阅读说明：本技术 密封用树脂组合物、密封用多层膜、热熔接性叠层膜和包装体 (Sealing resin composition, multilayer film for sealing, heat-sealable laminate film, and package ) 是由 关谷庆子 铃木雅生 斋藤哲也 工藤雄太 于 2019-03-07 设计创作，主要内容包括：本发明的课题在于提供一种兼备制袋性能和吹塑制膜加工性(挤出特性、气泡稳定性)的密封用树脂组合物、使用了该组合物的密封膜和热熔接性膜、以及使用了该热熔接性膜的包装体。本发明的密封用乙烯系树脂组合物同时满足下述条件(1)～(3)：(1)熔融指数(I<Sub>21</Sub>：190℃、21.6kg荷重)为42～80g/10min；(2)熔融指数(I<Sub>21</Sub>：190℃、21.6kg荷重)与熔融指数(I<Sub>2</Sub>：190℃、2.16kg荷重)之比I<Sub>21</Sub>/I<Sub>2</Sub>为5～25；(3)熔体张力(190℃)为25～180mN。(The present invention addresses the problem of providing a sealing resin composition having both bag-making performance and blown film processability (extrusion characteristics and bubble stability), a sealing film and a heat-sealable film each using the composition, and a package using the heat-sealable film. The ethylene resin composition for sealing of the present invention satisfies the following conditions(1) To (3): (1) melt index (I) 21 : 190 ℃ under a 21.6kg load) of 42 to 80g/10 min; (2) melt index (I) 21 : 190 ℃ under a 21.6kg load) and melt index (I) 2 : 190 ℃ under a 2.16kg load) ratio I 21 /I 2 5 to 25; (3) the melt tension (190 ℃) is 25-180 mN.)

1. A sealing ethylene resin composition characterized in that,

the following conditions (1) to (3) are satisfied:

(1) melt index (I)₂₁: 190 ℃ under a 21.6kg load) of 42 to 80g/10 min;

(2) melt index (I)₂₁: 190 ℃ under a 21.6kg load) and melt index (I)₂: 190 ℃ under a 2.16kg load) ratio I₂₁/I₂5 to 25;

(3) the melt tension (190 ℃) is 25-180 mN.

2. The ethylene resin composition for sealing according to claim 1, comprising:

(A) melt index (I)₂: 190 ℃ under a 2.16kg load) of 0.5 to 30g/10min and a density of 880 to 970kg/m³99.9 to 55% by mass of a linear polyethylene resin; and

(B) melt index (I)₂: 190 ℃ under a 2.16kg load) in the range of 0.01 to 20g/10min and a density of 900 to 940kg/m³0.1 to 45 mass% of a branched polyethylene resin,

wherein the total of the component (A) and the component (B) is 100% by mass.

3. A sealing film, characterized in that,

comprising a layer comprising the ethylene resin composition for sealing according to claim 1 or 2.

4. A heat-fusible laminate film characterized in that,

comprising the sealant film of claim 3 and a substrate.

5. A packaging body is characterized in that,

the heat-fusible laminate film of claim 4 is used.

Technical Field

The present invention relates to a sealing resin composition, a sealing multilayer film, a heat-sealable laminated film, and a package using the heat-sealable laminated film.

Background

Films made of polyethylene are used as packaging materials for packaging bags, standing bags, tubes, and the like for foods, snacks, medicines, and the like, and heat sealing properties according to the applications are required.

The polyethylene film is formed by extruding, without stretching, or stretching the resin composition. Typically, the resin is produced by a blow molding method and a T-mold method (also referred to as a casting method). In the blow molding method, air is blown into a molten resin extruded in a cylindrical shape to expand the resin, thereby forming a cylindrical film, and the cylindrical article is cut to produce a film. Since the strength of the film is reduced by making the film thinner, a film material which suppresses the reduction in strength is required.

As such a film material, for example, patent document 1 discloses a polyethylene resin composition which can form a film having good extrusion processability and excellent in all of the opening properties, tear strength and transparency by blending a high-density polyethylene and a specific high-pressure low-density polyethylene into an ethylene/α -olefin copolymer. Patent document 2 proposes a blend of a specific ethylene/α -olefin copolymer and a specific ethylene polymer. Patent document 3 discloses an easy-tear film composed of a composition containing an ethylene/α -olefin copolymer produced using a metallocene catalyst and a high-pressure low-density polyethylene.

