JPH10296936A - Laminated polyester sheet and packaging vessel comprising the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminated polyester sheet which is excellent in transparency, heat resistance, workability, etc., free from being whitened even though retort treatment is carried out, and excellent in gas barrier properties, and a packaging vessel prepared by using that. SOLUTION: A pair of skin layers 3 on both front and rear surfaces are formed of first polyester composed of 25 to 55 wt.% of polyethylene terephthalate or polyester (A) having that principally, and 75 to 45 wt.% of polyarylate (R). Further, a core layer 2 pinched between a pair of the skin layers 3 is formed of second polyester composed of 60 to 90 wt.% of polyethylene terephthalate or polyester (A) having that principally, and 40 to 10 wt.% of polyethylene-2,6-naphthalate or polyester (C) having that principally.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated polyester sheet having good transparency, heat resistance, workability and the like and excellent gas barrier properties, and a packaging container using the same. The present invention relates to the polyester sheet and the packaging container which can be suitably used for food and beverage containers such as jam, jelly, pudding, yogurt and the like which require retort sterilization property.

[0002]

2. Description of the Related Art Sheets forming packaging containers used for foods and beverages have conventionally been required to be excellent in processability and mechanical properties. It is required to have transparency so that the food can be easily seen, and heat resistance such that high-temperature filling of foods and drinks and heating cooking by a microwave oven or the like can be performed.

[0003] In addition, a packaging container made of the above-mentioned sheet is subjected to a so-called retort sterilization treatment (hereinafter referred to as "retort treatment") in order to completely sterilize microorganisms after filling the inside with food and beverages. Retort treatment is generally about 90
It is required to be excellent in retort treatment resistance so as not to deteriorate such as thermal deformation because it is performed for about 30 minutes in warm water of ° C.

[0004] A laminated sheet has been proposed as satisfying the above conditions.
No. 943 uses polyethylene terephthalate (hereinafter referred to as “PET”) having excellent transparency and processability for a core layer, and a pair of skin layers on both sides thereof is made of PET.
A sheet in which a polyester made of PET having a higher glass transition point and polyarylate (hereinafter referred to as “PAR”) is laminated is disclosed.

However, when this laminated sheet is processed into a container for food and drink such as jam, and subjected to retort treatment, there is a problem that although the container is not thermally deformed, the container is slightly whitened. In addition, food and beverage containers have excellent gas barrier properties that cut off contact with oxygen in the air and completely seal off the outside air so that chilled storage and long-term storage at room temperature are possible. Although required, the food and beverage container comprising the above-mentioned laminated sheet has insufficient gas barrier properties.

[0006]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems, has good transparency, heat resistance, workability, etc., does not cause whitening even when subjected to retort treatment, and further has a gas barrier property. An object of the present invention is to provide an excellent laminated polyester sheet and a packaging container using the same.

[0007]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, have reached the present invention. That is, according to the present invention, a pair of skin layers on both the front and back surfaces is made of PET or a polyester (A) having the main content of 25 to 55 wt% and a polyarylate (B) of 75 to 55 wt%.
The core layer sandwiched between the pair of skin layers is made of PET or polyester (A) 60 to 90 w mainly composed of 45% by weight of the first polyester.
The present invention provides a laminated polyester sheet characterized by being formed of a second polyester composed of t% and polyethylene-2,6-naphthalate or 40 to 10% by weight of a polyester (C) mainly containing the same. Things.

As described above, according to the present invention, PET or a polyester (A) containing 25 to 55% by weight of a polyester and a polyarylate (B) are formed on a pair of skin layers on both front and back surfaces.
The first polyester consisting of 75 to 45 wt% is used, and PET or polyester (A) 60 to 90 w mainly composed of PET is provided on the core layer sandwiched between the pair of skin layers.
The heat resistance of the laminated sheet is improved by using the second polyester consisting of t% and polyethylene-2,6-naphthalate or 40 to 10% by weight of the polyester (C) mainly containing the same. Further, since the core layer contains polyethylene-2,6-naphthalate having a high gas barrier property or polyester (C) mainly composed of the same, the gas barrier property of the laminated sheet is improved.

