CN100448667C - Packaging film - Google Patents

Abstract

A packaging film composed of at least three layers, i.e., an inner layer, interlayer, and outer layer, wherein the interlayer is made of a polyethylene resin composition comprising (M-1) 20 to 75 wt.% ethylene/alpha-olefin copolymer having an MFR of 0.1 to 100 g/10 min and a density of 0.90 to 0.940 g/cm<3>, (M-2) 20 to 70 wt.% high-density polyethylene having an MFR of 0.001 to 50 g/10 min and a density of 0.942 to 0.97 g/cm<3>, and (M-3) 5 to 20 wt.% high-pressure-process low-density polyethylene having an MFR of 0.01 to 20 g/10 min . The packaging film is excellent in heat-sealing strength, gloss, modulus, and impact strength and is thin and tough.

Description

Packaging film

technical field

The present invention relates to films for packaging. More specifically, it relates to a thin and strong packaging film that is excellent in heat-sealing strength and gloss, and also excellent in rigidity, flexibility, and impact strength.

technical background

Films used for packaging hygiene products such as disposable diapers and sanitary products generally require excellent heat seal strength and gloss. Moreover, it is required to be able to protect the contents, be easy to accumulate, and be easy to carry. In addition, from the perspective of protecting the global environment and reducing garbage in recent years, efforts have been made to reduce the thickness. Its rigidity and flexibility (elasticity) and impact strength are excellent, thin and strong.

For example, JP-A-2002-273843 describes a polyethylene film for compression packaging consisting of three layers: an outer layer, an inner layer, and an intermediate layer, as a polyethylene film for compression packaging excellent in tear strength and impact strength. The outer and inner layers of the film are made of resin containing ethylene-α-olefin copolymer with MFR of 0.1-10g/10min and density of 0.910-0.930g/ ^cm3 , and the middle layer is made of resin containing MFR of 0.1-10g /10min, a resin composition of ethylene-α-olefin copolymer with a density of 0.925-0.945g/cm ³ .

However, the polyethylene film for compression packaging described in the above-mentioned patent publication also requires further improvement in heat seal strength and gloss, and further improvement in rigidity, flexibility and impact strength is also required in order to be thinner and stronger.

Contents of the invention

An object of the present invention is to provide a thin and strong packaging film that is excellent in heat-sealing strength and gloss, and excellent in rigidity, flexibility (elasticity modulus) and impact strength.

The inventors of the present invention have carefully studied in view of the above-mentioned actual situation and found that the above-mentioned problems can be solved by using a resin composition having at least three layers of an inner layer, an intermediate layer and an outer layer, and the intermediate layer satisfies specific properties, thus completing the present invention. invention.

That is, the gist of the present invention is to provide a packaging film characterized in that it has at least three layers of an inner layer, an intermediate layer and an outer layer, the intermediate layer is between the inner layer and the outer layer, and each layer is composed of The following resin composition was constituted.

The middle layer is composed of:

(M-1) 20 to 75% by weight of an ethylene-α-olefin copolymer with an MFR of 0.1 to 100 g/10min and a density of 0.90 to 0.940 g/cm ³ ;

(M-2) 20-70% by weight of high-density polyethylene (M-2) with an MFR of 0.001-50 g/10min and a density of 0.942-0.97 g/cm ³ ; and

(M-3) A layer composed of a high-pressure low-density polyethylene having an MFR of 0.01 to 20 g/10 min and a polyethylene resin composition of 5 to 20% by weight. (The total amount of the above-mentioned copolymer (M-1), high-density polyethylene (M-2) and high-pressure low-density polyethylene (M-3) is 100% by weight.)

The inner layer and the outer layer are made of polyethylene resin or resin composition, and the polyethylene resin or resin composition has MFR in the range of 0.01-20g/10min and density in the range of 0.90-0.95g/cm ³ . The resin or resin composition of the inner layer and the outer layer may be the same or different.

Furthermore, the inner layer preferably consists of:

(I-1) MFR is 0.1～100g/10min, density is 0.90～0.95g/cm ³ ethylene-alpha-olefin copolymer 45～90% by weight; And

(I-2) A layer composed of a high-pressure low-density polyethylene with an MFR of 0.01 to 20 g/10 min and a polyethylene resin composition of 10 to 55% by weight. (wherein, the total amount of the above-mentioned copolymer (I-1) and high-pressure low-density polyethylene (I-2) is 100% by weight.),

The outer layer preferably consists of:

(O-1) 70 to 90% by weight of an ethylene-α-olefin copolymer with an MFR of 0.1 to 100 g/10min and a density of 0.90 to 0.95 g/cm ³ ; and

(O-2) A layer composed of a high-pressure low-density polyethylene with an MFR of 0.01 to 20 g/10 min and a polyethylene resin composition of 10 to 30% by weight. (However, the total amount of the above-mentioned copolymer (O-1) and high-pressure-processed low-density polyethylene (O-2) is 100% by weight.).

Furthermore, the (M-2) composition of the intermediate layer is preferably composed of:

(LL-3) 20 to 80% by weight of an ethylene-α-olefin copolymer with an MFR of 0.1 to 2 g/10min and a density of not less than 0.88 g/cm ³ and less than 0.93 g/cm ³ ; and

(LL-4) MFR is 2-100g/10min, density is 0.93-0.97g/cm ³ ethylene-α-olefin copolymer 20-80% by weight constituted (among them, (LL-3) and (LL-4 ) The total amount is 100% by weight.).

Detailed ways

middle layer

The middle layer of the packaging film of the present invention is composed of:

(M-1) 20-75% by weight of ethylene-α-olefin copolymer;

(M-2) 20-70% by weight of high-density polyethylene; and

(M-3) A layer composed of a polyethylene resin composition comprising 5 to 20% by weight of high-pressure low-density polyethylene. However, the total amount of (M-1), (M-2) and (M-3) is 100% by weight. (M-1) is preferably 30 to 70% by weight, and (M-2) is preferably 20 to 65% by weight. (M-1) If it exists in the said range, since film strength will improve, it is preferable. (M-2) If it exists in the said range, since both the elastic modulus of a film and heat-sealing strength can be improved, it is preferable. (M-3) Since the heat-sealing strength of a film will improve that it exists in the said range, it is preferable.

