JP2000264367A - Easily unsealable container - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an easily unsealable container wherein in a packaging container having a polypropylene resin on a heat-sealed surface, particularly in a container body having a polypropylene resin on its heat-sealed surface, even if a cover material has a paper base material, a sufficient sealing strength and unsealing, at the time of unsealing, can be easily effected in a stable manner. SOLUTION: The surface of a resin composition containing an ethylene resin component having a density of 0.895-0.940 g/cm3 and of 40-85 wt.%, an ethylene-α-olefin copolymer rubber component having a density of 0.860-0.890 g/cm3 and of 5-40 wt.%, and an adhesiveness imparting agent component (wt.% of each component means the ratio of its weight to the total weight of the three components) and having a tensile break elongation of 800% or less is heat-sealed to the surface of a propylene resin to form a heat-sealed structure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a packaging container having a propylene-based resin on a heat-sealing surface. The present invention relates to an easily-openable container which has sufficient sealing force even when it has, and which is easy and stable to open at the time of opening.

[0002]

2. Description of the Related Art Conventionally, seal pack packaging, in which a resin container body is heat-sealed with a resin film-like lid material and packaged, has been widely used mainly for packaging foods and beverages such as dairy products, confectionery, fruit juice drinks and the like. And occupy an important position together with plastic packaging bags. Conventionally, solution-type adhesives and hot-melt-type adhesives have been used as these sealants, but these are not always easy to open because the sealant causes a ductile fracture at the time of opening to form a thread. However, there was a problem of lack of easy-opening properties such as poor appearance of the peeled surface, and a lack of sealing properties such as peeling at high temperatures due to insufficient heat resistance. .

[0003] In order to improve such problems, various sealants having both sealing properties and easy-opening properties have been proposed in recent years.
Used. For example, when the lid has a paper base,
As a sealant layer formed on the paper substrate, a composition in which a tackifier is mixed with a polyolefin resin such as an ethylene-vinyl acetate copolymer is known. However, with these sealants, problems such as difficulty in opening the packaging container body having a propylene-based resin on the heat-sealing surface, and difficulty in smooth opening due to inconsistent force required for opening. Often occurs.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned prior art in an easily-openable container. Therefore, the present invention provides a packaging container having a propylene-based resin on a heat-sealing surface. In particular, even when the lid member has a paper base, the container body has a sufficient sealing force, and is easy and stable to be opened at the time of opening, particularly for a container body having a propylene-based resin on the heat sealing surface. It is an object of the present invention to provide an easily-openable container having the same.

[0005]

Means for Solving the Problems According to the present invention and the like, as a result of intensive studies to solve the above-mentioned problems, it has been found that the tensile elongation at break of a polyolefin resin composition containing a tackifier is important. The present invention has been completed, that is, the present invention relates to the following component (A), component (B), and component (C) [provided that the weight% of each component is based on a total of 100 weight% of these three components. It is. And a propylene-based resin surface having a heat-sealing structure in which the surface of the resin composition having a tensile elongation at break of 800% or less is heat-sealed. (A) Ethylene resin having a density of 0.895 to 0.940 g / cm ³ : 40 to 85% by weight (B) Ethylene-α-olefin copolymer rubber having a density of 0.860 to 0.890 g / cm ³ : 5 -40% by weight (C) Tackifier: 1-20% by weight

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the ethylene resin as the component (A) constituting the resin composition includes a homopolymer of ethylene and ethylene, for example, vinyl acetate, (meth) acrylic acid, Copolymers with (meth) acrylates and the like, and ethylene and, for example, propylene, 1-butene, 3-methyl-1-butene, 1-pentene, 4-methyl-1-pentene, 4,4- Dimethyl-
1-pentene, 1-hexene, 4-methyl-1-hexene, 1-heptene, 1-octene, 1-decene, 1-octadecene, and other copolymers with an α-olefin having about 3 to 18 carbon atoms, etc. Specific examples include, for example, a branched or linear ethylene homopolymer, an ethylene-vinyl acetate copolymer, an ethylene- (meth) acrylic acid copolymer,
Ethylene-ethyl (meth) acrylate copolymer, ethylene-propylene copolymer, ethylene-1-butene copolymer, ethylene-4-methyl-1-pentene copolymer, ethylene-1-hexene copolymer, Examples thereof include an ethylene-1-octene copolymer.

