JPH11138705A - Thermoplastic resin multi-layer laminated sheet and multi-layer laminated container composed thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermoplastic resin multi-layer laminated sheet, which has interlaminer bonding properties, thermoformability, rigidity, and moisture vapor barrier characteristics, and has excellent flavor retaining characteristics of contents, and is preferable for using a container specially for oleaginous snack food or the like; and provide a multi-layer laminated container composed thereof. SOLUTION: A thermoplastic resin multi-layer laminated sheet is composed by laminating a styrene resin layer C on both sides of a moisture vapor barrier resin layer A with an ethylene-vinyl acetate copolymer resin layer B therebetween, where a saturated polyester resin layer E is laminated on at lest one side thereof with a block copolymer resin layer D, comprising a polymer block of substituted monovinyl aromatic hydrocarbon and a polymer block of conjugated diene, therebetween. A multi-layer container is composed by thermoforming the said sheet, where the saturated polyester resin layer E composes an innermost layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermoplastic resin multilayer laminated sheet and a multilayer laminated container comprising the same.
More specifically, a thermoplastic resin having interlayer adhesion, thermoformability, rigidity, and water vapor barrier properties, and having excellent flavor retention of contents when used as a container, and particularly suitable as a container for oil-based snack foods and the like. The present invention relates to a multilayer laminated sheet and a multilayer laminated container comprising the same.

[0002]

2. Description of the Related Art Conventionally, multilayer containers of paper / aluminum / polyethylene have been used as containers for oil-based snack foods and the like. However, since pinholes cannot be avoided, oxygen barrier properties and water vapor barrier properties are required. And the flavor of the contents is impaired. On the other hand, as a solution to this problem, a high-density polyethylene resin layer is formed between the outer layers of a styrene-based resin layer having excellent thermoformability and rigidity via an adhesive layer such as an ethylene-vinyl acetate copolymer resin. There is known a container made of a multilayer laminated sheet provided with a water vapor barrier property or the like to suppress deterioration in quality due to moisture absorption or the like of the content.

[0003] However, when the container made of the multilayer laminated sheet is used as a container for an oil-based snack food or the like, there is a problem that the styrene-based resin layer is attacked by the oil-based food and lowers the flavor of the contents. .

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned prior art in the multilayer laminated sheet, and has an interlayer adhesiveness, thermoformability, rigidity, and a water vapor barrier property. It is an object of the present invention to provide a thermoplastic resin multilayer laminated sheet having excellent flavor retention of contents when formed into a container and particularly suitable as a container for oil-based snack foods and the like, and a multilayer laminated container comprising the same.

[0005]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, further laminating a saturated polyester resin layer on the conventional multilayer laminated sheet;
The inventors have found that the above object can be achieved by interposing a specific resin in the lamination, and have reached the present invention. Therefore, the present invention provides ethylene-acetic acid on both surfaces of the water vapor barrier resin layer (A). A styrene-based resin layer (C) is laminated via a vinyl copolymer resin layer (B), and a block composed of a polymer block of a monovinyl-substituted aromatic hydrocarbon and a polymer block of a conjugated diene is provided on at least one surface thereof. A thermoplastic resin multilayer laminated sheet in which a saturated polyester resin layer (E) is laminated via a copolymer resin layer (D), and the sheet is formed by thermoforming the saturated polyester resin layer (E). The gist is a multilayer laminated container having an inner layer.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, the water vapor barrier resin constituting the water vapor barrier resin layer (A) includes:
Homopolymers of α-olefins having about 2 to 8 carbon atoms such as ethylene, propylene and butene-1, and those α-olefins and ethylene, propylene, butene-1,3-methylbutene-1, pentene-1,4- Methylpentene-1,
Carbon number 2 such as hexene-1, octene-1 and decene-1
Olefin-based resins such as copolymers with other α-olefins of up to about 20 are mentioned as typical examples, among which low-density polyethylene resin, medium-density polyethylene resin, high-density polyethylene resin, polypropylene resin, ethylene resin −
Propylene copolymer resins, propylene-ethylene copolymer resins, and the like are preferable, and in particular, the density is 0.941 to 0.1.
A high density ethylene resin such as a polyethylene resin or an ethylene-α-olefin copolymer resin having a high density of about 965 g / cm ³ is preferable.