(M-1)

The MFR of the ethylene-α-olefin copolymer (M-1) is 0.1 to 100 g/10 min, and the density is 0.90 to 0.940 g/cm ³ .

When MFR is in the said range, it is preferable from a viewpoint of extrusion processability and the intensity|strength of the film for packaging. In addition, when the density is within the above range, it is preferable from the viewpoints of rigidity, flexibility and strength of the film for packaging.

(M-2)

The MFR of the high-density polyethylene (M-2) used in the intermediate layer is 0.001-50 g/10 min, preferably 0.03-10 g/10 min, more preferably 0.1-1 g/10 min. If the MFR is 0.001 g/10 min or more, it is preferable in terms of good extrusion processability, and if it is 2 g/10 min or less, it is preferable in terms of the strength of the packaging film and the stability of bubbles during molding.

The high-density polyethylene (M-2) has a density of 0.942 to 0.97 g/cm ³ , preferably 0.945 to 0.970 g/cm ³ , more preferably greater than 0.945 and 0.960 g/cm ³ or less. If the density is at least 0.942 g/cm ³ , it is preferable in terms of improving the rigidity and flexibility of the packaging film, and if it is at most 0.97 g/cm ³ , it is preferable in terms of increasing the strength of the packaging film.

(M-3)

The MFR of the high-pressure low-density polyethylene (M-3) used for the intermediate layer of the packaging film of the present invention is 0.01 to 20 g/10 min, preferably 0.1 to 5 g/10 min, more preferably 0.3 to 2 g/10 min. If the MFR is 0.01 g/10 min or more, the compatibility with (M-1) is high, so it is preferable, and if it is 20 g/10 min or less, the strength of the packaging film and the stability of the air bubbles during molding are good. is preferred.

The density of the high-pressure low-density polyethylene (M-3) is not particularly specified, but is preferably 0.917 to 0.930 g/cm ³ , more preferably 0.919 to 0.925 g/cm ³ . If the density is at least 0.917 g/cm ³ , it is preferable in terms of improving the rigidity and flexibility of the packaging film, and if it is at most 0.93 g/cm ³ , it is preferable in terms of increasing the strength of the packaging film.

(LL-3)

Furthermore, the aforementioned (M-1) is preferably composed of two kinds of ethylene-α-olefin copolymers (LL-3) and (LL-4). When the (M-1) component is 100% by weight, (LL-3) is 20 to 80% by weight, preferably 50 to 70% by weight, and (LL-4) is 20 to 80% by weight, preferably 30 to 50% by weight. weight%.

The MFR of the copolymer (LL-3) is 0.1 to 2 g/10 min, preferably 0.3 to 1 g/10 min. If the MFR is 0.1 g/10 min or more, it is preferable in terms of good extrusion processability, and if it is 2 g/10 min or less, it is preferable in terms of the strength of the packaging film and the stability of bubbles during molding.

The density of the copolymer (LL-3) is 0.88 to 0.93 g/cm ³ , preferably 0.90 to 0.91 g/cm ³ , more preferably 0.903 to 0.907 g/cm ³ . If the density is at least 0.88 g/cm ³ , it is preferable to increase the rigidity and flexibility of the packaging film, and if it is at most 0.93 g/cm ³ , it is preferable to increase the strength of the packaging film.

(LL-4)

The MFR of the ethylene-α-olefin copolymer (LL-4) is 2 to 100 g/10 min, preferably 20 to 80 g/10 min. If the MFR is 2 g/10 min or more, it is preferable in terms of good extrusion processability, and if it is 100 g/10 min or less, it is preferable in terms of the strength of the packaging film and the stability of bubbles during molding.

The density of the copolymer (LL-4) is 0.93 to 0.97 g/cm ³ , preferably 0.930 to 0.949 g/cm ³ . If the density is at least 0.93 g/cm ³ , it is preferable to increase the rigidity and flexibility of the packaging film, and if it is at most 0.97 g/cm ³ , it is preferable to increase the strength of the packaging film.

When the ethylene-α-olefin copolymer (M-1) is composed of (LL-3) and (LL-4), the content of the ethylene-α-olefin copolymer (LL-3) is 15 to 60 % by weight, the content of ethylene-α-olefin copolymer (LL-4) is 5-25% by weight, the content of high-density polyethylene (M-2) is 20-70% by weight, high-pressure low-density polyethylene (M-2) -3) The content is 5 to 20% by weight. Furthermore, the content of the ethylene-α-olefin copolymer (LL-3) is preferably 15 to 50% by weight, and the content of the high-density polyethylene (M-2) is preferably 20 to 60% by weight.

(inner layer)

The inner layer of the packaging film of the present invention is composed of a polyethylene resin composition, and the MFR of the polyethylene resin or resin composition is in the range of 0.01 to 20 g/10 min, preferably in the range of 0.1 to 10 g/10 min. The density is in the range of 0.90 to 0.95 g/cm ³ , preferably in the range of 0.91 to 0.93 g/cm ³ . Examples of the polyethylene resin or resin composition include linear or branched polyethylene, high-pressure low-density polyethylene, or a composition composed of these. Furthermore, the inner layer preferably consists of:

(I-1) MFR is 0.1～100g/10min, density is 0.90～0.95g/cm ³ ethylene-alpha-olefin copolymer 45～90% by weight; And

(I-2) A polyethylene resin composition comprising 10 to 55% by weight of high-pressure low-density polyethylene having an MFR of 0.01 to 20 g/10 min. However, the total amount of the above-mentioned copolymer (I-1) and high-pressure-processed low-density polyethylene (I-2) is 100% by weight. (I-1) When it exists in the said range, film strength will improve, and it is preferable. (I-2) If it exists in the said range, the heat-sealing strength of a film will improve, and it is preferable.

