JP2011132394A - Biaxially stretched hollow container - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a biaxially stretched hollow container which excels in a gas barrier property, and consists of a polyester resin composition which has improved transparency. <P>SOLUTION: The biaxially stretched hollow container comprises molding a polyester resin composition (C) which includes: a copolyester resin (A) which has a sulfonic acid metal salt group, and mainly consists of an aromatic dicarboxylic acid unit and an aliphatic diol unit; and a polyamide resin (B) which consists of a diamine unit including a meta-xylylene diamine unit of at least 70 mol% and a dicarboxylic acid unit including a 4-20C α, ω-straight chain aliphatic dicarboxylic acid unit of at least 70 mol%. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a biaxially stretched hollow container comprising a resin composition comprising a polyester resin and a polyamide resin. Specifically, the present invention relates to a biaxially stretched hollow container made of a polyester resin composition capable of improving the transparency which has been a problem in the past while improving the gas barrier properties that were insufficient with only polyester.

  Polymers obtained by using aromatic dicarboxylic acid and aliphatic diol compounds as monomers, for example, polyester resins represented by polyethylene terephthalate resin (PET), have transparency, mechanical performance, melt stability, flavor retention, It is characterized by excellent recyclability. Therefore, aromatic polyester resins are widely used for various packaging materials such as films, sheets, and hollow containers. However, since the polyester resin does not necessarily have sufficient gas barrier properties against oxygen, carbon dioxide gas, etc., the range of use of the packaging container made of the polyester resin has been limited. As a method for improving the gas barrier property of the polyester resin, aluminum oxide or silicon oxide is vapor-deposited on a molded body made of a polyester resin or a packaging container, or a molded body made of a polyester resin with a gas barrier performance higher than that of the polyester resin. Although there are means such as coating or laminating on packaging containers, etc., there are problems such as requiring complicated manufacturing processes and impaired recyclability and mechanical performance, so the range of use is limited Met.

  As a means for improving the gas barrier property of the polyester resin while solving the above problems, there is a method in which a thermoplastic resin having a high gas barrier property is melt mixed with the polyester resin. One of the resins having high gas barrier properties is ethylene-vinyl alcohol copolymer resin. However, ethylene-vinyl alcohol copolymer resin is poor in compatibility with polyester resin due to the characteristics of its molecular structure. The resin composition formed by mixing turbidity has a drawback that it impairs the transparency that is characteristic of polyester resins. Further, at the optimum processing temperature in the polyester resin, the ethylene-vinyl alcohol copolymer resin has a tendency to rapidly deteriorate due to heat, so that there is a problem that the processing stability of the polyester resin is impaired.

  Examples of the gas barrier resin other than the ethylene-vinyl alcohol copolymer resin include polyamide resins represented by nylon 6, nylon 6, 6, and the like, and in particular, a diamine component mainly composed of metaxylylenediamine and adipic acid. Polymetaxylylene adipamide obtained by polymerizing a carboxylic acid component having a main component of is a polyamide resin excellent in gas barrier properties and is suitable. Polymetaxylene adipamide has a high gas barrier property compared to other polyamide resins, and has a glass transition temperature, melting point, and crystallinity similar to those of polyethylene terephthalate resins widely used among polyester resins. Therefore, it can be said that polymetaxylene adipamide is a very suitable resin as a material for improving the gas barrier property of the polyester resin.

  So far, a hollow molded article having excellent gas barrier properties in which a polyamide resin is contained in a polyester resin whose main repeating unit is ethylene terephthalate has been proposed, but the present invention simply proposed improvement of gas barrier properties by using a polyamide resin. However, there is no description regarding improvement of color tone and transparency (see Patent Document 1). Further, as a method for improving transparency, a method using a sulfonic acid metal as a copolymer component of a polyester resin (Patent Document 2) and a method using a low molecular weight polyamide resin (Patent Document 3) are disclosed. In the stretched hollow container, the transparency in the unstretched part is good, but the effect of improving the haze is insufficient in the stretched part of the trunk.

JP 58-160344 A JP-A-2-135259 JP-T-2003-527457

  An object of the present invention is to provide a biaxially stretched hollow container made of a polyester resin composition that solves the above-described problems, has excellent gas barrier properties, and has improved transparency.

  As a result of intensive studies on the solution of the above problems, the present inventors have obtained a specific polyester in obtaining a biaxially stretched hollow container using a polyester resin composition obtained by mixing a polyester resin and a metaxylylene group-containing polyamide resin. It has been found that the above problems can be solved by using a resin and a metaxylylene group-containing polyamide resin having a specific molecular weight, and the present invention has been completed.

