JP2008231316A - Aromatic polyester resin-based stretched article - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an aromatic polyester resin-based stretched article which is made of a mixture obtained by mixing a small amount of a polyglycolic acid resin with an aromatic polyester resin and is well balanced between stable gas barrier and good transparency, and to provide a multilayer aromatic polyester resin-based stretched article comprising the same. <P>SOLUTION: The aromatic polyester resin-based stretched article is made of a mixture of a polyglycolic acid resin with an aromatic polyester resin and is stretched, wherein the mixture contains 1-9 wt.% of the polyglycolic acid resin. The multilayer stretched article is provided by laminating a stretched aromatic polyester resin layer on at least one surface of the stretched article. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an improvement of an aromatic polyester resin molded article having improved gas barrier properties by blending a polyglycolic acid resin, and more specifically, an aromatic polyester resin stretch molded article in which gas barrier properties and transparency are harmonized, and the same. The present invention relates to an aromatic polyester resin-based multilayer stretched molded product.

  Aromatic polyester resins such as polyethylene terephthalate are excellent in moldability, mechanical properties, transparency and the like, and are widely used as packaging materials for various foods and beverage containers. However, as a packaging material for foods that are expected to be stored for a long period of time, the gas barrier property of the aromatic polyester resin is not sufficient, and deterioration of the contents due to oxygen permeation is difficult to avoid during long-term storage.

On the other hand, polyglycolic acid resins are known to have particularly excellent gas barrier properties in addition to heat resistance and mechanical strength (for example, Patent Document 1), and a relatively small amount thereof (5 to 50 wt% or 1 to 30 wt%). %) Has been proposed in an aromatic polyester resin (Patent Documents 2 and 3). However, the aromatic polyester resin and the polyglycolic acid resin are inherently incompatible, and the resin composition obtained by melt-kneading them loses transparency. It is understood that the decrease in transparency due to these blend compositions is essentially inevitable, and Patent Document 2 does not discuss at all. On the other hand, in Patent Document 3, when an aromatic polyester resin and a relatively small amount of polyglycolic acid resin are melt-kneaded, a coupling agent such as pyromellitic anhydride is added, or instead of polyglycolic acid. By using a copolymer of glycolic acid and isophthalic acid or the like, or an oxycarboxylic acid copolymer polyester having an aromatic dicarboxylic acid unit or a diol unit in addition to the oxycarboxylic acid unit, it is possible to suppress a decrease in transparency. I am trying. However, in this case, even if the decrease in transparency can be suppressed, the effect of improving gas barrier properties obtained by blending a small amount of polyglycolic acid resin is poor.
Japanese Patent Laid-Open No. 10-60136 US Pat. No. 4,565,851 JP 2005-200516 A WO2005 / 032800A1 publication

  Therefore, the main object of the present invention is an aromatic polyester resin stretch-molded article comprising a mixture obtained by blending a small amount of a polyglycolic acid resin with an aromatic polyester resin, and having a good harmony between gas barrier properties and transparency, and An object of the present invention is to provide an aromatic polyester resin-based multilayer stretched molded article containing the same.

  As a result of researches for the above-mentioned purpose, the present inventors have found that the content of polyglycolic acid resin is 1 to 9% by weight, which is overlapping in the above-mentioned Patent Documents 2 and 3 but not embodied in Examples. A molded product of a small amount of an aromatic polyester resin still exhibits a significant improvement in gas barrier properties and causes a significant increase in haze value (decrease in transparency) when unstretched. It can be seen that a significant decrease in haze value is obtained as compared with a molded article of aromatic polyester resin of 10% by weight or more (for example, Comparative Example 2 of Patent Document 3), and harmony between gas barrier properties and transparency is obtained. It was issued.

  The stretched molded article of the aromatic polyester resin of the present invention is based on such knowledge, and more specifically, a mixture of a polyglycolic acid resin containing 1 to 9% by weight of a polyglycolic acid resin and an aromatic polyester resin. And is stretched.