(I-1)

The MFR of the ethylene-α-olefin copolymer (I-1) is 0.1 to 100 g/10 min, preferably 0.5 to 50 g/10 min. When MFR is in the said range, it is preferable at the point that the intensity|strength and extrusion processability of the film for packaging are favorable. (I-1) has a density of 0.90 to 0.95 g/cm ³ , preferably 0.91 to 0.94 g/cm ³ . When the density is within the above range, the rigidity, flexibility and strength of the film for packaging are improved, so it is preferable.

Furthermore, the ethylene-α-olefin copolymer (I-1) is preferably composed of two kinds of ethylene-α-olefin copolymers (LL-1) and (LL-2). When the whole of (I-1) is 100% by weight, (LL-1) is 20 to 80% by weight, and (LL-2) is 20 to 80% by weight. Preferably (LL-1) is 55 to 75% by weight, and (LL-2) is 25 to 45% by weight.

(LL-1)

The MFR of the copolymer (LL-1) is 0.1 to 10 g/10 min, preferably 0.2 to 5 g/10 min, more preferably 0.4 to 1 g/10 min. If the MFR is 0.1 g/10 min or more, it is preferable in terms of extrusion processability, and if it is 10 g/10 min or less, the strength of the packaging film, heat resistance, and stability of bubbles during molding are good. above is preferred.

The density of the copolymer (LL-1) is 0.88 to 0.93 g/cm ³ , preferably 0.91 to 0.92 g/cm ³ , more preferably 0.913 to 0.918 g/cm ³ . If the density is at least 0.88 g/cm ³ , it is preferable to improve the rigidity and flexibility of the packaging film, and if it is at most 0.93 g/cm ³ , it is preferable to improve the heat sealability of the packaging film.

(LL-2)

The MFR of the ethylene-α-olefin copolymer (LL-2) is 2 to 100 g/10 min, preferably 2 to 80 g/10 min. If MFR is 2 g/10 min or more, it is preferable in terms of good extrusion processability, and if it is 100 g/10 min or less, it is preferable in terms of good strength of packaging film.

The density of the copolymer (LL-2) is 0.93 to 0.97 g/cm ³ , preferably 0.925 to 0.950 g/cm ³ , more preferably 0.935 to 0.945 g/cm ³ . If the density is at least 0.93 g/cm ³ , it is preferable to increase the rigidity and flexibility of the packaging film, and if it is at most 0.97 g/cm ³ , it is preferable to increase the strength of the packaging film.

(I-2)

The MFR of the high-pressure low-density polyethylene (I-2) is 0.01 to 20 g/10 min, preferably 0.3 to 5 g/10 min. If it is 0.01 g/10 min or more, it is preferable because the compatibility with (I-1) is high, and if it is 20 g/10 min or less, it is preferable because the stability of the bubbles during molding is good.

The density of (I-2) is not particularly specified, but is preferably 0.917 to 0.930 g/cm ³ , more preferably 0.910 to 0.925 g/cm ³ . If the density is at least 0.917 g/cm ³ , it is preferable in terms of improving the rigidity and flexibility of the packaging film, and if it is at most 0.930 g/cm ³ , it is preferable in terms of increasing the strength of the packaging film.

When (I-1) is composed of ethylene-α-olefin copolymers (LL-1) and (LL-2), the content of (LL-1) is 20 to 60% by weight relative to the entire inner layer, and (LL- The content of 2) is 25 to 40% by weight, and the content of high-pressure low-density polyethylene (I-2) is 10 to 55% by weight. However, the total amount of the above-mentioned copolymer (LL-1), the above-mentioned copolymer (LL-2), and high-pressure-processed low-density polyethylene (I-2) is 100% by weight.

When the content of the copolymer (LL-1) used in the inner layer is less than 20% by weight, the strength of the packaging film may decrease, and when it exceeds 60% by weight, the extrusion load of the polyethylene resin composition used in the inner layer may increase, The gloss of the packaging film decreases.

When the content of the copolymer (LL-2) is 25% by weight or less, the rigidity and flexibility of the packaging film may decrease, and when it exceeds 40% by weight, the strength of the packaging film may decrease.

The content of the high-pressure low-density polyethylene (I-2) is preferably 15 to 60% by weight. When the content of I-2 is less than 10% by weight, the gloss of the packaging film may decrease. In addition, when the polyethylene resin composition used for the inner layer is molded, the bubbles may become unstable. When it exceeds 60% by weight, the strength of the packaging film may be reduce.

(outer layer)

The outer layer of the packaging film of the present invention is composed of a polyethylene resin composition, and the MFR of the polyethylene resin or resin composition is in the range of 0.01 to 20 g/10 min, preferably in the range of 0.1 to 10 g/10 min. The density is in the range of 0.90 to 0.95 g/cm ³ , preferably in the range of 0.91 to 0.93 g/cm ³ . Examples of the polyethylene resin or resin composition include linear or branched polyethylene, high-pressure low-density polyethylene, or a composition composed of these. Furthermore, the outer layer preferably consists of:

(O-1) 70 to 90% by weight of an ethylene-α-olefin copolymer with an MFR of 0.1 to 100 g/10min and a density of 0.90 to 0.95 g/cm ³ ; and

(O-2) A polyethylene resin composition comprising 10 to 30% by weight of high-pressure low-density polyethylene having an MFR of 0.01 to 20 g/10 min. The total amount of the above-mentioned copolymer (O-1) and high-pressure low-density polyethylene (O-2) is 100% by weight. (O-1) If it exists in the said range, since film strength will improve, it is preferable. (O-2) Since the heat-sealing strength of a film will improve that it exists in the said range, it is preferable.