That is, the present invention relates to a copolymer polyester resin (A) 80 to 99% by weight, a diamine unit containing 70% by mole or more of metaxylylenediamine units, and an α, ω-linear aliphatic dicarboxylic acid having 4 to 20 carbon atoms. Biaxial molded polyester resin composition (C) comprising 1 to 20% by weight (%) of a polyamide resin (B) comprising a dicarboxylic acid unit containing 70 mol% or more of units (total of 100% by weight). In the stretched hollow container, the copolymerized polyester resin (A) comprises 70 mol% or more of an aromatic dicarboxylic acid, 70 mol% or more of a diol structural unit, an aliphatic diol, and dicarboxylic acid. 0.01-5 mol% of the acid structural unit has a sulfonic acid metal base, and the number average molecular weight of the polyamide resin (B) is 6000-15000. To a biaxially stretched hollow container.

According to the present invention, a parison and biaxially stretched hollow container made of a polyester composition having excellent gas barrier properties and improved transparency can be obtained.

  The present invention is described in detail below. The polyester resin composition (C) constituting the parison or biaxially stretched hollow container used in the present invention comprises a copolyester resin (A) and a polyamide resin (B).

  In the copolymerized polyester resin (A) constituting the biaxially stretched hollow container of the present invention, the aromatic dicarboxylic acid unit is 70 mol% or more, preferably 80 mol% or more, more preferably 90 mol% or more of the dicarboxylic acid structural unit. A polyester resin in which 70 mol% or more, preferably 80 mol% or more, more preferably 90 mol% or more of the diol structural unit is composed of an aliphatic diol unit. By increasing the proportion of the aromatic dicarboxylic acid unit or the aliphatic diol unit, the crystallinity of the copolyester resin (A) increases, and drying before use becomes easy. In the copolymerized polyester resin (A), 0.01 to 5 mol% of the dicarboxylic acid structural unit has a sulfonic acid metal base. As will be described later, in order to obtain a polyester resin (A) having a sulfonic acid metal base, it is necessary to copolymerize two or more kinds of dicarboxylic acid components. The sulfonic acid metal base is essential for improving compatibility with the polyamide resin (B), and the biaxially stretched hollow container obtained from the polyester resin composition (C) by finely dispersing the polyamide resin (B). This significantly improves the transparency. The ratio of the sulfonic acid metal base in the polyester resin (A) is preferably 0.01 to 5 mol%, more preferably 0.03 to 2 mol%, still more preferably 0.06 to 0.06 mol% of the dicarboxylic acid structural unit. 1.0 mol%. By setting it as this range, compatibility can be improved, without impairing the characteristic of a polyester resin (A). Two or more polyester resins (A) may be used in combination.

  Examples of the aromatic dicarboxylic acid include benzene dicarboxylic acids such as terephthalic acid and isophthalic acid; naphthalenedicarboxylic acids such as 2,6-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid and 2,7-naphthalenedicarboxylic acid; Examples thereof include biphenyl dicarboxylic acids such as' -biphenyl dicarboxylic acid and 3,4'-biphenyl dicarboxylic acid, and ester-forming derivatives thereof. Among these, it is preferable to use terephthalic acid. When terephthalic acid and other aromatic dicarboxylic acid are used in combination, isophthalic acid is preferably used. When isophthalic acid is used in combination, the proportion is 1 to 10 mol%, preferably 1 to 8 mol%, more preferably 1 to 6 mol% of the dicarboxylic acid component. In this range, the polyester resin copolymerized with isophthalic acid has a low crystallization rate and can improve moldability. Furthermore, aliphatic dicarboxylic acids such as adipic acid, azelaic acid, and sebacic acid, and monocarboxylic acids such as benzoic acid, propionic acid, and butyric acid can be used within the range not impairing the object of the present invention.

Examples of the aliphatic diol include ethylene glycol, 1,3-propylene diol, 1,4-butanediol, 1,4-cyclohexanedimethanol, 1,6-hexanediol, and ester-forming derivatives thereof. Among these, it is preferable to use ethylene glycol. Furthermore, alcohols such as butyl alcohol, hexyl alcohol and octyl alcohol, and polyhydric alcohols such as trimethylolpropane, glycerin and pentaerythritol can be used within the range not impairing the object of the present invention.