In the present invention, these ethylene resins are
From the viewpoint of easy opening property and heat sealing property as a resin composition,
Density of it essential is 0.895~0.940g / cm ^3, preferably from 0.910~0.930g / cm ^3. In addition, 190 according to JISK7210
It is preferable that the melt flow rate measured at 2.degree. C. and a load of 2.16 kg is 0.1 to 20 g / 10 minutes.

In the present invention, as the ethylene-α-olefin copolymer rubber as the component (B) constituting the resin composition, ethylene and, for example, propylene, 1-butene, 1-pentene, 1-hexene , 1-octene and other binary copolymers with an α-olefin having about 3 to 8 carbon atoms, such as 1,4-hexadiene, 5-methyl-1,5-hexadiene, 1,4- Octadiene, cyclohexadiene, cyclooctadiene, dicyclopentadiene, 5-ethylidene-2-norbornene, 5-butylidene-2-norbornene, 2-isopropenyl-5-
A ternary or higher copolymer obtained by copolymerizing a non-conjugated diene such as norbornene may be mentioned. The content of the α-olefin therein is 5 to 70% by weight, particularly 10 to 60% by weight. Preferably, specifically, for example, ethylene-propylene copolymer, ethylene-1-butene copolymer, ethylene-propylene-1,4-hexadiene copolymer, ethylene-propylene-dicyclopentadiene copolymer, ethylene -Propylene-5-ethylidene-2-
Norbornene copolymers and the like can be mentioned.

The ethylene-α-olefin copolymer rubber in the present invention must have a density of 0.860 to 890 g / cm ³ from the viewpoint of heat sealing properties as a composition. 23 according to JIS K7210
The melt flow rate measured at 0 ° C. under a load of 2.16 kg is preferably 0.05 to 20 g / 10 minutes.

In the present invention, the tackifier of component (C) constituting the resin composition is generally used as a tackifier resin in the fields of pressure-sensitive adhesive tapes, hot melt adhesives, paints and the like. A non-crystalline resin which is solid at ordinary temperature, specifically, for example, aliphatic, aromatic, aliphatic-aromatic petroleum resins, and hydrogenated petroleum resins, natural rosins, polymerized rosins, etc. Rosin-based resins, and rosin-based resins obtained by hydrogenating them, polyterpene-based resins, terpene-based resins such as terpene-phenol-based resins, and terpene-based resins obtained by hydrogenating them, and cumarone-indene-based resins, and Hydrogenated coumarone indene-based resin and the like can be mentioned.

The resin composition according to the present invention comprises the above (A)
It is essential that the component comprises 40 to 85% by weight, the component (B) comprises 5 to 40% by weight, the component (C) comprises 1 to 20% by weight, and the component (A) comprises 50 to 70% by weight. 15 to 35% by weight of the component (B) and 5 to 35% by weight of the component (C).
It is preferably 15% by weight [however, the weight% of each component is
Is based on a total of 100% by weight of these three components. ].

When the component (A) is less than the above range, the component (B) exceeds the above range, and the component (C) exceeds the above range, the sealing force of the resin composition is too strong to easily open. When the container is difficult to open, the component (A) exceeds the above range, the component (B) is below the above range, and the component (C) is below the above range. Is inferior.

The resin composition according to the present invention comprises the above (A)
Component, component (B), and component (C), and it is essential that the tensile elongation at break is 800% or less.
Preferably it is 600%. When the tensile elongation at break exceeds the above range, when used as a resin composition, particularly as a lid material having a paper substrate, the force required for opening is not constant, and it is difficult to perform smooth opening.

