JP2000296593A - Polyester multilayer sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To upgrade gas barrier properties, moldability and transparency by forming one or more layers each of a polyethylene terephthalate resin layer and a polytrimethylene naphthalate resin layer. SOLUTION: One or more layers each of a polyethylene terephthalate(PET) resin layer and a polytrimethylene naphthalate(PTN) resin layer are formed. PTN of such a kind as obtained especially from a 2,6-naphthalene dicarboxylic acid and a 1,3-propane diol, shows a rapid polymerization reaction and an outstanding resin physical property obtained. The weight ratio of the PTN resin layer of the polyester multilayer sheet is preferably 10 wt.% or more of the total polyester resin, which shows superb gas barrier properties. With regard to the manufacturing process of the polyester multilayer sheet, the PET resin and the PTN resin, for example, are supplied to a multilayer sheet molding machine having two or more melting/extruding machines and are extruded into sheet forms from a multilayer extrusion T-die after melting the resins at their respective melt temperatures and further, are quenched by a cooling drum to be molded.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyester multilayer sheet, and more particularly to a gas barrier property, transparency,
The present invention relates to a polyester multilayer sheet having excellent moldability.

[0002]

2. Description of the Related Art Instead of a conventional glass container, a plastic container that is lightweight and hard to break is widely used as a container for packaging various products.

[0003] Polyethylene terephthalate (hereinafter PET)
Polyester resins represented by the general formula (1) have better gas barrier properties than general-purpose olefin resins, and biaxially stretched bottles are also used for carbonated beverages. However, the gas barrier properties of the unstretched PET sheet are not sufficient, and in a container obtained by thermoforming the sheet, oxygen gas passes through the PET resin layer from the outside to the inside of the container, and the taste and components of the content are reduced. Changing is an unavoidable fact.

As a method for solving such a problem, a method using a polyester resin having a high gas barrier property has been proposed. For example, JP-A-49-1676 proposes a sheet made of polyethylene naphthalate (hereinafter referred to as PEN). However, PEN
Due to the low impact resistance of the sheet, the sheet and the container in which the sheet is thermoformed are very fragile.

On the other hand, JP-A-4-39025 discloses that
A laminated sheet comprising a PEN resin layer and a PET resin layer has been proposed. Although the PEN / PET laminated sheet has better gas barrier properties and impact resistance than each single-layer sheet, PEN has a glass transition temperature of about 40 times that of PET.
℃ high, thermoforming is difficult. That is, when the thermoforming temperature is set to the PET condition, the molding becomes defective, and when the PEN condition is set, the PET surface has a disadvantage that cloudiness due to crystallization occurs on the PET surface.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art and to provide a polyester multilayer sheet excellent in gas barrier properties, moldability and transparency.

[0007]

The above object is achieved by a polyester multilayer sheet having at least one polyethylene terephthalate resin layer and at least one polytrimethylene naphthalate resin layer.

[0008]

DETAILED DESCRIPTION OF THE INVENTION The PET resin used in the present invention is obtained by polycondensing terephthalic acid or an ester-forming derivative thereof with ethylene glycol or an ester-forming derivative thereof by a known method. And other copolymer components in a range that does not impair the physical properties of the copolymer.

Such copolymerization components include aromatic dicarboxylic acids such as isophthalic acid and naphthalenedicarboxylic acid, aliphatic dicarboxylic acids such as adipic acid and sebacic acid, butylene glycol, diethylene glycol, neopentyl glycol, propylene glycol, Examples include methylene glycol, 1,4-cyclohexanedimethanol, polyalkylene glycol, and a diethoxy compound of bisphenol A or bisphenol S. These can be used alone or in combination of two or more, but it is preferably 5 mol% or less of the entire polyester.

The PET resin used in the present invention may contain a polyfunctional compound for the purpose of improving moldability. Such polyfunctional compounds include trimellitic acid, pyromellitic acid, trimethylolpropane, pentaerythritol and the like. The content of the polyfunctional compound contained in the resin is preferably in the range of 0.1 to 2.0 mol% because of excellent sheet moldability.

The polytrimethylene naphthalate (hereinafter referred to as PTN) resin used in the present invention is obtained by polycondensing naphthalenedicarboxylic acid or its ester-forming derivative and propylene glycol or its ester-forming derivative by a known method. It is something that can be done. In particular, 2,
The PTN resin obtained from 6-naphthalenedicarboxylic acid and 1,3-propanediol is particularly preferable because the polymerization reaction is fast and the obtained resin properties are excellent.