Disclosure of Invention

Problems to be solved by the invention

In the conventional vinyl resin for sealing a blow-molded film for packaging, when the molecular weight distribution of the resin is wide, the fluidity is good, but the bag breaking strength at the time of bag formation is weak, and the bag forming performance tends to be poor (the temperature range at which bag formation can be performed becomes narrow). On the other hand, when the molecular weight distribution of the resin is narrow, the flowability is deteriorated and the melt tension is also lowered, so that the molding processability (extrusion characteristics and bubble stability) tends to be deteriorated. As described above, the conventional vinyl resin for sealing has a problem that bag-making performance and molding processability (extrusion characteristics and bubble stability) are difficult to be compatible with each other. In particular, in recent years, improvement in bag making performance is required in order to enable high-speed filling of the objects to be packaged (contents).

Accordingly, an object of the present invention is to provide a sealing resin composition having both bag-making performance and molding processability (extrusion characteristics and bubble stability), a sealing film and a heat-sealable film using the composition, and a package using the heat-sealable film.

Means for solving the problems

The present inventors have conducted extensive studies to solve the above problems, and as a result, have found that the use of a resin having a specific molecular weight distribution and melt tension can achieve both bag-making performance and molding processability (extrusion characteristics and bubble stability), thereby completing the present invention. That is, the present invention includes the following aspects.

[1] An ethylene resin composition for sealing, which satisfies the following conditions (1) to (3) at the same time:

(1) melt index (I)₂₁: 190 ℃ C., 21.6kg load) of 42E ℃80g/10min；

(2) Melt index (I)₂₁: 190 ℃ under a 21.6kg load) and melt index (I)₂: 190 ℃ under a 2.16kg load) ratio I₂₁/I₂5 to 25;

(3) the melt tension (190 ℃) is 25-180 mN.

[2]As in item [1]The ethylene resin composition for sealing, which comprises: (A) melt index (I)₂: 190 ℃ under a 2.16kg load) of 0.5 to 30g/10min and a density of 880 to 970kg/m³99.9 to 55% by mass of a linear polyethylene resin; and (B) melt index (I)₂: 190 ℃ under a 2.16kg load) in the range of 0.01 to 20g/10min and a density of 900 to 940kg/m³0.1 to 45% by mass of a branched polyethylene resin (wherein the total of the component (A) and the component (B) is 100% by mass).

[3] A sealing film comprising a layer composed of the ethylene-based resin composition for sealing according to item [1] or [2 ].

[4] A heat-fusible laminate film comprising the sealing film according to the item [3] and a substrate.

[5] A package using the heat-sealable laminate film according to item [4 ].

Effects of the invention

According to the present invention, a sealing ethylene resin composition having excellent bag-making performance and molding processability (extrusion characteristics, bubble stability) can be obtained. Further, when a heat-sealable laminate film including a sealing film made of such a sealing vinyl resin composition is used, the temperature range at which a bag can be made is wide (bag breaking strength is high), and therefore, the packaged article (contents) can be filled at high speed, and the productivity of the package is improved.

Detailed Description

The present invention will be described in detail below.

[ sealing resin composition ]

The ethylene resin composition for sealing of the present invention (hereinafter, also simply referred to as "the composition of the present invention") is characterized by satisfying the following conditions (1) to (3) at the same time.

(1) Melt index (I)₂₁: 190 ℃ under a 21.6kg load) of 42 to 80g/10 min.

(2) Melt index (I)₂₁: 190 ℃ under a 21.6kg load) and melt index (I)₂: 190 ℃ under a 2.16kg load) ratio I₂₁/I₂5 to 25.

(3) The melt tension (190 ℃) is 25-180 mN.

< Condition (1) >

Melt index (I) of the composition of the invention₂₁: 190 ℃ under a 21.6kg load) is usually 42 to 80g/10min, preferably 42 to 70g/10min, more preferably 43 to 65g/10min, and still more preferably 45 to 63g/10 min. If melt index (I)₂₁) Within the above range, good extrudability can be obtained. Melt index I₂₁Is a value measured at 190 ℃ under a 21.6kg load in accordance with JIS K7210.

< Condition (2) >)

Melt index (I) of the composition of the invention₂₁: 190 ℃ under a 21.6kg load) and melt index (I)₂: 190 ℃ under a 2.16kg load) ratio I₂₁/I₂Usually 5 to 25, preferably 8 to 24, more preferably 11 to 23, and further preferably 14 to 22. If I₂₁/I₂Within the above range, the extrudability and the bag breaking strength become good. Melt index I₂Is a value measured at 190 ℃ under a 2.16kg load in accordance with JIS K7210.