Therefore, the packaging container made of the laminated sheet does not whiten even after the retort treatment,
It has good gas barrier properties and excellent heat resistance and transparency.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The laminated sheet of the present invention is formed of a pair of skin layers on both sides, and a core layer sandwiched between the pair of skin layers.

As the skin layer constituting the laminated sheet of the present invention, PET or a polyester (A) composed mainly of PET is 25 to 55 wt% and PAR (B) is 75 to 45 wt%.
% Of the first polyester. If the blending ratio of PAR is less than 45 wt%, heat resistance will be low, and the container made of the sheet will be deformed during the retort treatment. On the other hand, if the mixing ratio of PAR exceeds 75% by weight, the processability of molding the laminated sheet into a container or the like will be reduced.

As the core layer constituting the laminated sheet, P
ET or polyester (A) 60-based mainly on ET
It is necessary to use a second polyester composed of 90% by weight and polyethylene-2,6-naphthalate (hereinafter referred to as "PEN") or 40 to 10% by weight of a polyester (C) mainly containing the same. Polyester (C)
If the compounding ratio is less than 10% by weight, the gas barrier property becomes inferior.
The container is whitened, resulting in poor appearance. If the blending ratio of the polyester (C) exceeds 40% by weight, the flexural modulus of the laminated sheet will decrease.

The core layer may further contain PAR (B) of 25 parts by weight or less based on 100 parts by weight of the second polyester. With such a configuration, the heat resistance can be improved without lowering the transparency, workability, and gas barrier properties of the laminated sheet. Further, the packaging container made of the laminated sheet has good heat resistance and does not whiten even when retorted. However, P
If the compounding ratio of AR (B) exceeds 25 parts by weight, the flexural modulus of the laminated sheet tends to decrease, and furthermore, the gas barrier property tends to decrease.

The weight ratio between the pair of skin layers and the core layer is as follows:
(Total of a pair of skin layers) / (core layer) = 3 / 97-4
It is preferably 0/60. When the weight ratio between the pair of skin layers and the core layer exceeds 40/60, the thickness of the skin layer increases, so that it is difficult to uniformly apply heat to the skin layer during the forming process, and the laminated sheet is formed into a container or the like. This is not preferable because the processability at the time of performing the process is remarkably reduced and the gas barrier property is also poor. If the weight ratio between the pair of skin layers and the core layer is smaller than 3/97, the thickness of the skin layer becomes small, so that whitening and deformation of the container during retort treatment cannot be suppressed.

The PET or the polyester (A) containing the same as the main component in the present invention is obtained by a melt polycondensation reaction or a solid phase polymerization of a terephthalic acid component and an ethylene glycol component as main components. The limiting viscosity is desirably in the range of 0.50 to 1.20.

In PET, in addition to the above components, phthalic acid,
Aromatic dicarboxylic acid components such as isophthalic acid, 2,5-dibromoterephthalic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-diphenyldicarboxylic acid, diphenylsulfondicarboxylic acid, trimellitic acid, trimesic acid, pyromellitic Aromatic polycarboxylic acid components such as acids, succinic acid, adipic acid, sebacic acid, azelaic acid, decanedicarboxylic acid, maleic acid, aliphatic dicarboxylic acid components such as itaconic acid, diethylene glycol, triethylene glycol,
Propylene glycol, 1,2-propanediol, 1,3
-Aliphatic diol components such as propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol and polyethylene glycol, and aliphatic such as glycerin, trimethylolpropane and pentaerythritol Polyhydric alcohol component, 1,4
Alicyclic diol components such as -cyclohexanedimethanol and 1,4-cyclohexanediethanol, and aromatic diol components such as p-xylylene glycol and ethylene oxide adducts of bisphenol A and bisphenol S;
A small amount (at most about 10 mol%) may be copolymerized as long as the characteristics of T are not impaired. PAR in the present invention
(B) is an aromatic polyester obtained by polymerization of an aromatic dicarboxylic acid component represented by the following formula and a bisphenol represented by the following formula, and has an intrinsic viscosity of 0.40 to 1.00. desirable.