The PTN resin used in the present invention may contain other copolymer components in a range that does not impair the original physical properties. Examples of such a copolymer component include aromatic dicarboxylic acids such as terephthalic acid and isophthalic acid, aliphatic dicarboxylic acids such as adipic acid and sebacic acid, ethylene glycol, butylene glycol, diethylene glycol, neopentyl glycol, hexamethylene glycol, and the like. ,
4-cyclohexanedimethanol, polyalkylene glycol, bisphenol A or bisphenol S diethoxy compound, and the like. These alone are 2
Although it is possible to use more than one kind, it is preferable that it is 5 mol% or less of the entire polyester.

Further, the PTN resin used in the present invention may contain a polyfunctional compound for the purpose of improving moldability. Such polyfunctional compounds include trimellitic acid, pyromellitic acid, trimethylolpropane, pentaerythritol and the like. It is preferable that the content of the polyfunctional compound contained in the resin is in the range of 0.1 to 2.0 mol% for excellent sheet moldability.

The PET resin used in the present invention contains terephthalic acid or an ester-forming derivative thereof and ethylene glycol or a derivative thereof as main components, and optionally contains other copolymer components and / or polyfunctional compounds in specified amounts. The added raw materials are antimony, titanium, germanium, tin,
It is produced by an esterification reaction step, a liquid phase polycondensation reaction step, and, if necessary, a solid phase polymerization reaction step, using at least one metal element-containing compound selected from the group consisting of zinc as a catalyst.

The PTN resin used in the present invention contains naphthalenedicarboxylic acid or an ester-forming derivative thereof and propylene glycol or a derivative thereof as main components, and optionally specifies other copolymerization components and / or polyfunctional compounds. At least one material selected from the group consisting of antimony, titanium, germanium, tin, and zinc.
It is produced by an esterification reaction step, a liquid phase polycondensation reaction step, and, if necessary, a solid phase polymerization reaction step, using a kind of metal element-containing compound as a catalyst.

The polyester multilayer sheet of the present invention is made of PE
It has at least one or more T resin layers and at least one PTN resin layer. The weight ratio of the PTN resin layer is preferably not less than 10% by weight of the entire polyester resin in order to obtain a sheet having excellent gas barrier properties.

The polyester multilayer sheet of the present invention is a substantially unstretched sheet produced by a known molding method. For example, a PET resin and a PTN resin are supplied to a multilayer sheet molding machine having two or more melt extruders.
It is extruded into a sheet from a die, and quenched by a cooling drum to form. As a form of the obtained multilayer sheet, a two-layer structure sheet composed of a PET resin layer and a PTN resin layer, a three-layer structure sheet having a PET resin layer as an intermediate layer and a PTN resin layer as an outer layer, and a PET resin having a PTN resin layer as an intermediate layer Examples include a three-layer sheet having a layer as an outer layer.

The polyester multilayer sheet of the present invention becomes a molded article having excellent gas barrier properties by thermoforming. In thermoforming, a multilayer sheet is heated and softened, pressed against a desired mold, the air in the gap between the mold and the sheet is removed, and a vacuum forming method in which the mold is brought into close contact with the mold at atmospheric pressure, or compressed air at or above atmospheric pressure is used. Compressed air forming method that makes the sheet adhere to the mold,
In addition, a molding method using vacuum molding and pressure molding together can be applied.

[0019]

The polyester multilayer sheet of the present invention has excellent gas barrier properties, transparency and moldability, and can be suitably used as a food container intended for long-term storage.

[0020]

The present invention will be described below in detail with reference to examples. Measurement and evaluation of each physical property were performed according to the following methods.

(1) Resin Intrinsic Viscosity (IV) Polyester resin is phenol / tetrachloroethane =
Dissolve in a 60/40 (weight ratio) mixture and use an automatic viscosity measurement device (SS-270LC manufactured by Shibayama Scientific) at 20 ° C.
Was measured.

(2) Glass transition temperature (Tg), melting point (T
m) The polyester resin was measured at a heating rate of 10 ° C./min using a differential scanning calorimeter (DSC-7 manufactured by Perkin Elmer).