In order to further stabilize the opening at the time of opening the resin composition of the present invention, the component (A)
In addition to the components (B) and (C), a propylene-based resin (D) is further added to the components (A), (B) and (C).
It is preferable to contain 5 to 30 parts by weight, particularly 10 to 25 parts by weight, based on 100 parts by weight of the total of the components.

Here, the propylene resin includes:
A homopolymer of propylene, and a copolymer of propylene and another α-olefin having about 2 to 8 carbon atoms such as ethylene and 1-butene, specifically, for example,
Propylene-ethylene copolymer, propylene-1-butene copolymer, propylene-ethylene-1-butene copolymer and the like, among them, propylene homopolymer, or,
Propylene-ethylene copolymers are preferred, in which case
Preferably, the ethylene content is up to 5% by weight.

In the present invention, these propylene-based resins can be used at 230 ° C. and 2.16 in accordance with JIS K7210.
The melt flow rate measured under a kg load is 0.1-20.
g / 10 minutes.

In the resin composition of the present invention, the component (A) is an ethylene resin, the component (B) is an ethylene-α-olefin copolymer rubber, and the component (C) is a tackifier. In addition to the propylene resin of the component (D) used as a preferred embodiment, other thermoplastic resins and rubbers, as well as antioxidants and light stabilizers, as long as the effects of the present invention are not impaired. Further, additives such as an antistatic agent, an antiblocking agent, a lubricant, a plasticizer, a pigment, a filler, and the like may be blended.

The resin composition of the present invention may be a single layer of the resin composition and may be used for a container lid or a container body as an easily-openable container. Resin, polyester resin, saponified ethylene-vinyl acetate copolymer, polyolefin resin,
Polycarbonate resin, polystyrene resin, various thermoplastic resins such as acrylic resin film or sheet,
Used as a laminated film or sheet with a substrate such as aluminum foil or paper. Among them, it is suitable as a laminated film or sheet with a paper substrate. The laminating method is a known T-die or a ring-shaped die, for example, by extrusion lamination to the base material or co-extrusion with the various thermoplastic resin base materials.

The easily-openable container of the present invention has a heat-sealing structure in which the surface of the resin composition and the surface of the propylene-based resin are heat-sealed. The propylene-based resin surface as the heat-sealed body is a single-layer or laminated state as long as the same propylene-based resin as described in the resin composition forms the heat-sealed body surface. But it doesn't matter.

In the easy-open container of the present invention, the thickness of the resin composition which is heat-sealed to the surface of the propylene-based resin is usually about 5 to 50 μm.

In the present invention, a preferred form of the easily-openable container is a packaging container comprising a container body and a lid material.
An easy-open container that includes a container body having a propylene-based resin on the heat sealing surface and a lid member in which a layer of the resin composition is formed on the paper substrate as the heat sealing surface.

[0022]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist. The component (A) is an ethylene resin, the component (B) is an ethylene-α-olefin copolymer rubber, the component (C) is a tackifier, and the component (D) is a tackifier.
The following propylene resins were used as the components.

(A) Ethylene resin density 0.920 g / cm ³ , melt flow rate 8 g
Ethylene homopolymer resin obtained by a high pressure method of / 10 min. Density 0.895 g / cm ³ , melt flow rate 16
g / 10 min ethylene-1-hexene copolymer resin.

(B) Ethylene-α-olefin copolymer
Rubber propylene content 26% by weight, density 0.860g / c
m ³ , an ethylene-propylene copolymer rubber having a melt flow rate of 3.2 g / 10 min. 1-butene content 10% by weight, density 0.890 g / c
m ³ , melt flow rate 18 g / 10 min.
1-butene copolymer rubber.

(C) Tackifier Hydrogenated aromatic petroleum resin (softening temperature 140 ° C.,
Specific gravity 0.999, number average molecular weight 860). (D) A propylene homopolymer having a propylene resin melt flow rate of 6 g / 10 minutes.

