JP2003246895A - Resin composition for sealant, sealant film and its use - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin composition for a sealant, which has excellent heat sealability and easy peelability and exhibits high sealing strength even at a low sealing temperature. <P>SOLUTION: The resin composition for a sealant comprises 30-90 wt.% of an ethylene polymer (A) having a melt flow rate of 0.1-30 g/10 min, a density of 0.900-0.940 g/cm<SP>3</SP>, and a specified melt tension value, 5-60 wt.% of an ethylene/α-olefin random copolymer (B) having a melt flow rate of 0.5-50 g/10 min, a density of less than 0.900 g/cm<SP>3</SP>, and a melting point determined by differential scanning calorimetry (DSC) of below 80°C, and 5-30 wt.% of a butene-based polymer (C) having a melt flow rate of 0.1-25 g/10 min and a density of 0.880-0.925 g/cm<SP>3</SP>. A film obtained from the resin composition is suitable for the sealant layer of a packaging film. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a resin composition for a sealant, a sealant film having heat sealability and easy peeling property, and a laminate film and a container using the sealant film.

[0002]

BACKGROUND OF THE INVENTION With the recent diversification of food, various packaging materials have been proposed. Among them, containers having easy peeling properties include instant noodles, yogurt containers, confectionery containers,
Widely used as other food containers. A sealant film having an easy peel property is required to simultaneously satisfy the contradictory performances of sealing property and easy peel property. Furthermore, due to the diversification of food containers, it has been desired to develop sealant films having various heat seal strengths. For example, when packaging food that is sensitive to heat, it is necessary to heat seal at a relatively low temperature to protect the contents. For such applications, there is a demand for a sealant film capable of exhibiting a strong sealing strength even in heat sealing at low temperatures and exhibiting an easy peel property.

Japanese Unexamined Patent Publication (Kokai) No. 10-337829 discloses an easily openable film formed of low density polyethylene and polybutene-1. However, the sealant film obtained by the publication has a problem that the sealing strength when it is sealed at a low temperature is insufficient.

[0004]

DISCLOSURE OF THE INVENTION The present invention provides a sealant resin composition having an excellent balance between heat seal strength and easy peeling property, and particularly capable of exhibiting high seal strength even at a low seal temperature, and a composition thereof. An object of the present invention is to provide a sealant film obtained, and a laminate film and a container using the same.

[0005]

Means for Solving the Problems That is, the present invention provides a melt flow rate (MFR, ASTM D1238, 19).
0.1 to 30 (g / 10 at 0 ° C, 2.16 kg load)
Min) and the density (ASTM D1505) are 0.900-0.
940 (g / cm ³ ), and the melt tension (MT) and the melt flow rate (MFR) are the following relational expressions 40 × (MFR) ^−0.67 ≦ MT ≦ 250 × (MF
R) ^-0.67 ethylene polymer (A) 30 to 90% by weight, melt flow rate (MFR, ASTM D1238, 1
90-50 ° C, 2.16 kg load) 0.5 to 50 (g / 10
Min) and density (ASTM D1505) is 0.900 (g
/ Cm ³ ) and differential scanning calorimetry (DS
Ethylene / α whose melting point required in C) is less than 80 ° C
-Olefin random copolymer (B) 5 to 60% by weight,
And melt flow rate (MFR, ASTM D12
38, 190 ° C, 2.16kg load) is 0.1 to 25
(G / 10 minutes) and the density (ASTM D1505) is 0.
It relates to a resin composition for a sealant formed from 5 to 30 wt% of a butene-based polymer (C) of 880 to 0.925 (g / cm ³ ).

Further, the present invention relates to a sealant film comprising the above resin composition of the present invention, and a laminate film and a container formed from the sealant film.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention relates to a resin composition composed of an ethylene polymer, an ethylene / α-olefin copolymer and a butene polymer, and a sealant film and a laminate film using the composition. , And about the container. Next, each of those configurations will be specifically described.

Ethylene Polymer (A) As the ethylene polymer (A) in the resin composition of the present invention, 190 ° C. and 2.1 in accordance with ASTM D1238.
Melt flow rate measured with a 6 kg load (hereinafter MFR
Abbreviated) is 0.1 to 30, preferably 0.5 to 20
(G / 10 min) and density (ASTM D1505)
Is 0.900 to 0.940, preferably 0.900 to
0.930 (g / cm ³ ), and the melt tension (MT) and the melt flow rate (MFR) have the following relational expression 40 × (MFR) ^−0.67 ≦ MT ≦ 250 × (MF
R) ^-0.67 is satisfied, and the ethylene polymer (A) is satisfied. Here, MT and MFR are both values measured at 190 ° C. The melt tension (MT) is a value obtained by measuring the stress when a molten ethylene polymer is stretched at a constant speed. Specifically, using a Toyo Seiki MT measuring machine, resin temperature 190 ° C., extrusion speed 15 mm / min, winding speed 15 m / min, nozzle diameter 2.0
It is a value measured under the conditions of 9 mmφ and a nozzle length of 8 mm. By having MFR within the above range and MT within the above relational expression, the melt tension of the ethylene-based polymer is increased,
Good moldability.