  The present invention also provides an aromatic polyester resin multilayer stretched molded product in which an aromatic polyester resin layer stretched on at least one surface of the aromatic polyester resin stretched molded product is laminated. Such a multilayer stretch molded body structure has a significant gas barrier property improving effect and a haze improving effect due to stretching of the aromatic polyester resin molded body having an extremely low polyglycolic acid resin content of 1 to 9% by weight of the present invention described above. Can be used to the maximum, and the following effects can be obtained. (A) Polyglycolic acid resin exhibits excellent gas barrier properties but is easily hydrolyzed. However, the hydrolyzability of the polyglycolic acid resin is remarkably relaxed by mixing with a large amount of aromatic polyester resin. (B) The second and greatest advantage is that the maximum gas barrier property improvement effect can be achieved while eliminating the problems in the manufacturing process by using a relatively small amount of polyglycolic acid resin. That is, the polyglycolic acid resin is a functional resin having excellent characteristics, but its production cost is lower than that of a general-purpose resin such as an aromatic polyester resin due to its hydrolyzability or the special property of the monomer (glycolide). It must be expensive. Therefore, it is desirable that the gas barrier property improving effect can be obtained with as little amount as possible. Conventionally, a laminate of a relatively thin polyglycolic acid resin layer and a relatively thick aromatic polyester resin layer has been used (for example, Patent Document 4), but the amount of polyglycolic acid resin used is further reduced. Therefore, to reduce the thickness of the polyglycolic acid resin layer, for example, when the co-injection method or the co-extrusion method, which is the most common lamination method, is employed, the polyglycolic acid resin and the aromatic polyester resin are melt processed. Due to the remarkably different characteristics, the thickness distribution in the product laminate tends to be uneven due to uneven thickness of the polyglycolic acid resin layer. On the other hand, according to the present invention, if an aromatic polyester resin having a polyglycolic acid resin content reduced to 1 to 9% by weight is used, the difference in melt processing characteristics from the aromatic polyester resin to be laminated is remarkably reduced. In addition, the aromatic polyester resin layer thickness per unit polyglycolic acid resin amount is remarkably increased (for example, when the polyglycolic acid resin amount is 5% by weight, about 100% of the polyglycolic acid resin layer). 20 times the thickness). Therefore, there is almost no reduction in the gas barrier property improvement effect due to uneven thickness accompanying the reduction in the amount of polyglycolic acid resin. On the other hand, the haze increase associated with the increase in thickness is caused by the increase in the amount of polyglycolic acid resin that accompanies the increase in thickness if the blend of polyglycolic acid resin is as low as 1 to 9% by weight. Therefore, it is rather improved when viewed with the same amount of polyglycolic acid resin. Further, the effect of improving the gas barrier property by blending the polyglycolic acid resin is such that the blending amount of the polyglycolic acid resin is less than 10% by weight (Comparative Example 1 → Comparative Example 5 and Comparative Example 8 → Comparative Example 9 in Table 1 described later). This was found to be more marked when the blending amount was 10 to 20% by weight (Comparative Example 5 → Comparative Example 6 and Comparative Example 9 → Comparative Example 10). Therefore, the use of a relatively small amount of polyglycolic acid resin as a whole makes it possible to improve the gas barrier properties with the difference in melt processing characteristics between polyglycolic acid resin and aromatic polyester resin. It is achieved while eliminating the problem. (C) Further, if a multilayer stretched molded article structure in which at least one surface including the surface in contact with the contents of the aromatic polyester resin molded article is covered with a stretched aromatic polyester resin layer is formed, gloss and transparency are improved. Further, according to the multilayer stretched molded article structure of the present invention, even if the total amount of the polyglycolic acid resin is constant, the aromatic polyester-based resin molded article having a high polyglycolic acid resin content with good gas barrier properties. The layer can be used, and the gas barrier property as a whole of the multilayer stretched molded article can be improved.

