Ltd.). I

/ ο

 (3) Acid value (eq / t): 0.150 g of the crushed sample was precisely weighed in a special test tube, benzyl alcohol was added and dissolved by heating, and then transferred to a Meyer containing black hole form. The special test tube was heated and washed with benzyl alcohol. Thereafter, the washing solutions were combined, and titrated with a 1/1 OH KOH benzyl alcohol solution using phenol red as an indicator. Then, the acid value was determined by the following equation.

Acid value (eq / t) = (AB ) X fx 1 0 2 / SW

 However, A: KOH titer of this test 1/1 ON (ml)

 B: Blank test 1/1 OH KOH titer (ml) f: Factor of 1/1 OH KOH solution

 SW: Sample weight (g)

(4) Oxygen permeability coefficient ^{(m · mm / m 2 -} 24 hrs - atm): It is an indicator of gas barrier properties. Using an injection molding machine IS-100E manufactured by Toshiba Machine Co., a plate-like sheet having a length of 15 cm, a width of 10 cm and a thickness of l mm was injection molded to obtain a sample. The measurement was carried out under the conditions of 20 ° C. and 100% RH according to the Mocon method described in ASTM-D-395-81.

 (5) Transparency (%): The turbidity [haze] of the sample obtained in (4) was measured according to the method described in ASTM-D-1003, and the transparency was calculated by the following equation. Was converted to

 Transparency (%) = 100—turbidity (%)

(6) Impact resistance (J): 50% of the sample obtained in (4) was subjected to a falling weight impact test (load: 1 kg) according to the method described in JIS K-72-111. The breaking energy E ₅₀ (J) was determined.

(7) Heat resistance (〃m): For the sample obtained in (4), using a VI CAT softening point measuring device (HD TS3-MH) manufactured by Toyo Seiki Seisaku-sho, a load of lkg / mm ² , It was determined by measuring the penetration displacement (〃 m) of the loaded needle at 60 ° C when the temperature was raised at a temperature rate of 0.83 ° C / min.

 (8) Appearance: Using an injection molding machine IS-100E manufactured by Toshiba Machine Co., Ltd., 100 blood collection tubes with an outer diameter of 15 mm, a wall thickness of l mm, and a length of 100 mm were collected. Molded. At that time, the appearance was evaluated as 〇 when the number of spots on the blood collection tube main body was 1 or less, △ when 2 to 4 vesicles were observed, and X when 5 or more.

(9) Decompression retention (%): The internal pressure of the blood collection tube main body obtained in (8) was reduced to 300 mmHg, and the blood collection tube main body was sealed with a butyl rubber stopper. Then, utilizing this reduced pressure, sampling is performed using a perforated needle. Water was aspirated into the vessel body. The amount of suction when sucking immediately after sealing was set at 100%, and the storage rate (%) of the amount of suction when sucking after storage at 50 ° C for 3 months in a sealed state was evaluated. The value of this retention rate is an indicator of gas barrier integrity when polyester is used as the main body of a reduced-pressure blood collection tube, and the blood collection tube must be kept under reduced pressure so that blood can be normally collected. On the other hand, if the gas barrier property is low, air is sucked during storage, and the degree of decompression is reduced accordingly, making it impossible to collect the required amount of blood. Therefore, the larger the numerical value of the degree of reduced pressure retention, the higher the gas barrier property, and the required blood collection volume can be collected. Example 1

In producing polyester, first, an ET / EI copolymer was produced. In other words, in a 100-liter stainless steel reactor equipped with a stirrer, condenser and accumulator, 39.8 kg of terephthalic acid and 3.5 kg of isofluric acid as raw materials And 16.2 kg of ethylene glycol were added so that the molar ratio of terephthalic acid to isophthalic acid was terephthalic acid / isophthalic acid = 92/8. Further, 9.5 g of triethyl phosphate was added as a heat stabilizer and stirred. The mixture was reacted at a temperature of 210 ° C. and a pressure of ^2.5 kg / cm ² for ^2.5 hours, then reacted at normal pressure for 2 hours, and water was continuously distilled off.