In the present invention, the ethylene-vinyl acetate copolymer resin constituting the ethylene-vinyl acetate copolymer resin layer (B) is a copolymer mainly composed of ethylene and vinyl acetate. Therefore, those having a vinyl acetate content of 2 to 30% by weight are preferred.

In the present invention, the styrene resin constituting the styrene resin layer (C) is styrene,
homo- or copolymers of styrene-based monomers such as α-methylstyrene, p-methylstyrene, dimethylstyrene, pt-butylstyrene, chlorostyrene, etc., and copolymers of these styrene-based monomers with other monomers, for example, styrene -Acrylonitrile copolymer (AS resin), their styrenic monomers or further other monomers,
Graft polymer obtained by graft polymerization in the presence of a diene rubber polymer such as polybutadiene, styrene-butadiene copolymer, polyisoprene, polychloroprene, etc., for example, high impact polystyrene (HIPS resin), styrene-acrylonitrile graft polymer (ABS) And polystyrene (GPPS resin) and high-impact polystyrene (HIPS resin).

In the present invention, the block copolymer resin constituting the block copolymer resin layer (D) comprising a polymer block of a monovinyl-substituted aromatic hydrocarbon and a polymer block of a conjugated diene is a linear copolymer. Various, such as shape, radial branch shape, branch taper shape are known,
In the present invention, a linear or radially branched one is preferred.

Here, the linear block copolymer is represented by the general formula (XY) _n , X- (YX) _n , Y- (XY) _n
[Where X is a polymer block of a monovinyl-substituted aromatic hydrocarbon, Y is a polymer block of a conjugated diene, and n is 1 or more, generally an integer of 1 to 5.] Etc., and the radiation-branched block copolymer is represented by the general formula (XY) _n -Z, X _n- (YX) _m-
Z, Y _n- (XY) _m -Z wherein X and Y are the same as above, and Z is a residue of the polyfunctional coupling agent used for forming the radially branched block. ,
n and m are 1 or more, generally an integer of 1 to 5. ] Etc. are represented.

In this block copolymer, examples of the monovinyl-substituted aromatic hydrocarbon constituting the polymer block X include styrene, α-methylstyrene, p-methylstyrene, dimethylstyrene, vinylnaphthalene and the like. Examples of the conjugated diene constituting the polymer block Y include butadiene and isoprene. Examples of the polyfunctional coupling agent include those having three or more functions such as polyepoxides, polyisocyanates, polyaldehydes, polyketones, and polyamines.

In the present invention, among the above block copolymer resins, a styrene-butadiene block copolymer is preferred, and the styrene content is 60 to 90% by weight and the butadiene content is 40 to 10% by weight. Are particularly preferred.

In the present invention, the saturated polyester resin constituting the saturated polyester resin layer (E) includes ethylene glycol, propylene glycol,
Aliphatic diols such as 4-butanediol, neopentyl glycol, hexamethylene glycol, diethylene glycol, 1,1-cyclohexane dimethylol, 1,
Alicyclic diols such as 4-cyclohexane dimethylol,
Diol units such as aromatic diols such as bisphenol and 2,2-bis (4′-hydroxyphenyl) propane; aliphatic dicarboxylic acids such as oxalic acid, succinic acid, adipic acid, sebacic acid and undecadicarboxylic acid; Hydroterephthalic acid, an alicyclic dicarboxylic acid such as hexahydroisophthalic acid, terephthalic acid, isophthalic acid, a polycondensate with a dicarboxylic acid unit such as an aromatic dicarboxylic acid such as naphthalene dicarboxylic acid, as long as it shows thermoplasticity ,
It may be modified with a small amount of triol or tricarboxylic acid, and specifically, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyethylene terephthalate / isophthalate copolymer, etc., among which polyethylene terephthalate, A polyethylene terephthalate-based resin such as a polyethylene terephthalate / isophthalate copolymer is preferred.