[0017]

Embedded image

HO—Ar ² —X—Ar ² —OH (wherein Ar ² is the same as the formula. X is a methylene group, a sulfone group, a carbonyl group, a cyclohexylene group, a sulfur atom, or an oxygen atom Wherein the hydrogen atom of the methylene group may be substituted with a methyl group.) Preferred examples of the aromatic dicarboxylic acid component include terephthal chloride and / or isophthal chloride. In particular, terephthal chloride and isophthal chloride include Is preferred from the viewpoint of melt processability and overall performance of the obtained PAR. In the case of such a mixture, the mixing ratio can be arbitrarily selected, but terephthal chloride / isophthal chloride = 9/1 to 1/9 (molar ratio) is preferable, and in particular, from the viewpoint of balance between melt processability and performance, 7 is preferred.
/ 3 to 3/7 (molar ratio), and more preferably 1/1 (molar ratio).

The bisphenols represented by the formulas include bisphenol A [2,2-bis (4-hydroxyphenyl) propane] and 2,2-bis (4-hydroxy-3,5
-Dimethylphenyl) propane, 2,2-bis (4-hydroxy-3,5-dichlorophenyl) propane, 2,2-bis (4-hydroxy-3,5-dibromophenyl) propane, bisphenol S [4,4 ' -Dihydroxydiphenylsulfone), 4,4'-dihydroxydiphenylether,
4,4'-dihydroxydiphenyl sulfide, 4,4'-dihydroxydiphenyl ketone, 4,4'-dihydroxydiphenylmethane, 1,1-bis (4-hydroxyphenyl)
Ethane, 1,1-bis (4-hydroxyphenyl) cyclohexane and the like are mentioned, and bisphenol A is particularly preferred. These may be used alone or in combination of two or more. Further, the above bisphenols are para-forms, but ortho- or meta-form bisphenols may be used, and ethylene glycol, propylene glycol or the like may be used in combination with these bisphenols.

A preferred example of PAR is terephthalic acid chloride / isophthalic acid chloride = 1/1 (molar ratio).
And U-Polymer (trade name) manufactured by Unitika Ltd. obtained by interfacial polymerization of phenol and bisphenol A.

The PEN or the polyester (C) comprising the same as the main component in the present invention is obtained by a melt polycondensation reaction or a solid phase polymerization of a 2,6-naphthalenedicarboxylic acid component and an ethylene glycol component as main components. It is desirable that the intrinsic viscosity is in the range of 0.40 to 1.0.

In addition to the above components, PEN contains phthalic acid,
Aromatic dicarboxylic acid components such as isophthalic acid, terephthalic acid, 4,4'-diphenyldicarboxylic acid, diphenylsulfonedicarboxylic acid, oxalic acid, malonic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, decanedicarboxylic acid, and maleic Acids, aliphatic dicarboxylic acid components such as itaconic acid, diethylene glycol, triethylene glycol, propylene glycol, 1,2-propanediol,
1,3-propanediol, 1,4-butanediol, 1,5
-Aliphatic diol components such as pentanediol, 1,6-hexanediol and neopentyl glycol; alicyclic diol components such as 1,4-cyclohexanedimethanol and 1,4-cyclohexanediethanol; ethylene oxide of bisphenol A and bisphenol S An aromatic diol component such as an adduct may be copolymerized in a small amount (at most about 10 mol%) as long as the properties of PEN are not impaired.

As a method for producing the first polyester constituting the skin layer and the second polyester constituting the core layer in the present invention, conventionally known methods can be employed.