26.6 g of antimony trioxide as a polycondensation catalyst and 9.5 g of triethyl phosphate as a heat stabilizer were added to the obtained reaction product, and the reaction temperature was raised to 260 ° C. Raise and maintain for 30 minutes under nitrogen atmosphere Was. Next, the nitrogen flow was stopped, the pressure was reduced to 0.3 mmHg over 1 hour, the state was maintained for 2.5 hours, and the mixture was allowed to react, and then discharged in a strand. After being cooled and solidified, it was cut into pellets, crystallized, and dried under reduced pressure at 150 ° C. for 8 hours to obtain resin pellets. This resin pellet has an intrinsic viscosity of 0.77, a glass transition temperature of 73 ° C, an acid value of 36 eq / t, an ethylene terephthalate unit of 92 mol%, and ethylene isophthalate. It contained 8 mol% of rate units. Hereinafter, this resin pellet is referred to as “pellet A”.

 Next, a blending ratio of a PET resin pellet having an intrinsic viscosity of 0.70 and an acid value of 28 eq / t (NEH203, manufactured by Unitika Ltd.) and the above resin pellet A was defined as a weight ratio. Then, the mixture was charged to 50/50 with a molding cycle at a temperature of 270 ° C. for 30 seconds.

 The ratio of ethylene terephthalate units / ethylene phthalate units (hereinafter referred to as “ET / EI”) is 96/4, the intrinsic viscosity is 0.70, and the glass transition temperature of the blend is 0.70. At 75 ° C, the acid value was 35 eq / t.

 The test sheet and the blood collection tube main body described above were prepared from this blend.

Table 1 shows the oxygen transmission coefficient, transparency, impact resistance, heat resistance, appearance of the blood collection tube main body, and the degree of vacuum retention of the obtained sheet. table 1

 PET: polyethylene terephthalate 28 eq / t), ΡΕΙ: polyethylene isophthalate (^ fffi 42 eq / t)

 ET / EI: Ethylene terephthalate unit Ethylene isophthalate unit

Α: ET / EI = 92 2 mol% / 8mol¾ copolymer weight ^: (麵 36 eq / t). C ET / EI = 35 mol¾ / 6 5moI copolymer (face 37 eq / t) B: ET / EI = 10 mol% / 9 Onto co-weight ^: (Sat 38 eq / t), D: Polyethylene terephthalate (レ ー ト 35 eq / t)

Example 2

In producing the polyester, first, an ET / EI copolymer having a different blending ratio from that of Example 1 was produced. That is, in a stainless steel reactor with an internal volume of 100 liters equipped with a stirrer, a capacitor and an accumulator, 4.3 kg of terephthalic acid and 38.9 kg of isofluric acid as raw materials And 16.2 kg of ethylene glycol so that the molar ratio of terephthalic acid to isofluric acid is terephthalic acid / isofluric acid = 10/90 I made it. Further, 9.5 g of triethyl phosphate was added as a heat stabilizer, and the mixture was stirred. The mixture was reacted at a temperature of 210 ° C. and a pressure of ^2.5 kg / cm ² for 2.5 hours, then reacted at normal pressure for 2 hours, and water was continuously distilled off.

 To the obtained reaction product, 26.6 g of antimony trioxide as a polycondensation catalyst and 9.5 g of triethyl phosphate as a heat stabilizer were added, and the reaction temperature was raised to 260 ° C. C and maintained under a nitrogen atmosphere for 30 minutes. Next, the nitrogen flow was stopped, the pressure was reduced to 0.3 mmHg over 1 hour, and the reaction was maintained for 3 hours. Thereafter, the mixture was discharged in a strand, cooled, solidified, cut into pellets, and dried under reduced pressure at 60 ° C. for 5 days to obtain a resin pellet. This resin pellet has an intrinsic viscosity of 0.81, a glass transition temperature of 62 ° C, an acid value of 38 eq / t, an ethylene terephthalate unit of 10 mol%, and an ethylene isophthalate. It contained 90 mol% of units. Hereinafter, this resin pellet is referred to as “pellet B”.

Next, the PET resin pellet (NEH2030 manufactured by Unitichika) and the above resin pellet B were mixed in a weight ratio of 9 1/9. And molded in a molding cycle at a temperature of 270 ° C. for 30 seconds.