< Condition (3) >)

The melt tension (190 ℃) (hereinafter also referred to as "MT") of the composition of the present invention is usually 25 to 180mN, preferably 30 to 160mN, more preferably 35 to 140mN, still more preferably 40 to 115, and particularly preferably 45 to 90. When the MT is within the above range, the molding processability is good from the viewpoints of bubble stability, suppression of fusion, and the like. MT was measured at 190 ℃ using a melt-extruded strand in accordance with the method described later.

The composition of the present invention satisfying the above conditions (1) to (3) preferably includes:

(A) melt index (I)₂: 190 ℃ under a 2.16kg load) in the range of 0.5 to 30g/10min and a density of 880E @970kg/m³99.9 to 55% by mass of a linear polyethylene resin (hereinafter also referred to as "ethylene resin (A)" or "component (A)"); and

(B) melt index (I)₂: 190 ℃ under a 2.16kg load) in the range of 0.01 to 20g/10min and a density of 900 to 940kg/m³0.1 to 45% by mass of a branched polyethylene resin (hereinafter also referred to as "ethylene resin (B)" or "component (B)") (wherein the total amount of the component (a) and the component (B) is 100% by mass).

< ethylene resin (A) >

I of component (A)₂Usually, the concentration is in the range of 0.5 to 30g/10min, preferably 1.0 to 25g/10min, more preferably 1.5 to 20g/10min, and still more preferably 2.0 to 12g/10 min.

The density of the component (A) is usually 880 to 970kg/m³Preferably 885 to 950kg/m³More preferably 890 to 945kg/m³More preferably 895 to 940kg/m³The range of (1). The above density is a value measured in accordance with JIS K7112 (density gradient tube method).

Examples of the component (a) include linear low density polyethylene. The linear low density polyethylene includes copolymers of ethylene and α -olefins, and such copolymers can be obtained by using a known catalyst such as a ziegler natta catalyst or a metallocene catalyst. In the present invention, a linear polyethylene resin satisfying the above-described characteristics can be selected from commercially available linear polyethylene resins and used. Further, as the component (a), 2 or more kinds of linear polyethylene resins may be used.

The blending ratio of the component (a) in the composition of the present invention (the total of the component (a) and the component (B) is 100 mass%) is usually in the range of 99.9 to 55 mass%, preferably 99 to 60 mass%, more preferably 98.5 to 65 mass%, and further preferably 98 to 70 mass%. When the blending ratio of the component (a) is within the above range, good low-temperature sealing properties are exhibited.

< ethylene resin (B) >

I of component (B)₂Usually 0.01 to 20g/10min, preferably 0.05 to 17g/10min, more preferably 0.08 to 15g/10 minmin, more preferably 0.1-10 g/10 min.

The density of the component (B) is usually 900 to 940kg/m³Preferably 905 to 935kg/m³More preferably 908 to 932kg/m³More preferably 910 to 930kg/m³The range of (1).

The component (B) may be a branched polyethylene resin satisfying the above physical properties, and may be a high-pressure low-density polyethylene produced under high pressure using a radical catalyst, or a low-pressure polyethylene produced under low pressure in the presence of a comonomer such as ethylene and an α -olefin using a Ziegler catalyst or a metallocene catalyst. The high-pressure low-density polyethylene is preferably used in the present invention because it has a high melt tension because of the presence of long-chain branches in the molecular chain. In the present invention, a branched polyethylene resin satisfying the above-described respective properties can be selected from commercially available branched polyethylene resins and used.

The blending ratio of the component (B) in the composition of the present invention (the total of the component (a) and the component (B) is 100 mass%) is usually in the range of 0.1 to 45 mass%, preferably 1 to 40 mass%, more preferably 1.5 to 35 mass%, and further preferably 2 to 30 mass%. When the blending ratio of the component (B) is within the above range, good low-temperature sealing properties are exhibited.

< other ingredients >

The composition of the present invention may contain, as required, various additives usually added to polyolefins, such as weather resistant stabilizers, heat resistant stabilizers, antistatic agents, antifogging agents, antiblocking agents, slip agents, lubricants, pigments, and anti-dripping agents, within a range not to impair the object of the present invention.

[ sealing film ]

The sealing film of the present invention is characterized by comprising a layer composed of the composition of the present invention described above. The sealing film of the present invention may be a laminated film further including a layer made of another material as long as the effects of the present invention are not impaired.