For example, as a method for producing the first polyester, PET or a polyester (A) mainly composed of PET, PAR (B), and a catalyst are charged into a reactor, and the mixture is melt-heated under reduced pressure to transesterify. There is a method in which the reaction is carried out, and when the reaction is completed, the mixture is discharged from the reactor to form a pellet. At this time, it is preferable to use a compound of an alkali metal such as sodium acetate, sodium hydroxide, potassium hydroxide or the like as a catalyst.

Further, PET or a polyester (A) containing the same as a main component, PAR (B), and the above catalyst are mixed using various blenders such as a turn-blender, and then melt-kneaded to perform a transesterification reaction. And a pelletizing method using a single-screw extruder or a twin-screw extruder (hereinafter, this method is referred to as a “melt blending method”).
Furthermore, there is also a method of simply blending PET or a polyester (A) mainly composed of PET and PAR (B) at the time of melt molding (hereinafter, this method is referred to as “molding blending method”). More preferably, the polyester is produced using a melt blending method.

In order to produce the second polyester constituting the core layer, PET or a polyester (A) containing the same as a main component, PEN or a polyester (C) containing the same as a main component, and a catalyst are used. A pellet may be formed in the same manner as described above. In addition, PAR (B) may be blended with the second polyester as needed within the above-mentioned predetermined range.

The laminated polyester sheet of the present invention can be produced by directly applying the molding method used for the conventional PET-based polyester. For example, the first polyester and the second polyester are each formed by a predetermined method. It can be obtained by melt-extrusion with a multilayer extrusion sheet forming apparatus equipped with a T-die and cooling with a cooling roller while adjusting to a weight ratio.

The thickness of the laminated sheet is preferably in the range of 0.5 to 1.2 mm, more preferably 0.7 to 0.9 m.
m is good. The thickness of the container obtained by compression molding or vacuum molding of the laminated sheet is preferably 0.2 to 0.45 mm in average thickness. Particularly preferably 0.25 to 0.35 m
m is good.

The laminated sheet of the present invention can have not only a three-layer structure including a core layer and a pair of skin layers, but also a five-layer structure in which a skin layer is disposed in the middle. In the present invention, in order to further improve the gas barrier property, an ethylene / vinyl alcohol copolymer having a high gas barrier property, polymethaxylylene adipamide, amorphous A gas barrier layer such as a polyamide resin may be provided. In this case, as an adhesive layer for bonding the core layer and the gas barrier layer to the outside of the gas barrier layer, a maleic anhydride graft-modified ethylene / vinyl acetate copolymer, high-density polyethylene, or low-density polyethylene is used. Alternatively, it is preferable to use polypropylene or the like.

Further, in the present invention, it is possible to effectively recycle the waste polyester generated when the laminated polyester sheet is formed and processed. In the present invention, all or one of the polyester constituting the core layer and the skin layer can be recycled. By using such a recycled polyester for the part, the cost can be reduced. In the present invention, the laminated polyester sheet is formed and processed as described above to prepare a packaging container for food or drink such as jam or jelly. As the lid of such a packaging container, any material may be used as long as it has heat resistance and gas barrier properties, for example, a plastic material or a metal material, or a laminate material of a plastic layer and a metal layer And a laminated material having a metal layer as a core layer and a plastic as a skin layer. A laminate of a plastic layer and a metal layer, or a laminate having a metal layer as a core layer and a plastic as a skin layer can be obtained by a method of bonding using an adhesive, an extrusion laminating method, or a co-extrusion method.

In order to bond the container body and the lid, it is possible to use a method in which an edge is formed around the mouth of the container body and a sealing material for heat bonding is arranged on the edge. . As a sealing material, it has easy peel properties,
It is preferable to use a heat-adhesive film having a softening point lower than that of the laminated polyester sheet constituting the container body. In addition, about the peel strength of a heat adhesive film, since it has an easy peel property as mentioned above, what has a peel strength of about 1.0-2.0 kg / 15mm, especially 1.5-1. Those having a peel strength of about 0.8 kg / 15 mm are preferred. Further, as the thickness of the heat-adhesive sealing material, a thickness of about 20 to 60 μm is appropriate.