(O-1)

The MFR of the ethylene-α-olefin copolymer (O-1) is 0.1 to 100 g/10 min, preferably 0.5 to 50 g/10 min. When MFR is in the said range, it is preferable at the point that the intensity|strength and extrusion processability of the film for packaging are favorable. (O-1) has a density of 0.90 to 0.95 g/cm ³ , preferably 0.91 to 0.94 g/cm ³ . When the density is within the above-mentioned range, the rigidity, flexibility and strength of the film for packaging are improved, so it is preferable.

(O-2)

The MFR of the high-pressure low-density polyethylene (O-2) used in the outer layer is 0.01-20 g/10 min, preferably 0.3-5 g/10 min. If it is 0.01 g/10 min or more, the compatibility with (O-1) is high, so it is preferable, and if it is 20 g/10 min or less, it is preferable at the point that the stability of bubbles during molding is good.

The density of (O-2) is not particularly specified, but is preferably 0.917 to 0.930 g/cm ³ , more preferably 0.910 to 0.925 g/cm ³ . If the density is at least 0.917 g/cm ³ , it is preferable in terms of improving the rigidity and flexibility of the packaging film, and if it is at most 0.930 g/cm ³ , it is preferable in terms of increasing the strength of the packaging film.

(LL-1)

Furthermore, the above-mentioned ethylene-α-olefin copolymer (O-1) is preferably composed of two kinds of ethylene-α-olefin copolymers (LL-1) and (LL-2). When the whole (O-1) is 100% by weight, (LL-1) is 20 to 80% by weight, and (LL-2) is 20 to 80% by weight. Preferably (LL-1) is 55 to 75% by weight, and (LL-2) is 25 to 45% by weight.

The MFR of the copolymer (LL-1) is 0.1 to 10 g/10 min, preferably 0.2 to 5 g/10 min, more preferably 0.4 to 1 g/10 min. If the MFR is 0.1 g/10 min or more, it is preferable in terms of extrusion processability, and if it is 10 g/10 min or less, the strength and heat resistance of the packaging film and the stability of bubbles during molding are good. above is preferred.

The density of the copolymer (LL-1) is 0.88 to 0.93 g/cm ³ , preferably 0.91 to 0.92 g/cm ³ , more preferably 0.913 to 0.918 g/cm ³ . If the density is at least 0.88 g/cm ³ , it is preferable to improve the rigidity and flexibility of the packaging film, and if it is at most 0.93 g/cm ³ , it is preferable to improve the heat sealability of the packaging film.

(LL-2)

The MFR of the copolymer (LL-2) is 2 to 100 g/10 min, preferably 2 to 80 g/10 min. If the MFR is 2 g/10 min or more, it is preferable in terms of good extrusion processability, and if it is 100 g/10 min or less, it is preferable in terms of good strength of the film for packaging.

The density of the copolymer (LL-2) is 0.93 to 0.97 g/cm ³ , preferably 0.925 to 0.950 g/cm ³ , more preferably 0.935 to 0.945 g/cm ³ . If the density is at least 0.93 g/cm ³ , it is preferable to increase the rigidity and flexibility of the packaging film, and if it is at most 0.97 g/cm ³ , it is preferable to increase the strength of the packaging film.

When (O-1) is composed of ethylene-α-olefin copolymers (LL-1) and (LL-2), the content of (LL-1) is 20 to 60% by weight relative to the entire outer layer, and (LL- The content of 2) is 25 to 40% by weight, and the content of high-pressure low-density polyethylene (O-2) is 10 to 55% by weight. However, the total amount of the above-mentioned copolymer (LL-1), the above-mentioned copolymer (LL-2), and high-pressure-processed low-density polyethylene (O-2) is 100% by weight.

When the content of the copolymer (LL-1) used in the outer layer is less than 20% by weight, the strength of the packaging film may decrease, and when it exceeds 60% by weight, the extrusion load of the polyethylene resin composition used in the inner layer may increase, The gloss of the packaging film decreases.

When the content of the copolymer (LL-2) is less than 25% by weight, the rigidity and flexibility of the packaging film may decrease, and when it exceeds 40% by weight, the strength of the packaging film may decrease.

The content of the high-pressure low-density polyethylene (O-2) is preferably 15 to 60% by weight. When the O-2 content is less than 10% by weight, the gloss of the packaging film sometimes decreases. In addition, when the polyethylene resin composition used for the inner layer is molded, the bubbles are sometimes unstable. When it exceeds 60% by weight, the strength of the packaging film Sometimes lower.

(copolymer)

The ethylene-α-olefin copolymer (LL-1) and ethylene-α-olefin copolymer (LL-3) that can be used in the present invention are preferably ethylene and carbon atoms having 4 to 12 carbon atoms using a metallocene catalyst. Ethylene-α-olefin copolymer obtained by copolymerizing α-olefin. Ethylene-α-olefin copolymer (LL-2) and ethylene-α-olefin copolymer (LL-4) use metallocene catalysts or Ziegler-Natta catalysts to make ethylene and carbon atoms of 4 to 12 Ethylene-α-olefin copolymer obtained by copolymerizing α-olefin.

The copolymer (LL-1) and the copolymer (LL-2) can also be produced by copolymerizing ethylene and an α-olefin to produce the copolymer (LL-1), and then continuously copolymerizing ethylene and an α-olefin to produce a copolymer (LL-2) A substance obtained by such a method. In addition, the α-olefin used for the production of the copolymer (LL-1) and the α-olefin used for the production of the copolymer (LL-2) may be the same or different. In addition, the copolymer (LL-1) and the copolymer (LL-2) may be obtained by melt-kneading the polymer (LL-1) and the copolymer (LL-2) produced separately by copolymerization with an extruder. obtained substance.