The thermoplastic resin multi-layer laminated sheet of the present invention composed of the above-mentioned resins and the like has a styrene-based multilayer sheet having an ethylene-vinyl acetate copolymer resin layer (B) on both sides of a water vapor barrier resin layer (A). A resin layer (C) is laminated, and on at least one surface thereof, a saturated polyester resin is interposed via a block copolymer resin layer (D) comprising a polymer block of a monovinyl-substituted aromatic hydrocarbon and a polymer block of a conjugated diene. The layer (E) is laminated.

Here, when the saturated polyester resin layer (E) is not provided, the scent retention of the contents when a container is formed cannot be imparted, and when the block copolymer resin layer (D) is not provided. The problem is that when the lid material (for example, polyethylene terephthalate / aluminum / polyethylene multilayer laminated film) is peeled off as a container, the saturated polyester resin layer (E) on the container side peels off. When the water vapor barrier resin layer (A) is not provided, the water vapor barrier property is naturally insufficient, and when the styrene resin layer (C) is not provided, the thermoformability is inferior.

The layer structure of the thermoplastic resin multilayer sheet according to the present invention has a basic structure of E / D / C / B / A /
In addition to B / C, pulverized scraps generated in the manufacturing process of the multilayer laminated sheet and the manufacturing process of the multilayer laminated container described later were further laminated as a scrap layer (F).
C / F / B / A / B / C, E / D / C / B / A / B / F
/ C, E / D / C / F / B / A / B / F / C, etc. Further, a layer made of another resin may be provided between each layer for the purpose of imparting a new function. it can.

[0017] The scrap pulverized material may be used by forming one layer of the multilayer laminated sheet as described above, or may be mixed with the styrene resin layer (C).

The production of the thermoplastic resin multi-layer laminated sheet of the present invention is carried out by conventionally known sequential extrusion lamination, sandwich extrusion lamination, co-extrusion molding, a combination thereof, and the like. It is advantageous. In the co-extrusion molding, usually, the resin constituting each layer is melt-kneaded by each extruder, integrated and laminated using a feed block or the like, coextruded into a sheet shape from a T-die, and then cooled by a molding roll or the like. And solidify to form a multilayer laminated sheet. The temperature of the feed block and the T-die at the time of molding should be equal to or higher than the melting point of each resin in order to uniformly melt the resin constituting each layer, and equal to or lower than 80 ° C. higher than the melting point of each resin in order to suppress thermal deterioration. Is preferred.

The thickness of the thermoplastic resin multilayer sheet of the present invention is 0.1 to 5.0 mm, and the thickness of each layer is 10 to 1500 μm for the water vapor barrier resin layer (A), The united resin layer (B) is 10 to 500 each.
μm (each B layer does not have to have the same thickness), and the styrene resin layer (C) is a scrap layer (F).
25 to 4950 μm (each C layer and each F layer when a plurality of F layers are provided need not have the same thickness), and the block copolymer resin layer (D ) Is preferably 10 to 500 μm, and the thickness of the saturated polyester resin layer (E) is preferably about 10 to 500 μm.

The multilayer laminated container of the present invention is obtained by thermoforming the above-described thermoplastic resin multilayer laminated sheet, and has a saturated polyester resin layer (E) as the innermost layer. Here, examples of the thermoforming method include a conventionally known vacuum forming method, a pressurized air forming method, a vacuum pressurized air forming method, and a plug assisted forming method, and the like. The surface temperature is at least 50 ° C. lower than the melting point of the resin constituting each layer, and is 5 ° below the melting point.
It is preferable that the temperature be 0 ° C. or higher.

[0021]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist of the present invention. In the following examples and comparative examples, various physical properties and performance evaluation methods of the thermoplastic resin multilayer laminated sheet and the multilayer laminated container are based on the following methods.