Examples of the above-mentioned heat-adhesive film include a polyolefin-based film, a modified polyester-based film, and a film made of a modified polyolefin modified with a polymerizable monomer represented by styrene and the like. Examples include DIFFEREN E7700T and PP-100 manufactured by Dainippon Ink and Chemicals, and ADMER XE070 and NE050 manufactured by Tosero.

[0033]

Next, the present invention will be specifically described based on examples, but the present invention is not limited to only these examples. The measurement of various physical properties in the examples was carried out by the following methods.

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

(2) Processability of laminated sheet: Thermoforming was performed at a sheet temperature of 160 ° C. using an unstretched laminated polyester sheet, and [height (L)] / [diameter (D)] = 1 / When the container (jam container) of No. 2 was molded, the percentage of defective such as unformed or whitened containers due to cracking or poor stretching of the container was 1% or less. Those with 5% or more were evaluated as x.

It should be noted that non-forming due to poor stretching is usually performed
The bottom edge of the part should be sharp
However, the bottom of the molded product
A rounded shape. In addition, the volume during molding
Container whitening refers to a balance between the stretching speed and the sheet temperature during stretching.
When the quality is poor, crystallization of the core layer occurs and part of the container becomes white.
Means to make (3) Oxygen gas barrier property of laminated sheet: MOCON
Oxygen Permeability Analyzer (OX-TRON-100)
The measured value of the oxygen gas transmission coefficient at 1.5cc / mm / m ^Two・ 24h
r · atm ◎ 1.5cc · mm / m^Two・ 24hr ・ at
3cc ・ mm / m larger than m^Two・ 24hr ・ It is smaller than atm
○, 3cc ・ mm / m^Two・ Large than 24hr ・ atm 10cc ・
mm / m^Two・ 24hr ・ atm less than 10cc ・ mm / m
^Two・ 24hr ・ atm or more was evaluated as ×.

(4) Heat resistance of laminated sheet: laminated polyester
After heat treatment of the tel sheet, the sheet's flexural modulus and opacity
The degree of heat resistance was determined by measuring the degree. What
The flexural modulus is measured based on ASTM D790.
And the flexural modulus after heat treatment is 5 × 10^FiveCan hold Pa
Temperature at 95 ° C for 30 minutes.
Even after the treatment, the bending elastic modulus is 5 × 10^FivePa or more
熱, heat treatment at 75 ° C or higher and lower than 95 ° C for 30 minutes
The bending elastic modulus is 5 × 10 ^FivePa or more
When heat-treated at 75 ° C for less than 30 minutes
Only the flexural modulus is 5 × 10^FiveThose that are above are indicated by ×
did.

The degree of white turbidity of the sheet was visually determined. If the sheet was not heat turbid at 95.degree. C. for 30 minutes or more and had good heat resistance, it was evaluated as .largecircle., And heat treated at 80.degree. C. for 30 minutes or more. Even when the sample did not become cloudy and the heat resistance was normal, the sample was evaluated as Δ, and when the sample was heat-treated at 80 ° C. for less than 30 minutes and evaluated as poor, the sample was evaluated as x.

(5) Transparency of the container body: The transparency of the container body was evaluated by the haze value of the molded container. That is, ◎ indicates that the haze value measured by a color measuring system manufactured by Nippon Denshoku Co. was 3 or less, ○ indicates that the haze value was greater than 3 and 5 or less, Δ indicates that the haze value was greater than 5 and was less than 10. Are represented by ×.