The copolymer (LL-3) and the copolymer (LL-4) can also be produced by copolymerizing ethylene and α-olefin to produce the copolymer (LL-3), and then continuously copolymerizing ethylene and α-olefin to produce the copolymer (LL-4) A substance obtained by such a method. In addition, the α-olefin used for the production of the copolymer (LL-3) and the α-olefin used for the production of the copolymer (LL-4) may be the same as or different from each other.

In addition, the copolymer (LL-3) and the copolymer (LL-4) may be obtained by melt-kneading the separately copolymerized polymer (LL-3) and the copolymer (LL-4) with an extruder. obtained substance.

Examples of α-olefins having 4 to 12 carbon atoms include butene-1, pentene-1, hexene-1, heptene-1, octene-1, nonene-1, and decene. -1, dodecene-1, 4-methyl-pentene-1, 4-methyl-hexene-1, etc., preferably hexene-1, 4-methyl-pentene-1, octene- 1. In addition, the above-mentioned α-olefins having 4 to 12 carbon atoms may be used alone or in combination of at least two kinds.

As the copolymer (LL-1), copolymer (LL-2), copolymer (LL-3) and copolymer (LL-4) of ethylene-α-olefin copolymers, for example, ethylene-butylene ethylene-1 copolymer, ethylene-4-methyl-pentene-1 copolymer, ethylene-hexene-1 copolymer, ethylene-octene-1 copolymer, preferably ethylene-hexene-1 copolymer, ethylene - 4-methyl-pentene-1 copolymer, ethylene-octene-1 copolymer, more preferably ethylene-hexene-1 copolymer.

The ethylene-α-olefin copolymer [(LL-1)～(LL-4)] used in the present invention is to use metallocene catalyst or Ziegler-Natta catalyst, utilize solution polymerization method, slurry polymerization method, high pressure It is obtained by polymerizing ethylene and the above-mentioned α-olefin by ion polymerization or gas phase polymerization.

(aggregation method)

The ethylene-α-olefin copolymer (LL-1) and ethylene-α-olefin copolymer (LL-3) used in the present invention are polymers obtained by using a metallocene catalyst. As the metallocene catalyst used, preferably A catalyst containing a transition metal compound having a cyclopentadiene-shaped anionic skeleton group. The so-called transition metal compound having a group that is a cyclopentadiene-shaped anion skeleton refers to a metallocene compound, for example, with the formula MLaX(n-a) (wherein, M is the 4th group of the periodic table of elements or a lanthanide transition metal atom; L is a group with a cyclopentadiene-shaped anion skeleton or a heteroatom-containing group, at least one of which is a group with a cyclopentadiene-shaped anion skeleton; multiple Ls can be crosslinked with each other; X is a halogen atom, hydrogen or carbon A hydrocarbon group with an atomic number of 1 to 20; n represents the atomic valence of an overplated metal atom, and a is an integer of 0<a≤n), which can be used alone or in combination of at least two.

Furthermore, the above-mentioned metallocene compounds, with organic aluminum compounds such as triethylaluminum and triisobutylaluminum, aluminum tetrahydrofuran compounds such as methylaluminumoxane (Methylalumoxane), and/or trityl tetrapentafluoro Combination of ionic compounds such as phenyl borate and N,N-dimethylaniline tetrapentafluorophenyl borate is used.

In addition, the above-mentioned metallocene catalyst may be an inorganic polymer catalyst in which the above-mentioned metallocene compound, organoaluminum compound, and aluminum tetrahydrofuran compound and/or ionic compound are supported or impregnated on SiO ₂ , AI ₂ O ₃ , etc. Catalysts formed in material carriers or particulate organic polymer carriers such as polyethylene and polystyrene.

Examples of the ethylene-α-olefin copolymer obtained by polymerization using the metallocene catalyst include, for example, the ethylene-α-olefin copolymer described in JP-A-9-183816.

Examples of the method for producing the ethylene-α-olefin copolymer (LL-2) and the ethylene-α-olefin copolymer (LL-4) used in the present invention include methods using the above-mentioned metallocenes. In addition, a method of polymerizing ethylene and an α-olefin using a Ziegler-Natta catalyst in the presence or absence of a solvent, and in a gas phase-solid phase, a liquid phase-solid phase, or a homogeneous liquid phase is also exemplified. . The polymerization temperature is usually 30 to 300°C, and the polymerization pressure is usually normal pressure to 3000kg/cm ² .

The manufacturing method of the high-pressure low-density polyethylene (I-2), (O-2) and (M-3) used in the present invention is to use a tank reactor or a tubular reactor, in the presence of a free radical generator A method of polymerizing ethylene under the conditions of a polymerization pressure of 1400-3000kg/cm ² and a polymerization temperature of 200-300°C. In addition, the melt index can be adjusted by using hydrocarbons such as hydrogen, methane, and ethane as molecular weight regulators.

The manufacturing method of the high-density polyethylene (M-2) used in the present invention is to use Ziegler-Natta catalyst, in the presence or absence of solvent, and in gas phase-solid phase, liquid phase-solid phase or uniform A method of polymerizing ethylene and ethylene-α-olefins having 3 to 18 carbon atoms in a liquid phase. The polymerization temperature is usually 30 to 300°C, and the polymerization pressure is usually normal pressure to 3000kg/cm ² . Moreover, as high-density polyethylene, you may select from a commercial item.

(Manufacturing method)

The method for producing the respective polyethylene resin compositions used in the inner layer, intermediate layer, and outer layer of the packaging film of the present invention includes a method of granulating and dry-blending each component of the polyethylene resin composition, Alternatively, a method of melt mixing. Various mixers such as Henschel mixer and drum mixer can be used for dry mixing, and various mixers for single-screw extruder, twin-screw extruder, Banbury mixer, and hot roll can be used for melt mixing. . In addition, as a manufacturing method of the polyethylene-type resin composition used in this invention, the following preferable manufacturing methods are mentioned, for example.