  In order to obtain a polyester resin (A) having a sulfonic acid metal base, the metal ions of the sulfonic acid metal salt include alkali metal ions such as lithium, sodium and potassium; alkaline earth metal ions such as magnesium and calcium; zinc and the like It is preferable to copolymerize a dicarboxylic acid component in which a transition metal ion and sulfosulfonic acid, sulfoterephthalic acid, sulfoisophthalic acid, 4-sulfonaphthalene-2,7-dicarboxylic acid and their derivatives are combined as a dicarboxylic acid component. . As the dicarboxylic acid compound, sodium 5-sulfoisophthalate, lithium 5-sulfoisophthalate and zinc 5-sulfoisophthalate are preferable.

  For the production of the polyester resin (A), a direct esterification method or a transesterification method, which are known methods, can be applied. Polycondensation catalysts used in the production of the polyester resin (A) include known antimony compounds such as antimony trioxide and antimony pentoxide, germanium compounds such as germanium oxide, titanium compounds such as titanium acetate, and aluminum compounds such as aluminum chloride. However, the present invention is not limited to these. Moreover, in order to raise molecular weight as needed, you may carry out solid-phase polymerization by a conventionally well-known method.

  The polyester resin (A) used in the present invention preferably has a moisture content in the polymer before use of 200 ppm or less, preferably 100 ppm or less, more preferably 50 ppm or less. In this case, the polyester resin may be dried to obtain the above moisture content. When the moisture content is within the above range, the polyester does not hydrolyze in the melt mixing step and the molecular weight does not extremely decrease.

The intrinsic viscosity (value measured at 25 ° C. in a mixed solvent of phenol / 1,1,2,2-tetrachloroethane = 60/40 weight ratio) of the polyester resin (A) used in the present invention is 0.5 to 2.0 dl. / G, preferably 0.6 to 1.5 dl / g. When the intrinsic viscosity is within the above range, the polyamide resin (B) is finely dispersed in the polyester resin composition (C) obtained by using this, whereby the transparency is improved, and the biaxially stretched hollow container is The mechanical properties required for the structure can be expressed.

Next, the polyamide resin (B) will be described.
The polyamide resin (B) in the present invention imparts an effect of improving the gas barrier properties of the polyester resin (A). As a diamine unit in a polyamide resin (B), a metaxylylene diamine unit is 70 mol% or more (100 mol% is included), Preferably it is 80 mol% or more, More preferably, it contains 90 mol% or more. The gas barrier property of the polyamide resin (B) obtained by using a metaxylylenediamine unit as a main component of a diamine unit can be improved efficiently. Examples of diamines that can be used in addition to metaxylylenediamine include paraxylylenediamine, 1,3-bis (aminomethyl) cyclohexane, 1,4-bis (aminomethyl) cyclohexane, tetramethylenediamine, hexamethylenediamine, and nonanemethylenediamine. , 2-methyl-1,5-pentanediamine and the like, but are not limited thereto.

  As a dicarboxylic acid unit in the polyamide resin (B), an α, ω-aliphatic dicarboxylic acid unit is contained in an amount of 70 mol% or more (including 100 mol%), preferably 75 mol% or more, and more preferably 80 mol% or more. By setting the content of the α, ω-aliphatic dicarboxylic acid unit to 70 mol% or more, it is possible to avoid a decrease in gas barrier properties and an excessive decrease in crystallinity. Examples of the α, ω-aliphatic dicarboxylic acid include suberic acid, adipic acid, azelaic acid, sebacic acid and the like, and adipic acid is preferably used. Examples of dicarboxylic acid units other than α, ω-aliphatic dicarboxylic acids include alicyclic dicarboxylic acids such as 1,3-cyclohexanedicarboxylic acid and 1,4-cyclohexanedicarboxylic acid, terephthalic acid, isophthalic acid, orthophthalic acid, and xylylene diene. Examples thereof include aromatic dicarboxylic acids such as carboxylic acid and naphthalenedicarboxylic acid, but are not limited thereto. In addition to the diamine unit and the dicarboxylic acid unit, as a unit constituting the polyamide resin (B), lactams such as ε-caprolactam and laurolactam, aminocaproic acid, and aminoundecanoic acid as long as the effects of the present invention are not impaired. Aliphatic aminocarboxylic acids such as para-aminomethylbenzoic acid and the like can also be used as copolymerized units.