 The blend had a molar ratio of ET / EI of 92/8, an intrinsic viscosity of 0.68, a glass transition temperature of 74 ° C, and an acid value of 31 eq / t. The test sheet and the blood collection tube main body described above were prepared from this blend.

 Table 1 shows the physical properties of the obtained sheet and the blood collection tube body. Example 3

 Polyester was composed of resin pellet A only. The molding temperature was 260 ° C., and the ratio of ET / EI of the resin pellet A was 92/8 in molar ratio. Using this resin pellet A, a sheet and a blood collection tube body were prepared at a temperature of 260 ° C.

 Table 1 shows the physical properties of the obtained sheet and the blood collection tube body. Example 4

 PET resin pellets (NEH203, manufactured by Unitika) and resin pellets B were charged at a weight ratio of 88/12, and the temperature was set at 270. C, The molding blend was performed in a molding cycle of 30 seconds. The molar ratio of ET / EI of the blend was 89/11 to prepare the sheet and the blood collection tube body.

 Table 1 shows the physical properties of the obtained sheet and the blood collection tube body. Example 5

In producing polyester, first, Example 1 and Example 2 An ET / EI copolymer having a mixing ratio different from that of the ET / EI copolymer was produced. Specifically, in a 100-liter stainless steel reactor equipped with a stirrer, condenser and accumulator, the raw materials terephthalic acid 15.1 kg and isofluric acid 28.1 kg and 16.2 kg of ethylene glycol so that the molar ratio of terephthalic acid to isofluric acid is terephthalic acid / isophthalic acid = 35/65 . Further, 9.5 g of triethyl phosphate as a heat stabilizer was added and stirred. The mixture was reacted at a temperature of 210 ° C. and a pressure of ^2.5 kg / cm ² for 2.5 hours, then reacted at normal pressure for 2 hours, and water was continuously distilled off.

 26.6 g of antimony trioxide as a polycondensation catalyst and 9.5 g of triethyl phosphate as a heat stabilizer were added to the obtained reaction product, and the reaction temperature was raised to 260 ° C. And maintained for 30 minutes under a nitrogen atmosphere. Next, the nitrogen flow was stopped, the pressure was reduced to 0.3 mmHg over 1 hour, and the reaction was maintained for 3 hours. After that, it was dispensed in a strand, cooled, solidified, cut into pellets, and dried under reduced pressure at 60 ° C for 5 days to obtain resin pellets. This resin pellet has an intrinsic viscosity of 0.82, a glass transition temperature of 64 ° C, an acid value of 37 eq / t, an ethylene terephthalate unit of 35 mol%, and an ethylene isophthalate unit. 65 mol%. Hereinafter, this resin pellet is referred to as “pellet C”.

Next, a PET resin pellet (NEH2030 manufactured by Unitika) and the above resin pellet C were charged so that the mixing ratio was 77/23 by weight, and the temperature was set at 270 °. C, The molding blend was performed in a molding cycle of 30 seconds. Then, the ratio of ET / EI of the blended product is 85/1 in molar ratio. As 5, the sheet and the blood collection tube body were prepared.

 Table 1 shows the physical properties of the obtained sheet and the blood collection tube main body. Example 6

 PET resin pellets (NEH2030 manufactured by Unitika) and resin pellets C were charged so that the mixing ratio was 69/31 by weight, and the temperature was set at 270 ° (3 The molding was performed in a molding cycle of 0 seconds, and the sheet and the blood collection tube main body were prepared by setting the molar ratio of ET / EI of the blended product to 80/20.

 Table 1 shows the physical properties of the obtained sheet and the blood collection tube body. Example 7

 The PET resin pellets (NEH2030 manufactured by Unitika) and the resin pellets B were charged so that the blending ratio was 72/28 by weight, and the temperature was set at 270 ° ( The molding was performed in a molding cycle of 30 seconds, and the other conditions were the same as in Example 2 except that the ET / EI ratio of the blend was 75/25 in molar ratio, and the sheet and blood collection tube were used. The physical properties of the obtained sheet and the main body of the blood collection tube are shown in Table 1. Example 8