(1) Using one polymerizer, divide the reaction conditions into two or more conditions, continuously polymerize ethylene-α-olefin copolymer LL-1~4 and high-density polyethylene, and then mix high-pressure low-density polyethylene method.

(2) A method of polymerizing each component with a plurality of polymerizers using a multistage polymerization process to finally obtain the polyethylene-based resin composition of the present invention.

(3) A method in which arbitrary two components among the components are produced by multistage polymerization, and then the remaining two components are mixed.

In the ethylene-α-olefin copolymer (LL-1) and the ethylene-α-olefin copolymer (LL-2), the α-olefins may be the same α-olefin or different α-olefins. Also, in the ethylene-α-olefin copolymer (LL-3) and the ethylene-α-olefin copolymer (LL-4), the α-olefins may be the same α-olefin or different α-olefins. olefins. When kneading ethylene-α-olefin copolymer (LL-1) and ethylene-α-olefin copolymer (LL-2), or kneading ethylene-α-olefin copolymer (LL-3) and ethylene-α- In the case of olefin copolymer (LL-4), as a kneading method, in order to obtain a packaging film with excellent appearance and strength, it is preferable to use twin-screw extrusion from the viewpoint of preventing resin from protruding and uniformly dispersing The mixing method of the mixer.

The respective polyethylene resin compositions used for the inner layer, intermediate layer, and outer layer of the packaging film of the present invention are formed into a multilayer film using a film blowing manufacturing device, a T-type cast film device, etc., and used as a packaging film. .

In the packaging film of the present invention, the respective thickness ratios of the inner layer, the middle layer, and the outer layer are usually 1/1/1 to 1/4/1 from the viewpoint of obtaining sufficient rigidity and sufficient heat-sealing strength. 1, preferably 1/1/1 to 1/3/1. In the packaging film of the present invention, the overall density of the film is preferably more than 0.93. When the density is within the above range, the mechanical physical properties are good, so it is preferable.

Resins other than the resin used in the present invention may be blended, if necessary, into the respective polyethylene resin compositions used for the inner layer, intermediate layer, and outer layer of the packaging film of the present invention. For example, polyolefin-based resins such as low-density elastomers may be blended in order to improve impact strength.

In the respective polyethylene resin compositions used in the inner layer, middle layer, and outer layer of the packaging film of the present invention, 2,6-di-tert-butyl-p-cresol (BHT), tetrakis[ Methylene-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]methane (trade name: IRGANOX1010) or n-octadecyl-3-(4'-hydroxyl-3, Phenol stabilizers such as 5'-di-tert-butylphenyl)propionate (trade name: IRGANOX1076), bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphate and tris(2 , phosphate-based stabilizers represented by 4-di-tert-butylphenyl) phosphate, etc., difunctional stabilizers such as Sumilizer GP, lubricants represented by higher fatty acid amides or higher fatty acid esters, etc. Glycerin esters or sorbitan esters of fatty acids with a number of 8 to 22, alkyl dialkanolamides of fatty acids with a carbon number of 8 to 22, antistatic agents such as polyethylene glycol esters, stearic acid Typical processability improvers such as calcium fatty acid metal salts, and pigments such as titanium oxide.

Additives such as resins such as low-density elastomers, antioxidants, anti-blocking agents, lubricants, and workability improvers formulated for various purposes can be melt-kneaded in advance on the inner layer, middle layer, and The respective polyethylene resin compositions used for the outer layer may be dry-blended separately, or may be dry-blended after serving as at least one main batch.

The packaging film of the present invention can be suitably subjected to surface treatment such as corona treatment for printing, and the treated surface after secondary processing such as surface treatment has excellent heat sealing performance and high strength can be obtained.

The packaging film of the present invention is particularly suitable for packaging films such as disposable diapers and sanitary products, which are hygienic products.

(Example)

Hereinafter, the present invention will be described in more detail using examples and comparative examples, but the aspects of the present invention are not limited to these examples. Evaluation was performed by the following method.

(1) Density: After heat-treating the extrudate (single filament) at 120°C for 2 hours at the time of MFR measurement, and slowly cooling it to room temperature for 1 hour, measure it with a density gradient tube according to the method specified in JIS K7112 .

(2) Follow the method specified in JIS K6760 for melt index (MFR, unit: g/10min). The load weight was 2.16 kg, and the temperature was 190°C.

(3) Gloss (unit: %)

Follow the method specified in ASTM D1003. Measure the outside of the tube with a reflection angle of 20°. The higher the value, the better the gloss.

(4) Tensile test

A dumbbell-shaped test piece of the size specified in JIS K6781 is punched out from the film, the distance between the clamps is 86mm, and the tensile speed is 200mm/min, and the tensile test is carried out, and the tensile test is performed at a tensile speed of 500mm/min. Tensile strength (unit: MPa) and elongation (unit: %) at break.

(5) Elastic rate (unit: MPa)

A dumbbell-shaped test piece of the size specified in JIS K6781 is punched out from the film, the distance between the clamps is 86mm, the tensile speed is 200mm/min, and the tensile test is carried out to obtain the slope of the initial stress relative to the displacement, as the elasticity Rate.

(6) Elmendorf (Elmendorf) tear strength (unit: kN/m)

Measured according to ASTM D1922.

(7) Dart-shaped drop hammer impact (unit: N)

Measured according to ASTM 1709A method.

(8) Heat seal strength (unit: N/15mm)

Films sealed at various temperatures using a heat-sealing machine, or a 15 mm-wide test piece taken from a sealed film product, were used to obtain a tensile load (200 mm/min) of 180° using a tensile tester. The peel strength of the heat-sealed part.

Table 1 shows the physical properties of the ethylene-α-olefin copolymer component (A), low-density polyethylene (B) and high-density polyethylene (C) obtained by high-pressure radical polymerization.