  The polyamide resin (B) is produced by a melt polycondensation (melt polymerization) method. As the melt polymerization method, for example, there is a method in which a nylon salt composed of diamine and dicarboxylic acid is heated in the presence of water under pressure and polymerized in a molten state while removing added water and condensed water. It can also be produced by a method in which diamine is directly added to a molten dicarboxylic acid and polycondensed. In this case, the polycondensation proceeds while raising the temperature of the reaction system so that the reaction temperature does not fall below the melting point of the generated oligoamide and polyamide. The polyamide resin (B) obtained by melt polymerization is once taken out, pelletized, and dried before use.

  In the polycondensation system of the polyamide resin (B), a phosphorus atom-containing compound may be added in order to obtain an effect of promoting an amidation reaction and an effect of preventing coloring during polycondensation. Examples of phosphorus atom-containing compounds include dimethylphosphinic acid, phenylmethylphosphinic acid, hypophosphorous acid, sodium hypophosphite, potassium hypophosphite, lithium hypophosphite, ethyl hypophosphite, phenylphosphonous acid, Sodium phenylphosphonite, potassium phenylphosphonate, lithium phenylphosphonate, ethyl phenylphosphonite, phenylphosphonic acid, ethylphosphonic acid, sodium phenylphosphonate, potassium phenylphosphonate, lithium phenylphosphonate, diethyl phenylphosphonate, Examples thereof include sodium ethylphosphonate, potassium ethylphosphonate, phosphorous acid, sodium hydrogen phosphite, sodium phosphite, triethyl phosphite, triphenyl phosphite, pyrophosphorous acid, etc. Na phosphite Hypophosphite metal salts such as lithium, potassium hypophosphite, lithium hypophosphite and the like are preferably used because they have a high effect of promoting amidation reaction and are excellent in anti-coloring effect, especially sodium hypophosphite. Is preferred. The phosphorus atom-containing compounds that can be used in the present invention are not limited to these compounds.

The amount of the phosphorus atom-containing compound added to the polycondensation system of the polyamide resin (B) is preferably 1 to 200 ppm or less, more preferably 5 to 190 ppm in terms of the phosphorus atom concentration in the polyamide resin (B). More preferred is 160 ppm. By setting the amount of the phosphorus atom-containing compound within the above range, the polyamide resin is prevented from being colored during polycondensation, and the polyester resin is melt-mixed with a polyester resin produced using an antimony catalyst. Blackening due to the reduction of the antimony catalyst slightly remaining therein is prevented.

  In the polycondensation system of the polyamide resin (B), it is preferable to add an alkali metal compound in combination with the phosphorus atom-containing compound. To prevent coloring of the polyamide during polycondensation, a sufficient amount of phosphorus atom-containing compound needs to be present, but in some cases it may promote gelation of the polyamide, so the amidation reaction rate is adjusted. Therefore, it is preferable to coexist an alkali metal compound or an alkaline earth metal compound. For example, lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, cerium hydroxide, magnesium hydroxide, calcium hydroxide, barium hydroxide and other alkali metal / alkaline earth metal hydroxides, lithium acetate, Examples include sodium acetate, potassium acetate, rubidium acetate, cesium acetate, magnesium acetate, calcium acetate, barium acetate, and other alkali metal / alkaline earth metal acetates, etc., but these compounds can be used without limitation. .

  When an alkali metal compound is added to the polycondensation system of the polyamide resin (B), the value obtained by dividing the number of moles of the compound by the number of moles of the phosphorus atom-containing compound (A) is 0.5 to 2.0. Preferably, it is 0.6 to 1.8, more preferably 0.7 to 1.5. By setting it as the above-mentioned range, it becomes possible to suppress the formation of gel while obtaining the amidation reaction promoting effect by the phosphorus atom-containing compound. The polyamide resin (B) includes a lubricant, a matting agent, a heat stabilizer, a weather stabilizer, an ultraviolet absorber, and a nucleating agent as long as the effects of the present invention are not impaired in addition to the phosphorus atom-containing compound and alkali metal compound described above. Plasticizers, flame retardants, antistatic agents, anti-coloring agents, anti-gelling agents, and other additives can also be added.

  The moisture content of the polyamide resin (B) is preferably 0.15% by weight or less, more preferably 0.1% by weight or less, and still more preferably 0.08% by weight or less. In this case, the polyamide resin may be dried to obtain the above moisture content. By controlling the moisture content of the polyamide resin (B) within the above range, the hydrolysis of the polyester resin (A) caused by the moisture generated from the polyamide resin (B) during melt mixing with the polyester resin (A) is suppressed. Can do. When drying a polyamide resin (B), it can carry out by a well-known method. For example, the polyamide resin (B) is charged in a heatable tumbler (rotary vacuum tank) equipped with a vacuum pump or in a vacuum dryer, and dried at a temperature below the melting point of the polymer, preferably below 160 ° C. under reduced pressure. However, it is not limited to this.