Among these, as the laminated film, at least one surface layer is preferably a layer composed of the composition of the present invention. In this laminated film, the layer composed of the composition of the present invention may be formed only on one side or may be formed on both sides. The substrate constituting the laminated film may be a substrate composed of the composition of the present invention, or may be a substrate composed of another material. When another layer is laminated, the layer composed of the composition of the present invention preferably has a thickness of 1/5 or more, more preferably 1/4 or more, and most preferably 1/3 or more, based on the entire film thickness.

The thickness of the sealing film of the present invention can be suitably set in accordance with various uses, and the thickness of the layer made of the vinyl resin composition is usually in the range of 5 to 250 μm, preferably 10 to 200 μm.

< method for producing sealing film >

The method for producing the sealant film of the present invention is not particularly limited, and the film can be formed by a known melt extrusion molding method. The melt extrusion molding method is not particularly limited, and a known method can be used, but film formation by blow molding is preferable. The film obtained in this way can be processed into a film for producing a food packaging bag or the like as it is or in a form of a non-stretched film or a stretched film by further stretching. In this case, the thickness of a film obtained by melt extrusion molding (referred to as a stretched raw film, and including a thick molded body referred to as a sheet depending on the thickness) varies depending on the molding method. The stretched base film when produced by blow molding is preferably 50 to 2000 μm thick, more preferably 100 to 1500 μm thick. The molten resin may be cooled by either air cooling or water cooling. In the case of a laminated film with other layers, a multilayer stretched film may be used by coextrusion molding using a multilayer die.

Examples of the method of stretching the raw stretch film include: a method of simultaneously or separately performing biaxial stretching in the longitudinal and transverse directions by a tenter method; a method of simultaneously performing biaxial stretching in a longitudinal and transverse direction by a tubular method; or a method of uniaxially stretching the film in the flow direction by utilizing a difference in the rotation speed ratio of 2 or more rolls.

[ Heat-fusible laminate film ]

The heat-fusible laminate film of the present invention (hereinafter also simply referred to as "the heat-fusible film of the present invention") is characterized by comprising the sealing film of the present invention and a substrate.

The substrate is not particularly limited, and examples thereof include known thermoplastic resins such as polyolefins [ high-pressure low-density polyethylene, linear low-density polyethylene (LLDPE: ethylene-alpha-olefin random copolymer), medium-density polyethylene, high-density polyethylene and other polyethylene; polypropylene such as propylene homopolymer and propylene/α -olefin random copolymer (propylene random copolymer); poly-4-methyl-pentene; polybutylene and the like, polyesters (polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate and the like), polyamides (nylon-6, nylon-66, poly (m-xylylene adipamide and the like), polyvinyl chloride, polyimide, ethylene-vinyl acetate copolymers or saponified products thereof, polyvinyl alcohol, polyacrylonitrile, polycarbonate, polystyrene, ionomers and the like, and only 1 kind may be used, or 2 or more kinds may be used in combination. Among these, thermoplastic resins having good stretchability and transparency, such as polypropylene, polyester (particularly polyethylene terephthalate), and polyamide, are preferable.

The heat-fusible film of the present invention can be produced by a method of dry laminating the sealing film and the base material, a method of co-extruding resins constituting the respective layers, or the like.

In the case where the sealing film and the base material cannot be bonded with sufficient adhesive strength, an adhesive layer may be provided between the respective layers. As the adhesive layer, an adhesive resin such as a binder such as a polyurethane-based or isocyanate-based adhesive or a modified polyolefin such as an unsaturated carboxylic acid-grafted polyolefin is used, whereby adjacent layers can be firmly bonded.

The heat-fusible film of the present invention is suitably used for various packaging films such as fluid packaging bags, liquid soup packaging bags, paper-made liquid containers, laminated films, liquid packaging bags of special shapes (self-supporting bags and the like), standard bags, heavy bags, cling films, sugar bags, oil-containing packaging bags, food packaging and the like, protective films, infusion bags, agricultural materials, bag liners, semiconductor materials, pharmaceuticals, food packaging and the like, cleaning films, and the like.

[ Package ]

The package of the present invention can be obtained, for example, by preparing the heat-sealable film of the present invention into a bag-like container, filling the container with the objects to be packaged (contents) for various applications as described above, and heat-sealing the container. The heat-fusible film of the present invention has a wide temperature range at which a bag can be made and excellent bag breaking strength, and therefore, can be filled with contents at high speed.