A PET resin pellet (NEH 203, manufactured by Unitika) and a resin pellet B were charged so that the mixing ratio was 45/55 by weight, and the temperature was set at 26 ° C and 30 ° C. The molding blend was performed in a molding cycle of seconds. Other than that, the same procedure as in Example 2 was carried out except that the ET / EI ratio of the blend was 50/50 in molar ratio to prepare a sheet and a blood collection tube body. Table 1 shows the physical properties of the obtained sheet and the main blood collection tube. In the polyesters of Examples 1 to 8, the blending ratio of ethylene terephthalate unit and ethylene ethylene phthalate unit, the acid value of the polyester, needle penetration displacement by VICAT softening point measuring device, oxygen permeation coefficient Since these were within the scope of the present invention, all of them were excellent in transparency and appearance, impact resistance and heat resistance, and could be suitably used as a blood collection tube main body. In addition, since polyester was made from ethylene terephthalate units and ethylene isophthalate units, it was possible to obtain products that could be made at low cost. Furthermore, in producing the copolymer, instead of producing PEI and blending it with PET, the ET / EI copolymer is used, so it is difficult to produce pure PEI. Normally, it takes one to two weeks for drying. In the present invention, this can be shortened to about five days, and the productivity is improved.

 Further, in Examples 4 to 8, the mixing ratio of the ethylene terephthalate unit and the ethylene isophthalate unit was further optimized, so that the oxygen permeability coefficient was reduced and the gas barrier uniformity was improved.

In Example 3, although the polyester was formed only of the ET / EI copolymer, the pellet was crystallized, so that the pellet could be dried at a high temperature in a short time. As a result, no white spots were formed on the product, and the product was excellent in transparency and impact resistance, and also excellent in gas barrier properties. Although the heat resistance was the same as the ET / EI composition, it was slightly inferior to that of Example 2 to which the molding blend method was applied, but satisfied predetermined requirements. Comparative Example 1

 A sheet and a blood collection tube were prepared at a molding temperature of 270 ° C. using only a polyester material as a PET resin pellet (NEH230, manufactured by Unitika).

 Table 1 shows the physical properties of the obtained sheet and blood collection tube. Comparative Example 2

 PET resin pellets (NEH 230, manufactured by Unitichika) and resin pellets B were charged so that the mixing ratio was 23/77 in weight ratio, and the temperature was set at 270 ° C. The molding blend was performed in a molding cycle of 30 seconds, and the resulting polyester had a molar ratio of ET / EI = 30/70 in terms of the molar ratio of ET / EI = 30/70, which was higher than the upper limit of the present invention. I tried to increase it. Other than that, the sheet and the blood collection tube main body were prepared in the same manner as in Example 2.

 Table 1 shows the physical properties of the obtained sheet and the blood collection tube body. Comparative Example 3

 Polyester was composed of resin pellet B only. The ratio of ET / EI of resin pellet B was 10/90 in molar ratio. Using this resin pellet B, a sheet and a blood collection tube body were produced at a temperature of 220 ° C.

 Table 1 shows the physical properties of the obtained sheet and the blood collection tube main body. Comparative Example 4

Inside the stirrer, condenser and accumulator In a 100 liter stainless steel reactor, 43.2 kg of the raw materials isophthalic acid, 16.2 kg of ethylene glycol, and 9.5 ml of triethyl phosphate as a heat stabilizer g and stirred. Their to, the mixture temperature 2 1 0 ° C, after 2 was allowed to react for 5 hours at a pressure 2. 5 k gZ cm ^z, reacted for 2 hours at normal pressure, water was distilled off continuously.

 26.6 g of antimony trioxide as a polycondensation catalyst and 9.5 g of triethyl phosphate as a heat stabilizer were added to the reaction product in the obtained reactor, and the reaction temperature was increased to 26 The temperature was raised to 0 ° C and maintained for 30 minutes under a nitrogen atmosphere. Next, the nitrogen flow was stopped, the pressure was reduced to 0.3 mmHg over 1 hour, and the reaction was maintained for 3.5 hours. Thereafter, the mixture was discharged in a strand, cooled, solidified, cut into pellets, and dried under reduced pressure at 50 ° C. for 7 days to obtain a resin pellet. This PEI resin pellet had an intrinsic viscosity of 0.83, a glass transition temperature of 58 ° C, and an acid value of 46 eq / t.