(Aromatic polyester resin)
The aromatic polyester resin constituting the stretched molded article of the present invention contains an aromatic polyester resin as a main resin component. Specific examples thereof include polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polyethylene naphthalate. (PEN), aromatic polyester such as polyethylene terephthalate (PETG) having poly 1,4 cyclohexanedimethanol as a copolymerization component, poly 1,4 cyclohexylene dimethylene terephthalate / isophthalate copolymer (PC1A), and the like. Of these, polyethylene terephthalate is preferably used. Here, polyethylene terephthalate is mainly composed of terephthalic acid units derived from terephthalic acid or an ester derivative thereof, and ethylene glycol units derived from ethylene glycol or an ester derivative thereof. , Other dicarboxylic acids such as isophthalic acid and naphthalene 2,6-dicarboxylic acid, or diols such as diethylene glycol, or those substituted with hydroxycarboxylic acid. Moreover, these 2 or more types of mixtures may be sufficient as needed.

  As the aromatic polyester resin, it is preferable to use those having an intrinsic viscosity as a molecular weight equivalent scale in the range of 0.6 to 2.0 dl / g, particularly 0.7 to 1.5 dl / g. If the intrinsic viscosity is too low, molding is difficult, and if it is too high, shear heat generation becomes large.

  Aromatic polyester resins are generally obtained by polycondensation using compounds containing metals such as antimony (Sb), germanium (Ge), tin (Sn), zinc (Zn), aluminum (Al), and titanium (Ti) as catalysts. Depending on the catalyst species, the physical properties of the product may be slightly different. In the present invention, the aromatic polyester resin as described above may be obtained from any metal compound (catalyst) including commercially available products. Can also be used. The metal compound (catalyst) is preferably a metal organic complex or oxide, and particularly preferably an oxide. The content in the aromatic polyester resin is usually 1 ppm or more and less than 1000 ppm, and use of a larger amount leads to coloring of the produced aromatic polyester resin and an increase in production cost.

  The aromatic polyester resin used in the present invention is 99 to 91% by weight, preferably 99 to 93% by weight, more preferably 99% to 95% by weight, based on the aromatic polyester resin described above. Including. If it is used in excess of 99% by weight, it becomes difficult to obtain the intended effect of improving the gas barrier property with a decrease in the amount of the corresponding polyglycolic acid resin. On the other hand, if the amount of the corresponding polyglycolic acid resin is increased to less than 91% by weight, a decrease in transparency of the obtained stretched molded product becomes a problem.

(Polyglycolic acid resin)
As the polyglycolic acid resin (hereinafter often referred to as “PGA resin”) used in the present invention, a homopolymer of glycolic acid consisting only of glycolic acid repeating units represented by — (O · CH ₂ · CO) — ( In addition to PGA and glycolide (GL), which is a bimolecular cyclic ester of glycolic acid), a polyglycolic acid copolymer is included.

  Examples of comonomers that give a polyglycolic acid copolymer together with glycolic acid monomers such as glycolide include ethylene oxalate (that is, 1,4-dioxane-2,3-dione), lactides, and lactones (for example, β-propiolactone, β-butyrolactone, β-pivalolactone, γ-butyrolactone, δ-valerolactone, β-methyl-δ-valerolactone, ε-caprolactone, etc.), carbonates (eg trimethylene carbonate, etc.), ethers Cyclic monomers such as ether esters (eg dioxanone), amides (ε-caprolactam etc.); lactic acid, 3-hydroxypropanoic acid, 3-hydroxybutanoic acid, 4-hydroxybutane Acid, such as 6-hydroxycaproic acid Bon acid or its alkyl ester; or can be given two or more thereof. Among them, a copolymer having only a repeating unit of hydroxycarboxylic acid is preferable as a whole, and the glycolic acid repeating unit in the PGA resin is 80% by weight or more in order to maintain a high gas barrier property improving effect on the aromatic polyester resin. It is preferable that it is a PGA homopolymer. By selecting such a PGA resin, it is possible to achieve a good balance between gas barrier properties and transparency.