  The number average molecular weight of the polyamide resin (B) is preferably from 6000 to 15000, more preferably from 7000 to 14000, still more preferably from 8000 to 13000. By setting the number average molecular weight of the polyamide resin (B) within the above range, the polyamide resin (B) is finely dispersed in the sea of the polyester resin (A) in the biaxially stretched hollow container made of the polyester resin composition (C). By doing so, the transparency of the container becomes excellent.

  The blending ratio of the polyester resin (A) and the polyamide resin (B) in the polyester resin composition (C) is 80 to 99% by weight of the polyester resin (A) and 1 to 20% by weight (total of the weight%) of the polyamide resin (B). Is preferably 100% by weight), more preferably 85 to 99% by weight of the polyester resin (A), 1 to 15% by weight of the polyamide resin (B), and still more preferably 90 to 98% by weight of the polyester resin (A). B) 2 to 10% by weight. By setting the content of the polyamide resin within the above range, the gas barrier property can be improved without impairing the transparency of the biaxially stretched hollow container.

  Further, the polyester resin composition (C) used in the present invention includes other resins such as polyethylene terephthalate resin, polyethylene naphthalate resin, and polybutylene terephthalate resin as long as the effects of the present invention are not impaired. Resin, polyamide resin such as nylon 6, nylon-6IT and nylon 66, polyolefin such as polyethylene and polypropylene may be blended. Or recycled resins, such as those molten mixtures, may be mix | blended. Also intended to prevent gelation of pigments, dyes, lubricants, matting agents, heat stabilizers, weathering stabilizers, UV absorbers, fluorescent brighteners, nucleating agents, plasticizers, flame retardants, antistatic agents, and polyamide resins Additives such as alkaline compounds can also be added.

As a method for producing the polyester resin composition (C), it is mixed by a conventionally known method. For example, polyester resin (A) and polyamide resin (B) are dry blended with a tumbler, V-type blender, Henschel mixer, etc., and the dry blended mixture is once with a single screw extruder, twin screw extruder, kneader, etc. Examples include a method of drying and crystallization by melting and mixing the above, and further heating the molten mixture under a high vacuum or an inert gas atmosphere as necessary.

  In the biaxially stretched hollow container of the present invention, the polyester resin composition (C) is injected from an injection cylinder through a mold hot runner into a mold cavity of an injection molding machine to obtain a parison, and the parison is further biaxially formed. It can be obtained by stretch blow molding.

The injection molding conditions for obtaining a parison that is a precursor of the biaxially stretched hollow container of the present invention preferably satisfy the following conditions (a) to (e).
(A) Resin temperature: 260-290 ° C
(B) Screw back pressure: 2.5 to 5.0 MPa
(C) Screw rotation speed: 80 to 250 rpm
(D) Injection speed: 80 to 180 cc / sec
(E) Mold temperature: 10-25 ° C

  The injection condition is a value shown on the meter of the injection molding apparatus. When no instrument is installed in the injection molding apparatus, it can be calculated from the specifications of the injection molding machine and the set values at the time of injection molding.

  The dispersion particle size of the polyamide resin (B) in the polyester resin composition (C) is mainly affected by the conditions during measurement and injection. That is, the kneading of the molten resin proceeds and the dispersed particle size decreases by increasing the back pressure of the screw during measurement and increasing the rotational speed of the screw. Also, by increasing the injection speed, the molten resin is sheared and the dispersed particle size is reduced. Therefore, by forming the parison within the above-mentioned range, the dispersed particle diameter of the polyamide resin (B) in the polyester resin composition (C) is small and the dispersion of the dispersed particle diameter is reduced, so that biaxially stretched hollow The transparency of the container is improved. The injection conditions (a) to (e) can be appropriately selected according to the melt viscosity of the resin to be molded.

  When the resin temperature is 260 to 290 ° C., it is possible to prevent the unmelted material from being deposited in the parison or the transparency from being lowered. Moreover, yellowing of a parison can be suppressed and deterioration of the external appearance of a biaxially stretched hollow container can be prevented. When the mold temperature is 10 to 25 ° C., it is possible to prevent the appearance from deteriorating due to the crystallization of the parison. Moreover, the transparency of the biaxially stretched hollow container is improved.