The ethylene-based polymer (A) used in the composition of the present invention may be a so-called high-pressure polyethylene produced under a high pressure using a radical catalyst, as long as it satisfies the above-mentioned physical properties. Alternatively, it may be a so-called medium- and low-pressure polyethylene produced by using a Ziegler catalyst or a metallocene catalyst in the presence of a comonomer such as ethylene and α-olefin under medium and low pressure. High-pressure polyethylene has a long-chain branch in its molecular chain and exhibits a high melt tension. Therefore, it can be preferably used in the present invention.

Random copolymerization of ethylene / α-olefin
Body (B) The ethylene / α-olefin random copolymer used as the component (B) in the resin composition of the present invention is ethylene and an α-olefin having 3 to 20 carbon atoms, preferably 3 to 10 carbon atoms.
It is a random copolymer obtained by copolymerizing with an olefin. Specific examples of α-olefins include:
Propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, 1-dodecene may be mentioned, preferably 1-butene, 1-hexene, 1-octene. Is. The content of α-olefin in the copolymer is 5 to 50 mol%, usually 7
~ 30 mol%.

MFR of ethylene / α-olefin random copolymer (ASTM D1238, 190 ° C., 2.1
6 kg load) is 0.5 to 50, preferably 1.0 to 30
(G / 10 min) and density (ASTM D1505)
Is less than 0.900 (g / cm ³ ), preferably 0.85
The melting point is 0 to 0.890 (g / cm ³ ), and the melting point determined by differential scanning calorimetry (DSC) is less than 80 ° C., or the melting point is not observed, which is amorphous.

The method for producing the ethylene / α-olefin random copolymer is not particularly limited, but it is produced by copolymerizing ethylene and α-olefin in the presence of a Ziegler-Natta catalyst or a metallocene catalyst. be able to.

Further, in the present invention, the density and / or
Alternatively, the composition can be used by blending several kinds of ethylene / α-olefin random polymers having different MFR.

Butene-based polymer (C) The butene-based polymer (B) used in the resin composition of the present invention is 1-butene homopolymer or 1-butene homopolymer.
It is a copolymer of butene and an α-olefin having 2 to 20 carbon atoms, preferably 2 to 10 excluding 1-butene. Specific examples of α-olefins include ethylene, propylene and 1
-Hexene, 4-methyl-1-pentene, 1-octene, 1-decene, 1-dodecene are mentioned, and ethylene and propylene are preferable. 1-in butene polymer
The butene content is 60 to 100, preferably 70.
-100 (mol%).

The butene-based polymer has a density of 0.880 to
0.925, preferably 0.885 to 0.920 (g /
cm3). Within this density range, the tackiness is low, so that when the container is manufactured from the film, the film does not adhere to a device such as a roll, and the contents can be filled at a high filling speed.

The MFR (190 ° C) is 0.1-2.
5, preferably 0.5 to 25, more preferably 1 to 25
It is in the range of (g / 10 minutes). Within this range, the film can be formed at a high forming speed without imposing an excessive load on the motor of the forming machine.

Such a butene polymer is disclosed in Japanese Examined Patent Publication No.
-7088, JP-A-59-206415,
JP-A-59-206416, JP-A-4-2185
08, JP-A-4-218607, JP-A-8
It can be produced by a polymerization method using a stereoregular catalyst described in Japanese Patent Publication No. 225605. The butene polymer used in the present invention may be one kind,
You may use it in combination of 2 or more types.

Resin Composition The resin composition of the present invention comprises an ethylene-based polymer (A), an ethylene / α-olefin random copolymer (B) and a butene-based polymer (C). (A)
Is 30 to 90, preferably 40 to 80% by weight, (B) is 5 to 60%, preferably 10 to 50% by weight, and (C) is 5 to 5% by weight.
It is in the range of 30, preferably 10 to 30% by weight. Here, the total amount of (A), (B) and (C) is 100% by weight. When the ratio of each component is within this range, the film obtained from the composition has an excellent balance between the sealing strength and the easy peeling property, and a practically suitable easy-open container can be obtained.

A characteristic of the resin composition of the present invention is that an ethylene / α-olefin random copolymer having a specific property is used as a constituent component of the resin composition. By using the ethylene / α-olefin random copolymer as described above, a film having an excellent balance between the sealing strength and the easy peeling property can be obtained even at a low sealing temperature. Further, since the optimum sealing temperature can be controlled by the amount of the ethylene / α-olefin random copolymer, it can be applied to an easily opened container having various characteristics.