  As the PGA resin, those having various molecular weight ranges are used, and oligomers may be used. That is, as the PGA resin, one having a molecular weight (Mw in terms of polymethyl methacrylate (weight average molecular weight)) in the range of 10,000 to 500,000 in GPC measurement using a hexafluoropropanol solvent is usually used. In particular, when an improvement in transparency by transesterification during melt kneading with an aromatic polyester resin is expected, it is preferable to use a PGA resin having a weight average molecular weight of 20,000 or less. However, in this case as well, if the weight average molecular weight is too small, the strength of the resulting composition tends to decrease, such being undesirable.

In order to obtain a higher-strength aromatic polyester resin composition, it is preferable to use a PGA resin having a weight average molecular weight of 30,000 or more, particularly 50,000 or more. However, even in this case, if the molecular weight is excessive, melt kneading with the aromatic polyester resin becomes difficult, and the strength of the molded product obtained on the contrary may be lowered. In particular, those having Mw in the range of 150,000 to 300,000 are preferable. On the other hand, the melt viscosity property is preferably in the range of 200 to 800 Pa · s, particularly preferably in the range of 300 to 700 Pa · s, as measured at 270 ° C. and a shear rate of 122 sec ⁻¹ .

  As such a high molecular weight PGA resin, it is preferable to use a PGA resin obtained by a method in which glycolide (and a small amount of a cyclic comonomer if necessary) is heated to cause ring-opening polymerization. This ring-opening polymerization method is a ring-opening polymerization method by substantially bulk polymerization. The ring-opening polymerization is usually performed at a temperature of 100 ° C. or higher in the presence of a catalyst. In order to suppress the decrease in the molecular weight of the PGA resin during melt kneading according to the present invention, the amount of residual glycolide in the PGA resin used is preferably suppressed to less than 0.5% by weight, particularly 0.2% by weight. It is preferable to make it less than. As the ring-opening polymerization catalyst, oxides, halides, carboxylates, alkoxides, etc., such as tin, titanium, aluminum, antimony, zirconium, zinc, and germanium are used. Among these, tin compounds, particularly tin chloride, are preferably used in terms of polymerization activity and colorlessness. However, when the residual tin (metal content) content in the PGA resin to be produced increases, It has been recognized that the melt stability or thermal stability during the processing tends to decrease, and the residual tin (metal content) content is preferably 70 ppm or less (about 100 ppm or less as tin chloride).

  The aromatic polyester resin used in the present invention contains the above-described polyglycolic acid resin in a proportion of 1 to 9% by weight, preferably 1 to 7% by weight, more preferably 1% by weight or more and less than 5% by weight. If it is less than 1% by weight, it is difficult to obtain the intended effect of improving gas barrier properties. On the other hand, when it exceeds 9% by weight, a decrease in transparency of the obtained stretched molded product becomes a problem.

(Melting and pelletizing)
In order to obtain an aromatic polyester resin composition as a raw material for the stretched molded product of the present invention, it is preferable to melt-knead the above-mentioned ratio of the aromatic polyester resin and the polyglycolic acid resin into pellets.

  For melt kneading, a plast mill, a kneader, or the like can be used, but a single screw extruder or a twin screw extruder is more preferably used industrially for further pelletization. The melt kneading temperature is generally a temperature that is equal to or higher than the higher melting point of the two components to be kneaded, that is, the aromatic polyester resin and the PGA resin, and the melting point of the aromatic polyester resin, particularly polyethylene terephthalate (PET) is usually about 260 ° C. Since the melting point of PGA is about 220 ° C., a temperature of about 260 ° C. or higher is generally adopted, but it is preferable that the optimum temperature is set depending on the melting point of the aromatic polyester resin actually used. In addition, since a certain amount of heat can be generated during the melt-kneading, the temperature setting of the melt-kneading apparatus can be set below the melting point of the aromatic polyester resin accordingly. The set temperature of melt kneading, preferably an extruder, is generally within the range of 220 to 350 ° C, more preferably 240 to 330 ° C, and even more preferably 260 to 300 ° C. If it is less than 220 ° C., it is insufficient or takes a long time to form a molten state. In addition, the resulting composition tends to have insufficient barrier properties. On the other hand, at a melt-kneading temperature exceeding 350 ° C., there is a risk of coloring or a reduction in barrier properties due to the occurrence of decomposition reaction or side reaction.