  As a method for forming the obtained parison into a biaxially stretched hollow container, a general blow molding machine may be used. For example, using a biaxial stretch blow molding machine, heat for about 15 seconds to 4 minutes with a far-infrared heater to bring the surface temperature of the parison to 90 to 120 ° C., blow with a stretch rod and a pressure of 0.5 to 3.5 MPa. Obtained by molding.

  The biaxially stretched hollow container of the present invention is excellent in gas barrier properties and excellent in transparency, for example, water, juice, fruit juice, tea, tea, coffee, health drinks, jelly drinks and other beverages, sake Alcoholic beverages such as shochu, wine, beer, liqueur, seasoning liquid, sauce, soy sauce, dressing, liquid soup, various seasonings such as mirin, vinegar, mayonnaise, ketchup, sauce, liquid and paste pharmaceuticals, lotion, Various articles such as cosmetic cream, cosmetic emulsion, hair conditioner, hair dye, shampoo, soap and detergent can be stored.

  EXAMPLES The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to these examples. The materials used in the examples, the analysis / measurement methods, and the biaxially stretched hollow container manufacturing methods are described below.

1. Materials The following materials were used in Examples and Comparative Examples.
(1) Polyester 1
Isovisic acid copolymerized PET resin (trade name: Polyshield 2400, intrinsic viscosity = 0.8 dl / g, melting point = 242 ° C., isophthalic acid 3.3 mol% copolymerization, amount of sodium 5-sulfonate in dicarboxylic acid component = 0.09 mol%). In use, a product dehydrated in a dehumidifying dryer at 150 ° C. for 6 hours was used.
(2) Polyester 2
Invista isophthalic acid copolymerized PET resin (trade name: Polyclear 1101E, intrinsic viscosity = 0.8 dl / g, melting point = 244 ° C., isophthalic acid 2.8 mol% copolymer, no sulfonic acid metal base) used. In use, a product dehydrated in a dehumidifying dryer at 150 ° C. for 6 hours was used.
(3) Polyamide 1
A 50-liter reactor equipped with a stirrer, a condenser, a cooler, a thermometer, a dripping tank, and a nitrogen gas introduction tube was charged with 15 kg of adipic acid and 13 g of sodium hypophosphite monohydrate, and sufficiently substituted with nitrogen. Then, the temperature was raised to 180 ° C. under a small amount of nitrogen stream, and adipic acid was uniformly melted. Then, 13.7 kg of metaxylylenediamine was required for 170 minutes while stirring the system. And dripped. During this time, the internal temperature was continuously raised to 245 ° C. Water generated by polycondensation was removed from the system through a condenser and a cooler. After completion of the dropwise addition of metaxylylenediamine, the internal temperature was further raised to 260 ° C., and the reaction was continued for 1 hour. Then, the polymer was taken out from the nozzle at the bottom of the reaction can as a strand, cooled with water, and pelletized. Next, the polymer obtained by the above operation was vacuum dried at 100 ° C. for 48 hours to obtain dried and crystallized pellets. Polyamide 1 thus obtained had a melting point = 238 ° C., a terminal carboxyl group concentration = 155.7 μeq / g, a terminal amino group concentration = 25.3 μeq / g, and a number average molecular weight = 11050.
(4) Polyamide 2
A 50-liter reactor equipped with a stirrer, a condenser, a cooler, a thermometer, a dripping tank, and a nitrogen gas introduction tube was charged with 15 kg of adipic acid and 15 g of sodium hypophosphite monohydrate, and sufficiently substituted with nitrogen Then, the temperature was raised to 180 ° C. under a small amount of nitrogen flow, and adipic acid was uniformly melted. Then, 13.6 kg of metaxylylenediamine was required for 170 minutes while stirring the system. And dripped. During this time, the internal temperature was continuously raised to 245 ° C. Water generated by polycondensation was removed from the system through a condenser and a cooler. After completion of the dropwise addition of metaxylylenediamine, the internal temperature was further raised to 260 ° C., and the reaction was continued for 1 hour. Then, the polymer was taken out from the nozzle at the bottom of the reaction can as a strand, cooled with water, and pelletized. Next, the polymer obtained by the above operation was vacuum dried at 100 ° C. for 48 hours to obtain dried and crystallized pellets. Polyamide 2 obtained had a melting point of 238 ° C., a terminal carboxyl group concentration of 167.5 μeq / g, a terminal amino group concentration of 27.3 μeq / g, and a number average molecular weight of 10250.