(3) Transparency (Haze) A polyester multilayer sheet having a thickness of 0.5 mm was subjected to J-haze measurement using a haze meter (Haze Meter 300A manufactured by Nippon Denshoku Co., Ltd.).
It was measured according to IS K 7105.

(4) Oxygen Barrier Property A polyester multilayer sheet having a thickness of 0.5 mm was measured using an oxygen permeability measuring device (OX- manufactured by MODERN CONTROL).
TRAN100) according to JIS K 7126.

(5) Thermoformability An 8-cavity vacuum forming machine with plug assist is used to
A cylindrical container having a size of 5 mm and an opening diameter of 100 mm was molded, and a case where a complete container was formed was evaluated as 、, and a case where there was uneven thickness or white turbidity was evaluated as x.

Examples 1 to 4 PET resin production process A predetermined amount of terephthalic acid and ethylene glycol were charged into a stainless steel autoclave so that the glycol component had a molar ratio of 1.2 to the acid component, and was constantly heated at 250 ° C. The esterification reaction was performed under pressure. After the end of the esterification reaction,
A predetermined amount of a germanium dioxide catalyst was added, and
The polycondensation reaction was performed under a reduced pressure of 33 Pa. Germanium dioxide was added as a 0.8% by weight aqueous solution. Table 1 shows the physical properties of the obtained PET resin.

Production process of PTN resin A predetermined amount of 2,6-naphthalenedicarboxylic acid dimethyl ester and 1,3-propanediol are added to a stainless steel autoclave so that the molar ratio of the glycol component to the acid component is 1.8. The transesterification reaction was carried out at 230 ° C. and normal pressure using calcium acetate as a catalyst. After completion of the transesterification reaction, a predetermined amount of a germanium dioxide catalyst was added, and a polycondensation reaction was performed at 280 ° C. under a reduced pressure of 133 Pa. Germanium dioxide was added as a 0.8% by weight aqueous solution. Table 1 shows the physical properties of the obtained PTN resin.

Manufacturing Process of PEN Resin A predetermined amount of dimethyl 2,6-naphthalenedicarboxylate and ethylene glycol were charged into a stainless steel autoclave so that the glycol component had a molar ratio of 1.8 to the acid component, and calcium acetate was added. 230 as a catalyst
The transesterification reaction was performed at a normal temperature and a temperature. After the transesterification reaction, add a predetermined amount of germanium dioxide catalyst,
The polycondensation reaction was performed at 280 ° C. under a reduced pressure of 133 Pa. Germanium dioxide was added as a 0.8% by weight aqueous solution. Table 1 shows the physical properties of the obtained PEN resin.

Multilayer sheet molding A multilayer sheet molding machine (PUL) having three melt extruders.
(ACO), the raw materials shown in Table 2 were supplied to the respective extruders to form multilayer sheets having a thickness of 0.5 mm. Table 2 shows the physical properties of the obtained multilayer sheet.

Comparative Example 1 In Example 1, except that the PTN resin layer was not formed,
The same experiment as in Example 1 was performed. Table 3 shows the results.

Comparative Examples 2 and 3 The same experiment as in Example 1 was performed except that PEN resin was used instead of PTN resin. Table 3 shows the results.

[0032]

[Table 1]

[0033]

[Table 2]

[0034]

[Table 3]

Continued on the front page (72) Inventor Yumi Ito 4-1 Kanebocho, Hofu City, Yamaguchi Prefecture Kanebo Gosen Co., Ltd. F-term (reference) 4F071 AA45 AA46 AF07 AF30 AH05 BB06 BC01 4F100 AK41B AK42A BA02 BA03 BA06 BA25A BA25B GB16 GB23 JD02 JL01 JN01 YY00A YY00B 4J002 CF06W CF08X GF00 GG01 GG02 4J029 AA03 AB01 AC01 AE03 BA04 CC06A HA01 HB01 HB02

Claims (3)

[Claims] 1. A polyethylene terephthalate resin layer,
A polyester multilayer sheet comprising at least one polytrimethylene naphthalate resin layer. 2. The polyester multilayer sheet according to claim 1, wherein the weight ratio of the polytrimethylene naphthalate resin layer is at least 10% by weight of the entire polyester multilayer sheet. 3. A polytrimethylene naphthalate resin,
The polyester multilayer sheet according to claim 1 or 2, which is obtained by polycondensing 2,6-naphthalenedicarboxylic acid and 1,3-propanediol.