(6) Retort resistance: After the container was subjected to retort treatment with warm water at 90 ° C. for 30 minutes, the degree of white turbidity and the change in shape were measured. When the haze value measured with a color measuring system manufactured by Nippon Denshoku Co., Ltd. is 3 or less, ◎ is indicated when the haze value is larger than 3 and smaller than 5,
When the value was larger than 10 and when it was 10 or more, it was evaluated as x. Shape change: when the volume change rate is 1% or less, ○ when the rate is greater than 1% and less than 5%, and 5%
The above time was evaluated as x.

Example 1 PET having a limiting viscosity of 0.81 (manufactured by Unitika Ltd.) and PAR having a limiting viscosity of 0.68 (manufactured by Unitika Ltd., U-polymer) were blended in the proportions shown in Table 1 and sodium acetate was added thereto. 0.06% by weight, and a twin-screw extruder (PC manufactured by Ikegai Iron Works, PC
Using M-30), melt-blending at 280 to 320 ° C (the higher the ratio of PAR, the higher the temperature is set), then extruding into strands to produce the first polyester pellets that constitute the skin layer. did.

Further, PET having a limiting viscosity of 0.81 (manufactured by Unitika) and PEN having a limiting viscosity of 0.61 (manufactured by Eastman Chemical Co., Ltd., product number 14911) were blended in the proportions shown in Table 1 and acetic acid was added thereto. 0.06% by weight of sodium was added, and 270 to 280 ° C.
, And extruded into strands to produce second polyester pellets constituting the core layer.

[0043]

[Table 1]

Next, using a multilayer extruded sheet forming apparatus equipped with a T-die, the first polyester forms a skin layer,
The sheet was extruded such that the weight ratio between the pair of skin layers and the core layer became the weight ratio shown in Table 1 so that the second polyester formed the core layer, and the sheet was cooled with a cooling roller at 30 ° C. A laminated polyester sheet having a thickness of 0.8 mm was obtained.

The extrusion conditions were as follows: core layer side cylinder temperature: 270 to 300 ° C .; skin layer side cylinder temperature: 275 to 310 ° C .; junction block, feeder block and die temperatures: 270 to 280 ° C. Hereinafter, the same conditions were used in other examples,
The temperature was set higher as the proportion of PAR charged increased.

As shown in FIG. 1, the obtained laminated sheet 1
The second polyester formed the core layer 2, and a pair of skin layers 3 made of the first polyester were formed on both surfaces thereof. The thickness of each of the skin layers 3 was equal, and the thickness of the laminated sheet 1 was 0.8 mm.

Table 1 shows the physical properties and the like of the obtained sheet. The obtained laminated sheet was thermoformed at a sheet temperature of 160 ° C. to prepare a container body 4 of a jam container having an L / D = 1/2 as shown in FIG. To the edge formed around the mouth of the container body 4, Admer XE070 manufactured by Tosero Corporation was thermally bonded as a sealing material 5, and the lid 6 was attached to the container body 4 via the sealing material 5.

Table 1 shows the physical properties and the like of the obtained container. Example 2 The proportion of PET / PEN charged and the weight ratio between the skin layer and the core layer were as shown in Table 1. Otherwise, a laminated sheet and a jam container were produced in the same manner as in Example 1.

Table 1 shows the physical properties and the like of the obtained laminated sheet and container.
Shown in

Example 3 5 parts by weight of PAR were further blended with 100 parts by weight of the second polyester composed of PET and PEN. First
The same polyester as that used in Example 1 was used, and the weight ratio between the skin layer and the core layer was as shown in Table 1. Otherwise, a laminated sheet and a jam container were produced in the same manner as in Example 1.

Table 1 shows the physical properties and the like of the obtained laminated sheet and container.
Shown in

Example 4 The charge ratio of PET / PEN was as shown in Table 1. Otherwise, a laminated sheet and a jam container were produced in the same manner as in Example 3.

Table 1 shows the physical properties and the like of the obtained laminated sheet and container.
Shown in

Example 5 Table 1 shows the charging ratio of PET / PEN and the charging amount of PAR.
As shown. Otherwise, a laminated sheet and a jam container were produced in the same manner as in Example 3.