(1) Water vapor barrier resin layer (A) and styrene
Strength between resin-based resin layer (C) or scrap layer (F)
Using a 10 mm wide strip sample collected from the multi-layer laminated sheet, the A layer and the C layer at one end thereof were peeled in advance according to JIS K 6854, and T was peeled off at a peel rate of 50 mm / min.
A shape peel test was performed.

(2) Styrene resin layer (C) and saturated polyether
According to JIS K 6854, the C layer at one end and the E layer were peeled in advance using a 10 mm wide strip sample taken from the adhesive strength multilayer laminated sheet between the stell resin layers (E) , and the peeling speed was 50 mm / min. At 1
An 80 degree peel test was performed.

(3) Using a water vapor permeable multilayer laminated sheet, the amount of water vapor transmission was measured at 25 ° C. and 90% RH in accordance with JIS Z0208.

(4) Sheets of 30 cm × 30 cm taken from the thermoformable multilayer laminated sheet were subjected to a surface temperature of 1 with a far-infrared ceramic heater from both sides.
After preheating to 30 to 220 ° C., the saturated polyester resin layer (E) becomes the inner layer of the container, and has a diameter of 5.5 cm.
A cylindrical container having a depth of 11 cm was subjected to plug-assist vacuum pressure forming, and a case where the designed container was formed was evaluated as ○, and the others were evaluated as ×.

(5) Retention of Flavor of Contents The container obtained in the evaluation of the thermoformability was filled with about 100 g of french fries, and the polyethylene side was covered with a lid made of a multilayer laminated film of polyethylene terephthalate / aluminum / polyethylene. Sealed as a sealing surface and 1 at 5 ° C
After storage for a week, randomly selected panelists evaluated the aroma, color, and taste against the same stored french fries separately. When 7 or more of the 10 panelists determined that there was no change, the evaluation was ○, and the others were evaluated as ×.

(6) Peelability of lid material The container obtained in the evaluation of the thermoformability was sealed with a lid material comprising a multilayer laminated film of polyethylene terephthalate / aluminum / polyethylene with the polyethylene side as a sealing surface, and then optionally sealed. The selected panelists peeled off the lid material, and when 7 or more of the 10 panelists could easily peel off the sealing surface, the evaluation was evaluated as ○, and the others were evaluated as ×.

Example 1 A high-density polyethylene resin (density 0.9
61 g / cm ³ , melt flow rate 1.0 g / 10
Minute, Mitsubishi Chemical Corporation “Mitsubishi Polyethylene HD: HY54
0 "), an ethylene-vinyl acetate copolymer resin (vinyl acetate content: 28% by weight, melt flow rate: 15.0 g / 10 min," LV67 "manufactured by Mitsubishi Chemical Corporation) as a resin for layer B.
0 "), a high-impact polystyrene resin (" 475D "manufactured by Asahi Kasei Corporation) as the resin for the C layer, and a styrene-butadiene block copolymer resin (styrene content 75% by weight, melt flow rate 8.0 g) as the resin for the D layer. / 1
0 minutes, "K-RESI" manufactured by Philips Spectro Chemical
NKR-05 "), and copolymerized polyethylene terephthalate resin (" PET-G 6763 "manufactured by Eastman Chemical Co., Ltd.) as a resin for the E layer, and each was melt-kneaded with five single-screw extruders and set at 230 ° C. The laminate is integrated by a feed block, coextruded in a sheet form from a T-die set at 230 ° C., and cooled and solidified by a forming roll composed of three polishing rolls to form a copolymerized polyethylene terephthalate resin layer ( E) 100 μm / styrene-butadiene block copolymer resin layer (D) 100 μm / high impact polystyrene resin layer (C) 475 μm / ethylene-vinyl acetate copolymer resin layer (B) 50 μm / high density polyethylene resin layer (A) 300 μm / ethylene-vinyl acetate copolymer resin layer (B) 50 μm / high-in Transfected polystyrene resin layer (C) 475, a layer structure of 5 or 7 layers, to produce a thermoplastic resin multilayer laminated sheet of the entire thickness of 1550.