Examples 1 to 3 and Comparative Examples 1 to 7 The ethylene resin (A) and the ethylene resin (B)
After the α-olefin copolymer rubber, the tackifier of the component (C), and the propylene resin of the component (D) are dry-blended in the proportions shown in Table 1, a single-screw extruder having a diameter of 40 mm is used. The resin composition was prepared by melt-kneading at 200 ° C.

With respect to the obtained resin composition, the tensile elongation at break was measured by the following method, and the results are shown in Table 1. Tensile breaking elongation According to JIS K7113, at 23 ° C., tensile speed 30
It was measured at 0 mm / min.

Subsequently, the obtained resin composition was supplied to an extruding laminator having a diameter of 35 mm equipped with a T-die, and extruded and laminated at 290 ° C. on a paper base material having a basis weight of 79 g / m ^3. A laminate having a 30 μm-thick resin composition layer thereon was formed.

On the other hand, the above-mentioned laminate is used as a cover material on a flange portion of a rectangular container body produced by thermoforming from a sheet of propylene homopolymer resin, and the resin composition layer is heat-sealed as an adhesive surface. To form an easily-openable container.
The obtained easily-openable container was evaluated for heat sealing performance by the following method, and the results are shown in Table 1.

Peel strength Using a hot plate type heat sealer, at a temperature of 120 ° C. and 140 ° C.
℃, 160 ℃, pressure 2 kg / cm ² , time 1 second,
The lid material is thermocompression-bonded to the container body flange at a width of 5 mm, the bonded portion is sampled at a length of 15 mm, and peeled at 23 ° C. at a pulling speed of 300 mm / min in the bonding width direction using an Instron type tensile tester. Then, the 180 degree peel strength was measured.

Opening stability : When the container lid was actually peeled off and the required force was constant and smooth peeling was achieved, the case where the required force was constant and the peeling was not smooth because the required force was not constant was marked as x. The stability was evaluated.

[0032]

[Table 1]

[0033]

According to the present invention, as a packaging container having a propylene-based resin on the heat-sealing surface, in particular, with respect to a container body having the propylene-based resin on the heat-sealing surface, the lid material is made of a paper base. Even if it has, it is possible to provide an easily-openable container which has a sufficient sealing force and is easy and stable to be opened at the time of opening.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08L 23:08) (C08L 23/04 23:16 23:10) (72) Inventor Yoshinobu Yada Yokkaichi, Mie Prefecture No. 1 Toho-cho, Yokohama-shi F-term in Yokkaichi Office of Mitsubishi Chemical Corporation (reference) JL14 YY00A 4J002 AE053 AF023 BA003 BA013 BB031 BB051 BB052 BB061 BB071 BB081 BB124 BB144 BB151 BB152 BB154 BK003 CE003 FD020 FD040 FD070 FD090 FD100 FD170 FD343 GF00 GG01

Claims (3)

[Claims] 1. The following components (A), (B) and (C) [where the weight percent of each component is based on a total of 100 weight percent of these three components. Wherein the surface of the resin composition having a tensile elongation at break of 800% or less and the surface of the propylene-based resin have a heat-sealing structure in which the surface is heat-sealed. (A) Ethylene resin having a density of 0.895 to 0.940 g / cm ³ : 40 to 85% by weight (B) Ethylene-α-olefin copolymer rubber having a density of 0.860 to 0.890 g / cm ³ : 5 -40% by weight (C) Tackifier: 1-20% by weight 2. The easy-open container according to claim 1, wherein the resin composition further contains the following component (D). (D) Propylene resin: 5 to 30 parts by weight based on 100 parts by weight of the total of the components (A), (B) and (C) 3. The container according to claim 1, wherein the easily-openable container comprises a container body having a propylene-based resin on a heat-sealing surface, and a lid member having a resin composition layer formed on a paper base material. The easy-open container according to the above.