(Table 1)

MFR[g/10min] Density [g/cm³] A1 0.5 0.904 Ethylene-hexene-1 copolymer manufactured by Sumitomo Mitsui Polyrefin Co., Ltd. (trade name: Eboriyuichi) A2 0.5 0.913 Ethylene-hexene-1 copolymer manufactured by Sumitomo Mitsui Polyrefin Co., Ltd. (trade name: Eboriyuichi) A3 5 0.940 Ethylene-hexene-1 copolymer manufactured by Sumitomo Mitsui Polyrefin Co., Ltd. (trade name: Eboriyuichi) 4A4 50 0.945 Ethylene-hexene-1 copolymer manufactured by Sumitomo Mitsui Polyrefin Co., Ltd. (trade name: Eboriyuichi) A5 60 0.930 Ethylene-hexene-1 copolymer manufactured by Sumitomo Mitsui Polyrefin Co., Ltd. (trade name: Eboriyuichi) A6 1 0.920 Ethylene-butene-1 copolymer manufactured by Nippon Polychem Co., Ltd. B1 0.5 0.923 Sumitomo Mitsui Polyrefin Co., Ltd. high-pressure-processed low-density polyethylene (trade name: Sumikasen) B2 0.6 0.922 Sumitomo Mitsui Polyrefin Co., Ltd. high-pressure-processed low-density polyethylene (trade name: Sumikasen) B3 1.1 0.923 Sumitomo Mitsui Polyrefin Co., Ltd. high-pressure-processed low-density polyethylene (trade name: Sumikasen) C1 0.1 0.956 Sumitomo Mitsui Polyrefin Co., Ltd. high-density polyethylene (trade name: ハイゼツクス) C2 1 0.947 Sumitomo Mitsui Polyrefin Co., Ltd. high-density polyethylene (trade name: ハイゼツクス) C3 5 0.960 Sumitomo Mitsui Polyrefin Co., Ltd. high-density polyethylene (trade name: ハイゼツクス) C4 0.35 0.955 Sumitomo Mitsui Polyrefin Co., Ltd. high-density polyethylene (trade name: ハイゼツクス) C5 0.03 0.947 Sumitomo Mitsui Polyrefin Co., Ltd. high-density polyethylene (trade name: ハイゼツクス)

(Embodiments 1-5)

-缝隙2.0mm，料筒温度为190℃，模具温度为200℃，膨胀比为2.0，牵引速度为30m/min，厚度结构比率：内层/中间层/外层＝1/2/1，加工厚度为50μm的膜。所得到的膜的组成、物理特性以及评价结果在表2中表示。Using a 3-layer film blowing processing machine, Extruder x3, mold

- Gap 2.0mm, barrel temperature 190°C, mold temperature 200°C, expansion ratio 2.0, traction speed 30m/min, thickness structure ratio: inner layer/middle layer/outer layer = 1/2/1, processing Film with a thickness of 50 μm. Table 2 shows the composition, physical properties, and evaluation results of the obtained film.

As the intermediate layer (M-1) component, a mixture of A1/A3=65/35 (weight ratio) was used. As the inner layer (I-1) component, in Example 1 and Example 5, a mixture of A2/A4=60/40 (weight ratio) was used, and in Examples 2-4, A2/A5= 60/40 (by weight) mixture. As the outer layer (O-1) component, in Examples 1, 2 and 5, a mixture of A2/A4=60/40 (weight ratio) was used, and in Examples 3 and 4, A2/A5= 60/40 (by weight) mixture.

In the inner layer, 0.4 parts by weight of aluminum silicate as an anti-blocking agent and 0.2 parts by weight of erucamide as a lubricant were added to 100 parts by weight of the inner layer, and in the outer layer, 0.2 parts by weight of erucamide was added to 100 parts by weight of the outer layer. 0.2 parts by weight of aluminum silicate as an anti-blocking agent, and 0.04 parts by weight of erucamide as a lubricant. The density of each layer of the film is obtained by multiplying the density of each polymer used by the weight fraction. The full-layer density of the film was calculated by multiplying the density of each layer by the thickness ratio.

(Comparative examples 1 to 4)

Using the processing equipment of Example 1, set the thickness structure ratio as inner layer/middle layer/outer layer=1/1/1, obtain a kind of three-layer film made of the same resin composition for all three layers, and change the thickness , Except that, the processing conditions were the same as in Example 1. With respect to 100 parts by weight of the film, 0.4 parts by weight of aluminum silicate as an antiblocking agent and 0.07 parts by weight of erucamide as a lubricant were added.

As (M-1), (I-1) and (O-1) component, in comparative example 1 and 2, used the mixture of A2/A4=60/40 (weight ratio), in comparative example 3, A6 was used, and in Comparative Example 4, a mixture of A1/A3=65/35 (weight ratio) was used. Table 3 shows the composition, physical properties and evaluation results of the obtained film.

The density of each layer and the whole layer of the film was obtained by the same method as in Example 1.

Comparative Examples 1, 2, and 4 in which the intermediate layer did not satisfy the composition of the present invention were inferior in heat-sealing strength compared with Examples. In addition, Comparative Example 3, which also did not satisfy the composition of the present invention, was inferior in gloss and tear strength compared to Examples.