Table 1 shows the physical properties and the like of the obtained laminated sheet and container.
Shown in

Example 6 The charging ratio of PET / PEN, the charging amount of PAR, and the weight ratio between the skin layer and the core layer were as shown in Table 1. Otherwise, a laminated sheet and a jam container were produced in the same manner as in Example 3.

Table 1 shows the physical properties and the like of the obtained laminated sheet and container.
Shown in

Example 7 The charging ratio of PET / PAR and the weight ratio between the skin layer and the core layer were as shown in Table 1. Otherwise, a laminated sheet and a jam container were produced in the same manner as in Example 6.

Table 1 shows the physical properties and the like of the obtained laminated sheet and container.
Shown in

Examples 8 to 9 The charging ratio of PET / PAR, the charging ratio of PET / PEN, and the weight ratio between the skin layer and the core layer were as shown in Table 1. Otherwise, a laminated sheet and a jam container were produced in the same manner as in Example 6.

Table 1 shows the physical properties and the like of the obtained laminated sheet and container.
Shown in

Example 10 The charge ratio of PET / PAR and the first polyester 10
The amount of PAR charged to 0 parts by weight and the weight ratio between the skin layer and the core layer were as shown in Table 1. Otherwise, a laminated sheet and a jam container were produced in the same manner as in Example 6.

Table 1 shows the physical properties and the like of the obtained laminated sheet and container.
Shown in

In Examples 1 and 2, the charging ratio of PET / PEN constituting the polyester of the core layer was within the range of the present invention, so that both were very excellent in gas barrier properties. Further, since the preparation ratio of PET / PAR constituting the polyester of the skin layer and the weight ratio between the skin layer and the core layer were within the range of the present invention, the transparency was very excellent. In addition, all showed good laminated sheet characteristics and container characteristics. In Examples 3 to 10, P was added to 100 parts by weight of the first polyester in the core layer.
Since AR was blended in an amount of 25 parts by weight or less, the blending ratio of PEN to the entire core layer was small, and the gas barrier properties were slightly inferior to those in Examples 1 and 2. However, the gas barrier properties were sufficient for a jam container. It had the following. In addition, since PAR having high heat resistance was blended in the core layer, heat resistance was improved, and excellent container characteristics without whitening even when subjected to retort treatment were exhibited. Furthermore, other laminated sheet characteristics and container characteristics were also good.

Comparative Example 1 The core layer was made of PET alone, and the weight ratio between the skin layer and the core layer was as shown in Table 2. Otherwise, a laminated sheet and a jam container were produced in the same manner as in Example 1.

Table 2 shows the physical properties and the like of the obtained laminated sheet and container.
Shown in

[0067]

[Table 2]

Comparative Example 2 The polyester of the core layer was made of PET alone, and the amount of PAR charged to 100 parts by weight of the second polyester constituting the core layer was higher than the upper limit of the present invention. Further, the first polyester constituting the skin layer has a PET charging ratio smaller than the lower limit of the invention. Table 2 shows the weight ratio between the skin layer and the core layer. Otherwise, a laminated sheet and a jam container were produced in the same manner as in Example 1.

Table 2 shows the physical properties and the like of the obtained laminated sheet and container.
Shown in

Comparative Example 3 In the first polyester constituting the skin layer, PE was used.
The charged amount of T was made larger than the upper limit of the present invention. And
Otherwise, in the same manner as in Example 4, a laminated sheet and a jam container were produced.

Table 2 shows the physical properties and the like of the obtained laminated sheet and container.
Shown in

Comparative Example 4 In the weight ratio of the skin layer to the core layer, the amount of the skin layer was larger than the upper limit of the present invention. Otherwise, a laminated sheet and a jam container were produced in the same manner as in Example 6.