(5) Polyamide 3
A 50-liter reactor equipped with a stirrer, a condenser, a cooler, a thermometer, a dripping tank, and a nitrogen gas introduction tube was charged with 15 kg of adipic acid and 15 g of sodium hypophosphite monohydrate, and sufficiently substituted with nitrogen Then, the temperature was raised to 180 ° C. under a small amount of nitrogen flow, and adipic acid was uniformly melted. Then, 13.6 kg of metaxylylenediamine was required for 170 minutes while stirring the system. And dripped. During this time, the internal temperature was continuously raised to 245 ° C. Water generated by polycondensation was removed from the system through a condenser and a cooler. After completion of the dropwise addition of metaxylylenediamine, the internal temperature was further raised to 260 ° C., and the reaction was continued for 1 hour. Then, the polymer was taken out from the nozzle at the bottom of the reaction can as a strand, cooled with water, and pelletized. Next, the polymer obtained by the above operation was vacuum dried at 100 ° C. for 48 hours to obtain dried and crystallized pellets. Polyamide 3 obtained had a melting point = 238 ° C., a terminal carboxyl group concentration = 189.4 μeq / g, a terminal amino group concentration = 27.0 μeq / g, and a number average molecular weight = 9200.
(6) Polyamide 4
A 50-liter reactor equipped with a stirrer, a condenser, a cooler, a thermometer, a dripping tank, and a nitrogen gas introduction tube was charged with 15 kg of adipic acid and 15 g of sodium hypophosphite monohydrate, and sufficiently substituted with nitrogen Then, the temperature was raised to 180 ° C. under a small amount of nitrogen stream, and adipic acid was uniformly melted. Then, 13.8 kg of metaxylylenediamine was required for 170 minutes while stirring the system. And dripped. During this time, the internal temperature was continuously raised to 245 ° C. Water generated by polycondensation was removed from the system through a condenser and a cooler. After completion of the dropwise addition of metaxylylenediamine, the internal temperature was further raised to 260 ° C., and the reaction was continued for 1 hour. Then, the polymer was taken out from the nozzle at the bottom of the reaction can as a strand, cooled with water, and pelletized. Next, the polymer obtained by the above operation was vacuum dried at 100 ° C. for 48 hours to obtain dried and crystallized pellets. Polyamide 1 obtained had a melting point = 238 ° C, a terminal carboxyl group concentration = 83.3 µeq / g, a terminal amino group concentration = 34.0 µeq / g, and a number average molecular weight = 17050.
(7) Polyamide 5
A 50-liter reactor equipped with a stirrer, a condenser, a cooler, a thermometer, a dripping tank, and a nitrogen gas introduction tube was charged with 15 kg of adipic acid and 15 g of sodium hypophosphite monohydrate, and sufficiently substituted with nitrogen Then, the temperature was raised to 180 ° C. under a small amount of nitrogen stream, and adipic acid was uniformly melted. Then, 13.8 kg of metaxylylenediamine was required for 170 minutes while stirring the system. And dripped. During this time, the internal temperature was continuously raised to 245 ° C. Water generated by polycondensation was removed from the system through a condenser and a cooler. After completion of the dropwise addition of metaxylylenediamine, the internal temperature was further raised to 260 ° C., and the reaction was continued for 1 hour. Then, the polymer was taken out from the nozzle at the bottom of the reaction can as a strand, cooled with water, and pelletized.
Next, after putting the polymer obtained by the above operation into a 50 L rotary tumbler equipped with a heating jacket, a nitrogen gas introduction tube, and a vacuum line, the system was depressurized while rotating, and then nitrogen with a purity of 99% by volume or more was obtained. The operation to bring the pressure to normal was performed 3 times. Thereafter, the temperature inside the system was raised to 140 ° C. under a nitrogen flow. Next, the system was depressurized, and the temperature was continuously raised to 190 ° C., and maintained at 190 ° C. for 30 minutes. Then, nitrogen was introduced to return the system to normal pressure, followed by cooling to obtain polyamide 5. It was. Polyamide 5 obtained had a melting point of 238 ° C., a terminal carboxyl group concentration of 66.5 μeq / g, a terminal amino group concentration of 17.6 μeq / g, and a number average molecular weight of 23800.