(Table 2)

unit Example 1 Example 2 Example 3 Example 4 Example 5 Inner composition weight% A2＝51A4＝34B1＝15 A2＝51A5＝34B1＝15 A2＝51A5＝34B1＝15 A2＝26A5＝17B1＝57 A2＝46A4＝30B1＝14B4＝10 (i-1) Composition (i-1) Density (i-1) MFR (LL-1)/(LL-2)[kg/m3][g/10min] 60/409202.5 60/409202.6 60/409202.6 60/409202.6 60/409362.5 The total density of the inner layer [kg/m3] 925 920 920 921 925 Inner MFR [g/10min] 1.9 1.9 1.9 1.0 1.9 middle layer composition % by weight (Note) A1＝42A3＝23B2＝15C1＝20 A1＝21A3＝12B2＝7C1＝10C2＝50 A1＝21A3＝12B2＝7C1＝10C3＝50W-MB＝5 A1＝21A3＝12B2＝7C1＝60W-MB＝5 A1＝19A3＝10C1＝9B2＝7C4＝55W-MB＝5 (M-1) Composition (M-1) Density (M-1) MFR (LL-3)/(LL-4)[kg/m3][g/10min] 65/359161.4 65/359161.4 65/359161.4 65/359161.4 65/359161.4 Middle layer density [kg/m3] 926 937 943 941 938 Middle layer MFR [g/10min] 0.9 1.0 2.1 0.33 0.5 Outer layer composition weight% A2＝51A4＝34B1＝15 A2＝51A4＝34B1＝15 A2＝51A5＝34B1＝15 A2＝51A5＝34B1＝15 A2＝46A4＝30B1＝14B4＝10 (O-1) Composition (O-1) Density (O-1) MFR (LL-1)/(LL-2)[kg/m3][g/10min] 60/409262.5 60/409262.5 60/409202.6 60/409202.6 60/409262.5 outer layer density [kg/m3] 925 925 920 920 925 Outer MFR [g/10min] 1.9 1.9 1.9 1.9 1.9 Full layer density [kg/m3] 926 931 931 931 931 Gloss % 93 93 43 51 32 elastic rate MPa MDTD 550700 590760 640580 560710 7201000 Tensile breaking strength MPa MDTD 4851 4847 4240 3940 4920 Tensile elongation at break point % MDTD 480740 580760 580760 480720 440720 tear strength kN/mMDTD 27270 38230 43280 28290 19340 dart impact N 3.0 2.1 2.0 1.7 1.2 Heat seal strength N/15mm130℃N/15mm135℃N/15mm140℃ 121516 141515 151515 151717 172019

(Note) W-MB: white pigment 60% by weight concentration

5 parts by weight of W-MB were added to 100 parts by weight of the polymer in total.

(table 3)

(Note) W-MB: white pigment 60% by weight concentration

5 parts by weight of W-MB were added to 100 parts by weight of polymers in total.

Industrial availability

According to the present invention, it is possible to obtain a thin and strong packaging film that is excellent in heat-sealing strength and glossiness, and also excellent in rigidity, flexibility, and impact strength.

Claims (5)

1. film for packaging is characterized in that: have following internal layer, intermediate layer and outer three layers at least, the intermediate layer is between internal layer and skin, and they are made of following composition,

The intermediate layer is by containing

M-1:MFR is that 0.1～100g/10min, density are 0.90～0.940g/cm ³Ethene-alpha-olefin copolymer 20～75 weight %,

M-2:MFR is that 0.001～50g/10min, density are 0.942～0.97g/cm ³High density polyethylene (HDPE) 20～70 weight % and

M-3:MFR is the layer that the polyethylene resin composition of high-pressure process low density polyethylene (LDPE) 5～20 weight % of 0.01～20g/10min constitutes, wherein, the total amount of described copolymer M-1, high density polyethylene (HDPE) M-2 and high-pressure process low density polyethylene (LDPE) M-3 is 100 weight %;

Internal layer and skin are made of polyvinyl resin or resin combination respectively, this polyvinyl resin or resin combination, and MFR is in the scope of 0.01～20g/10nin, and density is at 0.90～0.95g/cm ³Scope in, internal layer and outer field resin or resin combination can be identical, also can be different.

2. film for packaging as claimed in claim 1 is characterized in that:

Described internal layer is by containing

I-1:MFR is that 0.1～100g/10min, density are 0.90～0.95g/cm ³Ethene-0-olefin copolymer 45～90 weight % and

I-2:MFR is that the polyethylene resin composition of high-pressure process low density polyethylene (LDPE) 10～55 weight % of 0.01～20g/10min constitutes, and wherein, the total amount of described copolymer I-1 and high-pressure process low density polyethylene (LDPE) I-2 is 100 weight %;

And described skin is by containing

O-1:MFR is that 0.1～100g/10min, density are 0.90～0.95g/cm ³Ethene-alpha-olefin copolymer 70～90 weight % and

O-2:MFR is that the polyethylene resin composition of high-pressure process low density polyethylene (LDPE) 10～30 weight % of 0.01～20g/10min constitutes, and wherein, the total amount of described copolymer O-1 and high-pressure process low density polyethylene (LDPE) O-2 is 100 weight %.

3. film for packaging as claimed in claim 1 is characterized in that:

The ethene-alpha-olefin copolymer composition M-1 in described intermediate layer is made of following LL-3 and LL-4,

LL-3:MFR is that 0.1～2g/10min, density are greater than 0.88g/cm ³Less than 0.93g/cm ³Ethene-alpha-olefin copolymer 20～80 weight %,

LL-4:MFR is that 2～100g/10min, density are 0.93～0.97g/cm ³Ethene-alpha-olefin copolymer 20～80 weight %,

Wherein, the total amount of LL-3 and LL-4 is 100 weight %.

4. film for packaging as claimed in claim 2 is characterized in that:

The ethene-alpha-olefin copolymer I-1 of described internal layer and described outer field ethene-alpha-olefin copolymer O-1 are made of following LL-1 and LL-2,

LL-1:MFR is that 0.1～10g/10min, density are greater than 0.88g/cm ³Less than 0.93g/cm ³Ethene-alpha-olefin copolymer 20～80 weight %,

LL-2:MFR is that 2～100g/10min, density are 0.93～0.97g/cm ³Ethene-alpha-olefin copolymer 20～80 weight %,

Wherein, the total amount of LL-1 and LL-2 is 100 weight %, and internal layer and outer field polymer composition can be the same or different.

5. a toilet article packaging film is characterized in that: be made of each described film for packaging in the claim 1～4.