With respect to the obtained multilayer laminated sheet, the adhesive strength between the high-density polyethylene resin layer (A) and the high-impact polystyrene resin layer (C), the high-impact polystyrene resin layer (C) and the copolymerized polyethylene terephthalate resin layer (E ) And the water vapor permeability were measured. Separately, a multilayer laminated container was manufactured from the obtained multilayer laminated sheet by the thermoforming method described in the above evaluation method, and the thermoformability at that time was evaluated.

Further, regarding the obtained multilayer laminated container,
The flavor retention of the contents and the releasability of the lid material were evaluated. The results are shown in Table 1.

Example 2 Scraps of the multilayer laminate sheet produced during the production of Example 1 were further laminated, and a copolymerized polyethylene terephthalate resin layer (E) 100 μm / styrene-butadiene block copolymer resin layer (D ) 100 μm / high impact polystyrene resin layer (C) 100 μm / scrap layer (F) 375 μm / ethylene-vinyl acetate copolymer resin layer (B) 50 μm / high density polyethylene resin layer (A)
Example 1 was the same as Example 1 except that the layer structure was composed of 9 layers of 6 types of 300 μm / ethylene-vinyl acetate copolymer resin layer (B) 50 μm / scrap layer (F) 375 μ / high impact polystyrene resin layer (C) 100 μm. Similarly, a multilayer laminated sheet and a multilayer laminated container were manufactured, and various physical properties and performances were similarly evaluated. The results are shown in Table 1.

Comparative Example 1 A multilayer laminated sheet and a multilayer laminated container were produced in the same manner as in Example 1 except that the styrene-butadiene block copolymer resin layer (D) was not provided. Various physical properties and performances were evaluated, and the results are shown in Table 1.

Comparative Example 2 The procedure of Example 1 was repeated except that the copolymerized polyethylene terephthalate resin layer (E) and the styrene-butadiene block copolymer resin layer (D) were not provided. A laminated sheet and a multilayer laminated container were manufactured, and various physical properties and performances were similarly evaluated. The results are shown in Table 1.

Comparative Example 3 A container was produced in the same manner as in Example 1 except that a single-layer sheet was produced from the same copolymerized polyethylene terephthalate resin used in Example 1, and various physical properties and performances were evaluated in the same manner. The results are shown in Table 1.

[0035]

[Table 1]

[0036]

According to the present invention, in addition to having interlayer adhesiveness, thermoformability, rigidity, and water vapor barrier properties, it is excellent in flavor retention of contents when used as a container. The present invention can provide a thermoplastic resin multilayer laminated sheet suitable as a container, and a multilayer laminated container comprising the same.

Continuation of the front page (51) Int.Cl. ⁶ Identification symbol FI B32B 27/36 B32B 27/36 B65D 1/09 B65D 1/00 B (72) Inventor Katsuto Takahashi 2031-2, Akachi, Ogasa-machi, Ogasa-gun, Shizuoka Prefecture 2 No. Ikoma Chemical Industry Tokai Plant

Claims (4)

[Claims] A styrene resin layer (C) is laminated on both sides of a water vapor barrier resin layer (A) via an ethylene-vinyl acetate copolymer resin layer (B), and at least one surface of the styrene resin layer (C) is A thermoplastic resin comprising a saturated polyester resin layer (E) laminated via a block copolymer resin layer (D) comprising a polymer block of a substituted aromatic hydrocarbon and a polymer block of a conjugated diene. Multi-layer laminated sheet. 2. The thermoplastic resin multilayer sheet according to claim 1, wherein the water vapor barrier resin layer (A) comprises a high-density ethylene-based resin. 3. The thermoplastic resin multilayer sheet according to claim 1, wherein the block copolymer resin layer (D) comprises a styrene-butadiene block copolymer resin having a styrene content of 60 to 90% by weight. 4. A multilayer laminated container obtained by thermoforming the thermoplastic resin multilayer laminated sheet according to any one of claims 1 to 3, and having a saturated polyester resin layer (E) as an innermost layer.