  The melt kneading time is generally selected from the range of 30 seconds to 60 minutes, more preferably 1 minute to 15 minutes.

(Preliminary molding / stretching)
The aromatic polyester resin composition (pellet) obtained as described above is preformed and stretched to obtain the stretched molded product of the present invention. The preform has a planar sheet or a precursor shape of a container such as a cup or a bottle, and the molded body has a product shape such as a film or a cup or a bottle. Here, the terms “sheet” and “film” refer to a planar shaped product before and after stretching, and the thickness is relative, and is not intended to define a thickness with a boundary of about 250 μm as often used. .

  For the pre-molding, a melt resin molding method using any shape such as a sheet or a parison, preferably using an extruder or an injection molding machine, is used. Biaxial stretching, in which the stretched molded product of the present invention is obtained by subjecting the obtained preform to uniaxial or biaxial stretching, is more preferred. Biaxial stretching is performed by a tenter method, an inflation method, a blow molding method, or the like. For example, a blow molding method is preferable for forming a bottle, which includes a hot parison method in which a preform (parison) formed by injection molding is stretched in a hot state without being completely cooled, and a cooling temperature once after cooling. There is a cold parison method in which the film is reheated to stretch blow molding, and the cold parison method is preferred. The preform that has reached the stretching temperature is subjected to stretch blow molding using a stretch blow molding machine. A preform is introduced into a blow mold of a stretch blow molding machine, stretched in the longitudinal direction (axial direction) by a stretching rod in the blow mold, and stretched in a lateral direction (circumferential direction) by blowing high-pressure air. . Generally, a stretching rod is inserted to start stretching in the longitudinal direction, and a bottle is created by blowing high-pressure air at an appropriate time.

  Since the aromatic polyester resin used in the present invention has a low polyglycolic acid resin content of 1 to 9% by weight, the conditions for pre-molding and stretching are substantially the same as the molding of the aromatic polyester resin. For example, the stretching temperature is 80 to 130 ° C, more preferably 90 to 110 ° C. The stretch ratio is suitably about 4 to 16 times, particularly about 9 to 12 times as the area ratio.

(Manufacture of multilayer stretch molded products)
According to a preferred embodiment of the present invention, a multilayer stretched molded product in which an aromatic polyester resin layer is laminated on at least one surface, preferably on both surfaces, of the stretched molded product formed as described above is formed.

  The multilayer stretch molded article can also be formed by laminating an aromatic polyester resin layer stretched on at least one surface of the stretch molded article of the present invention formed as described above. It is more preferable to form a preform with the laminated aromatic polyester resin layer and to co-stretch it.

  For that purpose, the above-mentioned aromatic polyester resin layer and aromatic polyester resin layer are formed by co-extrusion extrusion, extrusion lamination, press molding, or the like, and then co-stretched.

  In addition to melt extrusion characteristics, the stretching characteristics of aromatic polyester resin and aromatic polyester resin are also approximated, so aromatic polyester resin / aromatic polyester resin or aromatic polyester resin / aromatic polyester resin / aromatic As for the formation and stretching conditions of the laminate composed of the polyester resin, the same method as the above-described formation and stretching method of the preform of the aromatic polyester resin single layer is used. The conditions for forming the polyester resin single-layer stretched molded body are also common. The proportion of the polyglycolic acid resin in the aromatic polyester resin layer of the multilayer stretched molded article may be 5 to 9% by weight. This is because the aromatic polyester resin is disposed on the surface layer, and the glossiness of the aromatic polyester resin layer is alleviated by the gloss.

  The thickness ratio of the aromatic polyester resin layer in the multilayer stretched molded article of the present invention thus formed varies depending on the polyglycolic acid resin content in the aromatic polyester resin used and the target gas barrier property level. In the present invention, which is mainly intended to improve gas barrier properties by using a small amount of polyglycolic acid resin, the ratio of the aromatic polyester resin layer thickness (A) to the aromatic polyester resin layer (total) thickness (B) However, it is preferable to set so that (B) / (A) = 0.05 to 30, particularly 0.1 to 20.