Table 2 shows the physical properties and the like of the obtained laminated sheet and container.
Shown in

Comparative Example 5 The weight ratio of the skin layer to the core layer was such that the amount of the skin layer was larger than the upper limit of the present invention. Further, the charge ratio of PET / PEN and the charge amount of PAR for forming the core layer were as shown in Table 2. Otherwise, a laminated sheet and a jam container were produced in the same manner as in Comparative Example 4.

Table 2 shows the physical properties and the like of the obtained laminated sheet and container.
Shown in

Comparative Example 6 The mixing ratio of PAR to 100 parts by weight of the first polyester in the core layer was made larger than the upper limit of the present invention as shown in Table 2 with respect to the PET / PEN charging ratio. PET
The charging ratio of / PAR and the weight ratio between the skin layer and the core layer were as shown in Table 2. Otherwise, a laminated sheet and a jam container were produced in the same manner as in Comparative Example 5.

Table 2 shows the physical properties and the like of the obtained laminated sheet and container.
Shown in

In Comparative Example 1, the second polyester was made of PET.
Since the laminate sheet was composed of only the above, the obtained laminated sheet was inferior in heat resistance. Therefore, the jam container formed with the sheet was inferior in retort resistance.

In Comparative Example 2, as in Comparative Example 1, the second polyester was composed of only PET, but the core layer was made of PA.
Since a large amount of R was blended, the retort resistance of the jam container was improved. However, since PEN was not blended in the core layer, the gas barrier property was slightly inferior. Furthermore, since the amount of PAR constituting the skin layer was large, the processability and heat resistance of the laminated sheet were also poor.

In Comparative Example 3, since the amount of PAR constituting the skin layer was small, the heat resistance was slightly inferior, and the retort resistance of the jam container was also inferior. Comparative Example 4,
In Comparative Example 5, since the skin layer was too thick, it was difficult to uniformly apply heat to the skin layer during the molding process, and the workability was poor. Further, since the core layer became thin, the gas barrier property was slightly inferior.

In Comparative Example 6, since the mixing ratio of PAR to the second polyester was too large, the elasticity of the laminated sheet was lowered and the processability was slightly inferior. In addition, the gas barrier properties and heat resistance were poor.

[0082]

According to the present invention, by forming the skin layer of the first polyester and the core layer of the second polyester, a laminated sheet having good transparency, heat resistance, workability and the like can be obtained. Obtainable. Further, since PEN having a high gas barrier property is blended in the core layer, the obtained laminated sheet has a high gas barrier property.

A packaging container formed from such a laminated sheet has high transparency, excellent heat resistance, does not whiten even when subjected to retort treatment, and has high gas barrier properties. It is. Therefore, it is possible to provide a packaging container that can be suitably used for a food or beverage container such as jam or jelly.

[Brief description of the drawings]

FIG. 1 is a sectional view of a laminated sheet according to the present invention.

FIG. 2 is a sectional view of a packaging container according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Laminated sheet 2 Core layer 3 Skin layer 4 Container main body 5 Sealing material 6 Lid

Claims (4)

[Claims] 1. A pair of skin layers on both the front and back sides is made of polyethylene terephthalate or 25 to 55% by weight of a polyester (A) mainly composed of polyethylene terephthalate and polyarylate (B) 75
The core layer sandwiched between the pair of skin layers is made of polyethylene terephthalate or 60 to 90 wt% of a polyester (A) mainly containing polyethylene terephthalate or polyethylene-2, 45 wt%. 6-
A laminated polyester sheet comprising naphthalate or a second polyester comprising 40 to 10% by weight of a polyester (C) containing the same as a main component. 2. The polyester according to claim 1, wherein the core layer is formed of a polyester further containing 25 parts by weight or less of polyarylate (B) with respect to 100 parts by weight of the second polyester. Laminated polyester sheet. 3. The weight ratio between the pair of skin layers and the core layer is as follows:
(Total of a pair of skin layers) / (core layer) = 3 / 97-4
The laminated polyester sheet according to claim 1 or 2, wherein the ratio is 0/60. 4. A packaging container comprising the laminated polyester sheet according to claim 1.