2. Analysis method and measurement method The properties of polyester and polyamide used in Examples and Comparative Examples, and the properties of polyester-based containers obtained by molding were analyzed and measured by the following methods.
(1) Polyamide terminal group concentration (a) Terminal amino group concentration ([NH ₂ ] μeq / g)
0.2-0.5 g of polyamide was precisely weighed, and the polyamide was dissolved in 30 ml of phenol / ethanol = 4/1 volume solution with stirring. After the polyamide was completely dissolved, neutralization titration with N / 100 hydrochloric acid was performed.
(B) Terminal carboxyl group concentration ([COOH] μeq / g)
0.2 to 0.5 g of polyamide was precisely weighed, and polyamide was dissolved in 30 ml of benzyl alcohol at 160 to 180 ° C. under nitrogen flow with stirring. After the polyamide was completely dissolved, it was cooled to 80 ° C. under a nitrogen stream, 10 ml of methanol was added with stirring, and neutralization titration with an aqueous N / 100 sodium hydroxide solution was performed.
(2) Number average molecular weight of polyamide The number average molecular weight (Mn) is calculated from the amino group concentration ([NH ₂ ] μeq / g) and the carboxyl group concentration ([COOH] μeq / g) of the polyamide by the following formula (A). did.
Mn = 2 × 10 ⁶ / ([NH ₂ ] + [COOH]) (A)
(3) Melting | fusing point of polyester and polyamide Using Shimadzu Corporation DSC-60, it measured with the temperature increase rate of 10 degree-C / min under nitrogen stream, and made melting peak temperature into melting | fusing point.
(4) Oxygen permeability measurement of biaxially stretched hollow container Using OX-TRAN 2/61 manufactured by MOCON, oxygen permeation was performed under the conditions of 100% RH inside, 50% RH outside, and 23 ° C. temperature. The rate (ml / (day · 0.21 atm)) was measured.
(5) Haze measurement of a biaxially stretched hollow container According to JIS K-7105. As a measuring device, a measuring device (COH-300) manufactured by Nippon Denshoku Industries Co., Ltd. was used.

3. Production of Biaxially Stretched Hollow Container A predetermined amount of polyester resin (A) and polyamide resin (B) were weighed and placed in a tumbler and mixed for 10 minutes. Subsequently, this mixture was injected with an injection molding apparatus (M200PDM-MJ, manufactured by Meiki Seisakusho Co., Ltd.) to obtain a parison having a length of 96 mm, a wall thickness of 4.0 mm, an outer diameter of 22.5 mm, and a weight of 27 g. The injection conditions are a back pressure of 4.0 MPa, a screw rotation speed of 150 rpm, an injection speed of 155 cc / sec, a resin temperature of 275 ° C., and a mold temperature of 15 ° C.
The parison was biaxially stretched and blow molded by a blow molding apparatus (EFB1000ET manufactured by Frontier Co., Ltd.) to form a biaxially stretched hollow container having a height of 223 mm, a body diameter of 65 mm, a capacity of 500 ml, and an average thickness of about 300 μm.

Examples 1-3, Comparative Examples 1-6
A biaxially stretched hollow container composed of a combination of the polyester resin (A) and the polyamide resin (B) shown in Table 1 was molded, and the oxygen permeability measurement of the container and the haze measurement of the trunk were performed. Table 1 shows the container material composition and various evaluation results.

  As is clear from Table 1, the biaxially stretched hollow container of the example satisfying the constitutional requirements of the present invention has good transparency with a haze of less than 5%, and the oxygen permeability is also compared with Comparative Example 1. It was low. On the other hand, in Comparative Examples 2-6, the haze of the container trunk | drum was high and it was inferior to transparency. Moreover, since Comparative Example 1 was a polyester simple substance, the transparency was good but the oxygen permeability was poor.

Claims (3)

Copolyester resin (A) 80 to 99% by weight, diamine unit containing 70% by mole or more of metaxylylenediamine units, and 70% by mole of α, ω-linear aliphatic dicarboxylic acid unit having 4 to 20 carbon atoms This is a biaxially stretched hollow container formed from a polyester resin composition (C) comprising 1 to 20% by weight (%) of a polyamide resin (B) comprising the above-mentioned dicarboxylic acid units (total weight is 100% by weight). In the copolymer polyester resin (A), 70 mol% or more of the dicarboxylic acid structural unit is composed of an aromatic dicarboxylic acid unit, 70 mol% or more of the diol structural unit is composed of an aliphatic diol unit, and the dicarboxylic acid structural unit is 0.01-5 mol% of sulfonic acid metal base is included, and the number average molecular weight of the polyamide resin (B) is 6000-15000 Stretched hollow container. The biaxially stretched hollow container according to claim 1, wherein the aromatic dicarboxylic acid is terephthalic acid and the aliphatic diol is ethylene glycol. The biaxially stretched hollow container according to claim 1, wherein the aromatic dicarboxylic acid comprises 90 to 99 mol% terephthalic acid and 1 to 10 mol% isophthalic acid.