In the present invention, an antioxidant, a heat stabilizer, a weather stabilizer, a slip agent, an anti-blocking agent, a crystal nucleating agent, etc., may be used as needed within the range of not impairing the performance of the resin composition of the present invention. The additive may be included.

The above components and, if necessary, various additives are blended in a mixer such as a Henschel mixer, a Banbury mixer or a tumbler mixer, and then pelletized using a uniaxial or biaxial extruder. It is possible to use it for the film forming of
It is also possible to use the blended state of the above components in a film forming machine.

Sealant Film By forming a film from the resin composition of the present invention, a sealant film for a packaging material that requires easy peeling properties can be produced. The film molding is
Either a cast molding method or an inflation molding method may be used, and a film having a uniform film thickness can be usually produced under the condition of a resin temperature of 180 to 240 ° C. The thickness of the film is usually 3 to 100 μm, preferably 5 to 8
It is in the range of 0 μm.

Laminate Film Although the sealant film can be used alone, it has a constitution of a laminate film laminated on a base film and is generally used as a packaging film or a packaging sheet.

The substrate film is not particularly limited, but a polyolefin film such as polyethylene or polypropylene, a styrene resin film, a polyester film such as polyethylene terephthalate or polybutylene terephthalate, nylon 6 or nylon 6, etc. 6, a polyamide film such as 6, or a stretched film thereof, a laminated film of a polyolefin film and a resin film having a gas barrier property such as a polyamide film or an ethylene-vinyl alcohol copolymer film, a metal foil such as aluminum, or A vapor-deposited film obtained by vapor-depositing aluminum, silica or the like, paper or the like is appropriately selected and used according to the purpose of use of the packaging material. This substrate film can be used not only in one kind but also in combination of two or more kinds.

Since the sealant film layer is located on at least one outermost layer of the laminate film, the resin composition of the present invention may be directly extrusion laminated onto the base film or the base film and the sealant may be used in the production thereof. A method of dry laminating the film or a method of co-extruding resins constituting both layers can be adopted.

As one embodiment of the laminate film, there may be mentioned a constitution of sealant film layer / polyolefin film layer / other film layer. Here, as the other film layer, a layer selected from the group consisting of the above-mentioned polystyrene film, polyester film, polyamide film, laminated film of polyolefin film and gas barrier resin film, aluminum foil, vapor deposition film, and paper. Can be mentioned.

When the polyolefin layer and the other film layer cannot be bonded with sufficient adhesive strength, a sealant film layer / polyolefin film layer / adhesive layer / other film layer can be used. As the adhesive layer, if an anchor coating agent such as urethane-based or isocyanate-based adhesive is used, or if a modified polyolefin such as unsaturated carboxylic acid grafted polyolefin is used as the adhesive resin, the adjacent layers can be firmly bonded. it can.

Container The sealant film layers of the above-mentioned laminated film are made to face each other, or the sealant film layer of the laminated film is made to face another film, and then the periphery thereof is formed from the outer surface side into a desired container shape. The container can be manufactured by heat-sealing at least a part of the container. Further, by heat-sealing the entire circumference, a sealed bag-shaped container can be manufactured. When this bag-shaped container forming process is combined with the content filling step, that is, the bottom and side portions of the bag-shaped container are heat-sealed, then the content is filled, and then the upper part is heat-sealed to produce a package. can do. Therefore, this laminate film is a solid material such as snacks,
It can be used for automatic packaging equipment for powder or liquid materials.

Further, the laminate film or sheet, or another film or sheet is formed from a cup-shaped container previously formed by vacuum molding or pressure forming, a container obtained by injection molding, or a paper base material. A container in which the contents are packaged is obtained by filling the contents in a container or the like, then coating the laminate film of the present invention as a lid material, and heat-sealing the top or side of the container. This container is preferably used for packaging instant noodles, miso, jelly, pudding, snacks and the like.

[0030]

The present invention will now be described with reference to examples, but the present invention is not limited thereto.

[0031]

Example 1 A two-layer T-die cast molding machine having a die width of 300 mm, which has an extruder having a screw diameter of 40 mm for a core layer and an extruder having a screw diameter of 30 mm for a sealant layer, using the following resin raw materials, At a molding temperature of 220 ° C. and a chill roll temperature of 30 ° C., a core layer / sealant layer (50 μm /
A film having a layer structure of 20 μm) was prepared. The heat seal strength, the easy peeling property and the stringing property of the obtained film were evaluated by the following methods. The results are shown in Table 1.