  The single-layer or multi-layer stretch-molded article of the present invention obtained as described above is used for containers such as bottles and cups or packaging films that have been conventionally formed from aromatic polyester resins typified by PET. .

  Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples. The measurement or evaluation of the characteristic values described in this specification including the following examples is based on the following method.

[Intrinsic viscosity]
An amorphous PET sample was dissolved in phenol / 1,1,2,2-tetrachloroethane, and an Ubbelohde viscometer no. 1 (viscosity constant 0.1173) was used to determine the intrinsic viscosity (IV, unit: dl / g) according to JIS K7390.

[Molecular weight measurement]
About 10 mg of the PGA sample is completely dissolved in 0.5 ml of special grade dimethyl sulfoxide in an oil bath at 150 ° C. The solution was cooled with cold water, and made up to 10 ml with hexafluoroisopropanol (HFIP) in which 5 mM sodium trifluoroacetate was dissolved. The solution was filtered through a PTFE 0.1 μm membrane filter and then injected into a gel permeation chromatography (GPC) apparatus, and the weight average molecular weight (Mw) was measured. The sample was injected into the GPC apparatus within 30 minutes after dissolution.

<GPC measurement conditions>
Equipment: “Shodex-104” manufactured by Showa Denko KK
Column: 2 HFIP-606M, 1 HFIP-G as a pre-column (series connection)
Column temperature: 40 ° C
Eluent: HFIP solution containing 5 mM sodium trifluoroacetate Flow rate: 0.6 ml / min Detector: RI (differential refractive index detector)
Molecular weight calibration: Seven standard polymethyl methacrylates having different molecular weights were used.

[Melt viscosity]
The PGA sample was measured with a “capillograph” manufactured by Toyo Seiki Seisakusho Co., Ltd. using a capillary with a diameter of 1 mm and a length of 10 mm under conditions of a temperature of 270 ° C. and a shear rate of 122 s ⁻¹ .

[Haze]
About the film thru | or sheet-like sample, it calculated | required by the measurement based on JISK7361-1 using Nippon Denshoku Industries Co., Ltd. haze meter "NDH2000".

[Oxygen permeability]
A film or sheet-like sample was measured under the condition of a relative humidity of 80% at 23 ° C. using an oxygen permeability measuring device “OX-TRAN 2/20” manufactured by Modern Control, and an oxygen gas permeability coefficient (PO ₂ ; unit: cm ³ · cm / cm ² · sec · cmHg).

[Create single-layer unstretched sheet]
(Comparative Examples 1-7)
Copolymerized polyester (“1101” manufactured by Kosa; intrinsic viscosity: 0.83 dl / g, hereinafter referred to as “PET”) as an aromatic polyester resin, and melt at 270 ° C. and a shear rate of 122 sec ⁻¹ as a polyglycolic acid resin A polyglycolic acid homopolymer (“PGA”) having a viscosity of 354 Pa · s was used. These were each blended in the proportions shown in Table 1 below, melt-kneaded at 280 ° C. using a twin-screw extruder (“2D30W2” manufactured by Toyo Seiki Seisakusho), and extruded to be pelletized. The pellets were pressed at 290 ° C., a pressure of 10 MPa, and 1 minute to obtain seven kinds of press sheets having a thickness of 100 μm.

[Create single layer stretched film]
(Comparative Example 8, Examples 1-3 and Comparative Examples 9-11)
About the 100 micrometer-thick press sheet obtained by carrying out similarly to the said Comparative Examples 1-7, it extended | stretched 3x3 times at 100 degreeC using the biaxial stretching machine (Toyo Seiki Co., Ltd. "xGH-S"). A stretched film having a thickness of about 11 μm was obtained.

For unstretched sheet and a stretched film obtained in the above Comparative Examples and Examples, by the method described above, the oxygen permeability of (PO ₂₎ and haze were measured. The results are shown together with the composition in Table 1 below.