 Using this PEI resin pellet, the temperature was 210. A sheet and a blood collection tube body were prepared with C.

 Table 1 shows the physical properties of the obtained sheet and the blood collection tube main body. Comparative Example 5

A PET resin pellet with an intrinsic viscosity of 0.70 and an acid value of 28 eq / t (NEH203, manufactured by Unitika) and a resin pellet B (acid value of 38 eq / t) It was blended so that the blending ratio was 7 2/28 by weight, and it was extruded at a temperature of 295 ° C using a twin screw extruder PCM-30 manufactured by Ikekai Tekko Co., Ltd. to pelletize. . Using this pellet, a molding temperature of 270 ° C A sheet and a blood collection tube main body were prepared by the method described above. The blend had a molar ratio of ET / EI of 75/25.

 Table 1 shows the physical properties of the obtained sheet and the blood collection tube body. Comparative Example 6

 PET resin pellet with intrinsic viscosity 0.72 and acid value 35 eq / t (NES-204, manufactured by Unitika Ltd .; hereinafter, this resin pellet is referred to as “pellet D”) and resin pellet B (acid value 38 eq / t). Then, the blending ratio of the pellets P and B was adjusted so that the weight ratio was 72/28, and the molding blend was performed at a molding temperature of 270 ° C for 30 seconds. Other than that, the sheet and the blood collection tube main body were produced in the same manner as in Example 7, except that the molar ratio of ET / EI of the preform was 75/25.

Table 1 shows the physical properties of the obtained sheet and the blood collection tube main body. In Comparative Example 1, since only PET was used, the transparency, impact resistance, heat resistance and appearance were excellent, but the oxygen permeability coefficient was higher than 2.8 m-mm / m ² · 24 hrs · atm. Therefore, the degree of reduced pressure retention was reduced, and it did not have a gas barrier property suitable for use as a blood collection tube.

 Comparative Example 2 was excellent in gas barrier properties because the blending ratio of the ethylene isophthalate unit was higher than the range of the present invention, but was inferior in transparency, appearance, impact resistance and heat resistance. Was.

In Comparative Example 3, since only the ET / EI copolymer was used, and the blending ratio of the ethylene glycol units was higher than the range of the present invention, Transparency: Impact resistance and heat resistance decreased, and white spots appeared on molded products, resulting in poor appearance. In addition, drying was time-consuming at the time of preparing the copolymer and at the time of molding the sheet and the blood collection tube main body, resulting in poor productivity.

 In Comparative Example 4, since only PEI was used, as in Comparative Example 3, transparency and appearance were inferior in impact resistance and heat resistance, and drying in PEI production and molding took time, and productivity was further increased. Dropped.

 In Comparative Example 5, since the pellet was molded after being melt-blended, the acid value of the sheet became higher than the range of the present invention. For this reason, the gas barrier properties, transparency, and impact resistance were excellent, but the heat resistance was poor.

 In Comparative Example 6, since the acid value of PET was higher than the range of the present invention, it was excellent in gas barrier property, transparency, and impact resistance, but was slightly inferior in heat resistance. Industrial applicability

 As described above, the polyester of the present invention is suitable for a gas barrier uniform container. The polyester of the present invention can be particularly preferably used as a blood collection tube main body.

Claims

The scope of the claims 1. Polyester consisting of 99 to 50 mol% of ethylene terephthalate units and 1 to 50 mol% of ethylene isocyanate units, and having an acid value of 40 eq / t or less. Ri, VI CAT using a softening point measuring apparatus, a sample having a thickness of l mm, load LKG / mm ^z, heating rate 0.8 3. Penetration displacement of the needle with a load at 60 ° C when the temperature is raised at C / min is 50〃m or less, and the oxygen permeability coefficient is 2.8 m £-mm / m ² 24 hrs · atm or less. 2. A method for producing the polyester of claim 1, comprising a polyethylene terephthalate having an acid value of 3 Oeq / t or less and an ethylene terephthalate having an acid value of 4 Oeq / t or less. It is characterized by molding and molding an ethylene isomer late copolymer. 3. A gasparous container made of claim 1 polyester. 4. The gas barrier container of claim 3, which is a blood collection tube.