Core layer: High pressure low density polyethylene (density 0.917 g / cm ³ , MFR (190 ° C.) 9.5 g)
/ 10 minutes) Sealant layer: High-pressure polyethylene (density 0.917)
g / cm ³ , MFR (190 ° C) 9.5 g / 10 minutes) 5
0% by weight, ethylene / 1-butene copolymer (density 0.8
85 g / cm ³ , MFR (190 ° C) 20 g / 10 minutes,
1-butene content 11 mol%, melting point 75 ° C.) 30% by weight,
And 1-butene polymer (density 0.915 g / cn ³ , MFR (190 ° C.) 1.8 g as a butene polymer component.
/ 10 minutes) 20% by weight.

(1) Heat sealing strength: Two strip-shaped test pieces of 15 mm were prepared, and the sealing layers were opposed to each other,
Heat sealing was performed at a predetermined temperature under a pressure of 0.2 MPa and a sealing time of 0.5 seconds. After that, 180 between layers
The peel strength at that time is measured at a speed of 300 mm / min, and the measured value is the heat seal strength (N / 15).
mm).

[0034]

[Example 2 and Comparative Example 1] Example 1 and Comparative Example 1 except that the high-pressure polyethylene, ethylene / 1-butene copolymer and 1-butene polymer used as the sealant layer had the contents shown in Table 1. The film was evaluated in the same manner. The results are shown in Table 1.

[0035]

[Table 1]

As is clear from the results shown in Table 1, the film of the present invention exhibits a high sealing strength at a sealing temperature lower than the conventional one. The easy peeling property was also good.

[0037]

The resin composition for a sealant of the present invention has a film having excellent balance between heat sealability and easy peeling property, and can exhibit high seal strength even at a lower seal temperature. It can be suitably used for food packaging containers.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C08J 5/18 CES C08J 5/18 CES C08L 23/08 C08L 23/08 23/20 23/20 F term ( reference) 3E086 AC07 AD01 AD06 BA04 BA13 BA14 BA15 BB51 BB90 CA01 DA08 4F071 AA15 AA15X AA16 AA17 AA18 AA20X AA21 AA21X AA76 AF54 AF59 BC01 BC12 4F100 AB10B AB33B AK03B AK04A AK04C AK06A AK07C AK09A AK12B AK41B AK46B AK62A AK67 AK68C AL05A BA02 BA03 BA07 BA10A BA10C DA01 DG10B EH23 EH66B GB16 JA04A JA06A JA13A JD02B JK06 JL12A JL14 4J002 BB03W BB05X BB17Y GG02 4J100 AA02P AA03Q AA04P AA04Q AA07Q AA17Q CA01 CA04 DA13 DA14 DA36 DA43 JA58

Claims (7)

[Claims] 1. Melt flow rate (MFR, ASTM
D1238, 190 ° C, 2.16kg load) is 0.1
30 (g / 10 minutes), density (ASTM D1505) is 0.900 to 0.940 (g / cm ³ ), and melt tension (MT) and melt flow rate (MF).
R) is the following relational expression 40 × (MFR) ^−0.67 ≦ MT ≦ 250 × (MF
R) ^-0.67 ethylene-based polymer (A) 30 to 90% by weight, melt flow rate (MFR, ASTM D1238,
190 ° C, 2.16 kg load) 0.5 to 50 (g / 1
0 minutes), density (ASTM D1505) is 0.900
(G / cm ³ ) and differential scanning calorimetry (D
SC) ethylene whose melting point is less than 80 ° C
5 to 60% by weight of α-olefin random copolymer (B), and melt flow rate (MFR, ASTM D
1238, 190 ℃, 2.16kg load) is 0.1-2
A resin composition for a sealant formed from 5 to 30% by weight of a butene polymer (C) having a density of 5 (g / 10 minutes) and a density (ASTM D1505) of 0.880 to 0.925 (g / cm ³ ). 2. The sealant resin composition according to claim 1, wherein the ethylene-based polymer is high-pressure polyethylene. 3. A sealant film comprising the resin composition according to claim 1 or 2 and having a thickness of 3 to 100 μm. 4. A layer of the sealant film according to claim 3, a polyolefin film, a polystyrene film,
A laminate comprising a polyester film, a polyamide film, a laminated film of a polyolefin and a gas barrier resin film, an aluminum foil, paper, and at least one film layer selected from the group consisting of vapor deposited films. Laminated film. 5. A layer of the sealant film according to claim 4, a polyolefin film layer, a polyolefin film, a polystyrene film, a polyester film,
At least one film layer selected from the group consisting of a polyamide film, a laminated film of a polyolefin and a gas barrier resin film, an aluminum foil, a paper, and a vapor deposited film is laminated in this order. Body film. 6. A container characterized in that the sealant film layer surfaces of the laminate film according to claim 4 or 5 are brought into contact with each other, and at least a part thereof is heat-sealed. 7. A sealant film layer of the laminate film according to claim 4 or 5, polyethylene, ethylene.
A container characterized in that a vinyl acetate copolymer and a molded product of a resin selected from the group consisting of polypropylene are opposed to each other, and at least a part thereof is heat-sealed.