As is apparent from Table 1 above, according to the present invention, the PET / PGA composition (aromatic polyester resin) containing 1 to 9% by weight of PGA exhibits a high haze value of 48 to 94% before stretching. (Comparative Examples 2 to 4) show a remarkably low haze value of 3 to 15% by stretching, and the transparency is improved and PO ₂ is reduced to about 1/2 (Examples 1 to 3). On the other hand, when the PGA content is 10% by weight or more, a decrease in PO ₂ is similarly observed due to stretching, but a decrease in haze is still not sufficient.

[Multilayer unstretched sheet]
(Comparative Example 12)
In the same manner as in Comparative Example 3, PET and PGA were mixed at a ratio of 95% by weight and 5% by weight, and pelletized by melt kneading and extrusion at 280 ° C. by a twin screw extruder as in Comparative Example 3, at 290 ° C., pressure Pressing was performed at 10 MPa for 1 minute to obtain a PET-PGA blend press sheet having a thickness of about 200 μm.

  Separately, PET alone was extruded using a single screw extruder (“PEX type extruder” manufactured by Pla Giken Co., Ltd.) to obtain a PET press sheet having a thickness of about 200 μm.

  The above-mentioned two kinds of press sheets were superposed on three layers in the order of PET / PET-PGA blend / PET to prepare a multilayer unstretched sheet.

This multilayer unstretched sheet exhibited PO ₂ : 37 × 10 ⁻¹³ cm ³ · cm / cm ² · sec · cm Hg and haze: 93%.

[Multilayer stretched film]
Example 4
The unstretched multilayer sheet obtained in Comparative Example 12 was biaxially stretched 3 × 3 times at a temperature of 100 ° C. in the same manner as in Examples 1 to 3 to obtain a multilayer stretched film having a total thickness of about 60 μm.

This multilayer stretched film exhibited PO ₂ : 18 × 10 ⁻¹³ cm ³ · cm / cm ² · sec · cmHg and haze: 12%.

  As described above, according to the present invention, an aromatic polyester comprising a mixture obtained by arranging a small amount of a polyglycolic acid resin in an aromatic polyester resin, and having a good harmony between stable gas barrier properties and good transparency. -Based resin stretch-molded bodies and aromatic polyester resin-based multilayer stretch-molded bodies including the same are provided.

Claims (9)

A stretched aromatic polyester-based resin stretched from a mixture of a polyglycolic acid resin containing 1 to 9% by weight of a polyglycolic acid resin and an aromatic polyester resin. A polyglycolic acid resin is a homopolymer of glycolic acid or a copolymer with other hydroxycarboxylic acid containing a glycolic acid repeating unit represented by-(O.CH ₂ .CO)-in a proportion of 80% by weight or more. The aromatic polyester-based resin stretch molded article according to claim 1. The aromatic polyester resin stretch-molded article according to claim 1 or 2, comprising a mixture of a polyglycolic acid resin containing 1 to 5% by weight of a polyglycolic acid resin and an aromatic polyester resin. An aromatic polyester resin-based multilayer stretched molded article in which an aromatic polyester resin layer stretched on at least one surface of the aromatic polyester-based resin stretched molded article according to any one of claims 1 to 3 is laminated. The multilayer stretch molded article according to claim 4, wherein an aromatic polyester resin layer stretched on both surfaces of the aromatic polyester resin stretch molded article is laminated. The multilayer stretched molded product according to claim 4 or 5, wherein the aromatic polyester resin-based stretched molded product and the aromatic polyester resin layer are co-stretched. The multilayer stretch-molded product according to any one of claims 4 to 6, wherein the aromatic polyester resin-based stretch-molded product comprises a mixture of a polyglycolic acid resin containing 5-9% by weight of a polyglycolic acid resin and an aromatic polyester resin. body. The stretched molded product according to any one of claims 1 to 7, which has a haze of 20% or less. The stretched molded article according to any one of claims 1 to 7, which has a haze of 10% or less.